It is important to make the catalyst layer of Membrane Electrode Assembly (MEA) thin to decrease platinum loading of the Polymer electrolyte fuel cell (PEFC) For traditional spray methods, the catalyst layer cannot be applied thinly and uniformly on MEA because a lot of aggregates are formed in catalyst ink In this study, inside structure and composition of the aggregates were investigated, and a comparison was made between catalyst layers applied with traditional spray methods and the powdery catalyst dispersion method proposed by the authors The mechanism of aggregate formation and how to prevent it were clarified It was shown that there were possibilities of catalyst loading reduction and performance improvements by both of the two methods

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A network model has been proposed in order to predict the gas velocity distributions in a PEFC It analyzes the gas-velocity distributions depending on the local pressure drop which is affected by the gas-flow rate and the water accumulation Liquid drop form was observed in a PEFC by using neutron radiography, and classified into two models The one is small liquid drop accumulated near the rib corner, and the other is larger drop which is generated to be combined with small drops Numerical simulations were carried out for obtaining the local pressure drop caused by a liquid drop, and correlation equations were obtained for the pressure loss coefficient

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In polymer electrolyte fuel cells (PEFCs), the freezing of produced water makes cell performance worse below zero In this study, we investigated the freezing phenomena in the cathode catalyst layer (CL) by the experiments, and identified the effects of current density, cathode gas pressure, and oxygen concentration It was shown from the results that the ice distribution in the CL and the estimated amount of ice produced in the CL till the shutdown depend on the current density while they are independent of the cathode gas pressure and the oxygen molar concentration To clarify the main cause dominating these tendencies in the cold start, we introduced the effect of ice formation on an increase in the through-plane electrical resistance of the CL into the three phase boundary and the CL models, and examined the freezing mechanism in the CL

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To reduce PEFC accessories, especially for water management, that account for 50% of FC system cost, it is effective to simplify the accessories based on understanding water behavior in cell In this study, we developed a noble method of measuring temperatures in a cell with the array of thin thermocouples (φ 50 um) Temperature measurement is useful to comprehend the water behavior through the relationship between the water behavior and temperature We fabricated an in-line thin thermocouple, which is specific to this measurement Here, butt-welding of the thin thermocouples was executed with a capillary tube in inner diameter φ 60 jam In addition, polyimide film coated the thermocouples in its thickness of 2 |im The thermocouple had electric insulation resistance of 0.5 kΩ, and it was not enough to measure the temperature in cell

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Supposing the design of household-use-scale ethanol-steam-reforming reactors, the authors conduct experiments with Cu/Zn0/Al203 catalyst More specifically, the authors investigate the influences of liquid-hourly space velocity LHSV upon concentrations such as C_<H2> C_<CO2>, C_<CO> and C_<CH4> and the influence of LHSV upon the ethanol conversion X_<C2H5OH>, in a wide range of LHSV at several S/C's and at several T_R's To conclude, all the concentrations are close to the theory of Shinoki et al. (2011) except for the case at low T_R (= 520 K) and high LHSV (>0.6 h^<-1>) To settle the inconsistency of this exceptional case, the authors propose a new theory using some chemical reactions related with acetaldehyde CH_3CHO By introducing the chemical-equilibrium performance measure a into this new theory, we can settle the inconsistency Furthermore, the authors discuss the influences of S/C and T_R in addition to LHSV

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Cells with solid oxide electrolyte can be applied for a hydrogen generator, namely Solid Oxide Electrolysis Cells SOECs (SOECs) In this study, we carried out the cycle analysis foi SOEC systems following two steps Firstly, SOEC system models with H2 production capacity of 300 Nm3/h were constructed Secondly, system efficiency was calculated based on heat and mass balance from a viewpoint of "exergy" We treated two cases of SOEC systems which have different operating temperatures, 850°C and 650℃ As a result, several factors which decide property of exergy efficiency were obtained. At load rate with endothermic reaction, the balance of temperature of heat source and stack performance is primary factor for exergy efficiency On the other side, the heat loss is more important factor at load rate with exothermic reaction Therefore it is important to select the suitable system considering the operating conditions such as load range of SOEC systems

