Investigation of Flow and Heat Transfer Performance of Double-Layer Pin-Fin Manifold Microchannel Heat Sinks

The manifold microchannel (MMC) heat sink is characterized by high heat transfer efficiency, high compactness, and low flow resistance. It can be an effective method for the high-flux removal of high-power electronic components. To further enhance the performance of the MMC, a double-layer pin–fin MMC structure was designed. The thermodynamic properties, including the flow and heat transfer characteristics, were numerically investigated using ANSYS Fluent with deionized water as the working liquid. Compared with the single-layer MMC, the temperature uniformity is better, the pressure drop is lower, and the comprehensive performance is improved at the cost of slightly larger thermal resistance for the double-layer MMC. The geometric effects on the thermodynamic performance were also analyzed. The results show that among the pin–fin structures with round, diamond-shaped, and rectangular cross-sections, the round pin–fins demonstrate the best comprehensive performance and the minimal thermal resistance. Under the same inlet velocity, the thermal resistance is decreased, and the comprehensive performance is first increased and then decreased as the pin–fin size increases. In addition, it is recommended to adopt a larger height ratio for low inlet velocity and a smaller height ratio for high inlet velocity.