OBSERVATIONS:

Sl.No

Event Position with Respect to TDC/BDC

Circumferential Distance (dc)‘cm’

Subtended AngleӨ in deg

1 IVO

2 IVC

3 EVO

4 EVC

1

Ex. No.1

VALVE TIMING DIAGRAM OF A FOUR STROKE DIESEL ENGINE

Aim:

To determine the opening and closing of the inlet and exhaust valves in a four stroke diesel engine and draw the valve timing diagram.

Apparatus / Equipments / Instruments Required:

1. Four stroke diesel engine test Rig2. Chalk3. Measuring tape4. String

Description:

The Four stroke engine has two valves namely inlet valve and exhaust valve. The cycle of operation is completed in two revolutions of the crank shaft.

During suction stroke, only air is charged into the cylinder. Theoritically this stroke is executed for 180 of crank shaft rotation. In actual practice the suction stroke starts before TDC and continues few degrees of crank rotation after BDC.

During compression stroke, the air is compressed. Theoritically this stroke should be executed for 1800 of crank shaft rotation. Before few degrees from TDC the fuel injection beings and ceases at few degrees after TDC with simultaneous auto ignition.

During power stroke, very high pressure developed by the combustion of fuel pushes the piston at fast rate, both suction and exhaust valves remain closed.

During exhaust stroke, the exhaust valves remain closed, gases are left out of the engine cylinder. The actual exhaust stroke starts before the BDC and continues a few degrees after TDC.

Procedure:

The inlet and exhaust valves are identified. The direction of rotation of the fly wheel has to be ascertained by observing the

correct sequence of opening and closing of valves. The fixed reference point is selected near the fly wheel periphery. The circumference of flywheel is measured using a string and tape.

2

The piston is moved to the top position by rotating the flywheel in the correct direction (clockwise) and a marking is made on the fly wheel against a reference point. This is the top dead center (TDC).

Another mark is made on the flywheel at 1800 from the TDC and this is the bottom dead center (BDC)

The fly wheel is rotated slowly in the same direction and the opening and closing of the inlet valve are marked on the fly wheel as IVO and IVC.

The timing at spark occurrence is also measured by looking into the opening of Cylinder block.

Similarly the opening and closing of the exhaust valve are also marked on the flywheel as EVO and EVC.

Circumferential distances between the various markings are measured with respect to the nearest dead center and the lengths are converted into suitable angle (Ө) and tabulated.

The valve timing diagram is drawn. The duration in degrees for which both the valves remain open is noted as the

angle of valves overlap.

Result:

Angle of valve

IVO –

IVC –

EVO –

EVC –

Thus the valve timing diagram of the given four stroke diesel engine is drawn.

3

OBSERVATIONS:

Circumference of Brake drum = πD = ________ m; D = _______m

Circumference of Rope drum = πd = ________ m; d = _________m

Mean effective Radius of brake drum (Rm) = _________m

TABULATION:

Sl. no

Crank shaft speed range (rpm)

RetardationTime with no load(sec)

Load (kg)

W-S(N)

RetardationTime with load(sec)

Braking Torque(Tb)N-m

Brake Power

Frictional Power

ήmech

4

Ex.no.2

Determination of mechanical efficiency by retardation test

Aim:

To conduct the retardation test on a single cylinder diesel engine and to determine the frictional power and thereby the mechanical efficiency.

Apparatus / Equipments / Instruments Required:

1. Diesel Engine Test Rig2. Stop Watch3. Measuring Tape4. Tachometer

Engine Details:

Type : Reciprocating Engine

Cooling : Water cooling

Rated power : 6Hp

Rated Speed : 750 rpm

Type of Loading : Rope brake drawn dynamometer (mechanical loading)

Fuel specifications:

Fuel : High speed diesel (HSD)

Calorific value : 43,500 KJ/Kg

Density of fuel q : 0.86 g/cc

Procedure:

Calculate Wmax

Check the engine for no load, coolant supply, fuel levels. Start engine, allow it to run for 3 minutes. Adjust fuel rack to obtain 1500 rpm. Cut off fuel supply by pulling fuel rack level and simultaneously note down time

taken for a fall in speed of 200 rpm. Soon after speed falls by rpm restore fuel supply immediately so that engine does not stop.

