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High porosity metal foams offer large surface area per unit volume and have been considered as effective candidates for convection heat transfer enhancement, with applications as heat sinks in electronics cooling. In this paper, the research progress in thermo-hydraulic performance characterization of metal foams and their application as heat sinks for electronics cooling are reviewed. We focus on natural convection, forced convection, flow boiling, and solid/liquid phase change using phase change materials (PCMs). Under these heat transfer conditions, the effects of various parameters influencing the performance of metal foam heat sink are discussed. It is concluded that metal foams demonstrate promising capability for heat transfer augmentation, but some key issues still need to be investigated regarding the fundamental mechanisms of heat transfer to enable the development of more efficient and compact heat sinks.

The present study presents a concept of biporous metal foam heat sink applicable to electronic cooling. This heat sink has two metal foam layers arranged in parallel along the primary flow direction, with different metal foam thickness, porosity, and pore density for each layer. The forced convective heat transfer in biporous metal foam heat sink is numerically investigated by employing the Forchheimer–Brinkman extended Darcy momentum equation and local thermal nonequilibrium energy equation. The effects of geometrical and morphological parameters on thermal and hydraulic performance are discussed in detail, and the heat transfer enhancement mechanism of biporous metal foam is analyzed. The thermal performance of biporous metal foam heat sink is compared with that of uniform metal foam heat sink. The results show that the thermal resistance of the biporous metal foam heat sink decreases with decrease of top layer metal foam porosity at a fixed bottom metal foam porosity of 0.9. It is seen that the biporous metal foam heat sink can outperform the uniform metal foam heat sink with a proper selection of foam geometrical and morphological parameters, which is attributed to the presence of high velocity gradient at the boundary layer that can enhance the convective heat transfer. The best observed thermal performance of biporous metal foam heat sink is achieved by employing 30 pores per inch (PPI) metal foam at the bottom layer, with a fixed 50 PPI metal foam at the top layer for the porosities of both layers equal to 0.9, and the optimal thickness of the bottom foam layer is about 1 mm.

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With the increasing popularity of fuel cells, improving their power density and the fuel cell system efficiency has become very topical. This study used the curved wing vortex generator to generate a secondary flow in the cathode flow channel to improve the performance of the proton exchange membrane fuel cell (PEMFC). The curved wing's structure and arrangement effects on the performance of fuel cells were numerically simulated. Next, to summarize the combined effects of cathode operating conditions on the performance of PEMFC, this study used the response surface method to assess the influence of operating conditions variables on the performance target of PEMFC with curved wings. The combined effects of cathode operating conditions, namely temperature, pressure, reactant stoichiometry, and relative humidity, on the system efficiency and power density of the fuel cell system were investigated.The predictive correlations between these variables were also fitted. The installation of curved wings promoted the diffusion of reactants, as well as improved the uniformity of temperature distribution and the discharge of liquid water in the fuel cell, enhancing its overall performance. Among the four operating parameters under study, the most significant effect on the fuel cell power density was provided by the temperature, followed by pressure, humidity, and reactant stoichiometry. The fuel cell efficiency was the most significantly improved by increasing the relative humidity, while temperature increase had the second-best impact, followed by pressure, and reactant stoichiometry.