This report describes an experimental study carried out to investigate the thermal storage efficiency of a submerged weir-type thermally stratified hot water storage tank by measuring transient temperature responses, under various hot-cold water temperature differences, flow rates, and tank configurations. From the experimental results, the semi-empirical equations suitable for predicting the thermal storage efficiency in the thermally stratified region, η_<v_1>, and that in the whole region of the tank, η_v, were deduced as the function of the Archimedes number based on inflow conditions, Ar_0, the Peclet number, Pe, the dimensionless residence time of water in the thermally stratified region, τ_<v_1>, and geometric parameters, φ_1 and φ_2.

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This paper reveals the way to compute air flow disiribution in a room, of which space is connected with outdoor and/or other room spaces through clearances, ducts or opennings, etc.. This computational method originates from the MAC method, or in more general, the difference method with the same code as MAC method. The thinking way of MAC method can be adopted for such cases naturally and easily, and a simultaneous nonlinear equation concerning pressure can be obtained through the equation of continuity. This equation has some features facilitating the solution. Using nonlinear SOR methods to solve this equation was considered and examined. As a result, the authors found that a special caution is needed for the accuracy (the accuracy of the Computed Value of SOR method) in the numerical solution of the nonlinear equation at the boundary cell connected with other space. For the future computation, the convergence of four nonlinear SOR methods were tested numerically. A simple two-dimensional program, computing the above air flow and evaluating the distrubution of the thermal comfort index and thermal load, was also accomplished and executed by the authors. It appears that three-dimensional computation may be possible also.

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A miter-tee is frequently used in industry. But its flow mechanism has scarcely been clarified in detail. So, in the first place, the flow pattern in a miter-tee with the branching angle of 90° and the sharp-edged corners of the lateral entrance, which is a most fundamental shape, was studied for laminar flow. But the areal ratio m was chosen to be equal to 1.0, 1.5 and 2.0. The Reynolds number Re_<1h> was taken to be less than or equal to 200. The obtained results are summarized as follows: 1) The Navier-Stokes equations describing the steady, two-dimensional, laminar flow field of incompressible fluid in the miter-tees were solved numerically by means of a finite difference relaxation method when Re_<1h>, covered a range between 1 and 200. The influence of m, Re_<1h> and the ratio of lateral discharge to total discharge Q_3^*/Q_1^* upon the flow through the miter-tee was investigated. Generally, the effect of the flow dividing in the lateral conduit is larger than that in the main conduit. Also, its degree in the lateral conduit grows when the separation from upstream edge of the lateral entrance occurs. 2) The flow field in the real miter-tees was studied experimentally by means of a flow visualization technique when Re_<1h> covered a range between 5 and 200. The flow pattern is observed to be very complex when Re_<1h>≧70. But the flow adjacent to the center-line plane is always observed to be two-dimensional, and at Q_3^*/Q_1^*=0.0 a portion of the flow from the upstream section of the main conduit is observed to flow into the lateral conduit shut off independently of m and Re_<1h>. 3) The results obtained by the numerical analysis and the experiment coincide qualitatively well. When Re_<1h> is sufficiently small or Re_<1h> is large but Q_3^*/Q_1^* is small, both results coincide quantitatively well.

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CPC solar collector, the compound parabolic solar concentrator, has become available and has given a powerful measures for high temperature uses such as industrial process and solar refrigeration for air-conditioning using dual effect absorption machine. CPC concentrators, developed by Dr. Winston, seems to have ideal characteristics, but application data has not yet been published. Present paper aims at analyzing practical characteristics for the actual design and disclosing peculiar performance figures comparing to conventional flat plate or single vacuum tube collector. The most effective factors are derived from computer simulation with design of experiment based on the equations to estimate solar heat collection, prepared by manufacturer. At the same time, strong influence is imposed on calculated heat collection by the separation of diffuse radiation and direct insolation, which is disclosed in the present paper. As the useful data for engineering purposes, monthly heat collection for typical districts in Japan, from cold climate to warm one, based on the HASP standard meteorological data are presented.