Repeat step 5 for a fall in speed of 400, 600 and 800 rpm. Now apply ½ Wmax gradually.

5

Repeat steps 5 and 6. Remove load gradually, run engine for 3 minutes, stop the engine by cutting of

fuel supply and close coolant supply.

Formulae:

Braking Torque (Tb) = (W-S) X Rm

Brake power (BP) = 2 πNT b

60 X 1000

Frictional Torque (Tf) = Tb X t 2

t 1−t 2

Frictional Power (Fp) = 2πNT f

60 X 1000

Indicated Power (Ip) = BP + FP

Mechanical Efficiency (ηmech) = BPIP X 100

Result:

Thus the Retardation test on single cylinder diesel engine is conducted and friction power and mechanical efficiency are calculated.

W-S (N) ηmech

6

TABULATION:

Sl.no Temperature 0C Observation

7

Ex.no.3

Testing of Fuels – Open Cup Apparatus

Aim:

To determine the flash point and fire point of the given sample of oil using Cleveland open cup apparatus.

Principle:

Mineral Oil when heated sufficiently to high temperature decomposes chemically to hydrocarbons chemically breakup into volatile combustible gases Flash point is the lowes temperature at which the decomposition of oil becomes demo stable. This is the formation of compressible and slightly explosive gas mixture before the surface of the oil. Fire point or the burning point is the lowest temperature at which the production of combustible gases from the oil is enough to maintain steady state after ignition.

Apparatus Required:

(1) Electric Heater(2) Rheostat(3) Thermostat

Procedure: The open cup is filled with the given sample oil up to the standard filling mark in

the cup. The thermometer is held in the oil in such a way that it does not touch the metallic

part. The sample of oil is heated so that it gives on vapour. At the testing time the test flames is applied by heating short distance over the

surface of oil and watched for flickering sound. The minimum temperature at which a momentary flash is obtained is called flash

point. Heating is continued after obtaining the flash point. The lowest temperature at

which the ignited vapour continues to burn is called fire point. Note the flash point and fire point of the given oil in a separate tabular column.

Result:Thus the flash point and fire point of given sample oil are found out as follows:

Sample Oil

Flash point Fire point

8

Sl.No Piston movement direction

Event Position with respect to TDC/BDC

Cirucmferential Distance (Dc) in cm

Subtended Angle (Ө) in deg

9

Ex.no.4

PORT TIMING OF A TWO STROKE PETROL ENGINE

Aim:

To draw the port timing diagram of a two stroke engine.

Apparatus Required:

1. 2-stroke cut section2. Measuring tape3. Chalk4. String

Procedure:

The Circumference of a flywheel is measured using the tape. Inlet, Exhaust and transfer ports are identified. The direction of rotation of flywheel is ascertained. The TDC and BDC are marked on flywheel. The opening and closing of all the ports are marked on flywheel. The timing at spark occurrence is also measured by looking into the opening of CBG

points. The PTD is drawn from the angles calculated.

Formula:

Ө = 360 X Dc

2 πR

Where,Ө – Subtended angle in degreeDc – Circumferential Distance in cm2πR – Circumference of flywheel in cm

Result:The point timing diagram of the given two stroke petrol engine is drawn.IPC =IPO =EPO =TPD =TPC =EPC =

10

OBSERVATION:T1 – Room temperatureT2 – Temperature of Water inlet temperatureT3 – Temperature of Water Outlet temperatureT4 – Temperature of Water outlet after calorimeter T5 – Temperature of Exhaust gas before calorimeterT6 – Temperature of Exhaust gas after calorimeter

Sl no

Speed Load Time for 10cc of fuel

Time for ‘x’ litres of water

TFC T1 T2 T3 T4 T5 T6

Manometer readings

h1 h2 h3

11

Ex.no.5HEAT BALANCE TEST ON DIESEL ENGINE

Aim:To prepare a heat balance sheet and to draw the heat balance chart for the given diesel

engine by performing heat balance test on the engine using air flow.

