EXPERIMENT NO.1

Aim: - To study refrigeration cycle, determine of coefficient of performance of cycle & determine of tonnage capacity of refrigeration unit.

Apparatus used: -Refrigeration test Rig consists of (Compressor (rotary), Air cooler

condenser, Capillary tube, Evaporator coil, voltmeter, current meter, voltmeter, energy

meter, Thermocouple pressure gauge, vacuum gauge, and freezer

Description of the Test Rig:- The experimental refrigeration cycle test rig consist of a compressor unit, condenser,

evaporator, cooling chamber, controlling devices and measuring instruments those are fitted

on a stand and a control panel. The apparatus is fabricated in such a way; to refrigeration

system hermetically sealed compressor is fitted on stand with the help of flexible foundation

bolts to minimize vibrations. Electric power input to the compressor is given through

thermostatic switch.

Temperature sensor details: -

1. T1 = Temperature Sensor : Fixed at Compressor Discharge Line 2. T2 = Temperature Sensor : Fixed after Condenser 3. T3 = Temperature Sensor : Fixed after Capillary Tube

4. T4 = Temperature Sensor : Inside freezer 5. T5 = Temperature Sensor: Fixed at Compressor Suction Line.

Theory: - The coefficient of performance of refrigeration plant is given by the ratio of heat absorbed,

by the refrigerant when passing through the evaporator or the system, to the working input to

the compressor to compress the refrigeration.

Co-efficient of Performance = Heat removed by refrigerant / Power input

Cop plant = m Cp T / K. Wh

Where m = mass of water kept in cooling chamber Cp = specific heat of water = 4.18 Kj /Kg K T = temperature of cooling water Kwh = 1000 x V.I x 60 x 60 KJ = V.I x KJ = V.I x 3600 KJ KWH = reading of energy meter.

Co-efficient of refrigeration cycle is given by the ratio of net refrigeration effect to the

power required to run the compressor.

3

COP (cycle) Net refrigerant effect in unit time / Power input in unit

time = m Cp T / KwH Where

(Q), = mass flow rate of the refrigerant m3 / sec

Cp= Specific heat of refrigerant

T = Temperature difference (T1-T3)

KWH = Kilowatt hours energy meter reading.

The co-efficient of performance of a refrigeration system is given by the ratio of heat absorb,

to the work input.

COP = Heat removed by refrigerant / Power input

= m x Cp T / K.Wh

Where, m = mass of water kept in cooling chamber Cp = specific heat of water = 4.18 Kj /Kg K T= temperature of cooling water Kwh = power consumed by the compressor in unit time.

Tonnage capacity:

The capacity of a refrigeration machine is the refrigeration effect in a given time from a

body. This capacity of machine is given by standard commercial ton of refrigeration. This is

called as refrigerating effect i.e. melting of 1 ton of ice at 0°C in 24 hours.

TR= 336 x 1000 / 24 x 60 x 60 = 3.88 Kj / sec. Tonnage capacity of the machine = Net refrigerating effect of machine / 3.88

= m x Cp T / 3.88

Procedure: Switch on the compressor and let it run for considerable time. Say for automatic cut off by thermostatic switch at normal position. Fill a measured quantity of water in ice cane (100 gm) and put it into cooling chamber. Measure initial temperature of water before putting into

cooling chamber by noting the value of T4 as T4i note down the energy meter reading. Wait

till compressor starts. Compressor shall be started automatically as and when temperature of cooling chamber falls up to adjusted temperature. After starting the compressor note down the temperature T4 at the interval of every 15

minutes and note it down as T4C.

4

Note down the power consumed by compressor till ice forms i.e. temperature T4 should

reach O°C. At 0°C of ice cane note down all the temperature i.e. T1, T2, T3, T4 and T5.

Also note down the suction and discharge pressure by the respective gauges. Note down

the flow rate of refrigerant by rotometer.

Hence Refrigeration effect TR = 336 x 1000 / 24 x 14000 KJ / hour

Where latent heat of fusion of ice = 336 KJ / kg.

Tonnage capacity of the plant

= Net refrigerant effect of plant / 14000 KJ / hour = m x Cp T / 14000 Where, m = mass of water kept in cooling chamber

Cp = initial and final heat of water = 4.18

T = initial temp. Tc = final temperature water T1- T2

T1 = initial temperature of water.

TC = final temperature of water

Tonnage capacity of cycle

= Net refrigerating effect produced by refrigerant / 14000 Kj /h = m x Cp T / 14000 tones

where m = mass flow rate of refrigerant Cp= Specific heat of refrigerant

T = Temperature of refrigerant at discharge and suction = T1, T5

Observation Table

Sr no. Energy meter reading Mass of Temperature of chilling T1 T2 T3 T5

water water initial final T Initial Final C = (a-

(a) (b) b)

Calculation:

1- COP (plant) = m x Cp T / KWH

Where m = Mass of water kept in ice cane (kg)

T = T4i – T4C KWH = Total energy meter reading (Final value – initial value of energy meter.)

