The fact that heating and cooling systems using solar energy are technically feasible has already been proven by a number of experimental installations; however, advantages of such systems over conventional systems in terms of energy conservation and total economy have not yet been completely clarified. The study presented in this paper has been done in an attempt to obtain some information necessary for optimizing the design of solar heating-cooling systems with the aid of computer simulation. In Part 1, the HVAC systems which were studied, mathematical models of equipment used in such systems, and computation algorithm are described.

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This report presents a simple method for calculation of the performance of the supersonic gas ejectors which employ various gases as driving fluid and by which various gases are entrained. Many types of ejectors are widely used in the industries, for example, as ventilators in air conditioning or environmental and sanitary facilities, or as exhausters of various gases in the chemical plants. The kinds of driving gases and entrained gases of the ejectors are increasing, and a simple and useful method for calculation of the performance and design of the gas ejectors is required. The present study is one of answers for these requirements, but it treats only supersonic gas ejectors. For the efficiency of supersonic ejectors with supersonic nozzles is higher than that of subsonic or low pressure ejectors with subsonic or converging nozzles. On the other hand, although the noise in running of supersonic ejectors is troubled, the trouble of noise can be resolved by adoption of the multiple nozzle supersonic ejectors as shown in the author's previous report. For simplication of computation, the author uses the expression of the relations of adiabatic gas flows as functions of Mach number and the total pressure ratio for estimation of flow losses in nozzle, entrained gas flow path and diffuser, and developes a simple method and equations for calculation of the performance (i.e. relation between compression ratio or adiabatic efficiency and flow ratio) of supersonic ejectors under the following assumptions: (1) one dimensional flow (depending only state values of gases and independent of the distance of flow direction; (2) ideal gases (pv=RT); (3) adiabatic flow; (4) mechanical mixing (with no chemical reactions) and (5) generation of normal shock following completion of mixing. By application of the method and equations to the calculation of performance of supersonic gas ejectors which are used for various kinds of gases, and comparison of the computational values and the experimental values by the other investigators such as L.T. Work and V.W. Haedrich, and it is made clear that the method is valid and useful for practical applications, and besides that the present method can be applied not only to the supersonic gas ejectors with cylindrical-diverging diffusers but also to the supersonic gas ejectors with converging-cylindrical-diverging diffusers, such as steam ejectors, which are used for high inlet pressure ratio and small flow ratio. After demonstration of validity and usefulness of the method and equations, the effects of flow losses in nozzle, entrained gas flow path and diffuser on the performance are investigated making use of total pressure ratio of each part contained in the equations, the effects of mollecular weight of gases on the performance are also investigated. In conclusion, it is made clear that: (1) The present method for caluculation of the performance of supersonic gas ejectors is valid and useful. (2) The effect of flow losses in nozzle on the performance is not negligible in the case of the ejectors for high inlet pressure ratio and small flow ratio but negligible in the case of the ejectors for low inlet pressure ratio and large flow ratio. (3) The effects of flow losses in entrained gas flow path is negligible. (4) The effects of flow losses in diffuser is serious. (5) The compression ratio is larger for larger molecular weights of driving gases and entrained gases, but the effects of molecular weights of gases on compression ratio is small. The effects on adiabatic efficiency, however, is large. In addition, a method for the design of the optimum ejectors will be discussed in the second article.

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The first report presented a simple method for calculation of the performance of the supersonic gas ejectors, and described the usefulness of that method and the effects of the inner flow losses and the molecular weights of gases on the performance. In this second report, a method for the design of the optimum ejectors is discussed. Most of old design methods were basd on the experiences and they were not always useful for inexperienced gases or inexperienced applications. In the present report, the method for the design of the optimum ejectors is based on the analysis of inner flow conditions of the supersonic gas ejectors, and it is generally useful for various kinds of gases and wide applications. Besides the basic conception of the optimum flow conditions in the optimum supersonic gas ejectors and the right comprehensions are of service for the users of many types of ejectors in the air conditioning or environmental and sanitary facilities as well as for the designers. In the general case of designing gas ejectors, the kinds of driving gases and entrained gases, their physical properties (pressure and temperature), required mass flow of entrained gas and compression ratio are given. The ejector which can satisfy these conditions by the minimum mass flow of driving gas is called the optimum ejector. The geometrical conditions for the sake of the optimum ejectors are called the optimum design conditions. It is exactly the problem of design to decide the geometrical conditions. The author applied the method for calculation of the performance, which was described in the first report, in order to find the relations between the performance and the inner flow conditions according to the classification by Ю. Н. Васильев, and established a method for the design of the optimum supersonic gas ejectors. In conclusion, it was made clear that the maximum performance can be obtained in the case of that the driving supersonic nozzle acts as an underexpanded nozzle, the speed of entrained gas reaches the sound speed in the initial mixing region, and the flow of mixing gases generates normal shock in the cylindrical part of the diffuser, the type of which should be supersonic, i.e. converging-cylindrical-diverging type. In the present report, the method for computation is precisely explained and the performance curves of the optimum gas ejectors are presented as examples of numerical computation. Lastly the method of application of these performance curves to designing the optimum ejectors is described. The author wishes to express his profound sense of gratitude to Dr. Susumu Murata, Professor of Osaka University, who suggested the problems.

