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Experimental Study of the Heat Transfer in Air Spaces Between Protective Fabrics and Sensors in Protective Clothing Tests
Chris M. J. Sawcyn and David A. Torvi

Heat transfer in horizontal enclosures found in common bench top tests of thermal protective fabrics was investigated using flow visualization, videotape observations and temperature measurements. These enclosures were partially heated from below for 10 s using natural gas and propane burners, which produced nominal heat flux exposures of 60 and 80 kW/m2 on the bottom boundary. During these exposures, the temperature difference across the enclosure increased by several hundred degrees Celsius in a few seconds. The nature of convection cells and Rayleigh number histories in the enclosures were compared for the two heat fluxes. Videotape observations and temperature measurements were used to determine the shape of isothermal surfaces on the bottom boundary. These experimental results have also been used as input data for numerical models of radiation and convection heat transfer in air spaces in protective clothing tests.

Keywords: Protective clothing, fire science, natural convection, enclosures, radiation, flow visualization, testing.

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