Clausius postulate

The Clausius postulate is the formulation given by Rudolph Clausius of the second law of thermodynamics and is equivalent to Kelvin's postulate.

It is stated as follows:

"A thermodynamic transformation of which the only result is to transfer heat from a body at a given temperature to a body at a higher temperature is impossible".

Rudolf Clausius (Credit: Yvonne Kristen).