Sample Calculation

COP = m. Cp T / KWh = (20 x 4.187 x 12) /( 245 x 3.9)

Tonnage capacity = COP / 3.88 TR Cp= Specific heat of water = 4.18

Result: -

Viva Question: -

1. Mention the advantages of vapour compression refrigeration system? 2. Describe the mechanism of a simple vapour compression refrigeration system? 3. What is sub cooling? 4. What is superheating?

5. Why is superheating considered to be good in certain cases?

EXPERIMENT NO. 2

4-STROKE CYCLE PETROL ENGINE

Aim : To Study of 4-stroke cycle petrol engine

Apparatus required : 4-stroke cycle petrol engine model

Theory All operations are carried out in 4-stroke of piston i.e. two revolutions of crank, therefore engine is called

4-stroke cycle engine.

Internal combustion engine: - When the combustion of fuel takes place inside the cylinder then

engine is known as I.C. Engine.

Classification of I.C. engine:-

(1) According to the fuel used in cycle:-

(a) Gas engine (b) Petrol engine (c) Diesel engine (d) Multi-fuel engine

(2) According to piston strokes in the working cycle:-

(a) Four strokes cycle engine (b) Two strokes cycle engine

(3) According to method of ignition:-

(a) Spark ignition (b) Compression ignition

(4) According to fuel feeding system:-

(a) Carburetor engine (b) Engine with fuel injection

(5) According to charge feeding system:-

(a) Naturally aspired engine (b) Supercharged engine

(6) According to the cooling system:-

(a) Air-cooled engine (b) Water cooled engine (c) Oil cooled engine

(7) According to no. of cylinder

(a) Single cylinder engine (b) Multi-cylinder engine

(8) According to speed of engine:-

(a) Low speed engine (b) Medium speed engine (c) High speed engine

(9) According to position of engine

(a) In line engine (Horizontal &Vertical engine) (b) V engine (c) Radial engine

(10) According to cycle of operation:-

(a) Otto-cycle engine (b) Diesel engine (c) Dual cycle engine

(11) According to method of governing:-

(a) Quality governed engine (b) Quantity governed engine

(12) According to valve arrangement:-

(a)Overhead valve engine (b) L-head type engine (c) T-head type engine (d) F-head type engine

COMPONENTS OF I.C. ENGINE:-

The essential parts of Otto-cycle & Diesel cycle engines are the same.

Cylinder: - It is the heart of the engine. The piston reciprocates in the cylinder. It has to withstand very

high pressure & temperature therefore if material should have high strength. Generally it is made from

cast iron. It is provided with cylinder liner on inner side & cooling arrangement on its outer side. The

upper end consists of a combustion as clearance space in which the ignition & combustion of charge takes

place. Generally Cylinder is cast in single piece.

Cylinder head: - The top cover o Define Clearance volume of cylinder towards TDC is called cylinder

head. It houses the spark plug in petrol engines & fuel injector in diesel engines.

Piston: - It is reciprocating member of the engine. It reciprocates in the cylinder. It is made of usually

cast iron / aluminum alloys. It’s All operations are carried out in 4-stroke of piston i.e. two revolutions of

crank, therefore engine is called 4-s cycle engine top surface is called piston crown & bottom surface is

piston skirt. Its top surface is made flat for four stroke engines & deflected for two stroke engines. Its

function is to compress the charge during compression stroke & to transmit the force to the connecting

rod.

Piston rings: - Piston rings provide a good sealing fit between piston & cylinder. The two or three piston

rings are provided on piston. The rings are usually made of cast iron having fire grade & high elasticity

which is not affected by the working heat. These are housed in the air-circumferential grooves provided

on the outer surface of the piston. The function of these rings to give gas tight fitting between the piston

& the cylinder prevents the leakage of high pressure gases.

Crank: - It is a rotating member. It makes circular motion in the crank case (its housing). Its one end

connected with shaft called Crank-shaft & other end is connected with Connecting rod.

Crank case: - It is housing of crank & body of engine to which cylinder & other engine parts are

fastened. It also acts as a ground for lubricating oil.

Crank shaft: - It is a rotating member which connects crank & the power developed by engine is

transmitted outside through the shaft .It is made of medium carbon or alloy steels.

Connecting rod: - It connects piston? & crank. It transmits power developed on the piston to crank shaft

through crank. It is usually made of medium carbon steel.

