WorldWideScience

Sample records for net gas flow

  1. Turbulent mixing between subchannels in a gas-liquid two-phase flow. For the equilibrium flow without net fluid transfer between subchannels

    International Nuclear Information System (INIS)

    Kawahara, Akimaro; Sadatomi, Michio; Sato, Yoshifusa; Saito, Hidetoshi.

    1995-01-01

    To provide data necessary for modeling turbulent mixing between subchannels in a nuclear fuel rod bundle, three experiments were made in series for equilibrium two-phase flows, in which net mass exchange does not occur between subchannels for each phase. The first one was the measurement of turbulent mixing rates of both gas and liquid phases by a tracer technique, using air and water as the working fluids. Three kinds of vertical test channels consisting of two subchannels were used. The data have shown that the turbulent mixing rate of each phase in a two-phase flow is strongly dependent on flow regime. So, to see the relation between turbulent mixing and two-phase flow configuration in the subchannels, the second experiment, flow visualization, was made. It was observed in slug and churn flows that a lateral inter-subchannel liquid flow of a large scale is caused by the successive axial transit of large gas bubbles in each subchannel, and the turbulent mixing for the liquid phase is dominated by this lateral flow. To investigate a driving force of such large scale lateral flow, the third experiment, the measurement of an instantaneous pressure differential between the subchannels, was made. The result showed that there is a close relationship between the liquid phase mixing rate and the magnitude of the pressure differential fluctuation. (author)

  2. Net global warming potential and greenhouse gas intensity

    Science.gov (United States)

    Various methods exist to calculate global warming potential (GWP) and greenhouse gas intensity (GHG) as measures of net greenhouse gas (GHG) emissions from agroecosystems. Little is, however, known about net GWP and GHGI that account for all sources and sinks of GHG emissions. Sources of GHG include...

  3. Gas Flow Detection System

    Science.gov (United States)

    Moss, Thomas; Ihlefeld, Curtis; Slack, Barry

    2010-01-01

    This system provides a portable means to detect gas flow through a thin-walled tube without breaking into the tubing system. The flow detection system was specifically designed to detect flow through two parallel branches of a manifold with only one inlet and outlet, and is a means for verifying a space shuttle program requirement that saves time and reduces the risk of flight hardware damage compared to the current means of requirement verification. The prototype Purge Vent and Drain Window Cavity Conditioning System (PVD WCCS) Flow Detection System consists of a heater and a temperature-sensing thermistor attached to a piece of Velcro to be attached to each branch of a WCCS manifold for the duration of the requirement verification test. The heaters and thermistors are connected to a shielded cable and then to an electronics enclosure, which contains the power supplies, relays, and circuit board to provide power, signal conditioning, and control. The electronics enclosure is then connected to a commercial data acquisition box to provide analog to digital conversion as well as digital control. This data acquisition box is then connected to a commercial laptop running a custom application created using National Instruments LabVIEW. The operation of the PVD WCCS Flow Detection System consists of first attaching a heater/thermistor assembly to each of the two branches of one manifold while there is no flow through the manifold. Next, the software application running on the laptop is used to turn on the heaters and to monitor the manifold branch temperatures. When the system has reached thermal equilibrium, the software application s graphical user interface (GUI) will indicate that the branch temperatures are stable. The operator can then physically open the flow control valve to initiate the test flow of gaseous nitrogen (GN2) through the manifold. Next, the software user interface will be monitored for stable temperature indications when the system is again at

  4. Fundamentals of gas particle flow

    CERN Document Server

    Rudinger, G

    1980-01-01

    Fundamentals of Gas-Particle Flow is an edited, updated, and expanded version of a number of lectures presented on the "Gas-Solid Suspensions” course organized by the von Karman Institute for Fluid Dynamics. Materials presented in this book are mostly analytical in nature, but some experimental techniques are included. The book focuses on relaxation processes, including the viscous drag of single particles, drag in gas-particles flow, gas-particle heat transfer, equilibrium, and frozen flow. It also discusses the dynamics of single particles, such as particles in an arbitrary flow, in a r

  5. Thermosensitive gas flow sensor

    International Nuclear Information System (INIS)

    Berlicki, T.; Osadnik, S.; Prociow, E.

    1997-01-01

    Results of investigations on thermal gas flow sensor have been presented. The sensor consists of three thin film resistors Si+Ta. The circuit was designed in the form of two bridges; one of them serves for measurement of the heater temperature, the second one for the measurement of temperature difference of peripheral resistors. The measurement of output voltage versus the rate of nitrogen flow at various power levels dissipated at the heater and various temperatures have been made. The measurements were carried out in three versions; (a) at constant temperature of the heater, (b) at constant power dissipated in the heater, controlled by the power of the heater, (c) at constant temperature of the heater controlled by the power dissipated in the peripheral resistors of the sensor. Due to measurement range it is advantageous to stabilize the temperature of the heater, especially by means of the power supplied to the peripheral resistors. In this case the wider measurement range can be obtained. (author)

  6. Communication nets stochastic message flow and delay

    CERN Document Server

    Kleinrock, Leonard

    2007-01-01

    Considerable research has been devoted to the formulation and solution of problems involving flow within connected networks. Independent of these surveys, an extensive body of knowledge has accumulated on the subject of queues, particularly in regard to stochastic flow through single-node servicing facilities. This text combines studies of connected networks with those of stochastic flow, providing a basis for understanding the general behavior and operation of communication networks in realistic situations.Author Leonard Kleinrock of the Computer Science Department at UCLA created the basic p

  7. Gas/liquid flow configurations

    International Nuclear Information System (INIS)

    Bonin, Jacques; Fitremann, J.-M.

    1978-01-01

    Prediction of flow configurations (morphology) for gas/liquid or liquid/vapour mixtures is an important industrial problem which is not yet fully understood. The ''Flow Configurations'' Seminar of Societe Hydrotechnique de France has framed recommendations for investigation of potential industrial applications for flow configurations [fr

  8. Translating Colored Control Flow Nets into Readable Java via Annotated Java Workflow Nets

    DEFF Research Database (Denmark)

    Lassen, Kristian Bisgaard; Tjell, Simon

    2007-01-01

    In this paper, we present a method for developing Java applications from Colored Control Flow Nets (CCFNs), which is a special kind of Colored Petri Nets (CPNs) that we introduce. CCFN makes an explicit distinction between the representation of: The system, the environment of the system, and the ......In this paper, we present a method for developing Java applications from Colored Control Flow Nets (CCFNs), which is a special kind of Colored Petri Nets (CPNs) that we introduce. CCFN makes an explicit distinction between the representation of: The system, the environment of the system......, and the interface between the system and the environment. Our translation maps CCFNs into Anno- tated Java Workflow Nets (AJWNs) as an intermediate step, and these AJWNs are finally mapped to Java. CCFN is intended to enforce the modeler to describe the system in an imperative manner which makes the subsequent...... translation to Java easier to define. The translation to Java preserves data dependencies and control-flow aspects of the source CCFN. This paper contributes to the model-driven software development paradigm, by showing how to model a system, environment, and their interface, as a CCFN and presenting a fully...

  9. Detekce provozu Skype pomocí dat NetFlow

    OpenAIRE

    Šebeň, Patrik

    2012-01-01

    NetFlow je sieťový protokol bežne používaný k zberu informácií o IP tokoch. Avšak existuje možnosť, ako použiť tieto zachytené dáta k identifikácií klientov v Skype komunikácií. Táto práca pojednáva o identifikácií určitých vzorov v Skype protokole a ich detekcií v NetFlow dátach. Týmto spôsobom sme schopný identifikovať nódy a supernódy v sieti Skype. NetFlow is a network protocol commonly used for collectiong IP traffic information. But there is a way to use this collected data for inden...

  10. Simulation of distribution nets for natural gas, in stationary state considering the compressible effects

    International Nuclear Information System (INIS)

    Valbuena C, Javier

    1997-01-01

    The general method is presented to calculate the losses of pressure in a RTD starting from the geometry of the net (diameter and longitude), of the real behavior of the gas, of the ruggedness of the pipe and of the flow, considering the compressibility of the fluid so much as the influence of the compressible effects. The simulation method is derived of the principles of conservation of mass and energy for a gas that follows a reversible poly tropic process of stable state and stable flow - stationary regime

  11. Radial flow gas dynamic laser

    International Nuclear Information System (INIS)

    Damm, F.C.

    1975-01-01

    The unique gas dynamic laser provides outward radial supersonic flow from a toroidal shaped stacked array of a plurality of nozzles, through a diffuser having ring shaped and/or linear shaped vanes, and through a cavity which is cylindrical and concentric with the stacked array, with the resultant laser beam passing through the housing parallel to the central axis of the diffuser which is coincident with the axis of the gas dynamic laser. Therefore, greater beam extraction flexibility is attainable, because of fewer flow shock disturbances, as compared to the conventional unidirectional flow gas dynamic laser in which unidirectional supersonic flow sweeps through a rectangular cavity and is exhausted through a two-dimensional diffuser. (auth)

  12. Petri net modeling of encrypted information flow in federated cloud

    Science.gov (United States)

    Khushk, Abdul Rauf; Li, Xiaozhong

    2017-08-01

    Solutions proposed and developed for the cost-effective cloud systems suffer from a combination of secure private clouds and less secure public clouds. Need to locate applications within different clouds poses a security risk to the information flow of the entire system. This study addresses this by assigning security levels of a given lattice to the entities of a federated cloud system. A dynamic flow sensitive security model featuring Bell-LaPadula procedures is explored that tracks and authenticates the secure information flow in federated clouds. Additionally, a Petri net model is considered as a case study to represent the proposed system and further validate the performance of the said system.

  13. Wet gas metering with the v-cone and neural nets

    Energy Technology Data Exchange (ETDEWEB)

    Toral, Haluk; Cai, Shiqian; Peters, Robert

    2005-07-01

    The paper presents analysis of extensive measurements taken at NEL, K-Lab and CEESI wet gas test loops. Differential and absolute pressure signals were sampled at high frequency across V-Cone meters. Turbulence characteristics of the flow captured in the sampled signals were characterized by pattern recognition techniques and related to the fractions and flow rates of individual phases. The sensitivity of over-reading to first and higher order features of the high frequency signals were investigated qualitatively. The sensitivities were quantified by means of the saliency test based on back propagating neural nets. A self contained wet gas meter based on neural net characterization of first and higher order features of the pressure, differential pressure and capacitance signals was proposed. Alternatively, a wet gas meter based on a neural net model of just pressure sensor inputs (based on currently available data) and liquid Froude number was shown to offer an accuracy of under 5% if the Froude number could be estimated with 25% accuracy. (author) (tk)

  14. Stochastic flows in the Brownian web and net

    Czech Academy of Sciences Publication Activity Database

    Schertzer, E.; Sun, R.; Swart, Jan M.

    2014-01-01

    Roč. 227, č. 1065 (2014), s. 1-160 ISSN 0065-9266 R&D Projects: GA ČR GA201/07/0237; GA ČR GA201/09/1931 Institutional support: RVO:67985556 Keywords : Brownian web * Brownian net * stochastic flow of kernels * measure-valued process * Howitt-Warren flow * linear system * random walk in random environment * finite graph representation Subject RIV: BA - General Mathematics Impact factor: 1.727, year: 2014 http://library.utia.cas.cz/separaty/2013/SI/swart-0396636.pdf

  15. Adiabatic gas-liquid flow

    International Nuclear Information System (INIS)

    Mayinger, F.

    1982-01-01

    The author starts by discussing the gas-fluidic mixture, its application and its special characteristics. The conservation theorems for these mixtures are then presented, including the continuity equation, the impulse equation, and energy balance. The type of flow in vertical channels, vertical downwards flow and flow in horizontal and inclined tubes is discussed followed by a short section on local volumetric steam contents and slip. The expressions for the slip and for the local volumetric steam contents are explained before discussing phase separation in nonflowing fluids. Pressure loss in tubes and channels is followed by discussion of pressure loss in various types of moulded bodies with particular reference to fuel rod bundles. In conclusion the author discusses pressure wave expansion, critical discharge and cross exchange in sub-divided channels. (A.N.K.)

  16. Intelligent gas-mixture flow sensor

    NARCIS (Netherlands)

    Lammerink, Theodorus S.J.; Dijkstra, Fred; Houkes, Z.; van Kuijk, J.C.C.; van Kuijk, Joost

    A simple way to realize a gas-mixture flow sensor is presented. The sensor is capable of measuring two parameters from a gas flow. Both the flow rate and the helium content of a helium-nitrogen gas mixture are measured. The sensor exploits two measurement principles in combination with (local)

  17. Measuring Cloud Service Health Using NetFlow/IPFIX

    DEFF Research Database (Denmark)

    Drago, Idilio; Hofstede, Rick; Sadre, Ramin

    2015-01-01

    The increasing trend of outsourcing services to cloud providers is changing the way computing power is delivered to enterprises and end users. Although cloud services offer several advantages, they also make cloud consumers strongly dependent on providers. Hence, consumers have a vital interest...... to be immediately informed about any problems in their services. This paper aims at a first step toward a network-based approach to monitor cloud services. We focus on severe problems that affect most services, such as outages or extreme server overload, and propose a method to monitor these problems that relies...... solely on the traffic exchanged between users and cloud providers. Our proposal is entirely based on NetFlow/IPFIX data and, therefore, explicitly targets high-speed networks. By combining a methodology to reassemble and classify flow records with stochastic estimations, our proposal has the distinct...

  18. Theoretical study of inspiratory flow waveforms during mechanical ventilation on pulmonary blood flow and gas exchange.

    Science.gov (United States)

    Niranjan, S C; Bidani, A; Ghorbel, F; Zwischenberger, J B; Clark, J W

    1999-08-01

    A lumped two-compartment mathematical model of respiratory mechanics incorporating gas exchange and pulmonary circulation is utilized to analyze the effects of square, descending and ascending inspiratory flow waveforms during mechanical ventilation. The effects on alveolar volume variation, alveolar pressure, airway pressure, gas exchange rate, and expired gas species concentration are evaluated. Advantages in ventilation employing a certain inspiratory flow profile are offset by corresponding reduction in perfusion rates, leading to marginal effects on net gas exchange rates. The descending profile provides better CO2 exchange, whereas the ascending profile is more advantageous for O2 exchange. Regional disparities in airway/lung properties create maldistribution of ventilation and a concomitant inequality in regional alveolar gas composition and gas exchange rates. When minute ventilation is maintained constant, for identical time constant disparities, inequalities in compliance yield pronounced effects on net gas exchange rates at low frequencies, whereas the adverse effects of inequalities in resistance are more pronounced at higher frequencies. Reduction in expiratory air flow (via increased airway resistance) reduces the magnitude of upstroke slope of capnogram and oxigram time courses without significantly affecting end-tidal expired gas compositions, whereas alterations in mechanical factors that result in increased gas exchanges rates yield increases in CO2 and decreases in O2 end-tidal composition values. The model provides a template for assessing the dynamics of cardiopulmonary interactions during mechanical ventilation by combining concurrent descriptions of ventilation, capillary perfusion, and gas exchange. Copyright 1999 Academic Press.

  19. Advances in gas-liquid flows 1990

    International Nuclear Information System (INIS)

    Kim, J.M.; Hashemi, A.

    1990-01-01

    Gas-liquid two-phase flows commonly occur in nature and industrial applications. Rain, clouds, geysers, and waterfalls are examples of natural gas-liquid flow phenomena, whereas industrial applications can be found in nuclear reactors, steam generators, boilers, condensers, evaporators, fuel atomization, heat pipes, electronic equipment cooling, petroleum engineering, chemical process engineering, and many others. The household-variety phenomena such as garden sprinklers, shower, whirlpool bath, dripping faucet, boiling tea pot, and bubbling beer provide daily experience of gas-liquid flows. The papers presented in this volume reflect the variety and richness of gas-liquid two-phase flow and the increasing role it plays in modern technology. This volume contains papers dealing with some recent development in gas-liquid flow science and technology, covering basic gas-liquid flows, measurements and instrumentation, cavitation and flashing flows, countercurrent flow and flooding, flow in various components and geometries liquid metals and thermocapillary effects, heat transfer, nonlinear phenomena, instability, and other special and general topics related to gas-liquid flows

  20. Stirling Engine with Unidirectional Gas Flow

    OpenAIRE

    Blumbergs, Ilmars

    2014-01-01

    In this study, a Stirling engine with unidirectional gas flow configuration of beta type Stirling engine is described and studied from kinematic and thermodynamics points of view. Some aspects of the Stirling engine with unidirectional gas flow engine are compared to classic beta type Stirling engines. The aim of research has been to develop a new type of Stirling engine, using SolidWorks 3D design software and Flow Simulation software. In the development process, special attention has been d...

  1. Net greenhouse gas emissions at Eastmain-1 reservoir, Quebec, Canada

    Energy Technology Data Exchange (ETDEWEB)

    Tremblay, Alain; Bastien, Julie; Bonneville, Marie-Claude; del Giorgio, Paul; Demarty, Maud; Garneau, Michelle; Helie, Jean-Francois; Pelletier, Luc; Prairie, Yves; Roulet, Nigel; Strachan, Ian; Teodoru, Cristian

    2010-09-15

    The growing concern regarding the long-term contribution of freshwater reservoirs to atmospheric greenhouse gases (GHG), led Hydro-Quebec, to study net GHG emissions from Eastmain 1 reservoir, which are the emissions related to the creation of a reservoir minus those that would have been emitted or absorbed by the natural systems over a 100-year period. This large study was realized in collaboration with University du Quebec a Montreal, McGill University and Environnement IIlimite Inc. This is a world premiere and the net GHG emissions of EM-1 will be presented in details.

  2. Prediction model for initial point of net vapor generation for low-flow boiling

    International Nuclear Information System (INIS)

    Sun Qi; Zhao Hua; Yang Ruichang

    2003-01-01

    The prediction of the initial point of net vapor generation is significant for the calculation of phase distribution in sub-cooled boiling. However, most of the investigations were developed in high-flow boiling, and there is no common model that could be successfully applied for the low-flow boiling. A predictive model for the initial point of net vapor generation for low-flow forced convection and natural circulation is established here, by the analysis of evaporation and condensation heat transfer. The comparison between experimental data and calculated results shows that this model can predict the net vapor generation point successfully in low-flow sub-cooled boiling

  3. Membrane barriers for radon gas flow restrictions

    International Nuclear Information System (INIS)

    Archibald, J.F.

    1984-08-01

    Research was performed to assess the feasibility of barrier membrane substances, for use within mining or associated high risk environments, in restricting the diffusion transport of radon gas quantities. Specific tests were conducted to determine permeability parameters of a variety of membrane materials with reference to radon flow capabilities. Tests were conducted both within laboratory and in-situ emanation environments where concentrations and diffusion flows of radon gas were known to exist. Equilibrium radon gas concentrations were monitored in initially radon-free chambers adjacent to gas sources, but separated by specified membrane substances. Membrane barrier effectiveness was demonstrated to result in reduced emanation concentrations of radon gas within the sampling chamber atmosphere. Minimum gas concentrations were evidenced where the barrier membrane material was shown to exhibit lowest radon permeability characteristics

  4. Gas and Oil Flow through Wellbore Flaws

    Science.gov (United States)

    Hatambeigi, M.; Anwar, I.; Reda Taha, M.; Bettin, G.; Chojnicki, K. N.; Stormont, J.

    2017-12-01

    We have measured gas and oil flow through laboratory samples that represent two important potential flow paths in wellbores associated with the Strategic Petroleum Reserve (SPR): cement-steel interfaces (microannuli) and cement fractures. Cement fractures were created by tensile splitting of cement cores. Samples to represent microannuli were created by placing thin steel sheets within split cement cores so flow is channeled along the cement-steel interface. The test sequence included alternating gas and oil flow measurements. The test fluids were nitrogen and silicone oil with properties similar to a typical crude oil stored in the SPR. After correcting for non-linear (inertial) flow when necessary, flows were interpreted as effective permeability and hydraulic aperture using the cubic law. For both samples with cement fractures and those with cement-steel interfaces, initial gas and oil permeabilities were comparable. Once saturated with oil, a displacement pressure had to be overcome to establish gas flow through a sample, and the subsequent gas permeability were reduced by more than 50% compared to its initial value. Keywords: wellbore integrity, leakage, fracture, microannulus, SPR. Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of NTESS/Honeywell, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND2017-8168 A

  5. Cash flow is cash and is a fact. Net income is just an opinion

    OpenAIRE

    Fernandez, Pablo

    2006-01-01

    A company's profit after tax (or net income) is quite an arbitrary figure, obtained after assuming certain accounting hypotheses regarding expenses and revenues. On the other hand, its cash flow is an objective measure, a single figure that is not subject to any personal criterion. In general, to study a company's situation, it is more useful to operate with the cash flow (equity cash flow, free cash flow or capital cash flow) as it is a single figure, while the net income is one of several t...

  6. Systems principles of planning the net cost of oil and gas extraction

    Energy Technology Data Exchange (ETDEWEB)

    Ryazanova, N I

    1979-01-01

    The automated system of calculation of ASPC ''oil extraction'' is developed in order to improve the existing system of planning of the oil extracting sector. The most complete expression of the systems construction of the plan is found in the section ''net cost and profit.'' Unity of the production process advances definite requirements for construction of the plan for net cost of oil and gas extraction as the model of this unified process. According to these requirements, the plan for net cost must be developed on the basis of interrelationship of the indicators of the plan for net cost within the section and with indicators of other sections of the plan, methodological unity and continuity of the methods of planning net cost by elements of outlays, articles of calculation and technical-economic factors, methodological continuity of regimes and stages of planning, as well as based on methodological continuity of the control levels. The listed requirements are principles for systems planning of the net cost of oil and gas extraction. These principles guarantee improvement in planning of net cost of oil and gas extraction according to the requirements made for the national economic planning.

  7. Open critical area model and extraction algorithm based on the net flow-axis

    International Nuclear Information System (INIS)

    Wang Le; Wang Jun-Ping; Gao Yan-Hong; Xu Dan; Li Bo-Bo; Liu Shi-Gang

    2013-01-01

    In the integrated circuit manufacturing process, the critical area extraction is a bottleneck to the layout optimization and the integrated circuit yield estimation. In this paper, we study the problem that the missing material defects may result in the open circuit fault. Combining the mathematical morphology theory, we present a new computation model and a novel extraction algorithm for the open critical area based on the net flow-axis. Firstly, we find the net flow-axis for different nets. Then, the net flow-edges based on the net flow-axis are obtained. Finally, we can extract the open critical area by the mathematical morphology. Compared with the existing methods, the nets need not to divide into the horizontal nets and the vertical nets, and the experimental results show that our model and algorithm can accurately extract the size of the open critical area and obtain the location information of the open circuit critical area. (interdisciplinary physics and related areas of science and technology)

  8. Inhalational anaesthesia with low fresh gas flow

    Directory of Open Access Journals (Sweden)

    Christian Hönemann

    2013-01-01

    Full Text Available During the inhalation of anaesthesia use of low fresh gas flow (0.35-1 L/min has some important advantages. There are three areas of benefit: pulmonary - anaesthesia with low fresh gas flow improves the dynamics of inhaled anaesthesia gas, increases mucociliary clearance, maintains body temperature and reduces water loss. Economic - reduction of anaesthesia gas consumption resulting in significant savings of > 75% and Ecological - reduction in nitrous oxide consumption, which is an important ozone-depleting and heat-trapping greenhouse gas that is emitted. Nevertheless, anaesthesia with high fresh gas flows of 2-6 L/min is still performed, a technique in which rebreathing is practically negligible. This special article describes the clinical use of conventional plenum vaporizers, connected to the fresh gas supply to easily perform low (1 L/min, minimal (0.5 L/min or metabolic flow anaesthesia (0.35 L/min with conventional Primus Draeger® anaesthesia machines in routine clinical practice.

  9. Limiting net greenhouse gas emissions in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, R A; Watts, E C; Williams, E R [eds.

    1991-09-01

    In 2988 the Congress requested DOE produce a study on carbon dioxide inventory and policy to provide an inventory of emissions sources and to analyze policies to achieve a 20% reduction in carbon dioxide emissions in 5 to 10 years and a 50% reduction in 15 to 20 years. This report presents the results of that study. Energy and environmental technology data were analyzed using computational analysis models. This information was then evaluated, drawing on current scientific understanding of global climate change, the possible consequences of anthropogenic climate change (change caused by human activity), and the relationship between energy production and use and the emission of radiactively important gases. Topics discussed include: energy and environmental technology to reduce greenhouse gas emissions, fossil energy production and electricity generation technologies, nuclear energy technology, renewable energy technologies, energy storage, transmission, and distribution technology, transportation, technology, industrial technology, residential and commercial building technology, greenhouse gas removal technology, approaches to restructuring the demand for energy.

  10. Risk Exposure and Net Flow in Investment Funds: Do Shareholders Monitor Asset Allocation?

    Directory of Open Access Journals (Sweden)

    Rafael Felipe Schiozer

    2014-03-01

    Full Text Available This study investigates the impact of asset allocation on the net flow of fixed income funds in the Brazilian market, by exploiting the exogenous variation in the risk perception of bank liabilities (CDs caused by the financial turmoil that followed Lehman Brothers’ demise in September 2008. The central hypothesis is that the exposure to assets negatively affected by the crisis impacts negatively the fund’s net flow. We find that, for mutual funds, the larger proportion of assets negatively affected by the crisis the larger the net outflow of resources, indicating that shareholders monitor asset allocation and exert disciplining power on fund managers by withdrawing their resources. In exclusive (fundos exclusivos, i.e., funds with a single shareholder, for which the shareholder is presumed to exert more influence on asset reallocation, we find no significant relationship between the exposure to assets negatively affected by the crisis and net flows.

  11. Gas flow headspace liquid phase microextraction.

    Science.gov (United States)

    Yang, Cui; Qiu, Jinxue; Ren, Chunyan; Piao, Xiangfan; Li, Xifeng; Wu, Xue; Li, Donghao

    2009-11-06

    There is a trend towards the use of enrichment techniques such as microextraction in the analysis of trace chemicals. Based on the theory of ideal gases, theory of gas chromatography and the original headspace liquid phase microextraction (HS-LPME) technique, a simple gas flow headspace liquid phase microextraction (GF-HS-LPME) technique has been developed, where the extracting gas phase volume is increased using a gas flow. The system is an open system, where an inert gas containing the target compounds flows continuously through a special gas outlet channel (D=1.8mm), and the target compounds are trapped on a solvent microdrop (2.4 microL) hanging on the microsyringe tip, as a result, a high enrichment factor is obtained. The parameters affecting the enrichment factor, such as the gas flow rate, the position of the microdrop, the diameter of the gas outlet channel, the temperatures of the extracting solvent and of the sample, and the extraction time, were systematically optimized for four types of polycyclic aromatic hydrocarbons. The results were compared with results obtained from HS-LPME. Under the optimized conditions (where the extraction time and the volume of the extracting sample vial were fixed at 20min and 10mL, respectively), detection limits (S/N=3) were approximately a factor of 4 lower than those for the original HS-LPME technique. The method was validated by comparison of the GF-HS-LPME and HS-LPME techniques using data for PAHs from environmental sediment samples.

  12. Gas transfer in a bubbly wake flow

    Science.gov (United States)

    Karn, A.; Gulliver, J. S.; Monson, G. M.; Ellis, C.; Arndt, R. E. A.; Hong, J.

    2016-05-01

    The present work reports simultaneous bubble size and gas transfer measurements in a bubbly wake flow of a hydrofoil, designed to be similar to a hydroturbine blade. Bubble size was measured by a shadow imaging technique and found to have a Sauter mean diameter of 0.9 mm for a reference case. A lower gas flow rate, greater liquid velocities, and a larger angle of attack all resulted in an increased number of small size bubbles and a reduced weighted mean bubble size. Bubble-water gas transfer is measured by the disturbed equilibrium technique. The gas transfer model of Azbel (1981) is utilized to characterize the liquid film coefficient for gas transfer, with one scaling coefficient to reflect the fact that characteristic turbulent velocity is replaced by cross-sectional mean velocity. The coefficient was found to stay constant at a particular hydrofoil configuration while it varied within a narrow range of 0.52-0.60 for different gas/water flow conditions.

  13. Reduction of gas flow nonuniformity in gas turbine engines by means of gas-dynamic methods

    Science.gov (United States)

    Matveev, V.; Baturin, O.; Kolmakova, D.; Popov, G.

    2017-08-01

    Gas flow nonuniformity is one of the main sources of rotor blade vibrations in the gas turbine engines. Usually, the flow circumferential nonuniformity occurs near the annular frames, located in the flow channel of the engine. This leads to the increased dynamic stresses in blades and as a consequence to the blade damage. The goal of the research was to find an acceptable method of reducing the level of gas flow nonuniformity as the source of dynamic stresses in the rotor blades. Two different methods were investigated during this research. Thus, this study gives the ideas about methods of improving the flow structure in gas turbine engine. On the basis of existing conditions (under development or existing engine) it allows the selection of the most suitable method for reducing gas flow nonuniformity.

  14. Transient gas flow through layered porous media

    International Nuclear Information System (INIS)

    Morrison, F.A. Jr.

    1975-01-01

    Low Reynolds number isothermal flow of an ideal gas through layered porous material was investigated analytically. Relations governing the transient flow in one dimension are obtained. An implicit, iterative, unconditionally stable finite difference scheme is developed for calculation of such flows. A computer code, SIROCCO, employing this technique has been written and implemented on the LLL computer system. A listing of the code is included. This code may be effectively applied to the evaluation of stemming plans for underground nuclear experiments. (U.S.)

  15. Limiting net greenhouse gas emissions in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, R A; Watts, E C; Williams, E R [eds.

    1991-09-01

    In 1988, Congress requested that DOE produce a study on carbon dioxide inventory and policy to provide an inventory of emissions sources and to analyze policies to achieve a 20% reduction in carbon dioxide emissions in 5 to 10 years and a 50% reduction in 15 to 20 years. Energy and environmental technology data were analyzed using computational analysis models. This information was then evaluated, drawing on current scientific understanding of global climate change, the possible consequences of anthropogenic climate change (change caused by human activity) and the relationship between energy production and use and the emission of radiatively important gases. Topics discussed include: state of the science in estimating atmosphere/climate change relationships, the potential consequences of atmosphere/climate change, us greenhouse emissions past and present, an approach to analyzing the technical potential and cost of reducing US energy-related greenhouse gas emissions, current policy base and National Energy Strategy actions, fiscal instruments, regulatory instruments, combined strategies and instruments, macroeconomic impacts, carbon taxation and international trade, a comparison to other studies.

  16. Heat transfer to accelerating gas flows

    International Nuclear Information System (INIS)

    Kennedy, T.D.A.

    1978-01-01

    The development of fuels for gas-cooled reactors has resulted in a number of 'gas loop' experiments in materials-testing research reactors. In these experiments, efforts are made to reproduce the conditions expected in gas-cooled power reactors. Constant surface temperatures are sought over a short (300 mm) fuelled length, and because of entrance effects, an accelerating flow is required to increase the heat transfer down-stream from the entrance. Strong acceleration of a gas stream will laminarise the flow even at Reynolds Numbers up to 50000, far above values normally associated with laminar flow. A method of predicting heat transfer in this situation is presented here. An integral method is used to find the velocity profile; this profile is then used in an explicit finite-difference solution of the energy equation to give a temperature profile and resultant heat-transfer coefficient values. The Kline criterion, which compares viscous and disruptive forces, is used to predict whether the flow will be laminar. Experimental results are compared with predictions, and good agreement is found to exist. (author)

  17. Pressure calculations in nanochannel gas flows

    NARCIS (Netherlands)

    Kim, J.H.; Frijns, A.J.H.; Nedea, S.V.; Steenhoven, van A.A.; Frijns, A.J.H.; Valougeorgis, D.; Colin, S.; Baldas, L.

    2012-01-01

    In this research, pressure driven flow within a nanochannel is studied for argon in rarefied gas states. A Molecular Dynamics simulation is used to resolve the density and stress variations. Normal stress calculations are based on Irving-Kirkwood method, which divides the stress tensor into its

  18. Surface Effects on Nanoscale Gas Flows

    Science.gov (United States)

    Beskok, Ali; Barisik, Murat

    2010-11-01

    3D MD simulations of linear Couette flow of argon gas confined within nano-scale channels are performed in the slip, transition and free molecular flow regimes. The velocity and density profiles show deviations from the kinetic theory based predictions in the near wall region that typically extends three molecular diameters (s) from each surface. Utilizing the Irwin-Kirkwood theorem, stress tensor components for argon gas confined in nano-channels are investigated. Outside the 3s region, three normal stress components are identical, and equal to pressure predicted using the ideal gas law, while the shear stress is a constant. Within the 3s region, the normal stresses become anisotropic and the shear stress shows deviations from its bulk value due to the surface virial effects. Utilizing the kinetic theory and MD predicted shear stress values, the tangential momentum accommodation coefficient for argon gas interacting with FCC structured walls (100) plane facing the fluid is calculated to be 0.75; this value is independent of the Knudsen number. Results show emergence of the 3s region as an additional characteristic length scale in nano-confined gas flows.

  19. Generation of net sediment transport by velocity skewness in oscillatory sheet flow

    Science.gov (United States)

    Chen, Xin; Li, Yong; Chen, Genfa; Wang, Fujun; Tang, Xuelin

    2018-01-01

    This study utilizes a qualitative approach and a two-phase numerical model to investigate net sediment transport caused by velocity skewness beneath oscillatory sheet flow and current. The qualitative approach is derived based on the pseudo-laminar approximation of boundary layer velocity and exponential approximation of concentration. The two-phase model can obtain well the instantaneous erosion depth, sediment flux, boundary layer thickness, and sediment transport rate. It can especially illustrate the difference between positive and negative flow stages caused by velocity skewness, which is considerably important in determining the net boundary layer flow and sediment transport direction. The two-phase model also explains the effect of sediment diameter and phase-lag to sediment transport by comparing the instantaneous-type formulas to better illustrate velocity skewness effect. In previous studies about sheet flow transport in pure velocity-skewed flows, net sediment transport is only attributed to the phase-lag effect. In the present study with the qualitative approach and two-phase model, phase-lag effect is shown important but not sufficient for the net sediment transport beneath pure velocity-skewed flow and current, while the asymmetric wave boundary layer development between positive and negative flow stages also contributes to the sediment transport.

  20. The determination of the initial point of net vapor generation in flow subcooled boiling

    International Nuclear Information System (INIS)

    Yan Changqi; Sun Zhongning

    2000-01-01

    The experimental results for the initial point of net vapor generation in up-flow subcooled boiling in an internally-heated annulus are given. The characteristics of the initial point of net vapor generation and the problem on gamma ray attenuation measurement are discussed. The comparison between the data and a calculation model is given, it is showed that the data agree well with the model

  1. Net Income, Book Value and Cash Flows: The Value Relevance in Jordanian Economic Sectors

    Directory of Open Access Journals (Sweden)

    DHIAA SHAMKI

    2013-07-01

    Full Text Available This paper examines the value relevance of financial statements variables namely net income, book value and cash flows simultaneously relative to Jordanian services and industrial firms for the period from 2000 to 2009. The main findings of this paper are three- dimensional. First, net income is value relevant, while book value and cash flows are irrelevant. Second, net income is more value relevant than book value and cash flows in both sectors. Third, this value relevance is greater in services sector than in industrial sector. The study shows that net income assist more in explaining market values in Jordanian services and industrial firms. Since research on the value relevance of these variables has neglected Jordan (and the Middle Eastern region, the study tries to fill this practical gap. The study is the first in Jordan that examines the value relevance of net income, book value and cash flows simultaneously and compares this value relevance according to Amman Stock Exchange sectors in one study in Jordan.

  2. Gas Flow Across Gaps in Protoplanetary Disks

    OpenAIRE

    Lubow, Steve H.; D'Angelo, Gennaro

    2005-01-01

    We analyze the gas accretion flow through a planet-produced gap in a protoplanetary disk. We adopt the alpha disk model and ignore effects of planetary migration. We develop a semi-analytic, one-dimensional model that accounts for the effects of the planet as a mass sink and also carry out two-dimensional hydrodynamical simulations of a planet embedded in a disk. The predictions of the mass flow rate through the gap based on the semi-analytic model generally agree with the hydrodynamical simu...

  3. [Greenhouse gas emissions, carbon leakage and net carbon sequestration from afforestation and forest management: A review.

    Science.gov (United States)

    Liu, Bo Jie; Lu, Fei; Wang, Xiao Ke; Liu, Wei Wei

    2017-02-01

    Forests play an important role in climate change mitigation and concentration of CO 2 reduction in the atmosphere. Forest management, especially afforestation and forest protection, could increase carbon stock of forests significantly. Carbon sequestration rate of afforestation ranges from 0.04 to 7.52 t C·hm -2 ·a -1 , while that of forest protection is 0.33-5.20 t C·hm -2 ·a -1 . At the same time, greenhouse gas (GHG) is generated within management boundary due to the production and transportation of the materials consumed in relevant activities of afforestation and forest management. In addition, carbon leakage is also generated outside boundary from activity shifting, market effects and change of environments induced by forest management. In this review, we summarized the definition of emission sources of GHG, monitoring methods, quantity and rate of greenhouse gas emissions within boundary of afforestation and forest management. In addition, types, monitoring methods and quantity of carbon leakage outside boundary of forest management were also analyzed. Based on the reviewed results of carbon sequestration, we introduced greenhouse gas emissions within boundary and carbon leakage, net carbon sequestration as well as the countervailing effects of greenhouse gas emissions and carbon leakage to carbon sequestration. Greenhouse gas emissions within management boundary counteract 0.01%-19.3% of carbon sequestration, and such counteraction could increase to as high as 95% considering carbon leakage. Afforestation and forest management have substantial net carbon sequestration benefits, when only taking direct greenhouse gas emissions within boundary and measurable carbon leakage from activity shifting into consideration. Compared with soil carbon sequestration measures in croplands, afforestation and forest management is more advantageous in net carbon sequestration and has better prospects for application in terms of net mitigation potential. Along with the

  4. Numerical Analysis of Dusty-Gas Flows

    Science.gov (United States)

    Saito, T.

    2002-02-01

    This paper presents the development of a numerical code for simulating unsteady dusty-gas flows including shock and rarefaction waves. The numerical results obtained for a shock tube problem are used for validating the accuracy and performance of the code. The code is then extended for simulating two-dimensional problems. Since the interactions between the gas and particle phases are calculated with the operator splitting technique, we can choose numerical schemes independently for the different phases. A semi-analytical method is developed for the dust phase, while the TVD scheme of Harten and Yee is chosen for the gas phase. Throughout this study, computations are carried out on SGI Origin2000, a parallel computer with multiple of RISC based processors. The efficient use of the parallel computer system is an important issue and the code implementation on Origin2000 is also described. Flow profiles of both the gas and solid particles behind the steady shock wave are calculated by integrating the steady conservation equations. The good agreement between the pseudo-stationary solutions and those from the current numerical code validates the numerical approach and the actual coding. The pseudo-stationary shock profiles can also be used as initial conditions of unsteady multidimensional simulations.

  5. A modeling method of semiconductor fabrication flows with extended knowledge hybrid Petri nets

    Institute of Scientific and Technical Information of China (English)

    Zhou Binghai; Jiang Shuyu; Wang Shijin; Wu bin

    2008-01-01

    A modeling method of extended knowledge hybrid Petri nets (EKHPNs), incorporating object-oriented methods into hybrid Petri nets (HPNs), was presented and used for the representation and modeling of semiconductor wafer fabrication flows. To model the discrete and continuous parts of a complex semiconductor wafer fabrication flow, the HPNs were introduced into the EKHPNs. Object-oriented methods were combined into the EKHPNs for coping with the complexity of the fabrication flow. Knowledge annotations were introduced to solve input and output conflicts of the EKHPNs.Finally, to demonstrate the validity of the EKHPN method, a real semiconductor wafer fabrication case was used to illustrate the modeling procedure. The modeling results indicate that the proposed method can be used to model a complex semiconductor wafer fabrication flow expediently.

  6. Boiling, condensation, and gas-liquid flow

    International Nuclear Information System (INIS)

    Whalley, P.B.

    1987-01-01

    Heat transfer phenomena involving boiling and condensation are an important aspect of engineering in the power and process industries. This book, aimed at advanced first-degree and graduate students in mechanical and chemical engineering, deals with these phenomena in detail. The first part of the book describes gas-liquid two-phase flow, as a necessary preliminary to the later discussion of heat transfer and change of phase. A detailed section on calculation methods shows how theory can be put to practical use, and there are also descriptions of some of the equipment and plant used in the process and power industries

  7. Convection flow study within a horizontal fluid layer under the action of gas flow

    Directory of Open Access Journals (Sweden)

    Kreta Aleksei

    2016-01-01

    Full Text Available Experimental investigation of convective processes within horizontal evaporating liquid layer under shear–stress of gas flow is presented. It is found the structures of the convection, which move in opposite direction relative to each other. First convective structure moves in reverse direction with the flow of gas, and the second convective structure moves towards the gas flow. Convection flow within the liquid layer is registered with help of PIV technique. Average evaporation flow rate of Ethanol liquid layer under Air gas flow is measured. Influence of the gas velocity, at a constant temperature of 20 °C, on the evaporation flow rate has been studied.

  8. Can Switching from Coal to Shale Gas Bring Net Carbon Reductions to China?

    Science.gov (United States)

    Qin, Yue; Edwards, Ryan; Tong, Fan; Mauzerall, Denise L

    2017-03-07

    To increase energy security and reduce emissions of air pollutants and CO 2 from coal use, China is attempting to duplicate the rapid development of shale gas that has taken place in the United States. This work builds a framework to estimate the lifecycle greenhouse gas (GHG) emissions from China's shale gas system and compares them with GHG emissions from coal used in the power, residential, and industrial sectors. We find the mean lifecycle carbon footprint of shale gas is about 30-50% lower than that of coal in all sectors under both 20 year and 100 year global warming potentials (GWP 20 and GWP 100 ). However, primarily due to large uncertainties in methane leakage, the upper bound estimate of the lifecycle carbon footprint of shale gas in China could be approximately 15-60% higher than that of coal across sectors under GWP 20 . To ensure net GHG emission reductions when switching from coal to shale gas, we estimate the breakeven methane leakage rates to be approximately 6.0%, 7.7%, and 4.2% in the power, residential, and industrial sectors, respectively, under GWP 20 . We find shale gas in China has a good chance of delivering air quality and climate cobenefits, particularly when used in the residential sector, with proper methane leakage control.

  9. Managing soil organic carbon in agriculture: the net effect on greenhouse gas emissions

    International Nuclear Information System (INIS)

    Marland, Gregg; West, Tristram O.; Schlamadinger, Bernhard; Canella, Lorenza

    2003-01-01

    A change in agricultural practice can increase carbon sequestration in agricultural soils. To know the net effect on greenhouse gas emissions to the atmosphere, however, we consider associated changes in CO 2 emissions resulting from the consumption of fossil fuels, emissions of other greenhouse gases and effects on land productivity and crop yield. We also consider how these factors will evolve over time. A change from conventional tillage to no-till agriculture, based on data for average practice in the U.S.; will result in net carbon sequestration in the soil that averages 337 kg C/ha/yr for the initial 20 yr with a decline to near zero in the following 20 yr, and continuing savings in CO 2 emissions because of reduced use of fossil fuels. The long-term results, considering all factors, can generally be expected to show decreased net greenhouse gas emissions. The quantitative details, however, depend on the site-specific impact of the conversion from conventional to no-till agriculture on agricultural yield and N 2 O emissions from nitrogen fertilizer

  10. Net global warming potential and greenhouse gas intensity influenced by irrigation, tillage, crop rotation, and nitrogen fertilization

    Science.gov (United States)

    Little information exists about sources and sinks of greenhouse gases (GHGs) affected by management practices to account for net emissions from agroecosystems. We evaluated the effects of irrigation, tillage, crop rotation, and N fertilization on net global warming potential (GWP) and greenhouse gas...

  11. 1st European Conference on Gas Micro Flows (GasMems 2012)

    NARCIS (Netherlands)

    Frijns, A.J.H.; Valougeorgis, D.; Colin, S.; Baldas, L.

    2012-01-01

    PREFACE The aim of the 1st European Conference on Gas Micro Flows is to advance research in Europe and worldwide in the field of gas micro flows as well as to improve global fundamental knowledge and to enable technological applications. Gas flows in microsystems are of great importance and touch

  12. Using UML and Petri nets for visualization of business document flow

    Directory of Open Access Journals (Sweden)

    Ivana Rábová

    2012-01-01

    Full Text Available The article deals with two principles of business workflow modeling, Petri nets and UML notation, that are the acceptable approaches to business modeling and can be used also for business documents workflow. The special type of Petri nets, WF-nets and UML activity diagrams are used in this article and both modeling ways are presented on the concrete business workflow and then there are presented and specified their advantage and disadvantage for business documents flows. At beginning it is explained the word workflow in context business documents, its features, principles and using in business environment. After that it is clarified that the UML is OMG’s most-used specification, and the way the world models not only application structure, behavior, and architecture, but also business process, workflows and data structure. Activity diagram UML is good way to show how different workflows in the business are managed, how they start, go and stop. Diagrams also show many different decision paths that can be taken from start to finish. State charts can be used as a detail the transitions or changes of states when documents can go through in the business. They show how a documents moves from one state to another and the rules that govern that change. Petri-nets offer a graphical notation for stepwise processes that include choice, iteration, and concurrent execution. Unlike UML Petri nets have an exact mathematical definition of their execution semantics, with a well-developed mathematical theory for process analysis. In the article there are modeled a special type of Petri nets, the WF-nets. The practical part of article incorporates two models of concrete business documents workflows presented in these notations, their comparison and recommendation for using these diagrams in business process management.

  13. Gas flow characteristics of a time modulated APPJ: the effect of gas heating on flow dynamics

    International Nuclear Information System (INIS)

    Zhang, S; Sobota, A; Van Veldhuizen, E M; Bruggeman, P J

    2015-01-01

    This work investigates the flow dynamics of a radio-frequency (RF) non-equilibrium argon atmospheric pressure plasma jet. The RF power is at a frequency of 50 Hz or 20 kHz. Combined flow pattern visualizations (obtained by shadowgraphy) and gas temperature distributions (obtained by Rayleigh scattering) are used to study the formation of transient vortex structures in initial flow field shortly after the plasma is switched on and off in the case of 50 Hz modulation. The transient vortex structures correlate well with observed temperature differences. Experimental results of the fast modulated (20 kHz) plasma jet that does not induce changes of the gas temperature are also presented. The latter result suggests that momentum transfer by ions does not have dominant effect on the flow pattern close to the tube. It is argued that the increased gas temperature and corresponding gas velocity increase at the tube exit due to the plasma heating increases the admixing of surrounding air and reduces the effective potential core length. With increasing plasma power a reduction of the effective potential core length is observed with a minimum length for 5.6 W after which the length extends again. Possible mechanisms related to viscosity effects and ionic momentum transfer are discussed. (paper)

  14. Net capital flows to and the real exchange rate of Western Balkan countries

    Directory of Open Access Journals (Sweden)

    Gabrisch Hubert

    2015-01-01

    Full Text Available This paper uses Granger causality tests to assess the linkages between changes in the real exchange rate and net capital inflows using the example of Western Balkan countries, which have suffered from low competitiveness and external imbalances for many years. The real exchange rate is a measure of a country’s price competitiveness, and the paper uses two concepts: relative unit labour cost and relative inflation differential. The sample consists of six Western Balkan countries for the period 1996-2012, relative to the European Union (EU. The main finding is that changes in the net capital flows precede changes in relative unit labour costs and not vice versa. Also, there is evidence that net capital flows affect the inflation differential of countries, although to a less discernible extent. This suggests that the increasing divergence in the unit labour cost between the EU and Western Balkan countries up to the global financial crisis was at least partly the result of net capital inflows. The paper adds to the ongoing debate on improving cost competitiveness through wage restrictions as the main vehicle to avert the accumulation of current account imbalances. It shows the importance of changes in the exchange rate regime, reform of the interaction between the financial and the real sector, and financial supervision and structural change.

  15. Land Use Effects on Net Greenhouse Gas Fluxes in the US Great Plains: Historical Trends and Model Projections

    Science.gov (United States)

    Del Grosso, S. J.; Parton, W. J.; Ojima, D. S.; Mosier, A. R.; Mosier, A. R.; Paustian, K.; Peterson, G. A.

    2001-12-01

    We present maps showing regional patterns of land use change and soil C levels in the US Great Plains during the 20th century and time series of net greenhouse gas fluxes associated with different land uses. Net greenhouse gas fluxes were calculated by accounting for soil CO2 fluxes, the CO2 equivalents of N2O emissions and CH4 uptake, and the CO2 costs of N fertilizer production. Both historical and modern agriculture in this region have been net sources of greenhouse gases. The primary reason for this, prior to 1950, is that agriculture mined soil C and resulted in net CO2 emissions. When chemical N fertilizer became widely used in the 1950's agricultural soils began to sequester CO2-C but these soils were still net greenhouse gas sources if the effects of increased N2O emissions and decreased CH4 uptake are included. The sensitivity of net greenhouse gas fluxes to conventional and alternative land uses was explored using the DAYCENT ecosystem model. Model projections suggest that conversion to no-till, reduction of the fallow period, and use of nitrification inhibitors can significantly decrease net greenhouse gas emissions in dryland and irrigated systems, while maintaining or increasing crop yields.

  16. Flow regimes in vertical gas-solid contact systems

    Energy Technology Data Exchange (ETDEWEB)

    Yerushalmi, J.; Cankurt, N. T.; Geldart, D.; Liss, B.

    1976-01-01

    The flow characteristics in fluidized beds, i.e., gas-solid systems, was studied to determine the flow regimes, the interaction of gas and solid in the various flow regimes and the dependence of this interaction and of transition between flow regimes on the properties of the gas and solid, on the gas and solid flow rates, and on the containing vessel. Fluidized beds with both coarse and fine particles are considered. Test results using high speed photography to view the operation of a 2-dimensional bed are discussed. (LCL)

  17. Net Capital Flows, Macroeconomic Shocks and Reserve Assets. The Case of Argentina (1994-2013

    Directory of Open Access Journals (Sweden)

    Luis N. Lanteri

    2014-06-01

    Full Text Available International reserves have been used as a source of protection against the vulnerability of the balance of payments, or alternatively, as an attempt to keep a competitive real exchange rate and to promote exports. This paper explores the correlation between the net capital flows and reserves. Similarly, the impact of some macroeconomic shocks on that variable is assessed. Estimates are carried out through both, the VEC (Vector Error Correction models and quarterly data of the Argentine economy for the period 1994-2013. Results show a negative correlation between international reserves and net capital flows (reserve accumulation through current account surpluses. At the same time, the expansionary fiscal policies and the continuing and widespread price increases would adversely affect the reserves.

  18. Nonlinear vacuum gas flow through a short tube due to pressure and temperature gradients

    Energy Technology Data Exchange (ETDEWEB)

    Pantazis, Sarantis; Naris, Steryios; Tantos, Christos [Department of Mechanical Engineering, University of Thessaly, Pedion Areos, 38334 Volos (Greece); Valougeorgis, Dimitris, E-mail: diva@mie.uth.gr [Department of Mechanical Engineering, University of Thessaly, Pedion Areos, 38334 Volos (Greece); André, Julien; Millet, Francois; Perin, Jean Paul [Service des Basses Températures, UMR-E CEA/UJF-Grenoble 1, INAC, Grenoble, F-38054 (France)

    2013-10-15

    The flow of a rarefied gas through a tube due to both pressure and temperature gradients has been studied numerically. The main objective is to investigate the performance of a mechanical vacuum pump operating at low temperatures in order to increase the pumped mass flow rate. This type of pump is under development at CEA-Grenoble. The flow is modelled by the Shakhov kinetic model equation, which is solved by the discrete velocity method. Results are presented for certain geometry and flow parameters. Since according to the pump design the temperature driven flow is in the opposite direction than the main pressure driven flow, it has been found that for the operating pressure range studied here the net mass flow rate through the pump may be significantly reduced.

  19. Nonlinear vacuum gas flow through a short tube due to pressure and temperature gradients

    International Nuclear Information System (INIS)

    Pantazis, Sarantis; Naris, Steryios; Tantos, Christos; Valougeorgis, Dimitris; André, Julien; Millet, Francois; Perin, Jean Paul

    2013-01-01

    The flow of a rarefied gas through a tube due to both pressure and temperature gradients has been studied numerically. The main objective is to investigate the performance of a mechanical vacuum pump operating at low temperatures in order to increase the pumped mass flow rate. This type of pump is under development at CEA-Grenoble. The flow is modelled by the Shakhov kinetic model equation, which is solved by the discrete velocity method. Results are presented for certain geometry and flow parameters. Since according to the pump design the temperature driven flow is in the opposite direction than the main pressure driven flow, it has been found that for the operating pressure range studied here the net mass flow rate through the pump may be significantly reduced

  20. Gas and water flow in the Callovo-Oxfordian argillite

    International Nuclear Information System (INIS)

    Harrington, J.F.; Noy, D.J.; Talandier, J.

    2010-01-01

    Document available in extended abstract form only. Understanding the impact and fate of this gas phase is of significant importance within performance assessment and for the accurate long-term prediction of repository evolution. This paper describes the initial results from an ongoing experimental study to measure the two-phase flow behaviour of the Callovo-Oxfordian argillite from the Bure underground research laboratory (URL) in France, using the custom-designed BGS permeameter. The primary objectives of the study are to measure: (i) the hydraulic conductivity and intrinsic permeability; (ii) the capillary displacement pressure; (iii) the effective gas permeability and relative permeability to gas for a range of conditions; and (iv) the post-test gas saturation. During testing, the specimen, a cylinder of 54 mm thickness, cut perpendicular to bedding, is subject to an isotropic confining stress, with fluids injected through the base of the specimen. A novel feature of the apparatus is the use of porous annular guard-ring filters around the inflow and outflow filters. The pressures in these two 'guard-rings' can be independently monitored to provide data on the distribution of pressure and anisotropy of the sample. Initial measurements, performed on a specimen orientation perpendicular to the bedding plane, have been divided into three components: re-saturation and consolidation; hydraulic properties; gas behaviour. During the initial period of equilibration, re-saturation of the sample were noted. Net volume change due to re-saturation closely agreed with pre-test geotechnical measurements of water saturation, suggesting the bulk of the gas phase was resident in non-dilatant pores and that the specimen was fully saturated at the onset of testing. A two step consolidation test was then performed with confining pressure raised to 11 MPa for 5 days and then to 12.5 MPa for a further 8 days. Values for drained bulk modulus based on the total volume of fluid

  1. Optimising gas pipeline operation - factors to consider in selecting flow measurement technology; Gas flow measurement

    Energy Technology Data Exchange (ETDEWEB)

    Fromm, Frank

    2010-07-01

    Multipath ultrasonic transit-time flow meters (UFM) have been employed in the gas industries for many years. Since their inception in the early seventies, advancements in the technology have been made with regard to available configurations, electronics offered and sensor design. Today, UFMs have proven to be reliable, versatile and capable of meeting the demands of the gas markets. It is clear that various UFM technologies have different advantages with regards to design and application use, which ultimately makes one more appropriate than the other. (Author)

  2. Gas-liquid flow filed in agitated vessels

    International Nuclear Information System (INIS)

    Hormazi, F.; Alaie, M.; Dabir, B.; Ashjaie, M.

    2001-01-01

    Agitated vessels in form of sti reed tank reactors and mixed ferment ors are being used in large numbers of industry. It is more important to develop good, and theoretically sound models for scaling up and design of agitated vessels. In this article, two phase flow (gas-liquid) in a agitated vessel has been investigated numerically. A two-dimensional computational fluid dynamics model, is used to predict the gas-liquid flow. The effects of gas phase, varying gas flow rates and variation of bubbles shape on flow filed of liquid phase are investigated. The numerical results are verified against the experimental data

  3. PIV Measurements of Gas Flow Fields from Burning End

    Science.gov (United States)

    Huang, Yifei; Wu, Junzhang; Zeng, Jingsong; Tang, Darong; Du, Liang

    2017-12-01

    To study the influence of cigarette gas on the environment, it is necessary to know the cigarette gas flow fields from burning end. By using PIV technique, in order to reveal velocity characteristics of gas flow fields, the velocities of cigarette gas flow fields was analyzed with different stepping motor frequencies corresponding to suction pressures, and the trend of velocity has been given with image fitting. The results shows that the velocities of the burning end increased with suction pressures; Between velocities of the burning end and suction pressures, the relations present polynomial rule; The cigarette gas diffusion in combustion process is faster than in the smoldering process.

  4. Comparison of net global warming potential and greenhouse gas intensity affected by management practices in two dryland cropping sites

    Science.gov (United States)

    Little is known about the effect of management practices on net global warming potential (GWP) and greenhouse gas intensity (GHGI) that account for all sources and sinks of greenhouse gas (GHG) emissions in dryland cropping systems. The objective of this study was to compare the effect of a combinat...

  5. Study on onset of nucleate boiling and net vapor generation point in subcooled flow boiling

    International Nuclear Information System (INIS)

    Ohtake, Hiroyasu; Wada, Noriyoshi; Koizumi, Yasuo

    2002-01-01

    The onset of nucleate boiling (ONB) and the point of net vapor generation on subcooled flow boiling, focusing on liquid subcooling and liquid velocity were investigated experimentally and analytically. Experiments were conducted using a copper thin-film (35μm) and subcooled water in a range of the liquid velocity from 0.27 to 4.6 m/s at 0.10MPa. The liquid subcoolings were 20, 30 and 40K, respectively. Temperatures at the onset of nucleate boiling obtained in the experiments increased with the liquid subcoolings and the liquid velocities. The increases in the temperature of ONB were represented with the classical stability theory of preexisting nuclei. The measured results of the net vapor generation agreed well with the results of correlation by Saha and Zuber in the range of the present experiments. (J.P.N.)

  6. Windowless gas target with gas-dynamical focussing of an ultrasonic neutral gas flow

    International Nuclear Information System (INIS)

    Tietsch, W.; Bethge, K.; Feist, H.; Schopper, E.

    1975-11-01

    The construction of a gas jet target for heavy ion reaction is reported on. The spatial compression strockwaves in a supersonic flow behind a laval nozzle are used as a target. The target thickness can be varied by the choice of the nozzle pressure and the static pressure in the expansion room. All gases can be used. (WL) [de

  7. Method for confirming flow pattern of gas-water flow in horizontal tubes under rolling state

    International Nuclear Information System (INIS)

    Luan Feng; Yan Changqi

    2008-01-01

    An experimental study on the flow patterns of gas-water flow was carried out in horizontal tubes under rolling state. It was found that the pressure drop of two phase flow was with an obvious periodical characteristic. The flow pattern of the gas-water flow was distinguished according to the characteristics of the pressure drop in this paper. It was proved that the characteristics of the pressure drop can distinguish the flow pattern of gas-water flow correctly through comparing with the result of careful observation and high speed digital camera. (authors)

  8. Simulations of overall flow in gas centrifuge considering feed jet

    International Nuclear Information System (INIS)

    He Liang; Jiang Dongjun; Ying Chuntong

    2010-01-01

    A coupled method for the numerical solution of the flow in rapidly rotating gas centrifuge was presented. An iteration process of DSMC and CFD was performed to analyze the overall flow in radial direction, in which DSMC was adopted to simulate the rarefied region, and CFD was adopted to the counter-current of gas centrifuge to discrete the model equations. It was applied to simulate the 2D symmetrical flow model considering the rarefied region with the feed jet flow. A series of illustrative numerical examples were given. The flow structures of the feed jet in the rarefied gas flow region were shown. The results suggest that DSMC CFD coupled method is competent to the simulations of overall flow in a gas centrifuge. (authors)

  9. Device accurately measures and records low gas-flow rates

    Science.gov (United States)

    Branum, L. W.

    1966-01-01

    Free-floating piston in a vertical column accurately measures and records low gas-flow rates. The system may be calibrated, using an adjustable flow-rate gas supply, a low pressure gage, and a sequence recorder. From the calibration rates, a nomograph may be made for easy reduction. Temperature correction may be added for further accuracy.

  10. The flows structure in unsteady gas flow in pipes with different cross-sections

    OpenAIRE

    Plotnikov Leonid; Nevolin Alexandr; Nikolaev Dmitrij

    2017-01-01

    The results of numerical simulation and experimental study of the structure of unsteady flows in pipes with different cross sections are presented in the article. It is shown that the unsteady gas flow in a circular pipe is axisymmetric without secondary currents. Steady vortex structures (secondary flows) are observed in pipes with cross sections in the form of a square and an equilateral triangle. It was found that these secondary flows have a significant impact on gas flows in pipes of com...

  11. The Perspective on Data and Control Flow Analysis in Topological Functioning Models by Petri Nets

    Directory of Open Access Journals (Sweden)

    Asnina Erika

    2014-12-01

    Full Text Available The perspective on integration of two mathematical formalisms, i.e., Colored Petri Nets (CPNs and Topological Functioning Model (TFM, is discussed in the paper. The roots of CPNs are in modeling system functionality. The TFM joins principles of system theory and algebraic topology, and formally bridges the solution domain with the problem domain. It is a base for further automated construction of software design models. The paper discusses a perspective on check of control and data flows in the TFM by CPNs formalism. The research result is definition of mappings from TFMs to CPNs.

  12. Petri Nets Based Modelling of Control Flow for Memory-Aid Interactive Programs in Telemedicine

    CERN Document Server

    Khoromskaia, V K

    2004-01-01

    Petri Nets (PN) based modelling of the control flow for the interactive memory assistance programs designed for personal pocket computers and having special requirements for robustness is considered. The proposed concept allows one to elaborate the programs which can give users a variety of possibilities for a day-time planning in the presence of environmental and time restrictions. First, a PN model for a known simple algorithm is constructed and analyzed using the corresponding state equations and incidence matrix. Then a PN graph for a complicated algorithm with overlapping actions and choice possibilities is designed, supplemented by an example of its analysis. Dynamic behaviour of this graph is tested by tracing of all possible paths of the flow of control using the PN simulator. It is shown that PN based modelling provides reliably predictable performance of interactive algorithms with branched structures and concurrency requirements.

  13. Fluid Flow Behaviour under Different Gases and Flow Rate during Gas Metal Arc Welding

    OpenAIRE

    Jaison Peter

    2013-01-01

    Gas metal arc welding (GMAW) is a highly efficient and fast process for fabricating high quality weld. High quality welds are fabricated by proper selection of consumable includes gas and filler metals. The optimum flow rate of gas will ensure the proper quality of weld. In this project, a fluid flow behavior of different flow rate is modeled and the change quality will be studied.

