ENHANCING HEAT TRANSFER RATES ACROSS DIFFERENT FLOW REGIMES USING PERFORATED-FINNED HEAT SINKS
Forced convection thermal performances of perforated-finned heat sinks (PFHSs) across different flow regimes are experimentally studied and results are compared to those for a solid-finned heat sink (SFHS). The perforations have a square cross-sectional area with a side dimension of 5.08 mm and are located equidistant along the length of the lateral surface of the fins. The porosity ranged from 0.15 to 0.55. The pressure drop across the PFHSs increased monotonically as the porosity increased, mainly due to the cavities formed over perforations. Since the higher flow resistance for a PFHS results in a lower volumetric flow rate compared to a comparable SFHS, PFHSs are potentially promising devices to enhance heat transfer rates without increasing pumping power. Local heat transfer coefficients (h) are computed from the experimental data and presented in the form of hA where A is the local heat transfer area. The lowest hA among all PFHSs was obtained by the largest porosity, which indicates an existence of a trade-off between the solid surface area of the fin with the void volume as such increasing the porosity beyond that threshold results in deterioration of thermal performance. This study would reveal some complicated physics in PFHSs as frequent changing the maximum and minimum local hAs by different porosities. A key result is that for some porosities, the thermal resistance can be reduced while maintaining a fixed pumping power; therefore, some PFHSs can handle higher heat loads without incurring a penalty in the pumping power.