Efficiency of heat engines coupled to nonequilibrium reservoirs

TL;DR

This paper analyzes quantum heat engines operating with nonequilibrium reservoirs, deriving their maximum efficiency and efficiency at maximum power using entropy production and effective temperature concepts.

Contribution

It introduces a framework to evaluate quantum heat engine efficiency with nonequilibrium reservoirs and generalizes the second law for such systems.

Findings

Maximum efficiency expressed via an effective temperature.

Efficiency at maximum power computed for engineered reservoirs.

Generalization of the Clausius statement to nonequilibrium conditions.

Abstract

We consider quantum heat engines that operate between nonequilibrium stationary reservoirs. We evaluate their maximum efficiency from the positivity of the entropy production and show that it can be expressed in terms of an effective temperature that depends on the nature of the reservoirs. We further compute the efficiency at maximum power for different kinds of engineered reservoirs and derive a nonequilibrium generalization of the Clausius statement of the second law.