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A fundamental planning problem is considered for an air-to-air heat pump system which is composed of compressor, indoor and outdoor coils, fans, expansion valve, and so forth. First, physical relationships of the objective system are formulated mathematically by investigating heat cycle and mass flew relationships of the system. Then, a multiobjective optimal planning problem is formulated by assuming full and partial loads for space heating and air-cooling. In this optimization problem, the following two mutually incommensurable designing objectives are formulated as objective functions; i.e., (a) to minimize the total cost of equipment necessary to construct the heart pump system, and (b) to minimize the annual amount of energy consumption necessary to drive the system. As constraints in the optimization procedure, following several conditions are considered: 1) Heat cycle and mass flow relationships of the system corresponding to each load level for air-conditioning. 2) Constraints concerning permissible level of noise generated from indoor and outdoor fans. 3) Some additional constraints concerning upper and lower limits of refrigerant's temperatures at several cycle points so as to avoid the generation of frost at the evaporator and so forth. In the above-mentioned optimization problem, the following two cases are investigated concerning control methods of the system for partial loads. Case-A: In this case, an inverter is assumed to be installed to control the system for partial loads. In this system, the discharge amount of refrigerant is changed by the compressor's volume control, and air-flow capacity of both indoor and outdoor fans are also assumed to be controlled. Case-B: In this case, the system is operated for partial loads by adopting a simple on-off control device. By involving the system's optimal operational problem for partial loads, the optimal system's designing problem is formulated as a multiobjective nonlinear optimization problem. By adopting both the weighting method and the generalized reduced gradient algorithm, the set of Pareto optimal solutions is derived for two cases concerning system's control mentioned above. In other words, the design variables concerning system's construction are determined optimally together with optimal control policy for partial loads. Through a numerical study by using the optimal planning method proposed here, it is ascertained that two design objectives investigated here are obviously conflicting to each other, and the designer can determine design variables rationally by analyzing the trade-off relationship between design objectives mentioned above. It is also recognized the advantageous point of control Case-A compared with Case-B though the cost is still high to equip an inverter control device into the system. Through this numerical calculation, both validity and effectiveness are ascertained of the optimal planning method proposed here compared with the conventional trial-and-error designing method.

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The heat exhaustive or absorptive panel is one of the elements of a solar assisted air-source heat pump system. In case of cooling, heat is exhausted from the panel to the outdoor air by convection and radiation in the nighttime. The purpose of this study is to develop a higher-efficient heat exhaustive panel. The numerical calculations and experiments were carried out on the heat exhausted from several kinds of panels which were treated as paint, marble powder, fins and wet-cloth, and the effects of radiative, convective and evaporative heat transfer from each panel surface were investigated. The results were obtained as follows: 1) The heat per 1 USRt which comes from compressor to condenser grows in accordance with the decrease in evaporation temperature or the increase in condensation temperature. And the medium must be kept in a lower condensation temperature in order to make a higher effectiveness of the heat pump system. 2) The panel has a higher surface temperature, then a greater heat will be exhausted from the panel. On the contrary, the condensation temperature of medium will be become higher. So it is necessary to develop a panel which has a higher exhausted heat with a lower surface temperature of panel. 3) The results of nighttime simulation using Tokyo standard weather data show that the exhausted heat flux from the marble powder, the fins and the wet-cloth panel is 1.05, 1.19 and 2.22 times as large as that of the paint panel, respectively. 4) Evaporative cooling by using a wet-cloth is very effective to drop down the panel temperature. But the economic efficiency must be concerned. On the other hand, as the panels are reversed to absorb solar heat, the absorptive heat flux is to become greater in the order of the paint, the marble powder and the fins panel because the temperature of medium is lower than the outdoor air temperature, especially in cloudy days.

