Estimation of the Parameters of Combustion of the Surface of Natural Combustible Materials by the Thermography Method
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Journal of Engineering Physics and Thermophysics, Vol. 93, No. 4, July, 2020
HEAT AND MASS TRANSFER IN COMBUSTION PROCESSES ESTIMATION OF THE PARAMETERS OF COMBUSTION OF THE SURFACE OF NATURAL COMBUSTIBLE MATERIALS BY THE THERMOGRAPHY METHOD N. V. Agafontsev and D. P. Kasymov
UDC 614.841.2
The results of an experimental investigation into the parameters of combustion of peat and wood using thermography have been presented. The mechanism of propagation of smoldering over the peat surface has been identified. The temperature field on the surface of peat during its combustion under the influence of a local heat source has been obtained, and the velocity of propagation of the smoldering front has been estimated. Using the IR-diagnostics method, temperature distributions have been obtained over the surface of wood specimens exposed to heat action under conditions of a ground fire with and without fire-retardant treatment. Keywords: thermography, wood, fire retardant, combustion, peat. Introduction. During the propagation of ground and crown forest fires, there is a release of a large quantity of heat, which can cause ignition of wooden structures in communities located close to the forest boundary and also result in the development of peat fires. The current level of knowledge of peat fires and methods of fighting them is insufficient for solving practical problems of preventing and extinguishing them. Despite the negative effects of peat fires [1], the mechanism of ignition of peat and deepening of the site of its combustion has not been investigated yet, and methods to identify the peat fire seat and to extinguish it quickly and efficiently at no significant cost have not been developed. A physicomathematical study of peat and wood combustion has been the subject of many investigations [2–5] in which the dynamics of combustion of various types of peat and the probability of their ignition, and also, the properties of extinguishing aerosols and gases released in combustion of a peat bed, have been investigated. It has been shown that the increased fire hazard of peat is due to its porous structure and low density, which makes combustion in peat fields unmanifest, and it can occur, in practice, in an airtight environment [11, 15]. According to [15], the main natural sources of peat fires are spontaneous combustion of peat and rainless storms, whereas the main man-made sources of such fires are sparks occurring during the operation of machinery and technical devices, and also due to careless handling of fire. It has been pointed out in [8, 15] that the combustion in the lower portion of peat is significantly more intense than the combustion in its upper portion, since the heavier fresh cold air arrives in the lower zone of the burning peat and intensifies the reaction of its combustion. In the process of combustion deepening into the peat, there is accumulation of heat in it and its propagation toward portions with higher humidity, which ignite after evaporation of the moisture they contain. In the construction indust
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