Ongoing thermal management research over the past decade has largely focused on thermal control elements (TCEs) that would provide nonlinear, switchable, and active thermal control of heat with passive or active actuation mechanisms. One group of passive TCEs are solid-state thermal rectifiers (also called thermal diodes) based on junctions of materials with different thermal properties. They are of particular interest because they are relatively simple to construct and can be macroscopic. In this type of thermal diodes, phase-invariant materials with opposite dependence of thermal conductivity on temperature can be used (PIM-PIM diodes), or a combination of different phase-changing materials (PCM-PCM diodes), or a combination of phase-changing and phase-invariant materials (PCM-PIM diodes).
The most important figure of merit for a diode is the rectification factor (RF), defined as the ratio between the heat fluxes in the forward and reverse directions. The RF should be as large as possible and depends on the choice of materials, but may also depend on the topography of the material interfaces.
To date, no study has been performed that considers all possible combinations of materials with additional changes in the topography of their interfaces. Therefore, we investigated how the simultaneous effects of combinations of materials, PIM-PIM, PCM-PCM, and PCM-PIM, and a zigzag topography of their interfaces affect or change RF.
For the purpose of the study, a multiparametric numerical analysis was performed. This contribution presents the comparative results of the study and provides guidelines for the future development of macroscopic solid-state thermal diodes.