Nonequilibrium thermodynamics of populations of weakly-coupled low-temperature-differential Stirling engines with synchronous and asynchronous transitions

TL;DR

This paper develops a nonequilibrium thermodynamics framework for populations of weakly-coupled low-temperature-differential Stirling engines, analyzing how synchronous and asynchronous transitions affect their power and efficiency.

Contribution

It introduces a conceptual model that accurately captures the thermodynamic irreversibility and dynamics of coupled Stirling engines, improving upon quasilinear response relations.

Findings

Synchronous transitions increase power and efficiency.

Asynchronous transitions decrease power and efficiency.

The conceptual model better preserves thermodynamic irreversibility.

Abstract

This study developed the theory of nonequilibrium thermodynamics for populations of low-temperature-differential (LTD) Stirling engines weakly-coupled in a general class of networks to clarify the effects of synchronous and asynchronous transitions on the power and thermal efficiency. We first show that synchronous (asynchronous) transitions increase (decrease) the power and thermal efficiency of weakly-coupled LTD Stirling engines based on quasilinear response relations between formally defined thermodynamic fluxes and forces. After that, we construct a conceptual model satisfying the quasilinear response relations to give a physical interpretation of the changes in power and thermal efficiency due to synchronous and asynchronous transitions, and justify the use of this conceptual model. We then show that the conceptual model, rather than the quasilinear response relations, preserves the thermodynamic irreversibility of the original model and thus gives more accurate results than those using the quasilinear response relations. Finally, we compare the dynamics between the original and the conceptual models for two-engine systems and show that the conceptual models roughly preserve the dynamical characteristics leading up to the synchronous transitions, while some detailed dynamical structures are lost.