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DEPARTMENT OF PRODUCTION ENGINEERING HALDIA INSTITUTE OF TECHNOLOGY

LAB MANUAL ON

I C ENGINE LABORATORY (ME 692)

CREDIT: 2

CONTACT HOURS / WEEK: 0-0-3

Syllabus

I C Engine Lab (ME 692)

Determination of calorific value of a fuel by Bomb calorimeter. Flue gas analysis by ORSAT apparatus. Study of valve timing diagram of Diesel Engine. Performance Test of a multi-cylinder Petrol Engine by Morse

method. Performance Text of an I.C. Engine using electric (eddy current)

dynamometer. Use of catalytic converters and its effect on flue gas of an I.C.

Engine. Study of MPFI (multipoint fuel injection system).

(At least six experiments must be conducted)

Course Outcome:

COS ME 692.

ME 692. 1 Identify the types and configurations of internal combustion engines. ME 692. 2 Understand the engine performance parameters and their relationship to operating

conditions.

ME 692. 3 Set up testing strategies and select proper instruments to evaluate performance characteristics.

ME 692. 4 Able to assess the environmental impacts of emissions from engine and adhere to the Government pollution norms.

ME 692. 5 Evaluate possible causes of discrepancy in practical experimental observations in comparison to theory.

ME 692. 6 Primarily via team-based laboratory activities, students will demonstrate the ability to interact effectively on a social and interpersonal level with fellow students, and will demonstrate the ability to divide up and share task responsibilities to complete assignments.

CO-PO Correlation:

COS ME 692. PO1 PO2 PO3 PO4 PO5 PO6 PO7 PO8 PO9 PO10 PO11 PO12

ME 692. 1 Identify the types and configurations of internal combustion engines.

3 3 3 3 2 2 2 - 2 2 2 2

ME 692. 2 Understand the engine performance parameters and their relationship to operating conditions.

3 2 3 3 3 1 2 - 1 1 1 1


3 3 3 2 2 1 1 - 1 1 1 2


3 3 2 2 1 3 3 3 1 1 1 1


2 3 2 2 1 2 3 3 1 1 1 1


3 2 3 3 3 1 1 1 1 1 1 1

* Enter correlation levels 1, 2 or 3 as defined below: 1: Slight (Low) 2: Moderate (Medium)3: Substantial (High) and It there is no correlation, put “-”

2.37 2.23 2.23 2.09 1.67 1.39 1.67 0.97 0.97 0.97 0.97 1.11

CO-PSO Correlation:

COS ME 692 PSO1 PSO2 PSO3

ME 692. 1 Identify the types and configurations of internal combustion engines. 3 2 3

ME 692. 2 Understand the engine performance parameters and their relationship to operating conditions. 2 3 2

ME 692. 3 Set up testing strategies and select proper instruments to evaluate performance characteristics. 2 3 2


3 2 2


2 3 3


2 3 2

* Enter correlation levels 1, 2 or 3 as defined below: 1: Slight (Low) 2: Moderate (Medium)3: Substantial (High) and It there is no correlation, put “-”

2.33 2.67 2.33

CO-EXPERIMENT CORRELATION MAP:

COS ME 692. E-O1 E-O2 E-O3 E-O4 E-O5 E-O6

ME 692. 1

Identify the types and configurations of internal combustion engines.

ME 692. 2 Understand the engine performance parameters and their relationship to operating conditions.


ME 692. 4

Able to assess the environmental impacts of emissions from engine and adhere to the Government pollution norms.


ME 692. 6

Primarily via team-based laboratory activities, students will demonstrate the ability to interact effectively on a social and interpersonal level with fellow students, and will demonstrate the ability to divide up and share task responsibilities to complete assignments.

EXPERIMENT NO-1:

Study of Cut Model of Four Stroke Single Cylinder Diesel Engine

EXPERIMENT NO-2:

Study of Valve Timing Diagram of a Four Stroke Diesel Engines

EXPERIMENT NO-3:

Determination of Flash Point and Fire Point of a Fuel

EXPERIMENT NO-4:

Determination of Calorific Value of a given Fuel or Oil

EXPERIMENT NO-5:

Load Test on Four Stroke Diesel Engine by Rope Brake Dynamometer

EXPERIMENT NO-6:

Flue Gas Analysis by Orsat Apparatus

EXPERIMENT NO-7:

Performance Test of a Muticylinder Petrol Engine by Morse Test

Department of Production Engineering

Sub: I C Engine Lab

Experiment No: ME-692/01

Title : Study of Cut Model of Four Stroke Single Cylinder Diesel Engine

Objective : To study the constructional details and working principles of 4-stroke diesel engine.

Theory: Heat engine is a device, which uses heat energy obtained from combustion of fuel and converts it into useful

mechanical energy. They are classified as external and internal combustion engines. Compression Ignition (CI) engine

is an internal combustion engine which operates on Diesel cycle and uses diesel oil as a fuel and commonly known as

diesel engine. In a 4-stroke diesel engine, the working cycle takes place in two revolutions of the crankshaft or 4

strokes of the piston. In this engine, pure air is sucked in the engine and the fuel is injected with high pressure fuel

pump and injectors near the end of the compression stroke. The fuel will auto-ignite after injection due to higher

pressure and temperature inside the cylinder caused by compression and thus signifying compression ignition. The

power developed and the performance of the engine depends on the condition of operation. In four strokes CI engine

compression ratio generally varies from 14:1 to 22:1. Following are the 4 strokes executed by a 4 stroke CI engine-

1. Suction- During suction stroke, piston moves from TDC to BDC (for vertical engines and IDC to ODC for

horizontal engines) and atmospheric air is sucked inside the cylinder through inlet valve.

2. Compression- The piston moves from BDC to TDC (for vertical engines and ODC to IDC for horizontal engines)

compressing the inducted air to the clearance volume to higher pressure and temperature.

3. Expansion- Fuel injection starts nearly at the end of the compression stroke. The rate of injection is such that the

combustion occurs at constant pressure as the piston moves from TDC to BDC (for vertical engines and IDC to

ODC for horizontal engines) delivering the useful power output.

4. Exhaust- The piston travels from BDC to TDC (for vertical engines and ODC to IDC for horizontal engines)

pushing out the products of combustion from the cylinder.

