Скачать или смотреть SPARK IGNITION VS COMPRESSION IGNITION ENGINE.

Differentiating a diesel engine from a petrol Engine.

The main parameters used for comparing the two Internal combustion engines are

Basic Operational Cycle
Type of fuel
Method of fuel injection
Ignition process
Compression Ratio
speed
Thermal efficiency
Weight.

1.... Basic operational cycle : petrol engines, also known as spark ignition (S.I) engines,works on the basis of otto cycle or constant volume heat addition cycle. in S.I engines,ignition process is carried out with the help of a spark plug which ignites a mixture of air and fuel that is compressed in the combustion chamber.

Whereas,a diesel engine also known as Compression Ignition (C.I) engine works on the basis of Diesel cycle or Constant pressure heat addition cycle. In C.I engines, self ignition occurs due to high temperature of highly compressed air. Hence, spark plugs are not required.

2....Type of Fuel: S.I engines uses petrol as their working fuel, petrol is a highly volatile fuel and has a high self ignition temperature

whereas, C.I engine uses diesel as the working fuel. Diesel is a non volatile fuel with a low self ignition temperature.

3.... Method of fuel injection

In S.I engines, a mixture of air and fuel is introduced in the suction stroke, thus, it consist of a carburetor for mixing the air and fuel.

while in a C.I engine, fuel in injected directly into the combustion chamber at high pressure. Thus , it consist of a fuel pump and a fuel injector

4... Compression Ratio: in S.I engines, compression ratio varies from 6 to 10. Here, upper limit of the compression ratio is determined by antiknock quality of the fuel,

while in C.I engines, compression ratio varies from 16 to 20. Here, upper limit of the compression ratio is determined by weight increase of the engine.

5... Speed...:S.I engines are high speed engines, due to their light weight and homogeneous combustion

whereas, C.I engines are low speed engines due to their heavy weight and heterogeneous combustion

6... Thermal efficiency: Due to lower compression ratio, maximum value of thermal efficiency is lower in an S.I engine compared to that of C.I.

7...Weight : S.I engines are generally lighter in weight due to their lower peak pressures as compare to C.I engines that are generally heavier, due to higher peak pressure.