tubewell energy audit

TUBEWELL ENERGY AUDIT MANUAL

NATIONAL ENERGY CONSERVATION CENTRE

ENERCON

Contents

1 INTRODUCTION ................................................................................................................. 1

1.1 Background .................................................................................................................................. 1

1.2 Water Requirement of Different Crops ............................................................................. 1 1.2.1 Kharif Crops ............................................................................................................................................................... 2 1.2.2 Rabbi crops ................................................................................................................................................................. 5

1.3 Ground Water in Pakistan ...................................................................................................... 7 1.3.1 Quantity ....................................................................................................................................................................... 7 1.3.2 Quality .......................................................................................................................................................................... 7

1.4 Tubewells in Pakistan .............................................................................................................. 7

1.5 Tubewell Energy Efficiency ................................................................................................... 8

1.6 Organization of the Manual ................................................................................................ 10

2 CENTRIFUGAL PUMP..................................................................................................... 11

2.1 Types of Pumping System ................................................................................................... 11 2.1.1 Horizontal Shaft Centrifugal Pump ............................................................................................................... 11 2.1.2 Turbine (Vertical Shaft) Pump ....................................................................................................................... 12 2.1.3 Submersible Pump ............................................................................................................................................... 12

2.2 Components of Centrifugal Pump .................................................................................... 13 2.2.1 Impeller ..................................................................................................................................................................... 14 2.2.2 Shaft ............................................................................................................................................................................ 14 2.2.3 Casing ......................................................................................................................................................................... 14

2.3 Pumping System Terminology .......................................................................................... 15 2.3.1 Head ............................................................................................................................................................................ 15 2.3.2 Static Head ............................................................................................................................................................... 16 2.3.3 Friction head (hf) .................................................................................................................................................. 17 2.3.4 Pump Performance Curve ................................................................................................................................. 17 2.3.5 Pump Suction Performance (NPSH) ............................................................................................................. 18 2.3.6 Best Efficiency Point ............................................................................................................................................ 22 2.3.7 Pump Curves for Multiple Impeller Sizes .................................................................................................. 23

2.4 Pump Speed Selection .......................................................................................................... 24

2.5 How to Select a Centrifugal Pump ................................................................................... 25

3 OPERATING CHARACTERISTICS OF TUBEWELL COMPONENTS .................... 27

ENERCON, The National Energy Conservation Centre

i

3.1 Well .............................................................................................................................................. 29 3.1.1 Parts of Tubewell ................................................................................................................................................. 29 3.1.2 Draw Down ............................................................................................................................................................. 30

3.2 Pumps ......................................................................................................................................... 31

3.3 Diesel Engines/Tractors ...................................................................................................... 35

3.4 Electric Motors ........................................................................................................................ 36

3.5 Transmission ........................................................................................................................... 38

3.6 Piping .......................................................................................................................................... 40

4 PERFORMANCE TESTING OF TUBEWELL COMPONENTS .................................. 43

4.1 Pumpset ..................................................................................................................................... 43

4.2 Diesel Engine............................................................................................................................ 45

4.3 Electric Motor .......................................................................................................................... 46 4.3.1 Load Test ................................................................................................................................................................. 46 4.3.2 Stator Resistance .................................................................................................................................................. 47 4.3.3 No Load Test ........................................................................................................................................................... 47

4.4 Transmission ........................................................................................................................... 47

4.5 Pump ........................................................................................................................................... 48

4.6 Piping System .......................................................................................................................... 49

4.7 Well .............................................................................................................................................. 49

5 INSTRUMENTSANDEQUIPMENT FORTUBEWELLENERGYAUDITS ........... 56

5.1 Water Flow Meter ................................................................................................................ 57

5.2 Pressure Module ..................................................................................................................... 58

5.3 Multimeter ................................................................................................................................ 58

5.4 Energy/Electric Power Analyzer ..................................................................................... 59

5.5 Tachometer............................................................................................................................... 59

5.6 Fuel Weighing System ................................................................................................... 60

5.7 Electric Well Sounder ......................................................................................................... 60


ii

5.8 Diesel Engine Compression Tester .................................................................................. 61

5.9 Smoke Tester/Flu Gas Analyzer .................................................................................... 61

5.10 Thermocouple Thermometer ............................................................................................ 62

5.11 Friction Torque Tester ......................................................................................................... 62

5.12 Tool Kit ....................................................................................................................................... 62

5.13 Accessories Kit ........................................................................................................................ 63

5.14 First Aid Kit ............................................................................................................................... 63

6 AUDIT METHODOLOGY ......................................................................................... 64

6.1 Calibration of Instruments ................................................................................................. 64

6.2 Audit Procedure ...................................................................................................................... 64 6.2.1 General Information: .................................................................................................................................. 64 6.2.2 Tube Well General Information ..................................................................................................................... 64 6.2.3 Safety Aspects .................................................................................................................................................... 64 6.2.4 Test Feasibility Review ............................................................................................................................... 65 6.2.5 Guidelines for Tube Well Energy Audit .......................................................................................... 65

6.3 Energy Audit Performa ........................................................................................................ 73

6.4 Manpower/Time Frame ...................................................................................................... 73

7 DATA ANALYSIS AND DIAGNOSIS OF TUBE WELL PROBLEMS ....................... 74

7.1 Calculations ........................................................................................................................... 74 7.1.1 Discharge .................................................................................................................................................................. 74 7.1.2 Head ............................................................................................................................................................................ 75 7.1.3 Water Power ....................................................................................................................................................... 78 7.1.4 Pump Set Efficiency ....................................................................................................................................... 78 7.1.5 Piping Efficiency .............................................................................................................................................. 78 7.1.6 Overall Efficiency ............................................................................................................................................ 79 7.1.7 Estimated Motor Efficiency .............................................................................................................................. 79 7.1.8 Estimated Engine Efficiency ............................................................................................................................ 79 7.1.9 Estimated Transmission Efficiency .............................................................................................................. 80 7.1.10 Estimated Pump Efficiency ......................................................................................................................... 80 7.1.11 Friction Loss in Stuffing Box ...................................................................................................................... 81 7.1.12 Voltage and Current Imbalance ................................................................................................................ 81

7.2 Diagnosis of Tube well Problems. .................................................................................... 81 7.2.1 Cavitation ................................................................................................................................................................. 82 7.2.2 Variations in Total System Head .................................................................................................................... 85 7.2.3 Diesel Engine ......................................................................................................................................................... 86


iii

7.2.4 Pump .......................................................................................................................................................................... 86 7.2.5 Transmission .......................................................................................................................................................... 86 7.2.6 Piping System ................................................................................................................................................... 86 7.2.7 Well ............................................................................................................................................................................ 87

7.3 Format for Audit Report ...................................................................................................... 87

8 BEST PRACTICES FOR ENERGY EFFICIENT IRRIGATION AND TRACTOR FUEL EFFICIENCY .................................................................................................................... 93

8.1 Crop and Irrigation System Water Requirements ..................................................... 93 8.1.1 Crop Evapotranspiration .................................................................................................................................. 93 8 . 1 . 2 Irrigation F r e q u e n c y ............................................................................................................................ 93 8.1.3 Net Irrigation Requirement ............................................................................................................................. 94 8.1.4 Gross Irrigation Requirement ......................................................................................................................... 94

8.2 Water Requirement of Different Crops.......................................................................... 95

8.3 Irrigation Methods ................................................................................................................. 96 8.3.1 Surface Irrigation ................................................................................................................................................. 96 8.3.2 High Efficiency Irrigation Systems (HEIS) ................................................................................................ 97

8.4 Tractor Fuel Efficiency ......................................................................................................... 99 8.4.1 Fuel Efficiency Factors for Tractor Selection ........................................................................................... 99 8.4.2 Proper Gear Selection ......................................................................................................................................... 99 8.4.3 Ballasting Tractors for Fuel Efficiency ......................................................................................................100 8.4.4 Tire Inflation .........................................................................................................................................................100 84.5 Tractor Maintenance to Conserve Energy...............................................................................................101 8.4.6 Efficient Soil Tillage Systems ........................................................................................................................101

ANNEX I : IRRIGATION PUMP SET EFFICIENCY IN DEVELOPING COUNTRIES – FIELD MEASUREMENTS IN PAKISTAN

ANNEX II : UNIT CONVERSION TABLE

ANNEX III : PUMP PERFORMANCE CURVES

ANNEX IV : EFFICIENCY OF DIFFERENT MOTOR CLASSES

ANNEX V : FRICTION LOSS DATA FOR DIFFERENT PIPE SIZES

ANNEX VI : FILLED TUBEWELL ENERGY AUDIT REPORTS


iv

Exhibits

Exhibit 1.1 Typical Field in Punjab Being Irrigated ......................................................................................................... 1 Exhibit 1.2: Typical Irrigated Rice Field in Pakistan ....................................................................................................... 2 Exhibit 1.3: A Maize Crop Near Okara Ready for Harvesting ...................................................................................... 2 Exhibit 1.4: Typical Irrigated Cotton Field in Punjab ...................................................................................................... 3 Exhibit 1.5: Furrow Irrigated Sugarcane Field .................................................................................................................. 4 Exhibit 1.6: Typical Wheat Field in Punjab (Pakistan) ................................................................................................... 5 Exhibit 1.7: Typical Tubewell in Punjab ............................................................................................................................... 7 Exhibit 2.1: Centrifugal Pump ................................................................................................................................................. 11 Exhibit 2.2Turbine Pump ......................................................................................................................................................... 12 Exhibit 2.3: Submersible Pump .............................................................................................................................................. 13 Exhibit 2.4: Components of Centrifugal Pumps .............................................................................................................. 13 Exhibit 2.5: Double Shroud Pump Impeller ...................................................................................................................... 14 Exhibit 2.6: Volute Casing ......................................................................................................................................................... 15 Exhibit 2.7: Pump Static Head ................................................................................................................................................ 16 Exhibit 2.8: Static Suction Head and Static Discharge Head ..................................................................................... 17 Exhibit 2.9: Pump Performance Curve ............................................................................................................................... 17 Exhibit 2.10: Pump Operating Point .................................................................................................................................... 17 Exhibit 2.11: Reason of Cavitation ........................................................................................................................................ 18 Exhibit 2.12: Available Net Pressure Suction Head (NPSH) ...................................................................................... 20 Exhibit 2.13: Pump Operation Point .................................................................................................................................... 22 Exhibit 2.14: Family of Pump Performance Curves ...................................................................................................... 23 Exhibit 2.15: Performance Curves for Different Impeller Sizes .............................................................................. 24 Exhibit 2.16: Pump Selection .................................................................................................................................................. 25 Exhibit 3.1: Energy Input-Output of a Diesel Engine Operated Pumping System ........................................... 28 Exhibit 3.2: Borehole of a Horizontal Shaft Tubewell .................................................................................................. 29 Exhibit 3.3: Parts of Tubewell ................................................................................................................................................ 29 Exhibit 3.4: Pump Draw Down ............................................................................................................................................... 30 Exhibit 3.5: Pump and Well Characteristic Curves........................................................................................................ 32 Exhibit 3.6: Characteristic Curve of Centrifugal Pump ................................................................................................ 33 Exhibit 3.7: Diesel Engine Performance Curves of Continuous Rated Power of 51 HP/38 kW ................ 36 Exhibit 3.8: Motor Efficiency Vs. Load Level .................................................................................................................... 38 Exhibit 4.1: Energy Input-Output and Efficiency of a Water Pumping System ................................................ 43 Exhibit 4.2: Total Dynamic Head- Horizontal Shaft Centrifugal Pump ................................................................ 51 Exhibit 4.3: Field Head – Deep Well Turbine Pump...................................................................................................... 52 Exhibit 4.4: Motor Efficiency vs Power Factor ................................................................................................................ 53 Exhibit 4.5: Observation Well to Measure Static and Pumping Water Levels for Uncased Well .............. 54 Exhibit 4.6: Pumping Situation Depicting No Well Problem ..................................................................................... 54 Exhibit 4.7: Pumping Situation Depicting Pump Installed at High Level Causing High Suction Lift ..... 54 Exhibit 4.8: Pumping Situation Depicting Plugged Strainer Causing High Suction Lift ........................ 55 Exhibit 5.1: Ultrasound Flow Meter ..................................................................................................................................... 57 Exhibit 5.2: Ultrasound Flow Meter Kit .............................................................................................................................. 57 Exhibit 5.3: Multimeter .............................................................................................................................................................. 58 Exhibit 5.4: Power Analyzer .................................................................................................................................................... 59 Exhibit 5.5: Tachometer ............................................................................................................................................................ 59 Exhibit 5.6: Fuel Weighing System ....................................................................................................................................... 60 Exhibit 5.7: Electric Well Sounder ........................................................................................................................................ 60 Exhibit 5.8: Diesel Engine Compression Tester .............................................................................................................. 61


v

Exhibit 5.9: Smoke Tester ........................................................................................................................................................ 61 Exhibit 5.10: Thermocouple Thermometer ..................................................................................................................... 62 Exhibit 5.11: First Aid Kit ......................................................................................................................................................... 63 Exhibit 6.1: Typical Name Plates of Motor and Pump ................................................................................................. 65 Exhibit 6.2: Typical Capacitor Bank of Electric Tubewell .......................................................................................... 66 Exhibit 6.3: Ultrasonic Flow Meter in Installed Position............................................................................................ 66 Exhibit 6.4: Power Analyzer Readings ............................................................................................................................... 66 Exhibit 6.5: Flow Meter Readings ......................................................................................................................................... 67 Exhibit 6.6: XY Method (Flow Trajectory Method) for Flow Measurement ...................................................... 67 Exhibit 6.7 : Scale in Position to take X Reading ............................................................................................................ 68 Exhibit 6.8: Free Zone Measurement .................................................................................................................................. 68 Exhibit 6.9: Electrical Readings ............................................................................................................................................. 69 Exhibit 6.10: Motor Speed Measurement .......................................................................................................................... 70 Exhibit 6.11: Motor Temperature Measurement ........................................................................................................... 70 Exhibit 6.12: Depth of Pump Installation .......................................................................................................................... 71 Exhibit 6.13: Length of Horizontal Line ............................................................................................................................. 72 Exhibit 6.14: Height above Ground ...................................................................................................................................... 72 Exhibit 6.15: Water Depth Measurement ......................................................................................................................... 72 Exhibit 8.1: Surface Irrigation ................................................................................................................................................ 97 Exhibit 8.2: Rain Gun System .................................................................................................................................................. 97 Exhibit 8.3: Centre Pivot System ........................................................................................................................................... 98 Exhibit 8.4: Drippers .................................................................................................................................................................. 98 Exhibit 8.5: Bubbler .................................................................................................................................................................... 98 Exhibit 8.6: Micro-tubes ............................................................................................................................................................ 99 Exhibit 8.7Impact of Tyre Inflation on Fuel Efficiency ..............................................................................................101


vi

Tables

Table 1.1:Water Requirement of Different Crops ............................................................................................................. 2 Table 1.2: Power Rating of Tubewells ................................................................................................................................... 8 Table 1.3: Utilization Pattern of Tubewells ......................................................................................................................... 8 Table 3.1: Recommended Well Case and Pumping Pipe Size for Various Flow Rates................................... 30 Table 3.2: Drawdown in Tubewells in the Indus Basin.............................................................................................. 31 Table 3.3: Typical NEMA B Design Motor, 10-20 hp; 85% Efficiency ................................................................... 37 Table 3.4: Effect of Voltage Variation on Induction Motor Performance ............................................................ 38 Table 3.5: Equivalent Length of Straight Pipe for Valves and Fittings (m) ........................................................ 41 Table 3.6: Increase in Friction Loss Due to Aging of Pipe .......................................................................................... 42 Table 4.1: Smoke Ratings as Per Bosch-Bacharak Smoke Test................................................................................ 45 Table 5.1: Instruments & Methods for Tubewell Energy Audit ............................................................................... 56 Table 7.1: Motor Efficiency Estimation .............................................................................................................................. 79 Table 7.2: Engine Efficiency Estimation ............................................................................................................................. 80 Table 7.3: Common Problems with Centrifugal Pumps and Their Causes ......................................................... 83 Table 8.1: Water Requirement of Different Crops under Various Irrigation Options ................................... 95


vii

1 INTRODUCTION

1.1 Background

Agriculture is a major sector of the economy of Pakistan as well as one of the major consumers of commercial energy. At present, irrigation pumps and farm tractors are large consumers of energy in the agriculture sector. It is very important that all segments of our economy, including agriculture, make the most efficient use of available energy resources.

1.2 Water Requirement of Different Crops

The agriculture of Pakistan is characterized by two main cropping seasons, namely, the Kharif (summer crops) from April to September; and Rabi (winter crops) from October to March. Wheat is the main crop of Rabi season, while rice, maize, sugarcane and cotton are considered the major crops of Kharif. Mono cropping, sequence cropping, mixed

cropping, inter-cropping and relay cropping systems are practiced by growers (farmers), especially those with small holdings, to maximize crop production per unit area. The cropping pattern is largely determined by water availability and the climatic conditions as adaptation of crops. Water requirement of different crops has been reproduced in the Table 1.1. Crop Water Requirement (Under Flood Irrigation) Acre Inches Cubic Meter Liters Wheat 16 1,645 1,644,000 Cotton 22 2,262 2,261,600 Maize (Autumn) 13 1,336 1,336,400

Exhibit 1.1 Typical Field in Punjab Being Irrigated


1

Maize (Spring) 20 2,056 2,056,400 Sugarcane 64 6,579 6,579,200 Rice 64 6,579 6,579,200

Table 1.1:Water Requirement of Different Crops

1.2.1 Kharif Crops

1.2.1.1 Rice

Rice is one of the leading cash and foreign exchange earning food crops of the world, including Pakistan. It requires a constant and plentiful supply of irrigation water. It needs 46 acre inches as soaking dose 4-6 days before transplanting, 1-2 acre inches at the time of transplanting and 3-4 acre inches 7-10 days after transplanting to maturity of the crop. The reproductive stages from penicle initiation to flowering and grain formation are the critical stages. Any stress at this stage will affect the yield and grain quality. However, rice requires over all 60-70 acre inches irrigation water on the basis of varieties.

1.2.1.2 Maize

Maize is also one of the cereal crops. It is very efficient water user. It needs large quantities of irrigation water for high yield, because drought conditions lead to lower yields and lower quality grains. Maize requires 6-8 irrigations. First irrigation 3-4 weeks after sowing, remaining may be given at 10-15 days interval. The grain formation is critical growth stage. It is not important grain crop in Sindh, but is grown mostly as fodder crop and very rare as for grain.

Exhibit 1.2: Typical Irrigated Rice Field in Pakistan

Exhibit 1.3: A Maize Crop Near Okara Ready for Harvesting


2

1.2.1.3 Sorghum (Jowar)

The major area of sorghum in Pakistan lies in Punjab, but the yield per hectare is higher in Sindh. The sorghum plants are drought resistant, but 3-4 irrigations (30-35,50-60 and 70- 80 days after sowing) are compulsory for better yield.

1.2.1.4 Millet (Bajra)

The area under millet crop is highly variable, because it is dependent on the amount and time of the rainfall. It is mostly confined to the desert and mountain (Thar, Cholistan and Kohistan) area. 3-4 irrigations are sufficient for better yield, as recommended for sorghum.

1.2.1.5 Mungbean (Green gram)/Mash (Black gram)/Arhar (Pigeonpea or Red gram)

It does not require much irrigation due to short duration and drought tolerant crop. However, 3-4 irrigations are sufficient for getting good yield. Flowering and seed development stages are very critical.

1.2.1.6 Cowpea

This crop is grown as pulse, vegetable, fodder and green manure crop, hence is of economic importance, especially in Sindh. Irrigation requirements are same as of mungbean crop.

1.2.1.7 Cotton

Cotton is alone fiber crop of Pakistan. It is also most important cash and foreign exchange earning crop. It requires 7-8 irrigations (at least 80 cm) to get an acceptable yield. The first irrigation is to be given 35-40 days after sowing (DAS) and subsequent irrigations should be applied at 15 days interval. The most critical stages for irrigation are early flowering to first boll opening and maturity.

1.2.1.8 Sunflower

Sunflower has gained higher popularity and acreage, among the new oilseed crops introduced for boosting edible oil production. The important features of this crop are short growing period, high yield potential and wide

Exhibit 1.4: Typical Irrigated Cotton Field in Punjab


3

range of growing season viz. autumn, spring and winter. It fits well in different cropping patterns, low irrigation water requirements, wide adaptability to soil and moisture conditions. Its seed contains high oil (over 40%) of good edible quality and meal of good quality free from toxic compounds. 3 irrigations are necessary. The 1st irrigation should be given 30-35 DAS, 2nd at start of flowering and 3rd just after petal fall.

