Ryota Kobayashi

Investigation of comfort temperature, adaptive model and the window-opening behaviour in Japanese houses

This study described in this paper was undertaken to investigate comfort temperatures and related behaviours in Japanese homes. In it temperatures were measured in the living rooms and a thermal comfort survey of residents and related window-opening behavioural survey was completed over a full year in the Gifu region of Japan. The residents were found to be highly satisfied with the thermal environment of their houses. Significant seasonal differences were found in their comfort temperatures. The results showed that comfort temperature changes varied with changes in both the indoor and outdoor climate. The strength of the relationship between indoor and outdoor temperatures justified the adoption of the adaptive model for both prediction and design of control strategies for the provision of indoor comfort. The window-opening behaviours were shown to be related to both the indoor or outdoor air temperatures. The deadband was narrower and constraints on the window opening in the houses investigated were both considerably lower than previously found in office building studies. The adaptive model is highly supported by this study of occupant perceptions and window-opening behaviour.

Fundamental research on gas–solid reaction between CO{sub 2} and Li{sub 2}CuO{sub 2} linking application for solid CO{sub 2} absorbent

Abstract We compared reactivity between CO2 and Li2CuO2 with that between CO2 and Li4SiO4 by using XRD, SEM observation, and thermogravimetry in order to study fundamentally a potential of Li2CuO2 oxide for application to solid CO2 absorbents. The CO2 absorption ability of Li2CuO2 was examined by measuring rate constants for the gas–solid reaction between perfectly single-phase Li2CuO2 and CO2 at various temperatures in 100xa0vol% CO2 atmosphere using the rate theory with thermogravimetry using rapid heating. The measured rate constants were compared with those reported previously for Li4SiO4 at various temperatures. Almost no difference was found between these rate constants of Li2CuO2 and Li4SiO4 at temperatures less than 660xa0°C, but at temperatures higher than 670xa0°C, the rate constants of Li2CuO2 were greater than those of Li4SiO4. These results demonstrate that Li2CuO2 can outstrip the ability of Li4SiO4 to absorb CO2. Moreover, different from Li4SiO4, the CO2 absorption ability of Li2CuO2 decays only slightly, even if the atmospheric CO2 concentration decreases.

Analyses of Microstructure and Oxygen Content Effects on Thermal Conductivity of AlN Ceramics by Using Slack’s Plot

In this study, we analyzed the effect of microstructure and oxygen content on the thermal conductivity of dense AlN ceramics by Slack’s plot, which plots the oxygen content estimated from the lattice parameter c versus the thermal resistivity, which is inverse of the thermal conductivity. The analyses were carried out for the AlN ceramics sintered with oxide additives such as Y2O3, Y2O3-Al2O3, or Y2O3-CaO-B. The data of AlN ceramics sintered with Y2O3 or Y2O3-CaO-B located on the plot of the relation between oxygen content in AlN lattice and thermal resistivity of AlN presented by Slack (Slack’s line) or Harris et al (Harris’s line), respectively. In contrast, the data of the sample sintered with Y2O3-Al2O3, which contains excess grain boundary phases, located above the Harris’s line. These results suggest that the thermal conductivities of AlN ceramics are influenced by not only the oxygen contents in the AlN lattices but also the contents of grain boundary phases.