We developed a packaged air-conditioner that improves annual efficiency. The developed system has a highly efficient wide-range compressor that improves the heat pump efficiency in the low air-conditioning loads, a heat exchanger that is optimized for both a vapor compression refrigeration system and refrigerant natural circulation system, an adaptive controller that suppresses unnecessary start-and-stop compressor operation and a refrigerant natural circulation system that enables highly efficient operation under a low ambient temperature condition. For this developed packaged air-conditioner, we tested and proved that <br>(i) the annual efficiency of the system was 1.51 times compared with that of the conventional one in a thermostatic chamber, <br>(ii) the efficiency for actual use was 1.58 times for the collaboratory of Hokkaido University in Sapporo and 1.67 times for the CAE room of Hitachi Appliances, Inc. in Shizuoka at ambient temperature in 2012, and <br>(iii) by revising the data the efficiency for actual use was 1.55 times for a common office in Tokyo at normal ambient temperature.

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Since a throttling loss of CO2 refrigeration cycle is relatively large, various types of expanders have been investigated to recover the throttling loss. However, the capacity of the expander developed so far is so large that it is unadaptable to a small cycle such as a vending machine. In this paper, a small radial piston type expander is designed to be operated with flow rate less than 5 kg/h and its performance is examined. In addition, leakage and friction at a piston seal which has large influence on the performance are also discussed. The developed expander can be operated with a small flow rate less than 5 kg/h and the total efficiency attains to 0.45 – 0.5. It is found that to reduce the leakage at the piston seal is more important than reducing the friction of the seal to get good performance.

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The study analyzed electricity demand characteristics in a university campus based on a year-through measurement data, and examined a method to predict electricity demand in summer season using a correlation between the electricity demand and outdoor air enthalpy. It was shown that the electricity demand could be divided into two parts, which are base loads and variable loads using the correlation. The variable load was corresponding to the air conditioning load. It was found that the electricity demand was influenced by particular events of the university such as summer vacation and submission of graduate theses. The regression analysis showed, however, a good agreement between the outdoor enthalpy and the summer electricity demand in whole campus because individual characteristics were moderated by a combination of different demand feasures.

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We have developed an innovative spherical activated carbon (SAC) for adsorption heat pump application. It was observed that the SAC had a large effective adsorption compared with conventional activated carbons against ethanol. To predict the system performance with SAC as adsorbent of adsorption heat pumps, a dynamic simulation model based on the heat exchanger characteristics estimation was performed. The simulation results revealed that the adsorption cooling system with the SAC achieved a larger cooling capacity compared with the conventional activated carbon powder-ethanol pair, and the COP at the optimum cycle time was improved by 12% by the SAC-ethanol pair.

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This paper proposes a method to estimate the stray capacitance between compressor motor windings and stator in operation, and the permittivity of refrigerant and lubricant oil mixture in this area. By applying this method, the complex experiment equipments and sensors are unnecessary. The estimation about the stray capacitance between the motor windings and stator in operation becomes possible according to the equivalent circuit of the inverter air conditioner by analyzing the high frequency leakage current of ground line. Further, the permittivity of refrigerant and lubricant oil mixture can be calculated by comparing the stray capacitance of equivalent circuit in operation with the stray capacitance of the compressor without refrigerant and lubricant oil. It is meaningful to discuss and solve the problem of EMI (electromagnetic interference) noise.

