Building Technologies Program Multi-Year Program Plan Research and Development 2008
Energy Technology Data Exchange (ETDEWEB)
None, None
2008-01-01
Building Technologies Program Multi-Year Program Plan 2008 for research and development, including residential and commercial integration, lighting, HVAC and water heating, envelope, windows, and analysis tools.
Energy Technology Data Exchange (ETDEWEB)
Smith, Brennan T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Welch, Tim [U.S. Department of Energy (DOE), Washington, DC (United States).Office of Energy Efficiency and Renewable Energy (EERE); Witt, Adam M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Stewart, Kevin M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lee, Kyutae [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); DeNeale, Scott T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bevelhimer, Mark S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Burress, Timothy A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pracheil, Brenda M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pries, Jason L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); O' Connor, Patrick W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Curd, Shelaine L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ekici, Kivanc [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States); Papanicolaou, Thanos [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States); Tsakiris, Achilleas [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States); Kutz, Benjamin [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States); Bishop, Norm [Knight Piesold, Denver, CO (United States); McKeown, Alisha [McKeown and Associates, Moberly, MO (United States); Rabon, Daniel [U.S. Department of Energy (DOE), Washington, DC (United States).Office of Energy Efficiency and Renewable Energy (EERE); Zimmerman, Gregory P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Uria Martinez, Rocio [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); McManamay, Ryan A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2017-02-01
The Multi-Year Plan for Research, Development, and Prototype Testing of Standard Modular Hydropower Technology (MYRP) presents a strategy for specifying, designing, testing, and demonstrating the efficacy of standard modular hydropower (SMH) as an environmentally compatible and cost-optimized renewable electricity generation technology. The MYRP provides the context, background, and vision for testing the SMH hypothesis: if standardization, modularity, and preservation of stream functionality become essential and fully realized features of hydropower technology, project design, and regulatory processes, they will enable previously unrealized levels of new project development with increased acceptance, reduced costs, increased predictability of outcomes, and increased value to stakeholders. To achieve success in this effort, the MYRP outlines a framework of stakeholder-validated criteria, models, design tools, testing facilities, and assessment protocols that will facilitate the development of next-generation hydropower technologies.
Research of Characteristics of Gas-liquid Two-phase Pressure Drop in Microreactor
Directory of Open Access Journals (Sweden)
Li Dan
2015-01-01
Full Text Available With the research system of nitrogen and deionized water, this paper researches the pressure drop of gas-liquid two-phase flow in the circular microchannel with an inner diameter which is respectively 0.9mm and 0.5mm, analyzes the effect of microchannel diameter on gas-liquid two-phase frictional pressure drop in the microchannel reactor, and compares with the result of frictional pressure drop and the predicting result of divided-phase flow pattern. The result shows that, the gas-liquid two-phase frictional pressure drop in the microchannel significantly increases with the decreasing microchannel diameter; Lockhart-Martinelli relationship in divided-phase flow pattern can preferably predict the gas-liquid two-phase frictional pressure drop in the microchannel, but the Tabular constant needs to be corrected.
Research of Characteristics of Gas-liquid Two-phase Pressure Drop in Microreactor
Li Dan
2015-01-01
With the research system of nitrogen and deionized water, this paper researches the pressure drop of gas-liquid two-phase flow in the circular microchannel with an inner diameter which is respectively 0.9mm and 0.5mm, analyzes the effect of microchannel diameter on gas-liquid two-phase frictional pressure drop in the microchannel reactor, and compares with the result of frictional pressure drop and the predicting result of divided-phase flow pattern. The result shows that, the gas-liquid two-...
Yee, Raymond K.; Hsu, Tai-Ran; Le, Thuy T
2013-01-01
This paper presents a unique learning and research experience for students from mechanical and electrical engineering majors in a course on senior design projects involving research and development, design and production of a proof-of-concept electric vehicle, the ZEM (Zero EMissions) vehicle. The ZEM vehicle combined positive aspects and latest technologies in electric vehicle design,solar-electric power conversions, and ergonomic human power into one affordable and environmentally sustainab...
CALCULATION ON TWO-PHASE FLOW TRANSIENTS AND THEIR EXPERIMENTAL RESEARCH
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
From basic equations of gas-liquid, solid-liquid, solid-gas two-phase flow, the calculating method on flowtransients of two-phase flow is developed by means of characteristic method. As one example, a gas-liquid flow transientis calculated and it agrees well with the experimental result. It is shown that the method is satisfactory for engineeringdemand.
RESEARCH ON THE FLOW STABILITY IN A CYLINDRICAL PARTICLE TWO-PHASE BOUNDARY LAYER
Institute of Scientific and Technical Information of China (English)
林建忠; 聂德明
2003-01-01
Based on the momentum and constitutive equations, the modified Orr-Sommerfeld equation describing the flow stability in a cylindrical particle two-phase flow was derived. For a cylindrical particle two-phase boundary layer, the neutral stability curves and critical Reynolds number were given with numerical simulation. The results show that the cylindrical particles have a suppression effect on the flow instability, the larger the particle volume fraction and the particle aspect-ratio are, the more obvious the suppression effect is.
Visualization and research of gas-liquid two phase flow structures in cylindrical channel
Directory of Open Access Journals (Sweden)
Stefański Sebastian
2017-01-01
Full Text Available Two-phase flows are commonly found in many industries, especially in systems, where efficient and correct functioning depend on specific values of flow parameters. In thermal engineering and chemical technology the most popular types of two-phase mixture are gas-liquid or liquid-vapour mixtures. Bubbles can create in flow different structures and determine diverse properties of flow (velocity of phase, void fraction, fluctuations of pressure, pipe vibrations, etc.. That type of flow is difficult to observe, especially in liquid-vapour mixture, where vapour is being made by heating the medium. Production of vapour and nucleation process are very complicated issues, which are important part of two-phase flow phenomenon. Gas-liquid flow structures were observed and described with figures, but type of structure depends on many parameters. Authors of this paper made an attempt to simulate gas-liquid flow with air and water. In the paper there was presented specific test stand built to observe two-phase flow structures, methodology of experiment and conditions which were maintained during observation. The paper presents also the structures which were observed and the analysis of results with reference to theoretical models and diagrams available in literature.
Cheng, Lixin; Bandarra Filho, Enio P; Thome, John R
2008-07-01
Nanofluids are a new class of fluids engineered by dispersing nanometer-size solid particles in base fluids. As a new research frontier, nanofluid two-phase flow and thermal physics have the potential to improve heat transfer and energy efficiency in thermal management systems for many applications, such as microelectronics, power electronics, transportation, nuclear engineering, heat pipes, refrigeration, air-conditioning and heat pump systems. So far, the study of nanofluid two-phase flow and thermal physics is still in its infancy. This field of research provides many opportunities to study new frontiers but also poses great challenges. To summarize the current status of research in this newly developing interdisciplinary field and to identify the future research needs as well, this paper focuses on presenting a comprehensive review of nucleate pool boiling, flow boiling, critical heat flux, condensation and two-phase flow of nanofluids. Even for the limited studies done so far, there are some controversies. Conclusions and contradictions on the available nanofluid studies on physical properties, two-phase flow, heat transfer and critical heat flux (CHF) are presented. Based on a comprehensive analysis, it has been realized that the physical properties of nanofluids such as surface tension, liquid thermal conductivity, viscosity and density have significant effects on the nanofluid two-phase flow and heat transfer characteristics but the lack of the accurate knowledge of these physical properties has greatly limited the study in this interdisciplinary field. Therefore, effort should be made to contribute to the physical property database of nanofluids as a first priority. Secondly, in particular, research on nanofluid two-phase flow and heat transfer in microchannels should be emphasized in the future.
Energy Technology Data Exchange (ETDEWEB)
Lim, I. C.; Seo, C. G.; Jeong, J. H.; Lee, B. H.; Choi, Y. S
2001-01-01
For the application of dynamic neutron radiography to the two-phase flow research using HANARO, several experimental items to which the radiography technique is beneficial were identified through the review of the outputs from the related researches and the discussions with experts. Also, the investigation of the equipments including the beam port, camera and converter was made and a hardware and a software for image processing were equipped. It was confirmed that the calibration curve for the attenuation of neutron beam in fluid which is required for the two-phase flow experiment could be obtained by the computer code calculation. Based on the investigation results on the equipment and the results from the measurement of BNCT beam characteristics, a high speed camera and an image intensifier will be purchased. Then, the high speed dynamic neutron radiography facility for two-phase flow experiments will be fully equipped.
Two-Phase Flow Research on the ISS for Thermal Control Applications
Motil, Brian J.
2013-01-01
With the era of full utilization of the ISS now upon us, this presentation will discuss some of the highest-priority areas for two-phase flow systems with thermal control applications. These priorities are guided by recommendations of a 2011 NRC Decadal Survey report, Recapturing a Future for Space Exploration, Life and Physical Sciences for a New Era as well as an internal NASA exercise in response to the NRC report conducted in early 2012. Many of these proposals are already in various stages of development, while others are still conceptual.
Gas-liquid countercurrent two-phase flow in a PWR hot leg: A comprehensive research review
Energy Technology Data Exchange (ETDEWEB)
Deendarlianto, E-mail: deendarlianto@ugm.ac.id [Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Safety Research, P.O. Box 510 119, D-01314 Dresden (Germany); Department of Mechanical and Industrial Engineering, Faculty of Engineering, Gadjah Mada University, Jalan Grafika No. 2, Yogyakarta 55281 (Indonesia); Hoehne, Thomas; Lucas, Dirk [Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Safety Research, P.O. Box 510 119, D-01314 Dresden (Germany); Vierow, Karen [Department of Nuclear Engineering Texas A and M University, 129 Zachry Engineering Center, 3133 TAMU College Station, TX 77843-3133 (United States)
2012-02-15
Highlights: Black-Right-Pointing-Pointer We review the scientific progress on the CCFL in a PWR hot leg. Black-Right-Pointing-Pointer It includes the experimental data, one-dimensional and CFD models in the open literatures. Black-Right-Pointing-Pointer The weak and strong points of the published works were clarified. Black-Right-Pointing-Pointer The research directions in this field were proposed. - Abstract: Research into gas-liquid countercurrent two-phase flow in a model of pressurized water reactor (PWR) hot leg has been carried out over the last several decades. An extensive experimental data base has been accumulated from these studies, leading to the development of phenomenological correlations and scaling parameters of the countercurrent flow limitation (CCFL). However, most of the proposed correlations apply under a relatively narrow range of conditions, generally limited to the test section conditions and/or geometry. Moreover the development of mechanistic models based on the underlying physical processes has been limited. In contrast to this mechanistic form of modelling, the implementation of computational fluid dynamics (CFD) techniques has also been pursued, but the considerable robust three-dimensional (3D) closure relations for this application remain an unachieved goal due to lack of detailed phenomenological knowledge and consequent application of empirical one-dimensional experimental correlations to the multidimensional problem. This paper presents a comprehensive review of research work on countercurrent gas-liquid two-phase flow in a PWR hot leg and provides direction regarding future research on this topic. In the introductory section, the problems facing current research are described. In the following sections, recent experimental as well as theoretical research achievements are overviewed. In the last section, the problems that remain unsolved are discussed, along with some concluding remarks. It was found that only limited theoretical
Ahmad, Zahoor; Hanif, Muhammad
2013-01-01
The development of estimators of population parameters based on two-phase sampling schemes has seen a dramatic increase in the past decade. Various authors have developed estimators of population using either one or two auxiliary variables. The present volume is a comprehensive collection of estimators available in single and two phase sampling. The book covers estimators which utilize information on single, two and multiple auxiliary variables of both quantitative and qualitative nature. Th...
Saito, Y.; Sekimoto, S.; Hino, M.; Kawabata, Y.
2011-09-01
To visualize boiling two-phase flow at high heat flux by using neutron radiography, a new neutron radiography facility was developed in the B-4 beam hole of KUR. The B-4 beam hole is equipped with a supermirror neutron guide tube with a characteristic wavelength of 1.2 Å, whose geometrical parameters of the guide tube are: 11.7 m total length and 10 mm wide ×74 mm high beam cross-section. The total neutron flux obtained from the KUR supermirror guide tube is about 5×10 7 n/cm 2 s with a nominal thermal output of 5 MW of KUR, which is about 100 times what is obtainable with the conventional KUR neutron radiography facility (E-2 beam hole). In this study a new imaging device, an electric power supply (1200 A, 20 V), and a thermal hydraulic loop were installed. The neutron source, the beam tube, and the radiography rooms are described in detail and the preliminary images obtained at the developed facility are shown.
Two-phase flow in refrigeration systems
Gu, Junjie; Gan, Zhongxue
2013-01-01
Two-Phase Flow in Refrigeration Systems presents recent developments from the authors' extensive research programs on two-phase flow in refrigeration systems. This book covers advanced mass and heat transfer and vapor compression refrigeration systems and shows how the performance of an automotive air-conditioning system is affected through results obtained experimentally and theoretically, specifically with consideration of two-phase flow and oil concentration. The book is ideal for university postgraduate students as a textbook, researchers and professors as an academic reference book, and b
Allen, J. L.; Creamer, E. G.; Kuehn, S. C.
2016-12-01
Short-term undergraduate research experiences (URE's) provide skill and confidence enhancement to students, but it is unclear how effective they are in comparison to a dedicated, longer-term URE. This study examines the impact of a long-term URE embedded in a sequence of five courses in the geology curriculum. It begins with a sophomore course in environmental geology, and continues through mineralogy, structural geology, and petrology, before concluding at our summer geology field camp. In this sequence, they build upon individual URE's related to the structure and petrology of fault rocks from a mid-crustal shear zone. Rather than have students engage in one or more short-term URE's, they retain the same project for two calendar years so that we can assess when and how different gains, including a more sophisticated understanding of the nature of science, begin to emerge and mature. As each student progresses, we document the longitudinal development of a diverse suite of gains including: (1) Technical and higher-order research skills, (2) personal gains such as self-identity as a scientist, and (3) communication skills. In this presentation, we describe the framework of the study and baseline observations recorded during the first year of a 2-year cohort. Using a Q-sort method, students were given a deck of 16 index cards with an educational outcome listed on each. They sorted the cards into three piles: Those that encouraged an interest in geology, those that deterred an interest, and those with no impact. Participants discussed the top cards from the negative and positive piles. The top attractors to geology are collegial relationships with faculty, the opportunity to use scientific equipment, field work, the concreteness of geology, and the availability of jobs. Factors that deter interest include hours of tedious homework, math courses, and time invested in wrong answers or failed experiments/sample preparation. Factors not yet evident include confidence in
Bioenergy Technologies Office Multi-Year Program Plan: July 2014
Energy Technology Data Exchange (ETDEWEB)
none,
2014-07-09
This is the May 2014 Update to the Bioenergy Technologies Office Multi-Year Program Plan, which sets forth the goals and structure of the Office. It identifies the research, development, demonstration, and deployment activities the Office will focus on over the next five years and outlines why these activities are important to meeting the energy and sustainability challenges facing the nation.
Multi-Year Program Plan 2011-2015
Energy Technology Data Exchange (ETDEWEB)
none,
2010-12-01
The Vehicle Technologies Multi-Year Program Plan, FY 2011 – 2015, outlines the scientific research and technologies developments for the five-year timeframe (beyond the FY 2010 base year) that need to be undertaken to help meet the Administration's goals for reductions in oil consumption and carbon emissions from the ground transport vehicle sector of the economy.
Vapor Compressor Driven Hybrid Two-Phase Loop Project
National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project will demonstrate a vapor compressor driven hybrid two-phase loop technology. The hybrid two-phase loop...
Thermo-fluid dynamics of two-phase flow
Ishii, Mamoru; Ishii, Mamoru; Ishii, M
2006-01-01
Provides a very systematic treatment of two phase flow problems from a theoretical perspectiveProvides an easy to follow treatment of modeling and code devlopemnt of two phase flow related phenomenaCovers new results of two phase flow research such as coverage of fuel cells technology.
Directory of Open Access Journals (Sweden)
Chuan Wu
2016-09-01
Full Text Available The parameters of gas-liquid two-phase flow bubbles in field coalbed methane (CBM wells are of great significance for analyzing coalbed methane output, judging faults in CBM wells, and developing gas drainage and extraction processes, which stimulates an urgent need for detecting bubble parameters for CBM wells in the field. However, existing bubble detectors cannot meet the requirements of the working environments of CBM wells. Therefore, this paper reports findings on the principles of measuring the flow pattern, velocity, and volume of two-phase flow bubbles based on conductivity, from which a new bubble sensor was designed. The structural parameters and other parameters of the sensor were then computed, the “water film phenomenon” produced by the sensor was analyzed, and the appropriate materials for making the sensor were tested and selected. After the sensor was successfully devised, laboratory tests and field tests were performed, and the test results indicated that the sensor was highly reliable and could detect the flow patterns of two-phase flows, as well as the quantities, velocities, and volumes of bubbles. With a velocity measurement error of ±5% and a volume measurement error of ±7%, the sensor can meet the requirements of field use. Finally, the characteristics and deficiencies of the bubble sensor are summarized based on an analysis of the measurement errors and a comparison of existing bubble-measuring devices and the designed sensor.
Wu, Chuan; Wen, Guojun; Han, Lei; Wu, Xiaoming
2016-09-17
The parameters of gas-liquid two-phase flow bubbles in field coalbed methane (CBM) wells are of great significance for analyzing coalbed methane output, judging faults in CBM wells, and developing gas drainage and extraction processes, which stimulates an urgent need for detecting bubble parameters for CBM wells in the field. However, existing bubble detectors cannot meet the requirements of the working environments of CBM wells. Therefore, this paper reports findings on the principles of measuring the flow pattern, velocity, and volume of two-phase flow bubbles based on conductivity, from which a new bubble sensor was designed. The structural parameters and other parameters of the sensor were then computed, the "water film phenomenon" produced by the sensor was analyzed, and the appropriate materials for making the sensor were tested and selected. After the sensor was successfully devised, laboratory tests and field tests were performed, and the test results indicated that the sensor was highly reliable and could detect the flow patterns of two-phase flows, as well as the quantities, velocities, and volumes of bubbles. With a velocity measurement error of ±5% and a volume measurement error of ±7%, the sensor can meet the requirements of field use. Finally, the characteristics and deficiencies of the bubble sensor are summarized based on an analysis of the measurement errors and a comparison of existing bubble-measuring devices and the designed sensor.
Institute of Scientific and Technical Information of China (English)
魏勃; 刘文辉; 袁林江
2014-01-01
产氢/产甲烷的两相厌氧技术在国内外受到普遍关注，如何提高产氢反应器的氢气产率和系统生物能源的高效转化成为两相厌氧研究的关键问题。总结了近年来两相厌氧技术研究和应用的最新成果，介绍了两相厌氧基质利用的运行情况、相分离的优势及两相中的优势菌种。同时，就氢/甲烷两相厌氧发酵的前景提出了建议。%Extensively attention has been paid to the two-phase anaerobic process for hydrogen and methane produc-tion in China and abroad. How to improve the hydrogen productivity of hydrogen producing reactor and efficient con-version of system bio-energy sources have become the key problem of two-phase anaerobic research. Recent ad-vances in the research on two-phase anaerobic technology and application of the newest achievement are summa-rized. The running situation of the two-phase anaerobic substrate utilization ,the superiority of phase separation and the predominant strains in two phases are introduced. Furthermore ,suggestions on the prospect concerning two-phase anaerobic fermentation for hydrogen and methane production have been made.
Natural Gas Multi-Year Program Plan
Energy Technology Data Exchange (ETDEWEB)
NONE
1997-12-01
This document comprises the Department of Energy (DOE) Natural Gas Multi-Year Program Plan, and is a follow-up to the `Natural Gas Strategic Plan and Program Crosscut Plans,` dated July 1995. DOE`s natural gas programs are aimed at simultaneously meeting our national energy needs, reducing oil imports, protecting our environment, and improving our economy. The Natural Gas Multi-Year Program Plan represents a Department-wide effort on expanded development and use of natural gas and defines Federal government and US industry roles in partnering to accomplish defined strategic goals. The four overarching goals of the Natural Gas Program are to: (1) foster development of advanced natural gas technologies, (2) encourage adoption of advanced natural gas technologies in new and existing markets, (3) support removal of policy impediments to natural gas use in new and existing markets, and (4) foster technologies and policies to maximize environmental benefits of natural gas use.
Next steps in two-phase flow: executive summary
Energy Technology Data Exchange (ETDEWEB)
DiPippo, R.
1980-09-01
The executive summary includes the following topics of discussion: the state of affairs; the fundamental governing equations; the one-dimensional mixture model; the drift-flux model; the Denver Research Institute two-phase geothermal flow program; two-phase flow pattern transition criteria; a two-fluid model under development; the mixture model as applied to geothermal well flow; DRI downwell instrumentation; two-phase flow instrumentation; the Sperry Research Corporation downhole pump and gravity-head heat exchanger systems; and the Brown University two-phase flow experimental program. (MHR)
Two-phase viscoelastic jetting
Energy Technology Data Exchange (ETDEWEB)
Yu, J-D; Sakai, S.; Sethian, J.A.
2008-12-10
A coupled finite difference algorithm on rectangular grids is developed for viscoelastic ink ejection simulations. The ink is modeled by the Oldroyd-B viscoelastic fluid model. The coupled algorithm seamlessly incorporates several things: (1) a coupled level set-projection method for incompressible immiscible two-phase fluid flows; (2) a higher-order Godunov type algorithm for the convection terms in the momentum and level set equations; (3) a simple first-order upwind algorithm for the convection term in the viscoelastic stress equations; (4) central difference approximations for viscosity, surface tension, and upper-convected derivative terms; and (5) an equivalent circuit model to calculate the inflow pressure (or flow rate) from dynamic voltage.
管道两相流冲刷腐蚀的CFD研究进展%Research Progress in CFD of Pipeline Erosion-Corrosion in Two Phase Flow
Institute of Scientific and Technical Information of China (English)
赵状; 吴玉国; 田壘; 吴栋
2014-01-01
The harm of erosion-corrosion to the oil industry was introduced, the factors affecting erosion-corrosion were discussed, such as solid phased particles factor, hydrodynamics factor, material factor, and so on. The research progress in computational fluid dynamics (CFD) method for the pipeline erosion-corrosion research was summarized;its advantages and disadvantages were pointed out. CFD numerical simulation provides a new method for study on the corrosion protection. The simulation can predict the erosion-corrosion occurring and development, which can provide reliable theoretical basis for pipeline optimization design and corrosion protection.%介绍了冲刷腐蚀对石化行业的危害，阐述了影响冲刷腐蚀的因素，即主要是流体力学因素、材料因素、固相颗粒等因素的耦合作用。对计算流体力学（CFD）方法在管道防腐中研究的进展情况进行总结，指出了研究的优点和缺点。CFD数值模拟为防腐蚀研究提供了新的方法。通过模拟结果可以预测腐蚀的发生和发展，并为管道优化设计和工艺防腐提供可靠的理论依据。
Two-Phase Technology at NASA/Johnson Space Center
Ungar, Eugene K.; Nicholson, Leonard S. (Technical Monitor)
1999-01-01
Since the baseline International Space Station (ISS) External Active Thermal Control System (EATCS) was changed from a two-phase mechanically pumped system to a single phase cascade system in the fall of 1993, two-phase EATCS research has continued at a low level at JSC. One of-the lessons of the ISS EATCS selection was that two-phase thermal control systems must have significantly lower power than comparable single phase systems to overcome their larger radiator area, larger line and fluid mass, and perceived higher technical risk. Therefore, research at JSC has concentrated on low power mechanically pumped two-phase EATCSs. In the presentation, the results of a study investigating the trade of single and two-phase mechanically pumped EATCSs for space vehicles will be summarized. The low power two-phase mechanically pumped EATCS system under development at JSC will be described in detail and the current design status of the subscale test unit will be reviewed. Also, performance predictions for a full size EATCS will be presented. In addition to the discussion of two-phase mechanically pumped EATCS development at JSC, two-phase technologies under development for biological water processing will be discussed. These biological water processor technologies are being prepared for a 2001 flight experiment and subsequent usage on the TransHab module on the International Space Station.
Bioenergy Technologies Office Multi-Year Program Plan. March 2016
Energy Technology Data Exchange (ETDEWEB)
Schwab, Amy [Bioenergy Technologies Office, Washington, DC (United States)
2016-03-01
The Bioenergy Technologies Office is one of the 10 technology development offices within the Office of Energy Efficiency and Renewable Energy at the U.S. Department of Energy. This Multi-Year Program Plan (MYPP) sets forth the goals and structure of the Bioenergy Technologies Office (the Office). It identifies the research, development, and demonstration (RD&D), and market transformation and crosscutting activities the Office will focus on over the next five years and outlines why these activities are important to meeting the energy and sustainability challenges facing the nation. This MYPP is intended for use as an operational guide to help the Office manage and coordinate its activities, as well as a resource to help communicate its mission and goals to stakeholders and the public.
Multi-year Content Analysis of User Facility Related Publications
Energy Technology Data Exchange (ETDEWEB)
Patton, Robert M [ORNL; Stahl, Christopher G [ORNL; Hines, Jayson [ORNL; Potok, Thomas E [ORNL; Wells, Jack C [ORNL
2013-01-01
Scientific user facilities provide resources and support that enable scientists to conduct experiments or simulations pertinent to their respective research. Consequently, it is critical to have an informed understanding of the impact and contributions that these facilities have on scientific discoveries. Leveraging insight into scientific publications that acknowledge the use of these facilities enables more informed decisions by facility management and sponsors in regard to policy, resource allocation, and influencing the direction of science as well as more effectively understand the impact of a scientific user facility. This work discusses preliminary results of mining scientific publications that utilized resources at the Oak Ridge Leadership Computing Facility (OLCF) at Oak Ridge National Laboratory (ORNL). These results show promise in identifying and leveraging multi-year trends and providing a higher resolution view of the impact that a scientific user facility may have on scientific discoveries.
Two Phase Technology Development Initiatives
Didion, Jeffrey R.
1999-01-01
Center research efforts applying this technique to fluid management and fluid pumping are discussed.
Development of a multi-year climate prediction model | Alexander ...
African Journals Online (AJOL)
Development of a multi-year climate prediction model. ... The available water resources in Southern Africa are rapidly approaching the limits of economic exploitation. ... that could be attributed to climate change arising from human activities.
Two-phase flow studies. Final report
Energy Technology Data Exchange (ETDEWEB)
Kestin, J.; Maeder, P.F.
1980-08-01
Progress on the following is reported: literature survey, design of two-phase flow testing facility, design of nozzle loop, thermophysical properties, design manual, and advanced energy conversion systems. (MHR)
Two-phase flow research. Phase 1: Two-phase nozzle research
Toner, S. J.
1981-07-01
Experimental performance of converging-diverging nozzles operating on air-water mixtures is presented for a wide range of parameters. Thrust measurements characterized the performance and photographic documentation was used to visually observe the off-design regimes. Thirty-six nozzle configurations were tested to determine the effects of convergence angle, area ratio, and nozzle length. In addition, the pressure ratio and mass flowrate ratio were varied to experimentally map off-design performance. The test results indicate the effects of wall friction and infer temperature and velocity differences between phases and the effect on nozzle performance. The slip ratio between the phases, gas velocity to liquid velocity, is shown to be below about 4 or 5.
Two Phase Flow and Space-Based Applications
McQuillen, John
1999-01-01
A reduced gravity environment offers the ability to remove the effect of buoyancy on two phase flows whereby density differences that normally would promote relative velocities between the phases and also alter the shape of the interface are removed. However, besides being a potent research tool, there are also many space-based technologies that will either utilize or encounter two-phase flow behavior, and as a consequence, several questions must be addressed. This paper presents some of these technologies missions. Finally, this paper gives a description of web-sites for some funding.
Two-Phase flow instrumentation for nuclear accidents simulation
Monni, G.; De Salve, M.; Panella, B.
2014-11-01
The paper presents the research work performed at the Energy Department of the Politecnico di Torino, concerning the development of two-phase flow instrumentation and of models, based on the analysis of experimental data, that are able to interpret the measurement signals. The study has been performed with particular reference to the design of power plants, such as nuclear water reactors, where the two-phase flow thermal fluid dynamics must be accurately modeled and predicted. In two-phase flow typically a set of different measurement instruments (Spool Piece - SP) must be installed in order to evaluate the mass flow rate of the phases in a large range of flow conditions (flow patterns, pressures and temperatures); moreover, an interpretative model of the SP need to be developed and experimentally verified. The investigated meters are: Turbine, Venturi, Impedance Probes, Concave sensors, Wire mesh sensor, Electrical Capacitance Probe. Different instrument combinations have been tested, and the performance of each one has been analyzed.
Study of two-phase flows in reduced gravity
Roy, Tirthankar
have been done in the past to understand the global structure of gas-liquid two-phase flows under reduced gravity conditions, using experimental setups aboard drop towers or aircrafts flying parabolic flights, detailed data on local structure of such two-phase flows are extremely rare. Hence experiments were carried out in a 304 mm inner diameter (ID) test facility on earth. Keeping in mind the detailed experimental data base that needs to be generated to evaluate two-fluid model along with IATE, ground based simulations provide the only economic path. Here the reduced gravity condition is simulated using two-liquids of similar densities (water and Therminol 59 RTM in the present case). Only adiabatic two-phase flows were concentrated on at this initial stage. Such a large diameter test section was chosen to study the development of drops to their full extent (it is to be noted that under reduced gravity conditions the stable bubble size in gas-liquid two-phase flows is much larger than that at normal gravity conditions). Twelve flow conditions were chosen around predicted bubbly flow to cap-bubbly flow transition region. Detailed local data was obtained at ten radial locations for each of three axial locations using state-of-the art multi-sensor conductivity probes. The results are presented and discussed. Also one-group as well as two-group, steady state, one-dimensional IATE was evaluated against data obtained here and by other researchers, and the results presented and discussed.
Multi-Year Program Plan - Building Regulatory Programs
Energy Technology Data Exchange (ETDEWEB)
none,
2010-10-01
This document presents DOE’s multi-year plan for the three components of the Buildings Regulatory Program: Appliance and Equipment Efficiency Standards, ENERGY STAR, and the Building Energy Codes Program. This document summarizes the history of these programs, the mission and goals of the programs, pertinent statutory requirements, and DOE’s 5-year plan for moving forward.
Multi-Year SSL Market Development Support Plan
Energy Technology Data Exchange (ETDEWEB)
Ledbetter, Marc R.
2012-05-01
This plan sets out a strategic, five year framework for guiding DOE's market development support activities for high-performance solid-state lighting (SSL) products for the U.S. general illumination market. The market development support activities described in this plan, which span federal fiscal years 2012 to 2016, are intended to affect the types of SSL general illumination products adopted by the market, to accelerate commercial adoption of those products, and to support appropriate application of those products to maximize energy savings. DOE has established aggressive FY16 goals for these activities, including goals for the types of products brought to market, the market adoption of those products, and the energy savings achieved through use of SSL products. These goals are for the combined effect of DOE's SSL market development support and R and D investment, as well as the leveraged activities of its partners. Goals include: (1) inducing the market introduction of SSL products achieving 140 lumens per Watt (lm/W) for warm white products, and 155 lm/W for cool white products, and (2) inducing sales of high-performance SSL products that achieve annual site electricity savings of 21 terawatt hours (0.25 quadrillion Btus primary energy) by FY16. To overcome identified market barriers and to achieve the above five year goals, DOE proposes to carry out the following strategy. DOE will implement a multi-year program to accelerate adoption of good quality, high performance SSL products that achieve significant energy savings and maintain or improve lighting quality. Relying on lessons learned from past emerging technology introductions, such as compact fluorescent lamps, and using newly developed market research, DOE will design its efforts to minimize the likelihood that the SSL market will repeat mistakes that greatly delayed market adoption of earlier emerging technology market introductions. To achieve the maximum effect per dollar invested, DOE will
Two-Phase Cavitating Flow in Turbomachines
Directory of Open Access Journals (Sweden)
Sandor I. Bernad
2012-11-01
Full Text Available Cavitating flows are notoriously complex because they are highly turbulent and unsteady flows involving two species (liquid/vapor with a large density difference. These features pose a unique challenge to numerical modeling works. The study briefly reviews the methodology curently employed for industrial cavitating flow simulations using the two-phase mixture model. The two-phase mixture model is evaluated and validated using benchmark problem where experimental data are available. A 3D cavitating flow computation is performed for the GAMM Francis runner. The model is able to qualitatively predict the location and extent of the 3D cavity on the blade, but further investigation are needed to quatitatively assess the accuracy for real turbomachinery cavitating flows.
Review of two-phase instabilities
Energy Technology Data Exchange (ETDEWEB)
Kang, Han Ok; Seo, Han Ok; Kang, Hyung Suk; Cho, Bong Hyun; Lee, Doo Jeong
1997-06-01
KAERI is carrying out a development of the design for a new type of integral reactors. The once-through helical steam generator is important design features. The study on designs and operating conditions which prevent flow instability should precede the introduction of one-through steam generator. Experiments are currently scheduled to understand two-phase instability, evaluate the effect of each design parameter on the critical point, and determine proper inlet throttling for the prevention of instability. This report covers general two-phase instability with review of existing studies on this topics. The general classification of two phase flow instability and the characteristics of each type of instability are first described. Special attention is paid to BWR core flow instability and once-through steam generator instability. The reactivity feedback and the effect of system parameters are treated mainly for BWR. With relation to once-through steam generators, the characteristics of convective heating and dryout point oscillation are first investigated and then the existing experimental studies are summarized. Finally chapter summarized the proposed correlations for instability boundary conditions. (author). 231 refs., 5 tabs., 47 figs
Critical thinking: a two-phase framework.
Edwards, Sharon L
2007-09-01
This article provides a comprehensive review of how a two-phase framework can promote and engage nurses in the concepts of critical thinking. Nurse education is required to integrate critical thinking in their teaching strategies, as it is widely recognised as an important part of student nurses becoming analytical qualified practitioners. The two-phase framework can be incorporated in the classroom using enquiry-based scenarios or used to investigate situations that arise from practice, for reflection, analysis, theorising or to explore issues. This paper proposes a two-phase framework for incorporation in the classroom and practice to promote critical thinking. Phase 1 attempts to make it easier for nurses to organise and expound often complex and abstract ideas that arise when using critical thinking, identify more than one solution to the problem by using a variety of cues to facilitate action. Phase 2 encourages nurses to be accountable and responsible, to justify a decision, be creative and innovative in implementing change.
Institute of Scientific and Technical Information of China (English)
朱明军; 袁惠新; 付双成; 董连东
2015-01-01
Traditional decanter centrifuge is only used to separate heavy sludge rather than floating sludge. This research developed a two-phase numerical simulation on a decanter centrifuge in separating light solid floating sludge. The three dimension software Pro-E was used to build the 3D model. The computational fluid dynamics software Fluent was applied to analyze volume fraction distribution of the solid and liquid phase as well as the effects of operating conditions and fluid parameters on flow field and separation properties. The simulation was based on Euler multiple phase flow model and RNGk-εturbulence model in a multiple coordinate reference system. The simulation results showed that the decanter centrifuge can be used to separate high density and middle-coarse particles;the fluid settling lamination was obvious and water was in the inner side while floating sludge outside of cistern;there was little effect of rotation speed discrepancy on separation properties. Rotation speed discrepancy in the range of 30—70r/min was optimal. With the increase of the feed concentration,particles’ setting velocity and separation efficiency decreased. Low setting velocity for small particles resulted in less separation efficiency and coarse particles had higher separation capabilities because of quick setting velocity.%传统的卧式螺旋卸料离心机只能分离沉渣，不能分离浮渣。本文对一种分离轻质固体浮渣的卧螺离心机进行两相数值模拟研究，使用Pro-E软件建立三维模型，应用计算流体力学软件Fluent，基于Euler多相流模型，采用RNG k-ε湍流模型及多重参考系（MRF）方法，模拟分析了这种卧螺离心机内的固液两相体积分数分布以及操作参数和物性参数对流场和分离性能的影响。模拟结果表明：此卧螺离心机适用于高浓度、中粗粒子的分离；流体沉降分层比较明显，水在液池的外层，浮渣在内层；转速差总体上对分离性
Coupling two-phase fluid flow with two-phase darcy flow in anisotropic porous media
Chen, J.
2014-06-03
This paper reports a numerical study of coupling two-phase fluid flow in a free fluid region with two-phase Darcy flow in a homogeneous and anisotropic porous medium region. The model consists of coupled Cahn-Hilliard and Navier-Stokes equations in the free fluid region and the two-phase Darcy law in the anisotropic porous medium region. A Robin-Robin domain decomposition method is used for the coupled Navier-Stokes and Darcy system with the generalized Beavers-Joseph-Saffman condition on the interface between the free flow and the porous media regions. Obtained results have shown the anisotropic properties effect on the velocity and pressure of the two-phase flow. 2014 Jie Chen et al.
Institute of Scientific and Technical Information of China (English)
何冲; 王淑红; 侯胜伟; 牛慧文
2012-01-01
The design scheme Based on AT89C52 Microcontrollers of two phase hybrid stepping motor control system is introduced, reflects two phase hybrid stepping motor control method in principle, increase the flexibility of stepping motor control system design. The control system adopts AT89C52 as controller, use BUW49 power tube of double H bridge type circuit as driver, join button control and LCD1602 display. The circuit structure of control system is simple and the thinking design is clearly. Experimental results shows that the control system operation is simple and reliable, it has strong practicability.%本文介绍了基于AT89C52单片机的两相混合式步进电机控制系统的设计方案,增加了步进电机控制系统设计的灵活性。控制系统采用AT89C52单片机作为控制器,由达林顿功率管BUW49组成的双H桥式电路作为驱动器,加入按键控制及LCD1602显示。控制系统的电路结构简单、设计思路清晰。实验表明,控制系统操作简单、运行可靠,具有较强的实用性。
Microgravity Two-Phase Flow Transition
Parang, M.; Chao, D.
1999-01-01
Two-phase flows under microgravity condition find a large number of important applications in fluid handling and storage, and spacecraft thermal management. Specifically, under microgravity condition heat transfer between heat exchanger surfaces and fluids depend critically on the distribution and interaction between different fluid phases which are often qualitatively different from the gravity-based systems. Heat transfer and flow analysis in two-phase flows under these conditions require a clear understanding of the flow pattern transition and development of appropriate dimensionless scales for its modeling and prediction. The physics of this flow is however very complex and remains poorly understood. This has led to various inadequacies in flow and heat transfer modeling and has made prediction of flow transition difficult in engineering design of efficient thermal and flow systems. In the present study the available published data for flow transition under microgravity condition are considered for mapping. The transition from slug to annular flow and from bubbly to slug flow are mapped using dimensionless variable combination developed in a previous study by the authors. The result indicate that the new maps describe the flow transitions reasonably well over the range of the data available. The transition maps are examined and the results are discussed in relation to the presumed balance of forces and flow dynamics. It is suggested that further evaluation of the proposed flow and transition mapping will require a wider range of microgravity data expected to be made available in future studies.
Institute of Scientific and Technical Information of China (English)
苏亮; 宋志平; 王宝寿; 丁力
2013-01-01
文章利用电阻层析成像技术进行了空隙率的静态测试，并将测试数据、COMSOL计算数据与MATLAB编程数据进行了比较。在验证了所编MATLAB程序的正确性后，将其应用于气液两相流空隙率测试。为了避免电阻层析成像技术在气液两相流空隙率测试中图像处理的难题，文中针对三种典型的气液两相流流型，建立了各自流型下的空隙率与截面平均电导率之间的函数关系。具体试验时，可将试验测试数据导入所编MATLAB程序中，得到截面平均电导率，并将此值代入对应流型下的空隙率与截面平均电导率之间的函数关系式中，进而得到空隙率值。该文提出的方法能够解决气液两相流空隙率测试的难点，具有较大的工程应用价值。%The void fraction is measured by electrical resistance tomography technology and the data mea-sured by experiment is compared with calculating data by COMSOL and simulating data by MATLAB. The MATLAB program is used to measure the void fraction of gas-liquid two-phase flow after it is proved true. The functional equation between void fraction and sectional average conductivity is established according to three different types of flow pattern in order to avoid the difficulity in image processing of gas-liquid two-phase flow. For one experiment, the measured data is imported into MATLAB program to obtain the val-ue of sectional average conductivity and then plug the value of sectional average conductivity into the func-tional equation above, the value of void fraction is obtained. The method proposed in this paper can solve the problem in void fraction measurement of gas-liquid two-phase flow and is of great engineering value.
Institute of Scientific and Technical Information of China (English)
陈飞; 孙斌; 王二朋; 白宏震
2012-01-01
为了研究文丘里管、多孔孔板和V型内锥3种功能节流式流量计测量得到的气液两相流动态特性,采用高频差压传感器获取不同流型下的动态差压信号,利用AOK时频谱对差压信号进行分析,通过时频谱图研究不同流型下信号的时变特征.通过对典型的泡状流、弹状流、塞状流信号的实验分析表明:文丘里管在塞泡流存在较强的噪声信号,V型内锥在泡状流存在较强的噪声信号.多孔孔板具有很好的降噪效果,且多孔孔板能均衡信号的能量,信号能量分布较均衡.3种节流仪表均能很好地描述两相流定态特性,能够用于两相流流型识别及其它参数测量.%In this paper, the dynamic characteristics in the measurement of gas-liquid two-phase flow with different throttle flow-meters including Venturi tube, multi-hole orifices plate and V-shaped inner conical were studied. Firstly, high-frequency pressure sensor is adopted to get the dynamic differential pressure signal under different flow patterns. Secondly, the AOK spectrum is introduced and used in the analysis of the dynamic differential pressure signal. Then, the time-varying characteristic of dynamic differential pressure signal in different flow patterns is studied by estimating the time-frequency spectrum. It is indicated by experiments with the typical bubbly flow, slug flow and plug flow signals that Venturi tube has strong noise component at plug flow, and V-shaped inner cone has strong noise component at bubbly flow, multi-hole orifices plate is good at restraining noise. Furthermore, the multi-hole orifices plate can perform fine rectifying function and balance the energy of signals, which makes the energy distribution of signals more proportionate. The three kinds of throttling flow-meter can well describe the dynamic characteristics of gas-liquid two-phase flow, which can be used in the two-phase flow pattern I-dentification and characteristic variables
Droplet Manipulations in Two Phase Flow Microfluidics
Directory of Open Access Journals (Sweden)
Arjen M. Pit
2015-11-01
Full Text Available Even though droplet microfluidics has been developed since the early 1980s, the number of applications that have resulted in commercial products is still relatively small. This is partly due to an ongoing maturation and integration of existing methods, but possibly also because of the emergence of new techniques, whose potential has not been fully realized. This review summarizes the currently existing techniques for manipulating droplets in two-phase flow microfluidics. Specifically, very recent developments like the use of acoustic waves, magnetic fields, surface energy wells, and electrostatic traps and rails are discussed. The physical principles are explained, and (potential advantages and drawbacks of different methods in the sense of versatility, flexibility, tunability and durability are discussed, where possible, per technique and per droplet operation: generation, transport, sorting, coalescence and splitting.
Two phase decision algorithm of replica allocation
Institute of Scientific and Technical Information of China (English)
Zuo Chaoshu; Liu Xinsong; Wang Zheng; Li Yi
2006-01-01
In distributed parallel server system, location and redundancy of replicas have great influence on availability and efficiency of the system. In order to improve availahility and efficiency of the system, two phase decision algorithm of replica allocation is proposed. The algorithm which makes use of auto-regression model dynamically predicts the future count of READ and WRITE operation, and then determines location and redundancy of replicas by considering availability, CPU and bands of the network. The algorithm can not only ensure the requirement of availability, but also reduce the system resources consumed by all the operations in a great scale. Analysis and test show that communication complexity and time complexity of the algorithm satisfy O( n ), resource optimizing scale increases with the increase of READ count.
Multi-year expansion planning of large transmission networks
Energy Technology Data Exchange (ETDEWEB)
Binato, S.; Oliveira, G.C. [Centro de Pesquisas de Energia Eletrica (CEPEL), Rio de Janeiro, RJ (Brazil)
1994-12-31
This paper describes a model for multi-year transmission network expansion to be used in long-term system planning. The network is represented by a linearized (DC) power flow and, for each year, operation costs are evaluated by a linear programming (LP) based algorithm that provides sensitivity indices for circuit reinforcements. A Backward/Forward approaches is proposed to devise an expansion plan over the study period. A case study with the southeastern Brazilian system is presented and discussed. (author) 18 refs., 5 figs., 1 tab.
Two-phase flow experimental studies in micro-models (Utrecht Studies in Earth Sciences 034)
Karadimitriou, N.K.
2013-01-01
The aim of this research project was to put more physics into theories of two-phase flow. The significance of including interfacial area as a separate variable in two-phase flow and transport models was investigated. In order to investigate experimentally the significance of the inclusion of interfa
Chiaramonte, Francis; Motil, Brian; McQuillen, John
2014-01-01
The Two-phase Heat Transfer International Topical Team consists of researchers and members from various space agencies including ESA, JAXA, CSA, and RSA. This presentation included descriptions various fluid experiments either being conducted by or planned by NASA for the International Space Station in the areas of two-phase flow, flow boiling, capillary flow, and crygenic fluid storage.
Institute of Scientific and Technical Information of China (English)
张勇健; 苍大强; 徐栋
2011-01-01
研究了湍流条件下固-液两相流体对流换热系数的增加值.实验比较了纳米级和微米级颗粒对基液对流换热系数变化的影响,加入固体颗粒可以有效地改善流体的换热能力.实验结果发现纳米级颗粒悬浮液的对流换热系数提高较微米级颗粒悬浮液更为明显,对流换热系数随着管式加热炉温度的升高略有增大,同时探讨了纳米流体换热效果较好的因为.%The convective heat transfer enhancement of solid-liquid two phase flow in turbulence was mainly investigated.The experiment compared the influence of nano-particles and micro-particles on convective heat transfer coefficient of base fluid and proved that addition solid particles could improve the fluid heat transfer effectively.The results showed compared with micro-particles suspension, nanofluid could enhance the convective heat transfer more effectively, and which increase slightly with the temperature raised of tube furnace.The reason of nano-fluid better heat transfer also was discussed.
Moerk, J. Steven (Inventor); Youngquist, Robert C. (Inventor); Werlink, Rudy J. (Inventor)
1999-01-01
A quality and/or flow meter employs a capacitance probe assembly for measuring the dielectric constant of flow stream, particularly a two-phase flow stream including liquid and gas components.ne dielectric constant of the flow stream varies depending upon the volume ratios of its liquid and gas components, and capacitance measurements can therefore be employed to calculate the quality of the flow, which is defined as the volume ratio of liquid in the flow to the total volume ratio of gas and liquid in the flow. By using two spaced capacitance sensors, and cross-correlating the time varying capacitance values of each, the velocity of the flow stream can also be determined. A microcontroller-based processing circuit is employed to measure the capacitance of the probe sensors.The circuit employs high speed timer and counter circuits to provide a high resolution measurement of the time interval required to charge each capacitor in the probe assembly. In this manner, a high resolution, noise resistant, digital representation of each of capacitance value is obtained without the need for a high resolution A/D converter, or a high frequency oscillator circuit. One embodiment of the probe assembly employs a capacitor with two ground plates which provide symmetry to insure that accurate measurements are made thereby.
Institute of Scientific and Technical Information of China (English)
任美鹏; 李相方; 徐大融; 尹邦堂
2012-01-01
常规钻井返出管线敞口，钻井液在返出管线中流动为非满管流动，小气侵量时，泥浆池液面变化不明显，检测装置无法测量液面变化，钻井液返出流量无法测量或者测量误差较大，无法感知小流量差的变化。本文基于气液两相流理论建立了井筒气液两相流参数与井口溢流速度的关系模型，计算表明气侵速度越大，气泡运移距井口越近，井口溢流速度越大。并以空气和钻井液（非牛顿流体）为介质，基于VOF多相流模型，模拟了钻井液返出流量变化时气液界面变化情况，分析了纯钻井液和不同含气率钻井液在返出管线流动时液面变化特征，得出纯钻井液流动时喇叭口处液面变化最明显，优化液面检测装置安装在喇叭上，更能准确及时地检测液面变化早期发现溢流，进气速度影响返出管线钻井液液面稳定性。%Because of the opening of mud return pipe, the pipe is not full of drilling mud. When gas kick is little, the change of pit gain was indistinct, so the detection device would not be available to reflect fluid level. According the undetectable or incorrect disadvantages and default of kick detection, this paper has established the relationship between wellhead kick velocity and gas-liquid two phase flow in wellhole based on the theory of two phase flow, and the result shows that the greater of the velocity of kick, the greater of wellhead kick velocity, and the wellhead kick velocity becomes also greater with the upper movement of bubble. Based on air and mud (non-Newtonian fluids) medium and VOF method, this paper has analyzed characters of mud level of return pipe with pure mud and different void fraction. According to the results, the mud level is most obvious in the bell nipple when the fluid is pure mud. When the device is installed on the bell mouth, pit level change monitoring would be more accurate and without delay to detect early kick
Building Technologies Program Multi-Year Program Plan Program Overview 2008
Energy Technology Data Exchange (ETDEWEB)
None, None
2008-01-01
Building Technologies Program Multi-Year Program Plan Program Overview 2008, including market overview and federal role, program vision, mission, design and structure, and goals and multi-year targets.
Pressure Loss across Tube Bundles in Two-phase Flow
Energy Technology Data Exchange (ETDEWEB)
Sim, Woo Gun; Banzragch, Dagdan [Hannam Univ., Daejon (Korea, Republic of)
2016-03-15
An analytical model was developed by Sim to estimate the two-phase damping ratio for upward two-phase flow perpendicular to horizontal tube bundles. The parameters of two-phase flow, such as void fraction and pressure loss evaluated in the model, were calculated based on existing experimental formulations. However, it is necessary to implement a few improvements in the formulations for the case of tube bundles. For the purpose of the improved formulation, we need more information about the two-phase parameters, which can be found through experimental test. An experiment is performed with a typical normal square array of cylinders subjected to the two-phase flow of air-water in the tube bundles, to calculate the two-phase Euler number and the two-phase friction multiplier. The pitch-to-diameter ratio is 1.35 and the diameter of cylinder is 18mm. Pressure loss along the flow direction in the tube bundles is measured with a pressure transducer and data acquisition system to calculate the two-phase Euler number and the two-phase friction multiplier. The void fraction model by Feenstra et al. is used to estimate the void fraction of the two-phase flow in tube bundles. The experimental results of the two phase friction multiplier and two-phase Euler number for homogeneous and non-homogeneous two-phase flows are compared and evaluated against the analytical results given by Sim's model.
Institute of Scientific and Technical Information of China (English)
王治武; 张洋; 陈星谷; 郑龙席; 卢杰
2015-01-01
为了掌握爆震频率对两相多循环爆震波起爆特性的影响规律,对采用高能火花塞点火的吸气式脉冲爆震发动机不同爆震频率下的起爆过程进行了试验研究,对比分析了不同频率下的P DE沿程压力分布,讨论了起爆特征参数,如DDT转变距离、着火延迟时间、DDT转变时间和起爆时间等,与爆震频率的变化关系. 试验结果显示,随着工作频率增加,爆燃燃烧向爆震燃烧的转变有所加快. 工作频率对着火延迟时间和爆震形成时间影响较大,对DDT时间影响很小,随着频率增加,着火延迟时间和爆震形成时间逐渐减小,而DDT时间略有下降.%In order to grasp the influence of detonation frequency on the initiation characteristics of two?phase multi?cycle detonation, an air?breathing pulse detonation engine mockup with high energy spark plug was designed and the experiments of detonation initiation process at different operating frequencies were carried out. The pressure dis?tributions along the length of PDE mockup at different operating frequencies were contrasted and analyzed. Mean?while , the relationship between the detonation frequency on the one hand and the initiation characteristic parameters on the other hand was discussed, such as the DDT transition distance, ignition delay time, DDT transition time and detonation initiation time and so on. The experimental results indicated that deflagration to detonation transition in?creased with increasing operating frequency. The operating frequency had obvious effect on ignition delay time and the detonation initiation time but had a weak effect on DDT time. As the operating frequency increased, the ignition delay time and detonation initiation time decreased linearly, while the DDT time declined slightly.
Tank waste remediation system multi-year work plan
Energy Technology Data Exchange (ETDEWEB)
1994-09-01
The Tank Waste Remediation System (TWRS) Multi-Year Work Plan (MYWP) documents the detailed total Program baseline and was constructed to guide Program execution. The TWRS MYWP is one of two elements that comprise the TWRS Program Management Plan. The TWRS MYWP fulfills the Hanford Site Management System requirement for a Multi-Year Program Plan and a Fiscal-Year Work Plan. The MYWP addresses program vision, mission, objectives, strategy, functions and requirements, risks, decisions, assumptions, constraints, structure, logic, schedule, resource requirements, and waste generation and disposition. Sections 1 through 6, Section 8, and the appendixes provide program-wide information. Section 7 includes a subsection for each of the nine program elements that comprise the TWRS Program. The foundation of any program baseline is base planning data (e.g., defendable product definition, logic, schedules, cost estimates, and bases of estimates). The TWRS Program continues to improve base data. As data improve, so will program element planning, integration between program elements, integration outside of the TWRS Program, and the overall quality of the TWRS MYWP. The MYWP establishes the TWRS baseline objectives to store, treat, and immobilize highly radioactive Hanford waste in an environmentally sound, safe, and cost-effective manner. The TWRS Program will complete the baseline mission in 2040 and will incur costs totalling approximately 40 billion dollars. The summary strategy is to meet the above objectives by using a robust systems engineering effort, placing the highest possible priority on safety and environmental protection; encouraging {open_quotes}out sourcing{close_quotes} of the work to the extent practical; and managing significant but limited resources to move toward final disposition of tank wastes, while openly communicating with all interested stakeholders.
Reynolds transport theorem for a two-phase flow
Collado, Francisco J.
2007-01-01
Transport equations for one-dimensional (1d), steady, two-phase flow have been proposed based on the fact that if the phases have different velocities, they cannot cover the same distance (the control volume length) in the same time. Thus, working in the same control volume for the two phases, the time scales of the phases have to be different. From this approach, transport balances for 1D, steady, two-phase flow have been already derived, supplying acceptable correlations for two-phase flow. Here, based on the strict application of the Reynolds transport theorem, general transport balances for two-phase flow are suggested.
Experimental and numerical investigation on two-phase flow instabilities
Energy Technology Data Exchange (ETDEWEB)
Ruspini, Leonardo Carlos
2013-03-01
Two-phase flow instabilities are experimentally and numerically studied within this thesis. In particular, the phenomena called Ledinegg instability, density wave oscillations and pressure drop oscillations are investigated. The most important investigations regarding the occurrence of two-phase flow instabilities are reviewed. An extensive description of the main contributions in the experimental and analytical research is presented. In addition, a critical discussion and recommendations for future investigations are presented. A numerical framework using a hp-adaptive method is developed in order to solve the conservation equations modelling general thermo-hydraulic systems. A natural convection problem is analysed numerically in order to test the numerical solver. Moreover, the description of an adaptive strategy to solve thermo-hydraulic problems is presented. In the second part of this dissertation, a homogeneous model is used to study Ledinegg, density wave and pressure drop oscillations phenomena numerically. The dynamic characteristics of the Ledinegg (flow excursion) phenomenon are analysed through the simulation of several transient examples. In addition, density wave instabilities in boiling and condensing systems are investigated. The effects of several parameters, such as the fluid inertia and compressibility volumes, on the stability limits of Ledinegg and density wave instabilities are studied, showing a strong influence of these parameters. Moreover, the phenomenon called pressure drop oscillations is numerically investigated. A discussion of the physical representation of several models is presented with reference to the obtained numerical results. Finally, the influence of different parameters on these phenomena is analysed. In the last part, an experimental investigation of these phenomena is presented. The designing methodology used for the construction of the experimental facility is described. Several simulations and a non
Two phase continuous digestion of solid manure on-farm
Energy Technology Data Exchange (ETDEWEB)
Schaefer, W.; Lehto, M. [MTT Agrifood Research Finland, Vihti (Finland). Animal Production Research; Evers, L.; Granstedt, A. [Biodynamic Research Inst., Jaerna (Sweden)
2007-07-01
Present commercially available biogas plants are mainly suitable for slurry and co-substrates. Cattle, horse and poultry farms using a solid manure chain experience a crucial competitive disadvantage, because conversion to slurry technology requires additional investments. Based on the technological progress of anaerobic digestion of municipal solid waste, so called 'dry fermentation' prototype plants were developed for anaerobic digestion of organic material containing 15-50% total solids (Hoffman, 2001). These plants show added advantages compared to slurry digestion plants: Less reactor volume, less process energy, less transport capacity, less odour emissions. On-farm research (Gronauer and Aschmann, 2004; Kusch and Oechsner, 2004) and prototype research (Linke, 2004) on dry fermentation in batch reactors show that loading and discharging of batch reactors remains difficult and/or time-consuming compared to slurry reactors. Additionally a constant level of gas generation requires offset operation of several batch reactors. Baserga et al. (1994) developed a pilot plant of 9.6 m{sup 3} capacity for continuous digestion of solid beef cattle manure on-farm. However, on-farm dry fermentation plants are not common and rarely commercially available. We assume that lack of tested technical solutions and scarceness of on-farm research results are the main reason for low acceptance of dry fermentation technology on-farm. We report about an innovative two phase farm-scale biogas plant. The plant continuously digests dairy cattle manure and organic residues of the farm and the surrounding food processing units. The two phase reactor technology was chosen for two reasons: first it offers the separation of a liquid fraction and a solid fraction for composting after hydrolysis and secondly the methanation of the liquid fraction using fixed film technology results in a very short hydraulic retention time, reduction in reactor volume, and higher methane content of the
CHOOSING STRUCTURE-DEPENDENT DRAG COEFFICIENT IN MODELING GAS-SOLID TWO-PHASE FLOW
Institute of Scientific and Technical Information of China (English)
Ning Yang; Wei Wang; Wei Ge; Jinghai Li
2003-01-01
@@ Introduction Gas-solid two-phase flow is often encountered in chemical reactors for the process industry. For industrial users, design, scale-up, control and optimization for these reactors require a good understanding of the hydrodynamics of gas-solid two-phase flow. For researchers, exploration and prediction of the complex phenomena call for a good comprehension of the heterogeneous structure and of the dominant mechanisms of gas-solid and solid-solid interactions.
