2020/06/23 by Martti Pekkanen, Pekkanen, Martti
Engineering · Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #FOS: Physical sciences #General Physics (physics.gen-ph) #Phase Equilibria and Thermodynamics #Statistical Mechanics and Entropy
paper · pdf · doi:10.48550/arxiv.2006.12825
openalex publication_date 2020/06/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
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.