Particle Image Velocimetry (PIV) is a technique that measures velocity at multiple points in a flow field from visualized images. Recent developments in electronics devices and extensive studies have enabled the evolution of PIV. PIV has wide application. In this paper, fu ndamentals of PIV were described briefly and current activities of PIV study were introduced.

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The freezing characteristics of a single water droplet placed on the column edge were visually investigated using a video camera. The temperatures of the edge face and the environment air were independently controlled. The solidification process of the water droplet was discussed based on the many pictures obtained. The experimental results indicated that the freezing time of droplet was strongly affected by the edge temperature. Furthermore, we found that the water dispersion thermosensitivity slurry was effective for the observation of the temperature of the droplet. Consequently, it was indicated that the heat transfer characteristics of the droplet under freezing condition were mainly affected by both temperature of the air and surface of the flat plate.

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Study on surface effect of heterogeneous nucleation was investigated using molecular dynamics method with NPT ensemble. Around 1000 water molecules were used and set in a periodic cell. Platinum was selected as material for top and bottom surfaces, since its lattice constant fits closely with ice Ih. Temperature and pressure were set at 250 K and 0. 1 MPa, respectively, for each calculation. Behavior of ice Ih on fcc(111) surface was examined. It was found that the structure of ice remained stable in a case of platinum surface and the structure was destroyed in a case of having a slightly different lattice constant. Behavior of water on Pt surface was also investigated by varying the shape of the surface. Three types of surface were selected, namely, a flat surface, a surface with one projection and a surface with three projections. It was found that, in a case of a flat plate, water next to Pt surface was strongly influenced by the surface and was prevented from forming ice structure. In a case of having one projection, there was a tendency to form an ice structure near the surface. In a case of having three projections, however, the tendency was weakened. Hence, it was concluded that heterogeneous nucleation of water is affected by a lattice constant of the substance as well as the shape of the surface.

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The GHP (Gas engine Heat Pump) system is expected to have high energy-efficiency in utilizing the waste heat exhausted from a gas engine. In summer season, a silica gel-water adsorption cooling unit driven by the exhaust heat is considered as a cooling system for saving energy.
In this work, an attempt was made to improve the COP of a silica gel-water adsorption cooling system by enhancing heat and mass transfer in the silica gel adsorption layer. A unit cell was introduced as a simplified model of adsorber for analyzing the phenomena of heat and mass transfer in the adsorbent. This cell was composed of a single tube with a silica gel layer bonded on its external surface. Optimization of heat and mass transfer characteristics for the unit cell was carried out by experimental and analytical approach.

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Heterogeneous nucleation of water was investigated using Molecular Dynamics method. Solid with fcc(111) surface was placed at the bottom of a cell consisting of 864 water molecules. ST2 model with NPT ensemble was used. The pressure and temperature were set at 0.1MPa and 275K, respectively. The interaction between water and the solid was based on the equations proposed by Spohr. Exception was made on the lattice constant which was slightly modified to fit with that for ice structure. The shape of the solid surface was considered. It was found that the only one layer of water molecules was adsorbed in a case of a flat surface, whereas ice nucleation occurred by removing some of the atoms from the surface. Spohr's interaction was also modified so that the dipole moment of water became anti-ferroelectric. It was found that the modification increased the ice growth, further. The effect of lattice constant of solid on nucleation was also investigated. It was found that the variation on lattice constant with a few percent from that of ice was acceptable for nucleation, especially on shrinking side. On expanding side, however, it gave some gaps for water molecules to fit in other than that for ice structure, and it prevented the growth of ice.

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The characteristics of carbon dioxide cooled under supercritical condition were investigated theoretically and experimentally. Numerical calculations were conducted to get a full understanding of the heat transfer characteristics under variable properties conditions. The effects of parameters such as mass flux, pressure, heat flux and tube diameter on heat transfer coefficient and pressure drop were calculated, and the results were discussed from the distribution of thermodynamic properties inside the cross section. A serial of experimental measurements with a pump cycle was conducted to confirm the above results. Large amounts of experimental data were obtained. These results were compared with those of numerical calculation, and a good agreement was found. The numerical and experimental results show that mass flux and pressure affect the heat transfer coefficient and pressure drop greatly for both middle and small sized tubes, and the effect of heat flux can be observed significantly for a middle sized tube, but for a small sized tube, the temperature distribution inside the cross section is usually small enough to make the effect of heat flux ignorable.

