Thermal Conduction in Textile Fabrics Sandwiched between Planar Heat Sources

Abstract

The thermal resistance of ordinary textile fabrics is so small that in the measurements of thermal conduction by sandwiching a specimen between two planar heat sources, the contact resistance of the specimen to the surfaces of heat sources becomes relatively larger than the thermal resistance of the specimen itself. In order to analyze the heat flow in this situation, a model taking into account the contact resistance for reducing the thermal conductivity as a parameter independent of fabric thickness was proposed. The changes of heat flow rate with thickness for layered specimens composed of the same fabric were measured for a series of woven and knitted fabrics. The contact resistance of the fabrics used was about 1.31 m2 K/kW in average. The thermal conductivity calculated by the model showed a tendency decreasing with increasing porosity. The heat flow rate of layered specimens composed of different kind fabrics, which was calculated by the model from the contact resistance and the thermal conductivity of component fabrics, was in good agreement with measured values. The apparent thermal conductivity calculated by assuming the temperature difference between the specimen surfaces being the same with that between the heat sources showed an increasing tendency with increasing thickness.