In this paper, we describe on the loads of water supply in apartment houses based on the analyses of actual measurements, the Monte Carlo Simulation and theoretical considerations. Firstly, the relations between the average and maximum volume of water supply and the number of flats are clarified, and the maximum flow rates at each interval of time, more than at one-minute intervals, are suggested for design as values of common and rare occurrences based on the analyses of results of measurements in 15 apartment houses. Instantaneous maximum flow rates at one-minute or less intervals are analyzed by the simulations and actual measurements. And it is clarified that the maximum value at one-minute intervals may be considered as the instantaneous maximum flow rate in the case of apartment house consisted of more than about 50 flats. Also, the relations between instantaneous maximum flow rates and number of flats are shown on the basis of the actual measurements of 10 apartment houses. On the calculation of instantaneous maximum flow rates, we suggest the convenient method utilizing the loading units, which are calculated by the Poisson distribution approximated as the probability distribution of simultaneous uses of water and the standard flow rates of apparatuses. The calculated results of instantaneous flow rates at each failure factor, 5% or less, are very near to the values calculated by simulation. Now, on the decision of the loading unit of a flat, we show two kinds of methods. One way is to sum up the loading units of each apparatus type at peak time of water consumption in the apartment house. Another way is to calculate by the Poisson distribution with mean value of simultaneous uses of water which is determined from the total volume of water supply and the standard flow rate of a flat. We clarify that it is suitable for the standard flow rate of a flat to be determined with 15(l/min) when we use the later method above mentioned. Lastly, we show the loading units of each apparatus type and a flat, and suggest the calculating curves of three levels, which are decided with the failure factor, 0.1, 0.2 and 1.0%.

View full abstract

In the analysis of flow in piping networks, dividing and combining losses at branches are usually ignored as being minor compared to the friction losses in pipes. But the losses at branches are not minor in many industrial piping systems. In this report, followed by previous ones, Part 1 and 2, the basic T-type dividing and combining flows with a dividing loss at the upstream branch and with a combining loss at the downstream branch are analysed. The results obtained are, 1) Basic T-type dividing and combining flow are classified into two types, type I and type II, according to the effect of a combining loss at the downstream branch to the flow. 2) The errors in the flow distributions and over-all loss coefficients caused by neglecting both losses at branches are calculated and illustrated in several graphs. The differences of the effects of both losses to the flows of type I and type II are clarified. 3) Arora's idea, "Flows in closed hydraulic networks will ajust so that the expenditure of system energy is minimum." is sasisfied only in the assumption that all the pressure losses in pipes are proportional to the n-th power of flow rate. When the variation principle in the flow distributions of piping networks becomes a problem, Millar's CONTENT function shoud be considered. The CONTENT function of the flow of type I are formulated and calculated.

View full abstract

A clean room with locally air-balanced supply-exhaust ventilation system installed at ceiling is studied by means of numerical simulation based on the k-ε two-equation turbulence model. The influences of the flow obstacle upon the flow and diffusion field and so on are precisely examined quantitatively. Results are as follows. 1) The ventilation efficiency in this clean room is well expressed by the SVE (Scale for Ventilation Efficiency) 1〜3 proposed by authors. 2) An arrangement of a flow obstacle below a supply jet have a rather great influence upon the flow and diffusion field of this type clean room. However the obstacle arranged between two supply jets have less influence than that below the supply openings. 3) The slight imbalance (less than 10%) of air volume rate in local supply-exhaust system has little influence on the ventilation efficiency. 4) The large imbalance (50%) of air volume rate in local supply-exhaust system reduces the ventilation efficiency of contaminant. It is confirmed that the locally closed circuit ventilation system (Locally Air-balanced Supply-exhaust Ventilation System) arranging supply and exhaust openings at ceiling is useful method for contamination control in conventional flow type clean room.

