Fire Science and Technology

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We have investigated fire behavior in a poorly ventilated compartment using a methyl alchol pool fire of 30cmφ as a source in a box of 2m(W) ×3m(L) ×0.6m(H). Temperatures, gas concentrations of CO, CO₂, O₂, and methyl alcohol vapor, fuel consumption rate, and air exchange rate were measured simultaneously. The level of the fuel surface was kept constant during the tests by means of automatic fuel supply system. The flame began to detach from the fuel surface as the oxygen concentration decreased to about 6 vol. %, it color then bocoming pale blue. The flame later detached from the fuel surface and a "ghosting flame" was observed for 20-40min. In the poorly ventilated burning conditions, it was revealed that the air exchange rate was about 5 litters/sec, oxygen concentration was about 13-14 vol. %, and the burning rate was about 0.3-0.33 g/sec which was almost 1/5 of the normal burning rate. Based on the O₂, and CO₂ concentrations and air exchange rate, the fuel comsumption rate was estimated and which corresponded to the consumption rate measured. It was found that three times of the stoichiometrically required ventilation was occurred in the ghosting period and it ensured complete combustion of methyl alcohol.

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This paper illustrates the use on an infrared image processor as a new temperature measurement and display method of the heat flow formed by an extended flame from an opening using a reduced model. In order to visualize the temperature distribution of the hot air, a stainless steel net and a ceramic sheet were set in the path or the heat flow as subject for the infrared image processor during separate experiments. The visualized temperatures were compared with the corresponding temperatures obtained by using chromelalumel thermocouples. Temperatures obtained by the infrared image processor were lower than the ones indicated by the thermocouples. The upper part of the thermal trajectory line (i.e. maximum temperature line along the flow) obtained by the visualized temperatures was located further from the vertical wall than the ones indicated by the thermocouples and Yokoi's data. This newly developed method gave a clear and wide enough temperature contour map for the experimental study of the flame extention.

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