WorldWideScience

Sample records for net gas flow

  1. 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...

  2. 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

  3. 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

  4. Thermographic study of gas flows

    Directory of Open Access Journals (Sweden)

    Elistratov S.L.

    2015-01-01

    Full Text Available To visualize the temperature field, thin threads and nets with different heat conductivity were located directly at the outlet or at some distance from the channel. This method allows to investigate fields of temperatures for diagnostics of streams of gas in channels of the modern heat exchangers and reactors.

  5. 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

  6. Software Tool Integrating Data Flow Diagrams and Petri Nets

    Science.gov (United States)

    Thronesbery, Carroll; Tavana, Madjid

    2010-01-01

    Data Flow Diagram - Petri Net (DFPN) is a software tool for analyzing other software to be developed. The full name of this program reflects its design, which combines the benefit of data-flow diagrams (which are typically favored by software analysts) with the power and precision of Petri-net models, without requiring specialized Petri-net training. (A Petri net is a particular type of directed graph, a description of which would exceed the scope of this article.) DFPN assists a software analyst in drawing and specifying a data-flow diagram, then translates the diagram into a Petri net, then enables graphical tracing of execution paths through the Petri net for verification, by the end user, of the properties of the software to be developed. In comparison with prior means of verifying the properties of software to be developed, DFPN makes verification by the end user more nearly certain, thereby making it easier to identify and correct misconceptions earlier in the development process, when correction is less expensive. After the verification by the end user, DFPN generates a printable system specification in the form of descriptions of processes and data.

  7. 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...

  8. 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...

  9. 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.

  10. 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...

  11. Gas flow path for a gas turbine engine

    Science.gov (United States)

    Montgomery, Matthew D.; Charron, Richard C.; Snyder, Gary D.; Pankey, William W.; Mayer, Clinton A.; Hettinger, Benjamin G.

    2017-03-14

    A duct arrangement in a can annular gas turbine engine. The gas turbine engine has a gas delivery structure for delivering gases from a plurality of combustors to an annular chamber that extends circumferentially and is oriented concentric to a gas turbine engine longitudinal axis for delivering the gas flow to a first row of blades A gas flow path is formed by the duct arrangement between a respective combustor and the annular chamber for conveying gases from each combustor to the first row of turbine blades The duct arrangement includes at least one straight section having a centerline that is misaligned with a centerline of the combustor.

  12. HVOF gas flow field characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Swank, W.D.; Fincke, J.R.; Haggard, D.C. [Idaho National Engineering Lab., Idaho Falls, ID (United States); Irons, G. [Hobart Tafa Technologies Inc., Concord, NH (United States)

    1994-12-31

    The effects of combustion chamber pressure and fuel/oxygen mixture ratio on the characteristics of a high pressure, supersonic HVOF gun are examined experimentally and theoretically. The measured temperature, velocity and entrained air fraction are obtained from an enthalpy probe/mass spectrometer system. Predictions of combustion chamber flame temperature and composition are calculated with an equilibrium combustion model. Nozzle and barrel exit conditions are calculated using a one-dimensional rocket performance model. The calculations are bounded by the assumption of frozen and equilibrium compositions. Comparisons between measurements and the predictions indicate that the flow field is far from chemical equilibrium. The aerodynamic force available for accelerating a particle is primarily controlled by the chamber pressure while the composition and temperature of the gas surrounding the particles is controlled by the mixture ratio.

  13. Swirling flow of a dissociated gas

    Science.gov (United States)

    Wolfram, W. R., Jr.; Walker, W. F.

    1975-01-01

    Most physical applications of the swirling flow, defined as a vortex superimposed on an axial flow in the nozzle, involve high temperatures and the possibility of real gas effects. The generalized one-dimensional swirling flow in a converging-diverging nozzle is analyzed for equilibrium and frozen dissociation using the ideal dissociating gas model. Numerical results are provided to illustrate the major effects and to compare with results obtained for a perfect gas with constant ratio of specific heats. It is found that, even in the case of real gases, perfect gas calculations can give a good estimate of the reduction in mass flow due to swirl.

  14. 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...

  15. Investigation of gas flow in SAGD

    Energy Technology Data Exchange (ETDEWEB)

    Canas, C.; Kantzas, A. [Calgary Univ., AB (Canada); Edmunds, N. [Laricina Energy Ltd., Calgary, AB (Canada)

    2009-07-01

    Non-condensable gases play an important role in the thermal efficiency of steam assisted gravity drainage (SAGD) processes. The accurate characterization of gas flow in SAGD is needed in order to predicts its potential impact on process performance. This study used flow equations to describe viscous drag in a gas-water-oil system. A 3-phase flow analysis was used to predict the amount of gas produced by viscous drag in 2 geometries: (1) flow in a capillary tube; and (2) the flow of a descending film on a plate. The functionality analysis described the response of the dragged gas to changes in operating and reservoir conditions. A 12.6{sup 3} oil draining zone volume was modelled as a bundle of capillaries with a porosity of 0.35. Capillary length was 2 meters. Results of the study showed that a portion of the gas in the steam chamber flows downwards, and was caused by the viscous drag of the falling liquids. Momentum transfer was highly dependent on operational and reservoir conditions. It was concluded that amounts of gas that flow downwards will increase when operating temperatures increase in the SAGD chamber. 17 refs., 1 tab., 10 figs.

  16. 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.

  17. Argon gas flow through glass nanopipette

    Science.gov (United States)

    Takami, Tomohide; Nishimoto, Kiwamu; Goto, Tadahiko; Ogawa, Shuichi; Iwata, Futoshi; Takakuwa, Yuji

    2016-12-01

    We have observed the flow of argon gas through a glass nanopipette in vacuum. A glass nanopipette with an inner diameter of 100 nm and a shank length of 3 mm was set between vacuum chambers, and argon gas was introduced from the top of the nanopipette to the bottom. The exit pressure was monitored with an increase in entrance pressure in the range of 50-170 kPa. Knudsen flow was observed at an entrance pressure lower than 100 kPa, and Poiseuille flow was observed at an entrance pressure higher than 120 kPa. The proposed pressure-dependent gas flow method provides a means of evaluating the glass nanopipette before using it for various applications including nanodeposition to surfaces and femtoinjection to living cells.

  18. 40 CFR 89.416 - Raw exhaust gas flow.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Raw exhaust gas flow. 89.416 Section... Procedures § 89.416 Raw exhaust gas flow. The exhaust gas flow shall be determined by one of the methods...) Measurement of the air flow and the fuel flow by suitable metering systems (for details see SAE J244. This...

  19. Net infiltration of the Death Valley regional ground-water flow system, Nevada and California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Recharge in the Death Valley regional ground-water flow system (DVRFS) was estimated from net infiltration simulated by Hevesi and others (2003) using a...

  20. 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.

  1. Flow splitter controls dual gas well

    Energy Technology Data Exchange (ETDEWEB)

    Rock, W.A.

    1973-02-01

    Originally designed to equalize 2 rates of flow in a direct-fired low pressure steam superheater, the flow splitter principle has found application in natural gas production. An interesting new application is the control of fow rates from 2 zones of a dually completed well into a single flow stream. The location was a production platform in the marshes of S. Louisiana and could be reached only by boat. The production plan was to ratio the flow of the 2 gas zones in accordance with pipeline demands. The flow control range for each zone was 4:1. The problem was to design a self-contained measurement and control system to meet these operating conditions. Understanding the PandI controller and how the flow splitter works are described in detail. In this field example, the entire platform measurement and control system was gas-powered and designed for an unattended location without any communication facility. This type installation is suitable for many locations, but is not 100% acceptable for all installations.

  2. 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.

  3. SSH Compromise Detection using NetFlow/IPFIX

    NARCIS (Netherlands)

    Hofstede, R.J.; Hendriks, Luuk; Sperotto, Anna; Pras, Aiko

    2014-01-01

    Flow-based approaches for SSH intrusion detection have been developed to overcome the scalability issues of host-based alternatives. Although the detection of many SSH attacks in a flow-based fashion is fairly straightforward, no insight is typically provided in whether an attack was successful. We

  4. 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.

  5. Modelling of gas flow through metallic foams

    Energy Technology Data Exchange (ETDEWEB)

    Crosnier, S. [CEA Grenoble, Dept. de Thermohydraulique et de Physique, 38 (France); Riva, R. [CEA Cadarache, 13 - Saint Paul lez Durance (France); Bador, B.; Blet, V.

    2003-09-01

    The transport and distribution of gases (hydrogen at the anode and air at the cathode) and water over the front surfaces of the electrodes in contact with electrolyte membrane are of great importance for the enhancement of efficiency of the Proton Exchange Membrane Fuel Cells (PEMFC). The use of metallic foam as a flow distributor in comparison with grooved plate (formed by parallel channels) commonly used in commercial fuel cells may be advantageous since this porous material has a porosity close to unity and then high specific surface area. In fact, the potentially active surface area is generally considered to be almost equal to the front surface area of the electrodes. In order to ensure a homogeneous flow distribution all over the active surface of such devices, a good understanding of gas flow through these particular porous media is necessary. For that purpose, studying of two-phase flow (oxygen, hydrogen and water) through metallic foams must be undertaken. This is carried out in the present work but, in a first step, only for single-phase flow, since the behaviour of two-phase flow derives from the first one. Novels hydraulic models have then been developed in the literature these last years. However, these models do not take into account the viscous dissipation of the flow along the walls bordering the porous media. Unfortunately, metallic foam used as distributors in fuel cell have thigh thickness (of the order of the millimeter), that shedding a doubt on the validity of the latter assumption. In this paper, we review the different hydraulic models in order to discuss the relevance and the limits of each to describe single-phase flow through foams which could be used as distributor in a fuel cell. For that purpose, numerical solutions obtained using modified MC3D-REPO package originally developed for the modelling of multicomponent two-phase flows in granular porous media have been compared to experimental data measured on a dedicated hydraulic device

  6. Estimation of hepatic blood flow by hydrogen gas clearance

    NARCIS (Netherlands)

    Gouma, D. J.; Coelho, J. C.; Schlegel, J.; Fisher, J. D.; Li, Y. F.; Moody, F. G.

    1986-01-01

    The hydrogen gas clearance technique was evaluated to estimate regional hepatic blood flow. Initially, the H2 gas method was compared to the indocyanine green clearance in mini pigs. The blood flow measured by the H2 gas method (0.49 +/- 0.03 ml/min/gm) was only 39% of the calculated blood flow by

  7. Cooled gas turbine blade edge flow analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mendonca, Marcio Teixeira de [Instituto Tecnologico de Aeronautica, Divisao de Engenharia Mecanica Aeronautica ITA/IEM, Sao Jose dos Campos, SP (Brazil)], e-mail: marcio@ita.br

    2010-07-01

    The flow on the rotating blades of a turbine is unsteady due to the wake of the stator blade row upstream. This unsteadiness is a source of losses and complex flow structures on the rotor blade due to the variation on the turbulence levels and location of the boundary layer laminar to turbulent transition. Convective cooled blades often time have cooling air ejected at the trailing edge right at the blade wake. The present investigation presents an analysis of a canonical flow consistent with the flow topology found at the trailing edge of a gas turbine blade with coolant ejection. A hydrodynamic stability analysis is performed for the combined wake and jet velocity profiles given by a gaussian distribution representing the turbulent rms wake and a laminar jet superposed. The growth rate of any instability found on the flow is an indication of faster mixing, resulting in a reduction on the wake velocity defect and consequently on the complexity associated with it. The results show that increasing the Mach number or the three-dimensionality of the disturbances result in a reduction of the amplification rate. When the flow at the trailing edge is modified by a jet, the amplification rates are lower, but the range of unstable stream wise wavenumbers is larger. (author)

  8. 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.

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

    NARCIS (Netherlands)

    Akkermans, Dirk H.M.

    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,

  10. 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.

  11. Report of the Third Workshop on the Usage of NetFlow/IPFIX in Network Management

    NARCIS (Netherlands)

    Drago, Idilio; Sadre, R.; Pras, Aiko

    2011-01-01

    The Network Management Research Group (NMRG) organized in 2010 the Third Workshop on the Usage of NetFlow/IPFIX in Network Management, as part of the 78th IETF Meeting in Maastricht. Yearly organized since 2007, the workshop is an opportunity for people from both academia and industry to discuss the

  12. 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 CO2 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 (GWP20 and GWP100). 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 GWP20. 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 GWP20. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Methods for measurement of gas flow velocity, methods for energy conversion using gas flow over solid material, and device therefor

    OpenAIRE

    Sood, Ajay Kumar; Ghosh, Shankar

    2004-01-01

    The present invention relates to a methods for energy conversion by gas flow over solid materials and also to a method for measurement of velocity of a gas flow over solid material such as doped semiconductors, graphite, and the like as a function of the 5 electricity generated in the solid material due to the flow of the gas the surface thereof using a combination of the Seebeck effect and Bernoulli's principle.

  17. Flow monitoring explained: from packet capture to data analysis with NetFlow and IPFIX

    NARCIS (Netherlands)

    Hofstede, R.J.; Celeda, Pavel; Trammell, Brian; Drago, Idilio; Sadre, R.; Sperotto, Anna; Pras, Aiko

    2014-01-01

    Flow monitoring has become a prevalent method for monitoring traffic in high-speed networks. By focusing on the analysis of flows, rather than individual packets, it is often said to be more scalable than traditional packet-based traffic analysis. Flow monitoring embraces the complete chain of

  18. 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...

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

    OpenAIRE

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

    2014-01-01

    Free-molecular gas flow in cylindrical channels (capillaries) in various schemes of molecule scattering by channel walls in view of surface diffusion is considered. The problem of separation of gas mixtures in their flow through membranes with nanopores is studied. The problem of uniform deposition of thin films on the inner surface of the fine cylindrical channel is discussed.

  20. Gas-Water Flow Behavior in Water-Bearing Tight Gas Reservoirs

    Directory of Open Access Journals (Sweden)

    Renyi Cao

    2017-01-01

    Full Text Available Some tight sandstone gas reservoirs contain mobile water, and the mobile water generally has a significant impact on the gas flowing in tight pores. The flow behavior of gas and water in tight pores is different than in conventional formations, yet there is a lack of adequate models to predict the gas production and describe the gas-water flow behaviors in water-bearing tight gas reservoirs. Based on the experimental results, this paper presents mathematical models to describe flow behaviors of gas and water in tight gas formations; the threshold pressure gradient, stress sensitivity, and relative permeability are all considered in our models. A numerical simulator using these models has been developed to improve the flow simulation accuracy for water-bearing tight gas reservoirs. The results show that the effect of stress sensitivity becomes larger as water saturation increases, leading to a fast decline of gas production; in addition, the nonlinear flow of gas phase is aggravated with the increase of water saturation and the decrease of permeability. The gas recovery decreases when the threshold pressure gradient (TPG and stress sensitivity are taken into account. Therefore, a reasonable drawdown pressure should be set to minimize the damage of nonlinear factors to gas recovery.

  1. Gas flow in porous media - turbulence or thermodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Littmann, W. [Consulting Reservoir Engineering, Wunstorf (Germany)

    2004-12-01

    The flow of gas into a wellbore is calculated by the back-pressure or deliverability equation. The exponent n, which accounts for the deviation from the ideal Darcy flow, is usually attributed to turbulence in the reservoir. It is shown, that turbulence in gas wells only occurs in very extreme cases, and that the exponent n can be assigned to temperature changes during the expansion of gas. The exponent n is then similar to the reciprocal of the exponent in the equation of state, that describes the adiabatic reversible expansion of a gas. The deviation of Darcy flow, which is observed in gas wells, is not due to turbulence but to the change of temperature. The expression ''non-Darcy flow'' is misleading, as the flow does still follow Darcy's law. (orig.)

  2. 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....../particle flows based on the kinetic theory for granular flows are given. Sub models for the interfacial transfer processes and chemical kinetics modelling are presented. Examples are shown for several gas/particle systems including flow in risers, segregation by size and reacting systems....

  3. Constant-net-time headway as a key mechanism behind pedestrian flow dynamics.

    Science.gov (United States)

    Johansson, Anders

    2009-08-01

    We show that keeping a constant lower limit on the net-time headway is the key mechanism behind the dynamics of pedestrian streams. There is a large variety in flow and speed as functions of density for empirical data of pedestrian streams obtained from studies in different countries. The net-time headway, however, stays approximately constant over all these different data sets. By using this fact, we demonstrate how the underlying dynamics of pedestrian crowds, naturally follows from local interactions. This means that there is no need to come up with an arbitrary fit function (with arbitrary fit parameters) as has traditionally been done. Further, by using not only the average density values but the variance as well, we show how the recently reported stop-and-go waves [Helbing, Phys. Rev. E 75, 046109 (2007)] emerge when local density variations take values exceeding a certain maximum global (average) density, which makes pedestrians stop.

  4. Modeling and Simulation of Wet Gas Flow in Venturi Flow Meter

    Directory of Open Access Journals (Sweden)

    Hossein SERAJ

    2011-09-01

    Full Text Available Wet gas which is a gas contains liquid, is encountered in various industrial applications such as oil and gas, power generation and mining plants. Measuring wet gas flow rate is required in many of these applications. Venturi flow meters are frequently used for wet gas flow measurement. This paper describes modeling and computer simulation of wet gas flow in the Venturi flow meters. The model used in this paper is based on an annular flow pattern. In this flow pattern, the gas is travelling in the middle of the pipe and the liquid is travelling along the pipe wall. In addition, it is assumed that some liquid droplets are entrained in the gas core. Then Simulink module of Matlab software has been used to simulate this model. This simulation has been used to compare various methods for correcting over-reading of Bernoulli formula when the same is used to measure wet gas flow rate in Venturi flow meter. By comparing the results obtained from simulation of these correction methods, it was found that some of these correction methods such as De Leeuw method are performing better than the others.

  5. 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.

  6. Effect of gas flow rate on titanium sponge reaction

    Science.gov (United States)

    Wang, Zhiliang; Feng, Gaoping; Wang, Mingdong; Hong, Yanji

    2017-08-01

    This paper expounds the important application of titanium sponge adsorption in inert gas purification, the reaction mechanism of titanium with nitrogen and oxygen was introduced. Explored the relationship between the absorption capacity of sponge titanium on the active gas in air samples and the gas flow rate. The model of sponge titanium for flowing air absorption was established by data analysis. The designed experiment verified the relationship between the titanium processing capacity and the gas collecting device. Finally, the influence of the mass of the sponge titanium on the degassing capacity was studied through experiments.

  7. Smolt Responses to Hydrodynamic Conditions in Forebay Flow Nets of Surface Flow Outlets, 2007

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Gary E.; Richmond, Marshall C.; Hedgepeth, J. B.; Ploskey, Gene R.; Anderson, Michael G.; Deng, Zhiqun; Khan, Fenton; Mueller, Robert P.; Rakowski, Cynthia L.; Sather, Nichole K.; Serkowski, John A.; Steinbeck, John R.

    2009-04-01

    This study provides information on juvenile salmonid behaviors at McNary and The Dalles dams that can be used by the USACE, fisheries resource managers, and others to support decisions on long-term measures to enhance fish passage. We researched smolt movements and ambient hydrodynamic conditions using a new approach combining simultaneous acoustic Doppler current profiler (ADCP) and acoustic imaging device (AID) measurements at surface flow outlets (SFO) at McNary and The Dalles dams on the Columbia River during spring and summer 2007. Because swimming effort vectors could be computed from the simultaneous fish and flow data, fish behavior could be categorized as passive, swimming against the flow (positively rheotactic), and swimming with the flow (negatively rheotactic). We present bivariate relationships to provide insight into fish responses to particular hydraulic variables that engineers might consider during SFO design. The data indicate potential for this empirical approach of simultaneous water/fish measurements to lead to SFO design guidelines in the future.

  8. 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.

  9. Monte Carlo simulation of gas-flow using MCNP

    Energy Technology Data Exchange (ETDEWEB)

    Matthes, W.K. [21027 Ispra, Via Francia 146 (Italy)]. E-mail: wilhelm_matthes@hotmail.com

    2005-09-15

    The simulation of the flow of rarefied gases by Monte Carlo has been long established and goes by the name DSMC (Direct Simulation by Monte Carlo). The theory, applications and references are well documented in Monographs on this subject, e.g., Bird [Bird, G.A., 1998. Molecular Gas Dynamics and the Direct Simulation of Gas Flows, Clarendon Press, Oxford], Cercignani [Cercignani, C., 2000. Rarified Gas Dynamics, Cambridge University Press, Cambridge]. However, as most applications are restricted to two-dimensional flows only, we want to demonstrate that the MCNP code (see [Briesmeier, J.F., 1986. MCNP-A General Monte Carlo Code for Neutron and Photon Transport, Version 3A, Los Alamos National Laboratory]), after a few modifications, provides a very flexible tool to investigate the flow (and reactions) of multicomponent gas-mixtures in complicated three-dimensional structures.

  10. Observations on the decay of a thermocline in a rock bed with no net fluid flow

    Energy Technology Data Exchange (ETDEWEB)

    Beasley, D.E.; Clark, J.A.; Holstege, M.J.

    1985-02-01

    The transient thermal response of a rock bed with no net fluid flow is examined following all-day charging under clear sky conditions. The experimental system consists of 1.86 m/sup 2/ (20 ft/sup 2/) of flat-plate solar collectors using air as the working fluid, a flow control system, and a 0.357 m/sup 3/ (12.6 ft/sup 3/) rock bed for thermal energy storage. A thermocline is established in the bed during charging due to the timevarying nature of the collector outlet temperature. Experimental measurements of the temperature distribution in the bed for a 13-hour stagnation period allow a preliminary estimate of the loss of available energy in the storage medium. The net loss in thermodynamic availability is 30 percent. Since the temperatures in the upper regions of the bed are lower than those in the central regions at the end of charging under clear sky conditions, the possibility of natural convection motion of the fluid in the bed exists. An ''apparent'' local thermal diffusivity is calculated and from comparison with stagnant bed values indicates that natural convection motion may occur in the upper regions of the bed.

  11. 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...

  12. Forest and grassland cover types reduce net greenhouse gas emissions from agricultural soils.

    Science.gov (United States)

    Baah-Acheamfour, Mark; Carlyle, Cameron N; Lim, Sang-Sun; Bork, Edward W; Chang, Scott X

    2016-11-15

    Western Canada's prairie region is extensively cultivated for agricultural production, which is a large source of greenhouse gas emissions. Agroforestry systems are common land uses across Canada, which integrate trees into the agricultural landscape and could play a substantial role in sequestering carbon and mitigating increases in atmospheric GHG concentrations. We measured soil CO2, CH4 and N2O fluxes and the global warming potential of microbe-mediated net greenhouse gas emissions (GWPm) in forest and herbland (areas without trees) soils of three agroforestry systems (hedgerow, shelterbelt and silvopasture) over two growing seasons (May through September in 2013 and 2014). We measured greenhouse gas fluxes and environmental conditions at 36 agroforestry sites (12 sites for each system) located along a south-north oriented soil/climate gradient of increasing moisture availability in central Alberta, Canada. The temperature sensitivity of soil CO2 emissions was greater in herbland (4.4) than in forest (3.1), but was not different among agroforestry systems. Over the two seasons, forest soils had 3.4% greater CO2 emission, 36% higher CH4 uptake, and 66% lower N2O emission than adjacent herbland soils. Combining the CO2 equivalents of soil CH4 and N2O fluxes with the CO2 emitted via heterotrophic (microbial) respiration, forest soils had a smaller GWPm than herbland soils (68 and 89kgCO2ha(-1), respectively). While emissions of total CO2 were silvopasture>hedgerow>shelterbelt, soils under silvopasture had 5% lower heterotrophic respiration, 15% greater CH4 uptake, and 44% lower N2O emission as compared with the other two agroforestry systems. Overall, the GWPm of greenhouse gas emissions was greater in hedgerow (88) and shelterbelt (85) than in the silvopasture system (76kgCO2ha(-1)). High GWPm in the hedgerow and shelterbelt systems reflects the greater contribution from the monoculture annual crops within these systems. Opportunities exist for reducing soil

  13. The gas heterogeneous flows cleaning technology from corona discharge field

    Science.gov (United States)

    Bogdanov, A.; Tokarev, A.; Judanov, V.; Vinogradov, V.

    2017-11-01

    A nanogold capture and extraction from combustion products of Kara-Keche coal, description the process: a coal preparation to experiments, nanogold introducing in its composition, temperature and time performance of combustion, device and function of experimental apparatus, gas-purification of the gas flow process and receiving combustion products (condensate, coke, ash, rags) is offerred.

  14. SIMULATION OF THE LASER DISCHARGE IN A SUPERSONIC GAS FLOW

    Directory of Open Access Journals (Sweden)

    Tropina, A. A.

    2013-06-01

    Full Text Available A heat model of the laser discharge in a supersonic turbulent gas flow has been developed. A numerical investigation of the error of the method of velocity measurements, which is based on the nitrogen molecules excitation, has been carried out. It is shown that fast gas heating by the discharge causes the velocity profiles deformation.

  15. Sub-surface gas flow in porous bodies

    Science.gov (United States)

    Teiser, Jens; Schywek, Mathias; de Beule, Caroline; Wurm, Gerhard

    2015-11-01

    Gas flow within porous media is of importance for various bodies in the Solar System. It occurs within the Martian soil, might be significant in the porous interiors of comets and also within dusty planetesimals in the Solar Nebula. In regimes of low atmospheric pressure, thermal creep leads to an efficient gas flux if temperature gradients are present, e.g. by solar insolation. This flow can lead to erosion or supports the exchange of volatiles within a porous body. Experiments showed that this gas flux dominates over diffusive gas transport under Martian conditions with gas velocities on the order of cm/s. Results from the Rosetta spacecraft suggest that eolian processes occur on comets which might be related to thermal creep gas flow. Here, we present new results of microgravity experiments on a thermally induced gas flow. Gas velocities and their dependence on the atmospheric pressure for different gases (Helium and air) are studied as well as the influence of the geometry of the pores.

  16. 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.

  17. Numerical modeling of microchannel gas flows in the transition flow regime via cascaded lattice Boltzmann method

    CERN Document Server

    Liu, Qing

    2016-01-01

    As a numerically accurate and computationally efficient mesoscopic numerical method, the lattice Boltzmann (LB) method has achieved great success in simulating microscale rarefied gas flows. In this paper, an LB method based on the cascaded collision operator is presented to simulate microchannel gas flows in the transition flow regime. The Bosanquet-type effective viscosity is incorporated into the cascaded lattice Boltzmann (CLB) method to account for the rarefaction effects. In order to gain accurate simulations and match the Bosanquet-type effective viscosity, the combined bounce-back/specular-reflection scheme with a modified second-order slip boundary condition is employed in the CLB method. The present method is applied to study gas flow in a microchannel with periodic boundary condition and gas flow in a long microchannel with pressure boundary condition over a wide range of Knudsen numbers. The predicted results, including the velocity profile, the mass flow rate, and the non-linear pressure deviatio...

  18. 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...

  19. Real gas flows with high velocities

    CERN Document Server

    Lunev, Vladimir V

    2009-01-01

    Gasdynamic Model and Equations Outline of the Gasdynamic Model Basic Equations and Postulates Equations of State Kinetic Theory Second Law of Thermodynamics Speed of Sound Integral Equations of Motion Kinematics of Fluid Media Differential Equations of Gasdynamics Rheological Model Initial and Boundary Conditions Similarity and Modeling in Gasdynamics Euler Equations Navier-Stokes Equations Turbulent Flows Viscous and Inviscid Flow Models Inviscid Gasdynamics Stream Function, Potential,

  20. 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)

  1. Estimations of gas flow maldistribution in packed-bed columns

    Energy Technology Data Exchange (ETDEWEB)

    Petrova, T.; Darakchiev, R.; Semkov, K.; Darakchiev, S. [Institute of Chemical Engineering, Bulgarian Academy of Sciences, Sofia (Bulgaria)

    2008-12-15

    A review of research articles dealing with estimation of the rate of gas flow maldistribution in packed-bed columns is presented. The proposed relations for determination of the maldistribution factor are given along with the conditions at which they are obtained. It is shown that the indices of maldistribution are usually based on particular terms, i.e., variation coefficient, dispersion or standard deviation. However, they cannot be regarded as a single indicator of gas maldistribution if the gas flow irregularities are not homogeneously distributed over the cross-section. There is no unified methodology for measuring the gas flow velocity profile. Schemes for measuring the velocity profiles, as well as equations for calculating the maldistribution factor are recommended. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  2. Partial wetting gas-liquid segmented flow microreactor.

    Science.gov (United States)

    Kazemi Oskooei, S Ali; Sinton, David

    2010-07-07

    A microfluidic reactor strategy for reducing plug-to-plug transport in gas-liquid segmented flow microfluidic reactors is presented. The segmented flow is generated in a wetting portion of the chip that transitions downstream to a partially wetting reaction channel that serves to disconnect the liquid plugs. The resulting residence time distributions show little dependence on channel length, and over 60% narrowing in residence time distribution as compared to an otherwise similar reactor. This partial wetting strategy mitigates a central limitation (plug-to-plug dispersion) while preserving the many attractive features of gas-liquid segmented flow reactors.

  3. Modeling the Gas-Solid Flow in Calcining Furnace

    Directory of Open Access Journals (Sweden)

    Haiyan Luo

    2011-03-01

    Full Text Available Gas-solid two-phase flow in calcining furnace is investigated in this paper. The turbulent fluid phase is calculated using the RNG k-e two-equation model in the Eulerain framework while the solid phase being handled via the particle stochastic trajectory model is calculated in the Lagrangian framework. Flow pattern characteristics of the fluid phase and the particle trajectories of the solid phase were predicted subject to a range of flow conditions and different particle sizes. The computed results provided useful information in the preview of kinetics regulation of the gas-solid two-phase in calcining furnace.

  4. 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.

  5. Effects of global gas flows on type I migration

    Science.gov (United States)

    Ogihara, Masahiro; Kokubo, Eiichiro; Suzuki, Takeru K.; Morbidelli, Alessandro; Crida, Aurélien

    2017-12-01

    Context. Magnetically-driven disk winds would alter the surface density slope of gas in the inner region of a protoplanetary disk (r ≲ 1 au). This in turn affects planet formation. Recently, the effect of disk wind torque has been considered with the suggestion that it would carve out the surface density of the disk from inside and would induce global gas flows (wind-driven accretion). Aims: We aim to investigate effects of global gas flows on type I migration and also examine planet formation. Methods: A simplified approach was taken to address this issue, and N-body simulations with isolation-mass planets were also performed. Results: In previous studies, the effect of gas flow induced by turbulence-driven accretion has been taken into account for its desaturation effect of the corotation torque. If more rapid gas flows (e.g., wind-driven accretion) are considered, the desaturation effect can be modified. In MRI-inactive disks, in which the wind-driven accretion dominates the disk evolution, the gas flow at the midplane plays an important role. If this flow is fast, the corotation torque is efficiently desaturated. Then, the fact that the surface density slope can be positive in the inner region due to the wind torque can generate an outward migration region extended to super-Earth mass planets. In this case, we observe that no planets fall onto the central star in N-body simulations with migration forces imposed to reproduce such migration pattern. We also see that super-Earth mass planets can undergo outward migration. Conclusions: Relatively rapid gas flows affects type I migration and thus the formation of close-in planets.

  6. Modeling gas flow through microchannels and nanopores

    Science.gov (United States)

    Roy, Subrata; Raju, Reni; Chuang, Helen F.; Cruden, Brett A.; Meyyappan, M.

    2003-04-01

    Microchannel based systems have emerged as a critical design trend in development of precise control and maneuvering of small devices. In microelectronics, space propulsion and biomedical areas, these systems are especially useful. Nanoscale pores are recently becoming of great interest due to their beneficial drag and heat transfer properties. However it is difficult to predict the flow performance of these microsystems and nanosystems numerically since the standard assumptions of using Navier-Stokes equations break down at micrometer scales, while the computational times of applicable molecular-dynamics codes become exorbitant. A two-dimensional finite-element based microscale flow model is developed to efficiently predict the overall flow characteristics up to the transition regime for reasonably high Knudsen number flow inside microchannels and nanopores. Presented two-dimensional numerical results for Poiseuille flow of a simple fluid through the microchannel are comparable to the numerical and experimental data published in the literature. The nanopore solutions are also validated with presented experimental data.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. Gas mass transfer for stratified flows

    Energy Technology Data Exchange (ETDEWEB)

    Duffey, R.B. [Brookhaven National Lab., Upton, NY (United States); Hughes, E.D. [CSA, Inc., Idaho Falls, ID (United States)

    1995-06-01

    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{sub t} = (2/{radical}{pi})Sc{sup 1/2}, where Sh{sub 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.

  14. Gas mass transfer for stratified flows

    Energy Technology Data Exchange (ETDEWEB)

    Duffey, R.B. [Brookhaven National Lab., Upton, NY (United States); Hughes, E.D. [CSA Inc., Idaho Falls, ID (United States)

    1995-07-01

    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 equilibrum 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{sub t} = (2/{radical}{pi}) Sc{sup 1/2}, where Sh{sub 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 geophysical and chemical engineering literature.

  15. 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.

  16. 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...

  17. An experimental investigation of flows from zero-net mass-flux actuators

    Science.gov (United States)

    Holman, Ryan Jay

    Zero-net mass-flux (ZNMF) devices consist of an oscillating driver, a cavity, and a small opening such as a rectangular slot or a circular orifice. The driver produces a series of vortex pairs (or rings) at the slot/orifice which add momentum and circulation to the flow. ZNMF devices are useful tools for flow control applications such as heat transfer, mixing enhancement, and boundary layer separation control. To date much research has been done to qualify and quantify the effects of ZNMF devices in many applications, both experimental and computational. However, a number of issues still remain. First, there is no universally accepted dimensionless parameter space, which makes device characterization and comparison between studies difficult. Second, most experimental studies do not sufficiently quantify the nearfield behavior, which hinders the fundamental understanding of the underlying flow physics. Of particular interest are the regimes of jet formation, and transition from laminar to turbulent-like flow, which are not well understood. Finally, the accuracy of experimental measurements are seldom reported in the literature. This study unifies the experimental and numerical data presented in the literature for ZNMF flowfields exhausting into a quiescent medium. A quantitative experimental database is also generated to completely characterize the topological regions of ZNMF flows over a useful range of the dimensionless parameter space. The database is derived chiefly from two-dimensional velocity field measurements using particle image velocimetry and laser Doppler anemometry. Vorticity, circulation, Reynolds stress, and turbulent kinetic energy is acquired to characterize the resulting flowfield. Significant insight into the behavior of voice coil driven ZNMF devices is uncovered. Design improvements are made by implementing a sinusoidal controller for piston motion and eliminating the need for a sealing membrane in the cavity. It is shown that the proper

  18. Determining fluid and gas flow distribution within separation apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Remizov, N.A.

    1982-01-01

    This study considered fluid and gas flow distribution in existing industrial separator units. The author found that overall hydraulic resistance was not identical in these units, resulting from variables in the gas-fluid mixtures' movement between the distribution points and the separator units. Separator loads were found to be imbalanced due to the imperfect design of these units. Load equalization could be obtained by way of achieving simultaneous pulsation suppression in distribution lines. Pulsation suppression itself is achieved through the use of a separation phase in collection pipelines followed by individual flow separation. Gas and fluid are thus introduced into the distribution pipeline and separator separately. Separator design dimensions and parameters are given along with suggestions for their application. Long-term industrial experience with flow separators has shown that these units not only require minimal operating expenditure, but also are highly reliable and effective.

  19. AERODYNAMICS OF SWIRLING FLOWS IN GAS OUTLET PIPES OF HEAT GENERATING PLANTS

    Directory of Open Access Journals (Sweden)

    Vadim Kajumovich Ahmetov

    2012-10-01

    Full Text Available The intermixing of hot turbulent gases in an axisymmetric channel with lateral surfaces of arbitrary shape and a pre-swirled flow is considered in the paper. This problem is relevant in connection with the development of new high-tech designs of natural fuel combustion facilities. Any designs are to comply with specific requirements. The temperature of the flue gas must not fall below a certain limit to prevent promotion of condensation that facilitates pipe corrosion. The gas outlet velocity must exceed 4 m/s to prevent the downdraft. The concentration of pollutants released into the atmosphere must fall within permissible limits. The mathematical model is based on parabolized Navier-Stokes equations that restrict its applicability to continuous flows. However, in view of the mechanical nature of the problem considered, continuous flows are of particular interest. The method of equal flow-rate surfaces is used as a numerical solution. The system of equations is based on streamlines. The net of lines is not available beforehand; therefore, it is constructed alongside with the problem solution. The system of equations is completed by an algebraic turbulence model. The proposed method makes it possible to check for the optimal flow regimes inside high-rise stack structures to assure that pollutant-containing smokes and gases, emitted into the atmosphere, produce the minimal damage onto the environment.

  20. AERODYNAMICS OF SWIRLING FLOWS IN GAS OUTLET PIPES OF HEAT GENERATING PLANTS

    Directory of Open Access Journals (Sweden)

    Akhmetov Vadim Kayumovich

    2012-10-01

    Full Text Available The intermixing of hot turbulent gases in an axisymmetric channel with lateral surfaces of arbitrary shape and a pre-swirled flow is considered in the paper. This problem is relevant in connection with the development of new high-tech designs of natural fuel combustion facilities. Any designs are to comply with specific requirements. The temperature of the flue gas must not fall below a certain limit to prevent promotion of condensation that facilitates pipe corrosion. The gas outlet velocity must exceed 4 m/s to prevent the downdraft. The concentration of pollutants released into the atmosphere must fall within permissible limits. The mathematical model is based on parabolized Navier-Stokes equations that restrict its applicability to continuous flows. However, in view of the mechanical nature of the problem considered, continuous flows are of particular interest. The method of equal flow-rate surfaces is used as a numerical solution. The system of equations is based on streamlines. The net of lines is not available beforehand; therefore, it is constructed alongside with the problem solution. The system of equations is completed by an algebraic turbulence model. The proposed method makes it possible to check for the optimal flow regimes inside high-rise stack structures to assure that pollutant-containing smokes and gases, emitted into the atmosphere, produce minimal damage onto the environment.

  1. A new gas release model for a homogeneous liquid-gas mixture flow in pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Kessal, Mohand [Department of Transport and Petroleum Equipment, Faculty of Oil and Chemistry, University of Boumerde' s, Boumerde' s 35000 (Algeria)]. E-mail: md.kessal@laposte.net; Bennacer, Rachid [Laboratoire Materiaux et Sciences des Constructions, Universite Cergy-Pontoise, Paris (France)

    2005-09-01

    The gas release phenomenon, resulting from a rapid decompression in a homogeneous gas-liquid flow is expressed by multiplying the mixture density by a degassing coefficient G {sub r}. The effect of this coefficient is calculated by using the classical conservation equations of fluid mechanics and diffusion laws. These equations are solved by an improved new two time step finite difference scheme. The method of characteristics is used at the boundaries. The theoretical results obtained are in good agreement with experimental data and confirm the gas release effect on the flow parameters.