Multi-year predictability in a coupled general circulation model
Energy Technology Data Exchange (ETDEWEB)
Power, Scott; Colman, Rob [Bureau of Meteorology Research Centre, Melbourne, VIC (Australia)
2006-02-01
Multi-year to decadal variability in a 100-year integration of a BMRC coupled atmosphere-ocean general circulation model (CGCM) is examined. The fractional contribution made by the decadal component generally increases with depth and latitude away from surface waters in the equatorial Indo-Pacific Ocean. The relative importance of decadal variability is enhanced in off-equatorial ''wings'' in the subtropical eastern Pacific. The model and observations exhibit ''ENSO-like'' decadal patterns. Analytic results are derived, which show that the patterns can, in theory, occur in the absence of any predictability beyond ENSO time-scales. In practice, however, modification to this stochastic view is needed to account for robust differences between ENSO-like decadal patterns and their interannual counterparts. An analysis of variability in the CGCM, a wind-forced shallow water model, and a simple mixed layer model together with existing and new theoretical results are used to improve upon this stochastic paradigm and to provide a new theory for the origin of decadal ENSO-like patterns like the Interdecadal Pacific Oscillation and Pacific Decadal Oscillation. In this theory, ENSO-driven wind-stress variability forces internal equatorially-trapped Kelvin waves that propagate towards the eastern boundary. Kelvin waves can excite reflected internal westward propagating equatorially-trapped Rossby waves (RWs) and coastally-trapped waves (CTWs). CTWs have no impact on the off-equatorial sub-surface ocean outside the coastal wave guide, whereas the RWs do. If the frequency of the incident wave is too high, then only CTWs are excited. At lower frequencies, both CTWs and RWs can be excited. The lower the frequency, the greater the fraction of energy transmitted to RWs. This lowers the characteristic frequency of variability off the equator relative to its equatorial counterpart. Both the eastern boundary interactions and the accumulation of
Estimating Global Cropland Extent with Multi-year MODIS Data
Directory of Open Access Journals (Sweden)
Christopher O. Justice
2010-07-01
Full Text Available This study examines the suitability of 250 m MODIS (MODerate Resolution Imaging Spectroradiometer data for mapping global cropland extent. A set of 39 multi-year MODIS metrics incorporating four MODIS land bands, NDVI (Normalized Difference Vegetation Index and thermal data was employed to depict cropland phenology over the study period. Sub-pixel training datasets were used to generate a set of global classification tree models using a bagging methodology, resulting in a global per-pixel cropland probability layer. This product was subsequently thresholded to create a discrete cropland/non-cropland indicator map using data from the USDA-FAS (Foreign Agricultural Service Production, Supply and Distribution (PSD database describing per-country acreage of production field crops. Five global land cover products, four of which attempted to map croplands in the context of multiclass land cover classifications, were subsequently used to perform regional evaluations of the global MODIS cropland extent map. The global probability layer was further examined with reference to four principle global food crops: corn, soybeans, wheat and rice. Overall results indicate that the MODIS layer best depicts regions of intensive broadleaf crop production (corn and soybean, both in correspondence with existing maps and in associated high probability matching thresholds. Probability thresholds for wheat-growing regions were lower, while areas of rice production had the lowest associated confidence. Regions absent of agricultural intensification, such as Africa, are poorly characterized regardless of crop type. The results reflect the value of MODIS as a generic global cropland indicator for intensive agriculture production regions, but with little sensitivity in areas of low agricultural intensification. Variability in mapping accuracies between areas dominated by different crop types also points to the desirability of a crop-specific approach rather than attempting
Response of two-phase droplets to intense electromagnetic radiation
Spann, James F.; Maloney, Daniel J.; Lawson, William F.; Casleton, Kent H.
1993-04-01
The behavior of two-phase droplets subjected to high intensity radiation pulses is studied. Droplets are highly absorbing solids in weakly absorbing liquid medium. The objective of the study was to define heating thresholds required for causing explosive boiling and secondary atomization of the fuel droplet. The results point to mechanisms for energy storage and transport in two-phase systems.
Two Phases of Coherent Structure Motions in Turbulent Boundary Layer
Institute of Scientific and Technical Information of China (English)
LIU Jian-Hua; JIANG Nan
2007-01-01
Two phases of coherent structure motion are acquired after obtaining conditional phase-averaged waveforms for longitudinal velocity of coherent structures in turbulent boundary layer based on Harr wavelet transfer. The correspondences of the two phases to the two processes (i.e. ejection and sweep) during a burst are determined.
Emerging Two-Phase Cooling Technologies for Power Electronic Inverters
Energy Technology Data Exchange (ETDEWEB)
Hsu, J.S.
2005-08-17
Oak Ridge National Laboratory (ORNL) is leading the research on a novel floating refrigerant loop that cools high-power electronic devices and the motor/generator with very low cooling energy. The loop can be operated independently or attached to the air conditioning system of the vehicle to share the condenser and other mutually needed components. The ability to achieve low cooling energy in the floating loop is attributable to the liquid refrigerant operating at its hot saturated temperature (around 50 C+). In an air conditioning system, the liquid refrigerant is sub-cooled for producing cool air to the passenger compartment. The ORNL floating loop avoids the sub-cooling of the liquid refrigerant and saves significant cooling energy. It can raise the coefficient of performance (COP) more than 10 fold from that of the existing air-conditioning system, where the COP is the ratio of the cooled power and the input power for dissipating the cooled power. In order to thoroughly investigate emerging two-phase cooling technologies, ORNL subcontracted three university/companies to look into three leading two-phase cooling technologies. ORNL's assessments on these technologies are summarized in Section I. Detailed descriptions of the reports by the three university/companies (subcontractors) are in Section II.
Oppermann, Sebastian; Stein, Florian; Kragl, Udo
2011-02-01
The development of biotechnological processes using novel two-phase systems based on molten salts known as ionic liquids (ILs) got into the focus of interest. Many new approaches for the beneficial application of the interesting solvent have been published over the last years. ILs bring beneficial properties compared to organic solvents like nonflammability and nonvolatility. There are two possible ways to use the ILs: first, the hydrophobic ones as a substitute for organic solvents in pure two-phase systems with water and second, the hydrophilic ones in aqueous two-phase systems (ATPS). To effectively utilise IL-based two-phase systems or IL-based ATPS in biotechnology, extensive experimental work is required to gain the optimal system parameters to ensure selective extraction of the product of interest. This review will focus on the most actual findings dealing with the basic driving forces for the target extraction in IL-based ATPS as well as presenting some selected examples for the beneficial application of ILs as a substitute for organic solvents. Besides the research focusing on IL-based two-phase systems, the "green aspect" of ILs, due to their negligible vapour pressure, is widely discussed. We will present the newest results concerning ecotoxicity of ILs to get an overview of the state of the art concerning ILs and their utilisation in novel two-phase systems in biotechnology.
Thermo-Fluid Dynamics of Two-Phase Flow
Ishii, Mamrou
2011-01-01
"Thermo-fluid Dynamics of Two-Phase Flow, Second Edition" is focused on the fundamental physics of two-phase flow. The authors present the detailed theoretical foundation of multi-phase flow thermo-fluid dynamics as they apply to: Nuclear reactor transient and accident analysis; Energy systems; Power generation systems; Chemical reactors and process systems; Space propulsion; Transport processes. This edition features updates on two-phase flow formulation and constitutive equations and CFD simulation codes such as FLUENT and CFX, new coverage of the lift force model, which is of part
Critical transport velocity in two-phase, horizontal pipe flow
Energy Technology Data Exchange (ETDEWEB)
Sommerville, D. (U.S. Army Chemical Research, Development and Engineering Center, Aberdeen Proving Grounds, MD (US))
1991-02-01
This paper reports on the suspension of solid particles or entrainment of liquid droplets in two- phase flow. Theoretical and empirical relationships have been derived for both instances without any consideration to the similarities between the two. However, a general relation for two-phase flow is desirable since there are systems that cannot be readily defined due to the dual (solid/liquid) nature of the transported material, such as colloids, pulp, slurries, and sludge. Using turbulence theory, one general equation can be derived to predict critical transport velocities for two-phase horizontal flow.
What types of investors generate the two-phase phenomenon?
Ryu, Doojin
2013-12-01
We examine the two-phase phenomenon described by Plerou, Gopikrishnan, and Stanley (2003) [1] in the KOSPI 200 options market, one of the most liquid options markets in the world. By analysing a unique intraday dataset that contains information about investor type for each trade and quote, we find that the two-phase phenomenon is generated primarily by domestic individual investors, who are generally considered to be uninformed and noisy traders. In contrast, our empirical results indicate that trades by foreign institutions, who are generally considered informed and sophisticated investors, do not exhibit two-phase behaviour.
Tunable two-phase coexistence in half-doped manganites
Indian Academy of Sciences (India)
P Chaddah; A Banerjee
2008-02-01
We discuss our very interesting experimental observation that the low-temperature two-phase coexistence in half-doped manganites is multi-valued (at any field) in that we can tune the coexisting antiferromagnetic-insulating (AF-I) and the ferromagnetic-metallic (FM-M) phase fractions by following different paths in (; ) space. We have shown experimentally that the phase fraction, in this two-phase coexistence, can take continuous infinity of values. All but one of these are metastable, and two-phase coexistence is not an equilibrium state.
Smith, Mike U.; Scharmann, Lawrence
2008-01-01
This investigation delineates a multi-year action research agenda designed to develop an instructional model for teaching the nature of science (NOS) to preservice science teachers. Our past research strongly supports the use of explicit reflective instructional methods, which includes Thomas Kuhn's notion of learning by ostention and treating…
Time dependent two phase flows in Magnetohydrodynamics: A ...
African Journals Online (AJOL)
Journal of the Nigerian Association of Mathematical Physics ... Open Access DOWNLOAD FULL TEXT Subscription or Fee Access. Time dependent two phase flows in Magnetohydrodynamics: A Greens function approach. BK Jha, HM Jibril ...
Gravity Independence of Microchannel Two-Phase Flow Project
National Aeronautics and Space Administration — Most of the amassed two-phase flow and heat transfer knowledge comes from experiments conducted in Earth’s gravity. Space missions span varying gravity levels,...
Vapor Compressor Driven Hybrid Two-Phase Loop Project
National Aeronautics and Space Administration — The Phase I project successfully demonstrated the feasibility of the vapor compression hybrid two-phase loop (VCHTPL). The test results showed the high...
TWO PHASE FLOW SPLIT MODEL FOR PARALLEL CHANNELS
African Journals Online (AJOL)
Ifeanyichukwu Onwuka
The equations are solved using the Broyden'smethod ... channel system subjected to a two-phase flow transient, and the results have been very .... system pressure, the heat addition rates inside ... three dimensional flows in the LP.
Particle modulations to turbulence in two-phase round jets
Institute of Scientific and Technical Information of China (English)
Bing Wang; Huiqiang Zhang; Yi Liu; Xiaofen Yan; Xilin Wang
2009-01-01
The particle modulations to turbulence in round jets were experimentally studied by means of two-phase velocity measurements with Phase Doppler Anemometer (PDA). Laden with very large particles, no significant attenuations of turbulence intensities were measured in the far-fields, due to small two-phase slip velocities and particle Reynolds number. The gas-phase turbulence is enhanced by particles in the near-fields, but it is significantly attenuated by the small particles in the far-fields. The smaller particles have a more profound effect on the attenuation of turbulence intensities. The enhancements or attenuations of turbulence intensities in the far-fields depends on the energy production, transport and dissipation mechanisms between the two phases, which are determined by the particle prop-erties and two-phase velocity slips. The non-dimensional parameter CTI is introduced to represent the change of turbulence intensity.
Transient two-phase performance of LOFT reactor coolant pumps
Energy Technology Data Exchange (ETDEWEB)
Chen, T.H.; Modro, S.M.
1983-01-01
Performance characteristics of Loss-of-Fluid Test (LOFT) reactor coolant pumps under transient two-phase flow conditions were obtained based on the analysis of two large and small break loss-of-coolant experiments conducted at the LOFT facility. Emphasis is placed on the evaluation of the transient two-phase flow effects on the LOFT reactor coolant pump performance during the first quadrant operation. The measured pump characteristics are presented as functions of pump void fraction which was determined based on the measured density. The calculated pump characteristics such as pump head, torque (or hydraulic torque), and efficiency are also determined as functions of pump void fractions. The importance of accurate modeling of the reactor coolant pump performance under two-phase conditions is addressed. The analytical pump model, currently used in most reactor analysis codes to predict transient two-phase pump behavior, is assessed.
Scaling of Two-Phase Systems Across Gravity Levels Project
National Aeronautics and Space Administration — There is a defined need for long term earth based testing for the development and deployment of two-phase flow systems in reduced-gravity, including lunar gravity,...
Two-phase cooling fluids; Les fluides frigoporteurs diphasiques
Energy Technology Data Exchange (ETDEWEB)
Lallemand, A. [Institut National des Sciences Appliquees (INSA), 69 - Lyon (France)
1997-12-31
In the framework of the diminution of heat transfer fluid consumption, the concept of indirect refrigerating circuits, using cooling intermediate fluids, is reviewed and the fluids that are currently used in these systems are described. Two-phase cooling fluids advantages over single-phase fluids are presented with their thermophysical characteristics: solid fraction, two-phase mixture enthalpy, thermal and rheological properties, determination of heat and mass transfer characteristics, and cold storage through ice slurry
Diagnosing Traffic Anomalies Using a Two-Phase Model
Institute of Scientific and Technical Information of China (English)
Bin Zhang; Jia-Hai Yang; Jian-Ping Wu; Ying-Wu Zhu
2012-01-01
Network traffic anomalies are unusual changes in a network,so diagnosing anomalies is important for network management.Feature-based anomaly detection models (ab)normal network traffic behavior by analyzing packet header features. PCA-subspace method (Principal Component Analysis) has been verified as an efficient feature-based way in network-wide anomaly detection.Despite the powerful ability of PCA-subspace method for network-wide traffic detection,it cannot be effectively used for detection on a single link.In this paper,different from most works focusing on detection on flow-level traffic,based on observations of six traffc features for packet-level traffic,we propose a new approach B6SVM to detect anomalies for packet-level traffic on a single link.The basic idea of B6-SVM is to diagnose anomalies in a multi-dimensional view of traffic features using Support Vector Machine (SVM).Through two-phase classification,B6-SVM can detect anomalies with high detection rate and low false alarm rate.The test results demonstrate the effectiveness and potential of our technique in diagnosing anomalies.Further,compared to previous feature-based anomaly detection approaches,B6-SVM provides a framework to automatically identify possible anomalous types.The framework of B6-SVM is generic and therefore,we expect the derived insights will be helpful for similar future research efforts.
Two-Phase Cooling of Targets and Electronics for Particle Physics Experiments
Thome, J R; Park, J E
2009-01-01
An overview of the LTCM lab’s decade of experience with two-phase cooling research for computer chips and power electronics will be described with its possible beneficial application to high-energy physics experiments. Flow boiling in multi-microchannel cooling elements in silicon (or aluminium) have the potential to provide high cooling rates (up to as high as 350 W/cm2), stable and uniform temperatures of targets and electronics, and lightweight construction while also minimizing the fluid inventory. An overview of two-phase flow and boiling research in single microchannels and multi-microchannel test elements will be presented together with video images of these flows. The objective is to stimulate discussion on the use of two-phase cooling in these demanding applications, including the possible use of CO2.
Building Technologies Program Multi-Year Program Plan Program Portfolio Management 2008
Energy Technology Data Exchange (ETDEWEB)
None, None
2008-01-01
Building Technologies Program Multi-Year Program Plan 2008 for program portfolio management, including the program portfolio management process, program analysis, performance assessment, stakeholder interactions, and cross-cutting issues.
Energy Technology Data Exchange (ETDEWEB)
None, None
2008-01-01
Building Technologies Program Multi-Year Program Plan 2008 for technology validation and market introduction, including ENERGY STAR, building energy codes, technology transfer application centers, commercial lighting initiative, EnergySmart Schools, EnergySmar
A phenomenological model of two-phase (air/fuel droplet developing and breakup
Directory of Open Access Journals (Sweden)
Pavlović Radomir R.
2013-01-01
Full Text Available Effervescent atomization namely the air-filled liquid atomization comprehends certain complex two-phase phenomenon that are difficult to be modeled. Just a few researchers have found the mathematical expressions for description of the complex atomization model of the two-phase mixture air/diesel fuel. In the following review, developing model of twophase (air/fuel droplet of Cummins spray pump-injector is shown. The assumption of the same diameters of the droplet and the opening of the atomizer is made, while the air/fuel mass ratio inside the droplet varies.
Multi-needle capacitance probe for non-conductive two-phase flows
Monrós-Andreu, G.; Martinez-Cuenca, R.; Torró, S.; Escrig, J.; Hewakandamby, B.; Chiva, S.
2016-07-01
Despite its variable degree of application, intrusive instrumentation is the most accurate way to obtain local information in a two-phase flow system, especially local interfacial velocity and local interfacial area parameters. In this way, multi-needle probes, based on conductivity or optical principles, have been extensively used in the past few decades by many researchers in two-phase flow investigations. Moreover, the signal processing methods used to obtain the time-averaged two-phase flow parameters in this type of sensor have been thoroughly discussed and validated by many experiments. The objective of the present study is to develop a miniaturized multi-needle probe, based on capacitance measurements applicable to a wide range of non-conductive two-phase flows and, thus, to extend the applicability of multi-needle sensor whilst also maintaining a signal processing methodology provided in the literature for conductivity probes. Results from the experiments performed assess the applicability of the proposed sensor measurement principle and signal processing method for the bubbly flow regime. These results also provide an insight into the sensor application for more complex two-phase flow regimes.
Design and evaluation of a two-phase turbine for low quality steam--water mixtures
Energy Technology Data Exchange (ETDEWEB)
Comfort, W.J. III
1977-05-16
A new two-phase turbine was designed and built for testing in the laboratory, using a low quality steam-water mixture as a working fluid. The measured performance compares well with performance predictions of a numerical model of the expander. Details of the selection of the type of expander are given. The design of an experimental expander for use in a clean two-phase flow laboratory experiment and the development of a numerical model for performance analysis and extrapolations are described. Experiments including static cascade performance with two-phase fluid, disk friction and windage measurements, and two-phase performance measurements of the experimental expander are reported. Comparisons of the numerical model and experimental results, and the prediction of the performance of an advanced design, indicating how performance improvements can be achieved, are also included. An engine efficiency of 23 percent for a single-nozzle test was measured. Full admission performance, based upon the numerical model and achievable nozzle thrust coefficients indicate that an engine efficiency of between 38 and 48 percent can be realized with present technology. If maximum liquid removal loss is assumed, this performance range is predicted to be 38 to 41 percent. Droplet size reduction and the development and implementation of enhanced two-phase flow analysis techniques should make it possible to achieve the research goal of 70 percent engine efficiency.
Controls on Arctic sea ice from first-year and multi-year survival rates
Energy Technology Data Exchange (ETDEWEB)
Hunke, Jes [Los Alamos National Laboratory
2009-01-01
The recent decrease in Arctic sea ice cover has transpired with a significant loss of multi year ice. The transition to an Arctic that is populated by thinner first year sea ice has important implications for future trends in area and volume. Here we develop a reduced model for Arctic sea ice with which we investigate how the survivability of first year and multi year ice control the mean state, variability, and trends in ice area and volume.
Mathematical modeling of disperse two-phase flows
Morel, Christophe
2015-01-01
This book develops the theoretical foundations of disperse two-phase flows, which are characterized by the existence of bubbles, droplets or solid particles finely dispersed in a carrier fluid, which can be a liquid or a gas. Chapters clarify many difficult subjects, including modeling of the interfacial area concentration. Basic knowledge of the subjects treated in this book is essential to practitioners of Computational Fluid Dynamics for two-phase flows in a variety of industrial and environmental settings. The author provides a complete derivation of the basic equations, followed by more advanced subjects like turbulence equations for the two phases (continuous and disperse) and multi-size particulate flow modeling. As well as theoretical material, readers will discover chapters concerned with closure relations and numerical issues. Many physical models are presented, covering key subjects including heat and mass transfers between phases, interfacial forces and fluid particles coalescence and breakup, a...
Velocity and energy relaxation in two-phase flows
Meyapin, Yannick; Gisclon, Marguerite
2009-01-01
In the present study we investigate analytically the process of velocity and energy relaxation in two-phase flows. We begin our exposition by considering the so-called six equations two-phase model [Ishii1975, Rovarch2006]. This model assumes each phase to possess its own velocity and energy variables. Despite recent advances, the six equations model remains computationally expensive for many practical applications. Moreover, its advection operator may be non-hyperbolic which poses additional theoretical difficulties to construct robust numerical schemes |Ghidaglia et al, 2001]. In order to simplify this system, we complete momentum and energy conservation equations by relaxation terms. When relaxation characteristic time tends to zero, velocities and energies are constrained to tend to common values for both phases. As a result, we obtain a simple two-phase model which was recently proposed for simulation of violent aerated flows [Dias et al, 2010]. The preservation of invariant regions and incompressible li...
A SAS Package for Logistic Two-Phase Studies
Directory of Open Access Journals (Sweden)
Walter Schill
2014-04-01
Full Text Available Two-phase designs, in which for a large study a dichotomous outcome and partial or proxy information on risk factors is available, whereas precise or complete measurements on covariates have been obtained only in a stratified sub-sample, extend the standard case-control design and have been proven useful in practice. The application of two-phase designs, however, seems to be hampered by the lack of appropriate, easy-to-use software. This paper introduces sas-twophase-package, a collection of SAS-macros, to fulfill this task. sas-twophase-package implements weighted likelihood, pseudo likelihood and semi- parametric maximum likelihood estimation via the EM algorithm and via profile likelihood in two-phase settings with dichotomous outcome and a given stratification.
A mechanical erosion model for two-phase mass flows
Pudasaini, Shiva P
2016-01-01
Erosion, entrainment and deposition are complex and dominant, but yet poorly understood, mechanical processes in geophysical mass flows. Here, we propose a novel, process-based, two-phase, erosion-deposition model capable of adequately describing these complex phenomena commonly observed in landslides, avalanches, debris flows and bedload transport. The model is based on the jump in the momentum flux including changes of material and flow properties along the flow-bed interface and enhances an existing general two-phase mass flow model (Pudasaini, 2012). A two-phase variably saturated erodible basal morphology is introduced and allows for the evolution of erosion-deposition-depths, incorporating the inherent physical process including momentum and rheological changes of the flowing mixture. By rigorous derivation, we show that appropriate incorporation of the mass and momentum productions or losses in conservative model formulation is essential for the physically correct and mathematically consistent descript...
Simulating confined swirling gas-solid two phase jet
Institute of Scientific and Technical Information of China (English)
金晗辉; 夏钧; 樊建人; 岑可法
2002-01-01
A k-ε-kp multi-fluid model was used to simulate confined swirling gas-solid two phase jet comprised of particle-laden flow from a center tube and a swirling air stream entering the test section from the coaxial annular. After considering the drag force between the two phases and gravity, a series of numerical simulations of the two-phase flow of 30μm, 45μm, 60μm diameter particles were performed on a x×r＝50×50 mesh grid respectively. The results showed that the k-ε-kp multi-fluid model can be applied to predict moderate swirling multi-phase flow. When the particle diameter is large, the collision of the particles with the wall will influence the prediction accuracy. The bigger the diameter of the particles, the stronger the collision with the wall, and the more obvious the difference between measured and calculated results.
Adaptive sampling in two-phase designs: a biomarker study for progression in arthritis
McIsaac, Michael A; Cook, Richard J
2015-01-01
Response-dependent two-phase designs are used increasingly often in epidemiological studies to ensure sampling strategies offer good statistical efficiency while working within resource constraints. Optimal response-dependent two-phase designs are difficult to implement, however, as they require specification of unknown parameters. We propose adaptive two-phase designs that exploit information from an internal pilot study to approximate the optimal sampling scheme for an analysis based on mean score estimating equations. The frequency properties of estimators arising from this design are assessed through simulation, and they are shown to be similar to those from optimal designs. The design procedure is then illustrated through application to a motivating biomarker study in an ongoing rheumatology research program. Copyright © 2015 © 2015 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd. PMID:25951124
Dynamic Modeling of Phase Crossings in Two-Phase Flow
DEFF Research Database (Denmark)
Madsen, Søren; Veje, Christian; Willatzen, Morten
2012-01-01
of the variables and are usually very slow to evaluate. To overcome these challenges, we use an interpolation scheme with local refinement. The simulations show that the method handles crossing of the saturation lines for both liquid to two-phase and two-phase to gas regions. Furthermore, a novel result obtained...... in this work, the method is stable towards dynamic transitions of the inlet/outlet boundaries across the saturation lines. Results for these cases are presented along with a numerical demonstration of conservation of mass under dynamically varying boundary conditions. Finally we present results...
Shock wave of vapor-liquid two-phase flow
Institute of Scientific and Technical Information of China (English)
Liangju ZHAO; Fei WANG; Hong GAO; Jingwen TANG; Yuexiang YUAN
2008-01-01
The shock wave of vapor-liquid two-phase flow in a pressure-gain steam injector is studied by build-ing a mathematic model and making calculations. The results show that after the shock, the vapor is nearly com-pletely condensed. The upstream Mach number and the volume ratio of vapor have a great effect on the shock. The pressure and Mach number of two-phase shock con-form to the shock of ideal gas. The analysis of available energy shows that the shock is an irreversible process with entropy increase.
STUDIES OF TWO-PHASE PLUMES IN STRATIFIED ENVIRONMENTS
Energy Technology Data Exchange (ETDEWEB)
Scott A. Socolofsky; Brian C. Crounse; E. Eric Adams
1998-11-18
Two-phase plumes play an important role in the more practical scenarios for ocean sequestration of CO{sub 2}--i.e. dispersing CO{sub 2} as a buoyant liquid from either a bottom-mounted or ship-towed pipeline. Despite much research on related applications, such as for reservoir destratification using bubble plumes, our understanding of these flows is incomplete, especially concerning the phenomenon of plume peeling in a stratified ambient. To address this deficiency, we have built a laboratory facility in which we can make fundamental measurements of plume behavior. Although we are using air, oil and sediments as our sources of buoyancy (rather than CO{sub 2}), by using models, our results can be directly applied to field scale CO{sub 2} releases to help us design better CO{sub 2} injection systems, as well as plan and interpret the results of our up-coming international field experiment. The experimental facility designed to study two-phase plume behavior similar to that of an ocean CO{sub 2} release includes the following components: 1.22 x 1.22 x 2.44 m tall glass walled tank; Tanks and piping for the two-tank stratification method for producing step- and linearly-stratified ambient conditions; Density profiling system using a conductivity and temperature probe mounted to an automated depth profiler; Lighting systems, including a virtual point source light for shadowgraphs and a 6 W argon-ion laser for laser induced fluorescence (LIF) imaging; Imaging system, including a digital, progressive scanning CCD camera, computerized framegrabber, and image acquisition and analysis software; Buoyancy source diffusers having four different air diffusers, two oil diffusers, and a planned sediment diffuser; Dye injection method using a Mariotte bottle and a collar diffuser; and Systems integration software using the Labview graphical programming language and Windows NT. In comparison with previously reported experiments, this system allows us to extend the parameter range of
Modelling two-phase transport of 3H/3He
Visser, A.; Schaap, J.D.; Leijnse, T.; Broers, H.P.; Bierkens, M.F.P.
2008-01-01
Degassing of groundwater by excess denitrification of agricultural pollution complicates the interpretation of 3H/3He data and hinders the estimation of travel times in nitrate pollution studies. In this study we used a two-phase flow and transport model (STOMP) to evaluate the method presented by
Two-phase alkali-metal experiments in reduced gravity
Energy Technology Data Exchange (ETDEWEB)
Antoniak, Z.I.
1986-06-01
Future space missions envision the use of large nuclear reactors utilizing either a single or a two-phase alkali-metal working fluid. The design and analysis of such reactors require state-of-the-art computer codes that can properly treat alkali-metal flow and heat transfer in a reduced-gravity environment. A literature search of relevant experiments in reduced gravity is reported on here, and reveals a paucity of data for such correlations. The few ongoing experiments in reduced gravity are noted. General plans are put forth for the reduced-gravity experiments which will have to be performed, at NASA facilities, with benign fluids. A similar situation exists regarding two-phase alkali-metal flow and heat transfer, even in normal gravity. Existing data are conflicting and indequate for the task of modeling a space reactor using a two-phase alkali-metal coolant. The major features of past experiments are described here. Data from the reduced-gravity experiments with innocuous fluids are to be combined with normal gravity data from the two-phase alkali-metal experiments. Analyses undertaken here give every expectation that the correlations developed from this data base will provide a valid representation of alkali-metal heat transfer and pressure drop in reduced gravity.
Coal-Face Fracture With A Two-Phase Liquid
Collins, E. R., Jr.
1985-01-01
In new method for mining coal without explosive, two-phase liquid such as CO2 and water, injected at high pressure into deeper ends of holes drilled in coal face. Liquid permeates coal seam through existing microfractures; as liquid seeps back toward face, pressure eventually drops below critical value at which dissolved gas flashvaporizes, breaking up coal.
Two-phase flow in micro and nanofluidic devices
Shui, Lingling
2009-01-01
This thesis provides experimental data and theoretical analysis on two-phase flow in devices with different layouts of micrometer or nanometer-size channels. A full flow diagram is presented for oil and water flow in head-on microfluidic devices. Morphologically different flow regimes (dripping, jet
Modelling two-phase transport of 3H/3He
Visser, A.; Schaap, J.D.; Leijnse, T.; Broers, H.P.; Bierkens, M.F.P.
2008-01-01
Degassing of groundwater by excess denitrification of agricultural pollution complicates the interpretation of 3H/3He data and hinders the estimation of travel times in nitrate pollution studies. In this study we used a two-phase flow and transport model (STOMP) to evaluate the method presented by V
Experimental Investigation of two-phase nitrogen Cryo transfer line
Singh, G. K.; Nimavat, H.; Panchal, R.; Garg, A.; Srikanth, GLN; Patel, K.; Shah, P.; Tanna, V. L.; Pradhan, S.
2017-02-01
A 6-m long liquid nitrogen based cryo transfer line has been designed, developed and tested at IPR. The test objectives include the thermo-hydraulic characteristics of Cryo transfer line under single phase as well as two phase flow conditions. It is always easy in experimentation to investigate the thermo-hydraulic parameters in case of single phase flow of cryogen but it is real challenge when one deals with the two phase flow of cryogen due to availibity of mass flow measurements (direct) under two phase flow conditions. Established models have been reported in the literature where one of the well-known model of Lockhart-Martenelli relationship has been used to determine the value of quality at the outlet of Cryo transfer line. Under homogenous flow conditions, by taking the ratio of the single-phase pressure drop and the two-phase pressure drop, we estimated the quality at the outlet. Based on these equations, vapor quality at the outlet of the transfer line was predicted at different heat loads. Experimental rresults shown that from inlet to outlet, there is a considerable increment in the pressure drop and vapour quality of the outlet depending upon heat load and mass flow rate of nitrogen flowing through the line.
Numerical simulation of two-phase flow in offshore environments
Wemmenhove, Rik
2008-01-01
Numerical Simulation of Two-Phase Flow in Offshore Environments Rik Wemmenhove Weather conditions on full sea are often violent, leading to breaking waves and lots of spray and air bubbles. As high and steep waves may lead to severe damage on ships and offshore structures, there is a great need for
TWO-PHASE EJECTOR of CARBON DIOXIDE HEAT PUMP CALCULUS
Directory of Open Access Journals (Sweden)
Sit B.M.
2010-12-01
Full Text Available It is presented the calculus of the two-phase ejector for carbon dioxide heat pump. The method of calculus is based on the method elaborated by S.M. Kandil, W.E. Lear, S.A. Sherif, and is modified taking into account entrainment ratio as the input for the calculus.
Coal Power Systems strategic multi-year program plans
Energy Technology Data Exchange (ETDEWEB)
None
2001-02-01
The Department of Energy's (DOE) Office of Fossil Energy (FE), through the Coal and Power Systems (C and PS) program, funds research to advance the scientific knowledge needed to provide new and improved energy technologies; to eliminate any detrimental environmental effects of energy production and use; and to maintain US leadership in promoting the effective use of US power technologies on an international scale. Further, the C and PS program facilitates the effective deployment of these technologies to maximize their benefits to the Nation. The following Strategic Plan describes how the C and PS program intends to meet the challenges of the National Energy Strategy to: (1) enhance American's energy security; (2) improve the environmental acceptability of energy production and use; (3) increase the competitiveness and reliability of US energy systems; and (4) ensure a robust US energy future. It is a plan based on the consensus of experts and managers from FE's program offices and the National Energy Technology Laboratory (NETL).
Investigations of two-phase flame propagation under microgravity conditions
Gokalp, Iskender
2016-07-01
Investigations of two-phase flame propagation under microgravity conditions R. Thimothée, C. Chauveau, F. Halter, I Gökalp Institut de Combustion, Aérothermique, Réactivité et Environnement (ICARE), CNRS, 1C Avenue de la Recherche Scientifique, 45071 Orléans Cedex 2, France This paper presents and discusses recent results on two-phase flame propagation experiments we carried out with mono-sized ethanol droplet aerosols under microgravity conditions. Fundamental studies on the flame propagation in fuel droplet clouds or sprays are essential for a better understanding of the combustion processes in many practical applications including internal combustion engines for cars, modern aircraft and liquid rocket engines. Compared to homogeneous gas phase combustion, the presence of a liquid phase considerably complicates the physico-chemical processes that make up combustion phenomena by coupling liquid atomization, droplet vaporization, mixing and heterogeneous combustion processes giving rise to various combustion regimes where ignition problems and flame instabilities become crucial to understand and control. Almost all applications of spray combustion occur under high pressure conditions. When a high pressure two-phase flame propagation is investigated under normal gravity conditions, sedimentation effects and strong buoyancy flows complicate the picture by inducing additional phenomena and obscuring the proper effect of the presence of the liquid droplets on flame propagation compared to gas phase flame propagation. Conducting such experiments under reduced gravity conditions is therefore helpful for the fundamental understanding of two-phase combustion. We are considering spherically propagating two-phase flames where the fuel aerosol is generated from a gaseous air-fuel mixture using the condensation technique of expansion cooling, based on the Wilson cloud chamber principle. This technique is widely recognized to create well-defined mono-size droplets
Two-phase relative permeability models in reservoir engineering calculations
Energy Technology Data Exchange (ETDEWEB)
Siddiqui, S.; Hicks, P.J.; Ertekin, T.
1999-01-15
A comparison of ten two-phase relative permeability models is conducted using experimental, semianalytical and numerical approaches. Model predicted relative permeabilities are compared with data from 12 steady-state experiments on Berea and Brown sandstones using combinations of three white mineral oils and 2% CaCl1 brine. The model results are compared against the experimental data using three different criteria. The models are found to predict the relative permeability to oil, relative permeability to water and fractional flow of water with varying degrees of success. Relative permeability data from four of the experimental runs are used to predict the displacement performance under Buckley-Leverett conditions and the results are compared against those predicted by the models. Finally, waterflooding performances predicted by the models are analyzed at three different viscosity ratios using a two-dimensional, two-phase numerical reservoir simulator. (author)
Computer simulation of two-phase flow in nuclear reactors
Energy Technology Data Exchange (ETDEWEB)
Wulff, W.
1992-09-01
Two-phase flow models dominate the economic resource requirements for development and use of computer codes for analyzing thermohydraulic transients in nuclear power plants. Six principles are presented on mathematical modeling and selection of numerical methods, along with suggestions on programming and machine selection, all aimed at reducing the cost of analysis. Computer simulation is contrasted with traditional computer calculation. The advantages of run-time interactive access operation in a simulation environment are demonstrated. It is explained that the drift-flux model is better suited for two-phase flow analysis in nuclear reactors than the two-fluid model, because of the latter`s closure problem. The advantage of analytical over numerical integration is demonstrated. Modeling and programming techniques are presented which minimize the number of needed arithmetical and logical operations and thereby increase the simulation speed, while decreasing the cost.
Computer simulation of two-phase flow in nuclear reactors
Energy Technology Data Exchange (ETDEWEB)
Wulff, W.
1992-01-01
Two-phase flow models dominate the economic resource requirements for development and use of computer codes for analyzing thermohydraulic transients in nuclear power plants. Six principles are presented on mathematical modeling and selection of numerical methods, along with suggestions on programming and machine selection, all aimed at reducing the cost of analysis. Computer simulation is contrasted with traditional computer calculation. The advantages of run-time interactive access operation in a simulation environment are demonstrated. It is explained that the drift-flux model is better suited for two-phase flow analysis in nuclear reactors than the two-fluid model, because of the latter's closure problem. The advantage of analytical over numerical integration is demonstrated. Modeling and programming techniques are presented which minimize the number of needed arithmetical and logical operations and thereby increase the simulation speed, while decreasing the cost.
Two-phase Flow Distribution in Heat Exchanger Manifolds
Vist, Sivert
2004-01-01
The current study has investigated two-phase refrigerant flow distribution in heat exchange manifolds. Experimental data have been acquired in a heat exchanger test rig specially made for measurement of mass flow rate and gas and liquid distribution in the manifolds of compact heat exchangers. Twelve different manifold designs were used in the experiments, and CO2 and HFC-134a were used as refrigerants.
Computational methods for two-phase flow and particle transport
Lee, Wen Ho
2013-01-01
This book describes mathematical formulations and computational methods for solving two-phase flow problems with a computer code that calculates thermal hydraulic problems related to light water and fast breeder reactors. The physical model also handles the particle and gas flow problems that arise from coal gasification and fluidized beds. The second part of this book deals with the computational methods for particle transport.
Viscosity Solutions for the two-phase Stefan Problem
Kim, Inwon C
2010-01-01
We introduce a notion of viscosity solutions for the two-phase Stefan problem, which incorporates possible existence of a mushy region generated by the initial data. We show that a comparison principle holds between viscosity solutions, and investigate the coincidence of the viscosity solutions and the weak solutions defined via integration by parts. In particular, in the absence of initial mushy region, viscosity solution is the unique weak solution with the same boundary data.
Recent advances in two-phase flow numerics
Energy Technology Data Exchange (ETDEWEB)
Mahaffy, J.H.; Macian, R. [Pennsylvania State Univ., University Park, PA (United States)
1997-07-01
The authors review three topics in the broad field of numerical methods that may be of interest to individuals modeling two-phase flow in nuclear power plants. The first topic is iterative solution of linear equations created during the solution of finite volume equations. The second is numerical tracking of macroscopic liquid interfaces. The final area surveyed is the use of higher spatial difference techniques.
Estimating disease prevalence in two-phase studies.
Alonzo, Todd A; Pepe, Margaret Sullivan; Lumley, Thomas
2003-04-01
Disease prevalence is ideally estimated using a 'gold standard' to ascertain true disease status on all subjects in a population of interest. In practice, however, the gold standard may be too costly or invasive to be applied to all subjects, in which case a two-phase design is often employed. Phase 1 data consisting of inexpensive and non-invasive screening tests on all study subjects are used to determine the subjects that receive the gold standard in the second phase. Naive estimates of prevalence in two-phase studies can be biased (verification bias). Imputation and re-weighting estimators are often used to avoid this bias. We contrast the forms and attributes of the various prevalence estimators. Distribution theory and simulation studies are used to investigate their bias and efficiency. We conclude that the semiparametric efficient approach is the preferred method for prevalence estimation in two-phase studies. It is more robust and comparable in its efficiency to imputation and other re-weighting estimators. It is also easy to implement. We use this approach to examine the prevalence of depression in adolescents with data from the Great Smoky Mountain Study.
An ALE Finite Element Approach for Two-Phase Flow with Phase Change
Gros, Erik; Anjos, Gustavo; Thome, John; Ltcm Team; Gesar Team
2016-11-01
In this work, two-phase flow with phase change is investigated through the Finite Element Method (FEM) in the Arbitrary Lagrangian-Eulerian (ALE) framework. The equations are discretized on an unstructured mesh where the interface between the phases is explicitly defined as a sub-set of the mesh. The two-phase interface position is described by a set of interconnected nodes which ensures a sharp representation of the boundary, including the role of the surface tension. The methodology proposed for computing the curvature leads to very accurate results with moderate programming effort and computational costs. Such a methodology can be employed to study accurately many two-phase flow and heat transfer problems in industry such as oil extraction and refinement, design of refrigeration systems, modelling of microfluidic and biological systems and efficient cooling of electronics for computational purposes. The latter is the principal aim of the present research. The numerical results are discussed and compared to analytical solutions and reference results, thereby revealing the capability of the proposed methodology as a platform for the study of two-phase flow with phase change.
Characterization of horizontal air–water two-phase flow
Energy Technology Data Exchange (ETDEWEB)
Kong, Ran; Kim, Seungjin, E-mail: skim@psu.edu
2017-02-15
Highlights: • A visualization study is performed to develop flow regime map in horizontal flow. • Database in horizontal bubbly flow is extended using a local conductivity probe. • Frictional pressure drop analysis is performed in horizontal bubbly flow. • Drift flux analysis is performed in horizontal bubbly flow. - Abstract: This paper presents experimental studies performed to characterize horizontal air–water two-phase flow in a round pipe with an inner diameter of 3.81 cm. A detailed flow visualization study is performed using a high-speed video camera in a wide range of two-phase flow conditions to verify previous flow regime maps. Two-phase flows are classified into bubbly, plug, slug, stratified, stratified-wavy, and annular flow regimes. While the transition boundaries identified in the present study compare well with the existing ones (Mandhane et al., 1974) in general, some discrepancies are observed for bubbly-to-plug/slug, and plug-to-slug transition boundaries. Based on the new transition boundaries, three additional test conditions are determined in horizontal bubbly flow to extend the database by Talley et al. (2015a). Various local two-phase flow parameters including void fraction, interfacial area concentration, bubble velocity, and bubble Sauter mean diameter are obtained. The effects of increasing gas flow rate on void fraction, bubble Sauter mean diameter, and bubble velocity are discussed. Bubbles begin to coalesce near the gas–liquid layer instead of in the highly packed region when gas flow rate increases. Using all the current experimental data, two-phase frictional pressure loss analysis is performed using the Lockhart–Martinelli method. It is found that the coefficient C = 24 yields the best agreement with the data with the minimum average difference. Moreover, drift flux analysis is performed to predict void-weighted area-averaged bubble velocity and area-averaged void fraction. Based on the current database, functional
Institute of Scientific and Technical Information of China (English)
鹿钦礼; 乔伟彪; 刘帅; 冯云飞
2012-01-01
Based on the model of the CFD Eulerian, using the method of the limited volumetry, we build the mathematics model of the solid and liquid two - phase flow. And we simulate sand blower whose lenth is 180 millimeter, inlet radius diameter is 4 millimeter, outlet is annular and inner annular radius diameter is 7 millimeter, outer annular radius diameter is 9 millimeter numerically. Research indicates; under the circumstance of the other invariant condition, the fracturing liquid inlet velocity increasing, the energy of turbulence is lower in the direction of the roller, with the include sand ratio decreasing, the pressure of the fracturing liquid is added in the every faces; with the outlet pressure increasing, the flow velocity of the fracturing liquid is also amplified.%基于计算流体力学中的欧拉模型、采用有限客积法建立固液两相在喷砂器内流动的数学模型.针对总长为180mm,入口半径为4mm,出口为环形且内环半径为7mm、外环半径为9mm的喷砂器进行数值模拟.结果表明:在其它条件不变的情况下,随着压裂液入口速度的增加,轴向距离各截面的湍动能逐渐减少,随着舍沙率的减少,压裂液在各截面的压强逐渐增大,随着出口压力的增加,压裂液流动速度也在增大.
Interfacial area transport for reduced-gravity two-phase flows
Vasavada, Shilp
An extensive experimental and theoretical study of two-phase flow behavior in reduced-gravity conditions has been performed as part of the current research and the results of the same are presented in this thesis. The research was undertaken to understand the behavior of two-phase flows in an environment where the gravity field is reduced as compared to that on earth. The goal of the study was to develop a model capable of predicting the flow behavior. An experimental program was developed and accomplished which simulated reduced-gravity conditions on earth by using two liquids of similar density, thereby decreasing the body force effect akin to actual reduced-gravity conditions. The justification and validation of this approach has been provided based on physical arguments as well as comparison of acquired data with that obtained aboard parabolic flights by previous researchers. The experimental program produced an extensive dataset of local and averaged two-phase flow parameters using state-of-the-art instrumentation. Such data were acquired for a wide range of flow conditions at different radial and axial locations in a 25 mm inner diameter test facility. The current dataset is, in the author's opinion, the most extensive and detailed dataset available for such conditions at present. Analysis of the data revealed important differences between two-phase flows in normal and reduced-gravity conditions. The data analysis also highlighted key interaction mechanisms between the fluid particles and physical phenomena occurring in two-phase flows under reduced-gravity conditions. The interfacial area transport equation (IATE) for reduced-gravity conditions has been developed by considering two groups of bubbles/drops and mechanistically modeling the interaction mechanisms. The developed model has been benchmarked against the acquired data and the predictions of the model compared favorably against the experimental data. This signifies the success achieved in modeling
Experimental Two-Phase Liquid-Metal Magnetohydrodynamic Generator Program
1979-04-01
efficiencies in excess of 0.8 are attainable. Initial measurements of local flow parameters in a NaK -nitrogen two-phase liquid - metal MHD generator...hot liquid metals . Thus, the concept of using surface-active aaents in MHD generators can be evaluated more rapidly and inexpensively with NaK , the...describe this aggregation of bchbles as a foam. When the Ba- NaK solution was transferred, helium was blown under the surface of the liquid metal with the
A real two-phase submarine debris flow and tsunami
Energy Technology Data Exchange (ETDEWEB)
Pudasaini, Shiva P.; Miller, Stephen A. [Department of Geodynamics and Geophysics, Steinmann Institute, University of Bonn Nussallee 8, D-53115, Bonn (Germany)
2012-09-26
The general two-phase debris flow model proposed by Pudasaini is employed to study subaerial and submarine debris flows, and the tsunami generated by the debris impact at lakes and oceans. The model, which includes three fundamentally new and dominant physical aspects such as enhanced viscous stress, virtual mass, and generalized drag (in addition to buoyancy), constitutes the most generalized two-phase flow model to date. The advantage of this two-phase debris flow model over classical single-phase, or quasi-two-phase models, is that the initial mass can be divided into several parts by appropriately considering the solid volume fraction. These parts include a dry (landslide or rock slide), a fluid (water or muddy water; e.g., dams, rivers), and a general debris mixture material as needed in real flow simulations. This innovative formulation provides an opportunity, within a single framework, to simultaneously simulate the sliding debris (or landslide), the water lake or ocean, the debris impact at the lake or ocean, the tsunami generation and propagation, the mixing and separation between the solid and fluid phases, and the sediment transport and deposition process in the bathymetric surface. Applications of this model include (a) sediment transport on hill slopes, river streams, hydraulic channels (e.g., hydropower dams and plants); lakes, fjords, coastal lines, and aquatic ecology; and (b) submarine debris impact and the rupture of fiber optic, submarine cables and pipelines along the ocean floor, and damage to offshore drilling platforms. Numerical simulations reveal that the dynamics of debris impact induced tsunamis in mountain lakes or oceans are fundamentally different than the tsunami generated by pure rock avalanches and landslides. The analysis includes the generation, amplification and propagation of super tsunami waves and run-ups along coastlines, debris slide and deposition at the bottom floor, and debris shock waves. It is observed that the
Recurrent pyogenic cholangitis : efficacy of two-phase helical CT
Energy Technology Data Exchange (ETDEWEB)
Jeong, Ki Ho; Cho, June Sik; Shin, Kyung Sook; Lee, Se Hyo; Yu, Ho Jun; Park, Jin Yong; Kim, Young Min [College of Medicine, Chungnam National University, Taejon (Korea, Republic of)
2000-01-01
To evaluate the usefulness of two-phase helical CT in patients with recurrent pyogenic cholangitis (RPC) for the detection of acute inflammation and assessment of the degree of portal vein (PV) stenosis as a cause of hepatic parenchymal atrophy. We retrospectively reviewed two-phase CT findings in 30 patients with RPC diagnosed by CT, ERCP (endoscopic retrograde cholangiopancreatography), and surgery. Two-phase helical CT scans were obtained 30 sec (arterial phase, AP) and 70 sec (portal phase, PP) after the start of IV administration of contrast material. Without prior information, we analyzed periductal parenchymal and ductal wall enhancement during the AP and PP, and the degree of PV stenosis during the PP. Acute inflammation was diagnosed on the basis of symptoms and laboratory findings. To evaluate the relationship between parenchymal a trophy and PV stenosis, the degree of PV stenosis in affected parenchyma was classified as one of three types (mild, less than 25%; moderate, 25-75%; severe, greater than 75%), as compared with the diameter of normal PV in unaffected parenchyma. Ten of the 30 patients underwent CT during the acute inflammatory stage and 20 during the remission stage. Of the ten patients with acute inflammation, eight (80%) showed transient periductal parenchymal enhancement during the AP (p less than 0.05), which correlated closely with acute inflammation. Only three (15%) of the 20 patients with remission, however, showed transient parenchymal enhancement during this phase, at which time ductal wall enhancement was seen in three (30%) of the ten patients with acute inflammation and in seven (35%) of the 20 who showed remission (p greater than 0.05). There was no significant difference in parenchymal and ductal wall enhancement during the PP between patients with acute inflammation and those who showed remission (p greater than 0.05). Hepatic parenchymal atrophy of the lesion was seen in 24 patients. Among these, PV stenosis was mild in five
Two algorithms for two-phase Stefan type problems
Institute of Scientific and Technical Information of China (English)
LIAN Xiao-peng; CHENG Xiao-liang; HAN Wei-min
2009-01-01
In this paper, the relaxation algorithm and two Uzawa type algorithms for solving discretized variational inequalities arising from the two-phase Stefan type problem are proposed. An analysis of their convergence is presented and the upper bounds of the convergence rates are derived. Some numerical experiments are shown to demonstrate that for the second Uzawa algorithm which is an improved version of the first Uzawa algorithm, the convergence rate is uniformly bounded away from 1 if τh-2 is kept bounded, where τ is the time step size and h the space mesh size.
Stochastic analysis of particle-fluid two-phase flows
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
This paper is devoted to exploring approaches to understanding the stochastic characteristics of particle-fluid two-phase flow. By quantifying the forces dominating the particle motion and modelling the less important and/or unclear forces as random forces, a stochastic differential equation is proposed to describe the complex behavior of a particle motion. An exploratory simulation has shown satisfactory agreement with phase doppler particle analyzer (PDPA) measurements, which indicates that stochastic analysis is a potential approach for revealing the details of particle-fluid flow phenomena.
Two-phase nozzle flow and the subcharacteristic condition
DEFF Research Database (Denmark)
Linga, Gaute; Aursand, Peder; Flåtten, Tore
2015-01-01
We consider nozzle flow models for two-phase flow with phase transfer. Such models are based on energy considerations applied to the frozen and equilibrium limits of the underlying relaxation models. In this paper, we provide an explicit link between the mass flow rate predicted by these models a...... leakage of CO2 is presented, indicating that the frozen and equilibrium models provide significantly different predictions. This difference is comparable in magnitude to the modeling error introduced by applying simple ideal-gas/incompressible-liquid equations-of-state for CO2....
Policy Design of Multi-Year Crop Insurance Contracts with Partial Payments.
Directory of Open Access Journals (Sweden)
Ying-Erh Chen
Full Text Available Current crop insurance is designed to mitigate monetary fluctuations resulting from yield losses for a specific year. However, yield realization tendency can vary from year to year and may depend on the correlation of yield realizations across years. When the current single-year Yield Protection (YP and Area Risk Protection Insurance (ARPI contracts are extended to multiple periods, actuarially fair premium rate is expected to decrease as poor yield realizations in a year can be offset by another year's better yield realizations. In this study, we first use simulations to demonstrate how significant premium savings are possible when coverage is based on the sum of yields across years rather than on a year-by-year basis. We then describe the design of a multi-year framework of crop insurance and model the insurance using a copula approach. Insurance terms are extended to more than a year and the premium, liability, and indemnity are determined by a multi-year term. Moreover, partial payment is provided at the end of each term to offset the possibility of significant loss in a single term. County-level data obtained from the U.S. Department of Agriculture are used to demonstrate the implementations of the proposed multi-year crop insurance. The proposed multi-year plan would benefit farmers by offering insurance guarantees across years for significantly lower costs.
Bioenergy Technologies Office Multi-Year Program Plan: November 2014 Update
Energy Technology Data Exchange (ETDEWEB)
None
2014-11-01
This is the November 2014 Update to the Multi-Year Program Plan, which sets forth the goals and structure of the Bioenergy Technologies Office. It identifies the RDD&D activities the Office will focus on over the next four years.
Bioenergy Technologies Office Multi-Year Program Plan: March 2015 Update
Energy Technology Data Exchange (ETDEWEB)
none,
2015-03-01
This is the March 2015 Update to the Multi-Year Program Plan, which sets forth the goals and structure of the Bioenergy Technologies Office. It identifies the RDD&D activities the Office will focus on over the next four years.
Policy Design of Multi-Year Crop Insurance Contracts with Partial Payments.
Chen, Ying-Erh; Goodwin, Barry K
2015-01-01
Current crop insurance is designed to mitigate monetary fluctuations resulting from yield losses for a specific year. However, yield realization tendency can vary from year to year and may depend on the correlation of yield realizations across years. When the current single-year Yield Protection (YP) and Area Risk Protection Insurance (ARPI) contracts are extended to multiple periods, actuarially fair premium rate is expected to decrease as poor yield realizations in a year can be offset by another year's better yield realizations. In this study, we first use simulations to demonstrate how significant premium savings are possible when coverage is based on the sum of yields across years rather than on a year-by-year basis. We then describe the design of a multi-year framework of crop insurance and model the insurance using a copula approach. Insurance terms are extended to more than a year and the premium, liability, and indemnity are determined by a multi-year term. Moreover, partial payment is provided at the end of each term to offset the possibility of significant loss in a single term. County-level data obtained from the U.S. Department of Agriculture are used to demonstrate the implementations of the proposed multi-year crop insurance. The proposed multi-year plan would benefit farmers by offering insurance guarantees across years for significantly lower costs.
Advanced reactors transition fiscal year 1996 multi-year program plan WBS 7.3
Energy Technology Data Exchange (ETDEWEB)
Hulvey, R.K.
1995-09-21
This document describes in detail the work to be accomplished in FY 1996 and the out years for the Advanced Reactors Transition (WBS 7.3. ). This document describes specific milestones and funding profiles. Based upon the Fiscal Year 1996 Multi-Year Program Plan (MYPP), DOE will provide authorization to perform the work outlined in the FY 1996 MYPP
Geothermal Energy Draft Multi-Year Program Plan: FY 1996-2000
Energy Technology Data Exchange (ETDEWEB)
None
1995-03-03
This is an internal DOE Geothermal Program planning and control document. The Five Year Plans and Multi-Year Plans usually included more detailed rationales and projections than other similar reports. Many of these reports were issued only in draft form.
Droplets Formation and Merging in Two-Phase Flow Microfluidics
Directory of Open Access Journals (Sweden)
Hao Gu
2011-04-01
Full Text Available Two-phase flow microfluidics is emerging as a popular technology for a wide range of applications involving high throughput such as encapsulation, chemical synthesis and biochemical assays. Within this platform, the formation and merging of droplets inside an immiscible carrier fluid are two key procedures: (i the emulsification step should lead to a very well controlled drop size (distribution; and (ii the use of droplet as micro-reactors requires a reliable merging. A novel trend within this field is the use of additional active means of control besides the commonly used hydrodynamic manipulation. Electric fields are especially suitable for this, due to quantitative control over the amplitude and time dependence of the signals, and the flexibility in designing micro-electrode geometries. With this, the formation and merging of droplets can be achieved on-demand and with high precision. In this review on two-phase flow microfluidics, particular emphasis is given on these aspects. Also recent innovations in microfabrication technologies used for this purpose will be discussed.
Experimental study of two-phase natural circulation circuit
Energy Technology Data Exchange (ETDEWEB)
Lemos, Wanderley Freitas; Su, Jian, E-mail: wlemos@lasme.coppe.ufrj.br, E-mail: sujian@nuclear.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Faccini, Jose Luiz Horacio, E-mail: faccini@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), RIo de Janeiro, RJ (Brazil). Lab. de Termo-Hidraulica Experimental
2012-07-01
This paper reports an experimental study on the behavior of fluid flow in natural circulation under single-and two-phase flow conditions. The natural circulation circuit was designed based on concepts of similarity and scale in proportion to the actual operating conditions of a nuclear reactor. This test equipment has similar performance to the passive system for removal of residual heat presents in Advanced Pressurized Water Reactors (A PWR). The experiment was carried out by supplying water to primary and secondary circuits, as well as electrical power resistors installed inside the heater. Power controller has available to adjust the values for supply of electrical power resistors, in order to simulate conditions of decay of power from the nuclear reactor in steady state. Data acquisition system allows the measurement and control of the temperature at different points by means of thermocouples installed at several points along the circuit. The behavior of the phenomenon of natural circulation was monitored by a software with graphical interface, showing the evolution of temperature measurement points and the results stored in digital format spreadsheets. Besides, the natural circulation flow rate was measured by a flowmeter installed on the hot leg. A flow visualization technique was used the for identifying vertical flow regimes of two-phase natural circulation. Finally, the Reynolds Number was calculated for the establishment of a friction factor correlation dependent on the scale geometrical length, height and diameter of the pipe. (author)
Two-phase electrochemical lithiation in amorphous silicon.
Wang, Jiang Wei; He, Yu; Fan, Feifei; Liu, Xiao Hua; Xia, Shuman; Liu, Yang; Harris, C Thomas; Li, Hong; Huang, Jian Yu; Mao, Scott X; Zhu, Ting
2013-02-13
Lithium-ion batteries have revolutionized portable electronics and will be a key to electrifying transport vehicles and delivering renewable electricity. Amorphous silicon (a-Si) is being intensively studied as a high-capacity anode material for next-generation lithium-ion batteries. Its lithiation has been widely thought to occur through a single-phase mechanism with gentle Li profiles, thus offering a significant potential for mitigating pulverization and capacity fade. Here, we discover a surprising two-phase process of electrochemical lithiation in a-Si by using in situ transmission electron microscopy. The lithiation occurs by the movement of a sharp phase boundary between the a-Si reactant and an amorphous Li(x)Si (a-Li(x)Si, x ~ 2.5) product. Such a striking amorphous-amorphous interface exists until the remaining a-Si is consumed. Then a second step of lithiation sets in without a visible interface, resulting in the final product of a-Li(x)Si (x ~ 3.75). We show that the two-phase lithiation can be the fundamental mechanism underpinning the anomalous morphological change of microfabricated a-Si electrodes, i.e., from a disk shape to a dome shape. Our results represent a significant step toward the understanding of the electrochemically driven reaction and degradation in amorphous materials, which is critical to the development of microstructurally stable electrodes for high-performance lithium-ion batteries.
Droplets formation and merging in two-phase flow microfluidics.
Gu, Hao; Duits, Michel H G; Mugele, Frieder
2011-01-01
Two-phase flow microfluidics is emerging as a popular technology for a wide range of applications involving high throughput such as encapsulation, chemical synthesis and biochemical assays. Within this platform, the formation and merging of droplets inside an immiscible carrier fluid are two key procedures: (i) the emulsification step should lead to a very well controlled drop size (distribution); and (ii) the use of droplet as micro-reactors requires a reliable merging. A novel trend within this field is the use of additional active means of control besides the commonly used hydrodynamic manipulation. Electric fields are especially suitable for this, due to quantitative control over the amplitude and time dependence of the signals, and the flexibility in designing micro-electrode geometries. With this, the formation and merging of droplets can be achieved on-demand and with high precision. In this review on two-phase flow microfluidics, particular emphasis is given on these aspects. Also recent innovations in microfabrication technologies used for this purpose will be discussed.
