Heat engine is a device which converts the chemical energy of fuel into thermal energy and then uses this energy to produce mechanical work.
In this blog i will explain you all terms of heat engine and I.C engine with their working and application. This is helpful for student studying in 11th class and also for diploma / polytechnic student.
Important I.C Engine Topic
- Classification of Heat Engine
- Difference Between Internal or External Combustion Engine
- Classification of I.C Engine
- Location , Function and materials of various parts of I.C engines.
- I.C engine term
- Working principle of two and four stroke cycle engine
- Application of I.C engine
- Important Question and Answer
Heat engine may be classified into following categories :-
a). External combustion engines ,
b). Internal combustion engines (I.C engine)
External combustion engine :- The engine in which combustion of fuel take place outside the engine cylinder is known as external combustion engine. E.g. steam engine , steam turbine etc.
Internal combustion engine :- The engine in which combustion of fuel take place inside the engine cylinder is known as internal combustion engine or (I.C Engine). e.g. petrol engine , diesel engine , gas engine.
Difference between internal and external combustion engines.
|External combustion engine||External combustion engine|
|Combustion of fuel take place inside the engine cylinder.||Combustion of fuel take place outside the engine cylinder|
|Greater mechanical simplicity.||They are complex in nature.|
|Initial cost is less.||Initial cost is very high.|
|They have high efficiency (35% – 40%).||They have low efficiency (15% -20%)|
|Lower ratio of weight to power output.||High ratio of weight to power output.|
|Water is less requires to dissipation of heat energy.||Water is more requires to dissipation of heat energy.|
|Starting of these engine is easy.||Starting of these engine is hard.|
|Cost of fuel used is high.||Cost of fuel used is low.|
|These engines are mainly used for transport vehicles.||These engine are mainly used for large electric power generation.|
Classification of I.C engines
The I.C engine may be classified as
- According to working cycle :-
- Otto cycle engine (spark – ignition or S.I engine)
- Diesel cycle engine (compression ignition or I.C engine)
- According to number of strokes/cycle :-
- Two stroke engines
- Four stroke engine
- According to the fuel used :-
- Petrol engine
- Diesel engine
- Gas engine
- CNG engine
- LPG engine
- According to number of cylinders used :-
- Single cylinder engine
- Multi- cylinder engine
- According to arrangement of cylinders :-
- In – line engine
- V – engine
- Radial engine
- Opposed cylinder engine
- Opposed piston engine
- According to method of ignition of fuel :-
- Spark ignition engine (S.I engine)
- Compression ignition engine (C.I engine)
- Hot spot ignition engine
- According to the method of cooling the cylinder :-
- Water cooled engine
- Air cooled engine
- According to the speed of engine :-
- Low speed engine
- Medium speed engine
- High speed engine
- According to method of governing :-
- Hit and miss governed engine
- Qualitatively governed engine
- Quantitatively governed engine
- According to field of application :-
- Stationary engine
- Marine engine
- Portable engine
- Automotive engine
- Air craft engine
- According to valve arrangement :-
- Over head valve engine
- Side valve engine
- According to fuel supply :-
- Carbureted type
- Injection type
Location , Function and materials of various parts of I.C engines.
|Material used||Material used||Function|
|Cylinder||Cast iron||It is the main body of engine in which piston reciprocate.|
|Piston||Cast iron , alluminium alloy||It compress the charge during compression state and transmit the force to the crank shaft.|
|Piston ring||Special grade cast iron||Fitting between piston ring to prevent the leakage of gases|
|Connecting rod||Nickel , chrome , steel and alluminium||It transmit the piston load to crank|
|Crank shaft||Forged steel, nickel alloy||It convert the reciprocating motion to rotary motion|
|valves||Nickel , chromium , steel or H.S.S||It control the inlets exhaust of the I.C engine|
|Fly wheel||Steel and cast iron||It absorb energy and given when energy try to slow down , keeping the engine speed almost constant|
|Cam shaft||Alloy or medium carbon steel||The cam shaft controls the opening and closing of valves at the time.|
|Spark plug||High nickel alloys , aluminium oxide ceramic , steel wire||It is used in spark ignition (S.I) engines only to initiate combustion process.|
|carburettor||Brass , gun metal , aluminium alloys||It is used in spark (S.I) engines.it mixes the petrol and air in proper proportion and supply the mixture to the cylinder at proper time.|
|Fuel injector||Carburized or maraging steel||It is used in diesel engine only. It supplies the fuel to the cylinder in the form of fine spray.|
|Fuel injection pump||Carburizing steel||It is used in diesel engine only. Its supplies fuel at a very high pressure to the fuel injector.|
Click here to read about Thermodynamics System
I.C engine term :-
- Cylinder bore (D) :- the nominal inner diameter of the working cylinder is known as cylinder bore.