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In comparison with warm air heating system, radiant heating system results in a lower room temperature when the same conditions of thermal environment is considered for both systems generally. As a matter of fact, the thermal load of ventilation for the radiant heating system is less than that of the warm air heating system. However, in which of the above-mentioned heating system the heat loss through the exterior wall exceeds, is a matter of question and actually depends upon the thermal environmental conditions of the space. In this paper, effort has been given to clarify the cases in which radiant heating system brings about less heat loss (through the exterior walls) than warm air heating system. In the previous paper, the authors could achieve some empirical index (i.e., so far called critical convective heat transfer coeficient) c.c.h.t.c. for a two-parallel-symmetric-infinite-planes space by which the energy savings characteristics of the heating system may be evaluated for that space. Nevertheless, in this paper, a theoretical formula is presented for estimation of the critical convective heat transfer coefficient which can be applied, concretely, for the practical spaces. The conception is based on the fact that, when the thermal environmental conditions are considered constant and the change of temperature in one of the surfaces (underchange-surface) of space (i.e., increase in radiant heat exchange) happens without causing any change in the heat loss of another exterior surface (object-surface), the convective heat transfer coefficient of that object-surface takes a particular value and in this paper has been called critical value. Also, the real value of convective heat transfer coefficient of a surface if becomes more than its critical value, the heat loss through that surface in the radiant heating system will be less than that of in the warm air heating system. Gebhart absorption-factors have been applied to develope a dimensionless theoretical formula for critical convective heat transfer coefficient. Moreover, the main parameters which affect the critical convective heat transfer coefficient, have been clarified as Gebhart absorption-factors (i.e., absorption-factors for wall to wall as well as man to wall), heat transfer coefficient in the vicinity of the man in the space and the emissivities of both man and the internal surfaces of the exterior walls. On the other hand, it has been shown that the thermal conductances of the walls, ambient temperature, internal heat production of human body and thermal resistance of clothing have almost no effect on the c.c.h.t.c. Besides, comparison of c.c.h.t.c. calculated by the rigorous method (i.e., based on energy balance equations) and by the approximate formula for various cases has shown the reliability of the approximate formula. Finally, the fundamental characteristics of c.c.h.t.c. have been discussed.

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Numerical experiments of heat loss through the exterior walls have been performed for two simplified space models, while the indoor thermal environmental conditions have been assumed equal for both space models. All the conditions in both space models have been assumed equal other than in one of the surfaces of one of the models temperature supposed to be different from the similar one of the other model. Based on this assumption (i.e., occurrence of temperature difference in some surface), one of the space models is supposed to be warmed up by a radiant heating system and the other by a warm air heating system. In the 128 experiments, in order to obtain the statistical results for heat loss-when the environmental parameters are assumed to change in the practical ranges-the table of orthogonal arrays L_<128>(2^<127>) has been applied. The purpose of this study may be summerized as follows: 1) In the previous paper, authors have proposed an index, so far called c.c.h.t.c. (critical convective heat transfer coefficient), which relates to the heat loss through the exterior walls. Here, the statistical magnitude of error between the results of the rigorous method and approximate formula for c.c.h.t.c. as well as the effects of main factors upon the error have been depicted. 2) The statistical magnitude of the heat loss rate of two space models and the influences of main factors have been shown. In regard to 1), the Gebhart absorption-factors have been applied in the approximate formula, but at meantime, the similar formula has been set in which the absorption-factors are replaced by shape factors. However, it has been found that in the latter formula the error considerably arises. In relation with 2), as heat loss rate changes due to the conditions, application of a calculation method by which the effects of radiant heat on the heat loss can be correctly evaluated is inevitable. Generally, application of simultaneous linear equations in this kind of calculation method for heat loss is necessary, however, in this paper a method called MRT method is proposed in which mean radiant temperatures relative to the walls and to the global object (i.e., represents the human body), are applied in the iterative computation. The iterative computation used in MRT method has shown that less than two times of iteration is necessary to give the correct results. It is possible to simplify the MRT method by simplifying the method used in obtaining the mean radiant temperatures. In this regard, some more simplified methods have been employed, and have also been statistically compared basd on the Experimental Design method.

