Heat Transfer In Protective Clothing Research Articles

Numerical simulation of heat transfer in protective clothing with various heat exposure distances

This paper reports on a model of heat transfer through multi-layer firefighter protective clothing with an air gap under radiant heat flux of 8.5 kW/m2. The model considers the dynamical changes of heat exposure distance due to human body movement. The predictive results were found in good agreement with the experimental measurements. Numerical model was employed to study the effects of heat exposure distance and moving speed on heat transfer in multi-layer fabric system. The results showed that the heat exposure distance had an significant impact on skin burn. The safe zones for firefighting operation were more than 0.3 m for 2nd degree burn and 0.15 m for 3rd degree burn when the fabric system was exposed to 8.5 kW/m2 for 300 s. However, the moving speed could speed up the time to 2nd degree burn but alleviate the time to 3rd degree burn.

Influence of the air gap between protective clothing and skin on clothing performance during flash fire exposure

A finite volume model was developed to simulate transient heat transfer in protective clothing during flash fire exposure. The model accounts for the combined conduction-radiation heat transfer in the air gap between the fabric and skin. The variation in the fabric and air gap properties with temperature and the thermochemical reactions in the fabric are also considered. This study investigates the influence of the air gap in protective clothing on the energy transfer through the clothing and hence on its performance. Different parameters that affect the conduction-radiation heat transfer through the air gap such as the air gap absorption coefficient and the air gap width were studied. Finally, the paper demonstrates that an innovative and potentially significant way to improve protective clothing performance is to reduce the emissivity on the backside of the fabric.

Numerical Simulation of Transient Heat Transfer in a Protective Clothing System during a Flash Fire Exposure

A finite volume model was developed to simulate the transient heat transfer in a protective clothing system. The model domain consists of a fire-resistant fabric, the human skin, and the air gap between the fabric and the skin. The model uses a more sophisticated treatment of the air gap compared to previous models: it accounts for transient combined conduction-radiation heat transfer within the air gap and includes the variation in the air gap properties with temperature. Predictions were obtained for the temperature and heat flux distributions in the fabric, skin, and air gap as a function of time, as well as the time to receive skin burn injuries. The numerical model was used to explore the physics of heat transfer in protective clothing, which could potentially be used to improve the performance of this clothing. This study illustrates the dependence of the temporal behavior of the heat fluxes on the specific model assumptions, as well as the associated sensitivity of skin burn predictions to these assumptions.