Equivalence of 'Reversible' and 'Irreversible' Entropy Modeling

TL;DR

This paper demonstrates that the 'reversible' and 'irreversible' entropy models are mathematically equivalent in terms of entropy accumulation, challenging traditional distinctions and simplifying entropy modeling language.

Contribution

It establishes the equivalence of the two main entropy models and questions the validity of the 'second fundamental equation' of reversible entropy.

Findings

Equivalence of 'reversible' and 'irreversible' entropy models.

Equation dS = dQ/T holds for non-reversible phenomena.

No evidence supports the falsity of the equation for non-reversible cases.

Abstract

There are currently two main, continuum models of entropy: a 'reversible', Clausius entropy model and an 'irreversible', Onsager-Prigogine entropy model. It is shown that the equations of the 'reversible' and the 'irreversible' entropy models are equivalent with respect to entropy accumulation, which entails same values of entropy change and, thus, same values of entropy. The equivalence contradicts the 'second fundamental equation' of the 'reversible' entropy model, dS = dQ/T, holding true for 'reversible' phenomena, only. The equivalence conforms with entropy history independence, which entails that equation dS = dQ/T must hold true for not 'reversible' phenomena, also. Several examples, e.g. by commercial engineering software, show that equation dS = dQ/T holds true for not 'reversible' phenomena, also. The two results of this analysis, the equivalence of the two entropy models and the falsity of 'reversibility', would be falsified by evidence for equation dS = dQ/T not holding true for not 'reversible' phenomena. No such evidence has been presented. The main consequence of the equivalence of the two entropy models is a signification simplification of the language used in the context of entropy modeling.