Flammability zone prediction using calculated adiabatic flame temperatures

Abstract

This paper describes our work to predict the flammability zone for any mixture of fuel, oxygen and nitrogen. The method utilizes a commercially available equilibrium program to determine the calculated adiabatic flame temperature (CAFT). The model is compared with our extensive experimental data obtained in a 20 L sphere at an initial pressure of 1 atm and 298 K. The data and model compare well over the entire flammability zone for two pure species, methane and ethylene, and not as well for a 50/50 mixture of methane/etbylene. Our results show that a good prediction of the flammability zone is obtained using a CAFT criteron of 1200 K. Furthermore, the intermediate species and solid carbon must be included in the equilibrium calculation to fit the fuel rich part of the zone. The intermediate species were selected by the equilibrium program using a built‐in species selection criteria. For a gas mixture of methane and ethylene, we were unable to identify, mixing rules for estimating KG and Pmax from pure component data. This method provides a direct approach to full flammability zone prediction.

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

“…T ad,mix = i x i T ad,i = 0.5T ad,methane + 0.5T ad,ethylene (9) The adiabatic temperature for this mixture is 1426 K, at which the computed LFL composition is 3.68% as it is shown in Fig. 7.…”

Flammability envelopes for methanol, ethanol, acetonitrile and toluene

“…It is not necessary to include organic molecules with more than the number of carbon atoms in the combustible fuel, because the carbon chain will not lengthen during the combustion process. Mashuga and Crowl (1999) determined that solid carbon should be included as one of the species in the chemical reaction equilibrium calculation.…”

“…This method was proposed by White (1925) and then used by Hertzberg, Cashdollar, Zlochower, and Ng (1984), Hansel, Mitchell, and Klotz (1992), Melhem (1997) and Mashuga and Crowl (1999) to predict flammability limits. Hertzberg et al (1984) and Mashuga and Crowl (1999) used the method to model the entire flammability envelope. This method will be applied to predict the flammability envelope for these flammable liquids, and the results will be compared to our experimental data.…”

Flame temperature theory-based model for evaluation of the flammable zones of hydrocarbon-air-CO2 mixtures

“…The flame temperature is calculated by assuming no heat losses. The temperature of such a flame is the calculated adiabatic flame temperature (CAFT) [13]. Vidal et al [14] pointed out that the CAFT is a powerful tool to estimate the LFL of gaseous mixtures.…”