Jet Impingement Heat Transfer Enhancement by Packing High-Porosity Thin Metal Foams Between Jet Exit Plane and Target Surface

Abstract

High-porosity metal foams are known for providing high heat transfer rates, as they provide a significant increase in wetted surface area as well as highly tortuous flow paths resulting in enhanced mixing. Further, jet impingement offers high convective cooling, particularly at the jet footprint areas on the target surface due to flow stagnation. In this study, high-porosity thin metal foams were subjected to array jet impingement, for a special crossflow scheme. High porosity (92.65%), high pore density (40 pores per inch (ppi)), and thin foams (3 mm) have been used. In order to reduce the pumping power requirements imposed by full metal foam design, two striped metal foam configurations were also investigated. For that, the jets were arranged in 3 × 6 array (x/dj = 3.42, y/dj = 2), such that the crossflow is dominantly sideways. Steady-state heat transfer experiments have been conducted for varying jet-to-target plate distance z/dj = 0.75, 2, and 4 for Reynolds numbers ranging from 3000 to 12,000. The baseline case was jet impingement onto a smooth target surface. Enhancement in heat transfer due to impingement onto thin metal foams has been evaluated against the pumping power penalty. For the case of z/dj = 0.75 with the base surface fully covered with metal foam, an average heat transfer enhancement of 2.42 times was observed for a concomitant pressure drop penalty of 1.67 times over the flow range tested.

A Review of Thermo-Hydraulic Performance of Metal Foam and Its Application as Heat Sinks for Electronics Cooling

“…Apart from the traditional duct type or single jet impingement, metal foam subjected to jet array impingement was also investigated. Singh and coauthors [115][116][117][118][119] have conducted extensive investigations on the forced convection in high porosity metal foams under jet array impingement. Singh et al [115] experimentally and numerically studied the forced convective heat transfer in aluminum foams (porosity of 0.94-0.96 and pore density of 10-40 PPI) subjected to jet array (5 Â 5) impingement.…”

Heat Transfer Augmentation through Different Jet Impingement Techniques: A State-of-the-Art Review

“…This augmentation in the local Nu was caused by the vigorous nature of the interaction between impinging jets and an increase in the magnitude of mixing and turbulent transport. Jet impingement heat transfer was studied by Madhavan et al [67] by using high-porosity metal foams between the jet plate and the target plate. High-porosity metal foams are used due to their high heat transfer rate.…”

Opportunities in Jet-Impingement Cooling for Gas-Turbine Engines

“…Experimental work used thin foams mounted onto the substrate. Several other investigations followed on this concept, where high-porosity and high pore-density thin aluminum and copper foams were used for jet impingement heat transfer enhancement [28,106,107]. One potential extension of this work can be the fouling of metal foams and its effect on the heat transfer especially for land-based largescale turbines, that can have a significant amount of corrosion and oxidation (presence of oxidized powders) that foul film holes and impingement holes.…”

“…Madhavan et al [106] used metal foam between the jet and the target plate to enhance impingement heat transfer. A marked increase in heat transfer coefficient was noted with a fully packed chamber.…”