Engine components

Reciprocating IC Engine look quiet simple but they are highly complex machines. There are two types of engines, viz., spark-ignition (SI) and compression ignition (CI) engine.

A cross section of single cylinder spark ignition engine with overhead valves is shown in figure.

EC & IC Engines

External combustion engines are those in which combustion takes place outside the engine whereas in internal combustion engines, combustion takes place within the engine.

For example:

In a steam engine or steam turbine, the heat generated due to the combustion of fuel is employed to generate high pressure steam which is used s a working fluid in a reciprocating engine or a turbine.

In case of gasoline or diesel engines, the product of combustion generated by combustion of fuel and air within the cylinder form the working fluid.

Classification of heat engine

Engines whether IC or EC are of two types, viz.,

• Rotary engine
• Reciprocating engine

A detailed classification is given in figure

Of the various types of heat engines, the most widely used ones are the reciprocating IC Engine, the gas turbine and the steam turbine.

ENGINE

An engine is a device which transforms one form of energy into another form. However, the efficiency of conversion plys an important role. Normally most of the engines covert thermal energy into mechanical work and therefore they are called 'heat engines'.

Heat engine is a device which transforms the chemical energy of a fuel into thermal energy and utilizes this energy to perform useful work.

Heat engines can be broadly classified into two categories:

• Internal combustion engines (IC Engines)
• External combustion engines (EC Engines)