Evaluating the necessity of heat transfer enhancement in metal hydride reactors for hydrogen storage and cooling

• Relevance of heat transfer enhancement in metal hydrides is evaluated. • Constant H 2 flow boundary condition is applied for realistic modelling. • A novel porous honeycomb is introduced for reactor thermal management. • Adding 21% fin volume reduces cooling system replacements by 60%. Over the past two decades, significant research has been devoted to exploring heat transfer enhancement techniques for metal hydrides. This study critically evaluates the necessity of such enhancement techniques for practical applications. For this, we considered two applications of metal hydrides: hydrogen storage for an electrolyzer and a cooling system for a heavy-duty refrigerated transport truck. Two materials, LaNi 5 and Ti 0.98 Zr 0.02 V 0.43 Fe 0.09 Cr 0.05 Mn 1.46 , are studied for hydrogen storage and cooling applications, respectively. A porous honeycomb fin structure is employed as a heat transfer enhancement technique, and its relevance for hydrogen storage and cooling applications is examined through a Multiphysics simulation model developed in COMSOL, which captures the dynamic behaviour during hydrogen absorption and desorption. Further, we explored a more realistic constant mass flow boundary condition at the hydrogen inlet (absorption) and outlet (desorption) boundaries and defined rated flow conditions for the metal hydride reactor. From the sensitivity analysis, fin volume and hydrogen mass flow rate are identified as critical parameters impacting reactor efficiency. Additionally, a reactor efficiency map is generated for both absorption and desorption processes, offering guidance for selecting optimal fin volume and hydrogen flow rates for the specific application of the metal hydrides. The results showed that the necessity for heat transfer enhancement depends on the electrolyzer’s rated flow rate and the total hydrogen storage capacity in hydrogen storage applications. For most practical hydrogen storage applications, heat transfer enhancement is not required for metal hydrides. However, in cooling applications, heat transfer enhancement significantly influenced the system performance and operating cycles. For 10-kW cooling of the heavy-duty refrigerated transport trucks, the number of cooling system replacements is reduced by up to 63 % with a 21 % fin volume, while the onboard mass of MH material decreased by ∼ 21 %.