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

    Energy Technology Data Exchange (ETDEWEB)

    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/sub 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.

  3. A flow pattern map for two-phase liquid-gas flow under reduced gravity conditions

    Science.gov (United States)

    Rezkallah, K. S.; Zhao, L.

    1995-08-01

    Two-phase gas-liquid flows have a wide range of applications in space including the flow of cryogenics in transport lines and heat-transfer fluids in a thermal control system. The behavior of these systems under reduced gravity must be understood in order to optimize the design and maintenance of such systems. Experimental studies on two-phase flow patterns and their transitions were conducted aboard the NASA KC-135 aircraft. A large set of flow pattern data for water-air and glycerin/water-air of different viscosities was reported. It was shown that two-phase flow under reduced gravity can be classified into four glow patterns: bubbly, slug, frothy slug-annular, and annular flows. Transitions between slug and frothy slug-annular, and frothy slug-annular and annular flows were predicted well using the liquid and gas Weber numbers as the mapping coordinates.

  4. Coordinated scheduling of electricity and natural gas infrastructures with a transient model for natural gas flow.

    Science.gov (United States)

    Liu, Cong; Shahidehpour, Mohammad; Wang, Jianhui

    2011-06-01

    This paper focuses on transient characteristics of natural gas flow in the coordinated scheduling of security-constrained electricity and natural gas infrastructures. The paper takes into account the slow transient process in the natural gas transmission systems. Considering their transient characteristics, natural gas transmission systems are modeled as a set of partial differential equations (PDEs) and algebraic equations. An implicit finite difference method is applied to approximate PDEs by difference equations. The coordinated scheduling of electricity and natural gas systems is described as a bi-level programming formulation from the independent system operator's viewpoint. The objective of the upper-level problem is to minimize the operating cost of electric power systems while the natural gas scheduling optimization problem is nested within the lower-level problem. Numerical examples are presented to verify the effectiveness of the proposed solution and to compare the solutions for steady-state and transient models of natural gas transmission systems.

  5. 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.

  6. 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

  7. Resonance Line Formation in Moving Gas Flows with High Porosity

    Science.gov (United States)

    Shulman, S. G.

    2017-06-01

    The formation of resonance lines in gas flows generated by interactions of circumstellar gas with a star's magnetosphere is examined. An effective method is proposed for calculating these lines when the magnetospheric wind is highly porous. The resonance sodium lines observed in the spectrum of UX Ori type star RZ Psc are modelled as an example. It is shown that the narrow absorptions observed in the short wavelength wings of these lines can be formed by scattering of the star's radiation in two gas jets that are semitransparent at the line frequencies when they cross the line of sight.

  8. 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...

  9. GAS FLOW IN UNDERWATER BREATHING INSTALLATIONS

    Directory of Open Access Journals (Sweden)

    Anca CONSTANTIN

    2017-11-01

    Full Text Available The open circuit underwater breathing apparatus can be a one or two-stage regulator used in scuba diving or a two-stage regulator used in surface supplied installations. These installations are proper in underwater sites at small depth. The pneumatic circuit of a two-stage regulator is composed mainly of a first stage regulator mounted on the air cylinders and a second stage carried by the diver in his mouth. The two regulators are linked together by a medium pressure hose. The circuit opens when the depression created by the diver’s inhalation, in the second stage body, reaches a certain value. The second stage opening causes a transient movement, namely an expansion wave that propagates through the medium pressure hose to the first stage regulator. The first stage regulator opens and the air in the cylinders is allowed to flow to the diver. The longer the hose, the greater the duration of the expansion wave propagation. Investigations on the wave propagation offer data on the inspiration unsteady motion duration which influences the respiratory effort of the diver.

  10. Melt removal mechanism by transverse gas flow during laser irradiation

    Science.gov (United States)

    Wei, Cheng-hua; Zhu, Yong-xiang; Zhou, Meng-lian; Ma, Zhi-liang; Wu, Tao-tao

    2017-05-01

    To determine the mechanism of melt removal by transverse gas flow, a lateral visualization technique of hydrodynamics on melt pool was developed and experimental apparatus were built. The intensity distribution of the focused beam was confirmed to be in top-hat shape with the 15mm×40mm rectangular. The interface of liquid-solid and free surface of molten metal was observed by a high velocity video camera with acquisition rate of 1kHz. Gas flow blew from left to right and the velocity varied from 15m/s to 90m/s to investigate the evolution of hydrodynamics. Experiment results showed that surface wave was generated at the initial stage and molten metal was removed out from the melt pool by shear stress. When some amount molten metal was removed from melt pool, gas flow separated at the leading edge and reattaches downstream of melt pool. Thus a stagnation point was formed at the downstream edge and a recirculation zone was generated on the left side of stagnation. With recirculation gas flow constrain, the molten metal only can be entrained into main stream and then be swept away. The molten material was removed out by shear stress on the right side of stagnation.

  11. 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

  12. Gas and liquid distribution in the monolith film flow reactor

    NARCIS (Netherlands)

    Heibel, A.K.; Vergeldt, F.J.; As, van H.

    2003-01-01

    The gas-liquid distribution in a monolith film flow reactor is investigated in the scope of this work. Magnetic resonance imaging (MRI) and a customized liquid collection method hate been successfully applied to determine the liquid distribution over the monolith cross-section. Using a

  13. 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.

  14. 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)

  15. 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.

  16. Preliminary report on the flow no-flow indicator for the BI-GAS char line

    Energy Technology Data Exchange (ETDEWEB)

    Roach, P. D.; Raptis, A. C.

    1978-07-01

    The BI-GAS coal gasification pilot plant at Homer City, Pa. has an urgent need for monitoring char flow to the gasifier. The feed lines contain finely divided char in a steam carrier and operate at 800/sup 0/F and 1650 psi. A high temperature microphone, developed at ANL, has been installed in one char feed line with the goal of distinguishing between flow and no-flow conditions. The microphone signal is amplified and spectrum analyzed to reveal signal components associated with both char flow and steam flow. So far, we have obtained data only on the background steam noise, because operational problems at the pilot plant have delayed the start of char flow since our microphone was installed. The steam flow provides a strong microphone signal with a rich spectral content extending to about 45 kHz. Char flow data are scheduled to be taken during summer 1978.

  17. Gas hydrate, fluid flow and free gas: Formation of the bottom-simulating reflector

    Science.gov (United States)

    Haacke, R. Ross; Westbrook, Graham K.; Hyndman, Roy D.

    2007-09-01

    Gas hydrate in continental margins is commonly indicated by a prominent bottom-simulating seismic reflector (BSR) that occurs a few hundred metres below the seabed. The BSR marks the boundary between sediments containing gas hydrate above and free gas below. Most of the reflection amplitude is caused by the underlying free gas. Gas hydrate can occur without a BSR, however, and the controls on its formation are not well understood. Here we describe two complementary mechanisms for free gas accumulation beneath the gas hydrate stability zone (GHSZ). The first is the well-recognised hydrate recycling mechanism that generates gas from dissociating hydrate when the base of the GHSZ moves upward relative to hydrate-bearing sediment. The second is a recently identified mechanism in which the relationship between the advection and diffusion of dissolved gas with the local solubility curve allows the liquid phase to become saturated in a thick layer beneath the GHSZ when hydrate is present near its base. This mechanism for gas production (called the solubility-curvature mechanism) is possible in systems where the influence of diffusion becomes important relative to the influence of advection and where the gas-water solubility decreases to a minimum several hundred metres below the GHSZ. We investigate a number of areas in which gas hydrate occurs to determine where gas formation is dominated by the solubility-curvature mechanism and where it is dominated by hydrate recycling. We show that the former is dominant in areas with low rates of upward fluid flow (such as old, rifted continental margins), low rates of seafloor uplift, and high geothermal gradient and/or pressure. Conversely, free-gas formation is dominated by hydrate recycling where there are rapid rates of upward fluid flow and seabed uplift (such as in subduction zone accretionary wedges). Using these two mechanisms to investigate the formation of free gas beneath gas hydrate in continental margins, we are able

  18. 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

  19. Solids flow mapping in gas-solid risers

    Science.gov (United States)

    Bhusarapu, Satish Babu

    Gas-solid risers are extensively used in many industrial processes for gas-solid reactions (e.g. coal combustion and gasification) and for solid catalyzed gas phase reactions (e.g. fluid catalytic cracking, butane oxidation to maleic anhydride). Ab initio prediction of the complex multiphase fluid dynamics in risers is not yet possible, which makes reactor modeling difficult. In particular, quantification of solids flow and mixing is important. Almost all the experimental techniques used to characterize solids flow lead to appreciable errors in measured variables in large scale, high mass flux systems. In addition, none of the experimental techniques provide all the relevant data required to develop a satisfactory solids flow model. In this study, non-invasive Computer Automated Radioactive Particle Tracking (CARPT) is employed to visualize and quantify the solids dynamics and mixing in the gas-solid riser of a Circulating Fluidized Bed (CFB). A single radioactive tracer particle is monitored during its multiple visits to the riser and with an assumption of ergodicity, the following flow parameters are estimated: (a) Overall solids mass flux in the CFB loop. (b) Solids residence time distribution in the riser and down-comer. (c) Lagrangian and Eulerian solids velocity fields in a fully-developed section of the riser. This includes velocity fluctuations and components of the diffusivity tensor. The existing CARPT technique is extended to large scale systems. A new algorithm, based on a cross-correlation search, is developed for position rendition from CARPT data. Two dimensional solids holdup profiles are estimated using gamma-ray computed tomography. The image quality from the tomography data is improved by implementing an alternating minimization algorithm. This work establishes for the first time a reliable database for local solids dynamic quantities such as time-averaged velocities, Reynolds stresses, eddy diffusivities and turbulent kinetic energy. In addition

  20. Fundamentals of multiphase, gas-solid and gas-liquid flows in porous media

    Science.gov (United States)

    Mazaheri, Ali Reza

    This thesis is concerned with fundamentals and applications of multiphase and particulate flows. The study contains three parts covering gas-liquid flows through porous media, gas-solid flows and Chemical-Mechanical Polishing (CMP). A continuum model for multiphase fluid flows through poro-elastic media is developed. It is shown that the present theory leads to the extended Darcy's law and contains, as its special case, Biot's theory of saturated poro-elastic media. The capillary pressure formulation derived from the new model is used and the equation governing the evolution of the saturation and its temporal variation in porous media is derived. The resulting nonlinear diffusion equation is then solved numerically. The results show that the capillary hysteresis occurs when the temporal variation of saturation is included. Application of the developed model to CO2 sequestration is discussed. Computer simulations of dilute Gas-Solid flows in complex geometry regions are studied. A procedure for handling particle trajectory analysis in unstructured grid is developed. Examples of particle transport and removal in human lung and hot-gas cleaning systems are presented. The simulation results for the human lung show that the capture efficiency is affected by the turbulence in the upper three bifurcation airways. Computer simulations of gas-solid flows in hot-gas cleaning for a demonstration scale filtration system is studied in details. Alternative designs of the filter vessel are proposed. The corresponding vessel performance are numerically simulated. Chemical mechanical polishing (CMP) has become critical to the fabrication of advanced multilevel integrated circuit in microelectronic industry. The effect of course surface roughness of abrasive particles on the polishing rate in CMP is studied. The effects of slurry pH and double layer attraction and repulsion on chemical-mechanical polishing are also studied. It is shown that the slurry pH and colloidal forces

  1. 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

  2. A physical-based gas-surface interaction model for rarefied gas flow simulation

    Science.gov (United States)

    Liang, Tengfei; Li, Qi; Ye, Wenjing

    2018-01-01

    Empirical gas-surface interaction models, such as the Maxwell model and the Cercignani-Lampis model, are widely used as the boundary condition in rarefied gas flow simulations. The accuracy of these models in the prediction of macroscopic behavior of rarefied gas flows is less satisfactory in some cases especially the highly non-equilibrium ones. Molecular dynamics simulation can accurately resolve the gas-surface interaction process at atomic scale, and hence can predict accurate macroscopic behavior. They are however too computationally expensive to be applied in real problems. In this work, a statistical physical-based gas-surface interaction model, which complies with the basic relations of boundary condition, is developed based on the framework of the washboard model. In virtue of its physical basis, this new model is capable of capturing some important relations/trends for which the classic empirical models fail to model correctly. As such, the new model is much more accurate than the classic models, and in the meantime is more efficient than MD simulations. Therefore, it can serve as a more accurate and efficient boundary condition for rarefied gas flow simulations.

  3. Fabrication of a gas flow device consisting of micro-jet pump and flow sensor

    Science.gov (United States)

    Tanaka, Katsuhiko; Dau, Van T.; Otake, Tomonori; Dinh, Thien X.; Sugiyama, Susumu

    2008-12-01

    A gas-flow device consisting of a valveless micro jet pump and flow sensor has been designed and fabricated using a Si micromachining process. The valveless micro pump is composed of a piezoelectric lead zirconate titanate (PZT) diaphragm actuator and flow channels. The design of the valvless pump focuses on a crosss junction formed by the neck of the pump chamber and one outlet and two opposite inlet channnels. The structure allows differences in the fluidic resistance and fluidic momentum inside the channels during each pump vibration cycle, which leads to the gas flow being rectified without valves. Before the Si micro-pump was developed, a prototype of it was fabricated using polymethyl methacrylate (PMMA) and a conventional machining techinique, and experiments on it confirmed the working principles underlying the pump. The Si micro-pump was designed and fabricated based on these working principles. The Si pump was composed of a Si flow channel plate and top and botom covers of PMMA. The flow channels were easily fabricated by using a silicon etching process. To investigate the effects of the step nozzle structure on the gas flow rate, two types of pumps with different channel depths (2D- and 3D-nozzle structures) were designed, and flow simulations were done using ANSYS-Fluent software. The simulations and excperimental data revealed that the 3D-nozzle structure is more advantageous than the 2D-nozzle structure. A flow rate of 4.3 ml/min was obtained for the pump with 3D-nozzle structure when the pump was driven at a resonant frequency of 7.9 kHz by a sinusoidal voltage of 40Vpp. A hot wire was fabricated as a gas-flow sensor near the outlet port on the Si wafer.

  4. Data set from gas sensor array under flow modulation.

    Science.gov (United States)

    Ziyatdinov, Andrey; Fonollosa, Jordi; Fernández, Luis; Gutiérrez-Gálvez, Agustín; Marco, Santiago; Perera, Alexandre

    2015-06-01

    Recent studies in neuroscience suggest that sniffing, namely sampling odors actively, plays an important role in olfactory system, especially in certain scenarios such as novel odorant detection. While the computational advantages of high frequency sampling have not been yet elucidated, here, in order to motivate further investigation in active sampling strategies, we share the data from an artificial olfactory system made of 16 MOX gas sensors under gas flow modulation. The data were acquired on a custom set up featured by an external mechanical ventilator that emulates the biological respiration cycle. 58 samples were recorded in response to a relatively broad set of 12 gas classes, defined from different binary mixtures of acetone and ethanol in air. The acquired time series show two dominant frequency bands: the low-frequency signal corresponds to a conventional response curve of a sensor in response to a gas pulse, and the high-frequency signal has a clear principal harmonic at the respiration frequency. The data are related to the study in [1], and the data analysis results reported there should be considered as a reference point. The data presented here have been deposited to the web site of The University of California at Irvine (UCI) Machine Learning Repository (https://archive.ics.uci.edu/ml/datasets/Gas+sensor+array+under+flow+modulation). The code repository for reproducible analysis applied to the data is hosted at the GutHub web site (https://github.com/variani/pulmon). The data and code can be used upon citation of [1].

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. Predicting Fluid Flow in Gas-Stirred Systems

    Science.gov (United States)

    Deb Roy, T.; Majumdar, A. K.

    1981-11-01

    Performance of many metallurgical operations where gas bubbles are injected into liquid baths, e.g., ladle degassing and desulfurization, is related to the level of bath circulation and agitation. This paper describes a method of calculating velocity fields and turbulence levels in these systems. The roles played by such factors as bubble size and volume of the two-phase gas/liquid region in determining the velocity field are examined. The applicability of fluid-flow calculations in preventing refractory failures is discussed.

  7. An Efficient Scalable Work-Stealing Runtime for Macro Data Flow Processing Using S-Net

    NARCIS (Netherlands)

    Gijsbers, B.; Grelck, C.

    2014-01-01

    S-Net is a declarative coordination language and component technology aimed at radically facilitating software engineering for modern parallel compute systems by near-complete separation of concerns between application (component) engineering and concurrency orchestration. S-Net builds on the

  8. Energy transfer model and its applications of ultrasonic gas flow-meter under static and dynamic flow rates.

    Science.gov (United States)

    Fang, Min; Xu, Ke-Jun; Zhu, Wen-Jiao; Shen, Zi-Wen

    2016-01-01

    Most of the ultrasonic gas flow-meters measure the gas flow rate by calculating the ultrasonic transmission time difference between the downstream and upstream. Ultrasonic energy attenuation occurs in the processes of the ultrasonic generation, conversion, transmission, and reception. Additionally, at the same time, the gas flow will also affect the ultrasonic propagation during the measurement, which results in the ultrasonic energy attenuation and the offset of ultrasonic propagation path. Thus, the ultrasonic energy received by the transducer is weaker. When the gas flow rate increases, this effect becomes more apparent. It leads to the measurement accuracy reduced, and the measurement range narrowed. An energy transfer model, where the ultrasonic gas flow-meter under without/with the gas flow, is established by adopting the statistical analysis and curve fitting based on a large amount of experimental data. The static sub model without the gas flow expresses the energy conversion efficiency of ultrasonic gas transducers, and the dynamic sub model with the gas flow reflects the energy attenuation pattern following the flow rate variations. The mathematical model can be used to determine the minimum energy of the excitation signal for meeting the requirement of specific measurement range, and predict the maximum measurable flow rate in the case of fixed energy of excitation signal. Based on the above studies, a method to enhance the excitation signal energy is proposed under the output power of the transmitting circuit being a finite value so as to extend the measurement rage of ultrasonic gas flow-meter.

  9. Gas flow control device for internal combustion engines

    Energy Technology Data Exchange (ETDEWEB)

    Matesic, A.; Castella, J.P.

    1996-08-29

    A gas flow control device for internal combustion engines, consisting of a single or double linearly movable member for controlling the flow rate of air in an intake duct, followed by a throttling mechanism for varying the cross-section of the duct. Both these devices may be common to all cylinders or provided plurally. Said including petrol engines or unsupercharged or turbocharged diesel engines, but is particularly suitable for four-stroke fuel ignition engines, i.e. those without a carburettor. (author)

  10. 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.

  11. Continuous flow production of concentrated hyperpolarized xenon gas from a dilute xenon gas mixture by buffer gas condensation.

    Science.gov (United States)

    Imai, Hirohiko; Yoshimura, Hironobu; Kimura, Atsuomi; Fujiwara, Hideaki

    2017-08-04

    We present a new method for the continuous flow production of concentrated hyperpolarized xenon-129 (HP (129)Xe) gas from a dilute xenon (Xe) gas mixture with high nuclear spin polarization. A low vapor pressure (i.e., high boiling-point) gas was introduced as an alternative to molecular nitrogen (N2), which is the conventional quenching gas for generating HP (129)Xe via Rb-Xe spin-exchange optical-pumping (SEOP). In contrast to the generally used method of extraction by freezing Xe after the SEOP process, the quenching gas separated as a liquid at moderately low temperature so that Xe was maintained in its gaseous state, allowing the continuous delivery of highly polarized concentrated Xe gas. We selected isobutene as the candidate quenching gas and our method was demonstrated experimentally while comparing its performance with N2. Isobutene could be liquefied and removed from the Xe gas mixture using a cold trap, and the concentrated HP (129)Xe gas exhibited a significantly enhanced nuclear magnetic resonance (NMR) signal. Although the system requires further optimization depending on the intended purpose, our approach presented here could provide a simple means for performing NMR or magnetic resonance imaging (MRI) measurements continuously using HP (129)Xe with improved sensitivity.

  12. Theory of Gas Injection: Interaction of Phase Behavior and Flow

    Science.gov (United States)

    Dindoruk, B.

    2015-12-01

    The theory of gas injection processes is a central element required to understand how components move and partition in the reservoir as one fluid is displacing another (i.e., gas is displacing oil). There is significant amount of work done in the area of interaction of phase-behavior and flow in multiphase flow conditions. We would like to present how the theory of gas injection is used in the industry to understand/design reservoir processes in various ways. The tools that are developed for the theory of gas injection originates from the fractional flow theory, as the first solution proposed by Buckley-Leveret in 1940's, for water displacing oil in porous media. After 1960's more and more complex/coupled equations were solved using the initial concept(s) developed by Buckley-Leverett, and then Welge et al. and others. However, the systematic use of the fractional flow theory for coupled set of equations that involves phase relationships (EOS) and phase appearance and disappearance was mainly due to the theory developed by Helfferich in early 80's (in petroleum literature) using method of characteristics primarily for gas injection process and later on by the systematic work done by Orr and his co-researchers during the last two decades. In this talk, we will present various cases that use and extend the theory developed by Helfferich and others (Orr et al., Lake et al. etc.). The review of various injection systems reveals that displacement in porous media has commonalities that can be represented with a unified theory for a class of problems originating from the theory of gas injection (which is in a way generalized Buckley-Leverett problem). The outcome of these solutions can be used for (and are not limited to): 1) Benchmark solutions for reservoir simulators (to quantify numerical dispersion, test numerical algorithms) 2) Streamline simulators 3) Design of laboratory experiments and their use (to invert the results) 4) Conceptual learning and to investigate

  13. Gas diffusion optic flow calculation and its applications in gas cloud infrared imaging

    Science.gov (United States)

    Liu, Shao-hua; Luo, Xiu-li; Wang, Ling-xue; Cai, Yi

    2015-11-01

    Motion detection frequently employs Optic Flow to get the velocity of solid targets in imaging sequences. This paper suggests calculate the gas diffusion velocity in infrared gas leaking videos by optic flow algorithms. Gas target is significantly different from solid objects, which has variable margin and gray values in diffusion. A series of tests with various scenes and leakage rate were performed to compare the effect of main stream methods, such as Farneback algorithm, PyrLK and BM algorithm. Farneback algorithm seems to have the best result in those tests. Besides, the robustness of methods used in uncooled infrared imaging may decline seriously for the low resolution, big noise and poor contrast ratio. This research adopted a special foreground detection method (FDM) and spectral filtering technique to address this issue. FDM firstly computes corresponding sample sets of each pixel, and uses the background based on the sets to make a correlation analysis with the current frame. Spectral filtering technique means get two or three images in different spectrum by band pass filters, and show a better result by mixing those images. In addition, for Optic Flow methods have ability to precisely detect directional motion and to ignore the nondirectional one, these methods could be employed to highlight the gas area and reduce the background noise. This paper offers a credible way for obtaining the diffusion velocity and resolves the robust troubles in practical application. In the meanwhile, it is an exploration of optic flow in varied shape target detection.

  14. One-dimensional flows of an imperfect diatomic gas

    Science.gov (United States)

    1959-01-01

    With the assumptions that Berthelot's equation of state accounts for molecular size and intermolecular force effects, and that changes in the vibrational heat capacities are given by a Planck term, expressions are developed for analyzing one-dimensional flows of a diatomic gas. The special cases of flow through normal and oblique shocks in free air at sea level are investigated. It is found that up to a Mach number 10 pressure ratio across a normal shock differs by less than 6 percent from its ideal gas value; whereas at Mach numbers above 4 the temperature rise is considerable below and hence the density rise is well above that predicted assuming ideal gas behavior. It is further shown that only the caloric imperfection in air has an appreciable effect on the pressures developed in the shock process considered. The effects of gaseous imperfections on oblique shock-flows are studied from the standpoint of their influence on the life and pressure drag of a flat plate operating at Mach numbers of 10 and 20. The influence is found to be small. (author)

  15. 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 (CH4 ) emissions. Here, we quantify the thaw-induced increase in CH4 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 (CO2 ) exchange. Using nested wetland and landscape eddy covariance net CH4 flux measurements in combination with flux footprint modeling, we find that landscape CH4 emissions increase with increasing wetland-to-forest ratio. Landscape CH4 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 CH4 emission of ~13 g CH4  m-2 is the dominating contribution to the landscape CH4 emission of ~7 g CH4  m-2 . In contrast, forest contributions to landscape CH4 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 CH4  m-2  yr-1 in landscape CH4 emissions. A long-term net CO2 uptake of >200 g CO2  m-2  yr-1 is required to offset the positive radiative forcing of increasing CH4 emissions until the end of the 21st century as indicated by an atmospheric CH4 and CO2 concentration model. However, long-term apparent carbon accumulation rates in similar boreal forest-wetland landscapes and eddy covariance landscape net CO2 flux measurements suggest a long-term net CO2 uptake between 49 and 157 g CO2  m-2  yr-1 . Thus, thaw-induced CH4 emission increases likely exert a positive net radiative greenhouse gas forcing through the 21st century.

  16. Flow structure formation and evolution in circulating gas-fluidised beds

    NARCIS (Netherlands)

    Li, J.; Kuipers, J.A.M.

    2004-01-01

    The occurrence of heterogeneous flow structures in gas-particle flows seriously affects the gas-solid contacting and transport processes in high-velocity gas-fluidized beds. Particles do not disperse uniformly in the flow but pass through the bed in a swarm of clusters. The so-called "core-annulus"

  17. Long-term flow monitoring of submarine gas emanations

    Science.gov (United States)

    Spickenbom, K.; Faber, E.; Poggenburg, J.; Seeger, C.

    2009-04-01

    One of the Carbon Capture and Storage (CCS) strategies currently under study is the sequestration of CO2 in sub-seabed geological formations. Even after a thorough review of the geological setting, there is the possibility of leaks from the reservoirs. As part of the EU-financed project CO2ReMoVe (Research, Monitoring, Verification), which aims to develop innovative research and technologies for monitoring and verification of carbon dioxide geological storage, we are working on the development of submarine long-term gas flow monitoring systems. Technically, however, these systems are not limited to CO2 but can be used for monitoring of any free gas emission (bubbles) on the seafloor. The basic design of the gas flow sensor system was derived from former prototypes developed for monitoring CO2 and CH4 on mud volcanoes in Azerbaijan. This design was composed of a raft floating on the surface above the gas vent to collect the bubbles. Sensors for CO2 flux and concentration and electronics for data storage and transmission were mounted on the raft, together with battery-buffered solar panels for power supply. The system was modified for installation in open sea by using a buoy instead of a raft and a funnel on the seafloor to collect the gas, which is then guided above water level through a flexible tube. Besides some technical problems (condensed water in the tube, movement of the buoys due to waves leading to biased measurement of flow rates), this setup provides a cost-effective solution for shallow waters. However, a buoy interferes with ship traffic, and it is also difficult to adapt this design to greater water depths. These requirements can best be complied by a completely submersed system. To allow unattended long-term monitoring in a submarine environment, such a system has to be extremely durable. Therefore, we focussed on developing a mechanically and electrically as simple setup as possible, which has the additional advantage of low cost. The system

  18. 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.

  19. 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...

  20. 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.

  1. 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.

  2. 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...

  3. The wide-range ejector flowmeter: calibrated gas evacuation comprising both high and low gas flows.

    Science.gov (United States)

    Waaben, J; Brinkløv, M M; Jørgensen, S

    1984-11-01

    The wide-range ejector flowmeter is an active scavenging system applying calibrated gas removal directly to the anaesthetic circuit. The evacuation rate can be adjusted on the flowmeter under visual control using the calibration scale ranging from 200 ml X min-1 to 151 X min-1. The accuracy of the calibration was tested on three ejector flowmeters at 12 different presettings. The percentage deviation from presetting varied from + 18 to - 19.4 per cent. The ejector flowmeter enables the provision of consistent and accurately calibrated extraction of waste gases and is applicable within a wide range of fresh gas flows.

  4. 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.

  5. A model of airport security work flow based on petri net

    Science.gov (United States)

    Dong, Xinming

    2017-09-01

    Extremely long lines at airports in the United States have been sharply criticized. In order to find out the bottleneck in the existing security system and put forward reasonable improvement plans and proposal, the Petri net model and the Markov Chain are introduced in this paper. This paper uses data collected by transportation Security Agency (TSA), assuming the data can represent the average level of all airports in the Unites States, to analysis the performance of security check system. By calculating the busy probabilities and the utilization probabilities, the bottleneck is found. Moreover, recommendation is given based on the parameters’ modification in Petri net model.

  6. Viewing inside Pyroclastic Flows - Large-scale Experiments on hot pyroclast-gas mixture flows

    Science.gov (United States)

    Breard, E. C.; Lube, G.; Cronin, S. J.; Jones, J.

    2014-12-01

    Pyroclastic density currents are the largest threat from volcanoes. Direct observations of natural flows are persistently prevented because of their violence and remain limited to broad estimates of bulk flow behaviour. The Pyroclastic Flow Generator - a large-scale experimental facility to synthesize hot gas-particle mixture flows scaled to pyroclastic flows and surges - allows investigating the physical processes behind PDC behaviour in safety. The ability to simulate natural eruption conditions and to view and measure inside the hot flows allows deriving validation and calibration data sets for existing numerical models, and to improve the constitutive relationships necessary for their effective use as powerful tools in hazard assessment. We here report on a systematic series of large-scale experiments on up to 30 ms-1 fast, 2-4.5 m thick, 20-35 m long flows of natural pyroclastic material and gas. We will show high-speed movies and non-invasive sensor data that detail the internal structure of the analogue pyroclastic flows. The experimental PDCs are synthesized by the controlled 'eruption column collapse' of variably diluted suspensions into an instrumented channel. Experiments show four flow phases: mixture acceleration and dilution during free fall; impact and lateral blasting; PDC runout; and co-ignimbrite cloud formation. The fully turbulent flows reach Reynolds number up to 107 and depositional facies similar to natural deposits. In the PDC runout phase, the shear flows develop a four-partite structure from top to base: a fully turbulent, strongly density-stratified ash cloud with average particle concentrations <<1vol%; a transient, turbulent dense suspension region with particle concentrations between 1 and 10 vol%; a non-turbulent, aerated and highly mobile dense underflows with particle concentrations between 40 and 50 vol%; and a vertically aggrading bed of static material. We characterise these regions and the exchanges of energy and momentum

  7. Flammable gas interlock spoolpiece flow response test report

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, T.C., Fluor Daniel Hanford

    1997-03-24

    The purpose of this test report is to document the testing performed under the guidance of HNF-SD-WM-TC-073, {ital Flammable Gas Interlock Spoolpiece Flow Response Test Plan and Procedure}. This testing was performed for Lockheed Martin Hanford Characterization Projects Operations (CPO) in support of Rotary Mode Core Sampling jointly by SGN Eurisys Services Corporation and Numatec Hanford Company. The testing was conducted in the 305 building Engineering Testing Laboratory (ETL). NHC provides the engineering and technical support for the 305 ETL. The key personnel identified for the performance of this task are as follows: Test responsible engineering manager, C. E. Hanson; Flammable Gas Interlock Design Authority, G. P. Janicek; 305 ETL responsible manager, N. J. Schliebe; Cognizant RMCS exhauster engineer, E. J. Waldo/J. D. Robinson; Cognizant 305 ETL engineer, K. S. Witwer; Test director, T. C. Schneider. Other support personnel were supplied, as necessary, from 305/306 ETL. The testing, on the flammable Gas Interlock (FGI) system spoolpiece required to support Rotary Mode Core Sampling (RMCS) of single shell flammable gas watch list tanks, took place between 2-13-97 and 2-25-97.

  8. 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.

  9. Gas flow calibrations performed at the National Metrology Institute of South Africa (NMISA

    Directory of Open Access Journals (Sweden)

    Jonker D.

    2014-01-01

    Full Text Available The National Metrology Institute of South Africa (NMISA Gas Flow Laboratory provides traceability to the South African Industry for gas flow measurements. A new primary standard for gas flow calibrations was purchased and commissioned. With three flow cells, a flow range of 0.5 mL/min to 50 000 mL/min is covered. The main features of this standard are accuracy, speed and convenience. This paper describes the activities of the NMISA Gas Flow Laboratory – a discussion of the primary standard, the validation thereof, calibration methods for client instrumentation, analysis of measurement results and the calculation of measurement uncertainties.

  10. Effect of swirling desolvation gas flow in an atmospheric pressure ion source.

    Science.gov (United States)

    Savtchenko, Serguei; Ashgriz, Nasser; Jolliffe, Chuck; Cousins, Lisa; Gamble, Heather

    2014-09-01

    A numerical study is performed to examine the effect of introducing a swirling desolvation gas flow on the flow transport characteristics in an electrospray and an atmospheric pressure chemical ionization (APCI) system. An ion source having three coaxial tubes is considered: (1) an inner capillary tube to inject the liquid sample, (2) a center coaxial tube to provide a room temperature gas flow to nebulize the liquid, referred to as the nebulizing gas flow, and (3) an outer coaxial tube having a converging exit to supply a high temperature gas for droplet desolvation, referred to as the desolvation gas flow. The results show that a swirling desolvation gas flow reduces the dispersion of the nebulizing gas and suppresses turbulent diffusion. The effect of swirling desolvation flow on the trajectory of a range of droplet sizes emitted from a source is also considered.

  11. Gas flow calculation method of a ramjet engine

    Science.gov (United States)

    Kostyushin, Kirill; Kagenov, Anuar; Eremin, Ivan; Zhiltsov, Konstantin; Shuvarikov, Vladimir

    2017-11-01

    At the present study calculation methodology of gas dynamics equations in ramjet engine is presented. The algorithm is based on Godunov`s scheme. For realization of calculation algorithm, the system of data storage is offered, the system does not depend on mesh topology, and it allows using the computational meshes with arbitrary number of cell faces. The algorithm of building a block-structured grid is given. Calculation algorithm in the software package "FlashFlow" is implemented. Software package is verified on the calculations of simple configurations of air intakes and scramjet models.

  12. The theoretical ideal fresh-gas flow sequence at the start of low-flow anaesthesia.

    Science.gov (United States)

    Mapleson, W W

    1998-03-01

    A spreadsheet model of a circle breathing system and a 70-kg anaesthetised 'standard man' has been used to simulate the first 20 min of low-flow anaesthesia with halothane, enflurane, isoflurane, sevoflurane and desflurane in oxygen. It is shown that, with the fresh-gas flow set initially equal to the total ventilation and the fresh-gas partial pressure to 3 MAC, the end-expired partial pressure can be raised to 1 MAC in 1 min with desflurane and sevoflurane, 1.5 min with isoflurane, 2.5 min with enflurane and 4 min with halothane. Sequences of lower fresh-gas flow and partial pressure settings are given for then maintaining 1 MAC end-expired partial pressure, with a minimum usage of anaesthetic, e.g. 13 ml of liquid desflurane in 20 min (of which only 33% is taken up by the patient) if the minimum acceptable flow is 11.min-1, or 8 ml (with 57% in the patient) if the minimum is 250 ml.min-1.

  13. A net-jet flow system for mass transfer and microsensor studies of sinking aggregates

    DEFF Research Database (Denmark)

    Ploug, H.; Jørgensen, BB

    1999-01-01

    A flow system was developed which enables studies of hydrodynamics and mass transfer in freely sinking aggregates. The aggregates stabilized their positions in the water phase at an upward flow Velocity which balanced and opposed the sinking velocity of the individual aggregate. The flow field...

  14. 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...

  15. Analytical flow/thermal modeling of combustion gas flows in Redesigned Solid Rocket Motor test joints

    Science.gov (United States)

    Woods, G. H.; Knox, E. C.; Pond, J. E.; Bacchus, D. L.; Hengel, J. E.

    1992-07-01

    A one-dimensional analytical tool, TOPAZ (Transient One-dimensional Pipe flow AnalyZer), was used to model the flow characteristics of hot combustion gases through Redesigned Solid Rocket Motor (RSRM) joints and to compute the resultant material surface temperatures and o-ring seal erosion of the joints. The capabilities of the analytical tool were validated with test data during the Seventy Pound Charge (SPC) motor test program. The predicted RSRM joint thermal response to ignition transients was compared with test data for full-scale motor tests. The one-dimensional analyzer is found to be an effective tool for simulating combustion gas flows in RSRM joints and for predicting flow and thermal properties.

  16. Two critical issues in Langevin simulation of gas flows

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jun [James Weir Fluids Laboratory, Department of Mechanical and Aerospace Engineering, University of Strathclyde, Glasgow G1 1XJ, United Kingdom and State Key Laboratory of High Temperature Gas Dynamics, Institute of Mechanics, Chinese Academy of Sciences (China); Fan, Jing [State Key Laboratory of High Temperature Gas Dynamics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-12-09

    A stochastic algorithm based on the Langevin equation has been recently proposed to simulate rarefied gas flows. Compared with the direct simulation Monte Carlo (DSMC) method, the Langevin method is more efficient in simulating small Knudsen number flows. While it is well-known that the cell sizes and time steps should be smaller than the mean free path and the mean collision time, respectively, in DSMC simulations, the Langevin equation uses a drift term and a diffusion term to describe molecule movements, so no direct molecular collisions have to be modeled. This enables the Langevin simulation to proceed with a much larger time step than that in the DSMC method. Two critical issues in Langevin simulation are addressed in this paper. The first issue is how to reproduce the transport properties as that described by kinetic theory. Transport coefficients predicted by Langevin equation are obtained by using Green-Kubo formulae. The second issue is numerical scheme with boundary conditions. We present two schemes corresponding to small time step and large time step, respectively. For small time step, the scheme is similar to DSMC method as the update of positions and velocities are uncoupled; for large time step, we present an analytical solution of the hitting time, which is the crucial factor for accurate simulation. Velocity-Couette flow, thermal-Couette flow, Rayleigh-Bénard flow and wall-confined problem are simulated by using these two schemes. Our study shows that Langevin simulation is a promising tool to investigate small Knudsen number flows.

  17. Study of Solid Particle Behavior in High Temperature Gas Flows

    Science.gov (United States)

    Majid, A.; Bauder, U.; Stindl, T.; Fertig, M.; Herdrich, G.; Röser, H.-P.

    2009-01-01

    The Euler-Lagrangian approach is used for the simulation of solid particles in hypersonic entry flows. For flow field simulation, the program SINA (Sequential Iterative Non-equilibrium Algorithm) developed at the Institut für Raumfahrtsysteme is used. The model for the effect of the carrier gas on a particle includes drag force and particle heating only. Other parameters like lift Magnus force or damping torque are not taken into account so far. The reverse effect of the particle phase on the gaseous phase is currently neglected. Parametric analysis is done regarding the impact of variation in the physical input conditions like position, velocity, size and material of the particle. Convective heat fluxes onto the surface of the particle and its radiative cooling are discussed. The variation of particle temperature under different conditions is presented. The influence of various input conditions on the trajectory is explained. A semi empirical model for the particle wall interaction is also discussed and the influence of the wall on the particle trajectory with different particle conditions is presented. The heat fluxes onto the wall due to impingement of particles are also computed and compared with the heat fluxes from the gas.

