- Author
- Roby, R. J. | Beyler, C. L.
- Title
- Compartment Fire Combustion Dynamics. Final Report. June 1, 1988-September 1, 1991.
- Coporate
- Virginia Polytechnic Institute and State University, Blacksburg, VA Hughes Associates, Wheaton, MD
- Sponsor
- National Institute of Standards and Technology, Gaithersburg, MD
- Report
- Final Report, 1991, 49 p.
- Contract
- NIST-GRANT-60NANB8D0829
- Keywords
- compartment fires | hexanes | polymethyl methacrylate | polyurethanes | smoke generation | species concentrations | toxic gases | wood
- Abstract
- A three year study has been completed which experimentally (1) determined the effect of a realistic compartment fire flows on species generation rates and their correlation with equivalence ratio, (2) established major toxic gas and smoke generation rates for important fuels such as PMMA, wood and TDI-based polyurethane, and (3) determined the efficiency of external flames in destroying major toxic gases produced within the compartment under oxygen deficient compartment fire combustion. The apparatus that was used for this investigation includes a 1.2m x 1.2m x 1.5m compartment with two ventilation paths; a normal window style exhaust vent, and a ducted air inlet vent. Separation of the two flows allows a relatively simple measurement of the air inflow, while leaving the exhaust flow dynamics undisturbed. Exhaust from the compartment is collected by a hood system instrumented to allow the measurement of gas and smoke generation rates. This system allows direct measurement of air and fuel supply rates as well as speies generation rates. Correlations were developed between upper layer species yields and plume equivalence ratios and compared to correlations obtained for upper layers developed in an open hood. The study shows that the correlations developed for species yeilds in hood apparatus are qualitatively valid, but differ significantly from the correlations obtained for more realistic compartment fire environments. The work has shown that upper layer species yields in realistic compartment fires are fairly independent of fuel but highly dependent on the fire dynamics; the ratio of the burning rate to the air entrainment rate (ie. the equivalence ratio) and the upper layer temperature. Simple equations are proposed for correlating the combustion efficiency and the major species yields with the plume equivalence ratio for two-layer compartment fires. The effect of external burning on CO and smoke yields from compartment fires was also investigated. A window-style exhaust vent was used for the external burning experiments and species yields were measured in the exhaust duct downstream of the compartment. The yields measured downstream of the exhaust vent were compared to yields measured in the compartment upper layer for similar fires. External burning of fuel rich exhaust gases significantly reduces the CO yield to below life threatening levels. Fires with steady-state, average plume equivalence ratios greater than 2 were always observed to have sustained external burning.