THE EFFECT OF AIR GAP THICKNESS ON HEAT TRANSFER IN FIREFIGHTERS' PROTECTIVE CLOTHING UNDER CONDITIONS OF SHORT EXPOSURE TO HEAT

Abstract

In this paper, the mechanism of heat transfer through the air gap between the layers of the fire protective clothing (FPC) and human skin under conditions of relatively short exposure to heat is studied. In the experiments, the thickness of the air gap varied from 0 mm to 10 mm with a step of 1 mm. The temperature on the simulated skin increased with the air gap until the thickness reached 7 mm. During a further increase from 8 mm to 10 mm, the temperature remained the same, and a little change could be observed. Corresponding to the experimental results, the Rayleigh number exceeded a value of 103 when the air-gap thickness was larger than 7 mm, and the convective heat transfer in the air gap cannot be ignored.