Design of Manifolded 3-D μ-Coolers Enabling High Heat Flux Capillary-Driven Boiling Over Large Areas

Maintaining reasonable operating temperature for large area high heat flux microprocessors in data centers and power electronics has emerged as a major engineering challenge. Recently, we have developed a high-performance area scalable $\mu $ -cooler using capillary-driven boiling in copper inverse opals (CIOs) by designing a 3-D manifold for liquid distribution and vapor extraction. The underlying concept takes advantage of the high heat flux capillary-driven boiling of random-packed CIOs, and minimized the overall pressure drop by incorporating a silicon-based 3-D manifold structure. In this work, we have developed physics-based heat transfer and fluid dynamics modeling platform, through which we address the importance of co-design of the CIO morphology and the manifold geometry and elucidate the optimized CIO wick and manifold geometry for maximum critical heat flux (CHF) of the CIO $\mu $ -cooler. The effective wicking length in CIO, $ L_{\text {eff}}$ , which is the longest distance for the liquid to travel inside the porous media, is a critical co-design parameter for the proposed $\mu $ -cooler to achieve the highest overall CHF, lowest superheat, and sufficient liquid delivery supply over the large area microprocessor. The modeling results indicate that CHF of up to 1013 W/cm2 can be achieved for a $\mu $ -cooler size of $5\times 5$ mm2 with the co-optimization of the CIO morphology and the manifold geometry.