Single-Phase Cryogenic Flows Through Microchannel Heat Sinks

Cryogenic fluids are used widely in several thermal management applications such as in regenerative cooling of rocket engine combustor liners, missile warning receivers, satellite tracking systems and cryo-adsorbent hydrogen storage systems. Single phase laminar flow and heat transfer rate of liquid nitrogen in microchannels is studied experimentally in this paper.The performance of two distinct geometries of microchannel heat sinks are evaluated and compared for simultaneous developing laminar flow in the Reynolds number range from 180 to 610. The first geometry pertains to parallel microchannels while the second corresponds to a staggered microscale pin fin array. Two parallel microchannel geometries having identical widths of 140μm and identical laminar thermal resistances but with different aspect ratios of 4.7 and 7.6 are compared. The pin fin heat sink consisted of square pins of 395μm side and oriented at 45 degrees to the flow. All three heat sinks have identical heat source surface area.Results are presented in a non-dimensional form in terms of the friction factor, Nusselt, Reynolds numbers and compared with the predictions of existing correlations in the literature for parallel microchannels and micro pin fin heat sinks.© 2014 ASME