Optimizing heat transfer within a rectangular channel through intermittent metal foam block configurations: A numerical study

Abstract A thorough numerical investigation was carried out to examine the heat transfer characteristics within a rectangular channel integrated with metal foam blocks for solar air heating applications. The study employed numerical simulations using the extended Darcy–Forchheimer model with the assumption that there exist local thermal nonequilibrium conditions within the porous foam region. Four configurations, denoted as P–A, P–P, A–P, and A–A, were explored based on the presence or absence of foam blocks relative to the heated section. The study meticulously analyzed the influence of key parameters, such as the number of foam blocks ( N = 1–5), permeability (quantified by pore density, ), and Reynolds number (), on the thermohydraulic performance. The results were promising, indicating a significant increase in the average Nusselt number () with the inclusion of foam blocks, albeit accompanied by an undesirable increase in the friction factor. Among the various configurations, the P–A arrangement, where porous blocks are situated at the entrance of the heating channel, exhibited superior thermal performance. Furthermore, the optimal heat transmission rate was attained with a single porous block ( N = 1) in the P–A configuration, at a Reynolds number of 16,000 and high permeability (). Conversely, the maximum friction factor was observed with five porous blocks ( N = 5) in the A–P configuration, at a Reynolds number of 4000 and low permeability (). The exhaustive analysis of thermohydraulic performance was evaluated using the performance evaluation criterion (PEC), which optimizes the trade‐off between increased heat transfer rate and consequent pressure loss. The P–A arrangement, particularly with higher permeability and a minimal number of porous blocks, demonstrated the highest PEC value of 2.71, representing a significant 171% improvement compared with an empty channel. This study underscores the effectiveness of strategically placing and optimizing metal foam blocks to improve the thermal performance of heat exchanger systems.