Aiming at reduction of the energy consumed in domestic and business use, research of an energy system corresponding to ZEB/ZEH (Zero Energy Building/House) is advanced. The authors are developing a hybrid heat source Stirling engine CHP (combined heat and power) system, which uses solar and woody biomass. This paper describes a basic solar Stirling engine power generation system only with solar energy. The system has a solar tracking type collector which is made by a Fresnel lens. The performance testing which improved heating method in a heater side for characteristic evaluation was conducted, so that about 14 W of electric power output of the Stirling engine generator became possible. However it's lacking in thermal energy collection by the Fresnel lens, also the heating in the heater side of the Stirling engine generator is not enough in direct-heating.

An external combustion engine such as a Stirling engine has low output response and can not cope with sudden load variation. In order to put the external combustion engine into practical use in the field with heavy load fluctuation, a transmission that compensates for the weak point of the external combustion engine is necessary. In this research, we will produce a car using the indirectly driven transmission we devised and verify how much capacity of Stirling engine can be drawn out

Thermoacoustic devices are expected to be put into practical use as low-cost and long-life waste heat utilization technology. In particular, 4-stage thermoacoustic cooling system is expected to be driven at low temperature. However, sufficient research has not been done at present. In this research, two kinds of 4-stage devices with different number of thermoacoustic engines and refrigerators were compared by numerical calculation ;one model has three engines and the other has two engines. It was found, both models can be driven at lower than 200°C. Furthermore, 3-engine model can be driven at a lower temperature, while 2-engine model has higher refrigeration capacity.

In recent years, offshore floating type wind turbines that can be installed in waters where the water depth exceeds 50 meter have been paying attention. Almost all large wind turbines for power generation are horizontal axis wind turbine with wing nacelle (generator, gear) and tower, wings and nacelles occupying heavy weight among the three elements are on the top of tower therefore turbine having a top heavy structure. When considering that cost reduction of wind power generation is achieved by enlarging the wind turbine, then stability will become a problem in case of floating type. The wind turbine has a type in which the axis connected to a generator vertically is called a vertical axis type. The power generation efficiency is inferior to that of the horizontal axis type, but it does not require direction control, and it also features the ability to install heavy electric generators and gears at the bottom. In the case where the floating offshore wind turbine is enlarged in size, this feature is advantageous in terms of stability. This study aims to clarify the influence of wave and tidal current fluctuation when a vertical axis type wind turbine is used as a floating offshore wind turbine. In the case of a horizontal axis type wind turbine, it has already been reported that the output decreases as the wind turbine tilts. In the case of a vertical axis type windmill, we tried to clarify the effect of the wind turbine being tilted by the model experiments. The results shows output of tilted vertical axis wind turbine is little increase.

Bi-directional flow is generated in wave energy plant with oscillating water column and in thermal acoustic engine. Turbine for bi-directional flow has been used in such devices and they rotates in the same direction. Some turbines for bidirectional flow were proposed, and their performance were investigated by wind tunnel test and CFD analysis. Typical turbines have some inherent disadvantages such as severe stall and low efficiency. Therefore, the authors proposed two unique turbines for bi-directional flow: Wells turbine with booster and counter-rotating impulse turbine. An extensive numerical works were conducted to perform a comparative study between the conventional and proposed turbines.

A straight-bladed vertical axis turbine for wave energy conversion has been proposed in order to develop a novel air turbine suitable for oscillating water column based on wave energy plant. The objective of this study is to show the effect of guide vane on the performance of straight-bladed vertical axis turbine. The experimental study was carried out by a wind tunnel. The rotor has four straight blades with a profile of NACA0018, a chord length of 80.5 mm, a pitch diameter of 460 mm and a blade width of 490 mm. Further, flows around the proposed turbine have been investigated by use of MPS (Moving Particle Semi-implicit) method. The guide vane has a profile of circular arc and a chord length of l = 87 mm. The distance between the guide vanes w and number of guide vanes n are changed in order to investigate the effect of guide vane solidity λ = l / w. We found that the number of guide vanes n and the guide vane solidity λ suitable for the proposed turbine are obtained in the case of n = 2 and λ = 0.829. We calculated flow visualization by the MPS method. Moreover we have confirmed the control of flow separation by the setting of the guide vane.

