Abstract
Effective thermal condutivity was measured for clothing materials in wide-spread use, ranging from thin woven fabrics to thick packing materials for winter garments. Measurement was carried out by the steady-state method and under the standard air condition using the Thermolabo (KESF-TL-2D). The measured thermal properties of clothing materials were studied in relation to their structural properties (thickness, weight, and volume fraction). An empirical formula for the effective thermal conductivity, λe, was presented, based on a simple model that includes the radiative heat transfer as well as the heat conduction through the mixture of fiber solid and air, and was compared with the results of measurement.
The resuts are summarized as follow :
(1) The thermal conductance λed decreases nearly inversely proportion to the thickness d for fabrics of d≤0.5 cm, whereas for thick materials (d≥1cm), it grows independent of the thickness. Consequently, A is constant around 0.04 W/mK for d≤ 0.5 cm and the volume fraction φ=10∼30%, while it isabout three times larger for d≥1cm andφ≤6%.
(2) An empirical formula suggested here well corresponds to the measured values of effective thermal conductivity.It is shown that for thick materials of d≥1.0cm, the thermal transmission is dominated by the radiative transfer.
(3) From the application of the emprical formula to the result, the proper heatconductivity of the fiber solid was shown to be estimated reasonably and the effects of structure on the thermal properties of clothing materials were also examined.
