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THERMAL ENGINEERING LAB MANUAL
BALAJI INSTITUTE OF
TECHNOLOGY AND
SCIENCE LAKNEPALLY (V), NARSAMPET (M), WARANGAL-506331
THERMAL
ENGINEERING
LABORATORY
MANUAL DEPARTMENT OF MECHANICAL
ENGINEERING
NUSRATH FAHIMA, Assistant professor
THERMAL ENGINEERING LAB MANUAL
III YEAR I SEM
BALAJI INSTITUTE OF TECHNOLOGY AND SCIENCE
DEPARTMENT OF MECHANICAL ENGINEERING
THERMAL ENGINEERING LABORATORY
YEAR: B.TECH IIIRD YR - I SEM ACADEMIC YEAR: 2015-16
LIST OF EXPERIMENTS
1. I.C. ENGINES VALVE / PORT TIMING DIAGRAMS.
2. I.C. ENGINES PERFORMANCE TEST FOR 4 –STROKE SI ENGINES.
3. I.C. ENGINES PERFORMANCE TEST FOR 2-STROKE SI ENGINES.
4. ENGINE MORSE, RETARDATION, MOTORING TESTS.
5. I.C. ENGINES HEAT BALANCE –CI/SI ENGINES.
6. I.C ENGINES ECONOMICAL SPEED TEST FOR FIXED LOAD ON 4-S SI
ENGINE.
7. I.C ENGINE EFFECT OF A/F RATIO IN A SI ENGINE.
8. PERFORMANCE TEST ON VARIABLE COMPRESSION RATIO ENGINE.
9. IC ENGINE PERFORMANCE TEST ON A 4S CI ENGINE AT CONSTANT
SPEED.
10. VOLUMETRIC EFFICIENCY OF RECIPROCATING AIR-COMPRESSOR
UNIT.
11. DIS-ASSEMBLY / ASSEMBLY OF ENGINES.
12. STUDY OF BOILERS.
PORT TIMING DIAGRAM OF SINGLE CYLINDER
TWO STROKE SPARK IGNITION ENGINE
AIM:
To draw the port timing diagram of a two stroke spark ignition engine.
APPARATUS REQUIRED:
1. A two stroke petrol engine 2. Measuring tape 3. Chalk
BRIEF THEORY OF THE EXPERIMENT:
The port timing diagram gives an idea about how various operations are taking place in an
engine cycle. The two stroke engines have inlet and transfer ports to transfer the combustible
air fuel mixture and an exhaust port to transfer exhaust gas after combustion. The sequence of
events such as opening and closing of ports are controlled by the movements of piston as it
moves from TDC to BDC and vice versa. As the cycle of operation is completed in two
strokes, one power stroke is obtained for every crankshaft revolution. Two operations are
performed for each stroke both above the piston (in the cylinder) and below the piston (crank
case). When compression is going on top side of the piston, the charge enters to the crank
case through inlet port. During the downward motion, power stroke takes place in the
cylinder and at the same time, charge in the crank case is compressed and taken to the
cylinder through the transfer port. During this period exhaust port is also opened and the
fresh charge drives away the exhaust which is known scavenging. As the timing plays major
role in exhaust and transfer of the charge, it is important to study the events in detail. The
pictorial representation of the timing enables us to know the duration and instants of opening
and closing of all the ports. Since one cycle is completed in one revolution i.e. 360 degrees of
crank revolution, various positions are shown in a single circle of suitable diagram
PROCEDURE
1. Mark the direction of rotation of the flywheel. Always rotate only in clockwise direction
when viewing in front of the flywheel.
2. Mark the Bottom Dead Center (BDC) position on the flywheel with the reference point
when the piston reaches the lowermost position during rotation of the flywheel.
3. Mark the Top Dead Center (TDC) position on the flywheel with the reference point when
the Piston reaches the top most position during the rotation of flywheel.
4. Mark the IPO, IPC, EPO, EPC, TPO, and TPC on the flywheel observing the following
conditions.
5. Inlet port open (IPO) when the bottom edge of the piston skirt just opens the lower most
part of the inlet port during its upward movement.
6. Inlet port close (IPC) when the bottom edge of the piston fully reaches the lower most part
of the inlet port during its downward movement.
7. Transfer port open (TPO) when the top edge of the piston just open the top most part of the
Transfer port during its downward movement.
8. Transfer port close (TPC) when the top edge of the piston fully reaches the upper most part
of the transfer port during its upward movement
9. Exhaust port open (EPO) when the top edge of the piston just opens the top most part of
the exhaust port during its downward movement.
10. Exhaust port close (EPC) when the top edge of the piston fully reaches the upper most
part of the exhaust port during its upward movement
11. Measure the circumferential distance of the above events either from TDC or from BDC
whichever is nearer and calculate their respective angles.
12. Draw a circle and mark the angles.
FORMULA:
Angle = 360
L=
X=
Where, L – Distance from nearest dead center in mm
X- Circumference of the Flywheel in mm
OBSERVATION TABLE:
Sl. No Description Distance in mm Angle in degrees
1 IPO before TDC
2 IPC after TDC
3 EPO before BDC
4 EPC after BDC
5 TPO before BDC
6 TPC after BDC
RESULT: The given two-stroke petrol engine is studied and the Port timing diagram is
drawn for the present set of values.
REVIEW QUESTIONS:
1. What is the difference between valves and ports?
2. How does the opening and closing of ports happen in two stroke engines?
3. What is the use of transfer port?
4. Give reason for larger exhaust port diameter than the transfer port.
5. What do you mean by scavenging?
6. What is the pressure developed in crank case?
7. What are the problems associated with two stroke engines?
8. What are the advantages of two stroke engines?
9. How are two stroke engines lubricated? Give the name.
10. Define compression ratio. Give the range of compression ratio for petrol and diesel
engines.
VALVE TIMING DIAGRAM OF A SINGLE
CYLINDER FOUR STROKE COMPRESSION
IGNITION ENGINE
AIM:
To draw the valve timing diagram of the four stroke compression ignition engine.
REQUIREMENTS:
1. Experimental engine
2. Measuring tape
3. Chalks
BRIEF THEORY OF THE EXPERIMENT:
The valve timing diagram gives an idea about how various operations are taking place in an
engine cycle. The four stroke diesel engines have inlet valve to supply air inside the cylinder
during suction stroke and an exhaust valve to transfer exhaust gas after combustion to the
atmosphere. The fuel is injected directly inside the cylinder with the help of a fuel injector.
The sequence of events such as opening and closing of valves which are performed by cam-
follower rocker arm mechanism in relation to the movements of the piston as it moves from
TDC to BDC and vice versa. As the cycle of operation is completed in four strokes, one
power stroke is obtained for every two revolution of the crankshaft. The suction,
compression, power and exhaust processes are expected to complete in the respective
individual strokes. Valves do not open or close exactly at the two dead centers in order to
transfer the intake charge and the exhaust gas effectively. The timing is set in such a way that
the inlet valve opens before TDC and closes after BDC and the exhaust valve opens before
BDC and closes after TDC. Since one cycle is completed in two revolutions i.e 720 degrees
of crank rotations.
PROCEDURE:
1. Mark the direction of rotation of the flywheel. Always rotate only in clockwise direction
when viewing in front of the flywheel.
2. Mark the Bottom Dead Center (BDC) position on the flywheel with the reference point
when the piston reaches the lowermost position during rotation of the flywheel.
3. Mark the Top Dead Center (TDC) position on the flywheel with the reference point when
the piston reaches the top most position during the rotation of flywheel.
4. Identify the four strokes by the rotation of the flywheel and observe the movement of inlet
and exhaust valves.
5. Mark the opening and closing events of the inlet and exhaust valves on the flywheel.
6. Measure the circumferential distance of the above events either from TDC or from BDC
whichever is nearer and calculate their respective angles.
7. Draw the valve timing diagram and indicate the valve opening and closing periods.
FORMULA:
Angle = 360
L=
X=
Where, L – Distance from nearest dead center in mm
X- Circumference of the Flywheel in mm mts are shown by drawing spirals of suitable
diameters. As the timing plays major role in transfer of the charge, which reflects on the
engine performance, it is important to study these events in detail.