For the evaluation of the heat engines, the thermal efficiency is commonly applied in the power plants. However, the maximization of the thermal efficiency do not lead the maximization of the available power output from OTEC, which converts into the work from the finite thermal energy stored between different temperature seawaters. The maximum work efficiency based on the theoretical maximum work from the ideal heat engine has been counseled for the evaluation, however, the implication in the available thermal energy has not identified substantially. This paper theoretically reveals the available thermal energy from the ocean thermal gradient and the effective energy, which is called the exergy, using the reference of the equilibrium temperature as the dead state. By employing the finite-time thermodynamics, the available energy and the exergy calculation methods are obtained and the normalized thermal efficiency for OTEC and the exergy efficiency are proposed.

Ocean thermal energy conversion (OTEC), utilizes the small temperature difference between the surface seawater and the deep seawater, requires relatively large heat transfer areas due to theoretically low thermal efficiency. Therefore, the optimum design method by minimizing the objective function that defined as total required heat transfer areas for heat exchangers per the maximum net power output has been employed. However, in the onshore type of small capacity OTEC system, the cost for seawater intake facility in the capital expense may be dominant. Therefore, the diminution in the capacity of the intake facility will lead lower the expense. This paper describes about the new optimum design applying the net maximum work efficiency as an element of the objective function. The results show the reduction in the capacity of total seawater flow rate against increase of total heat transfer area compared with the conventional design method.

Deep-sea observations have been conducted for the earthquake prediction through the acquisition of crustal deformation data and the influence of marine environment. Energy supply system for deep-sea observation tools is a necessity in long-term deep sea observation. There are high potential energy reservoirs and many active hydrothermal vents. Thermal energy conversion system using submarine hydrothermal utilizes two heat sources with different temperatures between submarine hydrothermal and cold deep seawater. The effective temperature difference of the working fluid is less than the heat source temperature difference due to the heat exchange between the working fluid and the heat source. This paper investigates on the influence of the heat source temperature change in the heat exchange process and the thermal characteristics of the working fluid on the system performance of the power generation system using submarine hydrothermal. The parametric performance analysis of Rankine cycle is carried out using the thermal characteristics of three working fluids. As a result, the maximum power output of water is the largest in three working fluids, followed in order by toluene and pentane. The low-temperature heat source, which is cold deep seawater, has strong influence on the maximum power output.

The longitudinal vortices flow out periodically near the intersection of the cross arrangement of the cylinder and the flat plate arranged orthogonally in the flow. We found that the longitudinal vortices are formed constantly behind the cylinder and the lift force acts on the cylinder when the cylinder moves parallel along the flat plate. Using this phenomenon, we developed new wind turbine with the cylinder blades driven by longitudinal vortex. In this study, the influence of the blade configuration is clarified. By changing the length of the cylinder blade, the region of the cylinder blade making the negative effect of the rotation is reduced and power is improved. Both maximum rotation speed and power are obtained when the blade length is protruded 15～20mm from the outer and inner edges of the ring plate. It is considered that it is the most effective length for vortex shedding generating lift force. Furthermore, the blade tip vortex is canceled by attaching the flange to the end of the cylinder blade. This operation improves the power and eases the change in the power by the blade length changes.

Oscillating flow past an automatically rotating S-shaped rotor is computationally simulated by a vortex particle method. Such a dynamic simulation for the autorotation requires non grid-based strategy. The angular velocity of the rotor is successfully updated by solving the equation of motion including a computed hydrodynamic torque on the rotor. As a result, in the case of the period of the oscillating flow being the same order as the rotor rotation, the sympathetic vibration can be observed in the angular velocity of the rotor.

Tahara Solar Wind Power Plant is a hybrid power plant of solar power (50MW) and wind power (6MW). Output of solar power plant is largely fluctuated by the amount of solar radiation. However, it is known that the fluctuation becomes small statistically by synthesized output fluctuation from many plants. Such phenomena is called smoothing effect. This paper evaluates the smoothing effect inside of a large solar power plant. Furthermore, feature of Tahara Solar Wind Power Plant is providing comparatively large capacity of wind power generation. Output of wind power plant is fluctuated by wind velocity. It is thought that correlation between amount of solar radiation and wind velocity comparatively low. Generally, smoothing effect is high when the independency of fluctuation is large. However, example of analysis of smoothing effect from solar power and wind power is not well known. This paper evaluates the smoothing effect of the total output of solar power and wind power.

