Zeolite-water heat-pump system has been developed in these 25 years. Recently, an instant beer-cooling system has appeared by using the zeolite heat pump system as a commercial product. It takes so long time for the development since the first proposal. The most serious problem through the development has been of the ability of absorbents. Themaximum heat exchange capacity to date exceeds 1MJ•kg^-1 for Mg89-A, which is comparable to the energy storage capacity of modern alkaline-ion batteries in weight-bases. But it needs high temperature heat sources more than 200°C for the activation. Absorbents useful at lower temperatures are thus desirable for effective use of various kinds of lower temperature heat sources Various nano-porous materials as well as zeolites now under investigation as candidates of heat-pump absorbents, such as silica-gels, allophane, imogolite, hydrotalcite, etc.

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Micro gas turbines are expected as engines for the distributed co-generation systems, performing power generation and heat recovery. Waste heat from micro gas turbines are discharged in the form of exhaust gas, and it is simple that exhaust gas is directly supplied to an absorption refrigerator. In this paper, we evaluated various single-double effect absorption cycles for exhaust gas driven absorption refrigerators, and clarified that the difference of performance among these cycles are little. We adopted one of these cycles for the prototype machine, and experimented with it to get the partial load characteristics and the effect of cooling water temperature on the performance. Based on the experimental data, we developed as imulation model of the static characteristics, and studied the direction of improvement.

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Waste heat from co-generation systems are usually recovered by hot water or steam, those are used to drive absorption refrigerators at cooling time, and those are used for heating via heat exchangers at heating time. However waste heat from micro gas turbines are discharged in the form of exhaust gas, it is simple that exhaust gas is directly supplied to absorption chiller-heaters. In the first report we studied cooling cycle, and this second paper, we evaluated various absorption heating cycles for exhaust gas driven absorption chiller-heaters, and adopted one of these cycles for the prototype machine. Also, we experimented with the prototype for wide range condition and got the heating characteristics. Based on the experimental data, we developed a simulation model of the static characteristics, and then studied how to increase the output by limited exhaust gas.

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In the present study, the local heat transfer and pressure drop characteristics are investigated experimentally for the flow boiling of refrigerant HFC134a in a multi-port extruded tube of 1.06mm in hydraulic diameter. The test tube is 865mm in total length made of aluminum. The pressure drop was measured at an interval of 191mm, the local heat transfer coefficient was measured in every subsection of 75mm in effective heating length. The measured pressure drop was compared with a few correlations. Those data agree with the correlation of Koyama et al., proposed for condensation process, and of Friedel. The local heat transfer coefficients were also compared with correlation of Yu et al. It is pointed out that multiplier of the convection term in a rectangular channel is different from that of circular tube.

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The effects of enhanced heat transfer tube with ability to control the heat transfer disturbance by mechanical tube expanding were experimentally investigated on the performance characteristics of air-cooled cross-fin-tube-type heat exchanger for air conditioner. Three kinds of the enhanced heat transfer tube were developed and used in the experiment. The enhanced heat transfer tube was a kind of spirally grooved tube and composed with the fins smaller than those of the conventional spirally grooved tube excepting four fins located in orthogonal position on the tube circumference. The optimum groove number to enhance the performance of heat exchanger was also shown.

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This study is combined convection heat transfer with melting of phase change material (PCM) in horizontal cylindrical tubes immersed in water. In this study, the heat transfer that combined the natural convection of water around the tubes with the melting of PCM inside the tubes was studied numerically and experimentally. Two horizontal cylindrical tubes were arranged in series. Numerical results were compared with experimental results. Results are presented as melting front contours of PCM, wall temperature distributions on the tubes, f low patterns and melting fraction.

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Average heat transfer coefficient during R-410A condensation in three kinds of spirally grooved tubes were theoretically predicted using the calculating tool developed by a R&D project of Japan Society of Refrigeration and Air Conditioning Engineers carried out during 1999 to 2001. The results were compared with their experimental data obtained by the authors. The predicted data almost agreed with the experimental data at operating refrigerant mass velocity of actual air conditioner. The predicted data in the lower refrigerant mass velocity range were higher than the experimental data, because the single phase flow regions existing at both inlet and outlet of actual condenser were not considered in theoretical predicting. On the other hand, since the stratified flow model was applied to the whole range of condenser, the predicted data in the higher refrigerant mass velocity range were lower than the experimental data.

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Energy consumption in almost all sectors is constantly increasing. Air conditioner is one of energy-intensive equipments and it is important to evaluate energy consumption with reasonable accuracy. For evaluation of energy conservation of air conditioners, it is necessary to take into account the variations of outdoor temperature, the heating/cooling load throughout a year and all the operating conditions. But according to the current standard, only a few found values and other estimated values are used to calculate annual energy consumption of air conditioner. It is needed to assess the legitimacy of current standard. Seasonal performance of air conditioners was tested, and an appropriate way of evaluation of energy conservation was investigated.

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For the sake of capturing the basic data in concern with the designing of vacuum evaporation apparatus, characteristics of the self-evaporation behavior of sprinkled water near the triple point has been investigated experimentally. The relationship between the amount of the vaporized water and the pressure in the vessel was elucidated quantitatively on the condition that over-heated water was sprinkled from water supplying nozzles of diameter of 4 mm into the center of the steam area in the heat insulation glass evaporation vessel having diameter of 200 mm and height of 1100 mm. Even under the mild water sprinkling conditions such as no small particle formation, small Reynolds number, and small Weber number, the temperature effectiveness of the self-evaporation in the center of the steam was as high as 80%, which clearly shows the effectiveness of this water-sprinkling method. In addition, the basic data for system designing such as water evaporation coefficient from water layer surface and temperature effectiveness of self-evaporation during the f1ight in the steam space were obtained.

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