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Our research on the process of heat storage in heat regenerative water vessels for air conditioning was previously published in a series of three papers, of which title is "Heat Storage Analysis of Water Reservoirs as Heat Source for Air Conditioning Systems". The fluid behavior in such water vessels was also qualitatively analyzed through a visualization technique of flows as reported in 4th paper, "Cold and Warm Water Behavior in Heat Regenerative Water Vessels for Air Conditioning". This paper will report on several approaches made upon the data and information obtained through the above-mentioned research, to design the water vessels most effectively.

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This study relates to the cooling and heating effect by a natural convection type cooling/heating unit installed in the ceiling plane right above building perimeter. The test was conducted at a mock-up room with facilities to control its exterior (outdoor) temperature condition in -20℃〜+35℃ variable range. Under this variable outdoor air temperature, measurements were made on the convection and heat radiation in the test room. Extensive reference was then made to the effect given on human body. This report particularly deals with the radiant effect in heating cycle. The test result obviously shows reduction of cold draught stream along window face and cold temperature radiation through window glass. Assuming a total surface of a human body of 1.8 square meters, the net radiant heat upon the human body will come in 50kcal/h and 30kcal/h when heating water temperatures are 75℃ and 55℃, respectively. The test results conclude that a sufficient amount of radiant effect can be expected even at such low temperatures. When this radiant-heat unit performs, the mean radiant temperature MRT in the test room rises 2.4〜3.2deg when water temperature is 75℃, and 1.5〜2.1deg when water temperature is 55℃. As the MRT rises, the effective temperature also increases; approximately in the order of 1.5deg and 1deg when water temperatures supplied are 75℃ and 55℃, respectively. Approximately 50% of the unit's heating capacity is transmitted to the room by radiation of ceiling panel, and the remaining 50% heat by convection plus ancillary radiation effect of warm air layer which moves along ceiling plane very slowly. As for temperature distribution in the room, the following results were obtained; at the point 0.5 meter away from the window face, floor temperature gets low by a direct effect of temperature radiation of cold window glass and down ward cold draught stream along window face, yet at the point 1 meter away from the window face, all temperatures measured at floor level, 0.5 meter and 1.5 meters levels above floor, fall under ±0.5deg fluctuation range of the mean room temperature. At any points 2 meters or more away from the window face, the floor temperatures get even higher than the temperatures measured at the plane 0.5 meter above floor,where by the test results set forth pattern of temperature distribution in the room the getting assumingly similar to that obtainable by the ceiling radiation panel heat systems. The study here to will develop here after to the extensive comparisons with the experimental data on the room environments by several conventional heating systems.

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In this study, the word train wind is defined as the wind generated by the piston movement of a train running in a tunnel. Because of the increasing number of passengers and trains running recently, the quantity of heat generation caused by them in a subway has increased. Moreover, owing to the lack of well water to absorb the above heat generation, the increase in air temperature at platform of stations as well as in tunnels is remarkable, which requires a cooling facility in summer thus making the sole employment of ventilation insufficient. Starting in 1971, cooling facilities had been employed by two stations in the subways, followed by successive employment and planning. Among the various cooling loads considered for subway stations, the load generated by train wind is the most difficult problem for the designer due to the lack of relative design data. The behavior of train wind, that is, how it carries off the cooled air of the platform and how it brings the warm air of the tunnel onto the platform, must be known for it is an essential factor. In the subway, we must observe the repeated movements which include the start, increase in speed, running with constant speed, slowing down and stopping of a train with a length of approximately 150 meters. The purpose of this study is to quantitatively analyze the transient phenomenon of the velocity of train wind and air discharge quantity at the time of the above mentioned movements so that the design data for an air conditioning facility in subways can be obtained. In this report, a model of a tunnel (30 meters length) with a single line, and without a ventilation hole and platform was prepared. The relation of the speed of the train with the velocity of train wind and with the air discharge quantity were experimentally obtained through the movements of a model train (1set) from start to finish in the tunnel model. In addition, paramenter identification was employed based on the above experimental data. Thus the authors proposed a theoretical equation (non-linear differential equation) of motion on air in a tunnel, taking the approximate model of the actual system into consideration.