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Renewable energies have been introduced widely in Japan, so that necessity of electricity storage system has been increasing for load leveling and demand regulation Hydrogen electricity storage system is suitable for large capacity and long time storage This paper reports that hydrogen electricity system using SOEC (Solid Oxide Electrolysis Cell) and SOFC (Solid Oxide Fuel Cell) achieves high charge-discharge efficiency And this paper shows the system diagram which contains sell-stack, high-temperature thermal storage, low-temperature thermal storage, and heat-exchangers Furthermore this paper reports high temperature thermal storage test using NaCl as thermal storage material

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[in Japanese]

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It has been found that cylinders with the spiral fins produce large Magnus effect despite spinning in low speed Thus effect can be applied to wind turbines referred as the Magnus wind turbines The performances of the Magnus wind turbines are not clear due to the extraordinary and complex features For the purpose of revealing the characteristics, we conducted the tests in JAXA low-speed wind tunnel (JAXA LWT1) with the 6.5m x 5.5m test section The Magnus wind turbine model was developed for this wind tunnel with enough stiffness and the emergency stop device In the present paper, we show the measured power coefficients to the several conditions and configurations Furthermore, we estimated the net performances, evaluating the power consumption caused by aerodynamic loads to spin the cylinder blades The results show the important trends of the performances to several parameters, for example, the tip-speed ratio both of the main rotor and cylinders, the diameter of the cylinders and the size of the end plates The estimated maximum power coefficient as the aerodynamically net value is 0.41 in all measurement cases

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This paper illustrates the results of a wind tunnel experiment for the measurement of aeroacoustic noise from a straight-bladed vertical-axis wind turbine (VAWT) The measurement of the sound pressure was conducted by using microphone arrays composed of 16 microphones At the side of the VAWT where the relative wind velocity that acts on a blade becomes maximum, it was observed that the existence of the blades led to a broadband sound from 400 Hz to 6300 Hz In addition, the possibility was confirmed that aeroacoustic noise from blade tips at 1250 Hz become more prominent with an increase in the tip speed ratio Above the VAWT, it was found out that the horizontal position where the sound level was the highest varied with the tip speed ratio

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As for fundamental understanding of densely arranged vertical axis wind turbines expected in future, wind tunnel model experiments are carried out to find out the aerodynamic interaction between two wind turbines With PIV measurement of time-dependent flow field, the interaction mechanism is deduced, which is classified into near-field interaction due to pressure-field coupling, and far-field interaction due to mean velocity distribution Savonius and Darrieus turbines are compared, and we have found different interaction mechanism between them Savonius turbine, which rotates at tip-speed ration less than unity, produces a dynamic pressure fluctuation to enhance the near-field interaction In contrast, two Darrieus turbines interact with shear layer released by rotating blade at high tip-speed ratio

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The flow characteristics of a new hybrid vertical axis wind turbine which has advantages of the drag type and the lift type wind turbine have been investigated by the conditional sampling PIV and stereoscopic PIV The experimental apparatus is constructed using the stereoscopic PIV measurement system with a conditional sampling device and a new hybrid vertical axis wind turbine installed in a circulating water channel The value of the new hybrid vertical axis wind turbine has been clarified by the pressure distribution around the blades calculated from the velocity fields measured by the PIV Moreover, three-dimensional motions of the tip vortices of the blades have been investigated by the velocity fields measured by the stereoscopic PIV