The main objective of this study is to realize the Photovoltaic (PV) power generation short-period forecasting with high accuracy using the neural network predictors learned by sky image features as input to detect PV power generation abrupt change. For extracting the features correlated with PV power generation abrupt change, we segmented the sky images into clear and cloudy areas and calculated the ratio clear areas of the whole image. For estimating the PV power generation, we calculated the averaged saturation of the sky image. We clustered the sky condition based on the extracted features and constructed the neural network predictors corresponding to each sky condition. For evaluating the proposed method, the one predictor for all sky conditions as a reference method forecasts PV output. As a result, we found that the proposed method for 20 minutes ahead PV output forecasting in the case that corresponds to “cloudy”, which is defined by Japan meteorological agency, decrease 18.3 % of mean-absolute error compared with reference method.

The efficient utilization of solar energy is important issue to shift to a sustainable society. However, the solar radiation in infrared band is not converted into electric energy efficiently, and the electric power generation during nighttime is difficult. In this study, the solar energy harvesting by utilizing stacked thermoelectric generators with phase change material (PCM) has been investigated. Experiments were performed using octadecane as PCM. The harvested energy and melting-solidification behavior of PCM were discussed in relation to number of stacked thermoelectric generators. As the results, electric power generation by solar radiation during daytime, and electric power generation by solar heat energy stored in PCM during nighttime were achieved. It was found that the optimum number of the stacked thermoelectric generators for generating electric power was estimated from the condition that heat energy was stored in PCM when strength of solar radiation reached a maximum during a daytime.

This study conducted the rough assessment on the model transporting liquid methane converted by methanation of carbon dioxide with hydrogen produced by water electrolysis using electric power of large scale wind power assumed to be installed in Patagonia region in Argentina from the viewpoint of energy productivity and energy balance. It was assumed that the CO₂ for methanation was transported from both Japan where CO₂ was produced by using the methane and South America. As a result, when wind turbines in 3000 kW class of 7.81×10⁵ units were assumed to be installed, the amount of liquid methane which could be transported to Japan was 2.2 times as large as the import volume of LNG in Japan, indicating that the model had the adequate energy productivity. The energy loss of the model was 76.1 %.

This study conducted the rough assessment on the model transporting liquid methane converted by methanation of carbon dioxide with hydrogen produced by water electrolysis using electric power of 3000 kW class wind power assumed to be installed in six local area in Tokai region from the viewpoint of energy productivity and energy balance. The compressed or liquefied H₂ as well as organic hydride and ammonia conversion were also evaluated as a competitive process. As a result, the energy loss ratio of the methanation process is the smallest among the investigated processes. Since the calorific value of methane obtained by the proposed model of local energy supply chain is much smaller than the demand of large city, e.g. Nagoya, it is necessary to select the appropriate city or town as an energy supply target.

This study aims to present a road map for effective reduction in CO₂ emissions by conducting several scenario analyses with limits on the accumulated CO₂ emissions until 2050. In the analysis, several improvements were made to evaluate the influence of time variation of power generation by renewable energy which could not be considered in the conventional Hokkaido MARKAL model. The analysis results show that there is a big change in introduction technology in the home & office sector in the case with the higher CO₂ emission reduction rate. Supply of heat and electric power by cogeneration system becomes advantageous for CO₂ and social cost reduction around 2020. After 2025, however, the grid electricity cost is decreasing due to the reduction of the facility introduction price of wind power generation, and the higher the CO₂ reduction rate becomes, the higher the dependency on the grid power becomes.

The Dashidaira Power Station utilizes water discharged from its dam in such a way that a good environment is maintained for the river on which it is located. However, the large variations in the head and flow rate of the water would impede stable operation under certain operating conditions in the case of a conventional hydraulic turbine with a fixed rotation speed. To resolve this issue, we developed an adjustable-speed system for small-scale hydroelectric power plants and delivered it to Dashidaira Power Station. This system makes stable operation possible over the full range of operations by allowing the rotation speed of the hydraulic turbine to be adjusted over a wide range through the connection of a frequency converter to the output terminal of the generator. As a result, the power station efficiently utilizes water resources that have not been effectively used up to now.