Constructional details of diesel engine:

Major components of a diesel engine are as below-

a) Engine block- Body of engine which contains the cylinder, cylinder head and crankcase and supports the entire

engine set up. The block of water-cooled engines includes a water jacket cast around the cylinders. On air-cooled

engines, the exterior surface of the block has cooling fins. Generally, engine block is made of cast iron or cast

aluminium.

b) Cylinder head- This forms the cover that is fitted on the top of the cylinder block. It may contain the combustion

chamber which is formed in the clearance volume when the piston is at TDC. The head will also contain the fuel

injector, inlet and exhaust valves together with their operating mechanism, a number of ports etc. Cylinder head is

made of cast iron or cast aluminium.

c) Cylinder- This is the circular portion in the engine block in which the piston reciprocates back and forth. The

walls of the cylinder have highly polished hard surfaces. Cylinders may be machined directly in the engine block,

or a hard metal (drawn steel) sleeve may be pressed into the softer metal block which is known as cylinder liner.

Sleeves may be dry sleeves, which do not contact the liquid in the water jacket, or wet sleeves, which form part of

the water jacket.

d) Cam shaft- The function of the camshaft is to open the valves at the correct time of engine operations. It is also

used as a drive for various auxiliary units such as the distributor, fuel pump and oil pump. Several methods are

employed to transmit the drive from the crankshaft to the camshaft like chain, gear and toothed belt drive.

Camshafts are generally made of forged steel, cast iron or cast steel.

e) Crank shaft- Rotating shaft through which engine work output is supplied to external systems. The crankshaft is

connected to the engine block with the main bearings. This is connected to the piston through the connecting rod

and converts the linear motion of the piston into the rotational motion of the flywheel. Crankshafts are made of

forged steel and cast iron. Counter-weights and the flywheel bolted to the crankshaft help in the smooth running of

the engine.

f) Connecting rod- The connecting rod connects the piston with the crankshaft. The end of connecting rod

connecting the piston is known as small end and the other end is known as big end. It is ‘I’ section beam.

Connecting rod is usually made of steel or alloy forging in most engines but may be aluminium in some small

engines.

g) Connecting rod bearings- Bearing where connecting rod fastens to crankshaft. These are generally made of

bronze, white metal.

h) Crankcase- Part of the engine blocks surrounding the rotating crankshaft. In many engines, the oil pan makes up

part of the crankcase housing.

i) Cylinder liner- It is a thin cylindrical shell which is inserted inside the engine bore and acts as protective surface

between the piston and cylinder bore. It protects the main cylinder bore from erosion and can be replaced after

damage. The liners being made of cast iron and cast steel have a much better wear resistance than many other

materials.

j) Fuel injector- A nozzle which is located at the cylinder head to inject the pressurized fuel into the combustion

chamber.

k) Fuel pump- Electrically or mechanically driven pump to supply fuel from the fuel tank (reservoir) to the engine.

l) Flywheel- Rotating mass with a large moment of inertia connected to the crankshaft of the engine. The purpose of

the flywheel is to store energy. Its primary function is to maintain uniform engine speed. The size of the flywheel

varies with the number of cylinders and the type and size of the engine. It also helps in balancing rotating masses.

m) Intake and Exhaust manifold- Piping system which delivers incoming air to the cylinders is known as intake

manifold. Piping system which carries exhaust gases away from the engine cylinders is known as exhaust

manifold. They are generally made of cast iron, cast aluminium.

n) Inlet and exhaust valves- The inlet valves allow the fresh air or fuel-air mixture to enter the combustion chamber

and the exhaust valve discharges the products of combustion. These valves are operated by camshaft in

accordance with the cam, tappet, push rod, spring and rocker arm. They are generally made of forged steel, alloy

steel.

o) Main bearings- The bearings connected to the engine block in which the crankshaft and camshaft rotates. The

maximum number of main bearings would be equal to the number of pistons plus one, or one between each set of

pistons plus the two ends. On some less powerful engines, the number of main bearings is less than this

maximum. These bearings must be capable of withstanding high speed, heavy load and high temperatures. They

are generally made off white metal, steel backed Babbitt based alloy.

p) Oil pan- Oil reservoir usually bolted to the bottom of the engine block, making a part of the crankcase acts as the

oil sump for most of the engines.

q) Push rods- Mechanical linkage between the camshaft and valves on overhead valve engines which is connected

with the rocker arm to actuate the valves. They are generally made of forged steel, alloy steel.

r) Piston- It is a cylindrical component which reciprocates inside the cylinder to execute the strokes and transmits

the forces of combustion to the connecting rod. The top of the piston is called the crown and the sides are called

the skirt. On some types of engines the piston crown is designed to a specific shape instead of being flat. This

allows for the shape of the combustion chamber to be included in the piston crown instead of in the cylinder head,

and may also have an effect on the flow of gases into and out of the cylinder. Pistons are made of cast iron, steel,

or aluminium.

s) Piston rings- Metal rings that fit into circumferential grooves around the piston and form a sliding surface against

the cylinder walls. Near the top of the piston there are compression rings made of highly polished hard chrome

steel or high-grade cast iron which form a seal between the piston and cylinder walls to restrict the high-pressure

gases from leaking past the piston into the crankcase. Below the compression rings there are oil rings which assist

in lubrication inside the cylinder walls and scrapes away excess oil to reduce oil consumption. Piston rings also

transmit the heat away from the piston and the cylinder walls.

t) Piston pin- This is a cylindrical body used as a pin to connect the piston with the connecting rod. It is also known

as Gudgeon pin which is generally made of forged steel, casehardened steel.

Figure 1.1: Sectional view of 4 stroke CI engine

Working principle of 4 stroke diesel engine:

In a 4 stroke diesel engine only pure air is drawn into the cylinder during suction stroke through the inlet valve when

the exhaust valve is closed. Then in compression stroke the piston moves up with both the valves remaining closed.

