Modeling of heat transfer through multilayer firefighter protective clothing/Modelarea transferului de caldura prin îmbracamintea de protectie pentru pompieri

• Published in: Industria textilă (Bucharest, Romania : 1994) Vol. 65; no. 5; p. 277
• Main Authors: Onofrei, Elena, Petrusic, Stojanka, Bedek, Gauthier, Dupont, Daniel, Soulat, Damien, Codau, Teodor-Cezar
• Format: Journal Article
• Language: English
• Published: Bucharest The National Research & Development Institute for Textiles and Leather - INCDTP 01.09.2014
• Subjects: Burns; Design analysis; Exposure; Fire resistant materials; Firefighters; Fires; Heat resistance; Heat transfer; Injuries; Materials science; Mathematical models; Physiology; Protective clothing; Radiation; Skin; Studies; Temperature; Textile industry; Textile research; Thermal comfort; Thermal radiation
• ISSN: 1222-5347

Acest articol este primul dintr-o serie de studii privind optimizarea performantelor îmbrâcâmintei de protectie pentru pompieri, în ceea ce prívente confortul termic $i protectia contra radiatiilor termice de mica intensitate. Lucrarea se axeazä pe dezvoltarea unui model numeric de transfer termic adecvat estimara temperatura $i fluxului termic în echipamentele de protectie destínate pompierilor. Utilizând aplicatiile pachetului Comsol Multiphysics®, pentru determinarea transferului de cäldurä s-a folosit metoda elementului finit. Rezultatele aplicärii acestui model au fost compárate cu cele experimentale, pentru un caz tipie de folosire a unui ansamblu de protectie format din trei straturi, în condifii obiçnuite. S-a observât o bunä core lape íntre rezultatele experimentale §i cele obpnute cu ajutorul modelului numeric. Acest model de transfer termic poate fi folosit în proiectarea îmbrâcâmintei de protectie pentru pompieri §i pentru evaluarea performantelor echipamentelor de protectie expuse diferitelor medii termice. This paper is the first in a series of studies on optimizing the performance of firefighter clothing, in respect of thermal comfort and skin protection from thermal injury that results from exposure to low-intensity thermal radiation. This paper focuses on the development of a heat transfer model suitable for predicting the temperature and heat flux in firefighter protective clothing exposed to low-intensity thermal radiation. The finite element method was used to evaluate the heat transfer by means of the Comsol Multiphysics® package. The model results were compared to experimental results for the case typical of routine conditions with a commonly used three-layer protective clothing assembly. Model predictions of the temperature agreed well with experimental temperature. This model could be used as an aid in the design of candidate protective clothing systems, by evaluating the performance of protective clothing systems in various thermal environments. When firefighters are exposed to a heat stress, their body reacts by activating sweat glands, i.e. through evaporative cooling mechanism. The protective clothing protects the firefighters from environmental heat and moisture but simultaneously prevents their flow in the opposite direction, away from the body to the environment. Consequently, risks of heat stress and steam burn injuries strongly increase. In such hot environments, heat and moisture transfer properties of the protective clothing have prevailing impact on firefighters' performances and their safety. Optimization of these coupled transfer phenomena from the skin through the garment could improve comfort of the wearers and hence their performance. Effective protective clothing should minimize heat stress while providing protection [2]. For this purpose, the firefighter protective clothing has to fulfill a variety of different demands according to the European standard EN 469: protection against heat from flames and thermal radiation, protection against hot liquids and other chemicals, resistance against abrasion and other mechanical stress, breathability, being not flammable, unshrinkable, easy to wash, light and comfortable [3]. A numerical model of heat transfer in protective clothing during exposure to low level of radiative heat flux was developed using the software Comsol Multiphysics® and the computational results were compared with the experimental ones. The predicted temperature values are in good agreement with the corresponding experimental measurements. At this stage, the model is restricted to dry fabrics, but further developments should include moisture effects. This model could be used as an aid in the design of candidate protective clothing systems, by evaluating the performance of protective clothing systems in various thermal environments. Thus, the model can be used to determine the effect of various parameters such as fabric thickness and density, thermal properties such as thermal conductivity and specific heat capacity, optical properties etc., or of environmental conditions such as radiant heat flux and ambient temperature, on the protective performance of clothing. These properties and parameters can be varied dynamically during the simulation.