OBSERVATIONS:
Sl. No Description Distance in mm Angle in degrees
1 IVO before TDC
2 IVC after TDC
3 EVO before BDC
4 EVC after BDC
RESULT:
The given four stroke compression ignition engine is studied and the valve timing diagram is
drawn for the present set of values.
REVIEW QUESTIONS:
1. How the valves are different from ports?
2. What are the advantages of four stroke engines over two stroke engines?
3. Why four stroke engines are more fuel efficient than two stroke engines?
4. Explain the lubrication system of four stroke engines.
5. What do you mean by valve overlap? What are their effects in SI engines?
6. How the cylinder numbers assigned in multi-cylinder I.C. engines?
7. Give firing order for a four and six cylinder engines.
8. Explain how the correct direction of rotation is found before starting the valve timing
experiment.
9. How do you identify an engine is working on two stroke or four stroke principle?
10. How do you identify whether it is petrol or diesel engine?
TWO STROKE SINGLE CYLINDER PETROL ENGINE
TEST RIG WITH DC GENERATOR
OBJECTIVE:
To conduct a performance test on two stroke single cylinder petrol engine.
INSTRUMENTATION:
1. Digital RPM Indicator to measure the speed of the engine.
2. Digital temperature indicator to measure various temperatures.
3. Differential manometer to measure quantity of air sucked into cylinder.
4. Burette with manifold to measure the rate of fuel consumed during test.
5. Digital voltmeter to measure the voltage.
6. DIGITAL AMMETER TO MEASURE THE CURRENT.
ENGINE SPECIFICATION:
ENGINE : BAJAJ
BHP : 2.5 HP
RPM : 2800 RPM
FUEL : PETROL
No OF CYLINDERS : SINGLE
BORE : 56.7 mm
STROKE LENGTH : 56.7mm
STARTING : KICK START
WORKING CYCLE : TWO STROKE
METHOD OF COOLING : AIR COOLED
METHOD OF IGNITION : SPARK IGNITION
ORIFICE DIA. : 20mm
DC GENERATOR SPECIFICATION:
TYPE : SELF EXCITED, DC COMPOUND GENERATOR.
POWER : 2.2 kW
SPEED : 3000 RPM (max)
RATED VOLTAGE : 220v DC
RESISTANCE LOAD BANK SPECIFICATION:
RATING : 2.5KW, 1Φ (SINGLE PHASE)
VARIATION : In 5 steps by dc switches.
COOLING : Air cooled
OBSERVATIONS:
Brake power : BP
Specific fuel consumption : Sfc
Actual volume : Va
Brake thermal efficiency : ŋbth
SWEPT VOLUME : VS
Volumetric efficiency : ŋv
DESCRIPTION:
This engine is a two stroke single cylinder, air-cooled, spark ignition type petrol engine. It is
coupled to a loading system which is in this case is a DC GENERATOR, having a resistance
load bank which will take load with the help of dc switches.
FUEL MEASUREMENT:
The fuel is supplied to the engine from the main fuel tank through a graduated measuring fuel
gauge (Burette). To measure the fuel consumption of the engine, fill the burette by opening
the cock. By starting a stop clock, measure the time taken to consume X cc of fuel by the
engine.
AIR INTAKE MEASUREMENT:
The suction side of the engine is connected to an Air tank. The atmospheric air is drawn into
the engine cylinder through the air tank. The manometer is provided to measure the pressure
drop across an orifice provided in the intake pipe of the Air tank. This pressure drop is used
to calculate the volume of air drawn into the cylinder. (Orifice diameter is 20 mm.)
LUBRICATION:
The engine is lubricated by mechanical lubrication.
Lubricating oil recommended – SAE- 40 OR Equivalent.
TEMPERATURE MEASUREMENT:
A digital temperature indicator with selector switch is provided on the panel to read the
temperature in degree centigrade, directly sensed by respective thermocouples located at
different places on the test rig.
THERMOCOUPLE DETAILS
T1 = AMBIENT TEMPERATURE
T2 = EXHAUST GAS OUTLET TEMPERATURE FROM ENGINE
LOADING SYSTEM:
The engine shaft is directly coupled to the DC Generator, which can be loaded by resistance
load bank. The load can be varied by switching ON the Load bank switches for various loads.
PROCEDURE:
1. Connect the instrumentation power input plug to a 230v, 50 Hz AC single phase AC
supply. Now all the digital meters namely, RPM indicator, temperature indicator display the
respective readings.
2. Fill up the petrol to the fuel tank mounted behind the panel.
3. Start the engine with the help of kicker provided at the rear end of the Engine.
4. Allow the engine to stabilize the speed ie, 2800 RPM by adjusting the accelerator knob.
5. Apply ¼ loads (500 W)
6. Note down all the required parameters mentioned below.
a. Speed of the engine in RPM.
B. Load from ammeter in amps.
C. Burette reading in cc.
D. Manometer reading in mm.
E. Time taken for consumption of Xcc petrol in seconds.
F. Temperature in degree C.
7. Load the engine step by step with the use of DC switches provided on the load bank panel.
8. Note down all required readings.
ENGINE PERFORMANCE TEST:
1. BRAKE POWER
BP = V x I ……………Kw.
1000 x ŋgen
Where, V = dc voltage in volts.
I = dc current in amps.
ŋgen = Generator efficiency = 80%
2. MASS OF FUEL CONSUMED.
M f c= X x 0.72 x 3600 …..Kg/ hr
1000 x t
Where, X = burette reading in cc
0.72 = density of petrol in gram / cc
t = time taken in seconds.
3. SPECIFIC FUEL CONSUMPTION.
Sfc = mfc………..kg/kW hr
BP
4. ACTUAL VOLUME OF AIR SUCKED IN TO THE CYLINDER.
Va = Cd X A √ 2gH X 3600 ……..m3/hr
where, H = h X δw ………meter of water.
1000 ΔA
A = area of orifice = Π d2/4
h = manometer reading in mm
δw = density of water =1000 kg/m3
δa = density of air =1.193 kg/ m3
Cd = co-efficient of discharge = 0.62
5. SWEPT VOLUME
Vs = Π d2 x L x N x 60S
4
Where, d = dia.S of bore = 56.7 mm
L = length of stroke = 56.7 mm
N = Speed of the engine in RPM.
6. VOLUMETRIC EFFICIENCY
ŋv = VA X 100 ……….%
VS
7. BRAKE THERMAL OR OVER ALL EFFICIENCY
Ŋbth = BP X 3600 X 100 ……….%
mfc X cv
Where, cv = calorific value of petrol = 43500 kJ / kg.
BP = Brake Power in kW.
8. MECHANICAL EFFICIENCY:
ΗMECH =BP X 100 …………%
IP
where , BP = Brake Power in kW.
IP = Indicated power in kW.
TABULAR COLUMN :( For performance test)
SL
no.
V
IN VOLTS
I
IN
AMPS
SPEED IN
RPM
TIME TAKEN FOR
10CC OF FUEL IN
SEC
t
MANOMETER
READING IN MM
h1 h2
MOTARING TEST
OBJECTIVE:
To measure the FP of the given four stroke single cylinder petrol engine by MOTARING
TEST.
PROCEDURE:
To conduct the motoring test, first connect the rectifier to the panel board.
1. Remove the spark plug connection from the engine.
2. Keep the change-over switch in the motoring direction.
3. Now slowly increase the power using Variac provided in the rectifier circuit.
4. Increase the voltage up to 220 Vand note down the armature current and voltage and
Speed.
5. Now slowly decrease the power on rheostats to zero and turn the change-over switch to
OFF position.
FRICTIONAL POWER OF THE ENGINE:
FP(ENGINE) = FP(TOTAL) – Losses in motor
Where, Losses in motor = No load generator losses.
= 380 W = 0.38 Kw
FP(TOTAL) = Total frictional power.
= V x I ………….. kW.
1000
Therefore, FP = ………………..kW.
Therefore,
INDICATED POWER
IP = BP + FP
TABULAR COLUMN: (FOR MOTARING TEST)
SL
NO.
SPEED IN RPM
RPM.
ARMATURE VOLTAGE
IN VOLTS.
ARMATURE CURRENT
IN AMPS.
1
2
RESULT:
RETARDATION TEST ON FOUR STROKE SINGLE
CYLINDER DIESEL ENGINE
Aim: To determine the frictional power of a four stroke single cylinder diesel engine by
retardation through additional flywheel method.
