Internal combustion engines

UNIT – IV

Chapter - 17

INTERNAL COMBUSTION ENGINES

HEAT ENGINES

Thermal Prime Mover is a prime mover that is made to utilize thermal (heat) energy for conversion into mechanical work. Examples: Steam Engines, Steam Turbines, Gas Turbines, Diesel Engines, Petrol Engines.

Thermal Prime Movers are also known as Heat Engines. A source of heat, a medium to carry the heat energy and a converting machine are all required for running the heat engine. The source of heat is a combustion chamber from which heat energy is supplied to the medium. Examples: Reciprocating type and Rotary type.

Reciprocating Type consists of a hollow cylinder into which a piston reciprocates by the action of the working fluid. Examples: Diesel Engine and Petrol Engine. Rotary Type consists of a wheel fixed upon a shaft and fitted with blades or vanes on it. The wheel rotates due to the action of the working fluid upon the blades. Examples: Steam Turbine and Gas Turbine.

1. HEAT ENGINES – CLASSIFICATION

Heat Engines are classified according to the place of combustion of fuel as discussed below:

1. External Combustion Engine (E.C. Engine)

 As the name implies, if the combustion of fuel takes place outside the engine, the engine is called External Combustion Engine. Examples: Steam Engines and Steam Turbines. In these, the combustion of fuel takes place in a boiler.

2. Internal Combustion Engine (I.C. Engine )

See Fig. 1(i). As the name implies, if the combustion takes place inside the engine, the engine is. called Internal Combustion Engine. In I.C. Engines, the working fluid is the product of combustion of fuel-air mixture. Examples: Petrol Engines, Diesel Engines

I.C. Engines have made a major revolution in the field of transportation and communication on land, on sea and in the sky. These are made use of in motorcycles, scooters, buses, cars, trucks, railway engines, ships, aero-engines, tractors, harvesters, etc.,

Yes! The development of I.C. engines has made a great contribution to human comforts. It is indeed surprising – rather unbelievable – that about 100 years ago, there was no I.C. Engine at all in any part of the world. Obviously, the present generation really enjoys very many comforts than our ancestors.

2. CLASSIFICATION OF I.C. ENGINES