Kaneko Takahashi

Numerical simulation of the effective thermal conductivity of wet clothing materials

Clothing materials may be considered composite materials composed of fiber, air, and moisture. For this paper, effective thermal conductivities of wet clothing materials were analyzed numerically using a proposed heat transfer model. The following simplifications were introduced. The clothing material fiber is woven with a single yarn, there is no air movement between fibers, and mass transfer is neglected. Numerical calculations were made using finite difference equations for steady three-dimensional heat conduction for several composite materials representing wet clothing materials. The main results obtained were as follows. The effective thermal conductivity of wet clothing material increases as the thermal conductivity of the yarn and the moisture content increase. We found that our numerical results agree qualitatively with those previously measured. The effective thermal conductivity of a wet layered material depends on the distribution of moisture and attains a maximum in the wet layer.

Effective Thermal Conductivity of Clothing Materials Coexisted with Conduction and Moisture Diffusion.

The effective thermal conductivity of the clothing materials in which heat flows accompany with mass transfer has been studied.The condition of this measurement may be more similar to practical use of the cloths.The experimental apparatus based upon the steady state comparison method is slightly modified in this study.The water tank is put on the heater and heat is flowed through the sample cloths upward from the heater that is placed at the bottom of the apparatus.The ordinary clothing materials used widely are selected as the sample.If the heater and the room temperature are kept constant, vapourizing rate η is scarcely independent of the number and the kind of cloths.The η, however, depends on the temperature difference between the heater and room temperature and relative humidity of the room.On the other hand, the temperature difference between upper and bottom surface of sample is nealy proportional to the number of cloths.Therefore, the effective thermal conductivity coexisting with heat conduction and mass diffusion may be evaluated by obtaining the sum of the thermal conductivity in the case that heat or mass transfers alone through the cloths.