There is growing demand for a stable supply of electrical power for continuous operation in factories and laboratories. Voltage drops of power grid due to thunderbolts cause serious damage to production line of precision instruments, and factory acceptance test of them. In recent year, to solve this problem, almost factories and laboratories have their own facilities such as interruptible power supply (UPS) and backup generator. However, in case of installing them, total evaluation including initial cost, reliability to compensate voltage drop, maintenance superiority and so on should be considered. To meet these requirements, Toshiba has developed and installed the large scale lithium ion battery system by utilizing SCiB^TM which is lithium ion battery cell manufactured by Toshiba. This paper describes the introduction of the characteristics such as life cycle, charge-discharge ability and safety of SCiB^TM. Also, the system configuration of installed system, operating method and expected effect on society are described.

In order to store huge CO₂ as from a thermal power plant in deep-ocean using CO₂ hydrate, CO₂ hydrate film thickness was measured under some temperature and ambient flow velocity conditions. Once the film was formed at the interface between CO₂ and water, the film thickness was measured continuously during several hours. As a result, the film thicknesses decreased with experimental temperature and ambient flow velocity increasing. Furthermore, the film thicknesses approximately maintain its initial film thickness when hydrate film formed at the interface. Thereafter, the prediction model for CO₂ hydrate film thickness was developed based on mass transfer. As a result of comparison each measured and predicted film thickness, it is clarified that the film thickness at initial stage can be predicted using the amount of CO₂ enclosed in the CO₂ concentration distribution before hydrate formation and saturation concentration of CO₂ with CO₂ hydrate. On the other hand, growth behavior of CO₂ hydrate is predicted by considering the permeation of water molecule through hydrate film. The predicted value with time indicate good agreement with measured values.

In recent years, CCS (CO₂ Capture and Storage) for mitigation of global warming has been expected which capture CO₂ from CO₂ emission source and storage it in ocean. The method using depression in seabed can be stored huge amount of CO₂ and long term covered with CO₂ hydrate films. However, knowledge of diffusion coefficient of Liquid CO₂ for water with CO₂ Hydrate films. The purpose of this study is estimated diffusion coefficient of CO₂ hydrate film. Therefore, we observed dissolution behavior of Liquid CO₂ to water under hydrate formable conditions by visualization experiment using bromophenol blue which is pH indicator. As a result, pH concentration in various CO₂-dissolving water was verified by variation of color with water including pH indicator, and saturated solution of CO₂ present pH2.9. As well as, we visualized diffusion behaviour of liquid CO₂ and compared them with calculated value of diffusion coefficient under the experimental condition. The value of diffusion coefficient was suggested as in 10^-9order.

Image classification is adopted to aerial photo of Minokamo city in order to estimating bamboo vegetation area. Firstly, the results of supervised and unsupervised classification are compared. In the case of supervised classification, even though the bamboo vegetation area is clearly distinguished, significant noise is also detected. Therefore, the unsupervised classification is better than the supervised classification in this case. For further noise reduction, object classification is adopted. Then the precision increase from 37% to 86 % due to noise reduction.

A small spark ignition combustion engine (air-cooled, single cylinder, 290 cc-displacement) is operated with a combustible gas, bio-syngas, from the autothermal fixed bed gasifier with Cedar pellet and the cylinder pressure is measured for combustion analysis. The city gas (13A) is used as the reference at the same load. The engine speed is 1,800 rpm. As a result, the thermal efficiency with the bio-syngas is higher than that with 13A. The NOx concentration in the exhaust is less than 100 ppm in any cases. The low averaged cylinder temperature should be the reason.

Biodiesel fuel (BDF) is expected to be an alternative resource for fossil fuel which could solve global warming and petroleum resource conservation problems. We proposed a dry process which has no need for washing water or waste water treatment as opposed to the conventional wet process. In the bubble strip system, gas is supplied by a gas pump propels gas through crude BDF in a gas bubbler, then the exit gas containing methanol (MeOH) vapor passes through a condenser and the MeOH is collected in a vessel. It is a closed system in which MeOH-free gas from the condenser returns to the inlet of the gas pump. In this study, we evaluated a large-scale bubble stripping unit compared with a small one to be put to practical use for purification of crude biodiesel. As a result, both units met requirements mandated by Japanese Industrial Standards for residual methanol concentration in BDF.

