Entrainment behavior on a density interface of stratified fluids is very important for the piping design of various plants. In the previous study, it was found that the dimensionless entrainment velocity was inversely proportional to an overall Richardson number. This tendency was derived by the turbulent energy released from the energy-containing eddy was proportional to the energy consumption by the entrainment. In the present study, the tangential injection made the horizontal eddy above the density interface. The entrainment is done by the tornado formation by the horizontal eddy. The entrainment velocity by the horizontal eddy was compared with the model of the turbulent energy consumption by the entrainment. The effective entrainment behavior was obtained with the horizontal eddy.

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A micro wire-mesh sensor (μWMS) based on an electrical conductivity measurement was developed for gas-liquid two-phase flow measurement in a narrow channel. The measuring method applies a principle of conventional wire-mesh tomography, which can measure the instantaneous void fraction distributions in the cross-section of the flow channel. In μWMS for narrow two-phase flow, the electrodes are fixed on the inner wall of the narrow channel, and the local void fractions were obtained by the electrical conductivity measurement between electrodes arranged on each wall. Therefore, the flow structure and the bubble behavior can be investigated in the channel with narrow gap. In this paper, a μWMS between parallel flat plates was developed for measurements of instantaneous void fraction distributions. The measured results were compared with high speed camera images, and three-dimensional bubble distributions were reconstructed from the void fraction distributions.

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To assess the stability of advanced light water reactors or steam generators in FBR, JAEA has been developing a prediction method for thermal-hydraulic instability based on system analysis code TRAC-BF1. In the present paper, thermal-hydraulic instability experiments were analyzed with TRAC-BF1 code and the applicability of the code for thermal-hydraulic instability was estimated. The heat flux of the boundary between stable and unstable region is in agreement with the experimental data within about 10% of error. The onset of instability can be predicted with TRAC-BF1.

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Japan Atomic Energy Agency (JAEA) develops three dimensional two-fluid model analysis code ACE-3D that adopts boundary fitted coordinate system in order to simulate complex shape flow channel. In this paper, boiling two-phase flow analysis in a tight-lattice rod bundle was performed by ACE-3D code, and predicted pressure loss was compared with experimental result. The predicted friction pressure loss was underestimated around 20% of measured values, and the effect of the turbulence model is considered as one of the causes of this underestimation. To evaluate effects of two-phase flow model used in ACE-3D code on pressure loss, numerical simulation of boiling two-phase in tight-lattice rod bundle with no lift force model was also performed. In the results, the prediction accuracies of the pressure loss improve by considering the lift force.

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Recently two-phase flow in microchannel has attracted attention, so gas-liquid two-phase slug flow has been investigated actively. But the flow pattern has been measured by void fraction in previous studies, so slug lengths have not been investigated very much. In this study, to control slug lengths at different situation of downstream we made slug flow by T-junction, and measured slug lengths and its variances at pair of different positions on tube, different length of tubes, different diameter of tubes, and different surface tension of liquid, hi experiments we used N_2 gas (18〜80 kPa) as gas phase and H_2O (2.00 〜 20.00 μl/min) and SDS-water solution as liquid phase. SDS is one of general surface-active agents. Gas and liquid phase are commingled at T-junction. And we measured slug lengths from time-series images observed by high speed video camera. We used 74 and 102 μm across glass tubes at observed place. In this study, the difference of diameter of the tube is the best influence parameter over slug lengths.

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The photoresist stripping process in photo lithography plays an important role in manufacturing large-scale integration. In the present study, experimental information is obtained to establish high concentrated ozone water technology for stripping the photoresist, in stead of chemicals such as sulfuric acid or hydrochloric acid. We examine flow structure between disks for the sake of improving removal rate of photoresist using flux between disks. A radial flow velocity and a rotational flow velocity are obtained by visualization of a flow in a narrow gap between disks. Flow structure is compared with a quantity of removed photoresist by using high concentrated ozone water. It is considered that removal rate of photoresist is affected by ozone water flow structure.

