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Heat Engine and Its Components

In this post, we will discuss heat engine and its components with the help of examples. Generally, heat engine consists of three main components i.e. Source, Sink, and Working substances.

What is Heat Engine?

A simple definition of Heat Engine, which defines it clearly is given below:

Any device which converts heat energy continuously into mechanical work is called Heat engine.


  1. When water is boiled in the vessel closed by a lid, then the steam generated inside through the lid off, showing thereby that high-pressure steam can be made to do work.
  2. Also, the high-velocity wind caused by heating the part of earth surfaces by sun do work in driving windmills.

All these simple and elementary facts indicate that transfer of heat to a body results in mechanical work and hence developed several types of modern heat engines-the steam engine, the internal combustion engine and gas turbines.

Components of Heat Engine

Heat engine consists of following components:

Heat Engine and its components
Fig. A heat engine
  1. Source
  2. Sink
  3. Working Substance

Let us explain each of them clearly:


A hot body at high-temperature T1 from which engine can draw heat is called Source.


A cold body at lower temperature T2 to which any amount of heat can be rejected is called the sink.

Working Substance:

The material which on being supplied with heat performs mechanical work is called a working substance.

Let Q1= amount of heat absorbed by working substance.

Q2 = amount of heat rejected to sink.

Therefore, the amount of work done per cycle:

W = Q1 – Q2

Efficiency of Heat Engine

It is defined as the ratio of the total amount of work done per cycle to total heat absorbed per cycle. It is denoted by  η

Heat Engine & It's components

This is how we discussed Heat Engine, its components & efficiency of the heat engine. We are always happy to clear your doubts. You can always ask your doubts, queries in the comment section.

See Also:

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