Interpretation of Fire Safety Distances of a Minivan Passenger Car by Burning Behaviors Analysis

In a car fire, thermal radiation poses a major threat to people and adjacent cars. Thus, estimations of fire safety distances are of great significance for the evacuation assignment and parking lot design. In the present full-scale experiment of a minivan car fire, the left cooling fan in the engine compartment was ignited as the origin of fire. The burn down of front bumper and windows markedly affected the fire intensity in engine and passenger compartment respectively. In the burning process, the peak heat release rate reached maximum value of 3.38 MW when gasoline leaked out. The flame model was assumed to be a superposition of several cuboids for the estimation of view factors of the fire. The average radiative fractions in the intense burning phases of engine and passenger compartments were first determined as 0.469 and 0.589, respectively, based on the burning behavior analysis. The resulting values allowed for the determination of thermal radiation in spatial positions and fire safety distances in the lateral side of the car for people and adjacent cars, which was an extension of previous researches of considering only the thermal radiation in certain positions. The calculation results of thermal radiation were in good agreement with the previous experimental data. The fire safety distances in the lateral direction of the car for people without protection and adjacent cars in this study, as examples, were about 7.3 m and 2.1 m respectively under threshold values of heat fluxes.