  18. 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.

  19. A study of gas flow pattern, undercutting and torch modification in variable polarity plasma arc welding

    Science.gov (United States)

    Mcclure, John C.; Hou, Haihui Ron

    1994-01-01

    A study on the plasma and shield gas flow patterns in variable polarity plasma arc (VPPA) welding was undertaken by shadowgraph techniques. Visualization of gas flow under different welding conditions was obtained. Undercutting is often present with aluminum welds. The effects of torch alignment, shield gas flow rate and gas contamination on undercutting were investigated and suggestions made to minimize the defect. A modified shield cup for the welding torch was fabricated which consumes much less shield gas while maintaining the weld quality. The current torch was modified with a trailer flow for Al-Li welding, in which hot cracking is a critical problem. The modification shows improved weldablility on these alloys.

  20. The effect of changing cow production and fitness traits on net income and greenhouse gas emissions from Australian dairy systems.

    Science.gov (United States)

    Bell, M J; Eckard, R J; Haile-Mariam, M; Pryce, J E

    2013-01-01

    The aim of this study was to compare the effect of changing a range of biological traits on farm net income and greenhouse gas emissions (expressed in carbon dioxide equivalents, CO2-eq.) in the Australian dairy cow population. An average cow was modeled, using breed-average information for Holsteins and Jerseys from the Australian Dairy Herd Improvement Scheme. A Markov chain approach was used to describe the steady-state herd structure, as well as estimate the CO2-eq. emissions per cow and per kilogram of milk solids. The effects of a single unit change in herd milk volume, fat and protein yields, live weight, survival, dry matter intake, somatic cell count, and calving interval were assessed. With the traits studied, the only single-unit change that would bring about a desirable increase in both net income and reduced emissions intensity per cow and per kilogram of milk solids in Australian dairy herds would be an increase in survival and reductions in milk volume, live weight, DMI, SCC, and calving interval. The models developed can be used to assess lifetime dairy system abatement options by breeding, feeding, and management. Selective breeding and appropriate management can both improve health, fertility, and feed utilization of Australian dairy systems and reduce its environmental impact. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  1. Arc-heated gas flow experiments for hypersonic propulsion applications

    Science.gov (United States)

    Roseberry, Christopher Matthew

    Although hydrogen is an attractive fuel for a hypersonic air-breathing vehicle in terms of reaction rate, flame temperature, and energy content per unit mass, the substantial tank volume required to store hydrogen imposes a drag penalty to performance that tends to offset these advantages. An alternative approach is to carry a hydrocarbon fuel and convert it on-board into a hydrogen-rich gas mixture to be injected into the engine combustors. To investigate this approach, the UTA Arc-Heated Wind Tunnel facility was modified to run on methane rather than the normally used nitrogen. Previously, this facility was extensively developed for the purpose of eventually performing experiments simulating scramjet engine flow along a single expansion ramp nozzle (SERN) in addition to more generalized applications. This formidable development process, which involved modifications to every existing subsystem along with the incorporation of new subsystems, is described in detail. Fortunately, only a minor plumbing reconfiguration was required to prepare the facility for the fuel reformation research. After a failure of the arc heater power supply, a 5.6 kW plasma-cutting torch was modified in order to continue the arc pyrolysis experiments. The outlet gas flow from the plasma torch was sampled and subsequently analyzed using gas chromatography. The experimental apparatus converted the methane feedstock almost completely into carbon, hydrogen and acetylene. A high yield of hydrogen, consisting of a product mole fraction of roughly 0.7, was consistently obtained. Unfortunately, the energy consumption of the apparatus was too excessive to be feasible for a flight vehicle. However, other researchers have pyrolyzed hydrocarbons using electric arcs with much less power input per unit mass.

  2. On radial gas flows, the Galactic Bar and chemical evolution in the Galactic Disc

    OpenAIRE

    Portinari, L.; Chiosi, C.

    2000-01-01

    We develop a numerical chemical model allowing for radial flows of gas, with the aim to analyse the possible role of gas flows in the chemical evolution of the Galactic Disc. The dynamical effects of the Galactic Bar on the radial gas profile of the Disc are especially addressed.

  3. Development of a low flow meter for measuring gas production in bioreactors

    Science.gov (United States)

    Accurate measurement of gas production from biological processes is important in many laboratory experiments. A gas flow rate measurement system, consisting of an embedded controller operating three gas meters, was developed to measure volumetric flows between 0 and 8 ml min-1 (1 atm, 273.15 K). The...

  4. Two-dimensional gas flows under heterogeneous combustion of solid porous media

    Science.gov (United States)

    Levin, V. A.; Lutsenko, N. A.

    2017-09-01

    Two-dimensional unsteady gas flows in porous media with heterogeneous-combustion centers are investigated under forced filtration and free convection. With the use of numerical methods, it is shown that complex gas flows including vortex ones can arise under the combustion of solid porous media. In the case of forced filtration, the gas tends to flow around the heated portion of an object preferring to flow along cold regions. Under natural convection, the vortex gas flows, which can exist for a reasonably long time and strongly affect the oxidizer inflow into the reaction zone, arise at the initial moment of the process in the combustion zone and in its vicinities.

  5. Derivation of stable Burnett equations for rarefied gas flows.

    Science.gov (United States)

    Singh, Narendra; Jadhav, Ravi Sudam; Agrawal, Amit

    2017-07-01

    A set of constitutive relations for the stress tensor and heat flux vector for the hydrodynamic description of rarefied gas flows is derived in this work. A phase density function consistent with Onsager's reciprocity principle and H theorem is utilized to capture nonequilibrium thermodynamics effects. The phase density function satisfies the linearized Boltzmann equation and the collision invariance property. Our formulation provides the correct value of the Prandtl number as it involves two different relaxation times for momentum and energy transport by diffusion. Generalized three-dimensional constitutive equations for different kinds of molecules are derived using the phase density function. The derived constitutive equations involve cross single derivatives of field variables such as temperature and velocity, with no higher-order derivative in higher-order terms. This is remarkable feature of the equations as the number of boundary conditions required is the same as needed for conventional Navier-Stokes equations. Linear stability analysis of the equations is performed, which shows that the derived equations are unconditionally stable. A comparison of the derived equations with existing Burnett-type equations is presented and salient features of our equations are outlined. The classic internal flow problem, force-driven compressible plane Poiseuille flow, is chosen to verify the stable Burnett equations and the results for equilibrium variables are presented.

  6. Whole Farm Net Greenhouse Gas Abatement from Establishing Kikuyu-Based Perennial Pastures in South-Western Australia

    Directory of Open Access Journals (Sweden)

    David G. Masters

    2012-08-01

    Full Text Available On-farm activities that reduce GHG emissions or sequester carbon from the atmosphere to compensate for anthropogenic emissions are currently being evaluated by the Australian Government as carbon offset opportunities. The aim of this study was to examine the implications of establishing and grazing Kikuyu pastures, integrated as part of a mixed Merino sheep and cropping system, as a carbon offset mechanism. For the assessment of changes in net greenhouse gas emissions, results from a combination of whole farm economic and livestock models were used (MIDAS and GrassGro. Net GHG emissions were determined by deducting increased emissions from introducing this practice change (increased methane and nitrous oxide emissions due to higher stocking rates from the soil carbon sequestered from growing the Kikuyu pasture. Our results indicate that livestock systems using perennial pastures may have substantially lower net GHG emissions, and reduced GHG intensity of production, compared with annual plant-based production systems. Soil carbon accumulation by converting 45% of arable land within a farm enterprise to Kikuyu-based pasture was determined to be 0.80 t CO2-e farm ha−1 yr−1 and increased GHG emissions (leakage was 0.19 t CO2-e farm ha−1 yr−1. The net benefit of this practice change was 0.61 t CO2-e farm ha−1 yr−1 while the rate of soil carbon accumulation remains constant. The use of perennial pastures improved the efficiency of animal production almost eight fold when expressed as carbon dioxide equivalent emissions per unit of animal product. The strategy of using perennial pasture to improve production levels and store additional carbon in the soil demonstrates how livestock should be considered in farming systems as both sources and sinks for GHG abatement.

  7. 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

  8. Magnetogasdynamic Power Extraction and Flow Conditioning for a Gas Turbine

    Science.gov (United States)

    Adamovich, Igor V.; Rich, J. William; Schneider, Steven; Blankson, Isaiah

    2003-01-01

    An extension of the Russian AJAX concept to a turbojet is being explored. This magnetohydrodynamic (MHD) energy bypass engine cycle incorporating conventional gas turbine technology has MHD flow conditioning at the inlet to electromagnetically extract part of the inlet air kinetic energy. The electrical power generated can be used for various on-board vehicle requirements including plasma flow control around the vehicle or it may be used for augmenting the expanding flow in the high speed nozzle by MHD forces to generate more thrust. In order to achieve this interaction, the air needs to be ionized by an external means even up to fairly high flight speeds, and the leading candidates may be classified as electrical discharge devices. The present kinetic modeling calculations suggest that the use of electron beams with characteristics close to the commercially available e-beam systems (electron energy approx. 60 keV, beam current approx. 0.2 mA/sq cm) to sustain ionization in intermediate pressure, low-temperature (P = 0.1 atm, T = 300 K) supersonic air flows allows considerable reduction of the flow kinetic energy (up to 10 to 20 percent in M = 3 flows). The calculations also suggest that this can be achieved at a reasonable electron beam efficiency (eta approx. 5), even if the e-beam window losses are taken into account. At these conditions, the exit NO and O atom concentrations due to e-beam initiated chemical reactions do not exceed 30 ppm. Increasing the beam current up to approx. 2 mA/sq cm, which corresponds to a maximum electrical conductivity of sigma(sub max) approx. 0.8 mho/m at the loading parameter of K = 0.5, would result in a much greater reduction of the flow kinetic energy (up to 30 to 40 percent). The MHD channel efficiency at these conditions would be greatly reduced (to eta approx. 1) due to increased electron recombination losses in the channel. At these conditions, partial energy conversion from kinetic energy to heat would result in a

  9. Gas molecule-molecule interaction and the gas-surface scattering effect on the rarefied gas flow through a slit into a vacuum

    Science.gov (United States)

    Sazhin, O.

    2009-05-01

    The effect of the gas molecule-molecule interaction and the gas-surface scattering on the gas flow through a slit into a vacuum are investigated in a wide range of the gas rarefaction using the direct simulation Monte Carlo method. To study the gas molecule-molecule interaction influence, we used the variable hard sphere and variable soft sphere models defined for an inverse-power-law potential and the generalized hard sphere model defined for the 12-6 Lennard-Jones potential. The Maxwell, Cercignani-Lampis, and Epstein models were used to simulate the gas-surface scattering. This study demonstrates that the gas molecule-molecule interaction can have a significant influence on the rarefied gas flow through a slit, while the influence of the gas-surface scattering is negligibly small. The presented numerical results are in agreement with the corresponding experimental ones.

  10. Ventilator gas flow rates affect inspiratory time and ventilator efficiency index in term lambs.

    Science.gov (United States)

    Bach, Katinka P; Kuschel, Carl A; Oliver, Mark H; Bloomfield, Frank H

    2009-01-01

    Despite increasing survival in the smallest preterm infants, the incidence of chronic lung disease has not decreased. Research into ventilatory strategies has concentrated on minimising barotrauma, volutrauma and atelectotrauma, but little attention has been paid to the role of bias gas flow rates and the potential for rheotrauma or shear stress injury. Ventilated preterm infants frequently receive relatively high gas flow rates. We hypothesised that altering bias gas flow rates would change the efficiency of ventilation and thereby affect ventilatory parameters. We tested this hypothesis using an artificial lung followed by ventilation of 8 term lambs. Between flows of 2 and 15 l/min, inflation time (Ti) in the artificial lung was inversely related to the bias gas flow rate. In the ventilated lambs, Ti was inversely related to flow rates up to 10 l/min, with no statistically significant effect at flow rates >10 l/min. There were no adverse effects on gas exchange or cardiovascular parameters until a flow rate of 3 l/min was used, when inadequate gas exchange occurred. Ti is inversely associated with the bias gas flow rate. Flow rates much lower than those used in many neonatal units seem to provide adequate ventilation. We suggest that the role of ventilator gas flow rates, which may potentially influence shear stress in ventilator-induced lung injury, merits further investigation. Copyright 2009 S. Karger AG, Basel.

  11. 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.

  12. Probabilistic and Other Neural Nets in Multi-Hole Probe Calibration and Flow Angularity Pattern Recognition

    Science.gov (United States)

    Baskaran, Subbiah; Ramachandran, Narayanan; Noever, David

    1998-01-01

    The use of probabilistic (PNN) and multilayer feed forward (MLFNN) neural networks are investigated for calibration of multi-hole pressure probes and the prediction of associated flow angularity patterns in test flow fields. Both types of networks are studied in detail for their calibration and prediction characteristics. The current formalism can be applied to any multi-hole probe, however the test results for the most commonly used five-hole Cone and Prism probe types alone are reported in this article.

  13. Determination of respiratory gas flow by electrical impedance tomography in an animal model of mechanical ventilation

    OpenAIRE

    Bodenstein, Marc; Boehme, Stefan; Bierschock, Stephan; Vogt, Andreas; David, Matthias; Markstaller, Klaus

    2014-01-01

    Background A recent method determines regional gas flow of the lung by electrical impedance tomography (EIT). The aim of this study is to show the applicability of this method in a porcine model of mechanical ventilation in healthy and diseased lungs. Our primary hypothesis is that global gas flow measured by EIT can be correlated with spirometry. Our secondary hypothesis is that regional analysis of respiratory gas flow delivers physiologically meaningful results. Methods In two s...

  14. Testing of a shrouded, short mixing stack gas eductor model using high temperature primary flow.

    OpenAIRE

    Eick, Ira James.

    1982-01-01

    Approved for public release; distribution is unlimited An existing apparatus for testing models of gas eductor systems using high temperature primary flow was redesigned and modified to provide improved control and performance over a wide range of gas temperatures and flow rates. Pumping coefficient, temperature, and pressure data were recorded for two gas eductor system models. The first, previously tested under hot flow conditions, consisted of a primary plate with four straight nozzle...

  15. 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.

  16. Boundary conditions for gas flow problems from anisotropic scattering kernels

    Science.gov (United States)

    To, Quy-Dong; Vu, Van-Huyen; Lauriat, Guy; Léonard, Céline

    2015-10-01

    The paper presents an interface model for gas flowing through a channel constituted of anisotropic wall surfaces. Using anisotropic scattering kernels and Chapman Enskog phase density, the boundary conditions (BCs) for velocity, temperature, and discontinuities including velocity slip and temperature jump at the wall are obtained. Two scattering kernels, Dadzie and Méolans (DM) kernel, and generalized anisotropic Cercignani-Lampis (ACL) are examined in the present paper, yielding simple BCs at the wall fluid interface. With these two kernels, we rigorously recover the analytical expression for orientation dependent slip shown in our previous works [Pham et al., Phys. Rev. E 86, 051201 (2012) and To et al., J. Heat Transfer 137, 091002 (2015)] which is in good agreement with molecular dynamics simulation results. More important, our models include both thermal transpiration effect and new equations for the temperature jump. While the same expression depending on the two tangential accommodation coefficients is obtained for slip velocity, the DM and ACL temperature equations are significantly different. The derived BC equations associated with these two kernels are of interest for the gas simulations since they are able to capture the direction dependent slip behavior of anisotropic interfaces.

  17. 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.

  18. 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.

  19. 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 [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2012-07-01

    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.

  20. Analysis of commingled gas reservoirs with variable bottom-hole flowing pressure and non-Darcy flow

    Energy Technology Data Exchange (ETDEWEB)

    El-Banbi, A. H.; Wattenbarger, R. A. [Texas A and M Univ., TX (United States)

    1998-12-31

    This paper presents an extension to a previously proposed method for estimating and forecasting production of commingled gas wells. The proposed method is known as the Layered Stabilized Flow Model (LSFM). The extension described in this paper takes into account bottom-hole flowing pressure variations and non-Darcy flow, and provides simulator verifications and field examples. The essence of the LSFM is the coupling of the material balance equation and the stabilized gas flow equation, including non-Darcy flow, for each layer of the commingled gas. It is a simple method, well adapted to spread-sheet applications. It requires only the flow rate and the bottom-hole flowing pressure history, plus the initial reservoir pressure and gas properties to be able to to proceed with reserve estimates. The LSFM parameters are determined by history matching the well`s production rate over a selected calibration period. The results of the LSFM provide estimates of the original gas in place (OGIP) and the two flow equation parameters for each layer, which then can be used for production forecasting. Excellent results have been achieved in field tests in moderate to high permeability reservoirs, even with long shut-ins and significant variation in bottom-hole flowing pressure. 21 refs., 5 tabs., 10 figs.

  1. Production Decline Analysis for Two-Phase Flow in Multifractured Horizontal Well in Shale Gas Reservoirs

    Directory of Open Access Journals (Sweden)

    Wei-Yang Xie

    2015-01-01

    Full Text Available After multistage fracturing, the flowback of fracturing fluid will cause two-phase flow through hydraulic fractures in shale gas reservoirs. With the consideration of two-phase flow and desorbed gas transient diffusion in shale gas reservoirs, a two-phase transient flow model of multistage fractured horizontal well in shale gas reservoirs was created. Accurate solution to this flow model is obtained by the use of source function theory, Laplace transform, three-dimensional eigenvalue method, and orthogonal transformation. According to the model’s solution, the bilogarithmic type curves of the two-phase model are illustrated, and the production decline performance under the effects of hydraulic fractures and shale gas reservoir properties are discussed. The result obtained in this paper has important significance to understand pressure response characteristics and production decline law of two-phase flow in shale gas reservoirs. Moreover, it provides the theoretical basis for exploiting this reservoir efficiently.

  2. 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)

  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. 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

    Multi-parametric flow cytometry (FCM) represents an invaluable instrument to conduct single cell analysis and has significantly increased our understanding of the immune system. However, due to new techniques allowing us to measure an increased number of phenotypes within the immune system, FCM...... for Advancement of Cytometry...

  5. Linear and nonlinear instability in vertical counter-current laminar gas-liquid flows

    CERN Document Server

    Schmidt, Patrick; Lucquiaud, Mathieu; Valluri, Prashant

    2015-01-01

    We consider the genesis and dynamics of interfacial instability in gas-liquid flows, using as a model the two-dimensional channel flow of a thin falling film sheared by counter-current gas. The methodology is linear stability theory (Orr-Sommerfeld analysis) together with direct numerical simulation of the two-phase flow in the case of nonlinear disturbances. We investigate the influence of three main flow parameters (density contrast between liquid and gas, film thickness, pressure drop applied to drive the gas stream) on the interfacial dynamics. Energy budget analyses based on the Orr-Sommerfeld theory reveal various coexisting unstable modes (interfacial, shear, internal) in the case of high density contrasts, which results in mode coalescence and mode competition, but only one dynamically relevant unstable internal mode for low density contrast. The same linear stability approach provides a quantitative prediction for the onset of (partial) liquid flow reversal in terms of the gas and liquid flow rates. ...

  6. Experimental Studies for Determining Gas Flow Rate Accidental Release on Linear Part of Pipeline

    Science.gov (United States)

    Fetisov, V. G.; Nikolaev, A. K.; Lykov, Y. V.

    2017-10-01

    The method of determining the flow rate of gas in the gas-dynamic resistance of a medium gas stream with high linear speed was studied. The reduction of the density of the gas is a result of its expansion. Multiple calculations of gas losses were evaluated. Calculation is set by loss of gas depending on the area of the pipeline damage. A comparative analysis was done. In order to establish a functional empirical dependence of the flow rate on the whole on the parameters of the leakage process, a series of experiments was conducted on a test bench and their processing was carried out. In experiments conducted, the effect of pressure and temperature in the receiver was evaluated, the physical properties of the gas and the diameter of the hole were predetermined by the limits of the amount of the whole flow rate in critical conditions, as well as the critical regime of gas leakage.

  7. 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...

  8. 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...... was approximated by a set of dynamic porous zones, where the grid cells were updated at every iteration based on the transferred nodal positions from the structural model. A time stepping procedure was introduced, so the solver is applicable in both steady and unsteady conditions. In order to reduce...... the computational effort, sub-cycling was applied for the structural solver within each time step, based on the quasi-steady state assumption. The numerical model was validated against experiments in both steady and unsteady conditions. In general, the agreement is satisfactory....

  9. 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.

  10. 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.

  11. Stratified turbulent gas-liquid flow in horizontal and inclined pipes

    Energy Technology Data Exchange (ETDEWEB)

    Shaham, O.; Taitel, V.

    1985-01-01

    A two-dimensional model for stratified turbulent-turbulent gas liquid flow in inclined pipes has been developed. The gas phase is treated as a bulk flow, but an exact solution carried out for the liquid phase. The model is capable of predicting the liquid velocity field, holdup and pressure drop.

  12. Use of schlieren methods to study gas flow in laser technology

    Science.gov (United States)

    Mrňa, Libor; Pavelka, Jan; Horník, Petr; Hrabovský, Jozef

    2016-11-01

    Laser technologies such as welding and cutting rely on process gases. We suggest to use schlieren imaging to visualize the gas flow during these processes. During the process of laser welding, the shielding gas flows to the welded area to prevent oxidation of the weld pool by surrounding air. The gas also interacts with hot plasma spurting from the key hole induced by the laser beam incident on the molten material. This interaction is quite complicated because hot plasma mixes with the cold shielding gas while the system is moving along the weld. Three shielding gases were used in the presented experiment: Ar, He and N2. Differences in dynamics of the flow are clearly visible on schlieren images. Moreover, high speed recording reveals a structure consisting of hot gas bubbles. We were also able to determine the velocity of the bubbles from the recording. During laser cutting, the process gas flows coaxially with the laser beam from the nozzle to remove the molten material out of the kerf. The gas flow is critical for the quality of the resulting edge of the cut. Schlieren method was used to study gas flow under the nozzle and then under the material being cut. This actually creates another slot nozzle. Due to the very low speed of flow below the material the schleiren method is already at the limit of its sensitivity. Therefore, it is necessary to apply a differential technique to increase the contrast. Distinctive widening of the flow shaped by the kerf was observed.

  13. Flow pattern formation in high-velocity gas-fluidised beds

    NARCIS (Netherlands)

    Li, J.; Kuipers, J.A.M.; Grace, J.R.; Zhu, J.; De Hugo, L.

    2002-01-01

    The occurrence of heterogeneous flow structures in gas-particle flows seriously affects the gas-solid contacting and transport processes in high-velocity fluidized beds. A computational study, using a discrete particle method based on Molecular Dynamics techniques, has been carried out to explore

  14. 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 ...

  15. Gas chromatography flow rates for determining deuterium/hydrogen ratios of natural gas by gas chromatography/high-temperature conversion/isotope ratio mass spectrometry.

    Science.gov (United States)

    Jia, Wanglu; Peng, Ping'an; Liu, Jinzhong

    2008-08-01

    The effects of the gas chromatography flow rate on the determination of the deuterium/hydrogen (D/H) ratios of natural gas utilising gas chromatography/high-temperature conversion/isotope ratio mass spectrometry (GC/TC/IRMS) have been evaluated. In general, the measured deltaD values of methane, ethane and propane decrease with increase in column flow rate. When the column flow rate is 1 mL/min or higher, which is commonly used for the determination of D/H ratios of natural gas, the organic H in gas compounds may not be completely converted into hydrogen gas. Based on the results of experiments conducted on a GC column with an i.d. of 0.32 mm, a GC flow rate of 0.6 mL/min is proposed for determining the D/H ratios of natural gas by GC/TC/IRMS. Although this value may be dependent on the instrument conditions used in this work, we believe that correct deltaD values of organic compounds with a few carbon atoms are obtained only when relatively low GC flow rates are used for D/H analysis by GC/TC/IRMS. Moreover, as the presence of trace water could significantly affect the determination of D/H ratios, a newly designed inlet liner was used to remove trace water contained in some gas samples. Copyright (c) 2008 John Wiley & Sons, Ltd.

  16. 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

    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...... of laboratory tests conducted in the Multiphase Flow Laboratory of TEA Sistemi. The transient behavior of the flow system, including the orifice, has also been predicted by means of a 1-D flow simulator [2]. The results of these simulations agree well with the experimental readings, thus providing a powerful......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...

  17. 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

    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....... 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....... 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...

  18. Spinal cord deformation due to nozzle gas flow effects using optical coherence tomography

    Science.gov (United States)

    Wong, Ronnie J.; Jivraj, Jamil; Vuong, Barry; Ramjist, Joel; Sun, Cuiru; Huang, Yize; Yang, Victor X. D.

    2015-03-01

    The use of gas assistance in laser machining hard materials is well established in manufacturing but not in the context of surgery. Laser cutting of osseous tissue in the context of neurosurgery can benefit from gas-assist but requires an understanding of flow and pressure effects to minimize neural tissue damage. In this study we acquire volumetric flow rates through a gas nozzle on the spinal cord, with dura and without dura.

  19. Critical pressure and multiphase flow in Blake Ridge gas hydrates

    Science.gov (United States)

    Flemings, P.B.; Liu, Xiuying; Winters, W.J.

    2003-01-01

    We use core porosity, consolidation experiments, pressure core sampler data, and capillary pressure measurements to predict water pressures that are 70% of the lithostatic stress, and gas pressures that equal the lithostatic stress beneath the methane hydrate layer at Ocean Drilling Program Site 997, Blake Ridge, offshore North Carolina. A 29-m-thick interconnected free-gas column is trapped beneath the low-permeability hydrate layer. We propose that lithostatic gas pressure is dilating fractures and gas is migrating through the methane hydrate layer. Overpressured gas and water within methane hydrate reservoirs limit the amount of free gas trapped and may rapidly export methane to the seafloor.

  20. 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

  1. Besnoitia besnoiti infections activate primary bovine endothelial cells and promote PMN adhesion and NET formation under physiological flow condition.

    Science.gov (United States)

    Maksimov, P; Hermosilla, C; Kleinertz, S; Hirzmann, J; Taubert, A

    2016-05-01

    Besnoitia besnoiti is an obligate intracellular and emerging coccidian parasite of cattle that mainly infects host endothelial cells during acute infection. We here analyzed early innate immune reactions of B. besnoiti-infected primary bovine umbilical vein endothelial cells (BUVEC). B. besnoiti infections significantly activated BUVEC since the gene transcripts of several adhesion molecules (P-selectin, intercellular adhesion molecule 1(ICAM-1)), chemokines (CXCL1, CXCL8, CCL5), and of COX-2 were significantly upregulated during in vitro infection. Overall, the highest upregulation of most transcripts was observed at 24 or 48 h post infection (p.i.). Enhanced adhesion molecule expression in infected host cells was confirmed by PMN adhesion assays being performed under physiological flow conditions revealing a significantly increased PMN adhesion on B. besnoiti-infected BUVEC layers at 24 h p.i. Furthermore, we were able to illustrate neutrophil extracellular traps (NETs) being released by PMN under physiological flow conditions after adhesion to B. besnoiti-infected BUVEC layers. The present study shows that B. besnoiti infections of primary BUVEC induce a cascade of pro-inflammatory reactions and triggers early innate immune responses.

  2. Stability Analysis of High-Speed Boundary-Layer Flow with Gas Injection

    Science.gov (United States)

    2014-06-01

    boundary-layer flow with gas injection 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Alexander V. Fedorov ...distribution unlimited Stability analysis of high-speed boundary-layer flow with gas injection Alexander V. Fedorov * and Vitaly G. Soudakov...Laminar Flow, AGARD Report Number 709, 1984. 2. Fedorov , A., “Transition and Stability of High-Speed Boundary Layers,” Annu. Rev. Fluid Mech., Vol

  3. Gas flow to a barometric pumping well in a multilayer unsaturated zone

    Science.gov (United States)

    You, Kehua; Zhan, Hongbin; Li, Jian

    2011-05-01

    When an open well is installed in an unsaturated zone, gas can flow between the subsurface and the well depending on the gas pressure gradient near the well. This well is called a barometric pumping well (BPW). Quantifying gas flow rate to and from a BPW is indispensable to optimize the passive soil vapor extraction in remediation of volatile organic compounds in the unsaturated zone. This study presents a two-dimensional (2-D) semianalytical solution for a multilayer unsaturated zone (ML solution) to determine gas flow rate to and from a BPW. The gas flow rate is approximated by a decomposing method frequently used in previous studies, that is, first solving the one-dimensional (1-D) vertical flow equation in response to the surface barometric pressure fluctuations and then superimposing this solution on that of the 1-D horizontally radial flow equation. The error induced by this approximation is quantified by a 2-D numerical simulation for the first time in this study. Results show that the maximum error induced is 20% at the peak flow rates. The ML solution is demonstrated to be sufficient for predicting subsurface gas pressure and gas flow rate in a multilayer unsaturated zone by the barometric pumping test at the Hanford site.

  4. 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.

  5. 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.

  6. Study on direct measurement of diesel exhaust gas flow rate. Development of ultrasonic exhaust gas flowmeter; Diesel hai gas ryuryo no chokusetsu sokuteiho ni kansuru kenkyu. Choonpa hai gas ryuryokeino kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Yamazaki, A.; Takamoto, M.; Yamzaki, H. [National Research Laboratory of Meteology, Tsukuba (Japan); Hosoi, K. [Japan Automobile Research Institute Inc., Tsukuba (Japan); Arai, S.; Shimizu, K. [Kaijo Corp., Tokyo (Japan)

    2000-02-25

    The partial flow dilution method is one of the typical measurement methods for particulate matter emission from diesel engines. In this method, exhaust gas at a transient flow rate should be transferred to a dilution tunnel at a constant ratio of exhaust gas. The present partial flow dilution method is used under steady-state engine operating conditions in lieu of direct flow rate measurement of exhaust gas. A more practical control of exhaust emission is, however, required world widely; therefore development of an exhaust gas flowmeter is indispensable in the partial flow dilution method for transient engine operating conditions. An ultrasonic exhaust gas flowmeter has been developed and been demonstrated to be capable of measuring the exhaust gas flow rate with sufficient accuracy. (author)

  7. 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.

  8. LDA/PIV measurements of gas flow in a 4-stroke motored engine

    Energy Technology Data Exchange (ETDEWEB)

    Obokata, T.; Kato, M.; Ishima, T. [Gunma Univ., Tenjin, Kiryu (Japan). Graduate School of Mechanical Engineering; Kaneko, M. [Fuji Heavy Industries Ltd., Tokyo (Japan)

    2009-07-01

    The key technology for improving the internal combustion engine involves understanding and controlling the gas flows in the cylinder. However, it is not easy to understand the turbulence characteristics of gas flows because they are intermittent, highly turbulent, and three-dimensional complex flows. Numerical simulations of gas flow and combustion are important and powerful tools to understand the gas flows in the cylinder. It is important to verify the numerical simulation results by the reliable and detailed experimental data obtained at the same engine. This presentation discussed an investigation on the turbulent characteristics of in-cylinder flows at the same engine by laser doppler anemometry (LDA) and particulate image velocimetry for verifying the numerical results. Turbulent characteristics of gas flow in the internal combustion engine were also experimentally analysed under various operating conditions. The experimental setup was illustrated and the specifications of LDA and the test engine were identified. The prototype tumble generation valve was also illustrated and the results of the measurement of flow velocity through an intake valve and measurement of in-cylinder flow velocity were offered. Animations of the flow velocity through a valve were also presented. It was concluded that the effect of the turbulence generating valve (TGV) was clarified by the experimental data. The effect of the TGV was remarkable in the upper side of the cylinder. tabs., figs.

  9. 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.

  10. Klinkenberg effect in hydrodynamics of gas flow through anisotropic porous materials

    Directory of Open Access Journals (Sweden)

    Wałowski Grzegorz

    2017-01-01

    Full Text Available This study discusses results of experiments on hydrodynamic assessment of gas flow through backbone (skeletal porous materials with an anisotropic structure. The research was conducted upon materials of diversified petrographic characteristics, both natural origin (rocky, pumice and process materials (char and coke. The study was conducted for a variety of hydrodynamic conditions, using air, as well as for nitrogen and carbon dioxide. The basis for assessing hydrodynamics of gas flow through porous material was a gas stream that results from the pressure forcing such flow. The results of measurements indicate a clear impact of the type of material on the gas permeability, and additionally – as a result of their anisotropic internal structure – to a significant effect of the flow direction on the value of gas stream.

  11. 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

    The supersonic separator is a novel technique to remove the condensable components from gas mixtures. But the particle behavior is not well understood in this complex supersonic flow. The Discrete Particle Method was used here to study the particle motion in supersonic flows with a strong swirl....... The results showed that the gas flow was accelerated to supersonic velocity, and created the low pressure and temperature conditions for gas removal. Most of the particles collided with the walls or entered into the liquid-collection space directly, while only a few particles escaped together with the gas...... 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...

  12. 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

  13. DSMC-computation of the Rarefied Gas Flow through a Slit into a Vacuum

    Science.gov (United States)

    Sazhin, Oleg

    2008-12-01

    The gas rarefaction, gas molecule-molecule interaction and gas-surface scattering influence on the gas flow through a slit into a vacuum is investigated by the direct simulation Monte Carlo (DSMC) method. To study the gas molecule-molecule interaction influence on the gas flow we used the hard sphere (HS), variable hard sphere (VHS) anc variable soft sphere (VSS) models defined for the inverse-power-law (IPL) potential and also the generalized hard sphere (GHS) model defined for the 12-6 Lennard-Jones (LJ) potential. Maxwell (specular-diffuse scheme), Cercignani-Lampis (CL) and Epstein approaches were used to simulate the gas-surface scattering. The results of computations of the mas; flow rate in a wide range of rarefactions and distributions of the density, temperature and mass velocity, and streamlines are presented. This study demonstrates that the gas molecule-molecule interaction significantly interferes with the gas flow through a slit, while the influence of the gas-surface scattering is negligibly small. Our results are in agreement with the corresponding theoretical asymptotes, experimental and numerical data.

  14. Experimental study on gas-liquid bubbly turbulent flow in a large square duct

    Science.gov (United States)

    Sun, Haomin; Kunugi, Tomoaki; Nakamura, Hideo

    2012-11-01

    Gas-liquid bubbly turbulent flow exists in many industrial areas. Therefore, many experiments for gas-liquid bubbly turbulent flow have been carried out in circular pipes for bubbly turbulent flow model. However, the cross-section of many flow passages are not the circular shape. Since the secondary flow of 2nd kind for single phase turbulent flow in a non-circular duct is well-known, the interaction between the secondary flow of 2nd kind and bubbles in gas-liquid bubbly turbulent flow in the non-circular duct could play an important role. In this study, in order to validate gas-liquid bubbly turbulent flow model in the non-circular duct, measurements were performed in a large square (136 mm × 136 mm) duct with duct length of 2.8m. The distributions of primary velocity, void fraction and turbulent Reynolds stresses were measured by a hot film probe. It is well-known that the primary velocity distribution of the bubbly flow in a circular pipe has a peak in the pipe center. In contrast, it was found that the primary velocity peaked near the corner of the square duct. In addition, primary velocity distribution changes under various flow conditions were discussed by measuring data of the void fraction and turbulent Reynolds stresses. Financially Supported by JSPS and G-COE Program(J-051).

  15. 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.

  16. 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.

  17. 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.

  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. Melt flow characteristics in gas-assisted laser cutting

    Indian Academy of Sciences (India)

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

    laser cutting, the gas jet plays two roles, one is to generate additional thermal energy during formation of FeO and other oxides. This additional energy enhances the process parameters like cutting speed and thickness of the workpiece. The second role is to supply the shear force to the gas/liquid boundary to eject the ...

  20. 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

  1. Gas Flow in the Capillary of the Atmosphere-to-Vacuum Interface of Mass Spectrometers

    Science.gov (United States)

    Skoblin, Michael; Chudinov, Alexey; Soulimenkov, Ilia; Brusov, Vladimir; Kozlovskiy, Viacheslav

    2017-10-01

    Numerical simulations of a gas flow through a capillary being a part of mass spectrometer atmospheric interface were performed using a detailed laminar flow model. The simulated interface consisted of atmospheric and forevacuum volumes connected via a thin capillary. The pressure in the forevacuum volume where the gas was expanding after passing through the capillary was varied in the wide range from 10 to 900 mbar in order to study the volume flow rate as well as the other flow parameters as functions of the pressure drop between the atmospheric and forevacuum volumes. The capillary wall temperature was varied in the range from 24 to 150 °C. Numerical integration of the complete system of Navier-Stokes equations for a viscous compressible gas taking into account the heat transfer was performed using the standard gas dynamic simulation software package ANSYS CFX. The simulation results were compared with experimental measurements of gas flow parameters both performed using our experimental setup and taken from the literature. The simulated volume flow rates through the capillary differed no more than by 10% from the measured ones over the entire pressure and temperatures ranges. A conclusion was drawn that the detailed digital laminar model is able to quantitatively describe the measured gas flow rates through the capillaries under conditions considered. [Figure not available: see fulltext.

  2. Gas Flow in the Capillary of the Atmosphere-to-Vacuum Interface of Mass Spectrometers.

    Science.gov (United States)

    Skoblin, Michael; Chudinov, Alexey; Soulimenkov, Ilia; Brusov, Vladimir; Kozlovskiy, Viacheslav

    2017-10-01

    Numerical simulations of a gas flow through a capillary being a part of mass spectrometer atmospheric interface were performed using a detailed laminar flow model. The simulated interface consisted of atmospheric and forevacuum volumes connected via a thin capillary. The pressure in the forevacuum volume where the gas was expanding after passing through the capillary was varied in the wide range from 10 to 900 mbar in order to study the volume flow rate as well as the other flow parameters as functions of the pressure drop between the atmospheric and forevacuum volumes. The capillary wall temperature was varied in the range from 24 to 150 °C. Numerical integration of the complete system of Navier-Stokes equations for a viscous compressible gas taking into account the heat transfer was performed using the standard gas dynamic simulation software package ANSYS CFX. The simulation results were compared with experimental measurements of gas flow parameters both performed using our experimental setup and taken from the literature. The simulated volume flow rates through the capillary differed no more than by 10% from the measured ones over the entire pressure and temperatures ranges. A conclusion was drawn that the detailed digital laminar model is able to quantitatively describe the measured gas flow rates through the capillaries under conditions considered. Graphical Abstract ᅟ.

  3. Gas phase dispersion in compost as a function of different water contents and air flow rates

    Science.gov (United States)

    Sharma, Prabhakar; Poulsen, Tjalfe G.