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Due to the environmental problems such as global warming and shortage of fossil fuel resources, natural gas and biomass ethanol have been used as alternative fuels of conventional gasoline Also high thermal efficiently combustion technology that can save fuel is strongly demanded Lean burn and EGR (Exhaust Gas Recirculation) dilution technology have been well known as high efficient combustion strategy However, dilution of mixture by air or EGR reduces ignitability and deteriorates ignition stability, Leading to slow burning velocity Recently, an ignition system which uses low-temperature plasma discharge has been proposed as a new device to improve ignition performance In this study, a performance of the newly developed repetitive pulse low temperature discharge ignition system was experimentally investigated The experiments were conducted using a small 4-stroke single cylinder engine Three fuels (gasoline, city gas, and ethanol) which have different ignitability were used As a result, the lean limit for stable ignition successfully was extended using the proposed low-temperature plasma discharge ignition system

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The cooling power of magnetic refrigeration depends on entropy change (AS) of magnetic materials greatly It is important for practical magnetic refrigeration to layer some magnetic materials To get data for layered materials, virtual materials based on Gd are composed The result of simulation with changing virtual materials' diameter and refrigeration cycle time shows that 1 the best diameter is 0.2mm, 2 refrigeration cycle time should be as large as possible, 3 Temperature differences should be small and the magnetocaloric effect is as large as possible

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In recent years, numerous space scientific missions are being planned which require very low temperatures and very low temperature environments Among them is cosmic microwave background radiation (CMB) The excellent full resolution of the X-ray detector which is used for CMB observations is obtained by cooling to below lOOmk The adiabatic demagnetization refrigerator (ADR) is cited as a refrigerator for generating temperatures in such a range ADR boasts high refrigeration efficiency at very low temperatures and further, has the advantage that it is not dependent on gravity since the cooling medium is solid At present, we are developing an ADR suitable for the CMB project Its prototype is the four-stage continuous-operation adiabatic demagnetization refrigerator (Continuous ADR) which has been developed previously First, proof-of-concept experiments of sensor cooling will be conducted using the existing CADR apparatus Improvements will be made based on the results, and the final goal is set as the development of a three-stage CADR The overall thermal design and the characteristics of the heat switch will be presented this time

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Recovered and recycle useful metal from waste of electric and electronic equipment (WEEE) is necessary to secure a stable material supply Fiber reinforced epoxy board was liquefied in biomass derived tar solvent That was liquefied by using tar derived from Japanese cedar and benzyl alcohol or cresol mixture solvent also Tar solvent was prepared from the liquid product by removing light fraction Epoxy board was liquefied almost completely in the tar solvent from Japanese cedar and cresol mixture solvent at 300℃ for 120 min under atmospheric pressure Finally, most of solvent was recovered from thermal decomposition of the once liquefied epoxy board at 500 -800℃ These experimental results indicate that waste printed circuit board can be liquefied in a recyclable solvent that was derived from the once liquefied epoxy board

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Recovery of tantalum from tantalum-condenser is recently important since production of tantalum have not been stable for the price and the quantity However, recovery of tantalum from tantalum-condenser is difficult since tantalum parts strongly cover with the flame retardant resin made of halogenated compound in the tantalum condenser In this study, stream gasification using mixed alkali carbonate is applied for recovery of tantalum, stabilization of halogenated compounds and hydrogen production Mold resin can be decomposed over 500℃ by using stream gasification with mixed alkali carbonate, and the recovery of tantalum parts from tantalum-condenser is successful

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When Polyethylene is heated in an inert atmosphere and the volatile products are condensed, the molecular weight distribution (MWD) of the product obtained is very wide In addition, this product is very waxy, has poor low properties, and is unusable as a liquid fuel. To improve the product quality, various catalysts are usually used in the recycling process However, these catalysts are costly. On the other hand, if the higher boiling fractions of the volatiles evolved due to degradation are not allowed to escape, then the MWD of the final product can be improved. This paper we have studied pyrolysis of High Density Polyethylene (HDPE) by using a reflux-condenser apparatus at 450℃ for removing of waxes in the pyrolysis oil. The product oil was analyzed by using GC/MS. The analysis result indicates that HDPE waste plastic to produced heavy fuel hydrocarbon chain range C_5 to C_<21> and light gas are also present and hydrocarbon range is Q_1-C_4.

