Heat transfer enhancement in microchannel heat sink by wavy channel with changing wavelength/amplitude

An improved design of wavy microchannel heat sink with changing wavelength or/and amplitude along the flow direction is proposed. The thermal resistance R and the maximum bottom wall temperature difference Delta T-b,T-max for the new design are compared with those for the straight and the original wavy design under a constant pumping power. The results show that the new design performance is enhanced significantly with lower R and smaller Delta T-b,T-max when the wavelength of wavy units decreases or the amplitude increases. The enhancement becomes more remarkably when the absolute value of the wavelength difference Delta lambda or amplitude difference Delta A between two adjacent wavy units increases. The performance can be further improved by simultaneously increasing the absolute values of Delta lambda and Delta A. Moreover, as compared with the straight and the original wavy microchannel heat sink, the reductions in R and Delta T-b,T-max for the new design is found more significant for the heat sink with a smaller channel aspect ratio. The heat transfer enhancement is attributed to the formation of vortices in the channel cross sections caused by the curved walls, which promotes the coolant mixing and enhances the convective heat transfer between coolant and channel walls. (C) 2017 Elsevier Masson SAS. All rights reserved.