The boiling behavior of biodiesel fuel (FAME) can be improved by the decomposition process based on the cross-metathesis reaction with 1-hexane on Grubbs’ catalyst. The drastic reduction of catalyst cost is, however, required to develop the method to the industrial level. In this study, the influence of the amount of catalyst on the yield of metathesis reaction is examined in a column type reactor. As the result, we determined the minimum amount of catalyst for keeping a saturated composition. Secondly, we tried to recover the catalyst from a product liquid using a porous glass filter, and reuse it to the same reaction. The experimental results show that the recovered catalyst can cause the cross-metathesis reaction. However, the yield is much lower compared to that with unused catalyst.

In our previous study, about 40% of algal oil could be converted to fatty acid methyl ester by the multi-step super-heated methanol vapor method. But, the product also included 27% of free fatty acid, and its reduction has been the important subject. In this study, we tried to produce a hydro-carbon fuel from a micro-algal oil extracted by the super-heated methanol vapor method using the catalytic cracking process. The experimental results show that a highly viscous algal-oil can be converted to a mobile liquid with the reaction temperature of 340oC. The carboxyl group of free fatty acids in the algal oil was decomposed, and olefinic hydro-carbons with a relatively low acid value were obtained successfully.

This paper describes how to produce a biodiesel fuel (BDF) from the waste soup of ramen noodles, especially focused on the recovery process of the oil from a lot of waste soup. As a result, by combining a semi-transparent bucket with a cock which capacity is about 6 L and the solvent extraction, it is shown that oil can be recovered easily from 300 or over waste soup of ramen noodles. About energy profit ratio (EPR) analysis, EPR will become more than 5.2, and the initial cost analysis, the price of bucket is about 1600yen which is little effect on the price of BDF produced from oil in the waste soup of ramen noodles. And it is shown that an increase of the running cost to produce BDF from this method is about 2.3 yen/L if the rate of recovery of hexane is over 99%, which is enough low compared with the production cost of the previous waste-cooking-oil BDF.

Liquefaction of waste plastic is a one of chemical recycling technology. Especially, catalytic cracking system with spent FCC catalyst gives higher yield and higher quality oils than pyrolysis process. The granulated blast furnace slag (GBF slag) contains mainly SiO₂, Al₂O₃ and CaO that is similar with zeolite in FCC catalyst. In this study, GBF slag was used for catalytic liquefaction as alternative spent FCC catalyst and dechlorination from poly vinyl chloride. The GBF slag gave intermediate products of spent FCC catalyst process and pyrolysis that is different of other acid and neutral materials. The chlorine in polyvinylchloride was trapped in GBF slag as inorganic chloride material.

In this study, experimental modal analysis system for evaluating modal characteristics of piping has been constructed by combining experimental setup and MATLAB programming. The experimental setup could monitor piping vibration produced by hammering. The MATLAB programming could identify such modal characteristics as natural frequency and modal damping ratio from the vibration data obtained by the experimental setup. The constructed experimental modal analysis system was applied to stainless steel pipes with different wall thickness, and the modal characteristics available for the evaluation of uniform wall thinning of the pipes were discussed by comparing the relationship between the pipe wall thickness and the modal characteristics. It was found that the modal damping ratio of mode 1 was promising parameter for the evaluation of the pipe wall thinning.

In this study, characteristics of liquid film flow and mass transfer were experimentally investigated in a downward annular flow system with two-phase flow of air and water. The liquid film thickness was evaluated by laser induced fluorescence, and the mass transfer was measured by the plaster dissolution method. The experiments were carried out in the vertical straight pipe flow with and without orifice at Reynolds numbers for liquid-film of 230, 470, 710 and 950, which were evaluated based on liquid film thickness and bulk velocity. The experimental results revealed that the mass transfer coefficient in the two-phase flow was higher than that in the single-phase flow at the same Reynolds number due to the influence thinner liquid film and boundary layer. The non-dimensional mass transfer coefficient behind the orifice in the two-phase flow showed a decrease in the peak value with decreasing liquid film Reynolds number, thought the distribution was similar to that of the single-phase flow.