Acute cholecystitis: two-phase spiral CT finding
Energy Technology Data Exchange (ETDEWEB)
Oh, Eung Young; Yoon, Myung Hwan; Yang, Dal Mo; Chun Seok; Bae, Jun Gi; Kim, Hak Soo; Kim, Hyung Sik [Chungang Ghil Hospital, Incheon (Korea, Republic of)
1998-07-01
To describe the two-phase spiral CT findings of acute cholecystitis. Materials and Methods : CT scans of nine patients with surgically-proven acute cholecystitis were retrospectively reviewed for wall thickening, enhancement pattern of the wall, attenuation of the liver adjacent to the gallbladder, gallstones,gallbladder distension, gas collection within the gallbladder, pericholecystic fluid and infiltration of pericholecystic fat. Results : In all cases, wall thickening of the gallbladder was seen, though this was more distinct on delayed images, Using high-low-high attenuation, one layer was seen in five cases, nd three layers in four. On arterial images, eight cases showed transient focal increased attenuation of the liver adjacent to the gall bladder;four of these showed curvilinear attenuation and four showed subsegmental attenuation. One case showed curvilinear decreased attenuation between increased attenuation of the liver and the gallbladder, and during surgery, severe adhesion between the liver and gallbladder was confirmed. Additional CT findings were infiltration of pericholecystic fat (n=9), gallstones (n=7), gallbladder distension (n=6), pericholecystic fluid(n=3), and gas collection within the gallbladder (n=2). Conclusion : In patients with acute cholecystitis,two-phase spiral CT revealed wall thickening in one or three layers ; on delayed images this was more distinct. In many cases, arterial images showed transient focal increased attenuation of the liver adjacent to the gallbladder.
Experimental study of a two-phase surface jet
Perret, Matias; Esmaeilpour, Mehdi; Politano, Marcela S.; Carrica, Pablo M.
2013-04-01
Results of an experimental study of a two-phase jet are presented, with the jet issued near and below a free surface, parallel to it. The jet under study is isothermal and in fresh water, with air injectors that allow variation of the inlet air volume fraction between 0 and 13 %. Measurements of water velocity have been performed using LDV, and the jet exit conditions measured with PIV. Air volume fraction, bubble velocity and chord length distributions were measured with sapphire optical local phase detection probes. The mean free surface elevation and RMS fluctuations were obtained using local phase detection probes as well. Visualization was performed with laser-induced fluorescence. Measurements reveal that the mean free surface elevation and turbulent fluctuations significantly increase with the injection of air. The water normal Reynolds stresses are damped by the presence of bubbles in the bulk of the liquid, but very close to the free surface the effect is reversed and the normal Reynolds stresses increase slightly for the bubbly flow. The Reynolds shear stresses time it takes the bubbles to pierce the free surface, resulting in a considerable increase in the local air volume fraction. In addition to first explore a bubbly surface jet, the comprehensive dataset reported herein can be used to validate two-phase flow models and computational tools.
Experimental study of two phase flow in inclined channel
Energy Technology Data Exchange (ETDEWEB)
Park, Goon Cherl; Lee, Tae Ho; Lee, Sang Won [Seoul National University, Seoul (Korea, Republic of)
1997-07-01
Local two-phase flow parameters were measured to investigate the internal flow structures of steam-water boiling flow in an inclined channel. The vapor phase local flow parameters, such as void fraction, bubble frequency, vapor velocity, interfacial area concentration and chord length, were measured, using two conductivity probe method, and local liquid phase velocity was measured by pitot tube. In order to investigate the effects of channel inclination on two phase flow structure, the experiments were conducted for three angles of inclination; 0 degree(vertical), 30 degree and 60 degree. The experimental flow conditions were confined to the liquid superficial velocities less than 1.4 m/sec and nearly atmospheric pressure, and the flow regime was limited to the subcooled boiling. Using the measured distributions of the local phasic parameters, correlations for the drift-flux parameters such as distribution parameter and drift velocity were proposed. Those correlations were compared with the available correlation applicable to the inclined channel by the calculation of average void fraction using the present data. 44 refs., 4 tabs., 88 figs. (author)
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
In the investigation of effect of KSCN on the partitioning of lysozyme in PEG2000/ammonium sulfate aqueous two-phase system, it was found that the KSCN could alter the pH difference between the two phases, and thus affect the partition of lysozyme. The relationship between partition coefficients of lysozyme and pH differences between two phases was discussed.
DESIGN OF TWO-PHASE SINUSOIDAL POWER CLOCK AND CLOCKED TRANSMISSION GATE ADIABATIC LOGIC CIRCUIT
Institute of Scientific and Technical Information of China (English)
Wang Pengjun; Yu Junjun
2007-01-01
First the research is conducted on the design of the two-phase sinusoidal power clock generator in this paper. Then the design of the new adiabatic logic circuit adopting the two-phase sinusoidal power clocks-Clocked Transmission Gate Adiabatic Logic (CTGAL) circuit is presented. This circuit makes use of the clocked transmission gates to sample the input signals, then the output loads are charged and discharged in a fully adiabatic manner by using bootstrapped N-Channel Metal Oxide Semiconductor (NMOS) and Complementary Metal Oxide Semiconductor (CMOS) latch structure.Finally, with the parameters of Taiwan Semiconductor Manufacturing Company (TSMC) 0.25 μm CMOS device, the transient energy consumption of CTGAL, Bootstrap Charge-Recovery Logic (BCRL)and Pass-transistor Adiabatic Logic (PAL) including their clock generators is simulated. The simulation result indicates that CTGAL circuit has the characteristic of remarkably low energy consumption.
Numerical simulation of air-water two-phase flow over stepped spillways
Institute of Scientific and Technical Information of China (English)
CHENG; Xiangju; CHEN; Yongcan
2006-01-01
Stepped spillways for significant energy dissipation along the chute have gained interest and popularity among researchers and dam engineers. Due to the complexity of air-water two-phase flow over stepped spillways, the finite volume computational fluid dynamics module of the FLUENT software was used to simulate the main characteristics of the flow. Adopting the RNG k-ε turbulence model, the mixture flow model for air-water two-phase flow was used to simulate the flow field over stepped spillway with the PISO arithmetic technique. The numerical result successfully reproduced the complex flow over a stepped spillway of an experiment case, including the interaction between entrained air bubbles and cavity recirculation in the skimming flow regime, velocity distribution and the pressure profiles on the step surface as well. The result is helpful for understanding the detailed information about energy dissipation over stepped spillways.
Effect of grain size reduction on high temperature oxidation ofbinary two-phase alloys
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The effect of grain size reduction on the high temperature oxidation of binary two-phase alloys was discussed based on the recent research progress. The results show that for those two-phase alloys with coarse grain prepared by the conventional methods, complex oxide scales are easily formed after oxidation under high oxygen pressure or under oxygen pressure below the stability limit of the less reactive component oxides. On the contrary, for the nano-sized alloys, an exclusive external oxidation of the most reactive component usually occurs during oxidation in air or pure oxygen even for much lower content of the most reactive component. So the gain size reduction is not always beneficial to improve the oxidation resistance of the materials, but exhibits different effects depending mainly on the protective feature of the scales. The transition mechanisms between the different oxidation modes are discussed with respect to the thermodynamic and dynamic aspects.
Contrast enhanced two-phase spiral CT of urinary bladder
Energy Technology Data Exchange (ETDEWEB)
Park, Jeung Uk; Cha, Seong Sook; Ryu, Ji Hwa; Oh, Jeong Geun; Chang, Seung Kuk; Choi, Seok Jin; Eun, Choong Kie [Inje Univ. College of Medicine, Pusan (Korea, Republic of); Seo, Chang Hye [Daedong General Hospital, Pusan (Korea, Republic of)
1997-10-01
To determine optimal scan time for the early phase of two-phase spiral CT and to evaluate its usefulness in the detection and assessment of extension of urinary bladder lesions. In four normal adults, we performed dynamic scanning and obtained time-density curves for internal and external iliac arteries and veins, and the wall of the urinary bladder. Sixty patients with 68 lesions of the urinary bladder or prostate underwent precontrast and two-phase spiral CT scanning. After injection of 100ml of noninonic contrast material, images for the early and delayed phases were obtained at 60 seconds and 5 minutes, respectively. We measured CT H. U. of the wall, the lesion, and lumen of urinary bladder as seen on axial scanning, in each image in which the lesion was best shown. For the detection of bladder lesions and assessment of their extension, precontrast, early-, and delayed phsed images were compared. Dynamic study of normal adults showed maximum enhancement of bladder wall between 60 and 100 seconds. The difference of CT H. U. between bladder wall and the lesion was greatest in the early phase. The best detection rate(98.5%) was seen during this phase, and for the detection of bladder lesion, this same phase was superior or equal (66/68, 97.1%) to the delayed phase. The precontrast image was also superior or equal (31/68, 45.6%) to that of the delayed phase. For the assessment of extension of bladder lesion, the early phase was superior (36/68, 52.9%) to the delayed phase, and precontrast image was superiour (1/68, 1.5%) to that of the delayed phase. For determining the stage of bladder cancer, the early phase was most accurate if the stages was below B{sub 2} or D, while for stage C, the delayed phase was most accurate. In two-hpase spiral CT scanning, we consider the optimal time for the early phase to be between 60 and 100 seconds after injection of contrast material. For the detection and assessment of extension of urinary bladder lesion, the early phase was
Stability of stratified two-phase flows in horizontal channels
Barmak, Ilya; Ullmann, Amos; Brauner, Neima; Vitoshkin, Helen
2016-01-01
Linear stability of stratified two-phase flows in horizontal channels to arbitrary wavenumber disturbances is studied. The problem is reduced to Orr-Sommerfeld equations for the stream function disturbances, defined in each sublayer and coupled via boundary conditions that account also for possible interface deformation and capillary forces. Applying the Chebyshev collocation method, the equations and interface boundary conditions are reduced to the generalized eigenvalue problems solved by standard means of numerical linear algebra for the entire spectrum of eigenvalues and the associated eigenvectors. Some additional conclusions concerning the instability nature are derived from the most unstable perturbation patterns. The results are summarized in the form of stability maps showing the operational conditions at which a stratified-smooth flow pattern is stable. It is found that for gas-liquid and liquid-liquid systems the stratified flow with smooth interface is stable only in confined zone of relatively lo...
Two-phase microfluidics: thermophysical fundamentals and engineering concepts
Kuznetsov, V. V.
2016-10-01
Thermophysical fundamentals and engineering concepts of the two-phase microfluidic devises based on controlled liquid decay are discussed in this paper. The results of an experimental study of the explosive evaporation at a thin film heater of the MEMS devise in application to thermal inkjet printing are presented. The peculiarities of homogeneous nucleation and bubble growth in the liquid subjected to pulse heating are discussed. Using experimental data a simple equation suitable for predicting the growth rate of a vapor bubble in a non-uniformly superheated liquid was obtained and used to complete a mathematical model of the self-consistent nucleation and vapor bubbles growth in the induced pressure field. The results of numerical calculations according to the proposed model showed good agreement with the experimental data on a time of nucleation and duration of the initial stage of an explosive evaporation of water.
Two-phase flow instability in a parallel multichannel system
Institute of Scientific and Technical Information of China (English)
HOU Suxia
2009-01-01
The two-phase flow instabilities observed in through parallel multichannel can be classified into three types, of which only one is intrinsic to parallel multichannel systems. The intrinsic instabilities observed in parallel multichannel system have been studied experimentally. The stable boundary of the flow in such a parallel-channel system are sought, and the nature of inlet flow oscillation in the unstable region has been examined experimentally under various conditions of inlet velocity, heat flux, liquid temperature, cross section of channel and entrance throttling. The results show that parallel multichannel system possess a characteristic oscillation that is quite independent of the magnitude and duration of the initial disturbance, and the stable boundary is influenced by the characteristic frequency of the system as well as by the exit quality when this is low, and upon raising the exit quality and reducing the characteristic frequency, the system increases its instability, and entrance throttling effectively contributes to stabilization of the system.
Response of two-phase droplets to intense electromagnetic radiation
Energy Technology Data Exchange (ETDEWEB)
Spann, J.F. (Morgantown Energy Technology Center, U.S. Department of Energy, P.O. Box 880, Morgantown, West Virginia 26507-0880 (United States)); Maloney, D.J.; Lawson, W.F.; Casleton, K.H. (Morgantown Energy Technology Center, U.S. Department of Energy, P.O. Box 880, Morgantown, West Virginia 26507-0880 (United States))
1993-04-20
The response of two-phase droplets to intense radiant heating is studied to determine the incident power that is required for causing explosive boiling in the liquid phase. The droplets studied consist of strongly absorbing coal particles dispersed in a weakly absorbing water medium. Experiments are performed by confining droplets (radii = 37, 55, and 80 [mu]m) electrodynamically and irradiating them from two sides with pulsed laser beams. Emphasis is placed on the transition region from accelerated droplet vaporization to droplet superheating and explosive boiling. The time scale observed for explosive boiling is more than 2 orders of magnitude longer than published values for pure liquids. The delayed response is the result of energy transfer limitations between the absorbing solid phase and the surrounding liquid.
Mathematical model of two-phase flow in accelerator channel
Directory of Open Access Journals (Sweden)
О.Ф. Нікулін
2010-01-01
Full Text Available The problem of two-phase flow composed of energy-carrier phase (Newtonian liquid and solid fine-dispersed phase (particles in counter jet mill accelerator channel is considered. The mathematical model bases goes on the supposition that the phases interact with each other like independent substances by means of aerodynamics’ forces in conditions of adiabatic flow. The mathematical model in the form of system of differential equations of order 11 is represented. Derivations of equations by base physical principles for cross-section-averaged quantity are produced. The mathematical model can be used for estimation of any kinematic and thermodynamic flow characteristics for purposely parameters optimization problem solving and transfer functions determination, that take place in counter jet mill accelerator channel design.
Two phase coexistence for the hydrogen-helium mixture
Fantoni, Riccardo
2015-01-01
We use our newly constructed quantum Gibbs ensemble Monte Carlo algorithm to perform computer experiments for the two phase coexistence of a hydrogen-helium mixture. Our results are in quantitative agreement with the experimental results of C. M. Sneed, W. B. Streett, R. E. Sonntag, and G. J. Van Wylen. The difference between our results and the experimental ones is in all cases less than 15% relative to the experiment, reducing to less than 5% in the low helium concentration phase. At the gravitational inversion between the vapor and the liquid phase, at low temperatures and high pressures, the quantum effects become relevant. At extremely low temperature and pressure the first component to show superfluidity is the helium in the vapor phase.
Phase appearance or disappearance in two-phase flows
Cordier, Floraine; Kumbaro, Anela
2011-01-01
This paper is devoted to the treatment of specific numerical problems which appear when phase appearance or disappearance occurs in models of two-phase flows. Such models have crucial importance in many industrial areas such as nuclear power plant safety studies. In this paper, two outstanding problems are identified: first, the loss of hyperbolicity of the system when a phase appears or disappears and second, the lack of positivity of standard shock capturing schemes such as the Roe scheme. After an asymptotic study of the model, this paper proposes accurate and robust numerical methods adapted to the simulation of phase appearance or disappearance. Polynomial solvers are developed to avoid the use of eigenvectors which are needed in usual shock capturing schemes, and a method based on an adaptive numerical diffusion is designed to treat the positivity problems. An alternate method, based on the use of the hyperbolic tangent function instead of a polynomial, is also considered. Numerical results are presente...
Two-phase flow simulation of aeration on stepped spillway
Institute of Scientific and Technical Information of China (English)
CHENG Xiangju; LUO Lin; ZHAO Wenqian; LI Ran
2004-01-01
Stepped spillways have existed as escape works for a very long time. It is found that water can trap a lot of air when passing through steps and then increasing oxygen content in water body, so stepped spillways can be used as a measure of re-aeration and to improve water quality of water body. However, there is no reliable theoretical method on quantitative calculation of re-aeration ability for the stepped spillways. By introducing an air-water two-phase flow model, this paper used k-ε turbulence model to calculate the characteristic variables of free-surface aeration on stepped spillway. The calculated results fit with the experimental results well. It supports that the numerical modeling method is reasonable and offers firm foundation on calculating re-aeration ability of stepped spillways. The simulation approach can provide a possible optimization tool for designing stepped spillways of more efficient aeration capability.
A TWO-PHASE APPROACH TO FUZZY SYSTEM IDENTIFICATION
Institute of Scientific and Technical Information of China (English)
Ta-Wei HUNG; Shu-Cherng FANG; Henry L.W.NUTTLE
2003-01-01
A two-phase approach to fuzzy system identification is proposed. The first phase produces a baseline design to identify a prototype fuzzy system for a target system from a coIlection of input-output data pairs. It uses two easily implemented clustering techniques: the subtractive clustering method and the fuzzy c-means (FCM) clustering algorithm. The second phase (fine tuning)is executed to adjust the parameters identified in the baseline design. This phase uses the steepest descent and recursive least-squares estimation methods. The proposed approach is validated by applying it to both a function approximation type of problem and a classification type of problem. An analysis of the learning behavior of the proposed approach for the two test problems is conducted for further confirmation.
Solutal Marangoni instability in layered two-phase flows
Picardo, Jason R; Pushpavanam, S
2015-01-01
In this paper, the instability of layered two-phase flows caused by the presence of a soluble surfactant (or a surface active solute) is studied. The fluids have different viscosities, but are density matched to focus on Marangoni effects. The fluids flow between two flat plates, which are maintained at different solute concentrations. This establishes a constant flux of solute from one fluid to the other in the base state. A linear stability analysis is performed, using a combination of asymptotic and numerical methods. In the creeping flow regime, Marangoni stresses destabilize the flow, provided a concentration gradient is maintained across the fluids. One long wave and two short wave Marangoni instability modes arise, in different regions of parameter space. A well-defined condition for the long wave instability is determined in terms of the viscosity and thickness ratios of the fluids, and the direction of mass transfer. Energy budget calculations show that the Marangoni stresses that drive long and shor...
Two-Phase Algorithm for Optimal Camera Placement
Directory of Open Access Journals (Sweden)
Jun-Woo Ahn
2016-01-01
Full Text Available As markers for visual sensor networks have become larger, interest in the optimal camera placement problem has continued to increase. The most featured solution for the optimal camera placement problem is based on binary integer programming (BIP. Due to the NP-hard characteristic of the optimal camera placement problem, however, it is difficult to find a solution for a complex, real-world problem using BIP. Many approximation algorithms have been developed to solve this problem. In this paper, a two-phase algorithm is proposed as an approximation algorithm based on BIP that can solve the optimal camera placement problem for a placement space larger than in current studies. This study solves the problem in three-dimensional space for a real-world structure.
Two-phase flow instabilities in a vertical annular channel
Energy Technology Data Exchange (ETDEWEB)
Babelli, I.; Nair, S.; Ishii, M. [Purdue Univ., West Lafayette, IN (United States)
1995-09-01
An experimental test facility was built to study two-phase flow instabilities in vertical annular channel with emphasis on downward flow under low pressure and low flow conditions. The specific geometry of the test section is similar to the fuel-target sub-channel of the Savannah River Site (SRS) Mark 22 fuel assembly. Critical Heat Flux (CHF) was observed following flow excursion and flow reversal in the test section. Density wave instability was not recorded in this series of experimental runs. The results of this experimental study show that flow excursion is the dominant instability mode under low flow, low pressure, and down flow conditions. The onset of instability data are plotted on the subcooling-Zuber (phase change) numbers stability plane.
Equations of two-phase flow in spray chamber
Institute of Scientific and Technical Information of China (English)
李新禹; 张志红; 金星; 徐杰
2009-01-01
The downstream water-air heat and moisture transfer system in a moving coordinate was studied. The relationship between the diameter of the misted droplets and the spray pressure was determined. Based on the theory of the relative velocity,the two-phase flow mode of the spray chamber and the efficiency equation for heat and moisture exchange were established. Corrections were carried out for the efficiency equation with spray pressure of 157 kPa. The results show that the pressure plays an important part in determining the efficiency of heat and moisture exchange. When the spray pressure is less than 157 kPa,better coincidence is noticed between the theoretical analysis and the test results with the error less than 6%. Greater error will be resulted in the case when the spray pressure is beyond 157 kPa. After the correction treatment,the coincidence between the theoretical and the experimental results is greatly improved.
Transient thermohydraulic modeling of two-phase fluid systems
Blet, N.; Delalandre, N.; Ayel, V.; Bertin, Y.; Romestant, C.; Platel, V.
2012-11-01
This paper presents a transient thermohydraulic modeling, initially developed for a capillary pumped loop in gravitational applications, but also possibly suitable for all kinds of two-phase fluid systems. Using finite volumes method, it is based on Navier-Stokes equations for transcribing fluid mechanical aspects. The main feature of this 1D-model is based on a network representation by analogy with electrical. This paper also proposes a parametric study of a counterflow condenser following the sensitivity to inlet mass flow rate and cold source temperature. The comparison between modeling results and experimental data highlights a good numerical evaluation of temperatures. Furthermore, the model is able to represent a pretty good dynamic evolution of hydraulic variables.
Flooding in counter-current two-phase flow
Energy Technology Data Exchange (ETDEWEB)
Ragland, W.A.; Ganic, E.N.
1982-01-01
Flooding is a phenomenon which is best described as the transition from counter-current to co-current flow. Early notice was taken of this phenomenon in the chemical engineering industry. Flooding also plays an important role in the field of two-phase heat transfer since it is a limit for many systems involving counter-current flow. Practical applications of flooding limited processes include wickless thermosyphons and the emergency core cooling system (ECCS) of pressurized water nuclear reactors. The phenomenon of flooding also is involved in the behavior of nuclear reactor core materials during severe accident conditions where flooding is one of the mechanisms governing the motion of the molten fuel pin cladding.
Response of two-phase droplets to intense electromagnetic radiation
Spann, James F.; Maloney, Daniel J.; Lawson, William F.; Casleton, Kent H.
1993-01-01
The response of two-phase droplets to intense radiant heating is studied to determine the incident power that is required for causing explosive boiling in the liquid phase. The droplets studied consist of strongly absorbing coal particles dispersed in a weakly absorbing water medium. Experiments are performed by confining droplets (radii of 37, 55, and 80 microns) electrodynamically and irradiating them from two sides with pulsed laser beams. Emphasis is placed on the transition region from accelerated droplet vaporization to droplet superheating and explosive boiling. The time scale observed for explosive boiling is more than 2 orders of magnitude longer than published values for pure liquids. The delayed response is the result of energy transfer limitations between the absorbing solid phase and the surrounding liquid.
Note on Two-Phase Phenomena in Financial Markets
Institute of Scientific and Technical Information of China (English)
JIANG Shi-Mei; CAI Shi-Min; ZHOU Wao; ZHOU Pei-Ling
2008-01-01
The two-phase behaviour in financial markets actually means the bifurcation phenomenon, which represents the change of the conditional probability from an unimodal to a bimodal distribution. We investigate the bifurcation phenomenon in Hang-Seng index. It is observed that the bifurcation phenomenon in financial index is not universal, but specific under certain conditions. For Hang-Seng index and randomly generated time series, the phenomenon just emerges when the power-law exponent of absolute increment distribution is between i and 2 with appropriate period. Simulations on a randomly generated time series suggest the bifurcation phenomenon itself is subject to the statistics of absolute increment, thus it may not be able to reflect essential financial behaviours. However, even under the same distribution of absolute increment, the range where bifurcation phenomenon occurs is far different from real market to artificial data, which may reflect certain market information.
Thirty-two phase sequences design with good autocorrelation properties
Indian Academy of Sciences (India)
S P Singh; K Subba Rao
2010-02-01
Polyphase Barker Sequences are ﬁnite length, uniform complex sequences; the magnitude of their aperiodic autocorrelation sidelobes are bounded by 1. Such sequences have been used in numerous real-world applications such as channel estimation, radar and spread spectrum communication. In this paper, thirty-two phase Barker sequences up to length 24 with an alphabet size of only 32 are presented. The sequences from length 25 to 289 have autocorrelation properties better than well-known Frank codes. Because of the complex structure the sequences are very difﬁcult to detect and analyse by an enemy’s electronic support measures (ESMs). The synthesized sequences are promising for practical application to radar and spread spectrum communication systems. These sequences are found using the Modiﬁed Simulated Annealing Algorithm (MSAA). The convergence rate of the algorithm is good.
Two-phase methanization of food wastes in pilot scale.
Lee, J P; Lee, J S; Park, S C
1999-01-01
A 5 ton/d pilot scale two-phase anaerobic digester was constructed and tested to treat Korean food wastes in Anyang city near Seoul. The easily degradable presorted food waste was efficiently treated in the two-phase anaerobic digestion process. The waste contained in plastic bags was shredded and then screened for the removal of inert materials such as fabrics and plastics, and subsequently put into the two-stage reactors. Heavy and light inerts such as bones, shells, spoons, and plastic pieces were again removed by gravity differences. The residual organic component was effectively hydrolyzed and acidified in the first reactor with 5 d space time at pH of about 6.5. The second, methanization reactor converted the acids into methane with pH between 7.4 and 7.8. The space time for the second reactor was 15 d. The effluent from the second reactor was recycled to the first reactor to provide alkalinities. The process showed stable steady-state operation with the maximum organic loading rate of 7.9 kg volatile solid (VS)/m3/d and the volatile solid reduction efficiency of about 70%. The total of 3.6 tons presorted MSW containing 2.9 tons of food organic was treated to produce about 230 m3 of biogas with 70% (v/v) of methane and 80 kg of humus. This process is extended to full-scale treating 15 tons of food waste a day in Euiwang city and the produced biogas is utilized for the heating/cooling of adjacent buildings.
Correct numerical simulation of a two-phase coolant
Kroshilin, A. E.; Kroshilin, V. E.
2016-02-01
Different models used in calculating flows of a two-phase coolant are analyzed. A system of differential equations describing the flow is presented; the hyperbolicity and stability of stationary solutions of the system is studied. The correctness of the Cauchy problem is considered. The models' ability to describe the following flows is analyzed: stable bubble and gas-droplet flows; stable flow with a level such that the bubble and gas-droplet flows are observed under and above it, respectively; and propagation of a perturbation of the phase concentration for the bubble and gas-droplet media. The solution of the problem about the breakdown of an arbitrary discontinuity has been constructed. Characteristic times of the development of an instability at different parameters of the flow are presented. Conditions at which the instability does not make it possible to perform the calculation are determined. The Riemann invariants for the nonlinear problem under consideration have been constructed. Numerical calculations have been performed for different conditions. The influence of viscosity on the structure of the discontinuity front is studied. Advantages of divergent equations are demonstrated. It is proven that a model used in almost all known investigating thermohydraulic programs, both in Russia and abroad, has significant disadvantages; in particular, it can lead to unstable solutions, which makes it necessary to introduce smoothing mechanisms and a very small step for describing regimes with a level. This does not allow one to use efficient numerical schemes for calculating the flow of two-phase currents. A possible model free from the abovementioned disadvantages is proposed.
Supporting universal prevention programs: a two-phased coaching model.
Becker, Kimberly D; Darney, Dana; Domitrovich, Celene; Keperling, Jennifer Pitchford; Ialongo, Nicholas S
2013-06-01
Schools are adopting evidence-based programs designed to enhance students' emotional and behavioral competencies at increasing rates (Hemmeter et al. in Early Child Res Q 26:96-109, 2011). At the same time, teachers express the need for increased support surrounding implementation of these evidence-based programs (Carter and Van Norman in Early Child Educ 38:279-288, 2010). Ongoing professional development in the form of coaching may enhance teacher skills and implementation (Noell et al. in School Psychol Rev 34:87-106, 2005; Stormont et al. 2012). There exists a need for a coaching model that can be applied to a variety of teacher skill levels and one that guides coach decision-making about how best to support teachers. This article provides a detailed account of a two-phased coaching model with empirical support developed and tested with coaches and teachers in urban schools (Becker et al. 2013). In the initial universal coaching phase, all teachers receive the same coaching elements regardless of their skill level. Then, in the tailored coaching phase, coaching varies according to the strengths and needs of each teacher. Specifically, more intensive coaching strategies are used only with teachers who need additional coaching supports, whereas other teachers receive just enough support to consolidate and maintain their strong implementation. Examples of how coaches used the two-phased coaching model when working with teachers who were implementing two universal prevention programs (i.e., the PATHS curriculum and PAX Good Behavior Game [PAX GBG]) provide illustrations of the application of this model. The potential reach of this coaching model extends to other school-based programs as well as other settings in which coaches partner with interventionists to implement evidence-based programs.
Influences of physical properties of two-phase mixture on void fraction in an annular vessel
Institute of Scientific and Technical Information of China (English)
LI Xiao-Ming; BI Qin-Cheng; FENG Quan-Ke; CHEN Ting-Kuan; DU She-Jiao
2004-01-01
To keep the void fraction of two-phase hydrogen in the moderator cell of the cold neutron source (CNS)of China Advanced Research Reactor (CARR) to a specified range, an annular vessel with the same size as the actual moderator cell was used as test section. Deionized water and alcohol, sucrose, and sodium chloride solutions with different concentrations were used as working fluid to find out influences of physical properties, such as density, viscosity and surface tension, of the two-phase mixture on void fraction. The tests proved that the ratio of surface tension to density of liquid phase has great influence on void fraction: the larger the ratio, the smaller the void fraction.Since the ratio of surface tension to density of Freon 113 is lower than that of liquid hydrogen, Freon 113 can be used as a working fluid to study the void fraction in the two-phase hydrogen thermosiphon loop in the CNS of CARR and the results will be conservative.
Application of stereology for two-phase flow structure validation in fluidized bed reactors
Directory of Open Access Journals (Sweden)
Anweiler Stanisław
2016-01-01
Full Text Available Paper describes a novel method for two-phase gas-solid flow structure validation in fluidized bed reactors. Investigation is based on application of stereology techniques. This is an innovative approach in the field of fluidization phenomena research. Study is focused on the analysis of flow structure images, obtained with high-speed visualization of the fluidization process. Fluidization is conducted in transparent narrow channel, where plastic balls are fluidized by air. Applied stereological analysis is grounded on the linear method and on the method of random and directed secants. This enables 2-dimensional image measurement and 3-dimensional stereological extrapolation. The major result is that for each two-phase gas-solid flow structure a set of stereological parameters exists. This enables quantification of the process. It has been found that the observation of inter-relation of all stereological parameters, during the changing of the flow structure, can be used for system control. The basic conclusion is that knowledge about the character of the changes may be used for constant process adjustment for various two phase systems such as gas-solid or gas-liquid.
A Heat Transfer Investigation of Liquid and Two-Phase Methane
VanNoord, Jonathan
2010-01-01
A heat transfer investigation was conducted for liquid and two-phase methane. The tests were conducted at the NASA Glenn Research Center Heated Tube Facility (HTF) using resistively heated tube sections to simulate conditions encountered in regeneratively cooled rocket engines. This testing is part of NASA s Propulsion and Cryogenics Advanced Development (PCAD) project. Nontoxic propellants, such as liquid oxygen/liquid methane (LO2/LCH4), offer potential benefits in both performance and safety over equivalently sized hypergolic propulsion systems in spacecraft applications. Regeneratively cooled thrust chambers are one solution for high performance, robust LO2/LCH4 engines, but cooling data on methane is limited. Several test runs were conducted using three different diameter Inconel 600 tubes, with nominal inner diameters of 0.0225-, 0.054-, and 0.075-in. The mass flow rate was varied from 0.005 to 0.07 lbm/sec. As the current focus of the PCAD project is on pressure fed engines for LO2/LCH4, the average test section outlet pressures were targeted to be 200 psia or 500 psia. The heat flux was incrementally increased for each test condition while the test section wall temperatures were monitored. A maximum average heat flux of 6.2 Btu/in.2 sec was achieved and, at times, the temperatures of the test sections reached in excess of 1800 R. The primary objective of the tests was to produce heat transfer correlations for methane in the liquid and two-phase regime. For two-phase flow testing, the critical heat flux values were determined where the fluid transitions from nucleate boiling to film boiling. A secondary goal of the testing was to measure system pressure drops in the two-phase regime.
Experience with the Multi-Year Implementation of an Industrial Control System
Kuhn, H K; Juillerat, A C; Rabany, Michel; Wollès, J C
2000-01-01
In 1990, CERN passed a multi-year purchasing and installation contract for the LEP 200 Cryogenics control system with ABB, one of the world's leading suppliers of integrated Distributed Control Systems (DCS). A financial framework provided over a period of eight years the required supplies. These were called up with so called "Release Orders", taking into account the latest technical developments. The issues and experiences with such a new approach and the resulting control system are described.
Advanced reactors transition FY 1997 multi-year work plan WBS 7.3
Energy Technology Data Exchange (ETDEWEB)
Hulvey, R.K.
1996-09-27
This document describes in detail the work to be accomplised in FY 1997 and the out-years for the Advanced Reactors Transition (WBS 7.3) under the management of the Babcock & Wilcox Hanford Company. This document also includes specific milestones and funding profiles. Based upon the Fiscal Year 1997 Multi-Year Work Plan, the Department of Energy will provide authorization to perform the work described.
Creep of Two-Phase Microstructures for Microelectronic Applications
Energy Technology Data Exchange (ETDEWEB)
Reynolds, Heidi Linch [Univ. of California, Berkeley, CA (United States)
1998-12-01
The mechanical properties of low-melting temperature alloys are highly influenced by their creep behavior. This study investigates the dominant mechanisms that control creep behavior of two-phase, low-melting temperature alloys as a function of microstructure. The alloy systems selected for study were In-Ag and Sn-Bi because their eutectic compositions represent distinctly different microstructure.” The In-Ag eutectic contains a discontinuous phase while the Sn-Bi eutectic consists of two continuous phases. In addition, this work generates useful engineering data on Pb-free alloys with a joint specimen geometry that simulates microstructure found in microelectronic applications. The use of joint test specimens allows for observations regarding the practical attainability of superplastic microstructure in real solder joints by varying the cooling rate. Steady-state creep properties of In-Ag eutectic, Sn-Bi eutectic, Sn-xBi solid-solution and pure Bi joints have been measured using constant load tests at temperatures ranging from O°C to 90°C. Constitutive equations are derived to describe the steady-state creep behavior for In-Ageutectic solder joints and Sn-xBi solid-solution joints. The data are well represented by an equation of the form proposed by Dom: a power-law equation applies to each independent creep mechanism. Rate-controlling creep mechanisms, as a function of applied shear stress, test temperature, and joint microstructure, are discussed. Literature data on the steady-state creep properties of Sn-Bi eutectic are reviewed and compared with the Sn-xBi solid-solution and pure Bi joint data measured in the current study. The role of constituent phases in controlling eutectic creep behavior is discussed for both alloy systems. In general, for continuous, two-phase microstructure, where each phase exhibits significantly different creep behavior, the harder or more creep resistant phase will dominate the creep behavior in a lamellar microstructure. If a
Statistical descriptions of polydisperse turbulent two-phase flows
Minier, Jean-Pierre
2016-12-01
Disperse two-phase flows are flows containing two non-miscible phases where one phase is present as a set of discrete elements dispersed in the second one. These discrete elements, or 'particles', can be droplets, bubbles or solid particles having different sizes. This situation encompasses a wide range of phenomena, from nano-particles and colloids sensitive to the molecular fluctuations of the carrier fluid to inertia particles transported by the large-scale motions of turbulent flows and, depending on the phenomenon studied, a broad spectrum of approaches have been developed. The aim of the present article is to analyze statistical models of particles in turbulent flows by addressing this issue as the extension of the classical formulations operating at a molecular or meso-molecular level of description. It has a three-fold purpose: (1) to bring out the thread of continuity between models for discrete particles in turbulent flows (above the hydrodynamical level of description) and classical mesoscopic formulations of statistical physics (below the hydrodynamical level); (2) to reveal the specific challenges met by statistical models in turbulence; (3) to establish a methodology for modeling particle dynamics in random media with non-zero space and time correlations. The presentation is therefore centered on organizing the different approaches, establishing links and clarifying physical foundations. The analysis of disperse two-phase flow models is developed by discussing: first, approaches of classical statistical physics; then, by considering models for single-phase turbulent flows; and, finally, by addressing current formulations for discrete particles in turbulent flows. This brings out that particle-based models do not cease to exist above the hydrodynamical level and offer great interest when combined with proper stochastic formulations to account for the lack of equilibrium distributions and scale separation. In the course of this study, general results
Gadomski, P.; Finnegan, D. C.; Lawson, D. E.; Hanlon, G.
2009-12-01
Quantitative high-resolution, multi-year datasets on tidewater glacier terminus activity are difficult and expensive to obtain and few in number. Furthermore, numerous factors influence terminus dynamics, thus requiring a holistic approach to data gathering to understand such activity. This paper describes ongoing research at Hubbard Glacier in Southeast Alaska and how these efforts are improving our understanding of an actively advancing tidewater margin. Hubbard Glacier, the largest tidewater glacier in North America, flows ~125 km from Mt Logan (5959 m) in the St. Elias Mountains to sea level where its terminus continues to thicken, widen and advance at an average rate of 32m/yr. Continued advance of the Hubbard Glacier may dam the channel linking Russell Fiord with Disenchantment Bay and potentially result in flooding of the Situk River destroying a fishery that provides the economic base for the community of Yakutat. As part of a multi-year investigation to monitor and assess the risk of dam formation by Hubbard Glacier, near real-time meteorological and terminus motion data are being monitored, while detailed field and remote sensing investigations quantify glacier activity. These investigations have included bathymetric mapping and hydrographic surveys, aerial and ground-based LiDAR topographic surveys, time-lapse photography and recurring satellite imagery of the glacier since 2005. Over the approximate three years of continuous near-realtime field-based monitoring the duration, patterns and daily rates of terminus advance and retreat are proving to be similar from year to year. These patterns suggest that the onset of advance and retreat may be linked to climate and extreme variations in the tidal cycle are influential in slowing terminus advance and causing periods of retreat to be superimposed onto longer durations of advance. These results when linked to time-lapse photography provide insight into ice marginal mechanisms of calving, while the results of
Particle migration in two-phase, viscoelastic flows
Jaensson, Nick; Hulsen, Martien; Anderson, Patrick
2014-11-01
Particles suspended in creeping, viscoelastic flows can migrate across stream lines due to gradients in normal stresses. This phenomenon has been investigated both numerically and experimentally. However, particle migration in the presence of fluid-fluid interfaces is hardly studied. We present results of simulations in 2D and 3D of rigid spherical particles in two-phase flows, where either one or both of the fluids are viscoelastic. The fluid-fluid interface is assumed to be diffuse and is described using Cahn-Hilliard theory. The particle boundary is assumed to be sharp and is described by a boundary-fitted, moving mesh. The governing equations are solved using the finite element method. We show that differences in normal stresses between the two fluids can induce a migration of the particle towards the interface in a shear flow. Depending on the magnitude of the surface tension and the properties of the fluids, particle migration can be halted due to the induced Laplace pressure, the particle can be adsorbed at the interface, or the particle can cross the interface into the other fluid. Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven, The Netherlands.
Criteria for guaranteed breakdown in two-phase inhomogeneous bodies
Bardsley, Patrick; Primrose, Michael S.; Zhao, Michael; Boyle, Jonathan; Briggs, Nathan; Koch, Zoe; Milton, Graeme W.
2017-08-01
Lower bounds are obtained on the maximum field strength in one or both phases in a body containing two-phases. These bounds only incorporate boundary data that can be obtained from measurements at the surface of the body, and thus may be useful for determining if breakdown has necessarily occurred in one of the phases, or that some other nonlinearities have occurred. It is assumed the response of the phases is linear up to the point of electric, dielectric, or elastic breakdown, or up to the point of the onset of nonlinearities. These bounds are calculated for conductivity, with one or two sets of boundary conditions, for complex conductivity (as appropriate at fixed frequency when the wavelength is much larger than the body, i.e. for quasistatics), and for two-dimensional elasticity. Sometimes the bounds are optimal when the field is constant in one of the phases, and using the algorithm of Kang, Kim, and Milton (2012) a wide variety of inclusion shapes having this property, for appropriately chosen bodies and appropriate boundary conditions, are numerically constructed. Such inclusions are known as E_Ω -inclusions.
Thermal performance of closed two-phase thermosyphon using nanofluids
Energy Technology Data Exchange (ETDEWEB)
Khandekar, Sameer; Mehta, Balkrishna [Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Joshi, Yogesh M. [Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India)
2008-06-15
Nanofluids, stabilized suspensions of nanoparticles typically <100 nm in conventional fluids, are evolving as potential enhanced heat transfer fluids due to their improved thermal conductivity, increase in single phase heat transfer coefficient and significant increase in critical boiling heat flux. In the present paper, we investigate the overall thermal resistance of closed two-phase thermosyphon using pure water and various water based nanofluids (of Al{sub 2}O{sub 3}, CuO and laponite clay) as working fluids. We observe that all these nanofluids show inferior thermal performance than pure water. Furthermore, we observe that the wettability of all nanofluids on copper substrate, having the same average roughness as that of the thermosyphon container pipe, is better than that of pure water. A scaling analysis is presented which shows that the increase in wettability and entrapment of nanoparticles in the grooves of the surface roughness cause decrease in evaporator side Peclet number that finally leads to poor thermal performance. (author)
Aqueous Nanofluid as a Two-Phase Coolant for PWR
Directory of Open Access Journals (Sweden)
Pavel N. Alekseev
2012-01-01
Full Text Available Density fluctuations in liquid water consist of two topological kinds of instant molecular clusters. The dense ones have helical hydrogen bonds and the nondense ones are tetrahedral clusters with ice-like hydrogen bonds of water molecules. Helical ordering of protons in the dense water clusters can participate in coherent vibrations. The ramified interface of such incompatible structural elements induces clustering impurities in any aqueous solution. These additives can enhance a heat transfer of water as a two-phase coolant for PWR due to natural forming of nanoparticles with a thermal conductivity higher than water. The aqueous nanofluid as a new condensed matter has a great potential for cooling applications. It is a mixture of liquid water and dispersed phase of extremely fine quasi-solid particles usually less than 50 nm in size with the high thermal conductivity. An alternative approach is the formation of gaseous (oxygen or hydrogen nanoparticles in density fluctuations of water. It is possible to obtain stable nanobubbles that can considerably exceed the molecular solubility of oxygen (hydrogen in water. Such a nanofluid can convert the liquid water in the nonstoichiometric state and change its reduction-oxidation (RedOx potential similarly to adding oxidants (or antioxidants for applying 2D water chemistry to aqueous coolant.
Stability of stratified two-phase flows in horizontal channels
Barmak, I.; Gelfgat, A.; Vitoshkin, H.; Ullmann, A.; Brauner, N.
2016-04-01
Linear stability of stratified two-phase flows in horizontal channels to arbitrary wavenumber disturbances is studied. The problem is reduced to Orr-Sommerfeld equations for the stream function disturbances, defined in each sublayer and coupled via boundary conditions that account also for possible interface deformation and capillary forces. Applying the Chebyshev collocation method, the equations and interface boundary conditions are reduced to the generalized eigenvalue problems solved by standard means of numerical linear algebra for the entire spectrum of eigenvalues and the associated eigenvectors. Some additional conclusions concerning the instability nature are derived from the most unstable perturbation patterns. The results are summarized in the form of stability maps showing the operational conditions at which a stratified-smooth flow pattern is stable. It is found that for gas-liquid and liquid-liquid systems, the stratified flow with a smooth interface is stable only in confined zone of relatively low flow rates, which is in agreement with experiments, but is not predicted by long-wave analysis. Depending on the flow conditions, the critical perturbations can originate mainly at the interface (so-called "interfacial modes of instability") or in the bulk of one of the phases (i.e., "shear modes"). The present analysis revealed that there is no definite correlation between the type of instability and the perturbation wavelength.
Microporous silica gels from alkylsilicate-water two phase hydrolysis
Energy Technology Data Exchange (ETDEWEB)
Chu, L.; Tejedor-Tejedor, M.I.; Anderson, M.A. [Univ. of Wisconsin, Madison, WI (United States). Water Chemistry Program
1994-12-31
Microporous silica gels have been synthesized through a nano-particulate sol-gel route. These gels have uniformly distributed and extremely small pores(< 15 {angstrom} in diameter). Hydrolysis and condensation reactions leading to these gels were carried out in an alkyl silicate-water (ammonia) two phase system. These reactions took place at the alkyl silicate droplet-water interfacial boundary. No alcohol was added. A clear, stable and uniformly distributed colloidal silica suspension having an average particle size less than 6 nm was prepared by this method. Fast hydrolysis, slow condensation and low solubility all contribute to a high supersaturation level and result in the formation of small particles. This process is consistent with classic nucleation theory. When the particles are produced under acidic rather than under basic reaction conditions, smaller particles are formed due to the slower condensation rate and lower solubility of these silica particles in acidic conditions. At the same pH, alkylsilicates having smaller alkyl groups react faster with water leading to smaller primary particles. Homogeneous nucleation conditions are achieved when the water/alkylsilicate ratio is high.
Pressure transient analysis of two-phase flow problems
Energy Technology Data Exchange (ETDEWEB)
Chu, W.C.; Reynolds, A.C.; Raghavan, R.
1986-04-01
This paper considers the analysis of pressure drawdown and buildup data for two-phase flow problems. Of primary concern is the analysis of data influenced by saturation gradients that exist within the reservoir. Wellbore storage effects are assumed to be negligible. The pressure data considered are obtained from a two-dimensional (2D) numerical coning model for an oil/water system. The authors consider constant-rate production followed by a buildup period and assume that the top, bottom, and outer boundaries of the reservoir are sealed. First, they consider the case where the producing interval is equal to the total formation thickness. Second, they discuss the effect of partial penetration. In both cases, they show that average pressure can be estimated by the Matthews-Brons-Hazebroek method and consider the computation of the skin factor. They also show that a reservoir limit test can estimate reservoir PV only if the total mobility adjacent to the wellbore does not vary with time.
Two-Phase Flow Hydrodynamics in Superhydrophobic Channels
Stevens, Kimberly; Crockett, Julie; Maynes, Daniel; Iverson, Brian
2015-11-01
Superhydrophobic surfaces promote drop-wise condensation and droplet removal leading to the potential for increased thermal transport. Accordingly, great interest exists in using superhydrophobic surfaces in flow condensing environments, such as power generation and desalination. Adiabatic air-water mixtures were used to gain insight into the effect of hydrophobicity on two-phase flows and the hydrodynamics present in flow condensation. Pressure drop and onset of various flow regimes in hydrophilic, hydrophobic, and superhydrophobic mini (0.5 x 10 mm) channels were explored. Data for air/water mixtures with superficial Reynolds numbers from 20-200 and 250-1800, respectively, were obtained. Agreement between experimentally obtained pressure drops and correlations in literature for the conventional smooth control surfaces was better than 20 percent. Transitions between flow regimes for the hydrophobic and hydrophilic channels were similar to commonly recognized flow types. However, the superhydrophobic channel demonstrated significantly different flow regime behavior from conventional surfaces including a different shape of the air slugs, as discussed in the presentation.
An automated two-phase system for hydrogel microbead production.
Coutinho, Daniela F; Ahari, Amir F; Kachouie, Nezamoddin N; Gomes, Manuela E; Neves, Nuno M; Reis, Rui L; Khademhosseini, Ali
2012-09-01
Polymeric beads have been used for protection and delivery of bioactive materials, such as drugs and cells, for different biomedical applications. Here, we present a generic two-phase system for the production of polymeric microbeads of gellan gum or alginate, based on a combination of in situ polymerization and phase separation. Polymer droplets, dispensed using a syringe pump, formed polymeric microbeads while passing through a hydrophobic phase. These were then crosslinked, and thus stabilized, in a hydrophilic phase as they crossed through the hydrophobic-hydrophilic interface. The system can be adapted to different applications by replacing the bioactive material and the hydrophobic and/or the hydrophilic phases. The size of the microbeads was dependent on the system parameters, such as needle size and solution flow rate. The size and morphology of the microbeads produced by the proposed system were uniform, when parameters were kept constant. This system was successfully used for generating polymeric microbeads with encapsulated fluorescent beads, cell suspensions and cell aggregates proving its ability for generating bioactive carriers that can potentially be used for drug delivery and cell therapy.
Two-Phase Flow Field Simulation of Horizontal Steam Generators
Directory of Open Access Journals (Sweden)
Ataollah Rabiee
2017-02-01
Full Text Available The analysis of steam generators as an interface between primary and secondary circuits in light water nuclear power plants is crucial in terms of safety and design issues. VVER-1000 nuclear power plants use horizontal steam generators which demand a detailed thermal hydraulics investigation in order to predict their behavior during normal and transient operational conditions. Two phase flow field simulation on adjacent tube bundles is important in obtaining logical numerical results. However, the complexity of the tube bundles, due to geometry and arrangement, makes it complicated. Employment of porous media is suggested to simplify numerical modeling. This study presents the use of porous media to simulate the tube bundles within a general-purpose computational fluid dynamics code. Solved governing equations are generalized phase continuity, momentum, and energy equations. Boundary conditions, as one of the main challenges in this numerical analysis, are optimized. The model has been verified and tuned by simple two-dimensional geometry. It is shown that the obtained vapor volume fraction near the cold and hot collectors predict the experimental results more accurately than in previous studies.
Unsteady flow analysis of a two-phase hydraulic coupling
Hur, N.; Kwak, M.; Lee, W. J.; Moshfeghi, M.; Chang, C.-S.; Kang, N.-W.
2016-06-01
Hydraulic couplings are being widely used for torque transmitting between separate shafts. A mechanism for controlling the transmitted torque of a hydraulic system is to change the amount of working fluid inside the system. This paper numerically investigates three-dimensional turbulent flow in a real hydraulic coupling with different ratios of charged working fluid. Working fluid is assumed to be water and the Realizable k-ɛ turbulence model together with the VOF method are used to investigate two-phase flow inside the wheels. Unsteady simulations are conducted using the sliding mesh technique. The primary wheel is rotating at a fixed speed of 1780 rpm and the secondary wheel rotates at different speeds for simulating different speed ratios. Results are investigated for different blade angles, speed ratios and also different water volume fractions, and are presented in the form of flow patterns, fluid average velocity and also torques values. According to the results, blade angle severely affects the velocity vector and the transmitted torque. Also in the partially-filled cases, air is accumulated in the center of the wheel forming a toroidal shape wrapped by water and the transmitted torque sensitively depends on the water volume fraction. In addition, in the fully-filled case the transmitted torque decreases as the speed ration increases and the average velocity associated with lower speed ratios are higher.
Passive Two-Phase Cooling of Automotive Power Electronics: Preprint
Energy Technology Data Exchange (ETDEWEB)
Moreno, G.; Jeffers, J. R.; Narumanchi, S.; Bennion, K.
2014-08-01
Experiments were conducted to evaluate the use of a passive two-phase cooling strategy as a means of cooling automotive power electronics. The proposed cooling approach utilizes an indirect cooling configuration to alleviate some reliability concerns and to allow the use of conventional power modules. An inverter-scale proof-of-concept cooling system was fabricated, and tests were conducted using the refrigerants hydrofluoroolefin HFO-1234yf and hydrofluorocarbon HFC-245fa. Results demonstrated that the system can dissipate at least 3.5 kW of heat with 250 cm3 of HFC-245fa. An advanced evaporator design that incorporates features to improve performance and reduce size was conceived. Simulation results indicate its thermal resistance can be 37% to 48% lower than automotive dual side cooled power modules. Tests were also conducted to measure the thermal performance of two air-cooled condensers--plain and rifled finned tube designs. The results combined with some analysis were then used to estimate the required condenser size per operating conditions and maximum allowable system (i.e., vapor and liquid) temperatures.
Simulation and modeling of two-phase bubbly flows
Energy Technology Data Exchange (ETDEWEB)
Sylvain L Pigny; Pierre F Coste [DEN/DER/SSTH, CEA/Grenoble, 38054 Grenoble Cedex 9 (France)
2005-07-01
Full text of publication follows: Phenomena related to bubbles in two-phase recirculating flows are investigated, via the computational code SIMMER, concerning an experiment in which air is injected in the lower part of a tank filled of water and initially at rest. Averaged mass and momentum transport equations are solved for air and water. Close to the injector, the formation of individual large bubbles is represented in the calculations, via direct simulation. Small scale phenomena, related to small bubbles behavior or turbulence in the liquid continuous phase, are modeled, in a statistical way, via classical closure laws. In a first calculation, the splitting of large bubbles is not represented. It is shown that this phenomenon, the space scale of which is close to the cell size, cannot be simulated, in view of the present computational resources. Nevertheless, relatively fine meshes are used, for an accurate description of hydrodynamical phenomena, and the splitting phenomenon is too large to be modeled via closure laws. A specific approach for the intermediate scales is therefore developed to represent it. (authors)
Energy Technology Data Exchange (ETDEWEB)
Kim, Moo Hwan; Cha, Jae Eun [Pohang University of Science and Technology, Pohang (Korea)
2000-04-01
The technology which models and measures the behavior of bubble in liquid sodium is very important to insure the safety of the liquid metal reactor. In this research, we designed/ manufactured each part and loop of experimental facility for sodium two phase flow, and applied a few possible methods, measured characteristic of two phase flow such as bubbly flow. A air-water loop similar to sodium loop on each measuring condition was designed/manufactured. This air-water loop was utilized to acquire many informations which were necessary in designing the two phase flow of sodium and manufacturing experimental facility. Before the manufacture of a electromagnetic flow meter for sodium, the experiment using each electromagnetic flow mete was developed and the air-water loop was performed to understand flow characteristics. Experiments for observing the signal characteristics of flow were performed by flowing two phase mixture into the electromagnetic flow mete. From these experiments, the electromagnetic flow meter was designed and constructed by virtual electrode, its signal processing circuit and micro electro magnet. It was developed to be applicable to low conductivity fluid very successfully. By this experiment with the electromagnetic flow meter, we observed that the flow signal was very different according to void fraction in two phase flow and that probability density function which was made by statistical signal treatment is also different according to flow patterns. From this result, we confirmed that the electromagnetic flow meter could be used to understand the parameters of two phase flow of sodium. By this study, the experimental facility for two phase flow of sodium was constricted. Also the new electromagnetic flow meter was designed/manufactured, and experimental apparatus for two phase flow of air-water. Finally, this study will be a basic tool for measurement of two phase flow of sodium. As the fundamental technique for the applications of sodium at
Experimental Assessment of the Two-Phase Flow in a Large Inclined Channel
Energy Technology Data Exchange (ETDEWEB)
Nguyen, Thanh Hung; Song, Ki Won; Revankar, Shripad T; Park, Hyun Sun [Pohang University of Science and Technology, Pohang (Korea, Republic of)
2014-10-15
In order to assess the cooling performance of the core catcher system, a model facility has been constructed in POSTECH using scaling analysis. This facility consists of horizontal, inclined and vertical section. To investigate the flow parameters in each section, the instrumentation is developed to measure two-phase characteristics such as local void fraction, bubble velocity and bubble size. To date, there has been a considerable amount of research conducted on the internal structure of two-phase flow in pipe. However, the number of attempts made on the experiment regarding large inclined channels has been still limited. One of the reasons for this lack of data is the difficulty in constructing experimental facility. In this paper, the parameters of the flow in the inclined section are presented. The inclined channel is 10 degree from the horizontal with the rectangular cross section of 300 cm{sup 2}. The distributions of local parameters are evaluated through the data of double sensor conductivity probes installed at different locations along the inclined section. The data sets of the structure of two-phase flow in an inclined large channel was acquired. The air was injected through the metal foam installed on the top surface wall of the inclined section. Water level was kept below the top of the inclined section so the amount of water was fixed during the experiment. 9 probes set up at the different locations to get the data of local two-phase parameters. The measurement at each location was conducted in 5 minutes to determine the mean value of each parameter. The result of local void fraction profiles at different locations indicates that the void distribution primarily changes along the height of the inclined section. The slug flow occurs in the channel which results in most bubbles attached to the top surface wall. This fact explains the high local void fraction near the top wall and its rapid decline towards the bottom wall of the inclined section. The
NUMERICAL CALCULATION OF SOLID-LIQUID TWO PHASE FLOW BETWEEN STAY VANES IN HYDRAULIC TURBINE
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
In this paper, an energy equation of silt-laden water flow is educed based on the energy equation of continuum fluid flow. The dissipation functions of liquid phase and solid phase are presented respectively. Then the extremity law of energy dissipation rate is introduced for the research of the silt-laden water flow and a new mathematical model is developed. The corresponding procedure based on the finite difference method (FDM) is developed to calculate the two phase flow in hydraulic turbine. The method is applied to analyze the silt-laden water flow between stay vanes, and the numerical results are in good agreement with the experimental ones.
Numerical methods for two-phase flow with contact lines
Energy Technology Data Exchange (ETDEWEB)
Walker, Clauido
2012-07-01
This thesis focuses on numerical methods for two-phase flows, and especially flows with a moving contact line. Moving contact lines occur where the interface between two fluids is in contact with a solid wall. At the location where both fluids and the wall meet, the common continuum descriptions for fluids are not longer valid, since the dynamics around such a contact line are governed by interactions at the molecular level. Therefore the standard numerical continuum models have to be adjusted to handle moving contact lines. In the main part of the thesis a method to manipulate the position and the velocity of a contact line in a two-phase solver, is described. The Navier-Stokes equations are discretized using an explicit finite difference method on a staggered grid. The position of the interface is tracked with the level set method and the discontinuities at the interface are treated in a sharp manner with the ghost fluid method. The contact line is tracked explicitly and its dynamics can be described by an arbitrary function. The key part of the procedure is to enforce a coupling between the contact line and the Navier-Stokes equations as well as the level set method. Results for different contact line models are presented and it is demonstrated that they are in agreement with analytical solutions or results reported in the literature.The presented Navier-Stokes solver is applied as a part in a multiscale method to simulate capillary driven flows. A relation between the contact angle and the contact line velocity is computed by a phase field model resolving the micro scale dynamics in the region around the contact line. The relation of the microscale model is then used to prescribe the dynamics of the contact line in the macro scale solver. This approach allows to exploit the scale separation between the contact line dynamics and the bulk flow. Therefore coarser meshes can be applied for the macro scale flow solver compared to global phase field simulations
Numerical flow analyses of a two-phase hydraulic coupling
Energy Technology Data Exchange (ETDEWEB)
Hur, N.; Kwak, M.; Moshfeghi, M. [Sogang University, Seoul (Korea, Republic of); Chang, C.-S.; Kang, N.-W. [VS Engineering, Seoul (Korea, Republic of)
2017-05-15
We investigated flow characteristics in a hydraulic coupling at different charged water conditions and speed ratios. Hence, simulations were performed for three-dimensional two-phase flow by using the VOF method. The realizable k-ε turbulence model was adopted. To resolve the interaction of passing blades of the primary and secondary wheels, simulations were conducted in the unsteady framework using a sliding grid technique. The results show that the water-air distribution inside the wheel is strongly dependent upon both amount of charged water and speed ratio. Generally, air is accumulated in the center of the wheel, forming a toroidal shape wrapped by the circulating water. The results also show that at high speed ratios, the solid-body-like rotation causes dry areas on the periphery of the wheels and, hence, considerably decreases the circulating flow rate and the transmitted torque. Furthermore, the momentum transfer was investigated through the concept of a mass flux triangle based on the local velocity multiplied by the local mixture density instead of the velocity triangle commonly used in a single-phase turbomachine analysis. Also, the mass fluxes along the radius of the coupling in the partially charged and fully charged cases were found to be completely different. It is shown that the flow rate at the interfacial plane and also the transmitted torque are closely related and are strongly dependent upon both the amount of charged water and speed ratio. Finally, a conceptual categorization together with two comprehensive maps was provided for the torque transmission and also circulating flow rates. These two maps in turn exhibit valuable engineering information and can serve as bases for an optimal design of a hydraulic coupling.