FORMULAE USED:
1. Mass moment of inertia of additional flywheel.
If =W * r2 kg m2 =
Where, W = weight of the additional flywheel in kg. = 38 kg.
R = radius of the additional flywheel in m = 0.19 m
2. Angular deceleration.
a. With additional flywheel, Ad1 = 2π(N1- N2)/60T1 rad/sec2
b. Without additional flywheel, Ad2 = 2π(N1- N2)/60T2 rad/sec2
Where, N1 = Initial speed of the engine. (1500rpm)
N2 = Final speed of the engine. (1400rpm)
T1 = Time taken for the speed to come down from N1to N2 with additional flywheel
T2 = Time taken for the speed to come down from N1to N2 without additional flywheel
And therefore,
Frictional Torque (Tf) = Mass moment of inertia * Angular deceleration
Tf = If * Ad1
To find frictional power,
FP = 2πN Tf /60
Where N = average speed = N1+ N2 / 2
Therefore, IP = BP + FP
TABULATION:
Sl.
No.
Weight of the
additional flywheel W
kg
Speed of
engine N
rpm
Time taken for speed
reduction
With flywheel
T1 sec
Without
flywheel T2
sec
PROCEDURE:
1. Start the engine and allow it to stabilize the speed.
2. Cut-off the fuel supply completely by pressing the rack of the fuel pump to
stop position.
3. Note down the time taken (T1) in seconds for the speed to come down from
1500 to 1400 rpm.
5. Now declutch the additional flywheel even while the engine is running. Repeat the steps
2 to 4 and note down the time (T2) for the engine to come down from 1500 to 1400 rpm.
In both the cases, the engine speed come down only due to frictional power of
the engine. From these, it is observed that the time T1 is greater than T2 because of inertia
of the additional fly wheel.
RESULT: Thus, the frictional power of a four stroke single cylinder diesel has been determined by
retardation through additional flywheel method.
MORSE TEST ON MULTI CYLINDER PETROL ENGINE
Aim: To conduct Morse test on given multi cylinder petrol engine in order to determine the
indicated power developed in the each cylinder of the engine and to determine the
mechanical efficiency.
Apparatus Required:
1. Multi cylinder petrol engine with ignition cut off arrangement
2. Loading arrangements
3. Tachometer
Theory and Description:
For slow speed engine the indicated power is directly calculated from the indicator
diagram. But in modern high speed engines, it is difficult to obtain accurate indicator diagram
due to inertia forces, and therefore, this method cannot be applied. In such cases the Morse
test can be used to measure the indicated power and mechanical efficiency of multi cylinder
engines. The engines test is carried out as follows. The engine is run at maximum load at
certain speed. The B.P is then measured when all cylinders are working. Then one cylinder is
made in operative by cutting off the ignition to that cylinder. As a result of this the speed of
the engine will decrease. Therefore, the load on the engine is reduced so that the engine speed
is restored to its initial value. The assumption made on the test is that frictional power is
depends on the speed and not upon the load on the engine.
Definitions:
Brake power (BP): The useful power available at the crank shaft of the engine is called brake
power of the engine. The brake power of the engine are determined by
1. Rope brake dynamometer. T = WRe
W = net load
Re = effective radius of the brake drum
2. Prony brake dynamometer T = WL
W = Load
L = Distance at which the load is applied
Observation and Tabulation:
(1) Brake power B.P =........... KW
(2) Rated Speed N =...........Rpm
(3) Type of loading: =...........
(4) Radius of brake drum: R =...........m
(5) Radius of Rope r = =...........m
(6) Number of cylinders = 4
TABULAR COLUMN:
S No Conditions Loading Speed
Rpm
BP ‘KW’
W1
kg
W2
kg
W1 –
W2
kg
Net
load
W in
‘N’
1 All cylinders are working
2 First cylinder was cut off
and remaining are in
working
3 Second cylinder was cut
off and remaining are in
working
4 Third cylinder was cut
off and remaining are in
working
5 Fourth cylinder was cut
off and remaining are in
working
Note: The speed should be same for all readings
3. Hydraulic dynamometer
B.P = WN/C
W = Load
N = Speed in RPM
C = Dynamometer constant
4. Electrical dynamometer
Indicated power: (I P) The power actually developed inside the engine cylinder due to the combustion of the fuel
are called indicated power.
IP = FP + BP; FP = Frictional power
Frictional power (FP): The power loss due to friction between the moving parts are called as frictional power.
Mechanical efficiency : (mech ) It is defined as the ratio of Brake power to indicated power.
= B.P/ I.P x 100
Procedure:
1. Check the engine for fuel availability, lubricant and cooling water connections.
2. Release the load completely on the engine and start the engine in no load conditions and
allow the engine to run for few minutes to attain the rated speed.
3. Apply the load and increase the load up to maximum load. (All four cylinders should be in
working). Now note the load on the engine and speed of the engine say the speed is ‘N’ rpm
4. Cut-off the ignition of first cylinder, now the speed of engine decreased. Reduce the load
on the engine and bring the speed of the engine to ‘N’ rpm. Now note the load on the engine.
5. Bring the all four cylinders are in working conditions and cut off the 2nd , 3rd and 4th
cylinder in turn and adjust the load to maintain same ‘N’ rpm and note the load .
Result:
Morse test was conducted on given petrol engine and indicated power developed in each
cylinder are determined and mechanical efficiency are also determined.
I.C ENGINE EFFECT OF A/F RATIO IN A SI ENGINE
OBJECTIVE: To determine the effect of A/F ratio on S I Engine.
INTRODUCTION: Test rig is with two stroke Petrol engine, coupled to Electrical
dynamometer. Engine is air cooled type, hence only load test can be conducted at a constant
speed of 3000rpm. Test rig is complete with base, air measurement, fuel measurement and
temperature measurement system. Thermocouple is employed to measure temperature
digitally. Two stroke engines are coupled with ports closing at inlet and exhaust. Hence
when compared to four stroke engine, it has low fuel efficiency because scavenging effect.
But its construction and maintenance is easy, and costs less.
TABULAR COLUMN:
Sl.
No.
Speeder
pm
Spring
balance Wkg
Manometer Reading Time for
10 cc of
fuel
collected, t
sec
h1 cm h2 cm Hw =
(h1~h2)
PROCEDURE:
1. Fill up water in manometer to required level
2. Ensure petrol level in the fuel tank.
3. Ensure engine oil.
4. Put MCB of alternator to ON, switch of all load bank or bring aluminum conductor of
water loading rheostat above water level.
5. Add water
6. Switch ON ignition
7. Fix accelerator at some setting
8. Now kick start the engine and when it pickups speed adjust at 3000 rpm
9. at this no load note down manometer, speed ,temperature, voltage current and time for 10
cc of fuel consumption.
10. Repeat for different loads.
CALCULATIONS:
1. Area of Orifice A0 = π/4d02sq.cm (d0 is orifice diameter = mm)
2. Manometer Head Ha = ( h1-h2) x ρw/ ρa m (ρw=1000kg/m3)
1. ρa=1.2kg/m3
2. h1 and h2 in m
3. Mass flow rate of Air Ma in kg/hr
Ma= A0 x Cd x3600 x ρa x (2xgxHa)1/2 kg/hr
4.Total fuel consumption
TFC =10x3600x ρf /t1x1000 kg/hr
5. Brake Power BP in Kw
BP= v1/ngx1000 kW
6. Specific fuel consumption: SFC in Kg/Kw-hr
SFC = TFC/BP
7.Air Fuel ratio : A/F
A/F = Ma/TFC
GRAPHS: Plot curves of BP vs. TFC, SFC, A/F,
PRECAUTIONS:
1. Do not allow speed above 3000 rpm
2. Don’t increase load above 8 Amps
3. Don’t run engine without engine oil
4. Mix petrol and 2T oil at 1 liter.
LAB QUESTIONS:
1.What are the 4strokes of SI engines?
2.What is the working cycle of SI Engine?
3.List out the performance parameters?
4.Indicate the different types of loads?
5.Differentiate SFC and TFC?