1.2.1.9 Sugarcane

Sugarcane is also one of the major crops. The highest acreage is in Punjab but yield is higher in Sindh. The crop requires 30-33 irrigations at 15 days interval during winter and weekly in summer (a total of 96 acre inches).

1.2.1.10 Soybean

It requires 5-7 irrigations from sowing to maturity. Irrigation at pod filling stage is very necessary, drought at this stage will reduce yield drastically.

1.2.1.11 Groundnut (Peanut)

This crop requires 30 acre inches during 5-7 irrigations. The first irrigation should be given 25-30 DAS and subsequent at 15-20 days intervals. The critical stage is seed development.

1.2.1.12 Sesame

The sesame is cultivated throughout Pakistan as irrigated as well as un-irrigated crop. It requires 3-4 (21 acre inches) irrigation at 30 days interval.

1.2.1.13 Caster

Caster is grown under arid conditions, mostly as rainfed crop. Under irrigated conditions, it needs 5-7 (20 acre inches) irrigation at 30 days interval.

1.2.1.14 Guar (Cluster bean)

It is a very important drought resistant Kharif legume of Barani and irrigated areas. However, if irrigation is available, then 20-25 cm per hectare, in the course of 2-3 irrigations increase the yield.

Exhibit 1.5: Furrow Irrigated Sugarcane Field


4

1.2.1.15 Moth

Moth is also important drought tolerant crop, cultivated as rainfed. Irrigated crop requires 2-4 irrigations.

1.2.1.16 Sesbania (Janter or Danicha)

This crop is widely grown in all over Pakistan as main Kharif fodder and as green manure crop. It adds about 80 kg/ha nitrogen in the soil, therefore also used as rotation crop for maintaining the soil fertility. This crop requires 4-6 irrigations. First 2-3 irrigations at weekly and following should be applied fortnightly.

1.2.2 Rabbi crops

1.2.2.1 Wheat

Wheat is a staple food of more than one third of the world population. The major area in Pakistan lies in Punjab, but the yield per hectare is slightly higher in Sindh. 5-6 irrigations (21 acre inches) are sufficient, for normal wheat crop, under optimum soil conditions. First irrigation should be given 3-4 weeks after sowing. Out of all stages, crown root initiation (CRI) is the most important stage for irrigation, in view of nutrient availability and root development. Other critical stages are tillering, heading, milky and dough 21, 50, 80 and 100 days after sowing (DAS) respectively.

1.2.2.2 Barley

Barley is drought tolerant crop. It does not require much irrigation. However, 3-4 irrigations are recommended for maximum yield per unit area. First irrigation is to be given at 35 DAS. The irrigation at actively tillering increases the yield.

1.2.2.3 Gram (Chickpea)

About 81% of gram area in Pakistan lies in Punjab followed by NWFP and Sindh, but the yield is highest in Sindh. No irrigation is required if planted after rice as Dobari crop. In

Exhibit 1.6: Typical Wheat Field in Punjab (Pakistan)


5

case of irrigated crop, only one irrigation is required at pre-flowering stage. Heavy pre-sowing irrigation is better than light pre-sowing irrigation.

1.2.2.4 Lentil (Masoor)

One irrigation at pre-flowering is adequate, but in light soil, it requires two irrigations. However, no irrigation is required for Dobari or Bosi crop.

1.2.2.5 Grasspea (Matter)

Two irrigations are sufficient under irrigated conditions, but no irrigation is required for Dobari or Bosi crop.

1.2.2.6 Rapeseed and Mustard

3-4 irrigations may be given to Toria and Sarsoon, 1-2 irrigations to Jambho or Taramira at 25-30 days intervals. Seed development stage is critical for irrigation. No irrigation is required for Dobari or Bosi crop.

1.2.2.7 Safflower

It is sensitive to heavy irrigations, especially in later growth stages. However, 56 irrigations are required under irrigated conditions.

1.2.2.8 Linseed

4-5 irrigations are enough. First irrigation 30 DAS and subsequent doses at 20-25 days intervals should be given. No irrigation is required, when it is grown as Dobari crop.

1.2.2.9 Lucerne (Alfalfa)

Lucerne is very important leguminous fodder, grown as a subsequent crop. 2 light irrigations in a week after sowing are helpful. It requires 10-15 irrigations in year, with an interval of 7-10 days during summer and 15-20 days in winter months. The yields are decreased with delay in irrigations.

1.2.2.10 Berseem

First 2 irrigations should be light and within a week. The following irrigations should be given at 10-15 days intervals.

1.2.2.11 Senji

It is one of the fodder crops, needs 2-3 irrigations during entire cropping period.


6

1.3 Ground Water in Pakistan

1.3.1 Quantity

The Indus Basin is formed by alluvial deposits carried by the Indus and its tributaries and is underlain by an unconfined aquifer covering about 15 million acres in surface area. In the Punjab about 79% of the area and in Sindh about 28% of the area is underlain by fresh groundwater, which is mostly used as supplemental irrigation water and pumped through tube wells. Some groundwater is saline and water from the saline tube wells is generally put into drains and, where this is not possible, it is discharged into the large canals for use in irrigation after diluting with the fresh canal water. In KPK abstraction in excess of recharge in certain areas such as Karak, Kohat, Bannu and D.I. Khan has lowered the water table and resulted in the contamination from underlying saline water. Whereas in Balochistan, the Makran coastal zone and several other basins contain highly brackish groundwater.

1.3.2 Quality

The quality of groundwater ranges from fresh (salinity less than 1000 mg/l TDS) near the major rivers to highly saline farther away, with salinity more than 3000 mg/l TDS. The general distribution of fresh and saline groundwater in the country is well known and mapped as it influences the options for irrigation and drinking water supplies. In the country some 14.2 million acres are underlain with groundwater having salinity less than 1000 mg/l TDS, 4.54 million acres with salinity from 1000 to 3000mg/l TDS and 10.57 million acres with salinity more than 3000 mg/l TDS.

1.4 Tubewells in Pakistan

According to 2010-11 Statistics of Agricultural Machinery, there were 954,320 tubewells and surface pumps in the country. Distribution of diesel and electric tubewells was 777,379 (81%) and 176,941 (19%) respectively. The average annual growth rate of tubewell population is 6.91%.

Exhibit 1.7: Typical Tubewell in Punjab


7

Power rating profile of the tubewells in Pakistan is provided in following table:

Less Than 10 hp 10 to 15 hp 16-20hp 20-25 hp 25 and Above Electric 50% 12% 16% 12% 10% Diesel 76% 1% 11% 4% 8%

Table 1.2: Power Rating of Tubewells

Utilization pattern of the tubewells in Pakistan has been provided in following table Province Total

Number of Tubewell

Average use Renting out time Days per Year

Hours per Day

Number of Tubewell

Average Hours rented per year

Average Hourly rate (Rs.)

Punjab Electric 61931 183 6 22174 619 110 Diesel 771642 124 5 143308 315 114 Sindh Electric 3349 151 7 513 468 112 Diesel 43691 123 6 6502 311 111 KPK Electric 9829 152 4 2350 43 106 Diesel 11020 108 5 2583 380 122 Baluchistan Electric 10659 227 7 681 532 120 Diesel 9552 189 5 611 259 121 Pakistan Electric 85,868 184 6 25,718 597 110

Diesel 834,905 125 5 153,004 316 114

Table 1.3: Utilization Pattern of Tubewells

1.5 Tubewell Energy Efficiency

Agriculture sector accounts for 13% of national electricity consumption, amounting 9,686 GWh annually. The estimated annual consumption of diesel (for irrigation purposes) is


8

58,100 tons of diesel (Pakistan Energy Year Book 2013). Furthermore, overall average efficiency of 5 to 7 percent for diesel tubewells and 20 to 30 percent for electric tubewells in Pakistan is estimated with potential for achieving overall efficiencies of 10 and 35 percent for diesel and electric tubewells, respectively. Improvement of irrigation pumpset efficiencies will not only conserve valuable energy supplies but also reduce pumping costs leading to lower cost of crop production. A successful energy conservation program requires a proper framework and baseline for identifying and evaluating energy conservation opportunities. Energy cannot be saved until it is known how it is being used and where its efficiency can be improved. In most cases, the establishment of this baseline requires a comprehensive and detailed survey of energy uses and losses. This survey is generally known as an Energy Audit. Findings of Tubewell Energy Audit Program conducted by Enercon in 1990s have been reproduced in a research paper attached to this manual as Annex I. Conducting an energy audit does not, however, constitute in itself an energy conservation program. A number of other conditions must also be met. First, there must be a will to save energy. Second, economically viable alternatives must be available. Third, financing must be available and fourth, the farmer must be committed to continuing the energy rationalizing efforts. The overall efficiency of a pumping plant depends upon the efficiencies of the power unit, transmission element, pump, piping system and the well. Instrumentation including electric power analyzers, fuel metering equipment, flow meters and pressure transducers, etc. is used in the evaluation of energy efficiency of the tubewell components as well as determining the causes of low efficiency. The test results are analyzed using basic computations and existing support material (exhibits, charts, calculators, computers, etc). The analysis results are used to build an energy balance. From this balance, it is determined how efficiently each component of the tubewell is actually operating and whether there is room for improvement. Finally, the costs and benefits of selected options are assessed. This manual is designed primarily to assist field engineers in carrying out tubewell energy audits and can also be used as a reference for university students taking courses on water pumping for irrigation and drainage.


9

1.6 Organization of the Manual

• Including this introductory chapter, this manual is divided into eight chapters. • Given that water pump is the heart of any tubewell, Chapter 2 provides a brief

introduction about the centrifugal pump types, its important terminology, components and selection.

• Chapter 3 provides brief review of the basic operating characteristics of tubewell components such as electric motors, diesel engines, transmission elements, pumps, piping and the well. An intimate knowledge of these operating characteristics is necessary for tubewell engineers involved in selection; installation, operational management and energy conservation programs.

• Chapter 4 discusses data requirements and types of tests for performance testing and trouble shooting of tubewell components.

• Instruments and equipment for tubewell audits are discussed in Chapter 5. • Tubewell energy audit methodology and data analysis are discussed in Chapters 6 and

7, respectively. • Chapter 8 provides brief overview of On Farm Energy Efficiency by covering Best

Practices for Energy Efficient Irrigation and Tractor Fuel Efficiency. • Relevant engineering information is given in the annexures.


10

2 CENTRIFUGAL PUMP

Pump is heart of any liquid handling system. For Irrigation Purposes, centrifugal pumps have universal adoption, being the most common type of irrigation pumps. A centrifugal pump operates in the following manner: 1. Liquid is forced into an impeller either by vacuum created at the eye the impeller. 2. The vanes of impeller pass kinetic energy to the liquid, thereby causing the liquid to

rotate. The liquid leaves the impeller at high velocity. 3. The impeller is surrounded by a volute casing or in case of a turbine pump a stationary

diffuser ring. The volute or stationary diffuser ring converts the kinetic energy into pressure energy.

In this chapter, a brief introduction has been provided about the centrifugal pump types, important terminology, components and selection.

2.1 Types of Pumping System

There are three major types of centrifugal pumps being used for irrigation purpose in Pakistan

2.1.1 Horizontal Shaft Centrifugal Pump

The pump is usually placed near the water level in a dug well. The pump and the motor are in the same plane. In Pakistan, horizontal shaft centrifugal pumps are usually being used where the required head ranges between 30 ft to 110 ft with usual power rating ranging between 5 to 30 hp. This is the most popular type of Pump for Tubewells, hence the major focus of the manual is on Horizontal Shaft Centrifugal Pump. Typical configuration of the centrifugal pump is presented in the Exhibit 2.1.

Exhibit 2.1: Centrifugal Pump


11

2.1.2 Turbine (Vertical Shaft) Pump

A turbine pump is a particular type of centrifugal pump that is mainly used to pump water from deeper wells as compared to horizontal shaft centrifugal pump. A turbine pump consists of a pump shaft, a rotating device known as an impeller, and a motor or an engine. A turbine pump may consist of multiple semi-open or enclosed impellers, also known as "stages." A metal plate called shroud supports the vanes of the impeller in an open or semi-open impeller, whereas in an enclosed impeller, the shroud encloses the impeller vanes. The motor on this type of pump is usually placed well above the water level. In Pakistan, turbine pumps are usually being used where the required head ranges between 75 ft to 160 ft with usual power rating ranging between 20 to 30 hp. Typical configuration of the Turbine pump is presented in the following Exhibit 2.2.

Exhibit 2.2Turbine Pump

2.1.3 Submersible Pump

A submersible pump has a hermetically sealed motor close-coupled to the pump body. The whole assembly is submerged in the fluid to be pumped. This pump is particularly suited for lower water table areas. The main advantage of this type of pump is that it prevents pump cavitation, a problem associated with a high elevation difference between pump and the fluid surface. In Pakistan, usually submersible pumps are being used where the required


12

head is more than 150 ft . Typical configuration of the Turbine pump is presented in the following Exhibit 2.3.

Exhibit 2.3: Submersible Pump

2.2 Components of Centrifugal Pump

The main components of a centrifugal pump are shown in following Exhibit and described below:

Exhibit 2.4: Components of Centrifugal Pumps

• Rotating components: an impeller coupled to a shaft • Stationary components: casing, casing cover, and bearings


13

2.2.1 Impeller

An impeller is a circular metallic disc with a built-in passage for the flow of fluid. Impellers are generally made of bronze, polycarbonate, cast iron or stainless steel. As the performance of the pump depends on the type of impeller, it is important to select a suitable design and to maintain the impeller in good condition. The number of impellers determines the number of stages of the pump. A single stage pump has one impeller and is best suited for low head (= pressure) service. A two-stage pump has two impellers in series for medium head service. A multi-stage pump has three or more impellers in series for high head service. Impellers can be classified on the basis of:

• Major direction of flow from the rotation axis: radial flow, axial flow, mixed flow • Suction type: single suction and double suction • Shape or mechanical construction

Closed impellers have vanes enclosed by shrouds (= covers) on both sides (Exhibit 2.5). They are generally used for water pumps as the vanes totally enclose the water. This prevents the water from moving from the delivery side to the suction side, which would reduce the pump efficiency. In order to separate the discharge chamber from the suction chamber, a running joint is necessary between the impeller and pump casing. This joint is provided by wearing rings, which are mounted either over extended portion of impeller shroud or inside the cylindrical surface of pump casing. A disadvantage of closed impellers is the higher risk of blockage.

2.2.2 Shaft

The shaft transfers the torque from the motor to the impeller during the startup and operation of the pump.

2.2.3 Casing

The main function of casing is to enclose the impeller at suction and delivery ends and thereby form a pressure vessel. The pressure at suction end may be as little as one-tenth of

Exhibit 2.5: Double Shroud Pump Impeller


14

atmospheric pressure and at delivery end may be twenty times the atmospheric pressure in a single-stage pump. For multi-stage pumps the pressure difference is much higher. The casing is designed to withstand at least twice this pressure to ensure a large enough safety margin. A second function of casing is to provide a supporting and bearing medium for the shaft and impeller. Therefore the pump casing should be designed to

• Provide easy access to all parts of pump for inspection, maintenance and repair • Make the casing leak-proof by providing stuffing boxes • Connect the suction and delivery pipes directly to the flanges • Be coupled easily to its prime mover (i.e. electric motor) without any power loss.

For Irrigation pumps, volute casing is used. Volute casing (Exhibit 2.6) has impellers that are fitted inside the casings. One of the main purposes is to help balance the hydraulic pressure on the shaft of the pump. However, operating pumps with volute casings at a lower capacity than the manufacturer’s recommended capacity can result in lateral stress on the shaft of the pump. This can cause increased wearing of the seals, bearings, and the shaft itself. Double-volute casings are used when the radial force becomes significant at reduced capacities.

Exhibit 2.6: Volute Casing

2.3 Pumping System Terminology

2.3.1 Head

Pressure is needed to pump the liquid through the system at a certain rate. This pressure has to be high enough to overcome the resistance of the system, which is also called “head”. The total head is the sum of static head and friction head:


15

2.3.2 Static Head

Static head is the difference in height between the source and destination of the pumped liquid (see Exhibit 2.7). Static head is independent of flow rate.Thestaticheadatacertainpressuredependsontheweightoftheliquidandcanbecalculatedwiththisequation:

𝐻𝑒𝑎𝑑𝑖𝑛𝐹𝑒𝑒𝑡 =𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒(𝑝𝑠𝑖) × 2.31

𝑆𝑝𝑒𝑐𝑖𝑓𝑖𝑐𝐺𝑟𝑎𝑣𝑖𝑡𝑦𝑜𝑓𝑡ℎ𝑒𝐹𝑙𝑢𝑖𝑑𝐵𝑒𝑖𝑛𝑔𝑃𝑢𝑚𝑝𝑒𝑑

Exhibit 2.7: Pump Static Head

Static head consists of (Exhibit 2.8): 1. Total suction head (hS): resulting from lifting the liquid relative to the pump center line.

The hSis positive if the liquid level is above pump centerline, and negative if the liquid level is below pump centerline (also called “suction lift)

2. Total discharge head (hd): the vertical distance between the pump centerline and the surface of the liquid in the destination tank.


16

Exhibit 2.8: Static Suction Head and Static Discharge Head

2.3.3 Friction head (hf)

This is the loss needed to overcome that is caused by the resistance to flow in the pipe and fittings. It is dependent on size, condition and type of pipe, number and type of pipe fittings, flow rate, and nature of the liquid. The friction head is proportional to the square of the flow rate. In most cases the total head of a system is a combination of static head and friction head.

2.3.4 Pump Performance Curve

The head and flow rate determine the performance of a pump, which is graphically shown in Exhibit 2.9as the performance curve or pump characteristic curve. For the calculation of the efficiency of the pumping system, these two parameters are of the prime importance. The Exhibit 2.9 shows a typical curve of a centrifugal pump where the head gradually decreases with increasing flow. As there instance of a system increases, the head will also increase. This causes the flow rate to decrease and will eventually reach zero. A zero flow rate is only acceptable for a short period without causing to the pump to burnout. The rate of flow at a certain head is called the duty point. The pump performance curve is made up of many duty points. The pump operating point is determined by the intersection of the system curve and the pump curve as shown in Exhibit.

Flow

Head

Static Head

Pump performance

curve S

Exhibit 2.9: Pump Performance Curve

Exhibit 2.10: Pump Operating Point


17

2.3.5 Pump Suction Performance (NPSH)

Cavitation or vaporization is the formation of bubbles inside the pump. This may occur when at the fluid’s local static pressure becomes lower than the liquid’s vapor pressure (at the actual temperature) as shown in Exhibit 2.11. A possible cause is when the fluid accelerates around a pump impeller. Vaporization itself does not cause any damage. However, when the velocity is decreased and pressure increased, the vapor will evaporate and collapse. This has three undesirable effects: 1. Erosion of vane surfaces, especially when pumping water-based liquids 2. Increase of noise and vibration, resulting in shorter seal and bearing life 3. Partially choking of the impeller passages, which reduces the pump performance and

can lead to loss of total head in extreme cases. To characterize the potential for boiling and cavitation, the difference between the total head on the suction side of the pump - close to the impeller, and the liquid vapor pressure at the actual temperature, can be used. Suction Head The suction head in the fluid close to the impeller can be expressed as the sum of the static and the velocity head:

ℎ𝑠 = 𝑃𝑠 γ� + 𝑉𝑠22𝑔� Equation 2.1

where

Exhibit 2.11: Reason of Cavitation


18

hs = suction head close to the impeller ps = static pressure in the fluid close to the impeller γ = specific weight of the fluid vs = velocity of fluid g = acceleration of gravity Liquids Vapor Head The liquids vapor head at the actual temperature can be expressed as:

ℎ𝑣 = 𝑃𝑣 γ� Equation 2.2

where hv = vapor head pv = vapor pressure It is worth mentioning that the vapor pressure in fluids depends on temperature. Water, our most common fluid, starts boiling at 20 oC if the absolute pressure in the fluid is 2.3 kN/m2. For an absolute pressure of 47.5 kN/m2, the water starts boiling at 80 oC. At an absolute pressure of 101.3 kN/m2 (normal atmosphere), the boiling starts at 100 oC. Net Positive Suction Head - NPSH The Net Positive Suction Head - NPSH - can be expressed as the difference between the Suction Head and the Liquids Vapor Head and expressed like 𝑁𝑃𝑆𝐻 = ℎ𝑠 − ℎ𝑣 Equation 2.3 or, by combining equation 2.1 and 2.2:

𝑁𝑃𝑆𝐻 = 𝑃𝑠 γ� + 𝑉𝑠22𝑔� − 𝑃𝑣 γ� s

Available NPSH - NPSHa The Net Positive Suction Head made available the suction system for the pump is often named NPSHa. The NPSHa can be determined during design and construction, or determined experimentally from the actual physical system.