Two Phase Flow Mapping and Transition Under Microgravity Conditions
Parang, Masood; Chao, David F.
1998-01-01
In this paper, recent microgravity two-phase flow data for air-water, air-water-glycerin, and air- water-Zonyl FSP mixtures are analyzed for transition from bubbly to slug and from slug to annular flow. It is found that Weber number-based maps are inadequate to predict flow-pattern transition, especially over a wide range of liquid flow rates. It is further shown that slug to annular flow transition is dependent on liquid phase Reynolds number at high liquid flow rate. This effect may be attributed to growing importance of liquid phase inertia in the dynamics of the phase flow and distribution. As a result a new form of scaling is introduced to present data using liquid Weber number based on vapor and liquid superficial velocities and Reynolds number based on liquid superficial velocity. This new combination of the dimensionless parameters seem to be more appropriate for the presentation of the microgravity data and provides a better flow pattern prediction and should be considered for evaluation with data obtained in the future. Similarly, the analysis of bubble to slug flow transition indicates a strong dependence on both liquid inertia and turbulence fluctuations which seem to play a significant role on this transition at high values of liquid velocity. A revised mapping of data using a new group of dimensionless parameters show a better and more consistent description of flow transition over a wide range of liquid flow rates. Further evaluation of the proposed flow transition mapping will have to be made after a wider range of microgravity data become available.
Multi-year Droughts and Pluvials over the Southwestern U.S. and Associated Circulations
Abatan, A. A.; Gutowski, W. J., Jr.
2015-12-01
The southwestern U.S. is highly vulnerable to climate variability leading to extremes, such as droughts and pluvials, because of its geographic location and climatologic characteristics. These can include multi-year and multi-decadal extremes in precipitation, as occurred in the 1950s drought. Multi-year droughts and pluvials can have severe consequences on water resources management, which makes them events of interest to a major water utility in the region, Denver Water. Denver Water managers are especially interested in 36-month droughts for planning water management, both for maintaining supply and adequate operating revenue. Our analysis is part of an effort to understand the basis for past droughts and pluvials and how they might change in the future. Several indices, based on their sensitivity to drought development at different time scales, data availability and drought types, have been developed for detecting and monitoring drought and pluvial severity. Among them are the Palmer drought severity index, standardized precipitation index (SPI), and standardized precipitation evapotranspiration index (SPEI). This study uses 36-month SPEI and SPI to analyze drought and pluvial episodes over the southwestern U.S., with a focus on the region that supplies water for Denver Water. Aims of this study include: 1) characteristics of multi-year droughts and pluvials (e.g., onset, duration, cessation, intensity, and frequency), 2) the contrasts between drought and pluvial characteristics, and 3) atmospheric large-scale features associated with the initiation and maintenance of extended drought and pluvial periods. We find that droughts and pluvials are not simply mirror images of each other in their characteristics, so that one is not simply the opposite phase of the other. This result is particularly true of the large-scale circulation patterns associated with droughts and pluvials. We diagnose how the circulation behavior sustains the very wet and very dry episodes
Review:Liquid film dryout model for predicting critical heat flux in annular two-phase flow
Institute of Scientific and Technical Information of China (English)
Bo JIAO; Li-min QIU; Jun-liang LU; Zhi-hua GAN
2009-01-01
Gas-liquid two-phase flow and heat transfer can be encountered in numerous fields, such as chemical engineering, refrigeration, nuclear power reactor, metallurgical industry, spaceflight. Its critical heat flux (CHF) is one of the most important factors for the system security of engineering applications. Since annular flow is the most common flow pattern in gas-liquid two-phase flow, predicting CHF of annular two-phase flow is more significant. Many studies have shown that the liquid film dryout model is successful for that prediction, and determining the following parameters will exert predominant effects on the accuracy of this model: onset of annular flow, inception criterion for droplets entrainment, entrainment fraction, droplets deposi-tion and entrainment rates. The main theoretical results achieved on the above five parameters are reviewed; also, limitations in the existing studies and problems for further research are discussed.
Multi-Year Radar Observations of Planetary Waves at High Conjugate Latitudes (Invited)
Fritts, D. C.; Iimura, H.; Janches, D.; Mitchell, N. J.; Singer, W.
2013-12-01
Meteor radars at nearly conjugate latitudes from ~54o to 68o S and N are enabling multi-year studies of planetary wave (PW) structure and seasonal, interannual, and inter-hemispheric variability. The various PWs exhibit dramatically different seasonal and inter-hemispheric variability, strongly variable amplitude and phase structures with altitude, latitude, and time, and episodic maxima in E-P flux components. This talk will review these features defined with meteor radars at Rothera Station and Ferraz Base (62 and 68 S), on Tierra del Fuego (54 S), and at Juliusruh, Germany and Esrange, Sweden (55 and 68 N).
Multi-Year Analysis Examines Costs, Benefits, and Impacts of Renewable Portfolio Standards
Energy Technology Data Exchange (ETDEWEB)
2016-01-01
As states consider revising renewable portfolio standard (RPS) programs or developing new ones, careful assessments of the costs, benefits, and other impacts of existing policies will be critical. RPS programs currently exist in 29 states and Washington, D.C. Many of these policies, which were enacted largely during the late 1990s and 2000s, will reach their terminal targets by the end of this decade. The National Renewable Energy Laboratory (NREL) and Lawrence Berkeley National Laboratory (LBNL) are engaged in a multi-year project to examine the costs, benefits, and other impacts of state RPS polices both retrospectively and prospectively. This fact sheet overviews this work.
Mechanical Properties of Multi-Year Sea Ice. Phase 1: Ice Structure Analysis,
1987-03-01
form at the bottom of the ridge by congela- pendicular to the other as shown in Figure 1. In tion growth. Meltwater ponds formed and refro- the event...observed between crossed polar- Greenland Sea (Tucker et al. 1985). The Fram izers, and the crystals appeared to be randomly Strait is the major outflow...Narssarssuaq, Greenland , 6-13 M. Mellor, H.W. Boeworth, G. Dred aad N. September, pp. 177-188. Perron (1985) Mechanical properties of multi-year Wang
Two-phase analysis in consensus genetic mapping.
Ronin, Y; Mester, D; Minkov, D; Belotserkovski, R; Jackson, B N; Schnable, P S; Aluru, S; Korol, A
2012-05-01
Numerous mapping projects conducted on different species have generated an abundance of mapping data. Consequently, many multilocus maps have been constructed using diverse mapping populations and marker sets for the same organism. The quality of maps varies broadly among populations, marker sets, and software used, necessitating efforts to integrate the mapping information and generate consensus maps. The problem of consensus genetic mapping (MCGM) is by far more challenging compared with genetic mapping based on a single dataset, which by itself is also cumbersome. The additional complications introduced by consensus analysis include inter-population differences in recombination rate and exchange distribution along chromosomes; variations in dominance of the employed markers; and use of different subsets of markers in different labs. Hence, it is necessary to handle arbitrary patterns of shared sets of markers and different level of mapping data quality. In this article, we introduce a two-phase approach for solving MCGM. In phase 1, for each dataset, multilocus ordering is performed combined with iterative jackknife resampling to evaluate the stability of marker orders. In this phase, the ordering problem is reduced to the well-known traveling salesperson problem (TSP). Namely, for each dataset, we look for order that gives minimum sum of recombination distances between adjacent markers. In phase 2, the optimal consensus order of shared markers is selected from the set of allowed orders and gives the minimal sum of total lengths of nonconflicting maps of the chromosome. This criterion may be used in different modifications to take into account the variation in quality of the original data (population size, marker quality, etc.). In the foregoing formulation, consensus mapping is considered as a specific version of TSP that can be referred to as "synchronized TSP." The conflicts detected after phase 1 are resolved using either a heuristic algorithm over the
Dynamics of two-phase interfaces and surface tensions: A density-functional theory perspective
Yatsyshin, Petr; Sibley, David N.; Duran-Olivencia, Miguel A.; Kalliadasis, Serafim
2016-11-01
Classical density functional theory (DFT) is a statistical mechanical framework for the description of fluids at the nanoscale, where the inhomogeneity of the fluid structure needs to be carefully accounted for. By expressing the grand free-energy of the fluid as a functional of the one-body density, DFT offers a theoretically consistent and computationally accessible way to obtain two-phase interfaces and respective interfacial tensions in a ternary solid-liquid-gas system. The dynamic version of DFT (DDFT) can be rigorously derived from the Smoluchowsky picture of the dynamics of colloidal particles in a solvent. It is generally agreed that DDFT can capture the diffusion-driven evolution of many soft-matter systems. In this context, we use DDFT to investigate the dynamic behaviour of two-phase interfaces in both equilibrium and dynamic wetting and discuss the possibility of defining a time-dependent surface tension, which still remains in debate. We acknowledge financial support from the European Research Council via Advanced Grant No. 247031 and from the Engineering and Physical Sciences Research Council of the UK via Grants No. EP/L027186 and EP/L020564.
48 CFR 36.301 - Use of two-phase design-build selection procedures.
2010-10-01
... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Use of two-phase design... ACQUISITION REGULATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Two-Phase Design-Build Selection Procedures 36.301 Use of two-phase design-build selection procedures....
24 CFR 115.201 - The two phases of substantial equivalency certification.
2010-04-01
... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false The two phases of substantial... ENFORCEMENT AGENCIES Certification of Substantially Equivalent Agencies § 115.201 The two phases of.... The Department has developed a two-phase process of substantial equivalency certification....
Directory of Open Access Journals (Sweden)
F. Golbabaei
2015-04-01
Conclusion: Overall, the results of the present research revealed that the application of two phase stirred tank bioreactors (TPPBs containing pure strains of Pseudomonas putida was successful for treatment of air streams with xylene.
Advanced reactors transition fiscal year 1995 multi-year program plan WBS 7.3
Energy Technology Data Exchange (ETDEWEB)
Loika, E.F.
1994-09-22
This document describes in detail the work to be accomplished in FY-1995 and the out years for the Advanced Reactors Transition (WBS 7.3). This document describes specific milestones and funding profiles. Based upon the Fiscal Year 1995 Multi-Year Program Plan, DOE will provide authorization to perform the work outlined in the FY 1995 MYPP. Following direction given by the US Department of Energy (DOE) on December 15, 1993, Advanced Reactors Transition (ART), previously known as Advanced Reactors, will provide the planning and perform the necessary activities for placing the Fast Flux Test Facility (FFTF) in a radiologically and industrially safe shutdown condition. The DOE goal is to accomplish the shutdown in approximately five years. The Advanced Reactors Transition Multi-Year Program Plan, and the supporting documents; i.e., the FFTF Shutdown Program Plan and the FFTF Shutdown Project Resource Loaded Schedule (RLS), are defined for the life of the Program. During the transition period to achieve the Shutdown end-state, the facilities and systems will continue to be maintained in a safe and environmentally sound condition. Additionally, facilities that were associated with the Office of Nuclear Energy (NE) Programs, and are no longer required to support the Liquid Metal Reactor Program will be deactivated and transferred to an alternate sponsor or the Decontamination and Decommissioning (D and D) Program for final disposition, as appropriate.
On the Stable Numerical Approximation of Two-Phase Flow with Insoluble Surfactant
Barrett, John W; Nürnberg, Robert
2013-01-01
We present a parametric finite element approximation of two-phase flow with insoluble surfactant. This free boundary problem is given by the Navier--Stokes equations for the two-phase flow in the bulk, which are coupled to the transport equation for the insoluble surfactant on the interface that separates the two phases. We combine the evolving surface finite element method with an approach previously introduced by the authors for two-phase Navier--Stokes flow, which maintains good mesh properties. The derived finite element approximation of two-phase flow with insoluble surfactant can be shown to be stable. Several numerical simulations demonstrate the practicality of our numerical method.
Role of Nucleation and Growth in Two-Phase Microstructure Formation
Energy Technology Data Exchange (ETDEWEB)
Shin, Jong Ho [Iowa State Univ., Ames, IA (United States)
2007-01-01
During the directional solidification of peritectic alloys, a rich variety of two-phase microstructures develop, and the selection process of a specific microstructure is complicated due to the following two considerations. (1) In contrast to many single phase and eutectic microstructures that grow under steady state conditions, two-phase microstructures in a peritectic system often evolve under non-steady-state conditions that can lead to oscillatory microstructures, and (2) the microstructure is often governed by both the nucleation and the competitive growth of the two phases in which repeated nucleation can occur due to the change in the local conditions during growth. In this research, experimental studies in the Sn-Cd system were designed to isolate the effects of nucleation and competitive growth on the dynamics of complex microstructure formation. Experiments were carried out in capillary samples to obtain diffusive growth conditions so that the results can be analyzed quantitatively. At high thermal gradient and low velocity, oscillatory microstructures were observed in which repeated nucleation of the two phases was observed at the wall-solid-liquid junction. Quantitative measurements of nucleation undercooling were obtained for both the primary and the peritectic phase nucleation, and three different ampoule materials were used to examine the effect of different contact angles at the wall on nucleation undercooling. Nucleation undercooling for each phase was found to be very small, and the experimental undercooling values were orders of magnitude smaller than that predicted by the classical theory of nucleation. A new nucleation mechanism is proposed in which the clusters of atoms at the wall ahead of the interface can become a critical nucleus when the cluster encounters the triple junction. Once the nucleation of a new phase occurs, the microstructure is found to be controlled by the relative growth of the two phases that give rise to different
Institute of Scientific and Technical Information of China (English)
夏广庆; 张斌; 孙得川; 陈茂林
2012-01-01
微型固体姿控发动机在航天领域具有广泛的应用前景.以基于MEMS技术的微喷管为研究对象,首先通过计算微喷管中的克努森数,得到了微喷管中的气相流动状态；然后,采用CFD-DSMC方法,模拟了微喷管中的气粒两相流动,并研究了颗粒相质量分数和粒径对气相流动的影响.结果表明,在所研究的来流条件下,微喷管中的连续介质假设是成立的；气相与颗粒相间的动量和能量交换,导致气相马赫数降低、温度升高,同时也导致颗粒相速度增加、温度降低；颗粒相质量分数和粒径均能显著影响气相的马赫数和温度.%Attitude control micro solid rocket motor has wide application potential in the aerospace field. The gas-particle two-phase flow in the micro nozzle based on the MEMS technology was investigated. Firstly, through calculating the Knudsen number of the micro nozzle, the gas phase flow state in the micro nozzle was obtained. Then the gas-particle two-phase flow in the micro nozzle was simulated by using the method of CFD-DSMC. The influence of particle mass fraction and particle diameter on the gas phase flow was studied. The result shows that the continuum assumption in the micro nozzle is established under the conditions of the defined flow in the study. The exchange of momentum and energy between the gas phase and the particle can not noly reduce the gas phase Mach number and raise the temperature, but also increase the particle phase velocity and decrease the temperature. The particle phase mass fraction and particle diameter can significantly influence the Mach number and temperature of gas phase.
Two Phase Compressible Flow Fields in One Dimensional and Eulerian Grid Framework
Lee, Sungsu; Park, Chan Wook
2008-11-01
Numerical investigation for two phase compressible flow fields of air-water in one dimensional tube are performed in the fixed Eulerian grid framework. Using an equation of states of Tait's type for a multiphase cell, the two phase compressible flow is modeled as equivalent single phase which is discretized using the Roe`s approximate Riemann solver, while the phase interface is captured via volume fractions of each phase. The most common problem found in the computational approaches in compressible multiphase flow is occurrence of the pressure oscillation at the phase interface. In order to suppress that phenomenon, tried are two approaches; a passive advection of volume fraction and a direct pressure relaxation with the compressible form of volume fraction equation. The results show that the direct pressure equalizing method suppresses pressure oscillation successfully and generates sharp discontinuities, transmitting and reflecting acoustic waves naturally at the phase interface. This work was supported by a research fund granted from Agency for Defense Development, South Korea
Survival estimation in two-phase cohort studies with application to biomarkers evaluation.
Rebora, Paola; Valsecchi, Maria Grazia
2016-12-01
Two-phase studies are attractive for their economy and efficiency in research settings where large cohorts are available for investigating the prognostic and predictive role of novel genetic and biological factors. In this type of study, information on novel factors is collected only in a convenient subcohort (phase II) drawn from the cohort (phase I) according to a given (optimal) sampling strategy. Estimation of survival in the subcohort needs to account for the design. The Kaplan-Meier method, based on counts of events and of subjects at risk in time, must be applied accounting, with suitable weights, for the sampling probabilities of the subjects in phase II, in order to recover the representativeness of the subcohort for the entire cohort. The authors derived a proper variance estimator of survival by linearization. The proposed method is applied in the context of a two-phase study on childhood acute lymphoblastic leukemia, which was planned in order to evaluate the role of genetic polymorphisms on treatment failure due to relapse. The method has shown satisfactory performance through simulations under different scenarios, including the case-control setting, and proved to be useful for describing results in the clinical example.
Analysis of two phase mass transfer by logarithmic driving force based on chemical thermodynamics
Energy Technology Data Exchange (ETDEWEB)
Nabeshima, Masahiro (Sumitomo Metal Mining Co. Ltd., Tokyo (Japan))
1994-04-01
In the Purex solvent extraction process in the reprocessing of spent fuel, the concentration of separated composition such as U changes continuously from very high condition to trace level. Also in most cases, water phase and organic phase continuously come in contact by counter flow operation. In this research, by the method of circulating organic phase between single liquid drop column and mixing tank, the extraction behavior of Nd and nitric acid in H[sub 2]O-NaNO[sub 3]/HNO[sub 3]-Nd(NO[sub 3])[sub 3]-100% TBP system was traced continuously, and the results of measurement and analysis are reported. The experimental equipment and the experimental condition are shown. As the driving force for two-phase mass transfer, that having chemical thermodynamic basis was introduced. It is considered that this driving force is effective for the kinetic analysis of mass transfer phenomena. Hereafter, it is necessary to confirm the more strict treatment using activity and the applicability to two-phase mass transfer phenomena. (K.I.).
A New Void Fraction Measurement Method for Gas-Liquid Two-Phase Flow in Small Channels.
Li, Huajun; Ji, Haifeng; Huang, Zhiyao; Wang, Baoliang; Li, Haiqing; Wu, Guohua
2016-01-27
Based on a laser diode, a 12 × 6 photodiode array sensor, and machine learning techniques, a new void fraction measurement method for gas-liquid two-phase flow in small channels is proposed. To overcome the influence of flow pattern on the void fraction measurement, the flow pattern of the two-phase flow is firstly identified by Fisher Discriminant Analysis (FDA). Then, according to the identification result, a relevant void fraction measurement model which is developed by Support Vector Machine (SVM) is selected to implement the void fraction measurement. A void fraction measurement system for the two-phase flow is developed and experiments are carried out in four different small channels. Four typical flow patterns (including bubble flow, slug flow, stratified flow and annular flow) are investigated. The experimental results show that the development of the measurement system is successful. The proposed void fraction measurement method is effective and the void fraction measurement accuracy is satisfactory. Compared with the conventional laser measurement systems using standard laser sources, the developed measurement system has the advantages of low cost and simple structure. Compared with the conventional void fraction measurement methods, the proposed method overcomes the influence of flow pattern on the void fraction measurement. This work also provides a good example of using low-cost laser diode as a competent replacement of the expensive standard laser source and hence implementing the parameter measurement of gas-liquid two-phase flow. The research results can be a useful reference for other researchers' works.
Institute of Scientific and Technical Information of China (English)
于靖民
2016-01-01
针对传统油井多相流地面分离计量方法的缺点，研究出了经旋流气相分离后油水两相流参数连续测量方法。基于低流量条件下油、水两相分离特点，在一个容积已知的环形空间内，利用仪器上位于油、水区域的两个阀门的不断切换，自动测量油相和水相排出该空间所用的时间来计算油井油水两相流条件下的流量和含水率。%Aimed at the shortcomings of traditional oil-well multiphase flow separation and metering method above the ground,a continuous metering method of oil-well two-phase flow after cyclonic gas-separation is studied in this paper.The flow rate and water content in oil wells can be calculated by this method.
Two phase flow combustion modelling of a ducted rocket
Stowe, R.A.; Dubois, C.; Harris, P.G.; Mayer, A.E.H.J.; Champlain, A. de; Ringuette, S.
2001-01-01
Under a co-operative program, the Defence Research Establishment Valcartier and Université Laval in Canada and the TNO Prins Maurits Laboratory in the Netherlands have studied the use of a ducted rocket for missile propulsion. Hot-flow direct-connect combustion experiments using both simulated and s
Animal-cell culture in aqueous two-phase systems.
Zijlstra, G.M.
1998-01-01
In current industrial biotechnology, animal-cell culture is an important source of therapeutic protein products. The conventional animal-cell production processes, however, include many unit operations as part of the fermentation and downstream processing strategy. The research described in this the
Modeling two-phase flow with offshore applications
Wemmenhove, Rik; Loots, Erwin; Luppes, Roel; Veldman, Arthur E.P.
2005-01-01
With the trend towards offshore LNG production and offloading, sloshing of LNG in partially filled tanks has become an important research subject for the offshore industry. LNG sloshing may induce impact pressures on the containment system and may affect the motions of the LNG carrier. So far, LNG
Animal-cell culture in aqueous two-phase systems
Zijlstra, G.M.
1998-01-01
In current industrial biotechnology, animal-cell culture is an important source of therapeutic protein products. The conventional animal-cell production processes, however, include many unit operations as part of the fermentation and downstream processing strategy. The research described in
Planning integration FY 1995 Multi-Year Program Plan (MYPP)/Fiscal Year Work Plan (FYWP)
Energy Technology Data Exchange (ETDEWEB)
1994-09-01
This Multi-Year Program Plan (MYPP) for the Planning Integration Program, Work Breakdown structure (WBS) Element 1.8.2, is the primary management tool to document the technical, schedule, and cost baseline for work directed by the US Department of Energy (DOE), Richland Operations Office (RL). As an approved document, it establishes a binding agreement between RL and the performing contractors for the work to be performed. It was prepared by the Westinghouse Hanford Company (WHC) and the Pacific Northwest Laboratory (PNL). This MYPP provides a picture from fiscal year 1995 through FY 2001 for the Planning Integration Program. The MYPP provides a window of detailed information for the first three years. It also provides `execution year` work plans. The MYPP provides summary information for the next four years, documenting the same period as the Activity Data Sheets.
Two-Phase Flow in Circular Secondary Sedimentation Tanks
Matko, T. I. R.
1997-01-01
The main objective of this work was to optimise a numerical model to predict the flow in circular secondary sedimentation tanks. The numerical models in the literature were reviewed and the new opportunities for research were identified. Single-phase flow characteristics of two circular sedimentation tanks were investigated using the CFD program, CFX-F3D. The flow in the circular clarifiers were modelled in two dimensions (axial and radial) and using the standard k-E turbule...
Simulation Experiments of Reacting Two-Phase Flow
1987-04-06
Simulation Experiments 16 2.8 Lord’s Work Done in the 1960’s 17 2.9 Investigations Performed by Wilkins and Carros in the 1960’s 19 2.10 Statement of Work 20...the fundamental research work described here. A gas gun facility, based on the studies of Lord (21 and Wilkins and Carros [3] was built at EMI-AFB...show that the calculations of Lord [2] are in error (see Section 4.). ’i 3-X: 2.9 Investigations Performed by Wilkins and Carros inthe 196o’s- Wilkins
Thermal Lattice Boltzmann Simulations for Vapor-Liquid Two-Phase Flows in Two Dimensions
Wei, Yikun; Qian, Yuehong
2011-11-01
A lattice Boltzmann model with double distribution functions is developed to simulate thermal vapor-liquid two-phase flows. In this model, the so-called mesoscopic inter-particle pseudo-potential for the single component multi-phase lattice Boltzmann model is used to simulate the fluid dynamics and the internal energy field is simulated by using a energy distribution function. Theoretical results for large-scale dynamics including the internal energy equation can be derived and numerical results for the coexistence curve of vapor-liquid systems are in good agreement with the theoretical predictions. It is shown from numerical simulations that the model has the ability to mimic phase transitions, bubbly flows and slugging flows. This research is support in part by the grant of Education Ministry of China IRT0844 and the grant of Shanghai CST 11XD1402300.
Modified two-phase anaerobic baffled process for low-concentration wastewater treatment
Institute of Scientific and Technical Information of China (English)
LIN Ying-zi; HAN Xiang-kui; YIN Jun; SHAO Pi-hong; AI Sheng-shu
2009-01-01
In this study low-concentration wastewater was investigated in the integral two-phase anaerobic baf-fled reactor by determining the removal of COD at various HRT,reflex ratios,and temperatures.Results indi-cate that the removal efficiency of COD is more than 90%at 25℃and 10-h HRT with no wastewater recycled,and the removal efficiency is up to 88%at 8-h HRT and reflex ratio of 150%.The removal efficiency is de-creased with the decreasing temperature and HRT.The removal efficiency of COD is approximaleIy 60%at10℃,which proves that the temperature does not affect it apparently.This research has significance for reduc-ing the cost ot wastewater and sludge treatment in cold area.
Heat transfer studies in a spiral plate heat exchanger for water: palm oil two phase system
Directory of Open Access Journals (Sweden)
S. Ramachandran
2008-09-01
Full Text Available Experimental studies were conducted in a spiral plate heat exchanger with hot water as the service fluid and the two-phase system of water palm oil in different mass fractions and flow rates as the cold process fluid. The two phase heat transfer coefficients were correlated with Reynolds numbers (Re in the form h = a Re m, adopting an approach available in literature for two phase fluid flow. The heat transfer coefficients were also related to the mass fraction of palm oil for identical Reynolds numbers. The two-phase multiplier (ratio of the heat transfer coefficient of the two phase fluid and that of the single phase fluid was correlated with the Lockhart Martinelli parameter in a polynomial form. This enables prediction of the two-phase coefficients using single-phase data. The predicted coefficients showed a spread of ± 10 % in the laminar range.
Zeng, Chao-Xi; Xin, Rui-Pu; Qi, Sui-Jian; Yang, Bo; Wang, Yong-Hua
2016-02-01
Aqueous two-phase systems, based on the use of natural quaternary ammonium compounds, were developed to establish a benign biotechnological route for efficient protein separation. In this study, aqueous two-phase systems of two natural resources betaine and choline with polyethyleneglycol (PEG400/600) or inorganic salts (K2 HPO4 /K3 PO4 ) were formed. It was shown that in the K2 HPO4 -containing aqueous two-phase system, hydrophobic interactions were an important driving force of protein partitioning, while protein size played a vital role in aqueous two-phase systems that contained polyethylene glycol. An extraction efficiency of more than 90% for bovine serum albumin in the betaine/K2 HPO4 aqueous two-phase system can be obtained, and this betaine-based aqueous two-phase system provided a gentle and stable environment for the protein. In addition, after investigation of the cluster phenomenon in the betaine/K2 HPO4 aqueous two-phase systems, it was suggested that this phenomenon also played a significant role for protein extraction in this system. The development of aqueous two-phase systems based on natural quaternary ammonium compounds not only provided an effective and greener method of aqueous two-phase system to meet the requirements of green chemistry but also may help to solve the mystery of the compartmentalization of biomolecules in cells.
Analysis of Developing Gas/liquid Two-Phase Flows
Energy Technology Data Exchange (ETDEWEB)
Elena A. Tselishcheva; Michael Z. Podowski; Steven P. Antal; Donna Post Guillen; Matthias Beyer; Dirk Lucas
2010-06-01
The goal of this work is to develop a mechanistically based CFD model that can be used to simulate process equipment operating in the churn-turbulent regime. The simulations were performed using a state-of-the-art computational multiphase fluid dynamics code, NPHASE–CMFD [Antal et al,2000]. A complete four-field model, including the continuous liquid field and three dispersed gas fields representing bubbles of different sizes, was first carefully tested for numerical convergence and accuracy, and then used to reproduce the experimental results from the TOPFLOW test facility at Forschungszentrum Dresden-Rossendorf e.V. Institute of Safety Research [Prasser et al,2007]. Good progress has been made in simulating the churn-turbulent flows and comparison the NPHASE-CMFD simulations with TOPFLOW experimental data. The main objective of the paper is to demonstrate capability to predict the evolution of adiabatic churn-turbulent gas/liquid flows. The proposed modelling concept uses transport equations for the continuous liquid field and for dispersed bubble fields [Tselishcheva et al, 2009]. Along with closure laws based on interaction between bubbles and continuous liquid, the effect of height on air density has been included in the model. The figure below presents the developing flow results of the study, namely total void fraction at different axial locations along the TOPFLOW facility test section. The complete model description, as well as results of simulations and validation will be presented in the full paper.
Two-phase flow interfacial structures in a rod bundle geometry
Paranjape, Sidharth S.
Interfacial structure of air-water two-phase flow in a scaled nuclear reactor rod bundle geometry was studied in this research. Global and local flow regimes were obtained for the rod bundle geometry. Local two-phase flow parameters were measured at various axial locations in order to understand the transport of interfacial structures. A one-dimensional two-group interfacial area transport model was evaluated using the local parameter database. Air-water two-phase flow experiments were performed in an 8 X 8 rod bundle test section to obtain flow regime maps at various axial locations. Area averaged void fraction was measured using parallel plate type impedance void meters. The cumulative probability distribution functions of the signals from the impedance void meters were used along with a self organizing neural network to identify flow regimes. Local flow regime maps revealed the cross-sectional distribution of flow regimes in the bundle. Local parameters that characterize interfacial structure, that is, void fraction alpha, interfacial area concentration, ai, bubble Sauter mean diameter, DSm and bubble velocity, vg were measured using four sensor conductivity probe technique. The local data revealed the distribution of the interfacial structure in the radial direction, as well as its development in the axial direction. In addition to this, the effect of spacer grid on the flow structure at different gas and liquid velocities was revealed by local parameter measurements across the spacer grids. A two-group interfacial area transport equation (IATE) specific to rod bundle geometry was derived. The derivation of two-group IATE required certain assumption on the bubble shapes in the subchannels and the bubbles spanning more than a subchannel. It was found that the geometrical relationship between the volume and the area of a cap bubble distorted by rods was similar to the one derived for a confined channel under a specific geometrical transformation. The one
One-phase or two-phase orthodontic treatment?
Mir, Carlos Flores
2016-12-01
Data sourcesMedline, Embase, Cochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), LILACS, BBO, ClinicalTrials.gov, the National Research Register and Pro-Quest Dissertation Abstracts and Thesis database.Study selectionRandomised controlled trials (RCTs) and controlled trials (CCTs) in children under 11 years at the beginning of treatment for interventions including; interceptive extractions, space maintenance, crossbite correction and habit dissuasion were considered.Data extraction and synthesisTwo reviewers independently extracted data and assessed study quality using the Cochrane Risk of Bias tool. Meta-analysis was possible for 11 comparisons.ResultsTwenty-two studies (18 RCTs, three CCTs) were included with 20 being considered to be at low or unclear risk of bias. For Class II correction in the short-term, meta-analyses demonstrated a statistically significant reduction in ANB (-1.4 degrees, 95 CI: -2.17, -0.64) and overjet (-5.81mm, 95 CI: -6.37, -5.25) with both functional appliances and headgear versus control. For Class II correction in the long-term, however, statistical significance was not found for the same outcomes. Treatment duration was prolonged with both functional appliances (6.85 months, 95 CI: 3.24, 10.45) and headgear (12.47 months, 95 CI: 8.67, 16.26) compared to adolescent treatments. Meta-analyses were not possible for comparisons of other interceptive treatments due to heterogeneity and methodological limitations. The overall quality of the evidence based on the GRADE assessment suggested that the level of evidence was low to moderate.ConclusionsThe results suggest a lack of evidence to prove that early treatment carries additional benefit over and above that achieved with treatment commencing later; however, this does not imply that early treatment is ineffective. The additional cost and burden to the patient, parent and clinician may, therefore, generally negate early treatment
Domain decomposition parallel computing for transient two-phase flow of nuclear reactors
Energy Technology Data Exchange (ETDEWEB)
Lee, Jae Ryong; Yoon, Han Young [KAERI, Daejeon (Korea, Republic of); Choi, Hyoung Gwon [Seoul National University, Seoul (Korea, Republic of)
2016-05-15
KAERI (Korea Atomic Energy Research Institute) has been developing a multi-dimensional two-phase flow code named CUPID for multi-physics and multi-scale thermal hydraulics analysis of Light water reactors (LWRs). The CUPID code has been validated against a set of conceptual problems and experimental data. In this work, the CUPID code has been parallelized based on the domain decomposition method with Message passing interface (MPI) library. For domain decomposition, the CUPID code provides both manual and automatic methods with METIS library. For the effective memory management, the Compressed sparse row (CSR) format is adopted, which is one of the methods to represent the sparse asymmetric matrix. CSR format saves only non-zero value and its position (row and column). By performing the verification for the fundamental problem set, the parallelization of the CUPID has been successfully confirmed. Since the scalability of a parallel simulation is generally known to be better for fine mesh system, three different scales of mesh system are considered: 40000 meshes for coarse mesh system, 320000 meshes for mid-size mesh system, and 2560000 meshes for fine mesh system. In the given geometry, both single- and two-phase calculations were conducted. In addition, two types of preconditioners for a matrix solver were compared: Diagonal and incomplete LU preconditioner. In terms of enhancement of the parallel performance, the OpenMP and MPI hybrid parallel computing for a pressure solver was examined. It is revealed that the scalability of hybrid calculation was enhanced for the multi-core parallel computation.
Reaction Mechanisms and Particle Interaction in Burning Two-Phase Systems
Dreizin, Edward L.; Shoshin, Yuriy L.; Murdyy, Ruslan S.; Hoffmann, Vern K.
2001-01-01
The main objective of this research is to understand the mechanisms by which particle interactions affect ignition and combustion in the two-phase systems. Combustion of metal aerosols representing the two-phase systems is carried out in the microgravity environment enabling one to avoid the buoyant flows that mask the particle motion due to the particle-particle interaction effects. In addition, relatively large, e.g., 100 micron diameter particles can be used, that remain aerosolized (i.e., do not fall down as they would at normal gravity) so that their behavior ahead, behind, and within the propagating flame can be resolved optically. An experimental apparatus exploiting this approach has been designed for the 2.2-s drop tower microgravity experiments. A typical experiment includes fluidizing metal particles under microgravity in an acoustic field, turning off the acoustic exciter, and igniting the created aerosol at a constant pressure using a hot wire igniter. The flame propagation and details of the individual particle combustion and particle interactions are studied using high-speed movie and video cameras coupled with microscope lenses to resolve individual particles. Recorded flame images are digitized and various image processing techniques including flame position tracking, color separation, and pixel by pixel image comparisons are employed to understand the processes occurring in the burning aerosols. Condensed combustion products are collected after each experiment for the phase, composition, and morphology analyses. New experiments described in this paper address combustion of Ti and Al particle clouds in air and combustion of Mg particle clouds in CO2. In addition, microgravity combustion experiments have been conducted with the particles of the newly produced Al-Mg mechanical alloys aerosolized in air.
A green deep eutectic solvent-based aqueous two-phase system for protein extracting
Energy Technology Data Exchange (ETDEWEB)
Xu, Kaijia; Wang, Yuzhi, E-mail: wyzss@hnu.edu.cn; Huang, Yanhua; Li, Na; Wen, Qian
2015-03-15
Highlights: • A strategy for the protein purification with a deep eutectic solvent(DES)-based aqueous two-phase system. • Choline chloride-glycerin DES was selected as the extraction solvent. • Bovine serum albumin and trypsin were used as the analytes. • Aggregation phenomenon was detected in the mechanism research. - Abstract: As a new type of green solvent, deep eutectic solvent (DES) has been applied for the extraction of proteins with an aqueous two-phase system (ATPS) in this work. Four kinds of choline chloride (ChCl)-based DESs were synthesized to extract bovine serum albumin (BSA), and ChCl-glycerol was selected as the suitable extraction solvent. Single factor experiments have been done to investigate the effects of the extraction process, including the amount of DES, the concentration of salt, the mass of protein, the shaking time, the temperature and PH value. Experimental results show 98.16% of the BSA could be extracted into the DES-rich phase in a single-step extraction under the optimized conditions. A high extraction efficiency of 94.36% was achieved, while the conditions were applied to the extraction of trypsin (Try). Precision, repeatability and stability experiments were studied and the relative standard deviations (RSD) of the extraction efficiency were 0.4246% (n = 3), 1.6057% (n = 3) and 1.6132% (n = 3), respectively. Conformation of BSA was not changed during the extraction process according to the investigation of UV–vis spectra, FT-IR spectra and CD spectra of BSA. The conductivity, dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to explore the mechanism of the extraction. It turned out that the formation of DES–protein aggregates play a significant role in the separation process. All the results suggest that ChCl-based DES-ATPS are supposed to have the potential to provide new possibilities in the separation of proteins.
A study of relative permeability parameters on rock cores using a two-phase flow test
Directory of Open Access Journals (Sweden)
Chung-Hui Chiao
2017-01-01
Full Text Available To ensure sequestration safety, confirming the injectivity of the reservoir rock formation is of critical importance, requiring studies of the rock permeability to uncover the fluid migration scenarios within the porous reservoir rock. Two-phase (super-critical CO2-brine flow behavior following the post CO2 injection is believed to be a dominating factor; its flooding behavior within the porous rock media needs to be further clarified prior to confirming the feasibility of domestic CO2 geo-sequestration. This study aims to determine the relative permeability of rock cores obtained from field outcropping. A test facility was established to determine the relative permeability during drainage and imbibition processes using a core-flooding test characterized by displacement method. The test facility was assembled locally and is regarded as a pioneering attempt. By relevant data interpretation, the parameters of relative permeability for predicting the movement of super-critical CO2 after injection can be modeled. More reliable parameters can be obtained using history matching processes wherein time-elapsed data calibration is used in conjunction with a computer code, TOUGH2. The test results were iteratively calibrated using numerical simulation by conducting a history matching process. The K-S curves derived from best-fit parameters are believed to be the most relevant relative permeability for the reservoir rock. Through this preliminary study, a better understanding of some of the problems and limitations associated with the determination of the rock relative permeability using two-phase flow test is achieved, but more advanced research is required.
Multiparametric Analysis of Oncology Drug Screening with Aqueous Two-Phase Tumor Spheroids.
Shahi Thakuri, Pradip; Ham, Stephanie L; Luker, Gary D; Tavana, Hossein
2016-11-07
Spheroids present a biologically relevant three-dimensional model of avascular tumors and a unique tool for discovery of anticancer drugs. Despite being used in research laboratories for several decades, spheroids are not routinely used in the mainstream drug discovery pipeline primarily due to the difficulty of mass-producing uniformly sized spheroids and intense labor involved in handling, drug treatment, and analyzing spheroids. We overcome this barrier using a polymeric aqueous two-phase microtechnology to robotically microprint spheroids of well-defined size in standard 384-microwell plates. We use different cancer cells and show that resulting spheroids grow over time and display characteristic features of solid tumors. We demonstrate the feasibility of robotic, high-throughput screening of 25 standard chemotherapeutics and molecular inhibitors against tumor spheroids of three different cancer cell lines. This screening uses over 7000 spheroids to elicit high quality dose-dependent drug responses from spheroids. To quantitatively compare performance of different drugs, we employ a multiparametric scoring system using half-maximum inhibitory concentration (IC50), maximum inhibition (Emax), and area under the dose-response curve (AUC) to take into account both potency and efficacy parameters. This approach allows us to identify several compounds that effectively inhibit growth of spheroids and compromise cellular viability, and distinguish them from moderately effective and ineffective drugs. Using protein expression analysis, we demonstrate that spheroids generated with the aqueous two-phase microtechnology reliably resolve molecular targets of drug compounds. Incorporating this low-cost and convenient-to-use tumor spheroid technology in preclinical drug discovery will make compound screening with realistic tumor models a routine laboratory technique prior to expensive and tedious animal tests to dramatically improve testing throughput and efficiency and
A Two-Phase Model of Resource Allocation in Visual Working Memory.
Ye, Chaoxiong; Hu, Zhonghua; Li, Hong; Ristaniemi, Tapani; Liu, Qiang; Liu, Taosheng
2017-03-02
Two broad theories of visual working memory (VWM) storage have emerged from current research, a discrete slot-based theory and a continuous resource theory. However, neither the discrete slot-based theory or continuous resource theory clearly stipulates how the mental commodity for VWM (discrete slot or continuous resource) is allocated. Allocation may be based on the number of items via stimulus-driven factors, or it may be based on task demands via voluntary control. Previous studies have obtained conflicting results regarding the automaticity versus controllability of such allocation. In the current study, we propose a two-phase allocation model, in which the mental commodity could be allocated only by stimulus-driven factors in the early consolidation phase. However, when there is sufficient time to complete the early phase, allocation can enter the late consolidation phase, where it can be flexibly and voluntarily controlled according to task demands. In an orientation recall task, we instructed participants to store either fewer items at high-precision or more items at low-precision. In 3 experiments, we systematically manipulated memory set size and exposure duration. We did not find an effect of task demands when the set size was high and exposure duration was short. However, when we either decreased the set size or increased the exposure duration, we found a trade-off between the number and precision of VWM representations. These results can be explained by a two-phase model, which can also account for previous conflicting findings in the literature. (PsycINFO Database Record
48 CFR 570.105-2 - Two-phase design-build selection procedures.
2010-10-01
... 48 Federal Acquisition Regulations System 4 2010-10-01 2010-10-01 false Two-phase design-build... ADMINISTRATION SPECIAL CONTRACTING PROGRAMS ACQUIRING LEASEHOLD INTERESTS IN REAL PROPERTY General 570.105-2 Two..., you must use the two-phase design-build selection procedures in section 303M of the Federal Property...
NUMERICAL SIMULATION OF CHARGED GAS-LIQUID TWO PHASE JET FLOW IN ELECTROSTATIC SPRAYING
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Multi-fluid k-ε-kp two phase turbulence model is used to simulate charged gas-liquid two phase coaxial jet, which is the transorting flow field in electrostatic spraying. Compared with the results of experiment, charged gas-liquid twophase turbulence can be well predicted by this model.
Solutions of Green s function for Lamb s problem of a two-phase saturated medium
Institute of Scientific and Technical Information of China (English)
无
2011-01-01
The solutions of Green's function are significant for simplification of problem on a two-phase saturated medium.Using transformation of axisymmetric cylindrical coordinate and Sommerfeld's integral,superposition of the influence field on a free surface,authors obtained the solutions of a two-phase saturated medium subjected to a concentrated force on the semi-space.
Symmetrical components and power analysis for a two-phase microgrid system
DEFF Research Database (Denmark)
Alibeik, M.; Santos Jr., E. C. dos; Blaabjerg, Frede
2014-01-01
This paper presents a mathematical model for the symmetrical components and power analysis of a new microgrid system consisting of three wires and two voltages in quadrature, which is designated as a two-phase microgrid. The two-phase microgrid presents the following advantages: 1) constant power...
Majhi, Bijoy Kumar; Jash, Tushar
2016-12-01
Biogas production from vegetable market waste (VMW) fraction of municipal solid waste (MSW) by two-phase anaerobic digestion system should be preferred over the single-stage reactors. This is because VMW undergoes rapid acidification leading to accumulation of volatile fatty acids and consequent low pH resulting in frequent failure of digesters. The weakest part in the two-phase anaerobic reactors was the techniques applied for solid-liquid phase separation of digestate in the first reactor where solubilization, hydrolysis and acidogenesis of solid organic waste occur. In this study, a two-phase reactor which consisted of a solid-phase reactor and a methane reactor was designed, built and operated with VMW fraction of Indian MSW. A robust type filter, which is unique in its implementation method, was developed and incorporated in the solid-phase reactor to separate the process liquid produced in the first reactor. Experiments were carried out to assess the long term performance of the two-phase reactor with respect to biogas production, volatile solids reduction, pH and number of occurrence of clogging in the filtering system or choking in the process liquid transfer line. The system performed well and was operated successfully without the occurrence of clogging or any other disruptions throughout. Biogas production of 0.86-0.889m(3)kg(-1)VS, at OLR of 1.11-1.585kgm(-3)d(-1), were obtained from vegetable market waste, which were higher than the results reported for similar substrates digested in two-phase reactors. The VS reduction was 82-86%. The two-phase anaerobic digestion system was demonstrated to be stable and suitable for the treatment of VMW fraction of MSW for energy generation.
A Multi-Year Budget Generation Program for Use in Navy Recruiting: A Users’ Manual,
1981-10-01
aor4- Ct 4 CL4. &40 *- o a. L&oCl. .&9 V 1 A .9 cc cc(IMc _o I -~ P . N .. II , I w - 1~ 10. 1 ~~I I It g c’ i~CIO I U-4 tic ff1 A WVA1; I1 Cd-C x r...0 0 *1 me a rC4 - - IIt of a 0 -OF- 0 4 a loo 0 ~ W% ,a a.I u~l CiftV I i C’ j *ag I I;:c ,’" Iw P 4t .0 -. 6 -, UiO -% a4i*u C~ L* I J TiC ’ Le. Le...or RCPORT A PERIOD Cove’rEO A MULTI-YEAR BUDGET GENERATION PROGRAM FOR USE IN NAVY RECRUITING 6. PERFORMING ON G. RCPOPT 11U0.51&( 7. AUlA 4084() S
Multi-year Estimates of Methane Fluxes in Alaska from an Atmospheric Inverse Model
Miller, S. M.; Commane, R.; Chang, R. Y. W.; Miller, C. E.; Michalak, A. M.; Dinardo, S. J.; Dlugokencky, E. J.; Hartery, S.; Karion, A.; Lindaas, J.; Sweeney, C.; Wofsy, S. C.
2015-12-01
We estimate methane fluxes across Alaska over a multi-year period using observations from a three-year aircraft campaign, the Carbon Arctic Reservoirs Vulnerability Experiment (CARVE). Existing estimates of methane from Alaska and other Arctic regions disagree in both magnitude and distribution, and before the CARVE campaign, atmospheric observations in the region were sparse. We combine these observations with an atmospheric particle trajectory model and a geostatistical inversion to estimate surface fluxes at the model grid scale. We first use this framework to estimate the spatial distribution of methane fluxes across the state. We find the largest fluxes in the south-east and North Slope regions of Alaska. This distribution is consistent with several estimates of wetland extent but contrasts with the distribution in most existing flux models. These flux models concentrate methane in warmer or more southerly regions of Alaska compared to the estimate presented here. This result suggests a discrepancy in how existing bottom-up models translate wetland area into methane fluxes across the state. We next use the inversion framework to explore inter-annual variability in regional-scale methane fluxes for 2012-2014. We examine the extent to which this variability correlates with weather or other environmental conditions. These results indicate the possible sensitivity of wetland fluxes to near-term variability in climate.
FeLoBAL Outflow Variability Constraints from Multi-Year Observations
McGraw, Sean M; Hamann, Frederick W; Capellupo, Daniel M; Gallagher, Sarah C; Brandt, William N
2013-01-01
The physical properties and dynamical behavior of Broad Absorption Line (BAL) outflows are crucial themes in understanding the connections between galactic centers and their hosts. FeLoBALs (identified with the presence of low-ionization Fe II BALs) are a peculiar class of quasar outflows that constitute approximately 1% of the BAL population. With their large column densities and apparent outflow kinetic luminosities, FeLoBALs appear to be exceptionally powerful and are strong candidates for feedback in galaxy evolution. We conducted variability studies of 12 FeLoBAL quasars with emission redshifts between 0.69 and 1.93, spanning both weekly and multi-year timescales in the quasar's rest frame. We detected absorption-line variability from low-ionization species (Fe II, Mg II) in four of our objects, with which we established a representative upper limit for the distance of the absorber from the supermassive black hole (SMBH) to be approximately 20 parsecs. Our goals are to understand the mechanisms producing...
Housing Abandonment and Demolition: Exploring the Use of Micro-Level and Multi-Year Models
Directory of Open Access Journals (Sweden)
Li Yin
2015-07-01
Full Text Available Policies focusing on enforcing property code violations and the improvement of vacant properties are argued to be more efficacious than demolition policies to fight urban blight. This study applies parcel level data to a multi-year hybrid modeling structure. A fine-grained analysis is conducted on the dynamic patterns of abandonment and demolition for a unique period of four years before and after the City of Buffalo’s stepped-up demolition efforts. Results showed that proximity to vacant and abandoned properties, sustained over the years, had the greatest impact on the possibility of a property being abandoned. The second greatest positive impact on property abandonment was small lot front size. Results also showed that neighborhood vacancy density had the greatest negative impact on surrounding housing sales prices over the years. There was no significant impact of demolition on housing sales prices. These findings suggested that the City should aim to have more incentive programs that are tailored to control the number of vacant properties, rather than focusing primarily on demolition-oriented programs.
Multi-year high-frequency physical and environmental observations at the Guadiana Estuary
Garel, E.; Ferreira, Ó.
2015-11-01
High-frequency data collected continuously over a multi-year time frame are required for investigating the various agents that drive ecological and hydrodynamic processes in estuaries. Here, we present water quality and current in situ observations from a fixed monitoring station operating from 2008 to 2014 in the lower Guadiana Estuary, southern Portugal (37°11.30' N, 7°24.67' W). The data were recorded by a multi-parametric probe providing hourly records (temperature, salinity, chlorophyll, dissolved oxygen, turbidity, and pH) at a water depth of ~ 1 m, and by a bottom-mounted acoustic Doppler current profiler measuring the pressure, near-bottom temperature, and flow velocity through the water column every 15 min. The time series data, in particular the probe ones, present substantial gaps arising from equipment failure and maintenance, which are ineluctable with this type of observation in harsh environments. However, prolonged (months-long) periods of multi-parametric observations during contrasted external forcing conditions are available. The raw data are reported together with flags indicating the quality status of each record. River discharge data from two hydrographic stations located near the estuary head are also provided to support data analysis and interpretation. The data set is publicly available in machine-readable format at PANGAEA (doi:10.1594/PANGAEA.845750).
Analysis of transient gas-liquid two-phase natural circulation
Energy Technology Data Exchange (ETDEWEB)
Kataoka, Isao; Matsumoto, Tadayoshi; Morita, Yu; Kawashima, Atsushi [Department of Mechanophysics Engineering, Osaka University, Suita, Osaka (Japan); Nakayama, Akio
1999-07-01
Analyses were made on the transient behavior of two-phase natural circulation in annular passage. Drift flux model was used in the analyses and several correlations of drift velocity were used and compared. Transient variation of void fraction, inlet liquid flux and length of two-phase region were predicted based on simplified model. It was revealed that in transient two-phase natural circulation, the condition for pressure difference between inlet and outlet is quite important and difficult to be specified. A simplified model for inlet pressure condition was assumed and transient two-phase natural circulation was reasonably predicted. The correlation of drift velocity was shown to have important effect on the flow behavior particularly for the transient variation of two-phase length. (author)
A MODEL FOR PREDICTING PHASE INVERSION IN OIL-WATER TWO-PHASE PIPE FLOW
Institute of Scientific and Technical Information of China (English)
GONG Jing; LI Qing-ping; YAO Hai-yuan; YU Da
2006-01-01
Experiments of phase inversion characteristics for horizontal oil-water two-phase flow in a stainless steel pipe loop (25.7 mm inner diameter,52 m long) are conducted. A new viewpoint is brought forward about the process of phase inversion in oil-water two-phase pipe flow. Using the relations between the total free energies of the pre-inversion and post-inversion dispersions, a model for predicting phase inversion in oil-water two-phase pipe flow has been developed that considers the characteristics of pipe flow. This model is compared against other models with relevant data of phase inversion in oil-water two-phase pipe flow. Results indicate that this model is better than other models in terms of calculation precision and applicability. The model is useful for guiding the design for optimal performance and safety in the operation of oil-water two-phase pipe flow in oil fields.
A numerical study of steady-state two-phase flow in porous media
Energy Technology Data Exchange (ETDEWEB)
Knudsen, Henning Arendt
2002-07-01
Two-phase flow in porous media means the simultaneous flow of two phases, say two liquids, e.g., oil and water. This flow is restrained to be within a porous medium. For example sandstone and limestone are typical porous stones that can contain oil and gas in nature. In the extraction of oil from reservoirs, oil is usually displaced by water. So on a large scale we can consider it to be a displacement process. However, on pore scale the ''mix'' and flow processes are complicated. Idealistically, one might consider the search for truth a sufficient motivation for work in this field. Nevertheless, from an economic and technological point of view, enhanced oil recovery is the main motivation for the study of two-phase flow in porous media. Luckily, there are additional systems in real world that falls into this category. One such system is the flow of water and pollutants in aquifers. General knowledge in the field might be beneficial for preserving ground water reserves in the future. In the laboratory one often encounters artificially made porous media. For example glass beads between two glass plates. Therein, one of the phases flowing may be a mixture of glycerol and water. The other phase can be air which then is the non-wetting phase; air does not wet glass. It can also be silicone oil, and in that case the water/glycerol is normally the nonwetting phase. There are other possibilities. In general, laboratory studies are performed on systems on pore scale. The flow properties on the various length scales found in flow systems in nature depend on these properties on pore scale. The so-called upscaling problem concerns how to relate pore scale properties with properties on larger scales. The scope of this thesis is the study of properties on pore scale. The upscaling problem, which is a large research field in itself, is thus outside the scope of this thesis. The results of Paper 3 is an exception since they may infer also to larger scales than
New considerations on the mass and energy balances in one-dimensional two-phase flow at steady state
Energy Technology Data Exchange (ETDEWEB)
Collado, F.J. [Zaragoza Univ. (Spain). Dept. de Ingenieria Mecanica; Munoz, M. [Zaragoza Univ. (Spain). Dept. de Ingenieria Mecanica
1997-08-01
A new equation to be added to the classical mass balance expressions for two-phase flow is presented. It is based on the definition of new differential control volumes of variable length which are proportional to the gas velocity in a compressible flow. The new equation is equivalent to the gas-solids velocity ratio being constant throughout the duct, and it is used to derive a new expression of the energy balance for a two-phase, non-reacting flow. Through this energy balance, new correlations for the pressure drop in pneumatic conveying lines are obtained, showing an excellent agreement with experimental data from the high-pressure research facility of the Institute of Gas Technology, Chicago, IL. Finally, a more general equation, which is also valid for the mass balance of reacting flows, is supplied. (orig.)
Liu, Yinyan; Deng, Yuchi; Zhang, Maomao; Yu, Peining; Li, Yi
2017-09-01
Oil-water two-phase flows are commonly found in the production processes of the petroleum industry. Accurate online measurement of flow rates is crucial to ensure the safety and efficiency of oil exploration and production. A research team from Tsinghua University has developed an experimental apparatus for multiphase flow measurement based on an electrical capacitance tomography (ECT) sensor, an electrical resistance tomography (ERT) sensor, and a venturi tube. This work presents the phase fraction and flow rate measurements of oil-water two-phase flows based on the developed apparatus. Full-range phase fraction can be obtained by the combination of the ECT sensor and the ERT sensor. By data fusion of differential pressures measured by venturi tube and the phase fraction, the total flow rate and single-phase flow rate can be calculated. Dynamic experiments were conducted on the multiphase flow loop in horizontal and vertical pipelines and at various flow rates.
Kassianov, Evgueni; Chand, Duli; Berg, Larry; Fast, Jerome; Tomlinson, Jason; Ferrare, Richard; Hostetler, Chris; Hair, John
2012-11-01
We use combined multi-year measurements from the surface and space for assessing the spatial and temporal distribution of aerosol properties within a large (~400x400 km) region centered on Cape Cod, Massachusetts, along the East Coast of the United States. The ground-based Aerosol Robotic Network (AERONET) measurements at Martha's Vineyard Coastal Observatory (MVCO) site and Moderate Resolution Imaging Spectrometer (MODIS) sensors on board the Terra and Aqua satellites provide horizontal and temporal variations of aerosol optical depth, while the Cloud- Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) offers the altitudes of aerosol-layers. The combined ground-based and satellite measurements indicated several interesting features among which were the large differences in the aerosol properties observed in July and February. We applied the climatology of aerosol properties for designing the Two-Column Aerosol Project (TCAP), which is supported by the U.S. Department of Energy's (DOE's) Atmospheric Radiation Measurement (ARM) Program. The TCAP field campaign involves 12-month deployment (started July 1, 2012) of the ground-based ARM Mobile Facility (AMF) and Mobile Aerosol Observing System (MAOS) on Cape Cod and complimentary aerosol observations from two research aircraft: the DOE Gulfstream-1 (G-1) and the National Aeronautics and Space Administration (NASA) B200 King Air. Using results from the coordinated G-1 and B200 flights during the recent (July, 2012) Intensive Observation Period, we demonstrated that the G-1 in situ measurements and B200 active remote sensing can provide complementary information on the temporal and spatial changes of the aerosol properties off the coast of North America.
Two-Phase Flow Technology Developed and Demonstrated for the Vision for Exploration
Sankovic, John M.; McQuillen, John B.; Lekan, Jack F.
2005-01-01
NASA s vision for exploration will once again expand the bounds of human presence in the universe with planned missions to the Moon and Mars. To attain the numerous goals of this vision, NASA will need to develop technologies in several areas, including advanced power-generation and thermal-control systems for spacecraft and life support. The development of these systems will have to be demonstrated prior to implementation to ensure safe and reliable operation in reduced-gravity environments. The Two-Phase Flow Facility (T(PHI) FFy) Project will provide the path to these enabling technologies for critical multiphase fluid products. The safety and reliability of future systems will be enhanced by addressing focused microgravity fluid physics issues associated with flow boiling, condensation, phase separation, and system stability, all of which are essential to exploration technology. The project--a multiyear effort initiated in 2004--will include concept development, normal-gravity testing (laboratories), reduced gravity aircraft flight campaigns (NASA s KC-135 and C-9 aircraft), space-flight experimentation (International Space Station), and model development. This project will be implemented by a team from the NASA Glenn Research Center, QSS Group, Inc., ZIN Technologies, Inc., and the Extramural Strategic Research Team composed of experts from academia.
Two-phase aqueous micellar systems: an alternative method for protein purification
Directory of Open Access Journals (Sweden)
Rangel-Yagui C. O.
2004-01-01
Full Text Available Two-phase aqueous micellar systems can be exploited in separation science for the extraction/purification of desired biomolecules. This article reviews recent experimental and theoretical work by Blankschtein and co-workers on the use of two-phase aqueous micellar systems for the separation of hydrophilic proteins. The experimental partitioning behavior of the enzyme glucose-6-phosphate dehydrogenase (G6PD in two-phase aqueous micellar systems is also reviewed and new results are presented. Specifically, we discuss very recent work on the purification of G6PD using: i a two-phase aqueous micellar system composed of the nonionic surfactant n-decyl tetra(ethylene oxide (C10E4, and (ii a two-phase aqueous mixed micellar system composed of C10E4 and the cationic surfactant decyltrimethylammonium bromide (C10TAB. Our results indicate that the two-phase aqueous mixed (C10E4/C10TAB micellar system can improve significantly the partitioning behavior of G6PD relative to that observed in the two-phase aqueous C10E4 micellar system.
