Thermodynamic engine powered by anisotropic fluctuations

TL;DR

This paper introduces an autonomous thermodynamic engine driven by anisotropic fluctuations, utilizing a Brownian gyrator concept with an electrical model to generate sustained power, relevant for nano-engines and biological systems.

Contribution

It presents a novel autonomous engine design powered by anisotropic thermal fluctuations, including a detailed electrical model and stability analysis for sustained power output.

Findings

Engine can sustain stable periodic motion

Electrical model demonstrates power generation from thermal fluctuations

Connection established to macroscopic Stirling engines

Abstract

The purpose of this work is to present the concept of an autonomous Stirling-like engine powered by anisotropy of thermodynamic fluctuations. Specifically, simultaneous contact of a thermodynamic system with two heat baths along coupled degrees of freedom generates torque and circulatory currents -- an arrangement referred to as a Brownian gyrator. The embodiment that constitutes the engine includes an inertial wheel to sustain rotary motion and average out the generated fluctuating torque, ultimately delivering power to an external load. We detail an electrical model for such an engine that consists of two resistors in different temperatures and three reactive elements in the form of variable capacitors. The resistors generate Johnson-Nyquist current fluctuations that power the engine, while the capacitors generate driving forces via a coupling of their dielectric material with the inertial wheel. A proof-of-concept is established via stability analysis to ensure the existence of a stable periodic orbit generating sustained power output. We conclude by drawing a connection to the dynamics of a damped pendulum with constant torque and to those of a macroscopic Stirling engine. The sought insights aim at nano-engines and biological processes that are similarly powered by anisotropy in temperature and chemical potentials.