View full abstract

The object of this paper is to obtain some characteristics of reliability of the refrigerated container on a container ship. The research in this field has been so little that the reliability of the refrigerated container has not been identified. In this paper, we analyse the field data which have been gathered from the failure reports of the refrigerated container on board over ten years, and then investigate the characteristics of reliability and maintainability using the field data. Particularly, in the case of data analysis, we use a Weibull distribution which has taken a very important role in reliability analysis, and utilizing the Weibull probability paper, we get estimates of the characteristic values of reliability, that is, MTBF (Mean Time Between Failures), failure rate and so on. It is shown that these results are very useful in the field of maintenance and management of the refrigerated container.

View full abstract

The purpose of this study is to obtain the information on an underground space in which internal heat gain and heat loss through the wall are well-balanced in summer. Firstly in this paper, permissible heat gain was defined as an index of cooling effect in underground space. It means the maximum amount of sensible heat gain to keep the temperature in underground space under a maximum value using only economizer cycle. After that, effects of several factors on the permissible heat gain were calculated numerically. The factors considered in this study were depth and configuration of space, underground temperature, climate, convection due to subsurface flow, and so on. As the result of this analysis, it was seen that convection due to subsurface flow increase the permissible heat gain to a considerable degree.

View full abstract

The basis of industrial ventilation is to remove harmful materials near their sources with local ventilating apparatus or push-pull ventilating apparatus and to exhaust pollutants which spread out in factories without being removed by the local vent by general ventilation system. However, in the factories such as welding ones where the positions of fume sources are not fixed, general ventilation plays an important role because it is difficult to use the local ventilating apparatus. It is often observed also that a large amount of fume is generated during throwing metal chips into a furnace and pouring the molten metal from the furnace into a ladle. In such a case we have to rely upon general ventilation to maintain in the factories the clean air because it is hard to remove lots of fume completely with the local ventilating apparatus only. Many studies on general ventilation have been carried out by V.V. Baturin and other researchers. However, a clear explanation has not been made about the reason why a large amount of fume stays in the factories under some bad weather conditions. The purpose of the study is to investigate the reason why fume stays in the factories under some bad weather conditions and to propose an effective way to improve natural air change. As a result of the investigation based on Baturin's formulae for predicting natural air change, vertical temperature distributions in a real foundry and several model experiments, it was clarified that the stay of the fume was caused by the cooling of roof by rain. Especially, when the temperature of the roof falls under the outdoor temperature, the air change decreases rapidly. Based on numerical calculations for the flow fields in factories, the authors proposed the installation of the guide plates to the upper windows in the side walls as a way to improve the natural air change. As a result of model experiments, it was clarified that the installation of the guide plates was effective to improve the natural air change.

View full abstract

It is very difficult to analyze a measuring mechanism and also to obtain precise guide to design synthetically shapes about flow paths of a flowmeter of vane wheel type. This is caused by that the components of the flowmeter have complex nonlinear characteristics. On an estimate of measurement characteristics, estimating methods of static measurement performance for a stationary flow rate have been established. Estimating methods of dynamic measurement performance for a changing flow rate, however, have neither been defined nor regarded as sufficient. In this study, for a purpose to obtain the basic guide to design the flowmeter with high static and dynamic characteristics, the following matters are mentioned. 1) The measuring mechanism which is become clear by using a transfer function method. 2) The reference to estimate the static and dynamic measurement performance based on above analysis. 3) The guide to design shapes of the flow path by making the relationship between the flow path and measurement errors clear. As the results, 1) The occurring mechanism of measurement errors was made clear. 2) The guide to design a fluid frictional resistance and the relationship between the numbers of jet ports and that of vane were obtained, for the purpose to stabilize the static measurement performance. 3) The relationship between the fluid frictional resistance and the mechanical frictional resistance was made clear for the improvement of the dynamic measurement performance.

