Modeling of Thermal Performance of Firefighter Protective Clothing during the Intense Heat Exposure.

Abstract

The purpose of this research is to investigate numerically the heat and moisture transport in the firefighter protective clothing under the flash fire exposure. Numerical results help in understanding the basic mechanisms of the transient heat and moisture transport through the protective clothing, air gap, and human skin; and the effects of the moisture content on the thermo-physical properties of protective garments during the radiation heat exposure as well as during the cool-down period. Prediction of thermal performance of garment aids in designing and creating a new firefighter protective turnout gear in order to prevent and minimize tissue burns that result from the radiant energy produced by the fire and from the localized contact flame exposure.

During fire extinguishing, firefighters often sweat profusely and are also exposed to the dousing water from a hose spray, which leads to accumulation of moisture in the turnout gear. Evaporation, condensation, desorption, and absorption of the moisture and energy associated with phase change can affect the temperature and energy flux to the skin.

Traditional thermal protective garments rely passively on thermal properties of fabric and the entrapment of insulating air layers to resist heat flux from flash fire exposures. To improve the level of heat flux resistance of thermal protective garments, this research evaluates the feasibility of developing a novel garment system based on the utilization of a water-injection. For the intelligent garment investigated in this research, the liquid water will be injected in the outer layer of the garment through a capillary net composed of thin perforated tubes; the injection process will be activated by a temperature sensor embedded in the outer fabric layer. Therefore, the new turnout system augments this outer layer, by providing an active thermal barrier and acting as a thermal buffer against the high heat flux associated with the flash fire exposure while the remaining inner layers continue to efficiently provide the conventional protection based on the traditional insulation due to their small thermal conductivity.