  14. Thermally driven gas flow beneath Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Amter, S.; Lu, Ning; Ross, B.

    1991-01-01

    A coupled thermopneumatic model is developed for simulating heat transfer, rock-gas flow and carbon-14 travel time beneath Yucca Mountain, NV. The aim of this work is to understand the coupling of heat transfer and gas flow. Heat transfer in and near the potential repository region depends on several factors, including the geothermal gradient, climate, and local sources of heat such as radioactive wastes. Our numerical study shows that small temperature changes at the surface can change both the temperature field and the gas flow pattern beneath Yucca Mountain. A lateral temperature difference of 1 K is sufficient to create convection cells hundreds of meters in size. Differences in relative humidities between gas inside the mountain and air outside the mountain also significantly affect the gas flow field. 6 refs., 7 figs

  15. Energy Demodulation Algorithm for Flow Velocity Measurement of Oil-Gas-Water Three-Phase Flow

    Directory of Open Access Journals (Sweden)

    Yingwei Li

    2014-01-01

    Full Text Available Flow velocity measurement was an important research of oil-gas-water three-phase flow parameter measurements. In order to satisfy the increasing demands for flow detection technology, the paper presented a gas-liquid phase flow velocity measurement method which was based on energy demodulation algorithm combing with time delay estimation technology. First, a gas-liquid phase separation method of oil-gas-water three-phase flow based on energy demodulation algorithm and blind signal separation technology was proposed. The separation of oil-gas-water three-phase signals which were sampled by conductance sensor performed well, so the gas-phase signal and the liquid-phase signal were obtained. Second, we used the time delay estimation technology to get the delay time of gas-phase signals and liquid-phase signals, respectively, and the gas-phase velocity and the liquid-phase velocity were derived. At last, the experiment was performed at oil-gas-water three-phase flow loop, and the results indicated that the measurement errors met the need of velocity measurement. So it provided a feasible method for gas-liquid phase velocity measurement of the oil-gas-water three-phase flow.

  16. Effect of gas quantity on two-phase flow characteristics of a mixed-flow pump

    OpenAIRE

    Qiang Fu; Fan Zhang; Rongsheng Zhu; Xiuli Wang

    2016-01-01

    The inlet gas quantity has a great influence on the performance and inner flow characteristics of a mixed-flow pump. In this article, both numerical and experimental methods are used to carry out this research work. The effects under the steady gas volume fraction state and the transient gas quantity variation process on the mixed-flow pump are investigated and compared in detail. It could be concluded that the head of the mixed-flow pump shows slight decline at the low gas volume fraction st...

  17. Prediction of Mass Flow Rate in Supersonic Natural Gas Processing

    Directory of Open Access Journals (Sweden)

    Wen Chuang

    2015-11-01

    Full Text Available The mass flow rate of natural gas through the supersonic separator was numerically calculated by various cubic equations of state. The numerical results show that the compressibility factor and specific heat ratio for ideal gas law diverge remarkably from real gas models at a high inlet pressure. Simultaneously, the deviation of mass flow calculated by the ideal and real gas models reaches over 10 %. The difference increases with the lower of the inlet temperature regardless of the inlet pressure. A higher back pressure results in an earlier location of the shock wave. The pressure ratio of 0.72 is the first threshold to get the separator work normally. The second threshold is 0.95, in which case the whole flow is subsonic and cannot reach the choked state. The shock position moves upstream with the real gas model compared to the ideal gas law in the cyclonic separation section.

  18. Estimation of net greenhouse gas balance using crop- and soil-based approaches: Two case studies

    International Nuclear Information System (INIS)

    Huang, Jianxiong; Chen, Yuanquan; Sui, Peng; Gao, Wansheng

    2013-01-01

    The net greenhouse gas balance (NGHGB), estimated by combining direct and indirect greenhouse gas (GHG) emissions, can reveal whether an agricultural system is a sink or source of GHGs. Currently, two types of methods, referred to here as crop-based and soil-based approaches, are widely used to estimate the NGHGB of agricultural systems on annual and seasonal crop timescales. However, the two approaches may produce contradictory results, and few studies have tested which approach is more reliable. In this study, we examined the two approaches using experimental data from an intercropping trial with straw removal and a tillage trial with straw return. The results of the two approaches provided different views of the two trials. In the intercropping trial, NGHGB estimated by the crop-based approach indicated that monocultured maize (M) was a source of GHGs (− 1315 kg CO 2 −eq ha −1 ), whereas maize–soybean intercropping (MS) was a sink (107 kg CO 2 −eq ha −1 ). When estimated by the soil-based approach, both cropping systems were sources (− 3410 for M and − 2638 kg CO 2 −eq ha −1 for MS). In the tillage trial, mouldboard ploughing (MP) and rotary tillage (RT) mitigated GHG emissions by 22,451 and 21,500 kg CO 2 −eq ha −1 , respectively, as estimated by the crop-based approach. However, by the soil-based approach, both tillage methods were sources of GHGs: − 3533 for MP and − 2241 kg CO 2 −eq ha −1 for RT. The crop-based approach calculates a GHG sink on the basis of the returned crop biomass (and other organic matter input) and estimates considerably more GHG mitigation potential than that calculated from the variations in soil organic carbon storage by the soil-based approach. These results indicate that the crop-based approach estimates higher GHG mitigation benefits compared to the soil-based approach and may overestimate the potential of GHG mitigation in agricultural systems. - Highlights: • Net greenhouse gas balance (NGHGB) of

  19. Simulation of gas compressible flow by free surface water flow

    International Nuclear Information System (INIS)

    Altafini, C.R.; Silva Ferreira, R.T. da

    1981-01-01

    The analogy between the water flow with a free surface and the compressible fluid flow, commonly called hydraulic analogy, is analyzed and its limitations are identified. The water table is the equipment used for this simulation, which allows the quatitative analysis of subsonic and supersonic flow with a low cost apparatus. The hydraulic analogy is applied to subsonic flow around circular cylinders and supersonic flow around cones. The results are compared with available theoretical and experimental data and a good agreement is achieved. (Author) [pt

  20. DSMC simulation of feed jet flow in gas centrifuge

    International Nuclear Information System (INIS)

    Jiang Dongjun; Zeng Shi

    2011-01-01

    Feed jet flow acts an important role for the counter-current in gas centrifuge. Direct simulation Monte-Carlo (DSMC) method was adopted to simulate the structure of the radial feed jet model. By setting the proper boundary conditions and the collision model of molecules, the flow distributions of the 2D radial feed jet were acquired under different feed conditions, including the wave structure of feed jet and the profile of the flow parameters. The analyses of the calculation results note the following flow phenomena: Near the radial outflow boundary, the obvious peaks of the flow parameters exist; higher speed of feed gas brings stronger influence on the flow field of the centrifuge; including the density, pressure and velocity of the gas, the distribution of the temperature is affected by the feed jet, at the outflow boundary, temperature to double times of the average value. (authors)

  1. Gas-Dynamic Methods to Reduce Gas Flow Nonuniformity from the Annular Frames of Gas Turbine Engines

    Science.gov (United States)

    Kolmakova, D.; Popov, G.

    2018-01-01

    Gas flow nonuniformity is one of the main sources of rotor blade vibrations in the gas turbine engines. Usually, the flow circumferential nonuniformity occurs near the annular frames, located in the flow channel of the engine. This leads to the increased dynamic stresses in blades and consequently to the blade damage. The goal of the research was to find an acceptable method of reducing the level of gas flow nonuniformity. Two different methods were investigated during this research. Thus, this study gives the ideas about methods of improving the flow structure in gas turbine engine. Based on existing conditions (under development or existing engine) it allows the selection of the most suitable method for reducing gas flow nonuniformity.

  2. Mass transfer between gas and particles in a gas-solid trickle flow reactor

    NARCIS (Netherlands)

    Kiel, J.H.A.; Kiel, J.H.A.; Prins, W.; van Swaaij, Willibrordus Petrus Maria

    1992-01-01

    Gas-solids mass transfer was studied for counter-current flow of gas and millimetre-sized solid particles over an inert packing at dilute phase or trickle flow conditions. Experimental data were obtained from the adsorption of water vapour on 640 and 2200 ¿m diameter molecular sieve spheres at

  3. Gage for gas flow measurement especially in gas-suction pipes

    International Nuclear Information System (INIS)

    Renner, K.; Stegmanns, W.

    1978-01-01

    The gage utilizes the differential pressure given by a differential pressure producer to generate, in a bypass, a partial gas flow measured by means of a direct-reading anemometer of windmill type. The partial gas flow is generated between pressure pick-up openings in the gas-suction pipe in front of a venturi insert and pressure pick-up openings at the bottleneck of the venturi insert. The reading of the anemometer is proportional to the main gas flow and independent of the variables of state and the properties of the gases to be measured. (RW) [de

  4. Computations of ideal and real gas high altitude plume flows

    Science.gov (United States)

    Feiereisen, William J.; Venkatapathy, Ethiraj

    1988-01-01

    In the present work, complete flow fields around generic space vehicles in supersonic and hypersonic flight regimes are studied numerically. Numerical simulation is performed with a flux-split, time asymptotic viscous flow solver that incorporates a generalized equilibrium chemistry model. Solutions to generic problems at various altitude and flight conditions show the complexity of the flow, the equilibrium chemical dissociation and its effect on the overall flow field. Viscous ideal gas solutions are compared against equilibrium gas solutions to illustrate the effect of equilibrium chemistry. Improved solution accuracy is achieved through adaptive grid refinement.

  5. Flow measurement in two-phase (gas-liquid) systems

    International Nuclear Information System (INIS)

    Hewitt, G.F.; Whalley, P.B.

    1980-01-01

    The main methods of measuring mass flow and quality in gas-liquid flows in industrial situations are reviewed. These include gamma densitometry coupled with differential pressure devices such as crifice plates, turbine flow meters and drag screens. For each method the principle of operation, and the advantages and disadvantages, are given. Some further techniques which are currently being investigated and developed for routine use are also described briefly. Finally the detailed flow measurements possible on a particular flow pattern - annular flow - is examined. (author)

  6. Research for rolling effects on flow pattern of gas-water flow in horizontal tubes

    International Nuclear Information System (INIS)

    Luan Feng; Yan Changqi

    2007-01-01

    The flow pattern transition of two-phase flow is caused by the inertial force resulted from rolling and incline of horizontal tubes under rolling state. an experimental study on the flow patterns of gas-water flow was carried out in horizontal tubes under rolling state, which rolling period is 15 second and rolling angle is 10 degrees, and a pattern flow picture is shown. It was found that there are two flow patterns in one rolling period under some gas flux and water flux. (authors)

  7. Radiation energy devaluation in diffusion combusting flows of natural gas

    International Nuclear Information System (INIS)

    Makhanlall, Deodat; Munda, Josiah L.; Jiang, Peixue

    2013-01-01

    Abstract: CFD (Computational fluid dynamics) is used to evaluate the thermodynamic second-law effects of thermal radiation in turbulent diffusion natural gas flames. Radiative heat transfer processes in gas and at solid walls are identified as important causes of energy devaluation in the combusting flows. The thermodynamic role of thermal radiation cannot be neglected when compared to that of heat conduction and convection, mass diffusion, chemical reactions, and viscous dissipation. An energy devaluation number is also defined, with which the optimum fuel–air equivalence for combusting flows can be determined. The optimum fuel–air equivalence ratio for a natural gas flame is determined to be 0.7. The CFD model is validated against experimental measurements. - Highlights: • Thermodynamic effects of thermal radiation in combusting flows analyzed. • General equation for second-law analyses of combusting flows extended. • Optimum fuel–air equivalence ratio determined for natural gas flame

  8. Building waste management core indicators through Spatial Material Flow Analysis: net recovery and transport intensity indexes.

    Science.gov (United States)

    Font Vivanco, David; Puig Ventosa, Ignasi; Gabarrell Durany, Xavier

    2012-12-01

    In this paper, the material and spatial characterization of the flows within a municipal solid waste (MSW) management system are combined through a Network-Based Spatial Material Flow Analysis. Using this information, two core indicators are developed for the bio-waste fraction, the Net Recovery Index (NRI) and the Transport Intensity Index (TII), which are aimed at assessing progress towards policy-related sustainable MSW management strategies and objectives. The NRI approaches the capacity of a MSW management system for converting waste into resources through a systematic metabolic approach, whereas the TII addresses efficiency in terms of the transport requirements to manage a specific waste flow throughout the entire MSW management life cycle. Therefore, both indicators could be useful in assessing key MSW management policy strategies, such as the consecution of higher recycling levels (sustainability principle) or the minimization of transport by locating treatment facilities closer to generation sources (proximity principle). To apply this methodological approach, the bio-waste management system of the region of Catalonia (Spain) has been chosen as a case study. Results show the adequacy of both indicators for identifying those points within the system with higher capacity to compromise its environmental, economic and social performance and therefore establishing clear targets for policy prioritization. Moreover, this methodological approach permits scenario building, which could be useful in assessing the outcomes of hypothetical scenarios, thus proving its adequacy for strategic planning. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Do tropical wetland plants possess a convective gas flow mechanism?

    DEFF Research Database (Denmark)

    Jensen, Dennis Konnerup; Sorrell, Brian Keith; Brix, Hans

    2011-01-01

    Internal pressurization and convective gas flow, which can aerate wetland plants more efficiently than diffusion, are common in temperate species. Here, we present the first survey of convective flow in a range of tropical plants. The occurrence of pressurization and convective flow was determined...... in 20 common wetland plants from the Mekong Delta in Vietnam. The diel variation in pressurization in culms and the convective flow and gas composition from stubbles were examined for Eleocharis dulcis, Phragmites vallatoria and Hymenachne acutigluma, and related to light, humidity and air temperature....... Nine of the 20 species studied were able to build up a static pressure of >50Pa, and eight species had convective flow rates higher than 1mlmin-1. There was a clear diel variation, with higher pressures and flows during the day than during the night, when pressures and flows were close to zero...

  10. Rarefield gas dynamics fundamentals, simulations and micro flows

    CERN Document Server

    Shen, Ching

    2006-01-01

    This book elucidates the methods of molecular gas dynamics or rarefied gas dynamics which treat the problems of gas flows when the discrete molecular effects of the gas prevail under the circumstances of low density, the emphasis being on the basis of the methods, the direct simulation Monte Carlo method applied to the simulation of non-equilibrium effects and the frontier subjects related to low speed microscale rarefied gas flows. It provides a solid basis for the study of molecular gas dynamics for senior students and graduates in the aerospace and mechanical engineering departments of universities and colleges. It gives a general acquaintance of modern developments of rarefied gas dynamics in various regimes and leads to the frontier topics of non-equilibrium rarefied gas dynamics and low speed microscale gas dynamics. It will be also of benefit to the scientific and technical researchers engaged in aerospace high altitude aerodynamic force and heating design and in the research on gas flow in MEMS.

  11. Net profit flow per country from 1980 to 2009: The long-term effects of foreign direct investment

    Science.gov (United States)

    2017-01-01

    Aim of the paper The paper aims at describing and explaining net profit flows per country for the period 1980–2009. Net profit flows result from Foreign Direct Investment (FDI) stock and profit repatriation: inward stock creating a profit outflow and outward FDI stock a profit inflow. Profit flows, especially ‘normal’ ones are not commonly researched. Theoretical background According to world-system theory, countries are part of a system characterised by a core, semi-periphery and periphery, as shown by network analyses of trade relations. Network analyses based on ownership relations of TransNational Corporations (TNCs) show that the top 50 firms that control about 40% of the world economy are almost exclusively located in core countries. So, we may expect a hierarchy in net profit flows with core countries on top and the periphery at the bottom. FDI outflows from the core countries especially rose in the 1990s, so we may expect that the difference has grown in time. Data and results A dataset on 'net profit flow' per country is developed. There are diverging developments in net profit flows since the 1980s, as expected: ever more positive for core countries, negative and ever lower for semi-peripheral and peripheral countries, in particular from the 1990s onwards. A fixed effects quantile regression using publicly available data confirms the prediction that peripheral countries share a unique characteristic: their outward investments do not have a positive influence on net profit flow as is the case with semi-peripheral and core countries. The most probable explanation is that peripheral outward investments are indirectly owned by firms located in core and semi-peripheral countries, so all peripheral profit inflows end up in those countries. PMID:28654644

  12. Net profit flow per country from 1980 to 2009: The long-term effects of foreign direct investment.

    Science.gov (United States)

    Akkermans, Dirk H M

    2017-01-01

    The paper aims at describing and explaining net profit flows per country for the period 1980-2009. Net profit flows result from Foreign Direct Investment (FDI) stock and profit repatriation: inward stock creating a profit outflow and outward FDI stock a profit inflow. Profit flows, especially 'normal' ones are not commonly researched. According to world-system theory, countries are part of a system characterised by a core, semi-periphery and periphery, as shown by network analyses of trade relations. Network analyses based on ownership relations of TransNational Corporations (TNCs) show that the top 50 firms that control about 40% of the world economy are almost exclusively located in core countries. So, we may expect a hierarchy in net profit flows with core countries on top and the periphery at the bottom. FDI outflows from the core countries especially rose in the 1990s, so we may expect that the difference has grown in time. A dataset on 'net profit flow' per country is developed. There are diverging developments in net profit flows since the 1980s, as expected: ever more positive for core countries, negative and ever lower for semi-peripheral and peripheral countries, in particular from the 1990s onwards. A fixed effects quantile regression using publicly available data confirms the prediction that peripheral countries share a unique characteristic: their outward investments do not have a positive influence on net profit flow as is the case with semi-peripheral and core countries. The most probable explanation is that peripheral outward investments are indirectly owned by firms located in core and semi-peripheral countries, so all peripheral profit inflows end up in those countries.

  13. Net vapor generation point in boiling flow of trichlorotrifluoroethane at high pressures

    Science.gov (United States)

    Dougall, R. S.; Lippert, T. E.

    1973-01-01

    The conditions at which the void in subcooled boiling starts to undergo a rapid increase were studied experimentally. The experiments were performed in a 12.7 x 9.5 mm rectangular channel. Heating was from a 3.2 mm wide strip embedded in one wall. The pressure ranged from 9.45 to 20.7 bar, mass velocity from 600 to 7000 kg/sq m sec, and subcooling from 16 to 67 C. Photographs were used to determine when detached bubbles first appeared in the bulk flow. Measurements of bubble layer thickness along the wall were also made. Results showed that the point of net vapor generation is close to the occurrence of fully-developed boiling.

  14. Hot gas flow cell for optical measurements on reactive gases

    DEFF Research Database (Denmark)

    Grosch, Helge; Fateev, Alexander; Nielsen, Karsten Lindorff

    2013-01-01

    A new design is presented for a gas flow cell for reactive gases at high temperatures. The design features three heated sections that are separated by flow windows. This design avoids the contact of reactive gases with the material of the exchangeable optical windows. A gas cell with this design ......-resolution measurements are presented for the absorption cross-section of sulfur dioxide (SO2) in the UV range up to 773 K (500 degrees C)...

  15. Lattice gas automata simulations of flow through porous media

    International Nuclear Information System (INIS)

    Matsukuma, Yosuke; Abe, Yutaka; Adachi, Hiromichi; Takahashi, Ryoichi

    1998-01-01

    In the course of a severe accident, a debris bed may be formed from once- molten and fragmented fuel elements. In order to avoid further degradation of the reactor core, it is necessary to remove the heat from the debris bed since the debris bed still release the decay heat. So as to predict the coolability of the debris bed, it is important to precisely estimate flow patterns through complex geometry of debris bed in microscopic level. Lattice gas automata could be powerful tool to simulate such a complex geometry. As a first step of the study, fundamental numerical simulation were conducted in two dimensional systems by using the lattice gas automata method to clarify single phase flow patterns through porous media in mesoscopic level. Immiscible lattice gas model is one of the lattice gas automata method and utilized for spinodal decomposition simulation of binary fluids. This model was applied to generate the complex flow geometry simulating porous media. It was approved that the complex flow geometries were successfully generated by the present method. Flow concentration was observed in specified flow channels for lower Reynolds number. Two dimensional flow concentration was caused by the irregular flow geometry generated by the present method, since the flow selects the channels of lower friction. Two dimensional pressure distribution was observed relating to the concentrations of flow in specified channels. The simulating results of the flow through the porous media by the present method qualitatively agree with the Ergun's equation. Quantitatively, the present results approach to Ergun's equation in higher Reynolds number than 10, although concentration of the flow in a specified flow channels were observed in lower Reynolds number than 10. It can be concluded that this technique is useful is useful to simulate flow through complex geometry like porous media. (author)

  16. Lagrangian solution of supersonic real gas flows

    International Nuclear Information System (INIS)

    Loh, Chingyuen; Liou, Mengsing

    1993-01-01

    This paper details the procedure of the real gas Riemann solution in the Lagrangian approach originally proposed by Loh and Hui for perfect gases. The extension to real gases is nontrivial and requires substantial development of an exact real-gas Riemann solver for the Lagrangian form of conservation laws. The first-order Gudonov scheme is enhanced for accuracy by adding limited anti-diffusive terms according to Sweby. Extensive calculations were made to test the accuracy and robustness of the present real gas Lagrangian approach, including complex wave interactions of different types. The accuracy for capturing 2D oblique waves and slip line is clearly demonstrated. In addition, we also show the real gas effect in a generic engine nozzle

  17. Device for measurement of gas mass flow. Einrichtung zur Gasmassenstrommessung

    Energy Technology Data Exchange (ETDEWEB)

    Sass, W

    1989-09-28

    The invention is concerned with a device for the measurement of gas mass flow, particularly measuring air mass flow for vehicles with internal combustion engines, with a measurement bridge, in one branch of which a gas flow resistance, particularly a hot film sensor, with gas flowing round it, is connected in series with a measurement resistance and in another branch of which a compensation resistance measuring the gas temperature is connected in series with a fixed resistor, where the bridge differential voltage is measured in the zero branch of the measuring bridge and a control parameter is produced from this, in order to control a transistor valve situated in the bridge supply path of a DC voltage source via its control electrode until the bridge is balanced, and where the voltage at the measurement resistance after the bridge is balanced is used as a measure of the gas mass flow. In order to obtain exact results of measurement in spite of relatively high interference noise from the cables, it is proposed that an increased supply DC voltage appreciably decreasing the occurring interference noise from the cables should be produced from a small DC voltage and that the output of the DC/DC voltage converter should be connected to the control electrode of the transistor valve, so that the control parameter for the control electrode is derived from the raised DC supply voltage through reducers depending on the gas flow.

  18. Rarefied, rotational gas flows in spiral galaxies

    International Nuclear Information System (INIS)

    Roberts, W.W. Jr.; Hausman, M.A.

    1983-01-01

    We develop a computational model of a rotating, rarefied gas in which the individual molecules collide inelastically and are subject to circularly asymmetric external forces and internal heating sources. This model is applied to the interstellar medium (ISM) of spiral galaxies, in which most of the matter is confined to discrete gas clouds separated by a tenuous intercloud medium. We identify inelastically-colliding gas molecules with interstellar clouds which orbit ballistically in the galactic gravitational field and are perturbed by expanding shells surrounding supernovae. When a small, spiral perturbation is added to the gravitational force to mimic a spiral galaxy, the cloud distribution responds with a strong, global shock. In the model, stars are formed from the gas when clouds collide or are perturbed by supernovae; these stars are the internal heating sources for the gas cloud system. We determine the morphologies (evolution, distribution) of the two components, gas and stars, in the model as functions of varying input physics. Variation of the cloud system's collisional mean free path (over physically-realistic ranges) has remarkably little influence on the computed shock structure

  19. Reactive Gas Solids Flow in Circulating Fluidised Beds

    DEFF Research Database (Denmark)

    Hjertager, Bjørn Helge; Solberg, Tron; Hansen, Kim Granly

    2005-01-01

    Progress in modelling and simulation of flow processes in gas/particle systems carried out at the authors? research group are presented. Emphasis is given to computational fluid dynamics (CFD) models that use the multi-dimensional multi fluid techniques. Turbulence modelling strategies for gas...

  20. The promising gas-dynamic schemes of vacuum deposition from the supersonic gas mixture flows

    International Nuclear Information System (INIS)

    Maltsev, R V; Rebrov, A K

    2008-01-01

    Gas jet deposition (GJD) becomes promising method of thin film and nanoparticle deposition. This paper is focused on elaboration of new methods of GJD based on different gas dynamic schemes of flow formation and interaction with substrate. Using direct statistical simulation method, the analysis was performed for: a) interaction of the jet from the sonic nozzle with a substrate; b) fan flow in the result of interaction of two opposite jets; c) convergent flow from the ring nozzle, directional to the axis; d) interaction of the jet after convergent flow with the substrate; e) fan flow in the result of interaction of two opposite jets after convergent expansion

  1. Coupling compositional liquid gas Darcy and free gas flows at porous and free-flow domains interface

    Energy Technology Data Exchange (ETDEWEB)

    Masson, R., E-mail: roland.masson@unice.fr [LJAD, University Nice Sophia Antipolis, CNRS UMR 7351 (France); Team COFFEE INRIA Sophia Antipolis Méditerranée (France); Trenty, L., E-mail: laurent.trenty@andra.fr [Andra, Chatenay Malabry (France); Zhang, Y., E-mail: yumeng.zhang@unice.fr [LJAD, University Nice Sophia Antipolis, CNRS UMR 7351 (France); Team COFFEE INRIA Sophia Antipolis Méditerranée (France)

    2016-09-15

    This paper proposes an efficient splitting algorithm to solve coupled liquid gas Darcy and free gas flows at the interface between a porous medium and a free-flow domain. This model is compared to the reduced model introduced in [6] using a 1D approximation of the gas free flow. For that purpose, the gas molar fraction diffusive flux at the interface in the free-flow domain is approximated by a two point flux approximation based on a low-frequency diagonal approximation of a Steklov–Poincaré type operator. The splitting algorithm and the reduced model are applied in particular to the modelling of the mass exchanges at the interface between the storage and the ventilation galleries in radioactive waste deposits.

  2. Effect of wall wettability on flow characteristics of gas-liquid two-phase flow

    International Nuclear Information System (INIS)

    Uematsu, Junichi; Abe, Kazuya; Hazuku, Tatsuya; Takamasa, Tomoji; Hibiki, Takashi

    2007-01-01

    To evaluate the effect of surface wettability in pipe wall on flow characteristics in a vertical upward gas-liquid to-phase flow, visualization study was performed using three test pipes, namely an acrylic pipe, a hydrophilic pipe, a hydrophobic pipe. Such basic flow characteristics as flow patterns and void fraction were investigated in these three pipes. In the hydrophilic pipe, the slug flow-to-churn flow transition boundary was shifted to higher gas velocity condition at a given liquid velocity, whereas the churn flow-to-annular flow transition boundary was shifted to lower gas velocity condition at a given liquid velocity. In the hydrophobic pipe, the inverted-churn flow regime was observed in the region where the churn flow regime was observed in the acrylic pipe, whereas the droplet flow regime was observed in the region where the annular flow regime was observed in the acrylic pipe. At high-gas flow rate condition, the mean void fraction in the hydrophobic pipe took relatively higher value to that in the acrylic pipe. (author)

  3. Effect of gas quantity on two-phase flow characteristics of a mixed-flow pump

    Directory of Open Access Journals (Sweden)

    Qiang Fu

    2016-04-01

    Full Text Available The inlet gas quantity has a great influence on the performance and inner flow characteristics of a mixed-flow pump. In this article, both numerical and experimental methods are used to carry out this research work. The effects under the steady gas volume fraction state and the transient gas quantity variation process on the mixed-flow pump are investigated and compared in detail. It could be concluded that the head of the mixed-flow pump shows slight decline at the low gas volume fraction state, while it decreases sharply at the high gas volume fraction state and then decreases with the increasing gas quantity. There is an obvious asymmetric blade vapor density on the blade suction side under each cavitation state. The cavities can be weakened obviously by increasing the inlet gas volume fraction within a certain range. It has little influence on the internal unsteady flow of the mixed-flow pump when the gas volume fraction is less than 10%, but the pump starts to operate with a great unsteady characteristic when the inlet gas volume fraction increases to 15%.

  4. Gas Flows in Dual Active Galactic Nuclei

    Science.gov (United States)

    Mueller Sanchez, Francisco; Comerford, Julia M.; Davies, Richard; Treister, Ezequiel; Privon, George C.; Nevin, Becky

    2018-06-01

    Dual Active Galactic Nuclei (AGN) are the Rosetta stone to understand the role of galaxy mergers in triggering nuclear activity and regulating black hole (BH) and galaxy growth. But very little is known about the physical processes required to effectively trigger AGN activity and regulate the growth of the two BHs. The work I will present here characterizes for the first time the properties of the stars, gas (molecular, ionized, and highly-ionized) and dust in all the confirmed dual AGN at z prototypical merger system NGC 6240: vigorous star formation, two AGNs, outflowing winds of ionized gas, rippling dust and gas lanes, and tidal tails. In this galaxy, we observe for the first time a dual outflow of different species of gas: an AGN-driven outflow of highly-ionized gas to the northeast and a starburst-driven outflow of ionized hydrogen to the northwest. This shows that stellar feedback and supermassive black hole feedback can work in tandem to regulate the stellar growth of a galaxy after a merger event. These results open a new door to studies of dual AGN and AGN pairs in general, and enable dual AGN to be used, for the first time, for studies of galaxy evolution.

  5. Stability and suppression of turbulence in relaxing molecular gas flows

    CERN Document Server

    Grigoryev, Yurii N

    2017-01-01

    This book presents an in-depth systematic investigation of a dissipative effect which manifests itself as the growth of hydrodynamic stability and suppression of turbulence in relaxing molecular gas flows. The work describes the theoretical foundations of a new way to control stability and laminar turbulent transitions in aerodynamic flows. It develops hydrodynamic models for describing thermal nonequilibrium gas flows which allow the consideration of suppression of inviscid acoustic waves in 2D shear flows. Then, nonlinear evolution of large-scale vortices and Kelvin-Helmholtz waves in relaxing shear flows are studied. Critical Reynolds numbers in supersonic Couette flows are calculated analytically and numerically within the framework of both linear and nonlinear classical energy hydrodynamic stability theories. The calculations clearly show that the relaxation process can appreciably delay the laminar-turbulent transition. The aim of the book is to show the new dissipative effect, which can be used for flo...

  6. Lagrangian solution of supersonic real gas flows

    Science.gov (United States)

    Loh, Ching-Yuen; Liou, Meng-Sing

    1993-01-01

    The present extention of a Lagrangian approach of the Riemann solution procedure, which was originally proposed for perfect gases, to real gases, is nontrivial and requires the development of an exact real-gas Riemann solver for the Lagrangian form of the conservation laws. Calculations including complex wave interactions of various types were conducted to test the accuracy and robustness of the approach. Attention is given to the case of 2D oblique waves' capture, where a slip line is clearly in evidence; the real gas effect is demonstrated in the case of a generic engine nozzle.

  7. Static Behaviour of Natural Gas and its Flow in Pipes

    OpenAIRE

    Ohirhian, Peter

    2010-01-01

    1. 2. A general differential equation that governs static behavior of any fluid and its flow in horizontal, uphill and downhill pipes has been developed. classical fourth order Runge-Kutta numerical method is programmed in Fortran 77, to test the equation and results are accurate. The program shows that a length ncrement as large as 10,000 ft can be used in the Runge-Kutta method of solution to differential equation during uphill gas flow and up to 5700ft for downhill gas flow The Runge-Kutta...

  8. Simulation of non-isothermal transient flow in gas pipeline

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira Junior, Luis Carlos; Soares, Matheus; Lima, Enrique Luis; Pinto, Jose Carlos [Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Quimica; Muniz, Cyro; Pires, Clarissa Cortes; Rochocz, Geraldo [ChemTech, Rio de Janeiro, RJ (Brazil)

    2009-07-01

    Modeling of gas pipeline usually considers that the gas flow is isothermal (or adiabatic) and that pressure changes occur instantaneously (quasi steady state approach). However, these assumptions are not valid in many important transient applications (changes of inlet and outlet flows/pressures, starting and stopping of compressors, changes of controller set points, among others). Besides, the gas properties are likely to depend simultaneously on the pipe position and on the operation time. For this reason, a mathematical model is presented and implemented in this paper in order to describe the gas flow in pipeline when pressure and temperature transients cannot be neglected. The model is used afterwards as a tool for reconciliation of available measured data. (author)

  9. Intercooler flow path for gas turbines: CFD design and experiments

    Energy Technology Data Exchange (ETDEWEB)

    Agrawal, A.K.; Gollahalli, S.R.; Carter, F.L. [Univ. of Oklahoma, Norman, OK (United States)] [and others

    1995-10-01

    The Advanced Turbine Systems (ATS) program was created by the U.S. Department of Energy to develop ultra-high efficiency, environmentally superior, and cost competitive gas turbine systems for generating electricity. Intercooling or cooling of air between compressor stages is a feature under consideration in advanced cycles for the ATS. Intercooling entails cooling of air between the low pressure (LP) and high pressure (BP) compressor sections of the gas turbine. Lower air temperature entering the HP compressor decreases the air volume flow rate and hence, the compression work. Intercooling also lowers temperature at the HP discharge, thus allowing for more effective use of cooling air in the hot gas flow path. The thermodynamic analyses of gas turbine cycles with modifications such as intercooling, recuperating, and reheating have shown that intercooling is important to achieving high efficiency gas turbines. The gas turbine industry has considerable interest in adopting intercooling to advanced gas turbines of different capacities. This observation is reinforced by the US Navys Intercooled-Recuperative (ICR) gas turbine development program to power the surface ships. In an intercooler system, the air exiting the LP compressor must be decelerated to provide the necessary residence time in the heat exchanger. The cooler air must subsequently be accelerated towards the inlet of the HP compressor. The circumferential flow nonuniformities inevitably introduced by the heat exchanger, if not isolated, could lead to rotating stall in the compressors, and reduce the overall system performance and efficiency. Also, the pressure losses in the intercooler flow path adversely affect the system efficiency and hence, must be minimized. Thus, implementing intercooling requires fluid dynamically efficient flow path with minimum flow nonuniformities and consequent pressure losses.

  10. Numerical studies of rock-gas flow in Yucca Mountain

    International Nuclear Information System (INIS)

    Ross, B.; Amter, S.; Lu, Ning

    1992-02-01

    A computer model (TGIF -- Thermal Gradient Induced Flow) of two-dimensional, steady-state rock-gas flow driven by temperature and humidity differences is described. The model solves for the ''fresh-water head,'' a concept that has been used in models of variable-density water flow but has not previously been applied to gas flow. With this approach, the model can accurately simulate the flows driven by small differences in temperature. The unsaturated tuffs of Yucca Mountain, Nevada, are being studied as a potential site for a repository for high-level nuclear waste. Using the TGIF model, preliminary calculations of rock-gas flow in Yucca Mountain are made for four east-west cross-sections through the mountain. Calculations are made for three repository temperatures and for several assumptions about a possible semi-confining layer above the repository. The gas-flow simulations are then used to calculate travel-time distributions for air and for radioactive carbon-14 dioxide from the repository to the ground surface

  11. Cascading Tesla Oscillating Flow Diode for Stirling Engine Gas Bearings

    Science.gov (United States)

    Dyson, Rodger

    2012-01-01

    Replacing the mechanical check-valve in a Stirling engine with a micromachined, non-moving-part flow diode eliminates moving parts and reduces the risk of microparticle clogging. At very small scales, helium gas has sufficient mass momentum that it can act as a flow controller in a similar way as a transistor can redirect electrical signals with a smaller bias signal. The innovation here forces helium gas to flow in predominantly one direction by offering a clear, straight-path microchannel in one direction of flow, but then through a sophisticated geometry, the reversed flow is forced through a tortuous path. This redirection is achieved by using microfluid channel flow to force the much larger main flow into this tortuous path. While microdiodes have been developed in the past, this innovation cascades Tesla diodes to create a much higher pressure in the gas bearing supply plenum. In addition, the special shape of the leaves captures loose particles that would otherwise clog the microchannel of the gas bearing pads.

  12. Real gas flow simulation in damaged distribution pipelines

    International Nuclear Information System (INIS)

    Kostowski, Wojciech J.; Skorek, Janusz

    2012-01-01

    The paper discusses chosen issues concerning damaged gas pipelines. Attention is paid to modelling the steady-state flow of natural gas in distribution pipelines, and the most commonly applied models of isothermal and adiabatic flow are evaluated for both the ideal and the real gas properties. A method of accounting for a leakage by means of a reference flow equation with a discharge coefficient is presented, and the dependency of the discharge coefficient on pressure is demonstrated both with literature data and the authors' experimental results. A relevant computational study of a pipeline failure is presented for a high- and a medium pressure pipeline. The importance of an appropriate choice of the flow model (isothermal or adiabatic flow of real or ideal gas) is demonstrated by the results of the study. It is shown that accounting for the variability of the discharge coefficient is required if medium pressure pipelines are analysed. However, it is eventually shown that the impact of the discharge coefficient on the predicted outflow rate is of lesser importance than that of the applied flow model. -- Highlights: ► Comparison of real/ideal gas, isothermal/adiabatic gas flow in a damaged pipeline. ► Variability of the discharge coefficient with pressure is demonstrated. ► Isothermal model predicts wrong values of downstream pressure, not just temperature. ► Isothermal model may cause significant error (for 2 case studies is >20%). ► Error in the discharge coefficient has a weak influence on the predicted flow rate.

  13. Gas microstrip detectors for X-ray tomographic flow imaging

    CERN Document Server

    Key, M J; Luggar, R D; Kundu, A

    2003-01-01

    A investigation into the suitability of gas microstrip detector technology for a high-speed industrial X-ray tomography system is reported. X-ray energies in the region 20-30 keV are well suited to the application, which involves imaging two-dimensional slices through gas/liquid multiphase pipeline flows for quantitative component fraction measurement. Stable operation over a period representing several hundred individual tomographic scans at gas gains of 500 is demonstrated using a Penning gas mixture of krypton/propylene.

  14. Building waste management core indicators through Spatial Material Flow Analysis: Net recovery and transport intensity indexes

    Energy Technology Data Exchange (ETDEWEB)

    Font Vivanco, David, E-mail: font@cml.leidenuniv.nl [Institut de Ciencia i Tecnologia Ambientals (ICTA), Departament d' Enginyeria Quimica, Universitat Autonoma de Barcelona (UAB), 08193 Bellaterra, Barcelona (Spain); Institute of Environmental Sciences (CML), Leiden University, P.O. Box 9518, 2300 RA Leiden (Netherlands); Puig Ventosa, Ignasi [ENT Environment and Management, Carrer Sant Joan 39, First Floor, 08800 Vilanova i la Geltru, Barcelona (Spain); Gabarrell Durany, Xavier [Institut de Ciencia i Tecnologia Ambientals (ICTA), Departament d' Enginyeria Quimica, Universitat Autonoma de Barcelona (UAB), 08193 Bellaterra, Barcelona (Spain)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Sustainability and proximity principles have a key role in waste management. Black-Right-Pointing-Pointer Core indicators are needed in order to quantify and evaluate them. Black-Right-Pointing-Pointer A systematic, step-by-step approach is developed in this study for their development. Black-Right-Pointing-Pointer Transport may play a significant role in terms of environmental and economic costs. Black-Right-Pointing-Pointer Policy action is required in order to advance in the consecution of these principles. - Abstract: In this paper, the material and spatial characterization of the flows within a municipal solid waste (MSW) management system are combined through a Network-Based Spatial Material Flow Analysis. Using this information, two core indicators are developed for the bio-waste fraction, the Net Recovery Index (NRI) and the Transport Intensity Index (TII), which are aimed at assessing progress towards policy-related sustainable MSW management strategies and objectives. The NRI approaches the capacity of a MSW management system for converting waste into resources through a systematic metabolic approach, whereas the TII addresses efficiency in terms of the transport requirements to manage a specific waste flow throughout the entire MSW management life cycle. Therefore, both indicators could be useful in assessing key MSW management policy strategies, such as the consecution of higher recycling levels (sustainability principle) or the minimization of transport by locating treatment facilities closer to generation sources (proximity principle). To apply this methodological approach, the bio-waste management system of the region of Catalonia (Spain) has been chosen as a case study. Results show the adequacy of both indicators for identifying those points within the system with higher capacity to compromise its environmental, economic and social performance and therefore establishing clear targets for policy

  15. Building waste management core indicators through Spatial Material Flow Analysis: Net recovery and transport intensity indexes

    International Nuclear Information System (INIS)

    Font Vivanco, David; Puig Ventosa, Ignasi; Gabarrell Durany, Xavier

    2012-01-01

    Highlights: ► Sustainability and proximity principles have a key role in waste management. ► Core indicators are needed in order to quantify and evaluate them. ► A systematic, step-by-step approach is developed in this study for their development. ► Transport may play a significant role in terms of environmental and economic costs. ► Policy action is required in order to advance in the consecution of these principles. - Abstract: In this paper, the material and spatial characterization of the flows within a municipal solid waste (MSW) management system are combined through a Network-Based Spatial Material Flow Analysis. Using this information, two core indicators are developed for the bio-waste fraction, the Net Recovery Index (NRI) and the Transport Intensity Index (TII), which are aimed at assessing progress towards policy-related sustainable MSW management strategies and objectives. The NRI approaches the capacity of a MSW management system for converting waste into resources through a systematic metabolic approach, whereas the TII addresses efficiency in terms of the transport requirements to manage a specific waste flow throughout the entire MSW management life cycle. Therefore, both indicators could be useful in assessing key MSW management policy strategies, such as the consecution of higher recycling levels (sustainability principle) or the minimization of transport by locating treatment facilities closer to generation sources (proximity principle). To apply this methodological approach, the bio-waste management system of the region of Catalonia (Spain) has been chosen as a case study. Results show the adequacy of both indicators for identifying those points within the system with higher capacity to compromise its environmental, economic and social performance and therefore establishing clear targets for policy prioritization. Moreover, this methodological approach permits scenario building, which could be useful in assessing the outcomes of

  16. Industrial aspects of gas-liquid two-phase flow

    International Nuclear Information System (INIS)

    Hewitt, G.F.

    1977-01-01

    The lecture begins by reviewing the various types of plant in which two phase flow occurs. Specifically, boiling plant, condensing plant and pipelines are reviewed, and the various two phase flow problems occurring in them are described. Of course, many other kinds of chemical engineering plant involve two phase flow, but are somewhat outside the scope of this lecture. This would include distillation columns, vapor-liquid separators, absorption towers etc. Other areas of industrial two phase flow which have been omitted for space reasons from this lecture are those concerned with gas/solids, liquid/solid and liquid/liquid flows. There then follows a description of some of the two phase flow processes which are relevant in industrial equipment and where special problems occur. The topics chosen are as follows: (1) pressure drop; (2) horizontal tubes - separation effects non-uniformites in heat transfer coefficient, effect of bends on dryout; (3) multicomponent mixtures - effects in pool boiling, mass transfer effects in condensation and Marangoni effects; (4) flow distribution - manifold problems in single phase flow, separation effects at a single T-junction in two phase flow and distribution in manifolds in two phase flow; (5) instability - oscillatory instability, special forms of instability in cryogenic systems; (6) nucleate boiling - effect of variability of surface, unresolved problems in forced convective nucleate boiling; and (7) shell side flows - flow patterns, cross flow boiling, condensation in cross flow

  17. Effect of surface wettability on flow patterns in vertical gas-liquid two-phase flow

    International Nuclear Information System (INIS)

    Nakamura, D.

    2005-01-01

    To examine the effect of the surface characteristics on the flow regime in two-phase flow, visualization study was performed using three test pipes, namely a no-coating pipe, a water-attracting coating pipe, a water-shedding coating pipe. Three flow regime maps were obtained based on the visual observation in the three pipes. In the water-attracting coating pipe, the slug flow-to-churn flow transition boundary was shifted to higher gas velocity at a given liquid velocity, whereas the churn flow-to-annular flow transition boundary was shifted to lower gas velocity at a given liquid velocity. In the water shedding coating pipe, the inverted-churn flow regime was observed in the region where the churn flow regime was to be observed in a no-coating pipe, whereas the droplet flow regime was observed in the region where the annular flow regime was to be observed in a no-coating pipe. The criteria for the slug flow-to-inverted-churn flow transition and the inverted-churn flow-to-droplet flow transition were modeled by force balance approaches. The modeled transition criteria could predict the observed flow transition boundaries reasonably well. (authors)

  18. Gas mass transfer for stratified flows

    International Nuclear Information System (INIS)

    Duffey, R.B.; Hughes, E.D.

    1995-01-01

    We analyzed gas absorption and release in water bodies using existing surface renewal theory. We show a new relation between turbulent momentum and mass transfer from gas to water, including the effects of waves and wave roughness, by evaluating the equilibrium integral turbulent dissipation due to energy transfer to the water from the wind. Using Kolmogoroff turbulence arguments the gas transfer velocity, or mass transfer coefficient, is then naturally and straightforwardly obtained as a non-linear function of the wind speed drag coefficient and the square root of the molecular diffusion coefficient. In dimensionless form, the theory predicts the turbulent Sherwood number to be Sh t = (2/√π)Sc 1/2 , where Sh t is based on an integral dissipation length scale in the air. The theory confirms the observed nonlinear variation of the mass transfer coefficient as a function of the wind speed; gives the correct transition with turbulence-centered models for smooth surfaces at low speeds; and predicts experimental data from both laboratory and environmental measurements within the data scatter. The differences between the available laboratory and field data measurements are due to the large differences in the drag coefficient between wind tunnels and oceans. The results also imply that the effect of direct aeration due to bubble entrainment at wave breaking is no more than a 20% increase in the mass transfer for the highest speeds. The theory has importance to mass transfer in both the geo-physical and chemical engineering literature

  19. Numerical Simulation of Natural Gas Flow in Anisotropic Shale Reservoirs

    KAUST Repository

    Negara, Ardiansyah

    2015-11-09

    Shale gas resources have received great attention in the last decade due to the decline of the conventional gas resources. Unlike conventional gas reservoirs, the gas flow in shale formations involves complex processes with many mechanisms such as Knudsen diffusion, slip flow (Klinkenberg effect), gas adsorption and desorption, strong rock-fluid interaction, etc. Shale formations are characterized by the tiny porosity and extremely low-permeability such that the Darcy equation may no longer be valid. Therefore, the Darcy equation needs to be revised through the permeability factor by introducing the apparent permeability. With respect to the rock formations, several studies have shown the existence of anisotropy in shale reservoirs, which is an essential feature that has been established as a consequence of the different geological processes over long period of time. Anisotropy of hydraulic properties of subsurface rock formations plays a significant role in dictating the direction of fluid flow. The direction of fluid flow is not only dependent on the direction of pressure gradient, but it also depends on the principal directions of anisotropy. Therefore, it is very important to take into consideration anisotropy when modeling gas flow in shale reservoirs. In this work, the gas flow mechanisms as mentioned earlier together with anisotropy are incorporated into the dual-porosity dual-permeability model through the full-tensor apparent permeability. We employ the multipoint flux approximation (MPFA) method to handle the full-tensor apparent permeability. We combine MPFA method with the experimenting pressure field approach, i.e., a newly developed technique that enables us to solve the global problem by breaking it into a multitude of local problems. This approach generates a set of predefined pressure fields in the solution domain in such a way that the undetermined coefficients are calculated from these pressure fields. In other words, the matrix of coefficients

  20. Numerical Simulation of Natural Gas Flow in Anisotropic Shale Reservoirs

    KAUST Repository

    Negara, Ardiansyah; Salama, Amgad; Sun, Shuyu; Elgassier, Mokhtar; Wu, Yu-Shu

    2015-01-01

    Shale gas resources have received great attention in the last decade due to the decline of the conventional gas resources. Unlike conventional gas reservoirs, the gas flow in shale formations involves complex processes with many mechanisms such as Knudsen diffusion, slip flow (Klinkenberg effect), gas adsorption and desorption, strong rock-fluid interaction, etc. Shale formations are characterized by the tiny porosity and extremely low-permeability such that the Darcy equation may no longer be valid. Therefore, the Darcy equation needs to be revised through the permeability factor by introducing the apparent permeability. With respect to the rock formations, several studies have shown the existence of anisotropy in shale reservoirs, which is an essential feature that has been established as a consequence of the different geological processes over long period of time. Anisotropy of hydraulic properties of subsurface rock formations plays a significant role in dictating the direction of fluid flow. The direction of fluid flow is not only dependent on the direction of pressure gradient, but it also depends on the principal directions of anisotropy. Therefore, it is very important to take into consideration anisotropy when modeling gas flow in shale reservoirs. In this work, the gas flow mechanisms as mentioned earlier together with anisotropy are incorporated into the dual-porosity dual-permeability model through the full-tensor apparent permeability. We employ the multipoint flux approximation (MPFA) method to handle the full-tensor apparent permeability. We combine MPFA method with the experimenting pressure field approach, i.e., a newly developed technique that enables us to solve the global problem by breaking it into a multitude of local problems. This approach generates a set of predefined pressure fields in the solution domain in such a way that the undetermined coefficients are calculated from these pressure fields. In other words, the matrix of coefficients

  1. Effect of pulsed corona discharge voltage and feed gas flow rate on dissolved ozone concentration

    Energy Technology Data Exchange (ETDEWEB)

    Prasetyaningrum, A., E-mail: ajiprasetyaningrum@gmail.com; Ratnawati,; Jos, B. [Department of Chemical Engineering, Faculty of Engineering, Diponegoro University Jl. Prof. H. Soedarto Tembalang, Semarang, Central Java, Indonesia, 50276 (Indonesia)

    2015-12-29

    Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O{sub 3}) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flow rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV.

  2. Effect of pulsed corona discharge voltage and feed gas flow rate on dissolved ozone concentration

    International Nuclear Information System (INIS)

    Prasetyaningrum, A.; Ratnawati,; Jos, B.

    2015-01-01

    Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O 3 ) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flow rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV

  3. Effect of pulsed corona discharge voltage and feed gas flow rate on dissolved ozone concentration

    Science.gov (United States)

    Prasetyaningrum, A.; Ratnawati, Jos, B.

    2015-12-01

    Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O3) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flow rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV.

  4. Development of a numerical model for fluid-structure interaction analysis of flow through and around an aquaculture net cage

    DEFF Research Database (Denmark)

    Chen, Hao; Christensen, Erik Damgaard

    2017-01-01

    In the present work, we developed a numerical model for fluid-structure interaction analysis of flow through and around an aquaculture net cage. The numerical model is based on the coupling between the porous media model and the lumped mass structural model. A novel interface was implemented...

  5. Gas flow and dust acceleration in a cometary Knudsen layer

    CERN Document Server

    Skorov, Yu V

    1999-01-01

    An analytical model of the innermost gas-dust coma region is proposed. The kinetic Knudsen layer adjacent to the surface of the cometary nucleus, where the initially non-equilibrium velocity distribution function of gas molecules $9 relaxes to Maxwell equilibrium distribution function and, as a result, the macro-characteristics of gas and dust flows vary several-fold, is considered. The gas phase model is based on the equations for mass, momentum and energy flux $9 conservation, and is a natural development of the Anisimov (1968) and Cercignani (1981) approaches. The analytical relations between the characteristics of the gas flow on the boundaries of the non- equilibrium layer and the $9 characteristics of the returning gas flow adsorbed by the surface are determined. These values form a consistent basis both for hydrodynamic models of the inner coma and for jet force models. Three particular models are presented: $9 (1) sublimation of a polyatomic one-component gas; (2) sublimation of a two-component polyat...

  6. Pulsatile pressure driven rarefied gas flow in long rectangular ducts

    Science.gov (United States)

    Tsimpoukis, Alexandros; Valougeorgis, Dimitris

    2018-04-01

    The pulsatile pressure driven fully developed flow of a rarefied gas through an orthogonal duct is investigated, based on the time-dependent linear Bhatnagar, Gross, and Krook equation, by decomposing the flow into its steady and oscillatory parts. The investigation is focused on the oscillatory part, which is characterized by the gas rarefaction and oscillation parameters, the duct aspect ratio, and the accommodation coefficient. As the oscillation frequency is increased, the amplitude of all macroscopic quantities is decreased, while their phase angle lag is increased reaching the limiting value of π/2. As the gas becomes more rarefied, higher frequencies are needed to trigger this behavior. At small and moderate frequencies, there is a critical degree of gas rarefaction, where a maximum flow rate is obtained. As the duct aspect ratio is decreased and tends to zero, the flow rate and mean wall shear stress amplitudes are increased, while their phase angle lags are slightly affected. The accommodation coefficient has a significant effect on the amplitude and a very weak one on the phase angle of the macroscopic quantities. The computation of the inertia and viscous forces clarifies when the flow consists of only one oscillating viscous region or of two regions, namely, the inviscid piston flow in the core and the oscillating Stokes layer at the wall with the velocity overshooting. Finally, the time average oscillatory pumping power is increased as the oscillation frequency is reduced and its maximum value is one half of the corresponding steady one.

  7. Conical flow near singular rays. [shock generation in ideal gas

    Science.gov (United States)

    Zahalak, G. I.; Myers, M. K.

    1974-01-01

    The steady flow of an ideal gas past a conical body is investigated by the method of matched asymptotic expansions, with particular emphasis on the flow near the singular ray occurring in linearized theory. The first-order problem governing the flow in this region is formulated, leading to the equation of Kuo, and an approximate solution is obtained in the case of compressive flow behind the main front. This solution is compared with the results of previous investigations with a view to assessing the applicability of the Lighthill-Whitham theories.

  8. About the statistical description of gas-liquid flows

    Energy Technology Data Exchange (ETDEWEB)

    Sanz, D.; Guido-Lavalle, G.; Carrica, P. [Centro Atomico Bariloche and Instituto Balseiro (Argentina)] [and others

    1995-09-01

    Elements of the probabilistic geometry are used to derive the bubble coalescence term of the statistical description of gas liquid flows. It is shown that the Boltzmann`s hypothesis, that leads to the kinetic theory of dilute gases, is not appropriate for this kind of flows. The resulting integro-differential transport equation is numerically integrated to study the flow development in slender bubble columns. The solution remarkably predicts the transition from bubbly to slug flow pattern. Moreover, a bubbly bimodal size distribution is predicted, which has already been observed experimentally.

  9. Gas flow in and out of a nuclear waste container

    International Nuclear Information System (INIS)

    Zwahlen, E.D.; Pigford, T.H.; Chambre, P.L.; Lee, W.W.L.

    1989-05-01

    We analyze the flow of gases out of and into a high-level-waste container in the unsaturated tuff of Yucca Mountain. Containers are expected to fail eventually by localized cracks and penetrations. Even though the penetrations may be small, argon gas initially in the hot container can leak out. As the waste package cools, the pressure inside the container can become less than atmospheric, and air can leak in. 14 C released from the hot fuel-cladding surface can leak out of penetrations, and air inleakage can mobilize additional 14 C and other volatile radioactive species as it oxidizes the fuel cladding and the spent fuel. In an earlier paper we studied the gas flow through container penetrations occurring at the time of emplacement. Here we analyze the flow of gas for various penetration sizes occurring at 300 years. 3 refs., 2 figs

  10. Hybrid continuum–molecular modelling of multiscale internal gas flows

    International Nuclear Information System (INIS)

    Patronis, Alexander; Lockerby, Duncan A.; Borg, Matthew K.; Reese, Jason M.

    2013-01-01

    We develop and apply an efficient multiscale method for simulating a large class of low-speed internal rarefied gas flows. The method is an extension of the hybrid atomistic–continuum approach proposed by Borg et al. (2013) [28] for the simulation of micro/nano flows of high-aspect ratio. The major new extensions are: (1) incorporation of fluid compressibility; (2) implementation using the direct simulation Monte Carlo (DSMC) method for dilute rarefied gas flows, and (3) application to a broader range of geometries, including periodic, non-periodic, pressure-driven, gravity-driven and shear-driven internal flows. The multiscale method is applied to micro-scale gas flows through a periodic converging–diverging channel (driven by an external acceleration) and a non-periodic channel with a bend (driven by a pressure difference), as well as the flow between two eccentric cylinders (with the inner rotating relative to the outer). In all these cases there exists a wide variation of Knudsen number within the geometries, as well as substantial compressibility despite the Mach number being very low. For validation purposes, our multiscale simulation results are compared to those obtained from full-scale DSMC simulations: very close agreement is obtained in all cases for all flow variables considered. Our multiscale simulation is an order of magnitude more computationally efficient than the full-scale DSMC for the first and second test cases, and two orders of magnitude more efficient for the third case

  11. Pattern Extraction Algorithm for NetFlow-Based Botnet Activities Detection

    Directory of Open Access Journals (Sweden)

    Rafał Kozik

    2017-01-01

    Full Text Available As computer and network technologies evolve, the complexity of cybersecurity has dramatically increased. Advanced cyber threats have led to current approaches to cyber-attack detection becoming ineffective. Many currently used computer systems and applications have never been deeply tested from a cybersecurity point of view and are an easy target for cyber criminals. The paradigm of security by design is still more of a wish than a reality, especially in the context of constantly evolving systems. On the other hand, protection technologies have also improved. Recently, Big Data technologies have given network administrators a wide spectrum of tools to combat cyber threats. In this paper, we present an innovative system for network traffic analysis and anomalies detection to utilise these tools. The systems architecture is based on a Big Data processing framework, data mining, and innovative machine learning techniques. So far, the proposed system implements pattern extraction strategies that leverage batch processing methods. As a use case we consider the problem of botnet detection by means of data in the form of NetFlows. Results are promising and show that the proposed system can be a useful tool to improve cybersecurity.

  12. Bayesian quantification of thermodynamic uncertainties in dense gas flows

    International Nuclear Information System (INIS)

    Merle, X.; Cinnella, P.

    2015-01-01

    A Bayesian inference methodology is developed for calibrating complex equations of state used in numerical fluid flow solvers. Precisely, the input parameters of three equations of state commonly used for modeling the thermodynamic behavior of the so-called dense gas flows, – i.e. flows of gases characterized by high molecular weights and complex molecules, working in thermodynamic conditions close to the liquid–vapor saturation curve – are calibrated by means of Bayesian inference from reference aerodynamic data for a dense gas flow over a wing section. Flow thermodynamic conditions are such that the gas thermodynamic behavior strongly deviates from that of a perfect gas. In the aim of assessing the proposed methodology, synthetic calibration data – specifically, wall pressure data – are generated by running the numerical solver with a more complex and accurate thermodynamic model. The statistical model used to build the likelihood function includes a model-form inadequacy term, accounting for the gap between the model output associated to the best-fit parameters and the true phenomenon. Results show that, for all of the relatively simple models under investigation, calibrations lead to informative posterior probability density distributions of the input parameters and improve the predictive distribution significantly. Nevertheless, calibrated parameters strongly differ from their expected physical values. The relationship between this behavior and model-form inadequacy is discussed. - Highlights: • Development of a Bayesian inference procedure for calibrating dense-gas flow solvers. • Complex thermodynamic models calibrated by using aerodynamic data for the flow. • Preliminary Sobol analysis used to reduce parameter space. • Piecewise polynomial surrogate model constructed to reduce computational cost. • Calibration results show the crucial role played by model-form inadequacies

  13. Prediction of strongly-heated internal gas flows

    International Nuclear Information System (INIS)

    McEligot, D.M.; Shehata, A.M.; Kunugi, Tomoaki

    1997-01-01

    The purposes of the present article are to remind practitioners why the usual textbook approaches may not be appropriate for treating gas flows heated from the surface with large heat fluxes and to review the successes of some recent applications of turbulence models to this case. Simulations from various turbulence models have been assessed by comparison to the measurements of internal mean velocity and temperature distributions by Shehata for turbulent, laminarizing and intermediate flows with significant gas property variation. Of about fifteen models considered, five were judged to provide adequate predictions

  14. Neutronics of a mixed-flow gas-core reactor

    International Nuclear Information System (INIS)

    Soran, P.D.; Hansen, G.E.

    1977-11-01

    The study was made to investigate the neutronic feasibility of a mixed-flow gas-core reactor. Three reactor concepts were studied: four- and seven-cell radial reactors and a seven-cell scallop reactor. The reactors were fueled with UF 6 (either U-233 or U-235) and various parameters were varied. A four-cell reactor is not practical nor is the U-235 fueled seven-cell radial reactor; however, the 7-cell U-233 radial and scallop reactors can satisfy all design criteria. The mixed flow gas core reactor is a very attractive reactor concept and warrants further investigation

  15. Turbine exhaust diffuser with region of reduced flow area and outer boundary gas flow

    Science.gov (United States)

    Orosa, John

    2014-03-11

    An exhaust diffuser system and method for a turbine engine. The outer boundary may include a region in which the outer boundary extends radially inwardly toward the hub structure and may direct at least a portion of an exhaust flow in the diffuser toward the hub structure. At least one gas jet is provided including a jet exit located on the outer boundary. The jet exit may discharge a flow of gas downstream substantially parallel to an inner surface of the outer boundary to direct a portion of the exhaust flow in the diffuser toward the outer boundary to effect a radially outward flow of at least a portion of the exhaust gas flow toward the outer boundary to balance an aerodynamic load between the outer and inner boundaries.

  16. Flow induced vibrations in gas tube assembly of centrifuge

    International Nuclear Information System (INIS)

    Alam, M.; Atta, M.A.; Mirza, J.A.; Khan, A.Q.

    1986-01-01

    A centrifuge essentially consists of a rotor rotating at very high speed. Gas tube assembly, located at the center of the rotor, is used to introduce feed gas into the rotor and remove product and waste streams from it. The gas tube assembly is thus a static component, the product and waste scoops of which are lying in the high pressure region of a fluid rotating at very high speed. This can cause flow induced vibrations in the gas tube assembly. Such vibrations affect not only the mechanical stability of the gas tube assembly but may also reduce the separative power of the centrifuge. In a cascade, if some of the centrifuges have gas tube vibration, then cascade performance will be affected. A theoretical analysis of the effect of waste tube vibrations on product and waste flow rates and pressures in the centrifuge is presented. A simple stage consisting of two centrifuges, in which one has tube vibration, is considered for this purpose. The results are compared with experiment. It is shown that waste tube vibration generates oscillations in waste and product flow rates that are observable outside the centrifuge. (author)

  17. Response of small pitot tubes in gas-liquid flows

    International Nuclear Information System (INIS)

    Davis, M.R.

    1980-01-01

    The pressure rise experienced by a pitot tube immersed in a bubbly gas-liquid mixture flow exceeds that predicted by homogeneous flow analysis under conditions where the pitot is smaller than the mean bubble size. A systematic dependence of the deviation from homogeneous flow analysis exists, depending upon the mixture void fraction. A maximum effect is observed at a void fraction of 0.60, where the pressure rise was found to be 1.73 times the predicted stagnation pressure rise or 0.87 of the mixture momentum flux density. The magnitude of these effects is comparable with similar effects reported elsewhere for gas/solid mixture flow due to relative motion between phases in the vicinity of the sensing probe tip. (orig.)

  18. Stability investigations of relaxing molecular gas flows. Results and perspectives

    Science.gov (United States)

    Grigor'ev, Yurii N.; Ershov, Igor V.

    2017-10-01

    This article presents results of systematic investigations of a dissipative effect which manifests itself as the growth of hydrodynamic stability and suppression of turbulence in relaxing molecular gas flows. The effect can be a new way for control stability and laminar turbulent transition in aerodynamic flows. The consideration of suppression of inviscid acoustic waves in 2D shear flows is presented. Nonlinear evolution of large-scale vortices and Kelvin — Helmholtz waves in relaxing shear flows are studied. Critical Reynolds numbers in supersonic Couette flows are calculated analytically and numerically within the framework of both classical linear and nonlinear energy hydrodynamic stability theories. The calculations clearly show that the relaxation process can appreciably delay the laminar-turbulent transition. The aim of this article is to show the new dissipative effect, which can be used for flow control and laminarization.