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In general, when the high temperature circular or rectangular channels are cooled by forced convection of gas, there are several methods for enhancement of heat transfer such as attaching radial or spiral fins on a channel surface or inserting twisted tape in a channel. The objective of this study is to investigate heat transfer characteristics by forced or natural convection of porous materials inserted into a rectangular channel with high porosity. In order to obtain the heat transfer characteristics of the one-side heated vertical rectangular channel inserting the porous material, an experiment was carried out. From the results obtained in this experiment, it was found that an amount of removed heat by forced convection using porous material (porosity > 0.996) was about 10% higher than that without the copper wire. Furthermore, the ratio between the amounts of heat removed of the rectangular channel with the porous material and without the porous material increases with increasing temperature of the channel wall.

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Critical heat flux -CHF- on subcooled flow boiling under vibration conditions, focusing on liquid velocity, acceleration and frequency of vibrations was investigated experimentally. Experiments were conducted using a copper thin-film and subcooled water in a range of the liquid velocity from 0.3 to 3.9 m/s at O.lOMPa. The liquid subcooling was 20K. The acceleration was 0.4, 1.3 and 4.15 m/s^2, respectively; the frequency was 2, 4 and 20 Hz, respectively. The vibration directions were horizontal and vertical to orientation of the heater. The present experimental results showed that critical heat fluxes under the vibration conditions of both vibration directions, i.e., horizontal and vertical vibrations to the heater, were higher than those for steady flow. The CHF under the vibration condition was increased with an increasing of acceleration of vibration. According to present observations, coalesced bubble on the heater was frequently released by vibration of the test heater: the characteristic length of coalesced bubble decreased. This behavior caused the CHF to become higher under the vibration condition.

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Homogeneous Charge Compression Ignition (HCCI) combustion has attracted considerable interest in recent years as a new combustion concept for internal combustion engines. The HCCI combustion process has four issues to be resolved: ignition timing control, slower combustion (maximum heat release rate), difficulty expanding stable operation to the high load region and avoidance of knocking. In this study, an attempt was made to overcome these issues by using double componential fuels. Absorption spectroscopic measurement was made in the combustion chamber in order to investigate low-temperature reactions in detail. As the result, by using double componential fuels, the ignition timing can be controlled and the rise of combustion can be slower.

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The progress of flame propagation and the autoignition behavior of the end gas at the time of knocking in a spark-ignition engine were examined on the basis of emission and absorption spectroscopic measurements and visualizations obtained by high-speed photography. The test fuels used were a 30 RON fuel and n-heptane. Emission and absorption spectroscopic techniques were applied to investigate the behavior of formaldehyde (HCHO) and OH radicals in the interval from the occurrence of a cool flame to autoignition. The results showed the occurrence of cool-flame reactions along with light absorption and faint light emission ascribable to HCHO in the end gas prior to knocking.

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Systems with closed side-branches are liable to an excitation of sound, as called cavity tone. In this study, flow-induced acoustic resonances of piping systems containing closed side-branches were investigated experimentally. The present investigation on the coaxial closed side-branches is the first rudimentary study to measure the pressure at the downstream side opening of the cavity by microphone and to visualize the fluid flow in the cross-section by using PIV. High-time-resolved PIV has a possibility to analyze the velocity field and the relation between sound propagation and flow field. The fluid flows at different points in the cavity interact with some phase differences and the relation can be clarified.

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It is important to advance safety and efficiency of the fast breeder reactor (FBR). A numerical prediction method of high accuracy and its validation with a simulated thermal flow field are indispensable. A wire-wrapped rod bundle system, which briefly simulated the fuel rods system in FBR, was built up in the experiments. The wire wrapped rods were made from Mexflon-material, of which refractive index was exactly same with that of water. The particle image velocimetry (PIV) was applied to measure the velocity field in the rod bundles, with variable flow rates and the temperature conditions. The aim of this study was to contribute to the certification of results of numerical simulation for the safety design of the FBR.