The air, which has been drawn into the cylinder during the suction stroke is progressively compressed as the piston

ascends and its temperature increases, until near the end of the compression stroke it becomes sufficiently high to

instantly ignite the fuel that is injected into the cylinder. When the piston is near the top of its compression stroke

diesel fuel is sprayed into the combustion chamber under high pressure higher than that existing in the cylinder itself

and the fuel then auto-ignites which started the combustion. Auto-ignition of the fuel commences the third consecutive

stroke, viz., power stroke during which both the valves remains closed and the hot products of combustion expands

thus forcing the piston downward. This is only the working stroke of the engine. The exhaust valve then opens usually

a little earlier than when the piston reaches its lowest point of travel. The exhaust gases are swept out on the following

upward stroke of the piston. The exhaust valve remains open throughout the exhaust stroke and closes a little after the

suction stroke starts. The reciprocating motion of the piston is converted into the rotary motion of the crankshaft by

means of a connecting rod and crankshaft. The crankshaft rotates in the main bearings which are set in the crankcase.

The flywheel is fitted on the crankshaft in order to smoothen out the uneven torque that is generated in the

reciprocating engine.

Figure 1.2: Four strokes of a diesel engine

Conclusion:

From the above study we came to know the working principle and constructional details of diesel engine.

Frequently asked questions during Interviews

(i) What are the four strokes of a CI engine?

(ii) What is the function of a camshaft?

(iii) What is the purpose of a flywheel?

(iv) What is piston ring?

(v) What types of materials are generally used to build engine block?


Sub: I C Engine Lab


Title : Study of Valve Timing Diagram of a Four Stroke Diesel Engines

Objective : To draw the actual valve timing diagram of the four stroke diesel engine.

Theory: The valve timing diagram gives an idea about the exact timing of opening and closing the inlet and exhaust

valves as well as their operational period. The four stroke diesel engines have inlet valve to supply air inside the

cylinder during suction stroke and an exhaust valve to transfer exhaust gas after combustion to the atmosphere. The

sequence of events such as opening and closing of valves are performed by cam-follower-rocker arm mechanism in

relation to the movements of the piston as it moves from TDC to BDC. As the cycle of operation is completed in four

strokes, one power stroke is obtained for every two revolution of the crankshaft. Valves do not open or close exactly at

the two dead centers in order to transfer the intake charge and the exhaust gas effectively. The timing is set in such a

way that the inlet valve opens before TDC and closes after BDC and the exhaust valve opens before BDC and closes

after TDC. As the timing plays major role in transfer of the charge, which reflects on the engine performance, it is

important to study these events in detail.

Procedure: 1. Mark the direction of rotation of the flywheel. Always rotate only in clockwise direction when viewing in

front of the flywheel.

2. Mark the Top Dead Center (TDC) position on the flywheel with the reference point when the piston reaches

the top most position during the rotation of flywheel. 3. Mark the Bottom Dead Center (BDC) position on the flywheel with the reference point when the piston

reaches the lowermost position during rotation of the flywheel. The BDC can also be marked on the flywheel

by taking half the circumference. 4. The cover on the valve casing is removed and inlet and exhaust valves and their push rods are identified.

5. By slowly cranking the camshaft in the direction of rotation identify the four strokes by the rotation of the

flywheel and observe the movement of inlet and exhaust valves. 6. Mark the opening and closing events of the inlet and exhaust valves on the flywheel.

7. Measure the circumferential distance of the above events either from TDC or from BDC whichever is nearer

and calculate their respective angles.

8. To determine the fuel injection start and stop position we need to check the cam and follower arrangement connected with the fuel pump. When the cam will start pushing the follower the fuel injection starts and when

it returns to its original position fuel injection stops. Consecutive movements of the follower should be

marked on the flywheel. 9. Draw the valve timing diagram and indicate the valve opening and closing periods, fuel injection start, fuel

injection stop and fuel injection periods.

Observation table:

Sl. no. Description Distance from nearest dead center

(mm)

Angles

(Degrees)

01 Inlet valve opens before TDC

02 Inlet valve closes after BDC

03 Exhaust valve open before BDC

04 Exhaust valve close after TDC

05 Fuel injection starts before TDC

06 Fuel injection stops after TDC

Results and discussions:

Circumference of the flywheel is, X = πD; D= Diameter of flywheel

Angle in degree = L

X x 3600

Where, L = Distance from nearest dead center in mm; X = Circumference of the Flywheel in mm

Figure 2.1: Valve timing diagram of a CI engine

Conclusion:

From the above experiment we came to know the procedure of determination of valve timing diagram experimentally.

We determine the inlet and exhaust valve opening, closing and operational duration, fuel injection duration of a 4

stroke diesel engine.

Quiz questions:

(i) Why the valves are not operated instantaneously at TDC and BDC?

(ii) What do you mean by valve overlapping?

(iii) What is the difference between the valve timing diagram of CI and SI engine?

(iv) How detonation or knocking is being affected by the valve timing in both CI and SI engines?

(v) How many valves are there in 2 stroke engines?


Sub: I C Engine Lab


Title : Determination of the flash and fire point of a given fuel.

Objective : To find the flash point and fire point of petrol and diesel fuel.

Apparatus : Open or closed cup tester, thermometer (0-300oC), sample fuel/oil, splinter sticks.

Theory: The flash point of a liquid is the lowest temperature at which the liquid gives off enough flammable vapour to form a

mixture with air which will ignite if an ignition source is available to it. At the flash point, the vapour may cease to

burn when the ignition source is removed. The flash point is a descriptive characteristic that is used to

distinguish flammable liquids (e.g. petrol) from combustible liquids. Liquids which have a flash point less than either 60.5°C (140.9°F) is called flammable, whereas liquids having a flash point above that temperature are called

combustible. Lower the flash point, greater the fire hazard. Every liquid has vapour pressure, which is a function of

that liquids temperature. As the temperature increases the vapour pressure increases, which increases the concentration of vapour of the flammable liquid in the air. Hence, temperature determines the concentration of vapour of the

flammable liquid in the air. A certain concentration of vapour in the air is necessary to sustain combustion, and that

concentration is different for each flammable liquid. The fire point of a fuel is the temperature at which the vapour produced by that given fuel will continue to burn for at

least 5seconds after ignition and removal of the ignition source. At the flash point a substance will ignite briefly, but

vapour might not be produced at a rate to sustain the fire. In general the fire points can be assumed to be about 10°C-

15°C higher than the flash points. Neither the flash point nor the fire point is dependent on the temperature of the ignition source, which is much higher. The physical significance of flash point and fire point is that-

a) Flash point is used to distinguish flammable liquids from combustible liquids.

b) During storage and transportation of the fuels flash point gives the lowest safest temperature. c) The lower the flash point, the more flame-hazardous the material.

d) Lower the flash point of a fuel to be used in engines also may cause carbon deposits.

