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THERMAL ENGINEERING LAB MANUAL (For III Year B. Tech I Semester (R-14), Mechanical Engineering)
DEPARTMENT OF MECHANICAL ENGINEERING
SRI VENKATESWARA COLLEGE OF ENGINEERING AND TECHNOLOGY
(AUTONOMOUS)
R. V. S. NAGAR, CHITTOOR-517127.
Name of the student: _____________________________
Roll Number: ______________ Branch: ______________
Name of the Laboratory: __________________________
Year & Sem: _______________ Academic Year: _______
THERMAL ENGINEERING LAB MANUAL LIST OF EXPERIMENTS
1. Determination of Viscosity of lubricating oil using
i. Redwood Viscometer –I
ii. Redwood Viscometer –I
iii. Say bolt Viscometer.
2. Determination of Flash point and fire point of sample fluid using
i. Abel’s apparatus
ii. Pensky Marten’s apparatus.
3. Study of Bomb and Junker’s gas calorimeter to determine the Calorific value of fuels.
4. Study of the constructional details & working principles of two-stroke/ four stroke
petrol/diesel engine and to draw
i.Valve Timing Diagram
ii. Port Timing Diagram
5. Performance test on two stage reciprocating Air compressor.
6. Performance test and Preparation of Heat balance sheet on 4-stroke, single cylinder
diesel engine.
7. Retardation test on 4-stroke, single cylinder diesel engine
8. Morse test on 4-stroke, 4- cylinder petrol engine.
9. Performance test on 2- stroke, single cylinder petrol engine.
10. Performance test on refrigeration test rig.
11. Assembly and Disassembly of IC engines.
INDEX
S. No
Date Name of the Experiment Page No:
Signature of the
Faculty
AIM
To determine the viscosity in Redwood seconds of the given sample of oil and to
plot the variation of Redwood seconds, kinematic and dynamic viscosity with temperature. APPARATUS
o Redwood viscometer-I,
o Stopwatch,
o Thermometer (0-1100C)
o Measuring flask. (50 c.c.) THEORY
The viscosity of given oil is determined as the time of flow in Redwood seconds. The
viscosity of a fluid indicates the resistance offered to shear under laminar condition.
Dynamic viscosity of a fluid is the tangential force on unit area of either of two parallel
planes at unit distance apart when the space between the plates is filled with the fluid and
one of the plate’s moves relative to the other with unit velocity in its own plane. The unit of
dynamic viscosity is dyne-sec/cm2. Kinematic viscosity of a fluid is equal to the ratio of the
dynamic viscosity and density of the fluid. The unit of kinematic viscosity is cm2/sec. DESCRIPTION
Redwood viscometer-I consists of a water bath and oil bath, both provided with two
thermometers inside them. There is a ball valve, which is located at center of oil bath to
flow of oil through the orifice. A heater with regulator is fixed for heating purpose.
PROCEDURE
1. Clean the oil cup with a suitable solvent thoroughly and dry it using soft tissue paper.
2. Keep the ball valve in its position so as to keep the orifice closed.
RREEDD WWOOOODD VVIISSCCOOMMEETTEERR-- II
3. The water is taken into the water bath and the oil whose viscosity is to be
determined is taken into the oil cup up to the mark.
4. Note down the time taken in Redwood seconds for a collection of 50 cc . of oil
with a stopwatch at the room temperature without supply of electric supply.
5. Heat the bath and continuously stir it taking care to see that heating of the bath is
done in a careful and controlled manner.
6. When the desired temperature is reached, place the cleaned 50 c.c. Flask below
the orifice in position.
7. Remove the ball valve and simultaneously start a stopwatch. Note the time of
collection of oil up to the 50 c.c. Mark.
8. During the collection of oil don’t stir the bath. Repeat the process at various
temperatures.
OBSERVATIONS
Time for Kinematic
Absolute
viscosity
Oil collecting
Density () Viscosity
A t B
S. No. Temperature 50 c.c. of
gm
OC oil
t sec dyne sec/ cm 2
cm 2/ sec
sec
Where
A = 0.0026 cm2/sec2
B = 1.72 cm 2
GRAPHS TO BE DRAWN
1. Redwood seconds Vs . temperature
2. Kinematic Viscosity Vs . temperature
3. Absolute Viscosity Vs . temperature
MODEL GRAPHS
Te
mp
Redwood seconds Kinematic Viscosity Absolute Viscosity
PRECAUTIONS
1. Stir the water continuously so that the temperature of the oil and water are equal.
2. Before collecting the oil at a temperature, check whether the oil is up to the Indicator
in the oil cup.
3. Always take the readings at a stable temperature
4. Ensure proper setting of the ball valve to avoid leakage
RESULT Variation of Redwood seconds, absolute viscosity and Kinematic viscosity with
temperature, were observed and found to be decreasing with temperature.
AIM To determine the viscosity in redwood second of the given samples of oil and to plot the
variation of Redwood seconds, kinematic and dynamic viscosity with temperature. INSTRUMENTS: Redwood
viscometer-II, Stopwatch,
Thermometer (0-1100C),
Measuring flask. (50 c.c.) THEORY The viscosity of given oil is determined as the time of flow in redwood seconds. The
viscosity of a fluid indicates the resistance offered to shear under laminar condition.
Dynamic viscosity of a fluid is the tangential force on unit area of either of two parallel
planes at unit distance apart when the space between the plates is filled with the fluid and
one of the plate’s moves relative to the other with unit velocity in its own plane. The unit of
dynamic viscosity is dyne-sec/cm2. Kinematic viscosity of a fluid is equal to the ratio of the
dynamic viscosity and density of the fluid. The unit of kinematic viscosity is
cm 2
sec DESCRIPTION Redwood viscometer-II consists of a water bath and oil bath, both provided with two
thermometers inside them. There is a ball valve, which is located at center of oil bath to
flow of oil through the orifice. A heater with regulator is fixed for heating purpose. PROCEDURE
1. Clean the oil cup with a suitable solvent thoroughly and dry it using soft tissue paper.
2. Keep the ball valve in its position so as to keep the orifice closed.
3. The water is taken into the water bath and the oil whose viscosity is to be
determined is taken into the oil cup up to the mark.
RREEDD WWOOOODD VVIISSCCOOMMEETTEERR-- IIII
4. Before switch on the electric supply, at room temperature note down the time taken
in Redwood seconds for a collection of 50 c.c. of oil with a stopwatch.
5. Heat the bath and continuously stir it taking care to see that heating of the bath is
done in a careful and controlled manner.
6. When the desired temperature is reached, place the cleaned 50 c.c. flask below the
orifice in position.
7. Remove the ball valve and simultaneously start a stopwatch.
8. Note the time of collection of oil up to the 50 c.c. Mark.
9. During the collection of oil don’t stir the bath.
10. Repeat the process at various temperatures.
OBSERVATIONS
\
Time for
Kinematic Absolute
viscosity
Density Oil collecting
Viscosity
B () S. No. Temperature 50 c.c. of A t
0C oil t gm/sec dyne sec/ cm 2
cm 2/ sec
sec
Where
A = 0.0272 cm2/sec2 B = 11.2 cm 2
GRAPHS TO BE DRAWN
1. Redwood seconds vs. temperature
2. Kinematic Viscosity vs. temperature
3. Absolute Viscosity vs. temperature
MODEL GRAPHS
Te
mp
Redwood seconds Kinematic Viscosity Absolute Viscosity
PRECAUTIONS
1. Stir the water continuously so that the temperature of the oil and water are equal.
2. Before collecting the oil at a temperature, check whether the oil is up to the
Indicator in the oil cup.
3. Always take the readings at a stable temperature
4. Ensure proper setting of the ball valve to avoid leakage
RESULTS
Variation of Redwood seconds -II, absolute viscosity and Kinematic viscosity with
temperature, were observed and found to be decreasing with temperature
AIM
To determine the viscosity in Saybolt seconds of the given sample of oil and to plot
the variation of Saybolt seconds, kinematic and dynamic viscosity with temperature. INSTRUMENTS
o Saybolt viscometer,
o Stop watch,
o Thermometer (0-1100C),
o Measuring flask (60 cc) THEORY
The viscosity of given oil is determined as the time of flow in Saybolt seconds. The
viscosity of a fluid indicates the resistance offered to shear under laminar condition.
Dynamic viscosity of a fluid is the tangential force on unit area of either of two parallel
planes at unit distance apart when the space between the plates is filled with the fluid and
one of the plate’s moves relative to the other with unit velocity in its own plane. The unit of
dynamic viscosity is dyne-sec/cm2. Kinematic viscosity of a fluid is equal to the ratio of the
dynamic viscosity and density of the fluid. The unit of kinematic viscosity is
cm 2 sec .
DESCRIPTION
Saybolt viscometer consists of a water bath and oil bath, both provided with two
thermometers inside them. There is a ball valve, which is located at center of oil bath to
flow of oil through the orifice. A heater with regulator is fixed for heating purpose.
PROCEDURE
1. Clean the oil cup with a suitable solvent thoroughly and dry it using soft tissue paper.
2. Keep the cork in its position so as to keep the orifice closed.
3. The water is taken into the water bath and the oil whose viscosity is to be
determined is taken into the oil cup up to the mark.
SSAAYYBBOOLLTT VVIISSCCOOMMEETTEERR
4. Before switch on the electric supply, at room temperature note down the time
taken in Saybolt seconds for a collection of 60 c.c. of oil with a stop watch.
5. Heat the bath and continuously stir it taking care to see that heating of the bath is
done in a careful and controlled manner.
6. When the desired temperature is reached, place the cleaned 60 c.c. flask below
the orifice in position.
7. Remove the cork valve and simultaneously start a stopwatch. Note the time of
collection of oil up to the 60 c.c. Mark.
8. During the collection of oil don’t stir the bath.
9. Repeat the process at various temperatures.
OBSERVATIONS
Time for
Kinematic Absolute
viscosity
Density Oil collecting
Viscosity
B () S. No. Temperature 50 c.c. of A t
0C oil t gm dyne sec/ cm 2
cm 2/sec sec
sec
Where
A= 0.00226 cm2/sec2
B=1.8 cm 2
GRAPHS TO BE DRAWN
1. Saybolt seconds vs. temperature
2. Kinematic Viscosity vs. temperature
3. Dynamic Viscosity vs. temperature
MODEL GRAPHS
Te
mp
Redwood seconds Kinematic Viscosity Absolute Viscosity
Tem p
PRECAUTIONS
1. Stir the water continuously so that the temperature of the oil and water are equal.
2. Before collecting the oil at a temperature, check whether the oil is up to the level.
3. Always take the readings at a stable temperature.
4. Ensure proper setting of the cork to avoid leakage.
RESULT Variation of Saybolt Seconds, Absolute viscosity and Kinematic viscosity with temperature,
were observed and found to be decreasing with temperature.
AIM
To determine the flash and fire point of the given sample of oil using Abel’s
apparatus closed cup methods. APPARATUS
Abel’s apparatus, Thermo meter (0-110oC). THEORY
This method determines the closed cup flash and fire points of petroleum products
and mixtures to ascertain whether they give off inflammable vapours below a certain
temperature. FLASH POINT: It is the lowest temperatures of the oil, at which, application of test flame causes the vapour
above the sample to ignite with a distinct flash inside the cup. FIRE POINT: It is the lowest temperature of the oil, at which, application of test flame causes burning for
a period of about five seconds. DESCRIPTION
The apparatus consists of a brass cup and cover fitted with shutter mechanism, test
flame arrangement, hand stirrer, thermometer socket. The brass cup is heated by water
bath (with energy regulator), fitted with a funnel and overflow pipe. PROCEDURE
1. Clean the oil cup and fill the up to the mark with the sample oil.
2. Insert the thermometer into the oil cup through the provision to note down the oil
temperature.
3. Using the Energy regulator, control the power supply given to the heater and rate of
heating
4. The oil is heated slowly when temperature of oil rises; it is checked for the flash point
for every one-degree rise in temperature.
AABBEELL’’SS FFLLAASSHH AANNDD FFIIRREE PPOOIINNTT TTEESSTT
5. After determining the flash point, the heating shall be further continued. The
temperature at which time of flame application that causes burning for a period at
least 5 seconds shall be recorded as the fire point.
6. Repeat the experiment 2 or 3 times with fresh sample of the same oil
7. Take the average value of flash and fire points.
PRECAUTIONS:
1. Stir the oil bath continuously to maintain the uniform temperature of sample oil.
2. The bluish halo that some time surrounds the test flame should not be
confused with true flash. OBSERVATIONS:
Sample oil Flash Point, 0 C Fire Point, 0 C
RESULT
The flash point is observed at _____ 0 C
The fire point is observed at ______ 0 C
AIM
To determine the flash and fire point of the given sample of oil using Pensky
Marten’s apparatus by both open and closed cup methods. APPARATUS
o Pensky Marten’s apparatus,
o Thermometer (0-110oC). THEORY
This method determines the closed cup and open cup flash and fire points of
petroleum products and mixtures to ascertain whether they give off inflammable vapours
below a certain temperature. Flash Point: It is the lowest temperatures of the oil at which application of test flame
causes the vapour above the sample to ignite with a distinct flash inside the cup.
Fire point It is the lowest temperature of the oil, at which, application of test flame causes
burning for a period of about five seconds.
DESCRIPTION
The apparatus consists of a brass cup and cover fitted with shutter mechanism
without shutter mechanism (open cup), test flame arrangement, hand stirrer (closed cup),
thermometer socket, etc., heated with energy regulator, a thermometer socket made of
copper. PROCEDURE
1. Clean the oil cup thoroughly and fill the oil cup with the sample oil to be tested up to
the mark.
2. Insert the thermometer into the oil cup through a provision, which measures the rise
of oil temperature.
