Development and evaluation of methods in measurement of heat of vaporization for fabric and yarn

In this study, we focused on the heat of vaporization of clothing as a method of effectively cooling body temperature. In the first place, a method using a KES thermal analysis apparatus (KES-F 7-II, Thermo Lab II) was developed for the heat of vaporization measurement in fabrics. Although the heat of vaporization measurement of fabrics has been shown to be feasible, the measurement results have been indicated to be strongly influenced by the structure of the fabrics. Therefore, it was necessary to measure each yarn in order to compare the materials and the structure of the yarn. The heat of vaporization is exactly proportional to the amount of vaporized water. Therefore, it is considered that the cooling effect depends on how much water can be vaporized per unit time. Utilizing this theory, a method for measuring the heat of vaporization of clothing could be considered. Two types of methods were developed, one is a method using a high-precision balance under no wind, and the other is a method using a thermo camera in a wind environment. It was shown that the heat of vaporization in the yarn can be measured by measuring various test samples using these measuring methods. Furthermore, the relationship between the heat of vaporization and the structure of the yarn was examined by X-ray CT measurement. ©2021 The Society of Fiber Science and Technology, Japan