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The characteristics of carbon dioxide cooled under supercritical condition were investigated theoretically and experimentally. Based on the results of numerical calculation and experimental measurements described in the 1st report, a new correlation was proposed to predict the heat transfer coefficient, and the Filonenko's equation was found adequate to predict the pressure drop inside as mall seized tube. Those correlations were compared with measurement results and the deviations were found lower than ±20%. Furthermore, a compressor cycle was assembled to investigate the effect of lubricant oil on heat transfer and pressure drop. The oil content in CO₂ was set to be about 0.5% during the measurements. This amount of lubricant oil was found affected the heat transfer coefficient significantly, with largest degradation of heat transfer coefficient at the pseudocritical point to nearly 50%. The effect of lubricant oil at small concentration on the pressure drop was found negligible.

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Fish protein hydrolysate (FPH) was prepared from the underutilized residues of 3-marine fish species disposed of by-products processing by protease treatment. The major component of the FPH was hydrolyzed protein (82-86%). The concentration dependent protective effect of FPH (2.5-10.0%, dry weight/wet weight) on the wanieso lizardfish (Saurida wnieso) frozen surimi at -25°C was evaluated by determining gel-forming ability, unfrozen water, and myofibrillar Ca-ATPase activity. The gel-forming ability and total myofibrillar Ca-ATPase activity of the surimi with FPH showed significantly higher values than those of without FPH (control) during frozen storage. The amount of unfrozen water in the frozen surimi with FPH was significantly increased compared to that in the control. The results indicate that FPH stabilized the hydrated water surrounding myofibrils. These findings suggest that the FPH prevent the freeze-induced denaturation of the surimi during frozen storage.

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The purpose of this research was to investigate the ice growth of a single crystal in three dimensions. Three-dimensional pattern of ice crystal growth in supercooled water was observed using Mach-Zehnder spectro-interferometer. Temperature was varied from -0.3 to -1.6°C. It was found that the ice crystal began to grow freely as a single crystal at the tip of the capillary tube in supercooled water at this range. The interferometer enables measurement of the thickness of crystal by counting the number of interference fringes. Sectional plane of tip of dendrite was obtained from the results and fits half parabola very c1osely. The coefficient of squared term of a half parabola was found to be depending upon the degree of supercooling and time. The coefficient, a, of a half parabola varied in time but at quasi steady state it was found to be depending only upon the degree of supercooling. Furthermore, the thickness of ice crystal was measured and the growth velocity along c-axis was calculated. It was found to be independent of the degree of supercooling but dependent on time. The equation on crystal growth in c-axis was obtained, experimentally.

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Recently, dynamic type of ice storage system has been high lightened, since it gives a solution to the problem of peak electrical load. The deferent types of the method of ice making produce the different types of ice, and the selection of the type of ice influence the coefficient of performance of ice storage system. Hence studying the shape of ice and its behavior such as stickiness are important. The shape of ice crystal depends on various factors such as concentration of solution, temperature, convection, time and so on. There are various types of ice exists, such as frazil ice, dendrite, needle ice, solid ice, slurry ice. However, there is no report measuring the volume of the crystal, yet, because the shape of the crystal is too complicated to measure. In this report, pure water was used and single crystal ice was formed in supercooled water. The shape of the crystal was measured in three-dimensions using Mach-Zehnder spectro-interferometer. Volume of the crystal was measured. It was found that the volume depends upon time and the degree of supercooling, and experimental equation was derived. Furthermore, projected area normal to c-axis was measured. It was found that the area depends not only on time but also the degree of supercooling.

