Rapid advancement toward miniaturization has emerged with confront for superior heat dissipation techniques. Of all the available cooling systems, microchannel-based cooling systems stand out to provide better cooling performance through superior heat removal abilities. In the present study, the cooling performance and hydraulic flow characteristics of a radial curved microchannel with three curvature ratios were numerically investigated and compared with a radial straight microchannel. Unlike the conventional straight microchannels, curved channels possess better fluid mixing as a result of the centrifugal force caused due to curvature. This phenomenon has a significant effect on heat transfer and fluid flow characteristics. Work on radial curved microchannels has been scarce and there is a lot of potential to augment the heat transfer with lower pumping power particularly with a central inlet. A three-dimensional conjugate heat transfer analysis was carried out for three radial curved microchannels and a radial straight microchannel using the ANSYS Fluent commercial software with the Reynolds number range of 125–275. The results showed a Nusselt number increment of 36.38% for radial curved microchannels when compared to the radial straight microchannel. Further, the lowest average wall temperature was noted for the radial curved microchannel with a curvature ratio of 0.17 which was 15.63 °C lower when compared to that in a radial straight microchannel for the same Reynolds number. Contours of velocity and temperature are presented at various locations along the stream to aid the results. The overall performance of all three radial curved microchannels was found to be higher than that of the radial straight microchannel in the Reynolds number range considered, out of which the maximum performance factor of 1.245 was obtained for the radial curved microchannel with a curvature ratio of 0.17 as compared to the radial straight 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 , which is 8.83 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 .