The solubility of LiBr in water is improved by adding 1,4-dioxane to a high-concentration aqueous LiBr solution, thus promoting the coordination of seven Li^+ ions around two tetra-coordinated structures consisting of ten water molecules, termed a 7:10 configuration. We measure the solubility of LiBr in water by constructing a cooling curve, and use the results to assess the effect of adding 1,4-dioxane to the LiBr-water solution based on thermodynamics. Measurements were carried out over a range of 17.3〜52.5mol/kg (60.0〜82.0wt%) LiBr and a molar water fraction of 0.92〜0.97. The following results were obtained: 1) The addition of 1,4-dioxane to a high-concentration aqueous LiBr solution is effective for increasing the solubility of LiBr in water over a wide temperature range. 2) The formation of the 7:10 configuration is promoted most at Xc=0.97, at which the solubility of LiBr in water is improved. The addition of 1,4-dioxane to such a system affords a 0.99 (J/mol・K) increase in entropy. 3) The difference between the enthalpy of the system measured before and after the suggested formation of the 7:10 configuration (-21200J/mol) is reasonably consistent with the theoretical stabilization energy of the 7:10 system (-23900J/mol), providing further evidence of the actual formation of the 7:10 configuration.

View full abstract

An advanced cylindrical tower-style thermal storage tank has been developed which features simultaneous storage of warm water and ice within a single unit employing ice-freezing coils. The tank, made of steel sheets, was installed at a new office building. By making use of thermal stratification, the principle of the tank's system is that it can simultaneously store warm water in its upper section, and ice, with a higher latent heating rate, in its lower section. To prevent warm and cold water from intermixing in the tank, a trap shaped density-stabilizing unit is installed in the middle of the tank. In the demonstration test we collected operational data from this novel thermal storage system for heating and cooling, by combining the tank and heat recovery heat pump during winter. The operational status of thermal storage and discharge was examined to analyze the nighttime peak-shifting factor, thermal storage efficiency, and energy conservation effects. The test results revealed that the tower-style thermal storage tank was capable for both practical and commercial use in buildings.

View full abstract

In the present research, a new method named "Index for Thermal Environment: ITE" is proposed for evaluating thermal sensation of human in sedentary posture at steady state. The results of this study are summarized as follows: 1. The following relation was obtained among the evaporation heat loss of sweat secretion, mean skin temperature and skin wettedness on a sedentary subject in the steady state. E_<reg>=α(1-βw)(t_<sk>-t_<sk,set>)exp(γt_<sk>) where, E_<reg>: evaporation heat loss of sweat secretion, W/m^2, w: skin wettedness, N.D., t_<sk>: mean skin temperature, ℃, t_<sk,set>: set point of mean skin temperature where sweat secretion occurs (=33.5℃), α, β, γ: constants (α=1.7×10^<-7> W/(m^2・℃), β=0.93N.D., γ=0.53l/℃) 2. The following relation was obtained among the thermal sensation, mean skin temperature and skin wettedness on a sedentary subject in the steady state. L(t_<sk>,w)=(t_<sk>-t_<sk,comf>)^2+H(w-w_<comf>)…t_<sk>≧t_<sk,comf> TSV=α(L(t_<sk>,w))^m TSV=-μ(t_<sk,comf>-t_<sk>)…t_<sk>≦t_<sk,comf> where, L: thermal load N.D., t_<sk>: mean skin temperature, ℃, t_<sk,comf>: mean skin temperature in thermally neutral state (=33.5℃), w: skin wettedness, N.D., w_<comf>: skin wettedness in thermally neutral state (=0.06N.D.), H, α, m, μ: constants (H=12.7℃^2, α=0.68N.D., m=0.71N.D., μ=0.941℃^<-1>) 3. Calculated values of ITE agree well with the experimental results within the range of "cold: TSV-3" to "hot: TSV+3". 4. The validity of ITE is confirmed under the various environmental conditions.

View full abstract

In this paper, we propose a new drainpipe with vortex chamber in order to free from danger of engulfing human body in the drain port of swimming pool, and show the basic flow properties of the drainpipe. The proposed drainpipe can control the suction force with the working of vortex flow. The drainpipe is constructed with thin vortex chamber, two tangential nozzles and one axial nozzle. The two tangential nozzles are connected with the two drain ports in the pool, and the axial nozzle is joined to discharge pipe. If the human body is sucked into the drain port, the vortex flow is generated in the vortex chamber. And then, the vortex flow restricts the flow rate. As the result, the suction force is reduced to safety range. In this system, it is worthy of note that the control action is performed with water flow itself without any mechanical equipment. In this study, the suction force and flow properties of the drainpipe were analyzed experimentally. As the results, it was evident that the suction force of the drainpipe is reduced drastically. In addition to that, the flow resistance of the drainpipe was smaller than the value of usual drainpipe.

