Influence of PCM incorporation on thermal performance of fire protective clothing subject to wet exposures

Firefighters tend to face a diverse set of environments comprised, not exclusively, by high heat intensity exposures. Hazards caused by water exposure such as steam burns may occur but have only been studied for a limited set of conditions. Sudden water exposure to a donned fire protective clothing (FPC) assembly in the post-fire phase has been recently shown to be hazardous to firefighters, causing second-degree burns. To mitigate this effect, in this work, the incorporation of PCMs in the textile layer near the skin (i.e. thermal liner) of the FPC is modeled and suggested as a potential solution. More specifically, a heat and mass transport model of an FPC incorporating PCMs is elaborated and utilized to compute heat and mass flux debits as well as PCM phase change in the post - fire phase. Heat and mass transfer mechanisms are identified in the post - fire phase as well as second-degree burn occurrence is checked for utilizing the Henriques burn criterion. The influence of PCM mass incorporation (i.e. textile latent heat) and PCM melting/solidification temperature on water exposure hazard prevention is established through parametric analyses. A textile fiber latent heat of 70 J PCM /g textile obtained by Rubitherm® RT44 HC PCM incorporation into the thermal liner ensures no skin burn occurrence. Furthermore, if the thermal liner fiber fraction is increased by just 4% (i.e. 4% decrease in porosity of the thermal liner), PCMs with melting and solidification temperatures up to 70 °C can be safely incorporated for skin burn prevention.