Numerical investigation on the characteristics of two-phase flow in fuel assemblies with spacer grid
Energy Technology Data Exchange (ETDEWEB)
Chen, D.; Yang, Z.; Zhong, Y.; Xiao, Y.; Hu, L. [Chongqing Univ. (China). Key Lab. of Low-grade Energy Utilization Technologies and Systems
2016-07-15
In pressurized water reactors (PWRs), the spacer grids of the fuel assembly has significant impact on the thermal-hydraulic performance of the fuel assembly. Particularly, the spacer grids with the mixing vanes can dramatically enhance the secondary flow and have significant effect on the void distribution in the fuel assembly. In this paper, the CFD study has been carried out to analyze the effects of the spacer grid with the steel contacts, dimples and mixing vanes on the boiling two-phase flow characteristics, such as the two-phase flow field, the void distribution, and so on. Considered the influence of the boiling phase change on two-phase flow, a boiling model was proposed and applied in the CFD simulation by using the UDF (User Defined Function) method. Furthermore, in order to analyze the effects of the spacer grid with mixing vanes, the adiabatic (without boiling) two-phase flow has also been investigated as comparison with the boiling two-phase flow in the fuel assembly with spacer grids. The CFD simulation on two-phase flow in the fuel assembly with the proposed boiling model can predict the characteristics of two-phase flow better.
Multi-year GNSS monitoring of atmospheric IWV over Central and South America for climate studies
Mendoza, Luciano; Bianchi, Clara; Fernández, Laura; Natali, María Paula; Meza, Amalia; Moirano, Juan
2017-04-01
Atmospheric water vapour has been acknowledged as an essential climate variable. Weather prediction and hazard assessment systems benefit from real-time observations, whereas long-term records contribute to climate studies. Nowadays, ground-based GNSS products have become widely employed, complementing satellite observations over the oceans. Although the past decade has seen a significant development of the GNSS infrastructure in Central and South America, its potential for atmospheric water vapour monitoring has not been fully exploited. With this in mind, we have performed a regional, seven-year long and homogeneous analysis, comprising 136 GNSS tracking stations, obtaining high-rate and continuous observations of column integrated water vapour and troposphere zenith total delay (Bianchi et al. 2016). As preliminary application for this data set, we have estimated local water vapour trends, their significance, and their relation with specific climate regimes. We have found evidence of drying at temperate regions in South America, at a rate of about 2% per decade, while a slow moistening of the troposphere over tropical regions is also weakly suggested by our results. Furthermore, we have assessed the regional performance of the empirical model GPT2w to blindly estimate troposphere delays. The model fairly reproduces the observed mean delays, including their annual and semi-annual variations. Nevertheless, a long-term evaluation has shown systematical biases, up to 20 mm, probably inherited form the underling atmospheric reanalysis. Additionally, the complete data set has been made openly available at a scientific repository (doi:10.1594/PANGAEA.858234). References: C. Bianchi, L. Mendoza, L. Fernandez, M. P. Natali, A. Meza, J. F. Moirano, Multi-year GNSS monitoring of atmospheric IWV over Central and South America for climate studies, Ann. Geophys., ISSN 0992-7689, eISSN 1432-0576, 34 (7), 623-639 (doi:10.5194/angeo-34-623-2016).
Directory of Open Access Journals (Sweden)
Jan-Christoph Kattenstroth
2010-07-01
Full Text Available Aging is associated with a progressive decline of mental and physical abilities. Considering the current demographic changes in many civilizations there is an urgent need for measures permitting an independent lifestyle into old age. The critical role of physical exercise in mediating and maintaining physical and mental fitness is well-acknowledged. Dance, in addition to physical activity, combines emotions, social interaction, sensory stimulation, motor coordination and music, thereby creating enriched environmental conditions for human individuals. Here we demonstrate the impact of multi-year (average 16.5 years amateur dancing (AD in a group of elderly subjects (aged 65 to 84 years as compared to education-, gender- and aged-matched controls (CG having no record of dancing or sporting activities. Besides posture and balance parameters, we tested reaction times, motor behavior, tactile and cognitive performance. In each of the different domains investigated, the AD group had a superior performance as compared to the non-dancer CG group. Analysis of individual performance revealed that the best participants of the AD group were not better than individuals of the CG group. Instead, the AD group lacked individuals showing poor performance, which was frequently observed for the CG group. This observation implies that maintaining a regular schedule of dancing into old age can preserve cognitive, motor and perceptual abilities and prevent them from degradation. We conclude that the far-reaching beneficial effects found in the AD group make dance, beyond its ability to facilitate balance and posture, a prime candidate for the preservation of everyday life competence of elderly individuals.
Light absorption and partitioning in Arctic Ocean surface waters: impact of multi year ice melting
Directory of Open Access Journals (Sweden)
S. Bélanger
2013-03-01
Full Text Available Ice melting in the Arctic Ocean exposes the surface water to more radiative energy with poorly understood effects on photo-biogeochemical processes and heat deposition in the upper ocean. In August 2009, we documented the vertical variability of light absorbing components at 37 stations located in the southeastern Beaufort Sea including both Mackenzie river-influenced waters and polar mixed layer waters. We found that melting multi-year ice released significant amount of non-algal particulates (NAP near the sea surface relative to sub-surface waters. NAP absorption coefficients at 440 nm (aNAP(440 immediately below the sea surface (0- were on average 3-fold (up to 10-fold higher compared to sub-surface values measured at 2–3 m depth. The impact of this unusual feature on the light transmission and remote sensing reflectance (Rrs was further examined using a radiative transfer model. A 10-fold particle enrichment homogeneously distributed in the first meter of the water column slightly reduced photosynthetically available and usable radiation (PAR and PUR by ~6% and ~8%, respectively, relative to a fully homogenous water column with low particles concentration. In terms of Rrs, the particle enrichment significantly flattered the spectrum by reducing the Rrs by up to 20% in the blue-green spectral region (400–550 nm. These results highlight the impact of melt water on the concentration of particles at sea surface, and the need for considering nonuniform vertical distribution of particles in such systems when interpreting remotely sensed ocean color. Spectral slope of aNAP spectra calculated in the UV domain decreased with depth suggesting that this parameter is sensitive to detritus composition and/or diagenesis state (e.g., POM photobleaching.
Identification of saline soils with multi-year remote sensing of crop yields
Energy Technology Data Exchange (ETDEWEB)
Lobell, D; Ortiz-Monasterio, I; Gurrola, F C; Valenzuela, L
2006-10-17
Soil salinity is an important constraint to agricultural sustainability, but accurate information on its variation across agricultural regions or its impact on regional crop productivity remains sparse. We evaluated the relationships between remotely sensed wheat yields and salinity in an irrigation district in the Colorado River Delta Region. The goals of this study were to (1) document the relative importance of salinity as a constraint to regional wheat production and (2) develop techniques to accurately identify saline fields. Estimates of wheat yield from six years of Landsat data agreed well with ground-based records on individual fields (R{sup 2} = 0.65). Salinity measurements on 122 randomly selected fields revealed that average 0-60 cm salinity levels > 4 dS m{sup -1} reduced wheat yields, but the relative scarcity of such fields resulted in less than 1% regional yield loss attributable to salinity. Moreover, low yield was not a reliable indicator of high salinity, because many other factors contributed to yield variability in individual years. However, temporal analysis of yield images showed a significant fraction of fields exhibited consistently low yields over the six year period. A subsequent survey of 60 additional fields, half of which were consistently low yielding, revealed that this targeted subset had significantly higher salinity at 30-60 cm depth than the control group (p = 0.02). These results suggest that high subsurface salinity is associated with consistently low yields in this region, and that multi-year yield maps derived from remote sensing therefore provide an opportunity to map salinity across agricultural regions.
Kattenstroth, Jan-Christoph; Kolankowska, Izabella; Kalisch, Tobias; Dinse, Hubert R
2010-01-01
Aging is associated with a progressive decline of mental and physical abilities. Considering the current demographic changes in many civilizations there is an urgent need for measures permitting an independent lifestyle into old age. The critical role of physical exercise in mediating and maintaining physical and mental fitness is well-acknowledged. Dance, in addition to physical activity, combines emotions, social interaction, sensory stimulation, motor coordination and music, thereby creating enriched environmental conditions for human individuals. Here we demonstrate the impact of multi-year (average 16.5 years) amateur dancing (AD) in a group of elderly subjects (aged 65-84 years) as compared to education-, gender- and aged-matched controls (CG) having no record of dancing or sporting activities. Besides posture and balance parameters, we tested reaction times, motor behavior, tactile and cognitive performance. In each of the different domains investigated, the AD group had a superior performance as compared to the non-dancer CG group. Analysis of individual performance revealed that the best participants of the AD group were not better than individuals of the CG group. Instead, the AD group lacked individuals showing poor performance, which was frequently observed for the CG group. This observation implies that maintaining a regular schedule of dancing into old age can preserve cognitive, motor and perceptual abilities and prevent them from degradation. We conclude that the far-reaching beneficial effects found in the AD group make dance, beyond its ability to facilitate balance and posture, a prime candidate for the preservation of everyday life competence of elderly individuals.
Variability of East African rainfall based on multi-year RegCM3 simulations
Anyah, R.; Semazzi, F.
2009-04-01
The International Center for Theoretical Physics(ICTP) regional climate model version 3(ICTP-RegCM3) multi-year simulations of East Africa rainfall during the October-December, short rains season are evaluated. Two parallel runs; based on NCEP reanalysis and NASA FvGCM lateral boundary conditions are performed. The simulated monthly and seasonal rainfall climatology as well as the inter-annual variability are found to be fairly consistent with observations. The model climatology over specific homogeneous climate sub-regions, except central Kenya highlands, also reasonably agree with the observed. The latitude-time evolution(intra-seasonal variability) of the simulated seasonal rainfall exhibits two distinct modes of behavior. The first is a quasi-stationary mode associated with high rainfall throughout the season within the equatorial belt between; 1oS and 2oN. The second mode is associated with the ITCZ-driven southward migration of regions of rainfall maxima as the season progresses, which is also consistent with the observed. Furthermore, observed rainfall variability over distinct homogeneous climate sub-regions is also fairly reproduced by the model, except over central Kenya Highlands and northeastern parts of Kenya. The spatial correlation between simulated seasonal rainfall and some of the global teleconnections(DMI and Nino3.4 indices) show that the regional model conserves some of the observed regional ‘hot spots' where rainfall-ENSO/DMI association are strong. At the same, unlike observations, the model reveals that along the East Africa Rift Valley and over western parts of Lake Victoria Basin, the association is weak, perhaps an indication that non-linear interactions between local forcing (captured by the model) and large scale systems either suppresses or obscures the dominant influence of the teleconnections on rainfall over certain parts.
Natural Gas Strategic Plan and Multi-Year Program Crosscut Plan, FY 1994--1999
Energy Technology Data Exchange (ETDEWEB)
1993-12-01
DOE has established a Natural Gas Coordinating Committee to ensure that all natural gas programs are conducted with a single strategic focus and without unnecessary duplication. This group prepared the FY 1993 update of the DOE Natural Gas Strategic Plan and Multi-Year Crosscut Program Plan (FY 1993-1998), which was first produced a year ago as a ``working draft`` for industry comment. This revised version incorporates these external comments and the results and recommendations of such developments as Order No. 636 of the Federal Energy Regulatory Commission (FERC), the FERC/DOE Natural Gas Deliverability Task Force Report; the National Petroleum Council`s 1992 natural gas study, The Potential for Natural Gas in the United States; relevant provisions of the EPACT, and new policy guidance from the Clinton Administration. The overall goal of the Natural Gas RD&D Program is to improve the Nation`s ability to supply, store, transport, distribute, and utilize gas in an economically efficient and environmentally beneficial manner. In support of DOE`s missions are programs that will: improve the confidence in the continued availability of a long-term gas supply (Resource and Extraction Area); provide more cost-effective and competitive means to use natural gas in both new and existing markets (Utilization Area); develop improved and less costly means of delivering and storing gas (Delivery and Storage Area); and develop and ensure availability of low cost environmental compliance technology, and reduce regulatory barriers to efficient market operations by promoting coordinated, efficient, and innovative Federal and State regulations (Environmental/Regulatory Impact Area). Each program area has its own unique mission that contributes to the goals and mission of the overall Natural Gas Program.
Stochastic Assessment of Water Resource System Vulnerability to Multi-year Drought
Hall, J. W.; Borgomeo, E.; Farmer, C.; Pflug, G.; Hochrainer-Stigler, S.
2015-12-01
Global climate models suggest an increase in evapotranspiration in many parts of the world which is likely to cause an increase in drought severity, yet the weakness of climate models in modelling persistence of hydro-climatic variables and the uncertainties associated with regional climate projections mean that impact assessments based on climate model output may underestimate the risk of multi-year droughts. In this paper we propose a vulnerability-based approach to test water resource system response to drought. We generate a large number of synthetic streamflow series with different drought durations and deficits and use them as input to a water resource system model. Two approaches to drought simulation are presented: (1) using a numerical streamflow generator based upon an optimal bootstrapping algorithm and (2) using a copula to characterise the joint probability distribution streamflow characteristics in successive months. Droughts with longer durations and larger deficits than the observed record are generated (1) by changing the objective function of the optimisation and (2) by perturbing the copula dependence parameter and by adopting an importance sampling strategy for low flows. In this way potential climate-induced changes in monthly hydrological persistence are factored into the vulnerability analysis. The method is applied to the London water resource system (England) to investigate under which drought conditions severe water use restrictions would need to be imposed on water users. Results indicate that the water resource system is vulnerable to drought conditions outside the range of historical events. The vulnerability assessment results were coupled with climate model information to compare alternative water management options with respect to their vulnerability to increasingly long and severe drought conditions.
Multi-year persistence of beach habitat degradation from nourishment using coarse shelly sediments.
Peterson, Charles H; Bishop, Melanie J; D'Anna, Linda M; Johnson, Galen A
2014-07-15
Beach nourishment is increasingly used to protect public beach amenity and coastal property from erosion and storm damage. Where beach nourishment uses fill sediments that differ in sedimentology from native beach sands, press disturbances to sandy beach invertebrates and their ecosystem services can occur. How long impacts persist is, however, unclear because monitoring after nourishment typically only extends for several months. Here, monitoring was extended for 3-4 years following each of two spatially separated, replicate nourishment projects using unnaturally coarse sediments. Following both fill events, the contribution to beach sediments of gravel-sized particles and shell fragments was enhanced, and although diminishing through time, remained elevated as compared to control sites at the end of 3-4 years of monitoring, including in the low intertidal and swash zones, where benthic macroinvertebrates concentrate. Consequently, two infaunal invertebrates, haustoriid amphipods and Donax spp., exhibited suppressed densities over the entire post-nourishment period of 3-4 years. Emerita talpoida, by contrast, exhibited lower densities on nourished than control beaches only in the early summer of the first and second years and polychaetes exhibited little response to nourishment. The overall impact to invertebrates of nourishment was matched by multi-year reductions in abundances of their predators. Ghost crab abundances were suppressed on nourished beaches with impacts disappearing only by the fourth summer. Counts of foraging shorebirds were depressed for 4 years after the first project and 2 years after the second project. Our results challenge the view that beach nourishment is environmentally benign by demonstrating that application of unnaturally coarse and shelly sediments can serve as a press disturbance to degrade the beach habitat and its trophic services to shorebirds for 2-4 years. Recognizing that recovery following nourishment can be slow, studies
Multi-year lags between forest browning and soil respiration at high northern latitudes.
Directory of Open Access Journals (Sweden)
Ben Bond-Lamberty
Full Text Available High-latitude northern ecosystems are experiencing rapid climate changes, and represent a large potential climate feedback because of their high soil carbon densities and shifting disturbance regimes. A significant carbon flow from these ecosystems is soil respiration (R(S, the flow of carbon dioxide, generated by plant roots and soil fauna, from the soil surface to atmosphere, and any change in the high-latitude carbon cycle might thus be reflected in R(S observed in the field. This study used two variants of a machine-learning algorithm and least squares regression to examine how remotely-sensed canopy greenness (NDVI, climate, and other variables are coupled to annual R(S based on 105 observations from 64 circumpolar sites in a global database. The addition of NDVI roughly doubled model performance, with the best-performing models explaining ∼62% of observed R(S variability. We show that early-summer NDVI from previous years is generally the best single predictor of R(S, and is better than current-year temperature or moisture. This implies significant temporal lags between these variables, with multi-year carbon pools exerting large-scale effects. Areas of decreasing R(S are spatially correlated with browning boreal forests and warmer temperatures, particularly in western North America. We suggest that total circumpolar R(S may have slowed by ∼5% over the last decade, depressed by forest stress and mortality, which in turn decrease R(S. Arctic tundra may exhibit a significantly different response, but few data are available with which to test this. Combining large-scale remote observations and small-scale field measurements, as done here, has the potential to allow inferences about the temporal and spatial complexity of the large-scale response of northern ecosystems to changing climate.
Spacecraft Thermal Management using Advanced Hybrid Two-Phase Loop Technology
2007-02-01
HYBRID TWO-PHASE LOOPS The schematic of the Hybrid Two-Phase Loop (HTPL) used for a thermal testing is shown in Figure 3. Main components for the...hybrid two-phase loop with single evaporator. The thermal test starts first by turning on the liquid pump to circulate liquid along the loop. Once the...Vapor Out Evaporator Body (E1) Evaporator Body (E2) Total Heat Input Heat Input (E1) Heat Input (E2) Thermal Resistance (E1) FIGURE 10. Thermal test results
Two phase flow bifurcation due to turbulence: transition from slugs to bubbles
Górski, Grzegorz; Litak, Grzegorz; Mosdorf, Romuald; Rysak, Andrzej
2015-09-01
The bifurcation of slugs to bubbles within two-phase flow patterns in a minichannel is analyzed. The two-phase flow (water-air) occurring in a circular horizontal minichannel with a diameter of 1 mm is examined. The sequences of light transmission time series recorded by laser-phototransistor sensor is analyzed using recurrence plots and recurrence quantification analysis. Recurrence parameters allow the two-phase flow patterns to be found. On changing the water flow rate we identified partitioning of slugs or aggregation of bubbles.
Numerical simulation of bubbly two-phase flow using the lattice Boltzmann method
Energy Technology Data Exchange (ETDEWEB)
Watanabe, Tadashi; Ebihara, Kenichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment
2000-09-01
The two-component two-phase lattice Boltzmann method, in which two distribution functions are used to represent two phases, is used to simulate bubbly flows as one of the fundamental two-phase flow phenomena in nuclear application fields. The inlet flow condition is proposed to simulate steady-state flow fields. The time variation and the spatial distribution of the volume fraction and the interfacial area are measured numerically. The simulation program is parallelized in one direction by the domain decomposition method using the MPI (Message Passing Interface) libraries, and parallel computations are performed on a workstation cluster. (author)
Rarefaction Waves at the Outlet of the Supersonic Two-Phase Flow Nozzle
Nakagawa, Masafumi; Miyazaki, Hiroki; Harada, Atsushi
Two-phase flow nozzles are used in the total flow system for geothermal power plants and in the ejector of the refrigerant cycle, etc. One of the most important functions of a two-phase flow nozzle is to convert the thermal energy to the kinetic energy of the two-phase flow. The kinetic energy of the two-phase flow exhausted from a nozzle is available for all applications of this type. There exist the shock waves or rarefaction waves at the outlet of a supersonic nozzle in the case of non-best fitting expansion conditions when the operation conditions of the nozzle are widely chosen. Those waves affect largely on the energy conversion efficiency of the two-phase flow nozzle. The purpose of the present study is to elucidate the character of the rarefaction waves at the outlet of the supersonic two-phase flow nozzle. The high pressure hot water blow down experiment has been carried out. The decompression curves by the rarefaction waves are measured by changing the flow rate of the nozzle and inlet temperature of the hot water. The back pressures of the nozzle are also changed in those experiments. The divergent angles of the two-phase flow flushed out from the nozzle are measured by means of the photograph. The experimental results show that the recompression curves are different from those predicted by the isentropic homogenous two-phase flow. The regions where the rarefaction waves occur become wide due to the increased outlet speed of two-phase flow. The qualitative dependency of this expansion character is the same as the isotropic homogenous flow, but the values obtained from the experiments are quite different. When the back pressure of the nozzle is higher, these regions do not become small in spite of the super sonic two-phase flow. This means that the disturbance of the down-stream propagate to the up-stream. It is shown by the present experiments that the rarefaction waves in the supersonic two-phase flow of water have a subsonic feature. The measured
Expansion Waves at the Outlet of the Supersonic Two-Phase Flow Nozzle
Nakagawa, Masafumi; Miyazaki, Hiroki; Harada, Atsushi; Ibragimov, Zokirjon
Two-phase flow nozzles are used in the total flow system of geothermal power plants and in the ejector of the refrigeration cycle, etc. One of the most important functions of the two-phase flow nozzle is converting two-phase flow thermal energy into kinetic energy. The kinetic energy of the two-phase flow exhausted from a nozzle is available for all applications of this type. In the case of non-best fitting expansion conditions, when the operation conditions of the supersonic nozzle are widely chosen, there exist shock waves or expansion waves at the outlet of the nozzle. Those waves affect largely the energy conversion efficiency of the two-phase flow nozzle. The purpose of the present study is to elucidate character of the expansion waves at the outlet of the supersonic two-phase flow nozzle. High-pressure hot water blowdown experiments have been carried out. The decompression curves of the expansion waves are measured by changing the flowrate in the nozzle and inlet temperature of the hot water. The back pressures of the nozzle are also changed in those experiments. The expansion angles of the two-phase flow flushed out from the nozzle are measured by means of the photograph. The experimental results show that the decompression curves are different from those predicted by the isentropic homogeneous two-phase flow theory. The regions where the expansion waves occur become wide due to the increased outlet speed of the two-phase flow. The qualitative dependency of this expansion character is the same as the isentropic homogeneous flow, but the values obtained from the experiments are quite different. When the back pressure of the nozzle is higher, these regions do not become small in spite of the supersonic two-phase flow. This means that the disturbance in the downstream propagates to the upstream. It is shown by the present experiments that the expansion waves in the supersonic two-phase flow of water have a subsonic feature. The measured expansion angles become
On the nonequilibrium segregation state of a two-phase mixture in a porous column
DEFF Research Database (Denmark)
Shapiro, Alexander; Stenby, Erling Halfdan
1996-01-01
The problem of segregation of a two-phase multicomponent mixture under the action of thermal gradient, gravity and capillary forces is studied with respect to component distribution in a thick oil-gas-condensate reservoir. Governing equations are derived on the basis of nonequilibrium thermodynam...... thermodynamics. A steady state of the two-phase mixture with nonzero diffusion fluxes and exchange between phases is described. In the case of binary mixtures analytical formulae for saturation, component distribution and flow in the two-phase zone are obtained....
Institute of Scientific and Technical Information of China (English)
FENG Qixi; FENG Quanke; TAKESHI Kawai
2008-01-01
The China Advanced Research Reactor (CARR) is scheduled to be operated in the autumn of 2008. In this paper, we report preparations for installing the neutron radiography instrument (NRI) and for utilizing it efficiently. The 2-D relative neutron intensity profiles for the water-vapor two-phase flow inside the tube were obtained using the MCNP code without influence of γ-ray and electronic-noise. The MCNP simulation of the 2-D neutron intensity profile for the water-vapor two-phase flow was demonstrated. The simulated 2-D neutron intensity profiles could be used as the benchmark data base by calibrating part of the data measured by the CARR-NRI. The 3-D objective images allow us to understand the flow pattern more clearly and it is reconstructed using the MATLAB through the threshold transformation techniques. And thus it is concluded that the MCNP code and the MATLAB are very useful for constructing the benchmark data base for the investigation of the water-vapor two-phase flow using the CARR-NRI.
Lian, Enyang; Ren, Yingyu; Han, Yunfeng; Liu, Weixin; Jin, Ningde; Zhao, Junying
2016-11-01
The multi-scale analysis is an important method for detecting nonlinear systems. In this study, we carry out experiments and measure the fluctuation signals from a rotating electric field conductance sensor with eight electrodes. We first use a recurrence plot to recognise flow patterns in vertical upward gas-liquid two-phase pipe flow from measured signals. Then we apply a multi-scale morphological analysis based on the first-order difference scatter plot to investigate the signals captured from the vertical upward gas-liquid two-phase flow loop test. We find that the invariant scaling exponent extracted from the multi-scale first-order difference scatter plot with the bisector of the second-fourth quadrant as the reference line is sensitive to the inhomogeneous distribution characteristics of the flow structure, and the variation trend of the exponent is helpful to understand the process of breakup and coalescence of the gas phase. In addition, we explore the dynamic mechanism influencing the inhomogeneous distribution of the gas phase in terms of adaptive optimal kernel time-frequency representation. The research indicates that the system energy is a factor influencing the distribution of the gas phase and the multi-scale morphological analysis based on the first-order difference scatter plot is an effective method for indicating the inhomogeneous distribution of the gas phase in gas-liquid two-phase flow.
Wang, Xinyu; Cui, Yanjun; Chen, Xia; Zhu, Hao; Zhu, Weiwei; Li, Yanfeng
2015-03-01
A novel two-phase partitioning bioreactor (TPPB) modified by polysulfone (PSF) microspheres and immobilized enzyme (novozym-435) was formed, and the resulting TPPB was applied into mandelic acid chiral separation. The PSF microspheres containing n-hexanol (named PSF/hexanol microspheres) was prepared by using the phase inversion method, which was used as the organic phase. Meanwhile, the immobilized enzyme novozym-435 was used as a biocatalyst. The water phase was composed of the phosphate buffer solution (PBS). (R, S)-Methyl mandelate was selected as the substrate to study enzymatic properties. Different reaction factors have been researched, such as pH, reaction time, temperature and the quantity of biocatalyst and PSF/hexanol microspheres added in. Finally, (S)-mandelic acid was obtained with an 80 % optical purity after 24 h in the two-phase partitioning bioreactor. The enantiomeric excess (eep) values were very low in the water phase, in which the highest eep value was only 46 %. The eep of the two-phase partitioning bioreactor had been enhanced more obviously than that catalyzed in the water phase.
A New Void Fraction Measurement Method for Gas-Liquid Two-Phase Flow in Small Channels
Directory of Open Access Journals (Sweden)
Huajun Li
2016-01-01
Full Text Available Based on a laser diode, a 12 × 6 photodiode array sensor, and machine learning techniques, a new void fraction measurement method for gas-liquid two-phase flow in small channels is proposed. To overcome the influence of flow pattern on the void fraction measurement, the flow pattern of the two-phase flow is firstly identified by Fisher Discriminant Analysis (FDA. Then, according to the identification result, a relevant void fraction measurement model which is developed by Support Vector Machine (SVM is selected to implement the void fraction measurement. A void fraction measurement system for the two-phase flow is developed and experiments are carried out in four different small channels. Four typical flow patterns (including bubble flow, slug flow, stratified flow and annular flow are investigated. The experimental results show that the development of the measurement system is successful. The proposed void fraction measurement method is effective and the void fraction measurement accuracy is satisfactory. Compared with the conventional laser measurement systems using standard laser sources, the developed measurement system has the advantages of low cost and simple structure. Compared with the conventional void fraction measurement methods, the proposed method overcomes the influence of flow pattern on the void fraction measurement. This work also provides a good example of using low-cost laser diode as a competent replacement of the expensive standard laser source and hence implementing the parameter measurement of gas-liquid two-phase flow. The research results can be a useful reference for other researchers’ works.
Critical Regimes of Two-Phase Flows with a Polydisperse Solid Phase
Barsky, Eugene
2010-01-01
This book brings to light peculiarities of the formation of critical regimes of two-phase flows with a polydisperse solid phase. A definition of entropy is formulated on the basis of statistical analysis of these peculiarities. The physical meaning of entropy and its correlation with other parameters determining two-phase flows are clearly defined. The interrelations and main differences between this entropy and the thermodynamic one are revealed. The main regularities of two-phase flows both in critical and in other regimes are established using the notion of entropy. This parameter serves as a basis for a deeper insight into the physics of the process and for the development of exhaustive techniques of mass exchange estimation in such flows. The book is intended for graduate and postgraduate students of engineering studying two-phase flows, and to scientists and engineers engaged in specific problems of such fields as chemical technology, mineral dressing, modern ceramics, microelectronics, pharmacology, po...
New results in gravity dependent two-phase flow regime mapping
Kurwitz, Cable; Best, Frederick
2002-01-01
Accurate prediction of thermal-hydraulic parameters, such as the spatial gas/liquid orientation or flow regime, is required for implementation of two-phase systems. Although many flow regime transition models exist, accurate determination of both annular and slug regime boundaries is not well defined especially at lower flow rates. Furthermore, models typically indicate the regime as a sharp transition where data may indicate a transition space. Texas A&M has flown in excess of 35 flights aboard the NASA KC-135 aircraft with a unique two-phase package. These flights have produced a significant database of gravity dependent two-phase data including visual observations for flow regime identification. Two-phase flow tests conducted during recent zero-g flights have added to the flow regime database and are shown in this paper with comparisons to selected transition models. .
Concurrent two-phase downflow measurement with an induced voltage electro-magnetic flowmeter
Opara, Uroš; Bajsič, Ivan
2015-01-01
With a set of polynomial approximations a possibility is shown of the use of an induced voltage electromagnetic flowmeter in the area of measuring cocurrent two-phase downflow in tubes. The principle of the meter operation remains hereby unchanged
Numerical simulation of multi-dimensional two-phase flow based on flux vector splitting
Energy Technology Data Exchange (ETDEWEB)
Staedtke, H.; Franchello, G.; Worth, B. [Joint Research Centre - Ispra Establishment (Italy)
1995-09-01
This paper describes a new approach to the numerical simulation of transient, multidimensional two-phase flow. The development is based on a fully hyperbolic two-fluid model of two-phase flow using separated conservation equations for the two phases. Features of the new model include the existence of real eigenvalues, and a complete set of independent eigenvectors which can be expressed algebraically in terms of the major dependent flow parameters. This facilitates the application of numerical techniques specifically developed for high speed single-phase gas flows which combine signal propagation along characteristic lines with the conservation property with respect to mass, momentum and energy. Advantages of the new model for the numerical simulation of one- and two- dimensional two-phase flow are discussed.
Directory of Open Access Journals (Sweden)
Mosdorf Romuald
2015-06-01
Full Text Available The two-phase flow (water-air occurring in square minichannel (3x3 mm has been analysed. In the minichannel it has been observed: bubbly flow, flow of confined bubbles, flow of elongated bubbles, slug flow and semi-annular flow. The time series recorded by laser-phototransistor sensor was analysed using the recurrence quantification analysis. The two coefficients:Recurrence rate (RR and Determinism (DET have been used for identification of differences between the dynamics of two-phase flow patterns. The algorithm which has been used normalizes the analysed time series before calculating the recurrence plots.Therefore in analysis the quantitative signal characteristicswas neglected. Despite of the neglect of quantitative signal characteristics the analysis of its dynamics (chart of DET vs. RR allows to identify the two-phase flow patterns. This confirms that this type of analysis can be used to identify the two-phase flow patterns in minichannels.
Reversible, on-demand generation of aqueous two-phase microdroplets
Energy Technology Data Exchange (ETDEWEB)
Collier, Charles Patrick; Retterer, Scott Thomas; Boreyko, Jonathan Barton; Mruetusatorn, Prachya
2017-08-15
The present invention provides methods of on-demand, reversible generation of aqueous two-phase microdroplets core-shell microbeads, microparticle preparations comprising the core-shell microbeads, and drug delivery formulation comprising the microparticle preparations. Because these aqueous microdroplets have volumes comparable to those of cells, they provide an approach to mimicking the dynamic microcompartmentation of biomaterial that naturally occurs within the cytoplasm of cells. Hence, the present methods generate femtoliter aqueous two-phase droplets within a microfluidic oil channel using gated pressure pulses to generate individual, stationary two-phase microdroplets with a well-defined time zero for carrying out controlled and sequential phase transformations over time. Reversible phase transitions between single-phase, two-phase, and core-shell microbead states are obtained via evaporation-induced dehydration and water rehydration.
Non-local two phase flow momentum transport in S BWR
Energy Technology Data Exchange (ETDEWEB)
Espinosa P, G.; Salinas M, L.; Vazquez R, A., E-mail: gepe@xanum.uam.mx [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Area de Ingenieria en Recursos Energeticos, Apdo. Postal 55-535, 09340 Ciudad de Mexico (Mexico)
2015-09-15
The non-local momentum transport equations derived in this work contain new terms related with non-local transport effects due to accumulation, convection, diffusion and transport properties for two-phase flow. For instance, they can be applied in the boundary between a two-phase flow and a solid phase, or in the boundary of the transition region of two-phase flows where the local volume averaging equations fail. The S BWR was considered to study the non-local effects on the two-phase flow thermal-hydraulic core performance in steady-state, and the results were compared with the classical local averaging volume conservation equations. (Author)
Falabella, Steven; Meyer, Glenn A; Tang, Vincent; Guethlein, Gary
2014-06-10
A two-phase mixed media insulator having a dielectric fluid filling the interstices between macro-sized dielectric beads packed into a confined volume, so that the packed dielectric beads inhibit electro-hydrodynamically driven current flows of the dielectric liquid and thereby increase the resistivity and breakdown strength of the two-phase insulator over the dielectric liquid alone. In addition, an electrical apparatus incorporates the two-phase mixed media insulator to insulate between electrical components of different electrical potentials. And a method of electrically insulating between electrical components of different electrical potentials fills a confined volume between the electrical components with the two-phase dielectric composite, so that the macro dielectric beads are packed in the confined volume and interstices formed between the macro dielectric beads are filled with the dielectric liquid.
Formation of a two-phase microstructure in Fe-Cr-Ni alloy during directional solidification
Fu, J. W.; Yang, Y. S.; Guo, J. J.; Ma, J. C.; Tong, W. H.
2008-12-01
The formation and evolution of a two-phase coupled growth microstructure in AISI 304 stainless steel are investigated using a quenching method during directional solidification. It is found that the two-phase microstructure, which is composed of coupled growth of thin lathy delta ferrite (δ) and austenite (γ), forms from the melt first during solidification. As solidification proceeds, the retained liquid transforms into austenite directly. On cooling, the subsequent incomplete solid-state transformation from ferrite to austenite results in the disappearance of the thinner lathy delta ferrite, and the final two-phase coupled growth microstructure is formed. The formation mechanism of the two-phase coupled growth microstructure is analyzed theoretically based on the nucleation and constitutional undercooling (NCU) criterion. Transmission electron microscope (TEM) and EDS analyses were carried out to identify the phases and determine the phase composition, respectively.
Experimental study on transient behavior of semi-open two-phase thermosyphon
Institute of Scientific and Technical Information of China (English)
朱华; 王建新; 张巧惠; 屠传经
2004-01-01
An experimental system was set up to measure the temperature, pressure, heat transfer rate and mass flow rate in a semi-open two-phase thermosyphon. The behaviors of a semi-open two-phase thermosyphon during startup, shutdown and lack of water were studied to get complete understanding of its thermal characteristics. The variation of wall temperature, heat-exchange condition and pressure fluctuations of semi-open two-phase thermosyphons showed that the startup of SOTPT needs about 60-70 min; the startup speed of SOTPT is determined by the startup speed of the condensation section; the average pressure in the heat pipe is equal to the environmental pressure usually; the shutdown of SOTPT needs about 30-50min; a semi-open two-phase thermosyphon has good response to lack of water accident.
A Rotational Pressure-Correction Scheme for Incompressible Two-Phase Flows with Open Boundaries.
Dong, S; Wang, X
2016-01-01
Two-phase outflows refer to situations where the interface formed between two immiscible incompressible fluids passes through open portions of the domain boundary. We present several new forms of open boundary conditions for two-phase outflow simulations within the phase field framework, as well as a rotational pressure correction based algorithm for numerically treating these open boundary conditions. Our algorithm gives rise to linear algebraic systems for the velocity and the pressure that involve only constant and time-independent coefficient matrices after discretization, despite the variable density and variable viscosity of the two-phase mixture. By comparing simulation results with theory and the experimental data, we show that the method produces physically accurate results. We also present numerical experiments to demonstrate the long-term stability of the method in situations where large density contrast, large viscosity contrast, and backflows occur at the two-phase open boundaries.
Single and two-phase flow pressure drop for CANFLEX bundle
Energy Technology Data Exchange (ETDEWEB)
Park, Joo Hwan; Jun, Ji Su; Suk, Ho Chun [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Dimmick, G. R.; Bullock, D. E. [Atomic Energy of Canada Limited, Ontario (Canada)
1998-12-31
Friction factor and two-phase flow frictional multiplier for a CANFLEX bundle are newly developed and presented in this paper. CANFLEX as a 43-element fuel bundle has been developed jointly by AECL/KAERI to provide greater operational flexibility for CANDU reactor operators and designers. Friction factor and two-phase flow frictional multiplier have been developed by using the experimental data of pressure drops obtained from two series of Freon-134a (R-134a) CHF tests with a string of simulated CANFLEX bundles in a single phase and a two-phase flow conditions. The friction factor for a CANFLEX bundle is found to be about 20% higher than that of Blasius for a smooth circular pipe. The pressure drop predicted by using the new correlations of friction factor and two-phase frictional multiplier are well agreed with the experimental pressure drop data of CANFLEX bundle within {+-} 5% error. 11 refs., 5 figs. (Author)
Bioconversion of apigenin-7-O-β-glucoside in aqueous two-phase system
Ilić Sanja M.; Đaković Sanja D.; Cvejić Jelena H.; Antov Mirjana G.; Zeković Zoran P.
2005-01-01
The study is concerned with the conversion of apigenin-7-O-β-glucoside into apigenin in polyethylene glycol 6000 / dextran 20000 aqueous two-phase system by β-glucosidase. Apigenin was separated from apigenin-7-O-β-glucoside and β-glucosidase by their partition into opposite phases. In 14% PEG / 22.5% DEX aqueous two-phase system obtained yield of apigenin in top phase was 108%.
Bioconversion of apigenin-7-O-β-glucoside in aqueous two-phase system
Directory of Open Access Journals (Sweden)
Ilić Sanja M.
2005-01-01
Full Text Available The study is concerned with the conversion of apigenin-7-O-β-glucoside into apigenin in polyethylene glycol 6000 / dextran 20000 aqueous two-phase system by β-glucosidase. Apigenin was separated from apigenin-7-O-β-glucoside and β-glucosidase by their partition into opposite phases. In 14% PEG / 22.5% DEX aqueous two-phase system obtained yield of apigenin in top phase was 108%.
CURE OF A MICROGEL-EPOXY RESIN TWO-PHASE POLYMER WITH ETHYLENE DIAMINE
Institute of Scientific and Technical Information of China (English)
SONG Aiteng; HUANG Wei; YU Yunzhao
1992-01-01
The curing of a microgel-epoxy resin two phase polymer prepared by in situ copolymerization of unsaturated polyester with acrylic monomer was studied. The unsaturated unit reacted with N- H during the cure of the resin with ethylene diamine. The Michael type reaction was ten times more rapid than the addition of N -H to epoxide .This was accounted for the lower apparent activation energy of the curing of the two phase resin.
Estimation of the sugar cane cultivated area from LANDSAT images using the two phase sampling method
Parada, N. D. J. (Principal Investigator); Cappelletti, C. A.; Mendonca, F. J.; Lee, D. C. L.; Shimabukuro, Y. E.
1982-01-01
A two phase sampling method and the optimal sampling segment dimensions for the estimation of sugar cane cultivated area were developed. This technique employs visual interpretations of LANDSAT images and panchromatic aerial photographs considered as the ground truth. The estimates, as a mean value of 100 simulated samples, represent 99.3% of the true value with a CV of approximately 1%; the relative efficiency of the two phase design was 157% when compared with a one phase aerial photographs sample.
Numerical investigation of confined swirling gas-solid two phase jet
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
This paper presents a k-ε-kp multi-fluid model for simulating confined swirling gas-solid two phase jet comprised of particle-laden flow from a center tube and a swirling air stream entering the test section from the coaxial annular. A series of numerical simulations of the two-phase flow of 30 μm, 45 μm, 60 μm diameter particles respectively yielded results fitting well with published experimental data.
Numerical Simulation of Swirling Gas-solid Two Phase Flow through a Pipe Expansion
Institute of Scientific and Technical Information of China (English)
Jin Hanhui; Xia Jun; Fan Jianren; Cen Kefa
2001-01-01
A k- ε -kp multi-fluid model is stated and adopted to simulate swirling gas-solid two phase flow. A particle-laden flow from a center tube and a swirling air stream from the coaxial annular enter the test section. A series of numerical simulations of the two-phase flow are performed based on 30 μ m, 45 μ m, 60 μ m diameter particles respectively. The results fit well with published experimental data.
Numerical investigation of confined swirling gas-solid two phase jet
Institute of Scientific and Technical Information of China (English)
金晗辉; 夏钧; 樊建人; 岑可法
2002-01-01
This paper presents a k-e-kp multi-fluid model for simulating confined swirling gas-solid two phase jet comprised of particle-laden flow from a center tube and a swirling air stream entering the test section from the coaxial annular. A series of numerical simulations of the two-phase flow of 30μm, 45μm, 60μm diameter particles respectively yielded results fitting well with published experimental data.
Scaling analysis of gas-liquid two-phase flow pattern in microgravity
Lee, Jinho
1993-01-01
A scaling analysis of gas-liquid two-phase flow pattern in microgravity, based on the dominant physical mechanism, was carried out with the goal of predicting the gas-liquid two-phase flow regime in a pipe under conditions of microgravity. The results demonstrated the effect of inlet geometry on the flow regime transition. A comparison of the predictions with existing experimental data showed good agreement.
Oscillation of a rigid catenary riser due to the internal two-phase flow
Energy Technology Data Exchange (ETDEWEB)
Bordalo, Sergio N.; Morooka, Celso K.; Cavalcante, Cesar C.P. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil); Matt, Cyntia G.C.; Franciss, Ricardo [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas
2008-07-01
Production of petroleum reservoirs from deep and ultra-deep waters is of paramount importance in Brazil, and several researches are necessary to develop appropriated equipment and risers for those operational conditions. Risers are suspended pipes used to transport the petroleum fluids between the seabed and the floating production unit. The structural flexibility of riser's lines is conferred by its length when compared with the diameter, characterizing it as a slender body. The risers are submitted to large static and dynamic loads originated from its own weight, waves, currents, platform motions and the internal flow. These loadings may threaten, by fatigue, the structural integrity of the system, compromising its useful life, and so they must be considered in the riser's project. There is a large amount of knowledge in the literature about the effects of external loadings on these systems, but the effect of the internal flow remains vastly unexplored. The variation of the flow mass and momentum inside the riser causes a dynamic loading on this system, originating an oscillatory motion. Furthermore, the gas-liquid two-phase flow may assume several flow patterns (bubble, slug, intermittent or annular), each one possessing completely different characteristics. In this work, the influence of the internal flow on the oscillatory motion (whipping motion) of catenary risers is analyzed. To provide a better understanding of this physical phenomenon, a scaled apparatus was designed and built. The material used to manufacture the riser's model was a flexible silicone tube, and air and water were used to simulate the two-phase flow. The instrumentation used to measure the fluids flow rates and the sustaining force at the top of the model was installed in the apparatus. A video acquisition system was used to determine the displacements, and frequency spectrum, of color targets positioned throughout the model, under several flow conditions. The flow patterns
Experimental investigation of two-phase pressure drop in rough minichannels
Directory of Open Access Journals (Sweden)
Paweł Wacławczyk
2014-01-01
Full Text Available Following the general tendency of miniaturization of devices in many branches of industry, smaller and smaller components are used. Mini channels are used to construct mini heat exchangers and mini reactors. Because of this fact, predicting two-phase pressure drops along the mini tube plays an important role already at the design stage. It defines the proper and safe operating conditions of such devices. It was decided to research this phenomena in five single mini channels and undertake a comparison of various correlations models reported in literature and check how the process of changing critical Reynolds value affects the conformity of the experimental data and results reported in literature. It was found that the Mishima-Hibiki model derived from literature offers the possibility of most accurate mathematical modelling. It was also found that changing critical Reynolds value because of mini channel roughness can significantly improve the accuracy of the existing correlations models e.g. for Lee-Lee model the improvement is equal to almost 9%.
Mathematical modeling and numerical simulation of two-phase flow problems at pore scale
Directory of Open Access Journals (Sweden)
Paula Luna
2015-11-01
Full Text Available Mathematical modeling and numerical simulation of two-phase flow through porous media is a very active field of research, because of its relevancy in a wide range of physical and technological applications. Some outstanding applications concern reservoir simulation and oil and gas recovery, fields in which a great effort is being paid in the development of efficient numerical methods. The mathematical model used in this work is written as a system comprising an elliptic equation for pressure and a hyperbolic one for saturation. Our aim is to obtain the numerical solution of this model by combining finite element and finite volume techniques, with a second-order non-oscillatory reconstruction procedure to build the values of the velocities at the cell interfaces of the FV mesh from pointwise values of the pressure at the FE nodes. The numerical results are compared to those obtained using the commercial code ECLIPSE showing an appropriate behavior from a qualitative point of view. The use of this FE-FV procedure is not the usual numerical method in petroleum reservoir simulation, since the techniques most frequently used are based on finite differences, even in standard commercial tools.
Inflow performance relationship curves in two-phase and three-phase flow conditions
Energy Technology Data Exchange (ETDEWEB)
Sukarno, P.
1986-01-01
This research investigates inflow performance relationship IPR curves for two and three-phase flow conditions, using a one-dimensional, three-phase cylindrical reservoir simulator. Using the simulator, a new method for predicting future IPR curves was developed. IPR curves for two-phase flow conditions from a well producing from low permeability formations are also presented. The purpose of this investigation is to predict the IPR curves at pseudo-steady state conditions using flowing test data obtained during the transient period. The new equations have also been applied to data from the simulator with good agreement. Three-phase IPR curves are also determined by using the simulator, and seven different hypothetical three-phase reservoir cases were studied. Three-hundred and eighty five data points were collected using 5 different values of water cut. Regression analysis techniques were applied to the data points and the new equations for predicting the three-phase IPR curves were developed. Comparison of the new equations to results from the simulator show excellent agreement.
A Fast Algorithm to Simulate Droplet Motions in Oil/Water Two Phase Flow
Zhang, Tao
2017-06-09
To improve the research methods in petroleum industry, we develop a fast algorithm to simulate droplet motions in oil and water two phase flow, using phase field model to describe the phase distribution in the flow process. An efficient partial difference equation solver—Shift-Matrix method is applied here, to speed up the calculation coding in high-level language, i.e. Matlab and R. An analytical solution of order parameter is derived, to define the initial condition of phase distribution. The upwind scheme is applied in our algorithm, to make it energy decay stable, which results in the fast speed of calculation. To make it more clear and understandable, we provide the specific code for forming the coefficient matrix used in Shift-Matrix Method. Our algorithm is compared with other methods in different scales, including Front Tracking and VOSET method in macroscopic and LBM method using RK model in mesoscopic scale. In addition, we compare the result of droplet motion under gravity using our algorithm with the empirical formula common used in industry. The result proves the high efficiency and robustness of our algorithm and it’s then used to simulate the motions of multiple droplets under gravity and cross-direction forces, which is more practical in industry and can be extended to wider application.
Revalorization of a two-phase olive mill waste extract into a micronutrient fertilizer.
Rodríguez-Lucena, Patricia; Hernández, Diana; Hernández-Apaolaza, Lourdes; Lucena, Juan J
2010-01-27
Micronutrient deficiencies in plants may be treated using metal complexes. A modified two-phase olive mill waste (OMWm) was characterized using FTIR spectroscopy. A study was also made of micronutrient (Fe, Zn, Mn and Cu) complexation and the stability of complexes. An evaluation was then made of the effectiveness of Fe(III)OMWm to supply Fe to soybean (Glycine max. cv Stine 0480) chlorotic plants through nutrient solution and foliar application. The OMWm presented structural similarities with the fulvic fraction of raw OMW containing abundant phenolic-hydroxyl and carboxyl groups able to form complexes. The OMWm could complex Fe, Zn, Mn and Cu, although the stabilities of the complexes under agronomic conditions were low. In dealing with Fe chlorosis, Fe(III)-OMWm improved the Fe nutritional status of soybean chlorotic plants when applied to the nutrient solution, while only regreening of leaves was observed in foliar applications. Hence, OMWm complexes constitute a promising eco-compatible and cheap alternative to synthetic chelates in dealing with micronutrient deficiencies when applied foliarly or to the nutrient solution, although further research is necessary to improve the stability and effectiveness of the complexes.
Effects of Gravity on Cocurrent Two-Phase Gas-Liquid Flows Through Packed Columns
Motil, Brian J.; Balakotaiah, Vemuri; Kamotani, Yasuhiro
2001-01-01
This work presents the experimental results of research on the influence of gravity on flow pattern transitions, pressure drop and flow characteristics for cocurrent gas-liquid two-phase flow through packed columns. The flow pattern transition data indicates that the pulse flow regime exists over a wider range of gas and liquid flow rates under reduced gravity conditions compared to normal gravity cocurrent down-flow. This is illustrated by comparing the flow regime transitions found in reduced gravity with the transitions predicted by Talmor. Next, the effect of gravity on the total pressure drop in a packed column is shown to depend on the flow regime. The difference is roughly equivalent to the liquid static head for bubbly flow but begins to decrease at the onset of pulse flow. As the spray flow regime is approached by increasing the gas to liquid ratio, the effect of gravity on pressure drop becomes negligible. Finally, gravity tends to suppress the amplitude of each pressure pulse. An example of this phenomenon is presented.
Gas-Liquid Two-Phase Flows Through Packed Bed Reactors in Microgravity
Motil, Brian J.; Balakotaiah, Vemuri
2001-01-01
The simultaneous flow of gas and liquid through a fixed bed of particles occurs in many unit operations of interest to the designers of space-based as well as terrestrial equipment. Examples include separation columns, gas-liquid reactors, humidification, drying, extraction, and leaching. These operations are critical to a wide variety of industries such as petroleum, pharmaceutical, mining, biological, and chemical. NASA recognizes that similar operations will need to be performed in space and on planetary bodies such as Mars if we are to achieve our goals of human exploration and the development of space. The goal of this research is to understand how to apply our current understanding of two-phase fluid flow through fixed-bed reactors to zero- or partial-gravity environments. Previous experiments by NASA have shown that reactors designed to work on Earth do not necessarily function in a similar manner in space. Two experiments, the Water Processor Assembly and the Volatile Removal Assembly have encountered difficulties in predicting and controlling the distribution of the phases (a crucial element in the operation of this type of reactor) as well as the overall pressure drop.
Two-phase flow boiling in small channels: A brief review
Indian Academy of Sciences (India)
Madhavi V Sardeshpande; Vivek V Ranade
2013-12-01
Boiling flows are encountered in a wide range of industrial applications such as boilers, core and steam generators in nuclear reactors, petroleum transportation, electronic cooling and various types of chemical reactors. Many of these applications involve boiling flows in conventional channels (channel size ≥ 3 mm). The key design issues in two phase flow boiling are variation in flow regimes, occurrence of dry out condition, flow instabilities, and understanding of heat transfer coefficient and vapor quality. This paper briefly reviews published experimental and modeling work in these areas. An attempt is made to provide a perspective and to present available information on boiling in small channels in terms of channel size, flow regimes, heat transfer correlations, pressure drop, critical heat flux and film thickness. An attempt is also made to identify strengths and weaknesses of published approaches and computational models of boiling in small channels. The presented discussion and results will provide an update on the state-of-the-art and will be useful to identify and plan further research in this important area.
Benzene bioremediation using cow dung microflora in two phase partitioning bioreactor
Energy Technology Data Exchange (ETDEWEB)
Singh, Dipty [Environmental Biotechnology Laboratory, Department of Life Sciences, University of Mumbai, Vidyanagari Campus, Santacruz (E), Mumbai-400 098 (India); Fulekar, M.H., E-mail: mhfulekar@yahoo.com [Environmental Biotechnology Laboratory, Department of Life Sciences, University of Mumbai, Vidyanagari Campus, Santacruz (E), Mumbai-400 098 (India)
2010-03-15
Bioremediation of benzene has been carried out using cow dung microflora in a bioreactor. The bioremediation of benzene under the influence of cow dung microflora was found to be 100% and 67.5%, at initial concentrations of 100 mg/l and 250 mg/l within 72 h and 168 h respectively; where as at higher concentration (500 mg/l), benzene was found to be inhibitory. Hence the two phase partitioning bioreactor (TPPB) has been designed and developed to carryout biodegradation at higher concentration. In TPPB 5000 mg/l benzene was biodegraded up to 50.17% over a period of 168 h. Further the Pseudomonas putida MHF 7109 was isolated from cow dung microflora as potential benzene degrader and its ability to degrade benzene at various concentrations was evaluated. The data indicates 100%, 81% and 65% degradation at the concentrations of 50 mg/l, 100 mg/l, 250 mg/l within the time period of 24 h, 96 h and 168 h respectively. The GC-MS data also shows the presence of catechol and 2-hydroxymuconic semialdehyde, which confirms the established pathway of benzene biodegradation. The present research proves the potential of cow dung microflora as a source of biomass for benzene biodegradation in TPPB.
Gradient-augmented hybrid interface capturing method for incompressible two-phase flow
Zheng, Fu; Shi-Yu, Wu; Kai-Xin, Liu
2016-06-01
Motivated by inconveniences of present hybrid methods, a gradient-augmented hybrid interface capturing method (GAHM) is presented for incompressible two-phase flow. A front tracking method (FTM) is used as the skeleton of the GAHM for low mass loss and resources. Smooth eulerian level set values are calculated from the FTM interface, and are used for a local interface reconstruction. The reconstruction avoids marker particle redistribution and enables an automatic treatment of interfacial topology change. The cubic Hermit interpolation is employed in all steps of the GAHM to capture subgrid structures within a single spacial cell. The performance of the GAHM is carefully evaluated in a benchmark test. Results show significant improvements of mass loss, clear subgrid structures, highly accurate derivatives (normals and curvatures) and low cost. The GAHM is further coupled with an incompressible multiphase flow solver, Super CE/SE, for more complex and practical applications. The updated solver is evaluated through comparison with an early droplet research. Project supported by the National Natural Science Foundation of China (Grant Nos. 10972010, 11028206, 11371069, 11372052, 11402029, and 11472060), the Science and Technology Development Foundation of China Academy of Engineering Physics (CAEP), China (Grant No. 2014B0201030), and the Defense Industrial Technology Development Program of China (Grant No. B1520132012).
Measurement of local two-phase flow parameters of nanofluids using conductivity double-sensor probe
Directory of Open Access Journals (Sweden)
Park Yu sun
2011-01-01
Full Text Available Abstract A two-phase flow experiment using air and water-based γ-Al2O3 nanofluid was conducted to observe the basic hydraulic phenomenon of nanofluids. The local two-phase flow parameters were measured with a conductivity double-sensor two-phase void meter. The void fraction, interfacial velocity, interfacial area concentration, and mean bubble diameter were evaluated, and all of those results using the nanofluid were compared with the corresponding results for pure water. The void fraction distribution was flattened in the nanofluid case more than it was in the pure water case. The higher interfacial area concentration resulted in a smaller mean bubble diameter in the case of the nanofluid. This was the first attempt to measure the local two-phase flow parameters of nanofluids using a conductivity double-sensor two-phase void meter. Throughout this experimental study, the differences in the internal two-phase flow structure of the nanofluid were identified. In addition, the heat transfer enhancement of the nanofluid can be resulted from the increase of the interfacial area concentration which means the available area of the heat and mass transfer.
Living between two worlds: two-phase culture systems for producing plant secondary metabolites.
Malik, Sonia; Hossein Mirjalili, Mohammad; Fett-Neto, Arthur Germano; Mazzafera, Paulo; Bonfill, Mercedes
2013-03-01
The two-phase culture system is an important in vitro strategy to increase the production of secondary metabolites (SMs) by providing an enhanced release of these compounds from plant cells. Whereas the first phase supports cell growth, the second phase provides an additional site or acts as a metabolic sink for the accumulation of SMs and also reduces feedback inhibition. This review is focused on several aspects of the two-phase culture system and aims to show the diverse possibilities of employing this technique for the in vitro production of SMs from plant cells. Depending on the material used in the secondary phase, two-phase culture systems can be broadly categorised as liquid-liquid or liquid-solid. The choice of material for the second phase depends on the type of compound to be recovered and the compatibility with the other phase. Different factors affecting the efficiency of two-phase culture systems include the choice of material for the secondary phase, its concentration, volume, and time of addition. Factors such as cell elicitation, immobilization, and permeabilization, have been suggested as important strategies to make the two-phase culture system practically reliable on a commercial scale. Since there are many possibilities for designing a two-phase system, more detailed studies are needed to broaden the range of secondary phases compatible with the various plant species producing SMs with potential applications, mainly in the food and pharmacology industries.
IMPROVED SUBGRID SCALE MODEL FOR DENSE TURBULENT SOLID-LIQUID TWO-PHASE FLOWS
Institute of Scientific and Technical Information of China (English)
TANG Xuelin; QIAN Zhongdong; WU Yulin
2004-01-01
The dense solid-phase governing equations for two-phase flows are obtained by using the kinetic theory of gas molecules. Assuming that the solid-phase velocity distributions obey the Maxwell equations, the collision term for particles under dense two-phase flow conditions is also derived.In comparison with the governing equations of a dilute two-phase flow, the solid-particle's governing equations are developed for a dense turbulent solid-liquid flow by adopting some relevant terms from the dilute two-phase governing equations. Based on Cauchy-Helmholtz theorem and Smagorinsky model,a second-order dynamic sub-grid-scale (SGS) model, in which the sub-grid-scale stress is a function of both the strain-rate tensor and the rotation-rate tensor, is proposed to model the two-phase governing equations by applying dimension analyses. Applying the SIMPLEC algorithm and staggering grid system to the two-phase discretized governing equations and employing the slip boundary conditions on the walls, the velocity and pressure fields, and the volumetric concentration are calculated. The simulation results are in a fairly good agreement with experimental data in two operating cases in a conduit with a rectangular cross-section and these comparisons imply that these models are practical.
Mixed Model for Silt-Laden Solid-Liquid Two-Phase Flows
Institute of Scientific and Technical Information of China (English)
唐学林; 徐宇; 吴玉林
2003-01-01
The kinetic theory of molecular gases was used to derive the governing equations for dense solid-liquid two-phase flows from a microscopic flow characteristics viewpoint by multiplying the Boltzmann equation for each phase by property parameters and integrating over the velocity space. The particle collision term was derived from microscopic terms by comparison with dilute two-phase flow but with consideration of the collisions between particles for dense two-phase flow conditions and by assuming that the particle-phase velocity distribution obeys the Maxwell equations. Appropriate terms from the dilute two-phase governing equations were combined with the dense particle collision term to develop the governing equations for dense solid-liquid turbulent flows. The SIMPLEC algorithm and a staggered grid system were used to solve the discretized two-phase governing equations with a Reynolds averaged turbulence model. Dense solid-liquid turbulent two-phase flows were simulated for flow in a duct. The simulation results agree well with experimental data.
