Causius Inequality

 Clausius inequality states that "when a system undergoes a cyclic process, the summation of dQ/T around a closed cycle is less than or equal to zero."

CLAUSIUS INEQUALITY

Clausius inequality states that "when a system undergoes a cyclic process, the summation of dQ/T around a closed cycle is less than or equal to zero."

Consider an engine operating between two fixed temperature reservoirs T1 and T2. Let, dQ1 unit of heat is supplied at temperature T1 and dQ2 unit of heat is rejected at temperature T2 in a cycle.

Thermal efficiency of any reversible engine working on the same temperature limit is given by

Since no engine can be more efficient than the reversible engine, the efficiency of an actual engine cycle must be less than a reversible cycle. Hence,

This equation is known as Clausius inequality. It provides the criterion of the reversibility of a cycle.