  19. Flow and separation in gas centrifuge with Beams type circulation

    International Nuclear Information System (INIS)

    Ajsen, Eh.M.; Borisevich, V.D.; Levin, E.V.

    1992-01-01

    Structure of the secondary circulation flows in the working chamber of gas centrifuge for uranium isotope separation is studied using the numerical methods. Influence of the circulation thermal component on the centrifuge efficiency is analyzed. The contribution of useful component concentration difference of binary isotope mixture in feeding flows to the centrifuge efficiency is determined. Dependence of concentration optimal difference, whereby the maximum efficiency is achieved, on temperature distribution on the rotor side wall is found

  20. Analytical treatment of gas flows through multilayer insulation, project 1

    Science.gov (United States)

    Lin, J. T.

    1972-01-01

    A theoretical investigation of gas flow inside a multilayer insulation system was made for the case of the broadside pumping process. A set of simultaneous first-order differential equations for the temperature and pressure of the gas molecules through the perforations on the insulation layers. A modified Runge-Kutta method was used for numerical experiment. The numerical stability problem was also investigated. It was shown that when the relaxation time is less than the time period over which the gas properties change appreciably, the set of differential equations can be replaced by a set of algebraic equations for solution. Numerical examples were given and comparisons with experimental data were made.

  1. Extended Macroscopic Study of Dilute Gas Flow within a Microcavity

    Directory of Open Access Journals (Sweden)

    Mohamed Hssikou

    2016-01-01

    Full Text Available The behaviour of monatomic and dilute gas is studied in the slip and early transition regimes using the extended macroscopic theory. The gas is confined within a two-dimensional microcavity where the longitudinal sides are in the opposite motion with constant velocity ±Uw. The microcavity walls are kept at the uniform and reference temperature T0. Thus, the gas flow is transported only by the shear stress induced by the motion of upper and lower walls. From the macroscopic point of view, the regularized 13-moment equations of Grad, R13, are solved numerically. The macroscopic gas proprieties are studied for different values of the so-called Knudsen number (Kn, which gives the gas-rarefaction degree. The results are compared with those obtained using the classical continuum theory of Navier-Stokes and Fourier (NSF.

  2. Measured gas and particle temperatures in VTT's entrained flow reactor

    DEFF Research Database (Denmark)

    Clausen, Sønnik; Sørensen, L.H.

    2006-01-01

    Particle and gas temperature measurements were carried out in experiments on VTTs entrained flow reactor with 5% and 10% oxygen using Fourier transform infrared emission spectroscopy (FTIR). Particle temperature measurements were performed on polish coal,bark, wood, straw particles, and bark...... and wood particles treated with additive. A two-color technique with subtraction of the background light was used to estimate particle temperatures during experiments. A transmission-emission technique was used tomeasure the gas temperature in the reactor tube. Gas temperature measurements were in good...... agreement with thermocouple readings. Gas lines and bands from CO, CO2 and H2O can be observed in the spectra. CO was only observed at the first measuring port (100ms) with the strongest CO-signal seen during experiments with straw particles. Variations in gas concentration (CO2 and H2O) and the signal from...

  3. Wet gas flow modeling for a vertically mounted Venturi meter

    International Nuclear Information System (INIS)

    Xu, Lijun; Zhou, Wanlu; Li, Xiaomin

    2012-01-01

    Venturi meters are playing an increasingly important role in wet gas metering in natural gas and oil industries. Due to the effect of liquid in a wet gas, the differential pressure over the converging section of a Venturi meter is higher than that when a pure gas flows through with the same flow rate. This phenomenon is referred to as over-reading. Thus, a correction for the over-reading is required. Most of the existing wet gas models are more suitable for higher pressure (>2 MPa) than lower pressure ( 0.5) than lower quality (<0.5) in recent years. However, conditions of lower pressure and lower quality also widely exist in the gas and oil industries. By comparing the performances of eight existing wet gas models in low-pressure range of 0.26–0.86 MPa and low-quality range of 0.07–0.36 with a vertically mounted Venturi meter of diameter ratio 0.45, de Leeuw's model was proven to perform best. Derived from de Leeuw's model, a modified model with better performance for the low-pressure and low-quality ranges was obtained. Experimental data showed that the root mean square of the relative errors of the over-reading was 2.30%. (paper)

  4. Statistical parameter characteristics of gas-phase fluctuations for gas-liquid intermittent flow

    Energy Technology Data Exchange (ETDEWEB)

    Matsui, G.; Monji, H.; Takaguchi, M. [Univ. of Tsukuba (Japan)

    1995-09-01

    This study deals with theoretical analysis on the general behaviour of statistical parameters of gas-phase fluctuations and comparison of statistical parameter characteristics for the real void fraction fluctuations measured with those for the wave form modified the real fluctuations. In order to investigate the details of the relation between the behavior of the statistical parameters in real intermittent flow and analytical results obtained from information on the real flow, the distributions of statistical parameters for general fundamental wave form of gas-phase fluctuations are discussed in detail. By modifying the real gas-phase fluctuations to a trapezoidaly wave, the experimental results can be directly compared with the analytical results. The analytical results for intermittent flow show that the wave form parameter, and the total amplitude of void fraction fluctuations, affects strongly on the statistical parameter characteristics. The comparison with experiment using nitrogen gas-water intermittent flow suggests that the parameters of skewness and excess may be better as indicators of flow pattern. That is, the macroscopic nature of intermittent flow can be grasped by the skewness and the excess, and the detailed flow structure may be described by the mean and the standard deviation.

  5. Statistical parameter characteristics of gas-phase fluctuations for gas-liquid intermittent flow

    International Nuclear Information System (INIS)

    Matsui, G.; Monji, H.; Takaguchi, M.

    1995-01-01

    This study deals with theoretical analysis on the general behaviour of statistical parameters of gas-phase fluctuations and comparison of statistical parameter characteristics for the real void fraction fluctuations measured with those for the wave form modified the real fluctuations. In order to investigate the details of the relation between the behavior of the statistical parameters in real intermittent flow and analytical results obtained from information on the real flow, the distributions of statistical parameters for general fundamental wave form of gas-phase fluctuations are discussed in detail. By modifying the real gas-phase fluctuations to a trapezoidaly wave, the experimental results can be directly compared with the analytical results. The analytical results for intermittent flow show that the wave form parameter, and the total amplitude of void fraction fluctuations, affects strongly on the statistical parameter characteristics. The comparison with experiment using nitrogen gas-water intermittent flow suggests that the parameters of skewness and excess may be better as indicators of flow pattern. That is, the macroscopic nature of intermittent flow can be grasped by the skewness and the excess, and the detailed flow structure may be described by the mean and the standard deviation

  6. Dynamic Modeling Strategy for Flow Regime Transition in Gas-Liquid Two-Phase Flows

    Directory of Open Access Journals (Sweden)

    Xia Wang

    2012-12-01

    Full Text Available In modeling gas-liquid two-phase flows, the concept of flow regimes has been widely 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 flow regime dependent. Current nuclear reactor safety analysis codes, such as RELAP5, classify flow regimes using flow regime maps or transition criteria that were developed for steady-state, fully-developed flows. As two-phase flows are dynamic in nature, it is important to model the flow regime transitions dynamically to more accurately predict the two-phase flows. The present work aims to develop a dynamic modeling strategy to determine flow regimes in gas-liquid two-phase flows through 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 of the interfacial area, fluid particle (bubble or liquid droplet disintegration, boiling and evaporation, and the destruction of the interfacial area, fluid particle coalescence and condensation. For 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 shapes, namely group-1 and group-2 bubbles. A preliminary approach to dynamically identify the flow regimes is discussed, in which discriminators are based on the predicted information, such as the void fraction and interfacial area concentration. The flow regime predicted with this method shows good agreement with the experimental observations.

  7. Gas-solid trickle flow hydrodynamics in a packed column

    NARCIS (Netherlands)

    Westerterp, K.R.; Kuczynski, M.

    1987-01-01

    The pressure gradient and the static and the dynamic hold-up have been measured for a system consisting of a Fluid Cracking Catalyst (FCC) of 30–150 × 10−6 m diameter, trickling over a packed bed and with a gas streaming in countercurrent flow. The experiments were carried out at ambient conditions

  8. Free-Molecular Gas Flow in Narrow (Nanoscale) Channel

    Czech Academy of Sciences Publication Activity Database

    Levdansky, V.V.; Roldugin, V.I.; Žďanov, V.M.; Ždímal, Vladimír

    2014-01-01

    Roč. 87, č. 4 (2014), s. 802-814 ISSN 1062-0125 Grant - others:BRFFI(BY) T12P-018; RFBR(RU) 12-08-90009 Institutional support: RVO:67985858 Keywords : narrow channels * free-molecular gas flow * surface diffusion Subject RIV: CF - Physical ; Theoretical Chemistry

  9. Numerical simulations of rarefied gas flows in thin film processes

    NARCIS (Netherlands)

    Dorsman, R.

    2007-01-01

    Many processes exist in which a thin film is deposited from the gas phase, e.g. Chemical Vapor Deposition (CVD). These processes are operated at ever decreasing reactor operating pressures and with ever decreasing wafer feature dimensions, reaching into the rarefied flow regime. As numerical

  10. Analytical study of solids-gas two phase flow

    International Nuclear Information System (INIS)

    Hosaka, Minoru

    1977-01-01

    Fundamental studies were made on the hydrodynamics of solids-gas two-phase suspension flow, in which very small solid particles are mixed in a gas flow to enhance the heat transfer characteristics of gas cooled high temperature reactors. Especially, the pressure drop due to friction and the density distribution of solid particles are theoretically analyzed. The friction pressure drop of two-phase flow was analyzed based on the analytical result of the single-phase friction pressure drop. The calculated values of solid/gas friction factor as a function of solid/gas mass loading are compared with experimental results. Comparisons are made for Various combinations of Reynolds number and particle size. As for the particle density distribution, some factors affecting the non-uniformity of distribution were considered. The minimum of energy dispersion was obtained with the variational principle. The suspension density of particles was obtained as a function of relative distance from wall and was compared with experimental results. It is concluded that the distribution is much affected by the particle size and that the smaller particles are apt to gather near the wall. (Aoki, K.)

  11. Lessons from wet gas flow metering systems using differential measurements devices: Testing and flow modelling results

    Energy Technology Data Exchange (ETDEWEB)

    Cazin, J.; Couput, J.P.; Dudezert, C. et al

    2005-07-01

    A significant number of wet gas meters used for high GVF and very high GVF are based on differential pressure measurements. Recent high pressure tests performed on a variety of different DP devices on different flow loops are presented. Application of existing correlations is discussed for several DP devices including Venturi meters. For Venturi meters, deviations vary from 9% when using the Murdock correlation to less than 3 % with physical based models. The use of DP system in a large domain of conditions (Water Liquid Ratio) especially for liquid estimation will require information on the WLR This obviously raises the question of the gas and liquid flow metering accuracy in wet gas meters and highlight needs to understand AP systems behaviour in wet gas flows (annular / mist / annular mist). As an example, experimental results obtained on the influence of liquid film characteristics on a Venturi meter are presented. Visualizations of the film upstream and inside the Venturi meter are shown. They are completed by film characterization. The AP measurements indicate that for a same Lockhart Martinelli parameter, the characteristics of the two phase flow have a major influence on the correlation coefficient. A 1D model is defined and the results are compared with the experiments. These results indicate that the flow regime influences the AP measurements and that a better modelling of the flow phenomena is needed even for allocation purposes. Based on that, lessons and way forward in wet gas metering systems improvement for allocation and well metering are discussed and proposed. (author) (tk)

  12. Gas flows in S-E binary systems of galaxies

    Science.gov (United States)

    Sotnikova, N. YA.

    1990-01-01

    Tidal interaction between the galaxies in binary systems leads to important consequences. Some peculiarities in galactic morphology as well as the transfer of matter from one galaxy to another may be due to this factor. In particular, gas flows in intergalactic space may be formed. Such flows enriching one component with gas from the other may play a substantial role in the evolution of mixed (S-E) pairs. One can mention several facts corroborating the possibility of the gas transfer from the spiral to the elliptical galaxy. High HI content (10(exp 7) to 10(exp 9) solar mass) is detected in nearly 40 E galaxies (Bottinelli and Gougenheim, 1979; Knapp et al., 1985). Such galaxies are often members of pairs or of multiple systems including an S galaxy, which may be the source of gas (Smirnov and Komberg, 1980). Moreover, the gas kinematics and its distribution also indicate an external origin for this gas (Knapp et al., 1985). In many cases there is an outer gaseous disk. The directions of the disk and of stellar rotation don't always coincide (van Gorkom et al., 1985; Varnas et al., 1987). The galaxy colors in S-E pairs are correlated (the Holmberg effect): bluer ellipticals have spiral components that are usually bluer (Demin et al., 1984). The fraction of E galaxies with emission lines (N sub em) in S-E pairs showing traces of tidal interaction is twice as large (N sub em approx. equals 0.24) as in pairs without interaction (N sub em approx. equals 0.12) (Sotnikova, 1988b). Since the presence of emission lines in a galaxy spectrum strongly depends on gas content, this fact also leads to the conclusion that ellipticals in interacting S-E pairs are enriched with gas. These facts may be considered as a serious indication of the existence of gas transfer. Hence, investigation of this process is of interest.

  13. The impact of dry matter loss during herbaceous biomass storage on net greenhouse gas emissions from biofuels production

    International Nuclear Information System (INIS)

    Emery, Isaac R.; Mosier, Nathan S.

    2012-01-01

    Life cycle inventory models of greenhouse gas emissions from biofuel production have become tightly integrated into government mandates and other policies to encourage biofuel production. Current models do not include life cycle impacts of biomass storage or reflect current literature on emissions from soil and biomass decomposition. In this study, the GREET model framework was used to determine net greenhouse gas emissions during ethanol production from corn and switchgrass via three biomass storage systems: wet ensiling of whole corn, and indoor and outdoor dry bale storage of corn stover and switchgrass. Dry matter losses during storage were estimated from the literature and used to modify GREET inventory analysis. Results showed that biomass stability is a key parameter affecting fuel production per farmed hectare and life cycle greenhouse gas emissions. Corn silage may generate 5358 L/ha of ethanol at 26.5 g CO 2 eq/MJ, relative to 5654 L/ha at 52.3 g CO 2 eq/MJ from combined corn stover and conventional grain corn ethanol production, or 3919 L/ha at 21.3 g CO 2 eq/MJ from switchgrass. Dry matter losses can increase net emissions by 3–25% (ensiling), 5–53% (bales outdoors), or 1–12% (bales indoors), decreasing the net GHG reduction of ethanol over gasoline by up to 10.9%. Greater understanding of biomass storage losses and greenhouse gas fluxes during storage is necessary to accurately assess biomass storage options to ensure that the design of biomass supply logistics systems meet GHG reduction mandates for biofuel production. -- Highlights: ► Analyzed the impact of biomass loss during storage. ► Probable dry matter losses strongly depend on storage method and infrastructure. ► Assessed impact of storage losses on LCA for cellulosic ethanol production. ► Storage losses increase GHG emissions by 1–53% depending upon storage conditions.

  14. Nets solution of flow for gases, using the Balance Pattern of Nodes and the method of linealization of equations

    International Nuclear Information System (INIS)

    Narvaez, Paulo Cesar

    1999-01-01

    The dimension of nets of distribution of gases is a complex problem, so much for the diversity of the phenomena that they are presented, like for the variation of the properties of the fluids, especially, the density for effect of the changes in the pressure along the net. This work presents a model for its simulation starting from the deduction of the general equation of flow in stable and isothermal state, its inclusion in the pattern of balance of nodes and the solution of this for the method of linealization of equations. Additionally, a summary of the empiric equations more used is made for the calculation of the fall of pressure for gases flowing in pipes and an example that it illustrates the application of the pattern and the developed method

  15. Effects of gas chamber geometry and gas flow on the neutron production in a fast plasma focus neutron source

    International Nuclear Information System (INIS)

    Tarifeño-Saldivia, Ariel; Soto, Leopoldo

    2014-01-01

    This work reports that gas chamber geometry and gas flow management substantially affect the neutron production of a repetitive fast plasma focus. The gas flow rate is the most sensitive parameter. An appropriate design of the gas chamber combined with a suitable flow-rate management can lead to improvements in the neutron production of one order of magnitude working in a fast repetitive mode. (paper)

  16. A study of stratified gas-liquid pipe flow

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, George W.

    2005-07-01

    This work includes both theoretical modelling and experimental observations which are relevant to the design of gas condensate transport lines. Multicomponent hydrocarbon gas mixtures are transported in pipes over long distances and at various inclinations. Under certain circumstances, the heavier hydrocarbon components and/or water vapour condense to form one or more liquid phases. Near the desired capacity, the liquid condensate and water is efficiently transported in the form of a stratified flow with a droplet field. During operating conditions however, the flow rate may be reduced allowing liquid accumulation which can create serious operational problems due to large amounts of excess liquid being expelled into the receiving facilities during production ramp-up or even in steady production in severe cases. In particular, liquid tends to accumulate in upward inclined sections due to insufficient drag on the liquid from the gas. To optimize the transport of gas condensates, a pipe diameters should be carefully chosen to account for varying flow rates and pressure levels which are determined through the knowledge of the multiphase flow present. It is desirable to have a reliable numerical simulation tool to predict liquid accumulation for various flow rates, pipe diameters and pressure levels which is not presently accounted for by industrial flow codes. A critical feature of the simulation code would include the ability to predict the transition from small liquid accumulation at high flow rates to large liquid accumulation at low flow rates. A semi-intermittent flow regime of roll waves alternating with a partly backward flowing liquid film has been observed experimentally to occur for a range of gas flow rates. Most of the liquid is transported in the roll waves. The roll wave regime is not well understood and requires fundamental modelling and experimental research. The lack of reliable models for this regime leads to inaccurate prediction of the onset of

  17. The Measurement of the Relationship between Taiwan’s Bond Funds’ Net Flow and the Investment Risk -Threshold Autoregressive Model

    OpenAIRE

    Wo-Chiang Lee; Joe-Ming Lee

    2014-01-01

    This article applies the threshold autoregressive model to investigate the relationship between bond funds’ net flow and investment risk in Taiwan. Our empirical findings show that bond funds’ investors are concerned about the investment return and neglect the investment risk. In particular, when expanding the size of the bond funds, fund investors believe that the fund cannot lose any money on investment products. In order to satisfy investors, bond fund managers only target short-term retur...

  18. NetFCM: A Semi-Automated Web-Based Method for Flow Cytometry Data Analysis

    DEFF Research Database (Denmark)

    Frederiksen, Juliet Wairimu; Buggert, Marcus; Karlsson, Annika C.

    2014-01-01

    data analysis has become more complex and labor-intensive than previously. We have therefore developed a semi-automatic gating strategy (NetFCM) that uses clustering and principal component analysis (PCA) together with other statistical methods to mimic manual gating approaches. NetFCM is an online...... tool both for subset identification as well as for quantification of differences between samples. Additionally, NetFCM can classify and cluster samples based on multidimensional data. We tested the method using a data set of peripheral blood mononuclear cells collected from 23 HIV-infected individuals...... corresponding to those obtained by manual gating strategies. These data demonstrate that NetFCM has the potential to identify relevant T cell populations by mimicking classical FCM data analysis and reduce the subjectivity and amount of time associated with such analysis. (c) 2014 International Society...

  19. Interaction of Liquid Film Flow of Direct Vessel Injection Under the Cross Directional Gas Flow

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Han-sol; Lee, Jae-young [Handong Global University, Pohang (Korea, Republic of); Euh, Dong-Jin [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    In order to obtain a proper scaling law of the flow, local information of the flow was investigated experimentally and also numerically. A series of experiments were conducted in the 1/20 modified linear scaled plate type test rig to analyze a liquid film from ECC water injection through the DVI nozzle to the downcomer wall. The present study investigates liquid film flow generated in a downcomer of direct vessel injection (DVI) system which is employed as an emergency core cooling (ECC) system during a loss of coolant accident in the Korea nuclear power plant APR1400. During the late reflooding, complicated multi-phase flow phenomena including the wavy film flow, film breakup, entrainment, liquid film shift due to interfacial drag and gas jet impingement occur. A confocal chromatic sensor was used to measure the local instantaneous liquid film thickness and a hydraulic jump in the film flow and boundaries of the film flow. It was found that CFD analysis results without surface tension model showed some difference with the data in surface tension dominated flow region. For the interaction between a liquid film and gas shear flow, CFD results make a good agreement with the real liquid film dynamics in the case of low film Reynolds number or low Weber number flow. In the 1/20 scaled plate type experiment and simulation, the deformed spreading profile results seem to accord with each other at the relatively low We and Re regime.

  20. Coupling of a two phase gas liquid 3D Darcy flow in fractured porous media with a 1D free gas flow

    OpenAIRE

    Brenner , Konstantin; Masson , Roland; Trenty , Laurent; Zhang , Yumeng

    2015-01-01

    A model coupling a three dimensional gas liquid compositional Darcy flow in a frac-tured porous medium, and a one dimensional compositional free gas flow is presented. The coupling conditions at the interface between the gallery and the porous medium account for the molar normal fluxes continuity for each component, the gas liquid thermody-namical equilibrium, the gas pressure continuity and the gas and liquid molar fractions continuity. The fractures are represented as interfaces of codimens...

  1. State Token Petri Net modeling method for formal verification of computerized procedure including operator's interruptions of procedure execution flow

    International Nuclear Information System (INIS)

    Kim, Yun Goo; Seong, Poong Hyun

    2012-01-01

    The Computerized Procedure System (CPS) is one of the primary operating support systems in the digital Main Control Room. The CPS displays procedure on the computer screen in the form of a flow chart, and displays plant operating information along with procedure instructions. It also supports operator decision making by providing a system decision. A procedure flow should be correct and reliable, as an error would lead to operator misjudgement and inadequate control. In this paper we present a modeling for the CPS that enables formal verification based on Petri nets. The proposed State Token Petri Nets (STPN) also support modeling of a procedure flow that has various interruptions by the operator, according to the plant condition. STPN modeling is compared with Coloured Petri net when they are applied to Emergency Operating Computerized Procedure. A converting program for Computerized Procedure (CP) to STPN has been also developed. The formal verification and validation methods of CP with STPN increase the safety of a nuclear power plant and provide digital quality assurance means that are needed when the role and function of the CPS is increasing.

  2. PREFACE: 1st European Conference on Gas Micro Flows (GasMems 2012)

    Science.gov (United States)

    Frijns, Arjan; Valougeorgis, Dimitris; Colin, Stéphane; Baldas, Lucien

    2012-05-01

    The aim of the 1st European Conference on Gas Micro Flows is to advance research in Europe and worldwide in the field of gas micro flows as well as to improve global fundamental knowledge and to enable technological applications. Gas flows in microsystems are of great importance and touch almost every industrial field (e.g. fluidic microactuators for active control of aerodynamic flows, vacuum generators for extracting biological samples, mass flow and temperature micro-sensors, pressure gauges, micro heat-exchangers for the cooling of electronic components or for chemical applications, and micro gas analyzers or separators). The main characteristic of gas microflows is their rarefaction, which for device design often requires modelling and simulation both by continuous and molecular approaches. In such flows various non-equilibrium transport phenomena appear, while the role played by the interaction between the gas and the solid device surfaces becomes essential. The proposed models of boundary conditions often need an empirical adjustment strongly dependent on the micro manufacturing technique. The 1st European Conference on Gas Micro Flows is organized under the umbrella of the recently established GASMEMS network (www.gasmems.eu/) consisting of 13 participants and six associate members. The main objectives of the network are to structure research and train researchers in the fields of micro gas dynamics, measurement techniques for gaseous flows in micro experimental setups, microstructure design and micro manufacturing with applications in lab and industry. The conference takes place on June 6-8 2012, at the Skiathos Palace Hotel, on the beautiful island of Skiathos, Greece. The conference has received funding from the European Community's Seventh Framework Programme FP7/2007-2013 under grant agreement ITN GASMEMS no. 215504. It owes its success to many people. We would like to acknowledge the support of all members of the Scientific Committee and of all

  3. Method and system for gas flow mitigation of molecular contamination of optics

    Science.gov (United States)

    Delgado, Gildardo; Johnson, Terry; Arienti, Marco; Harb, Salam; Klebanoff, Lennie; Garcia, Rudy; Tahmassebpur, Mohammed; Scott, Sarah

    2018-01-23

    A computer-implemented method for determining an optimized purge gas flow in a semi-conductor inspection metrology or lithography apparatus, comprising receiving a permissible contaminant mole fraction, a contaminant outgassing flow rate associated with a contaminant, a contaminant mass diffusivity, an outgassing surface length, a pressure, a temperature, a channel height, and a molecular weight of a purge gas, calculating a flow factor based on the permissible contaminant mole fraction, the contaminant outgassing flow rate, the channel height, and the outgassing surface length, comparing the flow factor to a predefined maximum flow factor value, calculating a minimum purge gas velocity and a purge gas mass flow rate from the flow factor, the contaminant mass diffusivity, the pressure, the temperature, and the molecular weight of the purge gas, and introducing the purge gas into the semi-conductor inspection metrology or lithography apparatus with the minimum purge gas velocity and the purge gas flow rate.

  4. Heat transfer and flow characteristics on a gas turbine shroud.

    Science.gov (United States)

    Obata, M; Kumada, M; Ijichi, N

    2001-05-01

    The work described in this paper is an experimental investigation of the heat transfer from the main flow to a turbine shroud surface, which may be applicable to ceramic gas turbines. Three kinds of turbine shrouds are considered with a flat surface, a taper surface and a spiral groove surface opposite to the blades in an axial flow turbine of actual turbo-charger. Heat transfer measurements were performed for the experimental conditions of a uniform heat flux or a uniform wall temperature. The effects of the inlet flow angle, rotational speed, and tip clearance on the heat transfer coefficient were clarified under on- and off-design flow conditions. The mean heat transfer coefficient was correlated to the blade Reynolds number and tip clearance, and compared with an experimental correlation and measurements of a flat surface. A comparison was also made for the measurement of static pressure distributions.

  5. Measurements of gas permeability and non-Darcy flow in gas-water-hydrate systems

    Energy Technology Data Exchange (ETDEWEB)

    Ersland, G.; Husebo, J.; Graue, A.; Kvamme, B. [Bergen Univ., Bergen (Norway). Dept. of Physics and Technology; Baldwin, B. [Green Country Petrophysics LLC, Dewey, OK (United States); Stevens, J.; Howard, J. [ConocoPhillips, OK (United States)

    2008-07-01

    Storage of carbon dioxide (CO{sub 2}) in natural gas hydrate reservoirs may offer stable long-term storage of a greenhouse gas while benefiting from methane production, without requiring heat. By exposing hydrate to a thermodynamically preferred hydrate former, CO{sub 2}, the hydrate may be maintained macroscopically in the solid state and retain the stability of the formation. However, there is concern over the flow capacity in such reservoirs. This depends on several factors, notably thermodynamic destabilization of hydrate in small pores due to capillary effects; the presence of liquid channels separating the hydrate from the mineral surfaces; and, the connectivity of gas or liquid filled pores and channels. This paper described a technique for measuring gas permeability in gas-water-hydrate systems. It reported on several experiments that measured gas permeability during stages of hydrate growth in sandstone core plugs. Interactions between minerals and surrounding molecules were also discussed. The formation of methane hydrate in porous media was monitored and quantified with magnetic resonance imaging (MRI). MRI images of hydrate growth within the porous rock were provided along with measurements of gas permeability and non-Darcy flow effects at various hydrate saturations. Gas permeability was measured at steady state flow of methane through the hydrate-bearing core sample. Significant gas permeability was recorded for porous sandstone even when hydrates occupied up to 60 per cent of the pore space. It was concluded that MRI imaging can be used effectively to map and quantify hydrate saturation in sandstone core plugs. 27 refs., 2 tabs., 10 figs.

  6. The positive net radiative greenhouse gas forcing of increasing methane emissions from a thawing boreal forest-wetland landscape.

    Science.gov (United States)

    Helbig, Manuel; Chasmer, Laura E; Kljun, NatasCha; Quinton, William L; Treat, Claire C; Sonnentag, Oliver

    2017-06-01

    At the southern margin of permafrost in North America, climate change causes widespread permafrost thaw. In boreal lowlands, thawing forested permafrost peat plateaus ('forest') lead to expansion of permafrost-free wetlands ('wetland'). Expanding wetland area with saturated and warmer organic soils is expected to increase landscape methane (CH 4 ) emissions. Here, we quantify the thaw-induced increase in CH 4 emissions for a boreal forest-wetland landscape in the southern Taiga Plains, Canada, and evaluate its impact on net radiative forcing relative to potential long-term net carbon dioxide (CO 2 ) exchange. Using nested wetland and landscape eddy covariance net CH 4 flux measurements in combination with flux footprint modeling, we find that landscape CH 4 emissions increase with increasing wetland-to-forest ratio. Landscape CH 4 emissions are most sensitive to this ratio during peak emission periods, when wetland soils are up to 10 °C warmer than forest soils. The cumulative growing season (May-October) wetland CH 4 emission of ~13 g CH 4  m -2 is the dominating contribution to the landscape CH 4 emission of ~7 g CH 4  m -2 . In contrast, forest contributions to landscape CH 4 emissions appear to be negligible. The rapid wetland expansion of 0.26 ± 0.05% yr -1 in this region causes an estimated growing season increase of 0.034 ± 0.007 g CH 4  m -2  yr -1 in landscape CH 4 emissions. A long-term net CO 2 uptake of >200 g CO 2  m -2  yr -1 is required to offset the positive radiative forcing of increasing CH 4 emissions until the end of the 21st century as indicated by an atmospheric CH 4 and CO 2 concentration model. However, long-term apparent carbon accumulation rates in similar boreal forest-wetland landscapes and eddy covariance landscape net CO 2 flux measurements suggest a long-term net CO 2 uptake between 49 and 157 g CO 2  m -2  yr -1 . Thus, thaw-induced CH 4 emission increases likely exert a positive net radiative greenhouse gas

  7. Non-isothermal compositional gas flow during carbon dioxide storage and enhanced gas recovery

    DEFF Research Database (Denmark)

    Singh, Ashok; Böettcher, N.; Wang, W.

    2011-01-01

    In this work we present the conceptual modeling and the numerical scheme for carbon dioxide storage into nearly depleted gas reservoirs for enhanced gas recovery reasons. For this we develop non-isothermal compositional gas flow model. We used a combined monolithic / staggered coupling scheme...... to solve mass balance equation for the gaseous mixture with heat and fractional mass transport equations. Temperature change resulting from fluid expansion and viscous heat dissipation is included in heat transport in addition to advection and conduction. We have used a modified version of the Peng...

  8. Flow characteristics of helium gas going through a 90°elbow for flow measurement

    International Nuclear Information System (INIS)

    Feng Beibei; Wang Shiming; Yang Xingtuan; Jiang Shengyao

    2014-01-01

    Numerical simulation is performed to investigate the pressure distribution of He-gas under high pressure and high temperature for 10MW High Temperature Gas-cooled Reactor (HTGR-10). Experimental measurements of wall pressure through a self-built test system are carried out to validate the credibility of the computational approach. We present a study for complex flow structure of He-gas using the case of an structurally 90°elbow that is reconstructed from the steam generator of HTGR-10. Pressure measurement of inner wall and outer wall is used to compare with the numerical results. Distribution of wall pressure of He-gas flowing through 90° elbow based on the numerical and experimental approaches show good agreement. Wall pressure distribution of eight cross sections of the elbow is given in detail to represent the entire region of elbow. (author)

  9. Estimation of gas wall shear stress in horizontal stratified gas-liquid pipe flow

    International Nuclear Information System (INIS)

    Newton, C.H.; Behnia, M.

    1996-01-01

    Two-phase pipe flows occur in many industrial applications, such as condensers and evaporators, chemical processing equipment, nuclear reactors, and oil pipelines. A variety of basic mechanistic flow models for predicting the pressure gradient and liquid loading characteristics of these types of flows to assist in design calculations has emerged over the past two decades, especially for the stratified and slug flow regimes. These models generally rely on a number of basic assumptions and empirical closure equations. Possibly the most notable of these relates to the evaluation of interfacial shear stresses. However, one of the most important yet least discussed assumptions used in most of these models is that the phase wall shear stresses can be accurately estimated from correlations developed for single-phase pipe flows. The object of this article is to present measurements of gas wall shear up to locations in close proximity to the gas-liquid interface for a variety of interface conditions in developed flow, and to determine the effects of the interface on average gas wall friction factors. In this context the interface may be smooth, rippled or wavy

  10. Simple methods for predicting gas leakage flows through cracks

    International Nuclear Information System (INIS)

    Ewing, D.J.F.

    1989-01-01

    This report presents closed-form approximate analytical formulae with which the flow rate out of a through-wall crack can be estimated. The crack is idealised as a rough, tapering, wedgeshaped channel and the fluid is idealised as an isothermal or polytropically-expanding perfect gas. In practice, uncertainties about the wall friction factor dominate over uncertainties caused by the fluid-dynamics simplifications. The formulae take account of crack taper and for outwardly-diverging cracks they predict flows within 12% of mathematically more accurate one-dimensional numerical models. Upper and lower estimates of wall friction are discussed. (author)

  11. Assessment of cleaning efficiency of the polydisperse gas flow in double-flow dedusting system

    Directory of Open Access Journals (Sweden)

    O.G. Butenko

    2016-05-01

    Full Text Available One of priority problems of nature protection activity at the industrial enterprises is upgrading the gas emissions cleaning of polydispersed dust. To solve the problem of catching of small fraction dust the double-flow dedusting system has been offered. Aim: The aim of the work is to determine the dependency type of the cleaning efficiency of polydisperse gas flow on gas separation factor double-flow dedusting system. Materials and methods: The analysis of influence of gas separation factor in the dividing device of double-flow dedusting system on its efficiency is carried out. By drawing up the mass balance of system on gas and on the mass of dust the general dependence for breakthrough of the main catcher, characterizing overall effectiveness of system, is received. Results: It is shown that value of breakthrough factor of the main catcher depends on dimensionless efficiency factors of the equipment. The received general dependence of breakthrough factor on separation factor allows to define the optimum value of separation factor for any combined dedusting system.

  12. Deviations from the Boltzmann distribution in vibrationally excited gas flows

    International Nuclear Information System (INIS)

    Offenhaeuser, F.; Frohn, A.

    1986-01-01

    A new model for the exchange of vibrational energy in one-dimensional flows of CO 2 -H 2 O-N 2 -O 2 -He gas mixtures is presented. In contrast to previous models, the assumption of local Boltzmann distributions for the vibrational degrees of freedom is not required. This generalization was achieved by the assumption that the molecules are harmonic oscillators with one or more degrees of freedom represented by finite numbers of energy levels. The population densities of these energy levels are coupled by a set of rate equations. It is shown that in some cases of molecular gas flow the Boltzmann distribution for the vibrational degrees of freedom may be disturbed. 12 references

  13. Ultrasonic Tomography Imaging for Liquid-Gas Flow Measurement

    Directory of Open Access Journals (Sweden)

    Muhammad Jaysuman PUSPPANATHAN

    2013-01-01

    Full Text Available This research was carried out to measure two-phase liquid – gas flow regime by using a dual functionality ultrasonic transducer. Comparing to the common separated transmitter–receiver ultrasonic pairs transducer, the dual functionality ultrasonic transceiver is capable to produce the same measurable results hence further improvises and contributes to the hardware design improvement and system accuracy. Due to the disadvantages and the limitations of the separated ultrasonic transmitter–receiver pair, this paper presents a non-invasive ultrasonic tomography system using ultrasonic transceivers as an alternative approach. Implementation of ultrasonic transceivers, electronic measurement circuits, data acquisition system and suitable image reconstruction algorithms, the measurement of a liquid/gas flow was realized.

  14. Flow and Combustion in Advanced Gas Turbine Combustors

    CERN Document Server

    Janicka, Johannes; Schäfer, Michael; Heeger, Christof

    2013-01-01

    With regard to both the environmental sustainability and operating efficiency demands, modern combustion research has to face two main objectives, the optimization of combustion efficiency and the reduction of pollutants. This book reports on the combustion research activities carried out within the Collaborative Research Center (SFB) 568 “Flow and Combustion in Future Gas Turbine Combustion Chambers” funded by the German Research Foundation (DFG). This aimed at designing a completely integrated modeling and numerical simulation of the occurring very complex, coupled and interacting physico-chemical processes, such as turbulent heat and mass transport, single or multi-phase flows phenomena, chemical reactions/combustion and radiation, able to support the development of advanced gas turbine chamber concepts.

  15. Transient heat transfer for forced convection flow of helium gas

    International Nuclear Information System (INIS)

    Liu, Qiusheng; Fukuda, Katsuya; Sasaki, Kenji; Yamamoto, Manabu

    1999-01-01

    Transient heat transfer coefficients for forced convection flow of helium gas over a horizontal cylinder were measured using a forced convection test loop. The platinum heater with a diameter of 1.0 mm was heated by electric current with an exponential increase of Q 0 exp(t/τ). It was clarified that the heat transfer coefficient approaches the steady-state one for the period τ over 1 s, and it becomes higher for the period of τ shorter than 1 s. The transient heat transfer shows less dependent on the gas flowing velocity when the period becomes very shorter. Semi-empirical correlations for steady-state and transient heat transfer were developed based on the experimental data. (author)

  16. Periodical gas flow around a well in porous media

    International Nuclear Information System (INIS)

    Shnaid, I.; Olek, S.

    1996-01-01

    Analytical solutions of the linearized governing equation are presented for periodic gas flow around a well in porous media. Two cases are considered: a fully penetrating well and a partially penetrating well. For the first case, a closed form solution is obtained, whereas for the second case the solution is in the form of eigenfunctions expansions. The results have practical application in compressed air energy storage. (authors)

  17. Gas flow parameter determination by molecular beam method

    International Nuclear Information System (INIS)

    Zarvin, A.E.; Sharafutdinov, R.G.

    1977-01-01

    This paper describes a molecular-beam system intended for studying nonequilibrium processes in supersonic rarefied gas flows. The system represented is a small molecular beam source placed inside the low intensity wind tunnel of the Institute of Thermophysics, Siberian Branch of the USSR Academy of Sciences. The time-of-flight method is used for measuring molecular velocity distribution functions on molecular beam axis. (Auth.)

  18. Gas flows in the circumgalactic medium around simulated high-redshift galaxies

    Science.gov (United States)

    Mitchell, Peter D.; Blaizot, Jérémy; Devriendt, Julien; Kimm, Taysun; Michel-Dansac, Léo; Rosdahl, Joakim; Slyz, Adrianne

    2018-03-01

    We analyse the properties of circumgalactic gas around simulated galaxies in the redshift range z ≥ 3, utilizing a new sample of cosmological zoom simulations. These simulations are intended to be representative of the observed samples of Lyman α (Ly α) emitters recently obtained with the multi unit spectroscopic explorer (MUSE) instrument (halo masses ˜1010-1011 M⊙). We show that supernova feedback has a significant impact on both the inflowing and outflowing circumgalactic medium (CGM) by driving outflows, reducing diffuse inflow rates, and by increasing the neutral fraction of inflowing gas. By temporally stacking simulation outputs, we find that significant net mass exchange occurs between inflowing and outflowing phases: none of the phases are mass-conserving. In particular, we find that the mass in neutral outflowing hydrogen declines exponentially with radius as gas flows outwards from the halo centre. This is likely caused by a combination of both fountain-like cycling processes and gradual photoionization/collisional ionization of outflowing gas. Our simulations do not predict the presence of fast-moving neutral outflows in the CGM. Neutral outflows instead move with modest radial velocities (˜50 km s-1), and the majority of the kinetic energy is associated with tangential rather than radial motion.

  19. APROACHING THE ECONOMIC DIMENSION OF SUSTAINABLE DEVELOPMENT FROM A FINANCIAL PERSPECTIVE: A CASE STUDY REGARDING CASH - FLOW ANALYSIS AND THE RELATIONSIPS BETWEEN CASH - FLOW AND NET INCOME

    Directory of Open Access Journals (Sweden)

    Diana Elena Vasiu

    2014-10-01

    Full Text Available Europe 2020, a strategy for smart, sustainable and inclusive growth stresses the necessity of smart, sustainable and inclusive growth. The objectives of a sustainable economic development include sustaining economic growth, maximizing private profits and expanding markets. Considering this, economic development must based on facts, not on papers. Therefore, considering the economic dimension of sustainable development, it is important to establish if Romanian companies listed and traded on Bucharest Stock Exchange are able to obtain profit while cash is withdrawn. Even if reported in the income statement, net profit is not simultaneously charged due to accrual accounting that makes the balance sheet provide a static picture of the financial position, while the cash flow statement provides a dynamic picture of it. Therefore, the financial performance analysis based on classical indicators of performance must be accompanied by the analysis of treasury, namely of the cash flow, which provides a comprehensive assessment possibility of the financial performance, flexibility and adaptability of the economic entity, in the context of a highly competitive and often unstable environment. A positive net flows is a confirmation of the economic success of the company representing the concrete expression of the net profit and other pecuniary accumulations, interpreted as the real self-financing investment capacity, which would lead to the real asset growth and thus to the increase of the owners' wealth.

  20. Net Greenhouse Gas Emissions at the Eastmain 1 Reservoir, Quebec, Canada

    Science.gov (United States)

    Strachan, I. B.; Tremblay, A.; Bastien, J.; Bonneville, M.; Del Georgio, P.; Demarty, M.; Garneau, M.; Helie, J.; Pelletier, L.; Prairie, Y.; Roulet, N. T.; Teodoru, C. R.

    2010-12-01

    Canada has much potential to increase its already large use of hydroelectricity for energy production. However, hydroelectricity production in many cases requires the creation of reservoirs that inundate terrestrial ecosystems. While it has been reasonably well established that reservoirs emit GHGs, it has not been established what the net difference between the landscape scale exchange of GHGs would be before and after reservoir creation. Further, there is no indication of how that net difference may change over time from when the reservoir was first created to when it reaches a steady-state condition. A team of University and private sector researchers in partnership with Hydro-Québec has been studying net GHG emissions from the Eastmain 1 reservoir located in the boreal forest region of Québec, Canada. Net emissions are defined as those emitted following the creation of a reservoir minus those that would have been emitted or absorbed by the natural systems over a 100-year period in the absence of the reservoir. Sedimentation rates, emissions at the surface of the reservoir and natural water bodies, the degassing emissions downstream of the power house as well as the emissions/absorption of the natural ecosystems (forest, peatlands, lakes, streams and rivers) before and after the impoundment were measured using different techniques (Eddy covariance, floating chambers, automated systems, etc.). This project provides the first measurements of CO2 and CH4 between a new boreal reservoir and the atmosphere as the reservoir is being created, the development of the methodology to obtain these, and the first attempt at approaching the GHGs emissions from northern hydroelectric reservoirs as a land cover change issue. We will therefore provide: an estimate of the change in GHG source the atmosphere would see; an estimate of the net emissions that can be used for intercomparison of GHG contributions with other modes of power production; and a basis on which to develop

  1. Spatial stochasticity and non-continuum effects in gas flows

    Energy Technology Data Exchange (ETDEWEB)

    Dadzie, S. Kokou, E-mail: k.dadzie@glyndwr.ac.uk [Mechanical and Aeronautical Engineering, Glyndwr University, Mold Road, Wrexham LL11 2AW (United Kingdom); Reese, Jason M., E-mail: jason.reese@strath.ac.uk [Department of Mechanical and Aerospace Engineering, University of Strathclyde, Glasgow G1 1XJ (United Kingdom)

    2012-02-06

    We investigate the relationship between spatial stochasticity and non-continuum effects in gas flows. A kinetic model for a dilute gas is developed using strictly a stochastic molecular model reasoning, without primarily referring to either the Liouville or the Boltzmann equations for dilute gases. The kinetic equation, a stochastic version of the well-known deterministic Boltzmann equation for dilute gas, is then associated with a set of macroscopic equations for the case of a monatomic gas. Tests based on a heat conduction configuration and sound wave dispersion show that spatial stochasticity can explain some non-continuum effects seen in gases. -- Highlights: ► We investigate effects of molecular spatial stochasticity in non-continuum regime. ► Present a simplify spatial stochastic kinetic equation. ► Present a spatial stochastic macroscopic flow equations. ► Show effects of the new model on sound wave dispersion prediction. ► Show effects of the new approach in density profiles in a heat conduction.

  2. MANA YANG LEBIH MEMILIKI VALUE-RELEVANT: NET INCOME ATAU CASH FLOWS (Studi Terhadap Siklus Hidup Organisasi

    Directory of Open Access Journals (Sweden)

    Juniarti Juniarti

    2005-01-01

    Full Text Available This research is aimed to examine the relative value-relevant of net income and cash flow measures in different life cycle stages. Corporate life cycle consists of four stages: start up, growth, mature, and decline stage. Firms in different life cycle stages have different characteristics, and therefore in each life cycle stages the usefulness of accounting measures also different. Net incomes are predicted to be more value relevant in mature stages, while cash flows are expected to be more value relevant in stages characterized by start up, growth, and decline stages. The results prove that in the growth stage, the analysis supports the hypothesis that cash flows are more value relevant than net income. However, in the mature stage, the analysis results reject the hypothesis. This research do not analyze for the start up stage and decline stage, because of the limitation of the sample data. Abstract in Bahasa Indonesia: Penelitian ini bertujuan untuk menguji manakah yang lebih memiliki value-relevant pengukuran laba atau arus kas pada masing-masing siklus hidup perusahaan. Siklus hidup perusahaan umumnya terbagi dalam tahap start-up, growth, mature dan decline. Karakteristik perusahaan berbeda untuk setiap tahap siklus hidup tersebut, karena itu kegunaan pengukuran akuntansi juga akan berbeda. Laba diperkirakan lebih memiliki value-relevant pada tahap mature, sementara arus kas diekspektasikan lebih memiliki value-relevant ketika perusahaan berada pada tahap start-up, growth dan decline. Penelitian ini membuktikan bahwa pada tahap growth, hasil pengujian yang dilakukan mendukung hipotesis bahwa cash flow lebih memiliki value relevant dibanding laba. Tetapi, untuk tahap mature, hipotesis yang diajukan tidak berhasil dibuktikan. Penelitian ini tidak dapat melakukan pengujian untuk tahap start-up dan decline, dikarenakan data sampel untuk kedua tahap tersebut tidak mencukupi untuk dilakukan pengujian. Kata kunci: siklus hidup organisasi, value

  3. A global meta-analysis on the impact of management practices on net global warming potential and greenhouse gas intensity from cropland soils

    Science.gov (United States)

    Agricultural practices contribute significant amount of greenhouse gas (GHG) emissions, but little is known about their effects on net global warming potential (GWP) and greenhouse gas intensity (GHGI) that account for all sources and sinks of carbon dioxide emissions per unit area or crop yield. Se...

  4. Simulation and Modeling of Flow in a Gas Compressor

    Directory of Open Access Journals (Sweden)

    Anna Avramenko

    2015-01-01

    Full Text Available The presented research demonstrates the results of a series of numerical simulations of gas flow through a single-stage centrifugal compressor with a vaneless diffuser. Numerical results were validated with experiments consisting of eight regimes with different mass flow rates. The steady-state and unsteady simulations were done in ANSYS FLUENT 13.0 and NUMECA FINE/TURBO 8.9.1 for one-period geometry due to periodicity of the problem. First-order discretization is insufficient due to strong dissipation effects. Results obtained with second-order discretization agree with the experiments for the steady-state case in the region of high mass flow rates. In the area of low mass flow rates, nonstationary effects significantly influence the flow leading stationary model to poor prediction. Therefore, the unsteady simulations were performed in the region of low mass flow rates. Results of calculation were compared with experimental data. The numerical simulation method in this paper can be used to predict compressor performance.

  5. Compressible gas flow through idealized cracks of large aspect ratio

    International Nuclear Information System (INIS)

    Chivers, T.C.; Skinner, J.; Williams, M.E.

    1975-07-01

    Gas flow through large aspect ratio idealized cracks is considered, where isothermal conditions with choking at exit are assumed in the theoretical analysis. For smooth wall cracks, comparisons are made between experimentally determined flowrates and those predicted, and good agreement is shown. This is followed by consideration of flow through a notional crack to examine the influence of width and surface roughness. By considering flow as simply proportional to Wsup(n), the treatment shows 'n' to reduce with W increasing, but surface roughness increases 'n' over the value appropriate to smooth conditions. From these observations it is concluded that further work is required to determine:- (i) real crack geometry and its influence on any leak-before-break philosophy, and (ii) the influence of real surface roughness on flowrate. (author)

  6. Rarefaction effects in gas flows over curved surfaces

    Science.gov (United States)

    Dongari, Nishanth; White, Craig; Scanlon, Thomas J.; Zhang, Yonghao; Reese, Jason M.

    2012-11-01

    The fundamental test case of gas flow between two concentric rotating cylinders is considered in order to investigate rarefaction effects associated with the Knudsen layers over curved surfaces. We carry out direct simulation Monte Carlo simulations covering a wide range of Knudsen numbers and accommodation coefficients, and for various outer-to-inner cylinder radius ratios. Numerical data is compared with classical slip flow theory and a new power-law (PL) wall scaling model. The PL model incorporates Knudsen layer effects in near-wall regions by taking into account the boundary limiting effects on the molecular free paths. The limitations of both theoretical models are explored with respect to rarefaction and curvature effects. Torque and velocity profile comparisons also convey that mere prediction of integral flow parameters does not guarantee the accuracy of a theoretical model, and that it is important to ensure that prediction of the local flowfield is in agreement with simulation data.

  7. Modeling of information flows in natural gas storage facility

    Science.gov (United States)

    Ranjbari, Leyla; Bahar, Arifah; Aziz, Zainal Abdul

    2013-09-01

    The paper considers the natural-gas storage valuation based on the information-based pricing framework of Brody-Hughston-Macrina (BHM). As opposed to many studies which the associated filtration is considered pre-specified, this work tries to construct the filtration in terms of the information provided to the market. The value of the storage is given by the sum of the discounted expectations of the cash flows under risk-neutral measure, conditional to the constructed filtration with the Brownian bridge noise term. In order to model the flow of information about the cash flows, we assume the existence of a fixed pricing kernel with liquid, homogenous and incomplete market without arbitrage.

  8. Exchange between the stagnant and flowing zone in gas-flowing solids-fixed bed contactors

    Directory of Open Access Journals (Sweden)

    ALEKSANDAR P. DUDUKOVIC

    2005-02-01

    Full Text Available In countercurrent gas – flowing solids – fixed bed contactors, a fraction of the flowing solids is in motion (dynamic holdup, while the other fraction is resting on the fixed bed elements. In this study it was experimentally proved that the stagnant zone should not be considered as a dead part of the column, but that there is a dynamic exchange between these two portions of flowing solids particles. Combining a mathematical model with tracer experiments, the rate of exchange was determined and it was shown that only a small part (ca. 20 % of the stagnant region should be considered as a dead one.

  9. 40 CFR 92.117 - Gas meter or flow instrumentation calibration, particulate measurement.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Gas meter or flow instrumentation... ENGINES Test Procedures § 92.117 Gas meter or flow instrumentation calibration, particulate measurement. (a) Sampling for particulate emissions requires the use of gas meters or flow instrumentation to...

  10. The Relation between Gas Flow and Combustibility using Actual Engine (Basic Experiment of Gas Flow and Combustibility under Low Load Condition)

    OpenAIRE

    田坂, 英紀; 泉, 立哉; 木村, 正寿

    2003-01-01

    Abstract ###Consideration of the global environment problems by exhaust gas is becoming important in recent years. ###Especially about internal combustion engine, social demand has been increasing about low pollution, high ###efficiency and so on. Controlling gas flow in cylinder becomes the key getting good combustion state in ###various driving states. ###The purpose of the research is analysis about the relation between gas flow and combustibility in the cylinder. ###So we measured gas flo...

  11. Mathematical modeling of non-stationary gas flow in gas pipeline

    Science.gov (United States)

    Fetisov, V. G.; Nikolaev, A. K.; Lykov, Y. V.; Duchnevich, L. N.

    2018-03-01

    An analysis of the operation of the gas transportation system shows that for a considerable part of time pipelines operate in an unsettled regime of gas movement. Its pressure and flow rate vary along the length of pipeline and over time as a result of uneven consumption and selection, switching on and off compressor units, shutting off stop valves, emergence of emergency leaks. The operational management of such regimes is associated with difficulty of reconciling the operating modes of individual sections of gas pipeline with each other, as well as with compressor stations. Determining the grounds that cause change in the operating mode of the pipeline system and revealing patterns of these changes determine the choice of its parameters. Therefore, knowledge of the laws of changing the main technological parameters of gas pumping through pipelines in conditions of non-stationary motion is of great importance for practice.

  12. Estimation of Flow Channel Parameters for Flowing Gas Mixed with Air in Atmospheric-pressure Plasma Jets

    Science.gov (United States)

    Yambe, Kiyoyuki; Saito, Hidetoshi

    2017-12-01

    When the working gas of an atmospheric-pressure non-equilibrium (cold) plasma flows into free space, the diameter of the resulting flow channel changes continuously. The shape of the channel is observed through the light emitted by the working gas of the atmospheric-pressure plasma. When the plasma jet forms a conical shape, the diameter of the cylindrical shape, which approximates the conical shape, defines the diameter of the flow channel. When the working gas flows into the atmosphere from the inside of a quartz tube, the gas mixes with air. The molar ratio of the working gas and air is estimated from the corresponding volume ratio through the relationship between the diameter of the cylindrical plasma channel and the inner diameter of the quartz tube. The Reynolds number is calculated from the kinematic viscosity of the mixed gas and the molar ratio. The gas flow rates for the upper limit of laminar flow and the lower limit of turbulent flow are determined by the corresponding Reynolds numbers estimated from the molar ratio. It is confirmed that the plasma jet length and the internal plasma length associated with strong light emission increase with the increasing gas flow rate until the rate for the upper limit of laminar flow and the lower limit of turbulent flow, respectively. Thus, we are able to explain the increasing trend in the plasma lengths with the diameter of the flow channel and the molar ratio by using the cylindrical approximation.

  13. Applied multiphase flow in pipes and flow assurance oil and gas production

    CERN Document Server

    Al-Safran, Eissa M

    2017-01-01

    Applied Multiphase Flow in Pipes and Flow Assurance - Oil and Gas Production delivers the most recent advancements in multiphase flow technology while remaining easy to read and appropriate for undergraduate and graduate petroleum engineering students. Responding to the need for a more up-to-the-minute resource, this highly anticipated new book represents applications on the fundamentals with new material on heat transfer in production systems, flow assurance, transient multiphase flow in pipes and the TUFFP unified model. The complex computation procedure of mechanistic models is simplified through solution flowcharts and several example problems. Containing over 50 solved example problems and 140 homework problems, this new book will equip engineers with the skills necessary to use the latest steady-state simulators available.

  14. Venturi Wet Gas Flow Modeling Based on Homogeneous and Separated Flow Theory

    Directory of Open Access Journals (Sweden)

    Xu Ying

    2008-10-01

    Full Text Available When Venturi meters are used in wet gas, the measured differential pressure is higher than it would be in gas phases flowing alone. This phenomenon is called over-reading. Eight famous over-reading correlations have been studied by many researchers under low- and high-pressure conditions, the conclusion is separated flow model and homogeneous flow model performing well both under high and low pressures. In this study, a new metering method is presented based on homogeneous and separated flow theory; the acceleration pressure drop and the friction pressure drop of Venturi under two-phase flow conditions are considered in new correlation, and its validity is verified through experiment. For low pressure, a new test program has been implemented in Tianjin University’s low-pressure wet gas loop. For high pressure, the National Engineering Laboratory offered their reports on the web, so the coefficients of the new proposed correlation are fitted with all independent data both under high and low pressures. Finally, the applicability and errors of new correlation are analyzed.

  15. PolNet: A Tool to Quantify Network-Level Cell Polarity and Blood Flow in Vascular Remodeling.

    Science.gov (United States)

    Bernabeu, Miguel O; Jones, Martin L; Nash, Rupert W; Pezzarossa, Anna; Coveney, Peter V; Gerhardt, Holger; Franco, Claudio A

    2018-05-08

    In this article, we present PolNet, an open-source software tool for the study of blood flow and cell-level biological activity during vessel morphogenesis. We provide an image acquisition, segmentation, and analysis protocol to quantify endothelial cell polarity in entire in vivo vascular networks. In combination, we use computational fluid dynamics to characterize the hemodynamics of the vascular networks under study. The tool enables, to our knowledge for the first time, a network-level analysis of polarity and flow for individual endothelial cells. To date, PolNet has proven invaluable for the study of endothelial cell polarization and migration during vascular patterning, as demonstrated by two recent publications. Additionally, the tool can be easily extended to correlate blood flow with other experimental observations at the cellular/molecular level. We release the source code of our tool under the Lesser General Public License. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  16. Gas and particle motions in a rapidly decompressed flow

    Science.gov (United States)

    Johnson, Blair; Zunino, Heather; Adrian, Ronald; Clarke, Amanda

    2017-11-01

    To understand the behavior of a rapidly decompressed particle bed in response to a shock, an experimental study is performed in a cylindrical (D = 4.1 cm) glass vertical shock tube of a densely packed (ρ = 61%) particle bed. The bed is comprised of spherical glass particles, ranging from D50 = 44-297 μm between experiments. High-speed pressure sensors are incorporated to capture shock speeds and strengths. High-speed video and particle image velocimetry (PIV) measurements are collected to examine vertical and radial velocities of both the particles and gas to elucidate features of the shock wave and resultant expansion wave in the lateral center of the tube, away from boundaries. In addition to optically analyzing the front velocity of the rising particle bed, interaction between the particle and gas phases are investigated as the flow accelerates and the particle front becomes more dilute. Particle and gas interactions are also considered in exploring mechanisms through which turbulence develops in the flow. This work is supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science and Academic Alliance Program, under Contract No. DE-NA0002378.

  17. Net farm income and land use under a U.S. greenhouse gas cap and trade

    Science.gov (United States)

    Justin S. Baker; Bruce A. McCarl; Brian C. Murray; Steven K. Rose; Ralph J. Alig; Darius Adams; Greg Latta; Robert Beach; Adam. Daigneault

    2010-01-01

    During recent years, the U.S. agricultural sector has experienced high prices for energy related inputs and commodities, and a rapidly developing bioenergy market. Greenhouse gas (GHG) emissions mitigation would further alter agricultural markets and increase land competition in forestry and agriculture by shifting input costs, creating an agricultural GHG abatement...

  18. Gas flow counter conversion electron Moessbauer spectroscopy (GFC-CEMS)

    International Nuclear Information System (INIS)

    Williamson, A.; Vijay, Y.K.; Jain, I.P.

    1999-01-01

    Conversion Electron Moessbauer Spectroscopy (CEMS) is well established technique to study surface properties of materials. However non availability of commercial experimental set up and complexity of operational parameters have been restricting the working experimental groups with in the country and abroad. In this paper we have presented the development work for the design of Gas Flow Counter (GFC), e.g. convenient sample mount, grounding, steady flow rate adjustment and minimum He-losses so that the detector operation and installation becomes convenient and dependable. The basic design is modified e.g. large volume to maintain steady gas flow, sample mount close to central wire and O-ring fitted flange. The CEMS spectra are recorded using conventional Moessbauer drive and 57 Co source. The calibrated spectrum shows a detection efficiency of about 20% for natural iron and steel foil. The CEMS spectrum for FeTi bulk and transmission Moessbauer Spectroscopy (TMS) spectrum of FeTi thin film deposited by vacuum evaporation on thin glass substrate were recorded to test the performance of GFC-CEMS. (author)

  19. Gas-liquid two-phase flows in double inlet cyclones for natural gas separation

    DEFF Research Database (Denmark)

    Yang, Yan; Wang, Shuli; Wen, Chuang

    2017-01-01

    The gas-liquid two-phase flow within a double inlet cyclone for natural gasseparation was numerically simulated using the discrete phase model. The numericalapproach was validated with the experimental data, and the comparison resultsagreed well with each other. The simulation results showed...... that the strong swirlingflow produced a high centrifugal force to remove the particles from the gas mixture.The larger particles moved downward on the internal surface and were removeddue to the outer vortex near the wall. Most of the tiny particles went into the innervortex zones and escaped from the up...

  20. Digital image processing based mass flow rate measurement of gas/solid two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Song Ding; Peng Lihui; Lu Geng; Yang Shiyuan [Tsinghua National Laboratory for Information Science and Technology, Department of Automation, Tsinghua University, Beijing, 100084 (China); Yan Yong, E-mail: lihuipeng@tsinghua.edu.c [University of Kent, Canterbury, Kent CT2 7NT (United Kingdom)

    2009-02-01

    With the rapid growth of the process industry, pneumatic conveying as a tool for the transportation of a wide variety of pulverized and granular materials has become widespread. In order to improve plant control and operational efficiency, it is essential to know the parameters of the particle flow. This paper presents a digital imaging based method which is capable of measuring multiple flow parameters, including volumetric concentration, velocity and mass flow rate of particles in the gas/solid two phase flow. The measurement system consists of a solid state laser for illumination, a low-cost CCD camera for particle image acquisition and a microcomputer with bespoke software for particle image processing. The measurements of particle velocity and volumetric concentration share the same sensing hardware but use different exposure time and different image processing methods. By controlling the exposure time of the camera a clear image and a motion blurred image are obtained respectively. The clear image is thresholded by OTSU method to identify the particles from the dark background so that the volumetric concentration is determined by calculating the ratio between the particle area and the total area. Particle velocity is derived from the motion blur length, which is estimated from the motion blurred images by using the travelling wave equation method. The mass flow rate of particles is calculated by combining the particle velocity and volumetric concentration. Simulation and experiment results indicate that the proposed method is promising for the measurement of multiple parameters of gas/solid two-phase flow.

  1. Digital image processing based mass flow rate measurement of gas/solid two-phase flow

    International Nuclear Information System (INIS)

    Song Ding; Peng Lihui; Lu Geng; Yang Shiyuan; Yan Yong

    2009-01-01

    With the rapid growth of the process industry, pneumatic conveying as a tool for the transportation of a wide variety of pulverized and granular materials has become widespread. In order to improve plant control and operational efficiency, it is essential to know the parameters of the particle flow. This paper presents a digital imaging based method which is capable of measuring multiple flow parameters, including volumetric concentration, velocity and mass flow rate of particles in the gas/solid two phase flow. The measurement system consists of a solid state laser for illumination, a low-cost CCD camera for particle image acquisition and a microcomputer with bespoke software for particle image processing. The measurements of particle velocity and volumetric concentration share the same sensing hardware but use different exposure time and different image processing methods. By controlling the exposure time of the camera a clear image and a motion blurred image are obtained respectively. The clear image is thresholded by OTSU method to identify the particles from the dark background so that the volumetric concentration is determined by calculating the ratio between the particle area and the total area. Particle velocity is derived from the motion blur length, which is estimated from the motion blurred images by using the travelling wave equation method. The mass flow rate of particles is calculated by combining the particle velocity and volumetric concentration. Simulation and experiment results indicate that the proposed method is promising for the measurement of multiple parameters of gas/solid two-phase flow.

