Thermodynamic Analysis of the Flammability Limits of Fuel, Oxygen and Inert Mixtures

摘要

In Sheldon's (1) presentation of the flammability limit of a methane-oxygen-nitrogenrnmixture, he did not consider the effect of other inert gases. In this paper, Sheldon's idea isrngeneralized by considering the presence of inert gases. Three important parameters appear in thernconservation of mass equation describing the mixture; the molar stoichiometric ratio of oxygen tornfuel, the molar ratio of inert gases to oxygen and the molar ratio of the excess gases to thernstoichiometric oxidizing mixture. Other literature data on the lower flammability limit for arnnumber of hydrocarbon compounds in both oxygen and air was utilized to show that lean limitrnvalues are almost identical. The flammable envelope is defined by a region in a plot of thernreciprocal of the molar fuel concentration versus the molar excess gases to stoichiometricrnoxidizing mixture ratio. A similar region is defined by a plot of the molar inert oxygen ratio versusrnthe molar excess gases to stoichiometric oxidizing mixture ratio. It is shown that the flammablernregion of any fuel can be defined by considering the flammability limits of a fuel in pure oxygen.