    2009-07-01

    Gas phase dispersion in a natural porous medium (yard waste compost) was investigated as a function of gas flow velocity and compost volumetric water content using oxygen and nitrogen as tracer gases. The compost was chosen because it has a very wide water content range and because it represents a wide range of porous media, including soils and biofilter media. Column breakthrough curves for oxygen and nitrogen were measured at relatively low pore gas velocities, corresponding to those observed in for instance soil vapor extraction systems or biofilters for air cleaning at biogas plants or composting facilities. Total gas mechanical dispersion-molecular diffusion coefficients were fitted from the breakthrough curves using a one-dimensional numerical solution to the advection-dispersion equation and used to determine gas dispersivities at different volumetric gas contents. The results showed that gas mechanical dispersion dominated over molecular diffusion with mechanical dispersion for all water contents and pore gas velocities investigated. Importance of mechanical dispersion increased with increasing pore gas velocity and compost water content. The results further showed that gas dispersivity was relatively constant at high values of compost gas-filled porosity but increased with decreasing gas-filled porosity at lower values of gas-filled porosity. Results finally showed that measurement uncertainty in gas dispersivity is generally highest at low values of pore gas velocity.

  4. Magnetogasdynamic effects during the interaction between a gas and erosion plasma flows in a magnetoplasma compressor

    Science.gov (United States)

    Ardelian, N. V.; Kamrukov, A. S.; Kozlov, N. P.; Kosmachevskii, K. V.; Popov, Iu. P.

    The physics of the interaction between a gas and erosion plasma flows is examined with reference to the results of a numerical experiment. It is shown that the interaction of a radially inhomogeneous flow with a deformable gas obstacle leads to the formation of a conical shock MHD-wave, with a local increase in pressure, temperature, and magnetic field at its front. Behind the shock wave, the plasma flow turns parallel to the contact boundary, with a noticeable increase in the radial velocity component. This leads to a significant increase in flow cumulation efficiency in comparison with a vacuum magnetoplasma compressor.

  5. Quantification of Carbon Dioxide Removal at Low Sweep Gas and Blood Flows.

    Science.gov (United States)

    de Villiers Hugo, Juan; Sharma, Ajay S; Ahmed, Usaama; Weerwind, Patrick W

    2017-12-01

    Advancement in oxygenator membrane technology has further expanded the boundaries in the clinical application of extracorporeal carbon dioxide removal (ECCO2R). Despite the advent of modern poly-4-methyl-1-pentene (PMP) membranes, limited information exists on the performance of these membranes at low sweep gas and blood flows. Moreover, physiological relationships for CO2 removal at these flows are less explored. Hence, CO2 removal was quantified in an in vitro setting using a PMP membrane oxygenator. ECCO2R was performed using a .8 m2 surface pediatric oxygenator in an in vitro setting with freshly drawn single-source porcine blood. In this setting, low blood flows of either 200 or 350 mL/min were generated, with sweep gas flow rates of 100, 200, and 400 mL/min, respectively. CO2 transfer ranged from 14.05 ± 4.35 mL/min/m2 to 18.76 ± 4.26 mL/min/m2 at a sweep gas to a blood flow ratio of .5:1 to 2:1 (p gas to blood flow ratio, while maintaining a constant gas flow, did not show a significant increase in CO2 extraction (p > .05). At these test parameters, an increase in sweep gas improved the CO2 transfer, whereas an increase in blood flow resulted in a lower CO2 transfer. These results indicate that CO2 removal in low-flow ECCO2R is mainly sweep gas flow driven. Although these settings might not be applicable for clinical use, this study gives tangible information about the important factor involved in ECCO2R.

  6. Gas-Liquid flow characterization in bubble columns with various gas-liquid using electrical resistance tomography

    Science.gov (United States)

    Jin, Haibo; Yuhuan, Han; Suohe, Yang

    2009-02-01

    Electrical resistance tomography (ERT) is an advanced and new detecting technique that can measure and monitor the parameters of two-phase flow on line, such as gas-liquid bubble column. It is fit for the industrial process where the conductible medium serves as the disperse phase to present the key bubble flow characteristics in multi-phase medium. Radial variation of the gas holdup and mean holdups are investigated in a 0.160 m i. d. bubble column using ERT with two axial locations (Plane 1 and Plane 2). In all the experiments, air was used as the gas phase, tap water as liquid phase, and a series of experiments were done by adding KCl, ethanol, oil sodium, and glycerol to change liquid conductivity, liquid surface tension and viscosity. The superficial gas velocity was varied from 0.02 to 0.2 m/s. The effect of conductivity, surface tension, viscosity on the mean holdups and radial gas holdup distribution is discussed. The results showed that the gas holdup decrease with the increase of surface tension and increase with the increase of viscosity. Meanwhile, the settings of initial liquid conductivity slightly influence the gas holdup values, and the experimental data increases with the increase of the initial setting values in the same conditions.

  7. WETTABILITY ALTERATION OF POROUS MEDIA TO GAS-WETTING FOR IMPROVING PRODUCTIVITY AND INJECTIVITY IN GAS-LIQUID FLOWS

    Energy Technology Data Exchange (ETDEWEB)

    Abbas Firoozabadi

    2003-12-01

    Wettability alteration to intermediate gas-wetting in porous media by treatment with FC-759, a fluoropolymer polymer, has been studied experimentally. Berea sandstone was used as the main rock sample in our work and its wettability before and after chemical treatment was studied at various temperatures from 25 to 93 C. We also studied recovery performance for both gas/oil and oil/water systems for Berea sandstone before and after wettability alteration by chemical treatment. Our experimental study shows that chemical treatment with FC-759 can result in: (1) wettability alteration from strong liquid-wetting to stable intermediate gas-wetting at room temperature and at elevated temperatures; (2) neutral wetting for gas, oil, and water phases in two-phase flow; (3) significant increase in oil mobility for gas/oil system; and (4) improved recovery behavior for both gas/oil and oil/water systems. This work reveals a potential for field application for improved gas-well deliverability and well injectivity by altering the rock wettability around wellbore in gas condensate reservoirs from strong liquid-wetting to intermediate gas-wetting.

  8. Lagrangian approach to modeling unsteady gas-liquid flow in a well

    Science.gov (United States)

    Liapidevskii, V. Yu; Tikhonov, V.

    2016-06-01

    The purpose of this paper is to develop a numerical method of solving the problem of evolution of the finite gas volume that entered in a liquid flow at a set flow rate. The drift- flux model is used as gas-liquid mixture equations. The velocities of both phases, mixture and gas, are related by the Zuber-Findlay equation which coefficients depend on flow regime and gas void fraction. Lagrangian coordinates are used to simplify the initial equations. The numerical solution scheme is proposed. The numerical solution of the Riemann problem is verified by comparison with the exact self-similar solution. The model and numerical method efficiency is illustrated by examples of gas kick calculations in a vertical well.

  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. Gas-Kinetic Computational Algorithms for Hypersonic Flows in Continuum and Transitional Regimes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I project explores two gas-kinetic computational algorithms for simulation of hypersonic flows in both continuum and transitional regimes. One is the...

  11. 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....

  12. 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

  13. 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.

  14. 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

  15. Experimental and CFD Simulations of Vertical Two-Phase Slug Flow for Gas-Newtonian and Non-Newtonian Liquids

    DEFF Research Database (Denmark)

    Ratkovich, Nicolas Rios; Bentzen, Thomas Ruby; Majumder, S.

    Gas-liquid two-phase flows are presented everywhere in industrial processes (i.e. gas-oil pipelines). In spite of the common occurrence of these two-phase flows, their understanding is limited compared to single-phase flows. Different studies on two-phase flow have focus on developing empirical c...

  16. Pressure loss in natural gas pipelines: Experimental studies of gas-particle flow, wall roughness and drag reduction

    Energy Technology Data Exchange (ETDEWEB)

    Strupstad, Andre

    2009-05-15

    Laboratory experiments on air-particle flow were performed in a horizontal once-through flow rig, with internal pipe diameters of 24 mm. Reynolds number was 40000 - 180000, temperatures 20 deg. Celsius and pressure below 2 bara. Spherical polystyrene and magnetite particles with mean diameters from 64 mum to 175 mum were used. The pressure loss in the experiments was best expressed in terms of friction factor. Differential pressure drop gave limited information because reduction in this value was due to change in the gas properties during particle injection. The reduction in the differential pressure was due to the increase in the absolute pressure, which resulted in an increased gas density. This increased density, which with an approximately constant gas mass flow, resulted in a lower volume flow, and thereby a lower gas velocity. A lower gas velocity results in a lower differential pressure. A calculation of the friction factors, which increased, showed that these reductions in the differential pressures were not drag reductions. Roughness measurements were made on three types of surfaces with a stylus instrument: 47 epoxy coated steel surfaces as used in natural gas pipelines, 5 plexiglass surfaces used in our flow experiments, and 9 steel surfaces. The roughness profiles obtained were used to calculate amplitude roughness parameters and texture roughness parameters. Theory of gas-particle drag reduction in pipes was reviewed. Turbulence attenuation was a necessary but not a sufficient condition for drag reduction to occur. Small particle diameter was identified as an important condition for achieving drag reduction. Also, relevant parameters for achieving turbulence attenuation were identified, including the Stokes number, ratio between particle diameter and pipe diameter and the particle Reynolds number. In the flow experiments the gas friction factor increased by up to 16 % with injection of particles as compared to particle free flow. The increase depended

  17. Determination of respiratory gas flow by electrical impedance tomography in an animal model of mechanical ventilation.

    Science.gov (United States)

    Bodenstein, Marc; Boehme, Stefan; Bierschock, Stephan; Vogt, Andreas; David, Matthias; Markstaller, Klaus

    2014-04-29

    A recent method determines regional gas flow of the lung by electrical impedance tomography (EIT). The aim of this study is to show the applicability of this method in a porcine model of mechanical ventilation in healthy and diseased lungs. Our primary hypothesis is that global gas flow measured by EIT can be correlated with spirometry. Our secondary hypothesis is that regional analysis of respiratory gas flow delivers physiologically meaningful results. In two sets of experiments n = 7 healthy pigs and n = 6 pigs before and after induction of lavage lung injury were investigated. EIT of the lung and spirometry were registered synchronously during ongoing mechanical ventilation. In-vivo aeration of the lung was analysed in four regions-of-interest (ROI) by EIT: 1) global, 2) ventral (non-dependent), 3) middle and 4) dorsal (dependent) ROI. Respiratory gas flow was calculated by the first derivative of the regional aeration curve. Four phases of the respiratory cycle were discriminated. They delivered peak and late inspiratory and expiratory gas flow (PIF, LIF, PEF, LEF) characterizing early or late inspiration or expiration. Linear regression analysis of EIT and spirometry in healthy pigs revealed a very good correlation measuring peak flow and a good correlation detecting late flow. PIFEIT = 0.702 · PIFspiro + 117.4, r(2) = 0.809; PEFEIT = 0.690 · PEFspiro-124.2, r(2) = 0.760; LIFEIT = 0.909 · LIFspiro + 27.32, r(2) = 0.572 and LEFEIT = 0.858 · LEFspiro-10.94, r(2) = 0.647. EIT derived absolute gas flow was generally smaller than data from spirometry. Regional gas flow was distributed heterogeneously during different phases of the respiratory cycle. But, the regional distribution of gas flow stayed stable during different ventilator settings. Moderate lung injury changed the regional pattern of gas flow. We conclude that the presented method is able to determine global respiratory gas flow of the lung in different phases of the respiratory

  18. 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....

  19. A powerful electrohydrodynamic flow generated by a high-frequency dielectric barrier discharge in a gas

    Energy Technology Data Exchange (ETDEWEB)

    Nebogatkin, S. V.; Rebrov, I. E.; Khomich, V. Yu.; Yamshchikov, V. A., E-mail: yamschikov52@mail.ru [Russian Academy of Sciences, Institute for Electrophysics and Electric Power (Russian Federation)

    2016-01-15

    Theoretical and experimental studies of an electrohydrodynamic flow induced by a high-frequency dielectric barrier discharge distributed over a dielectric surface in a gas have been conducted. Dependences of the ion current, the gas flow velocity, and the spatial distributions thereof on the parameters of the power supply of the plasma ion emitter and an external electric field determined by the collector grid voltage have been described.

  20. Stability Analysis of High-Speed Boundary-Layer Flow with Gas Injection (Briefing Charts)

    Science.gov (United States)

    2014-06-01

    boundary-layer flow with gas injection 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Alexander V. Fedorov ...Release; Distribution Unlimited Stability analysis of high-speed boundary-layer flow with gas injection Alexander Fedorov and Vitaly Soudakov Moscow...Dispersion relation from WKB analysis*,**: *Guschin, V.R., & Fedorov , A.V., Fluid Dynamics, Vol. 24, No.1, 1989 **Guschin, V.R., & Fedorov , A.V., NASA

  1. 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.

  2. 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

  3. Analysis of Diffusion Coefficient using Reversed-Flow Gas Chromatography-A Review

    OpenAIRE

    Khalisanni Khalid; Rashid A. Khan; Sharifuddin M. Zain

    2011-01-01

    Problem statement: Since the earliest publication on the technique, Reversed-Flow Gas Chromatography (RF-GC) has been used to determine physicochemical properties by measuring the value of one in the presence of another. The method is precise, accurate and simple compared to other conventional techniques. Approach: The experimental setup consists of a small modification of a commercial gas chromatograph, so that it includes a four- or six-port gas sampling valve and a simp...

  4. Flow modulation comprehensive two-dimensional gas chromatography-mass spectrometry using ≈4 mL min(-1) gas flows.

    Science.gov (United States)

    Franchina, Flavio A; Maimone, Mariarosa; Tranchida, Peter Q; Mondello, Luigi

    2016-04-08

    The main objective of the herein described research was focused on performing satisfactory flow modulation (FM), in comprehensive two-dimensional gas chromatography-mass spectrometry (GC×GC-MS), using an MS-compatible second-dimension gas flow of approx. 4 mL min(-1). The FM model used was based on that initially proposed by Seeley et al. [3]. The use of limited gas flows was enabled through fine tuning of the FM parameters, in particular the duration of the re-injection (or flushing) process. Specifically, the application of a long re-injection period (i.e., 700 ms) enabled efficient accumulation-loop flushing with gas flows of about 4 mL min(-1). It was possible to apply such extended re-injection periods by using different restrictor lengths in the connections linking the modulator to the auxiliary pressure source. FM GC×GC-MS applications were performed on a mixture containing C9-10 alkanes, and on a sample of essential oil. GC×GC-MS sensitivity was compared with that attained by using conventional GC-MS analysis, in essential oil applications. It was observed that signal intensities were, in general, considerably higher in the FM GC×GC-MS experiments. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Net Greenhouse Gas Budget and Soil Carbon Storage in a Field with Paddy–Upland Rotation with Different History of Manure Application

    Directory of Open Access Journals (Sweden)

    Fumiaki Takakai

    2017-06-01

    Full Text Available Methane (CH4 and nitrous oxide (N2O fluxes were measured from paddy–upland rotation (three years for soybean and three years for rice with different soil fertility due to preceding compost application for four years (i.e., 3 kg FW m−2 year−1 of immature or mature compost application plots and a control plot without compost. Net greenhouse gas (GHG balance was evaluated by integrating CH4 and N2O emissions and carbon dioxide (CO2 emissions calculated from a decline in soil carbon storage. N2O emissions from the soybean upland tended to be higher in the immature compost plot. CH4 emissions from the rice paddy increased every year and tended to be higher in the mature compost plot. Fifty-two to 68% of the increased soil carbon by preceding compost application was estimated to be lost during soybean cultivation. The major component of net GHG emission was CO2 (82–94% and CH4 (72–84% during the soybean and rice cultivations, respectively. Net GHG emissions during the soybean and rice cultivations were comparable. Consequently, the effects of compost application on the net GHG balance from the paddy–upland rotation should be carefully evaluated with regards to both advantages (initial input to the soil and disadvantages (following increases in GHG.

  6. Fluctuations and Correlations of net baryon number, electric charge, and strangeness: A comparison of lattice QCD results with the hadron resonance gas model

    CERN Document Server

    Bazavov, A; DeTar, C E; Ding, H -T; Gottlieb, Steven; Gupta, Rajan; Hegde, P; Heller, Urs; Karsch, F; Laermann, E; Levkova, L; Mukherjee, Swagato; Petreczky, P; Schmidt, Christian; Soltz, R A; Soeldner, W; Sugar, R; Vranas, Pavlos M

    2012-01-01

    We calculate the quadratic fluctuations of net baryon number, electric charge and strangeness as well as correlations among these conserved charges in (2+1)-flavor lattice QCD at zero chemical potential. Results in the continuum limit are obtained using calculations with tree level improved gauge and the highly improved staggered quark (HISQ) actions with almost physical light and strange quark masses at three different values of the lattice cut-off. We compare our results with the hadron resonance gas (HRG) model calculations and find agreement with HRG model results only for temperatures T < 150 MeV. We observe significant deviations in the temperature range 160 MeV < T < 170 MeV and qualitative differences in the behavior of the three conserved charge sectors. At $T \\simeq 160 MeV$ quadratic net baryon number fluctuations in QCD agree with HRG model calculations while, the net electric charge fluctuations in QCD are about 10% smaller and net strangeness fluctuations are about 20% larger. These fin...

  7. Miniature liquid flow sensor and feedback control of electroosmotic and pneumatic flows for a micro gas analysis system.

    Science.gov (United States)

    Ohira, Shin-Ichi; Toda, Kei

    2006-01-01

    Accurate liquid flow control is important in most chemical analyses. In this work, the measurement of liquid flow in microliters per minute was performed, and feedback control of the flow rate was examined. The flow sensor was arranged on a channel made in a polydimethylsiloxane (PDMS) block. The center of the channel was cooled by a miniature Peltier device, and the change in temperature balance along the channel formed by the flow was measured by two temperature sensors. Using this flow sensor, feedback flow control was examined with two pumping methods. One was the electroosmotic flow method, made by applying a high voltage (HV) between the reagent and waste reservoirs; the other was the piezo valve method, in which a micro-valve-seat was fabricated in a PDMS cavity with a silicone diaphragm. The latter was adopted for a micro gas analysis system (microGAS) for measuring atmospheric H2S and SO2. The obtained baselines were stable, and better limits of detection were obtained.

  8. Standardization of flow cytometry in myelodysplastic syndromes: report from the first European LeukemiaNet working conference on flow cytometry in myelodysplastic syndromes

    Science.gov (United States)

    van de Loosdrecht, Arjan A.; Alhan, Canan; Béné, Marie Christine; Della Porta, Matteo G.; Dräger, Angelika M.; Feuillard, Jean; Font, Patricia; Germing, Ulrich; Haase, Detlef; Homburg, Christa H.; Ireland, Robin; Jansen, Joop H.; Kern, Wolfgang; Malcovati, Luca; te Marvelde, Jeroen G.; Mufti, Ghulam J.; Ogata, Kiyoyuki; Orfao, Alberto; Ossenkoppele, Gert J.; Porwit, Anna; Preijers, Frank W.; Richards, Stephen J.; Schuurhuis, Gerrit Jan; Subirá, Dolores; Valent, Peter; van der Velden, Vincent H.J.; Vyas, Paresh; Westra, August H.; de Witte, Theo M.; Wells, Denise A.; Loken, Michael R.; Westers, Theresia M.

    2009-01-01

    The myelodysplastic syndromes are a group of clonal hematopoietic stem cell diseases characterized by cytopenia(s), dysplasia in one or more cell lineages and increased risk of evolution to acute myeloid leukemia (AML). Recent advances in immunophenotyping of hematopoietic progenitor and maturing cells in dysplastic bone marrow point to a useful role for multiparameter flow cytometry (FCM) in the diagnosis and prognostication of myelodysplastic syndromes. In March 2008, representatives from 18 European institutes participated in a European LeukemiaNet (ELN) workshop held in Amsterdam as a first step towards standardization of FCM in myelodysplastic syndromes. Consensus was reached regarding standard methods for cell sampling, handling and processing. The group also defined minimal combinations of antibodies to analyze aberrant immunophenotypes and thus dysplasia. Examples are altered numbers of CD34+ precursors, aberrant expression of markers on myeloblasts, maturing myeloid cells, monocytes or erythroid precursors and the expression of lineage infidelity markers. When applied in practice, aberrant FCM patterns correlate well with morphology, the subclassification of myelodysplastic syndromes, and prognostic scoring systems. However, the group also concluded that despite strong evidence for an impact of FCM in myelodysplastic syndromes, further (prospective) validation of markers and immunophenotypic patterns are required against control patient groups as well as further standardization in multi-center studies. Standardization of FCM in myelodysplastic syndromes may thus contribute to improved diagnosis and prognostication of myelodysplastic syndromes in the future. PMID:19546437

  9. FLOW REGIMES, GAS HOLD-UP AND AXIAL GAS MIXING IN THE GAS-LIQUID MULTISTAGE AGITATED CONTACTOR

    NARCIS (Netherlands)

    BREMAN, BB; BEENACKERS, AACM; BOUMA, MJ

    Experimental data are reported on Row regimes, gas hold-up and axial gas mixing of a gas-liquid Multi-stage Agitated Contactor (MAC), consisting of nine compartments [height, H, over diameter, D = 1; D = 0.09 m) separated by horizontal baffles with an opening of 0.04 m and with one centrally

  10. Influence of blast furnace gas flow speed on dust deposition characteristics in butterfly valve region

    Directory of Open Access Journals (Sweden)

    Lixin WANG

    2016-02-01

    Full Text Available The blast furnace gas contains plenty of dust, which deposits easily on the bottom of seat sealing surface of the tri-eccentric butterfly valve in the pipeline, causing stuck and damage to the valve plate, thereby affects the production of the blast furnace and brings great economic loss. To derive the influence mechanism of effects of the blast furnace gas flow speed within the pipeline on the dust deposition laws in the butterfly valve region, a 3D model of the butterfly valve and its regional flow field is built with Pro/E software. Based on FLUENT module of ANSYS Workbench, along with standard k-ε turbulence model and DPM model, simulation analysis of moving trajectories of dust particles in butterfly valve region under 3 blast furnace gas flow speeds is conducted. Results show that the deposition mass of dust particles decreases firstly, then increases with the enlargement of valve plate opening angle under the blast furnace gas flow speed of 8 m/s, while decreases with the enlargement of valve plate opening under the blast furnace gas flow speeds of 12 m/s and 16 m/s. In the case of the valve plate opening angle of 15°, the deposition rate of dust particles increases with the growing of blast furnace gas flow speed, while decreases with the growing of blast furnace gas flow speed under the cases of valve plate opening angle of 45° and 75°. The research results provide a theoretical reference for the development of automatic dust removal system in the butterfly valve region of the blast furnace gas pipeline.

  11. Radiation-transport method to simulate noncontinuum gas flows for MEMS devices.

    Energy Technology Data Exchange (ETDEWEB)

    Gallis, Michail A.; Torczynski, John Robert

    2004-01-01

    A Micro Electro Mechanical System (MEMS) typically consists of micron-scale parts that move through a gas at atmospheric or reduced pressure. In this situation, the gas-molecule mean free path is comparable to the geometric features of the microsystem, so the gas flow is noncontinuum. When mean-free-path effects cannot be neglected, the Boltzmann equation must be used to describe the gas flow. Solution of the Boltzmann equation is difficult even for the simplest case because of its sevenfold dimensionality (one temporal dimension, three spatial dimensions, and three velocity dimensions) and because of the integral nature of the collision term. The Direct Simulation Monte Carlo (DSMC) method is the method of choice to simulate high-speed noncontinuum flows. However, since DSMC uses computational molecules to represent the gas, the inherent statistical noise must be minimized by sampling large numbers of molecules. Since typical microsystem velocities are low (< 1 m/s) compared to molecular velocities ({approx}400 m/s), the number of molecular samples required to achieve 1% precision can exceed 1010 per cell. The Discrete Velocity Gas (DVG) method, an approach motivated by radiation transport, provides another way to simulate noncontinuum gas flows. Unlike DSMC, the DVG method restricts molecular velocities to have only certain discrete values. The transport of the number density of a velocity state is governed by a discrete Boltzmann equation that has one temporal dimension and three spatial dimensions and a polynomial collision term. Specification and implementation of DVG models are discussed, and DVG models are applied to Couette flow and to Fourier flow. While the DVG results for these benchmark problems are qualitatively correct, the errors in the shear stress and the heat flux can be order-unity even for DVG models with 88 velocity states. It is concluded that the DVG method, as described herein, is not sufficiently accurate to simulate the low-speed gas flows

  12. Approximate Solution for Choked Flow in Gas Seal Pads

    Science.gov (United States)

    Fleming, David P.

    2004-01-01

    Previous analyses of high pressure seals have considered adiabatic flow with friction but neglected effects of seal rotation. Most of this work analyzed a one-dimensional flow field. This works well to calculate stiffness and leakage of full circular seals, either face seals or annular ring seals. However, it cannot provide accurate results for a rectangular seal pad with its strongly two-dimensional flow field and its reliance on hydrodynamic forces to maintain a full fluid film. On the other hand, solutions of Reynolds lubrication equation have been obtained for the two-dimensional flow in a seal pad. But these solutions do not account for choking which occurs at high seal pressure ratios, nor do they consider the pressure loss that occurs in the entrance region of the flow field. The aim of the present work is to build on the Reynolds equation solution by use of an approximate choked flow analysis. This will account for the pressure losses in the flow entrance region, ensure that fluid velocities remain subsonic, and enable fluid inertial effects within the pad film to be accounted for. Results show that, in general, fluid inertia acts to decrease pad film load capacity and leakage, and increase film stiffness.

  13. Gas-liquid two-phase flow through packed bed reactors in microgravity

    Science.gov (United States)

    Motil, Brian Joseph

    Experimental results on flow pattern transitions, pressure drop and flow characteristics for cocurrent gas-liquid flow through packed bed reactors in microgravity is presented and analyzed. The pulse flow regime is shown to exist over a much wider range of gas and liquid flow rates when under microgravity conditions. A new model is developed to predict the transition from bubble flow to pulse flow based on the dimensionless Suratman number. The Suratman number is shown to represent the balance of forces at the pore level which determine the conditions necessary for the onset of pulse flow in the column. This model is then extended to normal gravity flows in the downward direction for fixed Bond numbers. A model to predict pressure drop in the absence of gravity is also presented. An additional pressure drop term is developed to extend the applicability of the Ergun equation to gas-liquid flow. This term represents the losses resulting from the dynamic interaction between the two phases and is superposed with the liquid viscous and inertia terms to represent the total pressure loss through a reactor bed in a microgravity environment. The modified two-phase Ergun equation is shown to provide good agreement with the experimental results.

  14. 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

  15. Multi parameter flow meter for on-line measurement of gas mixture composition

    NARCIS (Netherlands)

    van der Wouden, E.J.; Groenesteijn, Jarno; Wiegerink, Remco J.; Lötters, Joost Conrad

    2015-01-01

    In this paper we describe the development of a system and model to analyze the composition of gas mixtures up to four components. The system consists of a Coriolis mass flow sensor, density, pressure and thermal flow sensor. With this system it is possible to measure the viscosity, density, heat

  16. 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.

  17. 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

  18. 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.

  19. Hybrid simulations of rarefied supersonic gas flows in micro-nozzles

    NARCIS (Netherlands)

    Torre, F. la; Kenjereš, S.; Moerel, J.L.P.A.; Kleijn, C.R.

    2011-01-01

    We show that accurate predictions of gas flow and pressure in axisymmetric micro-thruster nozzles with throat diameters in the µm range, and thrusts in the µN range, cannot be performed using continuum based Computational Fluid Dynamics with slip flow boundary conditions, but can be performed by

  20. Algebraic model for bubble tracking in horizontal gas-liquid flow

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, Felipe G.C. de; Tisserant, Hendy R. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Morales, Rigoberto E.M. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica e de Materiais; Mazza, Ricardo A.; Rosa, Eugenio S. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Fac. de Engenharia Mecanica

    2008-07-01

    The current work extends the concept of unit-cell applied in gas-liquid slug flow models to predict the evolution of the gas and liquid flow properties along a horizontal pipe. The motivation of this model is its simplicity, easiness of application and low computational cost. It is a useful tool of reference data generation in order to check the consistency of numerical slug tracking models. The potential of the model is accessed by comparing the gas bubbles and liquid slug sizes, the translational bubble velocity and the pressure drop against experimental data. (author)

  1. 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.

  2. 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.

  3. 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.

  4. Studies of gas flow in grate fired boilers. Studier av gasstroemning i rosteldade pannor

    Energy Technology Data Exchange (ETDEWEB)

    Eriksson, Jan (Vattenfall Utveckling AB, Aelvkarleby (Sweden)); Tryman, R. (FOA, Tumba (SE))

    1991-01-22

    As a first step towards understanding the gas flow in a grate fired boiler, the isothermal flow in a water model has been studied. Laser-Doppler velocimetry of mean velocities and turbulence was performed in two coordinate directions at about 230 points. The FLUENT program was used for numerical calculations of the flow in the model, and an acceptable agreement with the measurements was achieved. (L.E.).

  5. Flow and heat transfer investigations in swirl tubes for gas turbine blade cooling

    OpenAIRE

    Biegger, Christoph

    2017-01-01

    A swirl tube is a very effective cooling technique for high thermal loaded components like gas turbine blades. Such a tube consists of one or more tangential inlet jets, which induce a highly 3D swirling flow. This swirling flow is characterized by large velocities near the wall and an enhanced turbulence in the tube which both increase the convective heat transfer. In the present work, the flow phenomena and the heat transfer in swirl tubes are studied experimentally and numerically. Therefo...

  6. Reacting Multi-Species Gas Capability for USM3D Flow Solver

    Science.gov (United States)

    Frink, Neal T.; Schuster, David M.

    2012-01-01

    The USM3D Navier-Stokes flow solver contributed heavily to the NASA Constellation Project (CxP) as a highly productive computational tool for generating the aerodynamic databases for the Ares I and V launch vehicles and Orion launch abort vehicle (LAV). USM3D is currently limited to ideal-gas flows, which are not adequate for modeling the chemistry or temperature effects of hot-gas jet flows. This task was initiated to create an efficient implementation of multi-species gas and equilibrium chemistry into the USM3D code to improve its predictive capabilities for hot jet impingement effects. The goal of this NASA Engineering and Safety Center (NESC) assessment was to implement and validate a simulation capability to handle real-gas effects in the USM3D code. This document contains the outcome of the NESC assessment.

  7. 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...

  8. 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

  9. Study on gas permeability coefficient measurement of coal seam by radial flow method

    Science.gov (United States)

    Zhang, Shuchuan

    2017-08-01

    For the accurate measurement of the coal seam permeability coefficient, the application range of the coal seam permeability coefficient was studied under various gas flow conditions with the guidance of the coal seam gas flow theory. Adopting the radial flow method, the measurement and calculation of the permeability coefficient of the coal seam C13-1 in Xinji No.1 Coal Mine shows that the permeability coefficient of the original coal seam C13-1 is less than 0.1, and the coal seam is difficult to extract.

  10. A Review of Experiments and Modeling of Gas-Liquid Flow in Electrical Submersible Pumps

    Directory of Open Access Journals (Sweden)

    Jianjun Zhu

    2018-01-01

    Full Text Available As the second most widely used artificial lift method in petroleum production (and first in produced amount, electrical submersible pump (ESP maintains or increases flow rate by converting kinetic energy to hydraulic pressure of hydrocarbon fluids. To facilitate its optimal working conditions, an ESP has to be operated within a narrow application window. Issues like gas involvement, changing production rate and high oil viscosity, greatly impede ESP boosting pressure. Previous experimental studies showed that the presence of gas would cause ESP hydraulic head degradation. The flow behaviors inside ESPs under gassy conditions, such as pressure surging and gas pockets, further deteriorate ESP pressure boosting ability. Therefore, it is important to know what parameters govern the gas-liquid flow structure inside a rotating ESP and how it can be modeled. This paper presents a comprehensive review on the key factors that affect ESP performance under gassy flow conditions. Furthermore, the empirical and mechanistic models for predicting ESP pressure increment are discussed. The computational fluid dynamics (CFD-based modeling approach for studying the multiphase flow in a rotating ESP is explained as well. The closure relationships that are critical to both mechanistic and numerical models are reviewed, which are helpful for further development of more accurate models for predicting ESP gas-liquid flow behaviors.

  11. Study of development of disturbance waves in annular gas-liquid flow

    Science.gov (United States)

    Cherdantsev, Andrey V.; Cherdantsev, Mikhail V.; Isaenkov, Sergey V.; Markovich, Dmitriy M.

    2017-09-01

    Downstream development of disturbance waves properties in annular regime of gas - liquid flow was conducted in adiabatic air-water downwards flow in a vertical pipe with inner diameter of 11.7 mm. The measurements were conducted using brightness-based laser-induced fluorescence technique. Instantaneous distributions of local thickness of liquid film along one longitudinal section of the duct over the first 45 cm from the inlet were obtained with sampling frequency of 10 kHz. Based on these spatiotemporal plots, dependence of local average velocity of disturbance waves on downstream distance was obtained for a wide range of gas and liquid flow rates. Three main stages of flow development were identified: a stage prior to formation of disturbance waves, a stage of constant acceleration of disturbance waves and a stage of deceleration nearly compensating the initial acceleration. Transitions to both second and third stages occur closer to the inlet at higher gas velocities and lower liquid flow rates. The initial acceleration is defined by the effect of the gas shear; it grows in parabolic manner with superficial gas velocity and shows weak dependence on liquid flow rate. The deceleration is supposed to occur due to entrainment of liquid from disturbance waves.

  12. Model investigations 3D of gas-powder two phase flow in descending bed with consideration radial distribution of flow

    Directory of Open Access Journals (Sweden)

    B. Panic

    2013-04-01

    Full Text Available The results of experimental investigations concerning radial distribution of powder accumulation in bed and static pressure were presented in this paper. To realize this research physical model of gas-powder two phase flow with descending bed was projected and constructed. Amounts of “dynamic” and “static” powder accumulated in bed, in dependence on gas velocity and of bed particles were investigated. In 3D model “static” powder (with its radial distribution at the tuyere level and in the higher part of bed was measured. The influence of bed particles, powder and gas radial distribution on values of interaction forces between flow phases in investigated system was defined.

  13. DEVELOPMENT OF A LOW-COST INFERENTIAL NATURAL GAS ENERGY FLOW RATE PROTOTYPE RETROFIT MODULE

    Energy Technology Data Exchange (ETDEWEB)

    E. Kelner; T.E. Owen; D.L. George; A. Minachi; M.G. Nored; C.J. Schwartz

    2004-03-01

    In 1998, Southwest Research Institute{reg_sign} began a multi-year project co-funded by the Gas Research Institute (GRI) and the U.S. Department of Energy. The project goal is to develop a working prototype instrument module for natural gas energy measurement. The module will be used to retrofit a natural gas custody transfer flow meter for energy measurement, at a cost an order of magnitude lower than a gas chromatograph. Development and evaluation of the prototype retrofit natural gas energy flow meter in 2000-2001 included: (1) evaluation of the inferential gas energy analysis algorithm using supplemental gas databases and anticipated worst-case gas mixtures; (2) identification and feasibility review of potential sensing technologies for nitrogen diluent content; (3) experimental performance evaluation of infrared absorption sensors for carbon dioxide diluent content; and (4) procurement of a custom ultrasonic transducer and redesign of the ultrasonic pulse reflection correlation sensor for precision speed-of-sound measurements. A prototype energy meter module containing improved carbon dioxide and speed-of-sound sensors was constructed and tested in the GRI Metering Research Facility at SwRI. Performance of this module using transmission-quality natural gas and gas containing supplemental carbon dioxide up to 9 mol% resulted in gas energy determinations well within the inferential algorithm worst-case tolerance of {+-}2.4 Btu/scf (nitrogen diluent gas measured by gas chromatograph). A two-week field test was performed at a gas-fired power plant to evaluate the inferential algorithm and the data acquisition requirements needed to adapt the prototype energy meter module to practical field site conditions.

  14. Performance comparison of supersonic ejectors with different motive gas injection schemes applicable for flowing medium gas laser

    Science.gov (United States)

    Singhal, G.; Subbarao, P. M. V.; Mainuddin; Tyagi, R. K.; Dawar, A. L.

    2017-05-01

    A class of flowing medium gas lasers with low generator pressures employ supersonic flows with low cavity pressure and are primarily categorized as high throughput systems capable of being scaled up to MW class. These include; Chemical Oxygen Iodine Laser (COIL) and Hydrogen (Deuterium) Fluoride (HF/DF). The practicability of such laser systems for various applications is enhanced by exhausting the effluents directly to ambient atmosphere. Consequently, ejector based pressure recovery forms a potent configuration for open cycle operation. Conventionally these gas laser systems require at least two ejector stages with low pressure stage being more critical, since it directly entrains the laser media, and the ensuing perturbation of cavity flow, if any, may affect laser operation. Hence, the choice of plausible motive gas injection schemes viz., peripheral or central is a fluid dynamic issue of interest, and a parametric experimental performance comparison would be beneficial. Thus, the focus is to experimentally characterize the effect of variation in motive gas supply pressure, entrainment ratio, back pressure conditions, nozzle injection position operated together with a COIL device and discern the reasons for the behavior.

  15. 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)

  16. Physics and Chemistry of MW Discharge in Gas Flows

    Science.gov (United States)

    2004-07-21

    main discharge area body ( Hallo ). One of the possible ways for measuring of electron temperature and concentration in these very thin and spatially...cold bulk hallo , whereas the first negative – from the hot breakdown filament. Gas temperature in channel filament turned out to be about 3000K

  17. 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 ...

  18. 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.

  19. Visualization and research of gas-liquid two phase flow structures in cylindrical channel

    Directory of Open Access Journals (Sweden)

    Stefański Sebastian

    2017-01-01

    Full Text Available Two-phase flows are commonly found in many industries, especially in systems, where efficient and correct functioning depend on specific values of flow parameters. In thermal engineering and chemical technology the most popular types of two-phase mixture are gas-liquid or liquid-vapour mixtures. Bubbles can create in flow different structures and determine diverse properties of flow (velocity of phase, void fraction, fluctuations of pressure, pipe vibrations, etc.. That type of flow is difficult to observe, especially in liquid-vapour mixture, where vapour is being made by heating the medium. Production of vapour and nucleation process are very complicated issues, which are important part of two-phase flow phenomenon. Gas-liquid flow structures were observed and described with figures, but type of structure depends on many parameters. Authors of this paper made an attempt to simulate gas-liquid flow with air and water. In the paper there was presented specific test stand built to observe two-phase flow structures, methodology of experiment and conditions which were maintained during observation. The paper presents also the structures which were observed and the analysis of results with reference to theoretical models and diagrams available in literature.

