Influence of secondary flow channels on heat transfer and fluid flow characteristics in curved microchannel

Microchannel-assisted cooling technologies have found extremely suitable for compact heat exchangers surpassing conventional fan-assisted heat sink solutions. Though extensive research was done on straight channels, research on curved microchannel is scant. In the present study, hydraulic flow characteristics and cooling performance of curved microchannel with secondary flow (CMCSF) with four different oblique angles are investigated numerically and compared with conventional curved microchannel (CCMC). A 3D conjugate heat transfer analysis is performed for four CMCSFs and CCMC using commercial software ANSYS Fluent with Reynolds number (Re) ranging between 125 and 325. A part of fluid from main channel is diverted into the secondary channels, leading to re-initialization of boundary layers. Also, this diverted flow that is fed into adjacent main channels consecutively results in better fluid mixing. Owing to these two phenomena, there is a huge enhancement in heat dissipation through the channel. The results revealed a Nusselt number increment of up to 80.12% for CMCSF in comparison with CCMC. Moreover, the average wall temperature was recorded lowest for CMCSF with oblique angle 30 degrees, which is 8.83 degrees C lower in comparison with CCMC for same Re. For the entire range of Re considered, the overall performance of all CMCSFs was found better than CCMC with maximum performance factor of 1.62 being achieved with secondary channel orientation of 24 degrees.