Safe Separation Distance Calculation Model with Changing Area of Fuel Packages in Large Space

In performance-based fire protection design, the safe separation distance of fuel packages is usually calculated by NFPA model, i.e., setting a certain heat release rate and considering the fuel package as a point. The distance between adjacent fuel packages is taken as the distance between the two central points, which includes the equivalent radius of the fuel packages. However, there are many problems in practice. This paper introduced the principle of changing area to calculate the safety distance between adjacent fuel packages, combined with the algorithm of point source, line source and area source. Results show that it may directly get the correlation between the required safety distance and acceptable fire development time by using the changing area model of the fuel packages, which can meet both the functional and economic demands of buildings and avoid the unsafe results calculated by NFPA 92B model. Calculation results of point, line and area source model are very close to each other, thus simpler model like point source model and line source model would be more applicable in engineering applications.