  2. The flows structure in unsteady gas flow in pipes with different cross-sections

    Science.gov (United States)

    Plotnikov, Leonid; Nevolin, Alexandr; Nikolaev, Dmitrij

    2017-10-01

    The results of numerical simulation and experimental study of the structure of unsteady flows in pipes with different cross sections are presented in the article. It is shown that the unsteady gas flow in a circular pipe is axisymmetric without secondary currents. Steady vortex structures (secondary flows) are observed in pipes with cross sections in the form of a square and an equilateral triangle. It was found that these secondary flows have a significant impact on gas flows in pipes of complex configuration. On the basis of experimental researches it is established that the strong oscillatory phenomena exist in the inlet pipe of the piston engine arising after the closing of the intake valve. The placement of the profiled plots (with a cross section of a square or an equilateral triangle) in the intake pipe leads to the damping of the oscillatory phenomena and a more rapid stabilization of pulsating flow. This is due to the stabilizing effect of the vortex structures formed in the corners of this configuration.

  3. The flows structure in unsteady gas flow in pipes with different cross-sections

    Directory of Open Access Journals (Sweden)

    Plotnikov Leonid

    2017-01-01

    Full Text Available The results of numerical simulation and experimental study of the structure of unsteady flows in pipes with different cross sections are presented in the article. It is shown that the unsteady gas flow in a circular pipe is axisymmetric without secondary currents. Steady vortex structures (secondary flows are observed in pipes with cross sections in the form of a square and an equilateral triangle. It was found that these secondary flows have a significant impact on gas flows in pipes of complex configuration. On the basis of experimental researches it is established that the strong oscillatory phenomena exist in the inlet pipe of the piston engine arising after the closing of the intake valve. The placement of the profiled plots (with a cross section of a square or an equilateral triangle in the intake pipe leads to the damping of the oscillatory phenomena and a more rapid stabilization of pulsating flow. This is due to the stabilizing effect of the vortex structures formed in the corners of this configuration.

  4. Real-time DDoS attack detection for Cisco IOS using NetFlow

    NARCIS (Netherlands)

    van der Steeg, Daniël; Hofstede, R.J.; Sperotto, Anna; Pras, Aiko

    Flow-based DDoS attack detection is typically performed by analysis applications that are installed on or close to a flow collector. Although this approach allows for easy deployment, it makes detection far from real-time and susceptible to DDoS attacks for the following reasons. First, the fact

  5. A versatile gas-flow proportional counter for Moessbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bibicu, I., E-mail: bibicu@infim.ro [National Institute for Materials Physics (Romania); Nicolescu, G. [IFIN-HH, National Institute of Physics and Nuclear Engineering (Romania); Cretu, C. [Transylvania University, Physics Department (Romania)

    2009-07-15

    This article presents a versatile gas-flow proportional counter for surface and transmission Moessbauer spectroscopy, suitable for studies with {sup 57}Fe, {sup 119}Sn and {sup 151}Eu isotopes. The main advantages obtained by new design are: (1) the height of the detection volume can be changed in large limits from 0 to 38 mm, (2) the detection volume can be choose symmetrical or not in respect with anode plan, (3) the anode replacement is easily (4) and different anode configuration can be used. The characteristics of the detector, operating at room temperature, are reported.

  6. Review of coaxial flow gas core nuclear rocket fluid mechanics

    International Nuclear Information System (INIS)

    Weinstein, H.

    1976-01-01

    In a prematurely aborted attempt to demonstrate the feasibility of using a gas core nuclear reactor as a rocket engine, NASA initiated a number of studies on the relevant fluid mechanics problems. These studies were carried out at NASA laboratories, universities and industrial research laboratories. Because of the relatively sudden termination of most of this work, a unified overview was never presented which demonstrated the accomplishments of the program and pointed out the areas where additional work was required for a full understanding of the cavity flow. This review attempts to fulfill a part of this need in two important areas

  7. Local studies in horizontal gas-liquid slug flow

    International Nuclear Information System (INIS)

    Sharma, S.; Lewis, S.; Kojasoy, G.

    1998-01-01

    The local axial velocity profile development in a horizontal air-water slug flow-pattern was experimentally investigated by simultaneously using two hot-film anemometers. One of the probes was exclusively used as phase identifier while the other probe was traversed for local velocity measurements. It was shown that the velocity rapidly develops into asymmetric but nearly fully-developed profiles within the liquid slugs whereas the velocity never develops into quasi-fully-developed profiles within the liquid layer underneath passing gas slugs. Transient nature of velocity at a given location was demonstrated. (author)

  8. Ozone formation in a transverse-flow gas discharge

    International Nuclear Information System (INIS)

    Baranov, G.A.; Zinchenko, A.K.; Lednev, M.G.

    1994-01-01

    The measurements of the ozone concentration in flows of air and nitrogen-oxygen mixtures under transverse dc discharge are performed using an absorption spectroscopy technique. The mechanism of ozone formation in the discharge is discussed. A simple equation is suggested for the estimation of ozone concentration in the gas mixtures. The influence of water vapor on the kinetics of formation and decay of O 3 molecules is considered. The numerical estimates of the ozone concentration are made using the suggested model of plasma-chemical reactions

  9. Two-component HLMC-gas flow instability and inhomogeneity phenomena in open-pool reactor

    International Nuclear Information System (INIS)

    Sergey I Shcherbakov

    2005-01-01

    Full text of publication follows: Consideration is being given to two-component gas-liquid flows with inhomogeneous gas content. The inhomogeneity of gas content over flow space can be caused by local mixing of gas and liquid, gas injection, gas-containing liquid jet penetration into the bulk of liquid without gas. The paper presents the computational results obtained using the direct non-stationary calculation with the TURBO-FLOW computer code. The results refer to flows near the liquid level, flows in downcomer gaps, collectors, elements with varying geometry (jet outlet into space, flow turn) for the pool-type reactors and experimental models. The following processes have been shown and discussed: formation of new liquid levels, entrainment of gas from the level, change in density composition of gas, flow stratification, effect of gas emergence rate and density convection on flow pattern. At gas phase transfer by liquid, two phenomena governing this transfer proceed: gas slip in liquid and density convection of non-uniformly aerated liquid. In horizontal flows, a vertical stratification of gas content always occurs. If the flow changes its direction to an upward one (collector at core inlet), the gas content maximum would be observed in channels nearest to the inlet. At the liquid level, the processes of gas separation from liquid and gas entrainment take place. The separation is a self-sustained process due to circulations arising near the level. The rate of gas entrainment is proportional to the rate of overflow and inversely proportional to the height of liquid level. At the downcomer region in case of its expansion, there occurs the instability of flow resulting in formation of liquid level and falling jet. The level is lower the more the gas content at inlet. The accumulation of gas occurs at sharp turns, encumbered regions (tube bundle), at all regions with upper (ceiling) constraints of flow. The flow instability being often observed in gas-liquid flows

  10. Surface roughness effects on onset of nucleate boiling and net vapor generation point in subcooled flow boiling

    International Nuclear Information System (INIS)

    Ohtake, Hiroyasu; Wada, Noriyoshi; Koizumi, Yasuo

    2003-01-01

    The ability to predict void formation and void fraction in subcooled flow boiling is of importance to the nuclear reactor technology because the presence of voids affects the steady state and transient response of a reactor. The onset of nucleate boiling and the point of net vapor generation on subcooled flow boiling, focusing on surface roughness, liquid subcooling and liquid velocity were investigated experimentally and analytically. Experiments were conducted using a copper thin-film and subcooled water in a range of the liquid velocity from 0.27 to 4.6 m/s at 0.10MPa; the liquid subcoolings were 20, 30 and 40K, respectively. The surface roughness on the test heater was observed by SEM. Experimental results showed that temperatures at the onset nucleate boiling increased with increasing the liquid subcoolings or the liquid velocities. The trend of increase in the temperature at the ONB was in good agreement with the present analytical result based on the stability theory of preexisting nuclei. The measured results for the net vapor generation point agreed well with the results of correlation by Saha and Zuber in the range of the present experiments. The temperature at the ONB decreased with an increasing size of surface roughness, while the NVG-point was independent on the surface roughness. The dependence on the ONB temperature of the roughness size was also represented well by the present analytical model

  11. Flow and Heat Transfer Characteristics of Turbulent Gas Flow in Microtube with Constant Heat Flux

    International Nuclear Information System (INIS)

    Hong, Chungpyo; Matsushita, Shinichi; Ueno, Ichiro; Asako, Yutaka

    2012-01-01

    Local friction factors for turbulent gas flows in circular microtubes with constant wall heat flux were obtained numerically. The numerical methodology is based on arbitrary-Lagrangian-Eulerian method to solve two-dimensional compressible momentum and energy equations. The Lam-Bremhorst's Low-Reynolds number turbulence model was employed to calculate eddy viscosity coefficient and turbulence energy. The simulations were performed for a wide flow range of Reynolds numbers and Mach numbers with different constant wall heat fluxes. The stagnation pressure was chosen in such a way that the outlet Mach number ranged from 0.07 to 1.0. Both Darcy friction factor and Fanning friction factor were locally obtained. The result shows that the obtained both friction factors were evaluated as a function of Reynolds number on the Moody chart. The values of Darcy friction factor differ from Blasius correlation due to the compressibility effects but the values of Fanning friction factor almost coincide with Blasius correlation. The wall heat flux varied from 100 to 10000 W/m 2 . The wall and bulk temperatures with positive heat flux are compared with those of incompressible flow. The result shows that the Nusselt number of turbulent gas flow is different from that of incompressible flow.

  12. Characterising gas behaviour during gas-liquid co-current up-flow in packed beds using magnetic resonance imaging

    OpenAIRE

    Collins, James HP; Sederman, Andrew John; Gladden, Lynn Faith; Afeworki, Mobae; Kushnerick, J Douglas; Thomann, Hans

    2016-01-01

    Magnetic resonance (MR) imaging techniques have been used to study gas phase dynamics during co-current up-flow in a column of inner diameter 43 mm, packed with spherical non-porous elements of diameters of 1.8, 3 and 5 mm. MR measurements of gas hold-up, bubble-size distribution, and bubble-rise velocities were made as a function of flow rate and packing size. Gas and liquid flow rates were studied in the range of 20–250 cm3 s−1 and 0–200 cm3 min−1, respectively. The gas hold-up within the b...

  13. Tritium inventory measurements by 'in-bed' gas flowing calorimetry

    International Nuclear Information System (INIS)

    Hayashi, T.; Suzuki, T.; Yamada, M.; Okuno, K.

    1996-01-01

    In order to establish the 'in-bed' tritium accounting technology for the ITER scale tritium storage system, a gas flowing calorimetry has been studied using a scaled ZrCo bed (25 g tritium capacity). The basic calorimetric characteristics, steady state temperature raise of He gas stream flowing through a secondary coil line fixed in the ZrCo tritide, was measured and correlated with the stored tritium inventory. The results shows that about 4 degrees raise of He stream temperature can be detected for each gram of tritium storage. The sensitivity of this calorimetry is about 0.05 g of tritium, calculated by 0.2 degrees of temperature sensor error. The accuracy is better than 0.25 g of tritium on 25 g storage, evaluated by 2 times of standard deviation from the repeat measurements. This accuracy of < 1% on full storage capacity is satisfied the target accountability to measure ± 1 gram of tritium on 100 g storage for ITER. 13 refs., 7 figs

  14. Integral Transport Analysis Results for Ions Flowing Through Neutral Gas

    Science.gov (United States)

    Emmert, Gilbert; Santarius, John

    2017-10-01

    Results of a computational model for the flow of energetic ions and neutrals through a background neutral gas will be presented. The method models reactions as creating a new source of ions or neutrals if the energy or charge state of the resulting particle is changed. For a given source boundary condition, the creation and annihilation of the various species is formulated as a 1-D Volterra integral equation that can quickly be solved numerically by finite differences. The present work focuses on multiple-pass, 1-D ion flow through neutral gas and a nearly transparent, concentric anode and cathode pair in spherical, cylindrical, or linear geometry. This has been implemented as a computer code for atomic (3He, 3He +, 3He + +) and molecular (D, D2, D-, D +, D2 +, D3 +) ion and neutral species, and applied to modeling inertial-electrostatic connement (IEC) devices. The code yields detailed energy spectra of the various ions and energetic neutral species. Calculations for several University of Wisconsin IEC and ion implantation devices will be presented. Research supported by US Dept. of Homeland Security Grant 2015-DN-077-ARI095, Dept. of Energy Grant DE-FG02-04ER54745, and the Grainger Foundation.

  15. Direct numerical simulation of stratified gas-liquid flow

    International Nuclear Information System (INIS)

    Lombardi, P.; De Angelis, V.; Banerjee, S.

    1996-01-01

    Interactions through an interface between two turbulent flows play an important role in many environmental and industrial problems, e.g. in determining the coupling fluxes of heat mass and momentum, between the ocean and atmosphere, and in the design of gas-liquid contractors for the chemical industry, as well as in determining interactions between phases in nuclear transients that are accompanied by system voiding e.g. LOCAs. Here, the Direct Numerical Simulation (DNS) of the interaction of two turbulent fluids through a flat interface has been simulated. The flow and the temperature fields are computed using a pseudospectral method. This study shows that shear stress at the interface correlates well with the heat flux. Extensive analysis of the near interface turbulence structure has been performed using quadrant analysis. From this it is clear that gas-side sweeps dominate over the high shear stress regions. This suggests that simple parameterizations based on sweep frequency may be adequate for predictions of scalar transport rates

  16. Impurity in a granular gas under nonlinear Couette flow

    International Nuclear Information System (INIS)

    Vega Reyes, Francisco; Garzó, Vicente; Santos, Andrés

    2008-01-01

    We study in this work the transport properties of an impurity immersed in a granular gas under stationary nonlinear Couette flow. The starting point is a kinetic model for low-density granular mixtures recently proposed by the authors (Vega Reyes et al 2007 Phys. Rev. E 75 061306). Two routes have been considered. First, a hydrodynamic or normal solution is found by exploiting a formal mapping between the kinetic equations for the gas particles and for the impurity. We show that the transport properties of the impurity are characterized by the ratio between the temperatures of the impurity and gas particles and by five generalized transport coefficients: three related to the momentum flux (a nonlinear shear viscosity and two normal stress differences) and two related to the heat flux (a nonlinear thermal conductivity and a cross-coefficient measuring a component of the heat flux orthogonal to the thermal gradient). Second, by means of a Monte Carlo simulation method we numerically solve the kinetic equations and show that our hydrodynamic solution is valid in the bulk of the fluid when realistic boundary conditions are used. Furthermore, the hydrodynamic solution applies to arbitrarily (inside the continuum regime) large values of the shear rate, of the inelasticity, and of the rest of the parameters of the system. Preliminary simulation results of the true Boltzmann description show the reliability of the nonlinear hydrodynamic solution of the kinetic model. This shows again the validity of a hydrodynamic description for granular flows, even under extreme conditions, beyond the Navier–Stokes domain

  17. Controlling hydrophilicity of polymer film by altering gas flow rate in atmospheric-pressure homogeneous plasma

    International Nuclear Information System (INIS)

    Kang, Woo Seok; Hur, Min; Lee, Jae-Ok; Song, Young-Hoon

    2014-01-01

    Graphical abstract: - Highlights: • Controlling hydrophilicity of polymer film by varying gas flow rate is proposed in atmospheric-pressure homogeneous plasma treatment. • Without employing additional reactive gas, requiring more plasma power and longer treatment time, hydrophilicity of polyimide films was improved after the low-gas-flow plasma treatment. • The gas flow rate affects the hydrophilic properties of polymer surface by changing the discharge atmosphere in the particular geometry of the reactor developed. • Low-gas-flow induced wettability control suggests effective and economical plasma treatment. - Abstract: This paper reports on controlling the hydrophilicity of polyimide films using atmospheric-pressure homogeneous plasmas by changing only the gas flow rate. The gas flow changed the discharge atmosphere by mixing the feed gas with ambient air because of the particular geometry of the reactor developed for the study, and a low gas flow rate was found to be favorable because it generated abundant nitrogen or oxygen species that served as sources of hydrophilic functional groups over the polymer surface. After low-gas-flow plasma treatment, the polymer surface exhibited hydrophilic characteristics with increased surface roughness and enhanced chemical properties owing to the surface addition of functional groups. Without adding any reactive gases or requiring high plasma power and longer treatment time, the developed reactor with low-gas-flow operation offered effective and economical wettability control of polyimide films

  18. Use of exhaust gas as sweep flow to enhance air separation membrane performance

    Science.gov (United States)

    Dutart, Charles H.; Choi, Cathy Y.

    2003-01-01

    An intake air separation system for an internal combustion engine is provided with purge gas or sweep flow on the permeate side of separation membranes in the air separation device. Exhaust gas from the engine is used as a purge gas flow, to increase oxygen flux in the separation device without increasing the nitrogen flux.

  19. Void fraction fluctuations in two-phase gas-liquid flow

    International Nuclear Information System (INIS)

    Ulbrich, R.

    1987-01-01

    Designs of the apparatus in which two-phase gas-liquid flow occurs are usually based on the mean value of parameters such as pressure drop and void fraction. The flow of two-phase mixtures generally presents a very complicated flow structure, both in terms of the unsteady formation on the interfacial area and in terms of the fluctuations of the velocity, pressure and other variables within the flow. When the gas void fraction is near 0 or 1 / bubble or dispersed flow regimes / then oscillations of void fraction are very small. The intermittent flow such as plug and slug/ froth is characterized by alternately flow portions of liquid and gas. It influences the change of void fractions in time. The results of experimental research of gas void fraction fluctuations in two-phase adiabatic gas-liquid flow in a vertical pipe are presented

  20. Investigation of the Flow Rate Effect Upstream of the Constant-Geometry Throttle on the Gas Mass Flow

    Directory of Open Access Journals (Sweden)

    Yu. M. Timofeev

    2016-01-01

    Full Text Available The turbulent-flow throttles are used in pneumatic systems and gas-supply ones to restrict or measure gas mass flow. It is customary to install the throttles in joints of pipelines (in teejoints and cross tees or in joints of pipelines with pneumatic automation devices Presently, in designing the pneumatic systems and gas-supply ones a gas mass flow through a throttle is calculated by a known equation derived from the Saint-Venant-Vantсel formula for the adiabatic flow of ideal gas through a nozzle from an unrestrictedly high capacity tank. Neglect of gas velocity at the throttle inlet is one of the assumptions taken in the development of the above equation. As may be seen in practice, in actual systems the diameters of the throttle and the pipe wherein it is mounted can be commensurable. Neglect of the inlet velocity therewith can result in an error when determining the required throttle diameter in design calculation and a flow rate in checking calculation, as well as when measuring a flow rate in the course of the test. The theoretical study has revealed that the flow velocity at the throttle inlet is responsible for two parameter values: the outlet flow velocity and the critical pressure ratio, which in turn determine the gas mass flow value. To calculate the gas mass flow, the dependencies are given in the paper, which allow taking into account the flow rate at the throttle inlet. The analysis of obtained dependencies has revealed that the degree of influence of inlet flow rate upon the mass flow is defined by two parameters: pressure ratio at the throttle and open area ratio of the throttle and the pipe wherein it is mounted. An analytical investigation has been pursued to evaluate the extent to which the gas mass flow through the throttle is affected by the inlet flow rate. The findings of the investigation and the indications for using the present dependencies are given in this paper. By and large the investigation allowed the

  1. Inductive flow meter for measuring the speed of flow and gas volume contained in a flow of liquid metal

    International Nuclear Information System (INIS)

    Mueller, S.

    1980-01-01

    The speed of flow of the sodium is measured in two closely adjacent flow crossections using pairs of electrodes in the field of two disc-shaped permanent magnets made of AlNiCo 450, by means of measurements of running time of speed fluctuations. The result of the measurement is independent of the temperature of the sensor and the temperature of the sodium. The same arrangement makes it possible to determine the proportion by volume of the fission gas in sodium with a limiting freequency of several kHz. (DG) [de

  2. A Conceptual Framework for the Indirect Method of Reporting Net Cash Flow from Operating Activities

    Science.gov (United States)

    Wang, Ting J.

    2010-01-01

    This paper describes the fundamental concept of the reconciliation behind the indirect method of the statement of cash flows. A conceptual framework is presented to demonstrate how accrual and cash-basis accounting methods relate to each other and to illustrate the concept of reconciling these two accounting methods. The conceptual framework…

  3. Towards real-time intrusion detection for NetFlow and IPFIX

    NARCIS (Netherlands)

    Hofstede, R.J.; Bartos, Vaclav; Sperotto, Anna; Pras, Aiko

    2013-01-01

    DDoS attacks bring serious economic and technical damage to networks and enterprises. Timely detection and mitigation are therefore of great importance. However, when flow monitoring systems are used for intrusion detection, as it is often the case in campus, enterprise and backbone networks, timely

  4. Entropy feature extraction on flow pattern of gas/liquid two-phase flow based on cross-section measurement

    International Nuclear Information System (INIS)

    Han, J; Dong, F; Xu, Y Y

    2009-01-01

    This paper introduces the fundamental of cross-section measurement system based on Electrical Resistance Tomography (ERT). The measured data of four flow regimes of the gas/liquid two-phase flow in horizontal pipe flow are obtained by an ERT system. For the measured data, five entropies are extracted to analyze the experimental data according to the different flow regimes, and the analysis method is examined and compared in three different perspectives. The results indicate that three different perspectives of entropy-based feature extraction are sensitive to the flow pattern transition in gas/liquid two-phase flow. By analyzing the results of three different perspectives with the changes of gas/liquid two-phase flow parameters, the dynamic structures of gas/liquid two-phase flow is obtained, and they also provide an efficient supplementary to reveal the flow pattern transition mechanism of gas/liquid two-phase flow. Comparison of the three different methods of feature extraction shows that the appropriate entropy should be used for the identification and prediction of flow regimes.

  5. Discharge characteristics and hydrodynamics behaviors of atmospheric plasma jets produced in various gas flow patterns

    Science.gov (United States)

    Setsuhara, Yuichi; Uchida, Giichiro; Nakajima, Atsushi; Takenaka, Kosuke; Koga, Kazunori; Shiratani, Masaharu

    2015-09-01

    Atmospheric nonequilibrium plasma jets have been widely employed in biomedical applications. For biomedical applications, it is an important issue to understand the complicated mechanism of interaction of the plasma jet with liquid. In this study, we present analysis of the discharge characteristics of a plasma jet impinging onto the liquid surface under various gas flow patterns such as laminar and turbulence flows. For this purpose, we analyzed gas flow patters by using a Schlieren gas-flow imaging system in detail The plasma jet impinging into the liquid surface expands along the liquid surface. The diameter of the expanded plasma increases with gas flow rate, which is well explained by an increase in the diameter of the laminar gas-flow channel. When the gas flow rate is further increased, the gas flow mode transits from laminar to turbulence in the gas flow channel, which leads to the shortening of the plasm-jet length. Our experiment demonstrated that the gas flow patterns strongly affect the discharge characteristics in the plasma-jet system. This study was partly supported by a Grant-in-Aid for Scientific Research on Innovative Areas ``Plasma Medical Innovation'' (24108003) from the Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT).

  6. Relation between plasma plume density and gas flow velocity in atmospheric pressure plasma

    International Nuclear Information System (INIS)

    Yambe, Kiyoyuki; Taka, Shogo; Ogura, Kazuo

    2014-01-01

    We have studied atmospheric pressure plasma generated using a quartz tube, helium gas, and copper foil electrode by applying RF high voltage. The atmospheric pressure plasma in the form of a bullet is released as a plume into the atmosphere. To study the properties of the plasma plume, the plasma plume current is estimated from the difference in currents on the circuit, and the drift velocity is measured using a photodetector. The relation of the plasma plume density n plu , which is estimated from the current and the drift velocity, and the gas flow velocity v gas is examined. It is found that the dependence of the density on the gas flow velocity has relations of n plu ∝ log(v gas ). However, the plasma plume density in the laminar flow is higher than that in the turbulent flow. Consequently, in the laminar flow, the density increases with increasing the gas flow velocity

  7. A mechanistic model of heat transfer for gas-liquid flow in vertical wellbore annuli.

    Science.gov (United States)

    Yin, Bang-Tang; Li, Xiang-Fang; Liu, Gang

    2018-01-01

    The most prominent aspect of multiphase flow is the variation in the physical distribution of the phases in the flow conduit known as the flow pattern. Several different flow patterns can exist under different flow conditions which have significant effects on liquid holdup, pressure gradient and heat transfer. Gas-liquid two-phase flow in an annulus can be found in a variety of practical situations. In high rate oil and gas production, it may be beneficial to flow fluids vertically through the annulus configuration between well tubing and casing. The flow patterns in annuli are different from pipe flow. There are both casing and tubing liquid films in slug flow and annular flow in the annulus. Multiphase heat transfer depends on the hydrodynamic behavior of the flow. There are very limited research results that can be found in the open literature for multiphase heat transfer in wellbore annuli. A mechanistic model of multiphase heat transfer is developed for different flow patterns of upward gas-liquid flow in vertical annuli. The required local flow parameters are predicted by use of the hydraulic model of steady-state multiphase flow in wellbore annuli recently developed by Yin et al. The modified heat-transfer model for single gas or liquid flow is verified by comparison with Manabe's experimental results. For different flow patterns, it is compared with modified unified Zhang et al. model based on representative diameters.

  8. On a boundary layer problem related to the gas flow in shales

    KAUST Repository

    Barenblatt, G. I.; Monteiro, P. J. M.; Rycroft, C. H.

    2013-01-01

    The development of gas deposits in shales has become a significant energy resource. Despite the already active exploitation of such deposits, a mathematical model for gas flow in shales does not exist. Such a model is crucial for optimizing

  9. Continuous gas/liquid–liquid/liquid flow synthesis of 4-fluoropyrazole derivatives by selective direct fluorination

    Directory of Open Access Journals (Sweden)

    Jessica R. Breen

    2011-08-01

    Full Text Available 4-Fluoropyrazole systems may be prepared by a single, sequential telescoped two-step continuous gas/liquid–liquid/liquid flow process from diketone, fluorine gas and hydrazine starting materials.

  10. Software development for continuous-gas-flow AMS

    International Nuclear Information System (INIS)

    Reden, K.F. von; Roberts, M.L.; Jenkins, W.J.; Rosenheim, B.E.; McNichol, A.P.; Schneider, R.J.

    2008-01-01

    The National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) Facility at Woods Hole Oceanographic Institution is presently completing installation of a novel continuous-flow AMS system. A multi-year development of an AMS microwave gas ion source in collaboration with Atomic Energy Canada Limited (AECL), Chalk River, has preceded this final step of an implementation that is expected to add a new dimension to 14 C AMS. National Instruments, NIM, and CAMAC modules have been programmed with LabVIEW on a Windows XP platform to form the basis for data acquisition. In this paper we discuss possible applications and include simulations of expected data acquisition scenarios like real-time AMS analysis of chromatograms. Particular attention will have to be given to issues of synchronization between rapidly changing input amplitudes and signal processing cycles in hardware and software

  11. Micro/Nano-pore Network Analysis of Gas Flow in Shale Matrix.

    Science.gov (United States)

    Zhang, Pengwei; Hu, Liming; Meegoda, Jay N; Gao, Shengyan

    2015-08-27

    The gas flow in shale matrix is of great research interests for optimized shale gas extraction. The gas flow in the nano-scale pore may fall in flow regimes such as viscous flow, slip flow and Knudsen diffusion. A 3-dimensional nano-scale pore network model was developed to simulate dynamic gas flow, and to describe the transient properties of flow regimes. The proposed pore network model accounts for the various size distributions and low connectivity of shale pores. The pore size, pore throat size and coordination number obey normal distribution, and the average values can be obtained from shale reservoir data. The gas flow regimes were simulated using an extracted pore network backbone. The numerical results show that apparent permeability is strongly dependent on pore pressure in the reservoir and pore throat size, which is overestimated by low-pressure laboratory tests. With the decrease of reservoir pressure, viscous flow is weakening, then slip flow and Knudsen diffusion are gradually becoming dominant flow regimes. The fingering phenomenon can be predicted by micro/nano-pore network for gas flow, which provides an effective way to capture heterogeneity of shale gas reservoir.

  12. HRL Aespoe - two-phase flow experiment - gas and water flow in fractured crystalline rock

    International Nuclear Information System (INIS)

    Kull, H.; Liedtke, L.

    1998-01-01

    (The full text of the contribution follows:) Gas generated from radioactive waste may influence the hydraulic and mechanical properties of the man-made barriers and the immediate surroundings of the repository. Prediction of alteration in fractured crystalline rock is difficult. There is a lack of experimental data, and calibrated models are not yet available. Because of the general importance of this matter the German Federal Ministry for Education, Science, Research and Technology decided to conduct a two-phase flow study at HRL Aespoe within the scope of the co-operation agreement with SKB. Within the presentation an overview of field experiments and modelling studies scheduled until end of '99 are given. Conceptual models for one- and two-phase flow, methodologies and with respect to numerical calculations necessary parameter set-ups are discussed. Common objective of in-situ experiments is to calibrate flow models to improve the reliability of predictions for gas migration through fractured rock mass. Hence, in a defined dipole flow field in niche 2/715 at HRL Aespoe effective hydraulic parameters are evaluated. Numerical modelling of non-isothermal, two-phase, two-component processes is feasible only for two-dimensional representation of a porous medium. To overcome this restriction a computer program will be developed to model three-dimensional, fractured, porous media. Rational aspects of two-phase flow studies are for the designing of geotechnical barriers and for the long-term safety analysis of potential radionuclide transport in a future repository required for the licensing process

  13. Leaf water relations and net gas exchange responses of salinized Carrizo citrange seedlings during drought stress and recovery.

    Science.gov (United States)

    Pérez-Pérez, J G; Syvertsen, J P; Botía, P; García-Sánchez, F

    2007-08-01

    Since salinity and drought stress can occur together, an assessment was made of their interacting effects on leaf water relations, osmotic adjustment and net gas exchange in seedlings of the relatively chloride-sensitive Carrizo citrange, Citrus sinensis x Poncirus trifoliata. Plants were fertilized with nutrient solution with or without additional 100 mm NaCl (salt and no-salt treatments). After 7 d, half of the plants were drought stressed by withholding irrigation water for 10 d. Thus, there were four treatments: salinized and non-salinized plants under drought-stress or well-watered conditions. After the drought period, plants from all stressed treatments were re-watered with nutrient solution without salt for 8 d to study recovery. Leaf water relations, gas exchange parameters, chlorophyll fluorescence, proline, quaternary ammonium compounds and leaf and root concentrations of Cl(-) and Na(+) were measured. Salinity increased leaf Cl(-) and Na(+) concentrations and decreased osmotic potential (Psi(pi)) such that leaf relative water content (RWC) was maintained during drought stress. However, in non-salinized drought-stressed plants, osmotic adjustment did not occur and RWC decreased. The salinity-induced osmotic adjustment was not related to any accumulation of proline, quaternary ammonium compounds or soluble sugars. Net CO(2) assimilation rate (A(CO2)) was reduced in leaves from all stressed treatments but the mechanisms were different. In non-salinized drought-stressed plants, lower A(CO2) was related to low RWC, whereas in salinized plants decreased A(CO2) was related to high levels of leaf Cl(-) and Na(+). A(CO2) recovered after irrigation in all the treatments except in previously salinized drought-stressed leaves which had lower RWC and less chlorophyll but maintained high levels of Cl(-), Na(+) and quaternary ammonium compounds after recovery. High leaf levels of Cl(-) and Na(+) after recovery apparently came from the roots. Plants preconditioned by

  14. Flow-pattern identification and nonlinear dynamics of gas-liquid two-phase flow in complex networks.

    Science.gov (United States)

    Gao, Zhongke; Jin, Ningde

    2009-06-01

    The identification of flow pattern is a basic and important issue in multiphase systems. Because of the complexity of phase interaction in gas-liquid two-phase flow, it is difficult to discern its flow pattern objectively. In this paper, we make a systematic study on the vertical upward gas-liquid two-phase flow using complex network. Three unique network construction methods are proposed to build three types of networks, i.e., flow pattern complex network (FPCN), fluid dynamic complex network (FDCN), and fluid structure complex network (FSCN). Through detecting the community structure of FPCN by the community-detection algorithm based on K -mean clustering, useful and interesting results are found which can be used for identifying five vertical upward gas-liquid two-phase flow patterns. To investigate the dynamic characteristics of gas-liquid two-phase flow, we construct 50 FDCNs under different flow conditions, and find that the power-law exponent and the network information entropy, which are sensitive to the flow pattern transition, can both characterize the nonlinear dynamics of gas-liquid two-phase flow. Furthermore, we construct FSCN and demonstrate how network statistic can be used to reveal the fluid structure of gas-liquid two-phase flow. In this paper, from a different perspective, we not only introduce complex network theory to the study of gas-liquid two-phase flow but also indicate that complex network may be a powerful tool for exploring nonlinear time series in practice.

  15. Simultaneous integrated optimal energy flow of electricity, gas, and heat

    International Nuclear Information System (INIS)

    Shabanpour-Haghighi, Amin; Seifi, Ali Reza

    2015-01-01

    Highlights: • Integration of electrical, natural gas, and district heating networks is studied. • Part-load performances of units are considered in modeling. • A modified teaching–learning based optimization is used to solve the problem. • Results show the advantages of the integrated optimization approach. - Abstract: In this paper, an integrated approach to optimize electrical, natural gas, and district heating networks simultaneously is studied. Several interdependencies between these infrastructures are considered in details including a nonlinear part-load performance for boilers and CHPs besides the valve-point effect for generators. A novel approach based on selecting an appropriate set of state-variables for the problem is proposed that eliminates the addition of any new variable to convert irregular equations into a regular set while the optimization problem is still solvable. As a large optimization problem, the optimal solution cannot be achieved by conventional mathematical techniques. Hence, it is better to use evolutionary algorithms instead. In this paper, the well-known modified teaching–learning based optimization algorithm is utilized to solve the multi-period optimal power flow problem of multi-carrier energy networks. The proposed scheme is implemented and applied to a typical multi-carrier energy network. Results are compared with some other conventional heuristic algorithms and the applicability and superiority of the proposed methodology is verified

  16. Propagation characteristics of pulverized coal and gas two-phase flow during an outburst.

    Science.gov (United States)

    Zhou, Aitao; Wang, Kai; Fan, Lingpeng; Tao, Bo

    2017-01-01

    Coal and gas outbursts are dynamic failures that can involve the ejection of thousands tons of pulverized coal, as well as considerable volumes of gas, into a limited working space within a short period. The two-phase flow of gas and pulverized coal that occurs during an outburst can lead to fatalities and destroy underground equipment. This article examines the interaction mechanism between pulverized coal and gas flow. Based on the role of gas expansion energy in the development stage of outbursts, a numerical simulation method is proposed for investigating the propagation characteristics of the two-phase flow. This simulation method was verified by a shock tube experiment involving pulverized coal and gas flow. The experimental and simulated results both demonstrate that the instantaneous ejection of pulverized coal and gas flow can form outburst shock waves. These are attenuated along the propagation direction, and the volume fraction of pulverized coal in the two-phase flow has significant influence on attenuation of the outburst shock wave. As a whole, pulverized coal flow has a negative impact on gas flow, which makes a great loss of large amounts of initial energy, blocking the propagation of gas flow. According to comparison of numerical results for different roadway types, the attenuation effect of T-type roadways is best. In the propagation of shock wave, reflection and diffraction of shock wave interact through the complex roadway types.

  17. Influence of leakage flow on the behaviour of gas behind a blockage in LMFBR subassembly geometry

    International Nuclear Information System (INIS)

    Fukuzawa, Y.

    1980-07-01

    Observations were made of the behaviour of gas behind a uniform porous 21% corner blockage within a pin-bundle of LMFBR subassembly geometry. The main parameter of the experiment was the leakage flow rate through the blockage. The behaviour of gas is significantly influenced by the leakage flow rate. The measured size and residence time of a gas cavity formed behind the blockage are shown and the mechanisms of the gas cavity dispersion by the leakage flow discussed by using a simple model of the liquid flow distribution behind the blockage. (orig.) [de

  18. Comparison of differential pressure model based on flow regime for gas/liquid two-phase flow

    International Nuclear Information System (INIS)

    Dong, F; Zhang, F S; Li, W; Tan, C

    2009-01-01

    Gas/liquid two-phase flow in horizontal pipe is very common in many industry processes, because of the complexity and variability, the real-time parameter measurement of two-phase flow, such as the measurement of flow regime and flow rate, becomes a difficult issue in the field of engineering and science. The flow regime recognition plays a fundamental role in gas/liquid two-phase flow measurement, other parameters of two-phase flow can be measured more easily and correctly based on the correct flow regime recognition result. A multi-sensor system is introduced to make the flow regime recognition and the mass flow rate measurement. The fusion system is consisted of temperature sensor, pressure sensor, cross-section information system and v-cone flow meter. After the flow regime recognition by cross-section information system, comparison of four typical differential pressure (DP) models is discussed based on the DP signal of v-cone flow meter. Eventually, an optimum DP model has been chosen for each flow regime. The experiment result of mass flow rate measurement shows it is efficient to classify the DP models by flow regime.

  19. Transient Flow Dynamics in Optical Micro Well Involving Gas Bubbles

    Science.gov (United States)

    Johnson, B.; Chen, C. P.; Jenkins, A.; Spearing, S.; Monaco, L. A.; Steele, A.; Flores, G.

    2006-01-01

    The Lab-On-a-Chip Application Development (LOCAD) team at NASA s Marshall Space Flight Center is utilizing Lab-On-a-Chip to support technology development specifically for Space Exploration. In this paper, we investigate the transient two-phase flow patterns in an optic well configuration with an entrapped bubble through numerical simulation. Specifically, the filling processes of a liquid inside an expanded chamber that has bubbles entrapped. Due to the back flow created by channel expansion, the entrapped bubbles tend to stay stationary at the immediate downstream of the expansion. Due to the huge difference between the gas and liquid densities, mass conservation issues associated with numerical diffusion need to be specially addressed. The results are presented in terms of the movement of the bubble through the optic well. Bubble removal strategies are developed that involve only pressure gradients across the optic well. Results show that for the bubble to be moved through the well, pressure pulsations must be utilized in order to create pressure gradients across the bubble itself.

  20. Practical computation of multidimensional thermal flows in a gas centrifuge

    International Nuclear Information System (INIS)

    Berger, M.H.

    1982-12-01

    A finite-element theory is derived for Onsager's two-dimensional equation approximating the steady, viscous, gas motion in a high-speed centrifuge. A new high-order tensor product element is proposed to make the computations easy. The method of weighted residuals is used to construct the stiffness matrix, associated boundary integrals, and load vectors. Ekman suction conditions along horizontal surfaces are shown to be natural boundary conditions of the weak approximation. A class of pure bounary-value problems are solved for the field variables of interest. We evaluate the effect of Ekman suction on the flow by computing with and without suction. Also, we compute the case of pure two-dimensional flow where the azimuthal velocity perturbation is presumed to vanish. The effect of this simplifying assumption on the end-to-end temperature difference necessary for a given circulation is discussed. Numerical results are presented graphically and we show that the so-called streamfunction must be graphed in physical coordinates for the isolines to be streamlines. Only in this form do the velocity vectors lie tangent to the contours. Also, the radial velocity is redefined for graphical purposes

  1. A simple model of gas flow in a porous powder compact

    Energy Technology Data Exchange (ETDEWEB)

    Shugard, Andrew D. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Robinson, David B. [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2014-04-01

    This report describes a simple model for ideal gas flow from a vessel through a bed of porous material into another vessel. It assumes constant temperature and uniform porosity. Transport is treated as a combination of viscous and molecular flow, with no inertial contribution (low Reynolds number). This model can be used to fit data to obtain permeability values, determine flow rates, understand the relative contributions of viscous and molecular flow, and verify volume calibrations. It draws upon the Dusty Gas Model and other detailed studies of gas flow through porous media.

  2. Simulations of viscous and compressible gas-gas flows using high-order finite difference schemes

    Science.gov (United States)

    Capuano, M.; Bogey, C.; Spelt, P. D. M.

    2018-05-01

    A computational method for the simulation of viscous and compressible gas-gas flows is presented. It consists in solving the Navier-Stokes equations associated with a convection equation governing the motion of the interface between two gases using high-order finite-difference schemes. A discontinuity-capturing methodology based on sensors and a spatial filter enables capturing shock waves and deformable interfaces. One-dimensional test cases are performed as validation and to justify choices in the numerical method. The results compare well with analytical solutions. Shock waves and interfaces are accurately propagated, and remain sharp. Subsequently, two-dimensional flows are considered including viscosity and thermal conductivity. In Richtmyer-Meshkov instability, generated on an air-SF6 interface, the influence of the mesh refinement on the instability shape is studied, and the temporal variations of the instability amplitude is compared with experimental data. Finally, for a plane shock wave propagating in air and impacting a cylindrical bubble filled with helium or R22, numerical Schlieren pictures obtained using different grid refinements are found to compare well with experimental shadow-photographs. The mass conservation is verified from the temporal variations of the mass of the bubble. The mean velocities of pressure waves and bubble interface are similar to those obtained experimentally.

  3. Differences in net global warming potential and greenhouse gas intensity between major rice-based cropping systems in China.

    Science.gov (United States)

    Xiong, Zhengqin; Liu, Yinglie; Wu, Zhen; Zhang, Xiaolin; Liu, Pingli; Huang, Taiqing

    2015-12-02

    Double rice (DR) and upland crop-single rice (UR) systems are the major rice-based cropping systems in China, yet differences in net global warming potential (NGWP) and greenhouse gas intensity (GHGI) between the two systems are poorly documented. Accordingly, a 3-year field experiment was conducted to simultaneously measure methane (CH4) and nitrous oxide (N2O) emissions and changes in soil organic carbon (SOC) in oil rape-rice-rice and wheat-rice (representing DR and UR, respectively) systems with straw incorporation (0, 3 and 6 t/ha) during the rice-growing seasons. Compared with the UR system, the annual CH4, N2O, grain yield and NGWP were significantly increased in the DR system, though little effect on SOC sequestration or GHGI was observed without straw incorporation. Straw incorporation increased CH4 emission and SOC sequestration but had no significant effect on N2O emission in both systems. Averaged over the three study years, straw incorporation had no significant effect on NGWP and GHGI in the UR system, whereas these parameters were greatly increased in the DR system, i.e., by 108% (3 t/ha) and 180% (6 t/ha) for NGWP and 103% (3 t/ha) and 168% (6 t/ha) for GHGI.

  4. Differences in net global warming potential and greenhouse gas intensity between major rice-based cropping systems in China

    Science.gov (United States)

    Xiong, Zhengqin; Liu, Yinglie; Wu, Zhen; Zhang, Xiaolin; Liu, Pingli; Huang, Taiqing

    2015-01-01

    Double rice (DR) and upland crop-single rice (UR) systems are the major rice-based cropping systems in China, yet differences in net global warming potential (NGWP) and greenhouse gas intensity (GHGI) between the two systems are poorly documented. Accordingly, a 3-year field experiment was conducted to simultaneously measure methane (CH4) and nitrous oxide (N2O) emissions and changes in soil organic carbon (SOC) in oil rape-rice-rice and wheat-rice (representing DR and UR, respectively) systems with straw incorporation (0, 3 and 6 t/ha) during the rice-growing seasons. Compared with the UR system, the annual CH4, N2O, grain yield and NGWP were significantly increased in the DR system, though little effect on SOC sequestration or GHGI was observed without straw incorporation. Straw incorporation increased CH4 emission and SOC sequestration but had no significant effect on N2O emission in both systems. Averaged over the three study years, straw incorporation had no significant effect on NGWP and GHGI in the UR system, whereas these parameters were greatly increased in the DR system, i.e., by 108% (3 t/ha) and 180% (6 t/ha) for NGWP and 103% (3 t/ha) and 168% (6 t/ha) for GHGI. PMID:26626733

  5. Numerical simulation for gas-liquid two-phase flow in pipe networks

    International Nuclear Information System (INIS)

    Li Xiaoyan; Kuang Bo; Zhou Guoliang; Xu Jijun

    1998-01-01

    The complex pipe network characters can not directly presented in single phase flow, gas-liquid two phase flow pressure drop and void rate change model. Apply fluid network theory and computer numerical simulation technology to phase flow pipe networks carried out simulate and compute. Simulate result shows that flow resistance distribution is non-linear in two phase pipe network

  6. Development of acoustic flow instruments for solid/gas pipe flows

    International Nuclear Information System (INIS)

    Sheen, S.H.; Raptis, A.C.

    1986-05-01

    Two nonintrusive acoustic flow sensing techniques are reported. One technique, passive in nature, simply measures the bandpassed acoustic noise level produced by particle/particle and particle/wall collisions. The noise levels, given in true RMS voltages or in autocorrelations, show a linear relationship to particle velocity but increase with solid concentration. Therefore, the passive technique requires calibration and a separate measure of solid concentration before it can be used to monitor the particle velocity. The second technique is based on the active cross-correlation principle. It measures particle velocity directly by correlating flow-related signatures at two sensing stations. The velocity data obtained by this technique are compared with measurements by a radioactive-particle time-of-flight (TOF) method. A multiplier of 1.53 is required to bring the acoustic data into agreement with the radioactive TOF result. The difference may originate from the difference in flow fields where particles are detected. The radioactive method senses particles mainly in the turbulent region and essentially measures average particle velocity across the pipe, while the acoustic technique detects particles near the pipe wall, and so measures the particle velocity in the viscous sublayer. Both techniques were tested in flows of limestone and air and 1-mm glass beads and air at the Argonne National Laboratory Solid/Gas Test Facility (SGFTF). The test matrix covered solid velocities of 20 to 30 m/s in a 2-in. pipe and solid-to-gas loading ratios of 6 to 22. 37 refs., 19 figs., 4 tabs

  7. Compressible Flow Phenomena at Inception of Lateral Density Currents Fed by Collapsing Gas-Particle Mixtures

    Science.gov (United States)

    Valentine, Greg A.; Sweeney, Matthew R.

    2018-02-01

    Many geological flows are sourced by falling gas-particle mixtures, such as during collapse of lava domes, and impulsive eruptive jets, and sustained columns, and rock falls. The transition from vertical to lateral flow is complex due to the range of coupling between particles of different sizes and densities and the carrier gas, and due to the potential for compressible flow phenomena. We use multiphase modeling to explore these dynamics. In mixtures with small particles, and with subsonic speeds, particles follow the gas such that outgoing lateral flows have similar particle concentration and speed as the vertical flows. Large particles concentrate immediately upon impact and move laterally away as granular flows overridden by a high-speed jet of expelled gas. When a falling flow is supersonic, a bow shock develops above the impact zone, and this produces a zone of high pressure from which lateral flows emerge as overpressured wall jets. The jets form complex structures as the mixtures expand and accelerate and then recompress through a recompression zone that mimics a Mach disk shock in ideal gas jets. In mixtures with moderate to high ratios of fine to coarse particles, the latter tend to follow fine particles through the expansion-recompression flow fields because of particle-particle drag. Expansion within the flow fields can lead to locally reduced gas pressure that could enhance substrate erosion in natural flows. The recompression zones form at distances, and have peak pressures, that are roughly proportional to the Mach numbers of impacting flows.

  8. Solid-Gas Coupling Model for Coal-Rock Mass Deformation and Pressure Relief Gas Flow in Protection Layer Mining

    OpenAIRE

    Zhu, Zhuohui; Feng, Tao; Yuan, Zhigang; Xie, Donghai; Chen, Wei

    2018-01-01

    The solid-gas coupling model for mining coal-rock mass deformation and pressure relief gas flow in protection layer mining is the key to determine deformation of coal-rock mass and migration law of pressure relief gas of protection layer mining in outburst coal seams. Based on the physical coupling process between coal-rock mass deformation and pressure-relief gas migration, the coupling variable of mining coal-rock mass, a part of governing equations of gas seepage field and deformation fiel...

  9. Flow restriction of multicontrolled natural gas; Restritor de fluxo de gas natural microcontrolado

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, Lauro C.; Reis, Antonio M.; Maldonado, Waldemar; Suzuqui, Moises [Universidade para o Desenvolvimento do Estado e da Regiao do Pantanal (UNIDERP), Campo Grande, MS (Brazil). Nucleo de Energia, Automacao e Controle; Scucuglia, Jose W.; Cortez, Marco A.A. [Universidade para o Desenvolvimento do Estado e da Regiao do Pantanal (UNIDERP), Campo Grande, MS (Brazil). Curso de Engenharia Eletrica; Teixeira, Marcelo C.M. [UNESP, Ilha Solteira, SP (Brazil). Faculdade de Engenharia Eletrica; Carrasco, Benjamim N. [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2004-07-01

    One of the specific cases of control in the operation of natural gas distribution is of the automatic restriction of the outflow due the violations of standards of draining of the natural gas in the ducts. With the objective to get a device of low cost, with national technology and high technological value aggregate, developed an electronic, microcontrolled, programmable device, and of low cost, that will function connected the sensors and valves of flow control, of form to monitor in real time the outflow of draining of the natural gas in the respective ducts and to restrict of automatic form the outflow, that necessary or always convenient. The developed hardware was conceived using micro controllers of high performance with capacity of reading of sensors of pressure, temperature and measurers of outflow. Had to a serial communication and the storage in memory of mass with 264 capacity of Kbytes is possible the pertinent visualization of graphs and reports to the behavior of the outflow and performance of the system. An internal RTC - Real Clock Teams, added to the hardware a clock and a calendar for acquisition of data in the schedule defined, as well as the possibility of unloading of the data through the telephonic line, using one embedded modem. (author)

  10. Analysis of three loss-of-flow accidents in the first wall cooling system of NET/ITER

    International Nuclear Information System (INIS)

    Komen, E.M.J.; Koning, H.

    1993-05-01

    This report presents the thermal-hydraulic analysis of three Loss-of-Flow Accidents (LOFAs) in the first wall cooling system of the Next European Torus (NET) design or the International Thermonuclear Experimental Reactor (ITER) design. The LOFAs considered result from a loss of the forced coolant flow caused by a loss of electrical power for the recirculation pump in the primary circuit. The analyses have been performed using the thermal-hydraulic system analysis code RELAP5/MOD3. In the analyses, special attention has been paid to the transient thermal-hydraulic behaviour of the cooling system and the temperature development in the first wall. In the LOFA case without plasma shutdown, melting starts in the first wall about 150 s after accident initiation. In the LOFA case with delayed plasma shutdown, melting starts in the first wall when the plasma shutdown is initiated later than about 110 s after accident initiation. Melting does not occur in the first wall during a LOFA with prompt plasma scram. (orig.)

  11. A New Approach for Accurate Prediction of Liquid Loading of Directional Gas Wells in Transition Flow or Turbulent Flow

    Directory of Open Access Journals (Sweden)

    Ruiqing Ming

    2017-01-01

    Full Text Available Current common models for calculating continuous liquid-carrying critical gas velocity are established based on vertical wells and laminar flow without considering the influence of deviation angle and Reynolds number on liquid-carrying. With the increase of the directional well in transition flow or turbulent flow, the current common models cannot accurately predict the critical gas velocity of these wells. So we built a new model to predict continuous liquid-carrying critical gas velocity for directional well in transition flow or turbulent flow. It is shown from sensitivity analysis that the correction coefficient is mainly influenced by Reynolds number and deviation angle. With the increase of Reynolds number, the critical liquid-carrying gas velocity increases first and then decreases. And with the increase of deviation angle, the critical liquid-carrying gas velocity gradually decreases. It is indicated from the case calculation analysis that the calculation error of this new model is less than 10%, where accuracy is much higher than those of current common models. It is demonstrated that the continuous liquid-carrying critical gas velocity of directional well in transition flow or turbulent flow can be predicted accurately by using this new model.

  12. Gas hydrates and clathrates. Flow assurance, environmental and economic perspectives and the Nigerian liquefied natural gas project

    International Nuclear Information System (INIS)

    Gbaruko, B.C.; Igwe, J.C.; Nwokeoma, R.C.; Gbaruko, P.N.

    2007-01-01

    Gas hydrates are nonstoichiometric crystalline compounds that belong to the inclusion group known as clathrates. They occur when water molecules attach themselves together through hydrogen bonding and form cavities which can be occupied by a single gas or volatile liquid molecule. Gas hydrates, asphaltenes and waxes are three major threats to flow assurance that must be well assessed by design team uptime. Gas hydrates are also looked upon as a future energy source and as a potential climate hazard. The purpose of this review is to show the chemistry and mechanism of gas hydrate formation, the problems they pose, especially to flow assurance, their system implications, their environmental and economic perspectives with respect to their prospects as storage and transport alternative to the liquefied natural gas technology. (author)

  13. Foam flow in a model porous medium: II. The effect of trapped gas.

    Science.gov (United States)

    Jones, S A; Getrouw, N; Vincent-Bonnieu, S

    2018-05-09

    Gas trapping is an important mechanism in both Water or Surfactant Alternating Gas (WAG/SAG) and foam injection processes in porous media. Foams for enhanced oil recovery (EOR) can increase sweep efficiency as they decrease the gas relative permeability, and this is mainly due to gas trapping. However, gas trapping mechanisms are poorly understood. Some studies have been performed during corefloods, but little work has been carried out to describe the bubble trapping behaviour at the pore scale. We have carried out foam flow tests in a micromodel etched with an irregular hexagonal pattern. Image analysis of the foam flow allowed the bubble centres to be tracked and local velocities to be obtained. It was found that the flow in the micromodel is dominated by intermittency and localized zones of trapped gas. The quantity of trapped gas was measured both by considering the fraction of bubbles that were trapped (via velocity thresholding) and by measuring the area fraction containing immobile gas (via image analysis). A decrease in the quantity of trapped gas was observed for both increasing total velocity and increasing foam quality. Calculations of the gas relative permeability were made with the Brooks Corey equation, using the measured trapped gas saturations. The results showed a decrease in gas relative permeabilities, and gas mobility, for increasing fractions of trapped gas. It is suggested that the shear thinning behaviour of foam could be coupled to the saturation of trapped gas.

  14. Modeling of flowing gas diode pumped alkali lasers: dependence of the operation on the gas velocity and on the nature of the buffer gas.

    Science.gov (United States)

    Barmashenko, B D; Rosenwaks, S

    2012-09-01

    A simple, semi-analytical model of flowing gas diode pumped alkali lasers (DPALs) is presented. The model takes into account the rise of temperature in the lasing medium with increasing pump power, resulting in decreasing pump absorption and slope efficiency. The model predicts the dependence of power on the flow velocity in flowing gas DPALs and checks the effect of using a buffer gas with high molar heat capacity and large relaxation rate constant between the 2P3/2 and 2P1/2 fine-structure levels of the alkali atom. It is found that the power strongly increases with flow velocity and that by replacing, e.g., ethane by propane as a buffer gas the power may be further increased by up to 30%. Eight kilowatt is achievable for 20 kW pump at flow velocity of 20  m/s.

  15. Numerical analysis of exhaust gas flow during the gas exchange process and the design optimization; Haiki manihorudonai no hiteijo nagare kaiseki gijutsu to sono oyo

    Energy Technology Data Exchange (ETDEWEB)

    Yoshizawa, K; Takeyama, S; Sakai, E; Tanzawa, K [Nissan Motor Co. Ltd., Tokyo (Japan)

    1997-10-01

    A simulation method was developed to estimate exhaust gas flow during the gas exchange process. In this simulation, one dimensional in-cylinder gas flow calculation and three dimensional exhaust gas flow calculation were combined. Gas flow inside the exhaust manifold catalyst during gas exchange was agreed in experiments. A simulation method was applied to select oxygen sensor location. A prediction of the oxygen sensor sensitivity of each cylinder gas was presented. The possibility of selecting oxygen sensor location in the exhaust manifold using calculation was proved. 5 refs., 10 figs., 1 tab.

  16. Effect of explicit representation of detailed stratigraphy on brine and gas flow at the Waste Isolation Pilot Plant

    International Nuclear Information System (INIS)

    Christian-Frear, T.L.; Webb, S.W.

    1996-04-01

    Stratigraphic units of the Salado Formation at the Waste Isolation Pilot Plant (WIPP) disposal room horizon includes various layers of halite, polyhalitic halite, argillaceous halite, clay, and anhydrite. Current models, including those used in the WIPP Performance Assessment calculations, employ a ''composite stratigraphy'' approach in modeling. This study was initiated to evaluate the impact that an explicit representation of detailed stratigraphy around the repository may have on fluid flow compared to the simplified ''composite stratigraphy'' models currently employed. Sensitivity of model results to intrinsic permeability anisotropy, interbed fracturing, two-phase characteristic curves, and gas-generation rates were studied. The results of this study indicate that explicit representation of the stratigraphy maintains higher pressures and does not allow as much fluid to leave the disposal room as compared to the ''composite stratigraphy'' approach. However, the differences are relatively small. Gas migration distances are also different between the two approaches. However, for the two cases in which explicit layering results were considerably different than the composite model (anisotropic and vapor-limited), the gas-migration distances for both models were negligible. For the cases in which gas migration distances were considerable, van Genuchten/Parker and interbed fracture, the differences between the two models were fairly insignificant. Overall, this study suggests that explicit representation of the stratigraphy in the WIPP PA models is not required for the parameter variations modeled if ''global quantities'' (e.g., disposal room pressures, net brine and gas flux into and out of disposal rooms) are the only concern

  17. Effect of explicit representation of detailed stratigraphy on brine and gas flow at the Waste Isolation Pilot Plant

    Energy Technology Data Exchange (ETDEWEB)

    Christian-Frear, T.L.; Webb, S.W. [Sandia National Labs., Albuquerque, NM (United States). Geohydrology Dept.

    1996-04-01

    Stratigraphic units of the Salado Formation at the Waste Isolation Pilot Plant (WIPP) disposal room horizon includes various layers of halite, polyhalitic halite, argillaceous halite, clay, and anhydrite. Current models, including those used in the WIPP Performance Assessment calculations, employ a ``composite stratigraphy`` approach in modeling. This study was initiated to evaluate the impact that an explicit representation of detailed stratigraphy around the repository may have on fluid flow compared to the simplified ``composite stratigraphy`` models currently employed. Sensitivity of model results to intrinsic permeability anisotropy, interbed fracturing, two-phase characteristic curves, and gas-generation rates were studied. The results of this study indicate that explicit representation of the stratigraphy maintains higher pressures and does not allow as much fluid to leave the disposal room as compared to the ``composite stratigraphy`` approach. However, the differences are relatively small. Gas migration distances are also different between the two approaches. However, for the two cases in which explicit layering results were considerably different than the composite model (anisotropic and vapor-limited), the gas-migration distances for both models were negligible. For the cases in which gas migration distances were considerable, van Genuchten/Parker and interbed fracture, the differences between the two models were fairly insignificant. Overall, this study suggests that explicit representation of the stratigraphy in the WIPP PA models is not required for the parameter variations modeled if ``global quantities`` (e.g., disposal room pressures, net brine and gas flux into and out of disposal rooms) are the only concern.

  18. Simulations of Micro Gas Flows by the DS-BGK Method

    KAUST Repository

    Li, Jun

    2011-01-01

    For gas flows in micro devices, the molecular mean free path is of the same order as the characteristic scale making the Navier-Stokes equation invalid. Recently, some micro gas flows are simulated by the DS-BGK method, which is convergent

  19. Correlation dimension estimate and its potential use in analysis of gas-solid flows

    DEFF Research Database (Denmark)

    Yin, Chungen; Rosendahl, Lasse Aistrup; Kær, Søren Knudsen

    2005-01-01

    Gas-solid flows are nonlinear systems. Therefore state-space analysis, a tool developed within the framework of nonlinear dynamics, could provide more useful insights into complex gas-solid flows. One of the positive aspects of state-space analysis is that the major properties of a system can be ...

  20. Visualization of Atomization Gas Flow and Melt Break-up Effects in Response to Nozzle Design

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Iver; Rieken, Joel; Meyer, John; Byrd, David; Heidloff, Andy

    2011-04-01

    Both powder particle size control and efficient use of gas flow energy are highly prized goals for gas atomization of metal and alloy powder to minimize off-size powder inventory (or 'reverb') and excessive gas consumption. Recent progress in the design of close-coupled gas atomization nozzles and the water model simulation of melt feed tubes were coupled with previous results from several types of gas flow characterization methods, e.g., aspiration measurements and gas flow visualization, to make progress toward these goals. Size distribution analysis and high speed video recordings of gas atomization reaction synthesis (GARS) experiments on special ferritic stainless steel alloy powders with an Ar+O{sub 2} gas mixture were performed to investigate the operating mechanisms and possible advantages of several melt flow tube modifications with one specific gas atomization nozzle. In this study, close-coupled gas atomization under closed wake gas flow conditions was demonstrated to produce large yields of ultrafine (dia.<20 {mu}m) powders (up to 32%) with moderate standard deviations (1.62 to 1.99). The increased yield of fine powders is consistent with the dual atomization mechanisms of closed wake gas flow patterns in the near-field of the melt orifice. Enhanced size control by stabilized pre-filming of the melt with a slotted trumpet bell pour tube was not clearly demonstrated in the current experiments, perhaps confounded by the influence of the melt oxidation reaction that occurred simultaneously with the atomization process. For this GARS variation of close-coupled gas atomization, it may be best to utilize the straight cylindrical pour tube and closed wake operation of an atomization nozzle with higher gas mass flow to promote the maximum yields of ultrafine powders that are preferred for the oxide dispersion strengthened alloys made from these powders.

  1. Heat transfer to a particle exposed to a rarefield ionized-gas flow

    International Nuclear Information System (INIS)

    Chen, X.; He, P.

    1986-01-01

    Analytical results are presented concerning the heat transfer to a spherical particle exposed to a high temperature, ionized- gas flow for the extreme case of free-molecule flow regime. It has been shown that the presence of relative velocity between the particle and the ionized gas reduces the floating potential on the particle, enhances the heat flux and causes appreciably non-uniform distribution of the local heat flux. Pronounced difference is found between metallic and non-metallic particles in the floating potential and the local heat flux distributions, in particular for the case with high gas-flow temperature. Relative contribution of atoms to the total heat flux is dominant for the case of low gas-flow temperature, while the heat flux is mainly caused by ions and electrons for the case of high gas-flow temperature

  2. Growth of a Massive Young Stellar Object Fed by a Gas Flow from a Companion Gas Clump

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xi; Shen, Zhiqiang [Shanghai Astronomical Observatories, Chinese Academy of Science, Nandan Rd. 80, Shanghai (China); Ren, Zhiyuan [National Astronomical Observatories, Chinese Academy of Science, Chaoyang District Datun Rd. A20, Beijing (China); Zhang, Qizhou [Harvard-Smithsonian Center for Astrophysics, 60 Garden St, Cambridge, MA 02138 (United States); Qiu, Keping [School of Astronomy and Space Science, Nanjing University, 22 Hankou Rd., Nanjing, Jiangsu 210093 (China)

    2017-02-01

    We present a Submillimeter Array (SMA) observation toward the young massive double-core system G350.69-0.49. This system consists of a northeast (NE) diffuse gas bubble and a southwest (SW) massive young stellar object (MYSO), both clearly seen in the Spitzer images. The SMA observations reveal a gas flow between the NE bubble and the SW MYSO in a broad velocity range from 5 to 30 km s{sup −1} with respect to the system velocity. The gas flow is well confined within the interval between the two objects and traces a significant mass transfer from the NE gas bubble to the SW massive core. The transfer flow can supply the material accreted onto the SW MYSO at a rate of 4.2×10{sup −4} M{sub ⊙} yr{sup −1}. The whole system therefore suggests a mode for the mass growth in the MYSO from a gas transfer flow launched from its companion gas clump, despite the driving mechanism of the transfer flow not being fully determined from the current data.

