Constraints on Onsager coefficients from quasi-static and reversible operations

TL;DR

This paper explores the constraints on Onsager coefficients in cyclic heat engines, linking quasi-static and reversible operations, and discusses conditions under which Onsager reciprocity holds or is violated.

Contribution

It establishes a connection between quasi-static and reversible cycles in heat engines and derives conditions for Onsager reciprocity within this framework.

Findings

Onsager reciprocity arises from quasi-static and reversible equivalence under tight coupling.

Reversible cycles can be achieved in finite time when tight coupling is relaxed.

Onsager reciprocity is violated if either cycle is not quasi-static or not reversible.

Abstract

The performance of a generic, cyclic heat engine between two heat reservoirs is discussed within a linear-irreversible framework. The Onsager reciprocal relation is derived as a consequence of the equivalence between quasi-static and reversible operations, under the tight-coupling condition. When the latter condition is relaxed, it is possible to achieve reversible cycle in a finite duration. Onsager reciprocity must be violated when either the quasi-static cycle is not reversible, or the reversible cycle is not quasi-static.