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Journal articles on the topic ""wall-Tube" electrode":
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CHENG, Lingyun, Nianwen XIANG, Kejie LI, Weijiang CHEN, Kai BIAN, Jin YANG, Zongqi XU, Congying HAN, Hongyang GU, and Chun YANG. "Reliability improvement of gas discharge tube by suppressing the formation of short-circuit pathways." Plasma Science and Technology 24, no. 3 (March 1, 2022): 035501. http://dx.doi.org/10.1088/2058-6272/ac479c.
Abstract After cumulative discharge of gas discharge tube (GDT), it is easy to form a short circuit pathway between the two electrodes, which increases the failure risk and causes severe influences on the protected object. To reduce the failure risk of GDT and improve cumulative discharge times before failure, this work aims to suppress the formation of two short-circuit pathways by optimizing the tube wall structure, the electrode materials and the electrode structure. A total of five improved GDT samples are designed by focusing on the insulation resistance change that occurs after the improvement; then, by combining these designs with the microscopic morphology changes inside the cavity and the differences in deposition composition, the reasons for the differences in the GDT failure risk are also analyzed. The experimental results show that compared with GDT of traditional structure and material, the method of adding grooves at both ends of the tube wall can effectively block the deposition pathway of the tube wall, and the cumulative discharge time before device failure is increased by 149%. On this basis, when the iron-nickel electrode is replaced with a tungsten-copper electrode, the difference in the electrode’s surface splash characteristics further extends the discharge time before failure by 183%. In addition, when compared with the traditional electrode structure, the method of adding an annular structure at the electrode edge to block the splashing pathway for the particles on the electrode surface shows no positive effect, and the cumulative discharge time before the failure of the two structures is reduced by 22.8% and 49.7%, respectively. Among these improved structures, the samples with grooves at both ends of the tube wall and tungsten-copper as their electrode material have the lowest failure risk.
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DEHGHANI, SAJJAD, MOHAMMAD KAZEM MORAVVEJ-FARSHI, and MOHAMMAD HOSSEIN SHEIKHI. "TEMPERATURE DEPENDENCE OF ELECTRICAL RESISTANCE OF INDIVIDUAL CARBON NANOTUBES AND CARBON NANOTUBES NETWORK." Modern Physics Letters B 26, no. 21 (July 16, 2012): 1250136. http://dx.doi.org/10.1142/s0217984912501369.
We present a model to understand the effect of temperature on the electrical resistance of individual semiconducting single wall carbon nanotubes (s-SWCNTs) of various diameters under various electric fields. The temperature dependence of the resistance of s-SWCNTs and metallic SWCNTs (m-SWCNTs) are compared. These results help us to understand the temperature dependence of the resistance of SWCNTs network. We experimentally examine the temperature dependence of the resistance of random networks of SWCNTs, prepared by dispersing CNTs in ethanol and drop-casting the solution on prefabricated metallic electrodes. Examining various samples with different electrode materials and spacings, we find that the dominant resistance in determination of the temperature dependence of resistance of the network is the resistance of individual tubes, rather than the tube–tube resistance or tube–metal contact resistance. It is also found that the tube–tube resistance depends on the electrode spacing and it is more important for larger electrode spacings. By applying high electric field to burn the all-metallic paths of the SWCNTs network, the temperature dependence of the resistance of s-SWCNTs is also examined. We also investigate the effect of acid treatment of CNTs on the temperature dependence of the resistance of SWCNTs and also multi-wall CNTs (MWCNTs) networks.
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Stein, Jennifer A., and Alanah Fitch. "Dual wall-tube electrode cell for use in clay-modified electrode studies." Electroanalysis 6, no. 1 (January 1994): 23–28. http://dx.doi.org/10.1002/elan.1140060106.
Birhane, Y. T., S. C. Lin, and F. C. Lai. "Effect of Electrode Length on the Performance of EHD Gas Pump." Applied Mechanics and Materials 598 (July 2014): 355–60. http://dx.doi.org/10.4028/www.scientific.net/amm.598.355.
