Influence of Initial Moisture Content on Heat and Moisture Transfer in Firefighters’ Protective Clothing

Abstract

This paper presents a model for heat and moisture transfer through firefighters' protective clothing (FPC) during radiation exposure. The model, which accounts for air gaps in the FPC as well as heat transfer through human skin, investigates the effect of different initial moisture contents on the thermal insulation performance of FPC. Temperature, water vapor density, and the volume fraction of liquid water profiles were monitored during the simulation, and the heat quantity absorbed by water evaporation was calculated. Then the maximum durations of heat before the wearer acquires first- and second-degree burns were calculated based on the bioheat transfer equation and the Henriques equation. The results show that both the moisture weight in each layer and the total moisture weight increase linearly within a given environmental humidity level. The initial moisture content in FPC samples significantly influenced the maximum water vapor density. The first- and second-degree burn injury time increase 16 sec and 18 sec when the RH increases from 0% to 90%. The total quantity of heat accounted for by water evaporation was about 10% when the relative humidity (RH) is 80%. Finally, a linear relationship was identified between initial moisture content and the human skin burn injury time before suffering first- and second-degree burn injuries.

The impact of water on firefighter protective clothing thermal performance and steam burn occurrence in firefighters

“…The authors concluded that while moisture decreases the heat flux towards the skin, it increases thermal hazard due to higher stored energy in the garment. Huang et al [15] J o u r n a l P r e -p r o o f numerically studied the relative humidity (0-90 % R.H) effect on the thermal performance of a 3 layer protective firefighting jacket exposure to a flux of 5 kW/m 2 . They found a positive trend between relative humidity and second-degree burn time.…”