Modulation and amplification of radiative far field heat transfer: Towards a simple radiative thermal transistor

TL;DR

This paper demonstrates that phase change materials can be used to create a simple radiative thermal transistor capable of modulating and amplifying heat transfer through phase transitions, with potential practical implementations.

Contribution

It introduces a straightforward model for a radiative thermal transistor using PCM between blackbodies, highlighting the effects of reflectivity and transition temperature on modulation and amplification.

Findings

Transistor effect occurs when PCM's critical temperature is between blackbody temperatures.

Higher reflectivity in the metallic state enhances switching.

Stiffer PCM transitions lead to greater thermal amplification.

Abstract

We show in this article that phase change materials (PCM) exhibiting a phase transition between a dielectric state and a metallic state are good candidates to perform modulation as well as amplification of radiative thermal flux. We propose a simple situation in plane parallel geometry where a so-called radiative thermal transistor could be achieved. In this configuration, we put a PCM between two blackbodies at different temperatures. We show that the transistor effect can be achieved easily when this material has its critical temperature between the two blackbody temperatures. We also see, that the more the material is reflective in the metallic state, the more switching effect is realized whereas the more PCM transition is stiff in temperature, the more thermal amplification is high. We finally take the example of VO2 that exhibits an insulator-metallic transition at 68{\textdegree}C. We show that a demonstrator of a radiative transistor could easily be achieved in view of the heat flux levels predicted. Far-field thermal radiation experiments are proposed to back the results presented.