The effects of electrode length on the characteristics of flow induced by an electrohydrodynamic (EHD) gas pump in circular pipe have been experimentally examined in this study. The gas pump has a diameter of 61.8 mm and uses eight evenly spaced emitting electrodes which are flush mounted on the tube inner wall. The gap distance between emitting and ground electrodes is fixed at 25 mm and two emitting electrode lengths (15 mm and 40 mm) are considered. Experiments are conducted using positive corona discharge with voltage varying from 17.5 kV to 23 kV. Several important implications from the present results for practical engineering applications are presented.
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Li, Mao Dong, Xue Ying Tang, Yu Hui Du, Juan Liu, Jun Ming Zhao, and Zhi Ping Zhu. "Electrochemical Property Study of Water-Wall Tube 20G in SO42- Medium at Room Temperature." Advanced Materials Research 676 (March 2013): 31–34. http://dx.doi.org/10.4028/www.scientific.net/amr.676.31.
In the article, the effect of SO42-on the corrosion behavior of boiler water-wall material 20G under the equilibrium phosphate treatment (EPT) was studied by a series of electrochemical experiments at room temperature. Electrodes AC impedance value (Rp) was used to evaluate the corrosion resistance of the material. The experiment results show that, SO42-ion is aggressive anion; water-wall tube material 20G has certain sensitive corrosion to the SO42-. The 20G electrode AC impedance value decreases with the increase of the SO42-’s concentration and the material corrosion resistance reduces.
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Yao, Fu, Duan Xiao-Long, Xing Ming-Ming, Luo Xi-Xian, Zhang Ying-Hui, and Liu Wang. "Study on Fabrication and UV Photoelectric Property of TiO2 Nanotube Array Electrodes." Journal of Nanoscience and Nanotechnology 16, no. 4 (April 1, 2016): 3945–50. http://dx.doi.org/10.1166/jnn.2016.11830.
Highly ordered TiO2 nanotube array electrodes were successfully fabricated by a two-step anodization method on Ti sheet substrates in an electrolyte composed of ammonium fluoride, deionized water, and glycol. The tube wall was smooth, and the average internal and external diameters, wall thickness, and tube length achieved were 80 nm, 90 nm, 10 nm, and 9 μm, respectively. X-ray diffraction and field emission scanning electron microscopy results revealed that the TiO2 nanotube arrays presented an amorphous structure. When calcined at 300 °C, the arrays crystallized into the anatase phase, and the crystallization degree of the oxide layer increased as the temperature rose. Calcinating at 400 °C did not obviously disrupt the porous structure of the highly ordered arrays. However, higher temperature enlarged the diameter of the nanotube array and roughened the tube wall. When the temperature reached 600 °C, the nanotube mouth broke because of the excessive stress, causing the oxide layer’s thinness and nanotube mouth clogging. The photoelectric test showed that the electrode presented obvious photoresponse under 300–400 nm UV excitation (maximized at 360 nm). The degree of crystallization and the micro-structure of the oxide layer can significantly affect the photoelectric properties of the electrode. After calcination at 400 °C, the TiO2 nanotube arrays, with highly ordered tubular structure directly connected to the Ti substrate, can ensure the rapid transportation of photo-induced electrons to the Ti substrate, while the high crystallinity of the arrays can help reduce the defect density of the nanotube and extend the lifetime of the photo-induced carriers. The electrode showed the best photoelectric property, and the photocurrent intensity was maximized (29.6 μA). However, the calcination process with over-temperature resulted in substantial loss of the TiO2 oxide layer, mouth clogging, and a severe decline in the photoelectric properties.
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Kapauan, Amando F. "A wall-tube electrode cell for computerized potentiometric stripping analysis." Analytical Chemistry 60, no. 19 (October 1988): 2161–62. http://dx.doi.org/10.1021/ac00170a037.
YABUTANI, TOMOKI, YOSHIO SHODA, YUJI TANI, YOHEI YAMADA, and JUNKO MOTONAKA. "DIRECT OXIDATION OF TRYPTOPHAN ON MULTI-WALL CARBON NANOTUBES MODIFIED CARBON ELECTRODE AND ITS APPLICATION TO FUEL CELL." International Journal of Modern Physics: Conference Series 06 (January 2012): 115–20. http://dx.doi.org/10.1142/s2010194512003030.
