Evaporation of water droplet can be enhanced by plasma irradiation that increases the surface wettability. Relation between plasma irradiation time and contact angle was examined first and then the lifetime of water drop on hot surface was measured changing the surface wettability by plasma irradiation. The lifetime of water drop decreased and the wetting limit temperature increased with the increasing irradiation time of plasma. Plasma irradiation changes contact angle but it is not stability. We found that contact angle is stability in limited conditions.

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In BWR, it is desired that post-BT heat transfer correlation can predict with high accuracy, from the viewpoint of POST-BT operation under abnormal transient. The post-BT test was carried out in an out-of-pile test facility that could simulate current BWR condition. Using these test data, the new post-BT heat transfer correlation was developed. The new heat transfer correlation agrees with present data well.

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This paper concerns the condensation of carbon dioxide and its heat transfer on vertical cylinder in sub critical region. In this region, physical properties show marked temperature and pressure dependence. In particular, as the pressure increases and approaches the critical point, the difference in the properties of liquid and vapor, and surface tension approach zero. Therefore, condensate flow from natural convection decrease and the configuration of condensation differ from that at lower pressures. In this study, the flow regimes were classified into the smooth laminar flow, wavy flow and wavy flow with scattered droplets based on observing condensate flow. And heat transfer is discussed in connection with the flow regime.

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Sustainable small-scale spontaneous vapor explosion was proposed to utilize for the innovative rapid cooling and the liquid atomizing processes, namely the CANOPUS method. On the basis of CANOPUS method, a highly viscous coal gasification slag was atomized into 30μm powders for use of cement raw materials. The cooling rate of Al_<89>-Si_<11> particle was up to 1.5×l0^8K/s, which is more than 280 times higher than the conventional cooling method.

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Impinging jet is very useful for heat transfer and mass transfer enhancement. Historical research process on the impinging jet heat transfer is described systematically. The present paper is composed of two stages. In the first stage, the heat transfer characteristics of impinging jet are described for the heat transfer movement of a single circular impinging jet, an inclined jet and an impinging jet with an oscillated surface. In the second stage, a systematic structure of an impingin jet and a heat transfer mechanism are explained corresponding to the turbulent structure at the stagnant region, turbulent heat flux and three-dimensional vorticity.

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Heat and mass transfer in the separated, reattached, and redeveloping regions of incompressible or compressible flow is very important in relation to many types of heat exchangers. There have been numerous works on published describing these flows for a wide variety of geometric configurations. In the present article a survey is made of published studies of heat transfer in the separated, reattached, and redeveloping regions of incompressible flow around or in a wide variety of flow configurations. Flow configurations cited in the article are the downward facing step, the sudden expansion plane channel, the abrupt expansion tube, the blunt flat place, the longitudinal blunt circular cylinder, and the surface mounted obstacle. The laminar and turbulent flow cases using both experimental and numerical methodologies are reviewed.

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The temperature fields on an impingement plate are fluctuated when the jet impinged on it, because jet is fluctuated by shearing vortices generated at a nozzle exit. To clarify the influence of flow fluctuations on temperature fields, the time and spatial temperature profiles over the impingement plate were measured using an infrared radiometer, moreover the flow fields were visualized by the means of Fluorescein injected upstream nozzle exit. It is found that the heat transfer was enhanced due to the sweep like motion of thermal boundary layer, and that the frequency of fluctuating temperature on the heated plate nearly corresponds to that of the passing vortex over the heated plate.

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The behavior of ring vortices and the impingement heat transfer of the pulsating axisymmetric jet were studied experimentally by using water jet and air jet, respectively. The growth of ring vortices was visualized by the dye injection on condition that F=1〜5Hz and A=0.075〜0.194. The heat transfer coefficients at the stagnation point were measured on condition that St=0.5〜0.8 and A=0.3〜0.7. It was observed that the frequency of ring vortices was equal to the pulsation frequency. And the growth of ring vortices and the velocity fluctuation in the pulsating jet depended on the pulsation conditions. The heat transfer coefficients were therefore varied uniquely by the pulsation frequency and the amplitude ratio.

