Impact of moisture content and thermal exposure on the thermal protective performance of multilayered thermal liner

Abstract

This study evaluates the heat transfer index (HTI24) of a multi-layer thermal liner subjected to varying degrees of heat flux under radiant, flame, and 50 % radiant – 50 % flame exposure using a vertical thermal protective performance tester. A three-layer needle-punched nonwoven thermal liner with moisture levels of 0 %, 25 %, 50 %, 75 %, and 100 % is tested across heat flux levels (20, 30 and 40 kW/m2). Regression analysis identifies the relationship among the heat transfer index, moisture percentage in the thermal liner, and heat flux under different exposure types, with regression equations developed to calculate the HTI24 values. Moisture positively influences HTI24 during different flame exposures. However, at lower levels of radiative heat flux, water percentage increases the HTI24 value, while at higher levels, water percentage has an adverse impact on the HTI24 value. These findings highlight the complex interplay of moisture percentage and thermal conditions in optimizing thermal protective performance.