An engine is a device which transforms one form of energy into another form. Most of the engines convert thermal engine to mechanical work and therefore they are called heat engine. Heat engine can be broadly classified into two types.
i. Internal combustion engine ii. External combustion engine
1.1 CLASSIFICATION OF INTERNAL COMBUSTION ENGINE:-
This type of engine is again classified into two types.
i. Rotary ii. Reciprocating
The reciprocating engine is a highly complex engine and has hundreds of component which have to perform their function satisfactory to produce output power. There are two types of engine; spark ignition and compression ignition engine. The diesel engine works on diesel oil, a non-volatile fuel. The self-ignition temperature is comparatively low. In this case fuel is injected directly into the combustion chamber at high pressure at the end of the compression stroke. Self-ignition occurs due to the high temperature of air because of the high compression. Spark plug and ignition are not necessary as in the case of spark engine. The CI engine is having a higher compression ratio, so the maximum value of the thermal efficiency can be obtained is higher. It is possible to obtain a power stroke for every revolution of crankshaft increasing the output of this engine.
The four stroke diesel engine is one of the most efficient and versatile prime movers. Small diesel engine is used in pump sets, construction machinery, air compressors, drilling jigs and many miscellaneous applications. Diesel engines are used both for mobile and stationary electric generating plants of varying capacities. Compared to gasoline engine, diesel engines are more efficient and therefore manufactures have come out with diesel engines in personal transportation. However the vibration and unpleasant odor in the exhaust are the main drawbacks. Tractors for agricultural application use about 30 kw diesel engines whereas jeeps, buses and trucks use