Thermal fatigue cracking may initiate at a tee pipe where high and low temperature fluids flow in. The mixing flow causes temperature fluctuation near the pipe wall and may result in fatigue crack initiation. In this study, flow pattern at the mixing tee pipe was investigated by experiments in order to prevent the thermal fatigue. Visualization of flow was conducted by a test section of transparent acrylic resin and a tracer method. This test section is consisted of a horizontal main pipe with an inner diameter of 150 mm and a vertical branch pipe with an inner diameter of 50 mm. Flow in the main pipe penetrated into the branch pipe intermittently. The penetration patterns were categorized by the momentum ration for the flows in the main and branch pipes. It should be noted that the penetration of the main flow into the branch pipe might cause the thermal fatigue in the branch pipe when the fluid temperature difference in the mixing is large.

Thermal fatigue cracking may initiate at a tee pipe in plants where high and low temperature fluids flow in. The thermal stress fluctuation is caused by the wall temperature fluctuation due to heat transfer of the fluid temperature fluctuation near the wall. In order to quantitatively evaluate the flow characteristics of mixing tee pipe to cause temperature fluctuation, measurement experiments were carried out with particle image flow velocimetry (PIV) and Ultrasonic Doppler Velocimetry (UDV). A change of the velocity distribution after mixing was observed by PIV. It showed that the jet flow from the branch pipe swayed in the direction perpendicular to the main flow. We could quantitatively catch the period of fluctuation of the wall jet flow using UDV.

Creep-strength-enhanced ferritic (CSEF) steel has been used in USC plants. The creep life of CSEF steel is determined by the result of uniaxial creep test using new material. Until recently, the failure morphology of the uniaxial creep test was heat-affected zone (HAZ) fracture, which was the same as the failure morphology of the actual plants. However, in 2016, it was reported that weld metal fracture was confirmd in the failure morphology of uniaxial creep test. There is concern that the creep strength of the weld metal will decrease, but there are very few reports on the characteristics of the weld metal of Gr. 91 steel welded joints. In this study, characteristic change of the base metal, HAZ and weld metal after aging in KA-STPA28 welded joint was investigated. As a result of the study, the hardness of the weld metal subjected to aging significantly decreased compared with that of the base metal and the HAZ subjected to aging. The creep strength of the weld metal was also significantly decreased by aging. From these results, it is suggested that the creep strength of the weld metal in KA-STPA28 welded joint used for a long term may be weaker than that of the HAZ.

In 2015, re-evaluation of the long-term creep strength of the CSEF steels was once again conducted by “the Assessment Committee on Creep Data of High Chromium Steels” since additional creep test data had been accumulated as well as the knowledge and experience of CSEF steels since the previous review conducted in 2010. The new long-term data exhibited lower creep strength than that obtained from the master creep life equation for KA-STPA type steel determined in 2010, then the master creep life equation was again reviewed on the basis of the new data using the same regression method as that used in 2010. In the present paper, we review the results for base metal and welded joints of the steel.

By the thermal stress and the centrifugal force, hot gas path components of gas turbine such as combustion, bucket and nozzle are damaged during long time operation. Recently, as hot gas path components have been frequently subjected to not only creep damage but also fatigue damage, new technique for evaluating fatigue damage is demanded. In this paper, we studied the effect of material degradation on low cycle fatigue life of materials used for bucket of the gas turbine. As the result, in the temperature condition of 900°C, the number of cycles to fracture increases as the aging time becomes longer. It is concluded that the increases would be caused by a decrease in maximum stress during the low cycle fatigue test due to softening of the Ni-based superalloy.

Fatigue damage causes problems disrupting stable operation of thermal power plants. Especially in thermal power plant boilers, circumferential grooving corrosion of water wall tubes, which are thought to be caused by a combination of thermal fatigue and sulfide corrosion, have been detected in actual plants. This grooving corrosion type damage may cause breakage of water wall tube, and thus it is necessary to respond various costly repairs. ASME Boiler and Pressure Vessel Code Section III SS-NH proposes a method using FEA for evaluating thermal stress causing fatigue for design purposes, and this method may be applied to the assessment of thermal fatigue in water wall tubes. However, the thermal and mechanical boundary conditions of the water wall tube are complicated and uncertain, so predicting thermal stress by performing individual FEA is not straight forward. Therefore, we propose a method to easily evaluate thermal stresses and fatigue life consumption from monitoring temperature data of actual water wall tubes and simplified equations, not requiring individual FEA.