3. Using the Energy regulator, control the power supply given to the heater and rate of
heating
4. The oil is heated slowly when temperature of oil rises, it is checked for the flash point
for every one degree rise in temperature.
PPEENNSSKKYY MMAARRTTEENN’’SS FFLLAASSHH AANNDD FFIIRREE PPOOIINNTT
5. After determining the flash point, the heating shall be further continued. The
temperature at which time of flame application which causes burning for a period at
least 5 seconds shall be recorded as the fire point.
6. Repeat the experiment 2 or 3 times with fresh sample of the same oil
7. Take the average value of flash and fire points.
PRECAUTIONS
1. Stir the oil bath continuously to maintain the uniform temperature of sample oil.
2. The bluish halo that some time surrounds the test flame should not be confused with
true flash.
OBSERVATIONS
Sample oil Flash Point, 0 C Fire Point, 0 C
RESULT
The flash point is observed at _________ 0 C
The fire point is observed at _____________ 0 C
AIM
To determine the water equivalent of the calorimeter using the given sample of solid
or liquid fuel of known calorific value (or) To determine the calorific value of the given solid
or liquid fuel if the water equivalent of the calorimeter known.
APPARATUS
Bomb, water jacket, stirrer, calorimeter vessel, combined lid, sensitive thermometer,
analytical balance with weight box, oxygen cylinder with pressure gauge, fuse wire, cotton
thread, firing unit, regulating valve and crucible hand pellet press
PRINCIPLE OF OPERATION
A Bomb Calorimeter will measure the amount of heat generated when matter is
burnt in a sealed chamber (Bomb) in an atmosphere of pure oxygen gas. A known amount
of the sample of fuel is burnt in the sealed bomb, the air in the bomb being replaced by
pure oxygen under pressure. The sample is ignited electrically. As the sample burns heat is
produced and rises in the temperature. Since the amount of heat produced by burning the
sample must be equal to the amount of heat absorbed by the calorimeter assembly, and
rise in temperature enables the determination of heat of the combustion of the sample. If
W = Water equivalent of the calorimeter assembly in calories per degree centigrade. T
= Rise in temperature (registered by a sensitive thermometer) in
degrees centigrade.
H = Heat of combustion of material in calories per gram. M
= Mass of sample burnt in grams.
Then W T H M
If the water equivalent of the calorimeter is to be determined, a substance like Benzoic acid
has a stable calorific value can be burnt in the bomb. Assuming the calorific value of
Benzoic acid and water equivalent can be determined.
BBOOMMBB CCAALLOORRIIMMEETTEERR
CALORIFIC VALUE
Gross or higher calorific value: The total amount of heat produced when one unit
mass of fuel has been burnt completely and the products of combustion have been cooled
to room temperature.
Net or Lower Calorific Value: The net heat produced when unit mass of fuel is burnt
completely and the products are permitted to escape.
LCV = HCV – Latent heat of water vapour formed DESCRIPTION
i. BOMB
The bomb consists of three parts i.e. bomb body, lid and the cap. Bomb Body
and the lid are made of corrosion resistant stainless steel containing Chromium,
Nickel and Molybdenum. The bomb body is cylindrical vessel having a capacity
of 300 ml. The walls are strong enough to withstand the normal operating
pressure (30atm) to extreme high pressures (300 atm.). During burning at high
pressure the nitrogen and sulphur contents are oxidized to nitric acid and
sulphuric acid respectively. The corrosion resistant nature of the bomb material
protects it from corrosive vapors. The bomb has lid, which is provided with two
terminals. The metallic rods pass through the terminals one of which are
provided with a ring for placing the crucible with a small hook and the other with a
groove. Each rod is also provided with a ring to press the fuse wire attached to it.
The upper side of the lid also provided with a small hook rod lifting and with a
Schrader valve for filling oxygen in the bomb
ii. WATER JACKET
The water jacket is made of copper and is highly chromium plated on the inside
and outside to minimize radiative losses. The jacket is filled with water.
iii. STIRRER UNIT
A stirrer is provided which is driven directly by an electric motor. The stirrer is
immersed in the water. The water is continuously stirred during the experiment
for uniform heat distribution.
iv. COMBINED LID
This is made of Borolite sheet and is provided with a hole for to keep the stirrer
unit in fixed position and hole to insert the temperature sensor. It has also
another hole to take out the connecting wires from the terminals on the bomb lid
to firing unit.
v. HAND PELLET PRESS
It is used for pressing the powder into a pellet.
vi. CRUCIBLE
It is made of stainless steel. The fuel to be burnt is weighed in this crucible.
vii. IGNITION WIRE
It is recommended that platinum wire used but an alternative nichrome wire is
also being offered.
viii. FIRING UNIT
It consists of the firing key, provision to give power to the stirrer motor, a switch
for operating the stirrer motor, two indicating lamps. When the circuit is
completed the indicating lamp glows. After the firing key is closed on, the fuse
wire burns, the indicating lamp stops glowing indicating the burning of the fuse
wire. PROCEDURE
About 0.5 to 1 grm of finely ground benzoic acid (Preferably compressed into a
pellet) is accurately weighed and taken into crucible.
Place the bomb lid on the stand provided and stretch pieces of fuse wire across
the electrodes (metal rods) provided in the lid tie about 5 cm of sewing cotton round
the wire.
Place the crucible in position and arrange the loose end of the cotton thread to
contact the Benzoic acid pellet in the crucible.
About 10 ml of distilled water are introduced into the bomb to absorb vapors of
sulphuric acid and nitric acids formed during the combustion and lid of the bomb is
screwed
Charge the bomb slowly with oxygen from the oxygen cylinder to a pressure of 25
atm. close the value and detach the bomb from the oxygen supply.
Fill the calorimeter vessel with sufficient water to submerge the cap of the bomb to a
depth of at least 2mm leaving the terminals projecting lower the bomb carefully in
the calorimeter vessel and after ascertaining that it is gas tight, connect the
terminals to the ignition circuit.
Adjust the stirrer and place the temperature sensor and cover in position. Start the
stirring mechanism, which must be kept in continuous operation during the
experiment after stirring for 5 minutes note the temperature reading of the
calorimeter. Close the circuit momentarily to fire the charge and continue the
observations of the temperature at an interval of one minute till the rate of change of
temperature becomes constant.
Afterwards stop the stirrer and remove the power supply to the firing unit. Remove
the bomb from the calorimeter and relax the pressure by opening the value. Verify
that the combustion is complete and washout the contents of the bomb clean and
dry.
Calculate the calorific value of the fuel or water equivalent of the calorimeter.
OBSERVATIONS:
Weight of the empty crucible W1 = gm
Weight of the empty crucible + Benzoic acid pellet W2 = gm
Weight of the benzoic acid pellet W2 W1 = gm
Weight of water taken in the calorimeter W3 = gm
Temperature of the water just before firing t1 = 0 C
Temperature of the water after firing t3 = 0 C
CALCULATIONS
Heat produced by burning of benzoic acid + Heat produced by burning of fuse wire
and cotton wire etc = Heat absorbed by calorimeter.
W2 W1 Cv W3 We t2 t1
PRECAUTIONS
Sample should not exceed 1 gms .
Don’t charge with more oxygen than is necessary.
Don’t fire the bomb if gas bubbles are leaking from the bomb when it is submerged in
water.
RESULT
Water equivalent of calorimeter We = gm
Calorific value of sample Cv = Cal/ gm
RESULT
Water equivalent of calorimeter We = gm
Calorific value of sample Cv = Cal/gm
AIM
To find the calorific value of given gaseous fuel. APPARATUS i) Calorimeter
a) Main calorimeter body
b) Three thermometers ii) Gas flow meter
a) Main gas flow meter body
b) Inlet / outlet nozzles
c) Union net with washer for thermometers iii) Pressure governor
a) Pressure governor body
b) Balancing beam arrangement
c) Counter balance tube
d) Inlet and outlet union nuts with washers and iv) Jars 2000 ml & 50 ml
PROCEDURE 1. Pour water into the governor till water starts overflowing through the overflow passage. 2. Replace and tighten the over flow nut. 3. Insert three thermometers provided with calorimeter into the rubber corks. 4. Insert rubber corks with thermometers into their places in calorimeter. 5. Insert burner into its support rod in the bottom of the calorimeter and turn the knurled
knob so that the burner is fixed tightly. The burner must go into the center of the
calorimeter body. 6. Connect the calorimeter, the flow meter and the pressure governor as shown in figure
using rubber tubing provided. Do not connect gas supply line. Take care to see that the
water regulator of calorimeter is in OFF position.
JJUUNNKKEERR’’SS GGAASS CCAALLOORRIIMMEETTEERR
7. Turn water regulator knob on calorimeter to ON position. Allow water to flow through the
calorimeter from overhead tank/ tap. Allow water to flow for 3 to 4 min into laboratory
sink, through the calorimeter. 8. Ensure that outlet tap of governor is closed. Connect gas supply line to governor inlet.
Remove burner from calorimeter then open governor outlet tap. Allow gas to pass
through the burner. 9. Light up the burner by holding a lighted match stick near the mesh at the top. 10. Adjust the air regulator sleeve at the bottom of the burner to get a blue, non-luminous
flame. Fix the lighted burner back into position. 11. Adjust water regulator on calorimeter to get a temperature difference of 12 0 C to
15 0 C between the inlet water & outlet water as indicated by the respective
Thermometers at the top of the calorimeter. 12. Allow 20 to 30 min for outlet water temperature to become steady. 13. Measure the water flow rate with the help of measuring jar. Simultaneously, note the
flow meter reading.
14. Note down the inlet &outlet water temperatures. 15. Repeat the test with same volume of gas 3 or 4 times and take average temperatures of
inlet and outlet water. CALCULATIONS
The formula to be used to calculate the calorific value to the test gas is as follows
C V = VW
x (T2-T1)x1000 VG
Where
C.V = calorific value of gas in Kcal
m3
VG = volume of gas in liters consume during test period
Vw = volume of water in liters passed during test period
VVAALLVVEE TTIIMMIINNGG DDIIAAGGRRAAMM
VALVE TIMING DIAGRAM ON SECTIONAL MODEL OF 4-STROKE SINGLE CYLINDER
DIESEL ENGINE
AIM:-To draw the actual valve timing diagram of a four-stroke single cylinder vertical diesel
engine.
APPARATUS:-Thread, scale, sectional four stroke single cylinder diesel engine test rig.
THEORY:-
Valve timing is the regulation of the points in the cycle at which the valves are set to
open and close. While the intake and exhaust valves should open, theoretically, at dead
centers, almost all SI engines employ an intake and exhaust valves opening and closing
a few degrees before dead centers .There are two factors: Mechanical and Dynamic for
the actual valve timing to be different from the theoretical valve timing.
a) Mechanical factor:-
The valves of a reciprocating engine are operated by cam mechanism. To avoid noise
and wear, the valve should be lifted slowly. For the same reason the valve cannot be
closed abruptly else it will bounce on its seat. Then the opening and closing periods are
spread over a considerable number of crank shaft degrees. As a result the opening of
the valve must commence a head of time at which it is fully opened. The same reason
applied for the closing time and valve must close after dead centers.
b) Dynamic factor:-
Besides the mechanical factor the actual valve timing is set taking the dynamic effects
of gas flow into consideration. As the piston moves all in the suction stroke, the fresh
air is drawn into the cylinder through the inlet valve when the piston reaches the BDC
and to move towards TDC in the compression stroke, the inertia of the entering fresh air
tends to cause to continue to move in the cylinder after BDC.
The exhaust valve is set to open before BDC. By earlier opening of the exhaust valve,
the scavenging period is increased. Also earlier opening means that exhaust pressure
is higher than the atmospheric pressure, which helps in scavenging process. The
exhaust valve is closed a few degrees after TDC. The inertia of the exhaust gases
tends to scavenge the cylinder by carrying out a greater mass gas lift in Clearance
volume. For some period there is valve overlapping i.e., the kinetic energy of fresh
charge helps in forcing out at exhaust gases.
WORKING PRINCIPLE:-
In a four stroke engine, the thermodynamic cycle of operations is completed in two
revolutions of the crank shaft or four strokes of the piston. During the four strokes, there are
five events to be completed, viz., suction, compression, combustion, expansion and
exhaust.
Suction stroke starts when the piston is at TDC and about to move downwards. The
inlet valve is open at this time and exhaust valve is closed. Due to the suction created by
the motion of the piston towards the BDC, air is drawn into the cylinder. When the piston
reaches the BDC the suction stroke ends and the inlet valve closes.
The air taken into the cylinder during the suction stroke is compressed by the return
stroke of the piston. During this stroke both inlet and exhaust valves are in closed position.
The air is now compressed to the clearance volume. At the end of the compression stroke
a metered quantity of fuel (diesel) is injected into the hot compressed air in fine sprays by
the fuel injector and it starts burning. During burning process the chemical energy of the
fuel is converted into heat energy.
The high pressure of the burnt gases forces the piston towards the BDC. Both the
valves are in closed position. Of the four-strokes only during this stroke, power is produced.
Both pressure and temperature decreases during expansion.
At the end of the expansion stroke the exhaust valve opens and the inlet valve remains
closed. The pressure falls to atmospheric level as a part of the burnt gases escape. The
piston starts moving from BDC to TDC and sweeps the burnt gases out from the cylinder.
The exhaust valve closes when the piston reaches TDC.
PROCEDURE:-
1. T.D.C. is identified and marked on the fly wheel with respect to one fixed point in the
engine.
2. The circumference of fly wheel is measured using thread and scale.
3. The BDC is marked on the flywheel by taking half the circumference.
4. By slowly cranking the camshaft in the direction of rotation the opening of inlet valve
is marked on the fly wheel w.r.t. fixed point when the push rod of inlet valve
becomes tight to move.