Cooling fins or cooling water jackets: - During combustion engine releases a large amount of heat thus

engine parts may be subjected to a temperature at which engine parts may not sustain their mechanical

properties such as Hardness etc. In order to keep the engine parts within safe temperature limits, the

cylinder & cylinder head are provided with cooling arrangement. The cooling fins are provided on light

duty engines while cooling water jackets are provided on medium & heavy duty engines.

Cam shaft: - It is provided on four stroke engines. It carries two cams, for controlling the opening &

closing of inlet & exhaust valves.

Inlet valve: - This valve controls the admission of charge into the engine into the engine during the

suction stroke.

Exhaust valve: - The removal of exhaust gases after doing work on piston is controlled by exhaust valve.

All operations are carried out in 4-stroke of piston i.e. two revolutions of crank, therefore engine is called

4-s cycle engine

Inlet manifold: - It is the passage which carries the charge from carburetor to engine.

Exhaust manifold: - It is the passage which carries the exhaust gases from the exhaust valve to

atmosphere.

Spark plug: - It is provided on petrol engines. It produces a high intensity spark which initiates the

combustion process of the charge.

Fuel injector: - It is provided on diesel engines. The Diesel fuel is injected in the cylinder at the end of

compression through fuel in All operations are carried out in 4-stroke of piston i.e. two revolutions of

crank, therefore engine is called 4-s cycle engine ejector under very high pressure.

Carburetor: - It is provided with petrol engine for Preparation of homogeneous mixture of air & fuel

(Petrol). This mixture as a charge is supplied to engine Cylinder through suction valve or port.

Fuel pump:-It is provided with diesel engine. The diesel is taken from fuel tank & its pressure is raised in

the fuel pump & then it is delivered to fuel injector.

Flywheel: - It is mounted on the crank shaft. It is made of Cast iron. It stores energy in form of inertia,

when energy is in excess & it gives back energy when it is in deficit i.e. it minimizes the speed

fluctuations on the engine

Construction: - It consists of cylinder, cylinder head attached with spark plug, piston attached with

piston rings, connecting rod, crank, crank shaft etc. In 4-stroke cycle engine valves are used instead of

ports. These are suction/inlet valve & exhaust/outlet valve. These valves are operated by cams attached on

separate shaft called cam shaft. It is rotated at half of the speed of crank shaft.

WORKING:-

The four stroke-cycles define Clearance volume. refers to its use in petrol engines, gas engines, light, oil

engine and heavy oil engines in which the mixture of air fuel are drawn in the engine cylinder. Since

ignition in these engines is due to a spark, therefore they are also called spark ignition engine as shown in

Fig (a)

SUCTION STROKE:

All operations are carried out in 4-stroke of piston i.e. two revolutions of crank, therefore engine is

called 4-s cycle engine In this Stroke the inlet valve opens and proportionate fuel-air mixture is

sucked in the engine cylinder. Thus the piston moves from top dead centre (T.D.C.) to bottom dead

centre (B.D.C.). The exhaust valve remains closed throughout the stroke.

COMPRESSION STROKE:

In this stroke both the inlet and exhaust valves remain closed during the stroke. The piston moves

towards (T.D.C.) and compresses the enclosed fuel-air mixture drawn. Just before the end of this

stroke the operating plug initiates a spark which ignites the mixture and combustion takes place at

constant pressure.

POWER STROKE OR EXPANSION STROKE:

In this stroke both the valves remain closed during the start of this stroke but when the piston just

reaches the B.D.C. the exhaust valve opens. When the mixture is ignited by the spark plug the hot

gases are produced which drive or throw the piston from T.D.C. to B.D.C. and thus the work is

obtained in this stroke.

EXHAUST STROKE:

This is the last stroke of the cycle. Here the gases from which the work has been collected become

useless after the completion of the expansion stroke and are made to escape through exhaust valve to

the atmosphere. This removal of gas is accomplished during this stroke. The piston moves from

B.D.C. to T.D.C. and the exhaust gases are driven out of the engine cylinder. The working of these

strokes is represented by P-V diagram as shown in Figure

F

i

g

u

r

e

7

(

a

)

4-stroke cycle petrol engine

Applications: - These engines are mostly used on automobiles. These engines are used in motorcycle,

cars, buses, trucks, aero planes, small pumping sets, electric generators etc. Now a day’s 4-stroke cycle

petrol engines have been replaced by 4-stroke cycle diesel engines for most of the applications.

Result/ conclusions

The above Experiment Concluded that 4 Stroke Cycle Petrol Engine required low maintenance

& having Higher Efficiency as compare to Diesel Engine.