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In the detached island area in Japan, it is thought from the danger of energy cutting into pieces at the time of a disaster, and the numerousness of natural resources that the demand and the possibility of renewable energy introduction are high In this research, in order to search for the suitable renewable energy introduction method in an object place Sikine island, We investigated the geographical conditions and regional peculiarity of Sikine island As a result, advantages were looked at by introduction of technological know-hows, such as sunlight, wind force, and heat of the earth, in Sikine island And it turned out that these introduction of technological know-hows has the possibility as alternative electric power at the time of a disaster

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Heat and mass transfer have been investigated during fast pyrolysis of biomass particle Temperature at the inside of the particle increased monotonously with time due to thermal conduction for T < 500K. The temperature increased slowly with time due to thermal conduction and heat of endothermic holo-cellulose decomposition for 500 K < T < 700 K. On the other hand, the temperature became higher than that at the surface of it due to heat of exothermic activated-lignin decomposition for T > 773 K. In order to investigate the effect of secondary tar decomposition, nitrogen career gas was introduced into the experimental test rig Although the temperature distribution didn't change even if the career gas input, generated gas flow rate was affected adequately by the secondary tar decomposition

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The purpose of this study is to develop a safe and efficient incineration method to treat a large amount of woody debris in the sea caused by the Great East Japan Earthquake Much of the debris remains untouched even two years after the earthquake We apply the two-stage combustion technique, which we developed for woody biomass, to the method Experiments are conducted using a small combustor and woody chips saturated with artificial sea water to simulate the incineration of the woody debris Effects of chloride on the combustion as well as combustion controllability are investigated for three different moisture contents

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A vibration mill using cog-ring media, which replaces the ball medium in a conventional vibration mill with a cog-ring medium, was developed to achieve high-impact pulverization of lignocellulosic biomass for producing bio-ethanol Japanese cedar powder pulverized by the vibration mill using cog-ring media showed that saccharification efficiency in enzymatic saccharification of Japanese cedar powder of greater than 70% was reached based on holocellulose at tube test For this study, the effect of agitation speed on enzymatic saccharification was investigated using a pulverized Japanese cedar powder Enzymatic saccharification was conducted at 10% solid concentration with agitation speeds of 0, 10, 30, 50, and 100 rpm using two scales of reactors, with 1 L and 3 L separable flasks, during 48 hr A Hi-F mixer, which was suitable for agitation of high-viscosity liquid, was used for agitation in enzymatic saccharification The enzyme of cellulase was dosed 0 5, 1, or 5% based on the weight of pulverized Japanese cedar powder Results show that the saccharification efficiency increased concomitantly with decreasing agitation speed until 30 rpm The best yields of 77% at 1 L and 75% at 3 L were obtained at 30 rpm agitation Moreover, relation between Reynolds number for mixing and saccharification efficiency was discussed to find good index for enzymatic saccharification by agitation

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Sanmu-shi, Chiba Prefecture, used to be a prosperous region based on its forestry industry and was widely known for its cedar trees branded as sanbu-sugi A combination of the aging labor population, the stagnant price of timber and the spread of disease that is typical to sanbu-sugi resulted in the devastation of the forests, which now requires immediate measures Now, neglect of thinner timber etc is remarkable in the forest in sanmu-shi Care of a forest is urged to such wood by finding out the utility value as firewood, and it tries to aim at reproduction of a forest as a result And event using the reproduced forest space aims at maintenance of a forest