  20. Analysing Gas-Liquid Flow in PEM Electrolyser Micro-Channels (Poster)

    DEFF Research Database (Denmark)

    Lafmejani, Saeed Sadeghi; Olesen, Anders Christian; Kær, Søren Knudsen

    -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......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...

  1. Operator Splitting Method for Simulation of Dynamic Flows in Natural Gas Pipeline Networks

    CERN Document Server

    Dyachenko, Sergey A; Chertkov, Michael

    2016-01-01

    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.

  2. 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.

  3. A CFD study of gas-solid jet in a CFB riser flow

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tingwen; Guenther, Chris

    2012-03-01

    Three-dimensional high-resolution numerical simulations of a gas–solid jet in a high-density riser flow were conducted. The impact of gas–solid injection on the riser flow hydrodynamics was investigated with respect to voidage, tracer mass fractions, and solids velocity distribution. The behaviors of a gas–solid jet in the riser crossflow were studied through the unsteady numerical simulations. Substantial separation of the jetting gas and solids in the riser crossflow was observed. Mixing of the injected gas and solids with the riser flow was investigated and backmixing of gas and solids was evaluated. In the current numerical study, both the overall hydrodynamics of riser flow and the characteristics of gas–solid jet were reasonably predicted compared with the experimental measurements made at NETL.

  4. 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.

  5. Selected problems of gas-liquid flow through the channels filled with metal foams

    Directory of Open Access Journals (Sweden)

    Dyga Roman

    2017-01-01

    Full Text Available Open-cell metal foams are relatively unknown type of cellular material, which is increasingly being used as structural packing in the industrial equipment. The paper presents an analysis of experimental results on heat transfer and hydrodynamics of gas-liquid two-phase flow through the channels filled with metal foams. The research included the registration of temperature and pressure changes on fluid flow path. Furthermore the phase void fraction was measured and flow patterns in present in the channel were observed. It was found that in two-phase flow, both from heat transfer and hydrodynamics of flow point of view, the liquid plays the dominant role. It was also found a significant influence of flow patterns on frictional pressure loss value and phase void fraction. Whereas the flow patterns and geometry of the foam in much lesser extent influence on the intensity of heat transfer. Type of gas-liquid flow patterns primarily depends on flow conditions, including the velocity and properties of fluids. On the other hand, it wasn’t stated any significant effect of geometrical parameters of foam on the type of flow and the value of phase void fraction. Among many flow patterns observed during the study, there have been identified four basic structures: plug, semi-slug, slug, and stratified.

  6. Rarefied gas flows through meshes and implications for atmospheric measurements

    Directory of Open Access Journals (Sweden)

    J. Gumbel

    Full Text Available Meshes are commonly used as part of instruments for in situ atmospheric measurements. This study analyses the aerodynamic effect of meshes by means of wind tunnel experiments and numerical simulations. Based on the Direct Simulation Monte Carlo method, a simple mesh parameterisation is described and applied to a number of representative flow conditions. For open meshes freely exposed to the flow, substantial compression effects are found both upstream and downstream of the mesh. Meshes attached to close instrument structures, on the other hand, cause only minor flow disturbances. In an accompanying paper, the approach developed here is applied to the quantitative analysis of rocket-borne density measurements in the middle atmosphere.

    Key words. Atmospheric composition and structure (instruments and techniques; middle atmosphere – composition and chemistry

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

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yun Goo [Central Research Institute, Korea Hydro and Nuclear Power Co., LTD, Daejeon (Korea, Republic of); Seong, Poong Hyun [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2012-12-15

    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.

  8. 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

  9. Gas segregation and two-phase flow in basaltic explosive activity

    Science.gov (United States)

    Pioli, L.; Cashman, K.; Wallace, P.

    2007-05-01

    Basaltic explosive activity is highly variable in intensity, ranging from less energetic fire fountaining and intermittent strombolian explosions, to more energetic ash-forming violent strombolian, subplinian and plinian activity. Moreover, unlike silicic volcanism, there is no direct relationship between explosivity and magma flux, due to the complex interplay between gas segregation and initial gas content of the magma, ascent rate, and gas segregation. Highly explosive activity is particularly common in mafic arc volcanoes, where magmas contain abundant water and higher gas fluxes are expected. Gas segregation and two-phase flow processes play a fundamental role in the explosive dynamics of basaltic magma. Passive degassing and bubble bursts are common in lava lakes or lava-filled vents, that is, in nearly static lava ponds. This style of activity indicates the rise of discrete bubbles through the low viscosity liquid. With an increase in the magma supply rate and initial water content, activity changes to that of contemporaneous lava emission and explosive activity, as is typical in many cinder cone eruptions. This paired activity illustrates preferential segregation of gas into the vertical conduit with respect to a lateral dyke system; the result is eruptive activity that is referred to as either transitional or violent strombolian. When magma rise rate exceeds values of the order of 104-5 kg/s, gas segregation is no longer possible and eruptive activity takes the form of sustained columns (subplinian to plinian activity). This summary illustrates the role of liquid and gas fluxes on the development of two-phase flow patterns in the conduit, which, in turn affects the eruption dynamics. For example, discrete explosions are generated when the pattern is periodic (characterized by regular temporal and spatial fluctuations), due to formation of gas slugs or void fraction waves, whereas strong fluctuations in the eruptive dynamics may be related to flow

  10. Melt flow characteristics in gas-assisted laser cutting

    Indian Academy of Sciences (India)

    We present a study on laser cutting of mild steel with oxygen as an assist gas. We correlate the cut surface quality with the melt film thickness. We estimate the optimum pressure required for melt ejection under laminar flow regime. The thickness of melt film inside the kerf is estimated using mass balance and the shear force ...

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    was validated for high resolution measurements at temperatures of up to 800 K (527 degrees C) in the ultraviolet (UV) and infrared (IR) regions (190-20 000 nm). Verification of the gas temperature in the cell is provided by a thermocouple and emission/transmission measurements in the IR and UV regions. High......-resolution measurements are presented for the absorption cross-section of sulfur dioxide (SO2) in the UV range up to 773 K (500 degrees C)...

  12. 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.

  13. Analytical modeling of coupled flow and geomechanics for vertical fractured well in tight gas reservoirs

    Directory of Open Access Journals (Sweden)

    Wang Ruifei

    2017-12-01

    Full Text Available The mathematical model of coupled flow and geomechanics for a vertical fractured well in tight gas reservoirs was established. The analytical modeling of unidirectional flow and radial flow was achieved by Laplace transforms and integral transforms. The results show that uncoupled flow would lead to an overestimate in performance of a vertical fractured well, especially in the later stage. The production rate decreases with elastic modulus because porosity and permeability decrease accordingly. Drawdown pressure should be optimized to lower the impact of coupled flow and geomechanics as a result of permeability decreasing. Production rate increases with fracture half-length significantly in the initial stage and becomes stable gradually. This study could provide a theoretical basis for effective development of tight gas reservoirs.

  14. Research on Gas-liquid Flow Rate Optimization in Foam Drilling

    Science.gov (United States)

    Gao, B. K.; Sun, D. G.; Jia, Z. G.; Huang, Z. Q.

    2010-03-01

    With the advantages of less gas consumption, higher carrying rocks ability, lower leakage and higher penetration rate, foam drilling is widely used today in petroleum industry. In the process of foam underbalanced drilling, the mixture of gas, liquid and cuttings flows upwards through the annular, so it is a typical gas-liquid-solid multi-phase flow. In order to protect the reservoir and avoid borehole wall collapsing during foam drilling, it is crucial to ensure that the bottom hole pressure is lower than the formation pressure and higher than the formation collapse pressure, and in the mean time, foam drilling fluid in the whole wellbore should be in the best foam quality stage in order to have sufficient capacity to carry cuttings. In this paper, main relations between bottom hole pressure and gas-liquid injecting rate are analyzed with the underbalanced multiphase flow models. And in order to obtain precise flow pattern and flow pressure, the whole well bore is spatial meshed and iterative method is used. So, a convenient safety window expressed by gas-liquid injecting rate is obtained instead of that by bottom hole pressure. Finally, a foam drilling example from a block in Yemen is presented; the drilling results show that this method is reliable and practical.

  15. 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.

  16. 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

  17. Influence of geotechnical factors on gas flow experienced in a UK longwall coal mine panel

    Energy Technology Data Exchange (ETDEWEB)

    Whittles, D.N.; Lowndes, I.S.; Kingman, S.W.; Yates, C.; Jobling, S. [University of Nottingham, Nottingham (United Kingdom). Nottingham Mining & Minerals Centre

    2006-04-15

    Methane drainage has become an integral part of modern coal mining operations when gas emissions cannot be practically dealt with using conventional ventilation methods alone. Boreholes are often drilled above and below the caving zone and connected to a drainage range located along the return gate. This paper describes the construction and analysis of the results obtained from the two- and three-dimensional geomechanical and gas flow models experienced around an active deep UK longwall coal production panel. The models constructed using the commercial FLAC codes were undertaken to provide information to the ventilation engineers at the mine on the likely gas sources and gas flow paths into the face line areas and gate roads. This information allows for the correct design of the orientation, length and support of the boreholes to maximise gas capture. The paper describes the method adopted to derive the relevant rock mass parameters and the laboratory tests conducted to obtain the stress-dependent permeability of coal measure rock strata. A functional relationship is proposed whereby the intrinsic bulk permeability of a sheared coal measure rock may be predicted from the confining stress. A detailed discussion of the geomechanical modelling methodology and the derivation of the strata permeabilities and gas flow modelling adopted is presented. The output of the models is described and used to interpret the major potential gas sources and pathway into the workings.

  18. Techniques in Gas-Phase Thermolyses. Part 6. Pulse Pyrolysis: Gas Kinetic Studies in an Inductively Heated Flow Reactor

    DEFF Research Database (Denmark)

    Egsgaard, Helge; Bo, P.; Carlsen, Lars

    1985-01-01

    A prototype of an inductively heated flow reactor for gas kinetic studies is presented. The applicability of the system, which is based on a direct coupling between the reactor and the ion source of a mass spectrometer, is illustrated by investigations of a series of simple bond fission reactions....... The method permits the direct determination of low-pressure rate constants, the transformation to high-pressure values, and correspondingly evaluation of activation parameters, being derived by means of an empirical effective temperature approach.......A prototype of an inductively heated flow reactor for gas kinetic studies is presented. The applicability of the system, which is based on a direct coupling between the reactor and the ion source of a mass spectrometer, is illustrated by investigations of a series of simple bond fission reactions...

  19. 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.

  20. Plane Poiseuille flow of a rarefied gas in the presence of strong gravitation.

    Science.gov (United States)

    Doi, Toshiyuki

    2011-02-01

    Plane Poiseuille flow of a rarefied gas, which flows horizontally in the presence of strong gravitation, is studied based on the Boltzmann equation. Applying the asymptotic analysis for a small variation in the flow direction [Y. Sone, Molecular Gas Dynamics (Birkhäuser, 2007)], the two-dimensional problem is reduced to a one-dimensional problem, as in the case of a Poiseuille flow in the absence of gravitation, and the solution is obtained in a semianalytical form. The reduced one-dimensional problem is solved numerically for a hard sphere molecular gas over a wide range of the gas-rarefaction degree and the gravitational strength. The presence of gravitation reduces the mass flow rate, and the effect of gravitation is significant for large Knudsen numbers. To verify the validity of the asymptotic solution, a two-dimensional problem of a flow through a long channel is directly solved numerically, and the validity of the asymptotic solution is confirmed. ©2011 American Physical Society

  1. Computational study of liquid-gas cross-flow within structured packing cells

    Science.gov (United States)

    Lavalle, Gianluca; Lucquiaud, Mathieu; Valluri, Prashant

    2016-11-01

    Absorption columns used in the carbon capture processes and filled with structured packings are crucial to foster the exchanges and the transfers between the absorber liquid and the flue gas. However, flow reversal can occur under special flow conditions, resulting in a dramatic drop of the technological performances. We investigate numerically the liquid-gas pattern within a cross-flow packing cell. The cell is a complex geometry with two connected channels, where the two phases flow co- or counter-currently. We show that an increase of both the gas speed and the liquid load leads to an increase of the pressure drop. Particular focus is also given to the analysis of flow repartition and flooding delay. We reveal that tilting the unit cell helps to delay the flooding and extends the operational capability. The pressure drop of the cross-flow unit cell is also compared to the Mellapak packing which is widely used in carbon capture applications. Finally, we support this study by performing numerical simulations on simpler geometries by means of a low-dimensional film-gas model, in order to investigate the two-phase dynamics and predict the flooding onset with a low computational cost. The authors gratefully acknowledge EPSRC Grant No. EP/M001482/1.

  2. 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.

  3. ENERGY COMPONENTS OF GAS-LIQUID FLOW IN AEROTANK

    Directory of Open Access Journals (Sweden)

    Frolova Anna Olegovna

    2013-09-01

    Full Text Available In the article the main processes of hydrodynamic regime of aeration tank are observed: the formation and ascent of air bubbles during aeration and motion of the water-sludge mixture. The formulas for determining the potential speed of an air bubble during aeration and energy of the water-sludge stream motion are presented. The investigation of interaction mechanism of purified waste water and air bubbles in the process of aeration in relation to the flow dynamics is poorly explored and challenging. Interaction of energetic components of the bubbles flow during aeration and uniform stream motion in the aerotank is the part of mass transfer and diffusion. The increase in total energy of the system by means of summing and raising potentials of the stream and bubbles speed can lead to increasing the purification effect, that means speeding up the diffusion processes.

  4. 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)

  5. 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.

  6. A flow cytometry-based screen of nuclear envelope transmembrane proteins identifies NET4/Tmem53 as involved in stress-dependent cell cycle withdrawal.

    Directory of Open Access Journals (Sweden)

    Nadia Korfali

    2011-04-01

    Full Text Available Disruption of cell cycle regulation is one mechanism proposed for how nuclear envelope protein mutation can cause disease. Thus far only a few nuclear envelope proteins have been tested/found to affect cell cycle progression: to identify others, 39 novel nuclear envelope transmembrane proteins were screened for their ability to alter flow cytometry cell cycle/DNA content profiles when exogenously expressed. Eight had notable effects with seven increasing and one decreasing the 4N:2N ratio. We subsequently focused on NET4/Tmem53 that lost its effects in p53(-/- cells and retinoblastoma protein-deficient cells. NET4/TMEM53 knockdown by siRNA altered flow cytometry cell cycle/DNA content profiles in a similar way as overexpression. NET4/TMEM53 knockdown did not affect total retinoblastoma protein levels, unlike nuclear envelope-associated proteins Lamin A and LAP2α. However, a decrease in phosphorylated retinoblastoma protein was observed along with a doubling of p53 levels and a 7-fold increase in p21. Consequently cells withdrew from the cell cycle, which was confirmed in MRC5 cells by a drop in the percentage of cells expressing Ki-67 antigen and an increase in the number of cells stained for ß-galactosidase. The ß-galactosidase upregulation suggests that cells become prematurely senescent. Finally, the changes in retinoblastoma protein, p53, and p21 resulting from loss of NET4/Tmem53 were dependent upon active p38 MAP kinase. The finding that roughly a fifth of nuclear envelope transmembrane proteins screened yielded alterations in flow cytometry cell cycle/DNA content profiles suggests a much greater influence of the nuclear envelope on the cell cycle than is widely held.

  7. A Gas-Kinetic Scheme for Turbulent Flow

    Science.gov (United States)

    2014-09-19

    derived from the Boltzmann equation, as shown in [ Cercignani , 1988, Xu, 1998], a gas-kinetic scheme is always consistent with a conventional one, within...function consistent with Eq. 4 is obtained by means of the Chapman-Enskog expansion [ Cercignani , 1988]: f = feq − τ̂Dfeq + 2τ̂D (τ̂Dfeq) + . . . . (5... Cercignani , 1988, Xu, 1998] that Eq. 5 truncated at the first order ignores thermal fluctuations and is con- sistent with Euler fluxes. Eq. 5 truncated at

  8. Method For Enhanced Gas Monitoring In High Density Flow Streams

    Science.gov (United States)

    Von Drasek, William A.; Mulderink, Kenneth A.; Marin, Ovidiu

    2005-09-13

    A method for conducting laser absorption measurements in high temperature process streams having high levels of particulate matter is disclosed. An impinger is positioned substantially parallel to a laser beam propagation path and at upstream position relative to the laser beam. Beam shielding pipes shield the beam from the surrounding environment. Measurement is conducted only in the gap between the two shielding pipes where the beam propagates through the process gas. The impinger facilitates reduced particle presence in the measurement beam, resulting in improved SNR (signal-to-noise) and improved sensitivity and dynamic range of the measurement.

  9. Two-phase Flow Characteristics in a Gas-Flow Channel of Polymer Electrolyte Membrane Fuel Cells

    Science.gov (United States)

    Cho, Sung Chan

    Fuel cells, converting chemical energy of fuels directly into electricity, have become an integral part of alternative energy and energy efficiency. They provide a power source of high energy-conversion efficiency and zero emission, meeting the critical demands of a rapidly growing society. The proton exchange membrane (PEM) fuel cells, also called polymer electrolyte fuel cells (PEFCs), are the major type of fuel cells for transportation, portable and small-scale stationary applications. They provide high-power capability, work quietly at low temperatures, produce only water byproduct and no emission, and can be compactly assembled, making them one of the leading candidates for the next generation of power sources. Water management is one of the key issues in PEM fuel cells: appropriate humidification is critical for the ionic conductivity of membrane while excessive water causes flooding and consequently reduces cell performance. For efficient liquid water removal from gas flow channels of PEM fuel cells, in-depth understanding on droplet dynamics and two-phase flow characteristics is required. In this dissertation, theoretical analysis, numerical simulation, and experimental testing with visualization are carried out to understand the two-phase flow characteristics in PEM fuel cell channels. Two aspects of two-phase phenomena will be targeted: one is the droplet dynamics at the GDL surface; the other is the two-phase flow phenomena in gas flow channels. In the former, forces over a droplet, droplet deformation, and detachment are studied. Analytical solutions of droplet deformation and droplet detachment velocity are obtained. Both experiments and numerical simulation are conducted to validate analytical results. The effects of contact angle, channel geometry, superficial air velocity, properties of gas phase fluids are examined and criteria for the detachment velocity are derived to relate the Reynolds number to the Weber number. In the latter, two-phase flow

  10. 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.

  11. Flow resistance reduction of coal water slurry through gas phase addition

    Directory of Open Access Journals (Sweden)

    Robak Jolanta

    2016-01-01

    Full Text Available One of the main advantages of coal water slurry fuel (CWS is a physical form that allows, among others, their transfer by pipelines over long distances. For this form of transport actions towards reducing the flow resistance of the transmitted medium are important. One of the treatments leading to reduction in the flow resistance of suspensions is to introduce gas into the stream of flowing slurry. The goal of that action is to either loosen the structure of densely packed grains or increase the velocity of the suspension. The paper presents the flow resistance of CWS in a horizontal pipeline and the effect of addition of the gas phase on the resistance level. The investigation was carried out with the use of a research stand enabling to measure the flow resistance of the multiphase/multicomponent systems. The measured diameter and length of sections were respectively: 0.03 and 2 m. The coal-water slurries (based on steam coals with concentration of dry coal in the range of 51 do 60% obtained by wet milling in a drum mill were used. During the tests, the following parameters were measured: slurry flow rate, air flow rate, temperature and pressure difference in inlet and outlet of the measured section. The volume flow rate of slurry fuel was in the range of 30 to 110 dm3/min while the volume flow rate of air was from 0.15 to 4 m3/h. Based on the obtained results, the slurry flow resistance as a function of the flow rate and share of introduced air was evaluated. The performed research allowed for assessment of flow resistance reduction condition and to determine the pipe flow curves for different temperatures. It was found that the effect of reducing the flow resistance of the coal slurry by introducing gas into the flow tube depended on the volumetric flow rate, and thus the linear velocity of the slurry. Under the experimental condition, this effect only occurred at low flow rates (30 - 50 dm3/min and low temperature of the suspension. The

  12. 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.

  13. 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

  14. 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 H2 and H5 emitted net GHGs -152.20kg CO2 eq. and -140.32kg CO2 eq., respectively, in comparison with 420.88kg CO2 eq. of scenario H1 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.

  15. Monte Carlo description of gas flow from laser-evaporated silver

    DEFF Research Database (Denmark)

    Ellegaard, Ole; SCHOU, J; Urbassek, H

    1999-01-01

    at times t much greater than tau(laser), and this demonstrates that at these later times, the collisions in the plume efficiently smear out the characteristics of the varying temperature at the surface during ablation. The physical properties of the gas flow are determined by the mean thermal energy...... surface temperature and evaporation rate at times t much greater than tau(laser), and this demonstrates that at these later times, the collisions in the plume efficiently smear out the characteristics of the varying temperature at the surface during ablation. The physical properties of the gas flow...... and evaporation rates. These realistic experimental input parameters are further combined with a direct simulation Monte Carlo (DSMC) description of collisions in the gas flow of ablated surface atoms. With this method, new data of plume development and collision processes in the beginning of the ablation process...

  16. 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.

  17. 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.

  18. 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.

  19. Analytical solution of gas bubble dynamics between two-phase flow

    Science.gov (United States)

    Mohammadein, S. A.; Shalaby, G. A.; Abu-Bakr, A. F.; Abu-Nab, A. K.

    The growth of a gas bubble between two-phase flow represents the current physical problem. The mathematical model is performed by mass, momentum and diffusion equations. The Problem is solved analytically by using the modified Plesset and Zwick method. The growth process is affected by shear stress, coefficient of consistency, surface tension and void fraction in order to derive the growth of a gas bubble between two-phase in non-Newtonian fluids. The growth of a gas bubble in non-Newtonian fluids flow performs lower values than that in case of Newtonian one. The initial time of bubble growth for the different values of superheating and flow index n in the thermal stage is obtained. Moreover, the effect of critical bubble radius Rcr is studied on the growth process. The results satisfy the growth model in Newtonian fluids given by Foster and Zuber (1954) [34] and Scriven theory (Scriven, 1959) [35] for limited values of physical parameters.

  20. 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

  1. 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

  2. Re-assessment of net energy production and greenhouse gas emissions avoidance after 40 years of photovoltaics development

    Science.gov (United States)

    Louwen, Atse; van Sark, Wilfried G. J. H. M.; Faaij, André P. C.; Schropp, Ruud E. I.

    2016-12-01

    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 present a review of 40 years of photovoltaics development, analysing the development of energy demand and greenhouse gas emissions associated with photovoltaics production. Here we show strong downward trends of environmental impact of photovoltaics production, following the experience curve law. For every doubling of installed photovoltaic capacity, energy use decreases by 13 and 12% and greenhouse gas footprints by 17 and 24%, for poly- and monocrystalline based photovoltaic systems, respectively. As a result, we show a break-even between the cumulative disadvantages and benefits of photovoltaics, for both energy use and greenhouse gas emissions, occurs between 1997 and 2018, depending on photovoltaic performance and model uncertainties.

  3. 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.

  4. Numerical Study of a Mixing Flow of Gas and Liquid in Hydrocyclone

    Science.gov (United States)

    Yilmaz, Abdurrahman

    Hyrocyclones are commonly used for the separation of minerals from the mixture of liquid and suspended solids such as in the mixture of water and sand. In the present study, the hydrocyclone consisted of two different inlets such as liquid inlet and gas inlet and one outlet for the mixture of liquid and gas, and its geometry includes two different scales of reactor dimensions. Introducing gas while the hydrocyclone was in operation brought a new understanding of the hydrocyclone study. The optimization of the hydrocyclone operation for different gas flow rates and different water pressures was conducted in order to learn the effect of such different parameters on the vortex generation inside the hydrocyclone. These different parameters were used as the boundary conditions for the present numerical simulation and have impacted on the magnitudes of pressure, fraction, velocity streamlines, tangential velocity and axial velocity field distributions. All the simulations given in the present study were calculated with Fluent of the ANSYS 17.2 package program. k-epsilon model was applied for all the calculations with the volume of fluid (VOF) algorithm with no-slip conditions. The numerical study resulted in the results in six different cases with the combination of two sets of boundary conditions of 3 cfm, 9 cfm, 12 cfm, 15 cfm with 1psi gas inlet flow rates; and 100 gpm and 20 gpm with 15 psi, 20 psi and 25 psi water inlet pressures. Changing the gas flow rates with a constant water pressure had a significant impact on the vortex generation inside the hydrocyclone. However, changing the water inlet pressures with a constant gas flow rate did not have any effect on the development of the swirl flow inside the hydrocyclone.

  5. Modelling gas-liquid flow and local mass transfer in stirred tanks

    OpenAIRE

    Moilanen, Pasi

    2009-01-01

    This doctorial thesis offers a guideline for modelling gas-liquid flow in stirred tanks with computational fluid dynamics (CFD). Particularly the effect of varying physical properties and industrial operating conditions is highlighted. The most important thing in modelling mass transfer in stirred vessels is the accurate prediction of local bubble size. Population balances for bubbles are needed for accurate description of the local mass transfer rate. There are many pitfalls in gas-liquid mo...

  6. Two methods for calculating regional cerebral blood flow from emission computed tomography of inert gas concentrations

    DEFF Research Database (Denmark)

    Kanno, I; Lassen, N A

    1979-01-01

    Two methods are described for calculation of regional cerebral blood flow from completed tomographic data of radioactive inert gas distribution in a slice of brain tissue. It is assumed that the tomographic picture gives the average inert gas concentration in each pixel over data collection perio...... are implemented using synthetic data of xenon-133 emission computed tomography and some of the difficulties likely to be encountered in practice are stressed....

  7. Low Density Real Gas Flows About Hypersonic Vehicles.

    Science.gov (United States)

    1991-11-01

    in the adjacent cell to the boundary cell, as: Vbc = Vdj -(3-29) Solid Wall (No-slip). Although the exact form of the solid wall (no-slip) boundary...Wall. In the nonequilibrium flow over a body, the solid surface may act as a catalyst for the recombination of atoms and ions: hence, the heat transfer...catalycity is represented in terms of species catalytic efficiencies, defined as the ratio of the number of species recombining at the wall to the

  8. Determination of gas & liquid two-phase flow regime transitions in wellbore annulus by virtual mass force coefficient when gas cut

    Science.gov (United States)

    Qu, Junbo; Yan, Tie; Sun, Xiaofeng; Chen, Ye; Pan, Yi

    2017-10-01

    With the development of drilling technology to deeper stratum, overflowing especially gas cut occurs frequently, and then flow regime in wellbore annulus is from the original drilling fluid single-phase flow into gas & liquid two-phase flow. By using averaged two-fluid model equations and the basic principle of fluid mechanics to establish the continuity equations and momentum conservation equations of gas phase & liquid phase respectively. Relationship between pressure and density of gas & liquid was introduced to obtain hyperbolic equation, and get the expression of the dimensionless eigenvalue of the equation by using the characteristic line method, and analyze wellbore flow regime to get the critical gas content under different virtual mass force coefficients. Results show that the range of equation eigenvalues is getting smaller and smaller with the increase of gas content. When gas content reaches the critical point, the dimensionless eigenvalue of equation has no real solution, and the wellbore flow regime changed from bubble flow to bomb flow. When virtual mass force coefficients are 0.50, 0.60, 0.70 and 0.80 respectively, the critical gas contents are 0.32, 0.34, 0.37 and 0.39 respectively. The higher the coefficient of virtual mass force, the higher gas content in wellbore corresponding to the critical point of transition flow regime, which is in good agreement with previous experimental results. Therefore, it is possible to determine whether there is a real solution of the dimensionless eigenvalue of equation by virtual mass force coefficient and wellbore gas content, from which we can obtain the critical condition of wellbore flow regime transformation. It can provide theoretical support for the accurate judgment of the annular flow regime.

  9. Simulation of Argon Gas Flow Effects in a Continuous Slab Caster

    Science.gov (United States)

    Thomas, B. G.; Huang, X.; Sussman, R. C.

    1994-08-01

    Three-dimensional finite-volume-based numerical models of fluid, heat, and mass transport have been developed and applied to help explain the complex inter-related phenomena of multiphase fluid flow, superheat dissipation, and grade intermixing during the continuous casting of steel slabs. Gas bubbles are simulated using a continuum model, which calculates the volume fraction and velocities of the gas, and its effect on the liquid flow. Turbulence has been incorporated using the standard K-ɛ turbulence model. Reasonable agreement has been achieved between predicted velocities and corresponding measurements and observations in full-scale water models, both with and without gas injection. The effects of argon gas bubble injection on flow-related phenomena are investigated with simulations of a typical steel slab caster. Argon bubbles alter the flow pattern in the upper recirculation zone, shifting the impingement point and recirculation zones upward. The effect increases with increasing gas fraction and decreasing bubble size. Argon injection also causes superheat to be removed higher in the caster, moves the hot spot upward, lowers the peak heat flux, and increases heat extraction from the wide face and meniscus regions. During a steel grade transition, argon injection slightly affects slab surface composition but has no effect on intermixing in the slab interior.

  10. Monte Carlo description of gas flow from laser-evaporated silver

    DEFF Research Database (Denmark)

    Ellegaard, O.; Schou, Jørgen; Urbassek, H.M.

    1999-01-01

    at times t much greater than tau(laser), and this demonstrates that at these later times, the collisions in the plume efficiently smear out the characteristics of the varying temperature at the surface during ablation. The physical properties of the gas flow are determined by the mean thermal energy...... and evaporation rates. These realistic experimental input parameters are further combined with a direct simulation Monte Carlo (DSMC) description of collisions in the gas flow of ablated surface atoms. With this method, new data of plume development and collision processes in the beginning of the ablation process...

  11. Raman imaging of millimeter-long carbon nanotubes grown by a gas flow method

    Science.gov (United States)

    Kihara, Katsuya; Ishitani, Akihiro; Koyama, Tomohiro; Fukasawa, Mamoru; Inaba, Takumi; Shimizu, Maki; Homma, Yoshikazu

    2017-02-01

    Growing long carbon nanotubes (CNTs) is an important prerequisite for practical applications of CNTs. Although gas-flow-guided chemical vapor deposition can be used to produce millimeter-long CNTs, little is known regarding the associated growth mechanism. In the present work, Raman imaging was employed to characterize individual CNTs grown by the gas flow method, and Raman images of a CNT over 1.6 mm long were obtained. Two radial breathing modes were observed and the associated Raman images exhibited exactly identical distributions, indicating that the long CNT most likely had a double-walled structure, in which the CNT diameter was uniform along the whole length.

  12. The effect of surface temperature on dynamics of water droplet in minichannel with gas flow

    Directory of Open Access Journals (Sweden)

    Isachenko Ekaterina

    2017-01-01

    Full Text Available The experiments have been carried out to study dynamics of liquid droplets, blown by the gas flow in a mini-channel. The mean velocity at which the droplet motion over the substrate starts was determined depending on the surface temperature at different droplet volumes. The shadow method was the main method of measurement. The advancing and receding contact angles were measured depending on the gas flow rate. The friction force was determined using the advancing and receding contact angles and droplet size. A motion of a droplet was also observed from the top. The local velocity and acceleration of droplet were calculated.

  13. Oscillating gas flow induces reptation of granular droplets

    Science.gov (United States)

    Pastenes, Javier C.; Géminard, Jean-Christophe; Melo, Francisco

    2013-07-01

    We report on the reptation of vertically vibrated droplets of fine particles lying on a solid incline. On the one hand, time-resolved measurements show that the gas pressure in the gap between the droplet bottom and the solid surface can be accounted for by a Darcy law. The cumulative effect of the viscous drag is responsible for the droplet formation. On the other hand, we show that the gap pressure is responsible for an effective horizontal acceleration whose cumulative effect is the upward reptation of the droplets. Using various geometries of the solid substrate, we manipulate the droplets and study the effects of the substrate geometry and of the experimental parameters on the droplet shape and dynamics. The experimental results are discussed in the light of theoretical arguments. This study demonstrates that, by the choice of a suitable geometry of the surface and characteristics of the vibration, one can develop tools for precise powder handling and control.

  14. Swirling midframe flow for gas turbine engine having advanced transitions

    Energy Technology Data Exchange (ETDEWEB)

    Montgomery, Matthew D.; Charron, Richard C.; Rodriguez, Jose L.; Kusters, Bernhard W.; Morrison, Jay A.; Beeck, Alexander R.

    2016-12-27

    A gas turbine engine can-annular combustion arrangement (10), including: an axial compressor (82) operable to rotate in a rotation direction (60); a diffuser (100, 110) configured to receive compressed air (16) from the axial compressor; a plenum (22) configured to receive the compressed air from the diffuser; a plurality of combustor cans (12) each having a combustor inlet (38) in fluid communication with the plenum, wherein each combustor can is tangentially oriented so that a respective combustor inlet is circumferentially offset from a respective combustor outlet in a direction opposite the rotation direction; and an airflow guiding arrangement (80) configured to impart circumferential motion to the compressed air in the plenum in the direction opposite the rotation direction.

  15. 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.

  16. 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.

  17. Flow of Gas and Water in Hydraulically Fractured Shale Gas Reservoirs, March 28-29, 2011

    Science.gov (United States)

    Underground fluid flow is primarily controlled by two physical factors: hydraulic conduits and pressure gradients. Both are required, or fluids will not move. In their natural state, shale formations are very impermeable.

  18. Performance of a two-phase gas/liquid flow model in vertical wells

    Energy Technology Data Exchange (ETDEWEB)

    Kabir, C.S.; Hasan, A.R. (Chevron Oil Field Research Co., La Habra, CA (USA))

    1990-07-01

    Application of a recently developed method for predicting two-phase gas/oil pressure-drop in vertical oil wells is presented. The new method, which is flow-pattern based, is capable of handling flow in both circular and annular channels. Five principal flow regimes, bubbly, dispersed bubbly, slug, churn and annular, are recognized while developing appropriate correlations for predicting void fraction and pressure-drop in each flow regime. Standard oilfield correlations are used for estimating PVT properties of oil and gas: Standing's correlation for solution gas-oil ratio; Katz's correlation for oil formation volume factor; Standing's, and Chew and Connally's correlations for dead and live oil viscosities, respectively; and Lee et al.'s correlation for gas viscosity. A finite-difference algorithm is developed to compute pressure gradient in a wellbore. Computations performed on 115 field tests, involving all the two-phase flow regimes, suggest that the new method performs better than the Aziz et al. correlation. Further comparison of the new method's performance with other standard methods, such as, Orkiszewski, Duns and Ros, Beggs and Brill, Hagedorn and Brown, and Chierci et al., reveals its consistency and improved performance. The test data bank used in this study is that previously used by other authors; thus, validation of the new method is demonstrated with an independent data set. 4 figs., 42 refs., 7 tabs.

  19. Cyclostrophic adjustment in swirling gas flows and the Ranque-Hilsch vortex tube effect

    Science.gov (United States)

    Kalashnik, M. V.; Visheratin, K. N.

    2008-04-01

    A theoretical analysis of cyclostrophic adjustment is presented; i.e., adjustment to balance between pressure gradient and centrifugal force in axisymmetric flow of an inviscid gas is examined. The solution to the problem is represented as the sum of a time-independent (balanced) and time-dependent (wave) components. It is shown that the wave component of the flow in an unbounded domain decays with time, and the corresponding solution reduces to the balanced component. In a bounded domain, the balanced flow component exists against the background of undamped acoustic waves. It is found that the balanced flow is thermally stratified at Mach numbers close to unity, with a substantial decrease in gas temperature (to between -50 and -100°C) in the axial region. This finding, combined with the results of special experiments, is used to explain the Ranque-Hilsch vortex tube effect.

  20. Investigation of Radio Frequency Discharges and Langmuir Probe Diagnostic Methods in a Fast Flowing Electronegative Background Gas

    National Research Council Canada - National Science Library

    Lockwood, Nathaniel P

    2007-01-01

    ... (Pinhero and others, 1998). The effect of a flowing background gas on the charged and excited neutral species generation by an RF discharge in a flow tube and the diagnostics of the resulting plasma with a Langmuir probe...

  1. Two dimensional stagnation point flow of a dusty gas near an oscillating plate

    Science.gov (United States)

    Fernandez De La Mora, J.

    1982-01-01

    Necessary improvements to a paper on the flow of a dusty gas by Datta and Mishra (1980) are presented. Particular attention is given to the importance of particle phase compressibility and the hyperbolic nature of the particle momentum conservation equation which prohibits downstream (wall) boundary conditions for the solid phase. Fundamental differences between particulate and ordinary flow boundary layers are discussed, and the correct conservation equations are written.

  2. A Fractal Model for the Maximum Droplet Diameter in Gas-Liquid Mist Flow

    Directory of Open Access Journals (Sweden)

    Xiao-Hua Tan

    2013-01-01

    Full Text Available Distribution characteristics of liquid droplet size are described using the fractal theory for liquid droplet size distribution in gas-liquid mist flow. Thereby, the fractal expression of the maximum droplet diameter is derived. The fractal model for maximum droplet diameter is obtained based on the internal relationship between maximum droplet diameter and the droplet fractal dimension, which is obtained by analyzing the balance between total droplet surface energy and total gas turbulent kinetic energy. Fractal model predictions of maximum droplet diameter agree with the experimental data. Maximum droplet diameter and droplet fractal dimension are both found to be related to the superficial velocity of gas and liquid. Maximum droplet diameter decreases with an increase in gas superficial velocity but increases with an increase in liquid superficial velocity. Droplet fractal dimension increases with an increase in gas superficial velocity but decreases with an increase in liquid superficial velocity. These are all consistent with the physical facts.

  3. 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.

  4. Numerical simulation of the passive gas mixture flow

    Directory of Open Access Journals (Sweden)

    Kyncl Martin

    2016-01-01

    Full Text Available The aim of this paper is the numerical solution of the equations describing the non-stationary compressible turbulent multicomponent flow in gravitational field. The mixture of perfect inert gases is assumed. We work with the RANS equations equipped with the k-omega and the EARSM turbulence models. For the simulation of the wall roughness we use the modification of the specific turbulent dissipation. The finite volume method is used, with thermodynamic constants being functions in time and space. In order to compute the fluxes through the boundary faces we use the modification of the Riemann solver, which is the original result. We present the computational results, computed with the own-developed code (C, FORTRAN, multiprocessor, unstructured meshes in general.

  5. Optimization of the gas flow in a GEM chamber and development of the GEM foil stretcher

    Directory of Open Access Journals (Sweden)

    Noto Francesco

    2014-01-01

    Full Text Available The gas electron multiplier technology has been proven to tolerate rat e larger than 50 MHz/cm2 without noticeable aging and to provide sub resolution on working chambers up to 45 cm x 45 cm. A new gas electron multiplier-based tracker is under development for the Hall A upgrade at Jefferson Lab. The chambers of the tracker have been designed in a modular way: each chamber consists of 3 adjacent gas electron multiplier modules, with an active area of 40 cm x 50 cm each. We optimized the gas flow inside the gas electron multiplier module volume, using the COMSOL physics simulator framework; the COMSOL-based analysis includes the design of the inlet and outlet pipes and the maximization of the uniformity of the gas flow. We have defined the procedures for the assembling of the gas electron multiplier modules and designed a mechanical system (TENDIGEM that will be used to stretch the GEM foils at the proper tension (few kg/cm; the TENDIGEM is based on the original design developed at LNF.

