Thermal Behavior in Hydrogen Storage Tank for Fuel Cell Vehicle on Fast Filling

The current hydrogen storage systems for fuel-cell vehicles are mainly a compressed hydrogen storage type, but it is known that the temperature inside the tank commonly increases while the tank is being filled with hydrogen. This study examines filling methods that prevent the temperature from exceeding the designed temperature of the tank. In order to propose a filling method that suppresses the temperature rise inside the tank and achieves filling within a short time, fast-filling tests were conducted on test tanks designed for fast filling of fuel cell vehicles. The detailed influences of the differences in type of tank and filling pressure on the rate of the internal temperature increase were investigated. Thermal responses were measured at various parts inside and outside the tank while varying the filling pressure, type of tank, tank capacity, filling time, and filling pattern, using a test tank that allows multi-point measurement of the internal temperature. Remarkable differences in the rate of temperature increase during filling (ΔT) were observed between different types of tank, and characteristic differences in temperature were observed in the distribution of temperatures in the tank. In the type 4 tank, in particular, the temperature in the upper area inside the tank was higher than in other parts of the tank, depending on the filling rate. This paper indicates that if temperature, internal pressure and capacity of the tank are known when filling starts, it may be possible to shorten the filling time by selecting the optimum filling rate and to predict the maximum temperature reached in the tank.