Kinetic Parameters of Smoke Aerosols during Combustion of Modified Wood

Abstract

The most dangerous factors of fire are formation of smoke and thermal decomposition of toxic products. In case of fire, smoke spreads to evacuation routes. In this case, a person may be disoriented and feel panic. Smoke is an aerosol produced by the thermal decomposition of materials. The study object is the wood, which is widely used in construction. Up to date, the influence of wood species and wood surface layer modifiers on the smoke-forming ability has been studied. The effect of wood surface layer modifiers on the properties of aerosols remains insufficiently studied. The objective is to evaluate the effect of the wood surface layer modifiers on the formation and stability of smoke aerosols. In the course of work, the ultimate analysis method was used to assess the modifying effect of selected phosphoric acid esters. It is known that these compounds constitute effective flame retardants and are able to provide the biological stability of the wood. Granulometric analysis was additionally performed to evaluate the aerosol’s properties. To evaluate the energy characteristics of the modified wood surface, the “neutral drop” method was used. As a result of the studies, a percentage phosphorous content was obtained in the surface layer of the wood before and after thermal decomposition. This data made it possible to conclude that the thermal effect of diethyl phosphite is very effective and stable when it is used as a modifier. Based on the granulometric analysis, the size distribution of solid aerosol particles was obtained. When using the selected modifiers, the maximum particle size of the aerosol is reduced, which in turn reduces the optical density of the smoke. Phosphoric acid esters affect the kinetic parameters of the aerosol, which were obtained on the basis of mathematical calculation. Diethyl phosphite produces the greatest effect on the decrease in the aerosol’s stability. The formation of an aerosol having a smaller particle size occurs during thermal decomposition of the modified wood having a thermally stable surface. Therefore, the modification of wood by phosphoric acid esters reduces its propensity to smoke-generating ability, which determines the reduction in death rate of humans in the event of fire.