Irreversibilities and efficiency at maximum power of heat engines: illustrative case of a thermoelectric generator

TL;DR

This paper investigates the efficiency at maximum power of thermoelectric generators, demonstrating how different sources of irreversibility influence efficiency and revealing a continuous transition between two efficiency regimes.

Contribution

It provides a detailed analysis of how internal and external irreversibilities affect the maximum power efficiency in thermoelectric generators, highlighting a universal efficiency behavior.

Findings

Efficiency at maximum power depends on the source of irreversibility.

A continuous transition exists between Curzon-Ahlborn and universal efficiencies.

Dissymmetry in thermal contact conductance affects efficiency outcomes.

Abstract

Thermoelectric generators are particularly suitable to investigate the irreversible processes which govern the coupled transport of matter and heat in solid-state systems. We study the efficiency at maximum power in the strong coupling regime, where the thermal flux is proportionnal to the electrical current inside the generator. We demonstrate that depending on the source of irreversibility we obtain either the Curzon-Ahlborn efficiency for external dissipation or a universal efficiency at maximum power for internal dissipation. A continuous change between these two extremes is evidenced. Effects of dissymetry of thermal contact conductance are also investigated.