Basic Research on Optimization of Heat-Retention Characteristics of Fiber Bulk Materials

Abstract

The objective of this study is to investigate the possibility on the variable thermal resistance of fiber bulk materials as a heat insulating bedquilt for keeping a human being warm and comfortable independent upon the change in the environmental temperature. The system for maintaining the optimum thermal condition in the bed was realized by varying the porosity of the fiber bulk materials using the deformation of the thin wires of shape memory alloy by the temperature change.The relations between the porosities and the apparent thermal resistances of the typical three kinds of fiber bulk materials were measured. As a result, it was clarified that the possible variable range of the apparent thermal resistance is about the double for the cotton fiber bulk materials with polyester fibers. Mixing of the fine metal wires, which is a substitute for shape memory alloy, had little effect on the thermal resistance in the range of the mixing fraction.Furthermore, the considerations on the thermal characteristics of the fiber bulk materials were performed using the numerical analysis assuming heat conduction and radiation heat transfer. Finally, the experiment on the change in the volume of fiber bulk materials and in the thermal resistance was carried out actually by mixing the fine wires of shape memory alloy..