Second Law of thermodynamics

Kelvin plank Statement

It is impossible for a heat engine to produce net work in a complete cycle if it exchanges heat only with bodies at a single fixed temperature.

Two reversible adiabatic parts cannot intersect each other which violates the Kelvin-Plank;s statement.

The machine which violate Kelvin plank statement is called PPM2 (Perpetual Motion Machine of Second kind).

Clauses Statement

It is impossible to construct a device which operating in a cycle transfers heat from cooler body to a hotter body without any work input.