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In order to measure the latent heat of melting of ice slurries with various solute concentrations, an adiabatic calorimeter was constructed. Ice slurries were made from each aqueous solution of ethanol, ethylene glycol and silane coupling agent. The latent heat of melting of ice made from tap water was measured with the present calorimeter and the uncertainty of the result was one percent. Ice slurries were made both by mixing ice particles made from water with each aqueous solution and by freezing each aqueous solution with stirring in a vessel. The latent heat of melting of these ice slurries was measured with various concentrations of solution. The latent heat of melting decreased as the solute concentration or the freezing point depression increased. The latent heat of ice slurries made from ethanol or ethylene glycol aqueous solution agreed with that of ice made from pure water known already. The latent heat of melting of ice slurries made from silane coupling agent aqueous solution got smaller than that of ice made from pure water as the freezing point depression increased.

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The present paper reports experimental results of the saturated liquid density for four combinations of HFC-134a and its compatible lubricants such as Polyalkyleneglycol (PAG) and Polyolester (POE) oils. The saturated liquid density is measured by the method using spherical buoys made of glass. The experiments have been conducted for temperatures from 256 to 313 K, densities from 933 to 1327 kg• m^-3 and oil-concentrations from 0 to 1. The present results show that the saturated liquid density for HFC-134a+oil mixtures decreases with increasing oil-concentration at a constant-temperature while showing slightly positive or negative deviations from the mass fraction average for the experimental temperatures we have concerned.

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The influence of return bend on the frictional performance of R-410A and R-22 in a 5-mm diameter wavy tube is examined in this study with a curvature ratio of 6. 63. For the single-phase results, the existing correlations give fairly good agreements with the present data. Conversely, the existing two-phase correlations of the return bend fail to predict the present data. For test results of the two-phase flow at G≥200 kg m^-2s^-1, the ratio of (dP_c/dz)/(dP_s/ dz) is approximately equal to 2 and is relatively independent of the vapor quality. However, the ratio of (dP_c/dz)/(dP_s/ dz) decreases with the increase of quality when x is less than 0.3 for a smaller mass flux of 100 kg m^-2s^-1. The value of (dP_c/dz)/(dP_s/ dz) reaches approximately 5 for x = 0.1 that may be attributed to the change of the two-phase flow pattern. The frictional two-phase multiplier in U bend can be fairly correlated by using the Chisholm correlation. By introducing the Martinelli parameter to the Chisholm correlation, a new correlation could be obtained to describe the present φ²_B,L data if more experimental data are available.

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Experimental specific isochoric heat capacities (Cv) and P_ρT properties for isobutane are presented that were measured with a twin-cell type adiabatic isochoric calorimeter. The measurements were obtained for temperatures from 272 to 408 K and for pressures up to 30MPa. The sample purity was 99. 99 mol%. The expanded uncertainties (i.e., a coverage factor k= 2 ) are ±l3 mK for temperature, ±8k Pa for pressure, ±0.16% for density, and ±3.6% for Cv in the liquid phase. An evaluation and a comparison of the experimental data with highly reliable equations of state confirmed satisfactorily the thermodynamic consistency of the present measurements.

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Specific heat capacity at constant volume is one of the most important thermodynamic properties to develop and evaluate thermodynamic equations of state. With this viewpoint, isochoric heat capacities of ethanol-water mixtures have beenmeasured with a twin-cell type adiabatic calorimeter developed at the National Defense Academy. Temperatures were measured with a platinum resistance thermometer on the bottom of each cell and were reported on the ITS-90. Sample pressure measurements were made with a quartz crystal transducer. Densities were calculated from the volume of the calorimeter cell and sample mass. The experimental expanded uncertainty (with a coverage factor k=2)of temperature measurements is ±13mK, and that of pressure measurement is ±8kPa. The expanded relative uncertainty for isochoric heat capacity is estimated to be ±2% for liquid phase measurements, and for density it is ±0.16%. The present measurements for {xC₂H₅OH + (l-x)H₂O} with x=(0.104, 0.253, 0.498 and 0.755), were obtained at temperatures from 280 to 420 K and at pressures up to 30 MPa.