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In order to clarify effects of high electric charge on freezing of supercooled sodium acetate solution, 50 wt% solution was prepared as test specimen and two kinds of experiments were carried out using an electron-gun. In the first case, the electrode was dipped into the test specimen called the contact type. In the other case, the electrode was placed above the free surface of the test specimen called the non-contact type. Two types of test tubes were used as a container for the test specimen, namely, polypropylene and glass, and the degree of supercooling was varied from 10 to 30K. Voltage applied was varied from 45kV to 84kV. It was found that the supercooled sodium acetate solution solidified in a case of using polypropylene test tube whereas no solidification occurred in a case of glass test tube. The phenomenon was observed for both kinds of experiments, i.e. contact and non-contact types. The mechanism was discussed and suggested that ions are collected on the free surface of sodium acetate solution in a case of polypropylene test tube and discharged with sparks. The reason for the stable supercooling state was suggested that sodium acetate solution is ionized and sodium ion forms hydration. It causes to reduce the number of free water molecules to form hydration with sodium acetate. It is believed that solidification nuclei are generated by separating the ion hydration in aqueous solution, and it can be done by applying electric discharge with sparks. Therefore, with respect to coagulation control of sodium acetate aqueous solution in the low degree of supercooling, the high voltage applied is a very effective technique.

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For the local flow boiling heat transfer coefficient in small diameter circular tubes, the authors had previously proposed a prediction correlation, in which the liquid film conductive evaporation heat transfer peculiar to small diameter tubes was taken into account in addition to forced convective evaporation and nucleate boiling. The liquid film conductive evaporation is the evaporation of the thin liquid film around vapor plugs in slug flow due to conduction through the film and shows considerably good heat transfer. However, this correlation was found not to be accurately applicable to high vapor pressure refrigerants and the flow at low flow rate in horizontal small tubes. Based on new experimental data, the correlation was partly modified to overcome these shortcomings. Compared with existing correlations, the improved correlation has higher prediction performance for 410A data by the authors and for a number of experimental data by the other researchers including R 32, R 1234yf, H2O and CO2. The good prediction performance of the present correlation is shown in the following figure.<br>

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Vapor pressure and saturated liquid density for HFE-7100 (C₄F₉OCH₃, methoxy-nonafluorobutane) were measured in the temperature range from 300 K to 400 K at intervals of 10 K by the extraction method. Experimental uncertainties are 0.028 K for temperature, 0.4 kPa for pressure and 0.7 kg‧m^-3 for density. On a basis of the present data, correlations of vapor pressure and saturated liquid density were formulated. The standard deviations from correlations were 0.6 kPa for vapor pressure and 0.4 kg‧m^-3 for saturated liquid density.

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The influence of electric vehicles (EVs) on photochemical pollution and air temperature under a mid-summer condition in 2010 was investigated by using a numerical model. The objective area was about 100 km square region centered on the Osaka plain. All of the current passenger cars and the mini-cars were assumed to be changed from internal combustion ve hicles to EVs. Based on existing emission inventories, the changes in the emission amount of pollutants and sensible heat were estimated by fully top-down approaches. Additional power demand by EVs was assumed to be supplied from the lo cal thermal power plants within the objective area. The emission amount from the power plants were estimated for the cases with/without nuclear power plants (NPPs). The impacts of EVs on the ozone pollution level and on the thermal environment were evaluated by accumulated values over a certain threshold. By the shift to EV, each emission amount of NOx, NMVOC and CO₂ decreases, and the pollution level becomes lower. The decrease amount is large in the northern and eastern inland areas. Such a tendency relates to the sea breeze path and the photochemical regime in the study area. Mitigation effect on the hot environment near the ground surface is very small. Substitution of NPPs by thermal power plants increases regional emission amount of NOx largely and increases pollu tion level slightly. By the shift to EV, emission amount of CO₂ increases; however, pollution level becomes lower than the current level.

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This study quantifies the proportion of anthropogenic heat and convective heat from a building by using a numerical simulation system. The numerical simulation system consists of external heat balance simulation, building heat load simulation, air-conditioning energy simulation and anthropogenic heat simulation. As the results of the numerical simulation for a 12 story-building with an absorption refrigerator and cooling tower, it is shown that latent heat release occupies large part of the anthropogenic heat and the amount of sensible heat released by convection occupies approximately 80% of the atmospheric heat load by sensible heat. By changing the air-conditioning system to the system with an air-cooled heat pump chiller, the atmospheric heat load by sensible heat increases to 2.1 times and the sensible heat from the air-conditioning system becomes two times larger than the sensible heat by convection. .