There are two basic types of flash point measurement: open cup and closed cup. While both types of cups can be used on almost any combustible liquid, the open cup is used for less volatile liquids (i.e., having a high flash point, such as

lubricating oil), while the closed cup is used for more volatile liquids (i.e., having a low flash point, such as ethyl

alcohol). In open cup test the sample is kept in a cup which is heated, and at intervals an external ignition source is

brought over the surface. Closed cup testers normally give lower values for the flash point than open cup (typically 5°C–10°C lower) and are better approximation to the temperature at which the vapour pressure reaches the lower

flammable limit.

Working principle of open cup type flash point measurement:

The open cup apparatus consists of a cylindrical cup of standard size. It is held in place in the metallic holder that is

placed on a wire gauge and is heated by means of an electric heater housed inside the metallic holder. A provision is

made on the top edge of the cup to hold the thermometer in position. A standard filling mark has been scribed on the

inner side of the cup and the sample oil is filled up to this mark. During the experiment the temperature of the heater

has to be raised slowly and an external ignition source will also have to be introduced.

Figure 3.1: Open cup tester

Procedure:

1. Fill the cleaned open cup with the given sample of oil up to the standard filling mark of the cup.

2. Insert the thermometer in the holder on the top edge of the cup. Make sure that the tip of the thermometer is

immersed in the oil and should not touch the metallic part.

3. Heat the sample oil by means of an electric heater so that the sample oil gives out vapour.

4. When the oil gives out vapour, start to introducing the external ignition source (the flame should not touch the

ignition source) and watch for any flash with flickering sound.

5. Blow out the burnt vapour before introducing the ignition source again. This ensures that always fresh vapours are

left over the surface of the oil and the test is carried out accurately.

6. Continue the process of heating and placing the ignition source at small intervals of rise in temperature till the first

flash with the peak flickering sound and note the corresponding temperature as the flash point.

7. Continue the heating further and watch the fire point, which is noted when the oil vapour ignites and continue to

burn at least for 5 seconds if the external ignition source is removed.

8. Repeat the test twice or thrice with fresh sample of the same oil for accuracy.

Observation table:

Serial no. Type of apparatus Temperature (oC) Observations


The flash point of the given sample fuel / oil is =

The fire point of the given sample fuel / oil is =

Conclusion:

From the above experiment the physical significance of flash point and fire point of oil/fuel can be understood and the

flash point and fire point of the given oil was found out.

Quiz questions:

(i) Define flash point and fire point.

(ii) What is the significance of knowing the flash point and fire point of a fuel to be used in I.C Engines? (iii) What are the values of flash point and fire point for gasoline?

(iv) What are the desirable level of flash point and fire point of a fuel?

(v) How ignition flame is used in this experiment?


Sub: I C Engine Lab


Title : Determination of calorific value of the given fuel or oil.

Objective : To Find the Calorific Value of Diesel Fuel and Coal by Bomb Calorimeter

Apparatus : Bomb calorimeter set up, pressure gauge with copper tubes for filling oxygen inside the

bomb under pressure, nichrome wire 44swg, cotton thread.

Introduction:

The calorific value or heating value is the total heat released when a substance (fuel or food) undergoes

complete combustion with oxygen under standard conditions. It may be expressed with the quantities: energy/mass

(KJ/kg) for liquid and solid and energy/volume (KJ/m3) for gaseous substances. It can be categorized into higher calorific value (HCV) and lower calorific value (LCV). After combustion, if the products of combustion cooled down

to their initial temperature so that the water vapour produced can condense by releasing the latent heat of condensation

which will be accounted in the total heat released will give HCV and if the product of combustion does not cooled down and latent heat of condensation will not accounted in the total heat released will give LCV.

A calorimeter is an object used for measuring the heat of chemical reactions or physical changes as well as heat

capacity. A bomb calorimeter is a type of constant-volume calorimeter used in measuring the heat released during combustion of a particular reaction carried by a solid and liquid fuel. Basically, a bomb calorimeter consists of a

stainless steel bomb (may be made of copper also) where the fuel is placed and reaction is occurring, crucible (made

of nickel alloy, quartz, platinum and stainless Steel etc.) to contain the sample fuel, a stirrer, good thermometer (which

can read very low temperature difference), calorimeter vessel (made of copper and is coated with Ni-Cr to reflect the heat back into the water instead of radiating it) in which the bomb is placed and is filled with water and ignition circuit

connected to the bomb. In the moist, high pressure oxygen environment inside the bomb, nitrogen present will be

oxidized to nitric acid, sulfur present will be oxidized to sulfuric acid, and chlorine present will be released as a mixture of chlorine and hydrochloric acid during combustion. These acids combine with the residual high temperature

oxygen to form a corrosive vapour which will etch ordinary metals. The Bomb body and the lid are machined from an

ultra-strong corrosion resistant stainless steel alloy containing Cr, Ni & Mo which satisfying special ringing and

bending tests for inter-crystalline corrosion. The cover or head of the bomb carries the oxygen valve for admitting oxygen and a release valve for exhaust gases. Bomb calorimeter always gives the higher calorific value of the fuel as

the product of combustion condenses releasing the latent heat of condensation to the surrounding water.

Working principle of bomb calorimeter:

The whole bomb pressurized with excess pure oxygen (typically at 30atm) and containing a weighed mass of a sample

fuel (typically 1-1.5gm) is submerged under a known volume of water i.e. 2000ml to saturate the internal atmosphere, thus ensuring that all water vapour produced during reaction is condensed before the charge is electrically ignited. The

bomb forms a closed system so that no gases can escape during the reaction. The weighed reactant put inside the steel

container is then ignited by an electric discharge. Heat released by the combustion will flow and will raise the

temperature of the steel bomb, its contents, and the surrounding water jacket. The temperature change in the water is then accurately measured with a thermometer. A small correction is made to account for the electrical energy input,

the burning fuse, the burning thread and acid production (by titration of the residual liquid). Apart from this, the mass

of the bomb, stand, container which also be heated are assumed to be equivalent to equal amount of water mass to be heated if it is not possible to determine the change in temperature of the individual components (bomb, stand,

container). After the temperature rise has been measured, the excess pressure in the bomb is released. Based on the

energy balance principle i.e. heat liberated will be equal to heat absorbed the calorific value or the heating value can be found out.