19

Exhibit 2.12: Available Net Pressure Suction Head (NPSH)

For a common application - where the pump lifts a fluid from an open tank at one level to an other, the energy or head at the surface of the tank is the same as the energy or head before the pump impeller and can be expressed as:

ℎ𝑜 = ℎ𝑠 + ℎ𝑙 Equation 2.4

where h0 = head at surface hs = head before the impeller hl = head loss from the surface to impeller - major and minor loss in the suction pipe In an open tank the head at surface can be expressed as:

ℎ𝑜 = 𝑃𝑜 γ� = 𝑃𝑎𝑡𝑚 γ� Equation 2.5

For a closed pressurized tank the absolute static pressure inside the tank must be used. The head before the impeller can be expressed as:

ℎ𝑠 = 𝑃𝑠 γ� + 𝑉𝑠22𝑔� + ℎ𝑒 Equation 2.6

where he = elevation from surface to pump - positive if pump is above the tank, negative if the pump is below the tank Transforming Equation 2.4 with Equation 2.5 and 2.6:


20

𝑃𝑎𝑡𝑚 γ� = 𝑃𝑠 γ� + 𝑉𝑠2

2g� + ℎ𝑒 + ℎ1 Equation 2.7

The head available before the impeller can be expressed as:

𝑃𝑠 γ� + 𝑉𝑠22g� = 𝑃𝑎𝑡𝑚 γ� − ℎ𝑒 − ℎ𝑙 Equation 2.8

or as the available NPSHa:

𝑁𝑃𝑆𝐻𝑎 = 𝑃𝑎𝑡𝑚 γ� − ℎ𝑒 − ℎ𝑙 −𝑃𝑣 γ� Equation 2.9

Available NPSHa - the Pump is above the Tank If the pump is positioned above the tank, the elevation - he - is positive and the NPSHa decreases when the elevation of the pump increases. At some level the NPSHa will be reduced to zero and the fluid starts to evaporate. Available NPSHa - the Pump is below the Tank If the pump is positioned below the tank, the elevation - he - is negative and the NPSHa increases when the elevation of the pump decreases (lowering the pump). It's always possible to increase the NPSHa by lowering the pump (as long as the major and minor head loss due to a longer pipe don't increase it more). This is important and it is common to lower the pump when pumping fluids close to evaporation temperature. Required NPSH - NPSHr The NPSHr, called as the Net Suction Head as required by the pump in order to prevent cavitation for safe and reliable operation of the pump. The required NPSHr for a particular pump is in general determined experimentally by the pump manufacturer and a part of the documentation of the pump.


21

Exhibit 2.13: Pump Operation Point

The available NPSHa of the system should always exceeded the required NPSHr of the pump to avoid vaporization and cavitation of the impellers eye. The available NPSHa should in general be significant higher than the required NPSHr to avoid that head loss in the suction pipe and in the pump casing, local velocity accelerations and pressure decreases, start boiling the fluid on the impeller surface. Pumps with double-suction impellers has lower NPSHr than pumps with single-suction impellers. A pump with a double-suction impeller is considered hydraulically balanced but is susceptible to an uneven flow on both sides with improper pipe-work. To prevent cavitation, centrifugal pumps must operate with a certain amount of pressure at the inlet i.e. net positive suction head (NPSH). NPSHR is typically included on pump performance curves. If the NPSHA is sufficiently above the NPSHR, then the pump should not cavitate. A common rule in system design is to ensure that NPSHA is 25% higher than NPSHR for all expected flow rates. When oversized pumps operate in regions far to the right of their design points, the difference between NPSHA and NPSHR can become dangerously small.

2.3.6 Best Efficiency Point

An important characteristic of the head/flow curve is the best efficiency point (BEP). At the BEP, the pump operates most cost-effectively in terms of both energy efficiency and maintenance. Operating a pump at a point well away from its BEP may accelerate wear in bearings, mechanical seals, and other parts. In practice, it is difficult to keep a pump operating consistently at this point because systems usually have changing demands.


22

However, keeping a pump operating within a reasonable range of its BEP lowers overall system operating costs. Manufacturers use a coverage chart to describe the performance characteristics of a family of pumps. This type of chart, shown in Exhibit 2.14, is useful in selecting the appropriate pump size for a particular application. The pump designation numbers in Exhibit2.14 refer to the pump inlet size, the pump outlet size, and the impeller size, respectively. There is significant overlap among these various pump sizes, which is attributable to the availability of different impeller sizes within a particular pump size.

Exhibit 2.14: Family of Pump Performance Curves

2.3.7 Pump Curves for Multiple Impeller Sizes

Once a pump has been selected as roughly meeting the needs of the system, the specific performance curve for that pump must be evaluated. Often, impellers of several different sizes can be installed with it, and each impeller has a separate, unique performance curve. Exhibit2.15 displays performance curves for each size of impeller. Also illustrated are iso-efficiency lines, which indicate how efficient the various impellers are at different flow conditions. Sizing the impeller and the pump motor is an iterative process that uses the curves shown in Exhibit 2.15 to determine pump efficiency and performance over its anticipated operating range.


23

Exhibit 2.15: Performance Curves for Different Impeller Sizes

2.4 Pump Speed Selection

Pump speed is usually an important consideration in system design. The pump speed is perhaps best determined by evaluating the effectiveness of similar pumps in other applications. In the absence of such experience, pump speed can be estimated by using a dimensionless pump performance parameter known as specific speed. Specific speed can be used in two different references: impeller specific speed and pump suction specific speed. The impeller specific speed (Ns) is used to evaluate a pump’s performance using different impeller sizes and pump speeds. Specific speed is an index that, in mechanical terms, represents the impeller speed necessary to generate 1 gallon per minute at 1 foot of head. The equation for impeller specific speed is as follows:

𝑁𝑠 =𝑛�𝑄

𝐻34�

where Ns = specific speed n = pump rotational speed (rpm) Q = flow rate (gpm)


24

H = total head per stage (ft) For standard impellers, specific speeds range from 500 to 10,000. Pumps with specific speed values between 2,000 and 3,000 usually have the highest efficiency.

2.5 How to Select a Centrifugal Pump

The data required to size and source a pump include 1) system flow demands and 2) the system’s resistance curve. To determine the system curve, the required data include the system configuration, the total pipe length, the pipe size, and the number of elbows, tees, fittings, and valves. A designer can use these data—along with known fluid properties and the head available from the suction source—to estimate the system’s head loss and its NPSHA at the pump suction. At this point, the designer must review the manufacturers’ data to find pumps that can meet system requirements. This process requires repeated evaluations of many different pump characteristics, including the BEP, pump speed, NPSHR, and pump type. Using the expected system operating range, a designer must evaluate the family of performance curves, similar to that shown in Exhibit, for each pump manufacturer to identify pumps that meet the service needs. The next step is to evaluate the performance curves of each pump selected. Each pump usually has a range of performance curves for each impeller size offered with that pump. In Exhibit, a 4x1.5-6 pump is used as an example. The design point is just below the curve for the 6-inch impeller. For this particular pump size, at these operating conditions, the pump efficiency is 74%, and the 5-hp motor appears strong enough to meet service requirements. The pump’s BEP is just slightly to the right of

Exhibit 2.16: Pump Selection


25

the design point and the NPSHR is 6 ft. If the NPSHA is more than 7.5 ft, or at least 25% higher than the NPSHR, the 4x1.5-6 pump should be suitable.


26

3 OPERATING CHARACTERISTICS OF TUBEWELL COMPONENTS

A tubewell consists of the following major components: Well Majority of pumps are installed on drilled wells which may be

cased or un-cased. Public tube wells are generally cased and gravel packed. Coir, cement, brass and PVC strainers are in common use. Coir and cement strainers are widely used by farmers on private tubewells because of low initial cost.

Pump Majority of pumps installed in Pakistan are the horizontal shaft (dug well) centrifugal pumps. Turbine and submersible turbine pumps constitute a small percentage and have been installed in the deep water zones of the country.

Prime mover Electric motors, high and slow speed stationary diesel engines and tractors are the common power units used for irrigation water pumping.

Transmission Electric motors are usually direct coupled to the pumps. Flat belt drives are common for transmitting power from diesel engines. In some cases high speed diesel engines are directly coupled to the pumps and belts are used for transmitting power from electric motors.

Piping Galvanized iron pipes of 50 to 75 mm (2 to 3 in) diameter and steel pipes of 75 to 150 cm (3 to 6 in.) diameter' are commonly used on tube wells in Pakistan. Bends and pipes fabricated from sheet steel arc also common.

Each component of the tubewell has distinct operating characteristics. The energy efficiency of a tubewell depends on the degree of matching amongst the components and their individual efficiencies. Energy input output view of a water pumping system is shown in Exhibit 3.1. Operating characteristics of the various tubewell components are briefly described in the following sections.


27

Exhi

bit 3

.1: E

nerg

y In

put-

Out

put o

f a D

iese

l Eng

ine

Ope

rate

d Pu

mpi

ng S

yste

m


28

3.1 Well

The crust of earth is normally porous. Absorption of water w h i c h f a l l s o n t h e ground surface infiltrates through the crust and fills its pores. If a hole is drilled into the zone of saturation or a pipe with holes is installed, water will appear in it and will stand corresponding to the level of water contained in the formation. A saturated formation capable of yielding sufficient quantity of water is called an aquifer. This water can move freely under a p r e s s u r e gradient and is available for pumping. A tube well is a type of water well in which a long 100–200 mm (5 to 8 inch) wide stainless steel tube or pipe is bored into an underground aquifer. The lower end is fitted with a strainer, a pump at the top lifts water for irrigation. The required depth of the well depends on the depth of the water table.

Exhibit 3.2: Borehole of a Horizontal Shaft

Tubewell

3.1.1 Parts of Tubewell

A complete tube-well means: 1. A borehole vertical drilled up to

designed depth 2. Installation of requisite well assembly

i.e., housing pipe, blind pipe, slotted pipe or strainers, bail plug and other accessories.

3. Placing of suitable gravel pack (in case of gravel, packed tube-wells)/ Placing of suitable sand pack (in case of sand packed tube-wells).

Exhibit 3.3: Parts of Tubewell


29

Housing pipe: It is the pipe provided in upper portion of the tube-well in which pump and motor assembly is accommodated. Slotted pipe or screen: The screen or slotted pipe should be provided against the required thickness of aquifer in order to allow ground water to be pumped into the tube-well. The housing pipe, blind pipe and slotted pipe to be used in the tube-well may preferably be of seamless mild steel. Gravel packing: The term gravel packing is used to the placing of uniform gravel adjacent to the well screen. Use of cage type wire wound Strainer/Brass Strainer: These strainers are used in fine sandy formation. Column pipe: It is G. I. pipe directly connected with pump motor assembly, acts as delivery pipe, which is brought above top of housing pipe, and provided with a 90° bend and a sluice valve for controlling discharges Department of Agriculture and private contractors offer tubewell digging services. Pumping Rate in LPM

Size of well casing (in cm)

Size of pumping pipe (in cm)

113-226 10 5 226-302 12.5 7.5 302-378 15 8.25 to 1 378-567 15 10 567-945 20 12.5 945-1512 20 15

Table 3.1: Recommended Well Case and Pumping Pipe Size for Various Flow Rates

3.1.2 Draw Down

The difference in the static and pumping water levels in the well is called drawdown. Drawdown in a pumped well consists of head loss in the formation around the well (aquifer loss)and the head loss which takes place in entrance to the well itself(well loss) as shown in Exhibit3.4. Aquifer loss is a function of aquifer characteristics, geometry of well and boundary condit ions while well loss is primarily a function of open area of well Exhibit 3.4: Pump Draw Down


30

strainer, slot size, slot velocity, frictional and convergence losses. Diameter of wells varies from15 to 60cm for drilled wells and from 1.5 to 5 m for open wells. Data on drawdown per unit discharge (specific capacity) from tubewells having different diameters, lengths and types of strainers, etc in the lndus Basin is presented in Table 3.2 These drawdowns arc common during the first 3 to 5 years. Once the strainers are affected by incrustation, yield begins to fall and drawdown starts increasing thus reducing efficiency of the well

Designed Capacity

of tubewell

(ft3/s)

Type of Strainer

Range of Open Area (%)

Dia of Strainer

(in)

Effective Well Dia

(in)

Range of length of strainer

(ft)

Range of depth of bore (ft)

Type of Formation

Drawdown per ft3/s

(ft)

3 Slit type brass of

iron

5 to 8 10 22 120-150 200-350

Med-Sand 4 to 6

3 -Do- Do 10 18 -Do- -Do- -Do- 6 2 -Do- -Do- 8 12-18 120 200-

250 -Do- 6-8

2 -Do- -Do- 8 12-18 120 200-250

-Do- 6-8

2 Coir String

10-15 10 10 120 200-250

-Do- 6-8

2 -Do- 10-15 8 8 100-120 -Do- Med-fine sand

8-10

1 to 2 -Do- 10 - 15 6 6 100 200 -Do- 10-12

Table 3.2: Drawdown in Tubewells in the Indus Basin

3.2 Pumps

Centrifugal pumps are commonly used on tubewells. Characteristics of a turbine pump and well have been combined in Exhibit 3.5. The head- discharge curves of both the pump and well intersect at the operating point. The head discharge curve of the well (well curve) is determined with the help of a test pump. After the yield characteristics and desired discharge rate have been determined, a pump with the desired characteristics is selected and permanently installed at the well. System head tends to increase due to lowering of water table and aging of pipes resulting in the shift of operating point to the left. A properly selected pump should, therefore,


31

operate a little to the right of the peak efficiency point on the pump efficiency curve when new.

Exhibit 3.5: Pump and Well Characteristic Curves

Among the more important factors affecting the operation of a centrifugal pump are the suction conditions. Abnormally high suction lifts (low Net Positive Suction Head) beyond the suction rating of the pump, usually cause serious reduction in capacity and efficiency, and often lead to serious trouble from vibration and cavitation. Typical characteristic curves of a centrifugal pump are shown in Exhibit 3.6. Pump performance curves of various pump models available is Pakistan’s market have been regenerated in the Annex II.


32

Exhibit 3.6: Characteristic Curve of Centrifugal Pump

The mathematical relationships between these several variables are known as the affinity laws and can be expressed as follows: With impeller diameter kept constant: Q1Q2

= N1N2

Law 1a

H1H2

= �N1N2�2 Law 1b


33

BHP1BHP2

= �N1N2�3 Law 1c

With speed kept constant: Q1Q2

= D1D2

Law 2a

H1H2

= �D1D2�2

Law 2b

BHP1BHP2

= �D1D2�3

Law 2c

Q1 = Capacity and H 1 = head at N 1 rpm. or with impeller dia. D1 Q2 = Capacity and H 2 =head at N 2 rpm or with impeller dia. D2

Law 1a applies to Centrifugal, Angle Flow, Mixed Flow, Propeller, Peripheral, Rotary and Reciprocating pumps. Law 1b and 1c apply to Centrifugal, Angle Flow, Mixed Flow, Propeller, and Peripheral Pumps. Law 2a, 2b and 2c apply to Centrifugal pumps only. Where complete rating charts such as those shown in Exhibit 3.6 are not available, pump performance at other than manufacturer's specified points can be estimated using the affinity laws. However, this is true for Law 2 only under certain defined conditions. Calculated head-discharge characteristic using Law 1 agrees very closely to the test performance curves. The use of Affinity Law 1, therefore, to calculate performance when the speed is changed and the impeller diameter remains constant, is quite accurate approximation. When the impeller of a pump is reduced in diameter, the design relationships are changed, and in reality a new design results. The discrepancy is small for low specific speed pumps and more pronounced for higher specific speed pumps. Law 2, therefore, must be used with great deal of caution. When the affinity laws are used for calculating speed or diameter changes, it is important to consider the effect of suction lift on the characteristic for the increased velocity in the suction line and pump may result in cavitation that may substantially alter the characteristic curve of the pump.


34

Characteristic curves for various models of a famous make of centrifugal pumps are given in Annexure II.

3.3 Diesel Engines/Tractors

According to 2010-11 Statistics of Agricultural Machinery, there were 954,320 tubewells and surface pumps in the country. Distribution of diesel and electric tubewells was 777,379 (81%) and 176,941 (19%) respectively. Locally made and imported high speed diesel engines and tractors constitute the power units for diesel tubewells. The performance of a typical diesel engine under various conditions of load and speed is shown in Exhibit 3.7. For a diesel engine there is no sharp limit of power output at any speed and the color or exhaust smoke is a good guide for loading of an engine in good condition. A manufacturer may publish test curves showing a favorable output at all speeds but such a curve could not be compared with another test unless the exhaust conditions of smoke were same. Manufacturers specifications typically give only the maximum power output of an engine. Engines for intermittent use are rated at approximately 80 to 90 percent of the maximum power. For engines under continuous operation such as those installed on tubewells and tractors, the rating is approximately 60 percent of the maximum. To prevent the purchaser from abusing the engine, a throttle stop or governor is often installed. Small intake valves, to limit the mass of air induced into the engine, can also accomplish this purpose. Some manufacturers may advertise and deliver engines setup for maximum power. Naturally, an attempt to develop maximum power for extended periods will greatly shorten the life of the engine. Close examination of Exhibit 3.7 will indicate that a diesel engine can be operated at reasonably high efficiency for a wide range of loads by changing the speed. For example the engine whose performance is shown in Exhibit 3.7 can deliver 28hp to 45hp at specific diesel consumption of 0.221 kg/kWh with speed changing from 1200 to 2200 rpm. The fuel consumption will, however, vary from a high of 0.220 kg/kWh at 2400 rpm speed to a low of 0.210 kg/kWh at 1800 rpm. Therefore, proper throttle setting and the selection of appropriate engine and pump pulleys can greatly improve fuel efficiency especially when the engine is partially loaded.


35

Exhibit 3.7: Diesel Engine Performance Curves of Continuous Rated Power of 51 HP/38 kW1

Although diesel engines can be operated at high efficiencies at varying loads, a grossly oversized engine results in high pumping cost due to high investment and maintenance costs.

3.4 Electric Motors

The electric motors employed for irrigation water pumping are mainly 3-phase squirrel cage induction motors. The losses in an induction motor are caused by a variety of imperfections. These losses can be grouped under no-load and operating losses. The relative magnitude of these losses for a typical motor in the 7.5 to 15 kW (10 to 20 hp} range are given in Table 3.3. Losses % Primary I2R Losses (Stator) 5.6 Secondary I2R Losses (Rotor) 2.7 Iron Core Losses 3.0 Friction and Windage 1.4

1Curve 1 - Maximum rating (ISO Fuel Stop Power), Curve 2 - Intermittent rating, Curve 3 - Continuous rating


36

Stray Losses 2.3 Losses Sub-Total 15.0 Useful Power 85.0

Table 3.3: Typical NEMA B Design Motor, 10-20 hp; 85% Efficiency

Efficiency of induction motors varies with the degree of loading (Exhibit 3.8). While the efficiency of electric motors does not vary greatly within the half to full load range, overloaded motors have shorter lives and more expensive to maintain. On the other hand under loaded motors increase the cost per kilowatt of power used and cause unnecessary loading of the supply grid due to low power factors. Voltage variation can have a significant effect on the motor efficiency (Table 3.4). It also has severe effects on other motor parameters and tends to reduce motor life. As summarized in Table 3.4, voltage variation effect is especially ad- verse when the voltages are higher than rated and should be avoided or controlled to the extent possible. Voltage imbalance among the three phases has an even more serious effect on motor operation and should be strictly controlled. A 5 percent voltage imbalance, for example, can increase motor losses by 33 percent. Effect of Voltage Change

Operating Characteristics

90% Voltage 110% Voltage 120% Voltage

Starting and maximum running Torque

Decrease 19% Increase 21% Increase 44%

Synchronous Speed No Change No Change No Change Percentage Slip Increase 23% Decrease 17% Decrease 30% Full load speed Decrease 0.5-1% Increase 1% Increase 0.5-1% Staring Current Decrease 10-12% Increase 10-12% Increase 25% Full load Current Increase1-5% Increase 2-11% Increase 15-35% Temperature rise at full load

Increase 6-12% Increase 4-23% Increase 30-80%

Standard NEMA design B Motors Efficiency Full Load Increase 0.5-1% Decrease 1-4% Decrease 7-10% 0.75% Load Increase 1-2% Decrease 2-5% Decrease 6-12% 0.5% Load Increase 2-4% Decrease 4-7% Decrease 14-18%


37

Power Factor Full Load Increase 8-10% Decrease 10-15% Decrease 10-30% 0.75% Load Increase 10-12% Decrease 10-15% Decrease 10-30% 0.5% Load Increase 10-15% Decrease 10-15% Decrease 15-40%

Table 3.4: Effect of Voltage Variation on Induction Motor Performance

Exhibit 3.8: Motor Efficiency Vs. Load Level

Performance data for various efficiency classes of electric motors is given in Annexure III.