Preliminary Study: Treatment of Food Industrial Wastewater using Two-Phase Anaerobic Treatments
Directory of Open Access Journals (Sweden)
Shahrul Shafendy Ibrahim
2013-11-01
Full Text Available Abstract: Food processing industrial wastewater is well known for its high concentration of COD, BOD and suspended solid. The condition of the wastewater formed makes it illegal for the industry to release the wastewater to the open body of water without essential treatment. The study is conducted on food manufacturing company which specializes in chips export business. The quality of the wastewater produced from the manufacturing is not appropriate to be discharged directly. Thus, a two phase treatment system involving UASB and HUASB reactors as primary treatment and followed by AF reactor as secondary treatment is proposed. Basically, this research will focus on the performance of UASB-AF and HUASB-AF treatment systems and the affect of adding palm oil shell into the HUASB and AF respectively as support media. Parameters measured are pH, COD, NH3-N, oil and grease and total phosphorus. The instruments used for collecting data in this research are pH meter and HACH DR5000. In this research, the highest COD removal for the effluents from the U1 and U2 were at the 14th day with 93.6% removal and at the 62th day with 96.6% each. Meanwhile, in the R2 treatment system, the highest COD removal for the effluents from the H1 and H2 were at the 14th day with 98.3% removal and at 110th day with 97.6% removal. It is hoped that this study will generate useful findings that could be applied to alleviate the current problem at the food factory and also at other food industry in the future.
Multi-year ozone concentration and its spectra in Shanghai, China
Energy Technology Data Exchange (ETDEWEB)
Geng, Fuhai; Mao, Xiaoqin [Shanghai Meteorological Bureau, Shanghai (China); Shanghai Key Laboratory of Meteorology and Health, Shanghai (China); Zhou, Mingyu, E-mail: mingyuzhou34@163.com [National Marine Environmental Forecasts Center, State Oceanic Administration, Beijing (China); Zhong, Shiyuan [Department of Geography, Michigan State University, East Lansing, MI (United States); Lenschow, Donald [National Center for Atmospheric Research, Boulder, CO (United States)
2015-07-15
The periodic properties of surface ozone variation were studied at five stations with different environmental conditions in Shanghai based on multi-year observations of ozone concentration and UV radiation using spectral decomposition methods. The spectra of surface ozone have distinct peaks at semi-diurnal, diurnal, intraseasonal, semiannual, annual, and quasi-biennial periods. The spectra for the frequency band larger than the semi-diurnal follow a − 5/3 power law at all the stations. The diurnal peak values for all stations in different years are similar to each other, while the semi-diurnal peak values are somewhat different among the stations. The peak value of semi-diurnal cycle at the station Dongtan (ecological environment area) is smaller than that at the other stations. The monthly mean of surface ozone has a significant seasonal variation with a maximum in May, a secondary maximum in fall, a lower value in summer (July and August), and a minimum in December or January. However the seasonal variation of UV radiation monthly mean shows a relatively higher value in summer (July and August), and for other months it is closely related to the ozone monthly mean. These secondary peaks of the ozone monthly mean in fall might be caused by the UV radiation coming back to its relevant value after falling off during the Asia summer monsoon; it was not related to biomass burning. The intraseasonal cycling of ozone might be related to the MJO (Madden–Julian Oscillation). Further studies are needed to understand the relationship between the local ozone intraseasonal variation and the MJO. The quasi-biennial variation of ozone in Shanghai might be a local reflection of climate change and could be associated with ENSO (El-Nino Southern Oscillation). Further studies will be needed to understand the relationship of the quasi-biennial variation of ozone to ENSO. - Highlights: • The spectral decomposition methods are used. • The spectra of surface ozone have multi
Confronting multi-year idealized LES with measurements at a mid-latitude meteorological site
Schemann, V.; Neggers, R.; Wegener, C.
2015-12-01
Long-term Large-Eddy Simulation (LES) at permanent meteorological sites is increasingly being used for the evaluation and improvement of parameterizations of fast boundary-layer physics for weather and climate models. Typically, idealized LES are generated that represent fine-scale downscalings of a large-scale model state at locations of interest, resolved at temporal and spatial resolutions at which turbulence and boundary layer clouds can be expected to be resolved. The setup relies on prescribed large-scale forings in combination with continuous nudging, at a time-scale large enough to allow the resolved fast physics to have enough freedom to establish their own, unique state. This study critically assesses the representativeness of such long-term LES, and asks to what degree the continuous nudging affects the budgets of thermodynamic state variables. To this purpose long-term, multi-year LES is confronted with relevant observations at a European midlatitude continental site. The large-scale advective forcings and surface properties used to drive the LES are derived from analyses of the Integrated Forecasting System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF). Evaluated aspects of the boundary layer include near-surface meteorology, vertical structure, and bulk properties including clouds. The evaluation focuses on the diurnal cycle, with the oservational datasets derived from state-of-the-art instrumentation at the Juelich Observatory for Cloud Evolution (JOYCE) in Germany. Conditional sampling is used to highlight results for regimes of interest, including the clear convective and shallow cumulus topped boundary layer. We find that the LES is able to reproduce the observed amplitude and time-variation of key boundary layer properties, including clouds. Budget studies of the thermodynamic state variables reveal that a rough balance exists between the prescribed larger-scale advection and the turbulence/convection as resolved by the
Controls on Arctic sea ice from first-year and multi-year ice survival rates
Armour, K.; Bitz, C. M.; Hunke, E. C.; Thompson, L.
2009-12-01
The recent decrease in Arctic sea ice cover has transpired with a significant loss of multi-year (MY) ice. The transition to an Arctic that is populated by thinner first-year (FY) sea ice has important implications for future trends in area and volume. We develop a reduced model for Arctic sea ice with which we investigate how the survivability of FY and MY ice control various aspects of the sea-ice system. We demonstrate that Arctic sea-ice area and volume behave approximately as first-order autoregressive processes, which allows for a simple interpretation of September sea-ice in which its mean state, variability, and sensitivity to climate forcing can be described naturally in terms of the average survival rates of FY and MY ice. This model, used in concert with a sea-ice simulation that traces FY and MY ice areas to estimate the survival rates, reveals that small trends in the ice survival rates explain the decline in total Arctic ice area, and the relatively larger loss of MY ice area, over the period 1979-2006. Additionally, our model allows for a calculation of the persistence time scales of September area and volume anomalies. A relatively short memory time scale for ice area (~ 1 year) implies that Arctic ice area is nearly in equilibrium with long-term climate forcing at all times, and therefore observed trends in area are a clear indication of a changing climate. A longer memory time scale for ice volume (~ 5 years) suggests that volume can be out of equilibrium with climate forcing for long periods of time, and therefore trends in ice volume are difficult to distinguish from its natural variability. With our reduced model, we demonstrate the connection between memory time scale and sensitivity to climate forcing, and discuss the implications that a changing memory time scale has on the trajectory of ice area and volume in a warming climate. Our findings indicate that it is unlikely that a “tipping point” in September ice area and volume will be
Directory of Open Access Journals (Sweden)
Michal Prazenica
2011-01-01
Full Text Available This paper deals with the two-stage two-phase electronic systems with orthogonal output voltages and currents - DC/AC/AC. Design of two-stage DC/AC/AC high frequency converter with two-phase orthogonal output using single-phase matrix converter is also introduced. Output voltages of them are strongly nonharmonic ones, so they must be pulse-modulated due to requested nearly sinusoidal currents with low total harmonic distortion. Simulation experiment results of matrix converter for both steady and transient states for IM motors are given in the paper, also experimental verification under R-L load, so far. The simulation results confirm a very good time-waveform of the phase current and the system seems to be suitable for low-cost application in automotive/aerospace industries and application with high frequency voltage sources.
Transportation Research Analysis Computing Center (TRACC)
Federal Laboratory Consortium — Argonne National Laboratory initiated a multi-year program with the US Department of Transportation (USDOT) in October 2006, to establish the Transportation Research...
Energy Technology Data Exchange (ETDEWEB)
NONE
1995-09-01
This document is a compilation of data relating to the Tank Waste Remediation System Multi-Year Program. Topics discussed include: management systems; waste volume, transfer and evaporation management; transition of 200 East and West areas; ferricyanide, volatile organic vapor, and flammable gas management; waste characterization; retrieval from SSTs and DSTs; heat management; interim storage; low-level and high-level radioactive waste management; and tank farm closure.
Studies of Two-Phase Gas-Liquid Flow in Microgravity. Ph.D. Thesis, Dec. 1994
Bousman, William Scott
1995-01-01
Two-phase gas-liquid flows are expected to occur in many future space operations. Due to a lack of buoyancy in the microgravity environment, two-phase flows are known to behave differently than those in earth gravity. Despite these concerns, little research has been conducted on microgravity two-phase flow and the current understanding is poor. This dissertation describes an experimental and modeling study of the characteristics of two-phase flows in microgravity. An experiment was operated onboard NASA aircraft capable of producing short periods of microgravity. In addition to high speed photographs of the flows, electronic measurements of void fraction, liquid film thickness, bubble and wave velocity, pressure drop and wall shear stress were made for a wide range of liquid and gas flow rates. The effects of liquid viscosity, surface tension and tube diameter on the behavior of these flows were also assessed. From the data collected, maps showing the occurrence of various flow patterns as a function of gas and liquid flow rates were constructed. Earth gravity two-phase flow models were compared to the results of the microgravity experiments and in some cases modified. Models were developed to predict the transitions on the flow pattern maps. Three flow patterns, bubble, slug and annular flow, were observed in microgravity. These patterns were found to occur in distinct regions of the gas-liquid flow rate parameter space. The effect of liquid viscosity, surface tension and tube diameter on the location of the boundaries of these regions was small. Void fraction and Weber number transition criteria both produced reasonable transition models. Void fraction and bubble velocity for bubble and slug flows were found to be well described by the Drift-Flux model used to describe such flows in earth gravity. Pressure drop modeling by the homogeneous flow model was inconclusive for bubble and slug flows. Annular flows were found to be complex systems of ring-like waves and a
Bubble Generation in a Flowing Liquid Medium and Resulting Two-Phase Flow in Microgravity
Pais, S. C.; Kamotani, Y.; Bhunia, A.; Ostrach, S.
1999-01-01
The present investigation reports a study of bubble generation under reduced gravity conditions, using both a co-flow and a cross-flow configuration. This study may be used in the conceptual design of a space-based thermal management system. Ensuing two-phase flow void fraction can be accurately monitored using a single nozzle gas injection system within a continuous liquid flow conduit, as utilized in the present investigation. Accurate monitoring of void fraction leads to precise control of heat and mass transfer coefficients related to a thermal management system; hence providing an efficient and highly effective means of removing heat aboard spacecraft or space stations. Our experiments are performed in parabolic flight aboard the modified DC-9 Reduced Gravity Research Aircraft at NASA Lewis Research Center, using an air-water system. For the purpose of bubble dispersion in a flowing liquid, we use both a co-flow and a cross-flow configuration. In the co-flow geometry, air is introduced through a nozzle in the same direction with the liquid flow. On the other hand, in the cross-flow configuration, air is injected perpendicular to the direction of water flow, via a nozzle protruding inside the two-phase flow conduit. Three different flow conduit (pipe) diameters are used, namely, 1.27 cm, 1.9 cm and 2.54 cm. Two different ratios of nozzle to pipe diameter (D(sub N))sup * are considered, namely (D(sub N))sup * = 0.1 and 0.2, while superficial liquid velocities are varied from 8 to 70 cm/s depending on flow conduit diameter. It is experimentally observed that by holding all other flow conditions and geometry constant, generated bubbles decrease in size with increase in superficial liquid velocity. Detached bubble diameter is shown to increase with air injection nozzle diameter. Likewise, generated bubbles grow in size with increasing pipe diameter. Along the same lines, it is shown that bubble frequency of formation increases and hence the time to detachment of a
Directory of Open Access Journals (Sweden)
V. I. Solonin
2014-01-01
Full Text Available The article presents a research of two-phase adiabatic flow in air sparging regime in vertical cylindrical channel filled with water. A purpose of the work is to obtain experimental data for further analysis of a character of the moving phases. Research activities used the optic methods PIV (Particle Image Visualization because of their noninvasiveness to obtain data without disturbing effect on the flow. A laser sheet illuminated the fluorescence particles, which were admixed in water along the channel length. A digital camera recorded their motion for a certain time interval that allowed building the velocity vector fields. As a result, gas phase velocity components typical for a steady area of the channel and their relations for various intensity of volume air rate were obtained. A character of motion both for an air bubble and for its surrounding liquid has been conducted. The most probable direction of phases moving in the channel under sparging regime is obtained by building the statistic scalar fields. The use of image processing enabled an analysis of the initial area of the air inlet into liquid. A characteristic curve of the bubbles offset from the axis for various intensity of volume gas rate and channel diameter is defined. A character of moving phases is obtained by building the statistic scalar fields. The values of vertical components of liquid velocity in the inlet part of channel are calculated. Using the obtained data of the gas phase velocities a true void fraction was calculated. It was compared with the values of void fraction, calculated according to the liquid level change in the channel. Obtained velocities were compared with those of the other researchers, and a small difference in their values was explained by experimental conditions. The article is one of the works to research the two-phase flows with no disturbing effect on them. Obtained data allow us to understand a character of moving the two-phase flows in
DYNAMIC MODELING STRATEGY FOR FLOW REGIME TRANSITION IN GAS-LIQUID TWO-PHASE FLOWS
Energy Technology Data Exchange (ETDEWEB)
X. Wang; X. Sun; H. Zhao
2011-09-01
In modeling gas-liquid two-phase flows, the concept of flow regime has been used to characterize the global interfacial structure of the flows. Nearly all constitutive relations that provide closures to the interfacial transfers in two-phase flow models, such as the two-fluid model, are often flow regime dependent. Currently, the determination of the flow regimes is primarily based on flow regime maps or transition criteria, which are developed for steady-state, fully-developed flows and widely applied in nuclear reactor system safety analysis codes, such as RELAP5. As two-phase flows are observed to be dynamic in nature (fully-developed two-phase flows generally do not exist in real applications), it is of importance to model the flow regime transition dynamically for more accurate predictions of two-phase flows. The present work aims to develop a dynamic modeling strategy for determining flow regimes in gas-liquid two-phase flows through the introduction of interfacial area transport equations (IATEs) within the framework of a two-fluid model. The IATE is a transport equation that models the interfacial area concentration by considering the creation and destruction of the interfacial area, such as the fluid particle (bubble or liquid droplet) disintegration, boiling and evaporation; and fluid particle coalescence and condensation, respectively. For the flow regimes beyond bubbly flows, a two-group IATE has been proposed, in which bubbles are divided into two groups based on their size and shape (which are correlated), namely small bubbles and large bubbles. A preliminary approach to dynamically identifying the flow regimes is provided, in which discriminators are based on the predicted information, such as the void fraction and interfacial area concentration of small bubble and large bubble groups. This method is expected to be applied to computer codes to improve their predictive capabilities of gas-liquid two-phase flows, in particular for the applications in
Multi-year analysis of ice microphysics derived from CloudSat and CALIPSO
Okamoto, H.; Sato, K.; Hagihara, Y.
2012-12-01
We conducted multi-year analys of ice microphysics using CloudSat and CALIPSO data. Inter-annual variability, land-ocean differences and seasonal changes of ice microphysical properties were reported for the observation periods from 2006 to 2009. CALIPSO changed the laser tilt angle from 0.3 degrees to 3 degrees off nadir direction on November 2007 and the zonal mean properties of backscattering coefficient and depolarization ratio were significantly decreased and increased, respectively, for low altitude after November 2007. This could be explained by the different backscattering behavior of horizontally oriented ice crystals for the different laser tilt angles. On the other hand, inter-annual variability of zonal mean properties of reflectivity factor observed by CloudSat showed the very similar characteristics during the four years. In addition, the lidar observables were similar when the monthly mean properties were compared for different years before November 2007 and also the same was true for the comparisons after November 2007. These analyses of observables suggested that the inter-annual variability of zonal mean properties of ice microphysics could be considered to be similar. Application of the radar-lidar algorithm showed that the change of the laser tilt angle introduced the large gap between the ice microphysical properties before and after November 2007, if the proper treatment of the oriented ice crystals were not conducted in the retrievals. Global analysis of cloud particle types showed that the frequent occurrence of oriented ice crystals were identified in the temperature range between -10 to -20 degrees C. It is also noted that the significant overestimation of ice water content and significant underestimation of ice effective radius were found if the scattering properties of the horizontally oriented ice particles were not considered. Therefore it is highly demanded that the realistic ice orientation model is implemented in the look up tables
Dynamic behavior of pipes conveying gas–liquid two-phase flow
Energy Technology Data Exchange (ETDEWEB)
An, Chen, E-mail: anchen@cup.edu.cn [Offshore Oil/Gas Research Center, China University of Petroleum-Beijing, Beijing 102249 (China); Su, Jian, E-mail: sujian@lasme.coppe.ufrj.br [Nuclear Engineering Program, COPPE, Universidade Federal do Rio de Janeiro, CP 68509, Rio de Janeiro 21941-972 (Brazil)
2015-10-15
Highlights: • Dynamic behavior of pipes conveying gas–liquid two-phase flow was analyzed. • The generalized integral transform technique (GITT) was applied. • Excellent convergence behavior and long-time stability were shown. • Effects of volumetric quality and volumetric flow rate on dynamic behavior were studied. • Normalized volumetric-flow-rate stability envelope of dynamic system was determined. - Abstract: In this paper, the dynamic behavior of pipes conveying gas–liquid two-phase flow was analytically and numerically investigated on the basis of the generalized integral transform technique (GITT). The use of the GITT approach in the analysis of the transverse vibration equation lead to a coupled system of second order differential equations in the dimensionless temporal variable. The Mathematica's built-in function, NDSolve, was employed to numerically solve the resulting transformed ODE system. The characteristics of gas–liquid two-phase flow were represented by a slip-ratio factor model that was devised and used for similar problems. Good convergence behavior of the proposed eigenfunction expansions is demonstrated for calculating the transverse displacement at various points of pipes conveying air–water two-phase flow. Parametric studies were performed to analyze the effects of the volumetric gas fraction and the volumetric flow rate on the dynamic behavior of pipes conveying air–water two-phase flow. Besides, the normalized volumetric-flow-rate stability envelope for the dynamic system was obtained.
A Derivation of the Nonlocal Volume-Averaged Equations for Two-Phase Flow Transport
Directory of Open Access Journals (Sweden)
Gilberto Espinosa-Paredes
2012-01-01
Full Text Available In this paper a detailed derivation of the general transport equations for two-phase systems using a method based on nonlocal volume averaging is presented. The local volume averaging equations are commonly applied in nuclear reactor system for optimal design and safe operation. Unfortunately, these equations are limited to length-scale restriction and according with the theory of the averaging volume method, these fail in transition of the flow patterns and boundaries between two-phase flow and solid, which produce rapid changes in the physical properties and void fraction. The non-local volume averaging equations derived in this work contain new terms related with non-local transport effects due to accumulation, convection diffusion and transport properties for two-phase flow; for instance, they can be applied in the boundary between a two-phase flow and a solid phase, or in the boundary of the transition region of two-phase flows where the local volume averaging equations fail.
Gas-liquid two-phase flow across a bank of micropillars
Krishnamurthy, Santosh; Peles, Yoav
2007-04-01
Adiabatic nitrogen-water two-phase flow across a bank of staggered circular micropillars, 100μm long with a diameter of 100μm and a pitch-to-diameter ratio of 1.5, was investigated experimentally for Reynolds number ranging from 5 to 50. Flow patterns, void fraction, and pressure drop were obtained, discussed, and compared to large scale as well as microchannel results. Two-phase flow patterns were determined by flow visualization, and a flow map was constructed as a function of gas and liquid superficial velocities. Significant deviations from conventional scale systems, with respect to flow patterns and trend lines, were observed. A unique flow pattern, driven by surface tension, was observed and termed bridge flow. The applicability of conventional scale models to predict the void fraction and two-phase frictional pressure drop was also assessed. Comparison with a conventional scale void fraction model revealed good agreement, but was found to be in a physically wrong form. Thus, a modified physically based model for void fraction was developed. A two-phase frictional multiplier was found to be a strong function of mass flux, unlike in previous microchannel studies. It was observed that models from conventional scale systems did not adequately predict the two-phase frictional multiplier at the microscale, thus, a modified model accounting for mass flux was developed.
A new two-phase erosion-deposition model for mass flows
Pudasaini, Shiva P.; Fischer, Jan-Thomas
2016-04-01
Erosion, entrainment and deposition are complex and dominant, but yet poorly understood, mechanical processes in geophysical mass flows. Here, we propose a novel, two-phase, erosion-deposition model capable of adequately describing these complex phenomena commonly observed in landslides, avalanches, debris flows and bedload transports. The model enhances an existing general two-phase mass flow model (Pudasaini, 2012) by introducing a two-phase variably saturated erodible basal morphology. The adaptive basal morphology allows for the evolution of erosion-deposition-depths, incorporating the inherent physical process and rheological changes of the flowing mixture. With rigorous derivation, we show that appropriate incorporation of the mass and momentum productions and losses in conservative model formulation is essential for the physically correct and mathematically consistent description of erosion-entrainment-deposition processes. Simulation indicates a sharp erosion-front and steady-state-rear erosion depth. The model appropriately captures the emergence and propagation of complex frontal surge dynamics associated with the frontal ambient-drag which is a new hypothesis associated with erosion. The novel enhanced real two-phase model also allows for simulating fluid-run-off during the deposition process. The model resembles laboratory experiments for particle-fluid mixture flows and reveals some major aspects of the mechanics associated with erosion, entrainment and deposition. Reference: Shiva P. Pudasaini (2012): A general two-phase debris flow model. J. Geophys. Res., 117, F03010, doi: 10.1029/2011JF002186.
Performance characteristics of two-phase-flow turbo-expanders used in water-cooled chillers
Energy Technology Data Exchange (ETDEWEB)
Brasz, J.J. [United Technologies Carrier, New York, NY (United States)
1999-07-01
Use of two-phase-flow throttle loss recovery devices in water-cooled chillers requires satisfactory part-load operation. This paper describes the results of two-phase-flow impulse turbine testing and the data reduction of the test results into a two-phase-flow turbine off-design performance model. It was found that the main parameter controlling the efficiency of two-phase-flow turbine is the ratio of the nozzle spouting velocity to the rotor speed. The turbine mass flow rate is mainly controlled by inlet subcooling of the entering liquid. The strong sensitivity of turbine mass flow rate on inlet subcooling allows the use of a conventional float valve upstream of the turbine as an effective means of controlling the turbine during part-load operation. For a well-designed two-phase-flow turbine, nozzle spouting velocity and therefore turbine efficiency is hardly affected by the amount of inlet subcooling. Also, capacity can be substantially reduced by a reduction in the amount of inlet subcooling entering the turbine nozzles. Hence, turbine part-load efficiency equals its full-load efficiency over a wide range of flow rates using this control concept. (Author)
New Results in Two-Phase Pressure Drop Calculations at Reduced Gravity Conditions
Braisted, Jon; Kurwitz, Cable; Best, Frederick
2004-02-01
The mass, power, and volume energy savings of two-phase systems for future spacecraft creates many advantages over current single-phase systems. Current models of two-phase phenomena such as pressure drop, void fraction, and flow regime prediction are still not well defined for space applications. Commercially available two-phase modeling software has been developed for a large range of acceleration fields including reduced-gravity conditions. Recently, a two-phase experiment has been flown to expand the two-phase database. A model of the experiment was created in the software to determine how well the software could predict the pressure drop observed in the experiment. Of the simulations conducted, the computer model shows good agreement of the pressure drop in the experiment to within 30%. However, the software does begin to over-predict pressure drop in certain regions of a flow regime map indicating that some models used in the software package for reduced-gravity modeling need improvement.
DSMC simulation of two-phase plume flow with UV radiation
Energy Technology Data Exchange (ETDEWEB)
Li, Jie; Liu, Ying; Wang, Ning; Jin, Ling [College of Aerospace Science and Engineering, National University of Defense Technology, Changsha, Hunan, 410073 (China)
2014-12-09
Rarefied gas-particle two-phase plume in which the phase of particles is liquid or solid flows from a solid propellant rocket of hypersonic vehicle flying at high altitudes, the aluminum oxide particulates not only impact the rarefied gas flow properties, but also make a great difference to plume radiation signature, so the radiation prediction of the rarefied gas-particle two-phase plume flow is very important for space target detection of hypersonic vehicles. Accordingly, this project aims to study the rarefied gas-particle two-phase flow and ultraviolet radiation (UV) characteristics. Considering a two-way interphase coupling of momentum and energy, the direct simulation Monte Carlo (DSMC) method is developed for particle phase change and the particle flow, including particulate collision, coalescence as well as separation, and a Monte Carlo ray trace model is implemented for the particulate UV radiation. A program for the numerical simulation of the gas-particle two-phase flow and radiation in which the gas flow nonequilibrium is strong is implemented as well. Ultraviolet radiation characteristics of the particle phase is studied based on the calculation of the flow field coupled with the radiation calculation, the radiation model for different size particles is analyzed, focusing on the effects of particle emission, absorption, scattering as well as the searchlight emission of the nozzle. A new approach may be proposed to describe the rarefied gas-particle two-phase plume flow and radiation transfer characteristics in this project.
Two phase convective heat transfer augmentation in swirl flow with non-boiling
Energy Technology Data Exchange (ETDEWEB)
Cha, K.O. [Myong Ji University, Kyonggi-do (Korea, Republic of); Kim, J.G. [Myongji University Graduate School, Kyonggi-do (Korea, Republic of)
1995-10-01
Two phase flow phenomena are observed in many industrial facilities and make much importance of optimum design for nuclear power plant and various heat exchangers. This experimental study has been investigated the classification of the flow pattern, the local void distribution and convective heat transfer in swirl and non-swirl two phase flow under the isothermal and nonisothermal conditions. The convective heat transfer coefficients in the single phase water flow were measured and compared with the calculated results from the Sieder-Tate correlation. These coefficients were used for comparisons with the two-phase heat transfer coefficients in the flow orientations. The experimental results indicate, that the void probe signal and probability density function of void distribution can used into classify the flow patterns, no significant difference in voidage distribution was observed between isothermal and non-isothermal condition in non-swirl flow, the values of two phase heat transfer coefficients increase when superficial air velocities increase, and the enhancement of the values is observed to be most pronounced at the highest superficial water velocity in non-swirl flow. Also two phase heat transfer coefficients in swirl flow are increased when the twist ratios are decreased. (author). 13 refs., 15 figs.
Kamal Chowdhury, AFM; Lockart, Natalie; Willgoose, Garry; Kuczera, George; Kiem, Anthony; Parana Manage, Nadeeka
2016-04-01
Stochastic simulation of rainfall is often required in the simulation of streamflow and reservoir levels for water security assessment. As reservoir water levels generally vary on monthly to multi-year timescales, it is important that these rainfall series accurately simulate the multi-year variability. However, the underestimation of multi-year variability is a well-known issue in daily rainfall simulation. Focusing on this issue, we developed a hierarchical Markov Chain (MC) model in a traditional two-part MC-Gamma Distribution modelling structure, but with a new parameterization technique. We used two parameters of first-order MC process (transition probabilities of wet-to-wet and dry-to-dry days) to simulate the wet and dry days, and two parameters of Gamma distribution (mean and standard deviation of wet day rainfall) to simulate wet day rainfall depths. We found that use of deterministic Gamma parameter values results in underestimation of multi-year variability of rainfall depths. Therefore, we calculated the Gamma parameters for each month of each year from the observed data. Then, for each month, we fitted a multi-variate normal distribution to the calculated Gamma parameter values. In the model, we stochastically sampled these two Gamma parameters from the multi-variate normal distribution for each month of each year and used them to generate rainfall depth in wet days using the Gamma distribution. In another study, Mehrotra and Sharma (2007) proposed a semi-parametric Markov model. They also used a first-order MC process for rainfall occurrence simulation. But, the MC parameters were modified by using an additional factor to incorporate the multi-year variability. Generally, the additional factor is analytically derived from the rainfall over a pre-specified past periods (e.g. last 30, 180, or 360 days). They used a non-parametric kernel density process to simulate the wet day rainfall depths. In this study, we have compared the performance of our
Energy Technology Data Exchange (ETDEWEB)
Stekelenburg, A.J.C.
1992-11-01
A literature study on the disturbances in two-phase flow in a boiling water reactor and the impact of those disturbances on in-core detector signals is carried out. It appears that the neutron physical processes, that are important for the transfer of density disturbance to the detector signal are well understood. Although much research has been done on density fluctuations in two-phase flow, it appears that reliable theoretical models or results of extensive measurements regarding the conditions in nuclear reactors are not available. 105 refs.
Delil, A. A. M.
2001-02-01
Earlier publications extensively describe NLR research on thermal-gravitational modeling and scaling of two-phase heat transport systems for spacecraft applications. These publications on mechanically and capillary pumped two-phase loops discuss pure geometric scaling, pure fluid to fluid scaling, and combined (hybrid) scaling of a prototype system by a model at the same gravity level, and of a prototype in micro-gravity environment by a scale-model on earth. More recent publications include the scaling aspects of prototype two-phase loops for Moon or Mars applications by scale-models on earth. Recent work, discussed here, concerns extension of thermal-gravitational scaling to super-g acceleration levels. This turned out to be necessary, since a very promising super-g application for (two-phase) heat transport systems will be cooling of high-power electronics in spinning satellites and in military combat aircraft. In such aircraft, the electronics can be exposed during maneuvres to transient accelerations up to 120 m/s2. The discussions focus on ``conventional'' (capillary) pumped two-phase loops. It can be considered as introduction to the accompanying article, which focuses on pulsating and oscillating devices. .
Energy Technology Data Exchange (ETDEWEB)
Saisorn, Sira [Energy Division, The Joint Graduate School of Energy and Environment (JGSEE), King Mongkut' s University of Technology Thonburi, Bangmod, Bangkok 10140 (Thailand); Wongwises, Somchai [Fluid Mechanics, Thermal Engineering and Multiphase Flow Research Laboratory (FUTURE), Department of Mechanical Engineering, King Mongkut' s University of Technology Thonburi, Bangmod, Bangkok 10140 (Thailand)
2008-01-15
Adiabatic two-phase air-water flow characteristics, including the two-phase flow pattern as well as the void fraction and two-phase frictional pressure drop, in a circular micro-channel are experimentally studied. A fused silica channel, 320 mm long, with an inside diameter of 0.53 mm is used as the test section. The test runs are done at superficial velocity of gas and liquid ranging between 0.37-16 and 0.005-3.04 m/s, respectively. The flow pattern map is developed from the observed flow patterns i.e. slug flow, throat-annular flow, churn flow and annular-rivulet flow. The flow pattern map is compared with those of other researchers obtained from different working fluids. The present single-phase experiments also show that there are no significant differences in the data from the use of air or nitrogen gas, and water or de-ionized water. The void fraction data obtained by image analysis tends to correspond with the homogeneous flow model. The two-phase pressure drops are also used to calculate the frictional multiplier. The multiplier data show a dependence on flow pattern as well as mass flux. A new correlation of two-phase frictional multiplier is also proposed for practical application. (author)
Numerical simulation of the two-phase flow produced by spraying a liquid by a nozzle
Simakov, N. N.
2017-07-01
A numerical experiment on the simulation of the two-phase flow formed during spraying of a liquid by a nozzle has been described. The radial and axial velocity profiles of the droplets and gas in the free spray and in the two-phase flow through a cylindrical apparatus have been calculated and represented taking into account the early drag crisis of droplets and peculiarities of turbulent friction in the gas, which was detected in previous experiments. The distinguishing feature of the numerical model of the two-phase flow is that it employs the differential equations describing the nonstationary flow of a compressible gas as the initial equations. In transition to their difference analog, the familiar Lax-Wendorff algorithm has been used. A comparison of the results of calculations based on this model with experimental data has demonstrated their concordance.
Selective separation and enrichment of proteins in aqueous two-phase extraction system
Institute of Scientific and Technical Information of China (English)
Feng Qu; Hao Qin; Min Dong; Dong Xu Zhao; Xin Ying Zhao; Jing Hua Zhang
2009-01-01
A simple aqueous two-phase extraction system(ATPS)of PEG/phosphate was proposed for selective separation and enrichment of proteins.The combination of ATPE with HPLC was applied to identify the partition of proteins in two phases.Five proteins (bovine serum albumin,Cytochrome C,lysozyme,myoglobin,and trypsin)were used as model proteins to study the effect of phosphate concentration and pH on proteins partition.The PEG/phosphate system was firstly applied to real human saliva and plasma samples,some proteins showed obviously different partition in two phases.The primary results manifest the selective separation and enrichment of proteins in ATPS provided the potential for high abundance proteins depletion in proteomics.
Two-phase pressure drop across a hydrofoil-based micro pin device using R-123
Energy Technology Data Exchange (ETDEWEB)
Kosar, Ali [Mechatronics Engineering Program, Sabanci University, Orhanli, Tuzla, 34956 Istanbul (Turkey)
2008-05-15
The two-phase pressure drop in a hydrofoil-based micro pin fin heat sink has been investigated using R-123 as the working fluid. Two-phase frictional multipliers have been obtained over mass fluxes from 976 to 2349 kg/m{sup 2} s and liquid and gas superficial velocities from 0.38 to 1.89 m/s and from 0.19 to 24 m/s, respectively. It has been found that the two-phase frictional multiplier is strongly dependent on flow pattern. The theoretical prediction using Martinelli parameter based on the laminar fluid and laminar gas flow represented the experimental data fairly well for the spray-annular flow. For the bubbly and wavy-intermittent flow, however, large deviations from the experimental data were recorded. The Martinelli parameter was successfully used to determine the flow patterns, which were bubbly, wavy-intermittent, and spray-annular flow in the current study. (author)
Reduced-gravity two-phase flow experiments in the NASA KC-135
Cuta, Judith M.; Michener, Thomas E.; Best, Frederick R.; Kachnik, Leo J.
1988-01-01
An adequate understanding is sought of flow and heat transfer behavior in reduced and zero gravity conditions. Microgravity thermal-hydraulic analysis capabilities were developed for application to space nuclear power systems. A series of reduced gravity two phase flow experiments using the NASA KC-135 were performed. The objective was to supply basic thermal hydraulic information that could be used in development of analytical tools for design of space power systems. The experiments are described. Two main conclusions were drawn. First, the tests demonstrate that the KC-135 is a suitable test environment for obtaining two phase flow and heat transfer data in reduced gravity conditions. Second, the behavior of two phase flow in low gravity is sufficiently different from that obtained in 1 g to warrant intensive investigation of the phenomenon if adequate analytical tools are to be developed for microgravity conditions.
Entropy analysis on non-equilibrium two-phase flow models
Energy Technology Data Exchange (ETDEWEB)
Karwat, H.; Ruan, Y.Q. [Technische Universitaet Muenchen, Garching (Germany)
1995-09-01
A method of entropy analysis according to the second law of thermodynamics is proposed for the assessment of a class of practical non-equilibrium two-phase flow models. Entropy conditions are derived directly from a local instantaneous formulation for an arbitrary control volume of a structural two-phase fluid, which are finally expressed in terms of the averaged thermodynamic independent variables and their time derivatives as well as the boundary conditions for the volume. On the basis of a widely used thermal-hydraulic system code it is demonstrated with practical examples that entropy production rates in control volumes can be numerically quantified by using the data from the output data files. Entropy analysis using the proposed method is useful in identifying some potential problems in two-phase flow models and predictions as well as in studying the effects of some free parameters in closure relationships.
Analytical solution of laminar-laminar stratified two-phase flows with curved interfaces
Energy Technology Data Exchange (ETDEWEB)
Brauner, N.; Rovinsky, J.; Maron, D.M. [Tel-Aviv Univ. (Israel)
1995-09-01
The present study represents a complete analytical solution for laminar two-phase flows with curved interfaces. The solution of the Navier-Stokes equations for the two-phases in bipolar coordinates provides the `flow monograms` describe the relation between the interface curvature and the insitu flow geometry when given the phases flow rates and viscosity ratios. Energy considerations are employed to construct the `interface monograms`, whereby the characteristic interfacial curvature is determined in terms of the phases insitu holdup, pipe diameter, surface tension, fluids/wall adhesion and gravitation. The two monograms are then combined to construct the system `operational monogram`. The `operational monogram` enables the determination of the interface configuration, the local flow characteristics, such as velocity profiles, wall and interfacial shear stresses distribution as well as the integral characteristics of the two-phase flow: phases insitu holdup and pressure drop.
On Riemann Solvers and Kinetic Relations for Isothermal Two-Phase Flows with Surface Tension
Rohde, Christian
2016-01-01
We consider a sharp-interface approach for the inviscid isothermal dynamics of compressible two-phase flow, that accounts for phase transition and surface tension effects. To fix the mass exchange and entropy dissipation rate across the interface kinetic relations are frequently used. The complete uni-directional dynamics can then be understood by solving generalized two-phase Riemann problems. We present new well-posedness theorems for the Riemann problem and corresponding computable Riemann solvers, that cover quite general equations of state, metastable input data and curvature effects. The new Riemann solver is used to validate different kinetic relations on physically relevant problems including a comparison with experimental data. Riemann solvers are building blocks for many numerical schemes that are used to track interfaces in two-phase flow. It is shown that the new Riemann solver enables reliable and efficient computations for physical situations that could not be treated before.
Investigation of two-phase heat transfer coefficients of argon-freon cryogenic mixed refrigerants
Baek, Seungwhan; Lee, Cheonkyu; Jeong, Sangkwon
2014-11-01
Mixed refrigerant Joule Thomson refrigerators are widely used in various kinds of cryogenic systems these days. Although heat transfer coefficient estimation for a multi-phase and multi-component fluid in the cryogenic temperature range is necessarily required in the heat exchanger design of mixed refrigerant Joule Thomson refrigerators, it has been rarely discussed so far. In this paper, condensation and evaporation heat transfer coefficients of argon-freon mixed refrigerant are measured in a microchannel heat exchanger. A Printed Circuit Heat Exchanger (PCHE) with 340 μm hydraulic diameter has been developed as a compact microchannel heat exchanger and utilized in the experiment. Several two-phase heat transfer coefficient correlations are examined to discuss the experimental measurement results. The result of this paper shows that cryogenic two-phase mixed refrigerant heat transfer coefficients can be estimated by conventional two-phase heat transfer coefficient correlations.
The Two-Phase Hell-Shaw Flow: Construction of an Exact Solution
Malaikah, K. R.
2013-03-01
We consider a two-phase Hele-Shaw cell whether or not the gap thickness is time-dependent. We construct an exact solution in terms of the Schwarz function of the interface for the two-phase Hele-Shaw flow. The derivation is based upon the single-valued complex velocity potential instead of the multiple-valued complex potential. As a result, the construction is applicable to the case of the time-dependent gap. In addition, there is no need to introduce branch cuts in the computational domain. Furthermore, the interface evolution in a two-phase problem is closely linked to its counterpart in a one-phase problem
Two-Phase Master Sintering Curve for 17-4 PH Stainless Steel
Jung, Im Doo; Ha, Sangyul; Park, Seong Jin; Blaine, Deborah C.; Bollina, Ravi; German, Randall M.
2016-11-01
The sintering behavior of 17-4 PH stainless steel has been efficiently characterized by a two-phase master sintering curve model (MSC). The activation energy for the sintering of gas-atomized and water-atomized 17-4 PH powders is derived using the mean residual method, and the relative density of both powders is well predicted by the two-phase MSC model. The average error between dilatometry data and MSC model has been reduced by 68 pct for gas-atomized powder and by 45 pct for water-atomized powder through the consideration of phase transformation of 17-4 PH in MSC model. The effect of δ-ferrite is considered in the two-phase MSC model, leading to excellent explanation of the sintering behavior for 17-4 PH stainless steel. The suggested model is useful in predicting the densification and phase change phenomenon during sintering of 17-4 PH stainless steel.
An Implicit Numerical Method for the Simulation of Two-phase Flow
Energy Technology Data Exchange (ETDEWEB)
Yoon, Han Young; Lee, Seung-Jun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Jeong, Jae Jun [Pusan National University, Busan (Korea, Republic of)
2015-10-15
An implicit numerical method is presented for the analysis of two-phase flows in PWRs. Numerical stability and efficiency are improved by decoupling energy equations from the pressure equation. All the convection and diffusion terms are calculated implicitly. The proposed numerical method is verified against conceptual two-phase flow problems. An implicit numerical method has been proposed for two-phase calculation where energy equations are decoupled from the pressure equation. Convection and diffusion terms are calculated implicitly. The calculation results are the same for PME-explicit, PM explicit, and PM-implicit. Large time step size has been tested with PM-implicit-c and the results are also the same.
Numerical Study of Void Fraction Distribution Propagation in Gas-Liquid Two-Phase Flow
Institute of Scientific and Technical Information of China (English)
YANG Jianhui; LI Qing; LU Wenqiang
2005-01-01
A dynamic propagation model was developed for waves in two-phase flows by assuming that continuity waves and dynamic waves interact nonlinearly for certain flow conditions. The drift-flux model is solved with the one-dimensional continuity equation for gas-liquid two-phase flows as an initial-boundary value problem solved using the characteristic-curve method. The numerical results give the void fraction distribution propagation in a gas-liquid two-phase flow which shows how the flow pattern transition occurs. The numerical simulations of different flow patterns show that the void fraction distribution propagation is determined by the characteristics of the drift-flux between the liquid and gas flows and the void fraction range. Flow pattern transitions begin around a void fraction of 0.27 and end around 0.58. Flow pattern transitions do not occur for very high void concentrations.
Numerical Simulation of Erosion-Corrosion in the Liquid Solid Two-Phase Flow
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
Erosion-corrosion of liquid-solid two-phase flow occurring in a pipe with sudden expansion in cross section is numerically simulated in this paper. The global model for erosion-corrosion process includes three main components: the liquid-solid two-phase flow model, erosion model and corrosion model. The Euierian-Lagranglan approach is used to simulate liquid-solid two-phase flow, while the stochastic trajectory model was adopted to obtain properties of particle phase. Two-way coupling effect between the fluid and the particle phase is considered in the model. The accuracy of the models is tested by the data in the reference. The comparison shows that the model is basically correct and feasible.
The solidification of two-phase heterogeneous materials: Theory versus experiment
Institute of Scientific and Technical Information of China (English)
ZHANG Bin; KIM Tongbeum; LU TianJian
2009-01-01
The solidification behavior of two-phase heterogeneous materials such as close-celled aluminum foams was analytically studied. The proposed analytical model can precisely predict the location of solidification front as well as the full solidification time for a two-phase heterogeneous material composed of aluminum melt and non-conducting air pores. Experiments using distilled water simulating the aluminum melt to be solidified (frozen) were subsequently conducted to validate the analytical model for two selected porosities (ε), ε=0 and 0.5. Full numerical simulations with the method of finite difference were also performed to examine the influence of pore shape on solidification. The remarkable agreement between theory and experiment suggests that the delay of solidification in the two-phase heterogeneous material is mainly caused by the reduction of bulk thermal conductivity due to the presence of pores, as this is the sole mechanism accounted for by the analytical model for solidification in a porous medium.
Thermodynamic properties and mixing thermodynamic parameters of two-phase metallic melts
Institute of Scientific and Technical Information of China (English)
Jian Zhang
2005-01-01
Based on the calculating model of metallic melts involving eutectic, the calculating equations of mixing thermodynamic parameters for two phase metallic melts have been formulated in the light of those equations of homogeneous solutions. Irrespective as to whether the activity deviation relative to Raoultian behavior is positive or negative, or the deviation is symmetrical or unsymmetrical, the evaluated results not only agree well with experimental values, but also strictly obey the mass action law. This testifies that these equations can authentically reflect the structural reality and mixing thermodynamic characteristics of two-phase metallic melts. The calculating equations of mixing thermodynamic parameters for the model of two phase metallic melts offer two practical criteria (activity and mixing thermodynamic parameters) and one theoretical criterion (the mass action law).
Thermodynamic calculations of a two-phase thermosyphon loop for cold neutron sources
de Haan, Victor-O.; Gommers, René; Rowe, J. Michael
2017-07-01
A new method is described for thermodynamic calculations of a two-phase thermosyphon loop based on a one-dimensional finite element division, where each time-step is split up in a change of enthalpy and a change in entropy. The method enables the investigation of process responses for a cooling loop from room temperature down to cryogenic temperatures. The method is applied for the simulation of two distinct thermosyphon loops: a two-phase deuterium and a two-phase hydrogen thermosyphon loop. The simulated process responses are compared to measurements on these loops. The comparisons show that the method can be used to optimize the design of such loops with respect to performance and resulting void fractions.
Two-phase application of multi-objective genetic algorithms in green building design
Energy Technology Data Exchange (ETDEWEB)
Wang, W.; Zmeureanu, R. [Concordia Univ., Centre for Building Studies, Montreal, PQ (Canada). Dept. of Building, Civil and Environmental Engineering; Rivard, H. [Ecole de Technologie Superieure, Montreal, PQ (Canada). Dept. of Construction Engineering
2005-07-01
The application of multi-objective genetic algorithms for green building design in two phases were presented in order to better help designers in the decision-making process. The purpose is to minimize two conflicting criteria: the life-cycle cost and the life-cycle environmental impact. Environmental impact criteria examined include energy and non-energy natural resources, global warming, and acidification. Variables focus on building envelope-related parameters. The application of multi-objective genetic algorithms is divided into two phases. The first phase intends to help designers in understanding the trade-off relationship between the two conflicting criteria. The second phase intends to refine the performance region that is of the designer's interest. The results after the two-phase application of the multi objective genetic algorithm were then presented. 13 refs., 4 tabs., 3 figs.
OPTIMIZATION DESIGN OF GAS-PARTICLE TWO-PHASE AXIAL-FLOW FAN
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
Based on the shaping theory of writhed blade in streamline design, the geometric shape of blade is designed and then computational formulas for the dynamic design of fan with writhed the blades in gas-particle two-phase axial-flow are derived with the two-phase continuum coupling model. Concurrently, the correlation between the structure of impeller and flow-field dynamic functional parameters is presented. Further, the software for the optimization design of gas-particle two-phase axial-flow fan with writhed blades is obtained. By means of the available software, a sample fan is formed with its all dynamic characteristic curves and geometric shape. Finally, the conclusion on the effect of particles on fan running is reached, quantitatively and qualitatively, as is expected in the fan industry.
Numerical simulation of the two-phase flows in a hydraulic coupling by solving VOF model
Luo, Y.; Zuo, Z. G.; Liu, S. H.; Fan, H. G.; Zhuge, W. L.
2013-12-01
The flow in a partially filled hydraulic coupling is essentially a gas-liquid two-phase flow, in which the distribution of two phases has significant influence on its characteristics. The interfaces between the air and the liquid, and the circulating flows inside the hydraulic coupling can be simulated by solving the VOF two-phase model. In this paper, PISO algorithm and RNG k-ɛ turbulence model were employed to simulate the phase distribution and the flow field in a hydraulic coupling with 80% liquid fill. The results indicate that the flow forms a circulating movement on the torus section with decreasing speed ratio. In the pump impeller, the air phase mostly accumulates on the suction side of the blades, while liquid on the pressure side; in turbine runner, air locates in the middle of the flow passage. Flow separations appear near the blades and the enclosing boundaries of the hydraulic coupling.
Interfacial Area and Interfacial Transfer in Two-Phase Flow Systems (Volume II. Chapters 6-10)
Energy Technology Data Exchange (ETDEWEB)
Guo, T.; Park, J.; Kojasoy, G.
2003-03-15
Experiments were performed on horizontal air-water bubbly two-phase flow, axial flow, stratified wavy flow, and annular flow. Theoretical studies were also undertaken on interfacial parameters for a horizontal two-phase flow.
Interfacial Area and Interfacial Transfer in Two-Phase Flow Systems (Volume III. Chapters 11-14)
Energy Technology Data Exchange (ETDEWEB)
Guo, T.; Park, J.; Kojasoy, G.
2003-03-15
Experiments were performed on horizontal air-water bubbly two-phase flow, axial flow, stratified wavy flow, and annular flow. Theoretical studies were also undertaken on interfacial parameters for a horizontal two-phase flow.
Interfacial Area and Interfacial Transfer in Two-Phase Flow Systems (Volume IV. Chapters 15-19)
Energy Technology Data Exchange (ETDEWEB)
Guo, T.; Park, J.; Kojasoy, G.
2003-03-15
Experiments were performed on horizontal air-water bubbly two-phase flow, axial flow, stratified wavy flow, and annular flow. Theoretical studies were also undertaken on interfacial parameters for a horizontal two-phase flow.
Interfacial Area and Interfacial Transfer in Two-Phase Flow Systems (Volume I. Chapters 1-5)
Energy Technology Data Exchange (ETDEWEB)
Guo, T.; Park, J.; Kojasoy, G.
2003-03-15
Experiments were performed on horizontal air-water bubbly two-phase flow, axial flow, stratified wavy flow, and annular flow. Theoretical studies were also undertaken on interfacial parameters for a horizontal two-phase flow.
Energy Technology Data Exchange (ETDEWEB)
Kock, Ingo; Frieling, Gerd; Navarro, Martin
2016-10-15
In the frame of the research project ZIESEL the GRS enhanced the state of science and technology for the realization and evaluation of long-term safety cases for the final deposition of radioactive wastes. The superior aim was the improved understanding of two-phase flow processes in a complex final repository system. The consideration of two-phase processes in modeling of final repository systems induces processes and effects that significantly affect the transport behavior of fluid and radionuclides. Two-phase processes include not only capillary pressures and relative permeabilities but also a basic competition of phases with respect to pore volume for storage and transport and density-driven vertical separation of phases. Basically seals have been shown to be essential for the system behavior because of their influence of the gas pressure dependent control function. The system behavior is also influences by the model geometry.
Investigation of Two-Phase Flow in AxialCentrifugal Impeller by Hydrodynamic Modeling Methods
Directory of Open Access Journals (Sweden)
V. O. Lomakin
2014-01-01
Full Text Available The article provides a methodology to study the flow in the wet part of the pump with fundamentally new axial-centrifugal impeller by methods of hydrodynamic modeling in the software package STAR CCM +. The objective of the study was to determine the normal and cavitation characteristics of the pump with a new type of wet part, as well as optimization of the geometrical parameters of the pump. Authors solved this problem using an example of the hot coolant pump, which should meet high requirements for cavitation quality and efficiency (hydraulic efficiency up to 87%, critical value of NPSH to 2.2 m.Also, the article focuses on the methods of numerical solution of two-phase flow simulation in a pump that are needed for a more accurate simulation of cavitation in the pump and research work in liquids with high gas content.Hydrodynamic modeling was performed on a computing cluster at the department E-10 of BMSTU for pump flow simulation in unsteady statement of problem using the computational grid size to 1.5 million cells. Simultaneously, the experimental model of the pump was made by 3D printing and tested at the stand in the BMSTU. Test results, which were compared with the calculated data are also given in the article. Inaccuracy of the calculation of pump head does not exceed 5%.The simulation results may be of interest to specialists in the field of hydrodynamic modeling, and for designers of such pumps. The authors also report production of a full-length prototype of the pump in order to conduct further testing for the verification of the data in the article, primarily in terms of cavitation characteristics.
Development of two-phase Flow Model, 'SOBOIL', for Sodium
Energy Technology Data Exchange (ETDEWEB)
Hahn, Do Hee; Chang, Won Pyo; Kim, In Chul; Kwon, Young Min; Lee, Yong Bum
2000-03-01
The objective of this research is to develop a sodium two-phase flow analysis model, 'SOBOIL', for the assessment of the initial stage of the KALIMER HCDA (Hypotherical Core Disruptive Accident). The 'SOBOIL' is basically similar to the multi-bubble slug ejection model used in SAS2A[1]. When a bubble is formed within the liquid slug, the bubble fills the whole cross section of the coolant channel except for a film left on the cladding or on the structure. Up to nine bubbles, separated by the liquid slugs, are allowed in the channel at any time. Each liquid slug flow rate in the model is performed in 2 steps. In the first step, the preliminary flow rate in the liquid slug is calculated neglecting the effect of changes in the vapor bubble pressures over the time step. The temperature and pressure distributions, and interface velocity at the interface between the liquid slug and vapor bubble are also calculated during this process. The new vapor temperature and pressure are then determined from the balance between the net energy transferred into the vapor and the change of the vapor energy. The liquid flow is finally calculated considering the change of the vapor pressure over a time step and the calculation is repeated until specified elapsed time is met. Continuous effort, therefore, must be made on the examination and improvement for the model to become reliable. To this end, much interest must be concentrated in the relevant international collaborations for access to a reference model or test data for the verification.
Intermediate scales between simulation and modeling of two-phase flows
Energy Technology Data Exchange (ETDEWEB)
Pigny, Sylvain L., E-mail: sylvain.pigny@cea.f [CEA/DEN, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)
2011-03-15
Research highlights: Simulation and modeling of bubbles are done at high Reynolds number. Intermediate scales between simulation and modeling are of importance. Specific approaches can be envisaged in accurate multiphase codes. An attempt leads to agreement with experimental data. We establish a link between multiphase codes and DNS ones. - Abstract: Phenomena related to two-phase flows in an experiment in which air is injected in the lower part of a tank filled with water are investigated, via the SIMMER-IV software. The Reynolds and Weber numbers of the bubbly flow have high values. Small scale phenomena, related to small bubbles behavior or turbulence in the liquid continuous phase, are modeled via classical closure laws. An attempt to represent the formation of individual large bubbles, close to the injector, via direct simulation is done. In a first calculation, the large bubbles break-up is not represented. This phenomenon, the space scale of which is close to the cell size, cannot be simulated, with the present computational resources. Nevertheless, relatively fine meshes are used, for an accurate description of hydrodynamical phenomena, and these phenomena are too large to be modeled via closure laws. The case is therefore useful to underline some basic limits in the potentialities of direct simulation and modeling and to propose an attempt to face the problem. The breakup of bubbles is now represented. Finally the validity of the approach is checked directly by simulating a single bubble experiment. The problem of the convergence between multiphase codes and direct simulation ones is pointed.
Evaluation of two-phase flow solvers using Level Set and Volume of Fluid methods
Bilger, C.; Aboukhedr, M.; Vogiatzaki, K.; Cant, R. S.
2017-09-01
Two principal methods have been used to simulate the evolution of two-phase immiscible flows of liquid and gas separated by an interface. These are the Level-Set (LS) method and the Volume of Fluid (VoF) method. Both methods attempt to represent the very sharp interface between the phases and to deal with the large jumps in physical properties associated with it. Both methods have their own strengths and weaknesses. For example, the VoF method is known to be prone to excessive numerical diffusion, while the basic LS method has some difficulty in conserving mass. Major progress has been made in remedying these deficiencies, and both methods have now reached a high level of physical accuracy. Nevertheless, there remains an issue, in that each of these methods has been developed by different research groups, using different codes and most importantly the implementations have been fine tuned to tackle different applications. Thus, it remains unclear what are the remaining advantages and drawbacks of each method relative to the other, and what might be the optimal way to unify them. In this paper, we address this gap by performing a direct comparison of two current state-of-the-art variations of these methods (LS: RCLSFoam and VoF: interPore) and implemented in the same code (OpenFoam). We subject both methods to a pair of benchmark test cases while using the same numerical meshes to examine a) the accuracy of curvature representation, b) the effect of tuning parameters, c) the ability to minimise spurious velocities and d) the ability to tackle fluids with very different densities. For each method, one of the test cases is chosen to be fairly benign while the other test case is expected to present a greater challenge. The results indicate that both methods can be made to work well on both test cases, while displaying different sensitivity to the relevant parameters.
Numerical investigation of the mechanism of two-phase flow instability in parallel narrow channels
Energy Technology Data Exchange (ETDEWEB)
Hu, Lian [Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University (China); Chen, Deqi, E-mail: chendeqi@cqu.edu.cn [Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University (China); CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology, Nuclear Power Institute of China, Chengdu 610041 (China); Huang, Yanping, E-mail: hyanping007@163.com [CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology, Nuclear Power Institute of China, Chengdu 610041 (China); Yuan, Dewen; Wang, Yanling [CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology, Nuclear Power Institute of China, Chengdu 610041 (China); Pan, Liangming [Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University (China)
2015-06-15
Highlights: • A mathematical model is proposed to predict the two-phase flow instability. • The mathematical model predicted result agrees well with the experimental result. • Oscillation characteristics of the two-phase flow instability is discussed in detail. - Abstract: In this paper, the mechanism of two-phase flow instability in parallel narrow channels is studied theoretically, and the characteristic of the flow instability is discussed in detail. Due to the significant confining effect of the narrow channel on the vapor–liquid interface, the two-phase flow resistance in the narrow channel is probably different from that in conventional channel. Therefore, the vapor confined number (N{sub conf}), defined by the size of narrow channel and bubble detachment diameter, is considered in the “Chisholm B model” to investigate the two-phase flow pressure drop. The flow instability boundaries are plotted in parameter plane with phase-change-number (N{sub pch}) and subcooling-number (N{sub sub}) under different working conditions. It is found that the predicted result agrees well with the experimental result. According to the predicted result, the oscillation behaviors near the flow instability boundary indicate that the Supercritical Hopf bifurcation appears in high sub-cooled region and the Subcritical Hopf bifurcation appears in low sub-cooled region. Also, a detailed analysis about the effects of key parameters on the characteristic of two-phase flow instability and the flow instability boundary is proposed, including the effects of inlet subcooling, heating power, void distribution parameter and drift velocity.
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Based on the Biot's theory about two-phase saturated medium, according to the character of d function, the Green function on two-phase saturated medium by the point source under concentrated force can be derived. By the Betti's theorem for the two-phase saturated medium field, the source vector and static displacement field by elastic dislocation on the two-phase saturated medium were comprehensively discussed.
Investigation on two-phase flow instability in steam generator of integrated nuclear reactor
Institute of Scientific and Technical Information of China (English)
无
1996-01-01
In the pressure range of 3-18MPa,high pressure steam-water two-phase flow density wave instability in vertical upward parallel pipes with inner diameter of 12mm is studied experimentally.The oscillation curves of two-phase flow instability and the effects of several parameters on the oscillation threshold of the system are obtained.Based on the small pertubation linearization method and the stability principles of automatic control system,a mathematical model is developed to predict the characteristics of density wave instability threshold.The predictions of the model are in good agreement with the experimental results.
Position Control of Synchronous Motor Drive by Modified Adaptive Two-phase Sliding Mode Controller
Institute of Scientific and Technical Information of China (English)
Mohamed Said Sayed Ahmed; Ping Zhang; Yun-Jie Wu
2008-01-01
A modified adaptive two-phase sliding mode controller for the synchronous motor drive that is highly robust to uncertain-ties and external disturbances is proposed in this paper. The proposed controller uses two-phase sliding mode control (SMC) where the 1st phase mainly controls the system in steady states and disturbed states-it is a smoothing phase. The 2nd phase is used mainly in the case of disturbed states. Also, it is an autotuning phase and uses a simple adaptive algorithm to tune the gain of conventional variable structure control (VSC). The modified controller is useful in position control of a permanent magnet synchronous drive.