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Recently, the distance between an elbow and a flowmeter in a flow loop is reduced because industrial plants are more and more compact. The performed velocity profile is caused by an elbow. In this case, error of flowmeter may be generated. To estimate the error of measurement by ultrasonic flowmeter downstream of elbow, this study investigated the velocity distribution downstream of elbow by using PIV and numerical analysis. As a result, the error was small after the distance x/D=20 from elbow.

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A micro-grooved evaporator is one of the promising heat transfer devices with high evaporation and heat transfer performances by actualizing an interline region at a contact line in a groove meniscus. To obtain the high heat performance of this evaporator, the inter line region should exist on a heat transfer surface in high density. In this paper, the heat flux of micro-grooved evaporator with parallel grooves for several depths and widths of groove was measured. The measured value for single groove shows around 25% of the results calculated by numerical model. In addition, the optimal pattern of grooves on a micro-grooved evaporator using ethanol as working fluid was proposed. The heat performance of optimal evaporator was calculated using the results of heat flux and capillary-rise length for a single groove. The maximum heat flux of optimally patterned micro-grooved evaporator was calculated as 0.5MW/m^2 at super heat of 6K.

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At present, a microchannel heat exchanger is requested to achieve high efficiency in small size energy equipment. In order to clarify the heat transfer mechanism in a microchannel heat exchanger, knowledge on the thermal hydraulic characteristics of condensation flow in channels is essential. However, study on characteristics of condensation flow in a microchannel is hardly conducted except visualization of flow patterns. Objectives of the present study are to estimate the heat transfer performance of the present device and to clarify the thermal hydraulic characteristics of condensation in a capillary tube by observation of condensation behavior. As the results, it is confirmed that the microchannel heat exchanger has quantity of heat exchange of 7 kW when steam condensation occurred. In a single capillary tube as simulated unit microchannel, the flow pattern is transferred from the annular flow to bubbly flow through injection flow in a capillary tube.

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Micro gas turbine systems have been developed as a portable power supply. In this study the utilization of kerosene spray with pre-vaporized system for the micro gas turbine combustor was tested. Characteristics of the model combustor of micro gas turbine were investigated experimentally. Twin fluid atomizer was used for the fuel spray formation. An extension tube was set at the exit of fuel injector for the enhancement of pre-vaporization. The effect of the extension tube on flame stability was discussed. As a result, the blow off limit became wider when the extension tube was set at fuel nozzle exit.

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An engineering-model of hydrogen-fueled flat-flame ultra-micro combustor with a combustion chamber volume of 69.4 mm^3 was developed. To obtain high overall heat-insulation, heat-resistant and strength, the engineering-model combustor had a triple layer structure with an advanced ceramic, a heat insulation material and a stainless steel. The burning test of the combustor showed that it was easy to ignite and burn with a stable flame. Both the stable flame region and the ignition limit were enough wide to satisfy the design operation point of the combustor. The engineering-model combustor attained high combustion efficiency and high space heating rate of 7300 MW(m^3・MPa) with pressure loss around 5%. NOx concentration of the combustor was enough low of less than 3 ppm. While the combustor had good combustion characteristics, the heat loss ratio was high of 51 % of the heat release and the combustor had a large heat capacity. The heat transfer at the exit slit must be reduced and the combustor wall must be thinner.

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A micro-scale catalytic combustor using high-precision ceramic tape-casting technology has been developed for high-temperature applications such as thermophotovoltaic power generation. Pd catalyst/nanoporous alumina support fabricated through anodic oxidation was employed for the catalyst layer. Combustor structure that gives much smaller temperature gradient with high fuel-conversion efficiency has been proposed based on a series of CFD analysis of heat and fluid flow and surface reaction. In combustion experiments with a prototype combustor, the wall temperature as high as 700℃ has been achieved. It is also found that the wall temperature gradient is significantly reduced with the present combustor structure.

