Capillary-driven two-phase cooler for high-heat-flux electronics using copper wire mesh manifold and enhanced copper inverse opal wick heat sink

초록

Capillary-driven two-phase micro-cooler is a promising thermal management solution for passive cooling in high-heat-flux electronics applications. In this study, we have developed an area-scalable two-phase capillary-driven cooler that integrates a silicon pin array coated with copper inverse opal (CIO) wick with a copper wire mesh 3D manifold over a 5 × 5 mm2 heated area and utilizes water as the working fluid. We achieved a critical heat flux of ≈ 650 Wcm−2, and two-phase heat transfer coefficients ≈ 1 MWm−2 °C−1. We consider three different wick structures (a planar CIO layer, a sparse square pin array coated with CIO layer, and a dense square pin array coated with CIO layer), three inlet flow rates of 5, 10, and 15 g(min)−1, and two types of copper wire mesh 3D manifolds with different spacings between neighboring wire mesh layers of 550 and 650 μm, respectively. The two-phase heat transfer at critical heat flux (CHF) for CIO wick layer on sparse and dense silicon pin array increases by ≈ 47% and ≈ 120%, respectively, compared to that of the baseline planar CIO wick. This enhancement in the two-phase heat flux is directly correlated to the increase in the effective (extended) silicon (wick) surface area. Our systematic study concludes that the CHF values are limited by the wick structures rather than the copper wire mesh 3D manifold for baseline planar CIO wick and sparse silicon pin array covered with CIO layer. However, for the dense silicon pin fins covered with CIO layer, either the wick or the copper wire mesh manifold could be limiting the CHF; further study of the micro-coolers with larger heated footprint is required to understand the limiting factor. Furthermore, it is found that the 3D manifold with a center-to-center wire-mesh spacing of 550 μm (9 wire meshes) exhibit better coolant supply across the wick, showing a higher CHF, compared to the 3D manifold with a center-to-center wire-mesh spacing of 650 μm (8 wire meshes), owing to the larger number of parallel wire-mesh capillary pathways (9 vs. 8) and the shorter maximum lateral distance (≈ 275 μm vs. ≈ 325 μm) from the nearest mesh to the wick. Finally, we provided a comprehensive performance review of the capillary-based micro-coolers with and without 3D manifolding scheme to benchmark the present work. The next generation of copper wire mesh manifold will be optimized to cover large, heated area as well as improving the permeability of the copper wire mesh to support high two-phase heat flux.

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