Application of the mean radiant temperature method in the evaluation of radiative heat exchanges between a fire front and a group of firemen

Abstract

In this work will be studied the application of the Mean Radiant Temperature method in the evaluation of radiative heat exchanges between a fire front and a group of firemen. The development and the application of the Mean Radiant Temperature method will be presented in this work. The obtained results are used to analyse the protection made by firemen bodies in the others firemen in front a fire front. The obtained protection can be used in order to reduce the fire front radiative flux value that the firemen are subjected. In this study will be used a numerical model, that evaluates the human and clothing thermal response, in steady-state and transient conditions. The software calculates not only the temperature field in the human body tissue, arterial and venous blood and clothing, but also the blood and tissue mass field in the human body and the water mass field in body skin surface and clothing. This model considers the human body divided in 25 cylindrical and spherical elements, being each one sub-divided in 12 layers, which could be protected from the external environment through some clothing layers. The computational model of the human body and clothing thermal system is based on the energy balance integral equations for the human body tissue, blood and clothing as well as mass balance integral equations for the blood and transpired water in the skin surface and in the clothing. A thermoregulatory system model was adapted to control the human body tissue temperature. The radiative heat exchange numerical model between a fire front and the firemen is based in the Mean Radiant Temperature method. This numerical model considers the view factors determination between the firemen bodies and the surrounding surfaces (fire front and environment) and between the occupants’ section. In this calculus the grid generation around the firemen and in the fire front is used to evaluate the view factors. In the numerical simulation, presented in this study, is considered a fire front, the floor, the environment and a group of firemen. The numerical model calculates the Mean Radiant Temperature, that a group of 9 firemen are subjected.