5. Mark a point on the fly wheel where the inlet valve is completely closed.
6. In the same way mark the points where the exhaust valve open and close.
7. The distance of opening of inlet valve and closing of exhaust valve from TDC and
closing of inlet valve and opening of the exhaust valve from BDC are measured
using thread and scale.
8. The angles of opening and closing of inlet and exhaust valves are calculated w.r.t.
TDC and BDC.
PRECAUTIONS:-
1. The decompression lever must be checked (Should be in disengaged position) when
conducting the test.
2. Cranking should be done carefully and slowly so that the salient points are located
carefully.
OBSERVATIONS: circumference of the fly wheel = 2R
Sl.No. Event Distance from nearest dead
center Angle
1 IVO
2 IVC
3 EVO
4 EVC
5 FI
IVO = Inlet valve open
IVC = Inlet valve close
EVO = Exhaust valve open
EVC = Exhaust valve close
FI = Fuel Injection
1 cm = (1 rev of fly wheel / circumference of fly wheel) 0
X cm = X * (360/ π D) 0
Where D= diameter of the fly wheel in cm
Model Calculations:
1. Inlet valve opens at ……. cm before TDC =….. X 30 = …..0
2. Inlet valve closes at …….
3. Exhaust valve opens at
4. Exhaust valve closes at
5. Total suction process = IVO to IVC =
6. Total compression = BDC to TDC =
7. Total expansion = TDC to EVO =
8. Total exhaust = EVO to EVC =
RESULT:-
1. Total suction process :
2. Total compression process :
3. Total expansion process :
4. Total exhaust process :
5. Fuel Injection at :
PPOORRTT TTIIMMIINNGG DDIIAAGGRRAAMM
PORT TIMING DIAGRAM ON SECTIONAL MODEL OF 2-STROKE SINGLE CYLINDER
PETROL ENGINE
AIM: To draw the actual port timing diagram of a two stroke single cylinder petrol engine.
APPARATUS: Thread, scale, sectional single cylinder two stroke petrol engine test rig.
THEORY:
Port timing is the determination of points in the cycle at which the ports are set to open
and close. In the ideal cycle inlet, exhaust and transfer port opens and closes at dead
centers, but there is a difference between actual and ideal cycle.
WORKING PRINCIPLE:-
In two-stroke engine the cycle is completed in one revolution of the
crankshaft. The main difference between two-stroke and four stroke engines is in the
method of filling the fresh charge and removing the burnt gases from the cylinder. In the
four-stroke engine these operations are performed by the engine piston during the suction
and exhaust strokes respectively. In a two-stroke engine, the filling process is
accomplished by the charge compressed in crankcase or by a blower. The induction of the
compressed charge moves out of the product of combustion through exhaust ports.
Therefore, no piston strokes are required for these two operations. Two strokes are
sufficient to complete the cycle, one for compressing the fresh charge and the other for
expansion or power stroke.
The air or charge is inducted into the crankcase through the spring loaded
inlet port when the pressure in the crankcase is reduced due to the upward motion of the
piston during compression stroke. After compression and ignition, expansion takes place in
the usual way.
During the expansion stroke the charge in the crankcase is compressed. Near
the end of the expansion stroke, the piston uncovers the exhaust ports and the cyl inder
pressure drops to atmospheric pressure as the combustion products leave the cylinder.
Further movement of the piston uncovers the transfer port, permitting the slightly
compressed charge in the crankcase to enter the engine cylinder.
PROCEDURE:
1. The circumference of the flywheel is measured using thread and scale.
2. T.D.C. is identified and marked on the flywheel with respect to one fixed point in the
engine.
3. The B.D.C. is measured on the fly wheel by taking half of the circumference.
4. Mark various points on the flywheel relative to the opening and closing of ports.
OBSERVATIONS:-
S.NO Event Distance From Nearest
dead center Crank angle
1. IPO
2. IPC
3. TPO
4. TPC
5. EPO
6. EPC
I.P.O = Inlet port open
I.P.C = Inlet port close
T.P.O = Transfer port open
T.P.C = Transfer port close
E.P.O = Exhaust port open
E.P.C = Exhaust port close
1 cm = (1 rev of fly wheel / circumference of fly wheel) 0
X cm = X * (360/ ∏ D) 0
Model Calculations:
1. Transfer port opens at ….. cm before BDC = …… 0 before BDC.
2. Transfer port closes at
3. Exhaust port opens at
4. Exhaust port closes at
5. Spark ignition is produced at
RESULT:-
1. Total suction process:
2. Total compression process:
3. Total expansion process:
4. Total exhaust process
PPEERRFFOORRMMAANNCCEE TTEESSTT OONN TTWWOO SSTTAAGGEE RREECCIIPPRROOCCAATTIINNGG
AAIIRR CCOOMMPPRREESSSSOORR
PERFORMANCE TEST ON TWO STAGE RECIPROCATING AIR COMPRESSOR
AIM:
To conduct performance test on reciprocating air compressor, to determine its volumetric
efficiency and Isothermal efficiency.
EQUIPMENT /APPARATUS:
1. Two stage air compressor
2. Tachometer 0-2000 rpm
3. Stop watch
SPECIFICATIONS: Make : Altech
Dia. of low pressure piston : 70 mm
Dia. of High Pressure Piston : 50 mm
Stroke : 90 mm
Operating Pressure : 8 kgf / cm2
Speed : 700 rpm
Diameter of orifice : 20 mm
Power : 3 HP
Energy Meter Constant : 300 rev/kwh
DESCRIPTION:
The air compressor is a two stage, reciprocating type. The air is sucked from
atmosphere and compressed in the first cylinder. The compressed air then passes through
an inter cooler into the second stage cylinder, the compressed air then goes to reservoir
through safety valve. This valve operates an electrical switch that shuts off the motor when
pressure exceeds the set limit.
The test consists of an air chamber containing an orifice plate and a u-tube
manometer, the compressor and an induction motor.
PROCEDURE:
1) Open the discharge valve of the compressor and drain off air completely and
Close the valve.
2) Start the compressor, by starting the compressor motor & observe the pressure
developing slowly
3) At the particular test pressure, the outlet valve is opened slowly and adjusted so
that the pressure in the tank maintained constant.
4) At the particular test pressure, note the following reading
(i) Manometer,
(ii) Speed of the compressor,
(iii) Pressure,
(Iv) Time taken for 10 revolutions of energy meter.
5) Close the discharge valve so that pressure increases.
6) Repeat the above procedure for different pressures.
7) Switch off the power supply and stop the compressor.
PRECAUTIONS:
1. Check oil level in the compressor crank case
2. The orifice should never be closed
3. At the end of the experiment the outlet valve at of the reservoir should be opened as
the compressor is to be started again at low pressure to prevent undue strain on the
piston.
OBSERVATIONS:
S.No. Gauge
Pressure (kgf/cm2)
manometer readings in m
of water
Air head causing
flow in m of water
Speed
Actual Volume
Va
m3 / Sec
Theoretical Volume,
Vt
m3 / Sec
vol
% h1 h2 hw
1.
2.
3.
4.
5.
`
S.No.
Gauge Pressure (kgf/cm2)
Time for ‘n’ no: of
revolutions of Energy meter ‘s’
Motor input=
tk
n
3600
KW
Motor output=
8.0
motorinput
KW
Compressor input=
95.08.0
motorinput
KW
Compressor output=
ClnVP aa
KW
iso
%
1.
2.
3.
4.
5.
CALCULATIONS:
1. Actual Air intake:
Manometer reading h1 = …………..mm of water
Manometer reading h2 = …………..mm of water
Difference in water level, hw = 1000
21 hh m of water
Equivalent air column, ha = 16.1
1000
ww h
AirofDensity
waterofDensityh ….m. of air
Where hw = m. of water column
ha =m. of air column
w =Density of water in kg/m3 (1000 kg/m3)
a =Density of air in kg/m3 (1.16 kg/m3)
2. The actual volume of air compressed, Va = Cd a agh2 …..m3 / Sec
Where Cd=co efficient of discharge for the orifice =0.62
Orifice diameter = 0.02 m
Area of orifice, a = 4
)02.0( 2 = …..m2
ha= equivalent air column in ‘m’ of water
3. Theoretical volume of air compressed, Vt = 60
NLD4
2
…..m3 / Sec
Diameter of piston, D = 0.07 m
Stroke length, L = 0.09 m
Speed of the compressor, N = ……..rpm
4. Volumetric efficiency = 100V
V
t
a
5. Compressor input = Motor input 95.08.0 …..KW
Where
Energy meter constant, K= 300 Rev/KWh
Time for ‘n’ number of rev. = t sec
Motor input = tK
n
3600…….. KW
Efficiency of motor = 80%
Output of motor = Motor input 8.0
Belt transmission efficiency = 95 %( assumed)
Compressor input = Motor input 95.08.0 …..KW
6. Compressor output = ClnVP aa …….Kw
Compression ratio, C = pressure Atm.
pressure Atm. pressure Gauge
= 1.01325
1.01325 pressure Gauge
Note: Gauge pressure in Kgf/cm2
Pa= Atmospheric pressure = 101.325 KPa
Va= Actual volume of air compressed m3/sec
7. Isothermal efficiency = 100input Compressor
output Compressor
Model Graphs: Pressure Pressure Result:
Volu
met
ric
Eff
icie
ncy
Isoth
erm
al
Eff
icie
ncy
PPEERRFFOORRMMAANNCCEE TTEESSTT OONN 44--SSTTRROOKKEE,,
SSIINNGGLLEE CCYYLLIINNDDEERR DDIIEESSEELL EENNGGIINNEE
PPEERRFFOORRMMAANNCCEE TTEESSTT OONN 44--SSTTRROOKKEE SSIINNGGLLEE CCYYLLIINNDDEERR DDIIEESSEELL EENNGGIINNEE
AAIIMM:: TToo ccoonndduucctt aa ppeerrffoorrmmaannccee tteesstt oonn 44--ssttrrookkee ssiinnggllee ccyylliinnddeerr ddiieesseell eennggiinnee
uunnddeerr vvaarriioouuss llooaaddss..
EEQQUUIIPPMMEENNTT//AAPPPPAARRAATTUUSS::
11.. 44--SSttrrookkee,, ssiinnggllee ccyylliinnddeerr DDiieesseell eennggiinnee wwiitthh aa rrooppee bbrraakkee ddyynnaammoommeetteerr TTeesstt rriigg
22.. SSttooppwwaattcchh..
SSPPEECCIIFFIICCAATTIIOONNSS::
MMaakkee :: KKiirrlloosskkaarr
BBoorree :: 8800mmmm
SSttrrookkee :: 111100 mmmm
RRaatteedd SSppeeeedd :: 11550000 rrppmm
MMaaxx.. BB..PP :: 33..77KKWW ((55 HH..PP))
CCoommpprreessssiioonn RRaattiioo :: 1166..55::11
OOrriiffiiccee DDiiaammeetteerr :: 2200 mmmm
FFuueell :: DDiieesseell
DDeennssiittyy ooff DDiieesseell :: 882277 KKgg//mm33
SSppeecciiffiicc ggrraavviittyy ooff DDiieesseell :: 00..882277
CCaalloorriiffiicc VVaalluuee ooff DDiieesseell :: 4433440000 KKJJ // kkgg
BBrraakkee ddrruumm ddiiaammeetteerr :: 336600 mmmm
RRooppee ddiiaammeetteerr :: 1155 mmmm
EEqquuiivvaalleenntt ddiiaammeetteerr :: 337755 mmmm
CCooeeffffiicciieenntt ooff ddiisscchhaarrggee :: 00..6622
DDEESSCCRRIIPPTTIIOONN::
This is a water cooled single cylinder vertical diesel engine. It is coupled to a rope
pulley brake arrangement to absorb the power produced. Necessary weights and spring
balances are included to apply load on the brake drum. Suitable cooling water arrangement
for the brake drum is provided. Separate cooling water lines are provided for the engine
cooling. Thermocouples are provided for measuring temperature. A fuel measuring system
consists of a fuel tank mounted on a stand, burette, and a 3-way cork.
Air consumption is measured by using a M.S. tank, which is fitted with a standard
orifice and a U-tube water manometer that measures the pressures inside the tank..
TTHHEEOORRYY::
SSiinnggllee ccyylliinnddeerr ssttaattiioonnaarryy,, ccoonnssttaanntt ssppeeeedd ddiieesseell eennggiinneess aarree ggeenneerraallllyy qquuaalliittyy
ggoovveerrnneedd.. AAss ssuucchh tthhee aaiirr ssuupppplliieedd ttoo tthhee eennggiinnee iiss nnoott tthhrroottttlleedd aass iinn tthhee ccaassee ooff SS..II..
eennggiinneess.. TToo mmeeeett tthhee ppoowweerr rreeqquuiirreemmeennttss ooff tthhee sshhaafftt,, tthhee qquuaannttiittyy ooff ffuueell iinnjjeecctteedd iinnttoo tthhee
ccyylliinnddeerr iiss vvaarriieedd bbyy tthhee rraacckk iinn tthhee ffuueell ppuummpp.. TThhee rraacckk iiss uussuuaallllyy ccoonnttrroolllleedd bbyy aa ggoovveerrnnoorr
oorr bbyy aa hhaanndd.. TThhee aaiirr ffllooww rraattee ooff ssiinnggllee ccyylliinnddeerr eennggiinnee ooppeerraattiinngg aatt ccoonnssttaanntt ssppeeeedd ddooeess
nnoott vvaarryy aapppprreecciiaabbllyy wwiitthh tthhee oouuttppuutt ooff tthhee eennggiinnee.. SSiinnccee tthhee ffuueell ffllooww rraattee vvaarriieess mmoorree oorr
lleessss lliinneeaarrllyy wwiitthh oouuttppuutt,, tthhee ffuueell aaiirr rraattiioo iinnccrreeaasseess wwiitthh oouuttppuutt.. PPeerrffoorrmmaannccee tteessttss ccaann bbee
ccoonndduucctteedd eeiitthheerr aatt ccoonnssttaanntt ssppeeeedd ((oorr)) aatt ccoonnssttaanntt tthhrroottttllee.. TThhee ccoonnssttaanntt ssppeeeedd mmeetthhoodd
yyiieellddss tthhee FF..PP.. ooff tthhee eennggiinnee..