  6. 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.

  7. 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.

  8. Assessment of leakage at the implant-abutment connection using a new gas flow method.

    Science.gov (United States)

    Fauroux, Marie-Alix; Levallois, Bernard; Yachouh, Jacques; Torres, Jacques-Henri

    2012-01-01

    The aim of this study was to evaluate, with a new gas flow technique, leakage at the implant/abutment junction in systems with four different connections. Five Branemark System, five One Morse, five Intra-lock System, and five Ankylos Plus implants and abutments were used. A hole was drilled in the apex of each implant to allow gas to flow through the connection from negative to atmospheric pressure. The gas flow was calculated (slope of pressure decrease, in hPa.s-1). Each connection was tested after both manual and key tightening. Statistical analysis was performed on a generalized linear model with repeated measurements. The significance level was set at α=.05. A global significant difference was observed between the various systems (P=.0001). After manual tightening, gas leakage was (Ln[hPa.s-1], means±standard deviations): One Morse: 0.20 (±1.70); Branemark System: -4.56 (±2.61); Intra-lock: -4.31 (±4.17); Ankylos Plus; -7.59 (±0.76). After key tightening, mean values were: One Morse: -2.51 (±2.72); Branemark System: -7.23 (±1.01); Intra-lock: -7.76 (±0.50); Ankylos Plus; -7.73 (±0.62). This study confirms that gas flow is an appropriate method to assess connection leakage. Ankylos Plus connection leakage was very low when the assembly was tightened manually. Among conical connection systems, low (Ankylos Plus) and high (One Morse) leakage was observed. This gas flow study suggests, therefore, that connection design is not the most important parameter for implant/abutment connection leakage.

  9. Expanding the range for predicting critical flow rates of gas wells producing from normally pressured waterdrive reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Upchurch, E.R. (Thums Long Beach Co. (US))

    1989-08-01

    The critical flow rate of a gas well is the minimum flow rate required to prevent accumulation of liquids in the tubing. Theoretical models currently available for estimating critical flow rates are restricted to wells with water/gas ratios less than 150bbl/MMcf (0.84 X 10/sup -3/ m/sup 3//m/sup 3/). For wells producing at higher water/gas ratios from normally pressured waterdrive reservoirs, a method of estimating critical flow rates is derived through use of an empirical multiphase-flow correlation.

  10. Liter-scale production of uniform gas bubbles via parallelization of flow-focusing generators.

    Science.gov (United States)

    Jeong, Heon-Ho; Yadavali, Sagar; Issadore, David; Lee, Daeyeon

    2017-07-25

    Microscale gas bubbles have demonstrated enormous utility as versatile templates for the synthesis of functional materials in medicine, ultra-lightweight materials and acoustic metamaterials. In many of these applications, high uniformity of the size of the gas bubbles is critical to achieve the desired properties and functionality. While microfluidics have been used with success to create gas bubbles that have a uniformity not achievable using conventional methods, the inherently low volumetric flow rate of microfluidics has limited its use in most applications. Parallelization of liquid droplet generators, in which many droplet generators are incorporated onto a single chip, has shown great promise for the large scale production of monodisperse liquid emulsion droplets. However, the scale-up of monodisperse gas bubbles using such an approach has remained a challenge because of possible coupling between parallel bubbles generators and feedback effects from the downstream channels. In this report, we systematically investigate the effect of factors such as viscosity of the continuous phase, capillary number, and gas pressure as well as the channel uniformity on the size distribution of gas bubbles in a parallelized microfluidic device. We show that, by optimizing the flow conditions, a device with 400 parallel flow focusing generators on a footprint of 5 × 5 cm(2) can be used to generate gas bubbles with a coefficient of variation of less than 5% at a production rate of approximately 1 L h(-1). Our results suggest that the optimization of flow conditions using a device with a small number (e.g., 8) of parallel FFGs can facilitate large-scale bubble production.

  11. Fresh gas flow and carbon dioxide rebreathing in a low pressure semi-open anaesthesia system.

    Science.gov (United States)

    Tweed, W A; Amatya, R; Lekhak, B D

    1993-11-01

    We have constructed a simple system for field anaesthesia by using a Farman entrainer and a semi-open circuit to convert a draw-over apparatus to a continuous flow air/O2 system. Compressed O2 was the driving gas for the entrainer; fresh gas (FG) delivered to the semi-open circuit was a mixture of O2, entrained air and anaesthetic vapour. The purpose of this study was to examine FG flow rate and CO2 rebreathing during intermittent positive pressure ventilation (IPPV). A non-rebreathing inflation valve (Laerdal) placed at the end of the expiratory (efferent) limb of the circuit vented both expiratory gas and excess FG. Ambient air IPPV was applied through the Laerdal valve from a self-inflating bag or ventilator. Since this circuit is functionally similar to a T-piece, the gas from the efferent limb (340 ml, containing FG) entered the lungs first. If tidal volume was larger than 340 ml the balance was ambient air. Minute ventilation of the lungs with efferent limb gas was defined as Veff. Respiratory gas was sampled at the endotracheal tube and the CO2 tension was measured with a NIHON-KOHDEN CO2 analyzer. Thirty-seven adult patients having intra-abdominal or pelvic surgery under general tracheal anaesthesia were studied. Four FG flow rates (5.7, 8.0, 9.3, and 10.4 L.min-1), corresponding to driving gas pressures of 40, 60, 80, and 100 mmHg, were introduced in random order. Although inspired CO2 was detected at FG flow rates of 5.7-9.3 L.min-1, there were no differences in PETCO2 among the four groups.(ABSTRACT TRUNCATED AT 250 WORDS)

  12. Scientific Transactions No. 11 of the Institute of Mechanics, Moscow State University. [supersonic and hypersonic gas flow and the movement of gas with exothermic reactions

    Science.gov (United States)

    Gonor, A. L. (Editor)

    1982-01-01

    The results of flow around wings, the determination of the optimal form, and the interaction of the wake with the accompanying flow at supersonic and hypersonic speeds of the free-stream flow are given. Methods of numerical and analytical calculation of one dimensional unsteady and two dimensional steady motions of fuel-gas mixtures with exothermic reactions are also considered.

  13. 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

  14. A high precision gas flow cell for performing in situ neutron studies of local atomic structure in catalytic materials.

    Science.gov (United States)

    Olds, Daniel; Page, Katharine; Paecklar, Arnold; Peterson, Peter F; Liu, Jue; Rucker, Gerald; Ruiz-Rodriguez, Mariano; Olsen, Michael; Pawel, Michelle; Overbury, Steven H; Neilson, James R

    2017-03-01

    Gas-solid interfaces enable a multitude of industrial processes, including heterogeneous catalysis; however, there are few methods available for studying the structure of this interface under operating conditions. Here, we present a new sample environment for interrogating materials under gas-flow conditions using time-of-flight neutron scattering under both constant and pulse probe gas flow. Outlined are descriptions of the gas flow cell and a commissioning example using the adsorption of N2 by Ca-exchanged zeolite-X (Na78-2xCaxAl78Si144O384,x ≈ 38). We demonstrate sensitivities to lattice contraction and N2 adsorption sites in the structure, with both static gas loading and gas flow. A steady-state isotope transient kinetic analysis of N2 adsorption measured simultaneously with mass spectrometry is also demonstrated. In the experiment, the gas flow through a plugged-flow gas-solid contactor is switched between N215 and N214 isotopes at a temperature of 300 K and a constant pressure of 1 atm; the gas flow and mass spectrum are correlated with the structure factor determined from event-based neutron total scattering. Available flow conditions, sample considerations, and future applications are discussed.

  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. The effects of gas flow on granular currents.

    Science.gov (United States)

    Gilbertson, M A; Jessop, D E; Hogg, A J

    2008-06-28

    Currents of particles have been quite successfully modelled using techniques developed for fluid gravity currents. These models require the rheology of the currents to be specified, which is determined by the interaction between particles. For relatively small slow currents, this is determined primarily through friction, which can be controlled and reduced by fluidizing the particles, so that they may become much more mobile. Recent results cannot be predicted using many of the proposed models, and may be defined by the interaction between the particles and the fluid through which they are passing. However, in addition, particles that are only initially fluidized also form currents that are also mobile, but otherwise are different from continuously fluidized currents. The mobility of these currents appears not to be connected to the time taken for them to degas. This suggests that defining the continuous stresses on the particle current may not be sufficient to understand its motion and that a challenge for the future is to understand the structure of these flows and how this affects their motion.

  17. 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.

  18. A method for measuring the local gas pressure within a gas-flow stage in situ in the transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Colby, R. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA (United States); Alsem, D.H. [Hummingbird Scientific, Lacey, WA (United States); Liyu, A.; Kabius, B. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA (United States)

    2015-06-15

    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{sub 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.

  19. 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.

  20. 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.

  1. 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.

  2. Dynamic Gas Flow Effects on the ESD of Aerospace Vehicle Surfaces

    Science.gov (United States)

    Hogue, Michael D.; Cox, Rachel E.; Mulligan, Jaysen; Ahmed, Kareem; Wilson, Jennifer G.; Calle, Luz M.

    2017-01-01

    The purpose of this work is to develop a version of Paschen's Law that takes into account the flow of ambient gas past electrode surfaces. Paschen's Law does not consider the flow of gas past an aerospace vehicle, whose surfaces may be triboelectrically charged by dust or ice crystal impingement while traversing the atmosphere. The basic hypothesis of this work is that the number of electron-ion pairs created per unit distance between electrode surfaces is mitigated by the electron-ion pairs removed per unit distance by the flow of gas. The revised theoretical model must be a function of the mean velocity, v (sub xm), of the ambient gas and reduce to Paschen's law when the gas mean velocity, v (sub xm) equals 0. A new theoretical formulation of Paschen's Law, taking into account the Mach number and dynamic pressure, derived by the authors, will be discussed. This equation was evaluated by wind tunnel experimentation whose results were consistent with the model hypothesis.

  3. An Analysis of Cold Gas Flow-Field for UHV Class Interrupters

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ki Dong; Park, Kyong Yop [Korea Electrotechnology Research Institute (Korea); Song, Won Pyo [Hyosung Heavy Industrial (Korea)

    2000-06-01

    This paper presents a method of cold gas flow-field analysis within puffer type GCB(Gas Circuit Breaker). Using this method, the entire interruption process including opening operation of GCB can be simulated successfully. In particular, the distortion problem of the grid due to the movement of moving parts can be dealt with by the fixed grid technique. The gas parameters such as temperature, pressure, density, velocity through the entire interruption process can be calculated and visualized. It was confirmed that the time variation of pressure which was calculated from the application of the method to a model GCB agreed with the experimental one. Therefore it is possible to evaluate the small current interruption capability analytically and to design the interrupter which has excellent interruption capability using the proposed method. It is expected that the proposed method can reduce the time and cost for development of GCB very much. It also will be possible to develop the hot-gas flow-field analysis program by combining the cold-gas flow field program with the arc model and to evaluate the large current interruption capability. (author). 9 refs., 11 figs., 1 tab.

  4. Measurements of solids concentration and axial solids velocity in gas-solid two-phase flows.

    NARCIS (Netherlands)

    Nieuwland, J.J.; Nieuwland, J.J.; Meijer, R.; Kuipers, J.A.M.; van Swaaij, Willibrordus Petrus Maria

    1996-01-01

    Several techniques reported in the literature for measuring solids concentration and solids velocity in (dense) gas-solid two-phase flow have been briefly reviewed. An optical measuring system, based on detection of light reflected by the suspended particles, has been developed to measure local

  5. 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,

  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)

    van Eck, H. J. N.; Koppers, W. R.; van Rooij, G. J.; W. J. Goedheer,; Engeln, R.; D.C. Schram,; Cardozo, N. J. L.; 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. Effect of RF power and gas flow ratio on the growth and morphology ...

    Indian Academy of Sciences (India)

    Effect of RF power and gas flow ratio on the growth and morphology of the PECVD SiC thin films for MEMS applications. BHAVANA PERI, BIKASH BORAH and RAJ KISHORA DASH. ∗. School of Engineering Sciences and Technology, University of Hyderabad, Prof. C R Rao Road, Gachibowli,. Hyderabad 500046, India.

  9. 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

  10. Methylation of 2-Naphthol Using Dimethyl Carbonate under Continuous-Flow Gas-Phase Conditions

    Science.gov (United States)

    Tundo, Pietro; Rosamilia, Anthony E.; Arico, Fabio

    2010-01-01

    This experiment investigates the methylation of 2-naphthol with dimethyl carbonate. The volatility of the substrates, products, and co-products allows the reaction to be performed using a continuous-flow gas-phase setup at ambient pressure. The reaction uses catalytic quantities of base, achieves high conversion, produces little waste, and…

  11. Improved real gas routines for Sandia's NASA Ames flow field program

    Energy Technology Data Exchange (ETDEWEB)

    Eaton, R.R.; Larson, D.E.

    1976-02-01

    The real gas subroutines in Sandia's version of the NASA Ames flow field code have been extensively revised. Using these modifications the required computer run time for a difficult high Mach number case has been reduced from 1330 seconds to 151 seconds. (auth)

  12. Gas-pressurized dispersive powder flow tester for low volume sample characterization.

    Science.gov (United States)

    Majid, Ainnur Marlyana Abd; Wong, Tin Wui

    2013-05-01

    The conventional powder flow testers require sample volumes larger than 40g and are met with experimental hiccups due to powder cohesion. This study designed a gas-pressurized dispersive powder flow tester where a high velocity air is used to disaggregate powder (9g) and eliminate its cohesion. The pressurized gas entrained solid particles leaving an orifice where the distance, surface area, width and weight of particle dispersion thereafter are determined as flow index. The flow indices of seven lactose grades with varying size, size distribution, shape, morphology, bulk and tapped densities characteristics were examined. They were compared against Hausner ratio and Carr's index parameters of the same powder mass. Both distance and surface area attributes of particle dispersion had significant negative correlations with Hausner ratio and Carr's index values of lactose. The distance, surface area and ease of particle dispersion varied proportionately with circular equivalent, surface weighted mean and volume weighted mean diameters of lactose, and inversely related to their specific surface area and elongation characteristics. Unlike insensitive Hausner ratio and Carr's index, an increase in elongation property of lactose particles was detectable through reduced powder weight loss from gas-pressurized dispersion as a result of susceptible particle blockage at orifice. The gas-pressurized dispersive tester is a useful alternative flowability measurement device for low volume and cohesive powder. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. 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.

  14. Navier-Stokes-Fourier analytic solutions for non-isothermal Couette slip gas flow

    Directory of Open Access Journals (Sweden)

    Milićev Snežana S.

    2016-01-01

    Full Text Available The explicit and reliable analytical solutions for steady plane compressible non-isothermal Couette gas flow are presented. These solutions for velocity and temperature are developed by macroscopic approach from Navier-Stokes-Fourier system of continuum equations and the velocity slip and the temperature jump first order boundary conditions. Variability of the viscosity and thermal conductivity with temperature is involved in the model. The known result for the gas flow with constant and equal temperatures of the walls (isothermal walls is verified and a new solution for the case of different temperature of the walls is obtained. Evan though the solution for isothermal walls correspond to the gas flow of the Knudsen number Kn≤0.1, i.e. to the slip and continuum flow, it is shown that the gas velocity and related shear stress are also valid for the whole range of the Knudsen number. The deviation from numerical results for the same system is less than 1%. The reliability of the solution is confirmed by comparing with results of other authors which are obtained numerically by microscopic approach. The advantage of the presented solution compared to previous is in a very simple applicability along with high accuracy. [Projekat Ministarstva nauke Republike Srbije, br. 35046 i 174014

  15. 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

  16. Prediction of Ablation Rates from Solid Surfaces Exposed to High Temperature Gas Flow

    Science.gov (United States)

    Akyuzlu, Kazim M.; Coote, David

    2013-01-01

    A mathematical model and a solution algorithm is developed to study the physics of high temperature heat transfer and material ablation and identify the problems associated with the flow of hydrogen gas at very high temperatures and velocities through pipes and various components of Nuclear Thermal Rocket (NTR) motors. Ablation and melting can be experienced when the inner solid surface of the cooling channels and the diverging-converging nozzle of a Nuclear Thermal Rocket (NTR) motor is exposed to hydrogen gas flow at temperatures around 2500 degrees Kelvin and pressures around 3.4 MPa. In the experiments conducted on typical NTR motors developed in 1960s, degradation of the cooling channel material (cracking in the nuclear fuel element cladding) and in some instances melting of the core was observed. This paper presents the results of a preliminary study based on two types of physics based mathematical models that were developed to simulate the thermal-hydrodynamic conditions that lead to ablation of the solid surface of a stainless steel pipe exposed to high temperature hydrogen gas near sonic velocities. One of the proposed models is one-dimensional and assumes the gas flow to be unsteady, compressible and viscous. An in-house computer code was developed to solve the conservations equations of this model using a second-order accurate finite-difference technique. The second model assumes the flow to be three-dimensional, unsteady, compressible and viscous. A commercial CFD code (Fluent) was used to solve the later model equations. Both models assume the thermodynamic and transport properties of the hydrogen gas to be temperature dependent. In the solution algorithm developed for this study, the unsteady temperature of the pipe is determined from the heat equation for the solid. The solid-gas interface temperature is determined from an energy balance at the interface which includes heat transfer from or to the interface by conduction, convection, radiation, and

  17. 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.

  18. 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

  19. 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....... For practical reasons and space limitations the gas often enters through an inlet pipe making a 150-180° bend shortly before a short diffuser expanding to full tower diameter (Fig. 1). A swirl generator is placed immediately before the inlet to the diffuser to prevent recirculation near walls of the diffuser...... is carried out using LDA-measurements and flow visualization in a 1:16 scale laboratory model. In addition, the degree of mixing on injected water spray is simulated by visualization studies to find the optimal position of injection nozzles....

  20. Effect of delta wing on the particle flow in a novel gas supersonic separator

    DEFF Research Database (Denmark)

    Wen, Chuang; Yang, Yan; Walther, Jens Honore

    2016-01-01

    The present work presents numerical simulations of the complex particle motion in a supersonic separator with a delta wing located in the supersonic flow. The effect of the delta wing on the strong swirling flow is analysed using the Discrete Particle Method. The results show that the delta wings...... re-compress the upstream flow and the gas Mach number decreases correspondingly. However, the Mach number does not vary significantly from the small, medium and large delta wing configurations. The small delta wing generates a swirl near its surface, but has minor influences on the flow above it....... On the contrary, the use of the large delta wing produces a strong swirling flow in the whole downstream region. For the large delta wing, the collection efficiency reaches 70% with 2 μm particles, indicating a good separation performance of the proposed supersonic separator....

  1. Malignant human cell transformation of Marcellus Shale gas drilling flow back water.

    Science.gov (United States)

    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; Zelikoff, Judith

    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 LC50 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 6weeks 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. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. 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.

  3. 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.

  4. Numerical simulation of gas flow through unsaturated fractured rock at Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, C.A. [Nevada Univ., Las Vegas, NV (United States). Water Resources Center

    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{sub {minus}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{sup 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{sup {minus}1}), indicating that observed flow rates from wells along the east flank of Yucca Mountain were able to be simulated with a barometric model.

  5. A Study of Bubble and Slug Gas-Liquid Flow in a Microgravity Environment

    Science.gov (United States)

    McQuillen, J.

    2000-01-01

    The influence of gravity on the two-phase flow dynamics is obvious.As the gravity level is reduced,there is a new balance between inertial and interfacial forces, altering the behavior of the flow. In bubbly flow,the absence of drift velocity leads to spherical-shaped bubbles with a rectilinear trajectory.Slug flow is a succession of long bubbles and liquid slug carrying a few bubbles. There is no flow reversal in the thin liquid film as the long bubble and liquid slug pass over the film. Although the flow structure seems to be simpler than in normal gravity conditions,the models developed for the prediction of flow behavior in normal gravity and extended to reduced gravity flow are unable to predict the flow behavior correctly.An additional benefit of conducting studies in microgravity flows is that these studies aide the development of understanding for normal gravity flow behavior by removing the effects of buoyancy on the shape of the interface and density driven shear flows between the gas and the liquid phases. The proposal calls to study specifically the following: 1) The dynamics of isolated bubbles in microgravity liquid flows will be analyzed: Both the dynamics of spherical isolated bubbles and their dispersion by turbulence, their interaction with the pipe wall,the behavior of the bubbles in accelerated or decelerated flows,and the dynamics of isolated cylindrical bubbles, their deformation in accelerated/decelerated flows (in converging or diverging channels), and bubble/bubble interaction. Experiments will consist of the use of Particle Image Velocimetry (PIV) and Laser Doppler Velocimeters (LDV) to study single spherical bubble and single and two cylindrical bubble behavior with respect to their influence on the turbulence of the surrounding liquid and on the wall 2) The dynamics of bubbly and slug flow in microgravity will be analyzed especially for the role of the coalescence in the transition from bubbly to slug flow (effect of fluid properties and

  6. 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.

  7. Unified gas-kinetic scheme for diatomic molecular flow with translational, rotational, and vibrational modes

    Science.gov (United States)

    Wang, Zhao; Yan, Hong; Li, Qibing; Xu, Kun

    2017-12-01

    The unified gas-kinetic scheme (UGKS) is a direct modeling method for both continuum and rarefied flow computations. In the previous study, the UGKS was developed for diatomic molecular simulations with translation and rotational motions. In this paper, a UGKS with non-equilibrium translational, rotational, and vibrational degrees of freedom, will be developed. The new scheme is based on the phenomenological gas dynamics model, where the translational, rotational, and vibrational modes get to the equilibrium with different time scales with the introduction of rotational and vibrational collision numbers. This new scheme is tested in a few cases, such as the homogeneous flow relaxation, shock structure, shock tube problem, and flow passing through a circular and semi-circular cylinders. The analytical and DSMC solutions are used for the validation of the UGKS, and reasonable agreements have been achieved.

  8. Software Package \\Nesvetay-3D" for modeling three-dimensional flows of monatomic rarefied gas

    Directory of Open Access Journals (Sweden)

    V. A. Titarev

    2014-01-01

    Full Text Available Analysis of three-dimensional rarefied gas flowsin microdevices (micropipes, micropumps etc and over re-entry vehicles requires development of methods of computational modelling. One of such methods is the direct numerical solution of the Boltzmann kinetic equation for the velocity distribution function with either exact or approximate (model collision integral. At present, for flows of monatomic rarefied gas the Shakhov model kinetic equation, also called S-model, has gained wide-spread use. The equation can be regarded as a model equation of the incomplete thirdorder approximation. Despite its relative simplicity, the S-model is still a complicated integrodifferential equation of high dimension. The numerical solution of such an equation requires high-accuracy parallel methods.The present work is a review of recent results concerning the development and application of three-dimensional computer package Nesvetay-3D intended for modelling of rarefied gas flows. The package solves Boltzmann kinetic equation with the BGK (Krook and Shakhov model collision integrals using the discrete velocity approach. Calculations are carried out in non-dimensional variables. A finite integration domain and a mesh are introduced in the molecular velocity space. Next, the kinetic equation is re-written as a system of kinetic equations for each of the discrete velocities. The system is solved using an implicit finite-volume method of Godunov type. The steady-state solution is computed by a time marching method. High order of spatial accuracy is achieved by using a piece-wise linear representation of the distribution function in each spatial cell. In general, the coefficients of such an approximation are found using the least-square method. Arbitrary unstructured meshes in the physical space can be used in calculations, which allow considering flows over objects of general geometrical shape. Conservative property of the method with respect to the model collision

  9. Analysis of the Cold Gas Flow in Puffer Type Circuit Breaker

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hong Kyu; Jung, Hyun Kyo [Seoul National University (Korea); Shin, Seong Rok [Samsung SDI R and D Center (Korea); Kim, Doo Sung; Kweon, KI Yeoung [Hyosung Heavy Industry (Korea)

    2000-04-01

    There are many difficult problems in analyzing the gas flow in puffer type circuit breaker such as complex geometry, moving boundary, shock wave and so on. To predict the interruption performance accurately, these should be considered in the simulation. In this paper, the analysis procedure of the cold gas flow in the circuit breaker is presented. Euler equation is solved by FVFLIC method which is an explicit time difference scheme for an unsteady flow computation. Moving boundaries are treated with a cell elimination-addition technique. The pressure and density in front of piston are calculated from the rate of the cell volume change. The presented method is applied to the real circuit breaker model and the pressure in front of the piston is good agreement with the experimental one. (author). 8 refs., 13 figs., 1 tab.

  10. Nonlinear analysis of gas-water/oil-water two-phase flow in complex networks

    CERN Document Server

    Gao, Zhong-Ke; Wang, Wen-Xu

    2014-01-01

    Understanding the dynamics of multi-phase flows has been a challenge in the fields of nonlinear dynamics and fluid mechanics. This chapter reviews our work on two-phase flow dynamics in combination with complex network theory. We systematically carried out gas-water/oil-water two-phase flow experiments for measuring the time series of flow signals which is studied in terms of the mapping from time series to complex networks. Three network mapping methods were proposed for the analysis and identification of flow patterns, 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 based on K-means clustering, distinct flow patterns can be successfully distinguished and identified. A number of FDCN’s under different flow conditions were constructed in order to reveal the dynamical characteristics of two-phase flows. The FDCNs exhibit universal power-law degree distributions. The power-law exponent ...

  11. Experimental research of shock wave processes influence on machineless gas flow energy separation effect

    Science.gov (United States)

    Vinogradov, Y. A.; Zditovets, A. G.; Leontiev, A. I.; Popovich, S. S.; Strongin, M. M.

    2017-11-01

    Experimental results for artificially initiated shock wave influence on machineless gas flow energy separation effect are presented. The working principle of the technique is based on interaction of supersonic and subsonic flows through the heat-conducting wall. In result at output there are two flows with different temperature – heated supersonic air flow and cooled subsonic one. Shock waves were initiated by conic ribs placed along the supersonic channel. During the research varied parameters included uni-flow and counter-flow air moving direction in subsonic and supersonic channels, subsonic flow rate divided by supersonic one (from 0 to 0.9), stagnation flow temperature (298, 313 and 343K) and initial Mach number (1.9, 2.5). The research was carried out with the use of infrared thermal imaging, thermocouples, total and static pressure probes, National Instruments automation equipment. Energy separation effect is increasing with the growth of Mach number and stagnation flow temperature. Rib placement in supersonic channel causes rise of static pressure and wall temperature and results in decreasing of energy separation effect at output of the device by less than 12%. Operability of the device with shock wave generation is remained.

  12. Gas dynamics and mixture formation in swirled flows with precession of air flow

    Science.gov (United States)

    Tretyakov, V. V.; Sviridenkov, A. A.

    2017-10-01

    The effect of precessing air flow on the processes of mixture formation in the wake of the front winding devices of the combustion chambers is considered. Visual observations have shown that at different times the shape of the atomized jet is highly variable and has signs of precessing motion. The experimental data on the distribution of the velocity and concentration fields of the droplet fuel in the working volume of the flame tube of a typical combustion chamber are obtained. The method of calculating flows consisted in integrating the complete system of Reynolds equations written in Euler variables and closed with the two-parameter model of turbulence k-ε. Calculation of the concentration fields of droplet and vapor fuel is based on the use of models for disintegration into droplets of fuel jets, fragmentation of droplets and analysis of motion and evaporation of individual droplets in the air flow. Comparison of the calculation results with experimental data showed their good agreement.

  13. The RealGas and RealGasH2O options of the TOUGH+ code for the simulation of coupled fluid and heat flow in tight/shale gas systems

    Science.gov (United States)

    We developed two new EOS additions to the TOUGH+ family of codes, the RealGasH2O and RealGas. The RealGasH2O EOS option describes the non-isothermal two-phase flow of water and a real gas mixture in gas reservoirs, with a particular focus in ultra-tight (such as tight-sand and sh...

  14. 微通道内气-液弹状流动及传质特性研究进展 (Review on flow and mass transfer characteristics of gas-liquid slug flow in microchannels)

    NARCIS (Netherlands)

    Yao, Chaoqun; Yue, Jun; Zhao, Yuchao; Chen, Guangwen; Yuan, Quan

    2015-01-01

    Gas-liquid slug flow (also termed as Taylor flow) is a flow pattern characterized by the alternate movement of elongated bubbles and liquid slugs. Gas-liquid slug flow operation in microchannels has been found important implications in the enhancement of gas-liquid reactions due to its advantages

  15. Numerical Analysis of Inlet Gas-Mixture Flow Rate Effects on Carbon Nanotube Growth Rate

    Directory of Open Access Journals (Sweden)

    B. Zahed

    2013-01-01

    Full Text Available The growth rate and uniformity of Carbon Nano Tubes (CNTs based on Chemical Vapor Deposition (CVD technique is investigated by using a numerical model. In this reactor, inlet gas mixture, including xylene as carbon source and mixture of argon and hydrogen as  carrier gas enters into a horizontal CVD reactor at atmospheric pressure. Based on the gas phase and surface reactions, released carbon atoms are grown as CNTs on the iron catalysts at the reactor hot walls. The effect of inlet gas-mixture flow rate, on CNTs growth rate and its uniformity is discussed. In addition the velocity and temperature profile and also species concentrations throughout the reactor are presented.

  16. A relative permeability model to derive fractional-flow functions of water-alternating-gas and surfactant-alternating-gas foam core-floods

    Science.gov (United States)

    Idrees Al-Mossawy, Mohammed; Demiral, Birol; Raja, D. M. Anwar

    2013-04-01

    Foam is used in enhanced oil recovery to improve the sweep efficiency by controlling the gas mobility. The surfactant-alternating-gas (SAG) foam process is used as an alternative to the water-alternating-gas (WAG) injection. In the WAG technique, the high mobility and the low density of the gas lead the gas to flow in channels through the high permeability zones of the reservoir and to rise to the top of the reservoir by gravity segregation. As a result, the sweep efficiency decreases and there will be more residual oil in the reservoir. The foam can trap the gas in liquid films and reduces the gas mobility. The fractional-flow method describes the physics of immiscible displacements in porous media. Finding the water fractional flow theoretically or experimentally as a function of the water saturation represents the heart of this method. The relative permeability function is the conventional way to derive the fractional-flow function. This study presents an improved relative permeability model to derive the fractional-flow functions for WAG and SAG foam core-floods. The SAG flow regimes are characterized into weak foam, strong foam without a shock front and strong foam with a shock front.

  17. A TECHNOLOGY ASSESSMENT AND FEASIBILITY EVALUATION OF NATURAL GAS ENERGY FLOW MEASUREMENT ALTERNATIVES

    Energy Technology Data Exchange (ETDEWEB)

    Kendricks A. Behring II; Eric Kelner; Ali Minachi; Cecil R. Sparks; Thomas B. Morrow; Steven J. Svedeman

    1999-01-01

    Deregulation and open access in the natural gas pipeline industry has changed the gas business environment towards greater reliance on local energy flow rate measurement. What was once a large, stable, and well-defined source of natural gas is now a composite from many small suppliers with greatly varying gas compositions. Unfortunately, the traditional approach to energy flow measurement [using a gas chromatograph (GC) for composition assay in conjunction with a flow meter] is only cost effective for large capacity supplies (typically greater than 1 to 30 million scfd). A less costly approach will encourage more widespread use of energy measurement technology. In turn, the US will benefit from tighter gas inventory control, more efficient pipeline and industrial plant operations, and ultimately lower costs to the consumer. An assessment of the state and direction of technology for natural gas energy flow rate measurement is presented. The alternative technologies were ranked according to their potential to dramatically reduce capital and operating and maintenance (O and M) costs, while improving reliability and accuracy. The top-ranked technologies take an unconventional inference approach to the energy measurement problem. Because of that approach, they will not satisfy the fundamental need for composition assay, but have great potential to reduce industry reliance on the GC. Technological feasibility of the inference approach was demonstrated through the successful development of data correlations that relate energy measurement properties (molecular weight, mass-based heating value, standard density, molar ideal gross heating value, standard volumetric heating value, density, and volume-based heating value) to three inferential properties: standard sound speed, carbon dioxide concentration, and nitrogen concentration (temperature and pressure are also required for the last two). The key advantage of this approach is that inexpensive on-line sensors may be used

  18. Weather and Management Effects over Nine Years of Net Ecosystem Direct Greenhouse Gas Emissions from a Cropping System in the Red River Valley, Manitoba

    Science.gov (United States)

    Tenuta, M.; Amiro, B. D.

    2014-12-01

    Variation in weather and crop management practices strongly determines direct greenhouse gas emissions (CO2 and N2O) from agricultural crop land. Thus a long-term study was established to relate weather and management variations to direct emissions in the Northern Great Plains of Canada. Continuously emission determinations of CO2 and N2O were established at the Trace Gas Manitoba (TGAS-MAN) Long Term Greenhouse Gas Monitoring Site at Glenlea, Manitoba, using the flux gradient micrometeorlogical technique with a tunable diode laser analyzer. The soil is poorly drained clay in the Red River Valley. The field experiment consisted of four 4-hectare plots planted to corn in 2006 and faba bean in 2007. In 2008, grass-alfalfa forage was introduced to two plots (annual - perennial) and grown until 2011 whereas the other two plots (annual) were planted to annual crops: spring wheat, rapeseed, barley and spring wheat in 2008, 2009, 2010 and 2011, respectively. In late September of 2011 the grass-alfalfa forage was killed and in 2012, 2013 and 2014 all four plots were planted with corn, soybean and spring wheat, respectively. Management decisions increased emissions such as fertilizer N addition, and hay, straw and silage crop removal greatly increased emissions while choosing legume grain and perennial crops reduced emissions. Weather variation affecting seasonal and daily soil moisture, length of spring freeze-thaw period, and crop yield served to increase or decrease emissions. The variation in management and weather will be discussed in regards to impact on net emissions over the nine year study and answer if development of greenhouse gas neutral cropping systems is possible.

  19. Experiments on vertical gas-liquid pipe flows using ultrafast X-ray tomography

    Energy Technology Data Exchange (ETDEWEB)

    Banowski, M.; Beyer, M.; Lucas, D.; Hoppe, D.; Barthel, F. [Helmholtz-Zentrum Dresden-Rossendorf (Germany). Inst. fuer Sicherheitsforschung

    2016-12-15

    For the qualification and validation of two-phase CFD-models for medium and large-scale industrial applications dedicated experiments providing data with high temporal and spatial resolution are required. Fluid dynamic parameter like gas volume fraction, bubble size distribution, velocity or turbulent kinetic energy should be measured locally. Considering the fact, that the used measurement techniques should not affect the flow characteristics, radiation based tomographic methods are the favourite candidate for such measurements. Here the recently developed ultrafast X-ray tomography, is applied to measure the local and temporal gas volume fraction distribution in a vertical pipe. To obtain the required frame rate a rotating X-ray source by a massless electron beam and a static detector ring are used. Experiments on a vertical pipe are well suited for development and validation of closure models for two-phase flows. While vertical pipe flows are axially symmetrically, the boundary conditions are well defined. The evolution of the flow along the pipe can be investigated as well. This report documents the experiments done for co-current upwards and downwards air-water and steam-water flows as well as for counter-current air-water flows. The details of the setup, measuring technique and data evaluation are given. The report also includes a discussion on selected results obtained and on uncertainties.

  20. The Calculated Ratio of the Gas Flow in a Countercurrent Cyclone Dust Concentrator

    Science.gov (United States)

    Vasilevsky, Michail; Razva, Aleksandr; Pleschko, Alissa; Kadurkin, Ivan

    2016-02-01

    There are numerous studies of the structure of swirling flow in a variety of devices in which the peculiarities of the parameters associated with the twist flow. The values of the local parameters of the twist of the axial direction are experimentally and connect them with a constructive twist parameter, which is built from the idealized repose of the gas flow in vortex distribution and speed at the exit of the swirl. For counter flow chamber is the equation for the input pulse in the radial direction and the twist parameter is provided in the radial direction. It allows us to estimate the maximum radius of the circumferential velocity not only near the outlet, but also near the end surface of the chamber. On a cylindrical surface with a radius of outlet cyclone tangential turbulent friction in the radial direction depends on the product of a circle and radial speeds. Compiled equation changes the flow of angular momentum in the axial zone, depending on the force of friction tangential flow on the surface with the radius of the outlet pipe of the cyclone. This equation allowed assessing the circulation of gas in the axial zone.

  1. An integrated simulator of structure and anisotropic flow in gas diffusion layers with hydrophobic additives

    Science.gov (United States)

    Burganos, Vasilis N.; Skouras, Eugene D.; Kalarakis, Alexandros N.

    2017-10-01

    The lattice-Boltzmann (LB) method is used in this work to reproduce the controlled addition of binder and hydrophobicity-promoting agents, like polytetrafluoroethylene (PTFE), into gas diffusion layers (GDLs) and to predict flow permeabilities in the through- and in-plane directions. The present simulator manages to reproduce spreading of binder and hydrophobic additives, sequentially, into the neat fibrous layer using a two-phase flow model. Gas flow simulation is achieved by the same code, sidestepping the need for a post-processing flow code and avoiding the usual input/output and data interface problems that arise in other techniques. Compression effects on flow anisotropy of the impregnated GDL are also studied. The permeability predictions for different compression levels and for different binder or PTFE loadings are found to compare well with experimental data for commercial GDL products and with computational fluid dynamics (CFD) predictions. Alternatively, the PTFE-impregnated structure is reproduced from Scanning Electron Microscopy (SEM) images using an independent, purely geometrical approach. A comparison of the two approaches is made regarding their adequacy to reproduce correctly the main structural features of the GDL and to predict anisotropic flow permeabilities at different volume fractions of binder and hydrophobic additives.

  2. A novel acoustic method for gas flow measurement using correlation techniques

    Energy Technology Data Exchange (ETDEWEB)

    Knuuttila, M. [VTT Chemical Technology, Espoo (Finland). Industrial Physics

    1997-12-31

    The study demonstrates a new kind of acoustic method for gas flow measurement. The method uses upstream and downstream propagating low frequency plane wave and correlation techniques for volume flow rate determination. The theory of propagating low frequency plane waves in the pipe is introduced and is proved empirically to be applicable for flow measurement. The flow profile dependence of the method is verified and found to be negligible at least in the region of moderate perturbations. The physical principles of the method were applied in practice in the form of a flowmeter with new design concepts. The developed prototype meters were verified against the reference standard of NMI (Nederlands Meetinstituut), which showed that a wide dynamic range of 1:80 is achievable with total expanded uncertainty below 0.3 %. Also the requirements used for turbine meters of linearity, weighted mean error and stability were shown to be well fulfilled. A brief comparison with other flowmeter types shows the new flowmeter to be competitive. The advantages it offers are a small pressure drop over the meter, no blockage of flow in possible malfunction, no pulsation to flow, essentially no moving parts, and the possibility for bidirectional measurements. The introduced flowmeter is also capable of using the telephone network or a radio-modem to read the consumption of gas and report its operation to the user. (orig.) 51 refs.

