Predicting flammability limits via constancy of limit adiabatic flame temperature and limit expansion ratio

Lower and upper flammability limits for a combustible are, respectively, least and greatestcombustible concentration capable of propagating a flame. Mixtures with combustibleconcentrations greater than the lower flammability limit but less than the upper flammabilitylimit constitute the flammability zone. Keeping gas mixtures out of their flammability zone is animportant safety consideration both for the chemical and extraction industries. Unfortunatelythere is no generally accepted and applicable method for measuring flammability limits.Nassimi et al [1] used flammability limit data for 52 flammable compounds to define thermaltheory fuel universe and show that for combustibles belonging to thermal theory fuel universevalues of adiabatic flame temperature at the lower flammability limit are concentrated aroundtheir mean; while values of expansion ratio at the upper flammability limit are concentratedaround their mean [1]. Their work suggests constancy of adiabatic flame temperature andexpansion ratio as means for predicting flammability limits.In this work, we take a two pronged approach to extending Nassimi et al s work. In the firstprong, we have used their method for calculating flammability limits where we report andcompare the errors in predicted flammability limits using various flavors of our constancymethod. In the second prong, we have performed limit flame temperature and limit expansionratio calculations on a larger set of compounds to increase our confidence in aggregation aroundthe mean for these two quantities and to better delineate thermal theory fuel universe. Ourconclusions are based on calculations on 104 compounds. Inclusion of new flammables hasconsiderably improved the aggregation around the mean for limit quantities, which form thebasis of our flammability limit determination method.In summary, we have presented a method for predicting explosive limits and successfullytested it on the largest set of flammability limits which are available in the literature.

کلیدواژه ها:

Upper Flammability Limit ، Lower Flammability Limit ، Upper Explosive Limit ، Lower Explosive Limit ، Flammability Zone