  3. Dynamic Optimal Energy Flow in the Integrated Natural Gas and Electrical Power Systems

    DEFF Research Database (Denmark)

    Fang, Jiakun; Zeng, Qing; Ai, Xiaomeng

    2018-01-01

    . Simulation on the test case illustrates the success of the modelling and the beneficial roles of the power-to-gas are analyzed. The proposed model can be used in the decision support for both planning and operation of the coordinated natural gas and electrical power systems.......This work focuses on the optimal operation of the integrated gas and electrical power system with bi-directional energy conversion. Considering the different response times of the gas and power systems, the transient gas flow and steady- state power flow are combined to formulate the dynamic...... optimal energy flow in the integrated gas and power systems. With proper assumptions and simplifications, the problem is transformed into a single stage linear programming. And only a single stage linear programming is needed to obtain the optimal operation strategy for both gas and power systems...

  4. Nitrogen fertilization of switchgrass increases biomass yield and improves net greenhouse gas balance in northern Michigan, U.S.A

    International Nuclear Information System (INIS)

    Nikiema, Paligwende; Rothstein, David E.; Min, Doo-Hong; Kapp, Christian J.

    2011-01-01

    Nitrogen (N) fertilization can increase bioenergy crop production; however, fertilizer production and application can contribute to greenhouse gas (GHG) emissions, potentially undermining the GHG benefits of bioenergy crops. The objective of this study was to evaluate the effects of N fertilization on GHG emissions and biomass production of switchgrass bioenergy crop, in northern Michigan. Nitrogen fertilization treatments included 0 kg ha -1 (control), 56 kg ha -1 (low) and 112 kg ha -1 (high) of N applied as urea. Soil fluxes of CO 2 , N 2 O and CH 4 were measured every two weeks using static chambers. Indirect GHG emissions associated with field activities, manufacturing and transport of fertilizer and pesticides were derived from the literature. Switchgrass aboveground biomass yield was evaluated at the end of the growing season. Nitrogen fertilization contributed little to soil GHG emissions; relative to the control, there were additional global warming potential of 0.7 Mg ha -1 y -1 and 1.5 Mg ha -1 y -1 as CO 2 equivalents (CO 2 eq), calculated using the IPCC values, in the low and high N fertilization treatments, respectively. However, N fertilization greatly stimulated CO 2 uptake by switchgrass, resulting in 1.5- and 2.5-fold increases in biomass yield in the low and high N fertilization treatments, respectively. Nitrogen amendments improved the net GHG benefits by 2.6 Mg ha -1 y -1 and 9.4 Mg ha -1 y -1 as CO 2 eq relative to the control. Results suggest that N fertilization of switchgrass in this region could reduce (15-50%) the land base needed for bioenergy production and decrease pressure on land for food and forage crop production. -- Highlights: → We examine the effects of N fertilization of switchgrass on GHG emissions. → Effects of N fertilization on biomass production of switchgrass bioenergy crop. → N fertilization contributed little to greenhouse gas emissions. → N fertilization greatly stimulated CO 2 uptake by the switchgrass. → N

  5. Gas flow rate and powder flow rate effect on properties of laser metal deposited Ti6Al4V

    CSIR Research Space (South Africa)

    Pityana, S

    2013-03-01

    Full Text Available . The powder flow rate and the gas flow rate were varied to study their effect on the physical, metallurgical and mechanical properties of the deposits. The physical properties studied are: the track width, the track height and the deposit weight...

  6. An atmospheric pressure flow reactor: Gas phase kinetics and mechanism in tropospheric conditions without wall effects

    Science.gov (United States)

    Koontz, Steven L.; Davis, Dennis D.; Hansen, Merrill

    1988-01-01

    A new type of gas phase flow reactor, designed to permit the study of gas phase reactions near 1 atm of pressure, is described. A general solution to the flow/diffusion/reaction equations describing reactor performance under pseudo-first-order kinetic conditions is presented along with a discussion of critical reactor parameters and reactor limitations. The results of numerical simulations of the reactions of ozone with monomethylhydrazine and hydrazine are discussed, and performance data from a prototype flow reactor are presented.

  7. Convection Study by PIV Method Within Horizontal Liquid Layer Evaporating Into Inert Gas Flow

    Directory of Open Access Journals (Sweden)

    Kreta Aleksei

    2016-01-01

    Full Text Available The paper is devoted to the experimental study of convection in a horizontal evaporating liquid layer (ethanol of limited size under the action of gas flow (air. The two-dimensional velocity field in the liquid layer is obtained using the PIV method. The existence of a vortex convective flow within a liquid layer directed towards the gas flow has been revealed.

  8. High bias gas flows increase lung injury in the ventilated preterm lamb.

    Directory of Open Access Journals (Sweden)

    Katinka P Bach

    Full Text Available BACKGROUND: Mechanical ventilation of preterm babies increases survival but can also cause ventilator-induced lung injury (VILI, leading to the development of bronchopulmonary dysplasia (BPD. It is not known whether shear stress injury from gases flowing into the preterm lung during ventilation contributes to VILI. METHODS: Preterm lambs of 131 days' gestation (term = 147 d were ventilated for 2 hours with a bias gas flow of 8 L/min (n = 13, 18 L/min (n = 12 or 28 L/min (n = 14. Physiological parameters were measured continuously and lung injury was assessed by measuring mRNA expression of early injury response genes and by histological analysis. Control lung tissue was collected from unventilated age-matched fetuses. Data were analysed by ANOVA with a Tukey post-hoc test when appropriate. RESULTS: High bias gas flows resulted in higher ventilator pressures, shorter inflation times and decreased ventilator efficiency. The rate of rise of inspiratory gas flow was greatest, and pulmonary mRNA levels of the injury markers, EGR1 and CTGF, were highest in lambs ventilated with bias gas flows of 18 L/min. High bias gas flows resulted in increased cellular proliferation and abnormal deposition of elastin, collagen and myofibroblasts in the lung. CONCLUSIONS: High ventilator bias gas flows resulted in increased lung injury, with up-regulation of acute early response genes and increased histological lung injury. Bias gas flows may, therefore, contribute to VILI and BPD.

  9. Study on Gas-liquid Falling Film Flow in Internal Heat Integrated Distillation Column

    Science.gov (United States)

    Liu, Chong

    2017-10-01

    Gas-liquid internally heat integrated distillation column falling film flow with nonlinear characteristics, study on gas liquid falling film flow regulation control law, can reduce emissions of the distillation column, and it can improve the quality of products. According to the distribution of gas-liquid mass balance internally heat integrated distillation column independent region, distribution model of heat transfer coefficient of building internal heat integrated distillation tower is obtained liquid distillation falling film flow in the saturated vapour pressure of liquid water balance, using heat transfer equation and energy equation to balance the relationship between the circulating iterative gas-liquid falling film flow area, flow parameter information, at a given temperature, pressure conditions, gas-liquid flow falling film theory makes the optimal parameters to achieve the best fitting value with the measured values. The results show that the geometric gas-liquid internally heat integrated distillation column falling film flow heat exchange area and import column thermostat, the average temperature has significant. The positive correlation between the heat exchanger tube entrance due to temperature difference between inside and outside, the heat flux is larger, with the increase of internal heat integrated distillation column temperature, the slope decreases its temperature rise, which accurately describes the internal gas-liquid heat integrated distillation tower falling film flow regularity, take appropriate measures to promote the enhancement of heat transfer. It can enhance the overall efficiency of the heat exchanger.

  10. Modelling of non-catalytic reactors in a gas-solid trickle flow reactor: Dry, regenerative flue gas desulphurization using a silica-supported copper oxide sorbent

    NARCIS (Netherlands)

    Kiel, J.H.A.; Kiel, J.H.A.; Prins, W.; van Swaaij, Willibrordus Petrus Maria

    1992-01-01

    A one-dimensional, two-phase dispersed plug flow model has been developed to describe the steady-state performance of a relatively new type of reactor, the gas-solid trickle flow reactor (GSTFR). In this reactor, an upward-flowing gas phase is contacted with as downward-flowing dilute solids phase

  11. Taylor flow hydrodynamics in gas-liquid-solid micro reactors

    NARCIS (Netherlands)

    Warnier, M.J.F.

    2009-01-01

    Chemical reactions in which a gas phase component reacts with a liquid phase omponent at the surface of a solid catalyst are often encountered in chemical industry. The rate of such a gas-liquid-solid reaction is often limited by the mass transfer rate of the gas phase component, which depends on

  12. Gas flows in radial micro-nozzles with pseudo-shocks

    Science.gov (United States)

    Kiselev, S. P.; Kiselev, V. P.; Zaikovskii, V. N.

    2017-12-01

    In the present paper, results of an experimental and numerical study of supersonic gas flows in radial micro-nozzles are reported. A distinguishing feature of such flows is the fact that two factors, the nozzle divergence and the wall friction force, exert a substantial influence on the flow structure. Under the action of the wall friction force, in the micro-nozzle there forms a pseudo-shock that separates the supersonic from subsonic flow region. The position of the pseudo-shock can be evaluated from the condition of flow blockage in the nozzle exit section. A detailed qualitative and quantitative analysis of gas flows in radial micro-nozzles is given. It is shown that the gas flow in a micro-nozzle is defined by the complicated structure of the boundary layer in the micro-nozzle, this structure being dependent on the width-to-radius ratio of the nozzle and its inlet-to-outlet pressure ratio.

  13. Solution of weakly compressible isothermal flow in landfill gas collection networks

    Energy Technology Data Exchange (ETDEWEB)

    Nec, Y [Thompson Rivers University, Kamloops, British Columbia (Canada); Huculak, G, E-mail: cranberryana@gmail.com, E-mail: greg@gnhconsulting.ca [GNH Consulting, Delta, British Columbia (Canada)

    2017-12-15

    Pipe networks collecting gas in sanitary landfills operate under the regime of a weakly compressible isothermal flow of ideal gas. The effect of compressibility has been traditionally neglected in this application in favour of simplicity, thereby creating a conceptual incongruity between the flow equations and thermodynamic equation of state. Here the flow is solved by generalisation of the classic Darcy–Weisbach equation for an incompressible steady flow in a pipe to an ordinary differential equation, permitting continuous variation of density, viscosity and related fluid parameters, as well as head loss or gain due to gravity, in isothermal flow. The differential equation is solved analytically in the case of ideal gas for a single edge in the network. Thereafter the solution is used in an algorithm developed to construct the flow equations automatically for a network characterised by an incidence matrix, and determine pressure distribution, flow rates and all associated parameters therein. (paper)

  14. Solution of weakly compressible isothermal flow in landfill gas collection networks

    Science.gov (United States)

    Nec, Y.; Huculak, G.

    2017-12-01

    Pipe networks collecting gas in sanitary landfills operate under the regime of a weakly compressible isothermal flow of ideal gas. The effect of compressibility has been traditionally neglected in this application in favour of simplicity, thereby creating a conceptual incongruity between the flow equations and thermodynamic equation of state. Here the flow is solved by generalisation of the classic Darcy-Weisbach equation for an incompressible steady flow in a pipe to an ordinary differential equation, permitting continuous variation of density, viscosity and related fluid parameters, as well as head loss or gain due to gravity, in isothermal flow. The differential equation is solved analytically in the case of ideal gas for a single edge in the network. Thereafter the solution is used in an algorithm developed to construct the flow equations automatically for a network characterised by an incidence matrix, and determine pressure distribution, flow rates and all associated parameters therein.

  15. Solution of weakly compressible isothermal flow in landfill gas collection networks

    International Nuclear Information System (INIS)

    Nec, Y; Huculak, G

    2017-01-01

    Pipe networks collecting gas in sanitary landfills operate under the regime of a weakly compressible isothermal flow of ideal gas. The effect of compressibility has been traditionally neglected in this application in favour of simplicity, thereby creating a conceptual incongruity between the flow equations and thermodynamic equation of state. Here the flow is solved by generalisation of the classic Darcy–Weisbach equation for an incompressible steady flow in a pipe to an ordinary differential equation, permitting continuous variation of density, viscosity and related fluid parameters, as well as head loss or gain due to gravity, in isothermal flow. The differential equation is solved analytically in the case of ideal gas for a single edge in the network. Thereafter the solution is used in an algorithm developed to construct the flow equations automatically for a network characterised by an incidence matrix, and determine pressure distribution, flow rates and all associated parameters therein. (paper)

  16. U.S. natural gas pipeline flow and demand trends

    International Nuclear Information System (INIS)

    Carson, M.M.

    1992-01-01

    It is no surprise that regional natural gas supply and demand patterns in North America are constantly changing. A consensus of forecasters agree that the natural gas resource base is larger than envisaged in the early 1980s due to advances in exploration and production technology. In addition, on the demand side more gas will be burned by US power generators to meet growth in electricity. Gas consumption is up in the commercial sector, and natural gas is correctly seen as environmentally protective. But how much more natural gas does the US need? This paper reports that new pipeline projects are springing up all over the nation --- 43 to be exact, with most of them connecting gas deliverability out of basins west of the Mississippi to new markets along the Atlantic and Pacific coasts

  17. A critical comparison of constant and pulsed flow systems exploiting gas diffusion.

    Science.gov (United States)

    Silva, Claudineia Rodrigues; Henriquez, Camelia; Frizzarin, Rejane Mara; Zagatto, Elias Ayres Guidetti; Cerda, Victor

    2016-02-01

    Considering the beneficial aspects arising from the implementation of pulsed flows in flow analysis, and the relevance of in-line gas diffusion as an analyte separation/concentration step, influence of flow pattern in flow systems with in-line gas diffusion was critically investigated. To this end, constant or pulsed flows delivered by syringe or solenoid pumps were exploited. For each flow pattern, two variants involving different interaction times of the donor with the acceptor streams were studied. In the first one, both the acceptor and donor streams were continuously flowing, whereas in the second one, the acceptor was stopped during the gas diffusion step. Four different volatile species (ammonia, ethanol, carbon dioxide and hydrogen sulfide) were selected as models. For the flow patterns and variants studied, the efficiencies of mass transport in the gas diffusion process were compared, and sensitivity, repeatability, sampling frequency and recorded peak shape were evaluated. Analysis of the results revealed that sensitivity is strongly dependent on the implemented variant, and that flow pattern is an important feature in flow systems with in-line gas diffusion. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Experimental investigation on flow patterns of gas-liquid two-phase upward flow through packed channel with spheres

    International Nuclear Information System (INIS)

    Zhang Nan; Sun Zhongning; Zhao Zhongnan

    2011-01-01

    Experiments of visualized two-phase upward flow were conducted in the packed channel, which filled with 3, 5, 8 mm in diameter of glass sphere respectively. The gas superficial velocity ranges from 0.005 to 1.172 m/s. The liquid superficial velocity ranges from 0.004 to 0.093 m/s. Four representative flow patterns were observed as bubbly flow, cluster flow, liquid-pulse flow and churn-pulse flow, and corresponding flow pattern maps were also presented. It is found that the pulse flow region is dominant. The comparisons of flow pattern map between packed channel and non-packed channel show that the bubbly flow region in packed channel is narrower than that of non-packed channel due to the packing. The comparisons of flow pattern maps for three different packing sizes show that the cluster flow region expands with the increase of the packing diameter. In the low liquid superficial velocity, the cluster flow directly changes to churn-pulse flow in the packed channel with 8 mm packing. (authors)

  19. Numerical and experimental studies of droplet-gas flow

    Energy Technology Data Exchange (ETDEWEB)

    Joesang, Aage Ingebret

    2002-07-01

    This thesis considers droplet-gas flow by the use of numerical methods and experimental verification. A commercial vane separator was studied both numerical and by experiment. In addition some efforts are put into the numerical analysis of cyclones. The experimental part contains detailed measurements of the flow field between a pair of vanes in a vane separator and droplet size measurements. LDA (Laser Doppler Anemometry) was used to measure the velocity in two dimensions and corresponding turbulence quantities. The results from the LDA measurements are considered to be of high quality and are compared to numerical results obtained from a CFD (Computational Fluid Dynamics) analysis. The simulation showed good agreement between the numerical and experimental results. Combinations of different turbulence models; the standard k-epsilon model and the Reynold Stress Mode, different schemes; first order and higher order scheme and different near wall treatment of the turbulence; the Law of the wall and the Two-Layer Zonal model were used in the simulations. The Reynold Stress Model together with a higher order scheme performed rather poorly. The recirculation in parts of the separator was overpredicted in this case. For the other cases the overall predictions are satisfactory. PDA (Phase Doppler Anemometry) measurements were used to study the changes in the droplet size distribution through the vane separator. The PDA measurements show that smaller droplets are found at the outlet than present at the inlet. In the literature there exists different mechanisms for explaining the re-entrainment and generation of new droplets. The re-entrainments mechanisms are divided into four groups where droplet-droplet interaction, droplet break-up, splashing of impinging droplet and re-entrainment from the film are defined as the groups of re-entrainment mechanisms. Models for these groups are found in the literature and these models are tested for re-entrainment using the operational

  20. Melt flow characteristics in gas-assisted laser cutting

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    industrial applications. In this process the cut ... Under these assumptions the boundary layer theory flow over. Laser beam ... a flat plate can be applied to estimate the distance after which the flow separation takes place by calculating the ...

  1. Study of gas-water flow in horizontal rectangular channels

    Science.gov (United States)

    Chinnov, E. A.; Ron'shin, F. V.; Kabov, O. A.

    2015-09-01

    The two-phase flow in the narrow short horizontal rectangular channels 1 millimeter in height was studied experimentally. The features of formation of the two-phase flow were studied in detail. It is shown that with an increase in the channel width, the region of the churn and bubble regimes increases, compressing the area of the jet flow. The areas of the annular and stratified flow patterns vary insignificantly.

  2. Real-gas effects 1: Simulation of ideal gas flow by cryogenic nitrogen and other selected gases

    Science.gov (United States)

    Hall, R. M.

    1980-01-01

    The thermodynamic properties of nitrogen gas do not thermodynamically approximate an ideal, diatomic gas at cryogenic temperatures. Choice of a suitable equation of state to model its behavior is discussed and the equation of Beattie and Bridgeman is selected as best meeting the needs for cryogenic wind tunnel use. The real gas behavior of nitrogen gas is compared to an ideal, diatomic gas for the following flow processes: isentropic expansion; normal shocks; boundary layers; and shock wave boundary layer interactions. The only differences in predicted pressure ratio between nitrogen and an ideal gas that may limit the minimum operating temperatures of transonic cryogenic wind tunnels seem to occur at total pressures approaching 9atmospheres and total temperatures 10 K below the corresponding saturation temperature, where the differences approach 1 percent for both isentropic expansions and normal shocks. Several alternative cryogenic test gases - air, helium, and hydrogen - are also analyzed. Differences in air from an ideal, diatomic gas are similar in magnitude to those of nitrogen. Differences for helium and hydrogen are over an order of magnitude greater than those for nitrogen or air. Helium and hydrogen do not approximate the compressible flow of an ideal, diatomic gas.

  3. Net greenhouse gas emissions from manure management using anaerobic digestion technology in a beef cattle feedlot in Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Costa Junior, Ciniro, E-mail: cinirojr@hotmail.com [University of São Paulo, Center of Nuclear Energy in Agriculture, Laboratory of Biogeochemistry, Avenida Centenário, 303, Piracicaba, SP 13416-000 (Brazil); Cerri, Carlos E.P., E-mail: cepcerri@usp.br [University of São Paulo, “Luiz de Queiroz” College of Agriculture, Department of Soil Science, Avenida Pádua Dias, 11, Piracicaba, SP 13418-900 (Brazil); Pires, Alexandre V., E-mail: pires.1@usp.br [University of São Paulo, “Luiz de Queiroz” College of Agriculture, Department of Animal Science, Avenida Pádua Dias, 11, Piracicaba, SP 13418-900 (Brazil); Cerri, Carlos C., E-mail: cerri@cena.usp.br [University of São Paulo, Center of Nuclear Energy in Agriculture, Laboratory of Biogeochemistry, Avenida Centenário, 303, Piracicaba, SP 13416-000 (Brazil)

    2015-02-01

    As part of an agreement during the COP15, the Brazilian government is fostering several activities intended to mitigate greenhouse gas (GHG) emissions. One of them is the adoption of anaerobic digester (AD) for treating animal manure. Due to a lack of information, we developed a case study in order to evaluate the effect of such initiative for beef cattle feedlots. We considered the net GHG emissions (CH{sub 4} and N{sub 2}O) from the manure generated from 140 beef heifers confined for 90 days in the scope “housing to field application” by including field measurements, literature values, and the offset generated by the AD system through the replacement of conventional sources of nitrogen (N) fertilizer and electricity, respectively. Results showed that direct GHG emissions accounted for 0.14 ± 0.06 kg of carbon dioxide equivalent (CO{sub 2}eq) per kg of animal live weight gain (lwg), with ∼ 80% originating from field application, suggesting that this emission does not differ from the conventional manure management (without AD) typically done in Brazil (0.19 ± 0.07 kg of CO{sub 2}eq per kg lwg{sup −1}). However, 2.4 MWh and 658.0 kg of N-manure were estimated to be generated as a consequence of the AD utilization, potentially offsetting 0.13 ± 0.01 kg of CO{sub 2}eq kg lwg{sup −1} or 95% (± 45%) of total direct emissions from the manure management. Although, by replacing fossil fuel sources, i.e. diesel oil, this offset could be increased to 169% (± 47%). In summary, the AD has the potential to significantly mitigate GHG emissions from manure management in beef cattle feedlots, but the effect is indirect and highly dependent on the source to be replaced. In spite of the promising results, more and continuous field measurements for decreasing uncertainties and improving assumptions are required. Identifying shortcomings would be useful not only for the effectiveness of the Brazilian government, but also for worldwide plans in mitigating GHG emissions

  4. Net greenhouse gas emissions from manure management using anaerobic digestion technology in a beef cattle feedlot in Brazil.

    Science.gov (United States)

    Costa Junior, Ciniro; Cerri, Carlos E P; Pires, Alexandre V; Cerri, Carlos C

    2015-02-01

    As part of an agreement during the COP15, the Brazilian government is fostering several activities intended to mitigate greenhouse gas (GHG) emissions. One of them is the adoption of anaerobic digester (AD) for treating animal manure. Due to a lack of information, we developed a case study in order to evaluate the effect of such initiative for beef cattle feedlots. We considered the net GHG emissions (CH4 and N2O) from the manure generated from 140 beef heifers confined for 90 days in the scope "housing to field application" by including field measurements, literature values, and the offset generated by the AD system through the replacement of conventional sources of nitrogen (N) fertilizer and electricity, respectively. Results showed that direct GHG emissions accounted for 0.14 ± 0.06 kg of carbon dioxide equivalent (CO₂eq) per kg of animal live weight gain (lwg), with ~80% originating from field application, suggesting that this emission does not differ from the conventional manure management (without AD) typically done in Brazil (0.19 ± 0.07 kg of CO₂eq per kg lwg(-1)). However, 2.4 MWh and 658.0 kg of N-manure were estimated to be generated as a consequence of the AD utilization, potentially offsetting 0.13 ± 0.01 kg of CO₂eq kg lwg(-1) or 95% (±45%) of total direct emissions from the manure management. Although, by replacing fossil fuel sources, i.e. diesel oil, this offset could be increased to 169% (±47%). In summary, the AD has the potential to significantly mitigate GHG emissions from manure management in beef cattle feedlots, but the effect is indirect and highly dependent on the source to be replaced. In spite of the promising results, more and continuous field measurements for decreasing uncertainties and improving assumptions are required. Identifying shortcomings would be useful not only for the effectiveness of the Brazilian government, but also for worldwide plans in mitigating GHG emissions from beef production systems. Copyright

  5. Net greenhouse gas emissions from manure management using anaerobic digestion technology in a beef cattle feedlot in Brazil

    International Nuclear Information System (INIS)

    Costa Junior, Ciniro; Cerri, Carlos E.P.; Pires, Alexandre V.; Cerri, Carlos C.

    2015-01-01

    As part of an agreement during the COP15, the Brazilian government is fostering several activities intended to mitigate greenhouse gas (GHG) emissions. One of them is the adoption of anaerobic digester (AD) for treating animal manure. Due to a lack of information, we developed a case study in order to evaluate the effect of such initiative for beef cattle feedlots. We considered the net GHG emissions (CH 4 and N 2 O) from the manure generated from 140 beef heifers confined for 90 days in the scope “housing to field application” by including field measurements, literature values, and the offset generated by the AD system through the replacement of conventional sources of nitrogen (N) fertilizer and electricity, respectively. Results showed that direct GHG emissions accounted for 0.14 ± 0.06 kg of carbon dioxide equivalent (CO 2 eq) per kg of animal live weight gain (lwg), with ∼ 80% originating from field application, suggesting that this emission does not differ from the conventional manure management (without AD) typically done in Brazil (0.19 ± 0.07 kg of CO 2 eq per kg lwg −1 ). However, 2.4 MWh and 658.0 kg of N-manure were estimated to be generated as a consequence of the AD utilization, potentially offsetting 0.13 ± 0.01 kg of CO 2 eq kg lwg −1 or 95% (± 45%) of total direct emissions from the manure management. Although, by replacing fossil fuel sources, i.e. diesel oil, this offset could be increased to 169% (± 47%). In summary, the AD has the potential to significantly mitigate GHG emissions from manure management in beef cattle feedlots, but the effect is indirect and highly dependent on the source to be replaced. In spite of the promising results, more and continuous field measurements for decreasing uncertainties and improving assumptions are required. Identifying shortcomings would be useful not only for the effectiveness of the Brazilian government, but also for worldwide plans in mitigating GHG emissions from beef production systems

  6. Discrete unified gas kinetic scheme for all Knudsen number flows. III. Binary gas mixtures of Maxwell molecules

    Science.gov (United States)

    Zhang, Yue; Zhu, Lianhua; Wang, Ruijie; Guo, Zhaoli

    2018-05-01

    Recently a discrete unified gas kinetic scheme (DUGKS) in a finite-volume formulation based on the Boltzmann model equation has been developed for gas flows in all flow regimes. The original DUGKS is designed for flows of single-species gases. In this work, we extend the DUGKS to flows of binary gas mixtures of Maxwell molecules based on the Andries-Aoki-Perthame kinetic model [P. Andries et al., J. Stat. Phys. 106, 993 (2002), 10.1023/A:1014033703134. A particular feature of the method is that the flux at each cell interface is evaluated based on the characteristic solution of the kinetic equation itself; thus the numerical dissipation is low in comparison with that using direct reconstruction. Furthermore, the implicit treatment of the collision term enables the time step to be free from the restriction of the relaxation time. Unlike the DUGKS for single-species flows, a nonlinear system must be solved to determine the interaction parameters appearing in the equilibrium distribution function, which can be obtained analytically for Maxwell molecules. Several tests are performed to validate the scheme, including the shock structure problem under different Mach numbers and molar concentrations, the channel flow driven by a small gradient of pressure, temperature, or concentration, the plane Couette flow, and the shear driven cavity flow under different mass ratios and molar concentrations. The results are compared with those from other reliable numerical methods. The results show that the proposed scheme is an effective and reliable method for binary gas mixtures in all flow regimes.

  7. Measurement of flow characteristics of solid particles mixed with gas in pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Siberev, S P; Nazarov, S I; Soldatkin, G I

    1983-01-01

    A mathematical model of the interaction of solid particles in a gas stream flowing through a pipeline comprises equations for the energy and material balances in the system and for force and energy interactions between the solid particles and transducers located within the pipeline. Soviet researchers confirmed that the average value of stress recorded by a transducer is proportional to the average kinetic energy of the particles; for a constant particle speed, the stress is proportional to the mass flow of the particles. The analysis and flow transducer measurements are valuable in measuring and controlling flowline sand and soil in natural gas transport from gas wells and undergound storage facilities.

  8. Parents of two-phase flow and theory of “gas-lift”

    Directory of Open Access Journals (Sweden)

    Zitek Pavel

    2014-03-01

    Full Text Available This paper gives a brief overview of types of two-phase flow. Subsequently, it deals with their mutual division and problems with accuracy boundaries among particular types. It also shows the case of water flow through a pipe with external heating and the gradual origination of all kinds of flow. We have met it in solution of safety condition of various stages in pressurized and boiling water reactors. In the MSR there is a problem in the solution of gas-lift using helium as a gas and its secondary usage for clearing of the fuel mixture from gaseous fission products. Theory of gas-lift is described.

  9. Calculation of nonstationary gas-dynamic flows with periodic local supply of energy

    International Nuclear Information System (INIS)

    Mikhailova, N.V.; Myshetskaya, E.E.; Rakhimov, A.T.; Favorskii, A.P.

    The paper considers the motion of a flow of gas with local supply of energy periodic in time. Solution of the problem in one-dimensional formulation in the approximation of an ideal nonviscous non-heat-conducting gas is carried out by numerical methods. The possibility of emergence of the flow into a periodic regime is established and the rate of this process is calculated. The character of the periodic structure is investigated in dependence on the frequency of the superimposition of perturbations and the Mach number in unperturbed flow of the gas

  10. Parents of two-phase flow and theory of "gas-lift"

    Science.gov (United States)

    Zitek, Pavel; Valenta, Vaclav

    2014-03-01

    This paper gives a brief overview of types of two-phase flow. Subsequently, it deals with their mutual division and problems with accuracy boundaries among particular types. It also shows the case of water flow through a pipe with external heating and the gradual origination of all kinds of flow. We have met it in solution of safety condition of various stages in pressurized and boiling water reactors. In the MSR there is a problem in the solution of gas-lift using helium as a gas and its secondary usage for clearing of the fuel mixture from gaseous fission products. Theory of gas-lift is described.

  11. Experimental on two sensors combination used in horizontal pipe gas-water two-phase flow

    International Nuclear Information System (INIS)

    Wu, Hao; Dong, Feng

    2014-01-01

    Gas-water two phase flow phenomenon widely exists in production and living and the measurement of it is meaningful. A new type of long-waist cone flow sensor has been designed to measure two-phase mass flow rate. Six rings structure of conductance probe is used to measure volume fraction and axial velocity. The calibration of them have been made. Two sensors have been combined in horizontal pipeline experiment to measure two-phase flow mass flow rate. Several model of gas-water two-phase flow has been discussed. The calculation errors of total mass flow rate measurement is less than 5% based on the revised homogeneous flow model

  12. Gas-lift pumps for flowing and purifying molten silicon

    Science.gov (United States)

    Kellerman, Peter L.; Carlson, Frederick

    2016-02-23

    The embodiments herein relate to a sheet production apparatus. A vessel is configured to hold a melt of a material and a cooling plate is disposed proximate the melt. This cooling plate configured to form a sheet of the material on the melt. A pump is used. In one instance, this pump includes a gas source and a conduit in fluid communication with the gas source. In another instance, this pump injects a gas into a melt. The gas can raise the melt or provide momentum to the melt.

  13. Ion transport membrane module and vessel system with directed internal gas flow

    Science.gov (United States)

    Holmes, Michael Jerome; Ohrn, Theodore R.; Chen, Christopher Ming-Poh

    2010-02-09

    An ion transport membrane system comprising (a) a pressure vessel having an interior, an inlet adapted to introduce gas into the interior of the vessel, an outlet adapted to withdraw gas from the interior of the vessel, and an axis; (b) a plurality of planar ion transport membrane modules disposed in the interior of the pressure vessel and arranged in series, each membrane module comprising mixed metal oxide ceramic material and having an interior region and an exterior region; and (c) one or more gas flow control partitions disposed in the interior of the pressure vessel and adapted to change a direction of gas flow within the vessel.

  14. Study of gas-liquid flow in model porous media for heterogeneous catalysis

    Science.gov (United States)

    Francois, Marie; Bodiguel, Hugues; Guillot, Pierre; Laboratory of the Future Team

    2015-11-01

    Heterogeneous catalysis of chemical reactions involving a gas and a liquid phase is usually achieved in fixed bed reactors. Four hydrodynamic regimes have been observed. They depend on the total flow rate and the ratio between liquid and gas flow rate. Flow properties in these regimes influence transfer rates. Rather few attempts to access local characterization have been proposed yet, though these seem to be necessary to better describe the physical mechanisms involved. In this work, we propose to mimic slices of reactor by using two-dimensional porous media. We have developed a two-dimensional system that is transparent to allow the direct observation of the flow and the phase distribution. While varying the total flow rate and the gas/liquid flow rate ratio, we observe two hydrodynamic regimes: at low flow rate, the gaseous phase is continuous (trickle flow), while it is discontinuous at higher flow rate (pulsed flow). Thanks to some image analysis techniques, we are able to quantify the local apparent liquid saturation in the system. Its fluctuations in time are characteristic of the transition between the two regimes: at low liquid flow rates, they are negligible since the liquid/gas interface is fixed, whereas at higher flow rates we observe an alternation between liquid and gas. This transition between trickle to pulsed flow is in relative good agreement with the existing state of art. However, we report in the pulsed regime important flow heterogeneities at the scale of a few pores. These heterogeneities are likely to have a strong influence on mass transfers. We acknowledge the support of Solvay.

  15. Viscous slip coefficients for binary gas mixtures measured from mass flow rates through a single microtube

    OpenAIRE

    Yamaguchi, H.; Takamori, K.; Perrier, P.; Graur, I.; Matsuda, Y.; Niimi, T.

    2016-01-01

    The viscous slip coefficient for helium-argon binary gas mixture is extracted from the experimental values of the mass flow rate through a microtube. The mass flow rate is measured by the constant-volume method. The viscous slip coefficient was obtained by identifying the measured mass flow rate through a microtube with the corresponding analytical expression, which is a function of the Knudsen number. The measurements were carried out in the slip flow regime where the first-order slip bounda...

  16. 40 CFR 86.1320-90 - Gas meter or flow instrumentation calibration; particulate, methanol, and formaldehyde measurement.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 19 2010-07-01 2010-07-01 false Gas meter or flow instrumentation... Heavy-Duty Engines; Gaseous and Particulate Exhaust Test Procedures § 86.1320-90 Gas meter or flow..., methanol and formaldehyde emissions requires the use of gas meters or flow instrumentation to determine...

  17. A study on the effect of gas flow rate on the wave characteristics in two-phase gas-liquid annular flow

    International Nuclear Information System (INIS)

    Han Huawei; Zhu Zhenfeng; Gabriel, Kamiel

    2006-01-01

    Interfacial waves play a very important role in the mass, momentum and energy transport phenomena in annular flow. In this paper, film thickness time-trace measurements for air-water annular flow were collected in a small vertical tube using a parallel wire probe. Using the data, a typical disturbance wave shape was obtained and wave properties (e.g., width, height, speed and roughness) were presented. The liquid mass flux ranged from 100 to 200 kg/m 2 s and the gas mass flux ranged from 18 to 47 kg/m 2 s. Disturbance wave characteristics were defined and the effects of changing the gas flow rate on the wave spacing, wave width, wave peak height and wave base height were studied. An average velocity model for the wave and base regions has been developed to determine the wave velocity. The investigation method could be further extended to annular-mist flow which frequently occurs in boiling water reactors

  18. The Effect of Surfactants on Gas-Liquid Pipe Flows

    NARCIS (Netherlands)

    Van Nimwegen, A.T.

    2015-01-01

    Liquid loading is a major problem in the natural gas industry, in which gas production is limited by the accumulation of liquids in the well tubing. Liquid loading can be prevented by the injection of surfactants at the bottom of the well. The surfactants cause the liquid in the well to foam,

  19. Experiments in stratified gas-liquid pipe flow

    NARCIS (Netherlands)

    Birvalski, M.

    2015-01-01

    The growing demand for energy in the future will necessitate the production of natural gas from fields which are located farther offshore, in deep water and in very cold environments. This will confront us with difficulties in ensuring continuous production of the fluids (natural gas, condensate and

  20. Application of a vortex shedding flowmeter to the wide range measurement of high temperature gas flow

    International Nuclear Information System (INIS)

    Baker, S.P.; Ennis, R.M. Jr.; Herndon, P.G.

    1981-01-01

    A single flowmeter was required for helium gas measurement in a Gas Cooled Fast Breeder Reactor loss of coolant simulator. Volumetric flow accuracy of +-1.0% of reading was required over the Reynolds Number range 6 x 10 3 to 1 x 10 6 at flowing pressures from 0.2 to 9 MPa (29 to 1305 psia) at 350 0 C (660 0 F) flowing temperature. Because of its inherent accuracy and rangeability, a vortex shedding flowmeter was selected and specially modified to provide for a remoted thermal sensor. Experiments were conducted to determine the relationship between signal attenuation and sensor remoting geometry, as well as the relationship between gas flow parameters and remoted thermal sensor signal for both compressed air and helium gas. Based upon the results of these experiments, the sensor remoting geometry was optimized for this application. The resultant volumetric flow rangeability was 155:1. The associated temperature increase at the sensor position was 9 0 C above ambient (25 0 F) at a flowing temperature of 350 0 C. The volumetric flow accuracy was measured over the entire 155:1 flow range at parametric values of flowing density. A volumetric flow accuracy of +- % of reading was demonstrated

  1. Experimental Study of gas-liquid two-phase flow affected by wall surface wettability

    International Nuclear Information System (INIS)

    Takamasa, T.; Hazuku, T.; Hibiki, T.

    2008-01-01

    To evaluate the effect of wall surface wettability on the characteristics of upward gas-liquid two-phase flow in a vertical pipe, an experimental study was performed using three test pipes: an acrylic pipe, a hydrophilic pipe and a hydrophobic pipe. Basic flow characteristics such as flow patterns, pressure drop and void fraction were measured in these three pipes. In the hydrophilic pipe, a slug to churn flow transition boundary was shifted to a higher gas velocity at a given liquid velocity, whereas a churn to annular flow transition boundary was shifted to a lower gas velocity at a given liquid velocity. In the hydrophobic pipe, an inverted-churn flow regime was observed in the region where the churn flow regime was observed in the acrylic pipe, while a droplet flow regime was observed in the region where an annular flow regime was observed in the acrylic pipe. At a high gas flow rate, the mean void fraction in the hydrophobic pipe was higher than in the acrylic pipe. The effect of surface wettability on frictional pressure loss was confirmed to be insignificant under the present experimental conditions

  2. Stress and Damage Induced Gas Flow Pattern and Permeability Variation of Coal from Songzao Coalfield in Southwest China

    Directory of Open Access Journals (Sweden)

    Minghui Li

    2016-05-01

    Full Text Available The permeability of coal is a critical parameter in estimating the performance of coal reservoirs. Darcy’s law describes the flow pattern that the permeability has a linear relationship with the flow velocity. However, the stress induced deformation and damage can significantly influence the gas flow pattern and permeability of coal. Coals from Songzao coalfield in Chongqing, southwest China were collected for the study. The gas flow velocities under different injection gas pressures and effective stresses in the intact coal and damaged coal were tested using helium, incorporating the role of gas flow pattern on the permeability of coal. The relationships between the flow velocity and square of gas pressure gradient were discussed, which can help us to investigate the transformation conditions of gas linear flow and gas nonlinear flow in the coal. The results showed that the gas flow in the intact coal existed pseudo-initial flow rate under low effective stress. The low-velocity non-Darcy gas flow gradually occurred and the start-up pressure gradient increased in the coal as the effective stress increased. The gas flow rate in the damaged coal increased nonlinearly as the square of pressure gradient increased under low effective stress. The instability of gas flow caused by high ratio of injection gas pressure over effective stress in the damaged coal contributed to the increase of the gas flow rate. As the effective stress increased, the increase of gas flow rate in coal turned to be linear. The mechanisms of the phenomena were explored according to the experimental results. The permeability of coal was corrected based on the relationships between the flow velocity and square of gas pressure gradient, which showed advantages in accurately estimating the performance of coal reservoirs.

  3. A review on measuring methods of gas-liquid flow rates

    International Nuclear Information System (INIS)

    Minemura, Kiyoshi; Yamashita, Masato

    2000-01-01

    This paper presents a review on the state of current measuring techniques for gas-liquid multiphase flow rates. After briefly discussing the basic idea on measuring methods for single-phase and two-phase flows, existing methods for the two-phase flow rates are classified into several types, that is, with or without a homogenizing device, single or combined method of several techniques, with intrusive or non-intrusive sensors, and physical or software method. Each methods are comparatively reviewed in view of measuring accuracy and manageability. Its scope also contains the techniques developed for petroleum-gas-water flow rates. (author)

  4. Gas-kinetic unified algorithm for hypersonic flows covering various flow regimes solving Boltzmann model equation in nonequilibrium effect

    International Nuclear Information System (INIS)

    Li, Zhihui; Ma, Qiang; Wu, Junlin; Jiang, Xinyu; Zhang, Hanxin

    2014-01-01

    Based on the Gas-Kinetic Unified Algorithm (GKUA) directly solving the Boltzmann model equation, the effect of rotational non-equilibrium is investigated recurring to the kinetic Rykov model with relaxation property of rotational degrees of freedom. The spin movement of diatomic molecule is described by moment of inertia, and the conservation of total angle momentum is taken as a new Boltzmann collision invariant. The molecular velocity distribution function is integrated by the weight factor on the internal energy, and the closed system of two kinetic controlling equations is obtained with inelastic and elastic collisions. The optimization selection technique of discrete velocity ordinate points and numerical quadrature rules for macroscopic flow variables with dynamic updating evolvement are developed to simulate hypersonic flows, and the gas-kinetic numerical scheme is constructed to capture the time evolution of the discretized velocity distribution functions. The gas-kinetic boundary conditions in thermodynamic non-equilibrium and numerical procedures are studied and implemented by directly acting on the velocity distribution function, and then the unified algorithm of Boltzmann model equation involving non-equilibrium effect is presented for the whole range of flow regimes. The hypersonic flows involving non-equilibrium effect are numerically simulated including the inner flows of shock wave structures in nitrogen with different Mach numbers of 1.5-Ma-25, the planar ramp flow with the whole range of Knudsen numbers of 0.0009-Kn-10 and the three-dimensional re-entering flows around tine double-cone body

  5. A multiphase flow meter for the on-line determination of the flow rates of oil, water and gas

    International Nuclear Information System (INIS)

    Roach, G.J.; Watt, J.S.

    1997-01-01

    Multiphase mixtures of crude oil, formation water and gas are carried in pipelines from oil wells to production facilities. Multiphase flow meters (MFMs) are being developed to determine the flow rates of each component of the heterogeneous mixture in the pipeline. CSIRO Minerals has developed and field tested a gamma-ray MFM for the on-line determination of the flow rates of heterogeneous mixtures of oil, water and gas in pipelines. It consists of two specialised gamma-ray transmission gauges, and pressure and temperature sensors, mounted on the pipeline carrying the full flow of the production stream. The MFM separately measures liquids and gas flow rates, and the volume ratio of water and liquids (water cut). The MFM has been trialled at three offshore production facilities in Australia. In each, the MFM was mounted on the pipeline between the test manifold and the test separator. The multiphase streams from the various wells feeding to the platform were sequentially routed past the MFM. The MFM and test separator outputs were compared using regression analysis. The flow rates of oil, water and gas were each determined to relative errors in the range of 5-10% . The MFM has been in routine use on the West Kingfish platform in the Bass Strait since November 1994. The MFM was recently tested over a wide range of flow conditions at a Texaco flow facility near Houston. Water cut, based on pre-trial calibration, was determined to 2% rms over the range 0-100% water cut. The liquids and gas flow results were interpreted based on slip correlations obtained from comparison of the MFM and Texaco flows. Using these, the relative errors were respectively 6.6% for liquid flow, 6.2% for gas, 8% for oil and 8% for water. The MFM is licensed to Kvaerner FSSL of Aberdeen. Kvaerner will supply the gamma-ray MFM for both platform and subsea use. Technology transfer commenced in December 1996, and Kvaerner completed the manufacture of the first MFM in August 1997

  6. Aerodynamic improvement of the assembly through which gas conduits are taken into a smoke stack by simulating gas flow on a computer

    Science.gov (United States)

    Prokhorov, V. B.; Fomenko, M. V.; Grigor'ev, I. V.

    2012-06-01

    Results from computer simulation of gas flow motion for gas conduits taken on one and two sides into the gas-removal shaft of a smoke stack with a constant cross section carried out using the SolidWorks and FlowVision application software packages are presented.

  7. Large eddy simulations of flow and mixing in jets and swirl flows: application to a gas turbine

    Energy Technology Data Exchange (ETDEWEB)

    Schluter, J.U.

    2000-07-01

    Large Eddy Simulations (LES) are an accepted tool in turbulence research. Most LES investigations deal with low Reynolds-number flows and have a high spatial discretization, which results in high computational costs. To make LES applicable to industrial purposes, the possibilities of LES to deliver results with low computational costs on high Reynolds-number flows have to be investigated. As an example, the cold flow through the Siemens V64.3A.HR gas turbine burner shall be examined. It is a gas turbine burner of swirl type, where the fuel is injected on the surface of vanes perpendicular to the main air flow. The flow regime of an industrial gas turbine is governed by several flow phenomena. The most important are the fuel injection in form of a jet in cross flow (JICF) and the swirl flow issuing into a combustion chamber. In order to prove the ability of LES to deal with these flow phenomena, two numerical investigations were made in order to reproduce the results of experimental studies. The first one deals with JICF. It will be shown that the reproduction of three different JICF is possible with LES on meshes with a low number of mesh points. The results are used to investigate the flow physics of the JICF, especially the merging of two adjacent JICFs. The second fundamental investigation deals with swirl flows. Here, the accuracy of an axisymmetric assumption is examined in detail by comparing it to full 3D LES computations and experimental data. Having demonstrated the ability of LES and the flow solver to deal with such complex flows with low computational efforts, the LES approach is used to examine some details of the burner. First, the investigation of the fuel injection on a vane reveals that the vane flow tends to separate. Furthermore the tendency of the fuel jets to merge is shown. Second, the swirl flow in the combustion chamber is computed. For this investigation the vanes are removed from the burner and swirl is imposed as a boundary condition. As

  8. Stopped-flow technique for transit time measurement in a gas jet

    International Nuclear Information System (INIS)

    Rengan, K.; Lin, J.; Lim, T.; Meyer, R.A.; Harrell, J.

    1985-01-01

    A 'stopped-flow' technique for the measurement of transit time of reaction products in a gas jet is described. The method involved establishing the gas flow through the jet system when the reactor is operating steadily and allowing the pressure to reach equilibrium values. The gas flow is stopped by means of electrically operated valves. The transit-time measurement is achieved by opening the valves and initiating the multiscanning of total activity simultaneously. The value obtained agrees well with the transit time measured by pulsing the reactor. The 'stopped-flow' technique allows on-line measurement of transit time in any gas jet system where the physical transportation time is the major component of the transit time. This technique is especially useful for systems installed in reactors which do not have pulsing capability. (orig.)

  9. SIZE REDUCTION OF ELECTROSTATIC PRECIPITATOR CHAMBER BY MODIFICATION OF GAS FLOW DISTRIBUTION

    Directory of Open Access Journals (Sweden)

    Beata Sładkowska-Rybka

    2014-10-01

    Full Text Available Electrostatic precipitators (ESP are one of the most effective devices for particulate emission control, removing from the exhaust gases even 99,9 % of dust particles. The collection efficiency of the ESP depends on a number of factors: mechanical design and electrical operating parameters, physical and chemical properties of cleaned gas, characteristic of dust particles suspended in the gas. Among the most important factors affecting the ESP effectiveness, the velocity and the distribution of gas flow in the ESP chamber should be also indicated. Significant increase in ESP efficiency is possible thanks to the application of Skewed Gas Flow Technology (SGFT. In this paper the computer simulations results are shown. Authors investigated the possibility of ESP chamber size reduction by modification of gas flow distribution.

  10. Active bypass flow control for a seal in a gas turbine engine

    Science.gov (United States)

    Ebert, Todd A.; Kimmel, Keith D.

    2017-01-10

    An active bypass flow control system for controlling bypass compressed air based upon leakage flow of compressed air flowing past an outer balance seal between a stator and rotor of a first stage of a gas turbine in a gas turbine engine is disclosed. The active bypass flow control system is an adjustable system in which one or more metering devices may be used to control the flow of bypass compressed air as the flow of compressed air past the outer balance seal changes over time as the outer balance seal between the rim cavity and the cooling cavity wears. In at least one embodiment, the metering device may include a valve formed from one or more pins movable between open and closed positions in which the one pin at least partially bisects the bypass channel to regulate flow.

  11. Computational physics of electric discharges in gas flows

    CERN Document Server

    Surzhikov, Sergey T

    2012-01-01

    Gas discharges are of interest for many processes in mechanics, manufacturing, materials science and aerophysics. To understand the physics behind the phenomena is of key importance for the effective use and development of gas discharge devices. This worktreats methods of computational modeling of electrodischarge processes and dynamics of partially ionized gases. These methods are necessary to tackleproblems of physical mechanics, physics of gas discharges and aerophysics.Particular attention is given to a solution of two-dimensional problems of physical mechanics of glow discharges.The use o

  12. Rarefied gas flow simulations using high-order gas-kinetic unified algorithms for Boltzmann model equations

    Science.gov (United States)

    Li, Zhi-Hui; Peng, Ao-Ping; Zhang, Han-Xin; Yang, Jaw-Yen

    2015-04-01

    This article reviews rarefied gas flow computations based on nonlinear model Boltzmann equations using deterministic high-order gas-kinetic unified algorithms (GKUA) in phase space. The nonlinear Boltzmann model equations considered include the BGK model, the Shakhov model, the Ellipsoidal Statistical model and the Morse model. Several high-order gas-kinetic unified algorithms, which combine the discrete velocity ordinate method in velocity space and the compact high-order finite-difference schemes in physical space, are developed. The parallel strategies implemented with the accompanying algorithms are of equal importance. Accurate computations of rarefied gas flow problems using various kinetic models over wide ranges of Mach numbers 1.2-20 and Knudsen numbers 0.0001-5 are reported. The effects of different high resolution schemes on the flow resolution under the same discrete velocity ordinate method are studied. A conservative discrete velocity ordinate method to ensure the kinetic compatibility condition is also implemented. The present algorithms are tested for the one-dimensional unsteady shock-tube problems with various Knudsen numbers, the steady normal shock wave structures for different Mach numbers, the two-dimensional flows past a circular cylinder and a NACA 0012 airfoil to verify the present methodology and to simulate gas transport phenomena covering various flow regimes. Illustrations of large scale parallel computations of three-dimensional hypersonic rarefied flows over the reusable sphere-cone satellite and the re-entry spacecraft using almost the largest computer systems available in China are also reported. The present computed results are compared with the theoretical prediction from gas dynamics, related DSMC results, slip N-S solutions and experimental data, and good agreement can be found. The numerical experience indicates that although the direct model Boltzmann equation solver in phase space can be computationally expensive

  13. Thermodilution versus inert gas rebreathing for estimation of effective pulmonary blood flow

    DEFF Research Database (Denmark)

    Christensen, P; Clemensen, P; Andersen, P K

    2000-01-01

    To compare measurements of the effective pulmonary blood flow (Qep, i.e., nonshunted fraction of cardiac output, Qt) by the inert gas rebreathing (RB) method and the thermodilution (TD) technique in critically ill patients.......To compare measurements of the effective pulmonary blood flow (Qep, i.e., nonshunted fraction of cardiac output, Qt) by the inert gas rebreathing (RB) method and the thermodilution (TD) technique in critically ill patients....

  14. Measurements of gas velocity in supersonic flow using a laser beam

    International Nuclear Information System (INIS)

    Airoldi, V.J.T.; Santos, R. dos

    1982-01-01

    A study of measurements of supersonic velocities in a wind tunnel using a laser beam was performed. Techniques using lasers are most suitable because they do not disturb the gas flow. This work presents the technique entitled as fringe technique. It works using interference patterns due to two perpendicular laser beams crossing the sample (i.e. the gas flow). Experimental results are compared with other usual techniques. (R.S.)

  15. Influence of Gas Flow Rate on the Deposition Rate on Stainless Steel 202 Substrates

    OpenAIRE

    M.A. Chowdhury; D.M. Nuruzzaman

    2012-01-01

    Solid thin films have been deposited on stainless steel 202 (SS 202) substrates at different flow rates of natural gas using a hot filament thermal chemical vapor deposition (CVD) reactor. In the experiments, the variations of thin film deposition rate with the variation of gas flow rate have been investigated. The effects of gap between activation heater and substrate on the deposition rate have also been observed. Results show that deposition rate on SS 202 increases with the increase in g...

  16. Film behaviour of vertical gas-liquid flow in a large diameter pipe

    OpenAIRE

    Zangana, Mohammed Haseeb Sedeeq

    2011-01-01

    Gas-liquid flow commonly occurs in oil and gas production and processing system. Large diameter vertical pipes can reduce pressure drops and so minimize operating costs. However, there is a need for research on two-phase flow in large diameter pipes to provide confidence to designers of equipments such as deep water risers. In this study a number of experimental campaigns were carried out to measure pressure drop, liquid film thickness and wall shear in 127mm vertical pipe. Total pressur...

  17. Malignant human cell transformation of Marcellus shale gas drilling flow back water

    OpenAIRE

    Yao, Yixin; Chen, Tingting; Shen, Steven S.; Niu, Yingmei; DesMarais, Thomas L; Linn, Reka; Saunders, Eric; Fan, Zhihua; Lioy, Paul; Kluz, Thomas; Chen, Lung-Chi; Wu, Zhuangchun; Costa, Max

    2015-01-01

    The rapid development of high-volume horizontal hydraulic fracturing for mining natural gas from shale has posed potential impacts on human health and biodiversity. The produced flow back waters after hydraulic stimulation is known to carry high levels of saline and total dissolved solids. To understand the toxicity and potential carcinogenic effects of these waste waters, flow back water from five Marcellus hydraulic fracturing oil and gas wells were analyzed. The physicochemical nature of t...

  18. The impact of net value added on predicting the earnings and operating cash flow: An empirical study based on Tehran Stock Exchange

    Directory of Open Access Journals (Sweden)

    Omid Imani Khoshkhoo

    2013-12-01

    Full Text Available Information content of earnings and its components and other issues except the earnings such as the operating cash flow (OCF have been tested widely in the accounting and finance literature. Since they have had an essential role in most cases including financial reporting, contracts and evaluation models, specifying the items and financial variables that have had a significant relationship with these two variables are expected to be of utmost importance. One example of these variables and indicators is the value added. Although this variable has an economic concept, reporting of value added to the beneficiaries of business entity as the value-added statement has been observed in the field of accounting theories for many years. The main objective of this study was to investigate the effect of net value added (NVA as the basic result of value-added statement in predicting the accounting earnings and operating cash flow. For this purpose, the relationship of changes in net value added with the changes in accounting earnings and operating cash flow of listed companies in Tehran Stock Exchange from 2007 to 2011 was tested. Firstly the Single variable cross-sectional regression was analyzed and then the panel data analysis with the PLS technique was used to do a pooled analysis. The results of testing research hypothesis imply the significant relationship between changes in net value added and accounting earnings in the listed companies as cross-sectional and pooled forms. The results showed no significant relationship between changes in net value added and operating cash flow in the listed companies neither in cross-sectional nor pooled form.

  19. The use of a low-cost gas-liquid flow meter to monitor severe slugging

    DEFF Research Database (Denmark)

    Andreussi, Paolo; Bonizzi, Marco; Ciandri, Paolo

    2017-01-01

    A very simple, low-cost gas-liquid flow meter that only employs conventional field instrumentation has been used to monitor severe slugging occurring at the exit of a vertical pipe. This meter was originally developed for conventional oil field applications [1] and is based on the readings...... method to monitor severe slugging by means of low cost instrumentation, in particular, by replacing a cumbersome instrument such as a gamma-densitometer with a differential pressure transmitter. In field operation, the multiphase orifice used in these experiments can be replaced by a calibrated control...... of a multiphase orifice and the pressure drops of the gas-liquid mixture flowing in a vertical section of the pipe. Liquid and gas flow rates have been determined by means of semi-empirical equations developed for the specific set of flow parameters (geometry, flow rates, physical properties) adopted in a series...

  20. Propagation of atmospheric pressure helium plasma jet into ambient air at laminar gas flow

    International Nuclear Information System (INIS)

    Pinchuk, M; Kurakina, N; Spodobin, V; Stepanova, O

    2017-01-01

    The formation of an atmospheric pressure plasma jet (APPJ) in a gas flow passing through the discharge gap depends on both gas-dynamic properties and electrophysical parameters of the plasma jet generator. The paper presents the results of experimental and numerical study of the propagation of the APPJ in a laminar flow of helium. A dielectric-barrier discharge (DBD) generated inside a quartz tube equipped with a coaxial electrode system, which provided gas passing through it, served as a plasma source. The transition of the laminar regime of gas flow into turbulent one was controlled by the photography of a formed plasma jet. The corresponding gas outlet velocity and Reynolds numbers were revealed experimentally and were used to simulate gas dynamics with OpenFOAM software. The data of the numerical simulation suggest that the length of plasma jet at the unvarying electrophysical parameters of DBD strongly depends on the mole fraction of ambient air in a helium flow, which is established along the direction of gas flow. (paper)

  1. Propagation of atmospheric pressure helium plasma jet into ambient air at laminar gas flow

    Science.gov (United States)

    Pinchuk, M.; Stepanova, O.; Kurakina, N.; Spodobin, V.

    2017-05-01

    The formation of an atmospheric pressure plasma jet (APPJ) in a gas flow passing through the discharge gap depends on both gas-dynamic properties and electrophysical parameters of the plasma jet generator. The paper presents the results of experimental and numerical study of the propagation of the APPJ in a laminar flow of helium. A dielectric-barrier discharge (DBD) generated inside a quartz tube equipped with a coaxial electrode system, which provided gas passing through it, served as a plasma source. The transition of the laminar regime of gas flow into turbulent one was controlled by the photography of a formed plasma jet. The corresponding gas outlet velocity and Reynolds numbers were revealed experimentally and were used to simulate gas dynamics with OpenFOAM software. The data of the numerical simulation suggest that the length of plasma jet at the unvarying electrophysical parameters of DBD strongly depends on the mole fraction of ambient air in a helium flow, which is established along the direction of gas flow.

  2. A model of gas flow with friction in a slotted seal

    Directory of Open Access Journals (Sweden)

    Joachimiak Damian

    2016-09-01

    Full Text Available The paper discusses thermodynamic phenomena accompanying the flow of gas in a slotted seal. The analysis of the gas flow has been described based on an irreversible adiabatic transformation. A model based on the equation of total enthalpy balance has been proposed. The iterative process of the model aims at obtaining such a gas temperature distribution that will fulfill the continuity equation. The model allows for dissipation of the kinetic energy into friction heat by making use of the Blasius equation to determine the friction coefficient. Within the works, experimental research has been performed of the gas flow in a slotted seal of slot height 2 mm. Based on the experimental data, the equation of local friction coefficient was modified with a correction parameter. This parameter was described with the function of pressure ratio to obtain a mass flow of the value from the experiment. The reason for taking up of this problem is the absence of high accuracy models for calculating the gas flow in slotted seals. The proposed model allows an accurate determination of the mass flow in a slotted seal based on the geometry and gas initial and final parameters.

  3. Churn-annular flow pattern transition in a vertical upward gas-liquid two-phase flow in various conduits

    International Nuclear Information System (INIS)

    Takenaka, Nobuyuki; Ueda, Tadanobu; Asano, Hitoshi

    2008-01-01

    Void fraction was measured by neutron radiography for a vertical upward gas-water two-phase flow in a concentric annular tube with and with out a spacer, 4x4 rod bundle with and without a spacer and a tight rod bundle with and without a wrapping wire for various gas and liquid flow rates. The flow patterns of these two-phase flows were determined by the Mishima-Ishii flow pattern map and void fraction was calculated by the Ishii's drift flux model. The predicted values were compared with the experimental results. The void fraction was well predicted by the Mishima-Ishii flow pattern map and the Ishii's drift flux model except the annular flow region with void fraction lower than 0.8 for conduits with small equivalent diameter. A new churn-annular flow pattern transition condition of the void fraction equal to 0.8 was added. The void fraction for the present experimental condition was successful predicted with the new transition model. (author)

  4. Flow characteristics of centrifugal gas-liquid separator. Investigation with air-water two-phase flow experiment

    International Nuclear Information System (INIS)

    Yoneda, Kimitoshi; Inada, Fumio

    2004-01-01

    Air-water two-phase flow experiment was conducted to examine the basic flow characteristics of a centrifugal gas-liquid separator. Vertical transparent test section, which is 4 m in height, was used to imitate the scale of a BWR separator. Flow rate conditions of gas and liquid were fixed at 0.1 m 3 /s and 0.033 m 3 /s, respectively. Radial distributions of two-phase flow characteristics, such as void fraction, gas velocity and bubble chord length, were measured by traversing dual optical void probes in the test section, horizontally. The flow in the standpipe reached to quasi-developed state within the height-to-diameter aspect ratio H/D=10, which in turn can mean the maximum value for an ideal height design of a standpipe. The liquid film in the barrel showed a maximum thickness at 0.5 to 1 m in height from the swirler exit, which was a common result for three different standpipe length conditions, qualitatively and quantitatively. The empirical database obtained in this study would contribute practically to the validation of numerical analyses for an actual separator in a plant, and would also be academically useful for further investigations of two-phase flow in large-diameter pipes. (author)

  5. Dynamic simulation of dispersed gas-liquid two-phase flow using a discrete bubble model.

    NARCIS (Netherlands)

    Delnoij, E.; Lammers, F.A.; Kuipers, J.A.M.; van Swaaij, Willibrordus Petrus Maria

    1997-01-01

    In this paper a detailed hydrodynamic model for gas-liquid two-phase flow will be presented. The model is based on a mixed Eulerian-Lagrangian approach and describes the time-dependent two-dimensional motion of small, spherical gas bubbles in a bubble column operating in the homogeneous regime. The

  6. Effect of gas field production and CO2 injection on brine flow and salt precipitation

    NARCIS (Netherlands)

    Loeve, D.; Tambach, T.J.; Hofstee, C.; Plug, W.J.; Maas, J.

    2012-01-01

    This paper reports modeling of gas field produc-tion and CO2 injection from a theoretical reser-voir based on characteristics of the P18 gas field in the Dutch offshore, which consists of four geological deposits with different petrophysical properties. We especially focus on the brine flow during

  7. Gas–liquid flow in stirred reactors: Trailing vortices and gas accumulation behind impeller blades

    NARCIS (Netherlands)

    Ranade, V.; Deshpande, Vaibhav R.