3.5 Transmission

Flat belt drives between diesel engines and pumps are common. Electric motors are usually connected to pumps through flexible couplings. Flat and v-belt drives are also used.


38

Belts are simple, economical and trouble free method of transmitting power. Cush ion action, quiet operation, flexibility of space requirements, lubrication-free and reliable operation arc the main advantages of belt drives. Proper pulley alignment, belt joints and tension arc, however, prerequisites for satisfactory operation of belt drives. In its simplest form, the formula for power transmitted by a flat belt is

𝑃 = 𝑆 =×(𝑇1 − 𝑇2)

1000

where P = Power transmitted by belt, kW S = belt speed, m/s T1 = tension at the tight side, N T2 = tension at the slack side, N Flat belts are tightened to certain recommended tension ratios. Taking into consideration the centrifugal tension and incorporating tension ratio R, above equation can be rewritten as:

𝑃 =𝑆(𝑇1 − 𝑇𝑐)�1 − 1

𝑅� �1000

where T = centrifugal tension, N R = tension ratio= (T1-Tc)/(T2-Tc) With fixed center or manually adjusted drives and 180 deg arc, belts are installed at R=2 and the tension restored when R reaches 3. Various factors influence the length of service of a flat belt. A reduction in pulley diameter or an increase in belt thickness will cause a marked reduction in the service life of the belt. Specifically, a 50 percent reduction in pulley diameter will reduce the service life to 1/32 of its former value, while only a 20 percent increase in belt thickness will reduce life by 66 percent. To obtain a reasonable length ,of service with small pulleys, the thickness of belt or the tension must be reduced. A well-designed belt drive working under normal conditions should operate without slip. Creep, however, is inevitable with all types of belting but with good belts seldom reaches one percent. Poor maintenance of flat belt drives can lead to excessive slip and hence loss of power, overheating of drive components and short belt life.


39

The nature of drive between the prime mover and pump affects the efficiency of pumping system. In comparison with direct drives which have transmission efficiency of nearly 100 percent, efficiency of v-belt drives ranges from 90 to 95 percent and for flat belt drives from 80 to 95 percent.

3.6 Piping

The flow of water is basic to all hydraulics. Friction losses incident to water flow may seriously affect the performance of pumps. The most critical part of a system involving pumps is the suction piping. A centrifugal pump that lacks proper pressure or flow patterns at its inlet will not respond properly or perform to its maxi mum capability. A significant portion of the head against which many pumps operate is due largely to the friction losses created by the flow. A basic understanding of the nature of these losses and an accurate means of estimating their magnitude is therefore essential. It is well established that friction losses in either laminar or turbulent flow of in- compressible fluids in pipe lines can be expressed by the basic formula:

ℎ = 𝑓 ×𝐿𝐷

× 𝑉2

2𝑔

where h = friction head loss, m f = friction factor L = length of pipe, m D = average internal diameter of pipe, m v = average velocity in pipe, m/s g = acceleration due to gravity, m/s2 Extensive theoretical and empirical studies carried out by leading hydraulic laboratories of the world have resulted in a simple method for determining friction factor "f" as a function of relative pipe roughness and/or Reynold Number of flow. Exhibits based on a comprehensive analysis of mass of experimental data on pipe friction have been compiled and are available in hydraulic handbooks for quick reference. Friction loss data for pipe size common in Pakistan is reproduced in Annex IV. Piping for tubewells consist or straight pipes as well fittings such as valves, elbows, reducers/enlarges, tees, etc. The resistance to flow caused by a fitting may be computed from the equation:


40

ℎ = 𝐾𝑉2

2𝑔

where h = frictional head loss, m v = average velocity, m/s K = resistance coefficient of the fitting Wide differences in the values of K are found in the published literature. For convenience, friction loss in fittings is often expressed as an equivalent length of straight pipe. This presentation is simple to use on complicated piping layouts involving an assortment of different fittings. Equivalent length of straight pipe for various fittings is reproduced in Table 3.5.

Table 3.5: Equivalent Length of Straight Pipe for Valves and Fittings (m)

Pipes deteriorate with age. In general, the flow carrying capacity of a pipe line decreases with age due to roughening of the interior surface caused by corrosive products, etc. The effect corresponds to a variation in friction factor due to increasing relative roughness. Precise estimates of the effect of aging on pipe friction arc not available. Approximate data presented in Table 3.6 may be used with caution and discretion. Age of Pipe in Years Multiplier for use with Values Given in Annex 3

Small Pipes 4’’ -10’’ Large Pipes 12’’-60’’ New 1.00 1.00 5 1.40 1.30 10 2.20 1.60 15 3.60 1.80


41

20 5.00 2.00 25 6.30 2.10 30 7.25 2.20 35 8.10 2.30 40 8.75 2.40 45 9.25 2.60 50 9.60 2.86 55 9.80 3.26 60 10.00 3.70 65 10.05 4.25 70 10.10 4.70

Table 3.6: Increase in Friction Loss Due to Aging of Pipe


42

4 PERFORMANCE TESTING OF TUBEWELL COMPONENTS

The energy input-output and efficiency of a pumping system are presented in Exhibit 4.1. In cases where efficiency of the pumpset is of interest, the electric energy (or energy in fuel) and water horsepower need only be measured. However.a complete analysis requires determination of efficiencies of all components in the system. Data requirements and types of tests for performance testing and trouble shooting of tubewell components are discussed in this chapter.

4.1 Pumpset

Pumpset efficiency refers to the efficiency at which the prime mover, transmission and pump combination converts energy (electricity or fuel) into mechanical work done on water. The following data is required to calculate pumpset efficiency: • Electric power input to the motor

or rate of diesel consumption by the engine.

• Pump discharge. • Total dynamic head. Electric power input to the motor can be measured using a wattmeter. Fuel consumption by diesel engine can be measured by timing the period required to consume a known quantity of fuel or a fuel flow meter may be used.

Exhibit 4.1: Energy Input-Output and Efficiency of a W

ater Pumping System


43

Several methods of measuring pump discharge of tubewells are available. These include ultrasonic flow meter, impeller meters; orifice plates and trajectory coordinate method (X-Y Method) etc. Total dynamic head developed by a pump (Exhibit 4.1) is made up of the following:

• Static discharge head • Static suction lift • Head loss in the delivery pipe • Head loss in the suction pipe • Velocity head of discharge

Total dynamic head developed by a horizontal shaft centrifugal pump can be calculated from measurements of pressures immediately before and after the pump and velocities of flow in the suction and discharge pipes. Velocities of flow in discharge and suction pipes can be calculated from discharge and internal diameters of discharge and suction pipes, respectively. With reference to Exhibit 4.1, total dynamic head developed by the pump is:

𝐻 =𝑃𝑑𝛾− 𝑃𝑠𝛾

+𝑉𝑑2

2𝑔−𝑉𝑎2

2𝑔

where H = Total dynamic head, m Pd = Pressure reading on gauge in discharge pipe, Pa Ps = Pressure reading on gauge in suction pipe, Pa Vd = Velocity or water in discharge pipe, m/s Va = Velocity or water in suction pipe, m/s g = Acceleration due to gravity, m/s2 The method of head determination described above applies specifically to pumping units installed so that both suction and discharge flanges of the pump and adjacent piping are located so as to be accessible for installation of gauges for testing the pump. In this case the pump is charged with the head losses in the pump itself and all other head losses are rightfully charged against the piping system. The installation of turbine pumps is invariably such that it is not possible to obtain pressures at the suction and discharge of the submerged basic pumping unit. Therefore, the method of head determination and testing must necessarily vary from the practice used for horizontal pumps. The only fair method of head determination is one that will permit checking of pump performance in the field. The method is briefly described below. With reference to Exhibit 4.2, the total dynamic head determined by this method is called "Field Head" for it can be obtained by field measurements. In this method, all velocity, entrance and friction losses at the suction of the pump are charged against the pump. Also


44

all exit losses from pump discharge as well as all column friction losses arc charged against the pump. This makes the efficiency of the pump appear lower than it really is. However, when not charged to the pump it makes field checking of turbine pump performance impractical.

4.2 Diesel Engine

The two parameters needed to evaluate the efficiency of an engine are the rate of fuel consumption and brake power. Simultaneous measurements of fuel consumption and brake power can be made using a fuel flow meter and a dynamometer. Measurement of fuel consumption is relatively easy. However, field measurement of power output of the engine is not generally practical. Dynamometers are inherently big and heavy thus posing transport problems. In addition, coupling of the dynamometer with the stationary engines installed in difficult to reach positions makes the use of dynamometers nearly impossible. Under these conditions the only alternative solution is to estimate engine efficiency from indirect measurements such as compression pressure, color of smoke, operating temperature, etc. Low engine compression pressure, poor atomization of fuel, wrong injection timing, low engine operating temperature, etc., all lead to part of the fuel not being fully oxidized and to the production of smoke. Color of the exhaust gases is a fair indicator of the combustion efficiency of the engine and thus can be used to estimate the efficiency of the engine. Color of the exhaust may be classified as clear, light, medium, dark and very dark. A smoke tester may be used instead of visual observation. Smoke ratings are expressed in arbitrary units for the particular smoke meter brand. For the Bosch-Bacharak Smoke Test (ASTM D2156), Bosch l, Bosch 2, Bosch 3, Bosch 4 and Bosch 8 correspond to clear, light, medium ,dark and very dark smoke, respectively.

Color of Smoke (Bosch Number) Diesel Engine Efficiency, %

Clear (Bosch Number 1) 30 Light (Bosch Number 2) 28 Medium (Bosch Number 3) 25 Dark (Bosch Number 4) 21 Very Dark (Bosch Number 5) 16

Table 4.1: Smoke Ratings as Per Bosch-Bacharak Smoke Test

The slow and high speed diesel engines installed on tubewells operate under these conditions and their efficiency can be estimated from the color of exhaust. Tractor


45

engines are lightly loaded when used for pumping water and efficiency estimates based on exhaust color may be in significant error. Part load operation, inefficient combustion, low compression pressure, excessive friction and defective cooling system lead to low engine efficiencies. Following tests may be carried out for trouble shooting the causes of low efficiency:

• Smoke test for inefficient combustion • Compression test to detect low compression pressure in the combustion

chamber • Temperature of coolant entering and leaving the cooling system.

The other method of gathering information about the combustion performance of the engine is emission analyzer. The instrumental methods include instruments used for non-continuous or continuous sampling using extractive samples and in-situ type instruments that require no sampling system. The instrument contains sensors of oxygen, carbon dioxide, carbon monoxide, nitrogen, sulfur dioxide, sulfur trioxide, nitric oxide, nitrogen dioxide, hydrogen sulfide, and hydrocarbons. Emission analyzers are found in many different price brackets. The cheapest portable multi-gas analyzers are commonly found under $5000. Portable units with improved sample conditioning and added program functionality are often found in the $5000 to $25,000 price range.

4.3 Electric Motor

A number of methods have been employed around the world to measure, approximate, or otherwise determine motor efficiency. Some of these methods are listed below:

• Brake Test • Dynamometer Test • Duplicate machine Test • Equivalent Circuit Calculation Method • Input Measurement and Segregation of Loss Method. These methods,

however, are applicable to motors on a test bench only. Determination of the efficiency of a motor in service on a tubewell is extremely difficult for reasons outlined for the diesel engines. An adaptation of IEEE Standard 112-2004 for the field testing of motors involves decoupling the motor from the pu1np. Three measurements required in this procedure are:

4.3.1 Load Test

Voltage, current, power input and shaft speed of the motor under actual load.


46

4.3.2 Stator Resistance

With the motor turned off, stator resistance between phases.

4.3.3 No Load Test

Voltage, current and power input to the motor load and turned on .. Motor efficiency can also be approximately estimated from motor power factor which is an easily measured quantity. Both the efficiency and power factor are dependent on the load on the motor. Efficiency-power factor relationship for a popular brand of 3-phase induction motors is shown in Exhibit 4.3. Correction for efficiency loss due to voltage or current imbalance may be applied to refine the estimate. This method of efficiency estimation requires the measurement of power input, power factor and line voltages and currents. Percent load on the motor can be calculated from the motor output and rated capacity. Overloading can also be checked by measuring motor temperature as motors run hot when over loaded. Measurement of line voltages can help in the detection of low or unbalanced voltage. Low motor voltage at the motor may be caused by overload, poor connections and small lead-in wires. Motors run hot due to unbalanced voltage. Unbalance may be present in the supply or caused by the motor coil unbalance. Current imbalance is a common problem arriving from unbalanced supply voltage and sub-standard rewinding of motors. This leads to wastage of electrical energy. More important is the fact that motors with large current imbalance are more prone to burnouts due to fluctuations in supply voltage.

4.4 Transmission

Transmission efficiency of direct couplings is nearly 1OO percent and need not be measured. Energy is lost in belt drives mainly due to slip. Continuous deformation and flapping of belt adds to energy loss but is difficult to measure. For simplicity, efficiency of belt drives can be estimated from slip using the following equation:

𝜂𝑡𝑟 = 100 + (1 − 𝑆) × 0.95 ηtr = efficiency of belt transmission, % S = belt slip 0.95 = correction factor


47

The following measurements are required to calculate slip: • Diameter and rotational speed of pulley on the motor or engine • Diameter and rotational speed of pump pulley • Diameters of pulleys on countershaft, if any.

4.5 Pump

In order to calculate efficiency of a pump, power input to the pump and water power need to be determined. Power input to pump can be measured only for bench tests. Hence, direct field measurements leading to the determination of pump efficiency are not possible. Pumps can be removed from the installation and tested in the laboratory under field head-discharge conditions to determine efficiency. This method, however, can be applied to a small number of pumps. Nonetheless, results of limited laboratory tests can provide useful information to validate the efficiency estimates of large number of pumps. Pump efficiency can be estimated approximately from characteristic curves supplied by the manufacturer if the pump is in good condition. Alternatively, it can be calculated from the measured efficiency of the pumpset and estimated prime mover and transmission efficiencies. With reference to Exhibit 4.1, pump efficiency can be calculated as follows:

𝜂𝑝𝑢𝑚𝑝 =𝜂𝑝𝑢𝑚𝑝𝑠𝑒𝑡𝜂𝑝𝑚 × 𝜂𝑡𝑟

Where ηpump = Efficiency of the Pump ηpumpset = Efficiency of the Pumpset ηpm = Efficiency of the Primemover ηtr = Efficiency of the Transmission

Low pump efficiency may result from a variety of problems including but not limited to worn impeller and its housing, plugged impeller, wrong impeller adjustment, wrong impeller diameter, crooked shaft, tight stuffing box, air intake and cavitation, etc. Suction condition is one of the most important factors affecting performance of a centrifugal pump. A centrifugal pump that lacks proper pressure at its inlet will not respond properly or perform to its maximum capability. Abnormally high suction lifts beyond the suction rating of the pump usually cause serious reduction in discharge and efficiency and often lead to serious trouble from vibration and cavitation. The situation of high suction lift can be corrected by lowering the pump setting.


48

Air will be sucked into the pump through the stuffing box under suction lift conditions if a seal cage is not installed. This will result in reduction in discharge and efficiency of the pump. Stuffing boxes that are too tightly packed and other rotating parts rubbing against the pump body result in loss of energy. Friction in the pump can be measured to assess this loss.

4.6 Piping System

Of the total energy supplied by the pump to water only a part is used to perform useful work. The remainder is dissipated in friction as water flows through the piping system. Pipes of small diameter, un-necessary height and length of discharge pipe, bends, tees, restrictions, etc., cause loss of energy and need to be recorded during audit. With reference to Exhibit 4.1, piping system efficiency can be calculated as:

𝜂𝑝𝑖𝑝𝑒 =𝑈𝑠𝑒𝑓𝑢𝑙𝐻𝑒𝑎𝑑

𝑇𝑜𝑡𝑎𝑙𝐷𝑦𝑛𝑎𝑚𝑖𝑐𝐻𝑒𝑎𝑑

Useful head is the difference in elevation of the pumping level in the well and the top water level in the water course. Piping system efficiency can be calculated only for those installations where water is pumped from open wells or cased wells in which case both the useful and total dynamic heads can be measured. Measurement of pumping water level in tubewells where a casing pipe has not been installed is not possible unless an observation well is installed next to the blind pipe .

4.7 Well

Proper matching of the head-discharge characteristic of the pump and head-discharge characteristic of the well and piping is essential for efficient water pumping, An important limitation of a centrifugal pump is that the AVAILABLE Net Positive Suction Head should be more than the REQUIRED Net Positive Suction Head for normal operation. A horizontal shaft centrifugal pump is placed above the water table while a turbine pump is submerged in water. Thus there are chances of a horizontal shaft centrifugal pump operating under high suction lift condition. Wells when drilled new have large specific yield (less drawdown) and the performance of a new centrifugal pump installed close to the water table will be satisfactory. Pores of the aquifer near the well get plugged up with fine particles carried by water flowing into the


49

well. Similarly reduction in open area of strainers takes place due to lodging of sand particles, encrustation and silting of bottom portion of the well. The specific yield goes down resulting in large drawdown. The situation is aggravated if the water table also goes down leading to high suction lift beyond the suction rating of the pump. Determination of high suction conditions is, therefore, necessary. Three possible field situations are diagrammatically shown in Exhibit 4.4 to 4.6 and described below. The numbers given for static and pumping water levels, and dynamic suction lifts are approximate and apply to 1400 rpm centrifugal pumps only. SITUATION 1 This situation is depicted in Exhibit 4.5 and is characterized by;

Static water level from pump around 2 m. Pumping water level from pump around Sm. Suction lift at suction flange of pump around 6 m. This situation indicates no well problem.

SITUATION 2 With reference to Exhibit 4.6, this situation is characterized by;

Static water level from pump > 4.0 m. Pumping water level from pump > 6 m. Suction lift at suction flange of pump > 7 m.

This situation can be corrected by lowering the pump to within 2.0 m from the static water level. SITUATION 3 Exhibit 3.9 depicts a silted well and/or chocked strainer and is characterized by;

Static water level from pump around 2.0 m. Pumping water level from pump> 6.0 m. Suction lift at suction flange > 7.0 m

This situation can be corrected by rehabilitation of the well using mechanical/chemical methods. These rehabilitation methods are, however, applicable only on wells fitted with metallic screens.


50

Exhi

bit 4

.2: T

otal

Dyn

amic

Hea

d- H

oriz

onta

l Sha

ft Ce

ntri

fuga

l Pum

p


51

Exhibit 4.3: Field Head – Deep Well Turbine Pump


52

Exhibit 4.4: Motor Efficiency vs Power Factor


53

Exhibit 4.5: Observation Well to Measure

Static and Pumping Water Levels for Uncased Well

Exhibit 4.6: Pumping Situation Depicting No

Well Problem


54

Exhibit 4.7: Pumping Situation Depicting Pump Installed at High Level Causing High Suction Lift

Exhibit 4.8: Pumping Situation Depicting Plugged Strainer Causing High Suction Lift


55

5 INSTRUMENTS AND EQUIPMENT FOR TUBEWELL ENERGY AUDITS

Measurement of pump discharge, rate of energy consumption, pressures in the piping system, linear distances, rotational speeds and etc are basic to the energy audit of tube wells. A wide range of instruments with different operating principles are available to perform these tasks and are listed in Table 5.1. The choice of a particular package of instrumentation, however, depends on the amount of data to be collected, desired accuracy, working environment, skills of available manpower and time frame. For detailed information on instruments for energy audits, the reader is referred to the ENERCON publication entitled "Energy Measurement and Instrumentation". Parameter Instrument & Method

Pump Discharge Orifice Meter Pitot Tube Electronic flow meters Flumes Time and volume

Pressure Bourdon gauges Electronic transducers

Electric Energy Power Analyzer Kilowatt Meter

Fuel consumption Calibrated curette Balance Rotameter Electronic fuel flow meter

Speed Contact tachometer Photo tachometer

Water level Electric well sounder Airline well sounder

Temperature Glass thermometer Dial thermometer Thermocouple thermometer

Table 5.1: Instruments & Methods for Tubewell Energy Audit

These instruments are described in the following sections.