Film boiling on spheres in single- and two-phase flows.
Energy Technology Data Exchange (ETDEWEB)
Liu, C.; Theofanous, T. G.
2000-08-29
Film boiling on spheres in single- and two-phase flows was studied experimentally and theoretically with an emphasis on establishing the film boiling heat transfer closure law, which is useful in the analysis of nuclear reactor core melt accidents. Systematic experimentation of film boiling on spheres in single-phase water flows was carried out to investigate the effects of liquid subcooling (from 0 to 40 C), liquid velocity (from 0 to 2 m/s), sphere superheat (from 200 to 900 C), sphere diameter (from 6 to 19 mm), and sphere material (stainless steel and brass) on film boiling heat transfer. Based on the experimental data a general film boiling heat transfer correlation is developed. Utilizing a two-phase laminar boundary-layer model for the unseparated front film region and a turbulent eddy model for the separated rear region, a theoretical model was developed to predict the film boiling heat transfer in all single-phase regimes. The film boiling from a sphere in two-phase flows was investigated both in upward two-phase flows (with void fraction from 0.2 to 0.65, water velocity from 0.6 to 3.2 m/s, and steam velocity from 3.0 to 9.0 m/s) and in downward two-phase flows (with void fraction from 0.7 to 0.95, water velocity from 1.9 to 6.5 m/s, and steam velocity from 1.1 to 9.0 m/s). The saturated single-phase heat transfer correlation was found to be applicable to the two-phase film boiling data by making use of the actual water velocity (water phase velocity), and an adjustment factor of (1 - {alpha}){sup 1/4} (with a being the void fraction) for downward flow case only. Slight adjustments of the Reynolds number exponents in the correlation provided an even better interpretation of the two-phase data. Preliminary experiments were also conducted to address the influences of multi-sphere structure on the film boiling heat transfer in single- and two-phase flows.
Camomile autofermentation in polyethylene glycol/dextran two-phase system
Directory of Open Access Journals (Sweden)
Đaković Sanja D.
2008-01-01
Full Text Available The objective of this study was the investigation of the extractive bioconversion of apigenin-7-O-β-glucoside in camomile ligulate flowers into apigenin by autofermentation in polyethylene glycol 6000/dextran 200000 two-phase system. In 22.5% polyethylene glycol/14% dextran aqueous two-phase system the obtained yield of apigenin in the top phase was 96.5%. In the presence of plant material that partiotioned to the interphase, the yield of apigenin in the top phase was 3.5 times higher in comparison to the model system.
Preliminary Two-Phase Terry Turbine Nozzle Models for RCIC Off-Design Operation Conditions
Energy Technology Data Exchange (ETDEWEB)
Zhao, Haihua [Idaho National Lab. (INL), Idaho Falls, ID (United States); O' Brien, James [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2017-06-12
This report presents the effort to extend the single-phase analytical Terry turbine model to cover two-phase off-design conditions. The work includes: (1) adding well-established two-phase choking models – the Isentropic Homogenous Equilibrium Model (IHEM) and Moody’s model, and (2) theoretical development and implementation of a two-phase nozzle expansion model. The two choking models provide bounding cases for the two-phase choking mass flow rate. The new two-phase Terry turbine model uses the choking models to calculate the mass flow rate, the critical pressure at the nozzle throat, and steam quality. In the divergent stage, we only consider the vapor phase with a similar model for the single-phase case by assuming that the liquid phase would slip along the wall with a much slower speed and will not contribute the impulse on the rotor. We also modify the stagnation conditions according to two-phase choking conditions at the throat and the cross-section areas for steam flow at the nozzle throat and at the nozzle exit. The new two-phase Terry turbine model was benchmarked with the same steam nozzle test as for the single-phase model. Better agreement with the experimental data is observed than from the single-phase model. We also repeated the Terry turbine nozzle benchmark work against the Sandia CFD simulation results with the two-phase model for the pure steam inlet nozzle case. The RCIC start-up tests were simulated and compared with the single-phase model. Similar results are obtained. Finally, we designed a new RCIC system test case to simulate the self-regulated Terry turbine behavior observed in Fukushima accidents. In this test, a period inlet condition for the steam quality varying from 1 to 0 is applied. For the high quality inlet period, the RCIC system behaves just like the normal operation condition with a high pump injection flow rate and a nominal steam release rate through the turbine, with the net addition of water to the primary system; for
Two-phase flow stability structure in a natural circulation system
Energy Technology Data Exchange (ETDEWEB)
Zhou, Zhiwei [Nuclear Engineering Laboratory Zurich (Switzerland)
1995-09-01
The present study reports a numerical analysis of two-phase flow stability structures in a natural circulation system with two parallel, heated channels. The numerical model is derived, based on the Galerkin moving nodal method. This analysis is related to some design options applicable to integral heating reactors with a slightly-boiling operation mode, and is also of general interest to similar facilities. The options include: (1) Symmetric heating and throttling; (2) Asymmetric heating and symmetric throttling; (3) Asymmetric heating and throttling. The oscillation modes for these variants are discussed. Comparisons with the data from the INET two-phase flow stability experiment have qualitatively validated the present analysis.
Problems of heat transfer and hydraulics of two-phase media
Kutateladze, S S
1969-01-01
Problems of Heat Transfer and Hydraulics of Two-Phase Media presents the theory of heat transfer and hydrodynamics. This book discusses the various aspects of heat transfer and the flow of two-phase systems. Organized into two parts encompassing 22 chapters, this book starts with an overview of the laws of similarity for heat transfer to or from a flowing liquid with various physical properties and allowed for variation in viscosity and thermal conductivity. This book then explores the general functional relationship that exists between viscosity and thermal conductivity for thermodynamically
Two-Phase Flow in Geothermal Wells: Development and Uses of a Good Computer Code
Energy Technology Data Exchange (ETDEWEB)
Ortiz-Ramirez, Jaime
1983-06-01
A computer code is developed for vertical two-phase flow in geothermal wellbores. The two-phase correlations used were developed by Orkiszewski (1967) and others and are widely applicable in the oil and gas industry. The computer code is compared to the flowing survey measurements from wells in the East Mesa, Cerro Prieto, and Roosevelt Hot Springs geothermal fields with success. Well data from the Svartsengi field in Iceland are also used. Several applications of the computer code are considered. They range from reservoir analysis to wellbore deposition studies. It is considered that accurate and workable wellbore simulators have an important role to play in geothermal reservoir engineering.
Determination of production-shipment policy using a two-phase algebraic approach
Directory of Open Access Journals (Sweden)
Huei-Hsin Chang
2012-04-01
Full Text Available The optimal production-shipment policy for end products using mathematicalmodeling and a two-phase algebraic approach is investigated. A manufacturing systemwith a random defective rate, a rework process, and multiple deliveries is studied with thepurpose of deriving the optimal replenishment lot size and shipment policy that minimisestotal production-delivery costs. The conventional method uses differential calculus on thesystem cost function to determine the economic lot size and optimal number of shipmentsfor such an integrated vendor-buyer system, whereas the proposed two-phase algebraicapproach is a straightforward method that enables practitioners who may not havesufficient knowledge of calculus to manage real-world systems more effectively.
The performance of a cryogenic pump for the two-phase flow condition
YAMADA, HITOSHI; WATANABE, Mitsuo; Hasegawa, Satoshi; Kamijo, Kenjiro; 山田, 仁; 渡辺, 光男; 長谷川, 敏; 上條, 謙二郎
1985-01-01
An experimental investigation was carried out in order to obtain the performance characteristics of a cryogenic pump under a two-phase flow condition. The experiment used an oxygen pump with an inducer and liquid nitrogen as the test fluid. The vapor volumetric fraction at the pump inlet was calculated with an assumption of a constant enthalpy process across an orifice which was used to generate the two-phase flow at the pump inlet. The results showed that the pump head rise did hardly decrea...
Estimation of flow velocity for a debris flow via the two-phase fluid model
Directory of Open Access Journals (Sweden)
S. Guo
2014-06-01
Full Text Available The two-phase fluid model is applied in this study to calculate the steady velocity of a debris flow along a channel bed. By using the momentum equations of the solid and liquid phases in the debris flow together with an empirical formula to describe the interaction between two phases, the steady velocities of the solid and liquid phases are obtained theoretically. The comparison of those velocities obtained by the proposed method with the observed velocities of two real-world debris flows shows that the proposed method can estimate accurately the velocity for a debris flow.
Characterization of annular two-phase gas-liquid flows in microgravity
Bousman, W. Scott; Mcquillen, John B.
1994-01-01
A series of two-phase gas-liquid flow experiments were developed to study annular flows in microgravity using the NASA Lewis Learjet. A test section was built to measure the liquid film thickness around the perimeter of the tube permitting the three dimensional nature of the gas-liquid interface to be observed. A second test section was used to measure the film thickness, pressure drop and wall shear stress in annular microgravity two-phase flows. Three liquids were studied to determine the effects of liquid viscosity and surface tension. The result of this study provide insight into the wave characteristics, pressure drop and droplet entrainment in microgravity annular flows.
Thermal Marangoni Convection of Two-phase Dusty Fluid Flow along a Vertical Wavy Surface
Directory of Open Access Journals (Sweden)
S. Siddiqa
2017-01-01
Full Text Available The paper considers the influence of thermal Marangoni convection on boundary layer flow of two-phase dusty fluid along a vertical wavy surface. The dimensionless boundary layer equations for two-phase problem are reduced to a convenient form by primitive variable transformations (PVF and then integrated numerically by employing the implicit finite difference method along with the Thomas Algorithm. The effect of thermal Marangoni convection, dusty water and sinusoidal waveform are discussed in detail in terms of local heat transfer rate, skin friction coefficient, velocity and temperature distributions. This investigation reveals the fact that the water-particle mixture reduces the rate of heat transfer, significantly.
Two-dimensional Rarefaction Waves in the High-speed Two-phase Flow
Nakagawa, Masafumi; Harada, Atsushi
Two-phase flow nozzles are used in the total flow system for geothermal power plants and in the ejector of the refrigerant cycle, etc. One of the most important functions of a two-phase flow nozzle is to convert the thermal energy to the kinetic energy of the two-phase flow. The kinetic energy of the two-phase flow exhausted from a nozzle is available for all applications of this type. There exist the shock waves or rarefaction waves at the outlet of a supersonic nozzle in the case of non-best fitting expansion conditions when the operation conditions of the nozzle are widely chosen. The purpose of the present study is to elucidate theoretically the character of the rarefaction waves at the outlet of the supersonic two-phase flow nozzle. Two-dimensional basic equations for the compressible two-phase flow are introduced considering the inter-phase momentum transfer. Sound velocities are obtained from these equations by using monochromatic wave approximation. Those depend on the relaxation time that determines the momentum transfer. The two-phase flow with large relaxation times has a frozen sound velocity, and with small one has an equilibrium sound velocity. Rarefaction waves which occurred behind the two-phase flow nozzle are calculated by the CIP method. Although the frozen Mach number, below one, controls these basic equations, the rarefaction waves appeared for small relaxation time. The Mach line behind which the expansion starts depends on the inlet velocity and the relaxation time. Those relationships are shown in this paper. The pressure expansion curves are only a function of the revolution angle around the corner of the nozzle outlet for the relaxation time less than 0.1. For the larger relaxation time, the pressure decays because of internal friction caused by inter phase momentum transfer, and the expansion curves are a function of not only the angle but also the flow direction. The calculated expansion curves are compared with the experimental ones
Conceptual design of two-phase fluid mechanics and heat transfer facility for spacelab
North, B. F.; Hill, M. E.
1980-01-01
Five specific experiments were analyzed to provide definition of experiments designed to evaluate two phase fluid behavior in low gravity. The conceptual design represents a fluid mechanics and heat transfer facility for a double rack in Spacelab. The five experiments are two phase flow patterns and pressure drop, flow boiling, liquid reorientation, and interface bubble dynamics. Hardware was sized, instrumentation and data recording requirements defined, and the five experiments were installed as an integrated experimental package. Applicable available hardware was selected in the experiment design and total experiment program costs were defined.
On the peculiarities of LDA method in two-phase flows with high concentrations of particles
Poplavski, S. V.; Boiko, V. M.; Nesterov, A. U.
2016-10-01
Popular applications of laser Doppler anemometry (LDA) in gas dynamics are reviewed. It is shown that the most popular method cannot be used in supersonic flows and two-phase flows with high concentrations of particles. A new approach to implementation of the known LDA method based on direct spectral analysis, which offers better prospects for such problems, is presented. It is demonstrated that the method is suitable for gas-liquid jets. Owing to the progress in laser engineering, digital recording of spectra, and computer processing of data, the method is implemented at a higher technical level and provides new prospects of diagnostics of high-velocity dense two-phase flows.
Institute of Scientific and Technical Information of China (English)
吴波; 汪西力; 徐海良
2015-01-01
Based on RNGk-ε turbulence model and sliding grid technique, solid−liquid two-phase three-dimensional (3-D) unsteady turbulence of full passage in slurry pump was simulated by means of Fluent software. The effects of unsteady flow characteristics on solid−liquid two-phase flow and pump performance were researched under design condition. The results show that clocking effect has a significant influence on the flow in pump, and the fluctuation of flow velocity and pressure is obvious, particularly near the volute tongue, at the position of small sections of volute and within diffuser. Clocking effect has a more influence on liquid-phase than on solid-phase, and the wake-jet structure of relative velocity of solid-phase is less obvious than liquid-phase near the volute tongue and the impeller passage outlet. The fluctuation of relative velocity of solid-phase flow is 7.6% smaller than liquid-phase flow at the impeller outlet on circular path. Head and radial forces of the impeller are 8.1% and 85.7% of fluctuation, respectively. The results provide a theoretical basis for further research for turbulence, improving efficient, reducing the hydraulic losses and wear. Finally, field tests were carried out to verify the operation and wear of slurry pump.
Baniamerian, Ali; Bashiri, Mahdi; Zabihi, Fahime
2017-04-01
Cross-docking is a new warehousing policy in logistics which is widely used all over the world and attracts many researchers attention to study about in last decade. In the literature, economic aspects has been often studied, while one of the most significant factors for being successful in the competitive global market is improving quality of customer servicing and focusing on customer satisfaction. In this paper, we introduce a vehicle routing and scheduling problem with cross-docking and time windows in a three-echelon supply chain that considers customer satisfaction. A set of homogeneous vehicles collect products from suppliers and after consolidation process in the cross-dock, immediately deliver them to customers. A mixed integer linear programming model is presented for this problem to minimize transportation cost and early/tardy deliveries with scheduling of inbound and outbound vehicles to increase customer satisfaction. A two phase genetic algorithm (GA) is developed for the problem. For investigating the performance of the algorithm, it was compared with exact and lower bound solutions in small and large-size instances, respectively. Results show that there are at least 86.6% customer satisfaction by the proposed method, whereas customer satisfaction in the classical model is at most 33.3%. Numerical examples results show that the proposed two phase algorithm could achieve optimal solutions in small-size instances. Also in large-size instances, the proposed two phase algorithm could achieve better solutions with less gap from the lower bound in less computational time in comparison with the classic GA.
Comparison of two-phase and three-phase methanol synthesis processes
van de Graaf, G.H; Beenackers, A.A C M
1996-01-01
A comparison is made between the ICI (two-phase) methanol synthesis process and a three-phase slurry process based on a multi-stage agitated reactor. The process calculations are based on a complete reactor system consisting of the reactor itself, a recycling system and a gas-liquid separator. The b
Pressure Buildup Analysis for Two-Phase Geothermal Wells: Application to the Baca Geothermal Field
Riney, T. D.; Garg, S. K.
1985-03-01
The recently published pressure transient analysis methods for two-phase geothermal wells are employed to analyze the pressure buildup data for several wells located in the Redondo Creek area of the Baca geothermal field in New Mexico. The downhole drilling information and pressure/temperature surveys are first interpreted to locate zones at which fluid enters the well bore from the formation and to estimate the initial reservoir temperature and pressure in these zones. All of the Baca wells considered here induced flashing in the formation upon production. Interpretation of the buildup data for each well considers well bore effects (e.g., phase change in the well bore fluid and location of the pressure sensor with respect to the permeable horizon) and the carbon dioxide content of the fluid and its effects on the phase behavior of the reservoir fluids and differentiates between the single- and two-phase portions of the pressure buildup data. Different straight-line approximations to the two portions (i.e., single- and two-phase) of the data on the Homer plot are used to obtain corresponding estimates for the single- and two-phase mobilities. Estimates for the formation permeability-thickness (kH) product are also given.
Effects of Macroparticle Sizes on Two-phase Mixture Discharge Under DC Voltage
Institute of Scientific and Technical Information of China (English)
YAO Wenjun; HE Zhenghao; DENG Heming; WANG Guoli; ZHANG Man; MA Jun; LI Jin; YE Qizheng; HU Hui
2012-01-01
The discharge laws of the two-phase mixtures are of significance to the lightning protection and external insulation of HV transmission lines under the influence of severe climatic conditions. The initiation and propagation of discharge and its influence factors are the fundamental problems to be studied.
Institute of Scientific and Technical Information of China (English)
袁益让
2002-01-01
For compressible two-phase displacement problem, a kind of upwind operator splitting finite difference schemes is put forward and make use of operator splitting, of calculus of variations, multiplicative commutation rule of difference operators, decomposition of high order difference operators and prior estimates are adopted. Optimal order estinates in L2 norm are derived to determine the error in the approximate solution.
Vincent, Charles C.J.; Kok, Jacobus B.W.
1992-01-01
The two-phase closed loop thermosyphon is investigated with emphasis on the overall performance in transient operation. The control volume approach is the base of a global analysis describing the motion of vapor and liquid phases of the thermosyphon system in one-dimensional equations. Interfacial s
Affinity partitioning of human antibodies in aqueous two-phase systems
Rosa, P. A. J.; Azevedo, A. M.; Ferreira, I. F.; de Vries, J.; Korporaal, R.; Verhoef, H. J.; Visser, T. J.; Aires-Barros, M. R.
2007-01-01
The partitioning of human immunoglobulin (IgG) in a polymer-polymer and polymer-salt aqueous two-phase system (ATPS) in the presence of several functionalised polyethylene glycols (PEGs) was studied. As a first approach, the partition studies were performed with pure IgG using systems in which the t
Measurements of solids concentration and axial solids velocity in gas-solid two-phase flows.
Nieuwland, J.J.; Meijer, R.; Kuipers, J.A.M.; Swaaij, van W.P.M.
1996-01-01
Several techniques reported in the literature for measuring solids concentration and solids velocity in (dense) gas-solid two-phase flow have been briefly reviewed. An optical measuring system, based on detection of light reflected by the suspended particles, has been developed to measure local soli
A Dual-Stage Two-Phase Model of Selective Attention
Hubner, Ronald; Steinhauser, Marco; Lehle, Carola
2010-01-01
The dual-stage two-phase (DSTP) model is introduced as a formal and general model of selective attention that includes both an early and a late stage of stimulus selection. Whereas at the early stage information is selected by perceptual filters whose selectivity is relatively limited, at the late stage stimuli are selected more efficiently on a…
A FINITE ELEMENT COLLOCATION METHOD FOR TWO-PHASE INCOMPRESSIBLE IMMISCIBLE PROBLEMS
Institute of Scientific and Technical Information of China (English)
Ma Ning
2007-01-01
Two-phase, incompressible, immiscible flow in porous media is governed by a coupled system of nonlinear partial differential equations. The pressure equation is elliptic,whereas the concentration equation is parabolic, and both are treated by the collocation scheme. Existence and uniqueness of solutions of the algorithm are proved. A optimal convergence analysis is given for the method.
Two-phase (bio)catalytic reactions in a table-top centrifugal contact separator
Kraai, Gerard N.; Zwol, Floris van; Schuur, Boelo; Heeres, Hero J.; Vries, Johannes G. de
2008-01-01
A new spin on catalysis: A table-top centrifugal contact separator allows for fast continuous two-phase reactions to be performed by intimately mixing two immiscible phases and then separating them. Such a device has been used to produce biodiesel from sunflower oil and MeOH/NaOMe. A lipase-catalyze
Energy Technology Data Exchange (ETDEWEB)
Kang, Han-Ok; Han, Hun Sik; Kim, Young-In; Kim, Keung Koo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2015-05-15
Reduction of installation space for steam generators can lead to much smaller reactor vessel with resultant decrease of overall manufacturing cost for the components. A PCHE(Printed Circuit Heat Exchanger) is one of the compact types of heat exchangers available as an alternative to conventional shell and tube heat exchangers. Its name is derived from the procedure used to manufacture the flat metal plates that form the core of the heat exchanger, which is done by chemical milling. These plates are then stacked and diffusion bonded, converting the plates into a solid metal block containing precisely engineered fluid flow passages. PCSG(Printed Circuit Steam Generator) is a potential candidate to be applied to the integral reactor with its compactness and mechanical robustness. For the introduction of new steam generator, design requirement for the two-phase flow instability should be considered. This paper describes two-phase flow instability characteristics of PCSG for the low pressure condition. PCSG is a potential candidate to be applied to the integral reactor with its compactness and mechanical robustness. Interconnecting flow path was developed to mitigate the two-phase flow instability in the cold side. The flow characteristics of two-phase flow instability at the PCSG is examined experimentally in this study.
Comparison of two-phase and three-phase methanol synthesis processes
van de Graaf, G.H; Beenackers, A.A C M
1996-01-01
A comparison is made between the ICI (two-phase) methanol synthesis process and a three-phase slurry process based on a multi-stage agitated reactor. The process calculations are based on a complete reactor system consisting of the reactor itself, a recycling system and a gas-liquid separator. The
Effects of gravity and inlet location on a two-phase countercurrent imbibition in porous media
El-Amin, Mohamed
2012-01-01
We introduce a numerical investigation of the effect of gravity on the problem of two-phase countercurrent imbibition in porous media. We consider three cases of inlet location, namely, from, side, top, and bottom. A 2D rectangular domain is considered for numerical simulation. The results indicate that gravity has a significant effect depending on open-boundary location.
A Chebyshev collocation method for solving two-phase flow stability problems
Boomkamp, P.A.M.; Boersma, B.J.; Miesen, R.H.M.; Beijnon, G.V.
1997-01-01
This paper describes a Chebyshev collocation method for solving the eigenvalue problem that governs the stability of parallel two-phase flow. The method is based on the expansion of the eigenfunctions in terms of Chebyshev polynomials, point collocation, and the subsequent solution of the resulting
Lamb's integral formulas of two-phase saturated medium for soil dynamic with drainage
Institute of Scientific and Technical Information of China (English)
Bo-yang DING; Gai-hong DANG; Jin-hua YUAN
2010-01-01
When dynamic force is applied to a saturated porous soil,drainage is common.In this paper,the saturated porous soil with a two-phase saturated medium is simulated,and Lamb's integral formulas with drainage and stress formulas for a two-phase saturated medium are given based on Biot's equation and Betti's theorem(the reciprocal theorem).According to the basic solution to Biot's equation,Green's function Gij and three terms of Green's function G4i,Gi4,and G44 of a two-phase saturated medium subject to a concentrated force on a spherical coordinate are presented.The displacement field with drainage,the magnitude of drainage,and the pore pressure of the center explosion source are obtained in computation.The results of the classical Sharpe's solutions and the solutions of the two-phase saturated medium that decays to a single-phase medium are compared.Good agreement is observed.
Approaches to myosin modelling in a two-phase flow model for cell motility
Kimpton, L. S.; Whiteley, J. P.; Waters, S. L.; Oliver, J. M.
2016-04-01
A wide range of biological processes rely on the ability of cells to move through their environment. Mathematical models have been developed to improve our understanding of how cells achieve motion. Here we develop models that explicitly track the cell's distribution of myosin within a two-phase flow framework. Myosin is a small motor protein which is important for contracting the cell's actin cytoskeleton and enabling cell motion. The two phases represent the actin network and the cytosol in the cell. We start from a fairly general description of myosin kinetics, advection and diffusion in the two-phase flow framework, then identify a number of sub-limits of the model that may be relevant in practice, two of which we investigate further via linear stability analyses and numerical simulations. We demonstrate that myosin-driven contraction of the actin network destabilizes a stationary steady state leading to cell motion, but that rapid diffusion of myosin and rapid unbinding of myosin from the actin network are stabilizing. We use numerical simulation to investigate travelling-wave solutions relevant to a steadily gliding cell and we consider a reduction of the model in which the cell adheres strongly to the substrate on which it is crawling. This work demonstrates that a number of existing models for the effect of myosin on cell motility can be understood as different sub-limits of our two-phase flow model.
Theoretical aspects of electrical power generation from two-phase flow streaming potentials
Sherwood, J.D.; Xie, Yanbo; van den Berg, Albert; Eijkel, Jan C.T.
A theoretical analysis of the generation of electrical streaming currents and electrical power by two-phase flow in a rectangular capillary is presented. The injection of a second, non-conducting fluid phase tends to increase the internal electrical resistance of the electrical generator, thereby
Effects of Particles Collision on Separating Gas–Particle Two-Phase Turbulent Flows
Sihao, L. V.
2013-10-10
A second-order moment two-phase turbulence model incorporating a particle temperature model based on the kinetic theory of granular flow is applied to investigate the effects of particles collision on separating gas–particle two-phase turbulent flows. In this model, the anisotropy of gas and solid phase two-phase Reynolds stresses and their correlation of velocity fluctuation are fully considered using a presented Reynolds stress model and the transport equation of two-phase stress correlation. Experimental measurements (Xu and Zhou in ASME-FED Summer Meeting, San Francisco, Paper FEDSM99-7909, 1999) are used to validate this model, source codes and prediction results. It showed that the particles collision leads to decrease in the intensity of gas and particle vortices and takes a larger effect on particle turbulent fluctuations. The time-averaged velocity, the fluctuation velocity of gas and particle phase considering particles colli-sion are in good agreement with experimental measurements. Particle kinetic energy is always smaller than gas phase due to energy dissipation from particle collision. Moreover, axial– axial and radial–radial fluctuation velocity correlations have stronger anisotropic behaviors. © King Fahd University of Petroleum and Minerals 2013
Two-Phase Flow in Rotating Hele-Shaw Cells with Coriolis Effects
Escher, Joachim; Walker, Christoph
2011-01-01
The free boundary problem of a two phase flow in a rotating Hele-Shaw cell with Coriolis effects is studied. Existence and uniqueness of solutions near spheres is established, and the asymptotic stability and instability of the trivial solution is characterized in dependence on the fluid densities.
Liquid-liquid extraction of enzymes by affinity aqueous two-phase systems
Directory of Open Access Journals (Sweden)
Xu Yan
2003-12-01
Full Text Available From analytical to commercial scale, aqueous two-phase systems have their application in the purification, characterization and study of biomaterials. In order to improve the selectivity of the systems, the biospecific affinity ligands were introduced. In the affinity partitioning aqueous two-phase system, have many enzymes been purified. This review discusses the partitioning of some enzymes in the affinity aqueous two-phase systems in regard to the different ligands, including reactive dyes, metal ions and other ligands. Some integration of aqueous two-phase system with other techniques for more effective purification of enzymes are also presented.Tanto em escala de laboratório como industrial, os sistemas de duas fases aquosas podem ser utilizados para a purificação, caracterização e estudos de biomateriais. Para aumentar a seletividade desse sistema, ligantes de afinidade bioespecíficos podem ser utilizados. No sistema de duas fases aquosas por afinidade, muitas enzimas podem ser purificadas. Neste artigo de revisão, a partição de algumas enzimas por esse tipo de afinidade, utilizando diferentes ligantes como corantes e íons metálicos, são discutidas. Além disso, a integração desse sistema de duas fases aquosas com outras técnicas de purificação estão sendo apresentados, com o objetivo mostrar a melhoria da eficiência do processo.
Two-phase (bio)catalytic reactions in a table-top centrifugal contact separator
Kraai, Gerard N.; Zwol, Floris van; Schuur, Boelo; Heeres, Hero J.; Vries, Johannes G. de
2008-01-01
A new spin on catalysis: A table-top centrifugal contact separator allows for fast continuous two-phase reactions to be performed by intimately mixing two immiscible phases and then separating them. Such a device has been used to produce biodiesel from sunflower oil and MeOH/NaOMe. A lipase-catalyze
Kraai, Gerard N.; Schuur, Boelo; van Zwol, Floris; Haak, Robert M.; Minnaard, Adriaan J.; Feringa, Ben L.; Heeres, Hero J.; de Vries, Johannes G.; Prunier, ML
2009-01-01
Production of fine chemicals is mostly performed in batch reactors. Use of continuous processes has many advantages which may reduce the cost of production. We have developed the use of centrifugal contact separators (CCSs) for continuous two-phase catalytic reactions. This equipment has previously
Numerical Simulation of Hydrodynamic Wave Loading by a Compressible Two-Phase Model
Wemmenhove, R.; Loots, G.E.; Veldman, A.E.P.
2006-01-01
The numerical simulation of hydrodynamic wave loading on different types of offshore structures is important to predict forces on and water motion around these structures. This paper presents a numerical study of the effects of two-phase flow on an offshore structure subject to breaking waves. The
Lattice-Boltzmann-based two-phase thermal model for simulating phase change
Kamali, M.R.; Gillissen, J.J.J.; Van den Akker, H.E.A.; Sundaresan, S.
2013-01-01
A lattice Boltzmann (LB) method is presented for solving the energy conservation equation in two phases when the phase change effects are included in the model. This approach employs multiple distribution functions, one for a pseudotemperature scalar variable and the rest for the various species. A
Nonequilibrium capillarity effects in two-phase flow through porous media at different scales
Bottero, S.; Hassanizadeh, S.M.; Kleingeld, P.J.; Heimovaara, T.J.
2011-01-01
A series of primary drainage experiments was carried out in order to investigate nonequilibrium capillarity effects in two-phase flow through porous media. Experiments were performed with tetrachloroethylene (PCE) and water as immiscible fluids in a sand column 21 cm long. Four drainage experiments
Trapping and hysteresis in two-phase flow in porous media: A pore-network study
Joekar-Niasar, V.|info:eu-repo/dai/nl/30484229X; Doster, F.; Armstrong, R.T.; Wildenschild, D.; Celia, M.A.
2013-01-01
Several models for two-phase ﬂow in porous media identify trapping and connectivityof ﬂuids as an important contribution to macroscale hysteresis. This is especially true forhysteresis in relative permeabilities. The trapping models propose trajectories from theinitial saturation to the end saturati
Jafari, Davoud; Di Marco, Paolo; Filippeschi, Sauro; Franco, Alessandro
2017-01-01
Abstract Two-phase closed thermosyphons (TPCTs) are excellent thermal transfer devices that their integration into heat exchangers has been shown a strong potential for energy savings. The scope of this study is an experimental evaluation of the evaporation and condensation heat transfer of a TPCT
Effects of a two-phase oil-water mouthwash on halitosis.
Yaegaki, K; Sanada, K
1992-01-01
Many oral microorganisms possess hydrophobic outer surfaces. A two-phase, oil-water mouthwash has, therefore, recently been developed to remove such oral microorganisms. The oil phase consists of olive oil and other essential oils. The aqueous phase includes cetylpyridinium chloride, which is a disinfectant that promotes the adhesion of microorganisms to oil droplets. This study determined the effects of this mouthwash on the production of volatile sulfide in vivo and in vitro. Neither rinsing with water nor brushing teeth decreased the concentration of sulfide in mouth air at 3.5 h after treatment. A reduction of only 30% of sulfide was observed when a commercial mouthwash was used. However, this study demonstrated that use of the two-phase mouthwash led to approximately 80% reduction of sulfide. Furthermore, volatile sulfide and 2-ketobutyrate productions from methionine in a saliva putrefaction system were completely inhibited by the two-phase mouthwash; and consumption of methionine was decreased by 65 percent. It is concluded that the two-phase mouthwash strongly inhibits the production of volatile sulfide.
Gravity Effect on Two-Phase Immiscible Flows in Communicating Layered Reservoirs
DEFF Research Database (Denmark)
Zhang, Xuan; Shapiro, Alexander; Stenby, Erling Halfdan
2012-01-01
An upscaling method is developed for two-phase immiscible incompressible flows in layered reservoirs with good communication between the layers. It takes the effect of gravity into consideration. Waterflooding of petroleum reservoirs is used as a basic example for application of this method...... for gravity segregation. The effects of gravity are analyzed....
Generating a Two-Phase Lesson for Guiding Beginners to Learn Basic Dance Movements
Yang, Yang; Leung, Howard; Yue, Lihua; Deng, Liqun
2013-01-01
In this paper, an automated lesson generation system for guiding beginners to learn basic dance movements is proposed. It analyzes the dance to generate a two-phase lesson which can provide a suitable cognitive load thus offering an efficient learning experience. In the first phase, the dance is divided into small pieces which are patterns, and…
Forced Two-Phase Helium Cooling Scheme for the Mu2e Transport Solenoid
Energy Technology Data Exchange (ETDEWEB)
Tatkowski, G. [Fermilab; Cheban, S. [Fermilab; Dhanaraj, N. [Fermilab; Evbota, D. [Fermilab; Lopes, M. [Fermilab; Nicol, T. [Fermilab; Sanders, R. [Fermilab; Schmitt, R. [Fermilab; Voirin, E. [Fermilab
2015-01-01
The Mu2e Transport Solenoid (TS) is an S-shaped magnet formed by two separate but similar magnets, TS-u and TS-d. Each magnet is quarter-toroid shaped with a centerline radius of approximately 3 m utilizing a helium cooling loop consisting of 25 to 27 horizontal-axis rings connected in series. This cooling loop configuration has been deemed adequate for cooling via forced single phase liquid helium; however it presents major challenges to forced two-phase flow such as “garden hose” pressure drop, concerns of flow separation from tube walls, difficulty of calculation, etc. Even with these disadvantages, forced two-phase flow has certain inherent advantages which make it a more attractive option than forced single phase flow. It is for this reason that the use of forced two-phase flow was studied for the TS magnets. This paper will describe the analysis using helium-specific pressure drop correlations, conservative engineering approach, helium properties calculated and updated at over fifty points, and how the results compared with those in literature. Based on the findings, the use of forced-two phase helium is determined to be feasible for steady-state cooling of the TS solenoids
THE LINEAR HOMOGENEOUS FLOW MODEL FOR TWO-PHASE FLOW INSTABILITY IN BOILING CHANNELS
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
This paper presents liner homogeneous model describing two-phase flow instability. Dimensionless parameter η was derived by using the linear homogeneous model. Using parameter η the stability of a system could be easily judged. The calculated results agree with the experimental data well.
Extraction of peptide tagged cutinase in detergent-based aqueous two-phase systems
Rodenbrock, A.; Selber, K.; Egmond, M.R.; Kula, M.-R.
2010-01-01
Detergent-based aqueous two-phase systems have the advantage to require only one auxiliary chemical to induce phase separation above the cloud point. In a systematic study the efficiency of tryptophan-rich peptide tags was investigated to enhance the partitioning of an enzyme to the detergent-rich p
Effects of Gravity and Inlet Location on a Two-Phase Countercurrent Imbibition in Porous Media
Directory of Open Access Journals (Sweden)
M. F. El-Amin
2012-01-01
Full Text Available We introduce a numerical investigation of the effect of gravity on the problem of two-phase countercurrent imbibition in porous media. We consider three cases of inlet location, namely, from, side, top, and bottom. A 2D rectangular domain is considered for numerical simulation. The results indicate that gravity has a significant effect depending on open-boundary location.
Model description of bactrial 3-methylcatechol production in one- and two-phase systems
Husken, L.E.; Hoogakker, J.; Bont, de J.A.M.; Tramper, J.; Beeftink, H.H.
2003-01-01
Pseudomonas putida MC2 produces 3-methylcatechol from toluene in aqueous medium. A second phase of 1-octanol may improve total product accumulation. To optimise the design of such a biphasic process, a process model was developed, both for one- and two-phase applications. The insights obtained by th
Multi-scale symbolic time reverse analysis of gas-liquid two-phase flow structures
Wang, Hongmei; Zhai, Lusheng; Jin, Ningde; Wang, Youchen
Gas-liquid two-phase flows are widely encountered in production processes of petroleum and chemical industry. Understanding the dynamic characteristics of multi-scale gas-liquid two-phase flow structures is of great significance for the optimization of production process and the measurement of flow parameters. In this paper, we propose a method of multi-scale symbolic time reverse (MSTR) analysis for gas-liquid two-phase flows. First, through extracting four time reverse asymmetry measures (TRAMs), i.e. Euclidean distance, difference entropy, percentage of constant words and percentage of reversible words, the time reverse asymmetry (TRA) behaviors of typical nonlinear systems are investigated from the perspective of multi-scale analysis, and the results show that the TRAMs are sensitive to the changing of dynamic characteristics underlying the complex nonlinear systems. Then, the MSTR analysis is used to study the conductance signals from gas-liquid two-phase flows. It is found that the multi-scale TRA analysis can effectively reveal the multi-scale structure characteristics and nonlinear evolution properties of the flow structures.
Milking microalga Dunaliella salina for Beta-carotene production in two-phase bioreactors
Hejazi, M.; Holwerda, E.; Wijffels, R.H.
2004-01-01
A new method was developed for production of beta-carotene from Dunaliella salina. Cells were grown in low light intensity and then transferred to a production bioreactor illuminated at a higher light intensity. It was a two-phase bioreactor consisting of an aqueous and a biocompatible organic phase
Lattice-Boltzmann-based two-phase thermal model for simulating phase change
Kamali, M.R.; Gillissen, J.J.J.; Van den Akker, H.E.A.; Sundaresan, S.
2013-01-01
A lattice Boltzmann (LB) method is presented for solving the energy conservation equation in two phases when the phase change effects are included in the model. This approach employs multiple distribution functions, one for a pseudotemperature scalar variable and the rest for the various species. A
Generating a Two-Phase Lesson for Guiding Beginners to Learn Basic Dance Movements
Yang, Yang; Leung, Howard; Yue, Lihua; Deng, Liqun
2013-01-01
In this paper, an automated lesson generation system for guiding beginners to learn basic dance movements is proposed. It analyzes the dance to generate a two-phase lesson which can provide a suitable cognitive load thus offering an efficient learning experience. In the first phase, the dance is divided into small pieces which are patterns, and…
Well logging interpretation of production profile in horizontal oil-water two phase flow pipes
Zhai, Lu-Sheng; Jin, Ning-De; Gao, Zhong-Ke; Zheng, Xi-Ke
2012-03-01
Due to the complicated distribution of local velocity and local phase hold up along the radial direction of pipe in horizontal oil-water two phase flow, it is difficult to measure the total flow rate and phase volume fraction. In this study, we carried out dynamic experiment in horizontal oil-water two phases flow simulation well by using combination measurement system including turbine flowmeter with petal type concentrating diverter, conductance sensor and flowpassing capacitance sensor. According to the response resolution ability of the conductance and capacitance sensor in different range of total flow rate and water-cut, we use drift flux model and statistical model to predict the partial phase flow rate, respectively. The results indicate that the variable coefficient drift flux model can self-adaptively tone the model parameter according to the oil-water two phase flow characteristic, and the prediction result of partial phase flow rate of oil-water two phase flow is of high accuracy.
23 CFR 636.202 - When are two-phase design-build selection procedures appropriate?
2010-04-01
... 23 Highways 1 2010-04-01 2010-04-01 false When are two-phase design-build selection procedures appropriate? 636.202 Section 636.202 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS DESIGN-BUILD CONTRACTING Selection Procedures, Award Criteria §...
Experimental study on two-phase flow pressure drop in small diameter bends
Directory of Open Access Journals (Sweden)
A.T. Autee
2016-09-01
Full Text Available Measurement of two-phase flow pressure drop and its prediction across curved tubes and bends is important for the enhancement of the performance and safety of the heat exchangers and flow transmitting devices. The comparative study of some of the available two-phase pressure drop correlations reveals that the predicted values of pressure drops by these leading methods may differ by large. The applicability of these correlations to the small diameter tubes of range 4.0–8.0 mm and different bend angles of the range 90–180° is not fully established. The basic objective of the present experimental investigation is to generate the experimental data to develop the unified correlation applicable for the small diameter tubes of range 4.0–8.0 mm and different bend angles of the range 90–180°. Hence, experimental facility was developed to conduct the experiments to generate the data and to assess the predictive capability of some of the available two-phase pressure drop correlations. It was observed that the correlations considered for comparisons were unable to satisfactorily predict the measured experimental data within the ±50% error bands. A new correlation is developed in terms of curvature multiplier to the straight tube two-phase pressure drop. The correlation is validated with the present measured experimental data. The statistical analysis suggests that correlation shows satisfactory results.
A Stable Parametric Finite Element Discretization of Two-Phase Navier--Stokes Flow
Barrett, John W; Nürnberg, Robert
2013-01-01
We present a parametric finite element approximation of two-phase flow. This free boundary problem is given by the Navier--Stokes equations in the two phases, which are coupled via jump conditions across the interface. Using a novel variational formulation for the interface evolution gives rise to a natural discretization of the mean curvature of the interface. The parametric finite element approximation of the evolving interface is then coupled to a standard finite element approximation of the two-phase Navier--Stokes equations in the bulk. Here enriching the pressure approximation space with the help of an XFEM function ensures good volume conservation properties for the two phase regions. In addition, the mesh quality of the parametric approximation of the interface in general does not deteriorate over time, and an equidistribution property can be shown for a semidiscrete continuous-in-time variant of our scheme in two space dimensions. Moreover, our finite element approximation can be shown to be uncondit...
A two phase algorithm for solving a class of hard satissfiability problems
J.P. Warners; H. van Maaren
1998-01-01
textabstractThe DIMACS suite of satisfiability (SAT) benchmarks contains a set of instances that are very hard for existing algorithms. These instances arise from learning the parity function on 32 bits. In this paper we develop a two phase algorithm that is capable of solving these instances. In
Two-phase flow-induced forces on bends in small scale tubes
Cargnelutti, M.F.; Belfroid, S.P.C.; Schiferli, W.
2010-01-01
Two-phase flow occurs in many situations in industry. Under certain circumstances, it can be a source of flow-induced vibrations. The forces generated can be sufficiently large to affect the performance or efficiency of an industrial device. In the worst-case scenario, the mechanical forces that ari
Implementation of the interfacial area transport equation in trace for boiling two-phase flows
Bernard, Matthew S.
Correctly predicting the interfacial area concentration (a i) is vital to the overall accuracy of the two-fluid model because ai describes the amount of surface area that exists between the two-phases, and is therefore directly related to interfacial mass, momentum and energy transfer. The conventional method for specifying ai in the two-fluid model is through flow regime-based empirical correlations coupled with regime transition criteria. However, a more physically consistent approach to predicting ai is through the interfacial area transport equation (IATE), which can address the deficiencies of the flow regime-based approach. Some previous studies have been performed to demonstrate the feasibility of IATE in developmental versions of the nuclear reactor systems analysis code, TRACE. However, a full TRACE version capable of predicting boiling two-phase flows with the IATE has not been established. Therefore, the current work develops a version of TRACE that is capable of predicting boiling two-phase flows using the IATE. The development is carried out in stages. First, a version of TRACE which employs the two-group IATE for adiabatic, vertical upward, air-water conditions is developed. An in-depth assessment on the existing experimental database is performed to select reliable experimental data for code assessment. Then, the implementation is assessed against the qualified air-water two-phase flow experimental data. Good agreement is observed between the experimental data for ai and the TRACE code with an average error of +/-9% for all conditions. Following the initial development, one-group IATE models for vertical downward and horizontal two-phase flows are implemented and assessed against qualified data. Finally, IATE models capable of predicting subcooled boiling two-phase flows are implemented. An assessment of the models shows that TRACE is capable of generating ai in subcooled boiling two-phase flows with the IATE and that heat transfer effects dominate
Solid Waste Program Fiscal Year 1996 Multi-Year Program Plan WBS 1.2.1, Revision 1
Energy Technology Data Exchange (ETDEWEB)
NONE
1995-09-01
This document contains the Fiscal Year 1996 Multi-Year Program Plan for the Solid Waste Program at the Hanford Reservation in Richland, Washington. The Solid Waste Program treats, stores, and disposes of a wide variety of solid wastes consisting of radioactive, nonradioactive and hazardous material types. Solid waste types are typically classified as transuranic waste, low-level radioactive waste, low-level mixed waste, and non-radioactive hazardous waste. This report describes the mission, goals and program strategies for the Solid Waste Program for fiscal year 1996 and beyond.
Development of an ex-vessel corium debris bed with two-phase natural convection in a flooded cavity
Energy Technology Data Exchange (ETDEWEB)
Kim, Eunho; Lee, Mooneon; Park, Hyun Sun, E-mail: hejsunny@postech.ac.kr; Moriyama, Kiyofumi; Park, Jin Ho
2016-03-15
Highlights: • For ex-vessel severe accidents in LWRs with wet-cavity strategy, development of debris bed with two-phase natural convection flow due to thermal characteristics of prototypic corium particles was investigated experimentally by using simulant particles and local air bubble control system. • Based on the experimental results of this study, an analytical model was established to describe the spreading of the debris bed in terms of two-phase flow and the debris injection parameters. • This model was then used to analyze the formation of debris beds at the reactor scale, and a sensitivity analysis was carried out based on key accident parameters. - Abstract: During severe accidents of light water reactors (LWRs), the coolability of relocated corium from the reactor vessel is a significant safety issue and a threat to the integrity of containment. With a flooded cavity, a porous debris bed is expected to develop on the bottom of the pool due to breakup and fragmentation of the melt jet. As part of the coolability assessment under accident conditions, the geometrical configuration of the debris bed is important. The Debris Bed Research Apparatus for Validation of the Bubble-Induced Natural Convection Effect Issue (DAVINCI) experimental apparatus facility was constructed to investigate the formation of debris beds under the influence of a two-phase flow induced by steam generation due to the decay heat of the debris bed. Using this system, five kilograms of stainless steel simulant debris were injected from the top of the water level, while air bubbles simulating the vapor flow were injected from the bottom of the particle catcher plate. The airflow rate was determined based on the quantity of settled debris, which will form a heat source due to the decay of corium. The radial distribution of the settled debris was examined using a ‘gap–tooth’ approach. Based on the experimental results of this study, an analytical model was established to
Comparison of Experimental and Numerical Two-Phase Flows in a Porous Micro-Model
Directory of Open Access Journals (Sweden)
Dustin Crandall
2009-12-01
Full Text Available Characterizing two-phase flow in porous media is important to provide estimates of sweep efficiency in enhanced oil recovery and storage estimates in potential geological CO2 sequestration repositories. To further the current understanding of two-phase flow in porous media a micro-model of interconnected channels was designed and fabricated using stereolithography to experimentally study gas-liquid flows. This flowcell was created with a wide variability of throat dimensions to represent naturally occurring porous media. Low flow rate experiments of immiscible two-phase drainage were performed within this cell. Additionally, a computational model for analyzing two-phase flows in the same flowcell was developed and used to simulate conditions not possible with our laboratory settings. The computational model was first tested for the identical conditions used in the experimental studies, and was shown to be in good agreement with the experimentally determined fractal dimension of the invading gas structure, time until breakthrough, and fluid saturation. The numerical model was then used to study two-phase air-water flows in flowcells with the same geometry and different gas-liquid-solid contact angles. The percent saturation of air and the motion of the fluids through the cell were found to vary with changes in these parameters. Finally, to simulate flows expected during geologic carbon sequestration, the fluid properties and interface conditions were set to model the flow of CO2 into a brine-saturated porous medium at representative subsurface conditions. The CO2 flows were shown to have larger gas saturations than the previous air into water studies. Thus the accuracy of the computational model was supported by the flowcell experiments, and the computational model extended the laboratory results to conditions not possible with the apparatus used in the experiments.
Two-phase flow and boiling heat transfer in two vertical narrow annuli
Energy Technology Data Exchange (ETDEWEB)
Peng Changhong [Department of Nuclear and Thermal Power Engineering, Xi' an Jiaotong University, Xian 710049 (China)]. E-mail: pxm321@163.com; Guo Yun [Department of Nuclear and Thermal Power Engineering, Xi' an Jiaotong University, Xian 710049 (China); Qiu Suizheng [Department of Nuclear and Thermal Power Engineering, Xi' an Jiaotong University, Xian 710049 (China); Jia Dounan [Department of Nuclear and Thermal Power Engineering, Xi' an Jiaotong University, Xian 710049 (China); Nie Changhua [Nuclear Power Institute of China, Chengdu 610041 (China)
2005-07-01
Experimental study associated with two-phase flow and heat transfer during flow boiling in two vertical narrow annuli has been conducted. The parameters examined were: mass flux from 38.8 to 163.1 kg/m{sup 2} s; heat flux from 4.9 to 50.7 kW/m{sup 2} for inside tube and from 4.2 to 78.8 kW/m{sup 2} for outside tube; equilibrium mass quality from 0.02 to 0.88; system pressure from 1.5 to 6.0 MPa. It was found that the boiling heat transfer was strongly influenced by heat flux, while the effect of mass velocity and mass quality were not very significant. This suggested that the boiling heat transfer was mainly via nucleate boiling. The data were used to develop a new correlation for boiling heat transfer in the narrow annuli. In the two-phase flow study, the comparison with the correlation of Chisholm [Chisholm, D., 1967. A theoretical basis for the Lockhart-Martinelli correlation for two-phase flow. Int. J. Heat Mass Transfer 10, 1767-1778] and Mishima and Hibiki [Mishima, K., Hibiki, T., 1996. Some characteristics of air-water two-phase flow in small diameter vertical tubes. Int. J. Multiphase Flow 22, 703-712] indicated that the existing correlations could not predict the two-phase multiplier in the narrow annuli well. Based on the experimental data, a new correlation was developed.
Robust risk prediction with biomarkers under two-phase stratified cohort design.
Payne, Rebecca; Yang, Ming; Zheng, Yingye; Jensen, Majken K; Cai, Tianxi
2016-12-01
Identification of novel biomarkers for risk prediction is important for disease prevention and optimal treatment selection. However, studies aiming to discover which biomarkers are useful for risk prediction often require the use of stored biological samples from large assembled cohorts, and thus the depletion of a finite and precious resource. To make efficient use of such stored samples, two-phase sampling designs are often adopted as resource-efficient sampling strategies, especially when the outcome of interest is rare. Existing methods for analyzing data from two-phase studies focus primarily on single marker analysis or fitting the Cox regression model to combine information from multiple markers. However, the Cox model may not fit the data well. Under model misspecification, the composite score derived from the Cox model may not perform well in predicting the outcome. Under a general two-phase stratified cohort sampling design, we present a novel approach to combining multiple markers to optimize prediction by fitting a flexible nonparametric transformation model. Using inverse probability weighting to account for the outcome-dependent sampling, we propose to estimate the model parameters by maximizing an objective function which can be interpreted as a weighted C-statistic for survival outcomes. Regardless of model adequacy, the proposed procedure yields a sensible composite risk score for prediction. A major obstacle for making inference under two phase studies is due to the correlation induced by the finite population sampling, which prevents standard inference procedures such as the bootstrap from being used for variance estimation. We propose a resampling procedure to derive valid confidence intervals for the model parameters and the C-statistic accuracy measure. We illustrate the new methods with simulation studies and an analysis of a two-phase study of high-density lipoprotein cholesterol (HDL-C) subtypes for predicting the risk of coronary heart
Investigation of heat transfer and pressure drop of CO(2) two-phase flow in a horizontal minichannel
Wu, J; Haug, F; Franke, C; Bremer, J; Eisel, T; Koettig, T
2011-01-01
An innovative cooling system based on evaporative CO(2) two-phase flow is under investigation for the tracker detectors upgrade at CERN (European Organization for Nuclear Research). The radiation hardness and the excellent thermodynamic properties emphasize carbon dioxide as a cooling agent in the foreseen minichannels. A circular stainless steel tube in horizontal orientation with an inner diameter of 1.42 mm and a length of 0.3 m has been used as a test section to perform the step-wise scanning of the vapor quality in the entire two-phase region. To characterize the heat transfer and the pressure drop depending on the vapor quality in the tube, measurements have been performed by varying the mass flux from 300 to 600 kg/m(2) s, the heat flux from 7.5 to 29.8 kW/m(2) and the saturation temperature from -40 to 0 degrees C (reduced pressures from 0.136 to 0.472). Heat transfer coefficients between 4 kW/m(2) K and 28 kW/m(2) K and pressure gradients up to 75 kPa/m were registered. The measured data was analyzed...
Hydrodynamics and heat transfer of gas-solid two-phase mixtures flowing through packed beds-a review
Institute of Scientific and Technical Information of China (English)
Yulong Ding; Yurong He; Ngoc Thang Cong; Wei Yang; Haisheng Chen
2008-01-01
Flow of a gas-solid two-phase mixture through a packed bed is relevant to a number of industrial processes such as heat recovery and filtration of dusty flue gases,iron making in shaft reactors,gas purification,and sorption enhanced reaction processes.In spite of the industrial relevance,little work has been reported in the literature.The limited amount of research work has mainly addressed the macroscopic hydrodynamics in terms of pressure drop and solids hold-ups at the ambient temperature.Very little is done,until fairly recent,on solids motion at the single particle level,hydrodynamics at elevated temperatures and heat transfer.This paper reviews the recent development in the field including both the hydrodynamics and heat transfer of gas-solid two-phase mixtures flowing through packed beds,which is believed to represent the state-of-the-art in the field.The review is not aimed to be exhaustive but rather focused on our own work carried out over the past few years in the Institute of Particle Science & Engineering at the University of Leeds.And some of our results are compared with that of other groups.
A two-phase solid/fluid model for dense granular flows including dilatancy effects
Mangeney, Anne; Bouchut, Francois; Fernandez-Nieto, Enrique; Koné, El-Hadj; Narbona-Reina, Gladys
2016-04-01
Describing grain/fluid interaction in debris flows models is still an open and challenging issue with key impact on hazard assessment [{Iverson et al.}, 2010]. We present here a two-phase two-thin-layer model for fluidized debris flows that takes into account dilatancy effects. It describes the velocity of both the solid and the fluid phases, the compression/dilatation of the granular media and its interaction with the pore fluid pressure [{Bouchut et al.}, 2016]. The model is derived from a 3D two-phase model proposed by {Jackson} [2000] based on the 4 equations of mass and momentum conservation within the two phases. This system has 5 unknowns: the solid and fluid velocities, the solid and fluid pressures and the solid volume fraction. As a result, an additional equation inside the mixture is necessary to close the system. Surprisingly, this issue is inadequately accounted for in the models that have been developed on the basis of Jackson's work [{Bouchut et al.}, 2015]. In particular, {Pitman and Le} [2005] replaced this closure simply by imposing an extra boundary condition at the surface of the flow. When making a shallow expansion, this condition can be considered as a closure condition. However, the corresponding model cannot account for a dissipative energy balance. We propose here an approach to correctly deal with the thermodynamics of Jackson's model by closing the mixture equations by a weak compressibility relation following {Roux and Radjai} [1998]. This relation implies that the occurrence of dilation or contraction of the granular material in the model depends on whether the solid volume fraction is respectively higher or lower than a critical value. When dilation occurs, the fluid is sucked into the granular material, the pore pressure decreases and the friction force on the granular phase increases. On the contrary, in the case of contraction, the fluid is expelled from the mixture, the pore pressure increases and the friction force diminishes. To
Lingle, Craig S.; Brenner, Anita C.; Zwally, H. Jay; DiMarzio, John P.
1991-01-01
Mean changes in the surface elevation near the west margin of the Greenland ice sheet are measured using Seasat altimetry and altimetry from the Geosat Exact Repeat Mission (ERM). The Seasat data extend from early July through early October 1978. The ERM data extend from winter 1986-87 through fall 1988. Both seasonal and multi-year changes are measured using altimetry referenced to GEM T2 orbits. The possible effects of orbit error are minimized by adjusting the orbits into a common ocean surface. Seasonal mean changes in the surface height are recognizable during the Geosat ERM. The multi-year measurements indicate the surface was lower by 0.4 +/- 0.4 m on average in late summer 1987 than in late summer 1978. The surface was lower by 0.2 +/- 0.5 m on average in late summer 1988 than in late summer 1978. As a control case, the computations art also carried out using altimetry referenced to orbits not adjusted into a common ocean surface.
Taylor, Rachel A; Sherratt, Jonathan A; White, Andrew
2013-12-01
Many natural systems are subject to seasonal environmental change. As a consequence many species exhibit seasonal changes in their life history parameters--such as a peak in the birth rate in spring. It is important to understand how this seasonal forcing affects the population dynamics. The main way in which seasonal models have been studied is through a two dimensional bifurcation approach. We augment this bifurcation approach with extensive simulation in order to understand the potential solution behaviours for a predator-prey system with a seasonally forced prey growth rate. We consider separately how forcing influences the system when the unforced dynamics have either monotonic decay to the coexistence steady state, or oscillatory decay, or stable limit cycles. The range of behaviour the system can exhibit includes multi-year cycles of different periodicities, parameter ranges with coexisting multi-year cycles of the same or different period as well as quasi-periodicity and chaos. We show that the level of oscillation in the unforced system has a large effect on the range of behaviour when the system is seasonally forced. We discuss how the methods could be extended to understand the dynamics of a wide range of ecological and epidemiological systems that are subject to seasonal changes.
Fundamental Studies on Two-Phase Gas-Liquid Flows Through Packed Beds in Microgravity
Balakotaiah, Vemuri; McCready, Mark J.; Motil, Brian J.
2002-01-01
In the typical operation of a packed-bed reactor, gas and liquid flow simultaneously through a fixed bed of solid particles. Depending on the application, the particles can be of various shapes and sizes and provide for intimate contact and high rates of transport between the phases needed to sustain chemical or biological reactions. The packing may also serve as either a catalyst or as a support for growing biological material. NASA has flown two of these packed-bed systems in a microgravity environment with limited or no success. The goal of this research is to develop models (with scale-up capability) needed for the design of the physicochemical equipment to carry out these unit operations in microgravity. New insight will also lead to improvements in normal gravity operations. Our initial experiment was flown using an existing KC-135 two-phase flow rig with a modified test section. The test section is a clear polycarbonate rectangular column with a depth of 2.54 cm, a width of 5.08 cm, and 60 cm long. The column was randomly packed with spherical glass beads by slowly dropping the beads into the bed. Even though care was taken in handling the column after it was filled with packing, the alternating high and low gravity cycles with each parabola created a slightly tighter packed bed than is typically reported for this type. By the usual method of comparing the weight difference of a completely dry column versus a column filled with water, the void fraction was found to be .345 for both sizes of beads used. Five flush mounted differential pressure transducers are spaced at even intervals with the first location 4 cm from the inlet port and the subsequent pressure transducers spaced at 13 cm intervals along the column. Differential pressure data was acquired at 1000 Hz to adequately observe pulse formation and characteristics. Visual images of the flow were recorded using a high-speed SVHS system at 500 frames per second. Over 250 different test conditions were
Zhang, G; Stillinger, F H; Torquato, S
2016-12-28
Disordered hyperuniform many-particle systems have attracted considerable recent attention, since they behave like crystals in the manner in which they suppress large-scale density fluctuations, and yet also resemble statistically isotropic liquids and glasses with no Bragg peaks. One important class of such systems is the classical ground states of "stealthy potentials." The degree of order of such ground states depends on a tuning parameter χ. Previous studies have shown that these ground-state point configurations can be counterintuitively disordered, infinitely degenerate, and endowed with novel physical properties (e.g., negative thermal expansion behavior). In this paper, we focus on the disordered regime (0 two-phase media by circumscribing each point with a possibly overlapping sphere of a common radius a: the "particle" and "void" phases are taken to be the space interior and exterior to the spheres, respectively. The hyperuniformity of such two-phase media depends on the sphere sizes: While it was previously analytically proven that the resulting two-phase media maintain hyperuniformity if spheres do not overlap, here we show numerically that they lose hyperuniformity whenever the spheres overlap. We study certain transport properties of these systems, including the effective diffusion coefficient of point particles diffusing in the void phase as well as static and time-dependent characteristics associated with diffusion-controlled reactions. Besides these effective transport properties, we also investigate several related structural properties, including pore-size functions, quantizer error, an order metric, and percolation thresholds. We show that these transport, geometrical, and topological properties of our two-phase media derived from decorated stealthy ground states are distinctly different from those of equilibrium hard-sphere systems and spatially uncorrelated overlapping spheres. As the extent of short-range order increases, stealthy disordered
2012-01-01
Multi-year insurance has been proposed as a tool to incentivise policy-holders to invest in property-level adaptation. In a world of rising natural catastrophe risks, such autonomous adaptations could have significant benefits for the property owner, the insurer and society. We review some arguments made in respect of multi-year contracts and provide new analyses on their price implications. We conclude that even under conditions of known and stationary risk, initial capital requirements coul...
