Experimental investigation of heat transfer and thermal protective performance of flame-resistant fabrics exposed to different intensities of fire

This study focused on the three-dimensional heat transfer process between flame-retardant fabrics and the air gap beneath the clothing under varying flame intensities. Thermal protective performance testing as well as fabric appearance and heat shrinkage measurements were conducted on single and multilayer fabrics at two heat flux levels. The impact of the heat source, fabric layers and air gap was investigated. Through the two-dimensional visualization of temperature distribution, the distribution was uneven due to local heat sources, affected by the heat source density and fabric layers. Multilayer fabrics demonstrated superior thermal protective properties to single-layer fabrics, and exhibited higher temperatures and stored more heat. The air gap thickness significantly influenced the thermal protection of the fabric system (p < 0.01), and opening the boundary did not always enhance thermal protective performance, as this depended on the internal heat transfer mechanism of the air gap.