Designing of microsink to maximize the thermal performance and minimize the Entropy generation with the role of flow structures

Abstract

Designing a novel microsink with geometric structures for better cooling of compact tiny-sized electronic devices at lower pressure drop is the utmost desire of recent technological development. A three-dimensional numerical study of conjugate heat transfer has been carried out to propose a microsink with the disruptive structures placed symmetrically about the vertical midplane in a rectangular microchannel. The channels are made of silicon with the structures like triangular cavity (TC), secondary branches (SB) and blockage (B) with water as a working fluid. The effects of these structures are illustrated by heat transfer, friction factor, thermal performance (TP), entropy generation (EG) due to heat transfer, entropy generation (EG) due to pressure drop and entropy generation number (EGN) over the range of Reynolds number (Re) from 146 to 618. The best channel has been identified from the rigorous analysis among the microchannels with the only triangular cavity (TC), triangular cavity with the secondary branch (TCSB) and triangular cavity along with secondary branch and blockage (TCSBB) from the highest TP and minimum EGN. These two models have been chosen to find out a best channel as criteria of highest heat transfer with the same pumping power from the highest TP and minimum temperature of electronic sink from the lowest EGN. The highest TP and lowest EGN are obtained from the channel TCSBB compared to other three channels. The parametric variation of relative angle of the secondary branch, length of cavity, width of secondary branch and cavity, pitch distance have been varied to find the maximum TP and the minimum EGN. The values have been obtained equal to 2.01 and 0.41 respectively at Re of 480. The significant roles of longitudinal vortex on the augmentation of heat transfer and minimizations of EG mechanism with the alteration of geometrical parameters are exploited and described explicitly. Finally, the correlations of heat transfer enhancement and rise in pressure drop dependent on geometric parameter have been inscribed based on Response surface methodology.