Convective Heat Transfer in Porous Media and Development of Micro-channel Cooling

自从硅集成电路（IC）发明以来，电路集成已经有了超过五个数量级的增长。电路集成度的提高导致芯片级的功率密度更高。今天的芯片耗散在10w/cm^2的数量级是相对常见的，并且预计未来芯片的耗散要求在100w/cm^2的数量级。微通道散热片是对高热流密度表面具有潜在冷却能力的候选材料之一。本文对微通道散热器的传热和流体流动进行了实验和分析研究。制作并测试了不同通道宽度和翅片高度的水冷铜散热器。在给定的进口冷却液温度Ti和散热器的最高允许温度Tmax条件下，特别关注了散热器的可带走热量。换热结果表明，在Ti=20℃，Tmax=80℃时，现有散热器的散热能力可达数百W/cm^2。同时对微通道进出口压力损失进行了测量，发现对于固定排热，存在使压力损失最小的最优通道宽度。为了优化设计微通道，还开发了充分发展的层流通道流分析。分析较好地预测了实验结果。

Since the invention of the silicon integrated circuit (IC), there has been in excess of a five-orders-of-magnitude increase in circuit integration. This increase in circuit integration causes higher power density at the chip level.It is relatively common for today's chip to dissipate on the order of 10w/cm^2, and dissipation requirements on the order of 100w/cm^2 are projected for tomorrow's chip. A micro-channel heat sink is one of the candidates that have potential capability of cooling for such high heat flux surface. In this study, heat transfer and fluid flow were investigated both experimentally and analytically on the micro-channel heat sinks. Water-cooled, copper heat sinks with different channel widths and fin heights were fabricated and tested.Special attentions are focused on the removable heat by the heat sinks under the given conditions of the inlet coolant temperature Ti, and the maximum allowable temperature Tmax, of the heat sinks. The results of the heat transfer show very high cooling capability, the heat flux of several hundreds W/cm^2 can be dissipated by the present heat sinks at Ti=20C and Tmax=80C.Pressure losses between the inlet and outlet of the micro-channel were also measured, and it was found that the optimal channel width, which can minimize the pressure loss, exists for fixed removed heat. The fully-developed, laminar, channel flow analysis was also developed to make an optimum design of micro-channels. The analysis predicts fairly well the experimental results.