Absorption refrigeration cycle consume less electric power input and widely use in Japan for the field of air conditioning and refrigeration. And further, this refrigeration cycle could be able to drive using waste heat. However there exists some restriction of temperature range belong to equipment specification. In this study to control concentration of working fluid in the cycle using refrigerant reservoir, experimental apparatus was made and some experiments were performed to examine the fundamental characteristics of this cycle using TFE-NMP as a working fluid.

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One of the most effective methods to use waste heat to energy for the field of air conditioning and refrigeration is the use of absorption refrigeration cycle. And Absorption refrigerator is widely used as air conditioning utility in Japan. In this study, focusing on absorption heat pump for air-cooling and heating, TFE-NMP working fluid pair is used. Therefore TFE-NMP working fluid pair need Rectification in the process of generating refrigerant vapor (TFE). This experiment reveals fundamental characteristics of rectifier.

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On Dynamic-type ice storage system, the continuously preventing technique of the ice growing and adhering to the pipe wall from supercooled releaser to Supercooling chiller is proposed. -2.0 degree level supercooled water cooled by the evaporator of an electric refrigerator is able to be changed to sherbet ice perfectly by the supercooled releaser. Heating (less than 100W) the plastic pipe prevents the ice growing and adhering. 50USRT level experiment results are discussed and the stability prevention of the ice growing and adhering condition is shown.

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The temperature of earth is almost constant (about 16 degree) at 100m below the ground surface through a year and the thermal conductivity of the earth soil is small. These facts show that the earth is suitable as a heat sink and/or heat source. In summertime, the heat absorbed by an air conditioner is transmitted into the earth soil and the heat ia stored until winter. In wintertime the heat is used for heating a building through the heat exchanging system. We call such a system Gaia (goddess of the earth) Energy System. In this paper the authors studied the behavior of the Gaia Energy System by computating the amount of heat transmission. A shortage of this system is poor heat emission into soil. It is because of low thermal conductivity of soil. To overcome this shortage, the authors examined the effect of fins fitted on a heat exchanger pipe, experimentally as well as numerically.

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Absorber in ammonia-water absorption cycle is one of the most critical components from the viewpoint of size compactness, cost reduction, and performance improvement. The objectives of this study are to visualize the bubble shape and to analyze a combined heat and mass transfer for bubble absorption process. This experimental study was performed on a small bubble of ammonia absorption. Ammonia was provided through a single nozzle (2.0mm) into ammonia aqueous solution under system pressures of 0.1 MPa. Concentration of the solution was 0.2 kg/kg and temperature was at 298 K. Visualized date of bubble absorption shows bubble diameter and ascent speed.

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A computer simulation program taking into consideration the effect of heat exchange has been developed in order to predict the performance of absorption refrigeration cycles using waste heat. A double-stage simulation model is applied to a lithium-bromide/water system, with the objective of evaluating the possibilities of effectively utilizing waste-heat as a secondary heat source for the low-temperature generator. It is possible to reduce the necessary amount of high-temperature waste heat while effectively utilizing low-temperature waste-heat. The effectiveness of introducing a secondary heat source of about the same temperature level as the low-temperature generator is also demonstrated.

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Performance of rectifying column affects the coefficient of performance (COP) in an ammonia absorption refrigerator (AAR). Refrigerant mass fraction is one of the key parameters to discuss the performance of the rectifying column. Focusing on the refrigerant mass fraction, this paper presents a method to estimate the refrigerant mass fraction with mass and energy balance and the result of the experiment which measures refrigerant mass fraction by sampling from the refrigerant receiver. Through out these investigations, the refrigerant mass fraction became lower than the expected value which is calculated from the condition of saturated vapor at the top of the rectifying column. We confirm that the refrigerant mass fraction could be estimated with sufficient accuracy from mass and energy balance equations around the separator at the inlet of the evaporator.

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Heat and mass transfer coefficients during ammonia gas absorption into a falling liquid film formed by distilled water on a horizontal tube were obtained experimentally. The test absorber consists of 200 mm i.d., 600 mm long stainless steel shell, a 17.3 mm o.d., 14.9 mm i.d. stainless steel test tube with 600 mm working length mounted along the axis of shell, and a 12.7 mm o.d. pipe manifold of supplying the absorbent. In this paper, it was clear that heat and mass transfer coefficient could be enhanced by increasing the flow rate of absorbent and temperature difference between absorbent and ammonia gas. And new correlations of heat and mass transfer in dimensionless form were proposed.

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In order to optimize the heat driven type MH refrigeration system thermally, the calculation model based on one-dimensional thermal diffusion equation and the experimental using demonstrational system were made. At first, we investigated the thermal optimized driving temperature condition and the best MH alloy's mass ratio. But even though under the thermal optimization condition, the refrigeration performance of this system was not good to compare with traditional one. The reason of it is that the effective thermal conductivity of MH alloy bed is extremely low (about 1 W/m ・K). Then, in order to enhance the refrigeration performance, the mixing carbon fiber into the MH bed is used in this study. The effect of adding the carbon fiber on the refrigeration performance is also analyzed by the above-mentioned calculation model and demonstrational system. As shown in the results of these analyses, we are able to increase the cooling load by carbon fiber mixing. Furthermore, the decrease of COP by adding carbon fiber is not remarkable. Eventually, the mixing carbon fiber is good refrigeration performance enhancement method for this system.

