Research On Bus Fire Protection Development System Based On Fire Risk Analysis

Bus fire,which is highly harmful and rarely detected,threatens the public's lives and affects detrimentally when the incidence occurs.With the rapid development of bus technology,the utilization of emerging power technology related to battery has brought more safety hazards than before.The fire risk of electric buses is becoming severe nowadays.The application of technologies,such as hydrogen fuel technology,automatic driving and intelligent interconnection,has also brought great uncertainty to bus fire.However,it has limited vehicle fire prevention that most bus fire domestic and international researches focus on taking remedial measures after the accident occurred instead of prevention first.Fire safety is not included in the development system of bus products,which leads to the asynchrony between the development of bus products and the application of fire protection technology,so the prevention of bus fires has great limitations.In this paper,theoretical analysis is used to analyze the mechanism of fire accidents.Petrella evaluation system and related evaluation methods are used to classify the fire hazard of bus materials.The experimental research is used to quantitatively analyze the key fire hazard sources of bus.The cone calorimeter is used to conduct combustion experiments on the materials applied to buses,and the combustion characteristics of the materials are collected to assess the level of fire hazard quantitatively.The thermal radiation test of the power steering oil is carried out on the early fire test bench to make a research on the fire hazard and fire behavior of the 60Ah single-cell lithium iron phosphate battery.Based on the basic data obtained from the experimental research,we apply FDS to build the three-dimensional model of HFF6800GEVB3 pure electric bus.In order to study the application of simulation analysis in developing fire prevention,the simulation analysis method was used to simulate the spread of bus fire.Firstly,this paper analyzes the fire hazard sources of buses.By focusing on the HFF6800 buses,we identify the first type of fire hazard sources,and form a list of flammable materials on buses.At the same time,the system of safety analysis method is used to identify the second type of fire hazard sources,and the bus safety checklist is compiled to provide reference for fire safety protection during the whole life cycle of the bus.After that,the accident mechanism analysis method is used to analyze the fire caused by the bus fire system,such as automobile circuit system,oil circuit system,exhaust system,mechanical friction,engine compartment static,PCB board,etc.Therefore,we can study theoretically the direction of fire safety development in the bus design.Secondly,based on the identification of hazard source,this paper designs an experimental scheme,uses the cone calorimeter to collect the combustion characteristic data of the materials used on the bus,summarizes the experimental results of various materials,and uses the Petrella evaluation system to assess its fire hazard.More than 90%of the 20 kinds of interior and exterior materials used in the experiment are medium-risk materials.The chassis and high-voltage lines of the experiment are all medium or above hazardous materials.The radiation test of the power steering oil is carried out on the experimental platform in the early stage of the fire.The fire critical heat flow(CHF)of the power steering oil is 8.07 kW/m2,and the risk of fire under the high external radiant heat flow is high.The radiant heating experiment is carried out on a 60Ah monomer lithium iron phosphate battery.The experimental results show that the SOC value of the battery and the external radiant flux have a significant impact on the thermal runaway of the battery.Because of the quantitative experimental analysis of fire hazard sources,the fire protection design and development direction of buses have been further improved.Thirdly,this paper directly uses the combustion characteristic parameters of various materials obtained by experiments as the basic conditions of numerical simulation.The 3D simulation model of the actual fire scene of Ankai HFF6800GEVB3 pure electric bus is constructed by FDS software,and the fire is simulated at the head,the middle and the tail of the bus.The changes in CO concentration,temperature and smoke particles are analyzed.The simulation results show that opening the window is beneficial to exhaust smoke and hot air from the fire.Finally,this paper maps the results obtained in the fire risk analysis study with the AK.NAM vehicle product development process model of Ankai Automobile Co.,Ltd,based on risk analysis thinking,the fire protection safety research was started synchronously while the product planning started.Integrating the prevention plan of automobile fire hazard into each section of product design and verification under the cooperation of the V model-based AK.NAM automotive product development process.Through the model selection of automotive materials,the optimization design of the vehicle circuit,pipelines laying,and other specific design to reduce fire hazard from the beginning of buses production.Through designing verification scheme,evaluating the rationality of the design scheme,identifying the critical points of preventive maintenance of the product and developing fire protection and preventive maintenance plan to ensure the vehicle product can prevent the fire occurrence within the whole life cycle.Therefore,a complete vehicle fire protection system for the whole life cycle could be established,which would lay a solid foundation for automobile fire prevention from the initial design perspective.