Coupled heat transfer simulations for evaluation of thermal performance during hydrogen absorption in cylindrical uranium-based hydride beds

Abstract

In this work, we established a three-dimensional coupled heat transfer model to evaluate the heat transfer during the hydrogenation reaction process in a uranium-based hydride bed. We constructed numerical simulations combined with the proposed model using Fluent to systematically investigate the influence of structure configurations, cooling media, and material thermal–physical properties on the thermal performance. Importantly, because the coolant temperature and the bed wall continuously changed during the hydrogen recovery process, the solid–liquid interface temperature had to be considered for an efficient thermal design of the bed wall cooling system. Accordingly, a coupling iteration algorithm was developed to improve the temperature prediction accuracy. In addition, we systematically investigated the effects of layer thickness, thermal conductivity, and cooling systems on the heat transfer behavior. The results demonstrated that reducing the hydride layer thickness, mixing the metal hydride bed with high-conductivity materials, increasing the cooling agent flow velocity, and using a cooling agent with a lower temperature were more beneficial in improving the thermal performance of the metal hydride bed. In addition, thinning the hydride layer and enhancing the hydride material thermal conductivity were found to decrease the peak temperature. Furthermore, the heat transfer efficiencies of hydride materials, bed structures, and cooling systems should be well matched to obtain optimal operating parameters. The results highlighted the applicability of the proposed model and the coupled heat transfer method to effectively characterize the temperature patterns of uranium-based hydride beds during hydrogen absorption.