Irreversibility and entropy production of a thermally driven micromachine

TL;DR

This paper analyzes the non-equilibrium thermodynamics of a three-sphere micromachine driven by thermal differences, calculating irreversibility, entropy production, and efficiency within a stochastic Langevin framework.

Contribution

It provides a detailed theoretical analysis of entropy production and efficiency in a thermally driven micromachine with asymmetric thermal and mechanical properties.

Findings

Maximum irreversibility occurs at a finite time related to spring relaxation.

Steady-state entropy production depends on temperature and friction asymmetries.

Diffusion coefficient varies with temperature differences and friction coefficients.

Abstract

We discuss the non-equilibrium properties of a thermally driven micromachine consisting of three spheres which are in equilibrium with independent heat baths characterized by different temperatures. Within the framework of a linear stochastic Langevin description, we calculate the time-dependent average irreversibility that takes a maximum value for a finite time. This time scale is roughly set by the spring relaxation time. The steady-state average entropy production rate is obtained in terms of the temperatures and the friction coefficients of the spheres. The average entropy production rate depends on thermal and/or mechanical asymmetry of a three-sphere micromachine. We also obtain the center of mass diffusion coefficient of a thermally driven three-sphere micromachine as a function of different temperatures and friction coefficients. With the results of the total entropy production rate and the diffusion coefficient, we finally discuss the efficiency of a thermally driven micromachine.