The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
James G. Uber - One of the best experts on this subject based on the ideXlab platform.
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Calibrating Pipe Wall Demand Coefficient for Chlorine Decay in Water Distribution System
Journal of Water Resources Planning and Management, 2007Co-Authors: Feng Shang, James G. UberAbstract:Methodology and algorithm to calibrate Pipe Wall demand coefficients for chlorine decay using an input-output model framework are developed and applied. An input-output model of water quality in water distribution systems developed previously provides information that is not available using traditional simulation approaches: the various flow paths between particular input sources and output nodes, and their associated time delays and impacts on output node water quality. Such information constitutes a complete description of the input-output behavior under typical assumptions of first-order chemical decay or production reactions. With the input-output model, the chlorine concentration at output locations can be expressed explicitly as a function of the concentrations at upstream input locations, and Pipe Wall demand coefficients. Thus the sensitivity of water quality at the outputs to Wall demand coefficients can be derived analytically and calculated efficiently. The sensitivity information is also used to study uncertainty in Wall demand coefficient estimates that are caused by chlorine measurement errors.
Vaclav Matousek - One of the best experts on this subject based on the ideXlab platform.
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Pipe Wall friction in vertical sand slurry flows
Particulate Science and Technology, 2009Co-Authors: Vaclav MatousekAbstract:This article describes the results of extensive laboratory tests of vertical flows of three sand fractions (0.12, 0.37, and 1.84 mm sands) in a 150 mm Pipe. The tests revealed an interesting phenomenon of a surprisingly low contribution of the medium sand to the total friction of the mixture flow in the vertical Pipe. The frictional pressure drop in highly concentrated flows at high velocities was lower for slurries of the medium sand than for slurries of both the fine sand and the coarse sand. The solids friction at the Pipe Wall is analyzed taking into account effects of particle-particle interactions and particle-liquid interactions in the boundary layer of a vertical flow of settling slurry. The analysis suggests that the observed phenomenon is associated with the hydrodynamic liquid lift force acting on solid particles traveling near a Pipe Wall. This off-Wall force seems to be more effective for the medium sand particles than for the fine sand particles and coarse sand particles interacting with liq...
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Pipe Wall friction in vertical sand slurry flows
ASME 2005 Fluids Engineering Division Summer Meeting, 2005Co-Authors: Vaclav MatousekAbstract:Friction due to the presence of solid particles suspended in a flow is a result of processes in a relatively thin layer near the Pipe Wall. Pipe-Wall friction generated by particles in permanent contact with Pipe Wall is relatively well understood. However, very little is known about the friction deriving from sporadic contact (collisions) of particles with the Wall. This friction is a major contributor to the frictional pressure drop in many slurry Pipeline applications. The paper describes results of extensive laboratory tests of vertical flows of different sand fractions (fine, medium and coarse sands) carried out in the Laboratory of Dredging Engineering of the Delft University. In order to identify mechanisms that govern the solid-particle friction at the Pipe Wall the paper analyses friction conditions in observed vertical flows. The effects of particle-particle interactions and particle-liquid interactions on the Pipe-Wall friction are evaluated. One of the interesting phenomena observed in the laboratory was that frictional pressure drops in highly-concentrated flows at high velocities are lower for slurries of medium sand and coarse sand than for slurries of fine sand. The observed trend is believed to be associated with the liquid–lift force acting on solid particles traveling near a Pipe Wall. This off-Wall force seems to be the most effective for medium to coarse particles traveling in highly concentrated mixture in the near-Wall region. Thus pressure drops due to the presence of solids in non-stratified flows seem to be primarily produced by the combined effect of the Bagnold collisional force (force that colliding particles exert against the Pipe Wall) and liquid lift force acting on solid particles in the near-Wall zone of the slurry flow.Copyright © 2005 by ASME
Kim Kyung Woo - One of the best experts on this subject based on the ideXlab platform.
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Development of ToSPACE for Pipe Wall Thinning Management in Nuclear Power Plants
World Journal of Nuclear Science and Technology, 2019Co-Authors: Kyeong Mo Hwang, Hun Yun, Hyeok Ki Seo, Geun Young Lee, Kim Kyung WooAbstract:A number of piping components in the secondary system of nuclear power plants are exposed to aging mechanisms such as FAC (Flow-Accelerated Corrosion), cavitation, flashing, SPE (Solid Particle Erosion), LDIE (Liquid Droplet Impingement Erosion), etc. Those mechanisms may lead to thinning, leak, or rupture of the components. Due to the Pipe ruptures caused by Wall thinning in Surry unit 2 of USA in 1986 and in Mihama unit 3 of Japan in 1994, the Pipe Wall thinning management has emerged as one of the most important issues in nuclear power plants. To manage the Pipe Wall thinning in the secondary system, Korea has used a foreign program since 1996. As using the foreign country’s program for long term, it was necessary to improve from the perspective of the users. Accordingly, KEPCO-E & C has started to develop the 3D-based Pipe Wall thinning management program (ToSPACE, Total Solution for Piping And Component Engineering management) from eight years ago, and the development was successful. This paper describes the major functions included in ToSPACE program, such as 3D-based DB (Database) buildup, development of FAC and erosion evaluation theories, UT (Ultra-sonic Test) data reliability analysis, field connection with 3D, automatic establishment of long-term inspection plan, etc. ToSPACE program was developed to allow site engineers performing the selection of inspection quantity at each refueling outage, UT data reliability analysis, UT evaluation, determination of next inspection timing, identification of the inspecting and replacing components in 3D drawings, etc., to access easily.