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This paper describes the design and characteristics of a tape-type radial foil bearing for ultra-small gas turbine generators. A tape-shaped foil made of stainless steel (SUS304) is wrapped three times around a rotor, and then fixed in a housing. The outer and middle coil segments of the foil have some etched grooves so that they deform as leaf spring shapes in the housing. These springs support the inner coil segment of the foil, i.e. bearing foil, elastically. We designed the bearing geometry, and theoretically estimated the stiffness of the foil spring. We also measured the stiffness of the foil spring, and confirmed that the calculated and measured values fairly matched. Using the obtained stiffness, pressure distribution in the bearing clearance was simulated by divergence formulation (DF) method. Based on this result, we designed and produced a tape-type radial foil bearing test rig with a Ti-6Al-4V rotor of 8 mm in diameter. The test rig stably rotated at 430000 rpm, which was limited by the performance of the turbine.

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A prototype flexible Joule-Thomson micro-refrigerator was fabricated and its cooling power was examined. The micro-refrigerator uses N_2, C_2H_4, CO_2 as a working gas and it consists mainly of heat exchanger (The outside diameter of outer tube is 0.9 mm and that of inner tube is 0.4 mm. The length of the heat exchanger is 450mm) and evaporator (The inner diameter of the capillary is 0.1 mm). The cooling power of 100 mW at evaporator temperature of 277 K was attained at the inlet and outlet gas (CO2) pressures of 5.0 MPa and 0.1 MPa, respectively. To understand the cooling performance, numerical analysis of heat exchanger has been done and the effects of mass flow rate and dimension of heat exchanger on temperature profiles and effectiveness were examined.

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A vibration-driven electret generator has been developed. By using parylene as the spring material, a low-resonant-frequency MEMS generator is realized. Large in-plane amplitude of 0.5 mm at the resonant frequency as low as 21 Hz has been achieved. Electrostatic levitation is adopted for the gap control. Electrostatic repulsive force is stably induced with translational and rotational alignment error of 1.2 mm. With our early prototype, we have obtained output power of 0.375 μW.

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In order to improve the output performance of PEFC, it is important to investigate the two-phase condition in gas diffusion layer (GDL). In this study, the simulated GDL structure was developed by numerical analysis including the random orientation of carbon fibers and binders. And detailed structural estimation was carried out. As structural properties, pore size distribution, electrical resistivity and tortuosity were calculated, and these values almost agreed with actual measurement values. Furthermore, our past two-phase network model was improved, and the model based on an actual structure was developed by a direct 3D networking porous structure. And the influence of GDL structure on the two-phase condition with accumulated water was evaluated, and effective diffusion coefficient of oxygen in GDL with liquid water was calculated.

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This paper demonstrates numerical simulations of droplet on the gas diffusion layer of the polymer electrolyte fuel cell. The lattice Boltzmann method for incompressible two-phase flows at high density ratios were applied for the simulations in order to precisely predict the shape and moving velocity of water droplet surrounding by the air in the gas channel. Simulations were conducted in 2-D and 3-D and height and moving velocity of droplet were compared with experiment as a function of mean gas velocity in the gas channel. The droplet heights by the simulations were qualitatively agreed with the experimental data, while the simulation results of moving speed of droplet somewhat overestimated the experimental results.

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Polymer electrolyte fuel cell (PEFC) has advantages because of less environmental impact and high system efficiency. It is expected to use many applications such as fuel cell vehicles, residential fuel cell systems. However, there are many technical problems to overcome for the practical use of fuel cells. In particular, it is important to improve the system reliability and the stack failure diagnosis. In this study, PEFC stack performances and effects of cooling failure were investigated. From the result, voltage deviations were calculated in consideration of the Nernst loss caused by the hydrogen partial pressure loss. From the results of a cooling failure test, the plugged cell temperature increased by 8.65℃ at 33 A. The voltage of plugged cell increased on the cooling failure test, though the stack voltage dropped.

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Tokyo Gas has been aggressively developing new models of residential PEFC co-generation system "ENE FARM" since the world's first launch of the previous models in 2005. The new systems are both revolutionary and sophisticated so as to be sold as one of ordinary commodities, whereas the previous models were introduced to the limited customers in the Large-Scale Stationary Fuel Cell Demonstration Project conducted by NEF (New Energy Foundation). As of the end of FY2007, five hundred and twenty of the previous models were installed in the project, whose data and experiences during actual operation were utilized in the development of the new models. Hundreds of the new models were manufactured in FY2008, and they have been already in real operation in the project above. In FY2009, the new models are scheduled to be on sale by more than a thousand systems per year.