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In the previous paper, the authors presented the experiments for train wind generated by the piston movement of train running in a tunnel model, and proposed a theoretical equation of motion on air in a tunnel. In this report, the parameters were identified employing both the experimental data obtained in the previous report and the theoretical equation (non-linear differential equation) of motion on air as a mathematical model. In addition, the factors which are considered as influencing the air discharge quantity were analized through various simulations. In this report, the estimated values on the parameter which enables the difference between the output of the simulation model and the experimental data minimum were obtained. In other words, the index of performance of the simulation model was minimized. The above method of analysis has been known and widely adopted as the parameter identification of time variant systems in the field of modern automatic control theory. The thoeretical calculation method established above enables easy simulation of train wind velocity and air discharge quantity when the train speed, as an input, is the arbitrary function which would usually appear in the actual case. Moreover, the simulation for a tunnel 100 meters in length, for example, can be performed in the same way. In addition to the above, in the case of an actual tunnel with a straight single line and with openings at both ends where the train starts, increases speed, runs with same speed, slows down and stops the behavior of train wind can be satisfactorily assumed if the approximate values of each parameter are known. However, the conditions of an actual subway tunnel are not so simple because of the following questions: How should the ventilation holes and platforms be treated? How should the mass of air be evaluated? These problems, along with the double line tunnel and actual measurements, etc., will be analyzed by the authors in a future issue.

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There are considerably many literatures on the flow of single branches with adequate inlet length along upstream main duct, however data on cross-shaped branch pipe line with symmetrical lateral pipes are found few. In previous reports, an experimental study of this kind of branch pipe lines was made, and it was found that, when the discharge flow rates to the trifurcated pipes were divided into a certain ratio, an unexpected increase of energy losses occurs and the noticeable fluctuations of flow exist. From the experiments in order to explain these flow phenomena, the following two facts became clear. The first is that these energy losses are mainly caused by the occurrence of an intensive secondary circulation which swirls about the lateral axis in either a clockwise or an anticlockwise direction. The second is that the pressure and velocity fluctuations in the neighborhood of the branch part are caused by changing in direction of the secondary circulation. The purpose of this report is to express the loss coefficients in cross-shaped branch pipe line with circular cross section, and to offer data to practical application. First the equations to estimate the energy losses of flows in the trifurcated pipe have been given by making use of energy and momentum equations. The loss coefficient, ζ_<b2m>, for lateral flow was given as ζ_<b2m>={1-F(n_1)}-2ksinε・(1-n_1)n_2+(1-n_1)^2n_2^2…(1) in which n_1 is the ratio of flow rates of one lateral to those of the upstream portion of main pipe and also n_2 is such ratio about the lateral of opposite side, F(n_1) means a function of n_1 and 2ksinε is coefficient which is determined experimentally. Similarly the loss coefficient, ζ_<cm>, for main flow was given as ζ_<cm>=2(k_1cosε_1-1)n_1+(1-ξ)n_1^2+2{(k_2cosε_2-1)+(2-k_2cosε_2-ξ)n_1-(1-ξ)n_1^2}n_2+(1-ξ)(1-n_1)^2n_2^2…(2) in which each coefficient of n_1, n_2 are to be found experimentally. The above two equations are limited to express ζ_<b2m>, ζ_<cm> qualitatively as the function of n_1, n_2, so that the expressions in practical use for the loss coefficients were derived semi-empirically. Moreover if the loss coefficients of energy losses due to the downstream secondary circulation are illustrated against the ratios of flow rates to the downstream portion of main pipe, it can be expressed approximately with a curve having a maximum value regardless of the values of n_1, n_2. It was obvious that such loss coefficients were in approximate proportion to the angle between local axial and transverse velocity components i.e. the local swirl angle. The contents described in this paper may be summarized as follows: 1) The law of momentum was applied to the flow in the cross-shaped branch pipe line, and thus the loss coefficients for lateral flow and for main flow were expressed theoretically as the function of the discharge ratios into two laterals. 2) Under the consideration about the flow mechanism as described in the previous reports, empirical formulae for the loss coefficients were derived, and from these values the total loss coefficients could be obtained. 3) It became clear that the coefficients of energy losses occurred in a certain discharge ratios could be obtained approximately by adding the loss coefficients due to the secondary circulation to those based on the law of momentum. 4) It has been made an experiment for cross-shaped branch pipe line with square cross section, and the loss coefficients were compared with the data of those of circular cross section and discussed.

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In order to establish the optimum design and operation of the refrigeration system for energy conservation, the computer simulation is conducted to obtain the operating performance of the refrigeration system. The fundamental equations for simulation and logic flow diagram are prepared and a simulation program is set up. Then the simulation results are verified by the actual operating performance of the machines. Power consumption is investigated in accordance with the variations of output, chilled water temperature, outside wet bulb temperature and surface area of condenser or evaporator. A study is made on the sequence control for three machines.

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