    1999-01-01

    In a gas–liquid stirred reactor, gas tends to accumulate in low-pressure regions behind the impeller blades. Such gas accumulation significantly alters impeller performance characteristics. We have computationally investigated gas–liquid flow generated by a Rushton (disc) turbine. Rotating Rushton

  8. Brazing retort manifold design concept may minimize air contamination and enhance uniform gas flow

    Science.gov (United States)

    Ruppe, E. P.

    1966-01-01

    Brazing retort manifold minimizes air contamination, prevents gas entrapment during purging, and provides uniform gas flow into the retort bell. The manifold is easily cleaned and turbulence within the bell is minimized because all manifold construction lies outside the main enclosure.

  9. Experimental study of swirl flow patterns in Gas Conditioning Tower at various entry conditions

    DEFF Research Database (Denmark)

    Jinov, Andrei A.; Larsen, Poul Scheel

    1999-01-01

    In a gas conditioning tower hot flue gas with relatively high dust loads is cooled by injecting water spray near the top. For satisfactory operation wet particles should be kept off walls and all water should have evaporated to yield a uniformly cooled flow before it reaches the bottom of the tower...

  10. The reactive solid-gas flow of a fluidized bed for UO2 conversion

    International Nuclear Information System (INIS)

    Juanico, L.E.

    1991-01-01

    The reactive solid-gas flow of a fluidized bed for UO 2 conversion was modeled. The sedimentation-reaction process was treated using the drift-flux equations. Also, the associated pressure transient due to the reaction gas release was analyzed. An experiment was carried out to compare the results, and pressure transient was numerically simulated, reaching interesting conclusions. (Author) [es

  11. Heat and momentum transfer in a gas coolant flow through a circular pipe in a high temperature gas cooled reactor

    International Nuclear Information System (INIS)

    Ogawa, Masuro

    1989-07-01

    In Japan Atomic Energy Research Institute (JAERI), a very high temperature gas cooled reactor (VHTR) has been researched and developed with a purpose of attaining a coolant temperature of around 1000degC at the reactor outlet. In order to design VHTR, comprehensive knowledge is required on thermo-hydraulic characteristics of laminar-turbulent transition, of coolant flow with large thermal property variation due to temperature difference, and of heat transfer deterioration. In the present investigation, experimental and analytical studies are made on a gas flow in a circular tube to elucidate the thermo-hydraulic characteristics. Friction factors and heat transfer coefficients in transitional flows are obtained. Influence of thermal property variation on the friction factor is qualitatively determined. Heat transfer deterioration in the turbulent flow subjected to intense heating is experimentally found to be caused by flow laminarization. The analysis based on a k-kL two-equation model of turbulence predicts well the experimental results on friction factors and heat transfer coefficients in flows with thermal property variation and in laminarizing flows. (author)

  12. Confined dense particle-gas flow, application to nuclear fuel relocation

    International Nuclear Information System (INIS)

    Martin, A.

    2010-02-01

    In this work, we investigate particle-gas two-phase flows in the jamming regime where the flow stops in finite time. In this regime, which occurs quite often in nature and industrial applications, the flow is stochastic and needs therefore to be characterized by the jamming probability as well as the flow rate and its fluctuations that depend on the confining geometry, granular microstructure and gas properties. We developed a numerical approach based on the coupling of the Non Smooth Contact Dynamics for the solid phase and a mesoscopic method for the gas phase. We find that the flow rate as a function of the opening is well fit by a power law in agreement with reported experimental data. The presence of a gas affects only the mean flow rate, the flow statistics being sensibly the same as in the absence of the gas. We apply our quantitative statistical results in order to estimate the relocation rate of fragmented nuclear fuel inside its cladding tube as a result of a local balloon caused by an accident (loss-of-coolant accident). (author)

  13. Magnetic resonance velocity imaging of liquid and gas two-phase flow in packed beds.

    Science.gov (United States)

    Sankey, M H; Holland, D J; Sederman, A J; Gladden, L F

    2009-02-01

    Single-phase liquid flow in porous media such as bead packs and model fixed bed reactors has been well studied by MRI. To some extent this early work represents the necessary preliminary research to address the more challenging problem of two-phase flow of gas and liquid within these systems. In this paper, we present images of both the gas and liquid velocities during stable liquid-gas flow of water and SF(6) within a packing of 5mm spheres contained within columns of diameter 40 and 27 mm; images being acquired using (1)H and (19)F observation for the water and SF(6), respectively. Liquid and gas flow rates calculated from the velocity images are in agreement with macroscopic flow rate measurements to within 7% and 5%, respectively. In addition to the information obtained directly from these images, the ability to measure liquid and gas flow fields within the same sample environment will enable us to explore the validity of assumptions used in numerical modelling of two-phase flows.

  14. Effects of Biochar on the Net Greenhouse Gas Emissions under Continuous Flooding and Water-Saving Irrigation Conditions in Paddy Soils

    Directory of Open Access Journals (Sweden)

    Le Qi

    2018-05-01

    Full Text Available In this study, we investigated the greenhouse gas emission under different application of biochar in the conditions of continuous flooding and water-saving irrigation in paddy fields, whereas, plant and soil carbon sequestration were considered in the calculation of net greenhouse gas emissions. The emission rates of methane (CH4, carbon dioxide (CO2, and nitrous oxide (N2O gases were simultaneously monitored once every 7–10 days using the closed-chamber method. As a whole, the net greenhouse gas emission in the water-saving irrigation was more than that of the continuous flooding irrigation conditions. Compared with the water-saving irrigation, the continuous flooding irrigation significantly increased the CH4 in the control (CK and chemical fertilizer treatments (NPK. The CO2 emissions increased in each treatment of the water-saving irrigation condition, especially in the chemical fertilizer treatments (NPKFW. Similarly, the soil N2O emission was very sensitive to the water-saving irrigation condition. An interesting finding is that the biochar application in soils cut down the soil N2O emission more significantly than NPKFW in the water-saving irrigation condition while the effect of biochar increased under the continuous flooding irrigation condition.

  15. Oil and gas pipelines with hydrophobic surfaces better equipped to deal with gas hydrate flow assurance issues

    DEFF Research Database (Denmark)

    Perfeldt, Christine Malmos; Sharifi, Hassan; von Solms, Nicolas

    2015-01-01

    Gas hydrate deposition can cause plugging in oil and gas pipelines with resultant flow assurance challenges. Presently, the energy industry uses chemical additives in order to manage hydrate formation, however these chemicals are expensive and may be associated with safety and environmental...... concerns. Here we show the effect of a hydrophobically coated surface on hydrate formation in the presence of an antifreeze protein type I (AFP I) and a biodegradable synthetic polymer (LuvicapBio) in a high pressure crystallizer setup. The hydrophobic surface increased the hydrate induction time...... crystallizer. This indicates that 10 to 14 times less KHI is needed in the presence of a hydrophobically coated surface. These experimental studies suggest that the use of hydrophobic surfaces or pipelines could serve as an alternative or additional flow assurance approach for gas hydration mitigation...

  16. Random walk-percolation-based modeling of two-phase flow in porous media: Breakthrough time and net to gross ratio estimation

    Science.gov (United States)

    Ganjeh-Ghazvini, Mostafa; Masihi, Mohsen; Ghaedi, Mojtaba

    2014-07-01

    Fluid flow modeling in porous media has many applications in waste treatment, hydrology and petroleum engineering. In any geological model, flow behavior is controlled by multiple properties. These properties must be known in advance of common flow simulations. When uncertainties are present, deterministic modeling often produces poor results. Percolation and Random Walk (RW) methods have recently been used in flow modeling. Their stochastic basis is useful in dealing with uncertainty problems. They are also useful in finding the relationship between porous media descriptions and flow behavior. This paper employs a simple methodology based on random walk and percolation techniques. The method is applied to a well-defined model reservoir in which the breakthrough time distributions are estimated. The results of this method and the conventional simulation are then compared. The effect of the net to gross ratio on the breakthrough time distribution is studied in terms of Shannon entropy. Use of the entropy plot allows one to assign the appropriate net to gross ratio to any porous medium.

  17. Direct numerical simulations of gas-liquid multiphase flows

    CERN Document Server

    Tryggvason, Grétar; Zaleski, Stéphane

    2011-01-01

    Accurately predicting the behaviour of multiphase flows is a problem of immense industrial and scientific interest. Modern computers can now study the dynamics in great detail and these simulations yield unprecedented insight. This book provides a comprehensive introduction to direct numerical simulations of multiphase flows for researchers and graduate students. After a brief overview of the context and history the authors review the governing equations. A particular emphasis is placed on the 'one-fluid' formulation where a single set of equations is used to describe the entire flow field and

  18. Multicomponent gas flow computations by a discontinuous Galerkin scheme using L2-projection of perfect gas EOS

    Science.gov (United States)

    Franchina, N.; Savini, M.; Bassi, F.

    2016-06-01

    A new formulation of multicomponent gas flow computation, suited to a discontinuous Galerkin discretization, is here presented and discussed. The original key feature is the use of L2-projection form of the (perfect gas) equation of state that allows all thermodynamic variables to span the same functional space. This choice greatly mitigates problems encountered by the front-capturing schemes in computing discontinuous flow field, retaining at the same time their conservation properties at the discrete level and ease of use. This new approach, combined with an original residual-based artificial dissipation technique, shows itself capable, through a series of tests illustrated in the paper, to both control the spurious oscillations of flow variables occurring in high-order accurate computations and reduce them increasing the degree of the polynomial representation of the solution. This result is of great importance in computing reacting gaseous flows, where the local accuracy of temperature and species mass fractions is crucial to the correct evaluation of the chemical source terms contained in the equations, even if the presence of the physical diffusivities somewhat brings relief to these problems. The present work can therefore also be considered, among many others already presented in the literature, as the authors' first step toward the construction of a new discontinuous Galerkin scheme for reacting gas mixture flows.

  19. A study on nuclear heat load tolerable for NET/TF coils cooled by internal flow of helium II

    International Nuclear Information System (INIS)

    Hofmann, A.

    1988-02-01

    NbTi cables cooled by internal flow of superfluid helium are considered an option for the design of NET/TF coils with about 11 T peak fields. Starting from an available winding cross section of 0.61x0.61 m 2 for a 8 MA turns coil made of a 16 kA conductor it is shown that sufficient hydraulic cross section can be provided within such cables to remove the expected thermal load resulting from nuclear heating with exponential decay from inboard to outboard side of the winding. The concept is a pancake type coil with 1.8 K helium fed-in the high field region of each pancake. The temperature distribution within such coils is calculated, and the local safety margin is determined from temperature and field. The calculation takes account of nuclear and a.c. heating, and of thermal conductance between the individual layers and the coil casing. It is shown that operation with 1.8 K inlet and about 3 K outlet temperature is possible. The electrical insulation with about 0.5 mm thickness proves to provide sufficient thermal insulation. No additional thermal shield is required between the coil casing and the winding package. Two different types of conductors are being considered: a) POLO type cable with quadratic cross section and a central circular coolant duct, and b) an LCT type cable with two conductors wound in hand. Both concepts with about 500 m length of the cooland channels are shown to meet the requirements resulting from a peak nuclear heat load of 0.3 mW/cm 3 in the inboard turns. The hydraulic diameters are sufficient to operate each coils with self-sustained fountain effect pumps. Even appreciably higher heat loads with up to 3 mW/cm 3 of nuclear heating can be tolerated for the POLO type cable when the hydraulic diameter is enlarged to its maximum of 17 mm. (orig.) [de

  20. Net sputtering rate due to hot ions in a Ne-Xe discharge gas bombarding an MgO layer

    International Nuclear Information System (INIS)

    Ho, S.; Tamakoshi, T.; Ikeda, M.; Mikami, Y.; Suzuki, K.

    2011-01-01

    An analytical method is developed for determining net sputtering rate for an MgO layer under hot ions with low energy ( h i , above a threshold energy of sputtering, E th,i , multiplied by a yield coefficient. The threshold energy of sputtering is determined from dissociation energy required to remove an atom from MgO surface multiplied by an energy-transfer coefficient. The re-deposition rate of the sputtered atoms is calculated by a diffusion simulation using a hybridized probabilistic and analytical method. These calculation methods are combined to analyze the net sputtering rate. Maximum net sputtering rate due to the hot neon ions increases above the partial pressure of 4% xenon as E h Ne becomes higher and decreases near the partial pressure of 20% xenon as ion flux of neon decreases. The dependence due to the hot neon ions on partial pressure and applied voltage agrees well with experimental results, but the dependence due to the hot xenon ions deviates considerably. This result shows that the net sputtering rate is dominated by the hot neon ions. Maximum E h Ne (E h Ne,max = 5.3 - 10.3 eV) is lower than E th,Ne (19.5 eV) for the MgO layer; therefore, weak sputtering due to the hot neon ions takes place. One hot neon ion sputters each magnesium and each oxygen atom on the surface and distorts around a vacancy. The ratio of the maximum net sputtering rate is approximately determined by number of the ions at E h i,max multiplied by an exponential factor of -E th,i /E h i,max .

  1. Droplets in annular-dispersed gas-liquid pipe-flows

    NARCIS (Netherlands)

    Van 't Westende, J.M.C.

    2008-01-01

    Annular-dispersed gas-liquid pipe-flows are commonly encountered in many industrial applications, and have already been studied for many decades. However, due to the great complexity of this type of flow, there are still many phenomena that are poorly understood. The aim of this thesis is to shed

  2. Interstellar Gas Flow Vector and Temperature Determination over 5 Years of IBEX Observations

    International Nuclear Information System (INIS)

    Möbius, E; Heirtzler, D; Kucharek, H; Lee, M A; Leonard, T; Schwadron, N; Bzowski, M; Kubiak, M A; Sokół, J M; Fuselier, S A; McComas, D J; Wurz, P

    2015-01-01

    The Interstellar Boundary Explorer (IBEX) observes the interstellar neutral gas flow trajectories at their perihelion in Earth's orbit every year from December through early April, when the Earth's orbital motion is into the oncoming flow. These observations have defined a narrow region of possible, but very tightly coupled interstellar neutral flow parameters, with inflow speed, latitude, and temperature as well-defined functions of inflow longitude. The best- fit flow vector is different by ≈ 3° and lower by ≈ 3 km/s than obtained previously with Ulysses GAS, but the temperature is comparable. The possible coupled parameter space reaches to the previous flow vector, but only for a substantially higher temperature (by ≈ 2000 K). Along with recent pickup ion observations and including historical observations of the interstellar gas, these findings have led to a discussion, whether the interstellar gas flow into the solar system has been stable or variable over time. These intriguing possibilities call for more detailed analysis and a longer database. IBEX has accumulated observations over six interstellar flow seasons. We review key observations and refinements in the analysis, in particular, towards narrowing the uncertainties in the temperature determination. We also address ongoing attempts to optimize the flow vector determination through varying the IBEX spacecraft pointing and discuss related implications for the local interstellar cloud and its interaction with the heliosphere

  3. Non-equilibrium reacting gas flows kinetic theory of transport and relaxation processes

    CERN Document Server

    Nagnibeda, Ekaterina; Nagnibeda, Ekaterina

    2009-01-01

    This volume develops the kinetic theory of transport phenomena and relaxation processes in the flows of reacting gas mixtures. The theory is applied to the modeling of non-equilibrium flows behind strong shock waves, in the boundary layer, and in nozzles.

  4. MEMBRANOUS FLOWS IN GAS-LIQUID COLLECTORS-REGENERATORS OF SOLAR ABSORPTIVE SYSTEMS FEATURES

    Directory of Open Access Journals (Sweden)

    Doroshenko А.V.

    2009-12-01

    Full Text Available Article is devoted to the creation of new generation of solar collectors of the gas-liquid type, intended for use in alternative refrigerating and conditioning systems of drying-evaporating type with direct solar regeneration of absorbent. Special attention is given to the study of membranous flows features on inclined surfaces, including questions of such flows stability.

  5. Impact of meteorological parameters on extracted landfill gas composition and flow

    DEFF Research Database (Denmark)

    Fathi Aghdam, Ehsan; Scheutz, Charlotte; Kjeldsen, Peter

    2018-01-01

    The objective of this study was to investigate the impact of four pre-selected meteorological parameters (barometric pressure, wind speed, ambient temperature and solar radiation) on recovered landfill gas (LFG) flow, methane (CH4) content of the LFG and the recovered CH4 flow by performing...

  6. Model for radial gas fraction profiles in vertical pipe flow

    International Nuclear Information System (INIS)

    Lucas, D.; Krepper, E.; Prasser, H.M.

    2001-01-01

    A one-dimensional model is presented, which predicts the radial volume fraction profiles from a given bubble size distribution. It bases on the assumption of an equilibrium of the forces acting on a bubble perpendicularly to the flow path (non drag forces). For the prediction of the flow pattern this model could be used within an procedure together with appropriate models for local bubble coalescence and break-up. (orig.)

  7. Gas flow environmental and heat transfer nonrotating 3D program

    Science.gov (United States)

    Geil, T.; Steinhoff, J.

    1983-01-01

    A complete set of benchmark quality data for the flow and heat transfer within a large rectangular turning duct is being compiled. These data will be used to evaluate and verify three dimensional internal viscous flow models and computational codes. The analytical objective is to select such a computational code and define the capabilities of this code to predict the experimental results. Details of the proper code operation will be defined and improvements to the code modeling capabilities will be formulated.

  8. Experimental investigation of two-phase gas-liquid flow in microchannel with T-junction

    Science.gov (United States)

    Bartkus, German; Kozulin, Igor; Kuznetsov, Vladimir

    2017-10-01

    Using high-speed video recording and the method of dual laser scanning the gas-liquid flow was investigated in rectangular microchannels with an aspect ratio of 2.35 and 1.26. Experiments were earned out for the vertical flow of ethanol-nitrogen mixture in a microchannel with a cross section of 553×235 µm and for the horizontal flow of water-nitrogen mixture in a microchannel with a cross section of 315×250 µm. The T-mixer was used at the channel's inlet for gas-liquid flow formation. It was observed that elongated bubble, transition, and annular flows are the main regimes for a microchannel with a hydraulic diameter substantially less than the capillary constant. Using laser scanning, the maps of flow regimes for ethanol-nitrogen and water-nitrogen mixtures were obtained and discussed.

  9. Active bypass flow control for a seal in a gas turbine engine

    Science.gov (United States)

    Ebert, Todd A.; Kimmel, Keith D.

    2017-03-14

    An active bypass flow control system for controlling bypass compressed air based upon leakage flow of compressed air flowing past an outer balance seal between a stator and rotor of a first stage of a gas turbine in a gas turbine engine is disclosed. The active bypass flow control system is an adjustable system in which one or more metering devices may be used to control the flow of bypass compressed air as the flow of compressed air past the outer balance seal changes over time as the outer balance seal between the rim cavity and the cooling cavity wears In at least one embodiment, the metering device may include an annular ring having at least one metering orifice extending therethrough, whereby alignment of the metering orifice with the outlet may be adjustable to change a cross-sectional area of an opening of aligned portions of the outlet and the metering orifice.

  10. Numerical and experimental modelling of back stream flow during close-coupled gas atomization

    OpenAIRE

    Motaman, S; Mullis, AM; Borman, DJ; Cochrane, RF; McCarthy, IN

    2013-01-01

    This paper reports the numerical and experimental investigation into the effects of different gas jet mis-match angles (for an external melt nozzle wall) on the back-stream flow in close coupled gas atomization. The Pulse Laser Imaging (PLI) technique was applied for visualising the back-stream melt flow phenomena with an analogue water atomizer and the associated PLI images compared with numerical results. In the investigation a Convergent–Divergent (C–D) discrete gas jet die at five differe...

  11. Liquid metal cooled blanket concept for NET

    International Nuclear Information System (INIS)

    Malang, S.; Casal, V.; Arheidt, K.; Fischer, U.; Link, W.; Rust, K.

    1986-01-01

    A blanket concept for NET using liquid lithium-lead both as breeder material and as coolant is described. The need for inboard breeding is avoided by using beryllium as neutron multiplier in the outboard blanket. Novel flow channel inserts are employed in all poloidal ducts to reduce the MHD pressure drop. The concept offers a simple mechanical design and a higher tritium breeding ratio compared to water- and gas-cooled blankets. (author)

  12. Viscous-shock-layer solutions for turbulent flow of radiating gas mixtures in chemical equilibrium

    Science.gov (United States)

    Anderson, E. C.; Moss, J. N.

    1975-01-01

    The viscous-shock-layer equations for hypersonic laminar and turbulent flows of radiating or nonradiating gas mixtures in chemical equilibrium are presented for two-dimensional and axially-symmetric flow fields. Solutions were obtained using an implicit finite-difference scheme and results are presented for hypersonic flow over spherically-blunted cone configurations at freestream conditions representative of entry into the atmosphere of Venus. These data are compared with solutions obtained using other methods of analysis.

  13. Viscous shock layer solutions for turbulent flow of radiating gas mixtures in chemical equilibrium

    Science.gov (United States)

    Anderson, E. C.; Moss, J. N.

    1975-01-01

    The viscous shock layer equations for hypersonic laminar and turbulent flows of radiating or nonradiating gas mixtures in chemical equilibrium are presented for two-dimensional and axially symmetric flow fields. Solutions are obtained using an implicit finite difference scheme and results are presented for hypersonic flow over spherically blunted cone configurations at free stream conditions representative of entry into the atmosphere of Venus. These data are compared with solutions obtained using other methods of analysis.

  14. Simulation of neutral gas flow in a tokamak divertor using the Direct Simulation Monte Carlo method

    International Nuclear Information System (INIS)

    Gleason-González, Cristian; Varoutis, Stylianos; Hauer, Volker; Day, Christian

    2014-01-01

    Highlights: • Subdivertor gas flows calculations in tokamaks by coupling the B2-EIRENE and DSMC method. • The results include pressure, temperature, bulk velocity and particle fluxes in the subdivertor. • Gas recirculation effect towards the plasma chamber through the vertical targets is found. • Comparison between DSMC and the ITERVAC code reveals a very good agreement. - Abstract: This paper presents a new innovative scientific and engineering approach for describing sub-divertor gas flows of fusion devices by coupling the B2-EIRENE (SOLPS) code and the Direct Simulation Monte Carlo (DSMC) method. The present study exemplifies this with a computational investigation of neutral gas flow in the ITER's sub-divertor region. The numerical results include the flow fields and contours of the overall quantities of practical interest such as the pressure, the temperature and the bulk velocity assuming helium as model gas. Moreover, the study unravels the gas recirculation effect located behind the vertical targets, viz. neutral particles flowing towards the plasma chamber. Comparison between calculations performed by the DSMC method and the ITERVAC code reveals a very good agreement along the main sub-divertor ducts

  15. Triboelectric-based harvesting of gas flow energy and powerless sensing applications

    Energy Technology Data Exchange (ETDEWEB)

    Taghavi, Majid, E-mail: majid.taghavi@iit.it [Micro-BioRobotics Center, Istituto Italiano di Tecnologia, Pontedera (Italy); Biorobotics Institute, Scuola Superiore Sant’Anna, Pontedera, Pisa (Italy); Sadeghi, Ali; Mazzolai, Barbara [Micro-BioRobotics Center, Istituto Italiano di Tecnologia, Pontedera (Italy); Beccai, Lucia, E-mail: lucia.beccai@iit.it [Micro-BioRobotics Center, Istituto Italiano di Tecnologia, Pontedera (Italy); Mattoli, Virgilio, E-mail: virgilio.mattoli@iit.it [Micro-BioRobotics Center, Istituto Italiano di Tecnologia, Pontedera (Italy)

    2014-12-30

    Highlights: • The mechanical energy of both pure and impure gases can be harvested by the introduced system. • The blown gas vibrates a non conductive sheet between two surfaces, generating the triboelectric charges. • The system is able to measure the flow rate of the blown gas. • The existence of dust in the blown air can be detected without external powering. • A self powered smoke detector is introduced. - Abstract: In this work, we propose an approach that can convert gas flow energy to electric energy by using the triboelectric effect, in a structure integrating at least two conductive parts (i.e. electrodes) and one non-conductive sheet. The gas flow induces vibration of the cited parts. Therefore, the frequent attaching and releasing between a non-conductive layer with at least one electrode generates electrostatic charges on the surfaces, and then an electron flow between the two electrodes. The effect of blown gas on the output signals is studied to evaluate the gas flow sensing. We also illustrate that the introduced system has an ability to detect micro particles driven by air into the system. Finally we show how we can use this approach for a self sustainable system demonstrating smoke detection and LED lightening.

  16. Triboelectric-based harvesting of gas flow energy and powerless sensing applications

    International Nuclear Information System (INIS)

    Taghavi, Majid; Sadeghi, Ali; Mazzolai, Barbara; Beccai, Lucia; Mattoli, Virgilio

    2014-01-01

    Highlights: • The mechanical energy of both pure and impure gases can be harvested by the introduced system. • The blown gas vibrates a non conductive sheet between two surfaces, generating the triboelectric charges. • The system is able to measure the flow rate of the blown gas. • The existence of dust in the blown air can be detected without external powering. • A self powered smoke detector is introduced. - Abstract: In this work, we propose an approach that can convert gas flow energy to electric energy by using the triboelectric effect, in a structure integrating at least two conductive parts (i.e. electrodes) and one non-conductive sheet. The gas flow induces vibration of the cited parts. Therefore, the frequent attaching and releasing between a non-conductive layer with at least one electrode generates electrostatic charges on the surfaces, and then an electron flow between the two electrodes. The effect of blown gas on the output signals is studied to evaluate the gas flow sensing. We also illustrate that the introduced system has an ability to detect micro particles driven by air into the system. Finally we show how we can use this approach for a self sustainable system demonstrating smoke detection and LED lightening

  17. Predicting the Agglomeration of Cohesive Particles in a Gas-Solid Flow and its Effect on the Solids Flow

    Science.gov (United States)

    Kellogg, Kevin; Liu, Peiyuan; Lamarche, Casey; Hrenya, Christine

    2017-11-01

    In flows of cohesive particles, agglomerates will readily form and break. These agglomerates are expected to complicate how particles interact with the surrounding fluid in multiphase flows, and consequently how the solids flow. In this work, a dilute flow of particles driven by gas against gravity is studied. A continuum framework, composed of a population balance to predict the formation of agglomerates, and kinetic-theory-based balances, is used to predict the flow of particles. The closures utilized for the birth and death rates due to aggregation and breakage in the population balance take into account how the impact velocity (the granular temperature) affects the outcome of a collision as aggregation, rebound, or breakage. The agglomerate size distribution and solids velocity predicted by the continuum framework are compared to discrete element method (DEM) simulations, as well to experimental results of particles being entrained from the riser of a fluidized bed. Dow Corning Corporation.

  18. Simulation of granular and gas-solid flows using discrete element method

    Science.gov (United States)

    Boyalakuntla, Dhanunjay S.

    2003-10-01

    In recent years there has been increased research activity in the experimental and numerical study of gas-solid flows. Flows of this type have numerous applications in the energy, pharmaceuticals, and chemicals process industries. Typical applications include pulverized coal combustion, flow and heat transfer in bubbling and circulating fluidized beds, hopper and chute flows, pneumatic transport of pharmaceutical powders and pellets, and many more. The present work addresses the study of gas-solid flows using computational fluid dynamics (CFD) techniques and discrete element simulation methods (DES) combined. Many previous studies of coupled gas-solid flows have been performed assuming the solid phase as a continuum with averaged properties and treating the gas-solid flow as constituting of interpenetrating continua. Instead, in the present work, the gas phase flow is simulated using continuum theory and the solid phase flow is simulated using DES. DES treats each solid particle individually, thus accounting for its dynamics due to particle-particle interactions, particle-wall interactions as well as fluid drag and buoyancy. The present work involves developing efficient DES methods for dense granular flow and coupling this simulation to continuum simulations of the gas phase flow. Simulations have been performed to observe pure granular behavior in vibrating beds. Benchmark cases have been simulated and the results obtained match the published literature. The dimensionless acceleration amplitude and the bed height are the parameters governing bed behavior. Various interesting behaviors such as heaping, round and cusp surface standing waves, as well as kinks, have been observed for different values of the acceleration amplitude for a given bed height. Furthermore, binary granular mixtures (granular mixtures with two particle sizes) in a vibrated bed have also been studied. Gas-solid flow simulations have been performed to study fluidized beds. Benchmark 2D

  19. Effect of swirling device on flow behavior in a supersonic separator for natural gas dehydration

    DEFF Research Database (Denmark)

    Wen, Chuang; Li, Anqi; Walther, Jens Honore

    2016-01-01

    is designed for an annular supersonic separator. The supersonic swirling separation flow of natural gas is calculated using the Reynolds Stress model. The results show that the viscous heating and strong swirling flow cause the adverse pressure in the annular channel, which may negatively affect......The supersonic separator is a revolutionary device to remove the condensable components from gas mixtures. One of the key issues for this novel technology is the complex supersonic swirling flow that is not well understood. A swirling device composed of an ellipsoid and several helical blades...

  20. High temperature, high pressure gas loop - the Component Flow Test Loop (CFTL)

    International Nuclear Information System (INIS)

    Gat, U.; Sanders, J.P.; Young, H.C.

    1984-01-01

    The high-pressure, high-temperature, gas-circulating Component Flow Test Loop located at Oak Ridge National Laboratory was designed and constructed utilizing Section III of the ASME Boiler and Pressure Vessel Code. The quality assurance program for operating and testing is also based on applicable ASME standards. Power to a total of 5 MW is available to the test section, and an air-cooled heat exchanger rated at 4.4 MW serves as heat sink. The three gas-bearing, completely enclosed gas circulators provide a maximum flow of 0.47 m 3 /s at pressures to 10.7 MPa. The control system allows for fast transients in pressure, power, temperature, and flow; it also supports prolonged unattended steady-state operation. The data acquisition system can access and process 10,000 data points per second. High-temperature gas-cooled reactor components are being tested

  1. Methods and systems for detecting gas flow by photoacoustic signal generation

    Science.gov (United States)

    Choudhury, Niloy; Challener, William Albert

    2018-03-06

    A method for the detection of a gas flowing from a location in a structure is described. A hollow-core optical fiber is placed in a position adjacent the structure. The fiber includes a sound-conductive cladding layer; and further includes at least one aperture extending into its cross-sectional diameter. A beam of pulsed, optical is transmitted into the fiber with a tunable laser. The optical energy is characterized by a wavelength that can be absorbed by the gas that flows into the fiber through the aperture. This causes a temperature fluctuation in the region of gas absorption, which in turn generates an acoustic wave in the absorption region. The acoustic wave travels through the cladding layer, and can be detected with a microphone, so as to provide the location of gas flow, based on the recorded position and movement of the acoustic wave. A related system is also described.

  2. Cooling of a microchannel with thin evaporating liquid film sheared by dry gas flow

    Science.gov (United States)

    Kabova, Yu O.; Kuznetsov, V. V.

    2017-11-01

    A joint motion of thin liquid film and dry gas in a microchannel is investigated numerically at different values of initial concentration of the liquid vapor in the gas phase, taking into account the evaporation process. Major factors affecting the temperature distribution in the liquid and the gas phases are as follows: transfer of heat by liquid and gas flows, heat loses due to evaporation, diffusion heat exchange. Comparisons of the numerical results for the case of the dry gas and for the case of equilibrium concentration of vapor in the gas have been carried out. It is shown that use of dry gas enhances the heat dissipation from the heater. It is found out that not only intense evaporation occurs near the heating areas, but also in both cases vapor condensation takes place below the heater in streamwise direction.

  3. Flow structure of conical distributed multiple gas jets injected into a water chamber

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jiajun; Yu, Yonggang [Nanjing University of Science and Technology, Nanjing (China)

    2017-04-15

    Based on an underwater gun firing project, a mock bullet with several holes on the head was designed and experimented to observe the combustion gas injected into a cylindrical water chamber through this mock bullet. The combustion gas jets contain one vertical central jet and 4 to 8 slant lateral jets. A high speed camera system was used to record the expansion of gas jets in the experimental study. In numerical simulations, the Euler two-fluid model and volume of fluid method were adopted to describe the gas-liquid flow. The results show the backflow zone in lateral jet is the main factor influencing the gas-liquid turbulent mixing in downstream. On cross sections, the gas volume fraction increased with time but the growth rate decreased. With a change of nozzle structure, the gas fraction was more affected than the shock structure.

  4. The characteristics of heat flow in the Shenhu gas hydrate drilling area, northern South China Sea

    Science.gov (United States)

    Xu, Xing; Wan, Zhifeng; Wang, Xianqing; Sun, Yuefeng; Xia, Bin

    2016-12-01

    Marine heat flow is of great significance for the formation and occurrence of seabed oil, gas and gas hydrate resources. Geothermal gradient is an important parameter in determining the thickness of the hydrate stability zone. The northern slope of the South China Sea is rich in gas hydrate resources. Several borehole drilling attempts were successful in finding hydrates in the Shenhu area, while others were not. The failures demand further study on the distribution regularities of heat flow and its controlling effects on hydrate occurrence. In this study, forty-eight heat flow measurements are analyzed in the Shenhu gas hydrate drilling area, located in the northern South China Sea, together with their relationship to topography, sedimentary environment and tectonic setting. Canyons are well developed in the study area, caused mainly by the development of faults, faster sediment supply and slumping of the Pearl River Estuary since the late Miocene in the northern South China Sea. The heat flow values in grooves, occurring always in fault zones, are higher than those of ridges. Additionally, the heat flow values gradually increase from the inner fan, to the middle fan, to the external fan subfacies. The locations with low heat flow such as ridges, locations away from faults and the middle fan subfacies, are more conducive to gas hydrate occurrence.

  5. Optimization of Gas Flow Network using the Traveling Salesman ...

    African Journals Online (AJOL)

    The overall goal of this paper is to develop a general formulation for an optimal infrastructure layout design of gas pipeline distribution networks using algorithm developed from the application of two industrial engineering concepts: the traveling salesman problem (TSP) and the nearest neighbor (NN). The focus is on the ...

  6. Statistic characteristics of the gas-liquid flow in a vertical minichannel

    Science.gov (United States)

    Kozulin, I. A.; Kuznetsov, V. V.

    2010-03-01

    The gas-liquid upward flow was studied in a rectangular minichannel of 1.75×3.8 mm and length of 0.7 m. The experiments were carried out within the range of the gas superficial velocity from 0.1 to 10 m/s and the liquid superficial velocity from 0.07 to 0.7 m/s for the co-current H2O/CO2 flow under the conditions of saturation. The method for the two-beam laser scanning of structure and determination of statistic characteristics of the two-phase flow was worked through. The slug-bubble, slug, transitional, churn, and annular flows were distinguished. The statistics characteristics of liquid and gas phases motion in a minichannel were obtained for the first time including the velocities of phase motion.

  7. Operator splitting method for simulation of dynamic flows in natural gas pipeline networks

    Science.gov (United States)

    Dyachenko, Sergey A.; Zlotnik, Anatoly; Korotkevich, Alexander O.; Chertkov, Michael

    2017-12-01

    We develop an operator splitting method to simulate flows of isothermal compressible natural gas over transmission pipelines. The method solves a system of nonlinear hyperbolic partial differential equations (PDEs) of hydrodynamic type for mass flow and pressure on a metric graph, where turbulent losses of momentum are modeled by phenomenological Darcy-Weisbach friction. Mass flow balance is maintained through the boundary conditions at the network nodes, where natural gas is injected or withdrawn from the system. Gas flow through the network is controlled by compressors boosting pressure at the inlet of the adjoint pipe. Our operator splitting numerical scheme is unconditionally stable and it is second order accurate in space and time. The scheme is explicit, and it is formulated to work with general networks with loops. We test the scheme over range of regimes and network configurations, also comparing its performance with performance of two other state of the art implicit schemes.

  8. The effect of gas and fluid flows on nonlinear lateral vibrations of rotating drill strings

    Science.gov (United States)

    Khajiyeva, Lelya; Kudaibergenov, Askar; Kudaibergenov, Askat

    2018-06-01

    In this work we develop nonlinear mathematical models describing coupled lateral vibrations of a rotating drill string under the effect of external supersonic gas and internal fluid flows. An axial compressive load and a torque also affect the drill string. The mathematical models are derived by the use of Novozhilov's nonlinear theory of elasticity with implementation of Hamilton's variation principle. Expressions for the gas flow pressure are determined according to the piston theory. The fluid flow is considered as added mass inside the curved tube of the drill string. Using an algorithm developed in the Mathematica computation program on the basis of the Galerkin approach and the stiffness switching method the numerical solution of the obtained approximate differential equations is found. Influences of the external loads, drill string angular speed of rotation, parameters of the gas and fluid flows on the drill string vibrations are shown.

  9. Analysing Gas-Liquid Flow in PEM Electrolyser Micro-Channels (Poster)

    DEFF Research Database (Denmark)

    Lafmejani, Saeed Sadeghi; Olesen, Anders Christian; Kær, Søren Knudsen

    One means of increasing the hydrogen yield to cost ratio of a PEM water electrolyser, is to increase the operating current density. However, at high current densities (higher than 1 A/cm2), management of heat and mass transfer in the anode current collector and channel becomes crucial and can lead...... to hot spots. Management of heat and fluid flow through the micro-channels play a great role in the capability of PEM water electrolysis when working at high current densities. Despite, many studies have been done on gas-liquid flows; still there is a lack of research on gas-liquid flows in micro......-sized channels (hydraulic diameter of 1 mm) of PEM water electrolysis. Precisely controlling all the parameters that affect the gas-liquid flow in a PEM water electrolysis cell is quite challenging, hence a simplified setup is constructed consisting of only a transparent channel with a sheet of titanium felt...

  10. The effect of surfactant on stratified and stratifying gas-liquid flows

    Science.gov (United States)

    Heiles, Baptiste; Zadrazil, Ivan; Matar, Omar

    2013-11-01

    We consider the dynamics of a stratified/stratifying gas-liquid flow in horizontal tubes. This flow regime is characterised by the thin liquid films that drain under gravity along the pipe interior, forming a pool at the bottom of the tube, and the formation of large-amplitude waves at the gas-liquid interface. This regime is also accompanied by the detachment of droplets from the interface and their entrainment into the gas phase. We carry out an experimental study involving axial- and radial-view photography of the flow, in the presence and absence of surfactant. We show that the effect of surfactant is to reduce significantly the average diameter of the entrained droplets, through a tip-streaming mechanism. We also highlight the influence of surfactant on the characteristics of the interfacial waves, and the pressure gradient that drives the flow. EPSRC Programme Grant EP/K003976/1.

  11. Numerical simulation of gas-phonon coupling in thermal transpiration flows.

    Science.gov (United States)

    Guo, Xiaohui; Singh, Dhruv; Murthy, Jayathi; Alexeenko, Alina A

    2009-10-01

    Thermal transpiration is a rarefied gas flow driven by a wall temperature gradient and is a promising mechanism for gas pumping without moving parts, known as the Knudsen pump. Obtaining temperature measurements along capillary walls in a Knudsen pump is difficult due to extremely small length scales. Meanwhile, simplified analytical models are not applicable under the practical operating conditions of a thermal transpiration device, where the gas flow is in the transitional rarefied regime. Here, we present a coupled gas-phonon heat transfer and flow model to study a closed thermal transpiration system. Discretized Boltzmann equations are solved for molecular transport in the gas phase and phonon transport in the solid. The wall temperature distribution is the direct result of the interfacial coupling based on mass conservation and energy balance at gas-solid interfaces and is not specified a priori unlike in the previous modeling efforts. Capillary length scales of the order of phonon mean free path result in a smaller temperature gradient along the transpiration channel as compared to that predicted by the continuum solid-phase heat transfer. The effects of governing parameters such as thermal gradients, capillary geometry, gas and phonon Knudsen numbers and, gas-surface interaction parameters on the efficiency of thermal transpiration are investigated in light of the coupled model.

  12. Real-Gas Correction Factors for Hypersonic Flow Parameters in Helium

    Science.gov (United States)

    Erickson, Wayne D.

    1960-01-01

    The real-gas hypersonic flow parameters for helium have been calculated for stagnation temperatures from 0 F to 600 F and stagnation pressures up to 6,000 pounds per square inch absolute. The results of these calculations are presented in the form of simple correction factors which must be applied to the tabulated ideal-gas parameters. It has been shown that the deviations from the ideal-gas law which exist at high pressures may cause a corresponding significant error in the hypersonic flow parameters when calculated as an ideal gas. For example the ratio of the free-stream static to stagnation pressure as calculated from the thermodynamic properties of helium for a stagnation temperature of 80 F and pressure of 4,000 pounds per square inch absolute was found to be approximately 13 percent greater than that determined from the ideal-gas tabulation with a specific heat ratio of 5/3.

  13. Two-phase gas bubble-liquid boundary layer flow along vertical and inclined surfaces

    International Nuclear Information System (INIS)

    Cheung, F.B.; Epstein, M.

    1985-01-01

    The behavior of a two-phase gas bubble-liquid boundary layer along vertical and inclined porous surfaces with uniform gas injection is investigated experimentally and analytically. Using argon gas and water as the working fluids, a photographical study of the two-phase boundary layer flow has been performed for various angles of inclination ranging from 45 0 to 135 0 and gas injection rates ranging from 0.01 to 0.1 m/s. An integral method has been employed to solve the system of equations governing the two-phase motion. The effects of the gas injection rate and the angle of inclination on the growth of the boundary layer have been determined. The predicted boundary layer thickness is found to be in good agreement with the experimental results. The calculated axial liquid velocity and the void fraction in the two-phase region are also presented along with the observed flow behavior

  14. Prediction of gas volume fraction in fully-developed gas-liquid flow in a vertical pipe

    Energy Technology Data Exchange (ETDEWEB)

    Islam, A.S.M.A.; Adoo, N.A.; Bergstrom, D.J., E-mail: nana.adoo@usask.ca [University of Saskatchewan, Department of Mechanical Engineering, Saskatoon, SK (Canada); Wang, D.F. [Canadian Nuclear Laboratories, Chalk River, ON (Canada)

    2015-07-01

    An Eulerian-Eulerian two-fluid model has been implemented for the prediction of the gas volume fraction profile in turbulent upward gas-liquid flow in a vertical pipe. The two-fluid transport equations are discretized using the finite volume method and a low Reynolds number κ-ε turbulence model is used to predict the turbulence field for the liquid phase. The contribution to the effective turbulence by the gas phase is modeled by a bubble induced turbulent viscosity. For the fully-developed flow being considered, the gas volume fraction profile is calculated using the radial momentum balance for the bubble phase. The model potentially includes the effect of bubble size on the interphase forces and turbulence model. The results obtained are in good agreement with experimental data from the literature. The one-dimensional formulation being developed allows for the efficient assessment and further development of both turbulence and two-fluid models for multiphase flow applications in the nuclear industry. (author)

  15. Prediction of gas volume fraction in fully-developed gas-liquid flow in a vertical pipe

    International Nuclear Information System (INIS)

    Islam, A.S.M.A.; Adoo, N.A.; Bergstrom, D.J.; Wang, D.F.

    2015-01-01

    An Eulerian-Eulerian two-fluid model has been implemented for the prediction of the gas volume fraction profile in turbulent upward gas-liquid flow in a vertical pipe. The two-fluid transport equations are discretized using the finite volume method and a low Reynolds number κ-ε turbulence model is used to predict the turbulence field for the liquid phase. The contribution to the effective turbulence by the gas phase is modeled by a bubble induced turbulent viscosity. For the fully-developed flow being considered, the gas volume fraction profile is calculated using the radial momentum balance for the bubble phase. The model potentially includes the effect of bubble size on the interphase forces and turbulence model. The results obtained are in good agreement with experimental data from the literature. The one-dimensional formulation being developed allows for the efficient assessment and further development of both turbulence and two-fluid models for multiphase flow applications in the nuclear industry. (author)

  16. Numerical studies of rock-gas flow in Yucca Mountain; Yucca Mountain Site Characterization Project

    Energy Technology Data Exchange (ETDEWEB)

    Ross, B.; Amter, S.; Lu, Ning [Disposal Safety, Inc., Washington, DC (United States)

    1992-02-01

    A computer model (TGIF -- Thermal Gradient Induced Flow) of two-dimensional, steady-state rock-gas flow driven by temperature and humidity differences is described. The model solves for the ``fresh-water head,`` a concept that has been used in models of variable-density water flow but has not previously been applied to gas flow. With this approach, the model can accurately simulate the flows driven by small differences in temperature. The unsaturated tuffs of Yucca Mountain, Nevada, are being studied as a potential site for a repository for high-level nuclear waste. Using the TGIF model, preliminary calculations of rock-gas flow in Yucca Mountain are made for four east-west cross-sections through the mountain. Calculations are made for three repository temperatures and for several assumptions about a possible semi-confining layer above the repository. The gas-flow simulations are then used to calculate travel-time distributions for air and for radioactive carbon-14 dioxide from the repository to the ground surface.

  17. Comparison of electrical capacitance tomography and gamma densitometer measurement in viscous oil-gas flows

    Energy Technology Data Exchange (ETDEWEB)

    Archibong Eso, A.; Zhao, Yabin; Yeung, Hoi [Department of Offshore Process and Energy Systems Engineering, Cranfield University, Cranfield (United Kingdom)

    2014-04-11

    Multiphase flow is a common occurrence in industries such as nuclear, process, oil and gas, food and chemical. A prior knowledge of its features and characteristics is essential in the design, control and management of such processes due to its complex nature. Electrical Capacitance Tomography (ECT) and Gamma Densitometer (Gamma) are two promising approaches for multiphase visualization and characterization in process industries. In two phase oil and gas flow, ECT and Gamma are used in multiphase flow monitoring techniques due to their inherent simplicity, robustness, and an ability to withstand wide range of operational temperatures and pressures. High viscous oil (viscosity > 100 cP) is of interest because of its huge reserves, technological advances in its production and unlike conventional oil (oil viscosity < 100 cP) and gas flows where ECT and Gamma have been previously used, high viscous oil and gas flows comes with certain associated concerns which include; increased entrainment of gas bubbles dispersed in oil, shorter and more frequent slugs as well as oil film coatings on the walls of flowing conduits. This study aims to determine the suitability of both devices in the visualization and characterization of high-viscous oil and gas flow. Static tests are performed with both devices and liquid holdup measurements are obtained. Dynamic experiments were also conducted in a 1 and 3 inch facility at Cranfield University with a range of nominal viscosities (1000, 3000 and 7500 cP). Plug, slug and wavy annular flow patterns were identified by means of Probability Mass Function and time series analysis of the data acquired from Gamma and ECT devices with high speed camera used to validate the results. Measured Liquid holdups for both devices were also compared.

  18. Effects of flow rate and gas mixture on the welfare of weaned and neonate pigs during gas euthanasia.

    Science.gov (United States)

    Sadler, L J; Hagen, C D; Wang, C; Widowski, T M; Johnson, A K; Millman, S T

    2014-02-01

    The objectives of this study were to assess efficacy and welfare implications of gas euthanasia when applied to weaned and neonate pigs. Parameters associated with welfare, which were measured before loss of consciousness, included open-mouth breathing, ataxia, righting response, and escape attempts. Two age groups (weaned and neonate) were assessed in 9 gas treatments arranged in a 2 × 4 factorial design, with 2 gas types (CO2 = 100% CO2 and 50:50 = 50:50 CO2:argon) and 4 flow rates (box volume exchange/min: slow = 20%; medium = 35%; fast = 50%; prefill = prefilled followed by 20%) and a control treatment in which ambient air was passed through the box. Pig pairs (10/treatment) were placed in a modified Euthanex AgPro system (Euthanex Corp., Palmer, PA). Behavioral and physiological responses were observed directly and from video recordings for latency, duration, prevalence (percent of pigs affected), and frequency (number of occurrences/pig). Data were analyzed as linear mixed models or with a Cox proportional hazard model as appropriate. Piglet pair was the experimental unit. For the weaned pig, welfare was superior with CO2 relative to 50:50 within 1 or more flow rates on the basis of reduced duration of open-mouth breathing, duration of ataxia, frequency of escape attempts, and duration and frequency of righting response (P euthanasia. As such, a 50:50 CO2:argon gas mixture and slower flow rates should be avoided when euthanizing weaned or neonate pigs with gas methods. Neonate pigs succumb to the effects of gas euthanasia quicker than weaned pigs and display fewer signs of distress.

  19. Cellular properties of slug flow in vertical co-current gas-liquid flow: slug-churn transition

    International Nuclear Information System (INIS)

    Lusseyran, Francois

    1990-01-01

    This research thesis reports the study and description of the structure of a slug flow regime in a co-current vertical cylindrical duct, and the characterization and prediction of its transition towards a slug-churn (de-structured) regime. Flow physical mechanisms highlighted by the measurement of two important dynamics variables (wall friction and thickness of liquid films) are related to hypotheses of cellular models. The author first proposes an overview of slug flow regimes: theoretical steady and one-dimensional analysis, mass assessment equations of cellular models, application to the assessment of the flow rate and of the thickness of the film surrounding the gas slug. In the second part, the author addresses the slug flow regime transition towards the slug-churn regime: assessment of the evolution of flow dynamic properties, use of average wall friction analysis to obtain a relevant transition criterion. The third part presents experimental conditions, and measurement methods: conductometry for thickness measurement, polarography for wall friction measurement, and gas phase detection by using an optic barrier or optic fibres [fr

  20. Measurement of gas flow velocities by laser-induced gratings

    Energy Technology Data Exchange (ETDEWEB)

    Hemmerling, B; Stampanoni-Panariello, A [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Kozlov, A D.N. [General Physics Institute, Moscow (Russian Federation)

    1999-08-01

    Time resolved light scattering from laser-induced electrostrictive gratings was used for the determination of flow velocities in air at room temperature. By measuring the velocity profile across the width of a slit nozzle we demonstrated the high spatial resolution (about 200 mm) of this novel technique. (author) 3 figs., 1 ref.

  1. 40 CFR 86.120-94 - Gas meter or flow instrumentation calibration; particulate, methanol and formaldehyde measurement.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Gas meter or flow instrumentation... Procedures § 86.120-94 Gas meter or flow instrumentation calibration; particulate, methanol and formaldehyde measurement. (a) Sampling for particulate, methanol and formaldehyde emissions requires the use of gas meters...

  2. Flow chemistry: intelligent processing of gas-liquid transformations using a tube-in-tube reactor.

    Science.gov (United States)

    Brzozowski, Martin; O'Brien, Matthew; Ley, Steven V; Polyzos, Anastasios

    2015-02-17

    CONSPECTUS: The previous decade has witnessed the expeditious uptake of flow chemistry techniques in modern synthesis laboratories, and flow-based chemistry is poised to significantly impact our approach to chemical preparation. The advantages of moving from classical batch synthesis to flow mode, in order to address the limitations of traditional approaches, particularly within the context of organic synthesis are now well established. Flow chemistry methodology has led to measurable improvements in safety and reduced energy consumption and has enabled the expansion of available reaction conditions. Contributions from our own laboratories have focused on the establishment of flow chemistry methods to address challenges associated with the assembly of complex targets through the development of multistep methods employing supported reagents and in-line monitoring of reaction intermediates to ensure the delivery of high quality target compounds. Recently, flow chemistry approaches have addressed the challenges associated with reactions utilizing reactive gases in classical batch synthesis. The small volumes of microreactors ameliorate the hazards of high-pressure gas reactions and enable improved mixing with the liquid phase. Established strategies for gas-liquid reactions in flow have relied on plug-flow (or segmented flow) regimes in which the gas plugs are introduced to a liquid stream and dissolution of gas relies on interfacial contact of the gas bubble with the liquid phase. This approach confers limited control over gas concentration within the liquid phase and is unsuitable for multistep methods requiring heterogeneous catalysis or solid supported reagents. We have identified the use of a gas-permeable fluoropolymer, Teflon AF-2400, as a simple method of achieving efficient gas-liquid contact to afford homogeneous solutions of reactive gases in flow. The membrane permits the transport of a wide range of gases with significant control of the stoichiometry of

  3. The Effects of Rape Residue Mulching on Net Global Warming Potential and Greenhouse Gas Intensity from No-Tillage Paddy Fields

    Science.gov (United States)

    Zhang, Zhi-Sheng; Cao, Cou-Gui; Guo, Li-Jin; Li, Cheng-Fang

    2014-01-01

    A field experiment was conducted to provide a complete greenhouse gas (GHG) accounting for global warming potential (GWP), net GWP, and greenhouse gas intensity (GHGI) from no-tillage (NT) paddy fields with different amounts of oilseed rape residue mulch (0, 3000, 4000, and 6000 kg dry matter (DM) ha−1) during a rice-growing season after 3 years of oilseed rape-rice cultivation. Residue mulching treatments showed significantly more organic carbon (C) density for the 0–20 cm soil layer at harvesting than no residue treatment. During a rice-growing season, residue mulching treatments sequestered significantly more organic C from 687 kg C ha−1 season−1 to 1654 kg C ha−1 season−1 than no residue treatment. Residue mulching significantly increased emissions of CO2 and N2O but decreased CH4 emissions. Residue mulching treatments significantly increased GWP by 9–30% but significantly decreased net GWP by 33–71% and GHGI by 35–72% relative to no residue treatment. These results suggest that agricultural economic viability and GHG mitigation can be achieved simultaneously by residue mulching on NT paddy fields in central China. PMID:25140329

  4. The effects of rape residue mulching on net global warming potential and greenhouse gas intensity from no-tillage paddy fields.

    Science.gov (United States)

    Zhang, Zhi-Sheng; Cao, Cou-Gui; Guo, Li-Jin; Li, Cheng-Fang

    2014-01-01

    A field experiment was conducted to provide a complete greenhouse gas (GHG) accounting for global warming potential (GWP), net GWP, and greenhouse gas intensity (GHGI) from no-tillage (NT) paddy fields with different amounts of oilseed rape residue mulch (0, 3000, 4000, and 6000 kg dry matter (DM) ha(-1)) during a rice-growing season after 3 years of oilseed rape-rice cultivation. Residue mulching treatments showed significantly more organic carbon (C) density for the 0-20 cm soil layer at harvesting than no residue treatment. During a rice-growing season, residue mulching treatments sequestered significantly more organic C from 687 kg C ha(-1) season(-1) to 1654 kg C ha(-1) season(-1) than no residue treatment. Residue mulching significantly increased emissions of CO2 and N2O but decreased CH4 emissions. Residue mulching treatments significantly increased GWP by 9-30% but significantly decreased net GWP by 33-71% and GHGI by 35-72% relative to no residue treatment. These results suggest that agricultural economic viability and GHG mitigation can be achieved simultaneously by residue mulching on NT paddy fields in central China.

  5. Effect of ambient-level gas-phase peroxides on foliar injury, growth, and net photosynthesis in Japanese radish (Raphanus sativus)

    Energy Technology Data Exchange (ETDEWEB)

    Chen Xuan, E-mail: xuan66chen@yahoo.co.j [Chinese Research Academy of Environmental Science, No.8, Dayangfang, Anwai, Chaoyang District, Beijing 100012 (China); Aoki, Masatoshi [Faculty of Agriculture, Tokyo University of Agriculture and Technology, Saiwaicho 3-5-8, Fuchu-shi, Tokyo 183-8509 (Japan); Takami, Akinori [National Institute for Environmental Studies, Onogawa 16-2, Tsukuba-shi, Ibaraki 305-8506 (Japan); Chai Fahe [Chinese Research Academy of Environmental Science, No.8, Dayangfang, Anwai, Chaoyang District, Beijing 100012 (China); Hatakeyama, Shiro [Faculty of Agriculture, Tokyo University of Agriculture and Technology, Saiwaicho 3-5-8, Fuchu-shi, Tokyo 183-8509 (Japan)

    2010-05-15

    To investigate the effects of ambient-level gas-phase peroxides concurrent with O{sub 3} on foliar injury, photosynthesis, and biomass in herbaceous plants, we exposed Japanese radish (Raphanus sativus) to clean air, 50 ppb O{sub 3}, 100 ppb O{sub 3}, and 2-3 ppb peroxides + 50 ppb O{sub 3} in outdoor chambers. Compared with exposure to 100 ppb O{sub 3}, exposure to 2-3 ppb peroxides + 50 ppb O{sub 3} induced greater damage in foliar injury, net photosynthetic rates and biomass; the pattern of foliar injury and the cause of net photosynthetic rate reduction also differed from those occurring with O{sub 3} exposure alone. These results indicate for the first time that sub-ppb peroxides + 50 ppb O{sub 3} can cause more severe damage to plants than 100 ppb O{sub 3}, and that not only O{sub 3}, but also peroxides, could be contributing to the herbaceous plant damage and forest decline observed in Japan's air-polluted urban and remote mountains areas. - Ambient-level gas-phase peroxides coexisted with 50 ppb O{sub 3} may contribute to the herbaceous plants damage and forest decline observed in Japan.

  6. A low-power high-flow shape memory alloy wire gas microvalve

    International Nuclear Information System (INIS)

    Gradin, Henrik; Braun, Stefan; Stemme, Göran; Van der Wijngaart, Wouter; Clausi, Donato; Peirs, Jan; Reynaerts, Dominiek

    2012-01-01

    In this paper the use of shape memory alloy (SMA) wire actuators for high gas flow control is investigated. A theoretical model for effective gas flow control is presented and gate microvalve prototypes are fabricated. The SMA wire actuator demonstrates the robust flow control of more than 1600 sccm at a pressure drop of 200 kPa. The valve can be successfully switched at over 10 Hz and at an actuation power of 90 mW. Compared to the current state-of-the-art high-flow microvalves, the proposed solution benefits from a low-voltage actuator with low overall power consumption. This paper demonstrate that SMA wire actuators are well suited for high-pressurehigh-flow applications. (paper)

  7. Effect of gas temperature on flow rate characteristics of an averaging pitot tube type flow meter

    Energy Technology Data Exchange (ETDEWEB)

    Yeo, Seung Hwa; Lee, Su Ryong; Lee, Choong Hoon [Seoul National University of Science and Technology, Seoul (Korea, Republic of)

    2015-01-15

    The flow rate characteristics passing through an averaging Pitot tube (APT) while constantly controlling the flow temperature were studied through experiments and CFD simulations. At controlled temperatures of 25, 50, 75, and 100 .deg .C, the flow characteristics, in this case the upstream, downstream and static pressure at the APT flow meter probe, were measured as the flow rate was increased. The flow rate through the APT flow meter was represented using the H-parameter (hydraulic height) obtained by a combination of the differential pressure and the air density measured at the APT flow meter probe. Four types of H-parameters were defined depending on the specific combination. The flow rate and the upstream, downstream and static pressures measured at the APT flow meter while changing the H-parameters were simulated by means of CFD. The flow rate curves showed different features depending on which type of H-parameter was used. When using the constant air density value in a standard state to calculate the H-parameters, the flow rate increased linearly with the H-parameter and the slope of the flow rate curve according to the H-parameter increased as the controlled target air temperature was increased. When using different air density levels corresponding to each target air temperature to calculate the H-parameter, the slope of the flow rate curve according to the H-parameter was constant and the flow rate curve could be represented by a single line. The CFD simulation results were in good agreement with the experimental results. The CFD simulations were performed while increasing the air temperature to 1200 K. The CFD simulation results for high air temperatures were similar to those at the low temperature ranging from 25 to 100 .deg. C.

  8. Effect of gas temperature on flow rate characteristics of an averaging pitot tube type flow meter

    International Nuclear Information System (INIS)

    Yeo, Seung Hwa; Lee, Su Ryong; Lee, Choong Hoon

    2015-01-01

    The flow rate characteristics passing through an averaging Pitot tube (APT) while constantly controlling the flow temperature were studied through experiments and CFD simulations. At controlled temperatures of 25, 50, 75, and 100 .deg .C, the flow characteristics, in this case the upstream, downstream and static pressure at the APT flow meter probe, were measured as the flow rate was increased. The flow rate through the APT flow meter was represented using the H-parameter (hydraulic height) obtained by a combination of the differential pressure and the air density measured at the APT flow meter probe. Four types of H-parameters were defined depending on the specific combination. The flow rate and the upstream, downstream and static pressures measured at the APT flow meter while changing the H-parameters were simulated by means of CFD. The flow rate curves showed different features depending on which type of H-parameter was used. When using the constant air density value in a standard state to calculate the H-parameters, the flow rate increased linearly with the H-parameter and the slope of the flow rate curve according to the H-parameter increased as the controlled target air temperature was increased. When using different air density levels corresponding to each target air temperature to calculate the H-parameter, the slope of the flow rate curve according to the H-parameter was constant and the flow rate curve could be represented by a single line. The CFD simulation results were in good agreement with the experimental results. The CFD simulations were performed while increasing the air temperature to 1200 K. The CFD simulation results for high air temperatures were similar to those at the low temperature ranging from 25 to 100 .deg. C.

  9. Greenhouse gas emissions from different municipal solid waste management scenarios in China: Based on carbon and energy flow analysis.

    Science.gov (United States)

    Liu, Yili; Sun, Weixin; Liu, Jianguo

    2017-10-01

    Waste management is a major source of global greenhouse gas (GHG) emissions and many opportunities exist to reduce these emissions. To identify the GHG emissions from waste management in China, the characteristics of MSW and the current and future treatment management strategies, five typical management scenarios were modeled by EaseTech software following the principles of life cycle inventory and analyzed based on the carbon and energy flows. Due to the high organic fraction (50-70%) and moisture content (>50%) of Chinese municipal solid waste (MSW), the net GHG emissions in waste management had a significant difference from the developed countries. It was found that the poor landfill gas (LFG) collection efficiency and low carbon storage resulted landfilling with flaring and landfilling with biogas recovery scenarios were the largest GHG emissions (192 and 117 kgCO 2 -Eq/t, respectively). In contrast, incineration had the best energy recovery rate (19%), and, by grid emissions substitution, led to a substantial decrease in net GHG emissions (-124 kgCO 2 -Eq/t). Due to the high energy consumption in operation, the unavoidable leakage of CH 4 and N 2 O in treatment, and the further release of CH 4 in disposing of the digested residue or composted product, the scenarios with biological treatment of the organic fractions after sorting, such as composting or anaerobic digestion (AD), did not lead to the outstanding GHG reductions (emissions of 32 and -36 kgCO 2 -Eq/t, respectively) as expected. Copyright © 2017. Published by Elsevier Ltd.

