ASSESSMENT OF THE THERiMAL INSULATION PROPERTIES OF CLOTHING

At the present time there are various methods known for testing the thermal insulation properties of materials. These simulate condition when air-penetrable clothing is worn in wind. A detailed survey of these methods is given, for-example-in. However, conditions for testing thermal insula-tion properties of materials in models differ from conditions for testing air-penetrable clothing in i tnd. To assess the degree of difference and the authenticity of the results achieved it is essential to examine the physical processes which govern the transfer of heat through air-penetrable clothing in wind. We will look at clothing as if it were a multi-layered cylindrical package containing an air layer (Fig. 1). The thermal insulation properties Lf clothing are a:cepted to be the sum thermal resistance, which is (Fig. 1) the sum of the thermal resistance to heat emission from the external surface Rsurfac-of the external package R external ' of the air layer Rair ' and of the internal package R internal When there is an increase in wind velocity and th