Numerical Investigation of Spray Cooling-Based Thermal Management of Extreme Power Densities using Anisotropic Composite Heat Spreaders

Recent advancements in high thermal conductivity materials offer new possibilities in heat spreader designs that can tackle near-junction hotspot/focal spot thermal management in tandem with the active cooling methods. This study aims to characterize two-phase spray cooling performance utilizing an advanced composite heat spreader design that implements isotropic and anisotropic material (i.e., CVD diamond, graphite, and pyrolytic graphite) layers near the heat source to laterally spread the heat flux to manageable levels towards achieving reliable and efficient operation of ultra-high heat flux (>1,000 W/cm²) devices. The study incorporates experimentally obtained spray cooling performance data (particularly the heat transfer coefficient, as a key parameter) with alcohol/water binary mixtures, and numerically investigates the capabilities of the described composite heat spreader for thermal management of a simulated 1 mm² heat source. A thermal management technology that integrates the capabilities of two-phase spray cooling with the advanced heat spreaders would achieve a novel cooling method, alleviate thermal limits to the advancement of the most challenging power electronics applications involving ultra-high heat fluxes, and provide improved thermal performance and design (with reduced size, weight, and power).