Modeling a thermal conductivity process under the action of flame on the wall of fire­retardant reed

Abstract

Creating environmentally friendly flame-retardant materials for natural inflammable roof structures will make it possible to control the processes of thermal stability and physical-chemical properties of a protective coating over its life cycle. There is therefore a need to study conditions for the formation of a thermal conductivity barrier and for the establishment of a mechanism that inhibits heat transfer to the material. It was experimentally determined that reed, non-treated with a flame-retardant agent, was ignited under the action of burner in 5 seconds, with the flame spreading throughout the entire surface, which resulted in its complete burning and the loss of mass. The study that we conducted into the influence of a coating on the transfer processes of a high-temperature flame to a material, established the fire protection process mechanisms, which imply the inhibition of such an action. It was proven that this process includes the decomposition of flame retardants under the action of temperature, with heat absorption and release of incombustible gases, the formation of ash-like products at the surface of a natural combustible material, as well as thermal insulation. That made it possible to determine conditions to protect reed from fire by forming a barrier to thermal conductivity. Experimental study has confirmed that a sample of fire-retardant reed withstood a thermal influence; the action of a heat flow lead to the swelling of the impregnation and the coating, which lasted for 120 seconds. We estimated the maximum possible penetration of temperature through the thickness of a coating and established that when reed, protected by the impregnating composition, was exposed to a flame of the burner, temperature at the inner surface was less than 147 °C with the mass loss not exceeding 2.9 %. Even greater efficiency was demonstrated by samples that were treated with the coating; the temperature did not exceed 140 °C, with a 2.5% mass loss. We also established that the coefficient of thermal conductivity, when protected from fire, reaches 1.6 W/(m∙°C) for the impregnating composition, and 1.2 W/(m∙°C) for the coating, respectively.