A numerical investigation of wavy microchannels with secondary branches under non-uniform heating

The maneuverability of flight vehicles and their significant working power cause high non-uniform heat flux in their electrical components. Meanwhile, the package structure of components leads to a hostile heat dissipation environment in which air cooling cannot be realized, and a heat sink with conventional dimensions cannot meet the strong heat dissipation requirement, so the microchannel heat sink (MCHS) has been proposed instead. The mode of secondary branches of microchannel heat sink on the current research was full-opening one crossing the channel wall, the semi-opening secondary branch has rarely been studied yet. Meanwhile, the influences of secondary branches on the flow and heat transfer performance and temperature uniformity of an MCHS under non-uniform heat flux have not been mentioned. Hence, in this paper, a numerical model for a MCHS with secondary branches is proposed to enhance the thermal performance of heat sinks and to improve the temperature uniformity of the substrates. Considering the symmetry structure of the heat sinks, the computational domain is constructed by two parallel sinusoidal channels with secondary branches on the adjacent channel wall. The effects of geometric factors, such as the cross-sectional opening degree and the arrangement of branches on the thermal performance of the heat sinks, are studied. The results show that compared with the conventional wavy MCHS, the secondary branches promote fluid mixing efficiency, enhance thermal performance, and provide dynamic adjustment of the flow distribution. Furthermore, a heat sink with middle semi-opening branches shows superior thermal performance, while the one with interlaced semi-opening branches shows better temperature uniformity of substrate. Meanwhile, an MCHS with secondary branches has a much larger Fc and a smaller Ṡgen/Ṡgen, 0 than those of a heat sink with no branches.