Procedure:

1. Weight the sample fuel. Sample should not be less than 0.9gm not more than 1.5gm. 2. Weight the nichrome wire and cotton thread taken.

3. Connect the nicrome wire (fuse wire) across the electrodes. Tie the cotton thread to the fuse wire by one end and

the other end will touch the sample fuel. 4. Assemble the bomb and charge it slowly with oxygen to a pressure of around 30bar without displacing the original

air present in the bomb.

5. Pour known volume of distilled water (i.e. 2ltr) into calorimeter vessel upto the marked level.

6. Transfer the calorimeter vessel to the water jacket, lower the bomb into the calorimeter vessel and check that the bomb is gas tight. If gas escapes from the bomb, discard the test.

7. Setup the apparatus and keep the stirrer on.

8. After two minutes fire the charge using a special transformer and firing unit.

9. Record the thermometer reading once the temperature will be steady. 10. Remove the bomb from the calorimeter vessel. The bomb is allowed to remain unopened for thirty minutes after

the charge is fired, to allow the acid mist to settle and release the pressure and dismantle the bomb.

Figure 4.1: Bomb calorimeter

Observation table:

Serial no. Time Initial temperature(0C) Final temperature(

0C) Observations


Let, Mf = Mass of fuel sample burnt in the bomb in kg

Mw = Mass of water filled in the calorimeter; 2kg

WE = Water equivalent of bomb calorimeter in J/°C; (bomb-2.44kg, stand-0.12kg, container- 0.44kg).

Mtlo = Mass of thread left over after combustion in gm

Mnwlo = Mass of nichrome wire left over after combustion in gm

CVt = Calorific value of cotton thread, 17.55KJ/g

CVnw = Calorific value of nichrome wire, 1.4KJ/g

HCV = Higher calorific value of the fuel sample in KJ/kg

t1 = Initial temperature of water and apparatus in °C

t2 = Final temperature of water and apparatus in °C

Cw = Specific heat constant of water, 4.2KJ/kg-K

Now, Heat liberated by fuel = Mf × HCV

Heat absorbed by water and apparatus = WE × (t2 – t1)

From energy balance, Heat liberated during the reaction = Heat absorbed by water equivalent mass

Mf × HCV = WE × (t2 – t1)

HCV = WE × (t2 – t1) / Mf

But, for accurate analysis various correction factors should be accounted in the above basic equation. The correction

factors are as bellow-

a) Subtract thread correction factor, Ct (accounts for the heating value of the left over thread after combustion) = Mtlo

x CVt

b) Subtract fuse wire correction factor, Cf (accounts for the heating value of the left over fuse wire after combustion)

= Mnwlo x CVnw

c) Sulphur and Nitrogen oxidation correction factor, Ca (if can be found out)

Considering above all the correction factors, the modified equation will be-

H.C.V. = [{WE × (t2 – t1)} – (Ca + Ct + Cf)] / Mf

Determination of Water Equivalent of bomb calorimeter:

Before a material with an unknown heat of combustion can be tested in a bomb calorimeter, the heat capacity of the

bomb calorimeter also known as energy equivalent or water equivalent (WE) must first be determined. The WE of the

bomb calorimeter takes into consideration the sum of the heat capacities of the components in the calorimeter, such as

the metal bomb, bucket, water in the bucket, nichrome wire and cotton thread. The heat capacity of the calorimeter is

determined empirically by burning a sample of a standard material with a known calorific value. Benzoic acid is used

almost exclusively as a reference material because it burns completely in oxygen, it is not hygroscopic and it is readily

available in very pure form. The amount of heat produced by the reference sample is determined by multiplying the

calorific value of the standard material by the mass of the sample burned. Then, by dividing this value by the

temperature rise in the test, we obtain a resultant heat capacity of the bomb calorimeter known as water equivalent of

bomb calorimeter. The mass of the fuse wire and thread can be decided by the user, but once decided, it is highly

recommended that the same mass and material be used for all subsequent experiments to be done in the bomb

calorimeter. It should also ensure that the cotton thread and nichrome wire should burn completely. Mathematically,

Water Equivalent can be expressed as-

Water Equivalent (WE) in J/°C = [(Mf x HCV) + (Mt x CVt) + (Mnw x CVnw)]/∆t

Where, M = Mass of fuel sample burnt in the bomb in kg

HCV = Calorific value of the sample fuel; 26.5 kJ/gm for benzoic acid

Mt = Mass of thread in gm

Mnw = Mass of nichrome wire in gm

CVt = Calorific value of cotton thread, 17.55KJ/g

CVnw = Calorific value of nichrome wire, 1.4KJ/g

Conclusion:

From the above experiment we came to know the working principle of the bomb calorimeter and determined the

higher calorific value of the given fuel.

Quiz questions:

(i) Which type of CV is always found by bomb calorimeter and why?

(ii) Why bomb calorimeter is not used to determine the CV of gaseous fuels? What is the name of the calorimeter

which is used to determine the CV of gaseous fuel?

(iii) What will happen if the amount of fuel is very high in bomb calorimeter?

(iv) Why knowing the correct value of CV is important?

(v) What are the values of CV of gasoline and Diesel?


Sub: I C Engine Lab


Title : Load Test on Four Stroke Diesel Engine by Rope Brake Dynamometer.

Objective : To find out various performance parameters of a 4 stroke diesel engine.

Apparatus : Diesel engine test rig with brake rope dynamometer, stop watch, tachometer.

Introduction:

A dynamometer or "dyno" for short is a device for measuring force, moment of force (torque), or power. A

dynamometer can also be used to determine the torque and power required to operate a driven machine such as a

pump. In that case, motoring or driving dynamometer is used. A dynamometer that is designed to be driven is called

an absorption or passive dynamometer. A dynamometer that can either drive or absorb is called a universal or

active dynamometer. Rope brake dynamometer is an absorption dynamometer consisting of a rope encircling a brake

drum or flywheel, one end of the rope being loaded by weights and the other supported by a spring balance. The

effective torque absorbed is obtained by multiplying the drum radius by the difference of the tensions.