Direct oxidation of tryptophan on multi-wall carbon nanotubes modified glassy carbon electrode was examined. Surface poisoning, which was suppression of oxidative current caused from adsorption of oxidized compounds of amino acids through multiple redox scan, was observed on carbon material electrodes (multi-wall carbon nano tube(CNT), carbon powder(CP), Ketjen Black (KB) and glassy carbon(GC). It was found that CNT showed a highly inhibitory effect on the surface poisoning and high current value in the direct oxidation of tryptophan because of a π-π interaction between CNT and indole ring of tryptophan results from orbital mixing. This CNT modified GC electrode was applied to an anode in a fuel cell used with amino acids as fuel. As a result, the maximum of the power density showed 0.36 mW cm-2 at 2.5 mA cm-2 of the current density and 140 mV of the cell voltage.
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Rees, Neil V., Oleksiy V. Klymenko, Barry A. Coles, and Richard G. Compton. "Fast scan linear sweep voltammetry at a high-speed wall-tube electrode." Journal of Electroanalytical Chemistry 557 (October 2003): 99–107. http://dx.doi.org/10.1016/s0022-0728(03)00352-8.
Abstract Usually, heating surfaces used in thermal power plant boilers include economizers, water-cooled walls, superheaters, and reheaters, abbreviated as the “four tubes” of boilers. The leakage of the heating surface is a common form of unplanned shutdown in thermal power plants, accounting for more than 50% of abnormal shutdown accidents of units. Once the heating surface explosion occurs, the thermal power plant needs to shut down for treatment, resulting in huge losses in power generation and fuel consumption during startup and shutdown. This has a huge impact on the safety production and economic benefits of the enterprise. In this paper, the leaked water-cooled wall tube in the subcritical boiler was studied by means of microstructure analysis, hardness test, energy spectrum analysis, chemical composition test, macro-morphology inspection, and tensile test. The results revealed that the oxygen concentration difference between the area installed in ceiling pouring material and the area exposed to the air can result in significant differences in electrode potential between different areas of the front water wall tube passing through the ceiling. An oxygen concentration difference battery is formed. In this way, the water-cooled wall steel pipe continuously corroded and thinned. Finally, perforation leakage occurred under the pressure of the internal high-temperature medium.
Dissertations / Theses on the topic ""wall-Tube" electrode":
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Hadj, Ahmed Asmaa. "Design of new electrochemical cells for studying enzymes by protein film electrochemistry." Electronic Thesis or Diss., Aix-Marseille, 2022. http://www.theses.fr/2022AIXM0100.
L’électrochimie directe des protéines (PFE) est une technique dans laquelle une enzyme est adsorbée à une électrode et son activité catalytique est mesurée sous forme d’un courant électrique, ce qui permet l’étude de la cinétique d’enzyme en fonction de différents paramètres expérimentaux. Cette technique nécessite un transport rapide du substrat vers l’électrode. Dans une étude précédente, notre équipe a proposé une nouvelle cellule électrochimique offrant un transport supérieur à l’électrode tournante, couramment utilisée dans les méthodes PFE. Dans cette thèse, nous avons exploré, à l’aide de CFD, l’effet des différents paramètres et proposé des formules semi-empiriques pour prédire les propriétés de transport dans la cellule. Puis, nous avons validé expérimentalement nos prédictions. En outre, nous avons construit un nouveau type de cellule avec des mélangeurs intégrés qui devraient permettre des changements rapides de concentrations Protein Film Electrochemistry (PFE) is a technique in which an enzyme is adsorbed at an electrode and its catalytic turnover rate is measured as an electrical current which allows the investigation of enzyme’s kinetics as a function of different experimental parameters. However, this technique requires fast transport of the substrate towards the electrode. In a previous study, our team proposed a new design based on the wall-tube electrode that provides better transport than the rotating disc electrode, which is commonly used in PFE methods. In this thesis, we explored, using CFD, the effect of the various parameters of the design and proposed semi-empirical formulas to predict the mass transport coefficient and shear stress at the electrode. We used a 3D-printed cell to validate experimentally our predictions. Moreover, we designed and built a new type of wall-tube electrodes with integrated mixers that should allow faster changes of substrate and inhibitor’s concentrations
Book chapters on the topic ""wall-Tube" electrode":
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Han, Junling, Guannan Ren, Limei Peng, Hongyu Tian, and Pengbo Ji. "Analysis and Qualification Control of Welding Defects of Coated 15-15Ti Cladding Tube." In Springer Proceedings in Physics, 861–71. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-1023-6_73.