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The cooling tower, which discharges most of exhaust heat as latent heat, decreases sensible heat. So it is one of heat island measures. In this study, heat island mitigation effect by cooling tower is analyzed based on observation result of the temperature in the cooling tower. We indicate latent heat ratio of cooling tower as heat island mitigation effect. When the cooling tower operates forcibly and air-conditioning load is small, latent heat ratio is large. As a result, heat island mitigation effect becomes large.

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In order to investigate design and operating method of the hybrid ground source heat pump (HGSHP) system combined cooling tower, the authors developed a computer aided simulation tool for the system. Performance of the HGSHP system combined cooling tower, which has been installed in a new office building in Kitakyushu City, is predicted with the simulation tool. The result shows the HGSHP system can operate with high cooling seasonal performance factor (SPF) of 5.4. In addition, the authors investigated connection sequence and operation method of the HGSHP system. The result shows that the HGSHP system provides the highest cooling SPF when the cooling tower is connected in series with the ground heat exchangers (GHEXs) and the water as heat carrier fluid is circulated to the cooling tower ahead of the GHEXs. The system performance is additionally improved by using the simple cooling tower’s activation control by the inlet temperature of heat pump unit.

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The subject of this study is to establish design and operation method of the ground source heat pump system affected by ground water flow. In order to investigate relation between the ground temperature response around ground heat exchanger (GHEX) and ground water velocity, multilayered ground simulation model is developed. It was shown that heat medium temperature is not kept in steady state in thermal response test when the groundwater flow in all geological layer is not generated. It is suggested that the thickness of geological layer with ground water flow and the ground water velocity can be estimated by analyzing the apparent effective thermal conductivity, which is obtained by the thermal resp_-1 onse _-1test . Also, if the apparent effective thermal conductivity at elapsed time of 50 h is more than 4.5 W・m ・K ,the ratio of thickness of geological layer that have ground water flow with the velocity of 300 m・y^-1 is more than 25 % in all geological layer.

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Horizontal ground heat exchanger in ground source heat pump systems is susceptible to ground surface variations thus affecting its thermal performance. However, this configuration is desirable due to low installation costs as it mainly involved burying pipes in shallow trenches. The optimization of horizontal ground heat exchanger was investigated by simulating a cross section of the ground containing a single unit of slinky-loops. The analysis shows that although trench depth increased by one third in vertical orientation, there was no significant improvement on thermal performance compared to horizontal orientation. Unless land area is limited then it is suggested that loops are installed in vertical orientation. When the material used as ground heat exchanger was copper pipe, heat exchange rate improved by 20% compared to conventional HDPE pipe. As expected, ground thermal resistance has a limiting effect on thermal performance although the pipe was changed to a material with thermal conductivity of over 800 times higher. The effect of distributing the flow into a group of loops in parallel was also examined. Thermal performance increases as more heat transfer area was provided in parallel loops. The spacing between adjacent loops was studied to elucidate heat interference in parallel loops operation.

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The Solution Transportation Absorption chiller (STA) can transport the thermal energy at ambient temperature due to conversion of the thermal energy into concentration difference of the refrigerant and the solutions. This study, on the assumption that a large scale STA as the heat transportation distance is 10000 m and the cooling output is 3517 kW, simulates the dynamic behaviors decreased to 20 % of the cooling output and then analyze the effect of control ability and the refrigerant receiver on the transport pipe. The behaviors of the cooling output are almost the same tracking as those of both 1 m and 10000 m pipes. Lager volume of the pipe will results in more use of refrigerant in the refrigerant receiver because the increased amount of refrigerant mass in the strong solution is used by refrigerant in the refrigerant receiver. Therefore, STA can be controlled for the cooling output by the conventional control method. On the other hand, the receivers volume or filling amount of the refrigerant are required to be designed according to the pipe volume.