View full abstract

Researches on airborne dust particulate have been focusing mainly on the analysis of the quality of air in a clean room. Therefore, not many reports on the airborne dust in a house have been published. The need for such research is immense since it affects the health problems in daily life. This paper will show the result of the research conducted on the airborne dust particulate produced in daily life activities. A measuring instrument, which can continuously trace airborne particulate, is used in this research to measure the density of the house dust with regard to the diameter of the dust. Our research made clear that the density of the airborne dust particulate reaches its highest peak either when one put the bedding down on the floor or put it away. Although the density kept changing during the night, it remained at a high rate. The result suggests the interrelation between the density of airborne dust particulate in a house and the daily activities. Further, larger particles seemed to fluctuate in wider range of density. An air cleaner was more efficient in removing the larger particles in the air. Fungi tend to adhere to the larger particles so that the air cleaner could remove them altogether. Bacteria, however, do not adhere to the larger particles and could not be removed.

View full abstract

Being confronted by the problems of global warming and depletion of energy source, we have to use limited energy effectively. By way of example, it is necessary to recover and store heat from plural waste heat sources of recoverable temperatures and use it as much as possible according to its temperature level. The application of TSHST (Temperature Selective Heat Storage Tank) to a heat utilizing system will be effective, because it can prevent the reduction of quality of thermal energy caused by the mixing supplied fluid with that of stored other temperatures and extract that of destined temperature with little mixing loss. The purpose of this study is to improve the temperature selectivity of the TSHST. This paper deals with the mixing mechanism of TSHST when higher temperature water is supplied to the TSHST of constant temperature, which is corresponding to the initial stage of heat storage process. Experiments were conducted by changing such parameters as supplying flow rates, supplying temperature, length of the storage tank and the position and the numbers of apertures on the sub-tank. It was proved that the outflow from the sub-tank through a damper generates mixing by inducing surrounding low temperature water until it surfaces. The method to predict the temperature distributions in the main tank was shown by using the theory of induction caused by plume. The temperature distributions of calculated results and experimental results were compared and fairly good agreements were obtained between them.

View full abstract

As a cogeneration system for residences, introduction of a fuel cell and a diesel engine is considered. About the fuel cell, a solid high polymer film type accompanied by methanol steam reforming is taken up. And a small kerosene diesel is taken up for the engine. The algorithm of an employment plan applicable to both systems was proposed, the energy demand pattern of the Hokkaido district was applied to this. And this paper searched for system operation which serves as the minimum of operation cost. As a result, it was found that the heat conversion and heat storage of electric power by an electric heater is effective against efficiency deterioration at the time of partial load. Moreover, it is thought that the fuel unit price of a methanol reforming type fuel cell is becoming half, the operation cost will be competitive.

View full abstract

A reliability analysis was carried out on an underwater drainage pump system. The Cumulative Hazard Analysis (C.H.A.) was employed to estimate both the shape and scale parameters of Weibull Distribution for the system's components, and nine years of actual failure and maintenance data were taken from the operation record of a building complex. As a result, the analysis for the underwater drainage pump system shows that the C.H.A. is effective in numerically analyzing failure phenomena and the prevailing maintenance maintains system reliability over 0.7 The underwater drainage pump system consists of series and parallel subsystems. The series subsystem has a relay, an ampere meter, electrode rods and a main pipe. The parallel subsystem has a pair of pump, cable, pipe and gauge. Fig. 1 shows the schematic of the system. Table 1 shows the shape and scale parameters of the Weibull distribution of some components, which had relatively many failures. The shape parameters of the electrode rods and the pipe are less than one, which shows that poor design/construction caused these failures. Since in fact there are several design mistakes, C.H.A. is a useful data analysis method. The subsystem failure rates of other components except three components explained above were estimated applying the theory of Drenick, which assumes an exponential distribution for a combination of component. The system reliability illustrated in Fig. 2 was calculated using the estimated parameters and the consideration of system functional structure (series-parallel subsystem) with and without maintenance. It shows that the prevailing maintenance maintains system reliability over 0.7. It is important to increase the number of fundamental reliability data. Computer-aided Facility Management System (CAFM) and Building Energy and Environment System (BEMS) and will be necessary in the future.

View full abstract

One of Kajima Corporation of the authors began a long-term observational study in January 1993 as part of IDMP (International Daylight Measurement Programme) of CIE (Commission Internationale de l'Eclairage). The present comprehensive study provides information for interior design by determining correlations among external meteorological factors such as solar radiation, illuminance, luminance, night radiation, temperature, humidity, and wind velocity. This paper (Part 2) reports luminous efficacy of daylight obtained by using minute-by-minute data of solar radiation and illuminance for the period of eight years and estimation of direct and diffuse illuminance from global horizontal illuminance through discussion by solar altitude, by cloud ratio and by sky ratio.

View full abstract