Abstract

Forced convective enhanced heat transfer performance of air flows (50 = Re = 4000) in novel slotted sinusoidal wavy-plate-fins is investigated both experimentally and computationally. The slotted wavy fin core evaluated in the experiments was produced by direct metal laser sintering. Compared with the equivalent non-slotted core, results indicate that the pressure drop was reduced by as much as 31% whereas the heat transfer had no appreciable change. This very attractive enhancement by way of pressure drop reduction was further explored in a three-dimensional computational analysis. It is seen that a significant part of pressure loss in plain unslotted wavy-fin channels is due to form drag induced by flow recirculation in the trough regions. This is shown to be reduced substantially if the fins are slotted at large form drag locations. Their position and size, characterized respectively by phase angle and dimensionless slot size, are varied in the simulations to explore their role in the enhanced thermal-hydrodynamic performance. One such modified design exhibits a characteristically unusual performance at low Re, where a reduction in pressure loss (-16.8%) is also accompanied with an improvement in heat transfer (+17%). At high Re, however, a slight decline in heat transfer (-7.6%) is evidenced but the pressure drop is nearly cut in half (-46.6%). Moreover, the overall thermal-hydrodynamic performance based on the metric of fixed heat transfer rate and pressure drop constraint shows that ~15% reduction in the required heat transfer surface area can be achieved.

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