AbstractPhysical property test fuel rod is used for the engineering test and thermal comprehensive experimental verification of lead-cooled reactors. Preliminary electron beam welding (EBW) trials showed that the welding quality of coated 15-15Ti tube and 316L end plug were significantly affected by welding defects. By studying the welding defects with optical microscopy (OM) and scanning electron microscopy (SEM), it is showed that the inclusions in the coating of the cladding tube enter the welding line during EBW, increasing the tendency to form cracks and leading to welding cracks; the excessively long mating surface between the cladding tube and end plug results in welding gas expansion. Through the design of orthogonal tests with influential parameters including the length of the mating surface of the end plug, the removal amount of the inner wall of the cladding tube and the interference amount on the quality characteristics, the comprehensive effects of these parameters were studied and the best matching structure was determined, which breaks through the difficulty in the welding between 316L end plug and coated 15-15Ti tube, and the welding qualification has been verified to be improved.
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Xu, Hui, Lulu Fang, Qiaofeng Ding, Yanjun Guo, Xiaohui Li, Lu Wang, and Lin Yang. "Investigation on the Micromechanisms of the Cracking of 316L Heat Exchanger Tubes." In Advances in Transdisciplinary Engineering. IOS Press, 2021. http://dx.doi.org/10.3233/atde210283.
The cracking mechanisms of 316L heat exchanger tubes employed in power station were studied using optical microscope (OM) and scanning electron microscope (SEM). It is demonstrated that the hardness value, microstructure and tensile properties of selected #1 and #2 tube samples all meet the requirements of relevant standards, but the contents of Ni and Mo element of #1 tube are slightly lower than the standard requirements. The circumferential cracks on the two samples nucleate at the corrosion pits on the inner wall of the tubes, while Cl element was detected in the corrosion products of these pits. The cracks propagate from the inner wall to the outer wall along the circumferential direction of the tube, forming a dendritic crack morphology with both transgranular and intergranular propagation characteristics. Combined with the investigation of the service condition of the heat exchanger tubes and the analysis of the experimental results, it can be concluded that the main reason for cracking is the initiation of pin-corrosion when the content of chloride ion exceeds the standard during the service of the tubes, which will induce stress corrosion cracking, causing crack expansion through the wall thickness, and finally lead to leakage of the tube. In addition, from the point of view of materials, Mo is an important element to improve the pitting resistance of materials. The content of Mo element detected in the samples is lower than the standard requirement, which is also one of the reasons for the easy pitting corrosion of the inner wall of the pipe.
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Brandt, Siegmund. "The Discovery of the Electron (1897)." In The Harvest of a Century, 16–19. Oxford University PressOxford, 1992. http://dx.doi.org/10.1093/oso/9780199544691.003.0005.
Abstract In 1897 cathode rays were known for nearly three decades. They were produced in a gas discharge and gave rise to X rays when they fell on matter, e.g., the glass wall of a discharge tube. But their nature was unknown. There was contradictory experimental evidence. Some researchers took them for charged particles, in fact for ions which were familiar from electrolysis. Perrin had determined the sign of their charge to be negative. Others, among them Heinrich Hertz, who was unable to influence the rays by an electric field and to detect a magnetic field which should be caused by the rays if they were moving charges, took them to be electromagnetic waves.
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Lawton, B., and G. Klingenberg. "Application To Very High Pressure Environments." In Transient Temperature in Engineering and Science, 442–504. Oxford University PressOxford, 1996. http://dx.doi.org/10.1093/oso/9780198562603.003.0009.
