Yayoi Satsumoto

Evaluation of Overall and Local Ventilation in Diapers

A device to evaluate the distribution of the ventilation in diapers by using a tracer gas method (steady state method) was developed to investigate the effect of the design- and material-factor of diapers on heat and water vapor transfer by ventilation. This device can also evaluate the quantitative local microclimate ventilation rate during rest or walking between the interior of the diaper and the ambient atmosphere. Using forced ventilation, it was shown that the devices’ measurement captured the actual ventilation in the diapers. For the overall ventilation values it was found that the air permeability of the diaper fabric affected the ventilation but did not dominate it. It means the ventilation was affected not only by the air permeability but also by the construction and design of clothing. Leg movement caused about 20% increase of ventilation compared to the static condition. The ventilation of the pants design diapers were less affected by the movement. For the local ventilation values, the ventilation of the front upper site contributed heavily to the overall ventilation. The repeatability of the microclimate ventilation values measured by the steady state method obtained in our present study was better than that of the transient method reported in our earlier paper. It was demonstrated that the device allowed the evaluation of diaper design for the purpose of improving the microclimate in the diaper.

Evaluating Quasi-Clothing Heat Transfer: A Comparison of the Vertical Hot Plate and the Thermal Manikin

In earlier work, we used a vertical hot plate as a simple model of the human body, and it was important to determine whether or not our experimental results from the hot plate could really be applied to the body. Recently, thermal manikins have emerged as substitutes for the body, and this work tests whether or not the vertical hot plate can still be used as the substitute. Experiments are done with the abdominal segment of the thermal manikin and the vertical hot plate to investigate the effect of clothing construction factors like the size of air spaces and opening designs, open or closed, on quasi-clothing heat transfer. Results from the two methods agree with each other only when the size of the air space is 20 mm, and it is difficult to reproduce a setup with a precisely sized air space for the thermal manikin. The manikin has more experimental errors than the vertical hot plate, as clarified by results of the vertical hot plate model and the theoretical analysis that follows. The heat transfer coefficient of the open garment case is larger than that for the closed garment case, with proximity to the opening. In addition, the difference in the heat transfer coefficient is largest when the size of the air space is 10 mm. We have verified that the results of the vertical hot plate are helpful in understanding the results of the thermal manikin. Moreover, if the investigation of the effect of certain physical factors on heat transfer of quasi-clothing is performed analytically, it is not absolutely necessary to use a human model of actual dimensions, like a thermal manikin.

Effect of two kinds of quilt on the thermal comfort of subjects in a cold environment

Abstract The thermophysiological properties of two kinds of quilt, a ‘kaimaki’ and the popular square kind, which are matched in weight and fiber type of the wad, were determined by laboratory measurements, as well as by climatic chamber tests with human subjects. The thermal insulation rate of the popular square quilt specimen was a little larger than that of the kaimaki quilt in laboratory measurements and the average thermal insulation was almost the same with thermal manikin measurements. However, subjects preferred the kaimaki quilt with regard to thermophysiological comfort in climatic chamber tests under cold conditions. The thermal sensation of the upper arm of the subjects with a kaimaki quilt was also warmer than with the popular quilt, even though the upper-arm was covered by both types of quilt. This was because the kaimaki quilt covered the shoulders and the neck, which are some of the most sensitive parts of the body. Besides this, the closed construction of the kaimaki quilt prevented the penetration of cold air. This was confirmed by a simple hot plate model, which simulated the bed microclimate, which showed that air penetration accelerates convection in the bed microclimate.