In the case of a pressurized under floor air-conditioning system with the twisted groove type floor outlet during the space cooling poeration, the temperature gradient varies from the occupied zone to the upper part. The measured result of the discharge air velocity in the inflection point about 0.25m/s. The method to calculate the height of air flow from floor outlet is presented by assuming air flow pattern with the momentums of more than two different air fluxes and adding the momentum of them. Caluculated results on the height of the air fluxes agreed well with a lot of measured results. This method could make it possible to determine the discharge air velocity from the floor outlet against the temperature difference between the discharge air and the room air following the variable heat load in the optimum control in operating the system. Moreover, the air discharge angle and velocity could easily be determined from the required height of the occupied zone to be air conditioned.

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Transient free convection from a vertical hygroscopic plate with the desorption of moisture during heating and the adsorption during unheating was studied experimentally and numerically. The plate is made of thin glass epoxy board, on which stainless steel foils and hygroscopic papers are stuck together. Measured weight change of the moisture of the plate and its temperature change agree well with the numerical ones.

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In the preceding report, we investigated by means of one-half scaled model experiments a ceiling-cooling-type cooling system that uses ceiling-adhering air jets, and reported on the blown air-currents' adhesion to the ceiling and on the indoor thermal environment of a cooled living room in which this cooling method is used. In this report, we conduct numerical simulation coupling radiant and convective fields for a living room corresponding to the model experiments, and structurally analyze the indoor thermal environment realized by this cooling method. Additionally, we analyze through numerical simulation the indoor environment by altering the air supply and exhaust methods, and investigate inlets and outlets' influence on indoor thermal environment formation. We thus learned that with this cooling system, the position of exhaust inlets has a major influence on indoor thermal environment formation and that exhaust inlets positioned so as to directly exhaust ascending thermal currents from heat sources with a large thermal load are effective. The fact that the temperature of the sucked-in air is higher than that of the room's dwelling space means that if the air-conditioning thermal load is the same, the temperature of the blown air can be increased by the amount of this temperature difference and the condensation risk due to the blown air is correspondingly reduced. The method of cooling the ceiling surface with blown air currents effectively absorbs the window-surface load by means of radiation and transfers this heat within the room by convective heat transfer. But from the stand-point that this cooling system effectively exhausts the heat before the window-surface load diffuses within the room, this method also has the counter effect of promoting thermal diffusion to spaces within the room by radiant heat transfer.

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Recently, district heating and cooling plants have been installed increasingly with the redevelopment of urban areas. In order to assist operators to operate the plants rationally from economic and energy saving viewpoints, it is required to develop a computer-aided system for real-time operation of the plants. Fundamental functions necessary for the system are to predict energy demands precisely and to conduct unit startup/shutdown scheduling (unit commitment) rationally. Many effective methods of predicting energy demands have been proposed previously. However, no effective methods have been proposed for unit commitment. In addition, the relationship between energy demand prediction and unit commitment has not been investigated. The objectives of the present research are to develop a computer-aided system for real-time optimal operation of district heating and cooling plants and to in vestigate the relationship between energy demand prediction and unit commitment. An ARIMA model has been used in predicting energy demands for a period considered from the current time. In addition, a method of determining the value of a parameter for considering the uncertainty in energy demands has been presented. On the other hand, an optimal operational planning method in consideration of unit startup/shutdown cost has been used for unit commitment. By this method, the unit on/off status and load allocation for the period are determined to minimize the sum of energy supply and unit startup/shutdown cost, and to satisfy energy demands predicted. To evaluate the validity and effectiveness of the system developed, numerical calculations have been carried out using energy demands predicted and measured through a year for an existing district heating and cooling plant. The following are the main results obtained: 1) The characteristics of the errors between energy demands measured and predicted, which depend on season, time, and time-difference between measurement and prediction, have been clarified. From these characteristics, the uncertainty in energy demands which is taken into account in unit commitment has been estimated. 2) As representatives of the relationship between energy demand prediction and unit commitment, the relationships between the error in cold water demand prediction and the rate of increase in operational cost or the rate of deficit in cold water supply have been clarified. In addition, the trade-off relationship between the increase (rate) in operational cost and the deficit (rate) in cold water supply has been clarified with the uncertainty in cold water demand as a parameter. 3) It has been turned out that to reduce the annual operational cost, it is necessary to conduct unit commitment appropriately not only in summer but also in mid-season, and to use an appropriate value of the parameter for the uncertainty in cold water demand. 4) It has been shown that the unit commitment based on energy demands predicted can determine the unit startup/shutdown strategy appropriate even for energy demands measured.

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In this paper, the authors investigated direct heat exchange between snow and air. Hot air is cooled directly on the surface of snow through a vertical hole dug into a snow pile. Temperature changes of cooled air and shape changes of snow were observed by means of an experiment apparatus with the size of actual equipment. By reference to the actual conditions of an air-cooling system, initial snow height of snow pile, inlet air temperature and air flow rate were changed as parameters. The outlet air temperatures and snow shapes were measured. The following results were obtained. When the amount of remaining snow is decreased, the diameter of snow hole increases lineally and the snow height decreases lineally. The initial snow height is higher, air flow rate is larger and inlet air temperature is lower, the outlet air temperature becomes lower. And the authors derived an experimental equation to describe the relationships between the outlet air temperature and every parameter.