Viva questions

1. Define Clearance volume.

2. What is bore?

3. What is mean effective pressure

4. What is the function of Fly wheel?

5. Explain the function of power stroke in 4-stroke petrol engine cycle.

EXPERIMENT NO. 3

4-STROKE CYCLE DIESEL ENGINE

Aim : To Study of 4-stroke cycle diesel engine

Apparatus required : 4-stroke cycle diesel engine model

Theory

All operations are carried out in 4-stroke of piston i.e. two revolutions of crank, therefore engine

is called 4-s cycle engine.

INTERNAL COMBUSTION ENGINE: - When the combustion of fuel takes place inside the

cylinder then engine is known as I.C. Engine.

CLASSIFICATION OF I.C. ENGINE:-

(1) According to the fuel used in cycle:-

(a) Gas engine (b) Petrol engine (c) Diesel engine (d) Multi-fuel engine

(2) According to piston strokes in the working cycle:-

(a) Four strokes cycle engine (b) Two strokes cycle engine

(3) According to method of ignition:-

(a) Spark ignition (b) Compression ignition

(4) According to fuel feeding system:-

(a) Carbureted engine (b) Engine with fuel injection

(5) According to charge feeding system:-

(a) Naturally aspired engine (b) Supercharged engine

(6) According to the cooling system:-

(a) Air-cooled engine (b) Water cooled engine (c) Oil cooled engine

(7) According to no. of cylinder:-

(a) Single cylinder engine (b) Multi-cylinder engine

(8) According to speed of engine:-

(a) Low speed engine (b) Medium speed engine (c) High speed engine

(9) According to position of engine:-

(a) Inline engine (Horizontal &Vertical engine) (b) V engine (c) Radial engine

(10) According to cycle of operation:-

(a) Otto-cycle engine (b) Diesel cycle engine (c) Dual cycle engine

(11) According to method of governing:-

(a) Quality governed engine (b) Quantity governed engine

(12) According to valve arrangement:-

(a)Overhead valve engine (b) L-head type engine (c) T-head type engine (d) F-head type

engine

Components of I.C. engine:-when the combustion of fuel takes place inside the cylinder then

engine is known as I.C. engine.

The essential parts of Otto-cycle & Diesel cycle engines are the same.

Cylinder: - It is the heart of the engine. The piston reciprocates in the cylinder. It has to

withstand very high pressure & temperature therefore if material should have high strength.

Generally it is made from cast iron. It is provided with cylinder liner on inner side & cooling

arrangement on its outer side. The upper end consists of a combustion as clearance space in

which the ignition & combustion of charge takes place. Generally Cylinder is cast in single

piece.

Cylinder head: - The top cover of cylinder towards TDC is called cylinder head. It houses the

spark plug in petrol engines & fuel injector in diesel engines.

Piston: - It is reciprocating member of the engine. It reciprocates in the cylinder. It is made of

usually cast iron / aluminum alloys. Its top surface is called piston crown & bottom surface is

piston skirt. Its top surface is made flat for four stroke engines & deflected for two stroke

engines. Its function is to compress the charge during compression stroke & to transmit the force

to the connecting rod.

Piston rings: - Piston rings provide a good sealing fit between piston & cylinder. The two or

three piston rings are provided on piston. The rings are usually made of cast iron having fire

grade & high elasticity which is not affected by the working heat. These are housed in the air-

circumferential grooves provided on the outer surface of the piston. The function of these rings

to give gas tight fitting between the piston & the cylinder prevents the leakage of high pressure

gases.

Crank: - It is a rotating member. It makes circular motion in the crank case (its housing). Its one

end connected with shaft called Crank-shaft & other end is connected with Connecting rod.

Crank case: - It is housing of crank & body of engine to which cylinder & other engine parts are

fastened. It also acts as a ground for lubricating oil

Crank shaft: - It is a rotating member which connects crank & the power developed by engine

is transmitted outside through the shaft .It is made of medium carbon or alloy steels.

Connecting rod: - It connects piston? & crank. It transmits power developed on the piston to

crank shaft through crank. It is usually made of medium carbon steel.

Cooling fins or cooling water jackets:- Study of 4-stroke cycle diesel engine.- During

combustion engine releases a large amount of heat thus engine parts may be subjected to a

temperature at which engine parts may not sustain their mechanical properties such as Hardness

etc. In order to keep the engine parts within safe temperature limits, the cylinder & cylinder head

are provided with cooling arrangement. The cooling fins are provided on light duty engines

while cooling water jackets are provided on medium & heavy duty engines.

Cam shaft: - It is provided on four stroke engines. It carries two cams, for controlling the

opening & closing of inlet & exhaust valves.

Inlet valve: - This valve controls the admission of charge into the engine into the engine during

the suction stroke.

Exhaust valve: - The removal of exhaust gases after doing work on piston is controlled by

exhaust valve.

