Effect of utilizing roughed surfaces within a curved microchannel having cavities on the thermo-hydraulic performance

Curved microchannels with cavities have warranted significant interest from researchers due to their potential to improve the thermo-hydraulic performance of micro-scale hot components. However, there is a scarcity of information concerning the impact of using rough surfaces to such devices for heat transfer enhancement. To this focus, CFD simulations are conducted on a curved microchannel featuring cavities and different surface roughness without identifying any symmetrical planes. The microchannel comprises two curved segments, having a hydraulic diameter (Dh) of 0.3mm. Aluminum serves as a solid material, whereas water functions as a coolant. Reynolds number (Re) varies from 10 to 800. A constant heat flux of 30kW/m? is applied. Three cases with varying surface roughness (Ks/D) are analyzed: 0%, 3%, and 9%. The findings indicated that using rough surfaces is helpful for effective turbulence-inducing through boundary layer disturbing for heat transfer enhancement at low Re. An enhancement in heat transfer of 22.3% is observed, attributable to the roughness of 9% at Re=800, compared to the smooth baseline scenario, while the overall performance improved by about 12.2%. Two correlations are developed as a function of Re and Ks/D for Nusselt and Poiseuille numbers, which are believed to be useful for designers of microchannels.