TThhee eennggiinnee ppeerrffoorrmmaannccee iiss iinnddiiccaatteedd bbyy tthhee tteerrmm ““eeffffiicciieennccyy””.. FFiivvee iimmppoorrttaanntt
eennggiinnee eeffffiicciieenncciieess aanndd ootthheerr rreellaatteedd eennggiinnee ppeerrffoorrmmaannccee ppaarraammeetteerrss aarree::
11.. IInnddiiccaatteedd tthheerrmmaall eeffffiicciieennccyy 22..BBrraakkee tthheerrmmaall eeffffiicciieennccyy
33.. MMeecchhaanniiccaall eeffffiicciieennccyy 44..VVoolluummeettrriicc eeffffiicciieennccyy
55.. RReellaattiivvee eeffffiicciieennccyy 66..MMeeaann eeffffeeccttiivvee pprreessssuurree
77.. SSppeecciiffiicc ppoowweerr oouuttppuutt 88..SSppeecciiffiicc ffuueell ccoonnssuummppttiioonn
99.. FFuueell--aaiirr rraattiioo 1100..CCaalloorriiffiicc vvaalluuee ooff tthhee ffuueell
SSTTAARRTTIINNGG TTHHEE EENNGGIINNEE::
11.. EEnnggaaggee ddee--ccoommpprreessssiioonn lleevveerr bbeeffoorree ccrraannkkiinngg..
22.. CCrraannkk tthhee eennggiinnee aanndd ddiisseennggaaggee tthhee ddee--ccoommpprreessssiioonn lleevveerr..
33.. AAddjjuusstt tthhee ggoovveerrnnoorr ttoo aattttaaiinn tthhee rraatteedd ssppeeeedd..
PPRROOCCEEDDUURREE::
11.. OOppeenn tthhee tthhrreeee wwaayy ccoorrkk ssoo tthhaatt ffuueell fflloowwss ttoo tthhee eennggiinnee ddiirreeccttllyy ffrroomm tthhee ttaannkk..
22.. OOppeenn tthhee ccoooolliinngg wwaatteerr vvaallvveess aanndd eennssuurree wwaatteerr fflloowwss tthhrroouugghh tthhee eennggiinnee..
33.. SSttaarrtt tthhee eennggiinnee aanndd aallllooww rruunnnniinngg oonn nnoo llooaadd ccoonnddiittiioonn ffoorr ffeeww mmiinnuutteess..
44.. LLooaadd eennggiinnee bbyy aaddddiinngg wweeiigghhttss uuppoonn tthhee hhaannggeerr..
55.. AAllllooww tthhee ccoooolliinngg wwaatteerr iinn tthhee bbrraakkee ddrruumm aanndd aaddjjuusstt iitt ttoo aavvooiidd ssppiilllliinngg..
66.. AAllllooww tthhee eennggiinnee ttoo rruunn aatt tthhiiss llooaadd ffoorr ffeeww mmiinnuutteess..
77.. NNoottee tthhee ffoolllloowwiinngg rreeaaddiinnggss
aa)) EEnnggiinnee ssppeeeedd..
bb)) WWeeiigghhtt oonn tthhee hhaannggeerr..
cc)) SSpprriinngg bbaallaannccee
dd)) MMaannoommeetteerr
ee)) TTiimmee ffoorr 1100 cccc ooff ffuueell ccoonnssuummppttiioonn
88.. RReeppeeaatt tthhee aabboovvee pprroocceedduurree aatt ddiiffffeerreenntt llooaaddss..
99.. SSttoopp tthhee eennggiinnee aafftteerr rreemmoovviinngg llooaadd oonn tthhee eennggiinnee..
PPRREECCAAUUTTIIOONNSS::
11.. BBeeffoorree ssttaattiinngg tthhee eennggiinnee cchheecckk aallll tthhee ssyysstteemmss ssuucchh aass ccoooolliinngg,, lluubbrriiccaattiioonn aanndd ffuueell
ssyysstteemm
22.. EEnnssuurree ooiill lleevveell iiss mmaaiinnttaaiinneedd iinn tthhee eennggiinnee uupp ttoo rreeccoommmmeennddeedd lleevveell aallwwaayyss.. NNeevveerr
rruunn tthhee eennggiinnee wwiitthh iinnssuuffffiicciieenntt ooiill..
33.. NNeevveerr rruunn tthhee eennggiinnee wwiitthh iinnssuuffffiicciieenntt eennggiinnee ccoooolliinngg wwaatteerr aanndd eexxhhaauusstt ggaass
ccaalloorriimmeetteerr ccoooolliinngg wwaatteerr..
44.. FFoorr ssttooppppiinngg tthhee eennggiinnee,, llooaadd oonn tthhee eennggiinnee sshhoouulldd bbee rreemmoovveedd..
GRAPHS
11.. TT..FF..CC VVss BB ..PP 44.. II tthh VVss BB ..PP
22.. SS..FF..CC VVss BB ..PP 55.. mm VVss BB ..PP
33.. BBtthh VVss BB ..PP
OOBBSSEERRVVAATTIIOONNSS::
SS..NN
OO
LLooaadd
oonn
tthh
ee
bbrr aakk
ee dd
rr uu
mm
SSpp
ee ee dd
MMaann
oomm
ee tt ee
rr
rr ee aa
ddii nn
gg
AAii rr
hhee aadd
ccaauu
ss iinn
gg ff
ll ooww
(( HHaa))
mm oo
ff aaii rr
TTii mm
ee ff
oorr 11
00 cc
cc
ooff
ff uuee ll
TT.. FF
.. CC
HHee aatt
II nnpp
uutt
BB.. PP
FF.. PP
II ..PP
hh11 hh22 hh11~~hh22 WW11
kkgg SS
kkgg WW
kkgg
RRPP
MM
SSeecc kkgg//hhrr kkWW kkWW kkWW kkWW
11
22
33
44
55
66
SSAAMMPPLLEE CCAALLCCUULLAATTIIOONNSS::
11.. MMaannoommeetteerr RReeaaddiinngg hh11== mmmm
hh22 == mmmm
hh11~~hh22 ==hh== ……………………..mmmm ooff aaiirr
22.. AAiirr hheeaadd ccaauussiinngg ffllooww:: HHaa ==1000
h
air
water
== …….. mm ooff wwaatteerr
33.. EEnnggiinnee oouuttppuutt ((BBrraakkee PPoowweerr)) [[BB..PP]] == 100060
NT2
………… KKWW
WWhheerree,,
NN == RRaatteedd ssppeeeedd …….... RRppmm,,
WW11 == WWeeiigghhtt oonn hhaannggeerr ……………….. kkgg
SS == sspprriinngg bbaallaannccee rreeaaddiinngg ………………..kkgg
RRee == EEffffeeccttiivvee bbrraakkee ddrruumm rraaddiiuuss == ((RR ++ rr)) …… mm
WWhheerree RR iiss BBrraakkee ddrruumm rraaddiiuuss
rr iiss RRooppee rraaddiiuuss
WW == NNeett LLooaadd == ((WW11--SS)) 99..8811 ……………… NN
TT == TToorrqquuee == ((WW ** RRee))……………………NN--mm
TTiimmee ffoorr 1100cccc ooff ffuueell ccoonnssuummppttiioonn,, tt == ………….. SSeecc,,
S.NO
II..SS..FF..CC BB..SS..FF..CC
AAccttuuaall
vvoolluummee
ooff aaiirr VVaa MMaassss ooff aaiirr
TThheeoorreettiiccaall
vvoolluummee ooff aaiirr
VVtthh EEffffiicciieenncciieess
kkgg//kkww--hh kkgg//kkww--hh mm33//ss kkgg//ss
mm33//ss vv BB tthh II tthh mm
11
22
33
44
55
66
MMaassss ooff ffuueell ccoonnssuummppttiioonn ppeerr sseecc,, mmff == 1000
.10 dieselofGravitySp
t kkgg//sseecc
44.. TToottaall FFuueell ccoonnssuummppttiioonn,, TTFFCC == …… mmff 33660000……..kkgg // hhrr..
55.. HHeeaatt IInnppuutt,, HHII == 6060
CVTFC …………..KKWW
WWhheerree CCVV iiss ccaalloorriiffiicc vvaalluuee ooff DDiieesseell == 4433440000 KKJJ // kkgg
66.. FF.. PP == FFrriiccttiioonnaall PPoowweerr ffrroomm WWiilllliiaamm’’ss lliinnee ddiiaaggrraamm..
((TTFFCC VVss BB..PP))
77.. IInnddiiccaatteedd PPoowweerr,, II..PP == BB..PP ++ FF..PP
88.. BBrraakkee ssppeecciiffiicc ffuueell ccoonnssuummppttiioonn,, BBSSFFCC == PB
CFT
.
..…………....KKgg //KKww--hhrr
99.. IInnddiiccaatteedd ssppeecciiffiicc ffuueell ccoonnssuummppttiioonn,, IISSFFCC ==PI
CFT
.
..…………KKgg //KKww--hhrr
1100.. AAccttuuaall vvoolluummee ooff aaiirr iinnttaakkee==VVaa== CCdd AA00 aHg 2 == …….. mm33
WWhheerree CCdd== 00..6622
AA00== 33..1144 XX 1100--44 mm22
1111.. MMaassss ooff aaiirr iinnttaakkee mmaa == air VVaa …….. KKgg..
1122.. TThheeoorreettiiccaall vvoolluummee ooff aaiirr == VVtthh == 602
N Ls D4
2
mm33//SSeecc
1133.. VVoolluummeettrriicc eeffffiicciieennccyy == 100Vth
Va %%
1144.. BBrraakkee tthheerrmmaall eeffffiicciieennccyy,, BB tthh == 100.
.
IH
PB
1155.. IInnddiiccaatteedd tthheerrmmaall eeffffiicciieennccyy,, II tthh == 100.
HI
PI
1166..
1177.. MMeecchhaanniiccaall eeffffiicciieennccyy,, mm == 100.
.
PI
PB
MMOODDEELL GGRRAAPPHHSS::
BB..PP ,, KKWW
SSFF
CC
KKgg
// KKWW
-- hhrr
BB
tthh,, %%
RESULT:-
BB..PP,, KKWW
mm
eecchh ,,%%
BB..PP,, KKWW
ii tthh,, %%
BB..PP,, KKWW
BB..PP,, KKWW FF.. PP,, KKWW
TTFF
CC,,
KKgg
// hh
rr
HEAT BALANCE SHEET PREPARATION ON 4-
STROKE, SINGLE CYLINDER DIESEL ENGINE
TEST RIG
HEAT BALANCE SHEET PREPARATION ON 4-STROKE, SINGLE CYLINDER
DDIIEESSEELL EENNGGIINNEE TTEESSTT RRIIGG
AAIIMM:: TToo ccoonndduucctt aa HHeeaatt BBaallaannccee TTeesstt oonn aa 44-- ssttrrookkee ssiinnggllee ccyylliinnddeerr vveerrttiiccaall ddiieesseell eennggiinnee
aatt ddiiffffeerreenntt llooaaddss aanndd ttoo ddrraaww uupp aa hheeaatt bbaallaannccee sshheeeett oonn mmiinnuuttee bbaassiiss..
EEQQUUIIPPMMEENNTT // AAPPPPAARRAATTUUSS::
11.. 44--SSttrrookkee SSiinnggllee ccyylliinnddeerr DDiieesseell eennggiinnee wwiitthh aa rrooppee bbrraakkee ddyynnaammoommeetteerr..
22.. TTaacchhoommeetteerr ((00--22000000 rrppmm..))
33.. SSttooppwwaattcchh..
SSPPEECCIIFFIICCAATTIIOONNSS
MMaakkee :: KKiirrlloosskkaarr mmooddeell AAVVII
BBoorree :: 8800 mmmm
SSttrrookkee :: 111100 mmmm
RRaatteedd SSppeeeedd :: 11550000 rrppmm
MMaaxx.. BB..PP :: 33..77 KKWW
CCoommpprreessssiioonn RRaattiioo :: 1166 ..55::11
OOrriiffiiccee ddiiaammeetteerr :: 2200 mmmm
FFuueell :: DDiieesseell
SSppeecciiffiicc ggrraavviittyy ooff DDiieesseell :: 00..882277
CCaalloorriiffiicc VVaalluuee ooff DDiieesseell :: 4433440000 KKJJ // kkgg
BBrraakkee ddrruumm ddiiaammeetteerr :: 336600 mmmm
RRooppee ddiiaammeetteerr :: 1155 mmmm
EEqquuiivvaalleenntt ddiiaammeetteerr :: 337755 mmmm
DDEESSCCRRIIPPTTIIOONN::
TThhiiss iiss aa wwaatteerr ccoooolleedd ffoouurr ssttrrookkee ssiinnggllee ccyylliinnddeerr vveerrttiiccaall ddiieesseell eennggiinnee iiss ccoouupplleedd ttoo
aa rrooppee ppuulllleeyy bbrraakkee aarrrraannggeemmeenntt ttoo aabbssoorrbb tthhee ppoowweerr pprroodduucceedd,, NNeecceessssaarryy wweeiigghhttss aanndd
sspprriinngg bbaallaanncceess aarree iinncclluuddeedd ttoo aappppllyy llooaadd oonn tthhee bbrraakkee ddrruumm.. SSuuiittaabbllee ccoooolliinngg wwaatteerr
aarrrraannggeemmeenntt ffoorr tthhee bbrraakkee ddrruumm iiss pprroovviiddeedd.. SSeeppaarraattee ccoooolliinngg wwaatteerr lliinneess aarree pprroovviiddeedd ffoorr
tthhee eennggiinnee ccoooolliinngg.. TThheerrmmooccoouupplleess aarree pprroovviiddeedd ffoorr mmeeaassuurriinngg tteemmppeerraattuurree.. AA ffuueell
mmeeaassuurriinngg ssyysstteemm ccoonnssiissttss ooff aa ffuueell ttaannkk mmoouunntteedd oonn aa ssttaanndd,, bbuurreettttee,, aanndd aa 33--wwaayy ccoorrkk..