Inlet manifold: - It is the passage which carries the charge from carburetor to engine.

Exhaust manifold: - It is the passage which carries the exhaust gases from the exhaust valve to

atmosphere.

Spark plug: - It is provided on petrol engines. It produces a high intensity spark which initiates

the combustion process of the charge.

Fuel injector: - It is provided on diesel engines. The Diesel fuel is injected in the cylinder at the

end of compression through fuel injector under very high pressure.

Carburetor: - It is provided with petrol engine for Preparation of homogeneous mixture of air &

fuel (Petrol). This mixture as a charge is supplied to engine Cylinder through suction valve or

port.

Fuel pump:-It is provided with diesel engine. The diesel is taken from fuel tank & its pressure is

raised in the fuel pump & then it is delivered to fuel injector.

Flywheel: - It is mounted on the crank shaft. It is made of Cast iron. It stores energy in form of

inertia, when energy is in excess & it gives back energy when it is in deficit i.e. it minimizes the

speed fluctuations on the engine

Construction: - A 4-stroke cycle diesel engine contains fuel injector, fuel pump, cylinder,

cylinder head, inlet & exhaust valves, piston attached with piston rings, connecting rod, crank

shaft, cams, cam shaft, etc. One cycle of 4-stroke cycle diesel engine is completed in 4-stroke of

piston or two revolutions of crank shaft.

WORKING:

The working is divided into four strokes as shown in figure 8 (a). Working of these strokes is represented

by P-V diagram as shown in Figure 8 (b).

SUCTION STROKE:

With the movement of the piston from T.D.C. to B.D.C. during this stroke, the inlet valve opens and

the air at atmospheric pressure is drawn inside the engine cylinder; the exhaust valve however

remains closed. This operation is represented by the line 5-1

COMPRESSION STROKE:

The air drawn at atmospheric pressure during the suction stroke is compressed to high pressure and

temperature as the piston moves from B.D.C. to T.D.C. Both the inlet and exhaust valves do not open

during any part of this stroke. This operation is represented by 1-2

POWER STROKE OR EXPANSION STROKE:

As the piston starts moving from T.D.C to B.D.C, the quantity of fuel is injected into the hot

compressed air in fine sprays by the fuel injector and it (fuel) starts burning at constant pressure

shown by the line 2-3.

At the point 3 fuel supply is cut off. The fuel is injected at the end of compression stroke but in actual

practice the ignition of the fuel starts before the end of the compression stroke. The hot gases of the

cylinder expand adiabatically to point 4. Thus doing work on the piston.

EXHAUST STROKE:

The piston moves from the B.D.C. to T.D.C. and the exhaust gases escape to the atmosphere through

the exhaust valve. When the piston reaches the T.D.C. the exhaust valve closes and the cycle is

completed. This stroke is represented by the line 1-5.

Figure 8 (a) 4-Stroke Cycle Diesel Engine

Result/ conclusions

The above Experiment Concluded that 4 Stroke Cycle Diesel Engine required higher

maintenance & having Lower But operated at higher loads.

Viva questions

1. Explain 4-stroke cycle diesel engine.

2. What is internal combustion engine?

3. Explain Piston rings

4. What is Applications o f4-stroke cycle diesel engine?

5. What is Function of Crank shaft?

EXPERIMENT NO.4

2-STROKE CYCLE PETROL ENGINE

Aim: To Study of 2-stroke cycle petrol engine

Apparatus required: 2-stroke cycle petrol engine model

Theory

All essential operations are carried out in one revolution of the crank shaft or two strokes of the

piston therefore engine is called 2- stroke cycle engine as shown in figure 9.

Internal combustion engine: - When the combustion of fuel takes place inside the cylinder then

engine is known as I.C. Engine.

Classification of I.C. engine:-

(1) According to the fuel used in cycle:-

(a) Gas engine (b) Petrol engine (c) Diesel engine (d) Multi-fuel engine

(2) According to piston strokes in the working cycle:-

(a) Four strokes cycle engine (b) Two strokes cycle engine

(3) According to method of ignition:-

(a) Spark ignition (b) Compression ignition

(4) According to fuel feeding system:-

(a) Carbureted engine (b) Engine with fuel injection

(5) According to charge feeding system:-

(a) Naturally aspired engine (b) Supercharged engine

(6) According to the cooling system:-

(a) Air-cooled engine (b) Water cooled engine (c) Oil cooled engine

(7) According to no. of cylinder:-

(a) Single cylinder engine (b) Multi-cylinder engine

(8) According to speed of engine:-

(a) Low speed engine (b) Medium speed engine (c) High speed engine

(9) According to position of engine:-

(a) Inline engine (Horizontal &Vertical engine) (b) V engine (c) Radial engine

(10) According to cycle of operation:-

(a) Otto-cycle engine (b) Diesel cycle engine (c) Dual cycle engine

(11) According to method of governing:-

(a) Quality governed engine (b) Quantity governed engine

(12) According to valve arrangement:-

(a)Overhead valve engine (b) L-head type engine (c) T-head type engine (d) F-head type engine

Components of I.C. engine:-

The essential parts of Otto-cycle & Diesel cycle engines are the same.

