Abstract
•The feasibility study of employing a HTF pipe in a MH tank that integrates a PCM is made.•A 3D mathematical model is developed and is used for simulating various configurations of MH tank.•The influence of HTF type and its mass flow rate on hydrogen filling time is evaluated.
This study evaluates numerically the feasibility of employing a Heat Transfer Fluid (HTF) pipe in a Metal Hydride (MH) tank that integrates a Phase Change Material (PCM) heat exchanger. A 3D mathematical model is developed for this system and is used for simulating various configurations (Case 1: MH tank with PCM heat exchanger, Case 2: MH tank with PCM heat exchanger and open HTF pipe and Case 3: MH tank with PCM heat exchanger and closed HTF pipe). For each case, advantages and limitations are evaluated with respect to their heat transfer performance and filling time of hydrogen vis-a-vis heat storage capacity. In addition, the effects of the HTF type and its mass flow rate on the performance of the MH tank are studied. Besides showing a thermal coupling between MH bed, HTF pipe and PCM medium, the computational results indicate that the use of HTF pipe in MH-PCM tank is a tradeoff between reducing the hydrogen filling time and compromising the heat storage capacity. The results indicate that compared to the Case 1 (without HTF pipe) the filling time can be reduced by 94% for the Case 2 where the HTF pipe extracts 70% of the heat of reaction and delivers it to environment as waste heat. However, the filling time is reduced by only 72% for the Case 3 where all the heat of reaction is stored in PCM.