As the moisture content of a fabric increases, the relative water vapor permeability (the relative heat flow responsible for the cooling of the body) also increases and the fabric temperature drops due to the evaporation of the water from the surface of the fabric. In this work on the experimental study of water vapor permeability of wet fabrics, the effect of air layers between the skin of the wearer and the fabric on the total relative cooling heat flow (cooling effect) experienced by the skin of the garment wearer is investigated. It was found out that when layers of 2- and 4-mm thickness were introduced between the skin and the fabric, the relative water vapor permeability or relative cooling heat flow was smaller than when the fabric was in direct contact with the skin, and in this case it did not depend significantly on the fabric moisture content.

This paper deals with thermal insulation and thermal contact properties of woven fabric assemblies used to produce men's jackets. An important part of the paper is the description of the new computer-controlled instrument, the Alambeta, to measure insulation and thermal contact properties of fabrics. The heat flow passing between the textile sample and measuring head during thermal contact is measured directly by a special thin sensor, whose thermal inertia is similar to that of human skin. Thus, the instrument's warm-cool feeling sensitivity aproximates human skin. Spotbonding the outer fabric interlining and lining together reduces the total thermal resistance of the assembly and simultaneously increases (makes cooler) thermal absorptivity, a new parameter used to describe the warm-cool feeling of fabric. The meaning of this parameter, which mainly reflects the surface properties of the fabrics and whose level does not depend on experimental conditions, is explained in detail. The effect of temperature drop on the thermal properties of the fabric assemblies is also investigated.The increased resulting thermal conductivity with the average temperature of the assembly is a consequence of the increased portion of the heat transferred through the system by radiation.

In the present work an experimental investigation was conducted to obtain a correlation for the determination of convective heat transfer coefficients of stirred yoghurt in a plate heat exchanger. A rheological study was carried out in order to characterise the stirred yoghurt flow behaviour, evaluating its dependency both on shear rate and temperature. A shift in the temperature dependency was evidenced at 25°C. It is also shown that the material shows a complex flow behaviour, changing from a Bingham fluid to a power-law fluid at shear stresses in excess of approximately 6.7 Pa. As regards the heat transfer behaviour of the non-Newtonian stirred yoghurt a correlation for the convective heat transfer coefficient was obtained that reveals the large effects of the thermal entry length due to the high Prandtl numbers and to the short length of the plate heat exchanger.

A theoretical discussion of a new method of measuring thermal properties, particularly the thermal handle of textilees, is followed by the description of a new Alambeta device and sensor developed for the purpose.

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