56

5.1 Water Flow Meter

Portable Ultrasonic flow meter is used to measure discharge of pump with highest accuracy. It is mostly utilized on every type of water supply/discharge line. There are two sets of transducers that measure flow and velocity of fluid using ultrasonic waves. Ultrasonic flow meter is shown in Exhibit 5.1 & 5.2

Exhibit 5.1: Ultrasound Flow Meter

Exhibit 5.2: Ultrasound Flow Meter Kit


57

There four methods of installing transducers on the pipe i.e. V-method, Z-method, N-method (not commonly used) and W-method (very rarely used) to measure flow rate.

5.2 Pressure Module

Pressure module contains two electronic pressure transducers of the following specifications:

Low Pressure: Nominal Range -100to+1OOkPag (-15 to+ 15 Psig)

High Pressure: Nominal Range 0 to+690kPag (0 to+100psig)

Each transducer has output range of 5 volts beginning at 1 VDC and ending at 6 VDC across its pressure range. These transducers have built-in regulation of supply voltage and temperature effects. The transducers have threaded fittings and are connected to pressure taps on the discharge and suction pipes by means of quick couplings and Tyson tubing. The Pressure Module is electrically connected to the Switching Module which acts as interface for power supply and signal output. The output is monitored on the Millimeter.

5.3 Multimeter

The Multimeter is shown in Exhibit 5.5. The output of the various transducers such as water flow sensor (frequency), high and low pressure transducers (voltage) and etc. It is channeled to the Multimeter through the Switching Module. The Multimeter thus provides readout for the test data. Different components of multimeter are provided in the following:

Exhibit 5.3: Multimeter


58

5.4 Energy / Electric Power Analyzer

The enegy/electric power analyser shown in Exhibit 5.4 is capable of measuring AC parameters in both single and three phase (balanced and un-balanced) loads. Its applications include energy audits and general pupose trouble shooting of

electrical equipment and distribution lines. Its application in the electric tubewell energy audit includes the measurement of currents, voltages. Kilowatts and power factor of the electric motor. The analyser use clamp-on current transducers which enable the current in live circuit to be measured without disconnecting the current carrying conductors. Power qulaity of electric source can also be checked using Harmonic Mode of the meter.

5.5 Tachometer

The tachometer shown in Exhibit.5.5 can be used as photo tachometer as well as contact tachometer. It is used to measure the speeds of electric motors, diesel engines and pumps.

Amps, Volts and Common Terminal

Volt, Amps, Resistance and Diode Testing Terminal

Function Switch

Minimum, Maximum and Average Recording

AC or DC Resistance and Capacitance

Continuity Beeper

Relative Reading Frequency Counter Digital Display

Back Light Display

Exhibit 5.4: Power Analyzer

Exhibit 5.5: Tachometer


59

5.6 Fuel Weighing System

The fuel weighing system is shown in Exhibit 5.6. It consists of a top loading electronic balance. The beaker is containing fuel is placed on the balance. Fuel to the engine is supplied from the beaker and return flow is put back into it. A stop watch is used to time and change in the fuel on the balance. Fuel consumption is calculated from the time and weight data. As most liquid fuels are measured in the volume units, it is better to understand the conversion process. Dividing the fuel density with its weight will give the volume of the fuel.

5.7 Electric Well Sounder

Water level sensor is used to measure depth to water, pump tests and slug test and dewatering application. First we ensure the knobs that secure the control panel are tightly fastened then hang the unit on the well casing. Guide the tape over the tape guide avoiding the edge of the well casing to prevent damaging the tape. Now, rotate the hand brake counterclockwise until the tape slowly unwinds from the reel. The unit will beep when the probe touches water. Carefully determine the depth to water from the reference point by slowly lowering and raising the probe to the air/water interface. Raise the probe, dry it, and repeat the measurement. Rugged Level Tape probes are rated to full depth and can be used to measure the depth to the bottom of a well. Slowly unwind the tape until the probe touches the bottom and the tape becomes slack. As you wind the tape onto the reel, remove moisture and debris. Water level meter is shown in the Exhibit 5.7

Exhibit 5.6: Fuel Weighing System

Exhibit 5.7: Electric Well Sounder


60

5.8 Diesel Engine Compression Tester

A diesel engine compression tester is shown in Exhibit 5.8. The compression tester is used to detect compression defects in the engine. The compression test should be performed on a warm engine i.e. sump oil temperature about 40 °C.

5.9 Smoke Tester/Flu Gas Analyzer

Digital smoke tester is used to measure smoke level (0-6) for the indication of the operating condition of the engine. It takes constant sampling over one minute. Type of sensor is used in smoke tester is photo diode. High accuracy as the filter paper is continuously heated during sampling. Backlight display and rechargeable battery, mains unit and carrying case. Battery can be charged within the tester using the mains unit. Mains operation of the tester possible uses the mains unit.

Exhibit 5.8: Diesel Engine Compression Tester

Exhibit 5.9: Smoke Tester


61

5.10 Thermocouple Thermometer

A thermometer consists of a pair of conductors of different metals or alloys joined together at both ends. One end is placed in the area where temperature is to be measured. The difference in temperature between the measuring junction and reference junction causes a voltage to be generated. The magnitude of the voltage is a function of the difference in temperatures between the measuring and the reference junctions. A thermocouple with an electronic readout is shown in Exhibit. 5.10 Using the readout device with thermocouple probes in various configurations, the unit is used to measure ambient temperature, motor temperature, temperature of water entering and leaving the engine, exhaust temperature, temperature of engine oil etc. during tube well energy audits.

5.11 Friction Torque Tester

The apparatus to measure friction in the pump due to gland packing, etc. consists of a spring scale and a piece of string. In order to measure friction, the string is wound around the pump shaft. The free end of the string is tied to the spring scale hook. The scale is pulled thus rotating the shaft as the string un-winds. Scale reading is noted while the shaft rotates. Friction torque is calculated from the shaft radius and the scale reading.

5.12 Tool Kit

Contents of the Tool Kit for tubewell audits are listed below:

Tape for measurement of linear distances

Diameter Tape Hammer

Punch Drill machine Drill bits

Exhibit 5.10: Thermocouple Thermometer


62

Taper reamer Taps Hack saw Screw driver set Pipe wrenches Spanner set Nut drivers Vice wrench Adjustable wrench File Tap extractor set Tool apron Working gloves Goggles

5.13 Accessories Kit

The accessories kit consists of a variety of consumable and non-consumable items required to carry out the tubewell energy audits. These are: Pipe plugs Hose clamps Rubber pipe fittings PVC pipe sections Rubber sheet Tygon tubing Engine fuel line fittings GI pipe fittings Cutting fluid Pipe thread compound Cells and batteries Electrical tape Teflon tape Portable 12 volt air

compressor Complete car wheel with tire and tube

Extension cable with holder for light bulb

Kerosene lantern Flash light

Long rubber shoes Rope Hand held scientific calculator

5.14 First Aid Kit

Utmost care and alertness is required while auditing tubewells. Any negligence can result in electrical shock, entanglement with belts, burning due to contact with hot engine parts, deep falls, inhaling of poisonous gases, insect bites, etc. The First Aid Kit should contain ointment for cuts, bites, burns, etc. and bandages

Exhibit 5.11: First Aid Kit


63

6 AUDIT METHODOLOGY

Guidelines for conducting energy audit of electric and diesel tube wells are presented in this chapter.

6.1 Calibration of Instruments

All instruments should be calibrated before the tests and all calibration and correction data or curves should be prepared in advance.

6.2 Audit Procedure

Before proceeding on to tube wells audit, study of the following aspects of installation must be carried out:

6.2.1 General Information:

Take general information regarding tube well energy audit like Village Name, Audit Team Name, Audit Date, Arrival& Departure time of audit team, Name of the Farmer, Address, District and Cell Number.

6.2.2 Tube Well General Information

Note General Information like Well Type, Existing Pump Type, Delivery Piping Type, Suction Piping Type, Filter Type, Drive Type and Year of installation for Tube well, Bore and Filter. General/Physical condition of overall civil works of tube well, Motor Control Unit (MCU) and filter.

6.2.3 Safety Aspects

Note the condition of electric connections, pump shelter, retaining walls for safety purpose. In case of Turbine pump note Housing/Blind pipe (casing) length and diameter. In case of centrifugal pump note the well diameter. Pulley sizes, diameter of discharge and suction pipe for in case of drive belt.


64

Note: A tubewell should be subjected to detailed audit only if the audit team considers it safe.

6.2.4 Test Feasibility Review

Review the installation to ensure feasibility for: • Flow measurement (Discharge Point is appropriate) • Electric power (Availability, Proper Wiring & wire insulation) • Fuel measurement • Access for well sounding • Installation of pressure taps • Priming of pump if prime is lost due to drilling of holes for pressure taps.

6.2.5 Guidelines for Tube Well Energy Audit

This section has been arranged in such a manner that specific guidelines for conducting tubewell energy audit and its working example have been provided for every major step in the audit. • Switch off the Tube well or Stop the Prime mover in case of Diesel Tube Well • Note pump set name plate data i.e. Manufacturer, Year of Manufacturing, Serial number,

Pump and motor size, Rated Efficiency, Operative head, Impeller diameter, Discharge, Voltage/Voltage band and Full load amperes.

Exhibit 6.1: Typical Name Plates of Motor and Pump

• Check the Capacitor availability and capacity of capacitor in case of electric tubewell.


65

Exhibit 6.2: Typical Capacitor Bank of Electric Tubewell

• Install the flow meter in Z or V- method as shown in Exhibit 6.3

Exhibit 6.3: Ultrasonic Flow Meter in Installed Position

• Install the Power Analyzer for taking electrical reading (KW, KVAR, KVA, Voltage, Current, Power Factor and Frequency of electricity) in case of Elect. tube well. Installation is shown in the Exhibit6.4

• Install fuel meter for measuring

fuel consumption in case of diesel engine.

• Turn on the electric/diesel tube well

• Take flow meter reading from

Exhibit 6.4: Power Analyzer Readings


66

Ultrasonic flow meter as Exhibit 6.5

Exhibit 6.5: Flow Meter Readings

• In the absence of ultrasonic flow meter, Flow can be measured using Flow Trajectory method. Place the scale at the discharge point note down the horizontal distance covered by water during discharge. Keep the scale straight and now measure vertical distance of discharge. It is shown in the Exhibit 6.6

Exhibit 6.6: XY Method (Flow Trajectory Method) for Flow Measurement


67

Exhibit 6.7 : Scale in Position to take X Reading

In the above Exhibit X and Y distance is 16.1 and 12 inches respectively. • Measure free zone area at the discharge point as shown in Exhibit 6.8. However in our

sample case there is no free zone as evident from Exhibit 6.7. .

Exhibit 6.8: Free Zone Measurement


68

Electric Tube wells • If flow control valve is installed, collect 5 sets of data as follows;

Set 1 Valve completely closed. This is a short duration test. Collect power consumption and delivery and suction pressure data only. Set 2 Valve approximately 1/4open. Complete set of data required for this and other valve openings. Make sure that the water flow Meter runs full. Set 3 Valve approximately ½ open. Set 4 Valve approximately ¾ open. Set 5 Valve full open.

• If flow control valve is not installed, take three repeated sets of data at the prevailing operating condition.

• Take all electric reading i.e. Voltage, Current, Input Power, Power Factor using Power Analyzer like below as shown in Exhibits as shown below;

In our sample case electrical readings are Voltage=375 Volts, Amps=13.3A, KW=7.60 & Power Factor is 0.88 as shown in exhibit 6.9.

Exhibit 6.9: Electrical Readings

Diesel Tube wells • Collect 3 sets of data as explained below without changing the setting of flow control

valve, if installed. Set 1. At farmer's setting of engine speed. Set2. Approximately 15 to 20 percent higher engine speed than farmer's setting. Set3. Approximately l5 to 20 percent lower engine speed than farmer's setting


69

• Start the prime mover and take three or five sets of data as described above. The system should come to equilibrium before taking a set of data. Otherwise inrush current will be encountered in case of electric tube well while taking electrical reading.

• Measure fuel consumption, note the color of diesel engine exhaust and temperature of coolant leaving diesel engine in case of diesel engine.

In our sample case for first five minutes fuel consumption is 126 gram, next five minutes it is 152 grams and further five minutes it is 60 grams. • Observe the colour of smoke in three different

set of readings. • In the same way measure the exhaust

temperature (Celsius) that is 164, 247 and 125 for our sample case.

• Now measure the coolant temperature (Celsius) on entrance and at the time of exit from the engine that is 28, 27,5, 28 for entrance and 35,36, 33 for exit in our sample case.

• Measure pressure transducer on the suction and discharge sides of pump which is 1.083, 1.073, 1.070 for suction and 1.889, 1.787, 2.280 for discharge in our sample case.

• Measure speed of the pump & motor speeds using tachometer as Exhibit 6.10. which for our sample case measured speed is 1331, 1547 and 1105 for three set of readings.

• Measure ambient and motor temperatures for electric tube wells at a distance of approximately one meter away from the motor. Motor temperature is to be measured at a point on the motor where fan is not blowing the air using infrared temperature gun as shown in Exhibit 6.11. In our sample case measured temperature (Celcius) is 68 at motor and 65 at bearing.

Exhibit 6.11: Motor Temperature Measurement

• Measure the suction and delivery diameter using caliper as shown in Exhibit6.12

Exhibit 6.10: Motor Speed Measurement


70

In our sample case internal diameter of the delivery pipe is 5.2 inches.

Measurement for Total Dynamic Head • Measure the Bore depth/Well. In our sample case it is 25 feet. • Measure the pumping level. In our sample case it is 18, 19 and 16 feet. • Measure depth of pump installation as shown in Exhibit6.8. In our sample case, it is 15

feet.

Exhibit 6.12: Depth of Pump Installation

• Note draw down in case of sample it is zero. • Measure suction length i.e 4 feet in our sample case. • Measure delivery length i.e. 26 feet in our sample case (depth of pump installation +

height above the ground level + length of horizontal line = 15+4+7)


71

Exhibit 6.13: Length of Horizontal

Line Exhibit 6.14: Height above Ground

• Measure depth of static water level as shown in Exhibit 6.9 in our sample case we have

water table depth is 20 ft.

• Measure the delivery head i.e 15 feet is the value in our sample case. • Measure the suction head of pump i.e it is 4 feet our sample case. • Measure internal diameter of the bore casing that is 10 inch in our sample case. • Note the types and number of bends and valves in the delivery pipe there is one bend of

90 degree in our sample case. • To measure friction in the pump removes the belt of belt driven pumps. Measure shaft

diameter of the pump and wind string around the shaft of the pump. Tie free end of the string on the spring scale hook. Pull on the string scale thus rotating the pump. Take reading from spring scale while pulling.

• Add remarks that may include different observations like noise, vibration, miss alignment of the pump and motor, surging and accompanied unsteady discharge, leakage of the stuffing box during operation and after shut down. Engine compression seal cage in the stuffing box, Engine compression pressure should be taken into account. Use lube oil in the compression chamber to help start engine. Look unnecessary pipe fitting and unnecessary high discharge level.

Exhibit 6.15: Water Depth Measurement


72

6.3 Energy Audit Performa

Fill all the information in energy audit Performa that is containing the entire necessary parameters fill it carefully. A format has been provided in Section 7.3.

6.4 Manpower/Time Frame

Detailed tube well energy audits are carried out most efficiently by a team of one Energy Auditor or Field Engineer and one Mechanic. Time required for and audit depends on several factors such as:

o Type of prime mover o Type of transmission o Type of pump o Availability of electricity o Depth of pit in case of centrifugal pump o Starting problems with engine o Priming problems with pump o Access to pump set components o Availability and attitude of the farmer, etc.

The detailed audit of a centrifugal pump driven from diesel engine takes one full day. Centrifugal and turbine pumps driven from electric motors can be audited at the rate of two-three per day depending upon the availability of electricity and location of tube well


73

7 DATA ANALYSIS AND DIAGNOSIS OF TUBE WELL PROBLEMS

Analysis of tube well energy audit data involves conversion of transducer outputs to common units used in water pumping, calculation of different quantities and efficiencies, estimation of component performance from secondary data when performance cannot be directly measured and identification of sources of in efficiency, Analyzing and correcting pump set performance in the field is a complex subject because of the large number of variables involved. The inter-relationships of these variables can make such analysis time consuming if the relative importance of the variables is not understood. Performance curves of various components of the pumping plant are usually not available from the indigenous manufacturers which can further complicate the process of trouble shooting.

7.1 Calculations

7.1.1 Discharge

The pump discharge Q is the volume of water per unit time delivered by the pump. In SI measure it is usually expressed in liters per second (L/s) and cubic meters per second (m3/s). In FSS measure the corresponding units are gallons per minute (gpm)and cubic feet per second (ft3/s). Discharge can be measure directly from ultrasonic flow meter or can be estimated using XY Method.

7.1.1.1 Discharge Using XY- Method

Discharge can be measured using XY-Method, if there is no ultrasonic flow meter is available. In this method vertical and horizontal discharge is measured as explained in Audit methodology. Flow (in m3/hr) based on XY Method for Straight Pipeline:

𝑄 =𝐷 × (2.54)2 × (𝑋𝑅𝑒𝑎𝑑𝑖𝑛𝑔 (𝑖𝑛)) × 2.54

59 × �𝑌𝑅𝑒𝑎𝑑𝑖𝑛𝑔 (𝑖𝑛) × 2.54× 3.6


74

Where D = Internal diameter of the delivery pipe (Inches) Sample Case Data: D= Internal diameter of the delivery pipe (in)= 5.2” X= Horizontal drop distance= 16.1” Y= Vertical drop distance= 12” Then flow will be calculated

𝑄 =5.2 × (2.54)2 × (16.1 × 2.54)

59 × √12 × 2.54× 3.6

𝑄 =7129.69

59 × 5.52× 3.6

𝑄 = 78.79 m3/hr

7.1.2 Head

The pump head H represents the net work done on a unit weight of water in passing from the inlet or suction flange to the discharge flange For horizontal shaft centrifugal pumps, it is calculated using the expression.