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Recently, much attention has been paid to the fuel cell vehicle from the viewpoint of its very high fuel efficiency and zero emission characteristics. However, there are some serious problems left associated with the luck of hydrogen refueling stations and very high costs. Thus, we have developed a very small fuel cell vehicle system to resolve these problems. The vehicle features two concepts; one is carrying hydrogen cartridges to easily be replaced with fully charged ones, and the other is an inexpensive single seated small vehicle utilized based on a car-sharing system. High efficiency and sufficient vehicle performance have been demonstrated through chassis dynamometer tests and car-sharing tests in Honjo areas.

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In the hydrogen energy system, polymer material will be widely utilized as functional material. Rubbers are utilized as sealing material at the joint between pipings. Polymer electrolyte membranes are utilized as ionic conductor and as the partition between electrode. A farther performance for the polymer materials is required because the present polymer material has a permeability to hydrogen, which can not be negligible, resulting in the lower durability of it. We are fabricating an equipment, which can measure the hydrogen solubility and diffusivity in polymer material; these physical data obtained will be available for designing the material itself and hydrogen system. This equipment captures the hydrogen molecular properties with receiving the signal from a small NMR-sensor inserted in the polymer sample surrounded in a pressurized hydrogen-gas atmosphere. Here, the test measurement of the NMR signal for H2O/D2O mixture solution is shown.

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It is important to reduce the diffusion polarization at high load conditions for achieving higher performance in direct methanol fuel cell. This research applied stainless steel porous media to the flow field of a direct methanol fuel cell, and experimentally analyzed their effects on the cell performance. Two types of porous flow fields were tested and compared. The results show that a sintered spherical porous stainless steel flow field exhibited a very high effect of performance improvement which exceeds the DMFC development target set by NEDO. Diffusion polarization was especially decreased by the porous flow fields.

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This paper refers to the experiments of the direct ethanol utilization in a polymer electrolyte fuel cell. A small-scale direct methanol fuel cell, which consists of Nafion^[○!R」 112 membrane and Pt-Ru catalyst, was employed. Ethanol solution was directly supplied to the cell instead of methanol. The fuel cell was put in an incubator, and the temperature was kept constant during the experiment. The relationship between the current and the voltage was measured, and the power-current characteristic was also estimated. It was found that the direct ethanol conversion proceeded in the fuel cell. However, the terminal voltage and the power density were quite small, comparing to other fuel cells. In addition, the effects of the temperature and the ethanol concentration on the power generation performance were evaluated.

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The object of study is to separate and recover fuel constituents from anode exhaust gas of Solid Oxide Fuel Cell (SOFC). To achieve this object a system with Metal Hydride (MH) is proposed. The MH used in the system has the chemical formula of LaNi_<4.O8>Al_<O.92>, which is a kind of material can absorb selectively and preserve hydrogen. In the experiment MH was used to recovery hydrogen from the gas. The gas composition was calculated from SOFC fuel utilization. It suggests that the recovery rate is proportional to the ratio of H_2 in mixed gas. And it has been confirmed that poisoning of MH by H_2O.

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The scheme of calculating SOFC anode polarization based on electrochemical local equilibrium is proposed. The simulation uses three-dimensional structure, which is reconstructed from cross sectional images of Ni/YSZ cermet anode. The cross-sectional images are obtained by a dual-beam focused ion beam-scanning electron microscope (FIB-SEM). Gaseous, ionic and electronic transport equations, and the electrochemical reaction at three-phase boundary (TPB) are solved using the Lattice Boltzmann Method (LBM). In the LBM, the gas mole fraction, electron and ionic electrochemical potential distributions are considered. Gas transport is modeled using the Dusty Gas Model (DGM). The numerical simulation is performed under 0.7A/cm^2. This numerical method is considered to be a promising tool for predicting SOFC electrode polarization.

