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

Abstract

A method for determination of the LFLs of C-H-O compounds was developed. The method was very accurate when it was tested against experimental data. The temperature dependence of the LFL was studied. It is not always correct to assume that adiabatic flame temperature is constant. A method for determination of LFLs at different initial temperatures was developed.

Determination of upper flammability limits of C H O compounds in air at reference temperature and atmospheric pressure

“…Coward and Jones [4] stated that the flammability limits should be determined at constant pressure and such configuration has been applied by Mishra and Rahman [24] in their experiments. A constant pressure combustion process has been assumed in other works related to the determination of flammability limits [17,16,18,25] and this consideration is consistent with the experimental determination. As a first argument, the American Norm ASTM E681 [26] is considered.…”

“…The same concept has been applied by Mendiburu et al [16] for the determination of the LFL of CAHAO compounds. In the case of the LFL, it was assumed that complete combustion is achieved.…”

“…In this sense, the method is similar to those based on the calculated adiabatic flame temperature that were developed for the determination of the LFL [17,18]. Also among these works, those by Rowley et al [19] and Mendiburu et al [20,16] can be considered.…”

“…That parameter is defined as the ratio of the adiabatic flame temperature at the stoichiometric composition ðT stq Þ to the value of T UFL . This concept is the same adopted for the case of the LFL in previous work by Mendiburu et al [16].…”

Constants of explosive limits

“…The LEL and the UEL are generally considered to be 0.5 and 3 times the stoichiometric concentration of the fuel [29]. Methods for calculating the LEL or the UEL make use of the standard enthalpy of combustion [30,31], normal burning velocity [32], adiabatic flame temperature (AFT) for partial combustion to CO and H 2 O [33], minimum spark ignition energy [34], ratio of stoichiometric AFT to AFT the EL [17] or constancy of AFT [13,35,36]. In calculation of flammability limits from AFT, the existence of the flammability limits is considered to be a consequence of existence of a minimum sustaining temperature for the flame-thermal theory [37].…”