Kyeong Mo Hwang - One of the best experts on this subject based on the ideXlab platform.
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Development of ToSPACE for Pipe Wall Thinning Management in Nuclear Power Plants
World Journal of Nuclear Science and Technology, 2019Co-Authors: Kyeong Mo Hwang, Hun Yun, Hyeok Ki Seo, Geun Young Lee, Kim Kyung WooAbstract:A number of piping components in the secondary system of nuclear power plants are exposed to aging mechanisms such as FAC (Flow-Accelerated Corrosion), cavitation, flashing, SPE (Solid Particle Erosion), LDIE (Liquid Droplet Impingement Erosion), etc. Those mechanisms may lead to thinning, leak, or rupture of the components. Due to the Pipe ruptures caused by Wall thinning in Surry unit 2 of USA in 1986 and in Mihama unit 3 of Japan in 1994, the Pipe Wall thinning management has emerged as one of the most important issues in nuclear power plants. To manage the Pipe Wall thinning in the secondary system, Korea has used a foreign program since 1996. As using the foreign country’s program for long term, it was necessary to improve from the perspective of the users. Accordingly, KEPCO-E & C has started to develop the 3D-based Pipe Wall thinning management program (ToSPACE, Total Solution for Piping And Component Engineering management) from eight years ago, and the development was successful. This paper describes the major functions included in ToSPACE program, such as 3D-based DB (Database) buildup, development of FAC and erosion evaluation theories, UT (Ultra-sonic Test) data reliability analysis, field connection with 3D, automatic establishment of long-term inspection plan, etc. ToSPACE program was developed to allow site engineers performing the selection of inspection quantity at each refueling outage, UT data reliability analysis, UT evaluation, determination of next inspection timing, identification of the inspecting and replacing components in 3D drawings, etc., to access easily.
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a study on the development of prediction system for Pipe Wall thinning caused by liquid droplet impingement erosion
Corrosion science and technology, 2013Co-Authors: Kyunghoon Kim, Yunsu Cho, Kyeong Mo HwangAbstract:The most common Pipe Wall thinning degradation mechanisms that can occur in the steam and feedwater systems are FAC (Flow Acceleration Corrosion), cavitation, flashing, and LDIE (Liquid Droplet Impingement Erosion). Among those degradation mechanisms, FAC has been investigated by many laboratories and industries. Cavitation and flashing are also protected on the piping design phase. LDIE has mainly investigated in aviation industry and turbine blade manufactures. On the other hand, LDIE has been little studied in NPP (Nuclear Power Plant) industry. This paper presents the development of prediction system for Pipe Wall thinning caused by LDIE in terms of erosion rate based on air-water ratio and material. Experiment is conducted in 3 cases of air-water ratio 0.79, 1.00, and 1.72 using the three types of the materials of A106B, SS400, and A6061. The main control parameter is the air-water ratio which is defined as the volumetric ratio of water to air (0.79, 1.00, 1.72). The experiments were performed for 15 days, and the surface morphology and hardness of the materials were examined for every 5 days. Since the spraying velocity (v) of liquid droplets and their contact area () on specimens are changed according to the air-water ratio, we analyzed the behavior of LDIE for the materials. Finally, the prediction equations(i.e. erosion rate) for LDIE of the materials were determined in the range of the air-water ratio from 0 to 2%.
Shangde Qiu - One of the best experts on this subject based on the ideXlab platform.
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Bacterial community radial-spatial distribution in biofilms along Pipe Wall in chlorinated drinking water distribution system of East China
Applied microbiology and biotechnology, 2016Co-Authors: Liu Jingqing, Hongxing Ren, Wei Wang, Yan Liu, Liping Lou, Dong-qing Cheng, He Xiaofang, Xiaoyan Zhou, Shangde QiuAbstract:Biofilms in the Pipe Wall may lead to water quality deterioration and biological instability in drinking water distribution systems (DWDSs). In this study, bacterial community radial-spatial distribution in biofilms along the Pipe Wall in a chlorinated DWDS of East China was investigated. Three Pipes of large diameter (300, 600, and 600 mm) were sampled in this DWDS, including a ductile cast iron Pipe (DCIP) with Pipe age of 11 years and two gray cast iron Pipes (GCIP) with Pipe ages of 17 and 19 years, and biofilms in the upper, middle, and lower parts of each Pipe Wall were collected. Real-time quantitative polymerase chain reaction (qPCR) and culture-based method were used to quantify bacteria. 454 pyrosequencing was used for bacterial community analysis. The results showed that the biofilm density and total solid (TS) and volatile solid (VS) contents increased gradually from the top to the bottom along the Pipe Wall. Microorganisms were concentrated in the upper and lower parts of the Pipe Wall, together accounting for more than 80 % of the total biomass in the biofilms. The bacterial communities in biofilms were significantly different in different areas of the Pipe Wall and had no strong interaction. Compared with the upper and lower parts of the Pipe Wall, the bacterial community in the middle of the Pipe Wall was distributed evenly and had the highest diversity. The 16S rRNA genes of various possible pathogens, including Escherichia coli, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Salmonella enterica, were detected in the biofilms, and the abundances of these possible pathogens were highest in the middle of the Pipe Wall among three areas. The detachment of the biofilms is the main reason for the deterioration of the water quality in DWDSs. The results of this study suggest that the biofilms in the middle of the Pipe Wall have highly potential risk for drinking water safety, which provides new ideas for the study of the microbial ecology in DWDS.
