Thermal hydraulic performance of a double-layer microchannel heat sink with channel contraction

The present study investigates numerically the effects of vertically tapered and converging channel of a double layered microchannel heat sink (DL-MCHS) on its thermal and hydraulic performance. The problem is solved using a three-dimensional conjugate heat transfer model with counterflow between upper and lower channels. The taper effect is studied with different channel height contraction ratio R-h. Numerical results generally shows vertical taper effect of the channel contribute to higher thermal performance as compared to conventional design of straight channel but the pumping power required increases as the channel height contraction ratio increases. Thermal hydraulic performance factor eta is employed to assess the sustainability of the taper design of microchannels by considering both thermal and hydraulic performances. The results of thermal enhancement factors are below unity, indicating that the DL-MCHS with channel height contraction design is not a sustainable solution as compared to the DL-MCHS with conventional straight channel design when hydraulic performance is taken into account. (C) 2016 Published by Elsevier Ltd.