Apparatus Required:1. Diesel Engine2. Stop Watch3. Tachometer

Procedure: Before starting the engine, keep the fuel cut off switch in ON position. Start the engine Allow the engine to run at no load for about 10minutes to warm up and to attain steady

state condition, hence bring the engine to its rated speed. Distribute the load equal so as to get at least 3 trial runs during the test from no load to

full load. At no load the following observations are to be taken.

a. The speed of the engine by means of Tachometer.b. The time taken for every 10cc of fuel flow.c. The rate of flow of cooling water using water flow meter and stop watch.d. The temperature of the exhaust flue gas.e. ‘U’ tube manometer reading in terms of height of water column.f. Repeat the same procedure at different load.g. Be sure to allow sufficient time for the establishment of a steady state before taking a

new set of readings.h. Remove the load from the engine and stop the engine.

Formula:

(1) TFC = kg/secXtXSpecific gravity of petrol

1000Where,

X – consumption of petrol in ml.t- time taken for ‘X’ ml of petrol consumption.

(2) Heat input = TFC X Cv of petrol

(3) Heat equivalent to BP = 2πN (W−S)R X 9.81

60 X1000 X 3600KJ/hr

Where,N – Speed in Rpm

12

W – Load in kgS – Spring balance readingR - Radius of brake drum in ‘m’

(4) Heat Carried away by cooling water = xt X

360010

X Cpw (T3 –T2) KW

Where,x- litres of watert- time taken for ‘x’ litres of waterCpw – Specific heat of water to the engine.T2 – Inlet temperature of water to the engineT3 – Outlet temperature of water from the engine

.(5) Heat carried away by exhaust gases = mCpt(t3 – t2) KW

Cpt – Specific heat of flue gasest1- Exhaust gas inlet temperature to the calorimeter.t2- Exhaust gas out temperature from the engine.

(6) m- mass flow rate of air X flow rate of fuel (TFC) = ρair X Cd X a X V kg/secwhere, Cd = 0.64

a = area of orifice

V = √2ghm

.hd = manometer difference

.hm = hd

ρw

ρa

(7) Friction Power = From graph plotted between BP Vs TFC

(8) % of heat equivalent to break power = heat equivalent of BP X 100

heat input

(9) % of heat carried by cooling water = heat carried by coolingwater X100

heat input

(10) % of heat carried by exhaust gases = heat carried by exhaust gases X 100

heat input

13

Speed Condition of working of Engine

Load ( Kg)

Brake Power (KW)

Indicated Power (KW)

Frictional Power (KW)

Mechanical Efficiency (%)

TABULATION:

14

Ex.no.6Morse Test on Multi Cylinder Petrol Engine

Aim:To perform the Morse test on the given multi cylinder petrol engine and to determine the

efficiency at the given load.

Equipment / Accessories Required:1. Multi Cylinder Petrol Engine Test Rig2. Tachometer3. Stop watch

Procedure: Before starting the engine keep the fuel cut off level in ON position. Start the engine using starter motor. Allow the engine to run at no load for about 10 minutes to warm up and attain steady

state condition. Load the engine to the required level. When the engine is loaded to the required load adjust the throttle to maintain the speed of

the engine at its rated rpm. Allow few minutes for the engine attains steady state condition and note down the load

when all the cylinders are developing power. Cut off cylinder no.1 by lifting the cutoff switch no.1 Bring the engine again to rated speed by adjusting the load on brake drum and not by

adjusting the load on brake drum and not by adjusting the throttle and note down the corresponding load on the engine.

Similarly cut off the cylinder.2,3,4 and repeat the above procedure to find the load on the engine for cylinder.

Remove the load from the engine and stop the engine by switching off the ignition switch.

Formulae:Indicated power when:

Cylinder 1 is cut off IP1 = BPn - BP1 KW Cylinder 2 is cut off IP2 = BPn - BP2 KW Cylinder 3 is cut off IP3 = BPn - BP3 KW Cylinder 4 is cut off IP4 = BPn - BP4 KW Total Indicated Power = IP1 +IP2+IP3+IP4 KW

Total Frictional power loss when all = IPn + BPn KWcylinders are working (FPn)

15

Mechanical efficiency (ήmech) = BPn X 100

IPn

Result:Thus the Morse test on Multi Cylinder petrol Engine is done the

following observations are made.

16