VARIABLE COMPRESSION RATIO ENGINE TEST
RIG WITH DC GENERATOR
OBJECTIVE:
1. To demonstrate working of a variable compression ratio petrol engine
2. To conduct performance test on the VCR engine under different compression ratio from
2.5: 1 to 8: 1 & to draw the heat balance sheet
INSTRUMENTATION:
1. Digital RPM Indicator to measure the speed of the engine.
2. Digital temperature indicator to measure various temperatures.
3. Differential manometer to measure quantity of air sucked into cylinder.
4. BURETTE WITH MANIFOLD TO MEASURE THE RATE OF FUEL CONSUMED DURING TEST.
ENGINE SPECIFICATION:
ENGINE : GREAVES
BHP : 3 HP
RPM : 3000 RPM
FUEL : PETROL
No OF CYLINDERS : SINGLE
BORE : 70 mm
STROKE LENGTH : 66.7mm
STARTING : ROPE & SELF STARTING
WORKING CYCLE : FOUR STROKE
ENGINE COOLING : FORCED AIR COOLED
V C R HEAD COOLING : WATER COOLED
METHOD OF IGNITION : SPARK IGNITION
ORIFICE DIA. : 20mm
COMPRESSION RATIO : 2.5:1 to 8:1
SPARK PLUG : MICO W 160Z2
CARBURATOR : GREAVES 1320
GOVERNOR SYSTEM : MECHANICAL GOVERNOR
DC GENERATOR SPECIFICATION:
TYPE : SELF EXCITED, DC COMPOUND
GENERATOR.
POWER : 2.2kW
SPEED : 3000 RPM
RATED VOLTAGE : 220v DC
RESISTANCE LOAD BANK SPECIFICATION:
RATING : 2.5KW, 1Φ (SINGLE PHASE)
VARIATION : In 5 steps, by dc switches.
COOLING : Air cooled
OBSERVATIONS:
Indicated power : IP
Brake power : BP
Specific fuel consumption : Sfc
Actual volume : Va
Brake thermal efficiency : ŋbth
Indicated thermal efficiency : ηith
SWEPT VOLUME : VS
MECHANICAL EFFICIENCY : ΗMECH
Volumetric efficiency : ŋv
Frictional power : FP
DESCRIPTION:
This engine is a four stroke single cylinder, air-cooled, spark ignition type petrol engine. It is
coupled to a loading system which is in this case is a DC GENERATOR, having a resistive
load bank which will take load with the help of dc switches and also providing motoring test
facility to find out frictional power of the engine. The overhead cylinder head made of cast
iron is water cooled externally & has an encounter piston above the original piston in the
main engine. The counter piston is actuated by a screw rod mechanism to change the
clearance volume for different compression ratios.
AIR INTAKE MEASUREMENT:
The suction side of the engine is connected to an Air tank. The atmospheric air is drawn into
the engine cylinder through the air tank. The manometer is provided to measure the pressure
drop across an orifice provided in the intake pipe of the Air tank. This pressure drop is used
to calculate the volume of air drawn into the cylinder. (Orifice diameter is 20 mm)
FUEL MEASUREMENT:
The fuel is supplied to the engine from the main fuel tank through a graduated measuring fuel
gauge (Burette). By stopping the stop cock provided on the panel which stops the fuel to flow
from the tank, so that the fuel flows through the burette and the consumption can be
measured with respect to the time taken with the use of a stop watch.
LUBRICATION:
The engine is lubricated by mechanical lubrication.
Lubricating oil recommended – SAE- 40 OR Equivalent.
TEMPERATURE MEASUREMENT:
A digital temperature indicator with selector switch is provided on the panel to read the
temperature in degree centigrade, directly sensed by respective thermocouples located at
different places on the test rig.
THERMOCOUPLE DETAILS
T1= WATER INLET TEMPERATURE TO CALORI METER
T2 = WATER OUTLET TEMPERATURE FROM THE AUXILLARY
HEAD
T3 = EXHAUST GAS TEMPERATURE.
SPEED MEASUREMENT:
A DIGITAL SPEED INDICATOR IS PROVIDED ON THE PANEL WHICH WILL INDICATE THE
SPEED OF THE ENGINE IN TERMS OF RPM WITH THE HELP OF A FLUX CUT TYPE SENSOR
PROVIDED NEAR THE COUPLING.
WATER FLOW MEASUREMENT:
TWO ROTOMETERS ARE PROVIDED TO MEASURE THE QUANTITY OF WATER FLOW,
AMONG THEM ONE IS FOR THE ENGINE AUXILIARY HEAD AND ANOTHER ONE IS FOR
CALORIMETER. IT HAS AN ACRYLIC BODY AND HAS A TAPERED BORE GRADUATED IN
TERMS OF CC/SEC.
LOADING SYSTEM:
The engine shaft is directly coupled to the DC Generator which can be loaded by resistive
load bank. The load can be varied by switching ON the Load bank switches for various loads.
PROCEDURE:
1. Connect the instrumentation and DC supply power input plug to a 230v, 50 Hz AC single
phase AC supply. Now all the digital meters namely, RPM indicator, temperature indicator,
volt and ammeter display their respective readings.
2. Connect the inlet & outlet water connections and allow sufficient quantity of water to the
engine auxiliary head and to the exhaust gas calorie meter.
3. Fill up the petrol to the fuel tank mounted side of the panel.
4. Check the lubricating oil level in the oil sump.
5. Start the engine & allow the engine to stabilize the speed ie, 2800 or 3000 RPM by
adjusting the accelerator. (With the help of motorized facility)
6. Keep the selector switch in the generator direction.
7. Apply 500W
8. Note down all the required parameters mentioned below.
a. Speed of the engine in RPM.
b. Load from ammeter in amps.
c. Voltage from voltmeter in volts
d. Fuel consumption from the fuel rate indicator.
e. Quantity of airflow from the air rate indicator.
e. Different temperatures from Temperature indicator.
f. Spring Balance reading.
9. Load the engine step by step with the use of dc switches provided on the load bank
keeping
the speed constant such as,
a. 1000W
b. 1500W
c. 2000W
Note down the corresponding readings at each loads.
10. After taking all the readings remove the load by switching off the dc switches one by one
and also reduce the speed with help of accelerator arrangement.
11. Now shut-off the fuel supply and after about 2 minutes switch off the engine by using
STOP switch.
12. Then after about 10-15 minutes shut-off water supply.
13. Repeat the above procedure for different compression ratios.
14. To vary the compression ratio, rotate the indexing wheel to the required compression
ratio
shown on the graduation scale.
15. To change the compression ratio, switch off the engine and allow it to cool for some time
and then pull the lever at the rear end of the auxiliary head and then rotate the indexing
wheel and set the compression ratio to the required value with the use of a graduated
scale
provided.
ENGINE PERFORMANCE TEST:
1. BRAKE POWER
BP = V x I ……………Kw.
1000 x ŋgen
where, V = dc voltage in volts.
I = dc current in amps.
ŋgen = Generator efficiency = 80%
2 . MASS OF FUEL CONSUMED.
mfc= X x 0.82 x 3600 …..Kg/ hr
1000 x T
Where, X = burette reading in cc
0.82 = density of diesel in gram / cc
T = time taken in seconds.
3. SPECIFIC FUEL CONSUMPTION.
Sfc = mfc………..kg/kW hr
BP
4. SWEPT VOLUME
Vs = Π d2 X L X N X 60 ………. m3/hr
4 2
where, d = dia of bore = 70 mm
L = length of stroke = 66.7 mm
N = Speed of the engine in RPM.
5. VOLUMETRIC EFFICIENCY
ŋv = VA X 100 ……….%
VS
6. BRAKE THERMAL OR OVER ALL EFFICIENCY
ŋbth = BP X 3600 X 100 ……….%
mfc X cv
where , cv = calorific value of petrol = 43500 kJ / kg.
BP = Brake Power in kW.
TABULAR COLUMN FOR (PERFORMANCE TEST)
SL
NO.
LOAD
(W)
V
(volts)
I
(Amps)
N
(rpm)
H1
mm
H2
mm
t
sec
Rt1
1
2
3
4
5
6
TABULAR COLUMN FOR (TEMPERATURE)
SL
NO.
