To examine the safety of rescuers when hydrogen leaks from an FCV vehicle, we investigated the relationship between the minimum audible threshold of hydrogen leakage sound and the flow rate of hydrogen in approximately 74 dB noise level environment. The results indicate that perceptible maximum hydrogen flow rate for 5 m and 10 m from the center of the vehicle are 260 NL/min and 338 NL/min. However, these flow rate does not harm to the human at each direction.

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For the full-scale commercialization of fuel cell vehicles, early effort is needed to develop a work manual for the safe scrapping of end-of-life FCVs. Particularly it is necessary to raise the efficiency of the currently laborious and time-consuming scrapping work for FCV compressed hydrogen cylinders. The present study was focused on the possibility of omitting the vacuuming step for removing residual hydrogen from cylinders to be dismantled. The test results indicated that; 1)a cylinder containing hydrogen removed from a scrapped FCV is left in the atmosphere. 2)difference between the reaching time to flammable limit and the finish time of natural exhausting depends on the diameters and the direction of the cylinder exit remarkably. 3)when hydrogen in a cylinder is within the flammable limit, hydrogen could be ignited. Dismantling workers could be injured in their ears.

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To examine a safety correspondence method of the hydrogen fuel cell vehicle after the extinguishment of a fire, the carbon-fiber reinforced composite cylinder (CFRP cylinder) for automobile with the filling gas of maximum working pressure was heated by electrical oven, when a cylinder burst or leak, the survival temperature and the internal pressure of cylinder were investigated. As a result, a cylinder (Working Pressure 20MPa, Type III) burst at 200°C on cylinder surface with 38MPa. Another cylinder (Working Pressure 25MPa, Type IV) began leak from liner at approximately 150°C on the liner surface with 40MPa. The above result showed that the survival temperature of the CFRP cylinder is approximately 150 °C as low to be on the safer side. The CFRP cylinder after extinguishment of a fire should be cooled by water positively to became than this survival temperature.

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In a preliminary study of the thermal runaway propagation test, we performed an overcharging test, a heating test using heaters of several kinds, and a nail penetration test of a single cell to investigate the means for generating a thermal runaway. We found it was possible to generate thermal runaway due to overcharging, heating by a large film heater, and nail penetration. Next, we conducted thermal runaway propagation tests by heating some modules with the large film heater. We found we could produce thermal runaway only in one particular cell. In addition, we confirmed thermal runaway propagation to adjacent cells. Therefore, heater heating was an effective means of generating thermal runaway.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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