Carnot cycle was introduced by Nicolas Leonard P t Sadi Carnot (1796-1834), a French Engineer, in 1824. It consists of four reversible processes, two frictionless isothermal and two frictionless adiabatics. He used piston-cylinder mechanism and made the following assumptions.
• The piston moving in cylinder does not encounter any friction during motion.
• The walls of piston and cylinder are perfect insulators of heat.
• The head of the cylinder is so arranged that it acts as perfect conductor and also as a perfect insulator (Interchangeable cylinder head).
• The heat transfer to and from source & sink does not change the temperature of source and sink.