𝐻 = �𝑃𝛾

+ 𝑉2

2𝑔+ 𝑍�

𝑑− �

𝑃𝛾

+ 𝑉2

2𝑔+ 𝑍�

𝑠

Where P/ γ = Pressure head in the discharge line m(ft) V2/2g = Velocity Head, m Z = Elevation Head, m The pressure head P/γrepresents the work done by the pump in moving a unit weight of water against the pressure P. The term V2/2g called the velocity head, which represents the kinetic energy of a unit weight of water moving with velocity V. The elevation head or potential head represents the potential energy or a unit weight of water with respect to the chosen datum. The first parenthetical term in the equation under considerationis called the discharge head, and the second, the inlet or suction head. The difference is called the Total Dynamic Head. Total Head or Field Head developed by turbine pumps is calculated as follows:

𝐻 = 𝑃𝛾

+𝐻𝑠 + 𝑍 + 𝑉2

2𝑔


75

Where P/ γ = Pressure head in the discharge line m(ft) Hs = Vertical distance from level of water in well when pumping to the center line or discharge m (ft) Z = Elevation of pressure gage from center line of discharge, m (ft) V2/2g = Velocity head in the discharge pipe, m (ft) The other method of estimating of total dynamic head is through calculating Total Static Head, Friction Head and Drawdown separately. Step 1: Head Above Ground Level 𝐻𝑒𝑎𝑑𝑎𝑏𝑜𝑣𝑒𝐺𝑟𝑜𝑢𝑛𝑑𝐿𝑒𝑣𝑒𝑙(𝑓𝑡)

= 𝐷𝑒𝑙𝑖𝑣𝑒𝑟𝑦𝐻𝑒𝑎𝑑(𝑓𝑡) − 𝐷𝑒𝑝𝑡ℎ𝑜𝑓𝑃𝑢𝑚𝑝𝐼𝑛𝑠𝑡𝑎𝑙𝑙𝑎𝑡𝑖𝑜𝑛𝑏𝑒𝑙𝑜𝑤𝐺𝑟𝑜𝑢𝑛𝑑𝐿𝑒𝑣𝑒𝑙 (𝑓𝑡) In case of sample case Head above the Ground level= 4 ft Step 2: Static Head

𝑆𝑡𝑎𝑡𝑖𝑐𝐻𝑒𝑎𝑑(𝑓𝑡) =𝑊𝑎𝑡𝑒𝑟𝑇𝑎𝑏𝑙𝑒𝐷𝑒𝑝𝑡ℎ(𝑓𝑡) + 𝐻𝑒𝑎𝑑𝑎𝑏𝑜𝑣𝑒𝐺𝑟𝑜𝑢𝑛𝑑𝐿𝑒𝑣𝑒𝑙 (𝑓𝑡)

3.28

In case of our sample data: Water Table Depth (ft) = 20 Head Above the ground (ft)= 4 So Static Head (ft) = (20+4)/3.28= 7.31 Step 3: Friction Head

𝐹𝑟𝑖𝑐𝑡𝑖𝑜𝑛𝐻𝑒𝑎𝑑 = (4 ∗ 0.0015 ∗ (𝐷𝐿/3.28) ∗

� 𝑄′

3600∗��3.172∗(𝐷∗0.0254)24 ��

�

2

2 ∗ 9.81 ∗ 𝐷𝐿 ∗ 0.0254


76

Where DL = Delivery Pipe Length (ft) D = Diameter of the delivery pipe (inches) Sample data: DL= Delivery pipe Length= 26 ft D = Diameter of the delivery pipe= 5.2” Q = Flow = 78.79 m3/hr So Friction Head = 0.00581 m Step 4: Water Draw Down Drawdown= ((Flow Based on XY Method*35.31467/3600)/(2*PI*0.003*Length of the Strainer, M (ft))*2.3*(1/1/log(R/rw)))*0.3048 Flow= 78.79 m3/hr Length of filter/stainer = 38 ft R/rw= diameter of filter Drawdown = 0.6091 m Step 5: Total Head for Centrifugal Pump Total Head for Centrifugal= Total Static Head + Friction Head + Drawdown + (Seasonal Water Variation Summer)/3.28 Sample case data: Total Static Head = 7.31 m Seasonal Variation in Summer = 2 ft Friction Head = 0.00581 m Drawdown= 0.6091 m Hence Total Dynamic Head = 8.54 m


77

7.1.3 Water Power

Water power is calculated from pump discharge Qand Total Dynamic Head H. In SI, the power P in kW is given by

𝑃 = 𝑄 × 𝐻102�

Where Q is in liters per second H in meters. In FSS, the water horsepower is calculated by

ℎ𝑝 = 𝑄 × 𝐻3300�

Where Q is in imperial gallons per minute and H is in feet Sample case data: Water Power = 21.886 x 8.54 / 102 Water Power = 1.83 kW

7.1.4 Pump Set Efficiency

Pump set Efficiency is the Water Power divided by the power input to the prime mover. When prime mover is an electric motor, this is also called Wire-to-Water Efficiency. Electric power input to the motor is directly measured in kW and pump set efficiency is easy to calculate. For diesel engines, however, energy in fuel must be calculated first. Following conversion factors apply to diesel fuels sold in Pakistan:

In SI L/h 10.46kW

In FPS Imp. Gal/h 63.74hp

7.1.5 Piping Efficiency

Piping Efficiency is the ratio of difference in elevations of water level in the well during pumping and water course and the Total Dynamic Head.


78

7.1.6 Overall Efficiency

Overall Efficiency of a tube well is the product of Pump set and piping efficiencies.

7.1.7 Estimated Motor Efficiency

Motor efficiency can be estimated from motor power factor and current imbalance in the three phases using expression given below: Motor Efficiency = A + B x Motor Power Factor + C x Current Imbalance Values of constants A, B and C are given in Exhibit 6.1. These were developed from performance data published by on manufacturer of quality electric motors and limited field tests. Values of constants A, Band C for use in Eq.6.5 to calculate efficiency of 3-phase squirrel cage motors.

Motor Rating Constant A Constant B Constant C

kW HP Less than 3.7 Less than 5 0.35 0.56 -0.48 3.8-5.6 5.1-7.5 0.41 0.51 -0.48 5.7-7.5 7.6-10 0.15 0.81 -0.48 7.6-11.2 10.1-15 0.38 0.57 -0.48 11.3-15 15.1-20 0.36 0.57 -0.48 15.1-18.7 20.1-25 0.5 0.42 -0.48 18.8-22.4 25.1-30 0.61 0.32 -0.48 22.5-29.8 30.1-40 0.59 0.35 -0.48

Table 7.1: Motor Efficiency Estimation

Motor Efficiency = A + B x Motor Power Factor + C x Current Imbalance

7.1.8 Estimated Engine Efficiency


79

Color of Exhaust Estimated Diesel Engine Efficiency

Clear 0.3 Light 0.28 Medium 0.25 Dark 0.21 Very Dark 0.16

Table 7.2: Engine Efficiency Estimation

7.1.9 Estimated Transmission Efficiency

Efficiency of direct coupling is approximately 1.00. Efficiency of belt drives is calculated as follows:

𝐸𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦𝑜𝑓𝐵𝑒𝑙𝑡𝐷𝑟𝑖𝑣𝑒 =𝐷2 ×𝑁2𝐷1 ×𝑁1

× 0.95

Where: D1 = Diameter of driving pulley (mm/in) D2 = Diameter of driven pulley (mm/in) N1 = Speed of driving pulley (rpm)

N2 = Speed of driven pulley (rpm)

0.95 = correction factor

7.1.10 Estimated Pump Efficiency

The Pump Efficiency is the water power divided by the power input to the pump shaft. For pumps installed on tube wells it is impossible to obtain actual power input to the pump. Under these circumstances, pump efficiency can be estimated from pump set, prime mover and transmission efficiencies. In case of XY method Pump Efficiency (%) = (Flow x Total Dynamic Head x 9.81) x 100 / 3600 x Avg. Input KW Sample Case Data:


80

Flow = 78.79 m3/hr Total Dynamic Head= 8.54 m Avg. Input Power = 7.29 kW

7.1.11 Friction Loss in Stuffing Box

Power consumed in overcoming friction in the stuffing box is calculated from friction torque and pump speed. In SI, Friction Power in kW is given by

𝐹𝑟𝑖𝑐𝑡𝑖𝑜𝑛𝑃𝑜𝑤𝑒𝑟 = 2𝛱 × (𝑃𝑢𝑚𝑝𝑆𝑝𝑒𝑒𝑑, 𝑟𝑝𝑚) × (𝐹𝑟𝑖𝑐𝑡𝑖𝑜𝑛𝑇𝑜𝑟𝑞𝑢𝑒,𝑁.𝑚)

60000

In FSS, Friction Power to hp is given by

𝐹𝑟𝑖𝑐𝑡𝑖𝑜𝑛 P𝑜𝑤𝑒𝑟 = 2𝛱 × (𝑃𝑢𝑚𝑝𝑆𝑝𝑒𝑒𝑑, 𝑟𝑝𝑚) × (𝐹𝑟𝑖𝑐𝑡𝑖𝑜𝑛𝑇𝑜𝑟𝑞𝑢𝑒, 𝑙𝑏𝑖𝑛)

33000

The fraction of power consumed in overcoming friction can be presented as a decimal and used to identify tight packing of the stuffing box.

7.1.12 Voltage and Current Imbalance

𝑉𝑜𝑙𝑡𝑎𝑔𝑒𝐼𝑚𝑏𝑎𝑙𝑎𝑛𝑐𝑒 = |𝑉1 − 𝑉2| + |𝑉2 − 𝑉3| + |𝑉3 − 𝑉1|

𝑉1 + 𝑉2 + 𝑉3

Where V1, V2and V3 are the line voltages.

𝐶𝑢𝑟𝑟𝑒𝑛𝑡𝐼𝑚𝑏𝑎𝑙𝑎𝑛𝑐𝑒 = |𝐼1 − 𝐼2| + |𝐼2 − 𝐼3| + |𝐼3 − 𝐼1|

𝐼1 + 𝐼2 + 𝐼3

Where I1, I2and I3 are the line currents

7.2 Diagnosis of Tube well Problems.

Centrifugal pumps are especially sensitive to: i. variations in liquid condition (i.e., viscosity, specific gravity, and

temperature);


81

ii. suction variations, such as pressure and availability of a continuous volume of fluid;

iii. variations in demand. Mechanical failures may occur for a number of reasons. Some are induced by cavitation, hydraulic instability, or other system-related problems. Others are the direct result of improper maintenance. Maintenance-related problems include improper lubrication, misalignment, imbalance, seal leakage, and a variety of others that periodically affect machine reliability.

7.2.1 Cavitation

Cavitation in a centrifugal pump, which has a significant, negative effect on performance, is the most common failure mode. Cavitation not only degrades a pump’s performance, but also greatly accelerates the wear rate of its internal components.

7.2.1.1 Change of Phase

The formation or collapse of vapor bubbles in either the suction piping or inside the pump is one cause of cavitation. This failure mode normally occurs in applications such as boiler feed, where the incoming liquid is at a temperature near its saturation point. In this situation, a slight change in suction pressure can cause the liquid to flash into its gaseous state. Cavitation due to phase change seriously damages the pump’s internal components. Visual evidence of operation with phase-change cavitation is an impeller surface finish like an orange peel. Prolonged operation causes small pits or holes on both the impeller shroud and vanes.

7.2.1.2 Entrained Air/Gas

Pumps are designed to handle gas-free liquids. If a centrifugal pump’s suction supply contains any appreciable quantity of gas, the pump will cavitate. In the example of cavitation due to entrainment, the liquid is reasonably stable, unlike with the change of phase described in the preceding section. Nevertheless, the entrained gas has a negative effect on pump performance. While this form of cavitation does not seriously affect the pump’s internal components, it severely restricts its output and efficiency. The primary causes of cavitation due to entrained gas include: two-phase suction supply, inadequate available net positive suction head (NPSHA), and leakage in the suction-supply system. In some applications, the incoming liquid may contain moderate to high concentrations of air or gas. This may result from aeration or mixing of the liquid prior to


82

reaching the pump or inadequate liquid levels in the supply reservoir. Regardless of the

reason, the pump is forced to handle two-phase flow, which was not intended in its design. Table 7.3: Common Problems with Centrifugal Pumps and Their Causes

The Causes

Insu

ffice

int D

isch

arge

Pre

ssur

e

Inte

rmitt

ent O

pera

tion

Insu

ffici

ent C

apac

ity

No

Liqu

id D

elie

very

Hig

h Be

arin

g Te

mpe

ratu

re

Shor

t Bea

ring

Lift

Shor

t Mec

hani

cal S

eal L

ife

Hig

h Vi

brat

ion

Hig

h N

oise

Lev

el

Exce

ssiv

e Po

wer

Dem

and

Mot

or T

rips

Elev

ated

Mot

or T

empe

ratu

re

Elev

ated

Liq

uid

Tem

pera

ture

Bent ShaftCasing distorted from excessive pipe strainCavitationClogged impellerDriver imbalanceElectrical problems (driver)Entrained air (suction or seal leaks)Hydraulic instabilityImpeller installed backward (double-suction only)Improper mechanical sealInlet strainer partially cloggedInsufficient flow through pumpInsufficient suction pressure (NPSH)Insufficient suction volumeInternal wearLeakage in piping, valves, vesselsMechanical defects, worn, rusted, defective bearingsMisalignmentMisalignment (pump and driver)Mismatched pumps in seriesNoncondensables in liquidObstructions in lines or pump housingRotor imbalanceSpecific gravity too highSpeed too highSpeed too lowTotal system head higher than designTotal system head lower than designUnsuitable pumps in parallel operationViscosity too highWrong rotation


83

7.2.1.3 Turbulent Flow

The effects of turbulent flow (not a true form of cavitation) on pump performance are almost identical to those described for entrained air or gas in the preceding section. Pumps are not designed to handle incoming liquids that do not have stable, laminar flow patterns. Therefore, if the flow is unstable, or turbulent, the symptoms are the same as for cavitation.

7.2.1.4 Symptoms

Noise (e.g., like a can of marbles being shaken) is one indication that a centrifugal pump is cavitating. Other indications are fluctuations of the pressure gauges, flow rate, and motor current, as well as changes in the vibration profile.

7.2.1.5 How to Eliminate

Several design or operational changes may be necessary to stop centrifugal pump cavitation. Increasing the available net positive suction head (NPSHA) above that required (NPSHR) is one way to stop it. The NPSH required to prevent cavitation is determined through testing by the pump manufacturer. It depends upon several factors, including: type of impeller inlet, impeller design, impeller rotational speed, pump flow rate, and the type of liquid being pumped. The manufacturer typically supplies curves of NPSHR as a function of flow rate for a particular liquid (usually water) in the pump’s manual. One way to increase the NPSHA is to increase the pump’s suction pressure. If a pump is fed from an enclosed tank, either raising the level of the liquid in the tank or increasing the pressure in the gas space above the liquid can increase suction pressure. It also is possible to increase the NPSHA by decreasing the temperature of the liquid being pumped. This decreases the saturation pressure, which increases NPSHA. If the head losses in the suction piping can be reduced, the NPSHA will be increased. Methods for reducing head losses include: increasing the pipe diameter; reducing the number of elbows, valves, and fittings in the pipe; and decreasing the pipe length. It also may be possible to stop cavitation by reducing the pump’s NPSHR, which is not a constant for a given pump under all conditions. Typically, the NPSHR increases significantly as the pump’s flow rate increases. Therefore, reducing the flow rate by throttling a discharge valve decreases NPSHR.


84

In addition to flow rate, NPSHR depends on pump speed. The faster the pump’s impeller rotates, the greater the NPSHR. Therefore, if the speed of a variable-speed centrifugal pump is reduced, the NPSHR of the pump is decreased.

7.2.2 Variations in Total System Head

Centrifugal-pump performance follows its hydraulic curve (i.e., head versus flow rate). Therefore, any variation in the total backpressure of the system causes a change in the pump’s flow or output. Because pumps are designed to operate at their Best Efficiency Point (BEP), they become more and more unstable as they are forced to operate at any other point because of changes in total system pressure, or head (TSH). This instability has a direct impact on centrifugal-pump performance, reliability, operating costs, and required maintenance.

7.2.2.1 Symptoms of Changed Conditions

The symptoms of failure due to variations in TSH include changes in motor speed and flow rate. Motor Speed The brake horsepower of the motor that drives a pump is load dependent. As the pump’s operating point deviates from BEP, the amount of horsepower required also changes. This causes a change in the pump’s rotating speed, which either increases or decreases depending on the amount of work that the pump must perform. Flow Rate The volume of liquid delivered by the pump varies with changes in TSH. An increase in the total system back-pressure results in decreased flow, while a back-pressure reduction increases the pump’s output.

7.2.2.2 Correcting Problems

The best solution to problems caused by TSH variations is to prevent the variations. While it is not possible to completely eliminate them, the operating practices for centrifugal pumps should limit operation to an acceptable range of system demand for flow and pressure. If system demand exceeds the pump’s capabilities, it may be necessary to change the pump, the system requirements, or both. In many applications, the pump is either too small or too large. In these instances, it is necessary to replace the pump with one that is properly sized. For the application where the TSH is too low and the pump is operating in run-out condition (i.e., maximum flow and minimum discharge pressure), the system demand can be corrected by restricting the discharge flow of the pump. This approach,


85

called false head, changes the system’s head by partially closing a discharge valve to increase the back-pressure on the pump. Because the pump must follow its hydraulic curve, this forces the pump’s performance back toward its BEP. When the TSH is too great, there are two options: replace the pump or lower the system’s back-pressure by eliminating line resistance due to elbows, extra valves, etc.

7.2.3 Diesel Engine

i. Engine under loaded if less than 60 percent of the rated capacity is utilized. ii. Incomplete combustion if color of exhaust is other than clear or light.

iii. Worn cylinder, pistons and/ or faulty valves if engine compression pressure is less than 2000kPa(300psi).

iv. Faulty injectors and/or engine pulley too large if engine compression pressure is more than 2000 kPa (300 psi) and color of exhaust is medium, dark or very dark.

v. Engine running cold if temperature of water leaving theengineislessthan60°C(140°F).

7.2.4 Pump

i. Poor quality pump and/or worn impeller and/or improper matching of pump to the well and/or improper installation if

a. Size of pump is larger than 120 mm (5 in.) and efficiency less than 0.7, b. Size of pump is 75 to 100 mm (3to4in.) and efficiency is less than 0.65, c. Size of pump is 50 to 65mm(2to2.5in.)and efficiency is less than 0.60and d. Size of pump is 40mm (1.5in.) and efficiency is less than 0.50.

ii. Pump operating under high suction lift if dynamic suction is more than 7m of water column for 1400rpm pumps and more than 5m for 2900 rpm pumps.

iii. Tight stuffing box if more than percent of pump brake power is consumed in overcoming friction in the stuffing box.

7.2.5 Transmission

i. High belt slip if efficiency is less than 0.85 for flat belts. ii. High belt slip if efficiency is less than 0.90 for v-belts.

7.2.6 Piping System

i. Under-sized discharge pipe if: a. Flow velocity is greater than 2m/s (6.5ft/s) for pipes upto75mm(3in.)in

diameter and


86

b. Flow velocity is greater than 3 m/s (IO ft/s) for 100 mm (4in.)and larger pipes.

ii. Under-sized suction pipe if: a. Flow velocity is greater than l.5m/s (5 ft/s) for pipes up to 75mm (3in.) in

diameter and b. Flow velocity is greater than 2 m/s (6.5 ft/s) for 100mm(4in.)and larger

pipes. iii. Un-necessary high discharge level if difference in elevations of discharge and water

course levels is more than 1m (3ft). iv. Excessive head loss in piping system if piping efficiency is less than 0.85.

7.2.7 Well

i. Deep water table if pump is located more than 6 m (20 ft)above the static water level in case of open wells and morethan 3m(10ft)for drilled wells.

ii. Strainer chocked if drawdown in drilled wells is more than 4 m (13ft)

7.3 Format for Audit Report

Format for report of detailed tube well energy audits is presented below

REPORT OF DETAILED TUBEWELL ENERGY AUDIT

Village Name:

Audit Team Name:

Audit Date: Arrival Time:

Name of Farmer: Address:

District: Cell Number:

Well Type

Existing Pump Type

Piping Type (Delivery)


87

Piping Type (Suction)

Filter Type

Drive Type

Year of Installation/Age of:

Tubewell

Bore

Filter

General Condition:

Civil Works

Motor Control Unit

Filter Condition

Safety Aspects:

Electrical Connections

Pump Shelter

Retaining Walls

In case of Turbine Pump

Housing/Blind Pipe (casing) Length

Housing/Blind Pipe (casing) Diameter

In case of Centrifugal Pump

Well Diameter

In case of Belt Drive


88

Pulley Sizes

Piping

Diameter of discharge pipe, in

Diameter of suction pipe, in

Pump Set Name Plate Data

Pump Motor

Manufacturer

Year of Manufacturing

Model Number/Serial No.

Pump Size /Motor Capacity (In/HP)

Rated Efficiency (%)

Head/Operative Head Range (ft)

Impeller Diameter (In)

Discharge (Cusec)/GPM

Voltage/Voltage Band (V)

Full Load Amperes (A)

Motor Observations

Voltage (V)

Current (A)

Input Power (kW)

Power Factor (PF)


89

Capacitor Availability

Capacity of Capacitor (kVAr)

Engine Observations

Fuel Consumption by diesel engine

Color of diesel engine exhaust

Temperature of coolant entering diesel engine

Temperature of coolant leaving diesel engine

Temperature of exhaust of diesel engine

Pump Observations

Well/Bore Depth

Pumping Level

Suction Diameter

Delivery Diameter

Depth of Pump Installation

Drawdown

Suction Length

Delivery Length

Water Table Depth / Static Water Level

Suction Head

Delivery Head

Length of Filter


90

Diameter of the Filter

Internal Diameter of the Bore Casing (in)

Types and Number of Bends and Valves in Delivery Pipe

Type and Number of Bends and Valves in Suction Pipe

XY Measurements

Horizontal Distance (X) at drop point:

Vertical Distance (Y)

Inside Diameter of delivery pipe

Calculations

Total Dynamic head

Flow

Water power

Estimated diesel engine efficiency

Estimated electric motor efficiency :

Estimated transmission efficiency:

Estimated pump efficiency :

Pump set efficiency:

Piping efficiency:

General Observations

Prime Mover

Pump


91

Transmission

Piping

Well

Sample filled audit reports along with the data analysis have been reproduced in Annex V.