Cylinder: - It is the heart of the engine. The piston reciprocates in the cylinder. It has to

withstand very high pressure & temperature therefore if material should have high strength.

Generally it is made from cast iron. It is provided with cylinder liner on inner side & cooling

arrangement on its outer side. The upper end consists of a combustion as clearance space in

which the ignition & combustion of charge takes place. Generally Cylinder is cast in single

piece.

Cylinder head: - The top cover of cylinder towards TDC is called cylinder head. It houses the

spark plug in petrol engines & fuel injector in diesel engines.

Piston: - It is reciprocating member of the engine. It reciprocates in the cylinder. It is made of

usually cast iron / aluminum alloys. Its top surface is called piston crown & bottom surface is

piston skirt. Its top surface is made flat for four stroke engines & deflected for two stroke

engines. Its function is to compress the charge during compression stroke & to transmit the force

to the connecting rod.

Piston rings: - Piston rings provide a good sealing fit between piston & cylinder. The two or

three piston rings are provided on piston. The rings are usually made of cast iron having fire

grade & high elasticity which is not affected by the working heat. These are housed in the air-

circumferential grooves provided on the outer surface of the piston. The function of these rings

to give gas tight fitting between the piston & the cylinder prevents the leakage of high pressure

gases.

Crank: - It is a rotating member. It makes circular motion in the crank case (its housing). Its one

end connected with shaft called Crank-shaft & other end is connected with Connecting rod.

Crank case: - It is housing of crank & body of engine to which cylinder & other engine parts are

fastened. It also acts as a ground for lubricating oil.

Crank shaft: - It is a rotating member which connects crank & the power developed by engine

is transmitted outside through the shaft .It is made of medium carbon or alloy steels.

Connecting rod: - It connects piston & crank. It transmits power developed on the piston to

crank shaft through crank. It is usually made of medium carbon steel.

Cooling fins or cooling water jackets: - During combustion engine releases a large amount of

heat thus engine parts may be subjected to a temperature at which engine parts may not sustain

their mechanical properties such as Hardness etc. In order to keep the engine parts within safe

temperature limits, the cylinder & cylinder head are provided with cooling arrangement. The

cooling fins are provided on light duty engines while cooling water jackets are provided on

medium & heavy duty engines.

Cam shaft: - It is provided on four stroke engines. It carries two cams, for controlling the

opening & closing of inlet & exhaust valves.

Inlet valve: - This valve controls the admission of charge into the engine into the engine during

the suction stroke.

Exhaust valve: - The removal of exhaust gases after doing work on piston is controlled by

exhaust valve.

Inlet manifold: - It is the passage which carries the charge from carburetor to engine.

Exhaust manifold: - It is the passage which carries the exhaust gases from the exhaust valve to

atmosphere.

Spark plug: - It is provided on petrol engines. It produces a high intensity spark which initiates

the combustion process of the charge.

Fuel injector: - It is provided on diesel engines. The Diesel fuel is injected in the cylinder at the

end of compression through fuel injector under very high pressure.

Carburetor: - It is provided with petrol engine for Preparation of homogeneous mixture of air &

fuel (Petrol). This mixture as a charge is supplied to engine Cylinder through suction valve or

port.Fuel pump:-It is provided with diesel engine. The diesel is taken from fuel tank & its

pressure is raised in the fuel pump & then it is delivered to fuel injector.

Flywheel: - It is mounted on the crank shaft. It is made of Cast iron. It stores energy in form of

inertia, when energy is in excess & it gives back energy when it is in deficit i.e. it minimizes the

speed fluctuations on the engine

Construction: - It consists of a cylinder, cylinder head, piston, piston rings, connecting rod,

crank, crank case, crank shaft etc. The charge (air- fuel mixture) is prepared outside the cylinder

in the carburetor. The ports are provided charge inlet & exhaust outlet which are uncovered &

closed by moving piston. The suction port is used for induction of charge into crank case, the

transfer port is used for transfer of charge from crank case to cylinder & exhaust port serves the

purpose of discharging the burnt gases from the cylinder. The spark plug is located in the

cylinder head.