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This paper describes a gas turbine inlet air cooling system using high pressure spray nozzle Scale model inlet duct is manufactured within water spray of inlet fogging system, and many testing was conducted on the condition of same level of actual velocity with inlet duct at site As testing results, droplet size finally reduce to SMD 80 um at 1st blade leading edge Next, water spray adjusting actual attack to blade is provided to test piece of same material with actual compressor blade, and weigh is measured at every constant time period for getting averaged erosion depth As a result, it is concluded that erosion at leading edge of 1st compressor blade is predicted to be approx 1.2mm at maximum per 10 years less than acceptable limit of depth, and it may have no need for maintenance of blade replacement and so on in 10 years

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Higher temperature of the combustion leads to efficiency in gas turbine engines Now by the cooling of gas turbine blade, the gas temperature of the first stage inlet is possible to exceed the heatproof temperature of the turbine blade material, film cooling is one of the cooling to turbine blade methods Gas temperature in the first stage entrance is in creased by this cooling technology, but on the other hand, the increase in amount of cooling air leads to the mainstream gas temperature drop Efficient cooling and less air flow rate is required the high gas temperature further In this study, in order to obtain a difficult data, at high temperature, pressure conditions were carried out numerical calculations using the STAR-CCM+

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For upgrades of nuclear power plant with pressurized water reactor, it is one of the effective mean to improve the steam generator (SG) secondary flow To evaluate thermal-fluid dynamics in secondary system of SG, boiling two-phase phenomenon is needed to analyze In this study, new numerical analysis system is developing for PWR secondary system including SG and turbine system Firstly three dimensional two-phase flow analysis model of SG secondary-side is developed with two-fluid model, and we confirm that our model can estimate steam pressure of feedring type SG Secondaiy present model is applied to preheat type SG and evaluate the effect of increasing of steam pressure in secondary-side From this result, we succeeded in predicting the steam pressure increase with improving the method of feedwater supply

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To evaluate thermal-fluid dynamics in secondary system of the steam generator(SG), we developed new numerical analysis system for SG system It is three dimensional two-phase flow analysis with two-fluid model In addition, we developed the balance of plant (BOP) model include the turbine, condensate and feedwater system, in order to apply to plant cycle evaluation of thermal efficiency and operating characteristic of a power plant system

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In the previous study, numerical simulations were done for countercurrent gas-liquid flows in a vertical pipe by using a volume of fluid method (VOF) implemented in the CFD software, FLUENT6.3.26, to evaluate countercurrent flow limitation (CCFL) at the lower end of steam generator U-tubes The simulated CCFL characteristics agreed well with air-water experimental data but flooding in simulations appeared at the upper end of the vertical pipe, which meant that CCFL at the upper end was too rigorously simulated To avoid flooding at the upper end, therefore, water was supplied through the pipe wall simulating condensation on the inner surface and flooding near the lower end was simulated, but it was flooding in the pipe So in this study, the effect of the contact angle of water was evaluated, because the contact angle becomes small when the inner surface of the pipe is wet with a thin water layer With small contact angles, flooding at the lower end was successfully simulated

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Nuclear safety is getting more important in response to the Fukushima Danchi nuclear disaster in 2011 It is also the fact that designers put emphasis on economic efficiency Accurate prediction of fuel surface temperature is important from these points of view In this study a method to predict heated surface temperature was developed by modeling heated sections as upward flow in a vertical circular tube under high-pressure conditions of 7[MPa] and tracking the changes in flow regime as nucleate boiling, dryout and post-dryout The results were compared with several experimental data It was found from the comparison that prediction performance of boiling transition points and heated surface temperature of pre- and post-dryout region was good

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In order to understand the jet breakup behavior of the molten core material into coolant during a core distractive accident (CDA) for a sodium-cooled fast reactor (SFR), we simulate the jet breakup using the lattice Boltzmann (LB) HCZ model The applicability to jet breakup simulation by LBHCZ model is validated by the comparison with the experimental data obtained in the present study Sensitivity analyses are performed by using LBHCZ model It is shown that the jet breakup length is in good agreement with Epstein's correlation when the dominant phenomenon for the jet breakup is hydrodynamic fragmentation

