Research Of Detection And Fire-fighting Device For Motorcoach Spontaneous Combustion

Motorcoach spontaneous combustion fires occur frequently around the world,which not only cause a large number of casualties and property losses,but also lead to severe social influence.It is necessary to develop a device placed in the engine compartment which can extinguish fire effectively in the initial stage of fire.This paper studies the fire spread in the coach engine compartment by numerical simulation and experiments.A device that can detect and extinguish fire automatically is developed successfully based on the above simulation results.Carry out the fire extinguishing experiments under different conditions to optimize the parameters of the device and improve its ability of fire-fighting.Main works of this paper are as followed:The randomness and determinacy of the fire spread in the engine compartment are studied both by the above two means.For determinacy,this paper analyses the influence of fire source location and ventilation on the fire spread according to the experimental results after comparing the results of the two kinds of simulations to prove the rationality of the scheme and the accuracy of the data.For randomness,the Markov model of the fire spread is found according to the previous investigation and analysis.To calculate the transfer matrix of the model and the maximum of transition probability between adjacent combustibles,the probability of the fire spread at different times and the relationship between that probability and time are studied by hypothesis analyzing and theoretical calculations.Based on these work above,this paper focuses on determining the way of alarm and its thresholds of detection device,the arrangement of temperature sensing cable and the trigger time and threshold of the fire extinguishing equipment.The core of the detection device is designed based on Micro-controller STC 89C52 RC,while the fire extinguishing equipment adopts the nozzles,which is solid and helical,to jet ABC ultrafine powder extinguishing agents.Also the arrangement of the nozzles is designed on the structural characteristics of the engine compartment of the coach.Applying that device to the engine compartment simulator,it proves that the fire-fighting capability of the device is better when using the solid and helical nozzle and ABC ultrafine powder by experiments.Then this paper conducts a research on the influences of the fire source location,the amount and the injection pressure of extinguishing agent on anti-fire efficiency of the device by doing experiments under different conditions.And it optimizes device parameters based on the above research to improve the reliability and safety of the device.