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We have studied the method of numerical analysis of room air distribution mainly with rectangular geometrical boundary configuration. It is necessary, however, for the numerical method to be used in practical situations that the method is also well-established in the case of the room with non-rectangular configuration and/or various obstacles inside of itself, and so on. This paper discusses the numerical prediction technique for the air flow distribution of the room with many different boundary geometry. The finite element method is used in those cases of complex calculation domain such as non-rectangular one, and is applied to analyse viscous fluid flow problems. It requires larger storage capacity of electronic computer and more CPU time than those of the finite difference method. We, therefore, consider that it is worth-while for the time being to adopt the finite difference method to analyse the problem with the complex calculation domain. The flow is assumed to be laminar except one case (D-2), two-dimensional and isothermal. Stream function and vorticity method (ψ-ω method) is adopted. The solution procedure is the same as one we so far used except the technique for treating the complex configuration. The configurations of rooms are divided into two kinds. One has non-rectangular boundary (Type A, D) and the other has an obstacle (Type B, C). The details of those 4 types are as follows: Type A: The ceiling of the room is inclined to the horizontal, and other 3 surfaces are horizontal or vertical. The inlet-opening is provided at the upper part of left vertical wall and the exhaustopening is at the lowest part of left or right wall. Type B: In this case, there is an isolated island in the room. The inlet provided at the right edge of ceiling and exhaust is at the lowest of left vertical wall. We compute the flow fields at the various positions of the island. Type C: In this room, there is a fence attached to the floor. Inlet and exhaust opening are at the same positions as those of Type B. We change the position on the floor and height of the fence. Type D: This type is much more complex than Type A. In one case of this type, we try to compute the turbulent flow condition by turbulence energy-length scale model (k-l model). The inlet is at lower left wall and the exhaust is open to the upper part. In the case of Type B, ψ-ω method has the main problem of deciding the value of stream function (ψ_s) on the isolated island periphery. We use the condition that the line integration of total derivative of pressure (dp) taken along an arbitrary closed curve enclosing the island should be zero, or[numerical formula]. In order to obtain the converged velue of ψ_s under that condition, the half-interval method is adopted to correct initially guessed value of ψ_s. The another problem of ψ-ω method is to decide the vorticity at the inclined wall or at the intersection of two walls. In this report, we describe in detail the solution of those various problems. We compare the calculated results to experimental ones in respect to flow pattern. As a result, it becomes clear that the method we adopted is satisfactory.

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In the preceding report, a method of calculating various boundary configulations using stream function and vorticity method (ψ-ω method) for the finite difference procedure was presented, and the calculated flow patterns showed fairly good agreement with experimental ones.In this report, two simplified methods of treating obstacles in rooms are introduced. One is diffusion coefficient method (DCM) and the other is source term method (STM). DCM is more useful than STM since DCM can treat conjugate heat transfer problems in the same manner. We treat only rectangular room configulations, but these methods may be applied easily to non-rectangular rooms as well as non-rectangular obstacles. The applied calculation scheme in this study is primitive pressure-velocity code (P-V method). We calculate three kinds of geometrical conditions. Type I: There is an isolated island in rectangular rooms. Type II: There is a fence attached to the floor in rectangular rooms. Type III: There is one outlet at each vertical wall. The calculation method is examined in detail and its results are compared with visualized flow patterns together with the results of ψ-ω method. Main outcomes of the current study are as follows. Calculated results are proved to be reasonable qualitatively, but a little discrepancy is seen in the values between ψ-ω method and P-V method. Only a more detailed experiment would be able to judge the results more strictly. In the calculation procedure, P-V method is simpler than the ψ-ω method, but the latter is more stable and converges faster than the former. The simpleness of P-V method will be underlined much more in the calculations of three dimensional problems.

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