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In order to understand the jet breakup behavior of the molten core material into the coolant during a core disruptive accident (CDA) for a sodium-cooled fast reactor (SFR), we simulated the breakup using the lattice Boltzmann (LB) HCZ model The surface and fragmentation behavior was investigated in detail in the simulation results for examining the effect of ambient fluid around the jet As a result, we observed that the jet breaks up by fragmentation which occurs at side of the jet Thus, it was confirmed that the mechanism of the jet breakup behavior follows that of the Epstein's correlation when the dominant phenomenon for the jet break up is hydrodynamic fragmentation

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A fluidized bed is utilized in various industrial process such as combustion, drying, mixture, the catalyst reaction and granulation etc In order to achieve the energy saving of the ship, by utilizing the high reactivity of the fluidized bed, and is subjected to heat recovery of the exhaust gas Using the discrete element method in order to grasp the state of the particles for heat recovery and exhaust gas circulating fluidized bed that swings, and to calculate the particle mass flow rate near the wall Through a variety of calculation in different conditions, we have confirmed the effect of swing cycle, angle and the particle diameter has on the mass flow rate

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The critical heat flux (the CHF) in saturated pool boiling of water was investigated experimentally under the attachment of a honeycomb porous plate on the heated surface In the previous study, the CHF was shown experiment ally to be enhanced to more than twice that of a plain surface The CHF enhancement is caused by the automatic liquid supply due to capillary action and the reduction of the vapor escape flow resistance due to separation of liquid and vapor flow by the honeycomb porous structure In this paper, a simplified one-dimensional capillaiy limit model, in which the pressure drops caused by liquid and vapor flow through a honeycomb porous plate is balanced by capillary force, is applied to predict the CHF The calculated results are compared with the observed ones obtained from simplified experiments which extract the capillary action effect only

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In this study, effects of heat flux and nanofluid dispersion condition on the boiling heat transfer (BHT) and critical heat flux (CHF) m water pool boiling were investigated. For the heat flux effect, five different heat fluxes were applied to the heated surface during the nanoparticle deposition process with setting the boiling time in nanofluid to 0, 1, 3, 10 and 20 minutes. Static contact angle, BHT and CHF characteristic in relation with heat fluxes and boiling time were discussed. In addition, effect of nanoparticles dispersion stability was investigated by two kinds of nanofluid preparation method: one-step and two-step methods. These different preparation methods resulted in different level of nanofluid stability. Its effect on CHF performance in pool boiling was investigated.

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The ability to predict void formation, void fraction and critical heat flux -CHF- in flow boiling under oscillatory flow and vibration conditions is important to the safety technology of nuclear reactor during earthquake In the present study, the onset of nucleate boiling -ONB-, the point of net vapor generation -NVG- and CHF on saturated flow boiling under vibration conditions were investigated experimentally Steady state experiments were conducted using a copper thin-film and subcooled water at 0.1 MPa The liquid velocity was 0.27, 1.38, 3.20 and 4.07 m/s, respectively, the liquid subcooling was OK A heater was made of a printed circuit board A test section was a rectangular flow channel of 10 mm width and 10 mm height The test heater was heated by Joule heating of d c current from a low-voltage high-current stabilizer The heating rate of the heater was determined from supplied current and voltage The temperature of the heater was obtained by referring to the measured electric resistance The test section was arranged for horizontal position facing upward and for vertical position, respectively For the vibration condition, the test section was set on a vibration table The ONB was decided as an occurrence of the first boiling bubble The critical heat flux was determined as that immediately before the heating surface physically burned-out The CHF on saturated flow boiling under vibration conditions were investigated experimentally

