General Boundedness of Energy Exchange as Alternative to the Third Law of Thermodynamics

As an alternative to the third law of thermodynamics, there has been proposed the principle of the boundedness of energy exchange between thermodynamic systems whose composite constitutes an isolated system (Heidrich, Ann. Phys. 373, 665, 2016). In this paper it is argued that the boundedness of energy exchange is a more general principle that is not restricted to systems whose composite is isolated. This leads to a simpler and more general alternative to the third law. The point of view is the phenomenological, macroscopic, and non-statistical one of classical thermodynamics. This paper is a sequel to the paper (Heidrich, Ann. Phys. 373, 665, 2016).