- Piston area (A) :- it is the area of a circle of diameter equal to cylinder bor.
A = d2
- Dead centre :- the position of the working piston at the moment when its direction of motion reversed at either end point of the stroke is called dead centre.
- Stroke (L) :- the distance travelled by piston from one dead centre to other dead centre is called stroke.
- Crank radius or throw :- the distance between the centres of the crank shaft and crank pin is called crank radius.
- Displacement or swept volume :- the volume displace by the piston while travelling from one dead centre to the other is called displacement.
Vs = A*L = d2L
- Clearance volume (Vc) :- the volume of the combustion chamber above the piston when it is at the top dead centre or inner dead centre is known as clearance volume.
- Compression ratio (r) :- the ratio of total cylinder volume to clearance volume is called compression ratio.
Compression ratio = cylinder volume / clearance volume = Vs + Vc / Vc
r = 1+ Vs/ Vc
- Piston speed :- It is the distance travel by the piston per unit time.
Working principle of two and four stroke cycle engine
The step of operation in a cycle are :-
- Suction stroke :- During this stroke the inlet valve opens and exhaust valve remain closed. Only air is allow to enter into the cylinder. Piston moved prom T.D.C to B.D.C.
- Compression stroke :- Both the inlet and outlet valves remains closed. The air drawn during suction stroke is compessed. Due to high compression ratio (15 to 20) the air is compressed to a very high pressure (40 bar)and the temperature increase considerably ( as high as). This temperature is high enough to its ignite the fuel.
- Expansion or working stroke :- Both inlet and exhaust valve remain closed due to increase pressure of combustion gas . The piston is pushed down with a large force. Therefore power is produced during this stroke. The stroke is completed as the piston reach in B.D.C position.
- Exhaust stroke :- During this stroke the exhaust valve opens and inlet remains closed. The piston from B.D.C to T.D.C pushing out burn gases from the engine cylinder and exhaust valve is closed and cycle completed.
Click here to read Four stock engine
Application of I.C engine
- Petrol or S.I engine
- Four stroke petrol engine :- Mainly used in light vehicles such as cars , jeeps , Aeroplanes , motor cycles and scooters etc. due to increase price of petrol day by day.
- Two stroke petrol engine :- These engine are generally used in very light vehicles such as scooters , motor cycles , mopeds , hand sprayers and three Wheelers etc.
- Diesel or C.I engine
- Four stroke diesel engine :- Mainly used in heavy duty vehicles e.g. trucks , buses , tractors , diesel locomotives , earth moving machines etc.
- Two stroke diesel engine :- Mainly used in marine propulsion where lesser weight is of prime importance.
Ans. The spark ignition engine working on petrol or gas work on a cycle which is the slight modification of Otto cycle prepared by Dr.A.N(1876)
Ans. Heat engine is a device which convert the chemical energy of fuel into thermal energy and then uses this energy to produce mechanical work.
Ans. The engine is which combustion of fuel take place inside the engine cylinder is called internal combustion engine.
Ans. I.C engine has low weight to power ratio due to compact design and more efficient. The efficiency range from 30% – 35% , while the efficiency of stram engine varies from 15% – 20%.
Ans. Gudgeon pin connects the piston to the small end of the connecting rod.
Ans. The nominal inner diameter of the working cylinder is known as bore.
Ans. The ratio of the total cylinder volume to clearance volume is called compression ratio.
Ans. The engine which requires four strokes of piston or two revolution of the crank shaft to complete the working cycle is known as four stroke cycle engine.
Ans. The working cycle is completed in two strokes of piston or one revolution of the crank shaft.