A quantum Stirling heat engine operating in finite time

TL;DR

This paper analyzes a quantum Stirling heat engine operating in finite time, demonstrating how its efficiency approaches Carnot limits at slow speeds and identifying optimal operating speeds for maximum power.

Contribution

It introduces a finite-time model of a quantum Stirling engine with a time-dependent potential barrier, highlighting the importance of finite-time effects on efficiency and power.

Findings

Efficiency approaches Carnot limit at slow operation

Maximum power occurs at an intermediate speed

Finite-time effects significantly influence engine performance

Abstract

In a quantum Stirling heat engine, the heat exchanged with two thermal baths is partly utilized for performing work by redistributing the energy levels of the working substance. We analyze the thermodynamics of a quantum Stirling engine operating in finite time. We develop a model in which a time-dependent potential barrier changes the energy-level structure of the working substance. The process takes place under a constant interaction with the thermal bath. We further show that in the limit of slow operation of the cycle and low temperature, the efficiency of such an engine approaches Carnot efficiency. We also show that the maximum output power , for the strokes that affect the energy levels, is obtained at an intermediate operating speed, demonstrating the importance of a finite-time analysis.