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The enhancement of drop-wise condensation heat transfer was examined for steam at 0.1 MPa by using grooved-heat transfer surfaces The heat transfer surface was made of copper The size was 15 × 15mm The groves were formed on the heat transfer surface The groove size was 2mmTW × 2mmBW × 2mmD, 3mmTW × 3mmBW × 3mmD and 3mmTW × 2mmBW × 2mmD.The drop-wise condensation was attained by plating the surface with gold In the case that the surface was flat, the drop-wise condensation heat flux was of course much higher than that of the film-wise condensation As wall sub-cooling was increased, the difference of the heat flux between the drop-wise condensation and the film-wise condensation decreased to become zero The drop-wise condensation heat flux on the grooved heat transfer surface that was defined hypothetically by the flat surface was larger than that of the flat heat transfer surface When the top and the wall of the groove were plated with gold, the hypothetical drop-wise condensation heat flux was highest Next was the case that the top, the wall and the bottom of the groove was plated and third was only the top of the groove was plated It appeared in the recorded high speed video images that condensate drops on the top and the wall of the groove was pull down to the bottom of the groove As a result of it, the bare area that was exposed to steam seemed to increase When the groove size was increased from 2 mm to 3 mm, the enhancement of the drop-wise condensation heat flux was mitigated

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The thermal and nuclear power plants have been imposed a stable supply of electricity To certainly achieve this, we built the plant condition monitoring system based on the heat and mass balance calculation If there are some performance changes on the turbine system components of their power plants, the heat and mass balance of the turbine system will change This system has ability to detect the abnormal signs of their components by finding the changes of the heat and mass balance Moreover we note that this system is built for steam turbine cycle operating with saturated steam conditions

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In order to evaluate the effects of flow field on corrosion rate due to flow accelerated corrosion (FAC), the corrosion rate and flow velocity near wall were measured after an orifice In this study, the difference of flow field downstream from orifices with some aperture ratios was examined using Laser Doppler Velocimetry (LDV) Velocity distributions along the circumferential direction and along the flow direction with each aperture ratios of 0.62, 0.5 and 0.41 were compared, in order to verify the numerically simulated result The diameter of pipe was 50 mm, and the each orifice diameter was 31.0 mm, 25 mm and 20.5 mm, respectively Dependence of orifice aperture ratio on flow field downstream from an orifice was investigated by measurements of streamwise component of time-averaged velocity and standard deviation of velocity downstream from orifices

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For piping system in electric power plants, carbon steels and stainless steels are widely used In this study, we discussed the effect of impact velocity on liquid droplet impingement erosion in piping material Test chamber specified in ASTM G134 standard method by spray nozzle was used to carry out liquid droplet impingement tests on the specimens of carbon steels and stainless steel The comparison between carbon steels and stainless steel is discussed It was found that the threshold flow velocity below which no erosion occurred was obtained and the value varies depending on Vickers hardness of material The threshold flow velocity increased with the increased Vickers hardness of materials

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Flow Accelerated Corrosion (FAC) is a pipe wall thinning phenomena to be monitored and managed in power plants with high priority At present, its management has been conducted with conservative evaluation of thinning rate and residual lifetime of the piping based on wall thickness measurements However, noticeable case of wall thinning was occurred at separation and union pipe It is a problem to manage section beneath reinforcing plate of T-tube pipe and "crotch" of T-joint pipe, the region where measurement is difficult to conduct with ordinary ultrasonic testing device In this study, numerical analysis for T-tube and T-joint pipe was conducted, and wall thinning profile by FAC was evaluated by calculating mass transfer coefficient In the case of union flow from mam and branch pipe, the wall thinning profile of T-tube showed the tendency of increase at mam pipe On the other hand, noticeable profile appeared at "crotch" in T-joint