Measurement of brake power is one of the most important measurements of an engine. Apart from brake power

measurements some other performance parameters such as- brake specific fuel consumption, brake mean effective

pressure, volumetric efficiency etc. can also be measured during the experiment. If the above parameters can be found

out for different loads then the variation of any one parameter with other parameter can be plot graphically for analysis

such as load vs. brake specific fuel consumption, speed vs. load, speed vs. brake power etc. From the graphical

analysis the overall behavior of the engine with change in load can easily be analyzed.

Working principle of rope brake dynamometer:

In a rope brake dynamometer a rope is wrapped over the rime of a pulley or flywheel keyed to the crank shaft of the

engine. The flywheel mounted on the engine crank shaft is used as the dynamometer brake drum. The diameter of the

rope depends upon the power of the machine. The upper end of a rope is attached to the spring balance whereas the

lower end supports the weight of suspended mass. If the power is high, so will be the heat produced due to friction

between the rope and the wheel, and a cooling arrangement is necessary. For this, the flywheel usually has a hollow

section in which water is supplied. An outlet pipe with a flattened end takes the water out.

Let, W = Gross load applied in N = Pan weight + Rope weight + Force applied

S = Spring Balance reading in N

D = Diameter of the brake drum or flywheel in m

d = Diameter of rope

F = (W – S) = Effective load acting on the brake drum in N

N = rpm of the engine

The external moment or torque on the dynamometer is = (D + d) x (W – S) N-m

Therefore, work done per revolution = π x (D + d) x (W – S) N-m

Work done per minute = π x (D + d) x N x (W – S) N-m

Brake power (BP) in kW = π x (D + d) x N x (W – S) / (60x1000)

Procedure:

1. Before starting the engine check the fuel supply, lubricating oil and cooling water supply.

2. Set the dynamometer to zero load.

3. After starting the engine wait for sometimes so that the engine can reach to steady state condition.

4. After changing each and every load wait for sometimes before taking the necessary readings like fuel

consumption, air consumption, speed etc.

5. Bring the dynamometer load to zero, disengage the dynamometer and stop the engine.

6. Do the necessary calculations.

Specification of experimental set up:

Following are the specification of the used engine set up-

Diesel engine specification

Model Kirloskar TV1 model

Engine type Single cylinder, 4 stroke, vertical, naturally aspirated CI engine

Type of injection Direct injection

Type of cooling Water-Cooled

Rated Speed (rpm) 1500

Governing Class"A2 / B1"

Rated power output 7 BHP, 5.2 kW

Bore x Stroke 87.5 mm x 110 mm

Swept volume 661 cc

Clearance volume 38.35 cc

Compression ratio 17.5: 1

Nozzle opening pressure 210 bar

Fuel injection timing 23° BTDC

Lubricating oil SAE 30/40

Combustion chamber type Hemispherical open combustion chamber

Fuel injection pump MICO inline, with mechanical governor and flange mounted.

Test rig specification

Supplied by Apex Innovations Pvt. Ltd.

Manometer model MX 201

Manometer type U-tube

Burette range 0-50 ml

Dynamometer type Brake rope dynamometer, water cooled

Weight of the pan and rope 1kg

Diameter of the flywheel 0.35m

Diameter of rope 0.015m

Area of orifice 3.142m2

Observation table:

Sl.

no.

Weight

(N)

Spring

balance (N) RPM

Fuel consumption

(ml/min)

Water flow rate

(liter/sec)

Manometric head

of air in m of H2o


Following parameters can be found out from the experiment-

a) Brake power (BP):

Brake power is that part of the total power developed by the engine which is available at the output shaft of the engine.

Brake power can be measured by a rope brake dynamometer as:

Brake power (BP) in kW = π x (D + d) x N x (W – S) / (60x1000)

Now, if we neglect the rope diameter then BP in kW = π x D x N x (W – S) / (60x1000)

b) Volumetric efficiency (ηv):

It signifies the breathing capacity of the engine. More air means more fuel can be burned and more energy can be

converted to output power. Ideally, a volume of air equal to the swept volume of the engine should be inducted for

each cycle. But because of the short cycle time available and the flow restrictions presented by the air cleaner, intake

manifold and intake valves less than this ideal amount of air enters the cylinder. Volumetric efficiency is defined as-

Volumetric efficiency, ηv = Volume of air drawn inside the cylinder for one cycle

Swept volume of the engine × 100 %

= Volume flow rate of air

Swept volume of the engine × N

60

× 100 %

Where, Volume flow rate of air (m3/sec) is = Cd × A1× A0×√2gha

√A12−A0

2

Cd = Co-efficient of discharge of orificemeter, generally lies in between 0.64 to 0.75.

A1 = Area of pipe in m2

A0 = Area of orifice in m2

ha = Manometric head in m of air = (ρw x hw) / ρa

hw = Manometric head in m of water (from observation table)

ρw = Density of water

ρa = Density of air

N (rpm of engine) = N/2 for 4 stroke engine

= N for 2 stroke engine

c) Brake specific fuel consumption (BSFC):

Specific fuel consumption indicates the fuel consumed/hour per unit power output. It is of two types- Brake specific

fuel consumption and Indicated specific fuel consumption. BSFC indicates the rate of fuel consumed per unit brake

power output. BSFC can be found out as-

Brake specific fuel consumption, BSFC (kg/KW-hr) = mf / BP

Where, mf = fuel consumed per hour in kg/hr

BP = brake power produced

d) Brake mean effective pressure (BMEP):

It is an average pressure assumed to exist inside the cylinder under which the engine will produce same work which is

to be produced under actual variable working pressure. It is of two types- Brake mean effective pressure and Indicated

mean effective pressure. Assumption of mean effective pressure causes the calculations simpler than to be done under

variable working pressure. BMEP can be found out as-

Brake mean effective pressure (BMEP) = (BP × 60,000) / (Vs × N × K)

Where, BP = Brake power in KW

Vs = Swept volume in m2= (π × D2 × L) / 4

D = Diameter of cylinder in m

L = Stroke length in m

N = N/2 for 4 stroke engine

= N for 2 stroke engine

K = Number of cylinders

e) Brake thermal efficiency (ηbth):

Thermal efficiency indicates the ability of the combustion system to accept the fuel and provides comparable means of

assessing how efficiently the energy in the fuel is converting into mechanical output. It is two types- Brake thermal

efficiency and Indicated thermal efficiency. Brake thermal efficiency is the ratio of the energy associated with brake

power to the energy input given by fuel.