WORKING:-

The cylinder L is connected to a closed crank chamber C.C. During the upward stroke of the

piston M, the gases in L are compressed and at the same time fresh air and fuel (petrol) mixture

enters the crank chamber through the valve V. When the piston moves downwards, V closes and

the mixture in the crank chamber is compressed the piston is moving upwards and is

compressing an explosive change which has previously been supplied to L. Ignition takes place

at the end of the stroke. The piston then travels downwards due to expansion of the gases and

near the end of this stroke the piston uncovers the exhaust port (E.P.) and the burnt exhaust gases

escape through this port.

The transfer port (T.P.) then is uncovered immediately, and the compressed charge from the

crank chamber flows into the cylinder and is deflected upwards by the hump provided on the

head of the piston. It may be noted that the incoming air-petrol mixture helps the removal of

gases from the engine-cylinder; if, in case these exhaust gases do not leave the cylinder, the fresh

charge gets diluted and efficiency of the engine will decrease. The piston then again starts

moving from B.D.C. to T.D.C. and the charge gets compressed when E.P. (exhaust port) and

T.P. are covered by the piston; thus the cycle is repeated.

Applications: -

(1) 2-stroke engines are used; where simplicity & low cost is main considerations. These

engines have little higher specific fuel consumption.

(2) 50cc-70cc engines are used in mopeds, lawn movers & non-gear vehicles.

(3) 100cc-150cc engines are commonly used in scooter & motor cycles. 250cc engines are used

in high powered (racing) motor cycles.

Fig (a) 2-Stroke Cycle Petrol Engine

Result/ conclusions

The above Experiment concluded that 2 Stroke Cycle Petrol Engine required having higher Efficiency

and Lower Cost.

Viva questions

1. Explain 2-stroke cycle petrol engine

2. What is function of Carburettor?

3. Explain Applications of 2-stroke cycle engine

4. Explain cam shaft.

5. What is function of Carburetor?

EXPERIMENT NO. 5

2-STROKE CYCLE DIESEL ENGINE

Aim: To Study of 2-stroke cycle diesel engine.

Apparatus required: 2-Stroke Cycle Diesel engine Model

Theory

All essential operations are carried out in one revolution of the crank shaft or two strokes of the

piston therefore engine is called 2- stroke cycle engine as shown in figure 10.

INTERNAL COMBUSTION ENGINE: - When the combustion of fuel takes place inside the

cylinder then engine is known as I.C. Engine.

CLASSIFICATION OF I.C. ENGINE:-

(1) According to the fuel used in cycle:-

(a) Gas engine (b) Petrol engine (c) Diesel engine (d) Multi-fuel engine

(2) According to piston strokes in the working cycle:-

(a) Four strokes cycle engine (b) Two strokes cycle engine

(3) According to method of ignition:-

(a) Spark ignition (b) Compression ignition

(4) According to fuel feeding system:-

(a) Carbureted engine (b) Engine with fuel injection

(5) According to charge feeding system:-

(a) Naturally aspired engine (b) Supercharged engine

(6) According to the cooling system:-

(a) Air-cooled engine (b) Water cooled engine (c) Oil cooled engine

(7) According to no. of cylinder:-

(a) Single cylinder engine (b) Multi-cylinder engine

(8) According to speed of engine:-

(a) Low speed engine (b) Medium speed engine (c) High speed engine

(9) According to position of engine:-

(a) Inline engine (Horizontal &Vertical engine) (b) V engine (c) Radial engine

(10) According to cycle of operation:-

(a) Otto-cycle engine (b) Diesel cycle engine (c) Dual cycle engine

(11) According to method of governing:-

(a) Quality governed engine (b) Quantity governed engine

(12) According to valve arrangement:-

(a)Overhead valve engine (b) L-head type engine (c) T-head type engine (d) F-head type engine

Components of I.C. engine:-

The essential parts of Otto-cycle & Diesel cycle engines are the same.

Cylinder: - It is the heart of the engine. The piston reciprocates in the cylinder. It has to

withstand very high pressure & temperature therefore if material should have high strength.

Generally it is made from cast iron. It is provided with cylinder liner on inner side & cooling

arrangement on its outer side. The upper end consists of a combustion as clearance space in

which the ignition & combustion of charge takes place. Generally Cylinder is cast in single

piece.

Cylinder head: - The top cover of cylinder towards TDC is called cylinder head. It houses the

spark plug in petrol engines & fuel injector in diesel engines.

Piston: - It is reciprocating member of the engine. It reciprocates in the cylinder. It is made of

usually cast iron / aluminum alloys. Its top surface is called piston crown & bottom surface is

piston skirt. Its top surface is made flat for four stroke engines & deflected for two stroke

engines. Its function is to compress the charge during compression stroke & to transmit the force

to the connecting rod.

