Surface Temperature Measurements for Estimating Relative Heat Flow Through Textiles

Abstract

The heat flow through a variety of textile and related materials, at different relative humidity, temperature, and moisture transport combinations was satisfac torily predicted from the calculated thermal transmittance values times either (a) the temperature difference between a heated plate over which the material was suspended and the ambient room air above the material, or (b) the surface tem perature of the material measured by color changes in temperature-graded liquid crystal film strips placed on the material times a constant. Temperature differences were obtained by measuring the respective plate, fabric, and air temperatures with liquid crystal film strips and with a point-source radiation device. Calculated heat flow values using a and b were compared to those measured on a mixed flow thermal transmittance apparatus. A method of interpolating fractional temperature in the liquid crystal film strips was also devised. The latter affords an inexpensive method of predicting heat flow through textile substrates covering a body of uniform tem perature.