scholarly journals Radiative and convective heat exchanges between a fireman and the fire front and wind

Author(s):  
Eusébio Z. E. Conceição ◽  
et. al.
2020 ◽  
pp. 57-65
Author(s):  
Eusébio Conceiçã ◽  
João Gomes ◽  
Maria Manuela Lúcio ◽  
Jorge Raposo ◽  
Domingos Xavier Viegas ◽  
...  

This paper refers to a numerical study of the hypo-thermal behaviour of a pine tree in a forest fire environment. The pine tree thermal response numerical model is based on energy balance integral equations for the tree elements and mass balance integral equation for the water in the tree. The simulation performed considers the heat conduction through the tree elements, heat exchanges by convection between the external tree surfaces and the environment, heat exchanges by radiation between the flame and the external tree surfaces and water heat loss by evaporation from the tree to the environment. The virtual three-dimensional tree model has a height of 7.5 m and is constituted by 8863 cylindrical elements representative of its trunks, branches and leaves. The fire front has 10 m long and a 2 m high. The study was conducted taking into account that the pine tree is located 5, 10 or 15 m from the fire front. For these three analyzed distances, the numerical results obtained regarding to the distribution of the view factors, mean radiant temperature and surface temperatures of the pine tree are presented. As main conclusion, it can be stated that the values of the view factor, MRT and surface temperatures of the pine tree decrease with increasing distance from the pine tree in front of fire.


2000 ◽  
Vol 39 (3) ◽  
pp. 404-413 ◽  
Author(s):  
Souad Harmand ◽  
Barbara Watel ◽  
Bernard Desmet

2014 ◽  
pp. 316-321
Author(s):  
Eusébio Z. E. Conceição ◽  
Manuel C. Gameiro Silva ◽  
Domingos X. Viegas

2020 ◽  
pp. 39-49
Author(s):  
Eusébio Conceição ◽  
João Gomes ◽  
Maria Manuela Lúcio ◽  
Jorge Raposo ◽  
Domingos Viegas ◽  
...  

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.


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