Cooling Power and Thermal Buffering in Composite Heatsinks

Abstract

Composite thermal energy storage materials, consisting of a phase change material (PCM) coupled with a high thermal conductivity material combine favorable properties of both constituents, thereby increasing the cooling power density of the composite material. However, transient heat transfer in such composites remains challenging to predict. Previously, we introduced an approach to analyze the performance of thermal energy storage composites, assuming quasi-1D heat transport in anisotropic media with effective properties, based on the analytical solution to the Stefan phase-change problem. Here, we validate this approach using numerical results on TES composites. These results demonstrate heat flux exceeding that in pure copper, while maintaining high energy storage densities. Specifically, we report on quasi-1D heat transfer into 26.4 mm thick composites consisting of two constituents: high-conductivity metal, and high volumetric energy density PCM. We consider both constant temperature ($\Delta T = 1$ to 100°C) and constant heat flux ($q^{} = 10 ^{-1}$ to $10 ^{4}~\mathrm {W}/\mathrm{cm^{2}})$ boundary conditions, and monitor internal temperature profiles and heat fluxes. Combined, these results suggest the promise of thermal energy storage composites for high heat flux transient thermal management, and validate previously described analytical design tools used to assess such composites based on effective properties of a composite material.