york pres iplv

EFFICIENCYEFFICIENCYVERMONTVERMONTSuccessful Successful

Cooling SystemCooling SystemEnergy Energy

OptimizationOptimization

Topics for Discussion

Commercial Energy Consumption

Equipment EvaluationFull-load efficiency

Integrated part-load values

Electric utility charges

Power Factor

Help you understand how to evaluate an air-cooledsystem with regard to bottom-line implications.

Commercial Energy Consumption

U.S. DOE Electrical End-Use Estimates“Commercial Buildings Energy Consumption Survey”

Electric Utility Charges

• Customer Charge• Electric Fuel Charge Adjustment

– Fuel Charge Adjustment• Environmental Surcharge• Energy Charge• Kilowatt (kW) Demand/Delivery Charge• Power Factor Adjustment/Penalty

ASHRAE 90.1ASHRAE 90.1--2001 (Mandatory Provisions)2001 (Mandatory Provisions)

• Full Load (FL)– Predicts performance at a single operation point

• Doesn’t anticipate how equipment will respond during off-design conditions

• Equipment with excellent full-load characteristics may have less than satisfactory part-load characteristics

• Integrated Part Load Value (IPLV)– Predicts performance over a defined range of

operating points• Provides a more accurate account of actual

equipment operation

AirAir--Conditioning & Refrigeration InstituteConditioning & Refrigeration Institute• Provides programs to certify manufacturer’s

published equipment data– Verified through random testing

• Equipment labeled when in compliance

Equipment Evaluation

ARI Standard 550/590-98Standard defining the testing and rating requirements for all chillers

Provides an equal baseline for all manufacturers

Defines testing conditions for real-world, chiller performance

ARI Standard 550/590ARI Standard 550/590--9898• Developed through real-world studies

– 1992 U.S. Department of Energy Study

• DOE/EIA-0246(92)

– 1995 Building Owner’s & Managers Assn.

• 1995 BEE Report

• Developed Weighted Average for:– Building types, Buildings with/without economizer, Chiller

operational hours, etc.

• Determined 1% of a chiller’s operating hours spent at full load design conditions.– With such few hours spent at FL operation, an analysis

comparing FL only would be completely inaccurate.

ARI Standard 550/590ARI Standard 550/590--9898

IPLV = .01A + .42B + .45C + .12D

Equipment Evaluation

A = EER @ 100% load (95°F Ambient)B = EER @ 75% load (80°F Ambient)C = EER @ 50% load (65°F Ambient)D = EER @ 25% load (55°F Ambient)

EERtonkW 12/ =

Equipment Evaluation

1.26 FL 1.15 IPLV

kW / TON9.56 FL

10.41 IPLV2.80 FL

3.05 IPLV

EERCOP

A/C Chillers w/Condenser Minimum Efficiencies

IPLV ComparisonA/C Chiller A = 12.5 EER A/C Chiller B = 15.2 EER

kW/ton12.5 = 12/EER= 12/12.5= 0.96 kW/ton

kW/ton15.2 = 12/EER= 12/15.2= 0.79 kW/ton

0.17 kW/TON difference!

Approximate Annual Energy Costs (dollars)

IPLV Comparison

Equipment Evaluation

109109109Avg. Load

$35,003$42,536$50,955AEC0.08130.08130.0813Rate500050005000Op. Hours

0.790.961.15kW / ton15.212.510.41

IPLV (EER)ASHRAE

Minimum Efficiency

$15,952 difference!

System ConsiderationsAir-cooled system• Low maintenance• Low installation and

equipment costs• Higher Energy

Consumption• Water Scarcity

W/C ChillerA/C Chiller

Water-cooled systemHigher maintenance

High-efficiency

High installation costs

Low sound

How do you know How do you know when your when your

cooling system is cooling system is optimized?optimized?

Step 1: Begin with Step 1: Begin with the end in mind.the end in mind.

Decide what components Decide what components you are going to you are going to optimize.optimize.Look at the Look at the systemsystem..

Cooling System Energy:Cooling System Energy:•• ChillersChillers•• Tower fansTower fans•• Primary Chilled Water and Primary Chilled Water and

Condenser Water PumpsCondenser Water Pumps•• Sum of the kWh Sum of the kWh

consumption of the consumption of the above.above.