T1
0C
T2
0C
T3
0C
1
2
3
PERFORMANCE TEST RESULT @ DIFFERENT CRs
CR LOAD BP IP Mfc Sfc ηbth ηith ηv ηmech
Graphs to be plotted: 1) SFC v/s BP
2) ηbth v/s BP
3)ηmech v/s BP
4) ηvol v/s BP
RESULT:
HEAT BALANCE TEST ON SINGLE CYLINDER FOUR STROKE
COMPRESSION IGNITION ENGINE (KIRLOSKAR)
AIM: To perform a heat balance test on the given single cylinder four stroke C.I engine and to
prepare the heat balance sheet at various loads. APPARATUS REQUIRED: 1. C.I. Engine coupled with a dynamometer. 2. Air tank with air flow meter 3. Burette for fuel flow measurement 4. Rotometer for water flow measurement 5. Stop watch. 6. Thermometers. BRIEF THEORY OF THE EXPERIMENT:
From the law of conservation of energy, the total energy entering the engine in
various ways in a given time must be equal to the energy leaving the engine during the same
time, neglecting other form energy such as the enthalpy of air and fuel. The energy input to
the engine is essentially the heat released in the engine cylinder by the combustion of the
fuel. The heat input is partly converted into useful work output, partly carried away by
exhaust gases, partly carried away by cooling water circulated and the direct radiation to the
surroundings. In a heat balance test all these values are calculated and converted to
percentage with respect to the input and are presented in a chart at various loads.
EXPERIMENTAL SETUP:
The compact and simple engine test rig consisting of a four stroke single cylinder,
water cooled, constant speed diesel engine coupled to a rope brake dynamometer. The engine
is started by hand cranking using the handle by employing the decompression lever. Air from
atmosphere enters the inlet manifold through the air box. An orifice meter connected with an
inclined manometer is used for air flow measurement. A digital temperature indicator is used
to measure temperature of exhaust gas. A burette is connected with the fuel tank through a
control valve for fuel flow measurement. Provision is made to circulate water continuously
through the engine jacket. Rotometer is provided to measure the flow rate of cooling water.
Thermometers are provided to measure the temperature of cooling water passing through the
jacket.
STARTING THE ENGINE: 1. Keep the decompression lever in the vertical position 2. Insert the starting handle in the shaft and rotate it 3. When the flywheel picks up speed bring the decompression lever into horizontal position
and remove the handle immediately. 4. Now the engine will pick up.
STOPPING THE ENGINE:
1. Cut off the fuel supply by keeping the fuel governor lever in the other extreme
position. (For Diesel Engine)
PROCEDURE: 1. Start the engine at no load and allow idling for some time till the engine warm up. 2. at no load condition, note down the readings as per the observation table. 3. Note down the time taken for 10cc of fuel consumption using stopwatch and fuel
measuring burette. 4. After taking the readings open the fuel line to fill burette and supply fuel to run the engine
from the fuel tank again. 5. Now load the engine gradually to the desired valve. 6. Allow the engine to run at this load for some time in order to reach steady state condition. 7. Note down the readings as per the observation table. 8. Repeat the experiment for different loads. 9. Release the load slowly and stop the engine.
SPECIMEN CALCULATIONS:
1. Total fuel consumption = X/ (Time × specific gravity of fuel) ×3600/1000
kg/hr Where X –Quantity of fuel consumed in cc
Time –time taken for 10cc of fuel consumption
Specific gravity of fuel = 0.85 gm/cc
2. Heat input = (TFC × Calorific Value)/3600 Kw
3. B.P (Heat used for useful work output) =2NT/60000 Kw
4. % of heat used for useful work output % Q = (BP/HI) X100
5. Heat loss through cooling water =MW XCPW X (T2-T1) Kw
Where Mw =mass flow rate of water kg/sec
m= quantity of water collected
t2- time taken for m litres of water collection
Cpw –specific heat of water = 4.18 kJ/kg-K
T1 –inlet temperature of cooling water
T2 –outlet temperature of cooling water 6. % of heat loss through cooling water = Q(cooling water)/Heat Input X100
7. Heat loss through exhaust gases = Mg×CPg×(Tg-Ta) Kw
Where Mg = ma+ mf
8. Mass flow rate of air, ma = Manometer (H) x 0.8826 x10-3
x airρ(kg/s)
Density air= ofPatm/R xair,Tatmkg/m 3 ρ
Where Patm- atmospheric pressure (N/m2)
R –Gas constant, 287 J/kg-K
Tatm = atmospheric temperature Mass flow rate of fuel =TFC/3600 kg/sec
8. % of heat lost through exhaust gases = Q (exhaust gases) / Heat input x100
9. Unaccounted heat losses = Heat input-[Q(BP)+Q(cw) +Q(eg)]
PRECAUTIONS: 1. The engine should be checked for no load condition.
2. The cooling water inlet for engine should be opened.
3. The level of fuel in the fuel tank should be checked.
4. The lubrication oil level is to be checked before starting the engine.
RESULT: The heat balance test is conducted in the given diesel engine to draw up the heat balance
sheet at various loads.
Electrical Engine Fuel Air flow Energy Alternat Alternat
Temperatur
e
load speed in consum reading in meter or or
connected rpm ption for mm of reading time Voltage current Air Water Water Exhaust
in watts 10ml in water for no of in volts in amps inlet inlet outlet gas
sec revolutions T1 T2 T3 T4
PERFORMANCE TEST ON
RECIPROCATING AIR COMPRESSOR AIM:
To conduct a performance test on the two stage reciprocating air compressor and to
determine the volumetric efficiency and isothermal efficiency at various delivery pressures
APPARATUS REQUIRED:
1. Reciprocating air compressor test rig. 2. Manometer 3. Tachometer
SPECIFICATIONS:
Power : 5KW
Type : Two stage reciprocating
Cooling Medium: Air
3Capacity: 0.6 m/min
Maximum Pressure: 10 Bar
Speed : 950 rpm
BRIEF THEORY OF THE EXPERIMENT:
The two stage reciprocating compressor consists of a cylinder, piston, inlet and exit
valves which is powered by a motor. Air is sucked from atmosphere and compressed in the
first cylinder (Low pressure) and passed to the second cylinder (High pressure) through an
inter cooler. In the second cylinder, air is compressed to high pressure and stored in the air
tank.
During the downward motion of the piston, the pressure inside the cylinder drops
below the atmospheric pressure and the inlet valve is opened due to the pressure difference.
Air enters into the cylinder till the piston reaches the bottom dead center and as the piston
starts moving upwards, the inlet valve is closed and the pressure starts increasing
continuously until the pressure inside the cylinder above the pressure of the delivery side
which is connected to the receiver tank. Then the delivery valve opens and air is delivered to
the air tank till the TDC is reached. At the end of the delivery stroke a small volume of high
pressure air is left in the clearance volume. Air at high pressure in the clearance volume starts
expanding as the piston starts moving downwards up to the atmospheric pressure and falls
below as piston moves downward. Thus the cycle is repeated. The suction, compression and
delivery of air take place in two strokes / one revolution of the crank.
EXPERIMENTAL SETUP:
The two-stage air compressor consists of two driven by an AC motor. Air is first sucked into the
low pressure (LP) cylinder and it is compressed and delivered at some intermediate pressure. The
compressed air is then cooled in the intercooler and the same is then sucked by the high pressure (HP) cylinder.
Compressed air is the finally discharged to the receiver tank.
An orifice plate is mounted on one side of the air tank and which is connected with a
manometer for the measurement of air flow rate. One side of the air tank is attached with a
flexible rubber sheet to prevent damage due to pulsating air flow. A pressure gauge is
mounted on the air tank to measure the air tank pressure. The tank pressure can be regulated
by adjusting the delivery valve. A pressure switch is mounted on the air tank to switch off the
motor power supply automatically when the pressure inside the tank rises to the higher limit
and to avoid explosion.
PROCEDURE:
1. The manometer is checked for water level in the limbs. 2. The delivery valve in the receiver tank is closed. 3. The compressor is started and allowed to build up pressure in the receiver tank. 4. Open and adjust the outlet valve slowly to maintain the receiver tank pressure constant. 5. The dynamometer is adjusted so that the circular balance reads zero when the points at the
motor pedestal coincide. This can be done by operating the hand wheel. 6. Note down the readings as per the observation table.