92

8 BEST PRACTICES FOR ENERGY EFFICIENT IRRIGATION AND TRACTOR FUEL EFFICIENCY

8.1 Crop and Irrigation System Water Requirements

Water to plant is like blood to human: a nutrition carrier. Blood is recycled within our body whereas water is recycled through atmosphere. Crop plant requires as much water as is evaporated through plant leaves, noting more. If evaporation is more than what roots can supply, plant will wilt and die. If atmosphere is cooler and or with high humidity, evaporation through leaves will be lower, therefore plant water requirement is reduced. Crop plants unlike human don’t have pump (heart in case of mammals), therefore water rise in hairline roots by capillary action and sucked up by a vacuum created in tinny tubes by evaporation. Distilled water is evaporated through leaves and nutrition that dissolved during irrigation process when water saturates in soil, remains in the plant and is absorbed by plant tissues for growth. Water that passes through the roots and evaporates from leaves is all that is required to grow a healthy crop, rest of it is wasted by evaporation in atmosphere adding salt in soil increasing salinity. pH has increased from 7 to 9, in many cases (1 point rise means 100 times more). Excessive use of water is culprit of declining yields in spite the use of better seeds and intensive application of inorganic inputs.

8.1.1 Crop Evapotranspiration

Plants need water for growth and cooling. Small apertures (stomata) on the upper and lower surfaces of the leaves allow for the intake of carbon dioxide required for photosynthesis and plant growth. Water vapor is lost to the atmosphere from the plant leaves by a process called transpiration. Direct water evaporation also occurs from the plant leaves and from the soil surface. The total water used by the specific crop, which includes direct evaporation from plant leaves and the soil surface and transpiration, is called crop evapotranspiration (ETc).

8 . 1 .2 Irrigation F requ en c y

How much and how often irrigation water must be applied depends on the soil AWC in the actual plant root zone, the crop grown and stage of growth, the rate of evapotranspiration of the crop, the planned soil Management Allowable Depletion (MAD) level, and effective


93

rainfall. More simply put; it depends on the crop, soil, and climate. Once a MAD is selected, determining when to irrigate simply requires estimation or measurement of when the soil moisture reaches that level. Coarse textured and shallow soils must be irrigated more frequently than fine textured deep soils because fine textured deep soils store more available water. The moisture use rate varies with the crop and soil. It increases as the crop area canopy increases, as humidity decreases and as the days become longer and warmer.

8.1.3 Net Irrigation Requirement

The net amount of water to be replaced at each irrigation is the amount the soil can hold between field capacity and the moisture level selected when irrigation is needed (MAD). Maintaining the same soil moisture level throughout the growing season is not practical and probably not desirable. Ideally, an irrigation is started just before the selected MAD level is reached or when the soil will hold the irrigation application plus expected rainfall. The net amount of water required depends on soil AWC in the plant root zone and the ability of a particular crop to tolerate moisture stress. If the MAD level selected is 40 percent of AWC in the root zone (Soil-water Deficit = 40%), it is necessary to add that amount of water to bring the root zone up to field capacity. In semihumid and humid areas, good water managers do not bring the soil to field capacity with each irrigation, but leave room for storage of expected rainfall. When rainfall does not occur, the irrigation frequency must be shortened to keep the soil moisture within the MAD limit.

8.1.4 Gross Irrigation Requirement

The gross amount of water to be applied at each irrigation is the amount that must be applied to assure enough water enters the soil and is stored within the plant root zone to meet crop needs. No irrigation system that fully meets the season crop evapotranspiration needs is 100 percent efficient. Not all water applied during the irrigation enters and is held in the plant root zone. Also, all irrigation systems have a distribution uniformity less than 100 percent. Applying too much water too soon (poor irrigation water management) causes the greatest overuse of water. Irrigation systems and management techniques are available that reduce the avoidable losses. Unavoidable losses are caused by: • Unequal distribution of water being applied over the field. • Deep percolation below the plant root zone in parts of the field. • Translocation or surface runoff in parts of the field. • Evaporation from the soil surface; flowing and ponded water. • Evaporation of water intercepted by the plant canopy under sprinkler systems. • Evaporation and wind drift from sprinklers or spray heads.


94

• Non-uniform soils.

8.2 Water Requirement of Different Crops

The agriculture of Pakistan is characterized by two main cropping seasons, namely, the Kharif (summer crops) from April to September; and Rabi (winter crops) from October to March. Wheat is the main crop of Rabi season, while rice, maize, sugarcane and cotton are considered the major crops of Kharif. Mono cropping, sequence cropping, mixed cropping, inter-cropping and relay cropping systems are practiced by growers (farmers), especially those with small holdings, to maximize crop production per unit area. The cropping pattern is largely determined by water availability and the climatic conditions as adaptation of crops. Water requirement of different crops under different irrigation regimes has been reproduced in the following table:

Table 8.1: Water Requirement of Different Crops under Various Irrigation Options

Purpose of the Table 8.1 is to highlight water savings with change of water application method. In ideal case it must be appreciated that in each case crop water requirement is equal to water transpiration through leaves, rest of the water evaporates in to atmosphere leaving behind salts to increase salinity (pH).By changing irrigation method of irrigation we save water from going beyond root zone deep in the soil and evaporation in to air. In case of rice, soil is a major variant: most of places where rice is planted, soil has low water absorption capacity Therefore, water inundation is considered necessary. In such soils roots don’t need to outreach for water, therefore, water inundation is more productive. We have to understand soil, water and plant relationship. Soil composition determines consistent water availability and roots behave accordingly to absorb water-nutrient solution for development and production.


95

Whereas, when rice is planted in a loam soil, crop production on raised bed in a moist soil is more productive, there is no doubt about it. This means rice plant doesn’t need water more than it transpires provided it can be made available consistently, like every other plant. Rice can’t be compared with wheat because of temperature and humidity levels during crop life. Wheat is a winter crop when transpiration is much lower due to low temperatures, while rice is a summer crop growing in around 40 C temperature. We are going through an evolution, changing our mindset about rice being a crop that grows best in water inundation. Sugarcane is a long duration crop (almost a yearlong or even more), meant for tropical climate with moderate temperatures and high humidity. In semitropical areas such as Punjab, plant go under stress in summer (above 35C) and in cold (lower than 10C) especially under frost conditions. Sugarcane has much more biomass with water retention, therefore more water demanding. Comparing rice with wheat and sugarcane is not pertinent because of diverse factors.

8.3 Irrigation Methods

Irrigation systems should have the capability to apply the amount of water needed by the crop in addition to precipitation. Irrigation applications should occur in a uniform and timely manner while minimizing losses and damage to soil, water, air, plant, and animal resources. Irrigation application method and system selection should result in optimum use of available water. The selection should be based on a full awareness of management considerations, such as water source and cost, water quantity and quality, irrigation effects on the environment, energy availability and cost, farm equipment, product marketability, and capital for irrigation system installation, operation, and maintenance. The four basic irrigation methods, along with the many systems to apply irrigation water, include: surface, sprinkle, micro, and subirrigation:

8.3.1 Surface Irrigation

Water is applied by gravity across the soil surface by flooding or small channels (i.e., basins, borders, paddies, furrows, rills, corrugations). The surface irrigation method is the application of irrigation water to the soil surface by gravity. Application systems vary. It is necessary to understand that a volume balance of water in a surface irrigation system must


96

exist at all times. All water introduced at the head end of the system must be accounted for in surface flow or storage, infiltration, runoff, and a very small amount lost to evaporation during the time of irrigation. The amount lost to evaporation is generally neglected. Infiltration volume can be measured by changes in soil-water content in the root zone before and after irrigation, with the remainder going to deep percolation below the plant root zone.

8.3.2 High Efficiency Irrigation Systems (HEIS)

The terminology HEIS is used because traditional surface irrigation or flood irrigation mainly used by Pakistani farmers are not efficient and losing tremendous amount of water as compared to sprinkle and trickle system. So for adopting sprinkle and trickle system, terminology of HEIS is used as they are more efficient than surface irrigation system.

8.3.2.1 Sprinkle Irrigation System

Water is applied at the point of use by a system of nozzles (impact and gear driven sprinkler or spray heads) with water delivered to the sprinkler heads by surface and buried pipelines, or by both. Sprinkler irrigation laterals are classed as fixed set, periodic move, or continuous or self move. Sprinkler irrigation systems include solid set, hand move laterals, sideroll (wheel) laterals, center pivot, linear move (lateral move), and stationary and traveling gun types. Low Energy Precision Application (LEPA) and Low Pressure In Canopy (LPIC) systems are included with sprinkler systems because they use center pivots and linear move irrigation systems. This is mostly suitable to crops like wheat. Its major types are

i. Rain Gun System ii. Centre Pivot System

Rain Gun System It supplies water in the form of rain drops through a big gun mounted on the stand. There are three types of this systems: Permanently installed (The system in which

Exhibit 8.1: Surface Irrigation

Exhibit 8.2: Rain Gun System


97

pipes, laterals, sprinklers all are permanently installed), Semi Permanent (The system in which main line is installed with laterals, while sprinkle gun is movable), Potable system (The system in which laterals and sprinkle gun both are movable, only mainline is permanently installed) Centre Pivot System This is a system in which aluminum pipe is installed with sprinklers are mounted on it, and it moves in a circular shape, thus wetting the surface in a rain drop shape in an angular directions.

8.3.2.2 Micro Irrigation

Water is applied to the point of use through low pressure, low volume discharge devices (i.e., drip emitters, line source emitters, micro spray and sprinkler heads, bubblers) supplied by small diameter surface or buried pipelines. Three types are given below Drippers: They supplying water to the root zone in a drop like form.In online drippers These are placed manually on installed plastic pipes in the field, and this system mainly used for orchards having long spaces. In In Line Drippers, drippers are mounted in manufactured pipes through manufacturing processes. These are mounted in short spaces and mainly suitable to vegetables. Bubblers: It supplies water to the root zone in small rain drops shape. Discharge of this system is

Exhibit 8.3: Centre Pivot System

Exhibit 8.4: Drippers

Exhibit 8.5: Bubbler


98

more than drippers and can be used for orchards having creeping vegetables. Micro Tubes: Micro tubes are small dimensional plastic tubes mounted on installed pipes and its discharge is less than drippers and bubblers, suitable for low water requirement crops.

8.3.2.3 Sub-Irrigation

Water is made available to the crop root system by upward capillary flow through the soil profile from a controlled water table.

8.4 Tractor Fuel Efficiency

8.4.1 Fuel Efficiency Factors for Tractor Selection

When considering the addition of a new or used tractor for the farm equipment fleet, consider the operations for which it will be used. A larger tractor is sometimes selected for adequate weight (braking) or hydraulic power capacity required to lift or operate equipment. However, before acquiring a larger or heavier tractor, consider that at least seven percent of tractor power is commonly required to overcome rolling resistance created by the weight of the tractor. Tractor test data can be used to estimate fuel consumption and to aid tractor selection. To evaluate fuel efficiency, it is helpful to understand tractor test procedures, fuel efficiency measurements, and specific values found in tractor test reports.

8.4.2 Proper Gear Selection

Farmers are found operating their tractors in low gears which resulted in low average speeds (5.9 km/h) against recommended speed of 7-9km/h. As a result fuel efficiency gets very low. Gear up/throttle down strategy is advisable to optimize fuel efficiency and productivity (It is suggested that engine RPM should be kept 80% of the rated engine RPM during ploughing while the selection of gear, High-1 or 2, be used to increase the speed of tractor not engine RPM. e.g. MF-240′s rated RPM is 2250 RPM.

Exhibit 8.6: Micro-tubes


99

8.4.3 Ballasting Tractors for Fuel Efficiency

Most tractor operators know proper ballasting is important to transfer as much engine power as possible to the drawbar. Exactly how to accomplish this ballasting, however, frequently remains a mystery. Too little weight or ballast results in excessive drive wheel slippage and an obvious waste of fuel. Conversely, carrying too much ballast on a tractor dramatically lowers wheel slip but results in greater rolling resistance as the tractor sinks too far into the soil, causing wheels to be constantly climbing out of a deep rut. To maximize transfer of power from drive axles to the drawbar, optimum amounts of wheel slippage depend on the soil surface. On firm, untilled soil, wheel slip should be in a range of about 6–13%. More slippage is allowed on a tilled surface, 8–16%, with slightly more yet on a non-cohesive sandy soil. Conversely, optimal wheel slip is about 4–8% on concrete. Since only wheels on powered axles supply traction, it’s also important to distribute ballast properly between front and rear axles. Optimal weight split between axles is affected by tractor style and whether the attached implement is pulled or mounted. Equipment such as manure tank wagons and grain carts have significant tongue weight and can be considered “fully mounted” drawbar loads when calculating the proper weight split between front and rear axles because they add weight to the tractor’s rear axle similar to fully mounted implements.

8.4.4 Tire Inflation

Tractor rear tires are usually found to be over inflated by 20-22psi. Study suggested adjustment of tire inflation pressure to the recommended level that is 12-14 psi. This will bring the tractor slip in the range of 7 to 11% in unplowed fields and 10-15% in plowed fields compared to 12.5-16.6% in the unplowed field and plowed field respectively It’s important to know axle weight in order to calculate the load each tire carries. Correct tire inflation pressure for the load carried can be found from load and inflation tables available on the tire manufacturer’s web site or in the equipment operator’s manual. Correct inflation pressure for a given weight depends on tire size, whether the tire is used as a single or dual, and if the tire will be used at high speed (e.g. greater than 25 mi/h). Because underinflated tires wear sidewalls quickly, a natural tendency is to overinflate tires for a given load. Unfortunately, over-inflation reduces contact of the tire’s lugs with the soil and results in excessive slippage and increased fuel use. Following Exhibit shows fuel used for primary fall tillage operations with five different tractors when tires were inflated at a relatively high 24 psi inflation pressure and also with tires inflated at 14 psi pressure, which was more appropriate for the load these tires were carrying.


100

Exhibit 8.7Impact of Tyre Inflation on Fuel Efficiency

8.4.5 Tractor Maintenance to Conserve Energy

Efficient combustion of fuel and air inside the tractor’s engine directly affects the availability of engine power and fuel efficiency. Filters, usually both primary and secondary, are used to collect small particles and impurities to protect close machine tolerances inside the engine from wear. To maintain a proper fuel and air mixture in the engine cylinders, filters must be replaced on a periodic basis as restricted flow starts to impact combustion efficiency. Studies have shown that after the filters were replaced, average tractor power output increased by 3.5% without further modifications. Combustion efficiency is significantly affected by maintaining engine operating temperature within a certain range. In addition, engine wear increases rapidly if lubricating oil breaks down at high temperatures or water condenses at lower temperatures and reacts with sulfur compounds to create corrosion. Engine operating temperature should be carefully monitored. Thermostats on many engines open around 180°F, but consult the operation manual. Cooling system maintenance should include periodic inspection and replacement of coolant and possible replacement of the engine thermostat if it is defective in maintaining proper engine temperature. Letting a diesel tractor engine idle for a few minutes following hard work allows circulation of cooling oil.

8.4.6 Efficient Soil Tillage Systems

Soil tillage is one of the most energy-intensive processes in agricultural production. Soil tillage is one of the operations that requires the most direct energy in arable production, wherein even 55-65% of the direct field energy consumption should be accorded to tillage of heavy clay soils. In Slovenian agriculture, for each hectare 5.9 GJ energy of diesel fuel is used on average: 38% for basic soil preparation with mouldboard plough and harrow, 32% for harvesting, 20% for application of fertilizer and spraying and 10% for transport and


101

irrigation. It is the most expensive and complicated operation, being organizationally slow, fuel demanding, labor-difficult and ecologically unfavorable in crop production. It is clearly recognized that the application of an energy-saving method can make an effective contribution to the economy. Although it is known that the use of conservation and direct drilling can save an enormous quantity of energy and labor in comparison to conventional tillage. The main reason for this situation lies with the farmers, who are traditionally conservative and unwilling to accept new technologies.

The conventional tillage (CT) system is based on a high intensity of soil engagement and inversion of the soil with mouldboard plough. Conversely, the conservation tillage systems try to disturb the soil as little as possible to conserve its natural structure, leave the maximum vegetalresidue next to the soil surface and build a rough surface. Typical machines are hereby chisels and wing-tine cultivators.

The Japanese have reported that they experienced about 15.0-29.0% fuel savings after the introduction of a reduced tillage cropping system that had been adopted instead of the CT system. Average fuel consumption depends on soil texture, tillage system and differences within stubble crops (winter wheat, barley) and row crops (maize, soybean). For this reason, significant differences in fuel consumption were reported whenever maize was produced under conventional tillage (60.99 l ha-1), reduced tillage (34.81 l ha-1) and no tillage (7.35 l ha-1) on silty loam soil in Eastern Slavonia.


102

Major Reference

• Hydrocarbon development institute of Pakistan, Pakistan Energy Yearbook , 2013

• Igor J. Karassik, Joseph P. Messina, Paul Cooper & Charles C. Heald, Pump Handbook,3rd Edition, 2007

• National Energy Conservation Centre, Tubewell Energy Audit Manual, 1989

• Nazir Ahmad, Ground Water Resources of Pakistan, 1995

• Piper, Operations and Maintenance Manual for Energy Management, 1999

• Turner& Doty, Energy Manager Handbook, 6th Edition, 2006

• U.S. Department of Energy’s Industrial Technologies Program, Improving PumpingSystem Performance: A Sourcebook for Industry, 2nd Edition, 2006

• United States Department of Agriculture, National Engineering Handbook: IrrigationGuide, 1997

• www.energyefficiencyasia.org

http://www.energyefficiencyasia.org/

Annex-I

Annex I - 1 ENERCON, The National Energy Conservation Centre

Annex-II

Annex II - 1 ENERCON, The National Energy Conservation Centre

Annex II - 2 ENERCON, The National Energy Conservation Centre

Annex-III

Annex-III - 1 ENERCON, The National Energy Conservation Centre

50 Hz

submersible pumpsingle impeller performance curve with trimming

tolerances according to ISO 9906 annex A

55

65

75

85

0 1000 2000 3000 4000

R0 (187 mm)R2 (183.3 mm)R4 (179.5 mm)R6 (175.8 mm)R8 (172 mm)R10 (168.3 mm)R12 (164.6 mm)R14 (160.8 mm)R16 (157.1 mm)R18 (153.3 mm)R20 (149.6 mm)

5

10

15

20

0 1000 2000 3000 4000


0

10

20

30

40

0 1000 2000 3000 40000

20

40

60

80

100

120

140

0 20 40 60 80 100 120 140 160 180 200 220 240


H (m

)

Q (l/min)

Q (l/min)

η (%)

kW

Q (l/min)

2855 rpm

FX10-200H

(ft)

Q (m3/h)


50 Hz

submersible pumpsingle impeller performance curve


20

40

60

80

100

0 150 300 450 600

0.0

1.0

2.0

0 150 300 450 600

0

5

10

15

20

0 150 300 450 600

H (meter)

Q (l/min)

Q (l/min)

η (%)

kW

Q (l/min)

2855 rpm

AP6E


50 Hz



20

40

60

80

100

0 150 300 450 600

0.0

1.0

2.0

0 150 300 450 600

0

5

10

15

20

0 150 300 450 600

H (meter)

Q (l/min)

Q (l/min)

η (%)

kW

Q (l/min)

2855 rpm

AP6F


50 Hz



20

40

60

80

100

0 200 400 600 800

0.0

1.0

2.0

3.0

0 200 400 600 800

0

5

10

15

20

0 200 400 600 800

H (meter)

Q (l/min)

Q (l/min)

η (%)

kW

Q (l/min)

2855 rpm

AP6H


50 Hz



20

40

60

80

100

0 300 600 900 1200

0.0

1.0

2.0

3.0

0 300 600 900 1200

0

5

10

15

20

0 300 600 900 1200

H (meter)

Q (l/min)

Q (l/min)

η (%)

kW

Q (l/min)

2855 rpm

FX6-45


50 Hz



20

40

60

80

100

0 300 600 900 1200

0.0

2.0

4.0

0 300 600 900 1200

0

5

10

15

20

0 300 600 900 1200

H (meter)

Q (l/min)

Q (l/min)

η (%)

kW

Q (l/min)

2855 rpm

FX6-55


50 Hz



20

40

60

80

100

0 300 600 900 1200 1500

0.0

2.0

4.0

0 300 600 900 1200 1500

0

5

10

15

20

0 300 600 900 1200 1500

H (meter)

Q (l/min)

Q (l/min)

η (%)

kW

Q (l/min)

2855 rpm

FX6-65


50 Hz



20

40

60

80

100

0 400 800 1200 1600 2000

0.0

4.0

8.0

0 400 800 1200 1600 2000

0

10

20

30

0 400 800 1200 1600 2000

H (meter)

Q (l/min)

Q (l/min)

η (%)

kW

Q (l/min)

2855 rpm

FX8-90


50 Hz



20

40

60

80

100

0 500 1000 1500 2000 2500

2.0

6.0

10.0

0 500 1000 1500 2000 2500

0

10

20

30

0 500 1000 1500 2000 2500

H (meter)

Q (l/min)

Q (l/min)

η (%)

kW

Q (l/min)