AAiirr ccoonnssuummppttiioonn iiss mmeeaassuurreedd bbyy uussiinngg aa MM..SS.. ttaannkk,, wwhhiicchh iiss ffiitttteedd wwiitthh aa ssttaannddaarrdd oorriiffiiccee
aanndd aa UU--ttuubbee wwaatteerr mmaannoommeetteerr tthhaatt mmeeaassuurreess tthhee pprreessssuurreess iinnssiiddee tthhee ttaannkk..
TTeesstt RRiigg iiss pprroovviiddeedd wwiitthh eexxhhaauusstt ggaass ccaalloorriimmeetteerr.. TThhee eexxhhaauusstt ggaass ppiippee iiss
ccoonnnneecctteedd ttoo aa hheeaatt eexxcchhaannggeerr wwhheerreeiinn,,tthhee ggaasseess aarree ccoooolleedd bbyy aa ccoooolliinngg wwaatteerr lliinnee..
TThheerrmmooccoouupplleess aarree pprroovviiddeedd ttoo mmeeaassuurree tthhee iinnlleett aanndd oouuttlleett tteemmppeerraattuurreess ooff eexxhhaauusstt ggaass
aass wweellll aass ccoooolliinngg wwaatteerr ffoorr tthhee ccaalloorriimmeetteerr..
TTHHEEOORRYY::
PPaarrtt ooff tthhee hheeaatt ssuupppplliieedd ttoo aann II..CC.. eennggiinnee tthhrroouugghh tthhee ffuueell iiss uuttiilliizzeedd iinn ddooiinngg uusseeffuull
wwoorrkk,, aanndd tthhee rreesstt iiss wwaasstteedd iinn oovveerrccoommiinngg ffrriiccttiioonn,, iinn eexxhhaauusstt ggaasseess aanndd iinn eennggiinnee ccoooolliinngg
wwaatteerr.. AA ssttaatteemmeenntt ooff tthhee ssuupppplliieedd hheeaatt,, uusseeffuull wwoorrkk aanndd hheeaatt wwaasstteedd iinn oovveerrccoommiinngg
ffrriiccttiioonn,, eexxhhaauusstt ggaasseess,, eennggiinnee ccoooolliinngg iiss ccaalllleedd hheeaatt bbaallaannccee sshheeeett.. IItt mmaayy bbee ddrraawwnn oonn
tthhee bbaassiiss ooff uunniitt ttiimmee oorr ccyyccllee ooff ooppeerraattiioonn..
TThhee hheeaatt bbaallaannccee tthhuuss ggiivveess aa ppiiccttuurree aabboouutt tthhee uuttiilliittyy ooff hheeaatt ssuupppplliieedd tthhrroouugghh tthhee ffuueell..
TThhee lloosssseess ddeeppeennddss uupp oonn ttyyppee ooff tthhee eennggiinnee,, sseerrvviiccee ttoo wwhhiicchh iitt iiss eemmppllooyyeedd,, llooaadd,,
aattmmoosspphheerriicc ccoonnddiittiioonnss eettcc.. AA ddeessiiggnneerr iiss iinntteerreesstteedd ttoo kkeeeepp tthhee lloosssseess aass llooww aass ppoossssiibbllee
iinn oorrddeerr ttoo mmaaxxiimmiizzee tthhee rraatteedd ppoowweerr.. TTwwoo iimmppoorrttaanntt ffaaccttoorrss tthhaatt iinnfflluueennccee tthhee lloosssseess aarree
ssppeeeedd aanndd oouuttppuutt ooff aann eennggiinnee.. TThhee lloossss dduuee ttoo ffrriiccttiioonn iinnccrreeaasseess ccoonnssiiddeerraabbllyy mmoorree dduuee ttoo
iinnccrreeaassee iinn eennggiinnee ssppeeeedd tthhaann bbyy aann iinnccrreeaassee iinn llooaadd.. HHeeaatt ccaarrrriieedd aawwaayy bbyy eennggiinnee wwaatteerr
iinnccrreeaasseess sslloowwllyy wwiitthh llooaadd wwhhiillee hheeaatt ccaarrrriieedd aawwaayy bbyy eexxhhaauusstt ggaasseess iinnccrreeaasseess aabbrruuppttllyy
bbeeyyoonndd 8800%% ooff tthhee rraatteedd ppoowweerr oouuttppuutt dduuee ttoo hhiigghheerr ccoommbbuussttiioonn tteemmppeerraattuurreess,, iinneeffffiicciieenntt
ccoommbbuussttiioonn eettcc.
SSTTAARRTTIINNGG TTHHEE EENNGGIINNEE::
11.. EEnnggaaggee ddee--ccoommpprreessssiioonn lleevveerr bbeeffoorree ccrraannkkiinngg..
22.. CCrraannkk tthhee eennggiinnee aanndd ddiisseennggaaggee tthhee ddee--ccoommpprreessssiioonn lleevveerr..
33.. AAddjjuusstt tthhee ggoovveerrnnoorr ttoo aattttaaiinn tthhee rraatteedd ssppeeeedd..
PPRROOCCEEDDUURREE::
11.. OOppeenn tthhee tthhrreeee wwaayy ccoorrkk ssoo tthhaatt ffuueell fflloowwss ttoo tthhee eennggiinnee ddiirreeccttllyy ffrroomm tthhee ttaannkk..
22.. OOppeenn tthhee ccoooolliinngg wwaatteerr vvaallvveess aanndd eennssuurree wwaatteerr fflloowwss tthhrroouugghh tthhee eennggiinnee..
33.. SSttaarrtt tthhee eennggiinnee aanndd aallllooww rruunnnniinngg oonn nnoo llooaadd ccoonnddiittiioonn ffoorr ffeeww mmiinnuutteess..
44.. LLooaadd eennggiinnee bbyy aaddddiinngg wweeiigghhttss uuppoonn tthhee hhaannggeerr..
55.. AAllllooww tthhee ccoooolliinngg wwaatteerr iinn tthhee bbrraakkee ddrruumm aanndd aaddjjuusstt iitt ttoo aavvooiidd ssppiilllliinngg..
66.. AAllllooww tthhee eennggiinnee ttoo rruunn aatt tthhiiss llooaadd ffoorr ffeeww mmiinnuutteess..
77.. AAddjjuusstt tthhee ccoooolliinngg wwaatteerr rreegguullaattoorrss ssuucchh tthhaatt tthhee tteemmppeerraattuurree rraaiissee ooff CCoooolliinngg wwaatteerr
ffoorr eennggiinnee jjaacckkeett iiss aarroouunndd 5500CC aanndd ffoorr ccaalloorriimmeetteerr aarroouunndd 225500CC..
88.. NNoottee tthhee ffoolllloowwiinngg rreeaaddiinnggss
aa)) EEnnggiinnee SSppeeeedd
bb)) WWeeiigghhtt oonn tthhee hhaannggeerr
cc)) SSpprriinngg bbaallaannccee
dd)) MMaannoommeetteerr
ee)) TTiimmee ffoorr 1100cccc ooff ffuueell ccoonnssuummppttiioonn
ff)) FFllooww ooff CCoooolliinngg wwaatteerr tthhrroouugghh CCaalloorriimmeetteerr..
gg)) FFllooww ooff CCoooolliinngg wwaatteerr tthhrroouugghh EEnnggiinnee..
hh)) IInnlleett aanndd oouuttlleett tteemmppeerraattuurreess ooff eennggiinnee ccoooolliinngg wwaatteerr
ii)) IInnlleett aanndd oouuttlleett tteemmppeerraattuurreess ooff ccaalloorriimmeetteerr ccoooolliinngg wwaatteerr
jj)) IInnlleett aanndd oouuttlleett tteemmppeerraattuurreess ooff eexxhhaauusstt ggaasseess
kk)) AAmmbbiieenntt tteemmppeerraattee
99.. RReeppeeaatt tthhee aabboovvee pprroocceedduurree ffoorr ddiiffffeerreenntt llooaaddss..
1100.. SSttoopp tthhee eennggiinnee aafftteerr rreemmoovviinngg llooaadd oonn tthhee eennggiinnee..
OOBBSSEERRVVAATTIIOONNSS::
PPRREECCAAUUTTIIOONNSS::
11.. BBeeffoorree ssttaattiinngg tthhee eennggiinnee cchheecckk aallll tthhee ssyysstteemmss ssuucchh aass ccoooolliinngg ,, lluubbrriiccaattiioonn aanndd ffuueell
ssyysstteemm
22.. EEnnssuurree ooiill lleevveell iiss mmaaiinnttaaiinneedd iinn tthhee eennggiinnee uuppttoo rreeccoommmmeennddeedd lleevveell aallwwaayyss.. NNeevveerr
rruunn tthhee eennggiinnee wwiitthh iinnssuuffffiicciieenntt ooiill..
33.. NNeevveerr rruunn tthhee eennggiinnee wwiitthh iinnssuuffffiicciieenntt eennggiinnee ccoooolliinngg wwaatteerr aanndd eexxhhaauusstt ggaass
ccaalloorriimmeetteerr ccoooolliinngg wwaatteerr..
44.. BBeeffoorree ssttooppppiinngg tthhee eennggiinnee,, llooaadd oonn tthhee eennggiinnee sshhoouulldd bbee rreemmoovveedd..
SS..
NN
OO
LLooaadd oonn tthhee
bbrraakkee ddrruumm
SSpp
eeeedd
MMaannoommeetteerr
rreeaaddiinngg
AAii rr
hheeaadd
ccaauu
ssii nn
gg ff
ll ooww
(( HHaa))
mm oo
ff aaii rr
TTiimmee
ffoorr
1100
cccc ooff
ffuueell
EEnnggiinnee
ccoooolliinngg
wwaatteerr
tteemmppeerraattuurree
CCaalloorriimmeetteerr
wwaatteerr
tteemmppeerraattuurree
CCaalloorriimmeetteerr
eexxhhaauusstt
ggaasseess
tteemmppeerraattuurree
AAmmbb
iieenntt
TTeemm
ppeerraa
ttuurree
TT66OOCC II//PP OO//PP II//PP OO//PP II//PP OO//PP
WW11
kkgg SS
kkgg WW
kkgg RRPP
MM
hh11 hh22 hh11--hh22 SSeecc TT11OOCC TT22
OOCC TT11
00
CC TT33
OOCC TT44OOCC TT55
OOCC TT66OOCC
11
22
33
44
55
66
CCAALLCCUULLAATTIIOONNSS::
11.. EEnnggiinnee oouuttppuutt ((BBrraakkee PPoowweerr)) [[BB..PP]] == 100060
NT2
………… kkWW
WWhheerree,,
NN == RRaatteedd ssppeeeedd …….... RRppmm,,
WW00 == WWeeiigghhtt ooff hhaannggeerr
WW11 == WWeeiigghhtt oonn hhaannggeerr ……………….. kkgg
WW22 == sspprriinngg bbaallaannccee rreeaaddiinngg ………………..kkgg
RRee == EEffffeeccttiivvee bbrraakkee ddrruumm rraaddiiuuss == ((RR++rr)) …… mm
WWhheerree RR iiss BBrraakkee ddrruumm rraaddiiuuss
rr iiss RRooppee rraaddiiuuss
WW == NNeett LLooaadd == [[((WW11--WW22))++ WW00]] 99..8811 ……………… NN
TT == ((WW ** RRee))……………………NN--mm
22.. MMaassss ooff ffuueell ccoonnssuummppttiioonn ppeerr mmiinn,, mmff == 601000
.10X
dieselofGravitySp
t kkgg// mmiinn..
tt == TTiimmee ffoorr 1100cccc ooff ffuueell ccoonnssuummppttiioonn…………SSeecc
33.. HHeeaatt IInnppuutt,, HH//II == mmff xx CCvv ………….. kkJJ// mmiinn
CCVV iiss ccaalloorriiffiicc vvaalluuee ooff ggiivveenn ffuueell == 4433440000 KKJJ // kkgg
44.. AAccttuuaall AAiirr iinnttaakkee::
MMaannoommeetteerr rreeaaddiinngg hh11 == ……………………....mmmm ooff wwaatteerr
MMaannoommeetteerr rreeaaddiinngg hh22 == ……………………....mmmm ooff wwaatteerr
DDiiffffeerreennccee iinn wwaatteerr lleevveell,, hhww == 1000
21hh
………………..mm ooff wwaatteerr
EEqquuiivvaalleenntt aaiirr ccoolluummnn,, hhaa ==airofDensity
waterofDensityhw ==
16.1
1000wh ......mm.. ooff aaiirr
OOrriiffiiccee ddiiaammeetteerr,, dd == 00..0022 mm
AArreeaa ooff oorriiffiiccee,, aa == 4
)02.0( 2…………....mm22
55.. AAccttuuaall VVoolluummee ooff aaiirr iinnttaakkee,, VVaa == CCdd aa agh2 ………… mm33 // sseecc..
