Flow and heat transfer irreversibility in partial filled metal foams

Abstract

This paper presents the analysis of entropy generation, exergy and heat transfer through metal foams partially and completely filled in a vertical channel. The assembly of heater located in between two aluminum plates is located at the core of the channel and for the purpose of heat transfer augmentation aluminum metal foam of pore density 10 with porosity 0.95 are located on either side of the plates. Four different filling rates of 25%, 50%, 75% and 100%, and three metal foam thicknesses of 10 mm, 20 mm and 30 mm are examined in this research for a fluid velocity ranging from 0.1 to 3 m/s. Darcy Extended Forchheimer (DEF) model and local thermal non-equilibrium (LTNE) model is used for forecasting the flow features and heat transfer through the metal foam. The numerical methodology adopted in this research is confirmed by comparing the results with the literature and found fairly good agreement between them. The flow physiognomies in terms of friction factor, heat transfer performance in terms of Nusselt number and performance factor, exergy transfer in terms of mean exergy based Nusselt number, and entropy generation i.e., total irreversibility in terms of Bejan number and entropy generation number are presented and discussed. Results showed that the effect of partially filled metal foams are found to be better in terms of entropy generation, and exergy transfer, and the effect of higher metal foam thickness is found to be better in terms of exergy and heat transfer, but in terms of total entropy generation resulting in terms of both heat transfer and pressure drop smaller metal foam thickness exhibits better performance.