  10. Modeling Impacts of Alternative Practices on Net Global Warming Potential and Greenhouse Gas Intensity from Rice–Wheat Annual Rotation in China

    Science.gov (United States)

    Wang, Jinyang; Zhang, Xiaolin; Liu, Yinglie; Pan, Xiaojian; Liu, Pingli; Chen, Zhaozhi; Huang, Taiqing; Xiong, Zhengqin

    2012-01-01

    Background Evaluating the net exchange of greenhouse gas (GHG) emissions in conjunction with soil carbon sequestration may give a comprehensive insight on the role of agricultural production in global warming. Materials and Methods Measured data of methane (CH4) and nitrous oxide (N2O) were utilized to test the applicability of the Denitrification and Decomposition (DNDC) model to a winter wheat – single rice rotation system in southern China. Six alternative scenarios were simulated against the baseline scenario to evaluate their long-term (45-year) impacts on net global warming potential (GWP) and greenhouse gas intensity (GHGI). Principal Results The simulated cumulative CH4 emissions fell within the statistical deviation ranges of the field data, with the exception of N2O emissions during rice-growing season and both gases from the control treatment. Sensitivity tests showed that both CH4 and N2O emissions were significantly affected by changes in both environmental factors and management practices. Compared with the baseline scenario, the long-term simulation had the following results: (1) high straw return and manure amendment scenarios greatly increased CH4 emissions, while other scenarios had similar CH4 emissions, (2) high inorganic N fertilizer increased N2O emissions while manure amendment and reduced inorganic N fertilizer scenarios decreased N2O emissions, (3) the mean annual soil organic carbon sequestration rates (SOCSR) under manure amendment, high straw return, and no-tillage scenarios averaged 0.20 t C ha−1 yr−1, being greater than other scenarios, and (4) the reduced inorganic N fertilizer scenario produced the least N loss from the system, while all the scenarios produced comparable grain yields. Conclusions In terms of net GWP and GHGI for the comprehensive assessment of climate change and crop production, reduced inorganic N fertilizer scenario followed by no-tillage scenario would be advocated for this specified cropping system. PMID

  11. Modeling impacts of alternative practices on net global warming potential and greenhouse gas intensity from rice-wheat annual rotation in China.

    Directory of Open Access Journals (Sweden)

    Jinyang Wang

    Full Text Available BACKGROUND: Evaluating the net exchange of greenhouse gas (GHG emissions in conjunction with soil carbon sequestration may give a comprehensive insight on the role of agricultural production in global warming. MATERIALS AND METHODS: Measured data of methane (CH(4 and nitrous oxide (N(2O were utilized to test the applicability of the Denitrification and Decomposition (DNDC model to a winter wheat - single rice rotation system in southern China. Six alternative scenarios were simulated against the baseline scenario to evaluate their long-term (45-year impacts on net global warming potential (GWP and greenhouse gas intensity (GHGI. PRINCIPAL RESULTS: The simulated cumulative CH(4 emissions fell within the statistical deviation ranges of the field data, with the exception of N(2O emissions during rice-growing season and both gases from the control treatment. Sensitivity tests showed that both CH(4 and N(2O emissions were significantly affected by changes in both environmental factors and management practices. Compared with the baseline scenario, the long-term simulation had the following results: (1 high straw return and manure amendment scenarios greatly increased CH(4 emissions, while other scenarios had similar CH(4 emissions, (2 high inorganic N fertilizer increased N(2O emissions while manure amendment and reduced inorganic N fertilizer scenarios decreased N(2O emissions, (3 the mean annual soil organic carbon sequestration rates (SOCSR under manure amendment, high straw return, and no-tillage scenarios averaged 0.20 t C ha(-1 yr(-1, being greater than other scenarios, and (4 the reduced inorganic N fertilizer scenario produced the least N loss from the system, while all the scenarios produced comparable grain yields. CONCLUSIONS: In terms of net GWP and GHGI for the comprehensive assessment of climate change and crop production, reduced inorganic N fertilizer scenario followed by no-tillage scenario would be advocated for this specified

  12. CFD Validation of Gas Injection in Flowing Mercury over Vertical Smooth and Grooved Wall

    International Nuclear Information System (INIS)

    Abdou, Ashraf A.; Wendel, Mark W.; Felde, David K.; Riemer, Bernie

    2009-01-01

    The Spallation Neutron Source (SNS) is an accelerator-based neutron source at Oak Ridge National Laboratory (ORNL). The nuclear spallation reaction occurs when a proton beam hits liquid mercury. This interaction causes thermal expansion of the liquid mercury which produces high pressure waves. When these pressure waves hit the target vessel wall, cavitation can occur and erode the wall. Research and development efforts at SNS include creation of a vertical protective gas layer between the flowing liquid mercury and target vessel wall to mitigate the cavitation damage erosion and extend the life time of the target. Since mercury is opaque, computational fluid dynamics (CFD) can be used as a diagnostic tool to see inside the liquid mercury and guide the experimental efforts. In this study, CFD simulations of three dimensional, unsteady, turbulent, two-phase flow of helium gas injection in flowing liquid mercury over smooth, vertically grooved and horizontally grooved walls are carried out with the commercially available CFD code Fluent-12 from ANSYS. The Volume of Fluid (VOF) model is used to track the helium-mercury interface. V-shaped vertical and horizontal grooves with 0.5 mm pitch and about 0.7 mm depth were machined in the transparent wall of acrylic test sections. Flow visualization data of helium gas coverage through transparent test sections is obtained with a high-speed camera at the ORNL target test facility (TTF). The helium gas mass flow rate is 8 mg/min and introduced through a 0.5 mm diameter port. The local mercury velocity is 0.9 m/s. In this paper, the helium gas flow rate and the local mercury velocity are kept constant for the three cases. Time integration of predicted helium gas volume fraction over time is done to evaluate the gas coverage and calculate the average thickness of the helium gas layer. The predicted time-integrated gas coverage over vertically grooved and horizontally grooved test sections is better than over a smooth wall. The

  13. Reduction of gas flow into a hollow cathode ion source for a neutral beam injector

    International Nuclear Information System (INIS)

    Tanaka, S.; Akiba, M.; Arakawa, Y.; Horiike, H.; Sakuraba, J.

    1982-01-01

    Experimental studies have been made on the reduction of the gas flow rate into ion sources which utilize a hollow cathode. The electron emitter of the hollow cathode was a barium oxide impregnated porous tungsten tube. The hollow cathode was mounted to a circular or a rectangular bucket source and the following results were obtained. There was a tendency for the minimum gas flow rate for the stable source operation to decrease with increasing orifice diameter of the hollow cathode up to 10 mm. A molybdenum button with an appropriate diameter set in front of the orifice reduced the minimum gas flow rate to one half of that without button. An external magnetic field applied antiparallel to the field generated by the heater current stabilized the discharges and reduced the minimum gas flow rate to one half of that without field. Combination of the button and the antiparallel field reduced the minimum gas flow rate from the initial value (9.5 Torr 1/s) to 2.4 Torr 1/s. The reason for these effects was discussed on the basis of the theory for arc starvation

  14. Gas-liquid mass transfer in a cross-flow hollow fiber module : Analytical model and experimental validation

    NARCIS (Netherlands)

    Dindore, V. Y.; Versteeg, G. F.

    2005-01-01

    The cross-flow operation of hollow fiber membrane contactors offers many advantages and is preferred over the parallel-flow contactors for gas-liquid mass transfer operations. However, the analysis of such a cross-flow membrane gas-liquid contactor is complicated due to the change in concentrations

  15. Modeling study of rarefied gas effects on hypersonic reacting stagnation flows

    Science.gov (United States)

    Wang, Zhihui; Bao, Lin

    2014-12-01

    Recent development of the near space hypersonic sharp leading vehicles has raised a necessity to fast and accurately predict the aeroheating in hypersonic rarefied flows, which challenges our understanding of the aerothermodynamics and aerothermochemistry. The present flow and heat transfer problem involves complex rarefied gas effects and nonequilibrium real gas effects which are beyond the scope of the traditional prediction theory based on the continuum hypothesis and equilibrium assumption. As a typical example, it has been found that the classical Fay-Riddell equation fails to predict the stagnation point heat flux, when the flow is either rarefied or chemical nonequilibrium. In order to design a more general theory covering the rarefied reacting flow cases, an intuitive model is proposed in this paper to describe the nonequilibrium dissociation-recombination flow along the stagnation streamline towards a slightly blunted nose in hypersonic rarefied flows. Some characteristic flow parameters are introduced, and based on these parameters, an explicitly analytical bridging function is established to correct the traditional theory to accurately predict the actual aeroheating performance. It is shown that for a small size nose in medium density flows, the flow at the outer edge of the stagnation point boundary layer could be highly nonequilibrium, and the aeroheating performance is distinguished from that of the big blunt body reentry flows at high altitudes. As a result, when the rarefied gas effects and the nonequilibrium real gas effects are both significant, the classical similarity law could be questionable, and it is inadequate to directly analogize results from the classical blunt body reentry problems to the present new generation sharp-leading vehicles. In addition, the direct simulation Monte Carlo method is also employed to validate the conclusion.

  16. Couette flow regimes with heat transfer in rarefied gas

    Energy Technology Data Exchange (ETDEWEB)

    Abramov, A. A., E-mail: alabr54@mail.ru; Butkovskii, A. V., E-mail: albutkov@mail.ru [Zhukovski Central Aerohydrodynamics Institute (Russian Federation)

    2013-06-15

    Based on numerical solution of the Boltzmann equation by direct statistic simulation, the Couette flow with heat transfer is studied in a broad range of ratios of plate temperatures and Mach numbers of a moving plate. Flow regime classification by the form of the dependences of the energy flux and friction stress on the Knudsen number Kn is proposed. These dependences can be simultaneously monotonic and nonmonotonic and have maxima. Situations are possible in which the dependence of the energy flux transferred to a plate on Kn has a minimum, while the dependence of the friction stress is monotonic or even has a maximum. Also, regimes exist in which the dependence of the energy flux on Kn has a maximum, while the dependence of the friction stress is monotonic, and vice versa.

  17. Investigation of gas flow characteristics in proton exchange membrane fuel cell

    International Nuclear Information System (INIS)

    Kwac, Lee Ku; Kim, Hong Gun

    2008-01-01

    An investigation of electrochemical behavior of PEMFC (proton exchange membrane fuel cell) is performed by using a single-phase two-dimensional finite element analysis. Equations of current balance, mass balance, and momentum balance are implemented to simulate the behavior of PEMFC. The analysis results for the co-flow and counterflow mode of gas flow direction are examined in detail in order to compare how the gas flow direction affects quantitatively. The characteristics of internal properties, such as gas velocity distribution, mass fraction of the reactants, fraction of water and current density distribution in PEMFC are illustrated in the electrode and GDL (gas diffusion layer). It is found that the dry reactant gases can be well internally humidified and maintain high performance in the case of the counter-flow mode without external humidification while it is not advantageous for highly humidified or saturated reactant gases. It is also found that the co-flow mode improves the current density distribution with humidified normal condition compared to the counter-flow mode

  18. Reduced-order modellin for high-pressure transient flow of hydrogen-natural gas mixture

    Science.gov (United States)

    Agaie, Baba G.; Khan, Ilyas; Alshomrani, Ali Saleh; Alqahtani, Aisha M.

    2017-05-01

    In this paper the transient flow of hydrogen compressed-natural gas (HCNG) mixture which is also referred to as hydrogen-natural gas mixture in a pipeline is numerically computed using the reduced-order modelling technique. The study on transient conditions is important because the pipeline flows are normally in the unsteady state due to the sudden opening and closure of control valves, but most of the existing studies only analyse the flow in the steady-state conditions. The mathematical model consists in a set of non-linear conservation forms of partial differential equations. The objective of this paper is to improve the accuracy in the prediction of the HCNG transient flow parameters using the Reduced-Order Modelling (ROM). The ROM technique has been successfully used in single-gas and aerodynamic flow problems, the gas mixture has not been done using the ROM. The study is based on the velocity change created by the operation of the valves upstream and downstream the pipeline. Results on the flow characteristics, namely the pressure, density, celerity and mass flux are based on variations of the mixing ratio and valve reaction and actuation time; the ROM computational time cost advantage are also presented.

  19. Summary on experimental methods for statistical transient analysis of two-phase gas-liquid flow

    International Nuclear Information System (INIS)

    Delhaye, J.M.; Jones, O.C. Jr.

    1976-06-01

    Much work has been done in the study of two-phase gas-liquid flows. Although it has been recognized superficially that such flows are not homogeneous in general, little attention has been paid to the inherent discreteness of the two-phase systems. Only relatively recently have fluctuating characteristics of two-phase flows been studied in detail. As a result, new experimental devices and techniques have been developed for use in measuring quantities previously ignored. This report reviews and summarizes most of these methods in an effort to emphasize the importance of the fluctuating nature of these flows and as a guide to further research in this field

  20. Simulation of gas and particle flow in a circulating fluidized bed; Kaasu- ja kiintoainevirtauksen simulointi kiertoleijukattilassa

    Energy Technology Data Exchange (ETDEWEB)

    Kallio, S. [Aabo Akademi, Turku (Finland). Inst. of Heat Engineering

    1996-12-01

    The aim of this work was to study the effects of different parameters on the flow behaviour in a CFB riser by means of empirical models based on measurement data and a computer code based on macroscopic equations for multiphase flow. The effects of primary air velocity and riser geometry have been observed in the results. Simulation of secondary air flow proved to be problematic with the software used. In the project, also analyses of measurement data from cold model experiments has been performed. Moreover, the possibilities to use commercial CFD codes for simulation of gas-solids flow were investigated. The code FLUENT seemed promising. (author)

  1. Flow Rates in Liquid Chromatography, Gas Chromatography and Supercritical Fluid Chromatography: A Tool for Optimization

    Directory of Open Access Journals (Sweden)

    Joris Meurs

    2016-08-01

    Full Text Available This paper aimed to develop a standalone application for optimizing flow rates in liquid chromatography (LC, gas chromatography (GC and supercritical fluid chromatography (SFC. To do so, Van Deemter’s equation, Knox’ equation and Golay’s equation were implemented in a MATLAB script and subsequently a graphical user interface (GUI was created. The application will show the optimal flow rate or linear velocity and the corresponding plate height for the set input parameters. Furthermore, a plot will be shown in which the plate height is plotted against the linear flow velocity. Hence, this application will give optimized flow rates for any set conditions with minimal effort.

  2. Flow design and simulation of a gas compression system for hydrogen fusion energy production

    Energy Technology Data Exchange (ETDEWEB)

    Avital, E J; Salvatore, E [School of Engineering and Materials Science, Queen Mary University of London, Mile End Rd London E1 4NS (United Kingdom); Munjiza, A [Civil Engineering, University of Split, Livanjska 2100 Split (Croatia); Suponitsky, V; Plant, D; Laberge, M, E-mail: e.avital@qmul.ac.uk [General Fusion Inc.,108-3680 Bonneville Place, Burnaby, BC V3N 4T5 (Canada)

    2017-08-15

    An innovative gas compression system is proposed and computationally researched to achieve a short time response as needed in engineering applications such as hydrogen fusion energy reactors and high speed hammers. The system consists of a reservoir containing high pressure gas connected to a straight tube which in turn is connected to a spherical duct, where at the sphere’s centre plasma resides in the case of a fusion reactor. Diaphragm located inside the straight tube separates the reservoir’s high pressure gas from the rest of the plenum. Once the diaphragm is breached the high pressure gas enters the plenum to drive pistons located on the inner wall of the spherical duct that will eventually end compressing the plasma. Quasi-1D and axisymmetric flow formulations are used to design and analyse the flow dynamics. A spike is designed for the interface between the straight tube and the spherical duct to provide a smooth geometry transition for the flow. Flow simulations show high supersonic flow hitting the end of the spherical duct, generating a return shock wave propagating upstream and raising the pressure above the reservoir pressure as in the hammer wave problem, potentially giving temporary pressure boost to the pistons. Good agreement is revealed between the two flow formulations pointing to the usefulness of the quasi-1D formulation as a rapid solver. Nevertheless, a mild time delay in the axisymmetric flow simulation occurred due to moderate two-dimensionality effects. The compression system is settled down in a few milliseconds for a spherical duct of 0.8 m diameter using Helium gas and a uniform duct cross-section area. Various system geometries are analysed using instantaneous and time history flow plots. (paper)

  3. Flow design and simulation of a gas compression system for hydrogen fusion energy production

    Science.gov (United States)

    Avital, E. J.; Salvatore, E.; Munjiza, A.; Suponitsky, V.; Plant, D.; Laberge, M.

    2017-08-01

    An innovative gas compression system is proposed and computationally researched to achieve a short time response as needed in engineering applications such as hydrogen fusion energy reactors and high speed hammers. The system consists of a reservoir containing high pressure gas connected to a straight tube which in turn is connected to a spherical duct, where at the sphere’s centre plasma resides in the case of a fusion reactor. Diaphragm located inside the straight tube separates the reservoir’s high pressure gas from the rest of the plenum. Once the diaphragm is breached the high pressure gas enters the plenum to drive pistons located on the inner wall of the spherical duct that will eventually end compressing the plasma. Quasi-1D and axisymmetric flow formulations are used to design and analyse the flow dynamics. A spike is designed for the interface between the straight tube and the spherical duct to provide a smooth geometry transition for the flow. Flow simulations show high supersonic flow hitting the end of the spherical duct, generating a return shock wave propagating upstream and raising the pressure above the reservoir pressure as in the hammer wave problem, potentially giving temporary pressure boost to the pistons. Good agreement is revealed between the two flow formulations pointing to the usefulness of the quasi-1D formulation as a rapid solver. Nevertheless, a mild time delay in the axisymmetric flow simulation occurred due to moderate two-dimensionality effects. The compression system is settled down in a few milliseconds for a spherical duct of 0.8 m diameter using Helium gas and a uniform duct cross-section area. Various system geometries are analysed using instantaneous and time history flow plots.

  4. An Efficient Hybrid DSMC/MD Algorithm for Accurate Modeling of Micro Gas Flows

    KAUST Repository

    Liang, Tengfei

    2013-01-01

    Aiming at simulating micro gas flows with accurate boundary conditions, an efficient hybrid algorithmis developed by combining themolecular dynamics (MD) method with the direct simulationMonte Carlo (DSMC)method. The efficiency comes from the fact that theMD method is applied only within the gas-wall interaction layer, characterized by the cut-off distance of the gas-solid interaction potential, to resolve accurately the gas-wall interaction process, while the DSMC method is employed in the remaining portion of the flow field to efficiently simulate rarefied gas transport outside the gas-wall interaction layer. A unique feature about the present scheme is that the coupling between the two methods is realized by matching the molecular velocity distribution function at the DSMC/MD interface, hence there is no need for one-toone mapping between a MD gas molecule and a DSMC simulation particle. Further improvement in efficiency is achieved by taking advantage of gas rarefaction inside the gas-wall interaction layer and by employing the "smart-wall model" proposed by Barisik et al. The developed hybrid algorithm is validated on two classical benchmarks namely 1-D Fourier thermal problem and Couette shear flow problem. Both the accuracy and efficiency of the hybrid algorithm are discussed. As an application, the hybrid algorithm is employed to simulate thermal transpiration coefficient in the free-molecule regime for a system with atomically smooth surface. Result is utilized to validate the coefficients calculated from the pure DSMC simulation with Maxwell and Cercignani-Lampis gas-wall interaction models. ©c 2014 Global-Science Press.

  5. Greenhouse gas footprint and the carbon flow associated with different solid waste management strategy for urban metabolism in Bangladesh.

    Science.gov (United States)

    Islam, K M Nazmul

    2017-02-15

    Greenhouse gas (GHG) emissions from municipal solid waste (MSW) and associated climate change consequences are gripping attention globally, while MSW management as a vital subsystem of urban metabolism significantly influences the urban carbon cycles. This study evaluates the GHG emissions and carbon flow of existing and proposed MSW management in Bangladesh through scenario analysis, including landfill with landfill gas (LFG) recovery, waste to energy (WtE), and material recovery facility (MRF). The analysis indicates that, scenario H 2 and H 5 emitted net GHGs -152.20kg CO 2 eq. and -140.32kg CO 2 eq., respectively, in comparison with 420.88kg CO 2 eq. of scenario H 1 for managing per ton of wastes during the reference year 2015. The annual horizontal carbon flux of the waste input was 319Gg and 158Gg during 2015 in Dhaka and Chittagong, respectively. An integrated strategy of managing the wastes in the urban areas of Bangladesh involving WtE incineration plant and LFG recovery to generate electricity as well as MRF could reverse back 209.46Gg carbon and 422.29Gg carbon to the Chittagong and Dhaka urban system, respectively. This study provides valuable insights for the MSW policy framework and revamp of existing MSW management practices with regards to reduction of GHGs emissions from the waste sector in Bangladesh. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Dynamic gas flow during plasma operation in TMX-U

    International Nuclear Information System (INIS)

    Pickles, W.L.; Carter, M.R.; Clower, C.A.; Drake, R.P.; Hunt, A.L.; Simonen, T.C.; Turner, W.C.

    1982-01-01

    Control of the neutral density outside of the plasma radius is essential for proper operation of the various plasma configurations in TMX-U. TMX-U excess-beam, stream-gun, gas-box, and beam-reflux gases are pumped internally in regions defined by 73 0 Ti-gettered liners and warm Ti-gettered plasma liners. The array of fast and slow ion gauges - a large TMX-U diagnostic - has been used to measure the dynamic pressure in many of the liner-defined regions on three time scales. The natural divertor action, or plasma pump effect, of mirror plasmas has been measured using the ion gauge diagnostics on a fast time scale during operation of TMX-U with ECRH start-up. Routine operation of TMX-U is enhanced by the ability to verify the effectiveness of gettering and to locate leaks using pressure data collected on the two slow time scales. A computer code, DYNAVAC 6, which treats TMX-U as a set of conductance-coupled regions with pumping and sources in each region, has been used to successfully model the overall gas dynamics during all phases of TMX-U operation

  7. Petri Nets

    Indian Academy of Sciences (India)

    In a computer system, for example, typical discrete events ... This project brought out a series of influential reports on Petri net theory in the mid and late ... Technology became a leading centre for Petri net research and from then on, Petri nets ...

  8. Fundamental research of two-phase flows with high liquid/gas density ratios

    International Nuclear Information System (INIS)

    Mishima, Kaichiro; Hibiki, Takashi; Saito, Yasushi; Tobita, Yoshiharu; Konishi, Kensuke; Suzuki, Tohru

    2000-07-01

    In order to analyze the boiling of a fuel-steel mixture pool formed during the core disruptive accident in a fast breeder reactor, it is important to understand the flow characteristics of gas-liquid two-phase pools containing molten reactor materials. Since the liquid/gas density ratio is high, the characteristics of such two-phase flows may differ from those of ordinary flows such as water/air flow. In this study, as a fundamental research of two-phase flows with a high liquid/gas density ratio, the experiments were performed to visualize and measure molten metal (lead-bismuth)/nitrogen gas two-phase flows using a neutron radiography technique. From these experiments, fundamental data such as bubble shapes, void fractions and liquid velocity fields were obtained. In addition, the momentum exchange model of SIMMER-III, which has been developed by JNC, was assessed and improved using the experimental data. In the visualization by neutron radiography, it was found that deformed ellipsoidal bubbles could be seen with smaller gas flux or lower void fractions, and spherical cap bubbles could be seen with larger gas flux or higher void fractions. In addition, a correlation applicable to SIMMER-III was proposed through a comparison between the experimental data and traditional empirical correlations. Furthermore, a visualization experiment using gold-cadmium tracer particles showed that the image processing technique used in the quantification of void fractions is applicable to the measurement of the liquid velocity fields. On the other hand, in the analysis by SIMMER-III, it was confirmed that the original momentum exchange model was appropriate for ellipsoidal bobby flows and that the accuracy of SIMMER-III for cap bubbly flows was much improved with the proposed correlation. Moreover, a new procedure, in which the appropriate drag coefficient could be automatically selected according to bubble shape, was developed. The SIMMER-III code improved through this study can

  9. Simulations of Micro Gas Flows by the DS-BGK Method

    KAUST Repository

    Li, Jun

    2011-01-01

    For gas flows in micro devices, the molecular mean free path is of the same order as the characteristic scale making the Navier-Stokes equation invalid. Recently, some micro gas flows are simulated by the DS-BGK method, which is convergent to the BGK equation and very efficient for low-velocity cases. As the molecular reflection on the boundary is the dominant effect compared to the intermolecular collisions in micro gas flows, the more realistic boundary condition, namely the CLL reflection model, is employed in the DS-BGK simulation and the influence of the accommodation coefficients used in the molecular reflection model on the results are discussed. The simulation results are verified by comparison with those of the DSMC method as criteria. Copyright © 2011 by ASME.

  10. Numerical Simulation and Analysis of Gas-Liquid Flow in a T-Junction Microchannel

    Directory of Open Access Journals (Sweden)

    Hongtruong Pham

    2012-01-01

    Full Text Available Gas-liquid flow in microchannels is widely used in biomedicine, nanotech, sewage treatment, and so forth. Particularly, owing to the high qualities of the microbubbles and spheres produced in microchannels, it has a great potential to be used in ultrasound imaging and controlled drug release areas; therefore, gas-liquid flow in microchannels has been the focus in recent years. In this paper, numerical simulation of gas-liquid flows in a T-junction microchannel was carried out with computational fluid dynamics (CFD software FLUENT and the Volume-of-Fluid (VOF model. The distribution of velocity, pressure, and phase of fluid in the microchannel was obtained, the pressure distribution along the channel walls was analyzed in order to give a better understanding on the formation of microbubbles in the T-junction microchannel.

  11. DEM-CFD simulation of purge gas flow in a solid breeder pebble bed

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hao [School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230027 (China); Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Li, Zhenghong [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); University of Science and Technology of China, Hefei 230027 (China); Guo, Haibing [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Ye, Minyou [School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230027 (China); Huang, Hongwen, E-mail: inpclane@sina.com [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China)

    2016-12-15

    Solid tritium breeding blanket applying pebble bed concept is promising for fusion reactors. Tritium bred in the pebble bed is purged out by inert gas. The flow characteristics of the purge gas are important for the tritium transport from the solid breeder materials. In this study, a randomly packed pebble bed was generated by Discrete Element Method (DEM) and verified by radial porosity distribution. The flow parameters of the purge gas in channels were solved by Computational Fluid Dynamics (CFD) method. The results show that the normalized velocity magnitudes have the same damped oscillating patterns with radial porosity distribution. Besides, the bypass flow near the wall cannot be ignored in this model, and it has a slight increase with inlet velocity. Furthermore, higher purging efficiency becomes with higher inlet velocity and especially higher in near wall region.

  12. A methodology to model flow-thermals inside a domestic gas oven

    International Nuclear Information System (INIS)

    Mistry, Hiteshkumar; Ganapathisubbu, S.; Dey, Subhrajit; Bishnoi, Peeush; Castillo, Jose Luis

    2011-01-01

    In this paper, the authors describe development of a CFD based methodology to evaluate performance of a domestic gas oven. This involves modeling three-dimensional, unsteady, forced convective flow field coupled with radiative participating media. Various strategies for capturing transient heat transfer coupled with mixed convection flow field are evaluated considering the trade-off between computational time and accuracy of predictions. A new technique of modeling gas oven that does not require detailed modeling of flow-thermals through the burner is highlighted. Experiments carried out to support this modeling development shows that heat transfer from burners can be represented as non-dimensional false bottom temperature profiles. Transient validation of this model with experiments show less than 6% discrepancy in thermal field during preheating of bake cycle of gas oven.

  13. Analysing Gas-Liquid Flow in PEM Electrolyser Micro-Channels

    DEFF Research Database (Denmark)

    Lafmejani, Saeed Sadeghi; Olesen, Anders Christian; Kær, Søren Knudsen

    2016-01-01

    and are fairly expensive. One means of increasing the hydrogen yield to cost ratio of such systems, is to increase the operating current density. However, at high current densities, management of heat and mass transfer in the anode current collector and channel becomes crucial. This entails that further...... understanding of the gas-liquid flow in both the porous media and the channel is necessary for insuring proper oxygen, water and heat management of the electrolysis cell. In this work, the patterns of vertical upward gas-liquid flow in a 5×1×94 mm micro-channel are experimentally analysed. A sheet of titanium...... felt is used as a permeable wall for permeation of air through a column of water similar to the phenomenon encountered at the anode. The transparent setup is operated ex-situ and the gas-liquid flow regimes are identified using a camera....

  14. Influence of Gas Flow Rate on the Deposition Rate on Stainless Steel 202 Substrates

    Directory of Open Access Journals (Sweden)

    M.A. Chowdhury

    2012-12-01

    Full Text Available Solid thin films have been deposited on stainless steel 202 (SS 202 substrates at different flow rates of natural gas using a hot filament thermal chemical vapor deposition (CVD reactor. In the experiments, the variations of thin film deposition rate with the variation of gas flow rate have been investigated. The effects of gap between activation heater and substrate on the deposition rate have also been observed. Results show that deposition rate on SS 202 increases with the increase in gas flow rate within the observed range. It is also found that deposition rate increases with the decrease in gap between activation heater and substrate. In addition, friction coefficient and wear rate of SS 202 sliding against SS 304 under different sliding velocities are also investigated before and after deposition. The experimental results reveal that improved friction coefficient and wear rate is obtained after deposition than that of before deposition.

  15. Study on cocurrent downtake gas-liquid flow in a vertical channel

    International Nuclear Information System (INIS)

    Lozovetskij, V.V.

    1978-01-01

    Hydraulic resistance and liquid stall from the film surface at cocurrent film and gas downflow in vertical channel in measurement range of reynolds number from 100 to 1260 for the film and from 1.2x10 4 to 10 5 for gas are studied. For downflow two regimes are characteristic: purely annular, that is separate phase flow regime, and the regime of stall and carrying liquid droplets from the film surface, that is annular dispersed flow regime. The existence boundaries of both regimes are determined and criterial equations for pressure drop calculation are obtained. It is established experimentally that at sufficient range from the liquid input place on the working zone the established two-phase flow takes place. In their nucleus two areas can be singled out, which differ by the flow density values of stalled liquid: central, having the permanent flow density value and area adjacent to the film surface, the liquid in the combs of waves making a significant contribution to the flow density value. At equal flooding density with the relative gas speed increase, the flow density value of stalled liquid in the channel central part increase. A similar result also takes place at flooding density increase at permanent relative speed. Flooding density and relative speed increase leads to levelling stalled liquid distribution about the channel cross section

  16. Film thickness in gas-liquid two-phase flow, (2)

    International Nuclear Information System (INIS)

    Sekoguchi, Kotohiko; Fukano, Toru; Kawakami, Yasushi; Shimizu, Hideo.

    1977-01-01

    The effect of four rectangular obstacles inserted into a circular tube has been studied in gas-liquid two-phase flow. The obstacles are set on the inner wall of the tube, and the ratio of the opening is 0.6. The water film flows partially through the obstacles. The minimum thickness of water film was measured in relation to flow speed. The serious effect of the obstacles was seen against the formation of water film, and drainage under the obstacles and backward flow play important roles. Since water film can flow partially through the obstacles, the film in case of the rectangular obstacles in thicker than that in case of an orifice when the gas flow speed was slower than 5 m/s. However, when the gas flow speed is over 5 m/s, the film thickness was thinner. The minimum film thickness of downstream of the obstacles was almost same as that in case of no obstacle. The minimum film thickness of up stream depends on the location of measurement due to the effect of drainage. (Kato, T.)

  17. Malignant human cell transformation of Marcellus Shale gas drilling flow back water

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Yixin [Department of Epidemiology, Shanghai Jiaotong University School of Public Health (China); Department of Environmental Medicine, New York University School of Medicine, Tuxedo, NY 10987 (United States); Chen, Tingting [School of Material Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Shen, Steven S. [Biochemistry and Molecular Pharmaceutical, New York University School of Medicine (United States); Niu, Yingmei; DesMarais, Thomas L.; Linn, Reka; Saunders, Eric; Fan, Zhihua [Department of Environmental Medicine, New York University School of Medicine, Tuxedo, NY 10987 (United States); Lioy, Paul [Robert Wood Johnson Medical School Rutgers, The State University of New Jersey, Piscataway, NJ 08854 (United States); Kluz, Thomas; Chen, Lung-Chi [Department of Environmental Medicine, New York University School of Medicine, Tuxedo, NY 10987 (United States); Wu, Zhuangchun, E-mail: wuzhuangchun@mail.njust.edu.cn [College of Science, Donghua University, Shanghai 201620 (China); Costa, Max, E-mail: max.costa@nyumc.org [Department of Environmental Medicine, New York University School of Medicine, Tuxedo, NY 10987 (United States)

    2015-10-01

    The rapid development of high-volume horizontal hydraulic fracturing for mining natural gas from shale has posed potential impacts on human health and biodiversity. The produced flow back waters after hydraulic stimulation are known to carry high levels of saline and total dissolved solids. To understand the toxicity and potential carcinogenic effects of these wastewaters, flow back waters from five Marcellus hydraulic fracturing oil and gas wells were analyzed. The physicochemical nature of these samples was analyzed by inductively coupled plasma mass spectrometry and scanning electron microscopy/energy dispersive X-ray spectroscopy. A cytotoxicity study using colony formation as the endpoint was carried out to define the LC{sub 50} values of test samples using human bronchial epithelial cells (BEAS-2B). The BEAS-2B cell transformation assay was employed to assess the carcinogenic potential of the samples. Barium and strontium were among the most abundant metals in these samples and the same metals were found to be elevated in BEAS-2B cells after long-term treatment. BEAS-2B cells treated for 6 weeks with flow back waters produced colony formation in soft agar that was concentration dependent. In addition, flow back water-transformed BEAS-2B cells show better migration capability when compared to control cells. This study provides information needed to assess the potential health impact of post-hydraulic fracturing flow back waters from Marcellus Shale natural gas mining. - Highlights: • This is the first report of potential cytotoxicity and transforming activity of Marcellus shale gas mining flow back to mammalian cells. • Barium and Strontium were elevated in flow back water exposed cells. • Flow back water malignantly transformed cells and formed tumor in athymic nude mice. • Flow back transformed cells exhibited altered transcriptome with dysregulated cell migration pathway and adherent junction pathway.

  18. Malignant human cell transformation of Marcellus Shale gas drilling flow back water

    International Nuclear Information System (INIS)

    Yao, Yixin; Chen, Tingting; Shen, Steven S.; Niu, Yingmei; DesMarais, Thomas L.; Linn, Reka; Saunders, Eric; Fan, Zhihua; Lioy, Paul; Kluz, Thomas; Chen, Lung-Chi; Wu, Zhuangchun; Costa, Max

    2015-01-01

    The rapid development of high-volume horizontal hydraulic fracturing for mining natural gas from shale has posed potential impacts on human health and biodiversity. The produced flow back waters after hydraulic stimulation are known to carry high levels of saline and total dissolved solids. To understand the toxicity and potential carcinogenic effects of these wastewaters, flow back waters from five Marcellus hydraulic fracturing oil and gas wells were analyzed. The physicochemical nature of these samples was analyzed by inductively coupled plasma mass spectrometry and scanning electron microscopy/energy dispersive X-ray spectroscopy. A cytotoxicity study using colony formation as the endpoint was carried out to define the LC 50 values of test samples using human bronchial epithelial cells (BEAS-2B). The BEAS-2B cell transformation assay was employed to assess the carcinogenic potential of the samples. Barium and strontium were among the most abundant metals in these samples and the same metals were found to be elevated in BEAS-2B cells after long-term treatment. BEAS-2B cells treated for 6 weeks with flow back waters produced colony formation in soft agar that was concentration dependent. In addition, flow back water-transformed BEAS-2B cells show better migration capability when compared to control cells. This study provides information needed to assess the potential health impact of post-hydraulic fracturing flow back waters from Marcellus Shale natural gas mining. - Highlights: • This is the first report of potential cytotoxicity and transforming activity of Marcellus shale gas mining flow back to mammalian cells. • Barium and Strontium were elevated in flow back water exposed cells. • Flow back water malignantly transformed cells and formed tumor in athymic nude mice. • Flow back transformed cells exhibited altered transcriptome with dysregulated cell migration pathway and adherent junction pathway.

  19. Two-Phase Gas-Liquid Flow Structure Characteristics under Periodic Cross Forces Action

    Directory of Open Access Journals (Sweden)

    V. V. Perevezentsev

    2015-01-01

    Full Text Available The article presents a study of two-phase gas-liquid flow under the action of periodic cross forces. The work objective is to obtain experimental data for further analysis and have structure characteristics of the two-phase flow movement. For research, to obtain data without disturbing effect on the flow were used optic PIV (Particle Image Visualization methods because of their noninvasiveness. The cross forces influence was provided by an experimental stand design to change the angular amplitudes and the periods of channel movement cycle with two-phase flow. In the range of volume gas rates was shown a water flow rate versus the inclination angle of immovable riser section and the characteristic angular amplitudes and periods of riser section inclination cycle under periodic cross forces. Data on distribution of average water velocity in twophase flow in abovementioned cases were also obtained. These data allowed us to draw a conclusion that a velocity distribution depends on the angular amplitude and on the period of the riser section roll cycle. This article belongs to publications, which study two-phase flows with no disturbing effect on them. Obtained data give an insight into understanding a pattern of twophase gas-liquid flow under the action of periodic cross forces and can be used to verify the mathematical models of the CFD thermo-hydraulic codes. In the future, the work development expects taking measurements with more frequent interval in the ranges of angular amplitudes and periods of the channel movement cycle and create a mathematical model to show the action of periodic cross forces on two-phase gas-liquid flow.

  20. Structure of the gas-liquid annular two-phase flow in a nozzle section

    International Nuclear Information System (INIS)

    Yoshida, Kenji; Kataoka, Isao; Ohmori, Syuichi; Mori, Michitsugu

    2006-01-01

    Experimental studies on the flow behavior of gas-liquid annular two-phase flow passing through a nozzle section were carried out. This study is concerned with the central steam jet injector for a next generation nuclear reactor. In the central steam jet injector, steam/water annular two-phase flow is formed at the mixing nozzle. To make an appropriate design and to establish the high-performance steam injector system, it is very important to accumulate the fundamental data of the thermo-hydro dynamic characteristics of annular flow passing through a nozzle section. On the other hand, the transient behavior of multiphase flow, in which the interactions between two-phases occur, is one of the most interesting scientific issues and has attracted research attention. In this study, the transient gas-phase turbulence modification in annular flow due to the gas-liquid phase interaction is experimentally investigated. The annular flow passing through a throat section is under the transient state due to the changing cross sectional area of the channel and resultantly the superficial velocities of both phases are changed compared with a fully developed flow in a straight pipe. The measurements for the gas-phase turbulence were precisely performed by using a constant temperature hot-wire anemometer, and made clear the turbulence structure such as velocity profiles, fluctuation velocity profiles. The behavior of the interfacial waves in the liquid film flow such as the ripple or disturbance waves was also observed. The measurements for the liquid film thickness by the electrode needle method were also performed to measure the base film thickness, mean film thickness, maximum film thickness and wave height of the ripple or the disturbance waves. (author)

  1. Atomic iodine production in a gas flow by decomposing methyl iodide in a dc glow discharge

    International Nuclear Information System (INIS)

    Mikheyev, P A; Shepelenko, A A; Voronov, A I; Kupryaev, Nikolai V

    2002-01-01

    The production of atomic iodine for an oxygen - iodine laser is studied by decomposing methyl iodide in a dc glow discharge in a vortex gas flow. The concentration of iodine atoms in discharge products was measured from the atomic iodine absorption of the radiation of a single-frequency tunable diode laser at a wavelength of 1.315 μm. Atomic iodine concentrations sufficient for the operation of an oxygen - iodine laser were obtained. The concentration of atomic iodine amounted to 3.6 x 10 15 cm -3 for a pressure of the carrying argon gas of 15 Torr. The discharge stabilisation by a vortex gas flow allowed the glow discharge to be sustained in a strongly electronegative halogen-containing gas mixture for pressures up to 20 Torr. (active media)

  2. Numerical Investigation of PLIF Gas Seeding for Hypersonic Boundary Layer Flows

    Science.gov (United States)

    Johanson, Craig T.; Danehy, Paul M.

    2012-01-01

    Numerical simulations of gas-seeding strategies required for planar laser-induced fluorescence (PLIF) in a Mach 10 air flow were performed. The work was performed to understand and quantify adverse effects associated with gas seeding and to compare different flow rates and different types of seed gas. The gas was injected through a slot near the leading edge of a flat plate wedge model used in NASA Langley Research Center's 31- Inch Mach 10 Air Tunnel facility. Nitric oxide, krypton, and iodine gases were simulated at various injection rates. Simulation results showing the deflection of the velocity field for each of the cases are presented. Streamwise distributions of velocity and concentration boundary layer thicknesses as well as vertical distributions of velocity, temperature, and mass distributions are presented for each of the cases. Relative merits of the different seeding strategies are discussed.

  3. Visualization for gas-liquid two-phase flow using wire mesh tomography

    International Nuclear Information System (INIS)

    Motegi, Yuichi; Wanjiraniran, Weerin; Kikura, Hiroshige; Aritomi, Masanori; Yamauchi, Toyoaki

    2003-01-01

    Wire Mesh Tomography (WMT), which is system to measure two-phase flow, has been developed in our laboratory. Measurement principle of WMT is detecting conductivity difference between gas and liquid. WMT measures void fraction as raw date, and calculates gas velocity and bubble volume etc. In this paper, this measurement technique was applied to vertical circular pipe of 50 mm diameter and about 7 m heights. New Wire Mesh Sensor (WMS), which is measurement part of WMT, for circular pipe, have been made. When experiment was performed, superficial gas and water velocity. The effect of each flow parameter was found for void fraction, true gas velocity and bubble volume and the results was in good agreement with the past research, qualitatively. (author)

  4. Summary of 1988 WIPP [Waste Isolation Pilot Plant] Facility horizon gas flow measurements

    International Nuclear Information System (INIS)

    Stormont, J.C.

    1990-11-01

    Numerous gas flow measurements have been made at the Waste Isolation Pilot Plant (WIPP) Facility horizon during 1988. All tests have been pressure decay or constant pressure tests from single boreholes drilled from the underground excavations. The test fluid has been nitrogen. The data have been interpreted as permeabilities and porosities by means of a transient numerical solution method. A closed-form steady-state approximation provides a reasonable order-of-magnitude permeability estimate. The effective resolution of the measurement system is less than 10 -20 m 2 . Results indicate that beyond 1 to 5 m from an excavation, the gas flow is very small and the corresponding permeability is below the system resolution. Within the first meter of an excavation, the interpreted permeabilities can be 5 orders of magnitude greater than the undisturbed or far-field permeability. The interpreted permeabilities in the region between the undisturbed region and the first meter from an excavation are in the range of 10 -16 to 10 -20 m 2 . Measurable gas flow occurs to a greater depth into the roof above WIPP excavations of different sizes and ages than into the ribs and floor. The gas flows into the formation surrounding the smallest excavation tested are consistently lower than those at similar locations surrounding larger excavations of comparable age. Gas flow measured in the interbed layers near the WIPP excavations is highly variable. Generally, immediately above and below excavations, relatively large gas flow is measured in the interbed layers. These results are consistent with previous measurements and indicate a limited disturbed zone surrounding WIPP excavations. 31 refs., 99 figs., 5 tabs

  5. Transient heat transfer for helium gas flowing over a horizontal cylinder with exponentially increasing heat input

    International Nuclear Information System (INIS)

    Liu, Qiusheng; Fukuda, Katsuya

    2003-01-01

    The transient heat transfer coefficients for forced convection flow of helium gas over a horizontal cylinder were measured under wide experimental conditions. The platinum cylinder with a diameter of 1.0 mm was used as test heater and heated by electric current with an exponentially increasing heat input of Q 0 exp(t/τ). The gas flow velocities ranged from 5 to 35 m/s, the gas temperatures ranged from 25 to 80degC, and the periods of heat generation rate, τ, ranged from 40 ms to 20 s. The surface superheat and heat flux increase exponentially as the heat generation rate increases with the exponential function. It was clarified that the heat transfer coefficient approaches the quasi-steady-state one for the period τ longer than about 1 s, and it becomes higher for the period shorter than around 1 s. The transient heat transfer shows less dependence on the gas flowing velocity when the period becomes very shorter. The gas temperature in this study shows little influence on the heat transfer coefficient. Semi-empirical correlation for quasi-steady-state heat transfer was obtained based on the experimental data. The ratios of transient Nusselt number Nu tr to quasi-steady-state Nusselt number Nu st at various periods, flow velocities, and gas temperatures were obtained. The heat transfer shifts to the quasi-steady-state heat transfer for longer periods and shifts to the transient heat transfer for shorter periods at the same flow velocity. It also approaches the quasi-steady-state one for higher flow velocity at the same period. Empirical correlation for transient heat transfer was also obtained based on the experimental data. (author)

  6. Modeling of gas flow and deposition profile in HWCVD processes

    Energy Technology Data Exchange (ETDEWEB)

    Pflug, Andreas; Höfer, Markus; Harig, Tino; Armgardt, Markus; Britze, Chris; Siemers, Michael; Melzig, Thomas; Schäfer, Lothar

    2015-11-30

    Hot wire chemical vapor deposition (HWCVD) is a powerful technology for deposition of high quality films on large area, where drawbacks of plasma based technology such as defect generation by ion bombardment and high equipment costs are omitted. While processes for diamond coatings using H{sub 2} and CH{sub 4} as precursor have been investigated in detail since 1990 and have been transferred to industry, research also focuses on silicon based coatings with H{sub 2}, SiH{sub 4} and NH{sub 3} as process gases. HWCVD of silicon based coatings is a promising alternative for state-of-the-art radiofrequency-plasma enhanced chemical vapor deposition reactors. The film formation in HWCVD results from an interaction of several concurrent chemical reactions such as gas phase chemistry, film deposition, abstraction of surplus hydrogen bonds and etching by atomic hydrogen. Since there is no easy relation between process parameters and resulting deposition profiles, substantial experimental effort is required to optimize the process for a given film specification and the desired film uniformity. In order to obtain a deeper understanding of the underlying mechanisms and to enable an efficient way of process optimization, simulation methods come into play. While diamond deposition occurs at pressures in the range of several kPa HWCVD deposition of Si based coatings operates at pressures in the 0.1–30 Pa range. In this pressure regime, particle based simulation methods focused on solving the Boltzmann equation are computationally feasible. In comparison to computational fluid dynamics this yields improved accuracy even near small gaps or orifices, where characteristic geometric dimensions approach the order of the mean free path of gas molecules. At Fraunhofer IST, a parallel implementation of the Direct Simulation Monte Carlo (DSMC) method extended by a reactive wall chemistry model is developed. To demonstrate the feasibility of three-dimensional simulation of HWCVD processes

  7. A study on the effect of gas flow rate on the wave characteristics in two-phase gas-liquid annular flow

    Energy Technology Data Exchange (ETDEWEB)

    Han Huawei [Faculty of Engineering and Applied Science, University of Ontario Institute of Technology, Oshawa, Ont., L1H 7K4 (Canada)]. E-mail: colin.han@uoit.ca; Zhu Zhenfeng [Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, Sask., S7N 5A9 (Canada)]. E-mail: zhz752@mail.usask.ca; Gabriel, Kamiel [University of Ontario Institute of Technology, Oshawa, Ont., L1H 7K4 (Canada)]. E-mail: kamiel.gabriel@uoit.ca

    2006-12-15

    Interfacial waves play a very important role in the mass, momentum and energy transport phenomena in annular flow. In this paper, film thickness time-trace measurements for air-water annular flow were collected in a small vertical tube using a parallel wire probe. Using the data, a typical disturbance wave shape was obtained and wave properties (e.g., width, height, speed and roughness) were presented. The liquid mass flux ranged from 100 to 200 kg/m{sup 2} s and the gas mass flux ranged from 18 to 47 kg/m{sup 2} s. Disturbance wave characteristics were defined and the effects of changing the gas flow rate on the wave spacing, wave width, wave peak height and wave base height were studied. An average velocity model for the wave and base regions has been developed to determine the wave velocity. The investigation method could be further extended to annular-mist flow which frequently occurs in boiling water reactors.

  8. Development of gas-solid direct contact heat exchanger by use of axial flow cyclone

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Akihiko; Yokomine, Takehiko [Kyushu University (Japan). Interdisciplinary Graduate School of Engineering Sciences; Nagafuchi, Tatsuro [Miura Co. Ltd., Matsuyamashi (Japan)

    2004-10-01

    A heat exchanger between particulate or granular materials and gas is developed. It makes use of a swirling gas flow similar to the usual cyclone separators but the difference from them is that the swirl making gas is issued into the cyclone chamber with downward axial velocity component. After it turns the flow direction near the bottom of the chamber, the low temperature gas receives heat from high temperature particles supplied from above at the chamber's center. Through this configuration, a direct contact and quasi counter-flow heat exchange pattern is realized so that the effective recovery of heat carried by particles is achieved. A model heat exchanger was manufactured via several numerical experiments and its performances of heat exchange as well as particle recovery were examined. Attaching a small particle diffuser below the particle-feeding nozzle brought about a drastic improvement of the heat exchange performance without deteriorating the particle recovery efficiency. The outlet gas temperature much higher than the particle outlet temperature was finally obtained, which is never realized in the parallel flow heat exchanger. (author)

  9. A dynamic model of gas flow in a non-uniform pipe

    International Nuclear Information System (INIS)

    Mensah, S.; Lepp, R.M.

    1979-08-01

    A gas-line model, based on the analysis of compressible flow with friction, has been developed to describe the dynamics of gas flow in a non-uniform line, i.e. one comprising segments of different lengths and diameters. Acoustic wave analysis was used in a novel way, by considering the line as a cascaded connection of uniform pipes separated by discontinuities. The transmission matrix representing this non-uniform line is the product of the matrices for each element in the system. To facilitate implementation of the theoretical model on a hybrid computer, modal approximatons to its transfer functions were derived. Both models were validated against experimental data. (author)

  10. Experimental studies on particle deposition by thermophoresis and inertial impaction from particulate high temperature gas flow

    International Nuclear Information System (INIS)

    Kim, S.S.; Kim, Y.J.

    1987-01-01

    In view of fouling and erosion of gas turbine blade, heat exchanger and pipelines, increasing attention has been paid to particle deposition (transport) in high temperature flow systems. This is also necessary to develop a cleaning or filtration devices. Using 'real time' laser-light reflectivity and scanning electron microscope technique, we quantitatively treat particle size effect and the interaction between Brownian diffusion, thermoporesis (particle drift down a temperature gradient), and inertial impaction of particles (0.2 to 30 μm in diameter) in laminar hot combustion gas-particles flow (ca. 1565 K)

  11. CFD simulation of gas and non-Newtonian fluid two-phase flow in anaerobic digesters.

    Science.gov (United States)

    Wu, Binxin

    2010-07-01

    This paper presents an Eulerian multiphase flow model that characterizes gas mixing in anaerobic digesters. In the model development, liquid manure is assumed to be water or a non-Newtonian fluid that is dependent on total solids (TS) concentration. To establish the appropriate models for different TS levels, twelve turbulence models are evaluated by comparing the frictional pressure drops of gas and non-Newtonian fluid two-phase flow in a horizontal pipe obtained from computational fluid dynamics (CFD) with those from a correlation analysis. The commercial CFD software, Fluent12.0, is employed to simulate the multiphase flow in the digesters. The simulation results in a small-sized digester are validated against the experimental data from literature. Comparison of two gas mixing designs in a medium-sized digester demonstrates that mixing intensity is insensitive to the TS in confined gas mixing, whereas there are significant decreases with increases of TS in unconfined gas mixing. Moreover, comparison of three mixing methods indicates that gas mixing is more efficient than mixing by pumped circulation while it is less efficient than mechanical mixing.

  12. Theoretical Valuation of Multi-Channel Cyclone to Reduce Gas Flow Dustiness in Agressive Environment

    Directory of Open Access Journals (Sweden)

    Aleksandras Chlebnikovas

    2016-10-01

    Full Text Available Contaminated gas cleaning from finely divided solids is carried out using a new generation of multi-channel design cyclones. The application of these devices are separated and precipitated particles with a minimum diameter up to 2 micrometers, reaching up to 95% cleaning efficiency. Cyclones of such constructions are usually used under usual conditions at elevated temperature and low humidity. Under aggressive conditions, these devices can be clogged, and their recovery is not possible. Further studies are research into the application of constructive solutions to adapt the cyclone gas cleaning of the particulate matter under aggressive conditions. This theoretical evaluation has described the characteristics change of gas flow and particulate matters at different aggressive environment. Such conditions were loudly describe the gas-flow high-temperature range of 50–200 °C and gas-vapor stream, the humidity reaches 70–100%. Estimated aggressive conditions on the gas flow dynamics forces – pressure, resistance and centrifugal, and particulate mechanical – gravitational and adhesion strength. All parameters are evaluated in comparison with the values under normal conditions.

  13. Development of a new solvent-free flow efficiency coating for natural gas pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Fogg, Graham A.; Morse, Jennifer [Bredero Shaw, Houston, TX (United States)

    2005-07-01

    Pipeline design engineers have traditionally considered external anti-corrosion coatings for the protection of gas transmission pipelines, with less consideration given to the benefits of internal flow efficiency coatings. This paper reviews the benefits of using a traditional solvent-based flow efficiency coating, and the relationship between the internal surface roughness of a pipe, the pressure drop across the pipeline, and the maximum flow rate of gas through the pipeline. To improve upon existing solvent-based flow efficiency coatings, a research program was undertaken to develop a solvent-free coating. The stages in the development of this coating are discussed, resulting in the plant application of the coating and final qualification to API RP 5L2. (author)

  14. Hydrodynamic flow regimes, gas holdup, and liquid circulation in airlift reactors

    Energy Technology Data Exchange (ETDEWEB)

    Abashar, M.E.; Narsingh, U.; Rouillard, A.E.; Judd, R. [Univ. of Durban (South Africa)

    1998-04-01

    This study reports an experimental investigation into the hydrodynamic behavior of an external-loop airlift reactor (ALR) for the air-water system. Three distinct flow regimes are identified--namely homogeneous, transition, and heterogeneous regimes. The transition between homogeneous and heterogeneous flow is observed to occur over a wide range rather than being merely a single point as has been previously reported in the literature. A gas holdup correlation is developed for each flow regime. The correlations fit the experimental gas holdup data with very good accuracy (within {+-}5%). It would appear, therefore, that a deterministic equation to describe each flow regime is likely to exist in ALRs. This equation is a function of the reactor geometry and the system`s physical properties. New data concerning the axial variation of gas holdup is reported in which a minimum value is observed. This phenomenon is discussed and an explanation offered. Discrimination between two sound theoretical models--namely model 1 (Chisti et al., 1988) and model 2 (Garcia Calvo, 1989)--shows that model 1 predicts satisfactorily the liquid circulation velocity with an error of less than {+-} 10%. The good predictive features of model 1 may be due to the fact that it allows for a significant energy dissipation by wakes behind bubbles. Model 1 is now further improved by the new gas holdup correlations which are derived for the three different flow regimes.

  15. Re-assessment of net energy production and greenhouse gas emissions avoidance after 40 years of photovoltaics development

    NARCIS (Netherlands)

    Louwen, Atse|info:eu-repo/dai/nl/375268456; Van Sark, Wilfried G J H M|info:eu-repo/dai/nl/074628526; Faaij, André P C; Schropp, Ruud E I|info:eu-repo/dai/nl/072502584

    2016-01-01

    Since the 1970s, installed solar photovoltaic capacity has grown tremendously to 230 gigawatt worldwide in 2015, with a growth rate between 1975 and 2015 of 45%. This rapid growth has led to concerns regarding the energy consumption and greenhouse gas emissions of photovoltaics production. We

  16. Developments in greenhouse gas emissions and net energy use in Danish agriculture - How to achieve substantial CO2 reduction?

    DEFF Research Database (Denmark)

    Dalgaard, Tommy; Olesen, Jørgen E; Petersen, Søren O

    2011-01-01

    Greenhouse gas (GHG) emissions from agriculture are a significant contributor to total Danish emissions. Consequently, much effort is currently given to the exploration of potential strategies to reduce agricultural emissions. This paper presents results from a study estimating agricultural GHG e...

  17. Net soil respiration and greenhouse gas balance along a sequence of forest disturbance to smallholder rubber and oil palm plantations in Sumatra

    Science.gov (United States)

    Khusyu Aini, Fitri; Hergoualc'h, Kristell; Smith, Jo; Verchot, Louis; Martius, Christopher

    2017-04-01

    The rapid increase in demand for land to establish oil palm and rubber plantations has led to the conversion of forests, with potential impacts on greenhouse gas emissions and on climate change. This study evaluates the net greenhouse gas balance following forest change to other land uses, i.e. one year rubber plantation, twenty-year rubber plantation and eight year oil palm plantation on Sumatran mineral soils. None of the plantations had ever been fertilized previously. During this study they were fertilized to provide nitrogen at the recommended rate used by farmers (33.3 kg N ha-1 y-1). The ecosystem stores carbon in litterfall, standing litter biomass (undergrowth vegetation, leaves, twigs, litter on the soil surface), soil organic matter, root biomass, and standing tree biomass. It releases carbon to the atmosphere through soil respiration fluxes, negative values indicating that carbon is stored by the land use change and positive values indicating emissions to the atmosphere. Net soil respiration was assessed using a mass balance approach: standing litter and tree biomass were measured once; the rate of carbon accumulation from standing litter and tree biomass was calculated by dividing the stock by the age of plantation or the time since logging started in the disturbed forest. The carbon accumulation in standing litter, tree biomass in the forest and soil organic matter for all land-uses was estimated from available in the literature. Root biomass for each land-use system was calculated using the root:shoot ratio. The net soil respiration of carbon dioxide from the forest, disturbed forest, one year rubber plantation, twenty-year rubber plantation and oil palm plantation were calculated to be -6 (± 5), 12 (± 6), 11 (± 15), 10 (± 5), 39 (± 7) Mg ha-1 y-1, respectively. Soil nitrous oxide, methane and litterfall were measured for 14 months and respiration fluxes were measured for 5 months across land uses and different seasons. The measured emissions of

  18. Using artificial intelligence to improve identification of nanofluid gas-liquid two-phase flow pattern in mini-channel

    Science.gov (United States)

    Xiao, Jian; Luo, Xiaoping; Feng, Zhenfei; Zhang, Jinxin

    2018-01-01

    This work combines fuzzy logic and a support vector machine (SVM) with a principal component analysis (PCA) to create an artificial-intelligence system that identifies nanofluid gas-liquid two-phase flow states in a vertical mini-channel. Flow-pattern recognition requires finding the operational details of the process and doing computer simulations and image processing can be used to automate the description of flow patterns in nanofluid gas-liquid two-phase flow. This work uses fuzzy logic and a SVM with PCA to improve the accuracy with which the flow pattern of a nanofluid gas-liquid two-phase flow is identified. To acquire images of nanofluid gas-liquid two-phase flow patterns of flow boiling, a high-speed digital camera was used to record four different types of flow-pattern images, namely annular flow, bubbly flow, churn flow, and slug flow. The textural features extracted by processing the images of nanofluid gas-liquid two-phase flow patterns are used as inputs to various identification schemes such as fuzzy logic, SVM, and SVM with PCA to identify the type of flow pattern. The results indicate that the SVM with reduced characteristics of PCA provides the best identification accuracy and requires less calculation time than the other two schemes. The data reported herein should be very useful for the design and operation of industrial applications.

  19. Atmospheric pulsed laser deposition of plasmonic nanoparticle films of silver with flowing gas and flowing atmospheric plasma

    Science.gov (United States)

    Khan, T. M.; Pokle, A.; Lunney, J. G.

    2018-04-01

    Two methods of atmospheric pulsed laser deposition of plasmonic nanoparticle films of silver are described. In both methods the ablation plume, produced by a 248 nm, 20 ns excimer laser in gas, is strongly confined near the target and forms a nanoparticle aerosol. For both the flowing gas, and the atmospheric plasma from a dielectric barrier discharge plasma source, the aerosol is entrained in the flow and carried to a substrate for deposition. The nanoparticle films produced by both methods were examined by electron microscopy and optical absorption spectroscopy. With plasma assistance, the deposition rate was significantly enhanced and the film morphology altered. With argon gas, isolated nanoparticles of 20 nm size were obtained, whereas in argon plasma, the nanoparticles are aggregated in clusters of 90 nm size. Helium gas also leads to the deposition of isolated nanoparticles, but with helium plasma, two populations of nanoparticles are observed: one of rounded particles with a mean size of 26 nm and the other of faceted particles with a mean size 165 nm.

  20. General constraints on the effect of gas flows in the chemical evolution of galaxies

    International Nuclear Information System (INIS)

    Edmunds, M.G.

    1990-01-01

    The basic equations for the chemical evolution of galaxies in which the 'simple' closed box model is modified to allow any form of inflow or outflow are examined. It is found that there are quite general limiting constraints on the effects that such flows can have. Some implications for the actual chemical evolution of galaxies are discussed, and the constraints should also be useful in understanding the behaviour of detailed numerical models of galactic chemical evolution involving gas flows. (author)

  1. Renormalization of modular invariant Coulomb gas and Sine-Gordon theories, and quantum Hall flow diagram

    OpenAIRE

    Carpentier, David

    1998-01-01

    Using the renormalisation group (RG) we study two dimensional electromagnetic coulomb gas and extended Sine-Gordon theories invariant under the modular group SL(2,Z). The flow diagram is established from the scaling equations, and we derive the critical behaviour at the various transition points of the diagram. Following proposal for a SL(2,Z) duality between different quantum Hall fluids, we discuss the analogy between this flow and the global quantum Hall phase diagram.

  2. Non Lyapunov stability of a constant spatially developing 2-D gas flow

    Science.gov (United States)

    Balint, Agneta M.; Balint, Stefan; Tanasie, Loredana

    2017-01-01

    Different types of stabilities (global, local) and instabilities (global absolute, local convective) of the constant spatially developing 2-D gas flow are analyzed in a particular phase space of continuously differentiable functions, endowed with the usual algebraic operations and the topology generated by the uniform convergence on the plane. For this purpose the Euler equations linearized at the constant flow are used. The Lyapunov stability analysis was presented in [1] and this paper is a continuation of [1].

  3. For effective thermodynamic calculation of turbines flow-through by gas and steam

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, S; Hultsch, M

    1982-03-01

    A programme system for the medium and multiple section calculation of axial-flow turbines is explained. It allows calculations of turbine flow-through by gas and steam at designing and partial load states. The algorithms are independent upon the formulation of thermodynamic function, so that the programmes can be used for any means of production. The highest accuracy and efficiency can be guaranteed by the use of formulations of thermodynamic functions of water.

  4. Numerical analysis of the thermally induced flow in a strongly rotating gas centrifuge

    Energy Technology Data Exchange (ETDEWEB)

    Novelli, P.

    1982-04-01

    The present work is concerned with the numerical analysis of the thermally induced flow in a rapidly gas centrifuge. The primary purpose for this work is to investigate the dependence of the flow field on the thermal boundary conditions, angular speed, aspect ratio of the cylinder, holdup. Some of our results are compared with the predictions of asymptotic theories, particularly those of Sakurai-Mtsuda and Brouwers, and with the numerical results of Dickinson-Jones.

