STUDY OF MICROCHANNEL HEAT SINK PERFORMANCE WITH EXPANDED MICROCHANNELS AND NANOFLUIDS

Abstract

In this paper a microchannel heat sink with expanded microchannels and nanofluids isnumerically investigated. The object of this paper is to study and improve the cooling performanceof microchannel heat sink. Both the geometrical parameters and working fluids were studied and acomparison was made between them. Expanded microchannels (sudden expanded and diverging)were used instead of straight microchannels, also micro pin fins with square and triangular shapeswere used for heat transfer enhancement. Sudden expanded microchannels were studied withdifferent expansion ratios and expansion lengths. Three types of nanofluids (Cu-water, Al2O3-waterand Diamond-water) with volume concentration (1 – 5) % were studied as working fluids and theireffects on overall performance of heat sink were compared with pure water. The results obtainedshows that the overall performance of microchannel heat sink increased with increasing theexpansion ratio or decreasing the expansion length. For the same expansion ratio the suddenexpanded microchannels gives higher modification compared with diverging microchannels. Alsousing of nanofluids lead to enhance the heat transfer and the improvement got by geometricparameters such as using of expanded microchannels or fins is much larger than that obtained byusing nanofluids for the same heat sink.