Spherical and cylindrical conductive thermal diodes based on VO2
Institut Pprime, CNRS, Université de Poitiers, ISAE-ENSMA, Futuroscope, F-86962, Chasseneuil, France
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Accepted: 23 May 2019
Published online: 18 July 2019
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.
© Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature, 2019