Water cooled minichannel heat sinks for microprocessor cooling: Effect of fin spacing

For effective thermal management of high heat generating microprocessors, five different heat sinks with fin spacings of 0.2 mm, 0.5 mm, 1.0 mm, and 1.5 mm along with a flat plate heat sink were investigated. Microprocessor heat was simulated by a heated copper block with water as a coolant. At a heater power of 325 W, the lowest heat sink base temperature of 40.5 C was achieved by using a heat sink of 0.2 mm fin spacing which was about 9% lower than the best reported base temperature of 44 C using a nanofluid with commercial heat sink in the open literature. The base temperature and thermal resistance of the heat sinks were found to drop by decreasing the fin spacing and by increasing volumetric flow rate of water circulating through the heat sink. For a flat plate heat sink, the maximum thermal resistance was 0.216 K/W that was reduced to as little as 0.03 K/W by using a heat sink of 0.2 mm fin spacing. The overall heat transfer coefficient was found to be 1297 W/m² K and 2156 W/m² K for the case of a flat plat and 0.2 mm fin spacing heat sinks, respectively, the latter showed about two-folds enhancement compared to the former.