CCooeeffffiicciieenntt ooff DDiisscchhaarrggee,, CCdd == 00..6622
66.. MMaassss ooff aaiirr iinnttaakkee,, mmaa == a VVaa 6600…………kkgg // mmiinn
DDeennssiittyy ooff aaiirr a == 11..1166 KKgg//mm33
77.. TToottaall mmaassss ooff EExxhhaauusstt GGaass,, mmgg == mmaa ++ mmff …….. kkgg//mmiinn
TThhee ssppeecciiffiicc hheeaatt ooff eexxhhaauusstt ggaass iiss ddeetteerrmmiinneedd bbyy eeqquuaattiinngg
HHeeaatt lloosstt bbyy eexxhhaauusstt ggaass == HHeeaatt ccaarrrriieedd bbyy ccaalloorriimmeetteerr ccoooolliinngg wwaatteerr
88.. HHeeaatt lloosstt bbyy eexxhhaauusstt ggaass iinn ccaalloorriimmeetteerr
HHeegg == mmgg CCppgg ((TT44 –– TT55))…….... kkJJ//mmiinn
99.. HHeeaatt ggaaiinneedd bbyy ccaalloorriimmeetteerr ccoooolliinngg wwaatteerr
HHccww== mmccww CCppww ((TT33-- TT11)) kkJJ//mmiinn
1100.. HHeeaatt iinnppuutt,, HHII == mmff CCVV………… kkJJ//mmiinn
1111.. HHeeaatt EEqquuiivvaalleenntt ooff BB..PP,, HHBB..PP == BB..PP 6600 ……………….... kkJJ//mmiinn
1122.. HHeeaatt lloosstt bbyy eexxhhaauusstt ggaass,, HHeegg == mmgg CCppgg ((TT44 -- TT66)) …….... kkJJ//mmiinn
1133.. HHeeaatt CCaarrrriieedd bbyy eennggiinnee CCoooolliinngg wwaatteerr HHeeww == mmww CCppww ((TT22 –– TT11))…… kkJJ//mmiinn
1144.. HHeeaatt uunnaaccccoouunntteedd lloossss ,,HHuu == HHII –– ((HHBBPP ++ HHeeww ++ HHeegg)) ………… kkJJ//mmiinn
HHEEAATT BBAALLAANNCCEE SSHHEEEETT OONN MMIINNUUTTEE BBAASSIISS::
HHeeaatt
SSuupppplliieedd kkJJ//mmiinn %% Heat distributed kkJJ// mmiinn %%
HHeeaatt
ssuupppplliieedd bbyy
tthhee ffuueell
AA== 110000
HHeeaatt iinn BB..PP B= B/ AA==
HHeeaatt ccaarrrriieedd bbyy eennggiinnee CCoooolliinngg
wwaatteerr
C= C/ AA==
HHeeaatt CCaarrrriieedd bbyy eexxhhaauusstt ggaasseess D= D/ AA==
UUnnaaccccoouunntteedd lloosssseess
((rraaddiiaattiioonn,, ffrriiccttiioonn,, eettcc..,,))
E= E/ AA==
TToottaall AA== 110000 AA== 110000
RREESSUULLTT::--
RREETTAADDAATTIIOONN TTEESSTT OONN 44--SSTTRROOKKEE,, SSIINNGGLLEE
CCYYLLIINNDDEERR DDIIEESSEELL EENNGGIINNEE TTEESSTT RRIIGG
RREETTAARRDDAATTIIOONN TTEESSTT OONN 44--SSTTRROOKKEE,, SSIINNGGLLEE CCYYLLIINNDDEERR DDIIEESSEELL EENNGGIINNEE TTEESSTT RRIIGG
AAIIMM::
TToo ccoonndduucctt rreettaarrddaattiioonn tteesstt oonn 44--ssttrrookkee,, ssiinnggllee ccyylliinnddeerr ddiieesseell eennggiinnee,, ttoo ccaallccuullaattee
ffrriiccttiioonnaall ppoowweerr ddeevveellooppeedd bbyy tthhee eennggiinnee
EEQQUUIIPPMMEENNTT//AAPPPPAARRAATTUUSS::
11.. 44-- SSttrrookkee,, ssiinnggllee ccyylliinnddeerr DDiieesseell eennggiinnee wwiitthh rrooppee bbrraakkee ddrruumm ddyynnaammoommeetteerr..
22.. SSttooppwwaattcchh..
SSPPEECCIIFFIICCAATTIIOONNSS::
MMaakkee :: KKiirrlloosskkaarr AAVV
BBoorree :: 8800mmmm
SSttrrookkee :: 111100 mmmm
RRaatteedd SSppeeeedd :: 11550000 rrppmm
MMaaxx.. BB..PP :: 33..77KKWW ((55 HH..PP))
CCoommpprreessssiioonn RRaattiioo :: 1166 ..55::11
OOrriiffiiccee DDiiaammeetteerr :: 2200 mmmm
FFuueell OOiill :: DDiieesseell
SSppeecciiffiicc ggrraavviittyy ooff DDiieesseell :: 00..882277
CCaalloorriiffiicc VVaalluuee ooff DDiieesseell :: 4433440000 KKJJ // kkgg
TTHHEEOORRYY::
TThhee ffrriiccttiioonnaall ppoowweerr ooff aann II..CC.. eennggiinnee iiss ddeetteerrmmiinneedd bbyy tthhee ffoolllloowwiinngg mmeetthhooddss
aa)) WWiilllliiaann’’ss lliinnee mmeetthhoodd
bb)) IInnddiiccaattoorr aarreeaa mmeetthhoodd
cc)) RReettaarrddaattiioonn tteesstt
dd)) MMoottoorriinngg tteesstt
ee)) MMoorrssee tteesstt..
RREETTAARRDDAATTIIOONN TTEESSTT::
TThhiiss tteesstt iinnvvoollvveess tthhee mmeetthhoodd ooff rreettaarrddiinngg tthhee eennggiinnee bbyy ccuuttttiinngg tthhee ffuueell
ssuuppppllyy.. WWhheenn tthhee eennggiinnee iiss ssttooppppeedd ssuuddddeennllyy iittss rreettaarrddaattiioonn iinn ssppeeeedd iiss ddiirreeccttllyy rreellaatteedd ttoo
tthhee ffrriiccttiioonnaall rreessiissttaannccee iinnssiiddee tthhee eennggiinnee.. TThhee eennggiinnee iiss mmaaddee ttoo rruunn aatt nnoo llooaadd aanndd rraatteedd
ssppeeeedd ..wwhheenn tthhee eennggiinnee iiss rruunnnniinngg uunnddeerr sstteeaaddyy ooppeerraattiinngg ccoonnddiittiioonnss tthhee ssuuppppllyy ooff ffuueell iiss
ccuutt ooffff aanndd ssiimmuullttaanneeoouussllyy tthhee ttiimmee ooff ffaallll iinn ssppeeeeddss bbyy ssaayy 2200%% ,, 4400%%,, 6600%% ,, 8800%% ooff tthhee
rraatteedd ssppeeeedd iiss rreeccoorrddeedd.. TThhee tteessttss aarree rreeppeeaatteedd oonnccee aaggaaiinn wwiitthh 5500%% llooaadd oonn tthhee eennggiinnee.. AA
ggrraapphh ccoonnnneeccttiinngg ttiimmee ffoorr ffaallll iinn ssppeeeedd ((xx-- aaxxiiss )) aanndd ssppeeeedd ((yy –– aaxxiiss )) aatt nnoo llooaadd aass wweellll aass
5500 %% llooaadd ccoonnddiittiioonnss iiss ddrraawwnn aass sshhoowwnn iinn ffiigg..
110000rrppmm
SSppeeeedd
tt33 tt22
TTiimmee
GGrraapphh ffoorr rreettaarrddaattiioonn TTeesstt
IInn tthhiiss sseett uupp ttoo ssttoopp tthhee eennggiinnee rruunnnniinngg ffrroomm ssuuppppllyy ooff ffuueell aa vvaallvvee iiss pprroovviiddeedd.. AAss
tthhee eennggiinnee hhaass rruunn ffoorr ssuuffffiicciieenntt ttiimmee,, tthhee vvaallvvee iiss ccuuttooffff aanndd aatt tthhee ssaammee ttiimmee ddiiggiittaall ttiimmeerr iiss
sswwiittcchheedd oonn.. TTiimmee ffoorr rreedduuccttiioonn iinn ssppeeeedd ttiillll aa ppaarrttiiccuullaarr ssppeeeedd iiss nnootteedd..
PPRROOCCEEDDUURREE::
11.. CChheecckk tthhee ffuueell aanndd lluubbrriiccaattiinngg ooiill lleevveellss..
22.. SSuuppppllyy tthhee ffuueell ttoo tthhee eennggiinnee..
33.. OOppeenn tthhee ccuutt ooffff vvaallvvee ttoo eenntteerr tthhee ffuueell iinnttoo tthhee eennggiinnee
44.. NNooww ssttaarrtt tthhee eennggiinnee..
55.. CCoonnnneecctt tthhee wwaatteerr ssuuppppllyy ttoo tthhee eennggiinnee ffoorr ccoooolliinngg
66.. AAfftteerr iinniittiiaall wwoorrmm uupp tthhee eennggiinnee,, ccuutt ooff tthhee ffuueell ssuuppppllyy uussiinngg ((ccuutt ooffff vvaallvvee)) aatt nnoo llooaadd..
77.. TThhee ssuuppppllyy ooff ffuueell iiss ccuutt ooffff aanndd ssiimmuullttaanneeoouussllyy tthhee ttiimmee ooff ffaallll iinn ssppeeeeddss bbyy ssaayy 2200%%
,, 4400%%,, 6600%% ,, 8800%% ooff tthhee rraatteedd ssppeeeedd iiss rreeccoorrddeedd bbyy uussiinngg ddiiggiittaall ttiimmeerr aanndd ddiiggiittaall
RRPPMM iinnddiiccaattoorr..
88.. TThhee aabboovvee pprroocceedduurree iiss ffoolllloowweedd ffoorr 5500%% llooaadd ((ii..ee 77KKgg))..
BBeeffoorree SSTTAARRTTIINNGG TTHHEE EENNGGIINNEE::
11.. CChheecckk tthhee DDiieesseell LLeevveell iinn tthhee ddiieesseell ttaannkk..
22.. CChheecckk tthhee WWaatteerr ffllooww tthhrroouugghh EEnnggiinnee ccyylliinnddeerr..
33.. FFiirrsstt,, sswwiittcchh --OONN tthhee MMCCBB (( MMaaiinnss )) ooff tthhee ccoonnttrrooll ppaanneell aatt tthhee rriigghhtt bboottttoomm
ssiiddee ..
44.. EEnnssuurree tthhaatt wwaatteerr iiss fflloowwiinngg tthhrroouugghh tthhee eennggiinnee..
OOBBSSEERRVVAATTIIOONNSS
LLeett,,
tt22 aanndd tt33 bbee tthhee ttiimmee ooff ffaallll aatt nnoo llooaadd aanndd 5500%% llooaaddss
ωω == AAnngguullaarr vveelloocciittyy iinn rraadd//sseecc
α =dt
dw= Angular acceleration in rad/sec2
SS.. NNoo DDrroopp iinn ssppeeeedd TTiimmee ffoorr ffaallll ooff
ssppeeeedd aatt nnoo llooaadd,,
SSeecc
TTiimmee ffoorr ffaallll ooff
ssppeeeedd aatt 77KKgg llooaadd,,
SSeecc
11..
22..
33..
44..
55..
Torque, T= Moment of inertia ×Angular acceleration
TT==II××dt
dw
Moment of inertia of rotating parts is constant throughout the test
T=mk2 ×dt
dw (I = mk2 )
dw= dtI
T (eq1)
Now integrating the equation 1 between the limits ω1 aanndd ωω22
2
1
w
wdw= dt
I
Tt
t
2
1
2
1
w
ww == 12 ttI
T
Let, TF be the frictional torque and TL be the load torque . At no load condition both frictional and load torques will act. Hence at no load condition
ω2 – ω1= 02 tI
TF (eq 2)
Where TF = frictional torque Similarly for load condition
ω2 – ω1= 03 tI
TL (eq 3)
where TL = load torque
tt33 ((TTff++TTLL)) == ((ωω22 –– ωω11))mmkk22
tt33 ((TTff++TTLL)) == TTff××tt22 ((ffrroomm eeqq 22))
3
2
t
t=
I
TT LF
3
2
t
t = 1+
F
L
T
T
F
L
T
T =
3
32
t
tt
TF = TL×32
3
tt
t
PPRREECCAAUUTTIIOONNSS::
11.. DDoonn’’tt ssttaarrtt oorr ssttoopp tthhee eennggiinnee wwiitthh llooaadd..
22.. DDoonn’’tt ffoorrggeett ssuuppppllyy ooff ccoooolliinngg wwaatteerr ttoo tthhee eennggiinnee..
33.. AAfftteerr ssttaarrttiinngg tthhee eennggiinnee rreemmoovvee tthhee hhaannddllee ccaarreeffuullllyy ffrroomm tthhee sshhaafftt..
44.. TTaakkee tthhee ttiimmee ccaarreeffuullllyy ffoorr ddrrooppppiinngg ooff tthhee ssppeeeedd
SSAAMMPPLLEE CCAALLCCUULLAATTIIOONNSS::
LLooaadd TToorrqquuee oonn ddrruumm ((TTLL)) == 81.9rM NN mm
MM-- MMaassss iinn KKgg ooff sspprriinngg BBaallaannccee
rr -- RRaaddiiuuss ooff ttoorrqquuee aarrmm == 2
015.036.0 mm
FFrriiccttiioonnaall llooaadd TToorrqquuee (( FT )) == LTtt
t
32
3
tt22
== RReettaarrddaattiioonn ttiimmee aatt nnoo llooaadd
tt33 == RReettaarrddaattiioonn ttiimmee aatt 5500%% llooaadd
FFrriiccttiioonnaall ppoowweerr ((FF..PP)) == 60
2 FTN WW
BBrraakkee ppoowweerr BB..PP == 60
2 TN WW
MMeecchhaanniiccaall EEffffiicciieennccyy == 100.