  3. Hydrodynamic models of gas-liquid two-phase flow in porous media

    Directory of Open Access Journals (Sweden)

    B GutiérrezR

    2016-09-01

    Full Text Available Equations and models describing the hydrodynamic of gas-liquid two-phase flows in porous media have become increasingly necessary in order to predict their main features throughout porous networks. The main subject of this research was to study the influence of capillary, viscous and inertial forces and flow configurations on the hydrodynamic features of a gas-liquid two-phase flow in a glass micromodel. Experimental results were obtained and compared with those predicted by three published models. The Fundamental Forces Balance and the Fluid-Fluid Interface models did not describe accurately experimental behavior even when the first of them considers particular characteristics of flow patterns. Semi-empirical models such as The Relative Permeability can describe physical flow characteristics and can also be modified to include different effects not initially considered. Traditionally, relative permeabilities have been associated almost exclusively with saturation conditions. However, it was concluded in this research that liquid relative permeability is function of saturation conditions but also depends on flow patterns and Capillary number.

  4. The Calculated Ratio of the Gas Flow in a Countercurrent Cyclone Dust Concentrator

    Directory of Open Access Journals (Sweden)

    Vasilevsky Michail

    2016-01-01

    Full Text Available There are numerous studies of the structure of swirling flow in a variety of devices in which the peculiarities of the parameters associated with the twist flow. The values of the local parameters of the twist of the axial direction are experimentally and connect them with a constructive twist parameter, which is built from the idealized repose of the gas flow in vortex distribution and speed at the exit of the swirl. For counter flow chamber is the equation for the input pulse in the radial direction and the twist parameter is provided in the radial direction. It allows us to estimate the maximum radius of the circumferential velocity not only near the outlet, but also near the end surface of the chamber. On a cylindrical surface with a radius of outlet cyclone tangential turbulent friction in the radial direction depends on the product of a circle and radial speeds. Compiled equation changes the flow of angular momentum in the axial zone, depending on the force of friction tangential flow on the surface with the radius of the outlet pipe of the cyclone. This equation allowed assessing the circulation of gas in the axial zone.

  5. Lattice Boltzmann accelerated direct simulation Monte Carlo for dilute gas flow simulations.

    Science.gov (United States)

    Di Staso, G; Clercx, H J H; Succi, S; Toschi, F

    2016-11-13

    Hybrid particle-continuum computational frameworks permit the simulation of gas flows by locally adjusting the resolution to the degree of non-equilibrium displayed by the flow in different regions of space and time. In this work, we present a new scheme that couples the direct simulation Monte Carlo (DSMC) with the lattice Boltzmann (LB) method in the limit of isothermal flows. The former handles strong non-equilibrium effects, as they typically occur in the vicinity of solid boundaries, whereas the latter is in charge of the bulk flow, where non-equilibrium can be dealt with perturbatively, i.e. according to Navier-Stokes hydrodynamics. The proposed concurrent multiscale method is applied to the dilute gas Couette flow, showing major computational gains when compared with the full DSMC scenarios. In addition, it is shown that the coupling with LB in the bulk flow can speed up the DSMC treatment of the Knudsen layer with respect to the full DSMC case. In other words, LB acts as a DSMC accelerator.This article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'. © 2016 The Author(s).

  6. An Integrated microfluidic platform for liquid droplet in gas flow generation with in liquid flow collection and manipulation

    Science.gov (United States)

    Tirandazi, Pooyan; Hidrovo, Carlos H.

    2016-11-01

    Discretization of biological samples and chemical reactions within digital droplets is a powerful technique which has rapidly emerged in many biochemical syntheses. The ability to generate, manipulate, and monitor millions of microdroplets in a short time provides great potential for high throughput screening and detection in microbiology. Here we report a microfluidic device for the formation of uniform microdroplets (50 μm-100 μm) using a high speed gas as the continuous phase. Gas-borne droplets are generated in a chip-based flow-focusing device fabricated in PDMS, and travel along the gaseous microchannel and are subsequently captured within a second liquid phase. The droplets are then transferred and collected in a minichamber and move into the manipulation section for further processing operations on the drops. All these steps are performed automatically in a single multilayer chip. This integrated microfluidic platform for generation, collection, and manipulation of the droplets provides great opportunities for monitoring and detection of gas-analytes. Utilizing the generated picoliter airborne droplets feature lower reaction times and higher transfer rates as compared to conventional air sampling techniques. Thus, it can greatly facilitate the investigation of airborne analytes by interrogation of the digital droplets using different analytical techniques. Furthermore, the presented liquid-in-gas generation method can be utilized for production of oil-free microparticles and microcapsules used in the food industry and for drug delivery.

  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. 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

  9. Use of Distribution Devices for Hydraulic Profiling of Coolant Flow in Core Gas-cooled Reactors

    Directory of Open Access Journals (Sweden)

    A. A. Satin

    2014-01-01

    Full Text Available In setting up a reactor plant for the transportation-power module of the megawatt class an important task is to optimize the path of flow, i.e. providing moderate hydraulic resistance, uniform distribution of the coolant. Significant contribution to the hydraulic losses makes one selected design of the coolant supplies. It is, in particular, hemispherical or semi-elliptical shape of the supply reservoir, which is selected to reduce its mass, resulting in the formation of torusshaped vortex in the inlet manifold, that leads to uneven coolant velocity at the inlet into the core, the flow pulsations, hydraulic losses.To control the flow redistribution in the core according to the level of energy are used the switchgear - deflectors installed in a hemispherical reservoir supplying coolant to the fuel elements (FE of the core of gas-cooled reactor. This design solution has an effect on the structure of the flow, rate in the cooling duct, and the flow resistance of the collector.In this paper we present the results of experiments carried out on the gas dynamic model of coolant paths, deflectors, and core, comprising 55 fuel rod simulators. Numerical simulation of flow in two-parameter model, using the k-ε turbulence model, and the software package ANSYS CFX v14.0 is performed. The paper demonstrates that experimental results are in compliance with calculated ones.The results obtained suggest that the use of switchgear ensures a coolant flow balance directly at the core inlet, thereby providing temperature reduction of fuel rods with a uniform power release in the cross-section. Considered options to find constructive solutions for deflectors give an idea to solve the problem of reducing hydraulic losses in the coolant paths, to decrease pulsation components of flow in the core and length of initial section of flow stabilization.

  10. Implementation of an ultrasonic instrument for simultaneous mixture and flow analysis of binary gas systems

    Energy Technology Data Exchange (ETDEWEB)

    Alhroob, M.; Boyd, G.; Hasib, A.; Pearson, B.; Srauss, M.; Young, J. [Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019, (United States); Bates, R.; Bitadze, A. [School of Physics and Astronomy, University of Glasgow, G12 8QQ, (United Kingdom); Battistin, M.; Berry, S.; Bonneau, P.; Botelho-Direito, J.; Bozza, G.; Crespo-Lopez, O.; DiGirolamo, B.; Favre, G.; Godlewski, J.; Lombard, D.; Zwalinski, L. [CERN, 1211 Geneva 23, (Switzerland); Bousson, N.; Hallewell, G.; Mathieu, M.; Rozanov, A. [Centre de Physique des Particules de Marseille, 163 Avenue de Luminy, 13288 Marseille Cedex 09, (France); Deterre, C.; O' Rourke, A. [Deutsches Elektronen-Synchrotron, Notkestrasse 85, D-22607 Hamburg, (Germany); Doubek, M.; Vacek, V. [Czech Technical University, Technick 4, 166 07 Prague 6, (Czech Republic); Degeorge, C. [Physics Department, Indiana University, Bloomington, IN 47405, (United States); Katunin, S. [B.P. Konstantinov Petersburg Nuclear Physics Institute (PNPI), 188300 St. Petersburg, (Russian Federation); Langevin, N. [Institut Universitaire de Technologie of Marseille, University of Aix-Marseille, 142 Traverse Charles Susini, 13013 Marseille, (France); McMahon, S. [Rutherford Appleton Laboratory - Science and Technology Facilities Council, Harwell Science and Innovation Campus, Didcot OX11 OQX, (United Kingdom); Nagai, K. [Department of Physics, Oxford University, Oxford OX1 3RH, (United Kingdom); Robinson, D. [Department of Physics and Astronomy, University of Cambridge, (United Kingdom); Rossi, C. [INFN - Genova, Via Dodecaneso 33, 16146 Genova, (Italy)

    2015-07-01

    Precision ultrasonic measurements in binary gas systems provide continuous real-time monitoring of mixture composition and flow. Using custom micro-controller-based electronics, we have developed an ultrasonic instrument, with numerous potential applications, capable of making continuous high-precision sound velocity measurements. The instrument measures sound transit times along two opposite directions aligned parallel to - or obliquely crossing - the gas flow. The difference between the two measured times yields the gas flow rate while their average gives the sound velocity, which can be compared with a sound velocity vs. molar composition look-up table for the binary mixture at a given temperature and pressure. The look-up table may be generated from prior measurements in known mixtures of the two components, from theoretical calculations, or from a combination of the two. We describe the instrument and its performance within numerous applications in the ATLAS experiment at the CERN Large Hadron Collider (LHC). The instrument can be of interest in other areas where continuous in-situ binary gas analysis and flowmetry are required. (authors)

  11. Film stability in a vertical rotating tube with a core-gas flow.

    Science.gov (United States)

    Sarma, G. S. R.; Lu, P. C.; Ostrach, S.

    1971-01-01

    The linear hydrodynamic stability of a thin-liquid layer flowing along the inside wall of a vertical tube rotating about its axis in the presence of a core-gas flow is examined. The stability problem is formulated under the conditions that the liquid film is thin, the density and viscosity ratios of gas to liquid are small and the relative (axial) pressure gradient in the gas is of the same order as gravity. The resulting eigenvalue problem is first solved by a perturbation method appropriate to axisymmetric long-wave disturbances. The damped nature (to within the thin-film and other approximations made) of the nonaxisymmetric and short-wave disturbances is noted. In view of the limitations on a truncated perturbation solution when the disturbance wavenumber is not small, an initial value method using digital computer is presented. Stability characteristics of neutral, growing, and damped modes are presented showing the influences of rotation, surface tension, and the core-gas flow. Energy balance in a neutral mode is also illustrated.

  12. Microscale Modelling of Water and Gas-Water Flows in Subsea Sand Sediment

    Science.gov (United States)

    Sato, T.; Sugita, T.; Hirabayashi, S.; Nagao, J.; Jin, Y.; Kiyono, F.

    2009-12-01

    Methane hydrate is a promising energy resource in the near future. Its production is a current hot topic and flow of methane gas with water in sediment sand layer is very important to predict the production rate. In this study, permeability of microscale sand layer was numerically simulated by a three-dimensional lattice Boltzmann method. Shapes of real sands were extracted by series expansion of spherical harmonics using CT-scan images of real subsea core samples. These extracted sands were located in a cubic lattice domain by a simulated annealing method to fit to given porosities. Pressure difference was imposed at the both end faces of the domain to flow water and methane gas. By this simulation, permeability of water phase and water-gas two-phase flow were analysed and compared well with existing models. This work was financially supported by Japan's Methane Hydrate R&D Program planned by Ministry of Economy, Trade and Industry (METI). 3D image of an extracted frame-sand grain Distribution of gas and water phases in computational domain for Sw=0.80

  13. Gas flow rate dependence of the discharge characteristics of a helium atmospheric pressure plasma jet interacting with a substrate

    Science.gov (United States)

    Yan, Wen; Economou, Demetre J.

    2017-10-01

    A 2D (axisymmetric) computational study of the discharge characteristics of an atmospheric pressure plasma jet as a function of gas flow rate was performed. The helium jet emerged from a dielectric tube, with an average gas flow velocity in the range 2.5-20 m s-1 (1 atm, 300 K) in a nitrogen ambient, and impinged on a substrate a short distance dowstream. The effect of the substrate conductivity (conductror versus insulator) was also studied. Whenever possible, simulation predictions were compared with published experimental observations. Discharge ignition and propagation in the dielectric tube were hardly affected by the He gas flow velocity. Most properties of the plasma jet, however, depended sensitively on the He gas flow velocity, which determined the concentration distributions of helium and nitrogen in the mixing layer forming in the gap between the tube exit and the substrate. At low gas flow velocity, the plasma jet evolved from a hollow (donut-shaped) feature to one where the maximum of electron density was on axis. When the gas flow velocity was high, the plasma jet maintained its hollow structure until it struck the substrate. For a conductive substrate, the radial ion fluxes to the surface were relatively uniform over a radius of ~0.4-0.8 mm, and the dominant ion flux was that of He+. For a dielectric substrate, the radial ion fluxes to the surface peaked on the symmetry axis at low He gas flow velocity, but a hollow ion flux distribution was observed at high gas flow velocity. At the same time, the main ion flux switched from N2+ to He2+ as the He gas flow velocity increased from a low to a high value. The diameter of the plasma ‘footprint’ on the substrate first increased with increasing He gas flow velocity, and eventually saturated with further increases in velocity.

  14. Three-dimensional direct numerical simulations of co/counter-current vertical gas-Liquid annular flows

    Science.gov (United States)

    Farhaoui, Asma; Kahouadji, Lyes; Chergui, Jalel; Juric, Damir; Shin, Seungwon; Craster, Richard; Matar, Omar

    2016-11-01

    We carry out three-dimensional numerical simulations of co/counter current Gas-Liquid annular flows using the parallel code, BLUE, based on a projection method for the resolution of the Navier-Stokes equations and a hybrid Front-Tracking/Level-Set method for the interface advection. Gas-Liquid annular flows and falling films in a pipe are present in a broad range of industrial processes. This configuration consists of an important multiphase flow regime where the liquid occupies the area adjacent to the internal circumference of the pipe and the gas flows in the pipe core. Experimentally, four distinctive flow regimes were identified ('dual-wave', 'thick ripple', 'disturbance wave' and 'regular wave' regimes), that we attempt to simulate. In order to visualize these different regimes, various liquid (water) and gas (air) flow-rates are investigated. EPSRC UK Programme Grant EP/K003976/1.

  15. Performance of different PEEP valves and helmet outlets at increasing gas flow rates: a bench top study.

    Science.gov (United States)

    Isgrò, S; Zanella, A; Giani, M; Abd El Aziz El Sayed Deab, S; Pesenti, A; Patroniti, N

    2012-10-01

    Aim of the paper was to assess the performance of different expiratory valves and the resistance of helmet outlet ports at increasing gas flow rates. A gas flow-meter was connected to 10 different expiratory peep valves: 1 water-seal valve, 4 precalibrated fixed PEEP valves and 5 adjustable PEEP valves. Three new valves of each brand, set at different pressure levels (5-7.5-10-12.5-15 cmH(2)O, if available), were tested at increasing gas flow rates (from 30 to 150 L/min). We measured the pressure generated just before the valves. Three different helmets sealed on a mock head were connected at the inlet port with a gas flow-meter while the outlet was left clear. We measured the pressure generated inside the helmet (due to the flow-resistance of the outlet port) at increasing gas flow rates. Adjustable valves showed a variable degree flow-dependency (increasing difference between the measured and the expected pressure at increasing flow rates), while pre-calibrated valves revealed a flow-independent behavior. Water seal valve showed low degree flow-dependency. The pressures generated by the outlet port of the tested helmets ranged from 0.02 to 2.29 cmH(2)O at the highest gas flow rate. Adjustable PEEP valves are not suggested for continuous-flow CPAP systems as their flow-dependency can lead to pressures higher than expected. Precalibrated and water seal valves exhibit the best performance. Different helmet outlet ports do not significantly affect the pressure generated during helmet CPAP. In order to avoid iatrogenic complications gas flow and pressure delivered during helmet CPAP must always be monitored.

  16. Flow and heat transfer in gas turbine disk cavities subject to nonuniform external pressure field

    Energy Technology Data Exchange (ETDEWEB)

    Roy, R.P.; Kim, Y.W.; Tong, T.W. [Arizona State Univ., Tempe, AZ (United States)

    1995-10-01

    Injestion of hot gas from the main-stream gas path into turbine disk cavities, particularly the first-stage disk cavity, has become a serious concern for the next-generation industrial gas turbines featuring high rotor inlet temperature. Fluid temperature in the cavities increases further due to windage generated by fluid drag at the rotating and stationary surfaces. The resulting problem of rotor disk heat-up is exacerbated by the high disk rim temperature due to adverse (relatively flat) temperature profile of the mainstream gas in the annular flow passage of the turbine. A designer is concerned about the level of stresses in the turbine rotor disk and its durability, both of which are affected significantly by the disk temperature distribution. This distribution also plays a major role in the radial position of the blade tip and thus, in establishing the clearance between the tip and the shroud. To counteract mainstream gas ingestion as well as to cool the rotor and the stator disks, it is necessary to inject cooling air (bled from the compressor discharge) into the wheel space. Since this bleeding of compressor air imposes a penalty on the engine cycle performance, the designers of disk cavity cooling and sealing systems need to accomplish these tasks with the minimum possible amount of bleed air without risking disk failure. This requires detailed knowledge of the flow characteristics and convective heat transfer in the cavity. The flow in the wheel space between the rotor and stator disks is quite complex. It is usually turbulent and contains recirculation regions. Instabilities such as vortices oscillating in space have been observed in the flow. It becomes necessary to obtain both a qualitative understanding of the general pattern of the fluid motion as well as a quantitative map of the velocity and pressure fields.

  17. Evaporation-induced gas-phase flows at selective laser melting

    Science.gov (United States)

    Zhirnov, I.; Kotoban, D. V.; Gusarov, A. V.

    2018-02-01

    Selective laser melting is the method for 3D printing from metals. A solid part is built from powder layer-by-layer. A continuum-wave laser beam scans every powder layer to fuse powder. The process is studied with a high-speed CCD camera at the frame rate of 104 fps and the resolution up to 5 µm per pixel. Heat transfer and evaporation in the laser-interaction zone are numerically modeled. Droplets are ejected from the melt pool in the direction around the normal to the melt surface and the powder particles move in the horizontal plane toward the melt pool. A vapor jet is observed in the direction of the normal to the melt surface. The velocities of the droplets, the powder particles, and the jet flow and the mass loss due to evaporation are measured. The gas flow around the vapor jet is calculated by Landau's model of submerged jet. The measured velocities of vapor, droplets, and powder particles correlate with the calculated flow field. The obtained results show the importance of evaporation and the flow of the vapor and the ambient gas. These gas-dynamic phenomena can explain the formation of the denudated zones and the instability at high-energy input.

  18. Comparison of emergence times with different fresh gas flow rates following desflurane anaesthesia.

    Science.gov (United States)

    Jeong, Ji Seon; Yoon, Sung Wook; Choi, Sung Lark; Choi, Sung Hwan; Lee, Bong Yeong; Jeong, Mi Ae

    2014-12-01

    To investigate emergence times with different fresh gas flow rates, following desflurane anaesthesia. Patients undergoing surgery with desflurane anaesthesia were randomly assigned to receive fresh gas flow rates of 100% oxygen during emergence of 2 l/min (group D2), 4 l/min (group D4) or 6 l/min (group D6). Time to eye opening, spontaneous movement and extubation (emergence time) were assessed after desflurane discontinuation. The end-tidal concentration of desflurane and bispectral index were recorded at each of these timepoints. A total of 105 patients were included in the study, with 35 in each of the three groups. Mean times to extubation were 17.6 min, 9.9 min and 9.1 min in groups D2, D4 and D6, respectively. Times to eye opening, spontaneous movement and extubation in group D2 were significantly longer than in groups D4 and D6. These results suggest that there is the potential to predict emergence time based on fresh gas flow rate following desflurane anaesthesia. It should therefore be possible to use a low-flow technique during the emergence period, in addition to the maintenance period, without delaying recovery if the inhaled anaesthetic is stopped at the predicted time before the end of surgery. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  19. Evaluation of methods describing the flow of gas-liquid mixture in wells

    Energy Technology Data Exchange (ETDEWEB)

    Salim, P.H.; Stanislav, J.F. (Calgary Univ., AB (Canada))

    1994-02-01

    The simulataneous gas-liquid flow in pipes is of interest to petroleum, chemical and nuclear industries. Numerous empirical correlations have been proposed to estimate the pressure drop and liquid holdup for flow of gas-liquid mixtures, only a few of which are in current use. Ansari et al. (1990) published a comprehensive mechanistic model which describes the hydrodynamics of gas-liquid flow in horizontal and vertical pipes. A study was conducted to compare the individual performances of selected correlations and models with data obtained from both the field and laboratory sources. Most of the field data were for annular mist flow. The laboratory data are reported for air-water mixtures and this eliminates the need for flash-type calculations. However, the field data were obtained on hydrocarbon systems, and any inaccuracies in connection with C[sub 7+] fractions may potentially obscure the results of the calculations. It was found that the empirical correlations of Orkiszewski and Duns and Ros appear to be less efficient than methods derived from mechanistic concepts. The Ansari et al. method seems to be the most promising of all, however additional study is required for a definite conclusion. 31 refs., 7 tabs.

  20. Gas flow dependence for plasma-needle disinfection of S. mutans bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Goree, J [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States); Liu Bin [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States); Drake, David [Dows Institute for Dental Research, Dept. of Endodontics, College of Dentistry, University of Iowa, Iowa City, IA 52242 (United States)

    2006-08-21

    The role of gas flow and transport mechanisms are studied for a small low-power impinging jet of weakly-ionized helium at atmospheric pressure. This plasma needle produces a non-thermal glow discharge plasma that kills bacteria. A culture of Streptococcus mutans (S. mutans) was plated onto the surface of agar, and spots on this surface were then treated with plasma. Afterwards, the sample was incubated and then imaged. These images, which serve as a biological diagnostic for characterizing the plasma, show a distinctive spatial pattern for killing that depends on the gas flow rate. As the flow is increased, the killing pattern varies from a solid circle to a ring. Images of the glow reveal that the spatial distribution of energetic electrons corresponds to the observed killing pattern. This suggests that a bactericidal species is generated in the gas phase by energetic electrons less than a millimetre from the sample surface. Mixing of air into the helium plasma is required to generate the observed O and OH radicals in the flowing plasma. Hydrodynamic processes involved in this mixing are buoyancy, diffusion and turbulence.

  1. Mass flow discharge and total temperature characterisation of a pyrotechnic gas generator formulation for airbag systems

    Energy Technology Data Exchange (ETDEWEB)

    Neutz, Jochen; Koenig, Andreas [Fraunhofer Institut fuer Chemische Technologie ICT, Pfinztal (Germany); Knauss, Helmut; Jordan, Sebastian; Roediger, Tim; Smorodsky, Boris [Universitaet Stuttgart (Germany). Institut fuer Aerodynamik und Gasdynamik; Bluemcke, Erich Walter [AUDI AG, Department I/EK-523, Ingolstadt (Germany)

    2009-06-15

    The mass flow characteristics of gas generators for airbag applications have to comply with a number of requirements for an optimal deployment of the airbag itself. Up to now, the mass flow was determined from pressure time histories of so-called can tests. This procedure suffers from the missing knowledge on the temperature of the generated gas entering the can. A new test setup described in this paper could overcome this problem by providing highly time resolved information on the gas's total temperature and the mass flow of the generator. The test setup consisted of a combustion chamber with a specially designed Laval nozzle in combination with a temperature sensor of high time resolution. The results showed a high time resolved temperature signal, which was disturbed by the formation of a slag layer on the sensor. Plausibility considerations with experimentally and thermodynamically determined combustion temperatures led to satisfying results for the overall temperature as characteristic parameter of airbag inflating gases flows from pyrotechnics. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  2. Development of the ARISTOTLE webware for cloud-based rarefied gas flow modeling

    Science.gov (United States)

    Deschenes, Timothy R.; Grot, Jonathan; Cline, Jason A.

    2016-11-01

    Rarefied gas dynamics are important for a wide variety of applications. An improvement in the ability of general users to predict these gas flows will enable optimization of current, and discovery of future processes. Despite this potential, most rarefied simulation software is designed by and for experts in the community. This has resulted in low adoption of the methods outside of the immediate RGD community. This paper outlines an ongoing effort to create a rarefied gas dynamics simulation tool that can be used by a general audience. The tool leverages a direct simulation Monte Carlo (DSMC) library that is available to the entire community and a web-based simulation process that will enable all users to take advantage of high performance computing capabilities. First, the DSMC library and simulation architecture are described. Then the DSMC library is used to predict a number of representative transient gas flows that are applicable to the rarefied gas dynamics community. The paper closes with a summary and future direction.

  3. Tracing Gas Flows from Halo to Disk: Observing the Milky Way's Galactic Fountain

    Science.gov (United States)

    Werk, Jessica

    2017-08-01

    Galactic-scale winds are a common feature of galaxy formation models, and are observed ubiquitously across the star-forming sequence down to 0.5 Msun/yr. However, empirical constraints on the radial density profile and total spatial extent of these winds have been very challenging to obtain. At the same time, direct empirical evidence is scarce for the flows of gas onto galaxy disks that are critical for maintaining star formation. We have devised a simple experiment using blue horizontal branch (BHB) stars in the halo of the Milky Way that will directly map the location and density of diffuse, ionized gas flows between the Galactic disk and halo. This experiment, initiated in Cycle 23, obtains COS FUV spectra of halo BHB stars that sample a range of scale heights to 13 kpc towards the Northern Galactic pole. In this Cycle, we propose to observe 3 additional BHB stars along the complementary sightline to the South, effectively doubling our sightline sample size and permitting a novel test of the symmetry of gas flows at the disk-halo interface. This program allows us to unambiguously track inflowing and outflowing material from the Milky Way via absorption component blueshifts and redshifts. With BHBs at a range of known distances, we will directly determine changes in the gas density and metal mass as it travels through the disk-halo interface. Our experiment will yield the most detailed constraints on the physical state and energetics of the gas in the Milky Way's Galactic Fountain to date. Such constraints are fundamental to understanding the role of feedback in building the Galactic gaseous halo and the extent to which ongoing gas accretion fuels the ISM.

  4. Theoretical investigation on exciplex pumped alkali vapor lasers with sonic-level gas flow

    Science.gov (United States)

    Xu, Xingqi; Shen, Binglin; Huang, Jinghua; Xia, Chunsheng; Pan, Bailiang

    2017-07-01

    Considering the effects of higher excited and ion energy states and utilizing the methodology in the fluid mechanics, a modified model of exciplex pumped alkali vapor lasers with sonic-level flowing gas is established. A comparison of output characters between subsonic flow and supersonic flow is made. In this model, higher excited and ion energy states are included as well, which modifies the analysis of the kinetic process and introduces larger heat loading in an operating CW exciplex-pumped alkali vapor laser. The results of our calculations predict that subsonic flow has an advantage over supersonic flow under the same fluid parameters, and stimulated emission in the supersonic flow would be quenched while the pump power reaching a threshold value of the fluid choking effect. However, by eliminating the influence of fluid characters, better thermal management and higher optical conversion efficiency can be obtained in supersonic flow. In addition, we make use of the "nozzle-diffuser" to build up the closed-circle flowing experimental device and gather some useful simulated results.

  5. Stability analysis of inclined stratified two-phase gas-liquid flow

    Energy Technology Data Exchange (ETDEWEB)

    Salhi, Yacine, E-mail: yasalhi@ulb.ac.b [Laboratoire de Mecanique des Fluides Theorique et Appliquee, Faculte de Physique, U.S.T.H.B. El-Alia B.P. 32 16111. Alger (Algeria); Service Aero-Thermo-Mecanique Faculte des Sciences Appliquees Universite Libre de Bruxelles CP165, avenue F.D. Roosevelt 50, 1050 Bruxelles, Belgique (Belgium); Si-Ahmed, El-Khider [Laboratoire de Mecanique des Fluides Theorique et Appliquee, Faculte de Physique, U.S.T.H.B. El-Alia B.P. 32 16111. Alger (Algeria); GEPEA, Universite de Nantes, CNRS, UMR6144, CRTT-BP 406, 44602 Saint-Nazaire (France); Legrand, Jack [GEPEA, Universite de Nantes, CNRS, UMR6144, CRTT-BP 406, 44602 Saint-Nazaire (France); Degrez, Gerard [Service Aero-Thermo-Mecanique Faculte des Sciences Appliquees Universite Libre de Bruxelles CP165, avenue F.D. Roosevelt 50, 1050 Bruxelles, Belgique (Belgium)

    2010-05-15

    The present investigation involves the modeling of gas-liquid interface in a two-phase stratified flow through a horizontal or nearly-horizontal circular duct. The most complete and fundamental model used for these calculations is known as the one-dimensional two-fluid model. It is the most accurate of the two-phase models since it considers each phase independently and links both phases with six conservation equations. The mass and momentum balance equations are written in dimensionless form. The dimensionless mass and momentum balance equations are combined with the method of characteristics and an explicit method to simulate the flow. At first, the linear stability of the flow is investigated by disturbing the liquid flow with a small perturbation. An improved version of the one-dimensional two-fluid model for horizontal flows is developed as a set of non-linear hyperbolic governing equations. The importance of this research lies in obtaining a model that accounts for the effects of flow and geometrical conditions (such as liquid viscosity, surface tension). It is shown that, for positive values of the slope angle (upward inclination), the slug flow becomes more probable, whereas negative values of the slope angle (downward inclination) induce a more stable stratified flow.

  6. Gas-liquid two-phase flows in rectangular polymer micro-channels

    Science.gov (United States)

    Kim, Namwon; Evans, Estelle T.; Park, Daniel S.; Soper, Steven A.; Murphy, Michael C.; Nikitopoulos, Dimitris E.

    2011-08-01

    This study addresses gas-liquid two-phase flows in polymer (PMMA) micro-channels with non-molecularly smooth and poorly wetting walls (typical contact angle of 65°) unlike previous studies conducted on highly wetting molecularly smooth materials (e.g., glass/silicon). Four fundamentally different topological flow regimes (Capillary Bubbly, Segmented, Annular, Dry) were identified along with two transitory ones (Segmented/Annular, Annular/Dry) and regime boundaries were identified from the two different test chips. The regime transition boundaries were influenced by the geometry of the two-phase injection, the aspect ratio of the test micro-channels, and potentially the chip material as evidenced from comparisons with the results of previous studies. Three principal Segmented flow sub-regimes (1, 2, and 3) were identified on the basis of quantified topological characteristics, each closely correlated with two-phase flow pressure drop trends. Irregularity of the Segmented regimes and related influencing factors were addressed and discussed. The average bubble length associated with the Segmented flows scaled approximately with a power law of the liquid volumetric flow ratio, which depends on aspect ratio, liquid superficial velocity, and the injection system. A simplified semi-empirical geometric model of gas bubble and liquid plug volumes provided good estimates of liquid plug length for most of the segmented regime cases and for all test-channel aspect ratios. The two-phase flow pressure drop was measured for the square test channels. Each Segmented flow sub-regime was associated with different trends in the pressure drop scaled by the viscous scale. These trends were explained in terms of the quantified flow topology (measured gas bubble and liquid plug lengths) and the number of bubble/plug pairs. Significant quantitative differences were found between the two-phase pressure drop in the polymer micro-channels of this study and those obtained from previous glass

  7. The effect of slot height and difference in gas densities for coaxial jets on jet mixing in constrained swirled flow

    Science.gov (United States)

    Shishkin, N. E.

    2015-07-01

    Experiments were conducted about the effect of height of annular slot on efficiency of film cooling in a tube flow. Nonisothermal nature of flows was modelled by mixing of jets with different densities: air with argon or with helium: the concentration of foreign gas on wall was measured. The influence of nearwall jet swirling and of proportions of densities of gas flows as key factors for laminarization of mixing was considered.

  8. Influence of blast furnace gas flow speed on dust deposition characteristics in butterfly valve region

    OpenAIRE

    Lixin WANG; Bin WANG; Fengshan HUANG

    2016-01-01

    The blast furnace gas contains plenty of dust, which deposits easily on the bottom of seat sealing surface of the tri-eccentric butterfly valve in the pipeline, causing stuck and damage to the valve plate, thereby affects the production of the blast furnace and brings great economic loss. To derive the influence mechanism of effects of the blast furnace gas flow speed within the pipeline on the dust deposition laws in the butterfly valve region, a 3D model of the butterfly valve and its regio...

  9. GARUSO - Version 1.0. Uncertainty model for multipath ultrasonic transit time gas flow meters

    Energy Technology Data Exchange (ETDEWEB)

    Lunde, Per; Froeysa, Kjell-Eivind; Vestrheim, Magne

    1997-09-01

    This report describes an uncertainty model for ultrasonic transit time gas flow meters configured with parallel chords, and a PC program, GARUSO Version 1.0, implemented for calculation of the meter`s relative expanded uncertainty. The program, which is based on the theoretical uncertainty model, is used to carry out a simplified and limited uncertainty analysis for a 12`` 4-path meter, where examples of input and output uncertainties are given. The model predicts a relative expanded uncertainty for the meter at a level which further justifies today`s increasing tendency to use this type of instruments for fiscal metering of natural gas. 52 refs., 15 figs., 11 tabs.

  10. A modular particle continuum numerical method for hypersonic non-equilibrium gas flows

    Science.gov (United States)

    Schwartzentruber, T. E.; Scalabrin, L. C.; Boyd, I. D.

    2007-07-01

    A modular particle-continuum (MPC) numerical method for steady-state flows is presented which solves the Navier-Stokes equations in regions of near-equilibrium and uses the direct simulation Monte Carlo (DSMC) method to simulate regions of non-equilibrium gas flow. Existing, state-of-the-art, DSMC and Navier-Stokes solvers are coupled together using a novel modular implementation which requires only a limited number of additional hybrid functions. Hybrid functions are used to adaptively position particle-continuum interfaces and update boundary conditions in each module at appropriate times. The MPC method is validated for 2D flow over a cylinder at various hypersonic Mach numbers where the global Knudsen number is 0.01. For the cases considered, the MPC method is verified to accurately reproduce DSMC flow field results as well as local particle velocity distributions up to 2.2 times faster than full DSMC simulations.

  11. Optical Sensor of Thermal Gas Flow Based on Fiber Bragg Grating.

    Science.gov (United States)

    Jiang, Xu; Wang, Keda; Li, Junqing; Zhan, Hui; Song, Zhenan; Che, Guohang; Lyu, Guohui

    2017-02-15

    This paper aims at solving the problem of explosion proof in measurement of thermal gas flow using electronic sensor by presenting a new type of flow sensor by optical fiber heating. A measuring unit based on fiber Bragg grating (FBG) for fluid temperature and a unit for heat dissipation are designed to replace the traditional electronic sensors. The light in C band from the amplified spontaneous emission (ASE) light source is split, with one part used to heat the absorbing coating and the other part used in the signal processing unit. In the heating unit, an absorbing coating is introduced to replace the traditional resistance heating module to minimize the risk of explosion. The measurement results demonstrate a fine consistency between the flow and temperature difference in simulation. The method to enhance the measurement resolution of flow is also discussed.

  12. Turbine exhaust diffuser with a gas jet producing a coanda effect flow control

    Science.gov (United States)

    Orosa, John; Montgomery, Matthew

    2014-02-11

    An exhaust diffuser system and method for a turbine engine includes an inner boundary and an outer boundary with a flow path defined therebetween. The inner boundary is defined at least in part by a hub structure that has an upstream end and a downstream end. The outer boundary may include a region in which the outer boundary extends radially inward toward the hub structure and may direct at least a portion of an exhaust flow in the diffuser toward the hub structure. The hub structure includes at least one jet exit located on the hub structure adjacent to the upstream end of the tail cone. The jet exit discharges a flow of gas substantially tangential to an outer surface of the tail cone to produce a Coanda effect and direct a portion of the exhaust flow in the diffuser toward the inner boundary.

  13. Strip distortion generator for simulating inlet flow distortion in gas turbine engine ground test facilities

    Directory of Open Access Journals (Sweden)

    M. Saleem Yusoof

    2016-12-01

    Full Text Available A methodology has been developed to generate a non-uniform/distorted inlet flow field to test a gas turbine engine in ground test facilities. The distorted flow field is generated by positioning radial and circumferential strips of varying widths upstream of the Aerodynamic Interface Plane. The interacting wakes from these strips are used to generate a given target flow field. The approximate superposition of these wakes is investigated and used to construct the strip arrangement which is subsequently validated by computing the flow field by solving the Navier–Stokes equations. The strip geometry designed using the present methodology is able to produce the target Mach number distribution with a root-mean-square error of 5.06%.

  14. Prediction of the bed-load transport by gas-liquid stratified flows in horizontal ducts

    CERN Document Server

    Franklin, Erick de Moraes

    2016-01-01

    Solid particles can be transported as a mobile granular bed, known as bed-load, by pressure-driven flows. A common case in industry is the presence of bed-load in stratified gas-liquid flows in horizontal ducts. In this case, an initially flat granular bed may be unstable, generating ripples and dunes. This three-phase flow, although complex, can be modeled under some simplifying assumptions. This paper presents a model for the estimation of some bed-load characteristics. Based on parameters easily measurable in industry, the model can predict the local bed-load flow rates and the celerity and the wavelength of instabilities appearing on the granular bed.

  15. 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.

  16. 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

    2016-11-01

    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.

