Comparatives study of radiative heat exchanges between fire front from fireman and pine tree in warm thermal conditions

Abstract

This work presents the development of a numerical design in forest fire environments. A comparison between a tree body and a human body (fireman) thermal response systems is made. The three-dimensional pine tree model is constituted by trunk, branches and leaves represented by cylindrical elements. The human body model is divided into 35 elements and considers its thermoregulation. In both systems, special attention is required with conduction, convection, evaporation and radiation. There are also considered the heat exchanges by radiation between the fire front and both bodies. A vertical fire front, with 2 m of height and 20 m of length, was considered. The air temperature, air velocity, air relative humidity and mean radiant temperature are used. Two cases were studied: a pine tree and a fireman placed nearby the fire front. The results of the flame mean radiant temperature, temperature of the bodies surfaces and view factors are obtained. The results show that the fireman is most exposed than the pine tree to the fire front. Due to the human thermoregulatory and clothing systems, the fireman has a skin surface temperature much lower than the surface temperature in the trunks, branches and leaves of the tree. The evaporation in the tree is not sufficient to control the temperature.