.
PI
PB
RREESSUULLTT::--
MMOORRSSEE TTEESSTT OONN 44--SSTTRROOKKEE,, 44-- CCYYLLIINNDDEERR
PPEETTRROOLL EENNGGIINNEE TTEESSTT RRIIGG
MORSE TEST ON 4-STROKE, 4-CYLINDER PETROL ENGINE AIM: To conduct Morse test on a 4-stroke multi cylinder (4 – cylinder) petrol engine to
establish friction power & mechanical efficiency
EQUIPMENT REQUIRED:
1. 4-stroke,4 -cylinder petrol engine with a hydraulic dynamometer with provision to cut
off ignition to each cylinder independently.
2. Tachometer (0-2000 rpm).
3. Stop watch
SSPPEECCIIFFIICCAATTIIOONNSS::
MMaakkee :: PPrreemmiieerr
NNoo ooff ccyylliinnddeerrss :: 44
BBoorree :: 6688 mmmm
SSttrrookkee :: 7755 mmmm
RRaatteedd SSppeeeedd :: 11550000 rrppmm
BB..PP :: 77..3355 KKww ((1100 HHpp))
FFuueell :: PPeettrrooll
SSppeecciiffiicc GGrraavviittyy ooff ppeettrrooll :: 00..771166
CCaalloorriiffiicc vvaalluuee ooff ppeettrrooll :: 4477110000 KKJJ//kkgg
CCoommpprreessssiioonn RRaattiioo :: 77..88::11
OOrriiffiiccee ddiiaammeetteerr :: 2200 mmmm
DDEESSCCRRIIPPTTIIOONN::
TThhee tteesstt rriigg ccoonnssiissttss ooff aa mmuullttii ccyylliinnddeerr ppeettrrooll eennggiinnee ccoouupplleedd ttoo aa hhyyddrraauulliicc
ddyynnaammoommeetteerr.. TThhee eennggiinnee iiss 44--ccyylliinnddeerr,, 44--ssttrrookkee vveerrttiiccaall eennggiinnee ddeevveellooppiinngg 77..3355KKww aatt
11550000 rrppmm.. TThhiiss ttyyppee ooff eennggiinnee iiss bbeesstt ssuuiitteedd ffoorr aauuttoommoobbiilleess wwhhiicchh ooppeerraattee aatt vvaarryyiinngg
ssppeeeedd.. TThhee eennggiinnee iiss ffiitttteedd oonn aa rriiggiidd bbeedd aanndd iiss ccoouupplleedd tthhrroouugghh aa fflleexxiibbllee ccoouupplliinngg ttoo aa
hhyyddrraauulliicc ddyynnaammoommeetteerr tthhaatt aaccttss aass tthhee llooaaddiinngg ddeevviiccee.. AAllll tthhee iinnssttrruummeennttss aarree mmoouunntteedd oonn
aa ssuuiittaabbllee ppaanneell bbooaarrdd.. FFuueell ccoonnssuummppttiioonn iiss mmeeaassuurreedd wwiitthh aa bbuurreettttee aanndd aa 33--wwaayy ccoorrkk
wwhhiicchh rreegguullaatteess tthhee ffllooww ooff ffuueell ffrroomm tthhee ttaannkk ttoo tthhee eennggiinnee..
AAiirr ccoonnssuummppttiioonn iiss mmeeaassuurreedd bbyy uussiinngg aa MM..SS.. ttaannkk,, wwhhiicchh iiss ffiitttteedd wwiitthh aa ssttaannddaarrdd
oorriiffiiccee aanndd aa UU--ttuubbee wwaatteerr mmaannoommeetteerr tthhaatt mmeeaassuurreess tthhee pprreessssuurreess iinnssiiddee tthhee ttaannkk..
TToo ccoonndduucctt MMoorrssee tteesstt,, aann aarrrraannggeemmeenntt iiss pprroovviiddeedd ttoo ccuutt ooffff tthhee iiggnniittiioonn ttoo eeaacchh
ssppaarrkk pplluugg..
THEORY:
The frictional power of an I.C. engine is determined by the following methods:
f) William’s line method
g) Indicator area method
h) Motoring test
i) Morse test
The Morse test is applicable for multi cylinder petrol (or) diesel engine. The engine
is run at the rated speed and the output is measured. Then one cylinder is made not to fire
by Cut-off ignition, under this condition, the other cylinder operates the engine. As a
consequence the speed of the engine falls. The output is measured by restoring the speed
to the original value by decreasing the load. The difference between two outputs gives the
indicated power of the cylinder cutout.
Thus the indicated power of all cylinders can be evaluated and by deducting brake
power from the indicated power of all cylinders, the frictional power of the engine can be
estimated.
Let I.P of cylinders 1, 2, 3 & 4, be I.P1, I.P2, I.P3&I.P4 respectively. Let Frictional
power of the engine be ‘F.P’ at a given load. Thus for a four cylinder engine.
I.P1+I.P2+I.P3+I.P4 – F.P = B .P ………. (1)
Where B.P= Brake Power of engine when all cylinders are working.
When first cylinder is cut out I1 = 0, but Friction power of the engine remains at F.P
Then I.P2 + I.P3 + I.P4 - F.P = B.P1 …….. (2)
By (1) – (2) we have I.P1 = B.P – B.P1
Similarly I.P2 = B.P – B.P2
I.P3 = B.P – B.P3
I.P4 = B.P – B.P4
I.P. of the engine I.P = I.P1 + I.P2 + I.P3 + I.P4
F.P. of the engine F.P = I.P – B.P
STARTING THE ENGINE:
1. Disengage the clutch and start the engine using the ignition key.
2. Engage the clutch slowly.
3. Adjust the throttle valve, so that the engine attains rated speed.
PROCEDURE:
1. Open the three- way cork so that fuel flows to the engine directly from the tank
2. Open the cooling water valves and ensure water flows through the engine
3. Open the water line to the hydraulic dynamometer
4. Start the engine and allow to run on No Load condition for few minutes
5. Operate the throttle valve so that the engine picks up the rated speed
6. Load the engine at full load and maintain the speed at rated rpm i.e., 1500 rpm
by adjusting the throttle and dynamometer loading wheel.
7. Allow the engine to run at this load for a few minutes.
8. Cut-off ignition to the first cylinder, and thus speed is decreased.
9. Without disturbing the throttle valve position, decrease the load on the engine,
until the original speed is restored.
10. Note the dynamometer reading, restore the ignition to the first cylinder
11. Repeat the above procedure by cutting off ignition to each of the cylinders.
12. Note the dynamometer readings for each cylinder when they are cut -off.
13. Engine stopped after removing the load.
PRECAUTIONS:
1. Before stating the engine check all the systems such as cooling , lubrication and
fuel system
2. Ensure oil level is maintained in the engine upto recommended level always.
Never run the engine with insufficient oil.
3. Never run the engine with insufficient engine cooling water and exhaust gas
calorimeter cooling water.
4. For stopping the engine, load on the engine should be removed.
OBSERVATIONS:
RRaatteedd SSppeeeedd==11550000 rrppmm
S. No
Condition Dynamometer load (W) Kg
B.P,
KW
I.P,
KW
F.P
KW
1 All cylinders working
W =
2 1st cylinder cut-off W1=
3 2nd cylinder cut-off W2=
4 3rd cylinder cut-off W3=
5 4th cylinder cut-off W4=
SAMPLE CALCULATIONS:
`B.P =60000
2 TN ……. KW (where T= torque = W×R)
B.P1= 60000
2 1TN ……. KW (R=320mm)
B.P2=60000
2 2TN .…… KW
B.P3= 60000
2 3TN …… KW
B.P4= 60000
2 4TN …… KW
I.P1 = B.P-B.P1 …… KW
I.P2 = B.P-B.P2…… KW
I.P3 = B.P-B.P3 …… KW
I.P4 = B.P-B.P4….. KW
I.P = I.P1+I.P2+I.P3+I.P4 . .KW
F.P = I.P-B.P…… Kw
Frictional power, F.P = KW
Mechanical efficiency m = 100P.I
P.B
RESULT:-
PPEERRFFOORRMMAANNCCEE TTEESSTT OONN 22-- SSTTRROOKKEE,,
SSIINNGGLLEE CCYYLLIINNDDEERR
PPEETTRROOLL EENNGGIINNEE TTEESSTT RRIIGG
PERFORMANCE TEST ON 2- STROKE, SINGLE CYLINDER PETROL ENGINE TEST RIG
AIM: To conduct a load test on a single cylinder, 2- Stroke petrol engine and study its
performance under various loads.
EQUIPMENT / APPARATUS:
1. 2-Stroke, Single Cylinder Petrol Engine with Resistance load bank
2. Tachometer
3. Stop Watch
SPECIFICATIONS: Make : Bajaj
Stroke : 57mm
Bore : 57mm
Rated R.P.M : 3000rpm
Output : 3 hp
Fuel : Petrol
Specific Gravity of petrol : 0.716
Calorific Value of petrol : 47100 KJ/Kg
Lubrication : 3% mixture of self mixing oil and
petrol
DESCRIPTION:
This Petrol engine is an air cooled, single cylinder, Vertical, 2-stroke engine. The
engine is kick started. The petrol engine is coupled to a Resistance load dynamometer to
absorb the power produced. The dynamometer is provided with load controller switches for
varying the load. Fuel consumption is measured with a burette and a stop watch. A three-
way cork, which regulates the flow of petrol from the tank to the engine.
PROCEDURE:
1. Open the three way cork so that fuel flows to the engine directly from the tank.
2. Start the engine and allow running on no load condition for few minutes.
3. Load the engine, by switching on the resistance from the load bank.
4. Note the following readings
a) Speed.
b) Voltage and Current.
c) Time taken for 10 cc of petrol consumption.
5. Repeat the above procedure at different loads.
6. Stop the engine after removing load on the engine
PRECAUTIONS
1. Use only petrol mixed with 2T oil – use higher oil /petrol ratio to compensate for the lack of cooling air ( air flow over the engine while moving ) in the stationary test rig
2. Changing gear oil regularly.
3. Never run the engine with insufficient fuel
MMOODDEELL GGRRAAPPHHSS::
BB..PP,, KKWW
mm
eecchh ,,%%
BB..PP ,, KKWW
SSFF
CC
KKgg
// KKWW
-- hhrr
BB
tthh,, %%
BB..PP,, KKWW
ii tthh,, %%
BB..PP,, KKWW
SS..NNOO
LLooaadd oonn tthhee
rreessiissttaannccee llooaadd
bbaannkk SSpp
eeee
dd
MMaannoommeetteerr
rreeaaddiinngg
AAii rr
hheeaa
dd cc
aauu
ssii nn
gg
ff lloo
ww
(( HHaa))
mm oo
ff aa
ii rr
TTii mm
ee ff
oorr
1100
cccc
ooff
ff uuee
ll
TT.. FF
.. CC
HHee
aatt
II nnpp
uutt
II ..PP
BB.. PP
FF.. PP
VVoollttaaggee
((VVoollttss)) CCuurrrreenntt
((aammpp)) RRPPMM hh11 hh22
hh11~~hh22
ccmm SSeecc kkgg//hhrr kkWW kkWW kkWW kkWW
11
22
33
44
55
66
BB..PP,, KKWW FF.. PP,, KKWW TT
FFCC
,, KK
gg //
hhrr
SAMPLE CALCULATIONS:
1. Air head causing flow = 100
h
air
water
…………………….. mm ooff aaiirr
22.. AAccttuuaall vvoolluummee ooff aaiirr iinnttaakkee==VVaa== CCdd AA00 agH2 ==
WWhheerree CCdd== 00..6622
AA00== 33..1144 XX 1100--44
33.. TThheeoorreettiiccaall vvoolluummee ooff aaiirr == VVtthh == 60
N Ls D 4
2
mm33//SSeecc
44.. VVoolluummeettrriicc eeffffiicciieennccyy == 100V
V
th
a
55.. MMaassss ooff ffuueell == 1000
71.0 Q mm//sseecc
QQ == t
10 cc/ sec
66.. BBrraakkee ppoowweerr BB..PP == 100
g
IV
WW
g = 80 %
77.. BBrraakkee ssppeecciiffiicc ffuueell ccoonnssuummppttiioonn,, BBSSFFCC == PB
CFT
.
..…………....KKgg //KKww--hhrr
88.. IInnddiiccaatteedd ppoowweerr II..PP == BB..PP ++ FF..PP
SS.. NNOO
II..SS..FF..CC BB..SS..FF..CC
AAccttuuaall
vvoolluummee
ooff aaiirr
VVaa
MMaassss ooff
aaiirr
TThheeoorreettii
ccaall
vvoolluummee
ooff aaiirr
VVtthh
EEffffiicciieenncciieess
kkgg//kkww--hh kkgg//kkww--hh mm33//ss kkgg//ss mm33//ss VVooll BBtthh IItthh mm
11
22
33
44
55..
66..
99.. IInnddiiccaatteedd ssppeecciiffiicc ffuueell ccoonnssuummppttiioonn,, IISSFFCC ==PI
CFT
.
..…………KKgg //KKww--hhrr
1100.. BBrraakkee tthheerrmmaall eeffffiicciieennccyy,, BB tthh == vf Cm
PB
.
1111.. IInnddiiccaatteedd tthheerrmmaall eeffffiicciieennccyy,, II tthh == vf Cm
PI.
