Formation of Flammable Zones Due to the Action of Diffusional Mass Transfer—A Simplified Approach

The transient concentration profiles of a fuel or a toxic gas were examined following its release into air within a long confined volume with either an open or a closed end. The exact one-dimensional solution with its limitations for cases of molecular and convective diffusion was presented and discussed. Two approximate solutions simplifying the exact one were developed. Their results were compared to those of the exact one and an error analysis was given. It was shown that despite its simple mathematical form, the second approximate solution would predict the concentration profiles with a reasonable accuracy. Comparison of some of the calculated values of the concentration with the corresponding experimental values was also made.