Question

Why Carnot cycle is not practically possible ?

Answer 1

Carnot engine:

Any machine used to convert heat into mechanical work is called a heat engine. The Carnot engine is an ideal heat engine.

Properties of a Carnot engine:

1. It has $100\%$efficiency.
2. Change in pressure and volume of the working substance takes place slowly.
3. Working substance is always in thermal equilibrium with source and sink.
4. A perfectly insulating frictionless piston and a cylinder with perfectly insulating walls are used as working substances, they are considered to not have any dissipative effects like friction, conduction of heat, etc.

Carnot cycle is not practically possible as:

1. The Carnot cycle is reversible, whereas the real heat engines are not due to friction, heat transfer to the insulating wall, etc.
2. In a Carnot cycle, since the processes are reversible, they are extremely slow, while in real life, the engines work faster.

Carnot engine is not practically possible as in real life.