An investigation into the thermal rectification in one-dimensional asymmetric systems

Abstract

The thermal rectification phenomenon in a one-dimensional asymmetric system of two thin films with different temperature-dependent thermal conductivities is studied. Based on the traditional thermal diffusion equation, the optimization condition for maximizing the thermal rectification ratio is re-examined; a new sufficient condition is found that the interface temperatures in the forward and reverse heat transfer directions should be equal, regardless of how the thermal conductivities depend on temperature. In other words, the thermal rectification ratio is maximized when the temperature dependence of the thermal conductivity over the entire operating temperature range is fully exploited. This sufficient condition can be used to find out the optimal geometric parameters of nanostructures which determine the effective thermal conductivity. An illustration of an asymmetric system composed of monolayer graphene sheet (GS) and graphene nanomesh (GNM) is presented. This study is beneficial to the development of thermal devices such as thermal resistors, thermal diodes, and thermal logic circuits.