Optimization of metal foam pellet shape in packed beds for improved radial heat transfer using particle-resolved computational fluid dynamics

Process intensification in tubular reforming reactors has always been a topic of interest, particularly for improving the radial heat transfer. The innovation of open-cell metallic foam pellets is the latest in this category, as they bear unique transport properties. This work presents the optimization of metal foam pellet shapes for improved radial heat transport, using a virtual design platform based on a modified version of particle-resolved computational fluid dynamics. To optimize the pellet geometry, different configurations such as pellet with inner holes, external grooves, and varied aspect ratios, as well as different foam morphologies (cell size ϕ and porosity ε) are considered, and the influence of each pellet configuration on flow and energy transport in a randomly packed bed setup has been investigated. Based on the desirable properties of the packed bed, such as low pressure drop, high heat transfer coefficient, increased surface area, and high catalyst inventory, the overall performance of the investigated pellet shapes is analyzed. The foam ring with the aspect ratio of 2.5 and ϕ = 0.45 mm, ε = 0.82 has been identified as optimal under the investigated operating conditions 250 < Re_P < 2250, which is confirmed by pressure drop and heat transfer experiments.