Explain heat engines ? Explain its working.

Explanation

Heat engine is a device by which a system is made to undergo a cyclic process that results in conversion of heat to work.

A simple heat engine is shown in figure. The gas enclosed in a cylinder with a piston receives heat from a burner on absorbing heat energy the gas expends and pushes the piston upwards. So the wheel starts rotating.
To continue the rotations of the wheel an arrangement is necessary to the heat engine so that the piston can move up and down.
Gas is called a working substance of engine. The mechanism of conversion of heat into work varies for different heat engine.
The heat engines are of two types :
(i) External combustion engine such as stem engine.
(ii) Internal combustion engines such as diesel, petrol and gas engine.
The various steps involved in a cycle also differ from one engine to another.
The working substance goes through a cycle consisting of several processes. In some of then processes, it absorbs a total amount of heat `Q_1` from an external reservoir at some high temperature `(T_1)`.
And it released heat `Q_2` into the heat sink having temperature `(Q_1)`.