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Wall temperature and velocity of a stagnation region of a plane impinging jet were measured by using thermochromic liquid crystal (TLC) and PIV. The plane jet was excited in time and space by adding suction / blowing type disturbances produced by servomotor-driven injectors. Surface temperature distribution showed unsteady streaks in parallel to a wall jet direction. The lowest spatial-averaged-wall temperature and vorticity intensity on the wall could be realized when the phase angle of the adjacent disturbance-wave train was φ=π, in which chain-link-fence structures were expected to be formed in the free-jet region upstream of the stagnation region.

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Gas-flow in a free jet was calculated from a large eddy simulation (LES) and measured using a particle-image velocimetry (PIV). By comparison between both results, it was shown that LES could well simulate the turbulent flow in the fully developed region. Also, the behavior of vortices at the shear region was investigated.

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The local heat transfer characteristics of non-isothermal two-dimentional impinging hot air jets were investigated experimentally. Average and local heat transfer coefficients between an impingement plate and two-dimensional impinging hot air jets were measured by thermocouples mounted in a heat transfer block. Furthermore, the spontaneous appearance and growth of streamwise vortices were observed by high speed real-time laser holographic interferometry. From the results, it was found that the local heat transfer characteristics were quite different with in case of single nozzle and in case of multi-slot nozzles. Also it was cleared that the local heat transfer coefficients at the stagnation line were affected by the large-scale vortices on the boundary layer.

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In the subcritical Reynolds number range, the effect of aspect ratio (1〜8) on heat transfer characteristices under the tone-excitation impinged by a ellipse air jet has been studied experimentally. The main results are:(1) the position of axis-switching tends toward the downstream with the increase of aspect ratio. (2) For a larger aspect ratio, Cp and Nu under the tone-ecxitation added from the minor axis direction had small value and their profiles became flat, but those from the minor axis direction did not vary such as the results without tone-excitation.

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To control the heat transfer on the impingement surface, the oscillating rectangular jet, which flaps periodically in a direction normal to the nozzle axis, has been developed. The oscillating jet apparatus consists of the contraction section, the control ports having the PZT valves and the diffuser section. By opening and shutting the PZT valves, the jet was oscillated by the Coanda effect. In this study, the jet was oscillated in 1, 2 and 4Hz, and the distributions of the velocity and heat transfer coefficient were measured. The velocity profile was spread in wide spanwise direction, however, the maximum velocity decreases from the normal jet. The heat transfer coefficient was not changed with the jet frequency.

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Heat transfer characteristics of two-dimensional impinging jet were evaluated numerically for sinusoidal velocity at nozzle exit. Numerical calculation was carried out for Reynolds number,Re=500, 1000, and frequency, f=l, 2, 5, 10[Hz] at Prandtl number Pr=0.71. Local heat transfer is improved or is depressed within one period for low frequency. However, it is enhanced for high frequency within the present numerical conditions. Therefore, the frequency region which gives the heat transfer improvement, is determined for each Reynolds number.

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The temperature and the pressure distributions on a plate in the dual underexpanded impinging jets are experimentally and numerically studied in this paper. The experiments were performed by measuring the adiabatic wall temperature using an infrared imaging camera, wall static pressures and by visualizing density fields using schlieren method. Numerical calculations were also conducted by solving three dimensional compressible thin layer Navier-Storkes equatons . The main parameters for the dual jets are the nondimensional distance between the two nozzle centers H/D covering 1.5, 2.0, the nozzle to plate separation L/D 2.0, 3.0 ,4.0 and 5.0 and the pressure ratio defined by p_0/p_b 1.0〜6.0, where D is the diameter of each nozzle exit, p_0the stagnation pressure and p_b the back pressure. It is found that the agreement between the two jets is observed both in the experiments and the calculation. Moreover, the flow separation near the plate is predicted by the calculations.

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Two dimensional distributions of heat transfer coefficient on an inclined flat plate in an underexpanded impinging jet are measured by means of infrared camera. As a result, the temperature and pressure distributions show that the stagnation point at which the wall static pressure and wall temperature become maximum is independent of the pressure ratio for any inclined angles. Furthermore, in case of plate jet, the heat transfer coefficient around the stagnation point is found to be larger than that at the stagnation point itself. On the other hand, the heat transfer for the inclined plate at the same condition as the previous one differ from that for the normal impingement.