2855 rpm

FX8-110


50 Hz



20

40

60

80

100

0 500 1000 1500 2000 2500 3000

0.0

8.0

16.0

0 500 1000 1500 2000 2500 3000

0

10

20

30

0 500 1000 1500 2000 2500 3000

H (meter)

Q (l/min)

Q (l/min)

η (%)

kW

Q (l/min)

2855 rpm

FX8-130


50 Hz



20

40

60

80

100

0 1000 2000 3000 4000 5000

0.0

15.0

30.0

0 1000 2000 3000 4000 5000

0

20

40

60

0 1000 2000 3000 4000 5000

H (meter)

Q (l/min)

Q (l/min)

η (%)

kW

Q (l/min)

2855 rpm

FX10-240


4

10

22

12

16

18

Hm

Hft

U.S.gpm

26

8

0 200 400 600 800 16001000 1200

Qm /h3

0 250 300 35050 100 150 200

1400

24

20

14

6 20

30

40

50

60

70

80263

253

243

233

62.369.9

78

81.3

82.7

83.9

84

82.3

78

73.9

68.2

223

74.6

74.6

74.6

74.6

62.3

62.3

62.3

62.3

78

78

78

78

81.3

81.3

81.3

82.7

82.7

52.4

74.6

52.4

52.4

52.4

52.4

69.9

69.9

69.9

69.9

68.2

68.2

68.2

68.2

73.9

73.9

73.9

73.9

78

78

78

78

82.3

82.3

82.3

82.3

81.3

82.7

82.7

125FCM-2591460RPMCENTRIFUGAL

0 0

HP

10

20

10

Kw

5

15

15

5

20

25

U.S.gpm0 200 400 600 800 16001000 1200 1400

253

263

243

233

223


100FCH-3201460RPM

40

20

Hm

0

10

15

25

35

30

100

Hft

50 100 200 300 400 500 600 700 800 900 1000

20 40 60 80 120 140 160 180 200 220

20

40

50

60

70

80

90

100

110

120

130

30

CENTRIFUGAL

Qm /h3

U.S.gpm

335

325

315

305

63.8

68.8

72.8

75.7

76

75.5

75.5

75.5

75.5

76

76

76

75.7

75.7

75.7

72.8

72.8

72.8

68.8

68.8

68.8

63.8

63.8

63.8

HP

0

5

10

15

20

Kw

0 100 200 300 400 500 600 700 800 900 1000

5

10

15

20

25

0

U.S.gpm

335

325

315

305


100FCM-2591460RPM

10

12

24

20

60

30

40

Hm

0

50

0 100 200 400300 500 900600 700 800

8

14

16

18

22

70

4020 60 80 100 200140 160 180120

26575

35

45

55

65

Hft

25

2

6

8

4

KwHP

0 100 200 400300 500 900600 700 800

10

4

6

8

10

12

2

CENTRIFUGAL

Qm /h3

U.S.gpm

U.S.gpm

255

245

235

255

265

245

235

68.2

60.7

67.8

72.5

74.2

72.5

70.8

68.2

68.2

68.2

70.8

70.8

70.8

72.5

72.5

72.5

74.2

72.5

72.5

72.5

60.7

60.7

60.7

67.8

67.8

67.8


Annex-IV

=

Annex - IV : 1 ENERCON, The National Energy Conservation Centre

Annex-V

Friction Loss Data for Different Pipe Sizes

Nominal Pipe Size: 2"

• Inside Diameter: 0.053 m (2.1 inches)

Flow Velocity Pressure Drop (m3/s) (liter/s) (US

gpm) (m/s) (ft/s) (Pa/100m) (mmH2O/100m) (psi/100ft) (ftH2O/100ft)

4.0E-4 0.4 6.3 0.181 0.59 1053 107 0.047 0.107 5.0E-4 0.5 7.9 0.23 0.74 1548 158 0.068 0.158 6.0E-4 0.6 9.5 0.27 0.89 2159 220 0.095 0.22 7.0E-4 0.7 11.1 0.32 1.04 2844 290 0.126 0.29 8.0E-4 0.8 12.7 0.36 1.19 3591 366 0.159 0.37 9.0E-4 0.9 14.3 0.41 1.34 4545 463 0.2 0.46 0.0010 1.0 15.9 0.45 1.49 5418 552 0.24 0.55 0.0011 1.1 17.4 0.5 1.64 6556 668 0.29 0.67 0.0012 1.2 19.0 0.54 1.78 7523 767 0.33 0.77 0.0013 1.3 21 0.59 1.93 8829 900 0.39 0.9 0.0014 1.4 22 0.63 2.1 10240 1044 0.45 1.05 0.0015 1.5 24 0.68 2.2 11320 1154 0.5 1.16 0.0016 1.6 25 0.73 2.4 12879 1313 0.57 1.31 0.0017 1.7 27 0.77 2.5 14539 1483 0.64 1.48 0.0018 1.8 29 0.82 2.7 16300 1662 0.72 1.66 0.0019 1.9 30 0.86 2.8 17463 1781 0.77 1.78 0.0020 2.0 32 0.91 3.0 19350 1973 0.86 1.98 0.0030 3.0 48 1.36 4.5 41795 4262 1.85 4.3 0.0040 4.0 63 1.81 5.9 71207 7261 3.1 7.3 0.0050 5.0 79 2.3 7.4 111260 11345 4.9 11.4 0.0060 6.0 95 2.7 8.9 153249 15627 6.8 15.6 Nominal Pipe Size: 2 1/2"




7.0E-4 0.7 11.1 0.22 0.74 1239 126 0.055 0.126 8.0E-4 0.8 12.7 0.26 0.84 1565 160 0.069 0.16 9.0E-4 0.9 14.3 0.29 0.95 1915 195 0.085 0.195 0.0010 1.0 15.9 0.32 1.05 2365 241 0.105 0.24 0.0011 1.1 17.4 0.35 1.16 2762 282 0.122 0.28

Annex V : 1 ENERCON, The National Energy Conservation Centre

0.0012 1.2 19.0 0.38 1.26 3288 335 0.145 0.34 0.0013 1.3 21 0.42 1.37 3720 379 0.164 0.38 0.0014 1.4 22 0.45 1.47 4315 440 0.191 0.44 0.0015 1.5 24 0.48 1.58 4953 505 0.22 0.51 0.0016 1.6 25 0.51 1.68 5427 553 0.24 0.55 0.0017 1.7 27 0.55 1.79 6127 625 0.27 0.63 0.0018 1.8 29 0.58 1.89 6869 700 0.3 0.7 0.0019 1.9 30 0.61 2.0 7653 780 0.34 0.78 0.0020 2.0 32 0.64 2.1 8480 865 0.37 0.87 0.0030 3.0 48 0.96 3.2 17612 1796 0.78 1.8 0.0040 4.0 63 1.28 4.2 30005 3060 1.33 3.1 0.0050 5.0 79 1.6 5.3 46883 4781 2.1 4.8 0.0060 6.0 95 1.92 6.3 64576 6585 2.9 6.6 0.0070 7.0 111 2.2 7.4 87896 8963 3.9 9.0 0.0080 8.0 127 2.6 8.4 114802 11706 5.1 11.7 0.0090 9.0 143 2.9 9.5 138692 14142 6.1 14.2 0.01 10.0 159 3.2 10.5 171225 17460 7.6 17.5 Nominal Pipe Size: 3"




0.0012 1.2 19.0 0.25 0.82 1170 119 0.052 0.119 0.0013 1.3 21 0.27 0.89 1326 135 0.059 0.135 0.0014 1.4 22 0.29 0.96 1538 157 0.068 0.157 0.0015 1.5 24 0.31 1.03 1766 180 0.078 0.18 0.0016 1.6 25 0.33 1.1 1937 198 0.086 0.198 0.0017 1.7 27 0.36 1.17 2187 223 0.097 0.22 0.0018 1.8 29 0.38 1.24 2452 250 0.108 0.25 0.0019 1.9 30 0.4 1.3 2631 268 0.116 0.27 0.0020 2.0 32 0.42 1.37 2915 297 0.129 0.3 0.0030 3.0 48 0.63 2.1 6054 617 0.27 0.62 0.0040 4.0 63 0.84 2.7 10314 1052 0.46 1.05 0.0050 5.0 79 1.05 3.4 16116 1643 0.71 1.64 0.0060 6.0 95 1.26 4.1 22197 2263 0.98 2.3 0.0070 7.0 111 1.46 4.8 30213 3081 1.34 3.1 0.0080 8.0 127 1.67 5.5 39462 4024 1.74 4.0 0.0090 9.0 143 1.88 6.2 47674 4861 2.1 4.9 0.01 10.0 159 2.1 6.9 58857 6002 2.6 6.0 0.011 11.0 174 2.3 7.6 71217 7262 3.1 7.3 0.012 12.0 190 2.5 8.2 84754 8642 3.7 8.7 0.013 13.0 206 2.7 8.9 99468 10143 4.4 10.2 0.014 14.0 222 2.9 9.6 115360 11763 5.1 11.8


0.015 15.0 238 3.1 10.3 126122 12861 5.6 12.9 0.016 16.0 254 3.3 11.0 143499 14633 6.3 14.6 0.017 17.0 269 3.6 11.7 161997 16519 7.2 16.5 0.018 18.0 285 3.8 12.4 181616 18519 8.0 18.5





0.0030 3.0 48 0.37 1.2 1649 168 0.073 0.168 0.0040 4.0 63 0.49 1.61 2814 287 0.124 0.29 0.0050 5.0 79 0.61 2.0 4214 430 0.186 0.43 0.0060 6.0 95 0.73 2.4 5805 592 0.26 0.59 0.0070 7.0 111 0.86 2.8 7901 806 0.35 0.81 0.0080 8.0 127 0.98 3.2 10319 1052 0.46 1.05 0.0090 9.0 143 1.1 3.6 12467 1271 0.55 1.27 0.01 10.0 159 1.22 4.0 15391 1569 0.68 1.57 0.011 11.0 174 1.35 4.4 18623 1899 0.82 1.9 0.012 12.0 190 1.47 4.8 22163 2260 0.98 2.3 0.013 13.0 206 1.59 5.2 24772 2526 1.09 2.5 0.014 14.0 222 1.71 5.6 28730 2930 1.27 2.9 0.015 15.0 238 1.84 6.0 32981 3363 1.46 3.4 0.016 16.0 254 1.96 6.4 37525 3826 1.66 3.8 0.017 17.0 269 2.1 6.8 42362 4320 1.87 4.3 0.018 18.0 285 2.2 7.2 47493 4843 2.1 4.8 0.019 19.0 301 2.3 7.6 52916 5396 2.3 5.4 0.02 20 317 2.4 8.0 58633 5979 2.6 6.0 0.03 30 476 3.7 12.0 125328 12780 5.5 12.8 Nominal Pipe Size: 5"




0.0050 5.0 79 0.39 1.27 1413 144 0.062 0.144 0.0060 6.0 95 0.47 1.53 1950 199 0.086 0.199 0.0070 7.0 111 0.54 1.78 2539 259 0.112 0.26 0.0080 8.0 127 0.62 2.0 3316 338 0.147 0.34 0.0090 9.0 143 0.7 2.3 4197 428 0.185 0.43 0.01 10.0 159 0.78 2.5 4946 504 0.22 0.5


0.011 11.0 174 0.85 2.8 5984 610 0.26 0.61 0.012 12.0 190 0.93 3.1 7122 726 0.31 0.73 0.013 13.0 206 1.01 3.3 8358 852 0.37 0.85 0.014 14.0 222 1.09 3.6 9232 941 0.41 0.94 0.015 15.0 238 1.17 3.8 10598 1081 0.47 1.08 0.016 16.0 254 1.24 4.1 12058 1230 0.53 1.23 0.017 17.0 269 1.32 4.3 13612 1388 0.6 1.39 0.018 18.0 285 1.4 4.6 15261 1556 0.67 1.56 0.019 19.0 301 1.48 4.8 17004 1734 0.75 1.74 0.02 20 317 1.55 5.1 18840 1921 0.83 1.92 0.03 30 476 2.3 7.6 40271 4106 1.78 4.1 0.04 40 634 3.1 10.2 67826 6916 3.0 6.9 0.05 50 793 3.9 12.7 105978 10807 4.7 10.8 0.06 60 951 4.7 15.3 152608 15561 6.7 15.6





0.0070 7.0 111 0.38 1.23 1053 107 0.047 0.107 0.0080 8.0 127 0.43 1.41 1315 134 0.058 0.134 0.0090 9.0 143 0.48 1.59 1665 170 0.074 0.17 0.01 10.0 159 0.54 1.76 2055 210 0.091 0.21 0.011 11.0 174 0.59 1.94 2374 242 0.105 0.24 0.012 12.0 190 0.64 2.1 2825 288 0.125 0.29 0.013 13.0 206 0.7 2.3 3316 338 0.147 0.34 0.014 14.0 222 0.75 2.5 3845 392 0.17 0.39 0.015 15.0 238 0.81 2.6 4204 429 0.186 0.43 0.016 16.0 254 0.86 2.8 4783 488 0.21 0.49 0.017 17.0 269 0.91 3.0 5400 551 0.24 0.55 0.018 18.0 285 0.97 3.2 6054 617 0.27 0.62 0.019 19.0 301 1.02 3.3 6745 688 0.3 0.69 0.02 20 317 1.07 3.5 7474 762 0.33 0.76 0.03 30 476 1.61 5.3 15975 1629 0.71 1.63 0.04 40 634 2.1 7.0 26905 2744 1.19 2.7 0.05 50 793 2.7 8.8 42040 4287 1.86 4.3 0.06 60 951 3.2 10.6 60537 6173 2.7 6.2 0.07 70 1110 3.8 12.3 82398 8402 3.6 8.4 0.08 80 1268 4.3 14.1 101643 10365 4.5 10.4


0.09 90 1427 4.8 15.9 128642 13118 5.7 13.1 0.1 100 1585 5.4 17.6 158817 16195 7.0 16.2 0.11 110 1744 5.9 19.4 192168 19595 8.5 19.6


Annex-VI

FILLED TUBEWELL ENERGY AUDIT REPORT (ELECTRICITY DRIVEN)


Village Name: XYZ

Audit Team Name: XYZ

Audit Date: XYZ Arrival Time: XYZ

Name of Farmer: XYZ Address: XYZ

District: XYZ Cell Number: XYZ

Well Type Bore Uncased

Existing Pump Type Centrifugal

Piping Type (Delivery) MS

Piping Type (Suction) MS

Filter Type Cement

Drive Type Direct Couple


Tubewell 1996

Bore 2000

Annex VI : 1 ENERCON, The National Energy Conservation Centre

Filter 2000

General Condition:

Civil Works OK

MCU OK

Filter Condition OK

Safety Aspects:

Electrical Connections Safe

Pump Shelter Unsafe

Retaining Walls Safe


Housing/Blind Pipe (casing) Length N/A

Housing/Blind Pipe (casing) Diameter N/A


Well Diameter 8 feet


Pulley Sizes N/A


Piping

Diameter of discharge pipe, mm N/A

Diameter of suction pipe, mm N/A


Pump Motor

Manufacturer Local Local

Year of Manufacturing 1995 1994

Model Number/Serial No. 23987008 54675788

Pump Size /Motor Capacity (In/HP) 10 10

Rated Efficiency (%) 72 78

Head/Operative Head Range (ft) 45

Impeller Diameter (In)

Discharge (Cusec)/GPM 0.5

Voltage/Voltage Band (V) 380-440

Full Load Amperes (A) 17

Motor Observations

Voltage (V) V12= 375 V23= 378 V31= 362

Current (A) I1=13.3 I2= 12.1 I3 = 13.2

Input Power (kW) P1= 7.6 P2= 6.99 P3= 7.28

Power Factor (PF) 0.88 0.88 0.88

Capacitor Availability No


Capacity of Capacitor (kVAr) N/A

Engine Observations

Fuel Consumption by diesel engine N/A

Color of diesel engine exhaust N/A

Temperature of coolant leaving diesel engine N/A

Pump Observations

Well/Bore Depth 40 ft

Pumping Level Ground

Suction Diameter 5 inches

Delivery Diameter 5.2 inches

Depth of Pump Installation 15 feet

Drawdown

Suction Length 30 ft

Delivery Length 26 ft

Water Table Depth / Static Water Level 20 ft

Suction Head 4 ft

Delivery Head 19 ft

Length of Filter 38 ft

Diameter of the Filter 8 in

Internal Diameter of the Bore Casing (in) 10

Types and Number of Bends and Valves in Delivery Pipe 1 bend 90 degree


Type and Number of Bends and Valves in Suction Pipe 1 bend 90 degree

XY Measurements

Horizontal Distance (X) at drop point: 16.1 16.1 and 16.1 inches Average = 16.1

Vertical Distance (Y) 12 inches

Inside Diameter of delivery pipe 5.2 inches

Calculations

Total Dynamic head 8.54 m

Flow m3/hr 78.79

Water power 1.83 kW

Estimated diesel engine efficiency N/A

Estimated electric motor efficiency : 77.33

Estimated transmission efficiency: N/A

Estimated pump efficiency : 25.15%


Piping efficiency:


Prime Mover OK

Pump OK

Transmission OK

Piping OK

Well OK


FILLED TUBEWELL ENERGY AUDIT REPORT (DIESEL ENGINE DRIVEN)


Village Name: XYZ

Audit Team Name: XYZ

Audit Date: XYZ Arrival Time: XYZ

Name of Farmer: XYZ Address: XYZ

District: XYZ Cell Number: XYZ

Well Type Bore Uncased

Existing Pump Type Centrifugal

Piping Type (Delivery) MS

Piping Type (Suction) MS

Filter Type Cement

Drive Type Direct Couple


Tubewell 1996

Bore 2000

Filter 2000

General Condition:

Civil Works OK


MCU OK

Filter Condition OK

Safety Aspects:

Electrical Connections Safe

Pump Shelter Unsafe

Retaining Walls Safe


Housing/Blind Pipe (casing) Length N/A

Housing/Blind Pipe (casing) Diameter N/A


Well Diameter 8 feet


Pulley Sizes N/A

Piping

Diameter of discharge pipe, in 4

Diameter of suction pipe, in 5


Pump Motor

Manufacturer Local N/A

Year of Manufacturing 1995 N/A

Model Number/Serial No. 23987008 N/A


Pump Size /Motor Capacity (In/HP) 4x5 N/A

Rated Efficiency (%) 72 N/A

Head/Operative Head Range (ft) 45 N/A

Impeller Diameter (In) N/A

Discharge (Cusec)/GPM 0.5 N/A

Voltage/Voltage Band (V) N/A

Full Load Amperes (A) N/A

Motor Observations

Voltage (V) N/A

Current (A) N/A

Input Power (kW) N/A

Power Factor (PF) N/A

Capacitor Availability N/A

Capacity of Capacitor (kVAr) N/A

Engine Observations

Fuel Consumption by diesel engine 130 g for duration of five minutes

Color of diesel engine exhaust Dark

Temperature of coolant entering diesel engine 28 C

Temperature of coolant leaving diesel engine 35 C

Temperature of exhaust of diesel engine 164 C

Pump Observations


Well/Bore Depth 40 ft

Pumping Level 18 in

Suction Diameter 5 inches

Delivery Diameter 6 inches

Depth of Pump Installation 15 feet

Drawdown

Suction Length

Delivery Length

Water Table Depth / Static Water Level

Suction Head 7.27 ft

Delivery Head 1.08 ft

Length of Filter

Diameter of the Filter

Internal Diameter of the Bore Casing (in)

Types and Number of Bends and Valves in Delivery Pipe 1 bend 90 degree

Type and Number of Bends and Valves in Suction Pipe 1 bend 90 degree

XY Measurements

Horizontal Distance (X) at drop point: N/A

Vertical Distance (Y) N/A

Inside Diameter of delivery pipe N/A

Calculations


Total Dynamic head 8.54 m

Flow 114.192 m3/hr (by flow meter)

Water power 2.59 kW

Estimated diesel engine efficiency 21%

Estimated electric motor efficiency : N/A

Estimated transmission efficiency: 0.95

Estimated pump efficiency : 17.3%


Piping efficiency:


Prime Mover OK

Pump OK

Transmission OK

Piping OK

Well OK


Acronyms

BEP Best Efficiency Point

CT Conventional Tillage

DAS Days After Sowing

ETc Crop Evapotranspiration

FPS Foot Pound Second

MAD Management Allowable Depletion

MAF Million Acre Feet

MCU Motor Control Unit

NEMA National Electrical Manufacturers Association

NPSH Net Positive Suction Head

Ns Specific Speed

TDS Total Dissolved Solids

TSS Total Suspended Solids