1122.. MMeecchhaanniiccaall eeffffiicciieennccyy,, mm == 100.
.
PI
PB
RRESULT::--
AIM:
To conduct a performance test on a refrigerator with Freon 12 refrigerant to
determine the coefficient of performance. EQUIPMENT /APPARATUS:
1. Refrigeration test rig
2. Measuring jar
3. Stop watch
SPRCIFICATIONS:
Make : Altech
Compressor : 1 / 3 Ton of refrigeration
Condenser : Air Cooled
Expansion Device : i ) Capillary Tube
ii) Solenoid Valve
Evaporator Coil : Immersed in water Tank of stainless
steel
Refrigerant : Freon – 22. DESCRIPTION:
The test rig consists of a hermetically sealed compressor. The compressed
refrigerant from the compressor is sent to an air cooled condenser and the condensate in
liquid form is sent to the expansion valve /capillary tube for throttling. Due to throttling
temperature of the refrigerant falls and the cold refrigerant absorbs heat from the water in
the evaporator tank. The refrigerant is then returned to the compressor.
A suitable filter and a transparent rotameter to visually observe the liquid.
Refrigerant is fitted in the refrigerant line from condenser to evaporator. A thermocouple is
provided to measure the temperature of the water in the evaporator tank. An energy meter
is provided to measure the energy input to the compressor. Suitable pressure gauges are
provided at the compressor inlet (evaporator outlet),
PPEERRFFOORRMMAANNCCEE TTEESSTT OONN RREEFFRRIIGGEERRAATTIIOONN
TTEESSTT RRIIGG
Condenser inlet (compressor outlet), condenser outlet (before throttling) and evaporator
inlet (after throttling) to study the refrigeration cycle operating between the two pressures. A
thermostat is provided for the cutting off the power to compressor when the water
temperature reaches asset value. A voltmeter and an ammeter are provided to monitor the
inlet power supply. A voltage stabilizer is provided for the protection of compressor.
Provisions are provided in the refrigerant pipe lines for charging the test rig with additional
refrigerant if necessary. Additional 4 No’s of thermocouples are fitted at the condenser and
evaporator inlet and outlet for studying the temperature at the 4 points in the refrigeration
cycle
THEORY:
A refrigerator consists of a compressor connected by suitable pipelines to a
condenser, a capillary tube and an evaporator. Refrigerant (Freon12) in vapor state from
the evaporator is compressed in the compressor and sent to the condenser. Here it
condenses’s in to liquid and it is then throttled. Due to throttling temperature of refrigerant
drops and the cold refrigerant passes through the evaporator absorbing heat from the
object to be cooled. The refrigerant is then returned to the compressor and the cycle is
completed
PROCEDURE:
1. Fill up the evaporator tank with a know quantity of water (say 10-15 litres).
2. Switch on the compressor.
3. After about 5 minutes (after steady state had set in) note the initial energy meter
reading and water temperature in the evaporator.
4. After a known period of time, say 30 minutes note down the energy meter reading
and water temperature.
5. Calculate the actual COP.
6. Note the Refrigerant pressures at compressor inlet (evaporator outlet), condenser
inlet (compressor outlet), condenser outlet (before throttling) and evaporator inlet
(after throttling) using the pressure gauges.
7. Note the Temperatures at compressor inlet (evaporator outlet), condenser inlet
(compressor outlet), condenser outlet (before throttling) and evaporator inlet (after
throttling) using the thermocouples provided.
8. Draw pressure- enthalpy diagram.
9. Calculate the theoretical COP
10. Calculate the relative cop
PRECAUTIONS:
1. Before noting the water temperature, physically Stir the water to ensure that the
temperature is uniform in the water tank
2. Since COP depends upon the evaporator temperature and condenser temperature,
the calculated COP (which is an average value) will be different for varying
evaporator, condenser and water temperatures.
3. When the compressor turns off (by the thermostat) or is switched off manually, do
not turn on the power immediately. Allow a few minutes for the pressure in the
compressor inlet and outlet to equalize. The time delay provided in the voltage
stabilizer is for this purpose only. Immediate starting
will cause under load on the compressor and may even lead to burn out SAMPLE CALCULATIONS:
ACTUAL COP:
Quantity of water in evaporator tank, m =…………….. Kg
Time taken for experiment, t =………………..hours
Initial temperature of water,T0 =………..0C
Final temperature of water, Tf = ………..0C
Initial energy meter reading, E0 = …………Kwh
Initial energy meter reading, Ef = ……….Kwh
Refrigerating effect per hour = m(T0 - T f )
t
Energy input = E f Eo
…..KW
t
Actual Coefficient of Performance, COP = refrigerating effect
Energy input
Actual COP =
THEORETICAL COP:
Theoretical COP is calculated from the pressure measured from pressure gauges
(evaporator and condenser pressures) and the temperatures measured from four
thermocouples located at four points of the thermodynamic cycle (refer figure 1).
S.No Reading Temperature, Pressure, Pressure,
0C Psi Bar
1 Condenser inlet
2 Condenser outlet
3 Evaporator inlet
4 Evaporator outlet
Note: Bar = Psi +1
14.5
From P-h diagram for R-12 Enthalpy of refrigerant at evaporator outlet, (before compression) h1 = ….Kj/Kg
Enthalpy of refrigerant at condenser inlet, (after compression) h2 = … …..Kj /kg
Enthalpy of refrigerant at condenser outlet, (before throttling) h3 = ………..Kj/Kg
Enthalpy of refrigerant at evaporator inlet, (after throttling) h4 = …………….Kj/Kg
Theoretical COP = (h1
h4
)
(h2 h1 )
Actual COP
Relative COP = Theoritical COP
RESULT :
AASSSSEEMMBBLLYY AANNDD DDIISSAASSSSEEMMBBLLYY OOFF
IICC EENNGGIINNEESS
Aim: To study the different types of I.C engines, various parts of I.C engines, cycles of
operation etc.,
Introduction:
Any type of engine, which derives heat energy from the combustion of fuel and converts
this energy into mechanical work, is termed as a heat engine. These are classified as
1. External Combustion engines (E.C)
2. Internal Combustion engines (I.C)
If the combustion of fuel takes place outside the working cylinder then the
engine is called External Combustion Engine. If the combustion takes place inside the
working cylinder the engine is called Internal Combustion Engine. The most common
examples of E.C engines are steam engines and steam turbines. I.C engines are used in
scooters, cars, locomotives, agriculture and earth moving machinery, power generation and
in many industrial applications. The advantages of I.C engines over E.C engines are high
efficiency, simplicity, compactness, light weight, easy starting and low cost.
Classification of I.C Engines:
I.C Engines are classified as follows
1. According to the fuel used: Petrol engine, Diesel engine and Gas engine.
2. According to cycle of operations: 2-stroke engine and 4-stroke engine
3. According to the method of ignition: Spark ignition (S.I) engine, Compression Ignition
(C.I) engine.
4. According to the number of cylinders: single cylinder engine, multi cylinder engine.
5. According to the method of cooling the cylinder: Air-cooled engine and Water-cooled
engine.
6. According to the arrangement of cylinder: Horizontal engine, Vertical engine and
Radial engine.
I.C Engine Parts and their Function:
An I.C engine consists of many different parts, however the main components are
described below.
1.Cylinder: The heart of the engine is the cylinder and its primary function is to contain the
working fuel under pressure and the secondary function is to guide the piston. To avoid the
wear of the cylinder block cylinder liners are provided. The cylinder is made of Gray Cast
Iron.
2.Cylinder Head: One end of the cylinder is closed by means of a removable cylinder
head, which usually contains the inlet valve for admitting fuel and exhaust valve for
discharging products of combustion. The valves are operated by means of cams geared to
the engine shaft. The cylinder head is usually made of cast iron or alloy cast iron containing
Nickel, Chromium and Molybdenum.
3.Piston: The piston used in I.C engines is usually of trunk type and are open at one end.
The main function of the piston is to receive the impulse from the expanding gas and
transmit the energy to the crankshaft through the connecting rod. At the same time the
piston must also disperse a large amount of heat from the combustion chamber to the
cylinder walls. Pistons are made of cast iron or Aluminum alloys for lightness.
4. Piston Rings: These are circular rings and made of special steel alloys, which retain
elastic properties even at high temperatures. The piston rings are housed in the
circumferential grooves provided on the outer surface of the piston. Generally there are two
sets of rings mounted on the piston. The function of the upper rings is to provide air tight
seal to prevent leakage of the burnt gases into the lower portion. Similarly the function of
the lower rings is to provide effective seal to prevent leakage of the oil into the engine
cylinder.
5.Connecting Rod: One end of the connecting rod is connected to the piston through
piston pin and the other end is connected to the crank through the crank pin. The usual
cross section of connecting rod is I-section or H-section and these are made of carbon
steel or alloy steel. The main function is to transmit force from the piston to the crankshaft.
Moreover, it converts reciprocating motion of the piston into the circular motion of the crank
shaft in the working stroke.
6.Crank shaft: crank shaft consists of the shaft part which revolve in the main bearing. The
big end of the connecting rod is connected to the crank pin. The crank web connects to the
crank pin and shaft part. The function of the crankshaft is to transform reciprocating motion
into rotary motion. Crankshafts are made of carbon steel.
7.Cam shaft: It is driven from the crank shaft by timing gears on a chain. It operates the
intake valve and the exhaust valve through the cams and followers, push rods and rocker
arms.
8.Fly wheel: It is a big wheel mounted on the crank shaft whose function is to reduce the
vibrational fluctuations. It stores excess energy during power stroke and releases during
the other strokes.
Cycle of operation: The number of strokes of the piston required to complete the cycle
varies with the type of engine. There are two types of engines namely four stroke cycle
engine and two stroke cycle engine. A four-stroke cycle engine requires four strokes of
piston or two revolutions of the crankshaft to complete one cycle. In a two-stroke engine
there are two strokes of the piston or one revolution of the crankshaft to complete one
cycle. The four stroke and two stroke engines are further divided into petrol and diesel
engines according to the type of fuel used.
Four stroke petrol / Diesel engine: The four stroke engine utilizes four strokes namely
suction stroke, compression stroke, power stroke, and exhaust stroke for completion of a
cycle and it has two valves, one for the inflow of the air fuel mixture or pure air and the
other for the exhaust of burnt gases. At the start of the working cycle, the piston is at the
top dead center position (TDC). As the piston begins its outward stroke the inlet valve
opens and a mixture of fuel and air in metered proportions flows in, If the engine is of the
spark ignition type only, air flows in through the inlet valve. When the piston starts moving
back into the cylinder, both inlet and exhaust valves closes. The air or air fuel mixture thus
trapped between the piston and the cylinder head is now compressed until the piston
reaches the TDC at the end of compression stroke. Just before the end of the compression
stroke of the piston ignition occurs due to a spark in case of petrol engines or a spray of oil
injected into the cylinder in case of diesel engines. In either case, the thermal energy
released makes the compressed gas expand rapidly and drives the piston outwards. The
resulting stroke is called the power stroke. As the piston completes the power stroke and
returns T.D.C, the exhaust valve opens and the burnt exhaust gases in the cylinder are
driven out. At the instant the, piston reaches the TDC position, the exhaust valve closes
and the inlet valve will be ready to open, starting a new cycle of operation again.
Two stroke S.I / C.I engines:
The two stroke engines utilize only two strokes (Compression stroke and power
stroke) for the completion of a cycle. In two-stroke engine there are two ports. One in the
inlet and one in the outlet for gasses. The opening and closing of the ports depends on the
position of the piston in the cylinder. The piston is at T.D.C both outlet and transfer ports
are closed when the compressed air fuel mixture or air in the cylinder is about to be ignited
by either a sparking device or fuel injection. When piston travels back during the power
stroke, it uncovers the exhaust port first and a moment later the transfer port. The opening
of the transfer port puts the cylinder in contact with the crankcase containing a slightly
compressed air fuel mixture or air. The incoming fresh charge helps in driving out the burnt
gases through the exhaust port. The head of the piston being shaped to assist this
scavenging action. As the piston returns into the cylinder, it covers both the transfer and
exhausts ports and compresses the trapped gas until it reaches the T.D.C position. At the
same time a fresh charge is drawn into the crankcase through the inlet port. A cycle is thus
completed with one power stroke in every two-piston strokes.
In a two stroke engine a small amount of burnt gas always remains in
the cylinder along with the fresh charge when the piston covers the ports and starts
compressing the gases trapped inside. Moreover, since both transfer port and exhaust
ports are simultaneously open during part of the piston stroke, some of the incoming fresh
charge escapes with the burnt gases. As a result the efficiency of a two stroke engine is
lower, further two stroke engines consume large amounts of lubricating oil compared with
four stroke engines and are likely to be noisier because of the sudden opening of the
exhaust ports.
Valve Timing Diagram:
The valve timing diagram shows the position of the crank when the various
operations, i.e. suction, compression, expansion and exhaust begin and end.
The valve timing is the regulation of the positions in the cycle at which the valves are
set to open and close. Since the valves requires a finite period of time to open or close
without a rupture, a slight ‘lead’ time is necessary for the proper operation. The design of
valve operating can provide for smooth transition from one position to the other, while cam
setting determines the timing of the valve.
Theoretically it may be assumed that the valves open and close and spark (or
injection of fuel) occurs at the engine dead centers. However, in actual operation the valves
do not operate at it center positions but operate some degrees away on either side of the
dead centers. The opening occurs earlier and the exhaust continues even at later crank
angles. The ignition is also timed to occur earlier. The injection of fuel in the case of diesel
engine is also timed to occur in advance of the completion of compression stroke.
The timing of these events referred in terms of crank angles from dead center
positions, is presented on a valve-timing diagram. The correct timings are of fundamental
importance for the efficient and successful running of the I.C engine.