Flow accelerated corrosion (FAC) is one of important issues for aging of fossil and nuclear power plants. To understand the effect of the local flow field on FAC, FAC rates at an elbow pipe were measured under different flow velocity and temperature conditions. The elbow test section was made of stainless steel with the diameter of D = 49.5 mm and FAC rates were measured by using corrosion sensors made of carbon steel. The water temperature was about 150°C at first and decreased to 100°C and then 50°C. The dissolved oxygen concentration was kept under 0.1 μg/kg, and pH was nearly neutral (about 7.0) at room temperature. The mean cross-sectional velocity ranged from 0.39 to 5.74 m/s. FAC rates increased as flow velocity increased and their relation was not linear. FAC rates at 100°C were larger than those at 150°C and 50°C. At 150°C, the FAC rate was smaller at the intrados of the elbow pipe than at other circumferential locations. However, the location of the smallest FAC rate was changed to the extrados at 100°C. The influence of flow velocity was more noticeable at 100°C than that at 150°C and 50°C. This indicated that the influences of flow velocity and temperature on FAC was not the relationship of superposition law.

Flow Accelerated Corrosion (FAC) is one of the issues to be noticed considerably in plant piping management. For the integrity and safety of the plant, the wall-thinning and thinning rate due to FAC should be predicted, and we hope to construct the model to predict the wall thinning rate. We have studied FAC from the view point of flow dynamics. The mass transfer coefficient is measured by the electrochemical method with the point electrode in concentrated boundary layer. The Re number dependence of wall tinning rate is compared with mass transfer.

Flow accelerated corrosion (FAC) is one of the causes for wall thinning mechanisms in carbon steel pipes. Prediction of geometry factor is the key elements for estimation of FAC. Geometry factor is defined as the ratio of wall mass transfer coefficient in the piping systems such as elbow to that in a straight pipe. In order to simulate the mass transfer coefficient, we adopt the analogy between mass transfer and heat transfer. In this study, geometry factor of the elbow pipe is computed by using large eddy simulation (LES) for various Prandtl number and Reynolds number. When Prandtl number is close to unity, geometry factor changes depending on Prandtl number. However, as Prandtl number increases sufficiently, geometry factor becomes independent of Prandtl number. As the Reynolds number increases, geometry factor of the INSS elbow decreases, with reduction of the area in which large geometry factor is observed.

Flow-Accelerated Corrosion (FAC) is a pipe wall thinning phenomenon to be monitored and managed in the power plants with high priority. By using the prediction software “FALSET” for the pipe wall thinning developed by our institute, the wall thinning profile due to FAC at continuous pipe elements can be evaluated. However, in existing model, because the increment of the wall thinning amount was calculated according only to the distance between pipe elements, the effect of pipe layout (for example, the connection direction of the elbow) on the wall thinning profile could not be considered sufficiently. In this study, the wall thinning evaluation for continuous elbow pipe was conducted by utilizing the numerical analysis. Depending on the pipe layout (the distance between two elbows and the connection direction of the elbow), the wall thinning profiles at the second elbow were different. And also, calculating “geometry factor” which represents comparative amount of wall thinning against straight pipe, it was found that the geometry factor result in different values due to the connection direction of the elbow.

In JSME, research committee for the improvement of pipe wall thinning management had been held for 6 years in three phases since FY2008. In this committee, research and surveillance have been conducted on concerned technical area. Succeedingly, the 4th phase started from FY2015 and under this committee, new working group called “Management Rule Revision WG” was set up to review practical application and standardization of the developed relevant technique, especially prediction method. In this WG, implementation of prediction method to the management rule is mainly being discussed. So far in its activities, concept of adding new “Chapter D” providing option of utilizing prediction method to PWR/BWR technical rule has been proposed.

This paper considers the power transfer phenomenon of a fan-to-windmill system. We assume that the system consists of only mechanical components exhibiting passiveness, reciprocity, and linearity. The fan is mechanically driven at a constant torque and generates air-flow power. The windmill receives the power and also reaches a constant-torque rotation. In this stationary state, the torque is mathematically expressed as a linear combination of the angular velocities. An engineering interest is taken in the power transfer efficiency, which is defined as the receive-to-transmit power ratio. We derive a formula of power transfer efficiency in terms of the loading viscous coefficient. The load can be adjusted to lead the efficiency to its peak. The deduced maximum efficiency formula looks complicated. We then heuristically introduce a figure of merit called kQ, which rewrites the formula into quite an elegant fashion. We also display a graphical chart that enables one to comprehend how the maximum power transfer efficiency relates to kQ.