Eur. Phys. J. Plus (2019) 134: 340
https://doi.org/10.1140/epjp/i2019-12782-y

Regular Article

Spherical and cylindrical conductive thermal diodes based on VO₂

Institut Pprime, CNRS, Université de Poitiers, ISAE-ENSMA, Futuroscope, F-86962, Chasseneuil, France

^* e-mail: jose.ordonez@cnrs.pprime.fr

Received: 21 October 2018
Accepted: 23 May 2019
Published online: 18 July 2019

Abstract

We theoretically and comparatively study the performance of spherical and cylindrical conductive thermal diodes operating with a phase-change material, whose thermal conductivity significantly changes in a narrow interval of temperatures. Simple analytical expressions are derived for the temperature profiles, heat flows and optimal rectification factors of both diodes. It is shown that the diode geometry has a strong impact on the temperatures and heat flows, but not so much on the diode rectification factor. Optimal rectification factors of 20.8% and 20.7% are obtained for the spherical and cylindrical diodes operating with a temperature difference of 376−300 = 76 K and 376.5-300 = 76.5 K between the terminals of VO₂ and a phase invariant material, respectively. These similar rectification factors could be enhanced with a material thermal conductivity exhibiting a higher contrast than that of VO₂ . The obtained results can thus be useful to guide the development of phase-change materials able to optimize the rectification of conductive thermal diodes with different geometries.