Impact of Secondary Channel Combined with Different Shaped Cavities and Ribs on Double Layer Microchannel Heat Sink

Abstract

AbstractDouble layer microchannel heat sink is the convenient heat sink in respect of its low temperature gradient causing lesser thermal stress and other benefits. Advantage of secondary sub-channel observed in single layered sink is the motivation for the present study. Double layer microsinks with secondary sub-channel, different shaped cavities and ribs in their flow channels are investigated. The parameters such as wall or fluid temperatures, Nusselt number ratio (Nu/Nuo) and thermal performance factor (η) have been numerically evaluated. All cases of such microchannel design investigated in this study are observed beneficial except the case having vertical secondary sub-channel without rib. Horizontal secondary sub-channel along with cavities and ribs brings proper fluid mixing into the channel so that better temperature uniformity is obtained in the substrate and fluid layers as well. The average 24% reduction in ΔTb would help such heat sinks to recover from the thermal stresses. Although higher Re suggests higher heat transfer coefficient (h) and larger Nu, medium range of Re leads to optimum pumping power and η. It has been realized that the model having secondary sub-channel along with triangular cavity and diamond-shaped rib offers higher heat transfer coefficient, maximum Nu and the best overall performance among the cases studied. This heat sink exhibits optimum Nu/Nuo of 1.43 at Re = 346 and η of 1.26 at Re = 593, respectively.KeywordsDouble layered microchannel heat sinkSecondary sub-channelMaximum bottom wall temperature differenceNusselt number ratioThermal performance factor