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The authors have developed 310W @-100℃(173K) and 40W @-200℃(73K) Stirling coolers which are designed to be suitable for the cooling temperatures in ultra-low temperature range using the same driving parts. The difference between both the Stirling coolers results from a structure of heat exchangers. The former adopts a plate-fin type heat absorber and rejecter and an annular type regenerator. Meanwhile the latter adopts a cold head as the heat absorber, a gap type heat rejecter and a circular type regenerator. The cooling performances of both the Stirling coolers are the same tendency according to the cooling temperature, but the former measures of increase in cooling capacity and decrease in motor input are so bigger than the latter. The refrigeration systems for industrial use are built up by the former using a secondary heat transfer fluid circuit and also by the latter using direct cooling at the cold head. Those system take effect on the environment problem arising on a terrestrial scale.

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Experimental investigation on blowing-out phenomena of cooled air from the thermoacoustic tube was made with and without high temperature heat exchanger. Although all the instruments was made in fully air-tight, the air blew out continuously from the tube. The flow rate of the air increased with the distance from the outlet hole to the inlet of the measuring tube. The flow rate also increased with the increased of the diameter of the measuring tube.

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The performance of evaporative cooling system with self -supplied water wasexamine experimentally. Humid air was dehumidified through the desiccant dehumidifier and the air was cooled again by evaporation of the condensate that was condensed in the high temperature heat exchanger. Principle of the system was confirmed by this experiment. The amount of condensate was sufficient for evaporative cooling for low humidity condition. While, the condensate was not enough for high humidcondition.

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Refrigeration and air-conditioning equipments have been so widely used that developing their efficiency has great impacts on the saving energy resources and environments. Applying multipass configuration to refrigeration equipments is expected as one of novel approaches for developing the system efficiency. However, terrible maldistribution of refrigerant flow may occur when the dividing flow is two-phase state. In order to solve this problem, we have to predict the phase separation characteristics of dividing gas-liquid two-phase flow. Furthermore, since various fluids come to be used as refrigerants, we need a general method for prediction. Existing researches provided us some prediction models derived from the data of normal diameter (e.g. 30 mm i.d.) T-junctions. In this article, we experimentally obtained the data of the phase separation characteristics for small diameter (6 mm i.d.) T-junction to examine prediction abilities of the existing models.

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Undulation pump artificial heart is a rotary blood pump in which a special mechanism converts the rotation of a motor to the undulation motion of a disc in the pump. Undulation pump total artificial heart(UPTAH) is the most compact total artificial heart in the world. In this paper, performance, control method, animal experimental results and engineering problems of UPTAH will be discussed.

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A monopivot centrifugal pump is being developed for a second-generation artificial heart and the non-thrombogenicity was attained with flow visualization. A hydrodynamic levitation centrifugal pump is also being developed for a third-generation artificial heart and the hemocompatibility is investigated with CFD.

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Requirements for higher durability of artificial hearts and artificial lungs are growing rapidly as the feasibility of long-term life support using these devices has been clinically proven worldwide. Blood compatibilities of the devices, including anticoagulant and antitraumatic properties are among the keys to attain high reliability and durability of the system including these devices. Blood flow conditions inside the devices play an important role in blood compatibilities. In this study, the examples of artificial organ development are given in which the flow visualization techiniques using laser were performed to improve blood compatibility of artificial organs including blood pumps and membrane oxygenator.

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Proper design of a centrifugal blood pump is important to minimize the shear strain rate since the hemolysis has a strong relation to it. In this study, for the purpose of optimizing an impeller vane shape, we estimated the shear strain rate for different vane shapes with the help of CFD analysis, and discussed their probability of hemolysis by comparing the distribution of the shear strain rate. We prepared several impeller models by varying the vane inlet and outlet angles. Simulated results of the straight vane with the inlet and outlet angles of both 90-degree and the curved vane having the inlet and outlet angle of 40 and 90 degree, respectively, showed a larger high-shear-strain-rate-area in the near housing wall region than the others. On the other side, the result of the straight vane with the inlet and outlet angle of 40 and 81.16 degree showed smallest high-shear-strain-rate-area among all the models.

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This paper describes a computational fluid dynamics technique for artificial lung designing. A suitable artificial lung for extracorporeal circulation must offer low resistance and adequate gas exchange. These requirements are largely a function of device geometry, particularly as it relates to fuluid dynamics. To analyze flow behavior, computational fluid dynamics software (STAR-LT : CD Adapco Japan) was used to calcutate flow velocity and pressure drop in the artificial lung models. The inner part (Hollow fiber bundle) of the model was defined as porous medium, which acts like a sponge. Such modeling is highly useful as part of the process of developing artificial lung.

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Bridging to heart transplantation, both assist and replacement type artificial heart systems have been demonstrating effectiveness in the western countries. Since 1999,only 17 heart transplantations have been done in Japan due to severe donor hearts shortage. There is a strong need for implantable artificial heart systems in Japan. This paper describes the current status of artificial heart development in Japan, focusing on the efforts at Tokyo Medical and Dental University.

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A stentless valvular bioprosthetsis using a porcine aortic root has been shown to yield high performance in terms of durability, hydrodynamic characteristics and biocompatibility. The purpose of this study is to show the effect of the difference in methods of implanting the bioprosthesis at the aortic position on the hydrodynamic characteristics of the bioprosthesis. Subcoronary and Full-root techniques, that are mainly used for implanting the bioprosthesis into the aorta, were simulated under conditions in which the degree of elasticity around the bioprosthesis at the aortic root position was varied in a mock circulatory system. As a result, the forward flow at the bioprosthesis in the case of the Subcoronary was 11% greater than that of the Full-root. The variation in the elasticity around the bioprosthesis was suggested to influence the hydrodynamic characteristics.

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We have developed a new artificial pancreas system, "BIONIC artificial pancreas". This was consisted of two types existing artificial pancreas, which were open-loop mechanical artificial pancreas and hybrid artificial pancreas. By combining these two types of artificial pancreas, several problems of both were complemented. In the present study, we developed the simulation software about the blood control system from our experimental data, and investigated the Usefulness of this new system with this software and an animal experiments.

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