Jet-to-Porous Heat Sinks with a Variable Porous Height Layer

Abstract

The enhanced surface area and flow mixing offered by porous media are attractive features to augment the thermal performance of jet impingement heat sinks. However, the current jet-to-porous heat sinks demonstrate high pressure drop penalties and poor thermal performance due to the exacerbated jet momentum losses of the porous layer. In this study, jet impingement heat sinks with variable porous height layers are introduced to overcome the above drawbacks. The purpose of this study is using the porous domain in the selectively high-temperature areas of an annular heat sink and avoiding direct jet-to-porous interaction at the jet center. Consequently, the negative impacts of momentum loss are reduced and thus enhanced the thermohydraulic performance of jet-to-porous heat sinks. The realizable k-ε turbulent model for the fluid domain and the Darcy–Brinkman–Forchheimer equations for the porous domain are solved employing ANSYS Fluent for investigating the thermohydraulic characteristics of the system. It was shown that a jet impingement heat sink with a variable porous height layer, increasing in the radial direction, proves a significantly lower pressure drop penalty and thermal resistance than a constant porous height layer or a plain surface, while constant porous height shows lower thermohydraulic performance than the plain one at higher Re numbers. For instance, at a Re = 5,000 and HR = 0.5, the thermal resistance of a variable porous height layer is 9.63 × 10⁻⁵ (m²·K/W), which is 25% and 37% lower than that of the constant porous height surface and plain surface, respectively. The findings of the present study suggest that a variable porous height layer offers new ways to enhance the thermal management of future electronic systems.