Abstract This chapter deals with the application of intrusive and non-intrusive gas and wall temperature measurement methods in high-pressure, high-temperature environments such as occur in combustion chambers subjected to pressures up to 1000 MPa, in shock-tubes, and in the hostile conditions encountered in various ballistic applications, including combustion and flow processes in the gun chamber and tube, muzzle flow and flash events, and heating effects produced during projectile flight and impact. Novel electro thermal-chemical hybrid propulsion systems combining arc discharge with chemically released propulsion energy, ram accelerators making use of hypervelocity combustion, and pure electrical projectile acceleration techniques increase the difficulty of measuring transient temperatures during the firing. Similar problems arise in other applications; for example, in shaped-charge technology and in detonation physics.
Conference papers on the topic ""wall-Tube" electrode":
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Bondarenko, Gennady G., Maxim R. Fisher, and Vladimir I. Kristya. "Simulation of electrode material deposition at the tube wall of a high-pressure mercury arc discharge lamp." In 2008 IEEE 35th International Conference on Plasma Science (ICOPS). IEEE, 2008. http://dx.doi.org/10.1109/plasma.2008.4590916.
Oh, Si-Doek, and Ho-Young Kwak. "A Study of Bubble Behavior and Boiling Heat Transfer Enhancement Under Electric Field." In ASME 1996 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/imece1996-0761.
Abstract The effect of d.c electric field on nucleate boiling heat transfer for refrigerants, R11, R113 and FC72 was investigated experimentally in a single-tube shell/tube heat exchanger by using the temperature control method of wall superheat. Also the behavior of bubble under nonuniform electric field produced by wire electrodes was studied by numerical calculation. For R11, the Electrohydrodynamic (EHD) enhancement for boiling heat transfer was observed for all ranges of the wall superheat tested. However, the enhancement in boiling heat transfer disappeared if the wall superheat exceeds 13°C for R113 and no electric field effect on the boiling heat transfer was observed for FC72. An application of approximately 5kV was enough to eliminate the boiling hysteresis for R11 and R113. Numerical study has revealed that the bubbles are forced away from the heating surface and toward the electrostatic stagnation point by the dielectrophoretic force. Such modified bubble motion turns out to promote the boiling heat transfer if one use proper electrode configuration.
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Lei, Hong, and Xiaobo Tan. "A Novel Tubular Thin-Wall IPMC Sensor Capable of Two-Dimensional Sensing: Fabrication, Characterization and Modeling." In ASME 2014 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/smasis2014-7594.
An ionic polymer-metal composite (IPMC) sensor typically consists of a thin ion-exchange membrane with electrodes on both surfaces. Such IPMC sensors respond to deflections in the beam-bending directions only and thus are considered one-dimensional. In this paper, a novel IPMC sensor capable of two-dimensional sensing is presented. This tubular thin-wall IPMC has one common inner electrode and four outer electrodes, which form four routes of common-ground outputs. The fabrication method is reported along with the sensor package. A custom-designed experimental setup, which provides dynamic tip bending with adjustable orientations and controlled bending amplitude, is used to characterize the sensor response (short-circuit current) to the 2D mechanical stimulus in air. Based on the characterization results, we further model the proposed 2D tubular IPMC sensor by treating pairs of infinitesimal portion of tube wall as one-dimensional IPMC sensors and integrating them around the tube. Experimental results show that the fabricated IPMC sensor responds to omnidirectional stimulus within the cross-section plane and the proposed model captures well the sensor responses, indicating that this tubular IPMC sensor can be potentially used for 2D flow and displacement sensing.
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Sadek, H., J. Cotton, and C. Y. Ching. "Horizontal Tube Side Convective Condensation Under an Applied DC Voltage." In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-22158.
