EXPERIMENTAL DETERMINATION OF THE SPECIFIC COEFFICIENT OF RELEASE OF CARBON MONOXIDE DURING A FIRE IN THE ROOM

Аннотация

An experimental installation for small-scale modeling of thermal and gas dynamics of fire in conventionally sealed volume during the combustion of solid and liquid combustible substances and materials is created. The plant consists of a combustion chamber and the exposure chamber in which there are measured the current mass of combustible material, the temperature of heat source, the mean volume temperature and mean volume gas concentrations in the gas mixture. Analytical dependence for calculating the mean volume density of carbon monoxide is proposed. It is shown that the above mentioned density does not depend on the properties of the combustible material, sizes of the room and the area of the exposed surface of the fuel material. Thus, the above relationship is valid in a small-scale and large-scale conditions of fires in the room. Experimental dependences between mean volume density of carbon monoxide and the mean volume temperature are obtained. Experimental dependences of the coefficients of the specific release of carbon monoxide and specific gasification mass rates from testing time during the combustion of coniferous wood, transformer oil and PVC sheath cables are received. It was found that the above coefficients are substantially unsteady. A comparison of experimental results with those of literary sources and the analytical solution of the integral model is presented. The essential difference between the obtained values of L_CO and the provided ones in the literature can be explained by differences in the experimental conditions. Also the chemical compositions of the PVC sheath cables and transformer oil in this paper and in the published ones may differ significantly from each other. Furthermore, in these experiments there was not measured humidity of coniferous wood materials. It is shown that the values of the specific release coefficient and density of carbon monoxide are insignificant in the initial stage of burning when the oxygen concentration remains practically unchanged. By reducing the concentration of the oxygen emission of carbon monoxide increases dramatically and the density of carbon monoxide quickly reaches its critical value. It was found that the average value of the specific release coefficient of carbon monoxide depends essentially on the averaging period of the time. Averaging value can be changed in the case of coniferous wood materials in 2.63 times, for cable sheathing PVC - 1.8 times and transformer oil - 5.1 times.