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Transport and Oxidation of Compartment Fire Exhaust Gases in an Adjacent Corridor.


pdf icon Transport and Oxidation of Compartment Fire Exhaust Gases in an Adjacent Corridor. (1307 K)
Lattimer, B. Y.; Ewens, D. S.; Vandsburger, U.; Roby, R. J.

Journal of Fire Protection Engineering, Vol. 6, No. 4, 163-181, 1994.

Sponsor:

National Institute of Standards and Technology, Gaithersburg, MD

Keywords:

corridors; compartment fires; exhaust gases; oxidation; flame length; carbon monoxide; hydrocarbons; global equivalence ratio; soffits

Abstract:

The oxidation of underventilated compartment fire exhaust gases during their transport down a corridor adjacent to the compartment was experimentally investigated. External burning from a compartment has been reported to decrease the toxic exhaust gas levels downstream of the compartment. The focus of the investigation was to identify the phenomena controlling the oxidation of the combustion gases external of the compartment as they traveled down a corridor during external burning. Variables in the research included the fire size, the hallway inlet and exit soffit heights, and the vent area from which the exhaust gases exit the compartment. Through gas sampling both in the hallway and in the exhaust duct downstream of the hallway, the oxidation of carbon monoxide (CO) and total unburned hydrocarbons (UHC) was studied. The concentrations of CO and UHC were reduced from the entrance to the exit of the hallway by 65 percent and 98 percent, respectively, with no soffit at either end of the hallway. The addition of a 20 cm soffit at the hallway entrance dramatically improved the oxidation and dilution of CO and UHC, resulting in a reduction of 80 percent and 94 percent in CO and UHC concentrations; respectively, from the entrance to the exit of the hallway. A soffit at the hallway exit was found to inhibit the species oxidation and resulted in only a 51 percent and 94 percent reduction in CO and UHC concentrations, respectively, from the exit to the entrance of the hallway. Descriptions of the types of external burning which occurred for different soffit geometries are given and then related to how it affected the oxidation of the exhaust gases within the hallway. The global equivalence ratio (GER) in the compartment could not predict the post-hallway species yields, so correlations were developed to predict the CO and UHC yields downstream of the hallway using dimensionless groups derived from dimensional analysis.