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A novel coaxial jet nozzle equipped with a row of miniature electromagnetic flap actuators was applied to active control of a methane-air diffusion flame. The flame and associated flow structures were studied through flow visualization, while the combustion gas composition at a postflame location was investigated by an FT-IR exhaust gas analyzer. The flap motion synchronized with a square-wave signal at the preferred mode frequency was found to be effective in stabilizing the lifted flame, because it provided a well-mixed fuel-air mixture at its flame base, achieving low NOx emission. On the other hand, a sawtooth-wave signal control stabilized the lifted flame dramatically, and led to low UHC emission with successive supply of large scale vortices at its flame base.

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The axial cross section images of seeded air jet were taken using Nd:YAG Laser. Based on concentration fluctuation of these images, concentration integral scales were calculated and compared with velocity integral scales calculated from streamwise velocities measured by particle image velocimetry. As a result, concentration integral scales are smaller than velocity integral scales within the region that it was measured (s/D<54), and decrease rapidly in the range that s/Dis smaller than 20.

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An experimental study was carried out to investigate the unsteady heat transfer in the separated flow behind a circular cylinder in cross flow. The Reynolds number ranged from 1.2×10^3 to 4.8×10^4. Local and instantaneous heat flux on the surface was measured by a heat flux sensor and instantaneous temperature distribution on the surface was measured by an infrared camera. In the range of 3×10^3&le;Re&le;1×10^4, the Nusselt number in the separated flow region decreases suddenly with the decrease in the Reynolds number. The reason for this is explained that the effect of alternate reattaching flow on the rear face is intermittent below Re&sp;1×10^4, because the formation region of the rolling-up of the shear layer moves downstream.

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The effects of a longitudinal vortex on the local heat transfer and time-spatial temperature distributions downstream of backward-facing step were investigated. The longitudinal vortex was generated by the pairs vortex generators consisting of two rectangular blades, increasing linearly in separation downstream, are aligned laterally to the flow with a spacing at upstream region of the step. The temperature at near the reattachment point is fluctuated periodically for vortex generator, and the distribution of heat transfer coefficients averaged spanwise direction becomes flatter than that of the smooth. However, characteristics of heat transfer is similar to the smooth.

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Fluid flow and heat transfer characteristics of flow in symmetric channels with periodically grooved parts are investigated for the variations of period and height of the groove. Heat transfer increases significantly after the bifurcation from steady state flow to oscillatory one with the increase of pressure drop penalty. The efficiency defined as the ratio of the heat transfer enhancement to the drag increase is analysed to clarify the optimum channel geometry.

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The development process of self-sustained oscillation in a grooved channel, in the stream-wise direction, is studied by the electrochemical method. The unsteady wall shear stress results for three grooves show that the flow periodicity in the stream-wise direction is preserved after the onset of the self-sustained oscillation. However, as the Reynolds number is increased, the periodicity disappears and the magnitude of unsteadiness increases in downstream direction.

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This experimental study describes mass transfer enhancement in a wavy-walled tube for pulsatile flow. The effect of Strouhal number on mass transfer enhancement is especially focused. It is found that the peak mass transfer enhancement occurs at an intermediate Strouhal number, depending on the oscillatory fraction of the flow rate. The flow visualization result indicates that the unstable flow generated in the decelerating phase leads to the fluid mixing and contributed to the mass transfer enhancement.

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A new cooling technology for a system of arrays of heated cylinders using winding cooling air is shown.The new cooling technology decreases the temperature differences among heated cylinders. The highest temperature exists in the midst of the cylinders, because the distance between them is very small and the cylinders generate heat uniformly. The winding cooling air runs to the right of the cylinders and then along their axis. The temperature differences among heated cylinders are decreased when the pitches between cylinders increase in flow direction.

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The purpose of this study is to develop the dynamic model of the formation of density gradient layer in the storage tank due to the injection of dense fluid through a horizontal bottom-fill nozzle with inclined upward jet mixing into a tank partially filled with fluid. An analytical model was proposed on the formation of density gradient layer, and the density profile was obtained experimentally using a small tank and salt water. The analytical results was in good agreement with the experimental results.

