Thermal Behavior in Hydrogen Storage Tank for FCV on Fast Filling (2nd Report) 2008-01-0463

If a compressed hydrogen tank for vehicles is filled with hydrogen gas more quickly, the gas temperature in the tank will increase. In this study, we conducted hydrogen gas filling tests using the TYPE 3 and TYPE 4 tanks. During the tests, we measured the temperature of the internal liner surface and investigated its relationship with the gas temperature in the tank. We found that the gas temperature in the upper portion of the TYPE 4 tank rose locally during filling and that the temperature of the internal liner surface near that area also rose, resulting in a temperature higher than the gas temperature at the center of the tank.

To keep the maximum temperature in the tank below the designed temperature (85°C) during filling and examine the representative tank internal temperatures, it is important to examine filling methods that can suppress local rises of tank internal temperature. First, we focused on the method for jetting hydrogen gas into the tank and conducted filling tests while varying the jet nozzle diameter of the TYPE 4 tank. We found that as the jet nozzle diameter becomes smaller, i.e., the flow velocity increases, the possibility of a local temperature rise in the upper area of the tank decreases. Furthermore, investigation of the influence of gas jet direction on the gas temperature rise in the tank revealed that the gas temperature rise is almost constant with a small jet nozzle diameter as was used in this test.