Computational Fluid Dynamics Investigation of Filling Fuel Cell Electric Vehicle Hydrogen Storage Tanks According to Refueling Protocol Focused on Maximum Temperature Rise

Hydrogen refueling protocols such as SAE J2601 are designed to limit the temperature rise of hydrogen within the storage tank during refueling. However, the temperature distribution inside the tank is inherently non-uniform, and resulting thermal stratification may cause local temperatures to exceed prescribed limits when the protocol is applied based solely on measurements from a single thermocouple. Therefore, it is very important to estimate the maximum temperature behavior inside the tank during the filling process. A total of 64 CFD simulations are carried out to investigate the effect of the spatial temperature inhomogeneity. The results reveal that the temperature limit (<85 °C) imposed by SAE J2601 is satisfied even by the maximum temperatures in all the 64 cases. However, in some cases for the largest tank (10 kg) filling, it is found that the mass flow rate limit (<60 g/s) is exceeded at low initial pressure conditions. Mass flow rates of 75 g/s or more are calculated under conditions of 25 °C or lower. The increased mass flow rate is understood as the effect of assumption that the pressure drop from a hydrogen refueling station to the inlet of an on-board tank is neglected.