Local heat transfer distribution of thermally developing region in a rectangular open-cell metal foamed channel

The local heat transfers of a thermally developing region in a rectangular channel filled with porous metal foam are investigated experimentally. A thin metal foil technique and thermal IR imaging are adopted for the measurement of the local temperature distribution. An open-cell metal foam made from copper having a porosity of 0.96 is used. The pore density of the foam is 30 PPI (pores per inch). Fluid flow characteristics like permeability and foam drag coefficient are measured by conducting local pressure drop experiments. Additionally, by utilizing local pressure measurement data, the non-dimensional pressure coefficient is quantified. The non-dimensional pressure coefficient increases in the streamwise direction, irrespective of the Reynolds number, and remains almost constant in the spanwise direction for Reynolds numbers greater than 2000. The effect of the metal foam thickness on local heat transfer and pressure drop is investigated for 13 and 20 mm thick porous metal foam. It is compared with a smooth channel to quantify the heat transfer augmentation in a channel filled with metal foam. Compared to a smooth channel, the channel with 20 mm thick metal foam shows 14 to 25 times augmentation in the Nusselt number. Similarly, the channel with 13 mm foam shows 10 to 15 times augmentation in Nusselt number. The increasing trend of the local Nusselt number is observed in a streamwise direction. The different criteria are studied to understand the thermal performance evaluation. In the Constant Pumping Power Criterion (CPPC), enhancements ranged from 3.14 to 6.72 for a 20 mm thickness and 2.62 and 4.34 for a 13 mm foam thickness. Similarly, in the Performance Evaluation Criterion (PEC), enhancement ranges from 2.23 to 4.83 for a 20 mm foam thickness and 1.89 to 3.16 for a 13 mm foam thickness. A generalized correlation is suggested to describe the average Nusselt number considering the foam material, foam thickness, pore density, and porosity as parameters.