View full abstract

Although the re-evaporation phenomena at cooler fin surfaces have been totally neglected so far in designing commercial refrigerator and industrial air-conditioning systems, this paper demonstrates both experimentally and numerically that indoor humidity can be controlled more precisely by taking account of its effect. Under the circumstance as above, a numerical model equation is developed for predicting transient indoor humidity through a detailed theoretical analysis of moisture balance, which takes account of condensation and re-evaporation at the cooler fin surfaces when the air-conditioners are under and out of operation. A number of experiments was carried out by differentiating parameters such as the capacity of the refrigerating machine, and it was clarified that the predicted results are well compared with the experimental ones. A new design method based on the present model is also presented and discussed for selecting proper capacity of humidifiers.

View full abstract

There are many practical calculation methods of design air-conditioning load, but accuracy of design load obtained by these methods has been rarely examined. This paper discussed on precision of design air-conditioning load calculated by popular practical method. We asked some designers belonging to construction company or design office, for design load estimation in example case used by each designer's calculation method, and analyzed precision and characteristics of these load value. Nextly, we picked up two representative practical methods of design load calculation and made clear how much design loads are overestimated or underestimated compare to the reference range set by precise calculation.

View full abstract

In order to determine the design target values of residential hot water supply systems, we conducted experiments to test the preference of female subjects as to hot water temperature/flow rate in hot water usages such as dish washing, manual laundrying and face washing, using a hot water system of an experimental detached house. Based on the results of a questionnaire on subjects' life style and conditions of hot water usage, a water temperature assessment test for basic thermal sensation characteristics and 3 hot water usages in washing, we obtained simple aggregate, correlation, cross aggregate and quantification class-1, and analyzed subjects' preference concerning water temperature/flow rate and their behavior mode in hot water usages.

View full abstract

Having the possibility that both economical and energy saving aspects are improved by cascade utilization of exhaust heat as compared with conventional energy supply systems, gas turbine cogeneration systems are expected to play important roles in district heating and cooling. For the purpose of making positive use of this possibility, we should operate cogeneration systems by changing operational policy flexibly and intelligently according to seasonal and time fluctuation of energy demands and prices. In the Part 1, the authors proposed an optimal operational planning method on the basis of the above concept. The present paper describes an application of the method to introducing gas turbine cogeneration systems in a district heating and cooling project. The optimal operational planning problem is formulated as a mixed-integer linear programming problem, in which subject to constraints concerning equipment performance characteristics and energy balance relationships, binary and continuous variables for operational policy are determined so as to minimize the hourly running cost. The problem is solved numerically using an algorithm based on the branch and bound method. Annual running or total costs, and annual primary energy consumption are evaluated from operational policy determined through a year, and they are adopted as indicators for economics and energy conservation, respectively. The district studied here includes four office buildings and two hotels, and their total floor area is about 384000m^2. The gas turbine cogeneration systems considered are composed of cogeneration units, auxiliary boilers, steam absorption and electric compression refrigerators, heat exchangers, and other auxiliary machinery. The following types of cogeneration units are adopted as alternatives: type A: gas turbine-waste heat boiler system, type B: combined cycle and bleeding system, and type C: Cheng cycle system. In order to ascertain the validity and effectiveness of the optimization method, a comparison is first made between the optimal policy and the conventionally used thermal- or electric-following policies with respect to daily operational pattern and annual economics or energy conservation. At the same time, investigation is made into the influence of prices of purchased electricity and city gas on the optimal policy. Next, the above three types are compared with one another to find their differences in daily operation and annual total results. The main results obtained in the present study are as follows: 1) Using the optimal operational planning method, operational policy can be determined rationally from the economical viewpoint not only for gas turbine-waste heat boiler systems but also for combined cycle and bleeding, or Cheng cycle systems with high flexibility in operation. 2) It has been proved how the optimal policy reduces the annual running cost as compared with the thermal- or electric-following policies. It has also been made clear how the prices of purchased electricity and city gas influence the optimal policy. 3) Making good use of high flexibility in operation by the optimal policy, combined cycle and bleeding, or Cheng cycle systems show better economical and energy saving aspects than gas turbine-waste heat boiler systems.

View full abstract