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A dynamic analysis of a free piston Vuilleumier cycle heat pump was performed using a time-stepping integration method to investigate transient characteristics under power controlling. The nonlinear relationship between displacement and force for pistons was taken into account for the motion of reciprocating components. The force for pistons is mainly caused by the pressure change of working gas varying with piston displacements; moreover nonlinear viscous dissipative force due to the oscillating flow of working gas in heat exchangers and discontinuous damping force caused by solid friction at piston seals and rod seals are included. The displacements of pistons and pressure changes in the Vuilleumier cycle heat pump were integrated by an ideal isothermal thermodynamic relationship. It was assumed that the flow friction was proportional to the kinematic pressure of working gas, and that the solid friction at the seals was due to the functions of the working gas pressure and the tension of seal springs. In order to investigate the transient characteristics of a proposed free piston Vuilleumier cycle heat pump machine when hot-side working gas temperatures and alternate force were changed, some calculations were performed and discussed. These calculation results make clear transient characteristics at starting and power controlling. It was further found that only a small amount of starter power is required in particular conditions. During controlling, the machine becomes unstable when there is ar elatively large reduction in cooling or heating power. Therefore, an auxiliary device is additionally needed to obtain stable operation, such as al inear motor.

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This paper constructs the static simulation model of a desiccant air conditioning system and gives the guidelines for the efficient drive of the desiccant air conditioning system. The desiccant air conditioning system is composed of a desiccant wheel, a heat exchanger, two evaporative coolers and a heater. The process air and regeneration air are supplied to this system. The desiccant is Silica gel. In the simulation model, two-dimensional model in space is adopted for the desiccant wheel. As the simulation result, it is clarified that optimum outlet temperature of the regeneration air in the heater, rotational speed of the desiccant wheel, the rejected air flow rate of the regeneration air, the process and regeneration air flow rate that maximize COP exist. For example, in case that the regeneration temperature is 63°C and relative humidity is 55% maximum COP is about 0.62.

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This paper concerns the stability of Nd (neodymium) sintered magnets used for high-efficiency DC motors in refrigerant compressors. Many kinds of Nd sintered magnets with and without surface treatment were subjected to the aging test of 140°C and 1440 hours under three different atmospheric conditions of refrigerant, oil, moisture content and vacuum level. Mechanical and magnetic properties of the magnet were examined, and chemical characteristics of the oil and refrigerant were also analyzed As a result, most of the tested magnets retained the satisfactory properties after the aging test, but some magnets without surface treatment showed deterioration in magnetic properties. The deterioration was larger under the condition with higher moisture content. Concerning the oils and refrigerants, no remarkable change in their chemical characteristics was observed after the aging test. The test conditions employed in this study become one of the evaluation criteria of the Nd sintered magnets.

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We tested to use several compositions of a four-component-mixture R 32/125/134a/600 as a refrigerant for replacing R 22 in refrigeration system of refrigerated warehouses. R 32, R 125, and R 134a are hydrofluorocarbons and R 600 is normal butane. The refrigeration system designed for R 22 can be used without any change or with very minor change. By using appropriate composition of the four-component refrigerant, existing refrigeration system can provide best performance because the adjusted properties of the refrigerant can somewhat compensate for the individual hardware problems. Practical operation test was done by using a refrigeration system of nominal cooling capacity of 30.2 kW with a 22 kW two-stage compressor which equipped for an 858m³ refrigerated warehouse maintaining at -30°C. The pressure condition and the coefficient of performance of R 32/125/134a/600 are similar to R 22 from a theoretical viewpoint. The power consumption of R 32/125/134a/600 was small enough or not to be worse than that of R22, which was confirmed from the actual test results.

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This study deals with experimental results and data reduction model for a counter-current slug flow absorber working with ammonia-water mixture for significantly low solution flow rate-condition that is required for operating as the GAX cycle. From visualization results of flow pattern, frost flow just after the gas inlet followed by slug flow with well-shaped Taylor bubble are observed, while dry patch on the tube wall are not observed. The local heat flow rate is measured by varying main parameters, namely, pressure, ammonia gas flow rate, solution flow rate, ammonia concentration of inlet solution and coolant inlet conditions. A data reduction model to obtain local heat and mass transfer coefficient on the liquid side is proposed by using the drift flux model to analyze the flow characteristics. Control volume method and heat and mass transfer analogy are employed to solve the combined heat and mass transfer problem. As a result, it is found that the local heat and mass transfer coefficient on the liquid side is greatly influenced by the flow pattern. The heat and mass transfer coefficient at the frost flow region is higher than that at the slug flow region due to flow disturbance and random fluctuation.

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