A Stirling cooler (refrigerator) was proposed in 1862 and the first Stirling cooler was put on market in 1955. Since then, many Stirling coolers have been developed and marketed as cryocoolers. Recently, Stirling cycle machines for heating and cooling at near-ambient temperatures between 173 and 400K, are recognized as promising candidates for alternative system which are more compatible with people and the Earth. The ideal cycles of Stirling cycle machine offer the highest thermal efficiencies and the working fluids do not cause serious environmental problems of ozone depletion and global warming. In this review, the basic thermodynamics of Stirling cycle are briefly described to quantify the attractive cycle performance. The fundamentals to realize actual Stirling coolers and heat pumps are introduced in detail. The current status of the Stirling cycle machine technologies is reviewed. Some machines have almost achieved the target performance. Also, duplex-Stirling-cycle and Vuilleumier-cycle machines and their performance are introduced.

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A pulse tube refrigerator has high reliability because of its simple structure. Recently the level of development activity of the pulse tube refrigerator has increased, but the quantitative understanding of the refrigeration mechanism has not fully been obtained. Therefore various explanations were proposed. The concept of virtual gas piston in particular helps us to understand the function of a phase shifter such as a buffer tank and an orifice because the virtual gas piston corresponds to a piston of a Stirling refrigerator. However it is difficult to directly measure the averaged gas displacement which corresponds to the virtual gas piston because uniform gas flow such as a gas piston does not always exist. For example, there are a jet flow from orifice and circulated flows in a pulse tube, which are predicted theoretically. In spite of these phenomena, the averaged gas displacement is very important in practical use because it can simply predict the performance from the displacement.
In this report, we calculate the averaged gas displacement and mass flow through an orifice. The mass flow is calculated from the pressure change in a buffer tank. The averaged gas displacement is calculated from temperature profiles in the pulse tube and the mass flow. It is necessary to measure temperature in the pulse tube as widely as possible in order to calculate the averaged gas displacement. We apply a method using the Rayleigh Scattering the thermometry in the pulse tube. With this method, it is possible to perform 2-dimensional measurement without disturbing the gas flow. By this method, the averaged gas displacements and the temperature profiles of basic and orifice types of refrigeration were compared.

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On assuming the abscissa moving uniformly with the horizontal airflow in disregard of gravity, airflow motive force and heat transfer by the water spray have been easily analyzed theoretically. Here main results are as follows.
The theoretical maximum airflow motive pressure is proportional to both the initial relative velocity of waterdrop and the relative water flow per unit cross-sectional area of the apparatus to the airflow or the moving abscissa but unrelated to the size of waterdrop. The airflow motive pressure approaches to the above maximum with an increase in the length of the apparatus. Making the waterdrop size smaller has an effect on the aparatus to get longer virtually.
The initial velocity of waterdrop or the spraying nozzle pressure has little effect on the heat transfer between the air and the water.

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Phase separation of gas-liquid two-phase flow at an impacting tee was investigated experimentally and theoretically. It was found that the phase separation did not occur, if the outlet branches were symmetrical and pressure drops in these branches were identical. On the other hand, if the flow rates in the branches were different, phase separation was observed. Based on the principle of minimum energy dissipation, a thermodynamic model was derived. The results of the model were qualitatively in good agreement with the experimental behavior of impacting flows.

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In the present study, a prediction model for condensation of binary zeotropic refrigerant mixtures inside a horizontal smooth tube is proposed. In this model the following assumptions are employed : (1) The phase equilibrium is established at the vapor-liquid interface, while the bulk vapor is saturated and the bulk liquid is subcooled. (2) The heat transfer coefficients in liquid film and the frictional pressure drop are calculated by the correlations for pure refrigerants proposed by Haraguchi et al. (3) The mass transfer coefficient in the liquid film is infinite, and the mass transfer coefficient in the vapor core is estimated by a correlation that is derived from the correlation of the frictional pressure drop, based on the Chilton-Colburn analogy.
The predicted results are compared with the experimental ones for the condensation of HFC134a/HCFC 123 and HCFC22/CFC 114 mixtures. The predicted heat flux distribution along the tube axis is in good agreement with that of the experiment, and the calculated values of condensing length agree well with the experimental ones. Using the present model, the local mass fraction distribution, the diffusion mass flux and the mass transfer characteristics in both vapor and liquid phase are also demonstrated. From these results, the effect of mass transfer resistance on condensation heat transfer characteristics is clarified.

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Experimental and analytical studies for freezing phenomena of ethylene glycol solution on a vertical cooled polyvinyl-chloride plate have been performed. It is found that the crystal ice formed on the vertical plate is removed from the plate surface due to buoyancy force acting on the crystal ice. It is shown that the crystal ice formed on the vertical plate slides along the plate surface due to buoyancy force and the crystal ice grows in a shape of sheet by joining with the neighbour ice. The number of the removed ice per unit of time is, therefore, decreased as compared to that for the horizontal plate. It is found that the onset of ice removal condition is related to the heat fluxes from the plate surface to the plate and from the plate surface to the solution. The ice removal occurs easily for a vertical plate than for a horizontal one.

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In planning an air conditioning system, supply water and air temperatures are important factors from the viewpoint of cost reduction. For example, lower temperature supply water and air reduce the coefficient of performance of a refrigeration machine, and increase the thickness of heat insulation material. However, they enable larger temperature differences, and reduce equipment sizes and power demand. The purposes of this paper are to propose an optimal planning method for a cold air distribution system, and to analyze the effect of supply water and air temperatures on the long-term economics through a numerical study for an office building. As a result, it is shown that the proposed method effectively determines supply water and air temperatures for a cold air distribution system, and that the influence of supply air temperature is larger than that of supply water temperature on the long-term economics.

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By means of the transient hot-wire method, the measurements of thermal conductivity of ethanol water mixtures were carried out between-70 to-40° over the entire range of compositions. Furthermore, isobaric specific heat capacities were derived from the thermal conductivities measured. The thermal conductivities and isobaric specific heat capacitis of the ethanol-water mixtures were determined with an accuracy of±3% and ±6%, respectively.

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Because of the depletion of the stratospheric ozone layer, CFCs and HCFCs are on the way to the phase out. HFCs are one of the promising alternatives, but they have large global warming potential. From the viewpoints of ozone depletion and global warming, natural working fluids for compression heat pumping systems are being watched with keen interest especially in European countries. In the present study, cycle performances of propane, ammonia and carbon dioxide as a working fluid are calculated, and are compared with those of HCFC22. A theoretical fundamental heat pump cycle and a fundamental cycle with secondary refrigerant are selected for comparison; besides, a liquid injection cycle for ammonia and an internal heat exchange cycle for carbon dioxide are calculated. The effects of heat transfer characteristics and pressure drop in heat exchangers on heat pump performance are evaluated.

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In this paper, a new exhaust and air-supply system is presented. Conventionally, Ventilation systems which have two fans separately for exhaust and air-supply purposes, have been used widely to improve indoor comfort. However, these conventional systems are known to have some demerits : large driving power, high product cost and difficulty of taking-off impellers for cleaning, especially, when used as kitchen range hood fan systems, since these two fans are installed on the same driving shaft. The developed system has only one fan which separate exhaust flow and air-supply flow by using a labyrinth fin. The developed system has been compared with a conventional system and confirmed that the new system shows better performance from the viewpoint of energy saving and noise control.

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