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The nozzles for one-component two-phase flow are used in the total-flow system, which applied to the geothermal and the waste heat recovery power plants. Thermal energy can be transformed into kinetic energy by the nozzle. We have been investigating subsonic mist flow with velocity and temperature relaxation phenomena in a convergent-divergent nozzle in order to elucidate the critical flow and shock waves in it. In this paper, phase change (boiling) is taken into account, which is one of the most important phenomena in one-component two-phase flow. It is shown that phase change can increase the velocity of the two-phase flow, but not affect the feature of shock waves in subsonic flow.

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The present paper deals with the heat and mass transfer characteristics in the production process and melting of ice slurry, to which an increasing interest was paid due to its applications not only for cold thermal storage but also the energy transportation in high density and emergency cooling system. The attention was mainly paid, from the physical point of view, for the production mechanism of fine ice particle by the moving cooled plate method and for the flow and melting characteristics of ice slurry through the rectangular duct. In the production process of ice slurry by the moving cooled wall, the adhesion mechanism of fine ice particle was discussed. For the melting process of ice slurry flow, on the other hand, the behavior of ice particle and its effects on the heat transfer at the retuning bend were discussed.

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In order to use fluidity characteristics of ice slurry, it is neccesary to prevent ice particles.from adhering a cooling surface and agglomeration of ice particles. The purpose of this study is to observe ice particle characteristics of propylene glycol water solution added with an antiagglomeration surfactant. The results revealed that the fluidity characteristics of ice particles were made by the surfactant in comparison with the solution without the surfactant.

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We experimentally investigated the relation between the size of different kinds of ice thermal storage container filled with ice harvesting and the characteristics of the outlet temperature. We obtained following results : (1) The modified Stanton number can be used to effectively evaluate ice melting characteristics of different sizes of the container. (2) The outlet temperature from the ice thermal storage container can be estimated by modified Stanton number.

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Water-silicone oil emulsion with a silane coupling agent was used as a phase change material. Using stainless steel vessels coated with PFA resin, experiments of forming ice with stirring were carried out under various conditions of the temperature of brine for cooling and the composition of emulsion. We investigated the correlation between cooling heat flux and ice adhesion to the cooling surface in the ice formation process. The following results were obtained, (a) Silicone oil has the effect of preventing the formed ice from adhering to the cooling surface, (b) Under a condition of the same concentration of the additive, the maximum cooling heat flux without adhesion in the case of water fraction of 80vol.% was larger than that in the case of 100%.

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We've numerically investigated ice thermal storage characteristics of thermal storage tank packed with thermal storage material into spherical capsules (φ 40mm). The conditions of numerical analysis are that spherical capsule size is relatively large to the tank volume, and that heat medium flows one way in the tank. The following results were obtained from the numerical analysis. In the early time of ice thermal storage mode, low temperature fluid tends to flow at the bottom of tank, however, in the time of the mode going on, the fluid tends to flow uniformly in almost all the area of tank except around the inside wall. In the low velocity condition of the fluid, temperature distribution in the vertical direction of the fluid and the capsules occurs clearly, however, in the high velocity condition of the fluid, the temperature distribution is relatively uniform.

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A system with a water-embedded-type ice storage vessel is widely used because of its simple structure and compactness. However, the water-embedded-type ice storage vessel has a disadvantage, that is, the splidification rate is very small. The use of falling water film seems to be one of promising ways for solving this disadvantage. We have found in a previous study that the use of the falling water film is very effective, especially for high initial water temperatures. In the present study, we examined the performance of a falling-water-film-type ice thermal energy storage vessel with practical size, having vertical heat exchanger plates.

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The present study deals with the characteristics of the heat storage vessel packed with rectangular phase change materials by numerical analysis. The latent heat storage materials in the vessel are heated by utilizing the natural convection of the heat transfer medium, which flow the interval of the latent heat storage materials. The interval of rectangular latent heat storage materials is greatly related to natural convection of the heat transfer medium. Numerical results revealed temperature profiles and flow patterns of the heat transfer medium affected the heat storage characteristics.