Brake thermal efficiency (ηbth) = BP

mf × CVf × 100 %

Where, BP = Brake power in ‘kW’

mf = Mass of fuel consumed in kg/sec

CVf = Calorific value of fuel in KJ/kg

Conclusion:

From the above experiment we came to know the working principle of rope brake dynamometer, determination of

various performance parameters, their significance and their variations with load and fuel consumption for a 4 stroke

CI engine.

Quiz questions:

(i) Which device is used in the engine to make the speed of the engine constant and how it works?

(ii) What is the significance of black, blue and white smoke in the exhaust of an engine?

(iii) How to find out the maximum load to be applied on the engine if it is not mentioned?

(iv) What will happen in the engine if the cooling water supply is improper?

(v) What are the other methods of determining BP except brake rope dynamometer?


Sub: I C Engine Lab


Title : Flue Gas Analysis by ORSAT Apparatus.

Objective : Analysis of exhaust gases of IC engine by Orsat Apparatus.

Apparatus : Orsat apparatus, caustic potash solution, alkaline solution of pyrogallic acid, cuprous

chloride solution, brine and dry flue gas sample.

Introduction:

Flue gas is the mixture of gases resulting from combustion and other reactions in combustion equipments like engines

and boilers, composed largely of nitrogen, carbon dioxide, carbon monoxide, water vapour, and often sulfur dioxide,

excess O2 and sometimes serving as a source from which carbon dioxide or other compounds are recovered. Based on

the fuel composition flue gases are formed, a fuel having carbon and hydrogen compounds generates flue gas

containing oxides of carbon and hydrogen. To check the combustion efficiency of I.C engines, it is essential to know

the constituents of the flue gases being exhausted. An Orsat gas analyzer is a piece of laboratory equipment used to

analyze a gas sample (typically fossil fuel or flue gas) for its oxygen, carbon monoxide and carbon dioxide content.

Orsat apparatus consists of a water-jacketed measuring burette, connected in series to a set of three absorption

pipettes, each through a stop-cock to absorb different gases.

Pipette 1: Contains ‘KOH’ (caustic soda or potassium hydroxide; 250g KOH in 500mL of boiled distilled water) to

absorb CO2

Pipette 2: Contains an alkaline solution of ‘pyrogallic acid’ (25g pyrogallic acid + 200g KOH in 500ml of distilled

water) to absorb O2 and CO2

Pipette 3: Contains an acid solution of ‘cuprous chloride’ (100g cuprous chloride + 125 ml liquor ammonia + 375 ml

of water) to absorb CO, O2 and CO2.

The other end is provided with a three-way stop-cock, the free end of which is further connected to a U-tube packed

with glass wool for avoiding the incoming of any smoke particles, etc. The graduated burette is surrounded by a water

jacket to keep the temperature of the gas constant during the experiment. The lower end of the burette is connected to

a water reservoir by means of long rubber tubing.

Working principle of Orsat analyzer:

Typical flue gas analyzers measure the quantity of carbon dioxide, carbon monoxide and oxygen by a chemical

absorption principle. Based on the absorption factor of these three components their respective absorbing solutions are

selected in three different pipette compartments. When the gas is passed into these pipettes consecutively, where each

component is separated in sequence, helps to know the volume drop from initial flue gas volume. Water vapour in flue

gas removed by adsorption on solid calcium chloride and then passed into three pipettes. It is necessary that the flue

gas is passed first through potassium hydroxide pipette where CO2 is absorbed, then through alkaline pyrogallic acid

pipette where only O2 will be absorbed (because CO2 has already been removed) and finally through cuprous chloride

pipette, where only CO will be absorbed (because CO2 and O2 has already been removed). At last the remaining

amount of flue gas is assumed to contain N2 only.

At first the flue gas is passed into caustic potash (KOH) solution pipette to absorb CO2 to form potassium

carbonate by the reaction: 2KOH + CO2 ↔ K2CO3 + H2O at ambient conditions.

Then gas is led to alkaline pyrogallic acid containing pipette to absorb oxygen by the reaction: 2C6H3(OH)3

(pyrogallol) + 2KOH (saturated alkaline) + O2 ↔ 4H2O + 2C5H3OCOOK and a physical color change is observed.

Finally the gas is led to cuprous chloride pipette to absorb carbon monoxide by the reaction: 2CuCl + 2CO →

[CuCl(CO)]2.

Figure 6.1: Orsat analyzer

Procedure:

1. The whole apparatus is thoroughly cleaned, stoppers greased and then tested for air-tightness. The absorption

pipettes are filled with their respective solutions to level just below their rubber connections.

2. Their stop-cocks are then closed. The jacket and levelling reservoir are filled with water.

3. The three-way stop-cock is opened to the atmosphere and reservoir is raised, till the burette is completely filled

with water and air is excluded from the burette.

4. The three-way stop-cock is now connected to the flue gas supply and the reservoir is lowered to draw in the flue

gas in the burette. The sample gas mixed with some air is present in the apparatus. So the three-way stop-cock is

opened to the atmosphere, and the gas expelled out by raising the reservoir. This process of sucking and

exhausting of gas is repeated 3-4 times, so as to expel the air from the capillary connecting tubes, etc. Finally, gas

is sucked in the burette and the volume of the flue gas is adjusted to 100 ml at atmospheric pressure.

5. For adjusting final volume, the three-way stop-cock is opened to atmosphere and the reservoir is carefully raised

till the level of water in it is the same as in the burette which stands at 100 ml mark. The three-way stop-cock is

then closed finally.

6. The stopper of the absorption pipette containing caustic potash solution is opened and all the gas is forced into this

pipette by raising the water reservoir.

7. The gas is again sent to the burette by lowering the water reservoir. This process is repeated several times to

ensure complete absorption of CO2 by KOH solution.