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Flow visualization experiment and accelerated pipe wall thinning experiment were conducted by applying a swirling flow generated by a piping configuration, three-dimensionally connected dual elbow, to the inlet flow condition of a pipe orifice to investigate pipe wall thinning downstream of an orifice appearing due to the combination of swirling flow and orifice The flow downstream of the orifice was curved by the action of the swirling flow, and the channel wall where the flow turned off toward underwent a large amount of wall thinning Profiles of turbulent quantities, such as turbulent kinetic energy and Reynolds shear stress, were compared to those of amount of pipe wall thinning It was found that the profiles of Reynolds shear stress showed good agreement with those of pipe wall thinning in the case for a large amount of that However, relatively small amount of pipe wall thinning, any profile related to fluid motion could not explain the profiles of pipe wall thinning

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Effects of Cr content on flow accelerated corrosion (FAC) of carbon steels have been evaluated and their relation to oxide scale characteristics based on detailed oxide layer characterizations using transmission electron microscope with X-ray analyzer have been discussed There is no "threshold" concentration of chromium below which there is no effect of Cr content on the corrosion rate Time dependency to chromium effect has also been not observed Thickness of oxide layer does not affect the FAC rate in this experiments

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Flow Accelerated Corrosion (FAC) of carbon steel (CS) piping is one of main issues in secondary system of Pressurized Water Reactor (PWR) nuclear power plant Wall thinning of CS piping due to FAC increases potential risk of pipe rupture, cost for inspection and replacement of damaged pipes In particular, corrosion products generated by FAC of CS piping brought steam generator (SG) tube corrosion and degradation of thermal performance, when it intruded and accumulated in secondary side of PWR. ^(1) Therefore, we estimated an applicability and effectiveness of Oxygenated Water Chemistry (OWC) as a new approach to FAC suppression for PWR secondary system by experiment in laboratory and demonstration test at Tsuruga-2 (1160 MWe PWR, commercial operation started in 1987). ^<(2)(3)> Based on this result, OWC has been applied to condensate system in Tsuruga-2 from Jan 2011 And, to evaluate the FAC mitigation effect of OWC, wall thickness of actual condensate piping in Tsuruga-2 after OWC application was measured by continuous monitoring system, using high-temperature and high-resolution ultrasonic probe In this paper, behavior of actual wall thinning rate of condensate piping in Tsuruga-2 under various pH and DO concentration is discussed

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Assessing properly creep damage in power boiler tubes is, in some cases, important in securing rational operation and maintenance of aged thermal power plants, where accumulation of scale on tubes can cause over-heating Destructive remaining life assessment technique is regarded as appropriate for low alloy boiler tube base materials, and thus miniature creep testing is employed for the limitation of sampling due to the thin wall dimensions Some problems related to the determination of sampling portions and the interpretation of test results have been addressed This paper describes some technical considerations in applying the assessment technique to actual tubes together with some test data obtained from tests of disposed tubes after long term services

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Small Punch (SP) Creep test is a new testing methodology where a very small specimen is required to verify creep properties The size and the volume of SP creep specimens are smaller than those of conventional uniaxial creep specimens This testing method has been recognized as a practical procedure to examine residual creep lives of high temperature components Employing a part of aged boiler tubes of STBA24 used for about 140,000 hours below 500℃, the SP and the uniaxial creep tests were conducted at 650℃ in air and Argon gas to study the relationship between the SP and the uniaxial creep tests Vickers' hardness and gram number of the test material were independent on the sampling area SP creep rupture lives were nearly the same regardless of the sampling area and the testing atmosphere Ratio of the applied load in the SP creep test to the initial stress in the uniaxial one was about 2.1mm^2, and varied with the rupture life.

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Small punch (SP) creep test with TEM disk-size specimen (φ3mm, t 0.25mm) was applied to the aged boiler tube (STBA24), which had been used in excess of 140,000 hours, to investigate the distribution of material degradation and/or damage in the thin tube wall. Experimental results revealed that there was no significant difference between the creep properties of specimens removed from the inside and the outside of thin wall, and the material degradation and/or damage had been accumulated uniformly. Additionally, it was also revealed that the SP creep rupture data might be converted into uniaxial data by the average equivalent stress in steady state, σ_S, which has been newly proposed by the authors.

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