Optimizations of Multilevel Quantum Heat Engine with N Noninteracting Fermions Based on Lenoir Cycle

TL;DR

This paper optimizes a multilevel quantum heat engine with noninteracting fermions based on the Lenoir cycle, analyzing effects of heat leakage on efficiency and power, and examining Clausius relations at various leakage levels.

Contribution

It introduces an optimization framework for a quantum heat engine with fermions, considering heat leakage effects and analyzing reversible conditions and efficiency limits.

Findings

Efficiency decreases with increased heat leakage.

Engine efficiency returns to zero at higher compression ratios with leakage.

Reversible processes occur at specific compression ratios depending on heat leakage.

Abstract

We consider optimizations of Lenoir heat engine within a quantum dynamical field consisting of $N$ noninteracting fermions trapped in multilevel infinite potential square-well. Fermions play role as working substance of the engine with each particle nested at different level of energy. We optimized this quantum heat engine model by analysing the physical parameter and deriving the optimum properties of the engine model. The model we investigated consists of one high-energy heat bath and one low-energy sink bath. Heat leakage occurs between these two bathes as expected will degenerate the efficiency of quantum heat engine model. The degeneration increased as we raised the constant parameter of heat leakage. We also obtained loop curves in dimensionless power vs. efficiency of the engine, which efficiency is explicitly affected by heat leakage, but in contrast for the power output. From the curves, we assured that the efficiency of the engine would go back to zero as we raised compression ratio of engine with leakage. Lastly, we checked Clausius relations for each model with various levels of heat leakage. We found that models with leakage have a reversible process on specific compression ratios for each variation of heat leakage. Nevertheless, the compression ratio has limitations because of the $\oint dQ/E>0$ after the reversible point, i.e. violates the Clausius relation.