Experimental flammability limits and associated theoretical flame temperatures as a tool for predicting the temperature dependence of these limits

Abstract

The utility and limitations of adiabatic flame temperature calculations and minimum mixture energies in predicting the temperature dependence of flammability limits are explored. The limiting flame temperatures at constant pressure (1 bar) are calculated using a standard widelyused thermodynamic computer program. The computation is based on the calculated limiting flame temperature value at the reference initial temperature and the experimental limit concentration. The values recently determined in large chambers for the lower and upper flammability limits of a variety of simple organic and inorganic gases (methane, ethylene, dimethylether, and carbon monoxide) are used as the basis for the predictions of the limiting flame temperature concept. Such thermodynamic calculations are compared with more traditional ones based on a limiting mixture energy and a constant average heat capacity of the reactant mixture. The advantages and limitations of the methods are discussed in this paper.

Determination of lower flammability limits of C–H–O compounds in air and study of initial temperature dependence

“…Considering that T LFL does not change when the mixture's initial temperature changes is equivalent to assuming that n is equal to zero for any initial temperature. In published studies (Zabetakis, 1965;Zlochower, 2012;Mendiburu et al, 2015), that consideration had accurate results for methane, propane, iso-butane, ethylene, propylene, carbon monoxide, ammonia, and dimethyl ether. However this is not true for all compounds, as can be observed on Figs.…”

Extended Adiabatic Flame Temperature Method for Lower Flammability Limits Prediction of Fuel-Air-Diluent Mixture by Nonstoichiometric Equation and Nitrogen Equivalent Coefficients

“…However, the hazardous materials are formed usually under high temperature (>200 °C) and pressure (>10 bar) in the chemical processing industry. Hence, it is more reasonable to predict the flammability limits at elevated temperature and pressure. ,,− …”

Flammability limits temperature dependence of pure compounds in air at atmospheric pressure

“…Most of the methods available in the literature were developed to determine the LFLs, such as the works of Catoire and Nauder [3], Rowley et al [4], Britton [5], Britton and Frurip [6], Mendiburu et al [7], Zlochower [8], Mendiburu et al [9] and Liaw and Chen [10]. Fewer studies are devoted to determine the UFLs at different initial temperatures, among them the works of Mendiburu et al [11] and Liaw and Chen [10].…”

“…Some of these works ([7] [8], and [10]), are based on the assumption that the adiabatic flame temperature at the LFL is constant with respect to the initial mixture temperature. Such consideration gives good results for the case of hydrocarbons; however, the theoretical results deviate from the experimental data for CHO compounds.…”