THERMAL HYDRAULIC INVESTIGATION OF METALLIC FOAMS FOR COMPACT AND MULTI-FUNCTIONAL HEAT EXCHANGER

Compact Heat Exchangers are often used for cryogenic, air cooling and automotive systems. Indeed, they are able to transfer high amount of heat while keeping low volume and weight. For intermediate flow regime where classical enhancement techniques are no longer useful, porous fins such as metallic foams appear to be a new alternative. The purpose of this paper is to investigate experimentally and numerically the pressure drop and convective heat transfer for water flow in isotropic aluminium-alloy porous fins with different permeabilities and porosities. Comparisons of performances have been performed between metallic foams, empty duct flow. The experimental results indicate that friction and heat transfer rate are significantly affected by porosity as well as permeability of the porous fins. For intermediate Reynolds number (between 500-2,000), the metallic foams show relatively good performances in terms of heat transfer per unit pumping duty compared with conventional geometries (empty channel). For compactness of heat exchanger, the metallic foams with high pores density and low porosity are preferable. In terms of micro-mixing, metallic foams are able to enhance strongly the turbulent dissipation rate. So, metallic foams is a recommended solution for heat exchanger reactors.