Convective heat transfer and flow enhancement using nanofluids in divergent-convergent minichannel heatsink.

Abstract

The recent trend in technological advancements in the field of electronic devices offer high-performance compact systems. However, highly concentrated heat flux restricted their efficiency. Many researchers exploit different passive heat transfer techniques like geometry modification to alleviate high heat flux. Research is inadequate despite the potential of divergent-convergent minichannel in mixing flow and a higher proportion of surface area to volume than conventional channels. This study combines a geometrical modification with innovative high thermal conductive nanofluid as hybrid passive techniques. The numerical analysis employed a commercial CFD code based on the finite volume method. The investigation of forced convective heat transfer and nanofluids’ flow was achieved with single-phase and two-phase mixture models in a divergent-convergent minichannel heatsink (DCMH) having a hydraulic diameter of 1.42mm. The numerical investigation employed Al2O3/water and CuO/water nanofluids with 0 - 2.5 volume%, fluid velocity from 3 – 6 m/s (corresponding to Reynolds number 5000 – 10000), and the inlet temperature 303K. The two-phase model exhibits better agreement with established correlation than the single-phase model. The results found that the effects of principal parameters on the chip heat flux demonstrated the heat transfer coefficient’s growth with a rise in volume fractions and fluid velocity. Both nanofluids indicated better performance enhancement than water. Al2O3/water and CuO/water nanofluids augment over water by about 6.44% and 8.33% for 2.5 vol.%. Also, pressure loss rises when the velocity increases. The pressure loss relative to water at 2.5 vol.% and 5.5 m/s yields 15.14% and 18.56 % for Al2O3/water and CuO/water. The highest pumping power is 0.057 W for all the cases, which indicates the pumping demand is much lower than 1.0 W. The overall results established that the combined effects of DCMH and nanofluids have significantly improved the heat sink’s hydrothermal performance and can provide the desired heat dissipation from the enclosed chips in compact electronic devices.