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Adsorption refrigerators are able to generate cold water using low temperature waste heat, and are effective in reducing fossil fuel consumption and peak electric loads. In order to facilitate introduction of adsorption refrigerators, miniaturization of the machine and further lowering operation temperature are essential. In the present study, we experimentally investigated two-stage adsorption cycle with three Beds, which conventionally needs four Beds, using FAM-Z01 and Z05. The results showed that the cycle generated cooling ability of around 0.6 kW using hot water of 55 degrees Celsius. Therefore, we verified that miniaturization of the machine and lowering operation temperature can be achieved.

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For energy saving and CO2 reduction during idling stops, this study focused on the exhaust gas and exhaust heat of running refrigeration/freezing vehicles. We had proposed a novel system which stores the waste heat by a chemical heat pump and recycles it as coldness for air conditioning during an idling stop. In this study, we performed experiments of the system for enhancing the cold heat production. First, an equilibrium of ethylene glycol water solution vapor pressure and an equilibrium of CaSO41/2H2O/CaSO4 reaction were examined by thermogravimetry. Next, the reaction and cold-heat production characteristics of the chemical heat pump unit were examined for various densities of ethylene glycol water solution. As a result, it was found that the cold-heat of lower than 258 K was recovered for more than 12 hours at over 110 MJ/m ³-CaSO4 in the evaporator with 50 % ethylene glycol water solution.

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This paper presents theoretical and experimental investigation of an adsorption cooling system to predict the cycle performance of one bed adsorber based on the equilibrium condition. For this particular study, activated carbon-ethanol pair was chosen as the adsorbent-refrigerant pair because of a high adsorption capacity of activated carbons against ethanol. The experiment was conducted on five different pre-cooling and pre-heating settings. The experiments carried out were divided to two sections. First, the preliminary experiments were carried out on two extreme conditions. For the first extreme condition, the adsorption and desorption process were carried out without pre-cooling and pre-heating. Whilst for the second extreme condition, the adsorbent was pre-cooled and pre-heated until the adsorbent reach adsorption and desorption temperature. Then the experiments were carried out with three different time of pre-cooling/pre-heating time which was selected based on the preliminary experiments. The heat balance were analyzed critically and the optimum cycle time, namely the pre-cooling and pre-heating time for each adsorption and desorption process is discussed by identifying the suitable adsorbent pressure and temperature of the system.

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An ammine complex formation reaction with strontium chloride is expected as a reaction of the chemical heat storage system which has high heat release rate and high heat capacity. In this study, the heat release and storage cycles were demonstrated with the packed bed type reactor at the condition of heat source temperature 90 °C and evaporator temperature 0 °C, and the heat release rate was 1.1～1.3 kW per reactant volume. Besides, mass transfer rate, chemical reaction rate, and heat transfer rate were evaluated respectively, and the heat transfer was identified to be the rate-determining step in this reaction system. Then, the heat resistance was quantified by experiments as well as the simulation modeling the thin layer reactant packed bed. As a resu_-3 lt, ₂ the effective thermal conductivity of SrCl₂ packed bed was 0.18 W/m/K and thermal contact resistance was 1/h=2.3×10 m ･K/W.

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For development of a highly efficient desiccant air conditioning system, we have proposed to apply microwave heating as regeneration energy source of adsorbents. In this study, we focused on heating and water desorption characteristics for some silica gels under microwave irradiation. Microwave heating was performed for three particulate silica gels (RD, B, ID type). Moreover, water desorption experiments were also conducted for silica gel RD with various initial amounts of adsorbed water, microwave powers, and humid nitrogen flow velocities. As a result, a big difference in achieving temperature with microwave irradiation was observed between silica gels even under dry condition, meaning that each silica gel had a different microwave absorptivity. Among them, silica gel RD indicated the best microwave absorptivity and achieved the highest bed temperature, initial desorption rate, and desorption ratio by microwave irradiation. For silica gel RD, an amount of desorbed water in an equilibrium state was observed to be approximately proportional to initial amount of adsorbed water in every microwave power. It was also found that water desorption was promoted as increasing microwave power.

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