The manifold microchannel (MMC) heat sink differs from a traditional microchannel in that the flow length is greatly reduced to a small fraction of the total length of the heat sink. Until recently, the thermal analysis in nearly all studies ofmicrochannel heat sinks was based upon fully developed laminar flow. This is an acceptable approximation when the channel length is long relative to the entrance region, as is the case for a traditional microchannel. In the MMC, all or most of the channel is in the entrance region, and correlations for fully developed flow can greatly underpredict bath pressure drop and heat transfer.In recent years, several studies have addressed manifolding, developing flow, CFD and conjugate modeling of microchannels. These studies are reviewed and comparisons of various analytical and numerical models are offered. Of major interest are studieswhich are particular to hydraulically and thermally developing flow. In the case of fluids having low thermal conductivity, such as fluorocarbon and liquid nitrogen, an isothermal analysis modified by a fin efficiency is found to yield results acceptablyclose to those of a conjugate model.
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