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Reduced-Scale Ventilation-Limited Enclosure Fires: Heat and Combustion Product Measurements.


pdf icon Reduced-Scale Ventilation-Limited Enclosure Fires: Heat and Combustion Product Measurements. (1372 K)
Johnsson, E. L.; Bundy, M. F.; Hamins, A.

Volume 1;

Interflam 2007. (Interflam '07). International Interflam Conference, 11th Proceedings. Volume 1. September 3-5, 2007, London, England, 415-426 pp, 2007.

Keywords:

test methods; compartment fires; ventilation; combustion products; reduced scale; heat release rate; experiments; temperature measurements; fire tests; soot; heat flux; steady state; carbon monoxide; hydrocarbons; test methods; field models

Abstract:

The National Institute of Standards and Technology (NIST) recently conducted a series of reduced-scale compartment fire experiments with the purpose of generating a database of comprehensive and accurate measurements that can be utilized both for a better understanding of and improved modeling for compartment fires, especially in the ventilation-limited regime. The series of 17 experiments was conducted in a Reduced-Scale Enclosure (RSE) with dimensions 95 cm wide x 98 cm tall x 142 cm deep and a doorway 81 cm tall x 48 cm wide. This compartment was an approximately 2/5-scale model of the ISO 9705 room. Single, centered burners were used, and the fuels investigated were: natural gas, heptane, toluene, methanol, ethanol, and polystyrene. The liquid fuels were delivered in both pool burner and spray burner configurations. A few half-width doorway experiments were conducted with natural gas and heptane. Two types of wall material were included. Four to six target heat release rates up to 400 kW were explored with the goal of reaching underventilated conditions. Within the 17 experiments, 56 different combinations of fuel, heat-release rate, and doorway width were attained to produce steady state or generally steady periods for which the data were statistically analyzed.The heat release rate (HRR) was measured through oxygen-depletion calorimetry in the exhaust hood, and the fuel flows were also metered. Measurements of soot and gas species (through extraction) were made at two interior locations near the ceiling and in the exhaust hood. The gas species measured were CO, CO2, O2, and total hydrocarbons. Total hydrocarbons were measured with flameionization detectors, and hydrocarbon species were measured using gas chromatography. Gas temperatures were measured in several interior and doorway locations with both bare-bead and aspirated thermocouples. Doorway velocities were estimated with an array of bi-directional probes and pressure transducers. Heat flux gauges and surface thermocouples on the enclosure floor provided estimates of the thermal radiation environment. Results obtained from these experiments, including analysis of measurement uncertainty, are presented and discussed. Particular attention is given to distinctions between fires with different fuels, including some very high temperatures (>1200DGC), heat fluxes (>150 kW/m2), and CO concentrations (>8%). Insights into the composition of the measured hydrocarbons are detailed, and differences regarding half-width and full-width doorway experiments are described.