A novel design for performance enhancement in sandwich heat transfer unit with partially filled metal foam

A novel wavy metal foam sandwich heat transfer unit is proposed and numerically investigated in this study, introducing a unique structural design to enhance thermal-hydraulic performance. A three-dimensional solid-fluid coupling model, based on the Forchheimer-Brinkman extended Darcy model and the local thermal non-equilibrium method, is established to validate the effectiveness of the new design. Compared to general plate metal foam structures, the wavy configuration significantly improves heat transfer capability, achieving a 118.3 %–89.7 % and 74.7 %–173.3 % increase in the Nusselt number under laminar and turbulent conditions, respectively. The enhancement is primarily attributed to the formation of dual high-velocity regions, which strengthen field synergy and promote efficient heat transfer. Moreover, the penetrable wavy interface effectively eliminates recirculation cells, leading to a moderate and acceptable increase in pressure drop. A comprehensive parametric study is conducted, examining the effects of channel width, fin height, amplitude, wavelength, porosity, and pore density. These findings establish the wavy sandwich heat transfer unit as a promising and fundamentally different alternative to traditional metal foam-based heat exchangers, offering optimized thermal performance with acceptable pressure drop penalties.