During the filling of hydrogen tanks high temperatures can be generated inside the vessel because of the gas compression while during the emptying low temperatures can be reached because of the gas expansion. The design temperature range goes from 40 C to 85 C. Temperatures outside that range could affect the mechanical properties of the tank materials. CFD analyses of the filling and emptying processes have been performed in the HyTransfer project. To assess the accuracy of the CFD model the simulation results have been compared with new experimental data for different filling and emptying strategies. The comparison between experiments and simulations is shown for the temperatures of the gas inside the tank, for the temperatures at the interface between the liner and the composite material, and for the temperatures on the external surface of the vessel.JRC.C.1-Energy Storag

The influence of the initial tank temperature on the evolution of the internal gas temperature during the refueling of on-board hydrogen tanks is investigated in this paper. Two different types of tanks, four different fuel delivery temperatures (from ambient temperature refueling to a pre-cooled hydrogen at -40°C), several filling rates and initial pressures are considered. It is found that the final gas temperature increases linearly with the increase of the initial tank temperature while the temperature increase and the final state of charge (SOC) decrease linearly with increasing initial temperature. The final temperature dependency on the initial temperature is larger with type III than with type IV tank, and grows with increasing initial pressure. Additionally CFD simulations are performed to better understand the role of the relevant phenomena on the gas temperature histories e.g. gas compression, gas mixing, and heat transfer. By comparing the results of calculations with adiabatic and diathermal tank walls, the effect of the initial gas temperature has been separated from the effect of the initial wall temperature on the process.JRC.F.2-Energy Conversion and Storage Technologie