# Performance optimization of low-dissipation thermal machines revisited

## TL;DR

This paper introduces a simplified method for optimizing the performance of low-dissipation thermal machines, providing closed-form solutions for various objectives in engines and refrigerators.

## Contribution

It proposes an alternative optimization scheme that simplifies calculations and yields analytical expressions, improving upon standard methods for finite-time Carnot machine performance.

## Key findings

- Closed-form expressions for figures of merit
- Simplified optimization procedure
- Effective for engines and refrigerators

## Abstract

We revisit the optimization of performance of finite-time Carnot machines satisfying the low-dissipation assumption. The standard procedure seeks to optimize an objective function, such as power output of the engine, over the durations of contacts between the working medium and the heat reservoirs. This procedure may lead to unwieldy equations at the optimum of some objective functions. We propose an alternate scheme in which the output or input work is first optimized for a given cycle time, followed by an optimization of another objective function over the cycle time. The optimal behavior is thus obtained in a much simplified manner, with closed-form expressions for figures of merit. The approach is demonstrated for various objective functions, both for engines as well as refrigerators.