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In this paper, the dynamic characteristics of a single tubular solid oxide fuel cell were discussed. The single cell was put vertically inside an electric furnace, and the operating temperature inside the furnace was kept constant during the experiments. Hydrogen, nitrogen and steam mixture was supplied to the anode side channel. Air was supplied to the cathode side of the cell tube. The transient responses of the terminal voltage to the electric current reference value change were measured. Throughout the experiments, it was found that the cell voltage responds quickly to the current change. The effect of the fuel utilization, i.e. fuel flow rate, on the voltage response pattern was not remarkable. In the case of the constant fuel utilization, the fuel flow rate was changed during the current change. This type of the fuel supply operation causes the response delay of the cell voltage.

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A proton-conducting anode Ni/GDC(Gd_2O_3-doped Ce0_2)-BCY(BaCe_<0.8>Y_<0.2>O_<3-α>) has been proposed for a high power density Solid-Oxide-Fuel-Cell. The most striking feature is that, using the anode Ni/GDC-BCY(90%:10%), the polarized resistance which indicates an overpotential in anode is reduced to the half of that of the conventional anode Ni/GDC. As a result of our measurement, it is likely that the amount of adsorbed hydrogen on the surface of BCY is five times higher than that of GDC. It is clarified that adsorbed oxygen which is transferred as oxide ions through GDC particulates has large chance to react with the adsorbed hydrogen since much amount of hydrogen might be adsorbed on the surface of each BCY particulate distributed in the anode.

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In this paper, the reaction rate of methane steam reforming over anode material was estimated to obtain the fundamental data for the analysis and the design of a solid oxide fuel cell (SOFC) with direct internal reforming. The cermet of Ni and yttria-stabilized zirconia (YSZ) was applied for the anode of SOFC. In the experiment, Ni/YSZ was used as a catalyst for methane steam reforming. The volume ratio of Ni to YSZ is 60% to 40% and the particle size was below 300 μm. A small tubular reactor, which was put inside an electric furnace, was employed, and the Ni/YSZ powder was put inside the reactor. Methane and steam mixture was supplied into the reactor. The composition of the dry gas after reforming was measured with a gas chromatograph equipment. Based on the experimental data, the turnover rate of methane was estimated. In addition, the pre-exponential factor, the activation energy and the reaction order were calculated, and therefore the reaction rate equation was obtained.

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In the present study, we reveal the dominant chemical reactions and the optimum conditions, supposing the design of ethanol steam-reforming reactors. Experiments are conducted for Cu/ZnO/Al_2O_3 catalyst. Using a household-use-scale reactor with well-controlled temperature distributions, we specify the effect of T upon concentrations such as C_<H2>, C_<CO2>, C_<CO> and C_<CH4>. Furthermore, we compare experimental results with chemical-equilibrium theories. As a result, the Cu/ZnO/Al_2O_3 catalyst shows rather high performance at low values of reaction temperature T. This suggests that the Cu/ZnO/Al_2O_3 catalyst promotes the ethanol-steam-reforming and water-gas-shift reactions, but doesn't promote the methanation reaction. In addition, we have revealed the influence of liquid-hourly space velocity LHSV upon the ethanol conversion X_<C2H5OH>at in the range of LHSV from 0.05 to 1.40h^<-1>, at S/C = 3.0 and T= 420K, 470K and 520K, together with the influence of LHSVupon C_<H2>, C_<C02>, Cco and C_<CH4> at T= 470K.

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In a system composed of photovoltaic (PV) modules, water electrolyzers and fuel cells, the oxygen generated by electrolysis of water isn't often used. This paper focuses on the oxygen utilized for water purification, e.g. increasing dissolved oxygen (DO) level in a eutrophied lake, which will add value to the system. The purpose of this research is to estimate the system feasibility. It was found that maximum power point tracking (MPPT) control in the system was not necessary, judging from 87.1% of the annual average efficiency of the oxygen generation and PV energy production in the system without the control. Numerical analysis of DO behavior in Lake Kasumigaura, located in Ibaraki prefecture in Japan, using an ecosystem model was performed based on the observed data. The results show that the model approximately reproduced the temporal of the water quality observed in the field.