An experimental study was performed to investigate the tube side convective condensation under an applied DC high voltage. Experiments were performed in a horizontal, single-pass, counter-current heat exchanger with a rod electrode placed along the centre of the tube. A 8 kV DC voltage was applied across the annular gap between the central electrode and the pipe wall. The experiments were performed for mass flux in the range 45 to 156 kg/m2s and average quality of 45 percent. The application of the high voltage electric field results in electric body forces at the liquid-vapor interface which extracts the liquid from the bottom stratum towards the vapour core. The application of the 8 KV DC voltage increased heat transfer and pressure drop by factor 3 and 4.5 respectively at the lowest mass flux of 45 kg/m2s. The results show that liquid extraction from the bottom liquid stratum changed the mode of heat transfer at the bottom of the tube from convective condensation into film condensation.
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Burman, Debashish, Terrence W. Simon, Uwe Kortshagen, and Douglas Ernie. "Separation Control Using Plasma Actuators: Steady Flow in Low Pressure Turbines." In ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-46807.
A Dielectric Barrier Discharge plasma actuator is operated in flow over the suction surface of a Pack-B Low Pressure Turbine (LPT) airfoil at a Reynolds number of 50,000 (based on exit velocity and suction surface length) and inlet free-stream turbulence intensity of 2.5%. Measurements of total pressure using a glass total-pressure tube are taken. Corrections for streamline displacement due to shear and wall effects are made, and comparisons with previous hot-wire measurements are used to validate data. Measurements from previous work have shown that separation control is possible without stream-wise momentum addition, by adding disturbances that cause transition in the separated shear layer. The present results are from measurements taken using a glass dielectric, with a conventional two-electrode geometry, and a new three-electrode geometry. The region of high momentum flow produced due to the presence of the actuator is found to be above the shear layer, and not at the wall. The near-suction-surface total pressure field in the trailing part of the airfoil passage and its wall-normal gradient are used to demonstrate effective prevention of flow separation using the plasma actuator.
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Caruntu, Dumitru I., and Ezequiel Juarez. "Voltage Response of Primary Resonance of Coaxial Vibrations of Electrostatically Actuated DWCNT." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-66220.
This work investigates the voltage response of electrostatically actuated of Double-Wall-Carbon-Nano-Tube (DWCNT) parallel to a ground plate (electrode). The voltage between the DWCNT and the ground plate is an Alternating Current (AC) voltage whose frequency is near half of the fundamental natural frequency of the DWCNT. Since the application of this research is mass sensing, and the low power consumption is desired, the Direct Current (DC) voltage is not included in this work. DWCNT coaxial vibrations are investigated. Numerical solutions of this problem are reported.
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Kondo, Koichi, Kenji Yoshida, Tadayoshi Matsumoto, Tomio Okawa, and Isao Kataoka. "Flow Patterns of Gas-Liquid Two-Phase Flow in Round Tube With Sudden Expansion." In 10th International Conference on Nuclear Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/icone10-22154.
Experimental studies were made on the multi-dimensional behavior of upward gas-liquid two-phase flow through the vertical round tube with an axisymmetric sudden expansion, which is one of the typical multi-dimensional channel geometry. The aims of this study are to clarify the multi-dimensional behavior of bubbly or slug flow affected by sudden expansion channel geometry, and to accumulate the experimental data for two-phase flow analysis, which is applicable to predict with appropriate accuracy the multi-dimensional its behavior. The direct observation using high-speed video camera was performed and revealed the multi-dimensional dynamic flow behavior with bubbles and gas-slug affected by the sudden expansion part (20 mm-tube to 50 mm-tube). The characteristic phenomena were observed such as bubble break-up, deformation due to the strong shear of liquid flow, or liquid micro jet penetration through the gas-slug, and so on. From these results, the flow regime map and the flow patterns at the below and above of the sudden expansion part were classified in relation to the bubble diameter. Additionally, the measurement of the void fraction profiles in the tube cross sections of sudden expansion were conducted at the different axial positions. The void fraction was measured using a point-electrode resistivity probe. The void fraction measurements in this study showed in detail that how the two phase flow develops along the direction of the downstream of the sudden expansion. In just above the sudden expansion, the void fraction distribution appeared the wall peak or the core peak in void fraction in the upstream of the sudden expansion. In the downstream of the sudden expansion, the void fraction distribution changes from a saddle shape or power-low shape into finally the saddle shape as the bubbly flow develops along the downstream of the sudden expansion. These experimental data in the sudden expansion of a vertical upward bubbly flow would become benchmark with respect to the multi-dimensional behavior of the two-phase flow analysis.
