Discrete Systems in Thermal Physics and Engineering -- A Glance from Non-Equilibrium Thermodynamics

TL;DR

This paper explores non-equilibrium thermodynamics in discrete systems, establishing a theoretical framework that links entropy, temperature, and process efficiency beyond classical limits.

Contribution

It proves the embedding theorem ensuring the compatibility of non-equilibrium processes with entropy and introduces a non-equilibrium entropy as a state function.

Findings

Non-equilibrium entropy can be defined as a state function.

Contact temperature can serve as a primitive concept even out of equilibrium.

Efficiency of generalized cyclic processes exceeds Carnot limits.

Abstract

Non-equilibrium processes in Schottky systems generate by projection onto the equilibrium subspace reversible accompanying processes for which the non-equilibrium variables are functions of the equilibrium ones. The embedding theorem which guarantees the compatibility of the accompanying processes with the non-equilibrium entropy is proved. The non-equilibrium entropy is defined as a state function on the non-equilibrium state space containing the contact temperature as a non-equilibrium variable. If the entropy production does not depend on the internal energy, the contact temperature changes into the thermostatic temperature also in non-equilibrium, a fact which allows to use temperature as a primitive concept in non-equilibrium. The dissipation inequality is revisited, and an efficiency of generalized cyclic processes beyond the Carnot process is achieved.