潜熱蓄熱(PCM)内装左官材のパッシブ蓄熱効果に関する研究

 The objective of this study is to report the passive thermal storage effects achieved by applying PCM (Phase Change Material) plastered wall. The PCM plastered wall is a novel finish material where PCM in the form of n-paraffin capsules are mixed with wall finishing materials, such as plaster. When applied on the wall, the PCM plastered wall can deliver excellent indoor environmental improvements and energy savings, because of thermal storage of solar heat gain on the wall. In this study, the effects of the PCM plastered wall are elucidated using an experimental module with triple glass window at Otaru, Hokkaido.<br> First, the measuring method of the basic thermal performance test of thermal storage building materials was examined. The analysis of basic thermal performance using radiant heating, convection heating, and conduction heating, showed that convection heating had the highest reproducibility. In addition, when measuring the specific heat and latent heat of solid and liquid phases, it was found that the heating rate of ambient air had a minor effect on the measurement results (Fig. 8, Fig. 9, and Fig. 10). In contrast, the measurement results of specific heat in the solid liquid mixed phase region tended to depend on the heating rate. To measure the basic thermal performance of the PCM plastered wall, we had to examine the heating rate and the temperature rising width. It was found that a heating rate of 20[min. /K] was required and for more than 10 °C width, except for the phase change region at the thermo-hygrostat.<br> Second, the effects of the PCM plastered wall on indoor environmental improvement and energy savings were elucidated using the experimental module. The glass surface temperature of the indoor side was approximately 60 °C during the day in winter (Fig. 17). The heat balance between direct gain and heat loss from the window was measured by installing a heat flow meter on the indoor side glass surface (Fig. 15, Photo3). According to the integrated measured value on the heat flow meter, the heat balance of the window glass during the measurement period was +16.2 [MJ/m²], where the heat gain was more than the heat loss. The experimental module consist of two rooms: the gPCM room (coated with granulated PCM plastered wall) and the PB room (plain). The room temperatures at both rooms were evaluated and compared. It was found that the gPCM room had a higher minimum ambient temperature than the PB room. (Fig. 20 and Fig. 24). When the maximum room temperature became higher than the melting point, the minimum room temperature at the gPCM room the next morning was observed to be 3 [K] higher than that at the PB room. Moreover, excess over heat due to direct gain from heating for 24h was suppressed and energy savings were achieved because of the delay in the heating start time (Fig. 21).<br> Finally, the energy-saving effects of PCM plastered wall were established. The influx and efflux of the material measured using the heat flow sensor revealed the thermal behavior of the PCM layer. By observing the heat flow fluctuation in the PCM layer, we found that equivalent thermal conductivity showed a large amount of heat storage, and a small amount of heat loss (Fig. 29 and Fig. 30). In addition, the equivalent surface heat transfer was about the same as that of the gypsum board (Fig. 32). Energy saving effects of the PCM plastered wall was 17% (average of the measurement period) in the experimental module installed at Otaru, Hokkaido (Fig. 33). The use of PCM plastered wall is a novel passive thermal storage method that can be located closest to the interior of the heat storage material.