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Lu, Y. C., G. Goszczynski, and S. Ramamurthy. "Degradation of Alloy 800 Under Steam Generator Secondary Side Crevice Conditions." In 17th International Conference on Nuclear Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/icone17-75695.
Alloy 800 is the preferred steam generator (SG) tube materials for CANDU™ reactors and is also used extensively in SGs in some pressurized water reactor (PWR) systems. Degradation of Alloy 800 SG tubing has only been found in a few tubes at a limited number of stations despite the large number of SG tube operating years accumulated to date. Recently, underdeposit corrosion was detected in a few ex-service tubs removed from some CANDU SGs. Pits like wall loss of about 5% to 10% through-wall depth were found in these ex-service tubes. Evidence of intra-tubesheet cracking of Alloy 800 tubes was detected in a few European PWR SGs. There is no degradation in mechanical properties of these ex-service CANDU SG tubes. In addition, the degradation of Alloy 800 tubes observed so far is not a safety issue. However, the findings suggest that Alloy 800 tubing may have some aging degradation susceptibility after many years of service. Whether the degradation of Alloy 800 tubing is due to imperfections in its compositional or metallurgical properties inherent from manufacturing, or due to the aggressive chemistry conditions that should have been precluded by modern chemistry control strategy require clarification. Comprehensive examinations, including metallurgical examinations, orientation imaging microscopy (OIM), surface analyses and electrochemical measurements were performed on the removed ex-service CANDU SG tubes that had some underdeposit corrosion. The results were compared with a reference nuclear grade Alloy 800 tubing and with archive Alloy 800 new SG tubes from several CANDU stations. High-temperature electrochemical tests, scanning vibrating electrode Technique (SVET) measurements as well as C-ring autoclave tests were performed to determine the possible factors leading to Alloy 800 SG tubing degradation. SCC was initiated in a few C-ring specimens in the presence of artificial cold work flaws under simulated acidic SG secondary-side crevices chemistry conditions. OIM and surface analysis were also performed to characterize the degradation initiated in Alloy 800 tubing under the influence of cold work flaws. The possible factors leading to Alloy 800 SG tubing degradation under SG secondary crevices conditions are discussed.
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Yoshida, Kenji, Hidenobu Tanaka, Keizo Matsuura, and Isao Kataoka. "Studies on Gas-Phase Turbulence Modification in Vertical Upward Annular Flow." In ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45375.
Experimental and numerical studies were made to investigate the effects of wavy interface on the liquid film to gas-phase turbulence modification of air-water annular flow in a vertically arranged round tube. By using the constant temperature hotwire anemometer, time-averaged axial velocity profiles, turbulence fluctuation profiles, energy spectrum and auto-correlation coefficient for fluctuation velocity component of gas-phase axial velocity were precisely measured. The liquid film thickness was also measured by using point-electrode resistivity probe to make clear the time-averaged liquid film thickness and wave height moving on the liquid film. Direct observations using high speed video camera were also added to make clear the dynamic behavior and propergating velocity of ripple or disturbance waves on liquid film flow. Numerical simulations for gas-phase turbulence in annular flow considering the effect of wavy interface of liquid film flow were also carried out. Liquid film flow was modeled to be the wall surface roughness of interfacial wave height moving with the interfacial velocity. The roughness and moving velocity of the modeled liquid film for computational condition were provided by the present experimental results. Time-averaged velocity profiles and fluctuation velocity profiles were calculated with standard k-ε model. Numerical results were generally consistent with the experimental results obtained in the present study.
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Naito, J., M. Shikida, M. Hirota, Z. Y. Tan, and K. Sato. "Miniaturization of on-wall in-tube flexible thermal flow sensor using heat shrinkable tube." In 2008 IEEE 21st International Conference on Micro Electro Mechanical Systems. IEEE, 2008. http://dx.doi.org/10.1109/memsys.2008.4443808.