Piston rings: - Piston rings provide a good sealing fit between piston & cylinder. The two or

three piston rings are provided on piston. The rings are usually made of cast iron having fire

grade & high elasticity which is not affected by the working heat. These are housed in the air-

circumferential grooves provided on the outer surface of the piston. The function of these rings

to give gas tight fitting between the piston & the cylinder prevents the leakage of high pressure

gases.

Crank: - It is a rotating member. It makes circular motion in the crank case (its housing). Its one

end connected with shaft called Crank-shaft & other end is connected with Connecting rod.

Crank case: - It is housing of crank & body of engine to which cylinder & other engine parts are

fastened. It also acts as a ground for lubricating oil.

Crank shaft: - It is a rotating member which connects crank & the power developed by engine

is transmitted outside through the shaft .It is made of medium carbon or alloy steels.

Connecting rod: - It connects piston? & crank. It transmits power developed on the piston to

crank shaft through crank. It is usually made of medium carbon steel.

Cooling fins or cooling water jackets: - During combustion engine releases a large amount of

heat thus engine parts may be subjected to a temperature at which engine parts may not sustain

their mechanical properties such as Hardness etc. In order to keep the engine parts within safe

temperature limits, the cylinder & cylinder head are provided with cooling arrangement. The

cooling fins are provided on light duty engines while cooling water jackets are provided on

medium & heavy duty engines.

Cam shaft: - It is provided on four stroke engines. It carries two cams, for controlling the

opening & closing of inlet & exhaust valves.

Inlet valve: - This valve controls the admission of charge into the engine into the engine during

the suction stroke.

Exhaust valve: - The removal of exhaust gases after doing work on piston is controlled by

exhaust valve.

Inlet manifold: - It is the passage which carries the charge from carburetor to engine.

Exhaust manifold: - It is the passage which carries the exhaust gases from the exhaust valve to

atmosphere.

Spark plug: - It is provided on petrol engines. It produces a high intensity spark which initiates

the combustion process of 2-stroke cycle diesel engine.

Fuel injector: - It is provided on diesel engines. The Diesel fuel is injected in the cylinder at the

end of compression through fuel injector under very high pressure.

Carburetor: - It is provided with petrol engine for Preparation of homogeneous mixture of air &

fuel (Petrol). This mixture as a charge is supplied to engine Cylinder through suction valve or

port.

Fuel pump:-It is provided with diesel engine. The diesel is taken from fuel tank & its pressure is

raised in the fuel pump & then it is delivered to fuel injector.

Flywheel: - It is mounted on the crank shaft. It is made of Cast iron. It stores energy in form of

inertia, when energy is in excess & it gives back energy when it is in deficit i.e. it minimizes the

speed fluctuations on the engine

Construction: - It has fuel injector instead of spark plug in cylinder head. It uses high

compression ratio therefore injected fuel is self-ignited. It takes air as charge & fuel is injected at

the end of compression stroke.

WORKINGThe cylinder L is connected to a closed crank chamber C.C. During the upward

stroke of the piston M, the gases in L are compressed and at the same time fresh air enters the

crank chamber through the valve V. When the piston moves downwards, V closes and the air in

the crank chamber is compressed when the piston is moving upwards and then fuel is injected

through fuel pump and Ignition takes place at the end of the stroke. The piston then travels

downwards due to expansion of the gases and near the end of this stroke the piston uncovers the

exhaust port (E.P.) and the burnt exhaust gases escape through this port.

The transfer port (T.P.) then is uncovered immediately, and the compressed charge from the

crank chamber flows into the cylinder and is deflected upwards by the hump provided on the

head of the piston. It may be noted that the incoming air-petrol mixture helps the removal of

gases from the engine-cylinder; if, in case these exhaust gases do not leave the cylinder, the fresh

charge gets diluted and efficiency of the engine will decrease. The piston then again starts

moving from B.D.C. to T.D.C. and the charge gets compressed when E.P. (exhaust port) and

T.P. are covered by the piston; thus the cycle is repeated.

APPLICATIONS: -

(1.) 2-stroke engines are used, where simplicity & low cost is main considerations.

(2.) These engines have little higher specific fuel consumption.

(3.) 50cc-70cc engines are used in mopeds, lawn movers & non-gear vehicles

(4.) 100cc-150cc engines are commonly used in scooter & motor cycles.

(5.) 250cc engines are used in high powered (racing) motor cycles.

Result/ conclusions

The above Experiment concluded that 2 Stroke Cycle Diesel Engine required having lower

Efficiency and higher Cost as compare to Petrol Engine.

Viva questions

1. What is a function Fuel of Pump?

2. What is a function of Crank?

3. Explain Fuel Injector.

4. Explain cylinder of I.C Engine?

5. W

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