Experimental investigation of oblique finned microchannel heat sink

Sectional oblique fins are employed in contrast to the continuous fins in order to modulate the flow in microchannel heat sink. The breakage of continuous fin into oblique sections causes the thermal boundary layers to be re-initialized at the leading edge of each oblique fin and reduces the boundary-layer thickness. This regeneration of the entrance effect causes the flow to be always in a developing state thus resulting in better heat transfer. In addition, the presence of the smaller oblique channels causes a fraction of the flow to branch into the adjacent main channels. The secondary flows thus created improve fluid mixing which serves to further enhance the heat transfer. Experimental investigation employing copper based microchannels demonstrated that the combination of the re-entrance and secondary flow effect from oblique fins results in a much improved heat transfer performance against the conventional microchannel. The average Nusselt number, Nuave, for the copper microchannel heat sink which uses water as the working fluid can increase as much as 80%, from 8.6 to 15.8. The augmented convective heat transfer leads to 18% reduction in the total thermal resistance, while the maximum base temperature rise above inlet fluid temperature decreases 9.3°C, from 50.0°C to 40.7°C. Interestingly, there is only little or negligible pressure drop penalty associated with this novel heat transfer enhancement scheme in contrast to conventional enhancement techniques.