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Thermal Performance of Fire Fighter's Protective Clothing Part 1. Numerical Study of Transient Heat and Water Vapor Transfer.


pdf icon Thermal Performance of Fire Fighter's Protective Clothing Part 1. Numerical Study of Transient Heat and Water Vapor Transfer. (392 K)
Prasad, K. R.; Twilley, W. H.; Lawson, J. R.

NISTIR 6881; 36 p. August 2002.
Order number: PB2003-10085

Keywords:

protective clothing; fire fighters; mass transfer; mathematical modeling; fire research; water vapor; heat transfer; thermal radiation; numerical models; moisture

Abstract:

This study is the first in a series of reports on understanding the performancThis study is the first in a series of reports on understanding the performance of fire fighter clothing, in protecting skin from thermal injury resulting from exposure to high intensity thermal radiation. A detailed mathematical model is constructed to study transient heat and moisture transfer through multi-layered fabric assemblies with or without air gaps. The model accounts for changes in thermodynamic and transport properties of the fabric due to the presence of moisture. Numerical simulations are performed to study heat and mass transport through wet thermal liners (used in fire fighter protective clothing), when subjected to a radiative heat flux from a gas fired radiant panel. Results were found to compare favorably with experimental measurements. The numerical solution is further analyzed to provide a detailed physical understanding of the governing processes. Moisture in the cloth tends to vaporise upon heating and part of it recondenses in the interior of the cloth. It was observed that the temperature of the fabric layers and total heat flux to the skin is significantly influenced by the amount of moisture and the distribution of moisture in the protective clothing. Finally, simulations are performed for a wet turnout coat assembly, to demonstrate the flexibility of the model for designing fire fighter protective clothing.