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In order to clarify an aerodynamic performance of Magnus wind turbines with spiral fins, wind tunnel experiments and numerical simulations were conducted. The results show that the ratio of lift and drag, L/D, depends on the rotational ratio of η. The maximum L/D of the rotational cylinder with spiral fins was obtained at lower η than that of the cylinder without spiral fins. Therefore, the power for the cylinder rotation can be reduced with the spiral fins. The effective performance was provided at the fins angles around 35 degrees. The simulation results showed the spanwise flow can be observed on the surface of the spiral fins. The power coefficient of the Magnus wind turbines depends on the spanwise velocity on the surface. It revealed that the control of the spanwise flow with spiral fins play an important role in the performance of Magnus wind turbines

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The conventional small wind turbines designed for high tip speed ratio have lower performance at low wind speed region. Therefore, it is necessary to design the small wind turbine for lower tip speed ratio to attain the higher performance in the low wind speed. The authors proposed a small wind turbine with low tip speed ratio and tested it in a wind tunnel. It was obvious that the tested wind turbine has good power coefficient even in lower wind speed ranges and has low noise. This new wind turbine and PV panel are combined as a small hybrid power source named as WISH (Wind and Solar Hybrid) Box. This system is useful as the stand-alone power source, especially in developing countries.

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Influence of sectional shape on power characteristics of open cross flow type micro water turbine was investigated by model experiments. An increase of number of blades caused improvement of turbine efficiency. Ratio of inner diameter to outer diameter of a turbine hardly influences on turbine power characteristics. Efficiency of large turbines was higher than small ones. Following two effects were confirmed by field tests. (1) Scale effect: Efficiency obtained by field tests using a turbine with a diameter of 1.2m was higher than model tests. (2) Suppress effect of overload: Maximum generated power showed a tendency to be suppressed for a condition supposing over discharge.

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A velocity fluctuation can occur due to an interaction between a flow passing through the guide vanes and the flow running into the runner vane, resulting in a vibration of turbine and a blade cracking, especially in the hydraulic turbine which is operated in a wide range. High time-resolved velocity data can help to clarify the mechanism of the interaction and to provide good experimental data for the validation of numerical data. The unstable velocity field between rotating and stay vanes was measured quantitatively by using the high time-resolved particle image velocimetry (PIV).

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The Japanese wind power is now being watched with interest of the world, because the national target of wind energy is 3000MW that was proposed in the Primary Energy Supply Plan. It is possible to contribute environmental management, economic activation, employment measures and energy security. Therefore, we must give careful consideration to durability, safety and a pollution problem. This paper is introduced about remarkable wind technology (wind prediction, wind turbine system, operation control system, power generation system, soft tower, stable supply) in Japan.

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A variety of investigation researches are done to the introduction promotion of the pinwheel about the thunder harm damage that is one of the obstruction factors now and the pinwheel lightning measures examination is done. It is the one to arrange the lightning damage situation to the pinwheel of current our country including an overseas case, to do consideration based on the observational data concerning current lightning to the pinwheel as a lightning protection measures of the wind power generation equipment, and to contribute to a help of the performance gain of the wind power generation equipment.

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As of the end of 2007, wind power capacity became close to 94 GW all over the world. The United States, Spain, China and India recorded high increase of wind capacity last year. As to Japan, wind turbines have been suffering from typhoon attacks, lightning aggacks and high turbulence, which have acturally decelerated wind power development today. For example, in 2003 Miyako Island was attacked by a huge typhoon when all seven wind turbines were damaged or destroyed by the typhoon, with three turbines hit down to the ground, other threr lost blades. The keenest issue we are asked today is to develop "J-class wind models" which describe the characteristic of extreme winds in Japan in the same manner of IEC standard. The first approach is to study the past observed wind data. Considering meteorological and geographical conditions over Japan, statistical data were chosen at 50 meteorological stations out of 160. The value of Vref/V_<ave> and Ve50/Vref are higher than the IEC standard level. In this study, we developed typhoon simulation tools, and estimated Vref and the uncertainty of Vref at met-station in Japan using typhoon track data for past 50 year.