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This paper is continued from the last one in which the freezing characteristics of the spherical ice storage capsule were investigated. Melting processes of the ice inside the spherical capsule cut half were visualized and melting rates of the ice inside the spherical capsule were measured by using the same experimental apparatus used in the last paper. Experimental results were investigated and the coefficient of heat transmission K_w for the melted water based on the ice surface was defined under the assumption of the ice melting spherically. K_w obtained from melting rates measured was related to the melting conditions. A melting model to calculate K_w was proposed and its calculating method was shown. K_w calculated from this method was compared with that measured. Comparatively good agreements were obtained between measured and calculated results. It is possible to estimate the change of heat transfer characteristics of the spherical ice storage capsule caused by the melting conditions easily by using this calculation method.

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This study describes analyses and experiments on fundamental thermal characteristics of vertical heat exchanger's annual energy cycle in order to specify the availability of underground thermal energy utilization for heating and cooling. First of all, it was shown that a single bore-field was more effectively utilized as a heat source and a multiple bore-field as a storage medium. This was determined by analyses on standard thermal recovery ratio. A multiple bore-field has an optimum bore-spacing which maximizes the amount of heat extraction. Next, we evaluated the performance of a ground source heat pump system by experiments and analyses. We found that underground thermal energy could be utilized over a long period of time. We also compared the ground source heat pump and an air source heat pump for heating of a super insulated house. The ground source heat pump is a superior heating system for energy conservation and environmental protection.

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In air conditioning/ventilation systems which use a ceiling plenum as the route of airflow for air conditioning or ventilation, a beam inside the ceiling plenum can be regarded as the largest resisting substance for the airflow. Various airflow resisting substances inside a ceiling plenum can increase the initial and running cost. Moreover, the uneven pressure distribution generated can cause to make the supply and return airflow rate not uniform and deteriorate the indoor air quality and thermal environment. In order to assist the pressure resistance designing of a ceiling plenum, this report verified the effectiveness of equations by comparing the calculated and experimental values for the local loss of air flowing over a beam inside the ceiling plenum. The analysis was applied to the resistance loss of the beam with the lowest edge of right angle and with that of 1/5 gradient angle. As a result of the analysis, the following were found. (1) For the beam with lowest edge of right angle (The height of the beam is represented by B in Figure-1); Resistance coefficient can be expressed approximately by the equation for the one-step expansion of air flowing over the beam. ζ_1=(1/K-1)^2 Re in this case is 9.6×10^3<Re<7.9×10^4 (2) For the beam with lowest edge of 1/5 gradient angle (The height of the beam is represented by B' in Figure -2); 1) Resistance coefficient for one-step and two-step expansion can be expressed by two equations below respectively. [figure] Fig. -1 Conceptual drawing of airflow at one-stage expansion (in case of right angle) ζ_1'=(1/K'-1)^2 ζ 2'=(1/K'-1/(1-m'))^2+(1/(1-m')-1)^2 2) In a range of the height ratio at 0.68<m<0.85, it can be expressed approximately by the equation for one-step expansion. 3) In a range of the height ratio at 0.85≦m≦0.94, the experimental value stays between the values of the expressions for one-step and two-step expansion. Re in this case is 1.6×10^4<Re<6×10^4 The symbols used and the conceptual drawing of air flowing over the beam are shown below. Legend of main symbols ζ_1: Fluid resistance coefficient of one-step expan sion (in case of right angle) ζ_1: Fluid resistance coefficient of one-step expan sion (in case of 1/5 gradient angle) [figure] Fig. -2 Conceptual drawing of airflow at one-stage and two-stage expansion (in case of 1/5 gradient angle) ζ_2: Fluid resistance coefficient of two-step ex-pansion (in case of 1/5 gradient angle) V_1: Mean velocity inside ceiling plenum V_c: Maximum velocity of air flowing over beam (in case of right angle) V_c': Maximum velocity of air flowing over beam (in case of 1/5 gradient angle) H: Height of ceiling plenum B: Height of beam (in case of right angle) B': Height of beam (in case of 1/5 gradient angle) K: Velocity ratio (V_1/V_c) (in case of right angle) K': Velocity ratio (V_1/V_c') (in case of 1/5 gradi ent angle) m: Height ratio (B/H) (in case of right angle) m': Height ratio (B'/H) (in case of 1/5 gradient angle) Re: Reynolds number of air flowing under beam

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This paper presents a new method for deciding the supply-air temperature setpoint of VAV (Variable-Air-Volume) system of air-conditioning by vote. Conventional VAV control resets the supply-air temperature setpoint by a set of constant variation-ratios. These systems, however, suffer from significant problems. (1) How to decide the initial value of the supply-air temperature setpoint when VAV system starts running. (2) How to set appropriate variation-ratio of the suply-air setpoint. (3) How to respond demands when upper supply-air temperature and lower supply-air temperature are simultaneously offered. (4) How to link supply-air temperature control with supply-air volume control. The new method solves such problems. The vote method employs control logic that chooses to either minimize the system deviation of room temperature control or minimize supply-air volume according to its control objective. The vote method may also link supply-air temperature control with other control strategies, such as minimizing chilled/hot water volume control logic in the neutral zone of cooling/heating action. This paper also demonstrates effective graphical display of the vote method. The graphical display enables simple expression of such items as the decision's result and its influences, the current status and the importance of each VAV end unit, and selection ranges of supply-air temperature setpoint. These items are not easily expressed by words or numbers. Comparative experiments using a real system in a commercial building prove the controllability, stability and practicability of the vote method, and shows its advantages over conventional methods.

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