Energy Technology Data Exchange (ETDEWEB)
Ding, Xueqin; Wang, Yuzhi, E-mail: wyzss@hnu.edu.cn; Zeng, Qun; Chen, Jing; Huang, Yanhua; Xu, Kaijia
2014-03-01
Graphical abstract: - Highlights: • A series of novel cationic functional hexaalkylguanidinium ionic liquids and anionic functional tetraalkylguanidinium ionic liquids have been synthesized. • Functional guanidinium ionic liquid aqueous two-phase systems have been first designed for the purification of protein. • Mechanisms and performances of the process were researched. • Simple, green, safety and presents better purified ability than ordinary process. • A potential efficient platform for protein purification and related studies. - Abstract: A series of novel cationic functional hexaalkylguanidinium ionic liquids and anionic functional tetraalkylguanidinium ionic liquids have been devised and synthesized based on 1,1,3,3-tetramethylguanidine. The structures of the ionic liquids (ILs) were confirmed by {sup 1}H nuclear magnetic resonance ({sup 1}H NMR) and 13C nuclear magnetic resonance (13C NMR) and the production yields were all above 90%. Functional guanidinium ionic liquid aqueous two-phase systems (FGIL-ATPSs) have been first designed with these functional guanidinium ILs and phosphate solution for the purification of protein. After phase separation, proteins had transferred into the IL-rich phase and the concentrations of proteins were determined by measuring the absorbance at 278 nm using an ultra violet visible (UV–vis) spectrophotometer. The advantages of FGIL-ATPSs were compared with ordinary ionic liquid aqueous two-phase systems (IL-ATPSs). The proposed FGIL-ATPS has been applied to purify lysozyme, trypsin, ovalbumin and bovine serum albumin. Single factor experiments were used to research the effects of the process, such as the amount of ionic liquid (IL), the concentration of salt solution, temperature and the amount of protein. The purification efficiency reaches to 97.05%. The secondary structure of protein during the experimental process was observed upon investigation using UV–vis spectrophotometer, Fourier-transform infrared
Strongly coupled dispersed two-phase flows; Ecoulements diphasiques disperses fortement couples
Energy Technology Data Exchange (ETDEWEB)
Zun, I.; Lance, M.; Ekiel-Jezewska, M.L.; Petrosyan, A.; Lecoq, N.; Anthore, R.; Bostel, F.; Feuillebois, F.; Nott, P.; Zenit, R.; Hunt, M.L.; Brennen, C.E.; Campbell, C.S.; Tong, P.; Lei, X.; Ackerson, B.J.; Asmolov, E.S.; Abade, G.; da Cunha, F.R.; Lhuillier, D.; Cartellier, A.; Ruzicka, M.C.; Drahos, J.; Thomas, N.H.; Talini, L.; Leblond, J.; Leshansky, A.M.; Lavrenteva, O.M.; Nir, A.; Teshukov, V.; Risso, F.; Ellinsen, K.; Crispel, S.; Dahlkild, A.; Vynnycky, M.; Davila, J.; Matas, J.P.; Guazelli, L.; Morris, J.; Ooms, G.; Poelma, C.; van Wijngaarden, L.; de Vries, A.; Elghobashi, S.; Huilier, D.; Peirano, E.; Minier, J.P.; Gavrilyuk, S.; Saurel, R.; Kashinsky, O.; Randin, V.; Colin, C.; Larue de Tournemine, A.; Roig, V.; Suzanne, C.; Bounhoure, C.; Brunet, Y.; Tanaka, A.T.; Noma, K.; Tsuji, Y.; Pascal-Ribot, S.; Le Gall, F.; Aliseda, A.; Hainaux, F.; Lasheras, J.; Didwania, A.; Costa, A.; Vallerin, W.; Mudde, R.F.; Van Den Akker, H.E.A.; Jaumouillie, P.; Larrarte, F.; Burgisser, A.; Bergantz, G.; Necker, F.; Hartel, C.; Kleiser, L.; Meiburg, E.; Michallet, H.; Mory, M.; Hutter, M.; Markov, A.A.; Dumoulin, F.X.; Suard, S.; Borghi, R.; Hong, M.; Hopfinger, E.; Laforgia, A.; Lawrence, C.J.; Hewitt, G.F.; Osiptsov, A.N.; Tsirkunov, Yu. M.; Volkov, A.N.
2003-07-01
This document gathers the abstracts of the Euromech 421 colloquium about strongly coupled dispersed two-phase flows. Behaviors specifically due to the two-phase character of the flow have been categorized as: suspensions, particle-induced agitation, microstructure and screening mechanisms; hydrodynamic interactions, dispersion and phase distribution; turbulence modulation by particles, droplets or bubbles in dense systems; collective effects in dispersed two-phase flows, clustering and phase distribution; large-scale instabilities and gravity driven dispersed flows; strongly coupled two-phase flows involving reacting flows or phase change. Topic l: suspensions particle-induced agitation microstructure and screening mechanisms hydrodynamic interactions between two very close spheres; normal stresses in sheared suspensions; a critical look at the rheological experiments of R.A. Bagnold; non-equilibrium particle configuration in sedimentation; unsteady screening of the long-range hydrodynamic interactions of settling particles; computer simulations of hydrodynamic interactions among a large collection of sedimenting poly-disperse particles; velocity fluctuations in a dilute suspension of rigid spheres sedimenting between vertical plates: the role of boundaries; screening and induced-agitation in dilute uniform bubbly flows at small and moderate particle Reynolds numbers: some experimental results. Topic 2: hydrodynamic interactions, dispersion and phase distribution: hydrodynamic interactions in a bubble array; A 'NMR scattering technique' for the determination of the structure in a dispersion of non-brownian settling particles; segregation and clustering during thermo-capillary migration of bubbles; kinetic modelling of bubbly flows; velocity fluctuations in a homogeneous dilute dispersion of high-Reynolds-number rising bubbles; an attempt to simulate screening effects at moderate particle Reynolds numbers using an hybrid formulation; modelling the two-phase
Multi-Year Program Plan FY'09-FY'15 Solid-State Lighting Research and Development
Energy Technology Data Exchange (ETDEWEB)
None
2009-03-01
President Obama's energy and environment agenda calls for deployment of 'the Cheapest, Cleanest, Fastest Energy Source - Energy Efficiency.' The Department of Energy's (DOE) Office of Energy Efficiency and Renewable Energy (EERE) plays a critical role in advancing the President's agenda by helping the United States advance toward an energy-efficient future. Lighting in the United States is projected to consume nearly 10 quads of primary energy by 2012.3 A nation-wide move toward solid-state lighting (SSL) for general illumination could save a total of 32.5 quads of primary energy between 2012 and 2027. No other lighting technology offers the DOE and our nation so much potential to save energy and enhance the quality of our built environment. The DOE has set forth the following mission statement for the SSL R&D Portfolio: Guided by a Government-industry partnership, the mission is to create a new, U.S.-led market for high-efficiency, general illumination products through the advancement of semiconductor technologies, to save energy, reduce costs and enhance the quality of the lighted environment.
Experimental study on steam-water two-phase flow frictional pressure drops in helical coils
Institute of Scientific and Technical Information of China (English)
无
1997-01-01
Experiments of steam-water two-phase flow frictional pressure drop in a vertical helical coil were carried out in the high-pressure water test loop of Xi'an jiaotong University,The coil is made of stainless steel tube with an inner diameter of 16mm,the helix diameter measured from tube axis to tube axis is 1.3m,and helix angle of the coil is 3.65°,The experimental conditions are:pressurep=4-18MPa,mass velocity G=400-1400kg/(m2.s),inner wall heat flux q=100-700kW/m2,Based on these data,a correlation for predicting the steam-water two-phase flow frictional pressure drop was derived,it can be used for the design of steam generator of HTGR.
ESTIMATION OF MEAN IN PRESENCE OF MISSING DATA UNDER TWO-PHASE SAMPLING SCHEME
Directory of Open Access Journals (Sweden)
Narendra Singh Thakur
2011-01-01
Full Text Available To estimate the population mean with imputation i.e. the technique of substitutingmissing data, there are a number of techniques available in literature like Ratio method ofimputation, Compromised method of imputation, Mean method of imputation, Ahmed method ofimputation, F-T method of imputation, and so on. If population mean of auxiliary information isunknown then these methods are not useful and the two-phase sampling is used to obtain thepopulation mean. This paper presents some imputation methods of for missing values in twophasesampling. Two different sampling designs in two-phase sampling are compared underimputed data. The bias and m.s.e of suggested estimators are derived in the form of populationparameters using the concept of large sample approximation. Numerical study is performed overtwo populations using the expressions of bias and m.s.e and efficiency compared with Ahmedestimators.
Two-phase SPH modelling of waves caused by dam break over a movable bed
Institute of Scientific and Technical Information of China (English)
Seyedeh Leila RAZAVITOOSI; Seyed Ali AYYOUBZADEH; Alireza VALIZADEH
2014-01-01
This paper describes the application of the Smoothed Particle Hydrodynamics (SPH) method for modeling two dimensional waves caused by dam break over a movable bed in two dimensions. The two phase SPH method is developed to solve the Navier-Stokes equations. Both fluid and sediment phases are described by particles as weakly compressible fluids and the incompressibility is achieved by the equation of state. The sediment phase is modeled as a non-Newtonian fluid using three alternative approaches of artificial viscosity and Bingham Model. In this paper, the new formulations for two-phase flows are proposed. The numerical results obtained from the developed SPH model show acceptable accuracy with comparison to experimental data.
Two-phase flow patterns in adiabatic and diabatic corrugated plate gaps
Polzin, A.-E.; Kabelac, S.; de Vries, B.
2016-09-01
Correlations for two-phase heat transfer and pressure drop can be improved considerably, when they are adapted to specific flow patterns. As plate heat exchangers find increasing application as evaporators and condensers, there is a need for flow pattern maps for corrugated plate gaps. This contribution presents experimental results on flow pattern investigations for such a plate heat exchanger background, using an adiabatic visualisation setup as well as a diabatic setup. Three characteristic flow patterns were observed in the considered range of two-phase flow: bubbly flow, film flow and slug flow. The occurrence of these flow patterns is a function of mass flux, void fraction, fluid properties and plate geometry. Two different plate geometries having a corrugation angle of 27° and 63°, respectively and two different fluids (water/air and R365mfc liquid/vapor) have been analysed. A flow pattern map using the momentum flux is presented.
Simon, Moritz
2013-01-01
Motivated by applications in subsurface CO2 sequestration, we investigate constrained optimal control problems with partially miscible two-phase flow in porous media. The objective is, e.g., to maximize the amount of trapped CO2 in an underground reservoir after a fixed period of CO2 injection, where the time-dependent injection rates in multiple wells are used as control parameters. We describe the governing two-phase two-component Darcy flow PDE system and formulate the optimal control problem. For the discretization we use a variant of the BOX method, a locally conservative control-volume FE method. The timestep-wise Lagrangian of the control problem is implemented as a functional in the PDE toolbox Sundance, which is part of the HPC software Trilinos. The resulting MPI parallelized Sundance state and adjoint solvers are linked to the interior point optimization package IPOPT. Finally, we present some numerical results in a heterogeneous model reservoir.
A splitting technique for analytical modelling of two-phase multicomponent flow in porous media
DEFF Research Database (Denmark)
Pires, A.P.; Bedrikovetsky, P.G.; Shapiro, Alexander
2006-01-01
In this paper we discuss one-dimensional models for two-phase Enhanced Oil Recovery (EOR) floods (oil displacement by gases, polymers, carbonized water, hot water, etc.). The main result presented here is the splitting of the EOR mathematical model into thermodynamical and hydrodynamical parts....... The introduction of a potential associated with one of the conservation laws and its use as a new independent coordinate reduces the number of equations by one. The (n)x(n) conservation law model for two-phase n-component EOR flows in new coordinates is transformed into a reduced (n-1)x(n-1) auxiliary system...... containing just thermodynamical variables (equilibrium fractions of components, sorption isotherms) and one lifting equation containing just hydrodynamical parameters (phase relative permeabilities and viscosities). The algorithm to solve analytically the problem includes solution of the reduced auxiliary...
Thermal test results of the two-phase thermal bus technology demonstration loop
Edelstein, Fred; Liandris, Maria; Rankin, J. Gary
1987-01-01
A two-phase heat transport system, the Thermal Bus Technology Demonstrator, has been built and tested for NASA Johnson Space Center for application on Space Station. The loop is a separated two-phase system that uses evaporator flow control valves and liquid condenser flooding to achieve temperature control. Both ambient and thermal vacuum tests have been completed in NASA's Chamber A, initially using Freon-11 and then ammonia as the working fluid. Overall, the tests were quite successful, with the bus achieving all major test objectives, including operation at 19.5 kW and set points at 35 F (1.7 C), 70 F (21.1 C) and 104 F (40.0 C), load sharing, asymmetrical heating and isothermality around the loop. Low plate to vapor temperature drops were obtained for the monogroove cold plate using ammonia and are indicative of the high evaporative film coefficients obtainable with this design.
Design of an ammonia two-phase Prototype Thermal Bus for Space Station
Brown, Richard F.; Gustafson, Eric; Parish, Richard
1987-07-01
The feasibility of two-phase heat transport systems for use on Space Station was demonstrated by testing the Thermal Bus Technology Demonstrator (TBTD) as part of the Integrated Two-Phase System Test in NASA-JSC's Thermal Test Bed. Under contract to NASA-JSC, Grumman is currently developing the successor to the TBTD, the Prototype Thermal Bus System (TBS). The TBS design, which uses ammonia as the working fluid, is intended to achieve a higher fidelity level than the TBTD by incorporating both improvements based on TBTD testing and realistic design margins, and by addressing Space Station issues such as redundancy and maintenance. The TBS is currently being fabricated, with testing scheduled for late 1987/early 1988. This paper describes the TBS design which features fully redundant plumbing loops, five evaporators designed to represent different heat acquisition interfaces, 14 condensers which mate with either space radiators or facility heat exchangers, and several modular components.
Modeling the behavior of a two-phase flow apparatus in microgravity
Baker, Eric W.; Tuttle, Ronald F.
1992-01-01
There are many unknown parameters in two-phase flow in microgravity environment. The database is incomplete and therefore correlations are unknown. This has prompted theoretical and experimental work in the area. A Phillips Laboratory program is currently exploring this area. The Phillips Laboratory experiment is a closed loop rankine cycle with a boiler, condenser/subcooler, accumulator and a pump. The work reported herein attempts to model the Phillips Laboratory Apparatus using a thermal-hydraulic software modeling system called Sim-Tool, developed by Mainstream Engineering. This work also explores the limitations of software modeling a microgravity environment. Results of this modeling effort indicate that Sim-Tool needs further development in order to correctly predict two-phase flow in a microgravity environment.
Performance Prediction of Two-Phase Geothermal Reservoir using Lumped Parameter Model
Nurlaela, F.; Sutopo
2016-09-01
Many studies have been conducted to simulate performance of low-temperature geothermal reservoirs using lumped parameter method. Limited work had been done on applying non-isothermal lumped parameter models to higher temperature geothermal reservoirs. In this study, the lumped parameter method was applied to high-temperature two phase geothermal reservoirs. The model couples both energy and mass balance equations thus can predict temperature, pressure and fluid saturation changes in the reservoir as a result of production, reinjection of water, and/or natural recharge. This method was validated using reservoir simulation results of TOUGH2. As the results, the two phase lumped parameter model simulation without recharge shows good matching, however reservoir model with recharge condition show quite good conformity.
Velocity measurements in the liquid metal flow driven by a two-phase inductor
Pedcenko, A; Priede, J; Gerbeth, G; Hermann, R
2013-01-01
We present the results of velocity measurements obtained by ultrasonic Doppler velocimetry and local potential probes in the flow of GaInSn eutectic melt driven by a two-phase inductor in a cylindrical container. This type of flow is expected in a recent modification to the floating zone technique for the growth of small-diameter single intermetallic compound crystals. We show that the flow structure can be changed from the typical two toroidal vortices to a single vortex by increasing the phase shift between the currents in the two coils from 0 to 90 degrees. The latter configuration is thought to be favourable for the growth of single crystals. The flow is also computed numerically and a reasonable agreement with the experimental results is found. The obtained results may be useful for the design of combined two-phase electromagnetic stirrers and induction heaters for metal or semiconductor melts.
A state-of-the-art report on two-phase critical flow modelling
Energy Technology Data Exchange (ETDEWEB)
Jung, Jae Joon; Jang, Won Pyo; Kim, Dong Soo [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)
1993-09-01
This report reviews and analyses two-phase, critical flow models. The purposes of the report are (1) to make a knowledge base for the full understanding and best-estimate of two-phase, critical flow, (2) to analyse the model development trend and to derive the direction of further studies. A wide range of critical flow models are reviewed. Each model, in general, predicts critical flow well only within specified conditions. The critical flow models of best-estimate codes are special process model included in the hydrodynamic model. The results of calculations depend on the nodalization, discharge coefficient, and other user`s options. The following topics are recommended for continuing studies: improvement of two-fluid model, development of multidimensional model, data base setup and model error evaluation, and generalization of discharge coefficients. 24 figs., 5 tabs., 80 refs. (Author).
Adaptive moving grid methods for two-phase flow in porous media
Dong, Hao
2014-08-01
In this paper, we present an application of the moving mesh method for approximating numerical solutions of the two-phase flow model in porous media. The numerical schemes combine a mixed finite element method and a finite volume method, which can handle the nonlinearities of the governing equations in an efficient way. The adaptive moving grid method is then used to distribute more grid points near the sharp interfaces, which enables us to obtain accurate numerical solutions with fewer computational resources. The numerical experiments indicate that the proposed moving mesh strategy could be an effective way to approximate two-phase flows in porous media. © 2013 Elsevier B.V. All rights reserved.
Two-phase velocity measurements around cylinders using particle image velocimetry
Energy Technology Data Exchange (ETDEWEB)
Hassan, Y.A.; Philip, O.G.; Schmidl, W.D. [Texas A& M Univ., College Station, TX (United States)] [and others
1995-09-01
The particle Image Velocimetry flow measurement technique was used to study both single-phase flow and two-phase flow across a cylindrical rod inserted in a channel. First, a flow consisting of only a single-phase fluid was studied. The experiment consisted of running a laminar flow over four rods inserted in a channel. The water flow rate was 126 cm{sup 3}/s. Then a two-phase flow was studied. A mixture of water and small air bubbles was used. The water flow rate was 378 cm{sup 3}/s and the air flow rate was approximately 30 cm{sup 3}/s. The data are analyzed to obtain the velocity fields for both experiments. After interpretation of the velocity data, forces acting on a bubble entrained by the vortex were calculated successfully. The lift and drag coefficients were calculated using the velocity measurements and the force data.
A two-phase tabu search approach to scheduling optimization in container terminals
Institute of Scientific and Technical Information of China (English)
ZENG Qing-cheng; YANG Zhong-zhen
2007-01-01
An optimization model for scheduling of quay cranes (QCs) and yard trailers was proposed to improve the overall efficiency of container terminals. To implement this model, a two-phase tabu search algorithra was designed. In the QCs scheduling phase of the algorithm, a search was performed to determine a good QC unloading operation order. For each QC unloading operation order generated during the QC's scheduling phase, another search was run to obtain a good yard trailer routing for the given QC's unloading order. Using this information, the time required for the operation was estimated,then the time of return to availability of the units was fed back to the QC scheduler. Numerical tests show that the two-phase Tabu Search algorithm searches the solution space efficiently, decreases the empty distance yard trailers must travel, decreases the number of trailers needed, and thereby reduces time and costs and improves the integration and reliability of container terminal operation systems.
Kou, Jisheng
2013-01-01
A class of discontinuous Galerkin methods with interior penalties is presented for incompressible two-phase flow in heterogeneous porous media with capillary pressures. The semidiscrete approximate schemes for fully coupled system of two-phase flow are formulated. In highly heterogeneous permeable media, the saturation is discontinuous due to different capillary pressures, and therefore, the proposed methods incorporate the capillary pressures in the pressure equation instead of saturation equation. By introducing a coupling approach for stability and error estimates instead of the conventional separate analysis for pressure and saturation, the stability of the schemes in space and time and a priori hp error estimates are presented in the L2(H 1) for pressure and in the L∞(L2) and L2(H1) for saturation. Two time discretization schemes are introduced for effectively computing the discrete solutions. © 2013 Societ y for Industrial and Applied Mathematics.
Drop volumes and terminal velocities in aqueous two-phase systems
Energy Technology Data Exchange (ETDEWEB)
Bhavasar, P. M.; Jafarabad, K. R.; Pandit, A. B.; Sawant, S. B.; Joshi, J. B. [Bombay Univ. (India). Dept. of Chemical Technology
1996-12-01
Two phase aqueous extraction techniques employed in liquid-liquid extraction equipment such as spray columns and plate columns were studied, with particular attention to predicting drop sizes prior to jetting, and their terminal velocity. In the particular system studied, the values obtained by conventional models as found in the literature were considered inapplicable. A generalised model was constructed using video photographic measurements, and a correlation was developed for the terminal velocities of the drops in aqueous two-phase systems. This simplified model was found to be successful in expressing the terminal rise/fall velocities of droplets covering a specific range of Morton numbers (representing physical properties) from 0.00211 to 11050 and Eotvos numbers (representative of drop size) from 0.091 to 288. 22 refs., 6 figs.
Bondar, A; Dolgov, A; Nosov, V; Shekhtman, L; Shemyakina, E; Sokolov, A
2016-01-01
A two-phase Cryogenic Avalanche Detector (CRAD) with electroluminescence (EL) gap, operated in argon doped with a minor (49$\\pm$7 ppm) admixture of nitrogen, has been studied. The EL gap was optically read out using cryogenic PMTs located on the perimeter of the gap. We present the results of the measurements of the N$_2$ content, detector sensitivity to X-ray-induced signals, EL gap yield and electron lifetime in the liquid. The detector sensitivity, at a drift field in liquid Ar of 0.6 kV/cm, was measured to be 9 and 16 photoelectrons recorded at the PMTs per keV of deposited energy at 23 and 88 keV respectively. Such two-phase detectors, with enhanced sensitivity to the S2 (ionization-induced) signal, are relevant in the field of argon detectors for dark matter search and low energy neutrino detection.
Measurement of average density and relative volumes in a dispersed two-phase fluid
Sreepada, Sastry R.; Rippel, Robert R.
1992-01-01
An apparatus and a method are disclosed for measuring the average density and relative volumes in an essentially transparent, dispersed two-phase fluid. A laser beam with a diameter no greater than 1% of the diameter of the bubbles, droplets, or particles of the dispersed phase is directed onto a diffraction grating. A single-order component of the diffracted beam is directed through the two-phase fluid and its refraction is measured. Preferably, the refracted beam exiting the fluid is incident upon a optical filter with linearly varing optical density and the intensity of the filtered beam is measured. The invention can be combined with other laser-based measurement systems, e.g., laser doppler anemometry.
An acoustic-convective splitting-based approach for the Kapila two-phase flow model
ten Eikelder, M. F. P.; Daude, F.; Koren, B.; Tijsseling, A. S.
2017-02-01
In this paper we propose a new acoustic-convective splitting-based numerical scheme for the Kapila five-equation two-phase flow model. The splitting operator decouples the acoustic waves and convective waves. The resulting two submodels are alternately numerically solved to approximate the solution of the entire model. The Lagrangian form of the acoustic submodel is numerically solved using an HLLC-type Riemann solver whereas the convective part is approximated with an upwind scheme. The result is a simple method which allows for a general equation of state. Numerical computations are performed for standard two-phase shock tube problems. A comparison is made with a non-splitting approach. The results are in good agreement with reference results and exact solutions.
Use of two-phase flow heat transfer method in spacecraft thermal system
Hye, A.
1985-01-01
In space applications, weight, volume and power are critical parameters. Presently liquid freon is used in the radiator planels of the Space Shuttle to dissipate heat. This requires a large amount of freon, large power for pumps, large volume and weight. Use of two-phase flow method to transfer heat can reduce them significantly. A modified commercial vapor compression refrigerator/freezer was sucessfully flown in STS-4 to study the effect of zero-gravity on the system. The duty cycle was about 5 percent higher in flight as compared to that on earth due to low flow velocity in condenser. The vapor Reynolds number at exit was about 4000 as compared to about 12,000. Efforts are underway to design a refrigerator/freezer using an oil-free compressor for Spacelab Mission 4 scheduled to fly in January 1986. A thermal system can be designed for spacecraft using the two-phase flow to transfer heat economically.
Targeted Delivery by Smart Capsules for Controlling Two-phase Flow in Porous Media
Fan, J.; Weitz, D.
2015-12-01
Understanding and controlling two-phase flow in porous media are of particular importance to the relevant industry applications, such as enhanced oil recovery, CO2 sequestration, and groundwater remediation. We develop a variety of smart microcapsules that can deliver and release specific substances to the target location in the porous medium, and therefore change the fluid property or medium geometry at certain locations. In this talk, I will present two types of smart capsules for (a) delivering surfactant to the vicinity of oil-water interface and (b) delivering microgels to the high permeability region and therefore blocking the pore space there, respectively. We also show that flooding these two capsules into porous media effectively reduces the trapped oil and improves the homogeneity of the medium, respectively. Besides of its industrial applications, this technique also opens a new window to study the mechanism of two-phase flow in porous media.
Two-phase dusty fluid flow along a cone with variable properties
Siddiqa, Sadia; Begum, Naheed; Hossain, Md. Anwar; Mustafa, Naeem; Gorla, Rama Subba Reddy
2016-09-01
In this paper numerical solutions of a two-phase natural convection dusty fluid flow are presented. The two-phase particulate suspension is investigated along a vertical cone by keeping variable viscosity and thermal conductivity of the carrier phase. Comprehensive flow formations of the gas and particle phases are given with the aim to predict the behavior of heat transport across the heated cone. The influence of (1) air with particles, (2) water with particles and (3) oil with particles are shown on shear stress coefficient and heat transfer coefficient. It is recorded that sufficient increment in heat transport rate can be achieved by loading the dust particles in the air. Further, distribution of velocity and temperature of both the carrier phase and the particle phase are shown graphically for the pure fluid (air, water) as well as for the fluid with particles (air-metal and water-metal particle mixture).
Numerical simulation of oil-water two-phase flow in horizontal pipes
Energy Technology Data Exchange (ETDEWEB)
Santos, Michelly Martuchele; Ramirez, Ramiro Gustavo [Federal University of Itajuba (UNIFEI), MG (Brazil)], E-mail: ramirez@unifei.edu.br
2010-07-01
The numerical simulation of two phase flow through the CFD techniques have become of great interest due to the complexity of this type of flow. The present work aims to simulate the oil-water two-phase flow in horizontal pipes for stratification analysis of the mixture. In numerical simulations, incompressible flow, isothermal, steady state and laminar flow were considered. Numerical analysis of flow stratification was carried out for horizontal straight and curved pipe. FLUENT was the commercial software employed in the simulation. Three-dimensional mesh generated by ICEM-CFD program was used for numerical simulation. The numerical analysis flow pattern was carried out employing the Eulerian model, considering the drag and lift interphase forces. The simulation results for the horizontal straight pipe were qualitatively validated with experimental data obtained in the Laboratory of Phase Separation of UNIFEI. (author)
Simulation of non-equilibrium two-phase flow in single component fluid systems
Energy Technology Data Exchange (ETDEWEB)
Hoyer, Norbert [Scandpower A/S, Kjeller (Norway)
1996-12-31
Traditionally, two-phase flow has been modelled by separate correlations for void fraction, pressure drop and flow regimes. A more unified approach, which treats flow regimes as an integral part of the two-fluid model is described in this work. A general, transient simulator for steam-water/inert gas systems has been developed. MONA is based on a full two-fluid, three field, nonequilibrium, nonhomogeneous two-phase flow model. It includes further an extensive heat and mass transfer package. The major contribution for MONA validation comes from the FRIGG loop experiments, covering a wide range of parameters like geometry, flow, subcooling, pressure and heat flux. Both validation against steady state and dynamic experiments has been carried out, the former comprising void fractions, pressure drops as well as natural and forced circulation flow rates while the latter consists of boiling instability analysis. 69 refs., 41 figs., 5 tabs.
Membrane-less micro fuel cell based on two-phase flow
Hashemi, S. M. H.; Neuenschwander, M.; Hadikhani, P.; Modestino, M. A.; Psaltis, D.
2017-04-01
Most microfluidic fuel cells use highly soluble fuels and oxidants in streams of liquid electrolytes to overcome the mass transport limitations that result from the low solubility of gaseous reactants such as hydrogen and oxygen. In this work, we address these limitations by implementing controlled two-phase flows of these gases in a set of microchannels electrolytically connected through a narrow gap. Annular flows of the gases reshape the concentration boundary layer over the surface of electrodes and increase the mass-transport limited current density in the system. Our results show that the power density of a two-phase system with hydrogen and oxygen streams is an order of magnitude higher than that of single phase system consisting of liquid electrolytes saturated with the same reactants. The reactor design described here can be employed to boost the performance of MFFCs and put them in a more competitive position compared to membrane based fuel cells.
Energy Technology Data Exchange (ETDEWEB)
1991-07-01
The possible head degradation of the SRPR pumps may be attributable to two independent phenomena, one due to the inception of cavitation and the other due to the two-phase flow phenomena. The head degradation due to the appearance of cavitation on the pump blade is hardly likely in the conventional pressurized water reactor (PWR) since the coolant circulating line is highly pressurized so that the cavitation is difficult to occur even at LOCA (loss of coolant accident) conditions. On the other hand, the suction pressure of SRPR pump is order-of-magnitude smaller than that of PWR so that the cavitation phenomena, may prevail, should LOCA occur, depending on the extent of LOCA condition. In this study, therefore, both cavitation phenomena and two-phase flow phenomena were investigated for the SRPR pump by using various analytical tools and the numerical results are presented herein.
An acoustic-convective splitting-based approach for the Kapila two-phase flow model
Energy Technology Data Exchange (ETDEWEB)
Eikelder, M.F.P. ten, E-mail: m.f.p.teneikelder@tudelft.nl [EDF R& D, AMA, 7 boulevard Gaspard Monge, 91120 Palaiseau (France); Eindhoven University of Technology, Department of Mathematics and Computer Science, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Daude, F. [EDF R& D, AMA, 7 boulevard Gaspard Monge, 91120 Palaiseau (France); IMSIA, UMR EDF-CNRS-CEA-ENSTA 9219, Université Paris Saclay, 828 Boulevard des Maréchaux, 91762 Palaiseau (France); Koren, B.; Tijsseling, A.S. [Eindhoven University of Technology, Department of Mathematics and Computer Science, P.O. Box 513, 5600 MB Eindhoven (Netherlands)
2017-02-15
In this paper we propose a new acoustic-convective splitting-based numerical scheme for the Kapila five-equation two-phase flow model. The splitting operator decouples the acoustic waves and convective waves. The resulting two submodels are alternately numerically solved to approximate the solution of the entire model. The Lagrangian form of the acoustic submodel is numerically solved using an HLLC-type Riemann solver whereas the convective part is approximated with an upwind scheme. The result is a simple method which allows for a general equation of state. Numerical computations are performed for standard two-phase shock tube problems. A comparison is made with a non-splitting approach. The results are in good agreement with reference results and exact solutions.
Interfacial structures of confined air-water two-phase bubbly flow
Energy Technology Data Exchange (ETDEWEB)
Kim, S.; Ishii, M.; Wu, Q.; McCreary, D.; Beus, S.G.
2000-08-01
The interfacial structure of the two-phase flows is of great importance in view of theoretical modeling and practical applications. In the present study, the focus is made on obtaining detailed local two-phase parameters in the air-water bubbly flow in a rectangular vertical duct using the double-sensor conductivity probe. The characteristic wall-peak is observed in the profiles of the interracial area concentration and the void fraction. The development of the interfacial area concentration along the axial direction of the flow is studied in view of the interfacial area transport and bubble interactions. The experimental data is compared with the drift flux model with C{sub 0} = 1.35.
Two-Phase Algorithm for Multi-warehouse and Multi-task Based Logistics Delivery
Institute of Scientific and Technical Information of China (English)
ZHANG Jun-wei; MA Fan-yuan
2005-01-01
To a scaled logistic company, assigning is an important part of logistic, and further development will make the optimized assigning of multi-warehouse and multi-task possible. This paper provided a two-phase multiwarehouse and multi-task based algorithm which has two phases. In the first phase, it combines sweep algorithm,saving algorithm and virtual task point to present a method. And in the second phase it provides an algorithm for the arrangement of goods loading which is based on the constraints of time-window and attributes of goods and vehicle. It uses the computing results of the first phase to form more detailed delivery scheme based on the constraints of time-window and attributes of vehicle and goods.
Ultrafast synthesis of LTA nanozeolite using a two-phase segmented fluidic microreactor.
Zhou, Jianhai; Jiang, Hao; Xu, Jian; Hu, Jun; Liu, Honglai; Hu, Ying
2013-08-01
Fast synthesis of nanosized zeolite is desirable for many industrial applications. An ultrafast synthesis of LTA nanozeolite by the organic-additive-free method in a two-phase segmented fluidic microreactor has been realized. The results reveal that the obtained LTA nanozeolites through microreactor are much smaller and higher crystallinity than those under similar conditions through conventional macroscale batch reactor. By investing various test conditions, such as the crystallization temperature, the flow rate, the microchannel length, and the aging time of gel solution, this two-phase segmented fluidic microreactor system enables us to develop an ultrafast method for nanozeolite production. Particularly, when using a microreactor with the microchannel length of 20 m, it only takes 10 min for the crystallization and no aging process to successfully produce the crystalline LTA nanozeolites at 95 degrees C.
Tang, Malcolm S. Y.; Ng, Eng-Poh; Juan, Joon Ching; Ooi, Chien Wei; Ling, Tau Chuan; Woon, Kai Lin; Loke Show, Pau
2016-08-01
It is known that carbon nanotubes show desirable physical and chemical properties with a wide array of potential applications. Nonetheless, their potential has been hampered by the difficulties in acquiring high purity, chiral-specific tubes. Considerable advancement has been made in terms of the purification of carbon nanotubes, for instance chemical oxidation, physical separation, and myriad combinations of physical and chemical methods. The aqueous two-phase separation technique has recently been demonstrated to be able to sort carbon nanotubes based on their chirality. The technique requires low cost polymers and salt, and is able to sort the tubes based on their diameter as well as metallicity. In this review, we aim to provide a review that could stimulate innovative thought on the progress of a carbon nanotubes sorting method using the aqueous two-phase separation method, and present possible future work and an outlook that could enhance the methodology.
MICROGRAVITY EXPERIMENTS OF TWO-PHASE FLOW PATTERNS ABOARD MIR SPACE STATION
Institute of Scientific and Technical Information of China (English)
赵建福; 解京昌; 林海; 胡文瑞; A.V. Ivanov; A.Yu. Belyaev
2001-01-01
A first experimental study on two-phase flow patterns at a long-term,steady microgravity condition was conducted on board the Russian Space Station "MIR" in August 1999. Carbogal and air are used as the liquid and the gas phase,respectively. Bubble, slug, slug-annular transitional, and annular flows are observed.A new region of annular flow with lower liquid superficial velocity is discovered,and the region of the slug-annular transitionalfiow is wider than that observed by experiments on board the parabolic aircraft. The main patterns are bubble, slug annular transitional and annular flows based on the experiments on board MIR space station. Some influences on the two-phase flow patterns in the present experiments are discussed.
Microstructures and Mechanical Properties of Two-Phase Alloys Based on NbCr(2)
Energy Technology Data Exchange (ETDEWEB)
Cady, C.M.; Chen, K.C.; Kotula, P.G.; Mauro, M.E.; Thoma, D.J.
1998-12-07
A two-phase, Nb-Cr-Ti alloy (bee+ C15 Laves phase) has been developed using several alloy design methodologies. In effort to understand processing-microstructure-property relationships, diffment processing routes were employed. The resulting microstructure and mechanical properties are discussed and compared. Plasma arc-melted samples served to establish baseline, . . . as-cast properties. In addition, a novel processing technique, involving decomposition of a supersaturated and metastable precursor phase during hot isostatic pressing (HIP), was used to produce a refined, equilibrium two-phase microstructure. Quasi-static compression tests as a ~ function of temperature were performed on both alloy types. Different deformation mechanisms were encountered based upon temperature and microstructure.
Numerical Fractional-Calculus Model for Two-Phase Flow in Fractured Media
Directory of Open Access Journals (Sweden)
Wenwen Zhong
2013-01-01
Full Text Available Numerical simulation of two-phase flow in fractured porous media is an important topic in the subsurface flow, environmental problems, and petroleum reservoir engineering. The conventional model does not work well in many cases since it lacks the memory property of fracture media. In this paper, we develop a new numerical formulation with fractional time derivative for two-phase flow in fractured porous media. In the proposed formulation, the different fractional time derivatives are applied to fracture and matrix regions since they have different memory properties. We further develop a two-level time discrete method, which uses a large time step for the pressure and a small time step size for the saturation. The pressure equation is solved implicitly in each large time step, while the saturation is updated by an explicit fractional time scheme in each time substep. Finally, the numerical tests are carried out to demonstrate the effectiveness of the proposed numerical model.
Dynamic characteristics of two-phase thermal control system for spacecraft
Malozemov, Vladimir V.; Kudryavtseva, Natal'ya S.; Antonov, Viktor A.; Zagar, Oleg V.; Chernobaev, Nikolaj N.
1992-07-01
This paper deals with review of the issues associated with modelling the dynamic processes in the spacecraft two-phase thermal control systems. The work presents the results of modelling the nonstationary conditions of the evaporative and condensation heat exchangers functioning, investigates their response to the characteristic external influences. Disclosed are the results of the computer-aided modelling the two-phase thermal control system with a pump. The dynamic characteristics of the change in the inputs of pressures, temperatures and vapor content of a coolant in various branches of the system, as well as the lengths of the heat transfer zones in the evaporator and condenser under effect of the typical disturbing actions are obtained. The attained transients are analyzed.
Gas-driven subharmonic waves in a vibrated two-phase granular material.
Matas, J-P; Uehara, J; Behringer, R P
2008-04-01
Vibrated powders exhibit striking phenomena: subharmonic waves, oscillons, convection, heaping, and even bubbling. We demonstrate novel rectangular profile subharmonic waves for vibrated granular material, that occur uniquely in the two-phase case of grains, and a fluid, such as air. These waves differ substantially from those for the gas-free case, exhibit different dispersion relations, and occur for specific shaking parameters and air pressure, understandable with gas-particle flow models. These waves occur when the gas diffusively penetrates the granular layer in a time comparable to the shaker period. As the pressure is lowered towards P =0, the granular-gas system exhibits a Knudsen regime. This instability provides an opportunity to quantitatively test models of two-phase flow.
Cerroni, D.; Fancellu, L.; Manservisi, S.; Menghini, F.
2016-06-01
In this work we propose to study the behavior of a solid elastic object that interacts with a multiphase flow. Fluid structure interaction and multiphase problems are of great interest in engineering and science because of many potential applications. The study of this interaction by coupling a fluid structure interaction (FSI) solver with a multiphase problem could open a large range of possibilities in the investigation of realistic problems. We use a FSI solver based on a monolithic approach, while the two-phase interface advection and reconstruction is computed in the framework of a Volume of Fluid method which is one of the more popular algorithms for two-phase flow problems. The coupling between the FSI and VOF algorithm is efficiently handled with the use of MEDMEM libraries implemented in the computational platform Salome. The numerical results of a dam break problem over a deformable solid are reported in order to show the robustness and stability of this numerical approach.
A continuum theory for two-phase flows of particulate solids: application to Poiseuille flows
Monsorno, Davide; Varsakelis, Christos; Papalexandris, Miltiadis V.
2015-11-01
In the first part of this talk, we present a novel two-phase continuum model for incompressible fluid-saturated granular flows. The model accounts for both compaction and shear-induced dilatancy and accommodates correlations for the granular rheology in a thermodynamically consistent way. In the second part of this talk, we exercise this two-phase model in the numerical simulation of a fully-developed Poiseuille flow of a dense suspension. The numerical predictions are shown to compare favorably against experimental measurements and confirm that the model can capture the important characteristics of the flow field, such as segregation and formation of plug zones. Finally, results from parametric studies with respect to the initial concentration, the magnitude of the external forcing and the width of the channel are presented and the role of these physical parameters is quantified. Financial Support has been provided by SEDITRANS, an Initial Training Network of the European Commission's 7th Framework Programme
STUDY OF IDENTIFICATION OF TWO-PHASE FLOW PARAMETERS BY PRESSURE FLUCTUATION ANALYSIS
Directory of Open Access Journals (Sweden)
Ondrej Burian
2016-12-01
Full Text Available This paper deals with identification of parameters of simple pool boiling in a vertical rectangular channel by analysis of pressure fluctuation. In this work is introduced a small experimental facility about 9 kW power, which was used for simulation of pool boiling phenomena and creation of steam-water volume. Several pressure fluctuations measurements and differential pressure fluctuations measurements at warious were carried out. Main changed parameters were power of heaters and hydraulics resistance of channel internals. Measured pressure data was statistically analysed and compared with goal to find dependencies between parameters of two-phase flow and statistical properties of pressure fluctuation. At the end of this paper are summarized final results and applicability of this method for parameters determination of two phase flow for pool boiling conditions at ambient pressure.
RELAP5 simulation for one and two-phase natural circulation phenomenon
Energy Technology Data Exchange (ETDEWEB)
Sabundjian, Gaiane; Andrade, Delvonei Alves de; Umbehaun, Pedro Ernesto; Torres, Walmir Maximo; Castro, Alfredo Jose Alvim de [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mails: gdjian@ipen.br; delvonei@ig.com.br; umbehaun@ipen.br; wmtorres@ipen.br; Braz Filho, Francisco A.; Borges, Eduardo Madeira [Centro Tecnico Aeroespacial (CTA-IEAv), Sao Jose dos Campos, SP (Brazil). Inst. de Estudos Avancados]. E-mails: eduardo@ieav.cta.br; fbraz@ieav.cta.br; Belchior Junior, Antonio; Rocha, Ricardo Takeshi Vieira da [Centro Tecnologico da Marinha em Sao Paulo (CTMSP), Sao Paulo, SP (Brazil)]. E-mails: belchior@bol.com.br; rtvrocha@uol.com.br; Damy, Osvaldo Luiz Almeida; Torres, Eduardo [Universidade de Sao Paulo (USP), SP (Brazil). Escola Politecnica]. E-mails: osvaldo.damy@poli.usp.br; etorres@pac.ind.br
2007-07-01
The objective of this paper is to study the natural circulation phenomenon in one and two-phase regime. There has been a crescent interest in the scientific community in the study of the natural circulation. New generation of compact nuclear reactors uses the natural circulation for residual heat removal in case of accident or shutdown. For this study, the modeling and the simulation of the experimental circuit is performed with the RELAP5 code. The experimental circuit is mounted in the Chemical Engineering Department of the University of Sao Paulo. It is presented in this work the theoretical/experimental comparison for one and two-phase flow. These results will be stored in a database to validate RELAP5 calculations. This work was also used to training some users of RELAP5 from IEAv. (author)
Computer code for gas-liquid two-phase vortex motions: GLVM
Yeh, T. T.
1986-01-01
A computer program aimed at the phase separation between gas and liquid at zero gravity, induced by vortex motion, is developed. It utilizes an explicit solution method for a set of equations describing rotating gas-liquid flows. The vortex motion is established by a tangential fluid injection. A Lax-Wendroff two-step (McCormack's) numerical scheme is used. The program can be used to study the fluid dynamical behavior of the rotational two-phase fluids in a cylindrical tank. It provides a quick/easy sensitivity test on various parameters and thus provides the guidance for the design and use of actual physical systems for handling two-phase fluids.
Bondar, A.; Buzulutskov, A.; Dolgov, A.; Nosov, V.; Shekhtman, L.; Shemyakina, E.; Sokolov, A.
2017-02-01
A two-phase Cryogenic Avalanche Detector (CRAD) with electroluminescence (EL) gap, operated in argon doped with a minor (49±7 ppm) admixture of nitrogen, has been studied. The EL gap was optically read out using cryogenic PMTs located on the perimeter of the gap. We present the results of the measurements of the N2 content, detector sensitivity to X-ray-induced signals, EL gap yield and electron lifetime in the liquid. The detector sensitivity, at a drift field in liquid Ar of 0.6 kV/cm, was measured to be 9 and 16 photoelectrons recorded at the PMTs per keV of deposited energy at 23 and 88 keV respectively. Such two-phase detectors, with enhanced sensitivity to the S2 (ionization-induced) signal, are relevant in the field of argon detectors for dark matter search and low energy neutrino detection.
A Batch Arrival Retrial Queue with Two Phases of Service and Bernoulli Vacation Schedule
Institute of Scientific and Technical Information of China (English)
Gautam Choudhury; Kandarpa Deka
2013-01-01
We consider an MX/G/1 queueing system with two phases of heterogeneous service and Bernoulli vacation schedule which operate under a linear retrial policy.In addition,each individual customer is subject to a control admission policy upon the arrival.This model generalizes both the classical M/G/1 retrial queue with arrivals in batches and a two phase batch arrival queue with a single vacation under Bernoulli vacation schedule.We will carry out an extensive stationary analysis of the system,including existence of the stationary regime,embedded Markov chain,steady state distribution of the server state and number of customer in the retrial group,stochastic decomposition and calculation of the first moment.
Two-Phase Reactions in Microdroplets without the Use of Phase-Transfer Catalysts.
Yan, Xin; Cheng, Heyong; Zare, Richard N
2017-02-22
Many important chemical transformations occur in two-phase reactions, which are widely used in chemical, pharmaceutical, and polymer manufacturing. We present an efficient method for performing two-phase reactions in microdroplets sheared by sheath gas without using a phase-transfer catalyst. This avoids disadvantages such as thermal instability, high cost, and, especially, the need to separate and recycle the catalysts. We show that various alcohols can be oxidized to the corresponding aldehydes and ketones within milliseconds in moderate to good yields (50-75 %). The scale-up of the present method was achieved at an isolated rate of 1.2 mg min(-1) for the synthesis of 4-nitrobenzylaldehyde from 4-nitrobenzyl alcohol in the presence of sodium hypochlorite. The biphasic nature of this process, which avoids use of a phase-transfer catalyst, greatly enhances synthetic effectiveness.
Well-posed Euler model of shock-induced two-phase flow in bubbly liquid
Tukhvatullina, R. R.; Frolov, S. M.
2017-07-01
A well-posed mathematical model of non-isothermal two-phase two-velocity flow of bubbly liquid is proposed. The model is based on the two-phase Euler equations with the introduction of an additional pressure at the gas bubble surface, which ensures the well-posedness of the Cauchy problem for a system of governing equations with homogeneous initial conditions, and the Rayleigh-Plesset equation for radial pulsations of gas bubbles. The applicability conditions of the model are formulated. The model is validated by comparing one-dimensional calculations of shock wave propagation in liquids with gas bubbles with a gas volume fraction of 0.005-0.3 with experimental data. The model is shown to provide satisfactory results for the shock propagation velocity, pressure profiles, and the shock-induced motion of the bubbly liquid column.
Monte Carlo simulation of a two-phase flow in an unsaturated porous media
Directory of Open Access Journals (Sweden)
Xu Peng
2012-01-01
Full Text Available Relative permeability is a significant transport property which describes the simultaneous flow of immiscible fluids in porous media. A pore-scale physical model is developed for the two-phase immiscible flow in an unsaturated porous media according to the statistically fractal scaling laws of natural porous media, and a predictive calculation of two-phase relative permeability is presented by Monte Carlo simulation. The tortuosity is introduced to characterize the highly irregular and convoluted property of capillary pathways for fluid flow through a porous medium. The computed relative permeabilities are compared with empirical formulas and experimental measurements to validate the current model. The effect of fractal dimensions and saturation on the relative permeabilities is also discussed
Experimental study of two-phase water flow in vertical thin rectangular channels
Wright, Christopher T.; O'Brien, James E.; Anderson, Elgin A.
2001-11-01
An experimental heat transfer study of two-phase water flow in vertical thin rectangular channels with side vents is conducted. A multiple, heated channel configuration with up- and down-flow conditions is investigated. Parallel heated and unheated flow channels test the effects of cross flow on the onset of nucleate boiling (ONB) and critical heat flux (CHF). The test apparatus provides pressure and substrate temperature data and visual data of the boiling regimes and side-vent flow patterns. The objectives are to determine the two-phase, heat and mass transfer characteristics between adjacent channels as permitted by side-vent cross flow. These data will help develop ONB and CHF correlations for flow geometries typical of plate-type nuclear reactors and heat exchangers. Fundamentally, the data shows how the geometry, flow conditions, and channel configurations affect the heat transfer characteristics of interior channel flows, essential in understanding the ONB and CHF phenomena.
Jain, Ashu N; Khan, Tanya R; Daugulis, Andrew J
2010-11-01
The bioproduction of benzaldehyde from benzyl alcohol using Pichia pastoris was examined in a solid-liquid two-phase partitioning bioreactor (TPPB) to reduce substrate and product inhibition. Rational polymer selection identified Elvax 40W as an effective sequestering phase, possessing partition coefficients for benzyl alcohol and benzaldehyde of 3.5 and 35.4, respectively. The use of Elvax 40W increased the overall mass of benzaldehyde produced by approx. 300% in a 5 l bioreactor, relative to a single phase biotransformation. The two-phase system had a molar yield of 0.99, indicating that only minor losses occurred. These results provide a promising starting point for solid-liquid TPPBs to enhance benzaldehyde production, and suggest that multiple, targeted polymers may provide relief for transformations characterized by multiple inhibitory substrates/product/by-products.
On modeling shape memory polymers as elastic two-phase composite materials
Gilormini, Pierre; Diani, Julie
2012-01-01
International audience; A model has been proposed recently, which describes the experimentally observed mechanical behavior of some shape memory polymers. It considers a purely thermoelastic behavior, without strain rate effects, and assumes essentially that the polymer can be considered as a two-phase composite, with glassy and rubbery phases having volume fractions that depend on temperature only. Since a uniform stress hypothesis was used in the original formulation, with an inconsistency ...
Two-phase flow modelling of sediment suspension in the Ems/Dollard estuary
Xu, Chunyang; Dong, Ping
2017-05-01
Understanding and quantifying mud suspension and sediment transport processes are of great importance for effective exploitation and sustainable management of estuarine environments. Event-based predictive models are widely used to identify the key interactions and mechanisms that govern the dynamics involved and to provide the essential parameterisation for assessing the long-term morphodynamic evolution of the estuaries. This study develops a one-dimensional-vertical (1DV) Reynolds averaged two-phase model for cohesive sediments resuspension driven by tidal flows. To capture the time-dependent flocculation process more accurately, a new drag force closure which relates empirically to settling velocity of mud flocs with suspended sediment concentration (SSC) is incorporated into the two-phase model. The model is then applied to simulate mud suspension in the Ems/Dollard estuary during two periods (June and August 1996) of tidal forcing. Numerical predictions of bed shear stresses and sediment concentrations at different elevations above the bed are compared with measured variations. The results confirm the importance of including flocculation effects in calculating the settling velocity of mud flocs and demonstrates the sensitivity of prediction with the settling velocity in terms of flocs concentration. Although the two-phase modelling approach can in principle better capture the essential interactions between fluid and sediment phases, its practical advantages over the simpler single phase approach cannot be confirmed for the data periods simulated, partly because the overall suspended sediment concentration measured is rather low and the interaction between the two phases is weak and also because the uncertainties in the relationship between the settling velocity and flocs concentration.
Heat pipes et two-phase loops for spacecraft applications. ESA programmes
Energy Technology Data Exchange (ETDEWEB)
Supper, W. [European Space Agency / ESTEC. Thermal control and life support division (France)
1996-12-31
This document is a series of transparencies presenting the current and future applications of heat pipes in spacecraft and the activities in the field of capillary pumped two-phase loops: thermal tests, high-efficiency low pressure drop condensers, theoretical understanding of evaporator function, optimization of liquid and vapor flows, trade-off between low and high conductivity wicks, development of high capillary capacity wicks etc.. (J.S.)
INFLUENCE OF SURFACTANT ON TWO-PHASE FLOW REGIME AND PRESSURE DROP IN UPWARD INCLINED PIPES
Institute of Scientific and Technical Information of China (English)
XIA Guo-dong; CHAI Lei
2012-01-01
The influence of a surfactant on the two-phase flow regime and the pressure drop in upward inclined pipes is investigated for various gas/liquid flow rates.The air/water and air/100 ppm sodium dodecyl sulphate aqueous solution are used as the working fluids.The influence of the surfactant on the two-phase flow regime in upward inclined pipes is investigated using the electrical tomographic technique.For 0°,2.5° and 5° pipe inclinations,the surfactant has obvious effect on the transition from the stratified wavy flow to the annular flow,and the range of the stratified smooth flow regime is also extended to higher gas velocities.For 10°pipe inclination,no stratified flow regime is observed in the air/water flow.In the air/surfactant solution system,however,the stratified flow regime can be found in the range of USG =10m/s-28m/s and USL =0.07 m/s-0.2 m/s.For all inclination angles,the changes of the pressure gradient characteristics are accompanied with the flow pattern transitions.Adding surfactant in a two-phase flow would reduce the pressure gradient significantly in the slug flow and annular flow regimes.In the annular flow regime,the pressure gradient gradually becomes free of the influence of the upward inclined angle,and is only dependent on the property of the two-phase flow.
Kharin, Stanislav N.; Sarsengeldin, Merey M.; Nouri, Hassan
2016-08-01
On the base of the Holm model, we represent two phase spherical Stefan problem and its analytical solution, which can serve as a mathematical model for diverse thermo-physical phenomena in electrical contacts. Suggested solution is obtained from integral error function and its properties which are represented in the form of series whose coefficients have to be determined. Convergence of solution series is proved.
A two-phase free boundary problem for a nonlinear diffusion-convection equation
Energy Technology Data Exchange (ETDEWEB)
De Lillo, S; Lupo, G [Dipartimento di Matematica e Informatica, Universita degli Studi di Perugia, Via Vanvitelli 1, 06123 Perugia (Italy)], E-mail: silvana.delillo@pg.infn.it
2008-04-11
A two-phase free boundary problem associated with a diffusion-convection equation is considered. The problem is reduced to a system of nonlinear integral equations, which admits a unique solution for small times. The system admits an explicit two-component solution corresponding to a two-component shock wave of the Burgers equation. The stability of such a solution is also discussed.
Modelling of two-phase flow based on separation of the flow according to velocity
Energy Technology Data Exchange (ETDEWEB)
Narumo, T. [VTT Energy, Espoo (Finland). Nuclear Energy
1997-12-31
The thesis concentrates on the development work of a physical one-dimensional two-fluid model that is based on Separation of the Flow According to Velocity (SFAV). The conventional way to model one-dimensional two-phase flow is to derive conservation equations for mass, momentum and energy over the regions occupied by the phases. In the SFAV approach, the two-phase mixture is divided into two subflows, with as distinct average velocities as possible, and momentum conservation equations are derived over their domains. Mass and energy conservation are treated equally with the conventional model because they are distributed very accurately according to the phases, but momentum fluctuations follow better the flow velocity. Submodels for non-uniform transverse profile of velocity and density, slip between the phases within each subflow and turbulence between the subflows have been derived. The model system is hyperbolic in any sensible flow conditions over the whole range of void fraction. Thus, it can be solved with accurate numerical methods utilizing the characteristics. The characteristics agree well with the used experimental data on two-phase flow wave phenomena Furthermore, the characteristics of the SFAV model are as well in accordance with their physical counterparts as of the best virtual-mass models that are typically optimized for special flow regimes like bubbly flow. The SFAV model has proved to be applicable in describing two-phase flow physically correctly because both the dynamics and steady-state behaviour of the model has been considered and found to agree well with experimental data This makes the SFAV model especially suitable for the calculation of fast transients, taking place in versatile form e.g. in nuclear reactors. 45 refs. The thesis includes also five previous publications by author.
Institute of Scientific and Technical Information of China (English)
袁益让
1999-01-01
For compressible two-phase displacement problem, a kind of characteristic finite difference fractional steps schemes is put forward and thick and thin grids are used to form a complete set. Some techniques, such as piecewise biquadratic interpolation, of calculus of variations, multiplicative commutation rule of difference operators, decomposition of high order difference operators and prior estimates are adopted. Optimal order estimates in L~2 norm are derived to determine the error in the approximate solution.
Homogenization of. beta. -solid solution during fast heating of two-phase titanium alloys
Energy Technology Data Exchange (ETDEWEB)
Gridnev, V.N.; Zhuravlev, A.F.; Zhuravlev, B.F.; Ivasishin, O.M.; Markovskij, P.E. (AN Ukrainskoj SSR, Kiev. Inst. Metallofiziki)
1985-01-01
Using model alloy Ti-10%Mo as an example the homogenization of high-temperature ..beta..-phase during fast heating has been studied by calculational and experimental methods. The effect of heating rate and the initial structure disoersion on the homogenization is shown. A method is suggested for evaluation of the concentration state of ..beta..-solid solution depleted parts of commercial two-phase titanium alloys. The method has been used to study the homogenization process.
Heat transfer performance of two-phase closed thermosyphon with oxidized CNT/water nanofluids
Zeinali Heris, Saeed; Fallahi, Marjan; Shanbedi, Mehdi; Amiri, Ahmad
2016-01-01
In this paper, the effects of different acids on the thermal performance of oxidized carbon nanotubes (CNT)/water nanofluids in a two-phase closed thermosyphon were studied. The structures morphology and functionalization degree were studied concurrently. The results indicated that strong oxidants increased dispersivity of CNT in the nanofluids. In other words, as the number of COOH groups increased in the nanofluids, an upward trend was also observed in the thermal efficiency of the thermosyphon.