Investigating the protective performance of turnout gears for firefighters under diverse exposure conditions: Effect of age and body segments

Abstract

Present work investigates the impact of different exposures (flame, 50/50 convection and radiation, and radiation alone) on thermal performance of firefighters' clothing. The protective performance is evaluated across various body segments for firefighters of different ages. Transient heat transport equations are numerically discretized using finite difference approach. The computational domain comprises of a three-layer fabric assembly, a single-layer skin, and a microclimate between the fabric and skin. Heat transfer in the porous fabric assembly results from the interaction of both conduction and incident radiation penetrating through confined hot air within the fabric. The energy equation of fabric employs a two-flux model, encompassing self-emission originating from absorbed incident radiation in the encapsulated hot air. A nonlinear bioheat transfer model, accounting for age and body segment, incorporates temperature-dependent thermal conductivity, blood perfusion rate, skin thickness, and heat generation from metabolism, shivering, and external work. Results found that first and second-degree burn durations decrease by 30.85 % and 37.92 %, 26.73 % and 29.76 %, and 24.23 % and 26.63 % for flame, 50/50 convection-radiation and pure radiation heat exposure respectively as firefighter’s age from 25 to 65 years. The protective attire excels the best for the torso against direct flame but is the least effective for shielding arms from radiant heat. Moreover, the transition time from first to second-degree burn injury decreases by 64.77 %, 65.73 %, and 66.03 % for arms, and by 70.93 %, 66.29 %, and 67.22 % for legs in flame, 50/50 convective-radiative, and purely radiant heat exposures, respectively, with a 100 % reduction in skin conductivity coefficient.