Preliminary Investigation of the Fire Hazard Inherent in Micro Fuel Cell Cartridges

摘要

Micro fuel cells are an alternative to batteries as a portable source of electricity. Unlike a battery, which stores electricity, a fuel cell chemically reacts a base fuel with oxygen from the air to generate electricity. A fuel cell is recharged by simply replacing the fuel. The potential flammability of the base fuels is a concern when carried onboard an aircraft. A series of tests were performed to evaluate the flammability hazard associated with fuel cell fuel cartridges. Tests were conducted with various fuel chemistries including methanol, formic acid, butane, hydrogen gas, and borohydrides. The response of each fuel cartridge to an external alcohol fire was evaluated. Most of the fuels tested were flammable. The cartridge containing formic acid did not ignite under the test conditions. Butane produced the most vigorous fire. Heating hydrogen gas stored in a metal matrix caused breaching of the enclosure allowing the gas to escape and ignite. Borohydrides were difficult to ignite but gave off a flammable fume when heated and were capable of deep-seated exothermic reaction. It was found that the cartridge material can have a significant effect on flammability. Metal cartridges protected the fuel from an external fire better than plastic cartridges. Halon 1211 was effective against all but the deep-seated borohydride exothermic reaction.