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In order to clarify the effect of bubbles on freezing of supercooled water, two kinds ol experiments were carried out. In the first experiment, diameters and the number of bubbles in the water samples were measured using a CCD camera. The water samples had a free surface to observe and count the number of bubbles. In the second experiment, the degree of supercooling at freezing of supercooled water was measured. Water samples were covered with silicone oil to trap bubbles in the water. In each experiment, two kinds of water sample conditions were prepared. Ultra pure water was used and air was saturated at the room temperature. The volume of the water samples was 1cm^3 and bubbles were introduced into water samples. In the case of condition (1), the holding time period before starting the experiments was 0 hour at free surface. On the other hand, in the case of condition (2), the holding time was 100 hours at free surface. It was found that a lot and wide range of bubbles existed in the water samples in the case of the holding time of 0 hour at free surface. On the other hand, there were few number of bubbles in the case of the holding time of 100 hours. Meanwhile, degree of supercooling at freezing was high in the case of the holding time of 100 hours compared to the one of the holding time of 0 hour. The reason was suggested that the bubbles in the water can be released from the surface in the case of lOOhours and trapped at the oil-water interface in the case of Ohour. Hence, it was clarified that bubbles had effects on the freezing of supercooled water.

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In this paper the effect of porous metal plate-type-fin on the melting process of latent heat storage is studied fundamentally. Experiments using paraffin wax with the melting point of some 40℃ are conducted under the uniform heat flux condition for three kinds of heat storage systems (the system without any fins and the systems with vertical fin arrays and a single vertical fin). From the experiments, the melting pattern and the transient temperature change for each system are clarified. Further, natural convection flow in the system during the melting process is visualized using the photochromic technique. The visualization of the temperature field near the heat source wall is also tried using the shadowgraph technique.

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In this study, the effect of carbon fiber brushes on conductive heat transfer around heat transfer tubes is discussed. The experimental apparatus imitates a part of a heat exchanger. The transient thermal responses in the thermal energy storage material are measured. Numerical simulation is also carried out for the anisotropic conduction caused by the brushes. Carbon fiber brushes enhance remarkably the conductive heat flow in the thermal energy storage material. Transient thermal responses improve with an increase of the brush diameter db until d_b, reaches the distance between outer tube walls l_p'. Numerical results are good agreement with the experimental results.

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It is known that an ice particle in oil with uniform electric field reciprocates between electrode plates. This paper describes the utilization of above phenomenon for the melting augmentation of the ice particle. Experiment is carried out in silicone oil, and the particle diameter is approximately 3mm. As a result, the velocity from the positive electrode to ground level one is larger than that from the latter to the former. Each velocity increases with the advance of the melting. The overall heat transfer coefficient decreases with the melting and approaches to constant value.

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River water temperature does not rise in Summer,and does not fall downn in Winter.lt is used its heat enagy in the warm area. But in the cold area, it cannot be used ,because water temperature fall down. Economically heat exchange is difficult. Fluidized bed can supperss ice formation. So we research on suppression of ice formation by using liquid fluidized bed. It was found the ice thickness calculated by heat resistance and that measured are not in agreement. As a result, the former is thinner than the latter.

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Freezing phenomenon of solution including small particle has two special characteristics: (1) the particles are swept from freezing front, (2) the particles are trapped by the progress of freezing. In this paper, behavior of an isolated particle on the freezing front with freezing was investigated theoretically and experimentally. As the force acting on the particle, we considered electric double-layered force, van der Waals force, viscous drag and gravity forces, and proposed a theoretical model considered these forces. The predicted results were compared with the experimental results for electrolytic and non-electrolytic solutions. The critical freezing velocity (the maximum freezing velocity that the particle is swept on the frozen layer) depends on the particle diameter. Also, the critical freezing velocity in electrolytic solution rapidly decreases with the increase of electrolytic concentration on the freezing front.