  5. Formation of a vortex flow at the laser cutting of sheet metal with low pressure of assisting gas

    Energy Technology Data Exchange (ETDEWEB)

    Kovalev, O B; Yudin, P V; Zaitsev, A V [Khristianovich' s Institute of Theoretical and Applied Mechanics, Russian Academy of Sciences, Siberian Branch, Novosibirsk (Russian Federation)], E-mail: kovalev@itam.nsc.ru

    2008-08-07

    Specific features of subsonic jet gas flows in narrow channels geometrically similar to the laser cut are studied experimentally and theoretically. Such flows are visualized by a technique based on prior application of a viscous liquid film onto the side walls of the channel made of transparent glass. The gas flow inside the channel induces a liquid flow on the glass wall in the form of extremely small filaments, which coincide with the streamlines of the gas flow. Filming of these filaments by a CCD camera allows one to capture the specific features of these gas-dynamic flows. Mathematical modelling of the dynamics of a viscous compressible heat-conducting gas was performed by solving full three-dimensional Navier-Stokes equations. Numerical calculations and experiments reveal vortex structures in the flow at the entrance and exit of the channel, which may directly affect the surface quality in real gas-laser cutting of metals. The largest vortex, which arises at the channel exit, collects and accumulates the liquid flowing down the channel walls. Jet flows are generated by sonic nozzles with conical or cylindrical exit sections or by a double coaxial nozzle. The double nozzle includes the central conical nozzle and the side concentric nozzle, which allows additional side injection of the gas to be organized. The study with the double nozzle shows that the vortices disappear as the pressure in the external nozzle is increased, and a stable vortex-free attached gas flow is formed.

  6. Electric battery with gas-operated electrolyte flow. Elektrischer Akkumulator mit gasbetaetigter Elektrolytbewegung

    Energy Technology Data Exchange (ETDEWEB)

    Guetlich, K.F.; Kappus, W.; Zweigardt, H.; Eckardt, R.

    1986-08-28

    The invention relates to an electric accumulator with gas-operated electrolyte flow between electrode plates connected to form a plate block according to the principle of the mammoth pump. At least two supply pipes arranged parallel to each other and with connected gas supply are mounted to a base plate of non-conducting material. The base plate can be pushed in between plate block and housing wall. The base plate consists of two plastic foils of equal height and width the supply pipes and gas leads being formed by protrusions in the plastic foil.

  7. Electric battery with gas-operated electrolyte flow. Elektrischer Akkumulator mit gasbetaetigter Elektrolytbewegung

    Energy Technology Data Exchange (ETDEWEB)

    Guetlich, K.F.; Kappus, W.; Zweigardt, H.; Eckardt, R.

    1980-10-09

    The invention relates to an electric accumulator with gas-operated electrolyte flow between electrode plates connected to form a plate block according to the principle of the mammoth pump. At least two supply pipes arranged parallel to each other and with connected gas supply are mounted to a base plate of non-conducting material. The base plate can be pushed in between plate block and housing wall. The base plate consists of two plastic foils of equal height and width the supply pipes and gas leads being formed by protrusions in the plastic foil.

  8. Atmospheric pressure flow reactor: Gas phase chemical kinetics under tropospheric conditions without wall effects

    Science.gov (United States)

    Koontz, Steven L. (Inventor); Davis, Dennis D. (Inventor)

    1991-01-01

    A flow reactor for simulating the interaction in the troposphere is set forth. A first reactant mixed with a carrier gas is delivered from a pump and flows through a duct having louvers therein. The louvers straighten out the flow, reduce turbulence and provide laminar flow discharge from the duct. A second reactant delivered from a source through a pump is input into the flowing stream, the second reactant being diffused through a plurality of small diffusion tubes to avoid disturbing the laminar flow. The commingled first and second reactants in the carrier gas are then directed along an elongated duct where the walls are spaced away from the flow of reactants to avoid wall interference, disturbance or turbulence arising from the walls. A probe connected with a measuring device can be inserted through various sampling ports in the second duct to complete measurements of the first and second reactants and the product of their reaction at selected XYZ locations relative to the flowing system.

  9. Transition of Gas-Liquid Stratified Flow in Oil Transport Pipes

    Directory of Open Access Journals (Sweden)

    D. Lakehal

    2011-12-01

    Full Text Available Large-Scale Simulation results of the transition of a gas-liquid stratified flow to slug flow regime in circular 3D oil transport pipes under turbulent flow conditions expressed. Free surface flow in the pipe is treated using the Level Set method. Turbulence is approached via the LES and VLES methodologies extended to interfacial two-phase flows. It is shown that only with the Level Set method the flow transition can be accurately predicted, better than with the two-fluid phase-average model. The transition from stratified to slug flow is found to be subsequent to the merging of the secondary wave modes created by the action of gas shear (short waves with the first wave mode (high amplitude long wave. The model is capable of predicting global flow features like the onset of slugging and slug speed. In the second test case, the model predicts different kinds of slugs, the so-called operating slugs formed upstream that fill entirely the pipe with water slugs of length scales of the order of 2-4 D, and lower size (1-1.5 D disturbance slugs, featuring lower hold-up (0.8-0.9. The model predicts well the frequency of slugs. The simulations revealed important parameter effects on the results, such as two-dimensionality, pipe length, and water holdup.

  10. Net sea–air CO2 flux uncertainties in the Bay of Biscay based on the choice of wind speed products and gas transfer parameterizations

    Directory of Open Access Journals (Sweden)

    P. Otero

    2013-05-01

    Full Text Available The estimation of sea–air CO2 fluxes is largely dependent on wind speed through the gas transfer velocity parameterization. In this paper, we quantify uncertainties in the estimation of the CO2 uptake in the Bay of Biscay resulting from the use of different sources of wind speed such as three different global reanalysis meteorological models (NCEP/NCAR 1, NCEP/DOE 2 and ERA-Interim, one high-resolution regional forecast model (HIRLAM-AEMet, winds derived under the Cross-Calibrated Multi-Platform (CCMP project, and QuikSCAT winds in combination with some of the most widely used gas transfer velocity parameterizations. Results show that net CO2 flux estimations during an entire seasonal cycle (September 2002–September 2003 may vary by a factor of ~ 3 depending on the selected wind speed product and the gas exchange parameterization, with the highest impact due to the last one. The comparison of satellite- and model-derived winds with observations at buoys advises against the systematic overestimation of NCEP-2 and the underestimation of NCEP-1. In the coastal region, the presence of land and the time resolution are the main constraints of QuikSCAT, which turns CCMP and ERA-Interim in the preferred options.

  11. On a boundary layer problem related to the gas flow in shales

    KAUST Repository

    Barenblatt, G. I.

    2013-01-16

    The development of gas deposits in shales has become a significant energy resource. Despite the already active exploitation of such deposits, a mathematical model for gas flow in shales does not exist. Such a model is crucial for optimizing the technology of gas recovery. In the present article, a boundary layer problem is formulated and investigated with respect to gas recovery from porous low-permeability inclusions in shales, which are the basic source of gas. Milton Van Dyke was a great master in the field of boundary layer problems. Dedicating this work to his memory, we want to express our belief that Van Dyke\\'s profound ideas and fundamental book Perturbation Methods in Fluid Mechanics (Parabolic Press, 1975) will live on-also in fields very far from the subjects for which they were originally invented. © 2013 US Government.

  12. Two-phase gas bubble-liquid boundary layer flow along vertical and inclined surfaces

    International Nuclear Information System (INIS)

    Cheung, F.B.; Epstein, M.

    1985-01-01

    The behavior of a two-phase gas bubble liquid boundary layer along vertical and inclined porous surfaces with uniform gas injection is investigated experimentally and analytically. Using argon gas and water as the working fluids, a photographical study of the two-phase boundary layer flow has been performed for various angles of inclination ranging from 45 0 to 135 0 and gas injection rates ranging from 0.01 to 0.1 m/s. An integral method has been employed to solve the system of equations governing the two-phase motion. The effects of the gas injection rate and the angle of inclination on the growth of the boundary layer have been determined

  13. Determination of flow rates of oil, water and gas in pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Roach, G J; Watt, J S; Zastawny, H W [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lucas Heights, NSW (Australia). Div. of Mineral Physics

    1994-12-31

    This paper describes a multiphase flow meter developed by CSIRO for determining of the flow rates of oil, water and gas in high pressure pipelines, and the results of a trial of this flow meter on an offshore oil platform. Two gamma-ray transmission gauges are mounted about a pipeline carrying the full flow of oil, water and gas. The flow rates are determined by combining single energy gamma-ray transmission measurements which determine the mass per unit area of fluids in the gamma-ray beam as a function of time, dual energy gamma-ray transmission (DUET) which determine the approximate mass fraction of oil in the liquids, cross-correlation of gamma-ray transmission measurements, with one gauge upstream of the other, which determines flow velocity, pressure and temperature measurements, and knowledge of the specific gravities of oil and (salt) water, and solubility of the gas in the liquids, all as a function of pressure and temperature. 3 figs.

  14. Determination of flow rates of oil, water and gas in pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Roach, G.J.; Watt, J.S.; Zastawny, H.W. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lucas Heights, NSW (Australia). Div. of Mineral Physics

    1993-12-31

    This paper describes a multiphase flow meter developed by CSIRO for determining of the flow rates of oil, water and gas in high pressure pipelines, and the results of a trial of this flow meter on an offshore oil platform. Two gamma-ray transmission gauges are mounted about a pipeline carrying the full flow of oil, water and gas. The flow rates are determined by combining single energy gamma-ray transmission measurements which determine the mass per unit area of fluids in the gamma-ray beam as a function of time, dual energy gamma-ray transmission (DUET) which determine the approximate mass fraction of oil in the liquids, cross-correlation of gamma-ray transmission measurements, with one gauge upstream of the other, which determines flow velocity, pressure and temperature measurements, and knowledge of the specific gravities of oil and (salt) water, and solubility of the gas in the liquids, all as a function of pressure and temperature. 3 figs.

  15. Cavitation and gas-liquid flow in fluid machinery and devices. FED-Volume 190

    International Nuclear Information System (INIS)

    O'Hern, T.J.; Kim, J.H.; Morgan, W.B.; Furuya, O.

    1994-01-01

    Cavitation and gas-liquid two-phase flow have remained important areas in many industrial applications and constantly provided challenges for academic researchers and industrial practitioners alike. Cavitation and two-phase flow commonly occur in fluid machinery such as pumps, propellers, and fluid devices such as orifices, valves, and diffusers. Cavitation not only degrades the performance of these machines and devices but deteriorates the materials. Gas-liquid two-phase flow has also been known to degrade the performance of pumps and propellers and can often induce an instability. The industrial applications of cavitation and two-phase flow can be found in power plants, ship propellers, hydrofoils, and aerospace equipment, to name but a few. The papers presented in this volume reflect the variety and richness of cavitation and gas-liquid two-phase flow in various flow transporting components and the increasing role they play in modern and conventional technologies. Separate abstracts were prepared for 35 papers in this book

  16. Multipath ultrasonic gas flow-meter based on multiple reference waves.

    Science.gov (United States)

    Zhou, Hongliang; Ji, Tao; Wang, Ruichen; Ge, Xiaocheng; Tang, Xiaoyu; Tang, Shizhen

    2018-01-01

    Several technologies can be used in ultrasonic gas flow-meters, such as transit-time, Doppler, cross-correlation and etc. In applications, the approach based on measuring transit-time has demonstrated its advantages and become more popular. Among those techniques which can be applied to determine time-of-flight (TOF) of ultrasonic waves, including threshold detection, cross correlation algorithm and other digital signal processing algorithms, cross correlation algorithm has more advantages when the received ultrasonic signal is severely disturbed by the noise. However, the reference wave for cross correlation computation has great influence on the precise measurement of TOF. In the applications of the multipath flow-meters, selection of the reference wave becomes even more complicated. Based on the analysis of the impact factors that will introduce noise and waveform distortion of ultrasonic waves, an averaging method is proposed to determine the reference wave in this paper. In the multipath ultrasonic gas flow-meter, the analysis of each path of ultrasound needs its own reference wave. In case study, a six-path ultrasonic gas flow-meter has been designed and tested with air flow through the pipeline. The results demonstrate that the flow rate accuracy and the repeatability of the TOF are significantly improved by using averaging reference wave, compared with that using random reference wave. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Determination of flow rates of oil, water and gas in pipelines

    International Nuclear Information System (INIS)

    Roach, G.J.; Watt, J.S.; Zastawny, H.W.

    1993-01-01

    This paper describes a multiphase flow meter developed by CSIRO for determining of the flow rates of oil, water and gas in high pressure pipelines, and the results of a trial of this flow meter on an offshore oil platform. Two gamma-ray transmission gauges are mounted about a pipeline carrying the full flow of oil, water and gas. The flow rates are determined by combining single energy gamma-ray transmission measurements which determine the mass per unit area of fluids in the gamma-ray beam as a function of time, dual energy gamma-ray transmission (DUET) which determine the approximate mass fraction of oil in the liquids, cross-correlation of gamma-ray transmission measurements, with one gauge upstream of the other, which determines flow velocity, pressure and temperature measurements, and knowledge of the specific gravities of oil and (salt) water, and solubility of the gas in the liquids, all as a function of pressure and temperature. 3 figs

  18. Gas dynamic improvement of the axial compressor design for reduction of the flow non-uniformity level

    Science.gov (United States)

    Matveev, V. N.; Baturin, O. V.; Kolmakova, D. A.; Popov, G. M.

    2017-01-01

    Circumferential nonuniformity of gas flow is one of the main problems in the gas turbine engine. Usually, the flow circumferential nonuniformity appears near the annular frame located in the flow passage of the engine. The presence of circumferential nonuniformity leads to the increased dynamic stresses in the blade rows and the blade damage. The goal of this research was to find the ways of the flow non-uniformity reduction, which would not require a fundamental changing of the engine design. A new method for reducing the circumferential nonuniformity of the gas flow was proposed that allows the prediction of the pressure peak values of the rotor blades without computationally expensive CFD calculations.

  19. Time resolved mass flow measurements for a fast gas delivery system

    International Nuclear Information System (INIS)

    Ruden, E.L.; Degnan, J.H.; Hussey, T.W.; Scott, M.C.; Graham, J.D.; Coffey, S.K.

    1992-01-01

    A technique is demonstrated whereby the delivered mass and flow rate vs. time of a short rise time gas delivery system may be accurately determined. The gas mass M which flows past a point in a gas delivery system by an arbitrary time t may be accurately measured if that point is sealed off within a time interval short compared to the mass flow time scale. If the ejected mass is allowed to equilibrate in a known volume after being cut off from its source, a conventional static pressure measurement before and after injection, and application of the ideal gas law suffices. Assuming reproducibility, a time history M(t) may be generated, allowing the flow rate vs. time dM(t)/dt to be determined. Mass flow measurements are presented for a fast delivery system in which the flow of argon through a 3.2 mm I.D., 0.76 mm thick copper tube is cut off by imploding (θ pinching) the tube using a single turn tungsten magnetic field coil. Pinch discharge parameters are 44 μf, 20 kV, 47 nH, 3.5 mΩ, 584 kA, and 8.63 ps current period. Optical measurements of the tube's internal area vs. time indicate that the tube is sealed 2 ps from the time the tube is still 90% open (7 μs from the start of pinch current). The pinch delay is varied from 500--1,500 ps from the valve trigger (0--1,000 ps from the start of gas flow). The mass injected into the test volume is ∼ 100 μg during this interval. The leak rate of the sealed tube results in a mass increase of only ∼ 0.1 μg by the time the pressure gauge stabilizes (6 s). Results are correlated with piezoelectric probe measurements of the gas flow and 2-D axisymmetric numerical simulations of the θ pinch process. Simulations of a θ pinch suitable for characterizing an annular supersonic nozzle typical of those used in gas puff z pinches are discussed

  20. Effects of flow rate and temperature on cyclic gas exchange in tsetse flies (Diptera, Glossinidae).

    Science.gov (United States)

    Terblanche, John S; Chown, Steven L

    2010-05-01

    Air flow rates may confound the investigation and classification of insect gas exchange patterns. Here we report the effects of flow rates (50, 100, 200, 400 ml min(-1)) on gas exchange patterns in wild-caught Glossina morsitans morsitans from Zambia. At rest, G. m. morsitans generally showed continuous or cyclic gas exchange (CGE) but no evidence of discontinuous gas exchange (DGE). Flow rates had little influence on the ability to detect CGE in tsetse, at least in the present experimental setup and under these laboratory conditions. Importantly, faster flow rates resulted in similar gas exchange patterns to those identified at lower flower rates suggesting that G. m. morsitans did not show DGE which had been incorrectly identified as CGE at lower flow rates. While CGE cycle frequency was significantly different among the four flow rates (prate treatment variation. Using a laboratory colony of closely related, similar-sized G. morsitans centralis we subsequently investigated the effects of temperature, gender and feeding status on CGE pattern variation since these factors can influence insect metabolic rates. At 100 ml min(-1) CGE was typical of G. m. centralis at rest, although it was significantly more common in females than in males (57% vs. 43% of 14 individuals tested per gender). In either sex, temperature (20, 24, 28 and 32 degrees C) had little influence on the number of individuals showing CGE. However, increases in metabolic rate with temperature were modulated largely by increases in burst volume and cycle frequency. This is unusual among insects showing CGE or DGE patterns because increases in metabolic rate are usually modulated by increases in frequency, but either no change or a decline in burst volume. Copyright 2009 Elsevier Ltd. All rights reserved.

  1. Analyses of liquid-gas two-phase flow in fermentation tanks

    International Nuclear Information System (INIS)

    Toi, Takashi; Serizawa, Akimi; Takahashi, Osamu; Kawara, Zensaku; Gofuku, Akio; Kataoka, Isao.

    1993-01-01

    The understanding of two-phase flow is one of the important problems for both design and safety analyses of various engineering systems. For example, the flow conditions in beer fermentation tanks have an influence on the quality of production and productivity of tank. In this study, a two-dimensional numerical calculation code based on the one-pressure two-fluid model is developed to understand the circulation structure of low quality liquid-gas two-phase flows induced by bubble plume in a tank. (author)

  2. A gas kinetic scheme for hybrid simulation of partially rarefied flows

    Science.gov (United States)

    Colonia, S.; Steijl, R.; Barakos, G.

    2017-06-01

    Approaches to predict flow fields that display rarefaction effects incur a cost in computational time and memory considerably higher than methods commonly employed for continuum flows. For this reason, to simulate flow fields where continuum and rarefied regimes coexist, hybrid techniques have been introduced. In the present work, analytically defined gas-kinetic schemes based on the Shakhov and Rykov models for monoatomic and diatomic gas flows, respectively, are proposed and evaluated with the aim to be used in the context of hybrid simulations. This should reduce the region where more expensive methods are needed by extending the validity of the continuum formulation. Moreover, since for high-speed rare¦ed gas flows it is necessary to take into account the nonequilibrium among the internal degrees of freedom, the extension of the approach to employ diatomic gas models including rotational relaxation process is a mandatory first step towards realistic simulations. Compared to previous works of Xu and coworkers, the presented scheme is de¦ned directly on the basis of kinetic models which involve a Prandtl number correction. Moreover, the methods are defined fully analytically instead of making use of Taylor expansion for the evaluation of the required derivatives. The scheme has been tested for various test cases and Mach numbers proving to produce reliable predictions in agreement with other approaches for near-continuum flows. Finally, the performance of the scheme, in terms of memory and computational time, compared to discrete velocity methods makes it a compelling alternative in place of more complex methods for hybrid simulations of weakly rarefied flows.

  3. Rarefied gas flow in a rectangular enclosure induced by non-isothermal walls

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, Manuel; Tatsios, Giorgos; Valougeorgis, Dimitris, E-mail: diva@mie.uth.gr [Department of Mechanical Engineering, University of Thessaly, 38334 Volos (Greece); Stefanov, Stefan [Institute of Mechanics, Bulgarian Academy of Sciences, Sofia (Bulgaria)

    2014-05-15

    The flow of a rarefied gas in a rectangular enclosure due to the non-isothermal walls with no synergetic contributions from external force fields is investigated. The top and bottom walls are maintained at constant but different temperatures and along the lateral walls a linear temperature profile is assumed. Modeling is based on the direct numerical solution of the Shakhov kinetic equation and the Direct Simulation Monte Carlo (DSMC) method. Solving the problem both deterministically and stochastically allows a systematic comparison and verification of the results as well as the exploitation of the numerical advantages of each approach in the investigation of the involved flow and heat transfer phenomena. The thermally induced flow is simulated in terms of three dimensionless parameters characterizing the problem, namely, the reference Knudsen number, the temperature ratio of the bottom over the top plates, and the enclosure aspect ratio. Their effect on the flow configuration and bulk quantities is thoroughly examined. Along the side walls, the gas flows at small Knudsen numbers from cold-to-hot, while as the Knudsen number is increased the gas flows from hot-to-cold and the thermally induced flow configuration becomes more complex. These flow patterns with the hot-to-cold flow to be extended to the whole length of the non-isothermal side walls may exist even at small temperature differences and then, they are enhanced as the temperature difference between the top and bottom plates is increased. The cavity aspect ratio also influences this flow configuration and the hot-to-cold flow is becoming more dominant as the depth compared to the width of the cavity is increased. To further analyze the flow patterns a novel solution decomposition into ballistic and collision parts is introduced. This is achieved by accordingly modifying the indexing process of the typical DSMC algorithm. The contribution of each part of the solution is separately examined and a physical

  4. Numerical research of the swirling supersonic gas flows in the self-vacuuming vortex tube

    Science.gov (United States)

    Volov, V. T.; Lyaskin, A. S.

    2018-03-01

    This article presents the results of simulation for a special type of vortex tubes – self-vacuuming vortex tube (SVVT), for which extreme values of temperature separation and vacuum are realized. The main results of this study are the flow structure in the SVVT and energy loss estimations on oblique shock waves, gas friction, instant expansion and organization of vortex bundles in SVVT.

  5. Attenuation of hydrogen radicals traveling under flowing gas conditions through tubes of different materials

    International Nuclear Information System (INIS)

    Grubbs, R.K.; George, S.M.

    2006-01-01

    Hydrogen radical concentrations traveling under flowing gas conditions through tubes of different materials were measured using a dual thermocouple probe. The source of the hydrogen radicals was a toroidal radio frequency plasma source operating at 2.0 and 3.3 kW for H 2 pressures of 250 and 500 mTorr, respectively. The dual thermocouple probe was comprised of exposed and covered Pt/Pt13%Rh thermocouples. Hydrogen radicals recombined efficiently on the exposed thermocouple and the energy of formation of H 2 heated the thermocouple. The second thermocouple was covered by glass and was heated primarily by the ambient gas. The dual thermocouple probe was translated and measured temperatures at different distances from the hydrogen radical source. These temperature measurements were conducted at H 2 flow rates of 35 and 75 SCCM (SCCM denotes cubic centimeter per minute at STP) inside cylindrical tubes made of stainless steel, aluminum, quartz, and Pyrex. The hydrogen radical concentrations were obtained from the temperatures of the exposed and covered thermocouples. The hydrogen concentration decreased versus distance from the plasma source. After correcting for the H 2 gas flow using a reference frame transformation, the hydrogen radical concentration profiles yielded the atomic hydrogen recombination coefficient, γ, for the four materials. The methodology of measuring the hydrogen radical concentrations, the analysis of the results under flowing gas conditions, and the determination of the atomic hydrogen recombination coefficients for various materials will help facilitate the use of hydrogen radicals for thin film growth processes

  6. INTERACTION OF LIQUID FLAT SCREENS WITH GAS FLOW RESTRICTED BY CHANNEL WALLS

    Directory of Open Access Journals (Sweden)

    S. T. Aksentiev

    2005-01-01

    Full Text Available The paper gives description of physical pattern of liquid screen interaction that are injected from the internal walls of a rectangular channel with gas flow. Criterion dependences for determination of intersection coordinates of external boundaries with longitudinal channel axis and factor of liquid screen head resistance.

  7. Modeling and experiments on differential pumping in linear plasma generators operating at high gas flows

    NARCIS (Netherlands)

    Eck, van H.J.N.; Koppers, W.R.; Rooij, van G.J.; Goedheer, W.J.; Engeln, R.A.H.; Schram, D.C.; Lopes Cardozo, N.J.; Kleyn, A.W.

    2009-01-01

    The direct simulation Monte Carlo (DSMC) method was used to investigate the efficiency of differential pumping in linear plasma generators operating at high gas flows. Skimmers are used to separate the neutrals from the plasma beam, which is guided from the source to the target by a strong axial

  8. Methanol synthesis in a countercurrent gas-solid-solid trickle flow reactor. An experimental study

    NARCIS (Netherlands)

    Kuczynski, M.; Oyevaar, M.H.; Pieters, R.T.; Westerterp, K.R.

    1987-01-01

    The synthesis of methanol from CO and H2 was executed in a gas-solid-solid trickle flow reactor. The reactor consisted of three tubular reactor sections with cooling sections in between. The catalyst was Cu on alumina, the adsorbent was a silica-alumina powder and the experimental range 498–523 K,

  9. The Cauchy problem for a model of immiscible gas flow with large data

    Energy Technology Data Exchange (ETDEWEB)

    Sande, Hilde

    2008-12-15

    The thesis consists of an introduction and two papers; 1. The solution of the Cauchy problem with large data for a model of a mixture of gases. 2. Front tracking for a model of immiscible gas flow with large data. (AG) refs, figs

  10. A comparison of hyperbolic solvers for ideal and real gas flows

    Directory of Open Access Journals (Sweden)

    R. M. L. Coelho

    2006-09-01

    Full Text Available Classical and recent numerical schemes for solving hyperbolic conservation laws were analyzed for computational efficiency and application to nonideal gas flows. The Roe-Pike approximate Riemann solver with entropy correction, the Harten second-order scheme and the extension of the Roe-Pike method to second-order by the MUSCL strategy were compared for one-dimensional flows of an ideal gas. These methods require the so-called Roe's average state, which is frequently difficult and sometimes impossible to obtain. Other methods that do not require the average state are best suited for complex equations of state. Of these, the VFRoe, AUSM+ and Hybrid Lax-Friedrich-Lax-Wendroff methods were compared for one-dimensional compressible flows of a Van der Waals gas. All methods were evaluated regarding their accuracy for given mesh sizes and their computational cost for a given solution accuracy. It was shown that, even though they require more floating points and indirect addressing operations per time step, for a given time interval for integration the second-order methods are less-time consuming than the first-order methods for a required accuracy. It was also shown that AUSM+ and VFRoe are the most accurate methods and that AUSM+ is much faster than the others, and is thus recommended for nonideal one-phase gas flows.

  11. Complex research of acoustic impact on gas-dust flow in vortex ...

    African Journals Online (AJOL)

    Complex research of acoustic impact on gas-dust flow in vortex-acoustic dispenser. ... PROMOTING ACCESS TO AFRICAN RESEARCH ... Introduction The processing of wastes from mining operations is usually related to the needs of related industries in raw materials. ... EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT

  12. A pathway to eliminate the gas flow dependency of a hydrocarbon sensor for automotive exhaust applications

    Directory of Open Access Journals (Sweden)

    G. Hagen

    2018-02-01

    Full Text Available Gas sensors will play an essential role in future combustion-based mobility to effectively reduce emissions and monitor the exhausts reliably. In particular, an application in automotive exhausts is challenging due to the high gas temperatures that come along with highly dynamic flow rates. Recently, a thermoelectric hydrocarbon sensor was developed by using materials which are well known in the exhausts and therefore provide the required stability. As a sensing mechanism, the temperature difference that is generated between a catalytically activated area during the exothermic oxidation of said hydrocarbons and an inert area of the sensor is measured by a special screen-printed thermopile structure. As a matter of principle, this thermovoltage significantly depends on the mass flow rate of the exhausts under certain conditions. The present contribution helps to understand this cross effect and proposes a possible setup for its avoidance. By installing the sensor in the correct position of a bypass solution, the gas flow around the sensor is almost free of turbulence. Now, the signal depends only on the hydrocarbon concentration and not on the gas flow. Such a setup may open up new possibilities of applying novel sensors in automotive exhausts for on-board-measurement (OBM purposes.

  13. Closed-cycle gas flow system for cooling a HTc dc-SQUID magnetometer

    NARCIS (Netherlands)

    Bosch, van den P.J.; Holland, H.J.; Brake, ter H.J.M.; Rogalla, H.

    1994-01-01

    A closed-cycle gas flow system for cooling a high-crit. temp. d.c.-superconducting quantum interference device (SQUID) magnetometer by means of a cryocooler has been designed, constructed and tested. The magnetometer is aimed to measure heart signals with a sensitivity of 0.1 pT/Hz1/2. The required

  14. Fluid dynamics characterization of riser in a FCC cold flow model using gas radiotracer

    International Nuclear Information System (INIS)

    Santos, Valdemir A. dos; Lima, Emerson A.O.

    2013-01-01

    Was carried out the characterization of a diameter small riser of a cold flow model of a circulating fluidized bed (CFB), with aid of a radioactive tracer. Compressed air and catalytic cracking of petroleum flow through solids pneumatic transport regime, made of transparent material (glass, acrylic, PVC, polycarbonate) for study of problems in Fluid Catalytic Cracking (FCC) unit and development of methods of measurement of fluid dynamic parameters. The CFB model consisted of a mixer component solid-gas (compressed air at 25 deg C and 200 kN/m 2 ; cracking catalyst with an average diameter of 72μm and specific mass of 1,500 kg/m 3 ), comprising a riser pipe glass 0.02m internal diameter and 1.8m height, a gas solid separation vessel by flash effect, with the filter in the gas outlet, and a return column (a glass tube with an internal diameter of 0.0254m) to redirect the catalyst for the riser base. Recorded data allowed studies on residence time distribution of the gaseous phase in the riser, with the identification and characterization of the flow of gas-solid components in the CFB riser of small diameter. A plug flow type with deviations due to back mixing of catalyst close to the walls, associated with the density difference between this component was observed. (author)

  15. Economic impacts of natural gas flow disruptions between Russia and the EU

    NARCIS (Netherlands)

    Bouwmeester, Maaike; Oosterhaven, Jan

    2016-01-01

    In this paper we use a non-linear programming approach to predict the wider interregional and interindustry impacts of natural gas flow disruptions. In the short run, economic actors attempt to continue their business-as-usual and follow established trade patters as closely as possible. In the model

  16. Mountain scale modeling of transient, coupled gas flow, heat transfer and carbon-14 migration

    International Nuclear Information System (INIS)

    Lu, Ning; Ross, B.

    1993-01-01

    We simulate mountain-scale coupled heat transfer and gas flow at Yucca Mountain. A coupled rock-gas flow and heat transfer model, TGIF2, is used to simulate mountain-scale two-dimensional transient heat transfer and gas flow. The model is first verified against an analytical solution for the problem of an infinite horizontal layer of fluid heated from below. Our numerical results match very well with the analytical solution. Then, we obtain transient temperature and gas flow distributions inside the mountain. These distributions are used by a transient semianalytical particle tracker to obtain carbon-14 travel times for particles starting at different locations within the repository. Assuming that the repository is filled with 30-year-old waste at an initial areal power density of 57 kw/acre, we find that repository temperatures remain above 60 degrees C for more than 10,000 years. Carbon-14 travel times to the surface are mostly less than 1000 years, for particles starting at any time within the first 10,000 years

  17. CFD modeling of particle behavior in supersonic flows with strong swirls for gas separation

    DEFF Research Database (Denmark)

    Yang, Yan; Wen, Chuang

    2017-01-01

    flow from the dry gas outlet. The separation efficiency reached over 80%, when the droplet diameter was more than 1.5 μm. The optimum length of the cyclonic separation section was approximate 16–20 times of the nozzle throat diameter to obtain higher collection efficiency for the supersonic separator...

  18. Dynamic Gas Flow Effects on the ESD of Aerospace Vehicle Surfaces

    Science.gov (United States)

    Hogue, Michael D.; Kapat, Jayanta; Ahmed, Kareem; Cox, Rachel E.; Wilson, Jennifer G.; Calle, Luz M.; Mulligan, Jaysen

    2016-01-01

    The purpose of this work is to develop a dynamic version of Paschen's Law that takes into account the flow of ambient gas past aerospace vehicle surfaces. However, the classic Paschen's Law does not take into account the flow of gas of an aerospace vehicle, whose surfaces may be triboelectrically charged by dust or ice crystal impingement, traversing the atmosphere. The basic hypothesis of this work is that the number of electron-ion pairs created per unit distance by the electric field between the electrodes is mitigated by the electron-ion pairs removed per unit distance by the flow of gas. The revised Paschen equation must be a function of the mean velocity, v(sub xm), of the ambient gas and reduces to the classical version of Paschen's law when the gas mean velocity, v(sub xm) = 0. New formulations of Paschen's Law, taking into account Mach number and dynamic pressure, derived by the authors, will be discussed. These equations will be evaluated by wind tunnel experimentation later this year. Based on the results of this work, it is hoped that the safety of aerospace vehicles will be enhanced with a redefinition of electrostatic launch commit criteria. It is also possible that new products, such as new anti-static coatings, may be formulated from this data.

  19. Thermocapillary and shear driven flows in gas/liquid system in annular duct

    International Nuclear Information System (INIS)

    Gaponenko, Yu; Shevtsova, V; Nepomnyashchy, A

    2011-01-01

    We report the results of numerical study of two-phase flows in annulus for different aspect ratios obtained in the frame of the JEREMI experiment preparation. The geometry of the physical problem is a cylindrical and non-deformable liquid bridge concentrically surrounded by an annular gas channel under conditions of zero gravity. Thermocapillary (Marangoni) convection in liquid bridge of Pr = 68 is analyzed in the case when the interface is subjected to an axial gas stream. The gas flow is counter-directed with respect to the Marangoni flow. The inlet gas velocity U 0 g , temperature difference ΔT between end rods of the liquid bridge and aspect ratio are the control parameters of the system. In the case when the gas stream comes from the cold side, it cools down the interface to a temperature lower than that of the liquid beneath, and in a certain region of the parameter space that cooling causes instability due to a temperature difference in the direction, perpendicular to the interface. The present study is focused on the influence of the aspect ratio on the existence and characteristic features of the oscillatory regime.

  20. Counter-Rotatable Fan Gas Turbine Engine with Axial Flow Positive Displacement Worm Gas Generator

    Science.gov (United States)

    Giffin, Rollin George (Inventor); Murrow, Kurt David (Inventor); Fakunle, Oladapo (Inventor)

    2014-01-01

    A counter-rotatable fan turbine engine includes a counter-rotatable fan section, a worm gas generator, and a low pressure turbine to power the counter-rotatable fan section. The low pressure turbine maybe counter-rotatable or have a single direction of rotation in which case it powers the counter-rotatable fan section through a gearbox. The gas generator has inner and outer bodies having offset inner and outer axes extending through first, second, and third sections of a core assembly. At least one of the bodies is rotatable about its axis. The inner and outer bodies have intermeshed inner and outer helical blades wound about the inner and outer axes and extending radially outwardly and inwardly respectively. The helical blades have first, second, and third twist slopes in the first, second, and third sections respectively. A combustor section extends through at least a portion of the second section.

  1. Energy Efficient Thermal Management for Natural Gas Engine Aftertreatment via Active Flow Control

    Energy Technology Data Exchange (ETDEWEB)

    David K. Irick; Ke Nguyen; Vitacheslav Naoumov; Doug Ferguson

    2006-04-01

    The project is focused on the development of an energy efficient aftertreatment system capable of reducing NOx and methane by 90% from lean-burn natural gas engines by applying active exhaust flow control. Compared to conventional passive flow-through reactors, the proposed scheme cuts supplemental energy by 50%-70%. The system consists of a Lean NOx Trap (LNT) system and an oxidation catalyst. Through alternating flow control, a major amount of engine exhaust flows through a large portion of the LNT system in the absorption mode, while a small amount of exhaust goes through a small portion of the LNT system in the regeneration or desulfurization mode. By periodically reversing the exhaust gas flow through the oxidation catalyst, a higher temperature profile is maintained in the catalyst bed resulting in greater efficiency of the oxidation catalyst at lower exhaust temperatures. The project involves conceptual design, theoretical analysis, computer simulation, prototype fabrication, and empirical studies. This report details the progress during the first twelve months of the project. The primary activities have been to develop the bench flow reactor system, develop the computer simulation and modeling of the reverse-flow oxidation catalyst, install the engine into the test cell, and begin design of the LNT system.

  2. A method for measuring the local gas pressure within a gas-flow stage in situ in the transmission electron microscope

    International Nuclear Information System (INIS)

    Colby, R.; Alsem, D.H.; Liyu, A.; Kabius, B.

    2015-01-01

    Environmental transmission electron microscopy (TEM) has enabled in situ experiments in a gaseous environment with high resolution imaging and spectroscopy. Addressing scientific challenges in areas such as catalysis, corrosion, and geochemistry can require pressures much higher than the ∼20 mbar achievable with a differentially pumped environmental TEM. Gas flow stages, in which the environment is contained between two semi-transparent thin membrane windows, have been demonstrated at pressures of several atmospheres. However, the relationship between the pressure at the sample and the pressure drop across the system is not clear for some geometries. We demonstrate a method for measuring the gas pressure at the sample by measuring the ratio of elastic to inelastic scattering and the defocus of the pair of thin windows. This method requires two energy filtered high-resolution TEM images that can be performed during an ongoing experiment, at the region of interest. The approach is demonstrated to measure greater than atmosphere pressures of N 2 gas using a commercially available gas-flow stage. This technique provides a means to ensure reproducible sample pressures between different experiments, and even between very differently designed gas-flow stages. - Highlights: • Method developed for measuring gas pressure within a gas-flow stage in the TEM. • EFTEM and CTF-fitting used to calculate amount and volume of gas. • Requires only a pair of images without leaving region of interest. • Demonstrated for P > 1 atm with a common commercial gas-flow stage

  3. Pore-scale mechanisms of gas flow in tight sand reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Silin, D.; Kneafsey, T.J.; Ajo-Franklin, J.B.; Nico, P.

    2010-11-30

    Tight gas sands are unconventional hydrocarbon energy resource storing large volume of natural gas. Microscopy and 3D imaging of reservoir samples at different scales and resolutions provide insights into the coaredo not significantly smaller in size than conventional sandstones, the extremely dense grain packing makes the pore space tortuous, and the porosity is small. In some cases the inter-granular void space is presented by micron-scale slits, whose geometry requires imaging at submicron resolutions. Maximal Inscribed Spheres computations simulate different scenarios of capillary-equilibrium two-phase fluid displacement. For tight sands, the simulations predict an unusually low wetting fluid saturation threshold, at which the non-wetting phase becomes disconnected. Flow simulations in combination with Maximal Inscribed Spheres computations evaluate relative permeability curves. The computations show that at the threshold saturation, when the nonwetting fluid becomes disconnected, the flow of both fluids is practically blocked. The nonwetting phase is immobile due to the disconnectedness, while the permeability to the wetting phase remains essentially equal to zero due to the pore space geometry. This observation explains the Permeability Jail, which was defined earlier by others. The gas is trapped by capillarity, and the brine is immobile due to the dynamic effects. At the same time, in drainage, simulations predict that the mobility of at least one of the fluids is greater than zero at all saturations. A pore-scale model of gas condensate dropout predicts the rate to be proportional to the scalar product of the fluid velocity and pressure gradient. The narrowest constriction in the flow path is subject to the highest rate of condensation. The pore-scale model naturally upscales to the Panfilov's Darcy-scale model, which implies that the condensate dropout rate is proportional to the pressure gradient squared. Pressure gradient is the greatest near the

  4. Study on the emission characteristics of cathodes in an ionized gas flow

    International Nuclear Information System (INIS)

    Maslennikov, N.M.

    1975-01-01

    Emission characteristics of molybdenum, tungsten and tantalum cathodes in a flow of argon and argon-potassium plasma with gas pressure of 0.04 atm, 1 atm and 0.25 atm were investigated. Gas was heated in a plasmatron. Measuring electrodes were arranged across the gas flow. Investigations in an argon plasma were carried out with the object of comparing of current-voltage dependences for potassium-activated and nonactivated cathodes. In all cases the current-voltage characteristics were growing. No saturation was observed of a current between accurent electrodes. The increase of a current between the cathodes due to the thermionic emission from the cathode began to effect at the cathode temperature of 2.470 K. The work function was found to be 5 to 5.2 ev. The comparison of the results obtained experimentally in the paper show a qualitative coincidence with calculations by some authors and a discrepancy with theoretical conceptions of other authors

  5. Numerical investigations of the fluid flows at deep oceanic and arctic permafrost-associated gas hydrate deposits

    Science.gov (United States)

    Frederick, Jennifer Mary

    , allows us a unique opportunity to study the response of methane hydrate deposits to warming. Gas hydrate stability in the Arctic and the permeability of the shelf sediments to gas migration is thought to be closely linked with relict submarine permafrost. Submarine permafrost extent depends on several environmental factors, such as the shelf lithology, sea level variations, mean annual air temperature, ocean bottom water temperature, geothermal heat flux, groundwater hydrology, and the salinity of the pore water. Effects of submarine groundwater discharge, which introduces fresh terrestrial groundwater off-shore, can freshen deep marine sediments and is an important control on the freezing point depression of ice and methane hydrate. While several thermal modeling studies suggest the permafrost layer should still be largely intact near-shore, many recent field studies have reported elevated methane levels in Arctic coastal waters. The permafrost layer is thought to create an impermeable barrier to fluid and gas flow, however, talik formation (unfrozen regions within otherwise continuous permafrost) below paleo-river channels can create permeable pathways for gas migration from depth. This is the first study of its kind to make predictions of the methane gas flux to the water column from the Arctic shelf sediments using a 2D multi-phase fluid flow model. Model results show that the dissociation of methane hydrate deposits through taliks can supersaturate the overlying water column at present-day relative to equilibrium with the atmosphere when taliks are large (> 1 km width) or hydrate saturation is high within hydrate layers (> 50% pore volume). Supersaturated waters likely drive a net flux of methane into the atmosphere, a potent greenhouse gas. Effects of anthropogenic global warming will certainly increase gas venting rates if ocean bottom water temperatures increase, but likely won't have immediately observable impacts due to the long response times.

  6. A Global Meta-Analysis on the Impact of Management Practices on Net Global Warming Potential and Greenhouse Gas Intensity from Cropland Soils

    Science.gov (United States)

    Sainju, Upendra M.

    2016-01-01

    Management practices, such as tillage, crop rotation, and N fertilization, may affect net global warming potential (GWP) and greenhouse gas intensity (GHGI), but their global impact on cropland soils under different soil and climatic conditions need further evaluation. Available global data from 57 experiments and 225 treatments were evaluated for individual and combined effects of tillage, cropping systems, and N fertilization rates on GWP and GHGI which accounted for CO2 equivalents from N2O and CH4 emissions with or without equivalents from soil C sequestration rate (ΔSOC), farm operations, and N fertilization. The GWP and GHGI were 66 to 71% lower with no-till than conventional till and 168 to 215% lower with perennial than annual cropping systems, but 41 to 46% greater with crop rotation than monocroppping. With no-till vs. conventional till, GWP and GHGI were 2.6- to 7.4-fold lower when partial than full accounting of all sources and sinks of greenhouse gases (GHGs) were considered. With 100 kg N ha-1, GWP and GHGI were 3.2 to 11.4 times greater with partial than full accounting. Both GWP and GHGI increased curvilinearly with increased N fertilization rate. Net GWP and GHGI were 70 to 87% lower in the improved combined management that included no-till, crop rotation/perennial crop, and reduced N rate than the traditional combined management that included conventional till, monocopping/annual crop, and recommended N rate. An alternative soil respiration method, which replaces ΔSOC by soil respiration and crop residue returned to soil in the previous year, similarly reduced GWP and GHGI by 133 to 158% in the improved vs. the traditional combined management. Changes in GWP and GHGI due to improved vs. traditional management varied with the duration of the experiment and inclusion of soil and climatic factors in multiple linear regressions improved their relationships. Improved management practices reduced GWP and GHGI compared with traditional management

  7. A Global Meta-Analysis on the Impact of Management Practices on Net Global Warming Potential and Greenhouse Gas Intensity from Cropland Soils.

    Science.gov (United States)

    Sainju, Upendra M

    2016-01-01

    Management practices, such as tillage, crop rotation, and N fertilization, may affect net global warming potential (GWP) and greenhouse gas intensity (GHGI), but their global impact on cropland soils under different soil and climatic conditions need further evaluation. Available global data from 57 experiments and 225 treatments were evaluated for individual and combined effects of tillage, cropping systems, and N fertilization rates on GWP and GHGI which accounted for CO2 equivalents from N2O and CH4 emissions with or without equivalents from soil C sequestration rate (ΔSOC), farm operations, and N fertilization. The GWP and GHGI were 66 to 71% lower with no-till than conventional till and 168 to 215% lower with perennial than annual cropping systems, but 41 to 46% greater with crop rotation than monocroppping. With no-till vs. conventional till, GWP and GHGI were 2.6- to 7.4-fold lower when partial than full accounting of all sources and sinks of greenhouse gases (GHGs) were considered. With 100 kg N ha-1, GWP and GHGI were 3.2 to 11.4 times greater with partial than full accounting. Both GWP and GHGI increased curvilinearly with increased N fertilization rate. Net GWP and GHGI were 70 to 87% lower in the improved combined management that included no-till, crop rotation/perennial crop, and reduced N rate than the traditional combined management that included conventional till, monocopping/annual crop, and recommended N rate. An alternative soil respiration method, which replaces ΔSOC by soil respiration and crop residue returned to soil in the previous year, similarly reduced GWP and GHGI by 133 to 158% in the improved vs. the traditional combined management. Changes in GWP and GHGI due to improved vs. traditional management varied with the duration of the experiment and inclusion of soil and climatic factors in multiple linear regressions improved their relationships. Improved management practices reduced GWP and GHGI compared with traditional management

  8. Numerical simulation of gas flow through unsaturated fractured rock at Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Cooper, C.A.

    1990-01-01

    Numerical analysis is used to identify the physical phenomena associated with barometrically driven gas (air and water vapor) flow through unsaturated fractured rock at Yucca Mountain, Nevada. Results from simple finite difference simulations indicate that for a fractured rock scenario, the maximum velocity of air out of an uncased 10 cm borehole is 0.002 m s -1 . An equivalent porous medium (EPM) model was incorporated into a multiphase, multicomponent simulator to test more complex conceptual models. Results indicate that for a typical June day, a diurnal pressure wave propagates about 160 m into the surrounding Tiva Canyon hydrogeologic unit. Dry air that enters the formation evaporates water around the borehole which reduces capillary pressure. Multiphase countercurrent flow develops in the vicinity of the hole; the gas phase flows into the formation while the liquid phase flows toward the borehole. The effect occurs within 0.5 m of the borehole. The amount of water vapor leaving the formation during 1 day is 900 cm 3 . This is less than 0.1% of the total recharge into the formation, suggesting that the barometric effect may be insignificant in drying the unsaturated zone. However, gas phase velocities out of the borehole (3 m s -1 ), indicating that observed flow rates from wells along the east flank of Yucca Mountain were able to be simulated with a barometric model

  9. Viscous slip coefficients for binary gas mixtures measured from mass flow rates through a single microtube

    Science.gov (United States)

    Yamaguchi, H.; Takamori, K.; Perrier, P.; Graur, I.; Matsuda, Y.; Niimi, T.

    2016-09-01

    The viscous slip coefficient for helium-argon binary gas mixture is extracted from the experimental values of the mass flow rate through a microtube. The mass flow rate is measured by the constant-volume method. The viscous slip coefficient was obtained by identifying the measured mass flow rate through a microtube with the corresponding analytical expression, which is a function of the Knudsen number. The measurements were carried out in the slip flow regime where the first-order slip boundary condition can be applied. The measured viscous slip coefficients of binary gas mixtures exhibit a concave function of the molar ratio of the mixture, showing a similar profile with numerical results. However, from the detailed comparison between the measured and numerical values with the complete and incomplete accommodation at a surface, it is inappropriate to estimate the viscous slip coefficient for the mixture numerically by employing separately measured tangential momentum accommodation coefficient for each component. The time variation of the molar ratio in the downstream chamber was measured by sampling the gas from the chamber using the quadrupole mass spectrometer. In our measurements, it is indicated that the volume flow rate of argon is larger than that of helium because of the difference in the tangential momentum accommodation coefficient.

  10. Production of Natural Gas and Fluid Flow in Tight Sand Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Maria Cecilia Bravo

    2006-06-30

    This document reports progress of this research effort in identifying relationships and defining dependencies between macroscopic reservoir parameters strongly affected by microscopic flow dynamics and production well performance in tight gas sand reservoirs. These dependencies are investigated by identifying the main transport mechanisms at the pore scale that should affect fluids flow at the reservoir scale. A critical review of commercial reservoir simulators, used to predict tight sand gas reservoir, revealed that many are poor when used to model fluid flow through tight reservoirs. Conventional simulators ignore altogether or model incorrectly certain phenomena such as, Knudsen diffusion, electro-kinetic effects, ordinary diffusion mechanisms and water vaporization. We studied the effect of Knudsen's number in Klinkenberg's equation and evaluated the effect of different flow regimes on Klinkenberg's parameter b. We developed a model capable of explaining the pressure dependence of this parameter that has been experimentally observed, but not explained in the conventional formalisms. We demonstrated the relevance of this, so far ignored effect, in tight sands reservoir modeling. A 2-D numerical simulator based on equations that capture the above mentioned phenomena was developed. Dynamic implications of new equations are comprehensively discussed in our work and their relative contribution to the flow rate is evaluated. We performed several simulation sensitivity studies that evidenced that, in general terms, our formalism should be implemented in order to get more reliable tight sands gas reservoirs' predictions.

  11. Effect of inlet and outlet flow conditions on natural gas parameters in supersonic separation process.

    Directory of Open Access Journals (Sweden)

    Yan Yang

    Full Text Available A supersonic separator has been introduced to remove water vapour from natural gas. The mechanisms of the upstream and downstream influences are not well understood for various flow conditions from the wellhead and the back pipelines. We used a computational model to investigate the effect of the inlet and outlet flow conditions on the supersonic separation process. We found that the shock wave was sensitive to the inlet or back pressure compared to the inlet temperature. The shock position shifted forward with a higher inlet or back pressure. It indicated that an increasing inlet pressure declined the pressure recovery capacity. Furthermore, the shock wave moved out of the diffuser when the ratio of the back pressure to the inlet one was greater than 0.75, in which the state of the low pressure and temperature was destroyed, resulting in the re-evaporation of the condensed liquids. Natural gas would be the subsonic flows in the whole supersonic separator, if the mass flow rate was less than the design value, and it could not reach the low pressure and temperature for the condensation and separation of the water vapor. These results suggested a guidance mechanism for natural gas supersonic separation in various flow conditions.

  12. Water-saving ground cover rice production system reduces net greenhouse gas fluxes in an annual rice-based cropping system

    Science.gov (United States)

    Yao, Z.; Du, Y.; Tao, Y.; Zheng, X.; Liu, C.; Lin, S.; Butterbach-Bahl, K.

    2014-11-01

    To safeguard food security and preserve precious water resources, the technology of water-saving ground cover rice production system (GCRPS) is being increasingly adopted for rice cultivation. However, changes in soil water status and temperature under GCRPS may affect soil biogeochemical processes that control the biosphere-atmosphere exchanges of methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2). The overall goal of this study is to better understand how net ecosystem greenhouse gas exchanges (NEGE) and grain yields are affected by GCRPS in an annual rice-based cropping system. Our evaluation was based on measurements of the CH4 and N2O fluxes and soil heterotrophic respiration (CO2 emissions) over a complete year, and the estimated soil carbon sequestration intensity for six different fertilizer treatments for conventional paddy and GCRPS. The fertilizer treatments included urea application and no N fertilization for both conventional paddy (CUN and CNN) and GCRPS (GUN and GNN), and solely chicken manure (GCM) and combined urea and chicken manure applications (GUM) for GCRPS. Averaging across all the fertilizer treatments, GCRPS increased annual N2O emission and grain yield by 40 and 9%, respectively, and decreased annual CH4 emission by 69%, while GCRPS did not affect soil CO2 emissions relative to the conventional paddy. The annual direct emission factors of N2O were 4.01, 0.09 and 0.50% for GUN, GCM and GUM, respectively, and 1.52% for the conventional paddy (CUN). The annual soil carbon sequestration intensity under GCRPS was estimated to be an average of -1.33 Mg C ha-1 yr-1, which is approximately 44% higher than the conventional paddy. The annual NEGE were 10.80-11.02 Mg CO2-eq ha-1 yr-1 for the conventional paddy and 3.05-9.37 Mg CO2-eq ha-1 yr-1 for the GCRPS, suggesting the potential feasibility of GCRPS in reducing net greenhouse effects from rice cultivation. Using organic fertilizers for GCRPS considerably reduced annual emissions of CH4

  13. Water Saturation Relations and Their Diffusion-Limited Equilibration in Gas Shale: Implications for Gas Flow in Unconventional Reservoirs

    Science.gov (United States)

    Tokunaga, Tetsu K.; Shen, Weijun; Wan, Jiamin; Kim, Yongman; Cihan, Abdullah; Zhang, Yingqi; Finsterle, Stefan

    2017-11-01

    Large volumes of water are used for hydraulic fracturing of low permeability shale reservoirs to stimulate gas production, with most of the water remaining unrecovered and distributed in a poorly understood manner within stimulated regions. Because water partitioning into shale pores controls gas release, we measured the water saturation dependence on relative humidity (rh) and capillary pressure (Pc) for imbibition (adsorption) as well as drainage (desorption) on samples of Woodford Shale. Experiments and modeling of water vapor adsorption into shale laminae at rh = 0.31 demonstrated that long times are needed to characterize equilibrium in larger (5 mm thick) pieces of shales, and yielded effective diffusion coefficients from 9 × 10-9 to 3 × 10-8 m2 s-1, similar in magnitude to the literature values for typical low porosity and low permeability rocks. Most of the experiments, conducted at 50°C on crushed shale grains in order to facilitate rapid equilibration, showed significant saturation hysteresis, and that very large Pc (˜1 MPa) are required to drain the shales. These results quantify the severity of the water blocking problem, and suggest that gas production from unconventional reservoirs is largely associated with stimulated regions that have had little or no exposure to injected water. Gravity drainage of water from fractures residing above horizontal wells reconciles gas production in the presence of largely unrecovered injected water, and is discussed in the broader context of unsaturated flow in fractures.

  14. Modeling the scooping phenomenon for the heat transfer in liquid–gas horizontal slug flows

    International Nuclear Information System (INIS)

    Bassani, Carlos L.; Pereira, Fernando H.G.; Barbuto, Fausto A.A.; Morales, Rigoberto E.M.

    2016-01-01

    Highlights: • A low computational tool for heat transfer prediction on slug flows is presented. • The scooping phenomenon is modeled on a stationary approach. • The scooping phenomenon improved in 8% the heat transfer results. - Abstract: The heat transfer between the deep sea waters and the oil and gas mixtures flowing through production lines is a common situation in the petroleum industry. The optimum prediction of the liquid–gas flow parameters along those lines, when the intermittent flow pattern known as slug flow is dominant, has extreme importance in facilities' design. The mixture temperature drop caused by the colder sea waters, which can be regarded as an infinite medium with constant temperature, directly affects physical properties of the fluids such as the viscosity and specific mass. Gas expansion may also occur due to pressure and temperature gradients, thus changing the flow hydrodynamics. Finally, the temperature gradient affects the thermodynamic equilibrium between the phases, favoring wax deposition and thus increasing pressure drops or even blocking the production line. With those issues in mind, the present work proposes a stationary model to predict the mixture temperature distribution and the two-phase flow heat transfer coefficient based on the mass, momentum and energy conservation equations applied to different unit cell regions. The main contribution of the present work is the modeling of the thermal scooping phenomenon, i.e., the heat transfer between two adjacent unit cells due to the mass flux known as scooping. The model was implemented as a structured Fortran95 code with an upwind difference scheme. The results were compared to experimental data and presented good agreement. The analysis showed that the inclusion of the scooping phenomenon into the model resulted in an averaged 8% improvement in the temperature gradient calculation and heat transfer coefficient prediction for the flowing mixture.

  15. Implicit unified gas-kinetic scheme for steady state solutions in all flow regimes

    Science.gov (United States)

    Zhu, Yajun; Zhong, Chengwen; Xu, Kun

    2016-06-01

    This paper presents an implicit unified gas-kinetic scheme (UGKS) for non-equilibrium steady state flow computation. The UGKS is a direct modeling method for flow simulation in all regimes with the updates of both macroscopic flow variables and microscopic gas distribution function. By solving the macroscopic equations implicitly, a predicted equilibrium state can be obtained first through iterations. With the newly predicted equilibrium state, the evolution equation of the gas distribution function and the corresponding collision term can be discretized in a fully implicit way for fast convergence through iterations as well. The lower-upper symmetric Gauss-Seidel (LU-SGS) factorization method is implemented to solve both macroscopic and microscopic equations, which improves the efficiency of the scheme. Since the UGKS is a direct modeling method and its physical solution depends on the mesh resolution and the local time step, a physical time step needs to be fixed before using an implicit iterative technique with a pseudo-time marching step. Therefore, the physical time step in the current implicit scheme is determined by the same way as that in the explicit UGKS for capturing the physical solution in all flow regimes, but the convergence to a steady state speeds up through the adoption of a numerical time step with large CFL number. Many numerical test cases in different flow regimes from low speed to hypersonic ones, such as the Couette flow, cavity flow, and the flow passing over a cylinder, are computed to validate the current implicit method. The overall efficiency of the implicit UGKS can be improved by one or two orders of magnitude in comparison with the explicit one.

  16. CFD study of the heat transfer between a dilute gas particle suspension flow and an obstruction

    International Nuclear Information System (INIS)

    Nguyen, A.V.; Fletcher, C.A.J.

    1999-01-01

    The effect on heat transfer of solid particles suspended in a gas flow is of considerable importance in a number of industrial applications, ranging from coal combustion equipment and heat exchangers to catalytic reaction or cooling of nuclear reactors using gas graphite dust suspensions. Here, the heat transfer process between a dilute gas-particle suspension flow and an obstruction has been numerically investigated employing a novel Eulerian formulation for dilute gas particle suspension flows, which allows interaction of the key mechanisms to be quantified for the first time. As the particle reflection occurs around the obstruction, the heat transfer process has been modeled taking into account the incident and reflected particles explicitly. In the energy equations these particle families are treated separately. Only the effect on the gas convective heat transfer is expected to be of primary significance and investigated. The numerical computation is performed using the commercial computational fluid dynamics code, FLUENT, with the User Defined Subroutines. The authors study the heat transfer process between a dilute gas particle flow and an obstruction with simple geometries such as a 45 degree ramp and a cylindrical tube. The theoretical results for the latter case are compared with the available experimental data. The numerical simulation shows that both the particle size and the particle concentration (in the thermal boundary layer) affect the heat transfer process. Since both the particle incidence and reflection depend on the particle size and strongly influence the particle concentration distribution, they have to be physically correctly treated in the modeling of the heat transfer, as is demonstrated in the novel formulation. There is an optimum particle size for a maximum enhancement of the heat transfer. The particle concentration increases the efficiency of the heat transfer process expressed in terms of the local Nusselt numbers

  17. Evaluating renewable natural resources flow and net primary productivity with a GIS-Emergy approach: A case study of Hokkaido, Japan.

    Science.gov (United States)

    Wang, Chengdong; Zhang, Shenyan; Yan, Wanglin; Wang, Renqing; Liu, Jian; Wang, Yutao

    2016-11-18

    Renewable natural resources, such as solar radiation, rainfall, wind, and geothermal heat, together with ecosystem services, provide the elementary supports for the sustainable development of human society. To improve regional sustainability, we studied the spatial distributions and quantities of renewable natural resources and net primary productivity (NPP) in Hokkaido, which is the second largest island of Japan. With the help of Geographic Information System (GIS) software, distribution maps for each type of renewable natural resource were generated by kriging interpolation based on statistical records. A composite map of the flow of all types of renewable natural resources was also generated by map layer overlapping. Additionally, we utilized emergy analysis to convert each renewable flow with different attributes into a unified unit (i.e., solar equivalent joules [sej]). As a result, the spatial distributions of the flow of renewable natural resources of the Hokkaido region are presented in the form of thematic emergy maps. Thus, the areas with higher renewable emergy can be easily visualized and identified. The dominant renewable flow in certain areas can also be directly distinguished. The results can provide useful information for regional sustainable development, environmental conservation and ecological management.

  18. System for measurement and automatic regulation of gas flow within an oil aging test device

    Directory of Open Access Journals (Sweden)

    Žigić Aleksandar

    2014-01-01

    Full Text Available This paper describes a system within an oil aging test device that serves for measurement and automatic regulation of gas flow. Following an already realized system that continuously monitors, logs, and regulates transformer oil temperature during the aging process and maintains temperature consistency within strict limits, a model of a flow meter and regulator of air or oxygen through transformer oil samples is developed. A special feature of the implemented system is the measurement of very small gas flows. A short technical description of the realized system is given with a functional block diagram. The basic technical characteristics of the system are specified, and the operating principles and application of the system are described. The paper also gives performance test results in a real exploitation environment.

  19. Forming of film surface of very viscous liquid flowing with gas in pipes

    Directory of Open Access Journals (Sweden)

    Czernek Krystian

    2017-01-01

    Full Text Available The study presents the possible use of optoelectronic system for the measurement of the values, which are specific for hydrodynamics of two-phase gas liquid flow in vertical pipes, where a very-high-viscosity liquid forms a falling film in a pipe. The experimental method was provided, and the findings were presented and analysed for selected values, which characterize the two-phase flow. Attempt was also made to evaluate the effects of flow parameters and properties of the liquid on the gas-liquid interface value, which is decisive for the conditions of heat exchange and mass transfer in falling film equipment. The nature and form of created waves at various velocities were also described.

  20. Developments in greenhouse gas emissions and net energy use in Danish agriculture - How to achieve substantial CO2 reductions?

    International Nuclear Information System (INIS)

    Dalgaard, T.; Olesen, J.E.; Petersen, S.O.; Petersen, B.M.; Jorgensen, U.; Kristensen, T.; Hutchings, N.J.; Gyldenkaerne, S.; Hermansen, J.E.

    2011-01-01

    Greenhouse gas (GHG) emissions from agriculture are a significant contributor to total Danish emissions. Consequently, much effort is currently given to the exploration of potential strategies to reduce agricultural emissions. This paper presents results from a study estimating agricultural GHG emissions in the form of methane, nitrous oxide and carbon dioxide (including carbon sources and sinks, and the impact of energy consumption/bioenergy production) from Danish agriculture in the years 1990-2010. An analysis of possible measures to reduce the GHG emissions indicated that a 50-70% reduction of agricultural emissions by 2050 relative to 1990 is achievable, including mitigation measures in relation to the handling of manure and fertilisers, optimization of animal feeding, cropping practices, and land use changes with more organic farming, afforestation and energy crops. In addition, the bioenergy production may be increased significantly without reducing the food production, whereby Danish agriculture could achieve a positive energy balance. - Highlights: → GHG emissions from Danish agriculture 1990-2010 are calculated, including carbon sequestration. → Effects of measures to further reduce GHG emissions are listed. → Land use scenarios for a substantially reduced GHG emission by 2050 are presented. → A 50-70% reduction of agricultural emissions by 2050 relative to 1990 is achievable. → Via bioenergy production Danish agriculture could achieve a positive energy balance. - Scenario studies of greenhouse gas mitigation measures illustrate the possible realization of CO 2 reductions for Danish agriculture by 2050, sustaining current food production.