7. Repeat the experiment for various delivery pressures. This can be done by closing the
delivery valve and running the compressor to build up higher pressure. Ensure the tank
pressure is maintained constant by adjusting the outlet valve before taking the readings. 8. Tabulate the values and calculate the volumetric efficiency and isothermal efficiency.
OBSERVATION TABLE:
Sl. Delivery pressure Manometer reading (mm) Speed Torque Kg-
No (kgf/cm2)
m
h1 h2 h1-h2 Motor Comp
SPECIMEN CALCULATION:
Hair= (H1-H2/100) x W/air m Where,
Hair = Air head causing the flow, m
h1, h2 = Manometer reading, mm
W = Density of water = 1000kg/m3
air = Density of air, kg/m3
air=Pa/RT kg/m3
Where,
Pa = Atmospheric pressure
R = Gas constant for air = 0.287 KJ/Kg.K
T = Room temperature K
Va =Cd × A× (2gHair) ½
m3/sec
Where,
Va = actual volume of air compressed m3/s
Cd = Coefficient of discharge = 0.64 A = area of orifice
d = diameter of orifice = 0.02m
V1 =Va /TRTP×TNTP m3/sec
Where,
V1 = actual volume of air compressed at NTP m3/s
Va = actual volume of air compressed m3/s
TNTP =273 K
TRTP = 273 + Room temperature in K
V2 = 2π×D×L×Nc/4×60 m3/s Where, V2 = theoretical volume of air compressed m3/s D = diameter of cylinder = 0.1m L= stoke length = 0.085m Nc = speed of the compressor
V. E. =V1/ V2×100% Where, VE = volumetric efficiency V1=actual volume of air compressed at NTP m3/s V2=Theoretical volume of air compressed m3/s
Iso.P. = ln(r)×Pa×Va/1000 Kw Where, Iso. P = isothermal power
r = Pa+Pg/Pa r= compression ratio Pa = atmospheric pressure N/m2 Pg = pressure in the tank N/m2
I.P = (35/30) ×2×πm×(T×9N.81)/60000×ηmotorKW Where, IP = input power Nm =motor speed rpm T = torque on the motor kg-m
ηmotor= 0.9
Iso. E =Iso.P./ I.P. ×100 Where, Iso. E = isothermal efficiency
Iso. P = isothermal power IP = input power.
GRAPH: 1. Gauge pressure Vs Volumetric efficiency 2. Gauge pressure Vs Isothermal efficiency
PRECAUTIONS: 1. The orifice should never be closed so as to prevent the manometer fluid being sucked in to
the tank. 2. At the end of the experiment the outlet valve of the reservoir should be opened as the
Compressor is to be started against at low pressures so as to prevent excess strain on the
piston.
RESULT: The performance test on the given air compressor test rig is conducted and the volumetric and
isothermal efficiencies are determined at various delivery pressures and the characteristic
curves are drawn.
REVIEW QUESTIONS:
1. What is a plenum chamber? Why it is used? 2. What is the purpose of an inter cooler in an air compressor? 3. What will happen if the compressor is allowed to run for a very long time by closing its
delivery valve? 4. How do you define volumetric efficiency and isothermal efficiency of a compressor? Plot
it n Vs gauge pressure. 5. What is the reason for increase in isothermal efficiency with gauge pressure? 6. What is the reason for decrease in volumetric efficiency with gauge pressure? 7. What is the actual thermodynamic process during compression? 8. Why there is a difference discharge equation for pin fin apparatus and air compressor? 9.
Convert 150 mm of Hg in to Pascal. 10. Plot PV=Constant and PV=Constant process on a PV diagram and show how will you
calculate the isothermal efficiency? 11. Why are fins provided around the LP cylinders and the connecting pipe? 12. What is the type of dynamometer used for measuring the motor output? Explain its
working principle. 13. What is the pressure control device incorporated in the setup and explain its use.
STUDY OF BOILER
AIM: To study the boiler, its classifications and its accessories
THEORY:
A boiler is an enclosed vessel that provides a means for combustion heat to be
transferred into water until it becomes heated water or steam. The hot water or steam under
pressure is then usable for transferring the heat to a process. Water is a useful and cheap
medium for transferring heat to a process. When water is boiled into steam its volume
increases about 1,600 times, producing a force that is almost as explosive as gunpowder
The process of heating a liquid until it reaches its gaseous state is called evaporation.
Boiler Systems:
The boiler system comprises of feed water system, steam system and fuel system.
The feed water system provides water to the boiler and regulates it automatically to meet
the steam demand. Various valves provide access for maintenance and repair.
The steam system collects and controls the steam produced in the boiler. Steam is
directed through a piping system to the point of use. Throughout the system, steam
pressure is regulated using valves and checked with steam pressure gauges.
The fuel system includes all equipment used to provide fuel to generate the necessary
heat. The equipment required in the fuel system depends on the type of fuel used in
the system.
A typical boiler room schematic is shown in Figure 2.2.
The water supplied to the boiler that is converted into steam is called feed water. The
two sources of feed water are: (1) Condensate or condensed steam returned from the
processes and (2) Makeup water (treated raw water) which must come from outside the
boiler room and plant processes. For higher boiler efficiencies, the feed water is preheated by
economizer, using the waste heat in the flue gas.
BOILER TYPES AND CLASSIFICATIONS There are virtually infinite numbers of boiler designs but generally they fit into one of two
categories:
Fire tube or “fire in tube” boilers; contain gasses from a furnace pass and around which the water
to be converted to steam circulates. Fire tube boilers, typically have a lower initial cost, are more fuel efficient and easier to
operate, but they are limited generally to capacities of 25 tons/hr and pressures of 17.5
kg/cm2.
Water tube or “water in tube” boilers reversed with in the which water passing
Through the tubes and the hot gasses passing outside the tubes (see figure 2.3). These boilers can be of single- or multiple-drum type. These boilers can be built to any
Steam capacities and pressures, and have higher efficiencies than fire tube boilers.
Packaged Boiler: The packaged boiler is so called because it comes as a complete
package. Once delivered to site, it requires only the steam, water pipe work, fuel supply and
electrical connections to be made for it to become operational. Package boilers are generally
of shell type with fire tube design so as to achieve high heat transfer rates by both radiation
and convection.
Stoker Fired Boiler:
Stokers are classified according to the method of feeding fuel to the furnace and by
the type of grate. The main classifications are: 1. Chain-grate or travelling-grate stoker 2. Spreader stoker Chain-Grate or Travelling-Grate Stoker Boiler
Coal is fed onto one end of a moving steel chain grate. As grate moves along the
length of the furnace, the coal burns before dropping off at the end as ash. Some degree of
skill is required, particularly when setting up the grate, air dampers and baffles, to ensure
clean combustion leaving minimum of unburnt carbon in the ash.
The coal-feed hopper runs along the entire coal-feed end of the furnace. A coal grate
is used to control the rate at which coal is fed into the furnace, and to control the thickness of
the coal bed and speed of the grate. Coal must be uniform in size, as large lumps will not
burn out completely by the time they reach the end of the grate. As the bed thickness
decreases from coal feed end to rear end, different amounts of air are required- more quantity
at coal-feed end and less at rear end (see Figure 2.5).
Spreader Stoker Boiler Spreader stokers (see figure 2.6) utilize a combination of suspension burning and grate
burning. The coal is continually fed into the furnace above a burning bed of coal. The coal
fines are burned in suspension; the larger particles fall to the grate, where they are burned in a
thin, fast burning coal bed. This method of firing provides good flexibility to meet load
fluctuations, since ignition is almost instantaneous when firing rate is increased. Hence, the
spreader stoker is favoured over other types of stokers in many industrial applications.
Pulverized Fuel Boiler
Most coal-fired power station boilers use pulverized coal, and many of the larger
industrial water-tube boilers also use this pulverized fuel. This technology is well developed,
and there are thousands of units around the world, accounting for well over 90% of coal-fired
capacity. The coal is ground (pulverised) to a fine powder, so that less than 2% is +300 micro
metre (μm)-75% is andbelow75 70microns, for a bituminous coal. It should be noted that too
fine a powder is wasteful of grinding mill power. On the other hand, too coarse a powder
does not burn completely in the combustion chamber and results in higher unburnt losses.
