Evaluation of lower flammability limits of fuel–air–diluent mixtures using calculated adiabatic flame temperatures

Abstract The lower flammability limit (LFL) of a fuel is the minimum composition in air over which a flame can propagate. Calculated adiabatic flame temperatures (CAFT) are a powerful tool to estimate the LFL of gas mixtures. Different CAFT values are used for the estimation of LFL. SuperChems™ is used by industry to perform flammability calculations under different initial conditions which depends on the selection of a threshold temperature. In this work, the CAFT at the LFL is suggested for mixtures of fuel–air and fuel–air–diluents. These CAFT can be used as the threshold values in SuperChems™ to calculate the LFL. This paper discusses an approach to evaluate the LFL in the presence of diluents such as N 2 and CO 2 by an algebraic method and by the application of SuperChems™ using CAFT as the basis of the calculations. The CAFT for different paraffinic and unsaturated hydrocarbons are presented as well as an average value per family of chemicals.