8. The unabsorbed gas is finally taken back to the burette, till the level of solution in the CO2 absorption pipette

stands at the constant mark and then, its stop-cock is closed.

9. The levels of water in the burette and reservoir are equalized and the volume of residual gas is noted. The decrease

in volume-gives the volume of CO2 in 100 ml of the flue gas sample.

10. The volumes of O2 and CO are similarly determined by passing the remaining gas through alkaline pyrogallic acid

pipette and cuprous chloride pipette respectively.

11. The gas remaining in burette after absorption of CO2, O2 and CO is taken as nitrogen.

Observation table:

Sl. No. Amount of CO2

(100 – X) ml

Amount of O2

(X – Y) ml

Amount of CO

(Y – Z) ml

Amount of N2

Z ml


Amount of flue gas sample = 100 ml

Amount of CO2 = (100 – X) ml; X = Final volume of flue gas taken out from the KOH pipette

Amount of O2 = (X – Y) ml; Y = Final volume of flue gas taken out from the alkaline pyrogallic pipette

Amount of CO = (Y – Z) ml; Z = Final volume of flue gas taken out from the cuprous chloride pipette

Amount of N2 = Z ml

Precautions:

a) The reagents in the absorption pipette 1, 2 and 3 should bring to the etched mark levels one-by-one by operating

the reservoir bottle and the valve of each pipette. Then their respective valves are closed.

b) All the air in the reservoir bottle is expelled to atmosphere by lifting the reservoir bottle and opening the three-

way to atmosphere.

c) It is quite necessary to follow the order of absorbing gases: CO2 first, O2 second and CO last.

Conclusion:

From the above experiment we came to know the working principle of Orsat analyzer and the very basic principle of

measuring CO2, O2, CO and N2 emission parameters.

Quiz questions:

(i) What will happen if the sequence of flue gas entering the pipettes is altered?

(ii) What will happen if at beginning of the test atmospheric air will remain in the apparatus?

(iii) What are the assumptions of the experiment?

(iv) Will we get the exact amount of N2 by the experiment? Justify your answer.

(v) What are the harmful effects of carbon dioxide and carbon monoxide?


Sub: I C Engine Lab


Title : Performance Test of a Muticylinder Petrol Engine by Morse Test.

Objective : To find the indicated power (IP) on multi-cylinder SI engine by Morse test.

Apparatus : Multi-Cylinder SI engine test rig, stop watch, digital tachometer.

Introduction:

The purpose of Morse Test is to obtain the Indicated power of a multi-cylinder engine. The test consists of running the

engine against a dynamometer at a constant speed making inoperative in turn each cylinder of the engine and noting

the reduction in brake power developed while maintaining the speed constant. For SI engine each cylinder is rendered

inoperative by shortening the spark plug of the respective cylinder and for CI engine by cutting off the fuel supply to

the respective cylinder. It is assumed that pumping and friction losses are the same when the cylinder is inoperative as

well as during firing. This test is applicable only to multicylinder engines. When one cylinder is cut off, power

developed is reduced and speed of the engine falls. Accordingly the load on the dynamometer is adjusted so as to

restore the engine speed. This is done to maintain frictional power constant, which is considered to be independent of

the load and proportional to the engine speed. The observed difference in BP between all cylinders firing and with one

cylinder cut off is the IP of the cut off cylinder. Summation of IP of all the cylinders would then give the total IP of

the engine under test.

Working principle of Morse test:

If there are k number of cylinders, then-

IP1 + IP2 + IP3 + . . . . . . . . . . + IPk = ∑ BPkk1 + FPk (1)

Where, IP, BP, FP are indicated, brake and frictional power and suffix k stands for cylinder number. If the 1st cylinder

is cut off, it will not produce any power but it will have friction, then-

IP2 + IP3 + IP4 +. . . . . . . . + IPk = ∑ BPkk2 + ∑ FPk

k1 (2)

Subtracting (2) from (1), IP1 = ∑ BPkk1 – ∑ BPk

k2

Similarly, we can find out the IP of the other cylinders. The total IP developed by the engine is given by- IPk = ∑ IPkk1 .

When all the k cylinders are working, it is possible to find the brake power BPk of the engine. The frictional power of

the engine is given by- FPk = IPk – BPk

Procedure:

1. Before starting the engine check the fuel supply, lubrication oil, and availability of cooling water.

2. Set the dynamometer to zero load.

3. Run the engine till it attains the working temperature and steady state condition. Adjust the dynamometer load to

obtain the desired engine speed. Record this engine speed and dynamometer reading for the BP calculation.

4. Now cut off one cylinder.

5. Reduce the dynamometer load to restore the engine speed to the desired constant value as recorded in step 3.

Record the dynamometer reading for BP calculation.

6. Connect the cut off cylinder and run the engine on all cylinders for a short time. This is necessary for the steady

state conditions.

7. Repeat steps 4, 5, and 6 for other remaining cylinders turn by turn and record the dynamometer readings for each

cylinder.

8. Bring the dynamometer load to zero, disengage the dynamometer and stop the engine.

9. Do the necessary calculations.

Observation table:

Sl. No. Cylinders Working Brake Power, BP (KW)

1. 1-2-3-4

2. 2-3-4 BP234=

3. 1-3-4 BP134=

4. 1-2-4 BP124=

5. 1-2-3 BP123=


Total brake power when all the cylinders are working, BPT =

Indicated power of 1st cylinder, IP1 = BPT – BP234

Indicated power of 2nd cylinder, IP2 = BPT – BP134

Indicated power of 3rd cylinder, IP3 = BPT – BP124

Indicated power of 4th cylinder, IP4 = BPT – BP123

Total Indicated power IPT = IP1 + IP2 + IP3 + IP4

Total frictional power, FPT = IPT – BPT

Conclusion:

From the above experiment we came to know the determination of IP, BP and FP of multi-cylinder engine based on

Morse test.

Quiz questions:

(i) Can we apply Morse test for single cylinder engine? Justify your answer.

(ii) What are the assumptions of the experiment?

(iii) Will all the cylinders produce equal power In case of multi-cylinder engine? Justify your answer.

(iv) Can we use Morse Test for CI engine?

(v) What are the other methods to fine the IP of an SI engine?

department of production engineeringhithaldia.ac.in/cm/pe/lab/12. me 692.pdf · study of valve...

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