The pulverised coal is blown with part of the combustion air into the boiler plant through a
series of burner nozzles. Secondary and tertiary air may also be added. Combustion takes
place at temperatures from 1300-1700°C, depending largely on coal grade. Particle residence
time in the boiler is typically 2 to 5 seconds, and the particles must be small enough for
complete combustion to have taken place during this time. This system has many advantages
such as ability to fire varying quality of coal, quick responses to changes in load, use of high
pre-heat air temperatures etc.
One of the most popular systems for firing pulverized coal is the tangential firing
using four burners corner to corner to create a fireball at the center of the furnace (Fig 2.7)
FBC Boiler
When an evenly distributed air or gas is passed upward through a finely divided bed
of solid particles such as sand supported on a fine mesh, the particles are undisturbed at low
velocity. As air velocity is gradually increased, a stage is reached when the individual
particles are suspended in the air stream. Further, increase in velocity gives rise to bubble
formation, vigorous turbulence and rapid mixing and the bed is said to be fluidized. If the sand in a fluidized state is heated to the ignition temperature of the coal and the coal is
injected continuously in to the bed, the coal will burn rapidly, and the bed attains a uniform
temperature due to effective mixing. Proper air distribution is vital for maintaining uniform
fluidisation across the bed. Ash is disposed by dry and wet ash disposal systems.
Fluidised bed combustion has significant advantages over conventional firing systems and
offers multiple benefits namely fuel flexibility, reduced emission of noxious pollutants such
as SOx and NOx, compact boiler design and higher combustion efficiency.
BOILER FITTINGS AND ACCESSORIES •Safety valve: It is used to relieve pressure and prevent possible explosion of a boiler. •Water level indicators: They show the operator the level of fluid in the boiler, also known
as a sight glass, water gauge or water column is provided. •Bottom blow down valves: They provide a means for removing solid particulates that
condense and lie on the bottom of a boiler. As the name implies, this valve is usually located
directly on the bottom of the boiler, and is occasionally opened to use the pressure in the
boiler to push these particulates out. • Continuous blow down valve: This allows a small quantity of water to escape
continuously. Its purpose is to prevent the water in the boiler becoming saturated with
dissolved salts. Saturation would lead to foaming and cause water droplets to be carried over
with the steam - a condition known as priming. Blow down is also often used to monitor the
chemistry of the boiler water. •Flash Tank: High pressure blow down enters this vessel where the steam can 'flash' safely
and be used in a low-pressure system or be vented to atmosphere while the ambient pressures
blow down flows to drain. •Automatic Blowdown/Continuous Heat Recovery System: This system allows the boiler
to blowdown only when makeup water is flowing to the boiler, thereby transferring the
maximum amount of heat possible from the blowdown to the makeup water. No flash tank is
generally needed as the blowdown discharged is close to the temperature of the makeup
water. •Hand holes: They are steel plates installed in openings in "header" to allow for inspections
& installation of tubes and inspection of internal surfaces. •Steam drum internals, A series of screen, scrubber & cans (cyclone separators). •Low- water cutoff: It is a mechanical means (usually a float switch) that is used to turn off
the burner or shut off fuel to the boiler to prevent it from running once the water goes below a
certain point. If a boiler is "dry-fired" (burned without water in it) it can cause rupture or
catastrophic failure. •Surface blowdown line: It provides a means for removing foam or other lightweight non-
condensable substances that tend to float on top of the water inside the boiler.
•Circulating pump: It is designed to circulate water back to the boiler after it has expelled
some of its heat. •Feed water check valve or clack valve: A non-return stop valve in the feed water line. This
may be fitted to the side of the boiler, just below the water level, or to the top of the boiler.
•Top feed: A check valve (clack valve) in the feed water line, mounted on top of the boiler. It
is intended to reduce the nuisance of lime scale. It does not prevent lime scale formation but
causes the lime scale to be precipitated in a powdery form which is easily washed out of the
boiler. •Desuperheater tubes or bundles: A series of tubes or bundles of tubes in the water drum or
the steam drum designed to cool superheated steam. Thus is to supply auxiliary equipment
that doesn't need, or may be damaged by, dry steam. •Chemical injection line: A connection to add chemicals for controlling feed water pH.
CONTROLLING DRAFT:
Most boilers now depend on mechanical draft equipment rather than natural draft.
This is because natural draft is subject to outside air conditions and temperature of flue gases
leaving the furnace, as well as the chimney height. All these factors make proper draft hard to
attain and therefore make mechanical draft equipment much more economical. There are three types of mechanical draft: Induced draft: This is obtained one of three ways, the first being the "stack effect" of a
heated chimney, in which the flue gas is less dense than the ambient air surrounding the
boiler. The denser column of ambient air forces combustion air into and through the boiler.
The second method is through use of a steam jet. The steam jet oriented in the direction of
flue gas flow induces flue gasses into the stack and allows for a greater flue gas velocity
increasing the overall draft in the furnace. This method was common on steam driven
locomotives which could not have tall chimneys. The third method is by simply using an
induced draft fan (ID fan) which removes flue gases from the furnace and forces the exhaust
gas up the stack. Almost all induced draft furnaces operate with a slightly negative pressure.
Forced draft: Draft is obtained by forcing air into the furnace by means of a fan (FD fan)
and ductwork. Air is often passed through an air heater; which, as the name suggests, heats
the air going into the furnace in order to increase the overall efficiency of the boiler. Dampers
are used to control the quantity of air admitted to the furnace. Forced draft furnaces usually
have a positive pressure.
Balanced draft: Balanced draft is obtained through use of both induced and forced draft.
This is more common with larger boilers where the flue gases have to travel a long distance
through many boiler passes. The induced draft fan works in conjunction with the forced draft
fan allowing the furnace pressure to be maintained slightly below atmospheric.
Boiler Efficiency: Thermal efficiency of boiler is defined as the percentage of heat input that is effectively
utilized to generate steam. There are two methods of assessing boiler efficiency. 1) The Direct Method: Where the energy gain of the working fluid (water and steam) is
compared with the energy content of the boiler fuel. 2) The Indirect Method: Where the efficiency is the difference between the losses and the
energy input.
RESULT: The types of boilers and its accessories are studied.
REVIEW QUESTIONS:
1. What is the importance of draft in boilers? 2. Explain the principle of fire tube and water tube boilers? 3. Explain the principles of fluidized bed combustion and pulverized fuel combustion? 4. What is the difference between an economizer and an air pre heater? 5. Discuss the various types of heat losses in a boiler? 6. How do you measure boiler efficiency using direct method? 7. What do you understand by term evaporation ratio? 8. What is atomisation of fuel oil in combustion? 9. Discuss automatic blow down control system? 10. What is the function of de-aerator in boiler?
ECONOMICAL SPEED TEST (4-STROKE DIESEL ENGINE)
AIM: To conduct economical speed test on 4-Stroke diesel engine (Single cylinder)
THEORY:
The Test Ring consists of Four-Stroke Diesel Engine, to be tested for performance, is
connected to Rope Brake Drum with Spring Balance (Mechanical Dynamometer) with
Exhaust Gas Calorimeter. The arrangement is made for the following measurements of the
Set-up :
1) The Rate of Fuel Consumption is measured by using the pipette reading against the known
time.
2) Air Flow is measured by Manometer connected to Air Box.
3) The different mechanical loading is achieved by operating the spring balance of
Dynamometer in steps.
4) The different mechanical energy is measured by spring balance and radius of brake drum.
5) The Engine Speed (RPM) is measured by electronic digital RPM Counter.
6) Temperature at different points is measured by electronic digital Temperature Indicator.
7) Water Flow Rate through the engine & calorimeter is measured by Water meter.
The whole instrumentation is mounted on a self –contained unit ready for table operation.
PROCEDURE:
1. Check the diesel in the diesel tank.
2. Allow diesel, start the engine by using hand cranking.
3. The engine is set to the speed of 1500 RPM.
4. Apply load from the spring balance of dynamometer.
5. Allow some time so that the speed stabilizes.
6. Now take down spring balance readings.
7. Put tank valve in to pipette position and note down the time taken for particular quantity of
fuel consumed by the engine.
