Study On Gas Detection Technology Of Lithium Battery Fire In Aircraft Cargo

As lithium batteries more and more widely used in various fields of production and living, the air transport of lithium batteries is also showing a growing trend. The civil aviation organizations over the world make every effort to ensure the safety of lithium batteries in air transportation, in order to avoid unsafe events or accidents.Existing smoke fire detector can't detect the lithium battery fire effectively due to the high rate of false positives, alarm, shortcomings and so on, so choosing suitable technology for fire detection is particularly important.Through the independent design modification of lithium battery burning experiment platform to experiment of 18650 lithium battery combustion characteristic research, we collect and measure the gas composition and concentration released from the lithium battery. Select the carbon monoxide and methane gas of the released gas as a probe standard gas and combine the gas characteristics and working principle of the corresponding gas detector, design a lithium battery fire detection scheme by detecting carbon monoxide and methane gas in aircraft cargo. PyroSim is used to establish the airbus A320 aircraft main hold fire simulation model and simulate the gas detection scheme. Then verify the gas detection scheme through the medium-sized experiment platform.The experiment results show that the combustion process of lithium battery mainly divides into two phases: the incipient detonation response phase and secondary combustion phase. Under the condition of the same gas displacement, the incipient detonation response temperature decreases with the increasing of the charge state; while under the same charge state, battery that are after helium replacement has a lower incipient detonation temperature than that are without replacement.Production of carbon monoxide and methane is big in the released gas, which can be seen as a sign of the early fire detection. Through simulation, the alarming time of the carbon monoxide gas detector is 40 s, and the alarm concentration is 1150ppm; the alarming time of the methane gas detector is 51 s, and the alarming concentration is 1569 ppm; the alarming time of the smoke fire detector is 63 s. In themedium-sized platform validation experiment, the alarming time of the carbon monoxide gas detector is 43 s, and the alarming concentration is 1078 ppm, while the alarming time of the methane gas detector is 53 s, and the alarming concentration is1256 ppm, the result of which is similar to that of the simulation. The combination plan of the carbon monoxide and methane gas detection can meet the requirements of lithium battery fire detection.Based on the gas releasing characteristic of the lithium-ion battery, this thesis applies the fire gas detection technology in the airplane cargo in order to achieve the detection of the lithium battery fire within 60 s, providing convenience for putting out the fire immediately. This gas detection technology can not only effectively detect lithium battery fire in the airplane cargo, but also can avoid the weakness of the high rate of false alarm that smoke gas detector owns. It has strong pertinence and applicability.