The influence of high-porosity nickel foam on the transition flow regime for heat transfer and pressure drop characteristics in a rectangular channel

Abstract

This study investigates an approach of enhancing heat transfer in heat exchangers by increasing heat transfer area of the heat exchanger, and this is done by filling the rectangular test section with porous media to extend the heat transfer surface area and thus enhance the heat transfer. The permeability of the used nickel foam is determined by conducting pressure drop measurements through the nickel foam in the test section, and the heat transfer and pressure drop parameters are measured and compared with the empty test section. The results show that the values of the friction coefficient are 24.5 times the values of the empty test section, and the Nusselt number is observed to be three times higher when using nickel foam than that without foam in the test section. No transition regime is observed for the foam-filled test section on both heat transfer and pressure drop results; however, the transition from laminar to turbulent is found for the test section without foam. The results of thermal factor of the foam-filled test section show a thermal performance factor higher than unity through the entire Reynolds number range of 2000–6500, with better thermal performance factor at lower Reynolds number.