8. Note down the temperature readings at different points.
9. Note down the water readings.
10. Repeat the procedure (4) & (7) for different loads.
11. Tabulate the readings as shown in the enclosed list.
12. After the experiment is over, keep the diesel control valve at mains position.
OBSERVATIONS:
Engine Spring balance Readings Fuel pipette readings
Air flow Manometer readings in
mm
of water
Speed in RPM
F1 In Kgs
F2 In Kgs In ml
Time in Secs. H1 H2
CALCULATIONS
1. FUEL CONSUMPTION IN Kg/Hr
WF =Column (3a) of table readings / Column (3b) of table readings x 3.06
2. ENGINE OUT PUT” BHP”
BP= 2 N(F1 -F2)r/4500 KW
Where, N- Speed of engine in RPM
r- Radius of brake drum in mts =0.185 mts
F1&F2- Force indicated on spring balance in KGs
3. SPECIFIC FUEL CONSUMPTION (SFC):
SFC = WF/BHP =Kg/ BHP. Hr
4. FUEL HP(THERMAL HORSE POWER),
FHP= WF x CV x J/ 60 X 4500
Where, Cv = Calorific value of diesel= 10000 K.Cal /Kg
J= Mechanical equivalent of heat=427 kg.m / K.Cal
5. PERCENTAGE THERMAL EFFICIENCY. th
% η = BHP/ FHP x 100
6. AIR CONSUMPTION IN Kg/ Hr ‘Wa’
Wa = 0.6 x A0 x Va x 1.29 x 60 x 60
Where, Ao = Area of the orifice in m2 =/4 d
2
Where d= Dia. of the orifice in m = 0.015 mt
Va = (2g (hm/1000) x [(rw/ra) -1]) ½
Where g = 9.81 m/ sce2
hm = Manometer reading in mm (column 5)
ρw = Density of water = 1000 Kg/ m3
ρa = Density of air = 1.29 Kg/ m3
7. AIR TO FUEL CONSUMPTION RATIO.
Air to fuel consumption ratio =Wa/Wf
Sl.N Engine
Fuel
Consumed Air Consumed Air to Fuel
Engine
Specific fuel
Fuel Brake
output HP thermal
O RPM N Wf Kg/Hr Wa Kg/Hr RatioWa /Wf
consumption
SFC
BHP FHP efficiency
1
2
3
4
RESULT;
Economical speed test on 4-Stroke diesel engine (Single cylinder) is conducted. From
the graph economical speed of engine is---------------RPM @---------HP
DIS-ASSEMBLY AND ASSEMBLY OF AN ENGINE
AIM: To study the procedure for dis-assembly and assembly of a petrol engine by making a practical trail on it. INTRODUCTION: Due to use of engine continuously over period of time they may develop
certain troubles. Such as loss of efficiency noise irrational, fluctuations manufacturing of fuel
pump injector. As such there will be necessity of strip of all parts of the engine inspect then
for visual detects provide packing and scaling when ever required for this purpose
Disassembling and assembling of a petrol engine is done in a certain manner or correct
sequence.
The main parts of any engine are,
Cylinder Block:
1. It forms the basic frame work of the engine.
2. It houses the engine cylinders.
3. Serves as bearing or support and guides the piston reciprocating in it.
4. Block contains passengers for circulation of cooling water and lubricating oil.
There are two types of rings
a) Compression ring
b) Oil control ring
Connecting rod:
It connects the piston with the crank shaft thus facilitative the transmission of power combustion
chamber to the crank shaft it also converts the reciprocating motion of the piston into rotary
motion of crank shaft.
Fly wheel:
The fly wheel absorbs the energy power source and gives out this energy the other 3-strokes
keeping the crank shaft rotating at uniform speed through out.
Cam shaft: A shaft is responsible for opening the valves on addition the crank shaft operates. Cylinder head: 1. The head is a mono block casting.
2. It contains spark plug notes and cooling water Sackets, valve opening mechanism is mounted.
3. Complete valve opening mechanism is mounted on the head.
PROCEDURE:
The following procedure is to be followed while disassembling and Assembling of a
four-stroke cylinder petrol engine.
a) Study of the engine.
b) Plan the method for disassembling and keep the tools ready.
c) Remove the rocker armies ‘boxes
d) Remove the rocker armies and screw's to displace the covering plate on cylinder head.
e) Remove injector pipe end disconnect the injector.
f) Remove both the exhaust and inlet
g) Remove the push rod cover.
h) Remove the petrol tank
i) Remove fly wheel and fly wheel housing
j) Remove fuel pump and curb wetter
k) Remove the cylinder block
1) Remove connecting rod big ends and bearing
m) Remove side covers
n) Remove the cam shaft from the bearing.
o) Draw out all the lubricating oil from crank case
p) Remove the oil filter.
The following procedure is to be followed broadly in the gives sequence for assembling the Disassembled petrol engine
1) After proper cleaning and checking of all parts assembling is carried out 2) Position the piston along with rings to the small end of connecting rod, insert grudger pin
for fixing the piston to small end of the connecting rod. 3) Position the crankshaft into the bearing in the proper way 4) Fix the side covers and tighten properly. 5) Position the cylinder block clad fix it in a proper way 6) Fix the fuel pump and contributor 7) Position the fly wheel housing and fix the fly wheel correctly. 8) Fix both the inlet and the exhaust manifold. 9) Place the cylinder head block properly and fix the nuts properly. 10) Position the rocker worn and fix then correctly. 11) Tighten all the blocks with the help of nuts to make the engine fit. PRECAUTIONS: All the nuts and bolts removed during the disassembling should place
carefully. While dealing with rocker arms and crank shaft care must be taken. Use only the
tools while disassembling and assembling.
RESULT: Thus the procedure of the assembling & DISASSEMBLING of a four-stroke four-cylinder petrol engine is studied and recorde
EVALUATION OF ENGINE FRICTION BY CONDUCTING MORSE
ON 4-S MULTI CYLINDER PETROL ENGINE
AIM: to determine frictional power of four stroke three cylinder petrol engine.
INSTRUMENTATION:
1. Digital rpm indicator to measure the speed of the engine.
2. Digital temperature indicator to measure various temperatures.
3. Differential manometer to measure quantity of air sucked into cylinder.
4. Burette with manifold to measure the rate of fuel consumed during test.
ENGINE SPECIFICATION:
ENGINE : MARUTHI 800 ENGINE
BHP : 10 H.P
RPM : 1500 RPM
FUEL : PETROL
NO OF CYLINDERS : THREE
BORE : 70 MM
STROKE LENGTH : 66 MM
STARTING : SELF START
WORKING CYCLE : FOUR STROKE
METHOD OF COOLING : WATER COOLED
METHOD OF IGNITION : SPARK IGNITION
DESCRIPTION: the MARUTI 800 engine is a four stroke three cylinder, water – cooled,
spark ignition type petrol engine. it is coupled to a loading system which is in this case is a
hydraulic dynamometer.
FUEL MEASUREMENT:
The fuel is supplied to engine from the main fuel tank through a graduated measuring fuel
gauge (Burette) with 3 – way cock. To measure the fuel consumption of the engine, fill the
burette by opening the cock. By starting a stop clock, measure the time taken consume X cc
of fuel by the engine.
AIR INTAKE MEASUREMENT:
The suction of the engine is connected to an Air tank. The atmospheric air is drawn into the
engine cylinder through the air tank. The manometer is provided to measure the pressure drop
across an orifice provided in the intake pipe of the Air tank. This pressure drop is used to
calculate the volume of air drawn into the cylinder. (Orifice diameter is 20 mm)
LUBRICATION:-
The engine is lubricated by mechanical lubrication.
Lubricating oil recommended – SAE – 40 OR Equivalent.
TEMPERATURE MEASUREMENT:
A digital temperature indicator with selector switch is provided on the panel to
read the temperature in degree centigrade, directly sensed by respective
Thermocouples located at different places on the test rig.
ROTAMETER:
A rotameter is provided at the inlet of engine jacket to measure the quantity of water allowed
into the engine jacket. Valves are provided to regulate the flow rate of water flowing and that
can be directly read on the rotameter in cc/sec.
LOADING SYSTEM:
The engine shaft is directly coupled to the hydraulic dynamometer and is loaded by varying
the quantity of water allowed into the dynamometer at constant pressure head. By operating
the gate valve provided on the inlet line of the dynamometer,
