The second law of thermodynamics proposed by Clausius, Kelvin, Carnot ..etc in its original form as T dS> dQ for irreversible process and Tds =dQ only for reversible thermodynamics process.
This particular formulation may be stated in many "equivalent" forms most common is : The Carnot cycle is the most thermally efficient between T2 and T1. However, there is still controversy debate: this statement can not be exactly equal to the second law it is just a corollary?
The Carnot cycle is the most thermally efficient between T2 and T1. However, there is still controversy debate: this statement can not be exactly equal to the second law it is just a corollary?
It's my understanding it is a corollary to the Kelvin Plank statement of the second law.
Kelvin-Planck Statement of Second Law No heat engine can operate in a cycle while transferring heat with a single heat reservoir.
COROLLARY to Kelvin-Planck: No heat engine can have a higher efficiency than a Carnot Cycle operating between the same reservoirs
Clausius' Statement of Second Law No refrigeration or heat pump cycle can operate without a net work input
COROLLARY: No refrigerator or heat pump can have a higher COP than a Carnot Cycle refrigeratore or heat pump.
Hope this helps.
