Carbon Monoxide Production in Compartment Fires

Abstract

The development of empirical correlations for major species yields in compartment fires has become an important priority due to the inability to calculate these quantities from first principles. Studies of simplified upper layer environments have shown that major species production rates can be correlated with the equivalence ratio in what is known as the Global Equivalence Ratio concept (GER). Due to the simplification in these past experiments, it was not known if the GER concept was valid for compartment fires. Therefore, there was a need to determine if correlations existed between major species yields and the equivalence ratio for actual compartment fires.A 2.2 m 3 test compartment was used to investigate the burning of four fuels (hexane, PMMA, spruce and flexible polyurethane foam) in compartment fires. The test compartment was specially designed with a two-ventilation path system which allowed the direct measurement of the plume equivalence ratio (the ratio of the fuel volatilization rate to the air entrainment rate normalized by the stoichiometric fuel-to-air ratio).Empirical correlations between the upper layer yield of major species and the plume equivalence ratio were shown to exist. The results reveal that the production of CO is primarily dependent on the compartment flow dynamics (i.e., the equivalence ratio) and upper layer temperature. The correlations developed in the compartment fires are qualitatively similar to those developed by Beyler for simplified upper layer environments. However, quantitative differences exist and can be explained in terms of temperature differences in experiments.

Carbon monoxide and smoke production downstream of a compartment for underventilated fires

“…The second subsection discusses the ratio Yco/Ys, as a parameter recently analysed by Tewarson, [27]. We compare his results with our data and data published by Gottuk [28] and try to account for encountered differences. Finally, a discussion on the temperature distribution inside the compartment is presented.…”

“…The reason for this behaviour is related to the external combustion [28]. Moreover, it may be assumed, that before external burning starts, the smoke, CO and CO 2 yields as measured downstream of the compartment are the same as inside the compartment, because there may be no reduction without external burning.…”

“…That design allowed him to derive accurate information about mass of air entrained and thus the plume equivalence ratio [8], [28]. Among others, he presented data for hexane fire with external burning, where the sampling point was downstream of the compartment (Fig.…”

“…Among others, he presented data for hexane fire with external burning, where the sampling point was downstream of the compartment (Fig. 5.4 in [28]). In order to compare similar conditions, only data for the plume equivalence ratio greater than one was examined, corresponding to underventilated conditions.…”

Coupled Fire/Evacuation Analysis of the Station Nightclub Fire

“…The correlation between the yields of species i (CO, CO 2 etc.) and equivalence ratios used in the toxicity model is derived from the experimental data for PU foam and wood [15][16][17]. The critical equivalence ratio [8], which is used to divide the computational domain into two parts for the calculation of species concentrations, is 1.0.…”