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For the purpose of the utilization as a high-functional thermal insulation material, the analytical investigation on the heat transfer mechanism of thermal wave propagation within a solid with dispersed phase change material has been performed. The disperse condition of the phase change material and its weight ratio, the wave cycle of temperature, and melting temperature of the phase change material were set as the parameters , in the present analysis. The results have shown that the thermal-wave propagation characteristics were greatly influenced by the latent heat of phase change material and its disperse condition.

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In this report, we summarize a calculation method of crystal growth of binary semiconductors and apply the method to the analysis of InAs-GaAs binary crystal growth under 1g conditions. We investigate the effect of convection induced in the solution on the crystal growth process of an InAs-GaAs semiconductor. The effect of the gravitational directions and the crystal size on the crystal growth process is also investigated.

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We develop a numerical calculation method of crystal growth of InAs-GaAs by the Travelling Liquidus Zone (TLZ) method. We investigate the possibility of growing a uniform In_<0.3>Ga_<0.7>As binary compound semiconductor under microgravity conditions, forcusing on the crystal growth rate and supercooling . We find that the crystal growth rate coincides with the diffusion limited case under microgravity conditions. Supercooling is remarkably reduced by reducing the zone width.

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The change in profile caused by melting, flowing, and solidifying in the arc welding of plates was numerically calculated. The temperature distributions and molten regions in the plates were calculated by a finite element method and with an enthalpy method for phase change. The change in the surface profile of the molten pool under arc pressure and surface tension was calculated by a finite difference method. When the arc pressure was high, the bottom surface of the molten pool appeared and an unsatisfactory wavy or humped geometry remained after welding. The effects on the final geometry of the arc pressure, of the heating rate, and of the welding moving speed were obtained and used to determine optimum conditions.

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Taking advantage of this opportunity when the first Thermal Engineering Division Conference of the JSME in the present century is going to be held, the author aims to summarize how the thermophysical property research on technically-important fluids did contribute a series of remarkable achievements in the field of science and technology during the past century. Emphasis will be given to the significant progress in thermophysical property researches on water substances and refrigerants followed by environmentally-acceptable alternative refrigerants. The former has brought electric power generation that was still a novelty a hundred years ago into the most essential energy supporting our current daily lives, while the latter has made it possible that human being could harness air-conditioning which was nonexistent in the beginning of the last century. All what we have learnt throughout thermophysical property researches over the last several decades will then be discussed so as to identify what we have to do for the present 21st century.

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Some of thermodynamic properties, i.e., vapor pressures and PVT properties for the new alternative refrigerant have been need as soon and correctly as possible for aiming to use them industrially. In this study a new apparatus using the solid piston variable volume method was developed for the measuring the thermodynamic properties of alternative refrigerants. The measurable ranges of this experimental apparatus are from 278 K to 333 K in temperature, and from 1.0 to 4.0 MPa in pressure. The uncertainties of this study were estimated within ± 18 mK is temperature, ±3.0 kPa in pressure, and ±0.45 % in density. The variable volume vessel was determined between 14.0〜16.0 cm^3 by measuring saturated liquid density of Rl34a.

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The aqueous solution of ammonia is expected to be used as not only a working fluid for absorption refrigerator but also working fluids for a bottoming cycle of steam power plant, and other heat recovering systems. Therefore, the thermodynamic properties of this substance are required in the wide range of temperatures and pressures. The present pVTx property measurements were conducted in order to make clear the maximum density phenomena of the aqueous dilute solution of ammonia in the low temperature liquid region, and they showed the minimum pressure near the temperature 269 K along each isochore as shown in Fig.2. It is clear from thermodynamic theory that the minimum pressure state along isochoric line corresponds to the maximum density state along the isobaric line. This present study represents experimentally that the maximum density phenomena of water have influence on the similar property behavior for the aqueous dilute solution of ammonia.

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This paper deals with the measurement of quantities of gases such as nitrogen and carbon dioxide that penetrated through a rubber sheet into mineral oil by the means of combination of manometer and laser heterodyne interferometry. With N_2, the saturated solubility into the rubber is about equal to the one into the VG10 mineral oil, and diffusion coefficient is approximately 1/50 times smaller than VG10 mineral oil. The quantities of gas permeability of N_2 and CO_2 through rubber sheet increase with pressure and temperature.

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