Possibly also consider: Possibly also consider: secondary pumps, AHU secondary pumps, AHU fan energyfan energy..

2A: The Chiller: 2A: The Chiller: Do you know your Do you know your

chiller matrix?chiller matrix?

Chiller Efficiency MatrixPercent

LoadCapacity

Tons 55 60 65 70 75 80 85

10%20%30%40%50%60%70%80%90%100%

Entering Condenser Water Temperature

kW/ton usage

Const Speed Chiller Effy MatrixPercent Load

55 F 65 F 75 F 85 F

10% 1.140 1.180 1.22020% 0.700 0.740 0.810 0.90030% 0.547 0.587 0.653 0.74740% 0.470 0.515 0.585 0.67550% 0.428 0.476 0.544 0.63260% 0.400 0.450 0.517 0.60770% 0.383 0.437 0.503 0.59180% 0.375 0.425 0.493 0.58090% 0.371 0.420 0.484 0.573100% 0.368 0.416 0.482 0.564

Entering Condenser Water Temperature

kW/ton usage

Const Speed Chiller Effy Curves

0.200

0.300

0.400

0.500

0.600

0.700

0.800

0.900

1.000

1.100

1.200

10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Pct Load

kW/to

n 55 F65 F75 F85 F

Entg CondWtr Temp

VAR SPEED Chiller Efficiency Matrix

Percent Load55 F 65 F 75 F 85 F

10% 0.520 0.680 1.10020% 0.320 0.430 0.660 0.90030% 0.260 0.353 0.527 0.75340% 0.235 0.320 0.475 0.67050% 0.220 0.308 0.444 0.61260% 0.210 0.303 0.420 0.57770% 0.209 0.311 0.423 0.56980% 0.233 0.325 0.428 0.55890% 0.249 0.340 0.442 0.560100% 0.270 0.360 0.460 0.576

Entering Condenser Water Temperature

kW/ton usage

VAR SPEED Chiller Efficiency Curves

0.200

0.300

0.400

0.500

0.600

0.700

0.800

0.900

1.000

1.100

1.200

10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Pct Load

kW/to

n

55 F65 F75 F85 F

Entg CondWtr Temp

Cooling tower entering condenser Cooling tower entering condenser water bin hours for Burlington Vt.:water bin hours for Burlington Vt.:

•• 85F ECWT = 10 hrs85F ECWT = 10 hrs•• 75F ECWT = 1000 hrs75F ECWT = 1000 hrs•• 65F ECWT = 1450 hrs65F ECWT = 1450 hrs•• 55F ECWT and below = 6300 hrs55F ECWT and below = 6300 hrs

Chiller Performance Chiller Performance GeneralitiesGeneralities::•• Lower lift = less compressor Lower lift = less compressor

energy (Compressor lift is the energy (Compressor lift is the difference between the suction and difference between the suction and discharge pressure).discharge pressure).

•• Capacity has less affect on Capacity has less affect on compressor performance than lift.compressor performance than lift.

•• Different chillers have different Different chillers have different minimum lifts due to design minimum lifts due to design differences…differences…

Orifice: 13# differential pressure

Condenser

@ 85F ECWT

Refrigerant pressure= 19.1 psia

Compressor

Flooded Evaporator

@ 44F leaving

chilled water

Refrigerant pressure =

6.1 psia

Orifice : 4.3 # differential pressure

Condenser

@ 55FECWT

Refrigerant pressure= 10.4 psia

Compressor

Flooded Evaporator

@ 44F leaving

chilled water

Refrigerant pressure =

6.1 psia

Orifice : 4.3 # differential pressure

Condenser

@ 55F ECWT

Refrigerant pressure= 10.4 psia

Compressor Flooded Evaporator

@ 44F leaving

chilled water

Refrigerant pressure =

6.1 psia

Tubes not covered by

liquid

“stacking” phenomenon

Orifice : 4.3 # differential pressure

Condenser

@ 55F ECWT

Refrigerant pressure= 10.4 psia

Compressor Flooded Evaporator

@ 44F leaving

chilled water

Refrigerant pressure =

6.1 psia

Tubes not covered by

liquid

Motor cooling and oil loss problems stem from the same phenomenon; low internal differential pressure for systems which rely on a differential pressure to operate.