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Information from the wind tunnel experimental data that considered topography shape, ground roughness, turbulence intensity is important to use the numerical analysis simulation result like wind energy assessment. In this research, the flow field is analyzed when inflow velocity distributions with different turbulence intensity give for two-dimensional hill model for improvement of wind energy prediction accuracy and get the data that it is necessary to constract a high accuracy wind energy prediction model.

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In recent years, photovoltaic (PV) systems have been installed rapidly in the world. However, there is delay in the practical application of fault detection for PV systems. In this study, the temperature of bypass diodes (BD) mounted on P V modules was measured for simple and practical fault detection. The temperature of the BD of Module 31 was higher than other modules and a large current passed through one of the BD. Measuring a BD temperature is easier than conventional methods. It is possible to detect failure without a system shutdown. Moreover, we tried to evaluate the distribution of temperature of terminal box using the heat conduction equations. The evaluated results agreed approximately with measured results.

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An ammonia/water as working fluid is used for the ocean thermal energy conversion system (OTEC) to decrease an irreversible loss in heat exchangers. And this fluid is expected to improve the system performance. It is important to clear the characteristic and the true evaluation of heat exchanger in OTEC ststem. Therefore, it is important that the clarification of characteristic in heat exchangers. At this time, logarithmic temperature difference (LMTD) method that is limited when considered that physical properties of fluids are constant is used for the performance evaluation in heat exchangers in OTEC. Then, a generalized mean temperature difference (GMTD) method that can consider the change of the physical properties value of fluids is introduced into the evaluation of characteristics of heat exchangers that uses ammonia/water in this paper. GMTD was introduced into the evaluation of heat exchangers of OTEC using ammonia/water and the influence given to the evaluation of the characteristic, effectiveness, and system characteristics was clarified.

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An Ocean Thermal Energy Conversion (OTEC) is one of the renewable energy. Concerning an improvement on performance of OTEC system, a working fluid flow rate is one of the important operating conditions. On the OTEC system using ammonia/water mixture as working fluid, the effect of the working fluid flow rate has never been clarified. So this paper describes the effect of the working fluid flow rate on the system. As a result, a maximum net turbine power of 15.6kW is obtained at warm and cold water flow rates of 400m^3/h and working fluid flow rate of 6t/h. The characteristic turbine power output was found strongly dependent on the evaporator outlet pressure. So the reduction of the pressure drop between outlet of evaporator and inlet of turbine expected to improve the system efficiency.

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This work is a study on the Characteristics of the two phase screw expander. Screw expander will demonstrate a beneficial effect as new power recovery system from a low quality mixture like a geothermal fluid. It is important to make clear the influence of design conditions such as Built in Pressure ratio and operating conditions such as Quality, Rotor speed and Pressure ratio to a total system efficiency called the adiabatic efficiency. In this report, the adiabatic efficiency is divided into the theoretical efficiency, the volumetric efficiency and the diagram efficiency and evaluate the contribution of each conditions.

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A novel method for measuring wall thinning of pipes using the circumferential (C-) Lamb waves was proposed. The C-Lamb waves were generated and detected by noncontact air-coupled ultrasonic transducers (NAUT) that were extremely useful for ISI because of the non-contacting nature. In the method, wave-packets of multiple-turnaround C-Lamb wave are overlapped and interfere themselves when the number of tone-burst cycle takes large enough. Amplitudes of the overlapped signals are determined by the relative differences of phases of all the wave-packets overlapped. When the group velocity of the C-Lamb wave is changed due to pipe wall thinning (the dispersion relation change), amplitude of the overlapped signal is also changed in principle. In the proposed method, the wall thinning can be detected by measuring the frequency of the C-Lamb wave in the case of taking the maximum overlapped amplitude because the amplitude is also changed as a function of frequency of the C-lamb wave. The principle and verifications of the method were shown.

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