2B: The Tower: 2B: The Tower: •• Raising the tower setpoint Raising the tower setpoint

will save fan energy but will save fan energy but penalize the chiller.penalize the chiller.

•• TwoTwo--speed fan motors speed fan motors better than single speed.better than single speed.

•• Variable speed is best for Variable speed is best for energy and control.energy and control.

2C: The pumps: 2C: The pumps: •• Condenser water flow: Condenser water flow:

Reducing the condenser water Reducing the condenser water flow will save on the pump flow will save on the pump energy but penalize the chiller energy but penalize the chiller (similar to holding up the (similar to holding up the entering condenser water entering condenser water temperature). temperature).

Performance Matters

First Cost Advantage of Air Cooled ChillersEasy Installation – 20% less than Water Cooled Equivalent

No Cooling Tower, Tower pumps, Tower and Pump Starters

No equipment room required for the chillers

Multiple Circuits for redundancy – not multiple chillers

Mounted starters

Maintenance Advantage of Air Cooled ChillersEasy Maintenance – vs. Water Cooled

No on site Systems Engineer required

No water treatment or make up water required

No leaks on the roof

No cooling tower, condenser pumps, associated starters

Performance –The Traditional Trade-off for Air Cooled Chillers

Energy

Full Load typically 65% more than Water Cooled system

9.6 EER = 1.25 kW/TR (ASHRAE 90.1 Tier 1 requirement)

10.2 EER = 1.17 kW/TR (ASHRAE 90.1 Tier 2)

Part Load typically 100% more than Water Cooled system

12.5 EER = .96 kW/TR

Performance –The Traditional Trade-off for Air Cooled ChillersSound

Multiple Compressors and Condenser fans

Typical full load sound levels often 100+ dBA

Lower nighttime sound regulations can be limiting factor

Required acoustical treatments drive up first costSound blankets (-1 dBA) = 2-3% of first cost

Unit enclosures (-3 to 5 dBA) ~$10 K

How Latitude changes the balance• All the best of today’s air cooled chillers

– ASHRAE 90.1 energy level compliance up to 10.3 EER– R-134a environmentally sound HFC refrigerant– Compact single package design (150 – 260 TR)– Simple maintenance requirements– Dual Circuit design for redundancy

New

NewNew

NewNew

PLUS YOU NO LONGER COMPROMISE ON PERFORMANCE…World class IPLV performance – real world savings during the other 98% of the operating time vs. 90.1 requirements

15.2 EER

Part load sound levels 5-6 dBA lower than competitors

load shedding software for noise level management

Soft Start Capabilities for increased motor life

Reduced Full load amps for a reduction in wire sizing

Performance matters

Latitude delivers 15-25% Real World kWh Savings

The power of off design on Energy - 98% of operating hours are at off design conditions

Performance matters

– ARI IPLV part load points

– 12.5 vs 15.2 IPLV– $.0813/kWh

(2003 DOE National Average)

Latitude’s part load performance is tested & ARI certified

Annual Energy Savings due to part load efficiency

$-

$2,000

$4,000

$6,000

$8,000

$10,000

$12,000

$14,000

2000 2500 3000 3500 4000 4500 5000 5500 6000

Operating Hours

Ann

ual S

avin

gs

150 TR 180 TR 200 TR 250 TR

180 TR Chiller

5000 hours$7500/year savings

180 TR Chiller

5000 hours$7500/year savings

3000 hours$4500/year savings

• Soft Start• Power factor• First Costs – Electrical

installation– Wire and circuit breakers

reduced by 1-2 sizes– 5-15% Generator cost

savings• Operating Costs

– .95 Power Factor throughout operating range

Electrical Characteristics

Performance through Technology

• 25 years of real world experience with varying compressor motor speeds

• Logical Extension of Variable Speed Drive technology for compressor motor applications

• Eliminates Slide valve and associated inefficiencies, and reduces compressor moving parts by 50%

• Solid State unit mounted starter

Lowest Total Cost of Ownership

• First Cost savings = 10-15%– Electrical Savings– Elimination of sound attenuation equipment

• Operating Costs Savings = 15-25%

– 15 Year equipment life– 5000 hours per year operation – National Average $$/kWh ($0.0813)

Performance that delivers real world Performance that delivers real world savings every year of operationsavings every year of operation

Latitude can save you 10% of the cost of the chiller…….

Every year it operates!