  17. Control of Greenhouse Gas Emissions by Optimal DER Technology Investment and Energy Management in Zero-Net-Energy Buildings

    Energy Technology Data Exchange (ETDEWEB)

    Stadler, Michael; Siddiqui, Afzal; Marnay, Chris; Aki, Hirohisa; Lai, Judy

    2009-08-10

    The U.S. Department of Energy has launched the commercial building initiative (CBI) in pursuit of its research goal of achieving zero-net-energy commercial buildings (ZNEB), i.e. ones that produce as much energy as they use. Its objective is to make these buildings marketable by 2025 such that they minimize their energy use through cutting-edge, energy-efficiency technologies and meet their remaining energy needs through on-site renewable energy generation. This paper examines how such buildings may be implemented within the context of a cost- or CO2-minimizing microgrid that is able to adopt and operate various technologies: photovoltaic modules (PV) and other on-site generation, heat exchangers, solar thermal collectors, absorption chillers, and passive/demand-response technologies. A mixed-integer linear program (MILP) that has a multi-criteria objective function is used. The objective is minimization of a weighted average of the building's annual energy costs and CO2 emissions. The MILP's constraints ensure energy balance and capacity limits. In addition, constraining the building's energy consumed to equal its energy exports enables us to explore how energy sales and demand-response measures may enable compliance with the ZNEB objective. Using a commercial test site in northernCalifornia with existing tariff rates and technology data, we find that a ZNEB requires ample PV capacity installed to ensure electricity sales during the day. This is complemented by investment in energy-efficient combined heat and power (CHP) equipment, while occasional demand response shaves energy consumption. A large amount of storage is also adopted, which may be impractical. Nevertheless, it shows the nature of the solutions and costs necessary to achieve a ZNEB. Additionally, the ZNEB approach does not necessary lead to zero-carbon (ZC) buildings as is frequently argued. We also show a multi-objective frontier for the CA example, whichallows us to estimate the

  18. Signals features extraction in liquid-gas flow measurements using gamma densitometry. Part 1: time domain

    Directory of Open Access Journals (Sweden)

    Hanus Robert

    2016-01-01

    Full Text Available The paper presents an application of the gamma-absorption method to study a gas-liquid two-phase flow in a horizontal pipeline. In the tests on laboratory installation two 241Am radioactive sources and scintillation probes with NaI(Tl crystals have been used. The experimental set-up allows recording of stochastic signals, which describe instantaneous content of the stream in the particular cross-section of the flow mixture. The analyses of these signals by statistical methods allow to determine the mean velocity of the gas phase. Meanwhile, the selected features of signals provided by the absorption set, can be applied to recognition of the structure of the flow. In this work such three structures of air-water flow as: plug, bubble, and transitional plug – bubble one were considered. The recorded raw signals were analyzed in time domain and several features were extracted. It was found that following features of signals as the mean, standard deviation, root mean square (RMS, variance and 4th moment are most useful to recognize the structure of the flow.

  19. Physical understanding of gas-liquid annular flow and its transition to dispersed droplets

    Science.gov (United States)

    Kumar, Parmod; Das, Arup Kumar; Mitra, Sushanta K.

    2016-07-01

    Transformation from annular to droplet flow is investigated for co-current, upward gas-liquid flow through a cylindrical tube using grid based volume of fluid framework. Three transitional routes, namely, orificing, rolling, and undercutting are observed for flow transformation at different range of relative velocities between the fluids. Physics behind these three exclusive phenomena is described using circulation patterns of gaseous phase in the vicinity of a liquid film which subsequently sheds drop leading towards transition. Orifice amplitude is found to grow exponentially towards the core whereas it propagates in axial direction in a parabolic path. Efforts have been made to fit the sinusoidal profile of wave structure with the numerical interface contour at early stages of orificing. Domination of gas inertia over liquid flow has been studied in detail at the later stages to understand the asymmetric shape of orifice, leading towards lamella formation and droplet generation. Away from comparative velocities, circulations in the dominant phase dislodge the drop by forming either a ligament (rolling) or a bag (undercut) like protrusion in liquid. Study of velocity patterns in the plane of droplet dislodge reveals the underlying physics behind the disintegration and its dynamics at the later stages. Using numerical phase distributions, rejoining of dislodged droplet with liquid film as post-rolling consequences has been also proposed. A flow pattern map showing the transitional boundaries based on the physical mechanism is constructed for air-water combination.

  20. Effects of Gas Flow Rate on the Discharge Characteristics of a DC Excited Plasma Jet

    Science.gov (United States)

    Li, Xuechen; Jia, Pengying; Di, Cong; Bao, Wenting; Zhang, Chunyan

    2015-09-01

    A direct current (DC) source excited plasma jet consisting of a hollow needle anode and a plate cathode has been developed to form a diffuse discharge plume in ambient air with flowing argon as the working gas. Using optical and electrical methods, the discharge characteristics are investigated for the diffuse plasma plume. Results indicate that the discharge has a pulse characteristic, under the excitation of a DC voltage. The discharge pulse corresponds to the propagation process of a plasma bullet travelling from the anode to the cathode. It is found that, with an increment of the gas flow rate, both the discharge plume length and the current peak value of the pulsed discharge decrease in the laminar flow mode, reach their minima at about 1.5 L/min, and then slightly increase in the turbulent mode. However, the frequency of the pulsed discharge increases in the laminar mode with increasing the argon flow rate until the argon flow rate equals to about 1.5 L/min, and then slightly decreases in the turbulent mode. supported by National Natural Science Foundation of China (Nos. 10805013, 11375051), Funds for Distinguished Young Scientists of Hebei Province, China (No. A2012201045), Department of Education for Outstanding Youth Project of China (No. Y2011120), and Youth Project of Hebei University of China (No. 2011Q14)

  1. Potentiometric determination of total nitrogen in soils by flow injection analysis with a gas-diffusion unit

    OpenAIRE

    Ferreira, Alexandra M. R.; José L. F. C. Lima; Rangel,António O. S. S.

    1996-01-01

    A flow injection analysis (FIA) system incorporating a gas-diffusion unit and a potentiometric detector was developed for the determination of total nitrogen in soil digests. The solutions obtained from the Kjeldahl digestion of the soil samples were injected in the FIA system where ammonium was converted into ammonia. This gas diffused through a gas-permeable membrane to a buffer acceptor stream, allowing the separation of the gas from the rest of the sample. Once in contact with the buffer ...

  2. Application of spectral analysis in radiometric measurements of twophase liquid-gas flow

    Directory of Open Access Journals (Sweden)

    Zych Marcin

    2014-01-01

    Full Text Available This article presents use of the classical spectral analysis to identify a type of flow in investigation of gas transportation by liquid with a measurement of gamma radiation absorption. During numerous experiments it was found that a magnitude of the cross-spectral density distribution of recording signals reveals type of air-water mixture flow in a horizontal pipeline. As an example, some results of laboratory measurements equipped in 241Am radiation source and scintillation probes with of NaI(Tl crystals are presented. Moreover attached figures facilitate interpretation of observed results and in details illustrating the proposed method.

  3. Large concentration changes due to thermal diffusion effects in gas flow microsystems with temperature gradients

    DEFF Research Database (Denmark)

    Quaade, Ulrich; Johannessen, Tue; Jensen, Søren

    Thermal diffusion, or Sorét diffusion, is shown to cause significant concentration changes and transients in gas flow microsystems with temperature gradients. In a silicon microsystem, a temperature gradient of about 100 oC/mm is measured to produce concentration transients of up to 13.......7 % in an argon/helium mixture, when the flow is abruptly changed from a high value to a low value. Finite element simulations of the thermal diffusion in a geometry similar to the experimental setup reproduce the measurements....

  4. Prediction of gas-liquid two-phase flow regime in microgravity

    Science.gov (United States)

    Lee, Jinho; Platt, Jonathan A.

    1993-01-01

    An attempt is made to predict gas-liquid two-phase flow regime in a pipe in a microgravity environment through scaling analysis based on dominant physical mechanisms. Simple inlet geometry is adopted in the analysis to see the effect of inlet configuration on flow regime transitions. Comparison of the prediction with the existing experimental data shows good agreement, though more work is required to better define some physical parameters. The analysis clarifies much of the physics involved in this problem and can be applied to other configurations.

  5. Energy saving for OpenFlow switch on the NetFPGA platform based on queue engineering.

    Science.gov (United States)

    Vu, Tran Hoang; Luc, Vu Cong; Quan, Nguyen Trung; Thanh, Nguyen Huu; Nam, Pham Ngoc

    2015-01-01

    Data centers play an important role in our daily activities. The increasing demand on data centers in both scale and size has led to huge energy consumption that rises the cost of data centers. Besides, environmental impacts also increase considerably due to a large amount of carbon emissions. In this paper, we present a design aimed at green networking by reducing the power consumption for routers and switches. Firstly, we design the Balance Switch on the NetFPGA platform to save consumed energy based on Queue Engineering. Secondly, we design the test-bed system to precisely measure the consumed energy of our switches. Experimental results show that energy saving of our switches is about 30% - 35% of power consumption according to variation of input traffic compared with normal Openflow Switch. Finally, we describe performance evaluations.

  6. Dynamic behaviour of high-pressure natural-gas flow in pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Gato, L.M.C. [Department of Mechanical Engineering, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon (Portugal)]. E-mail: lgato@mail.ist.utl.pt; Henriques, J.C.C. [Department of Mechanical Engineering, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon (Portugal)]. E-mail: jcch@mail.ist.utl.pt

    2005-10-01

    The aim of the present study is the numerical modelling of the dynamic behaviour of high-pressure natural-gas flow in pipelines. The numerical simulation was performed by solving the conservation equations, for one-dimensional compressible flow, using the Runge-Kutta discontinuous Galerkin method, with third-order approximation in space and time. The boundary conditions were imposed using a new weak formulation based on the characteristic variables. The occurrence of pressure oscillations in natural-gas pipelines was studied as a result of the compression wave originated by the rapid closure of downstream shut-off valves. The effect of the partial reflection of pressure waves was also analyzed in the transition between pipes of different cross-sectional areas.

  7. Analysis of whole blood samples with low gas flow inductively coupled plasma-optical emission spectrometry.

    Science.gov (United States)

    Nowak, Sascha; Künnemeyer, Jens; Terborg, Lydia; Trümpler, Stefan; Günsel, Andreas; Wiesmüller, Gerhard A; Karst, Uwe; Buscher, Wolfgang

    2015-01-01

    Low gas flow ICP-OES with a total argon consumption below 0.7 L/min is introduced for the analysis of trace elements in blood samples to investigate the influence of samples containing an organic solvent in a demanding matrix on the performance of this plasma for the first time. Therefore, gadolinium was determined in human plasma samples and mercury in red blood cells, human plasma, and precipitated plasma protein fraction. Limits of detection (LOD) were determined to be in the low microgram per liter range for the analytes and the accuracy of the method was assessed by comparison with a conventional Fassel-type torch-based ICP-OES. It was proven that the low gas flow ICP-OES leads to comparable results with the instrument based on the Fassel-type torch.

  8. Simulation of Flow Behavior of Gas Condensate at Low Interfacial Tension

    DEFF Research Database (Denmark)

    Wang, Peng; Stenby, Erling Halfdan; Pope, Gary A.

    1996-01-01

    ) in the measurement, more attention is paid to the influence of IFT on gas/oil flow behavior. Two different types of model are used to compute the relative permeability. Model I is a Corey-type model combined with the capillary number concept. Model II is a modified form of the model proposed by Coats.The simulation...... results indicate that the effect of low IFT on relative permeability can be reasonably described by the two models selected, although the producing gas-oil ratio (GOR) obtained using Model I deviates somewhat from the experimental values in later depletion stages. The condensed liquid can be a mobile...... phase at very low liquid saturation, since the IFT is so low that the capillary force can be neglected. The liquid flows through the porous medium under the control of gra vity in this case....

  9. On boundary layer flow of a dusty gas from a horizontal circular cylinder

    Directory of Open Access Journals (Sweden)

    Rebhi A. Damseh

    2010-12-01

    Full Text Available The problem of flow of a viscous incompressible gas with dust particles across an isothermal cylinder is discussed. The dust particles are assumed to be uniformly distributed throughout the gas. The equations of motion are simplified by writing the equations in dimensionless form and then solved numerically to describe the flow for different values of the physical parameters of interest. These parameters are the particle concentration parameter (R, the temperature relaxation time parameter (A and the particle mass parameter (G. Many results are obtained and a representative set is displayed in graphs and tables. It is found that a distinct decrease in the velocity function is observed with an increase in the particle concentration parameter and increasing particle mass parameter induces a reduction in velocity. Furthermore, comparisons with previously published work are performed and the results are found to be in excellent agreement.

  10. The RealGas and RealGasH2O Options of the TOUGH+ Code for the Simulation of Coupled Fluid and Heat Flow in Tight/Shale Gas Systems

    Energy Technology Data Exchange (ETDEWEB)

    Moridis, George; Freeman, Craig

    2013-09-30

    We developed two new EOS additions to the TOUGH+ family of codes, the RealGasH2O and RealGas . The RealGasH2O EOS option describes the non-isothermal two-phase flow of water and a real gas mixture in gas reservoirs, with a particular focus in ultra-tight (such as tight-sand and shale gas) reservoirs. The gas mixture is treated as either a single-pseudo-component having a fixed composition, or as a multicomponent system composed of up to 9 individual real gases. The RealGas option has the same general capabilities, but does not include water, thus describing a single-phase, dry-gas system. In addition to the standard capabilities of all members of the TOUGH+ family of codes (fully-implicit, compositional simulators using both structured and unstructured grids), the capabilities of the two codes include: coupled flow and thermal effects in porous and/or fractured media, real gas behavior, inertial (Klinkenberg) effects, full micro-flow treatment, Darcy and non-Darcy flow through the matrix and fractures of fractured media, single- and multi-component gas sorption onto the grains of the porous media following several isotherm options, discrete and fracture representation, complex matrix-fracture relationships, and porosity-permeability dependence on pressure changes. The two options allow the study of flow and transport of fluids and heat over a wide range of time frames and spatial scales not only in gas reservoirs, but also in problems of geologic storage of greenhouse gas mixtures, and of geothermal reservoirs with multi-component condensable (H2O and CH4) and non-condensable gas mixtures. The codes are verified against available analytical and semi-analytical solutions. Their capabilities are demonstrated in a series of problems of increasing complexity, ranging from isothermal flow in simpler 1D and 2D conventional gas reservoirs, to non-isothermal gas flow in 3D fractured shale gas reservoirs involving 4 types of fractures, micro-flow, non-Darcy flow and gas

  11. Wire-mesh and ultrasound techniques applied for the characterization of gas-liquid slug flow

    Energy Technology Data Exchange (ETDEWEB)

    Ofuchi, Cesar Y.; Sieczkowski, Wytila Chagas; Neves Junior, Flavio; Arruda, Lucia V.R.; Morales, Rigoberto E.M.; Amaral, Carlos E.F.; Silva, Marco J. da [Federal University of Technology of Parana, Curitiba, PR (Brazil)], e-mails: ofuchi@utfpr.edu.br, wytila@utfpr.edu.br, neves@utfpr.edu.br, lvrarruda@utfpr.edu.br, rmorales@utfpr.edu.br, camaral@utfpr.edu.br, mdasilva@utfpr.edu.br

    2010-07-01

    Gas-liquid two-phase flows are found in a broad range of industrial applications, such as chemical, petrochemical and nuclear industries and quite often determine the efficiency and safety of process and plants. Several experimental techniques have been proposed and applied to measure and quantify two-phase flows so far. In this experimental study the wire-mesh sensor and an ultrasound technique are used and comparatively evaluated to study two-phase slug flows in horizontal pipes. The wire-mesh is an imaging technique and thus appropriated for scientific studies while ultrasound-based technique is robust and non-intrusive and hence well suited for industrial applications. Based on the measured raw data it is possible to extract some specific slug flow parameters of interest such as mean void fraction and characteristic frequency. The experiments were performed in the Thermal Sciences Laboratory (LACIT) at UTFPR, Brazil, in which an experimental two-phase flow loop is available. The experimental flow loop comprises a horizontal acrylic pipe of 26 mm diameter and 9 m length. Water and air were used to produce the two phase flow under controlled conditions. The results show good agreement between the techniques. (author)

  12. Comparison of analytic models of instability of rarefied gas flow in a channel

    Energy Technology Data Exchange (ETDEWEB)

    Aksenova, Olga A. [St.-Petersburg State University, Department of Mathematics and Mechanics, 198504, Universitetskiy pr., 28, Peterhof, St.-Petersburg (Russian Federation); Khalidov, Iskander A. [St.-Petersburg State Polytechnic University, Department of Mathematics and Mechanics, 195251, Polytechnicheskaya ul., 29, St.-Petersburg (Russian Federation)

    2014-12-09

    Numerical and analytical results are compared concerning the limit properties of the trajectories, attractors and bifurcations of rarefied gas flows in channels. The cascade of bifurcations obtained in our previous analytical and numerical investigations is simulated numerically for different scattering functions V generalizing the ray-diffuse reflection of gas particles from the surface. The main purpose of numerical simulation by Monte Carlo method is the investigation of the properties of different analytic nonlinear dynamic systems corresponding to rarefied gas flow in a channel. The results are compared as well for the models suggested originally by R. N. Miroshin, as for the approximations considered for the first time or for studied in our subsequent papers. Analytical solutions we obtained earlier for the ray reflection which means only one determined velocity of scattered from the walls gas atoms, generally different from the specular reflection. The nonlinear iterative equation describing a rarefied gas flow in a long channel becomes unstable in some regions of corresponding parameters of V (it means the sensitivity to boundary conditions). The values of the parameters are found from analytical approximations in these regions. Numerical results show that the chaotic behavior of the nonlinear dynamic system corresponds to strange attractors and distinguishes clearly from Maxwellian distribution and from the equilibrium on the whole. In the regions of instability (as the dimension of the attractor increases) the search for a corresponding state requires a lot more computation time and a lot of data (the amount of data required increases exponentially with embedding dimension). Therefore the main complication in the computation is reducing as well the computing time as the amount of data to find a suitably close solution. To reduce the computing time our analytical results are applied. Flow conditions satisfying the requirements to the experiment are

  13. Optimization of liquid and gas flow rates for aerated drilling fluids considering hole cleaning for vertical and low inclination wells

    Energy Technology Data Exchange (ETDEWEB)

    Ozbayoglu, M.E. [Middle East Univ., Metn (Lebanon)

    2009-07-01

    One of the most widely used technologies in depleted and/or low pressured formations is underbalanced drilling. Drilling fluids are usually gasified in order to achieve underbalanced conditions. The most commonly used drilling fluids during underbalanced drilling are pure gas, gas-liquid mixtures, and foams. This paper presented a study that focused on gas-liquid mixtures. The purpose of this paper was to express two-phase flow in vertical wellbores, and determine required flow rates for liquid and gas phase by considering formation pressure and hole cleaning properties. It was assumed that the liquid phase is the major contributor for cuttings transport, and that the gas phase only influences the bottom hole pressure. The paper introduced a mechanistic model for estimating the hydraulic behaviour of gas-liquid mixture drilling fluids under different flow patterns. Based on the bottom hole pressure and effective hole cleaning point of view, an algorithm was proposed for estimating the optimum required flow rates for liquid and gas phases based on the introduced mechanistic model. The model also predicts the required backpressure that must be applied. It was concluded that since the liquid flow rate is only dependent on proper hole cleaning, gas flow rate can be adjusted to achieve a bottomhole pressure equal to formation pressure. Also, backpressure should not be kept constant at the same value for static and dynamic conditions. Otherwise, bottomhole pressure cannot be kept constant. 14 refs., 9 figs., 1 appendix.

  14. A review of bias flow liners for acoustic damping in gas turbine combustors

    Science.gov (United States)

    Lahiri, C.; Bake, F.

    2017-07-01

    The optimized design of bias flow liner is a key element for the development of low emission combustion systems in modern gas turbines and aero-engines. The research of bias flow liners has a fairly long history concerning both the parameter dependencies as well as the methods to model the acoustic behaviour of bias flow liners under the variety of different bias and grazing flow conditions. In order to establish an overview over the state of the art, this paper provides a comprehensive review about the published research on bias flow liners and modelling approaches with an extensive study of the most relevant parameters determining the acoustic behaviour of these liners. The paper starts with a historical description of available investigations aiming on the characterization of the bias flow absorption principle. This chronological compendium is extended by the recent and ongoing developments in this field. In a next step the fundamental acoustic property of bias flow liner in terms of the wall impedance is introduced and the different derivations and formulations of this impedance yielding the different published model descriptions are explained and compared. Finally, a parametric study reveals the most relevant parameters for the acoustic damping behaviour of bias flow liners and how this is reflected by the various model representations. Although the general trend of the investigated acoustic behaviour is captured by the different models fairly well for a certain range of parameters, in the transition region between the resonance dominated and the purely bias flow related regime all models lack the correct damping prediction. This seems to be connected to the proper implementation of the reactance as a function of bias flow Mach number.

  15. Investigation of advanced propulsion technologies: The RAM accelerator and the flowing gas radiation heater

    Science.gov (United States)

    Bruckner, A. P.; Knowlen, C.; Mattick, A. T.; Hertzberg, A.

    1992-01-01

    The two principal areas of advanced propulsion investigated are the ram accelerator and the flowing gas radiation heater. The concept of the ram accelerator is presented as a hypervelocity launcher for large-scale aeroballistic range applications in hypersonics and aerothermodynamics research. The ram accelerator is an in-bore ramjet device in which a projectile shaped like the centerbody of a supersonic ramjet is propelled in a stationary tube filled with a tailored combustible gas mixture. Combustion on and behind the projectile generates thrust which accelerates it to very high velocities. The acceleration can be tailored for the 'soft launch' of instrumented models. The distinctive reacting flow phenomena that have been observed in the ram accelerator are relevant to the aerothermodynamic processes in airbreathing hypersonic propulsion systems and are useful for validating sophisticated CFD codes. The recently demonstrated scalability of the device and the ability to control the rate of acceleration offer unique opportunities for the use of the ram accelerator as a large-scale hypersonic ground test facility. The flowing gas radiation receiver is a novel concept for using solar energy to heat a working fluid for space power or propulsion. Focused solar radiation is absorbed directly in a working gas, rather than by heat transfer through a solid surface. Previous theoretical analysis had demonstrated that radiation trapping reduces energy loss compared to that of blackbody receivers, and enables higher efficiencies and higher peak temperatures. An experiment was carried out to measure the temperature profile of an infrared-active gas and demonstrate the effect of radiation trapping. The success of this effort validates analytical models of heat transfer in this receiver, and confirms the potential of this approach for achieving high efficiency space power and propulsion.

  16. Origin of three-dimensional shapes of chondrules. I. Hydrodynamics simulations of rotating droplet exposed to high-velocity rarefied gas flow

    Science.gov (United States)

    Miura, Hitoshi; Nakamoto, Taishi; Doi, Masao

    2008-09-01

    The origin of three-dimensional shapes of chondrules is an important information to identify their formation mechanism in the early solar nebula. The measurement of their shapes by using X-ray computed topography suggested that they are usually close to perfect spheres, however, some of them have rugby-ball-like (prolate) shapes [Tsuchiyama, A., Shigeyoshi, R., Kawabata, T., Nakano, T., Uesugi, K., Shirono, S., 2003. Lunar Planet. Sci. 34, 1271-1272]. We considered that the prolate shapes reflect the deformations of chondrule precursor dust particles when they are heated and melted in the high velocity gas flow. In order to reveal the origin of chondrule shapes, we carried out the three-dimensional hydrodynamics simulations of a rotating molten chondrule exposed to the gas flow in the framework of the shock-wave heating model for chondrule formation. We adopted the gas ram pressure acting on the chondrule surface of p=10 dyncm in a typical shock wave. Considering that the chondrule precursor dust particle has an irregular shape before melting, the ram pressure causes a net torque to rotate the particle. The estimated angular velocity is ω=140 rads for the precursor radius of r=1 mm, though it has a different value depending on the irregularity of the shape. In addition, the rotation axis is likely to be perpendicular to the direction of the gas flow. Our calculations showed that the rotating molten chondrule elongates along the rotation axis, in contrast, shrinks perpendicularly to it. It is a prolate shape. The reason why the molten chondrule is deformed to a prolate shape was clearly discussed. Our study gives a complementary constraint for chondrule formation mechanisms, comparing with conventional chemical analyses and dynamic crystallization experiments that have mainly constrained the thermal evolutions of chondrules.

  17. Effect of RF power and gas flow ratio on the growth and morphology ...

    Indian Academy of Sciences (India)

    Therefore, in this present study, thicker SiC thin films were deposited by PECVD process by using CH4 and SiH4 as the precursor gases in the presence of Ar as the carrier gas and two process parameters, i.e., radio frequency (RF) power with mixed frequency condition and flow ratio of silane to methane were varied by ...

  18. A Wall-Function Approach to Incorporating Knudsen-Layer Effects in Gas Micro Flow Simulations

    Science.gov (United States)

    2005-07-13

    conditions, such as those due to Kogan [3] and Cercignani [4], attempt to compensate for the structure of the Knudsen layer by adding a “fictitious...restrict our attention to its effect on the stress/strain relationship. For a planar wall bounding a monatomic gas flow, Cercignani derived the form of...curve-fitted approximation to the velocity correction function, I(x/λ) (obtained numerically by Cercignani ) as follows: 2 1 20 7

  19. Velocity measurements of the liquid - gas flow using gamma absorption and modified conditional averaging

    Directory of Open Access Journals (Sweden)

    Hanus Robert

    2015-01-01

    Full Text Available The paper presents idea and an exemplary application of gamma-absorption in the measurement of gas bubbles transportation in a gas-liquid mixture flow through a horizontal pipeline. In the tests on laboratory installation two 241Am radioactive sources and probes with NaI(Tl scintillation crystals have been used. For analysis of electrical signals obtained from detectors the modified conditional averaging of the absolute value of delayed signal (CAAV is proposed. The proposed method is based on the quotient of classical cross-correlation (CCF and CAAV. Results of the time delay estimation and gas-phase velocity measurements are compared with one obtained using CCF. The combined uncertainties of the mean velocity of air bubbles evaluation in the presented experiment did not exceed 2.1% (CCF and 1.7% (CCF/CAAV, which is a satisfactory result in industrial applications.

  20. Prediction Interval Construction for Byproduct Gas Flow Forecasting Using Optimized Twin Extreme Learning Machine

    Directory of Open Access Journals (Sweden)

    Xueying Sun

    2017-01-01

    Full Text Available Prediction of byproduct gas flow is of great significance to gas system scheduling in iron and steel plants. To quantify the associated prediction uncertainty, a two-step approach based on optimized twin extreme learning machine (ELM is proposed to construct prediction intervals (PIs. In the first step, the connection weights of the twin ELM are pretrained using a pair of symmetric weighted objective functions. In the second step, output weights of the twin ELM are further optimized by particle swarm optimization (PSO. The objective function is designed to comprehensively evaluate PIs based on their coverage probability, width, and deviation. The capability of the proposed method is validated using four benchmark datasets and two real-world byproduct gas datasets. The results demonstrate that the proposed approach constructs higher quality prediction intervals than the other three conventional methods.

  1. Heat Transfer and Pressure Drop in Concentric Annular Flows of Binary Inert Gas Mixtures

    Science.gov (United States)

    Reid, R. S.; Martin, J. J.; Yocum, D. J.; Stewart, E. T.

    2007-01-01

    Studies of heat transfer and pressure drop of binary inert gas mixtures flowing through smooth concentric circular annuli, tubes with fully developed velocity profiles, and constant heating rate are described. There is a general lack of agreement among the constant property heat transfer correlations for such mixtures. No inert gas mixture data exist for annular channels. The intent of this study was to develop highly accurate and benchmarked pressure drop and heat transfer correlations that can be used to size heat exchangers and cores for direct gas Brayton nuclear power plants. The inside surface of the annular channel is heated while the outer surface of the channel is insulated. Annulus ratios range 0.5 spacer ribs, or other surfaces.

  2. Multi Parameter Flow Meter for On-Line Measurement of Gas Mixture Composition

    Directory of Open Access Journals (Sweden)

    Egbert van der Wouden

    2015-04-01

    Full Text Available In this paper we describe the development of a system and model to analyze the composition of gas mixtures up to four components. The system consists of a Coriolis mass flow sensor, density, pressure and thermal flow sensor. With this system it is possible to measure the viscosity, density, heat capacity and flow rate of the medium. In a next step the composition can be analyzed if the constituents of the mixture are known. This makes the approach universally applicable to all gasses as long as the number of components does not exceed the number of measured properties and as long as the properties are measured with a sufficient accuracy. We present measurements with binary and ternary gas mixtures, on compositions that range over an order of magnitude in value for the physical properties. Two platforms for analyses are presented. The first platform consists of sensors realized with MEMS fabrication technology. This approach allows for a system with a high level of integration. With this system we demonstrate a proof of principle for the analyses of binary mixtures with an accuracy of 10%. In the second platform we utilize more mature steel sensor technology to demonstrate the potential of this approach. We show that with this technique, binary mixtures can be measured within 1% and ternary gas mixtures within 3%.

  3. Wave Structure and Velocity Profiles in Downwards Gas-Liquid Annular Flows

    Science.gov (United States)

    Zadrazil, Ivan; Hewitt, Geoff; Matar, Omar; Markides, Christos

    2012-11-01

    A downwards flow of gas in the core of a vertical pipe, and of liquid in the annulus between the pipe wall and the gas phase is referred to as a ``downwards annular flow'' (DAF). DAFs are conventionally described in terms of short-lived, small-amplitude ``ripples,'' and large-amplitude, high-speed ``disturbances.'' We use a combination of Laser Induced Fluorescence (LIF), Particle Image and Tracking Velocimetry (PIV, PTV) to study DAFs. We demonstrate through these techniques that the liquid films become progressively more complex with increasing liquid Reynolds number (ReL), while a similar increase of complexity is observed for increasing gas Reynolds number (ReG). Disturbance waves are observed for low and high ReL, and ripples for intermediate ReL. Additionally, a high degree of rolling breakdown of disturbance waves is observed in falling films at the highest ReL, which is a source of bubble entrainment into the film body. Our results will comprise: (i) statistical data on film thickness, and (ii) wave frequency, velocity, wavelength. In addition, a qualitative (e.g. re-circulation zones) and quantitative (e.g. mean/rms velocity profiles) velocity characterisation of the film flows will be presented.

  4. Thin liquid films with time-dependent chemical reactions sheared by an ambient gas flow

    Science.gov (United States)

    Bender, Achim; Stephan, Peter; Gambaryan-Roisman, Tatiana

    2017-08-01

    Chemical reactions in thin liquid films are found in many industrial applications, e.g., in combustion chambers of internal combustion engines where a fuel film can develop on pistons or cylinder walls. The reactions within the film and the turbulent outer gas flow influence film stability and lead to film breakup, which in turn can lead to deposit formation. In this work we examine the evolution and stability of a thin liquid film in the presence of a first-order chemical reaction and under the influence of a turbulent gas flow. Long-wave theory with a double perturbation analysis is used to reduce the complexity of the problem and obtain an evolution equation for the film thickness. The chemical reaction is assumed to be slow compared to film evolution and the amount of reactant in the film is limited, which means that the reaction rate decreases with time as the reactant is consumed. A linear stability analysis is performed to identify the influence of reaction parameters, material properties, and environmental conditions on the film stability limits. Results indicate that exothermic reactions have a stabilizing effect whereas endothermic reactions destabilize the film and can lead to rupture. It is shown that an initially unstable film can become stable with time as the reaction rate decreases. The shearing of the film by the external gas flow leads to the appearance of traveling waves. The shear stress magnitude has a nonmonotonic influence on film stability.

  5. Flow transport and gas mixing during invasive high frequency oscillatory ventilation.

    Science.gov (United States)

    Alzahrany, Mohammed; Banerjee, Arindam; Salzman, Gary

    2014-06-01

    A large Eddy simulation (LES) based computational fluid dynamics study was performed to investigate gas transport and mixing in patient specific human lung models during high frequency oscillatory ventilation. Different pressure-controlled waveforms (sinusoidal, exponential and square) and ventilator frequencies (15, 10 and 6Hz) were used (tidal volume=50mL). The waveforms were created by solving the equation of motion subjected to constant lung wall compliance and flow resistance. Simulations were conducted with and without endotracheal tube to understand the effect of invasive management device. Variation of pressure-controlled waveform and frequency exhibits significant differences on counter flow pattern, which could lead to a significant impact on the gas mixing efficiency. Pendelluft-like flow was present for the sinusoidal waveform at all frequencies but occurred only at early inspiration for the square waveform at highest frequency. The square waveform was most efficient for gas mixing, resulting in the least wall shear stress on the lung epithelium layer thereby reducing the risk of barotrauma to both airways and the alveoli for patients undergoing therapy. Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.

  6. Energy policy act transportation study: Interim report on natural gas flows and rates

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-11-17

    This report, Energy Policy Act Transportation Study: Interim Report on Natural Gas Flows and Rates, is the second in a series mandated by Title XIII, Section 1340, ``Establishment of Data Base and Study of Transportation Rates,`` of the Energy Policy Act of 1992 (P.L. 102--486). The first report Energy Policy Act Transportation Study: Availability of Data and Studies, was submitted to Congress in October 1993; it summarized data and studies that could be used to address the impact of legislative and regulatory actions on natural gas transportation rates and flow patterns. The current report presents an interim analysis of natural gas transportation rates and distribution patterns for the period from 1988 through 1994. A third and final report addressing the transportation rates and flows through 1997 is due to Congress in October 2000. This analysis relies on currently available data; no new data collection effort was undertaken. The need for the collection of additional data on transportation rates will be further addressed after this report, in consultation with the Congress, industry representatives, and in other public forums.

  7. Net land-atmosphere flows of biogenic carbon related to bioenergy: towards an understanding of systemic feedbacks.

    Science.gov (United States)

    Haberl, Helmut

    2013-07-01

    The notion that biomass combustion is carbon neutral vis-a-vis the atmosphere because carbon released during biomass combustion is absorbed during plant regrowth is inherent in the greenhouse gas accounting rules in many regulations and conventions. But this 'carbon neutrality' assumption of bioenergy is an oversimplification that can result in major flaws in emission accounting; it may even result in policies that increase, instead of reduce, overall greenhouse gas emissions. This commentary discusses the systemic feedbacks and ecosystem succession/land-use history issues ignored by the carbon neutrality assumption. Based on recent literature, three cases are elaborated which show that the C balance of bioenergy may range from highly beneficial to strongly detrimental, depending on the plants grown, the land used (including its land-use history) as well as the fossil energy replaced. The article concludes by proposing the concept of GHG cost curves of bioenergy as a means for optimizing the climate benefits of bioenergy policies.

  8. Effects of gas temperature on nozzle damping experiments on cold-flow rocket motors

    Science.gov (United States)

    Sun, Bing-bing; Li, Shi-peng; Su, Wan-xing; Li, Jun-wei; Wang, Ning-fei

    2016-09-01

    In order to explore the impact of gas temperature on the nozzle damping characteristics of solid rocket motor, numerical simulations were carried out by an experimental motor in Naval Ordnance Test Station of China Lake in California. Using the pulse decay method, different cases were numerically studied via Fluent along with UDF (User Defined Functions). Firstly, mesh sensitivity analysis and monitor position-independent analysis were carried out for the computer code validation. Then, the numerical method was further validated by comparing the calculated results and experimental data. Finally, the effects of gas temperature on the nozzle damping characteristics were studied in this paper. The results indicated that the gas temperature had cooperative effects on the nozzle damping and there had great differences between cold flow and hot fire test. By discussion and analysis, it was found that the changing of mainstream velocity and the natural acoustic frequency resulted from gas temperature were the key factors that affected the nozzle damping, while the alteration of the mean pressure had little effect. Thus, the high pressure condition could be replaced by low pressure to reduce the difficulty of the test. Finally, the relation of the coefficients "alpha" between the cold flow and hot fire was got.

  9. MODELING OF DIESEL- COMPRESSED NATURAL GAS BUBBLY FLOW UNDER INFLUENCING OF A MAGNETIC FIELD

    Directory of Open Access Journals (Sweden)

    HASANAIN A. ABDULWAHHAB

    2017-07-01

    Full Text Available Numerical simulation of a single compressed natural gas bubble in diesel flow with effecting magnetic flux is presented in this paper. The three dimensional incompressible Navier-Stokes equations have been used to solve the Diesel and compressed natural gas laminar two phase flow in horizontal pipe. The simulation was carried out using COMSOL Multiphysic software version 4.4, Level-Set method. The interface between the gaseous and liquid phases was described as the zero level set of a smooth function. The results showed that compressed natural gas bubble under magnetic field grow up vertically to have bigger elliptical shape in the Diesel phase, doubling in diameter before it breaks away in two parts of 0.2 and 0.8 tesla. Also, it has been noted that the compressed natural gas bubble velocity is decreasing as the magnetic field is strengthening. The numerical procedure has been validated by comparing the computational results with experimental results reported in the literature where a good agreement was achieved.

  10. Transient flow in pipelines of high-pressure hydrogen-natural gas mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Elaoud, Sami; Hadj-Taieb, Ezzeddine [Unit of Applied Fluid Mechanics and Modeling, ENIS, Sokra Road Km 4, P.O. Box W, Sfax 3038 (Tunisia)

    2008-09-15

    The purpose of this study is the numerical modeling of high-pressure transient flow of hydrogen-natural gas mixtures in rigid pipelines. The governing equations for such flows are two coupled, non-linear, hyperbolic, partial differential equations. The fluid pressure and velocity are considered as two principal dependent variables. The fluid is a homogeneous hydrogen-natural gas mixture for which the density is defined by an expression averaging the two gas densities where a polytropic process is admitted for the two components. The hydrogen-mixture mass ratio (or quality), assumed to be constant, is used in the mathematical formulation, instead of the void fraction which varies with pressure. The problem has been solved by the non-linear method of characteristics and the finite difference conservative method. To verify their validity, the computed results of the two numerical methods are compared for different values of the quality. The occurrence of pressure oscillations in hydrogen-natural gas mixture pipelines was studied as a result of the compression wave created by a rapid closure of downstream shut-off valve. (author)

  11. Short-term gas dispersion in idealised urban canopy in street parallel with flow direction

    Directory of Open Access Journals (Sweden)

    Chaloupecká Hana

    2016-01-01

    Full Text Available Chemical attacks (e.g. Syria 2014-15 chlorine, 2013 sarine or Iraq 2006-7 chlorine as well as chemical plant disasters (e.g. Spain 2015 nitric oxide, ferric chloride; Texas 2014 methyl mercaptan threaten mankind. In these crisis situations, gas clouds are released. Dispersion of gas clouds is the issue of interest investigated in this paper. The paper describes wind tunnel experiments of dispersion from ground level point gas source. The source is situated in a model of an idealised urban canopy. The short duration releases of passive contaminant ethane are created by an electromagnetic valve. The gas cloud concentrations are measured in individual places at the height of the human breathing zone within a street parallel with flow direction by Fast-response Ionisation Detector. The simulations of the gas release for each measurement position are repeated many times under the same experimental set up to obtain representative datasets. These datasets are analysed to compute puff characteristics (arrival, leaving time and duration. The results indicate that the mean value of the dimensionless arrival time can be described as a growing linear function of the dimensionless coordinate in the street parallel with flow direction where the gas source is situated. The same might be stated about the dimensionless leaving time as well as the dimensionless duration, however these fits are worse. Utilising a linear function, we might also estimate some other statistical characteristics from datasets than the datasets means (medians, trimeans. The datasets of the dimensionless arrival time, the dimensionless leaving time and the dimensionless duration can be fitted by the generalized extreme value distribution (GEV in all sampling positions except one.

  12. Anode-pore tortuosity in solid oxide fuel cells found from gas and current flow rates

    Science.gov (United States)

    Schmidt, V. Hugo; Tsai, Chih-Long

    The effect of solid oxide fuel cell (SOFC) anode thickness, porosity, pore size, and pore tortuosity on fuel and exhaust gas flow is calculated. Also determined is the concentration of these gases and of diluent gases as a function of position across the anode. The calculation is based on the dusty-gas model which includes a Knudsen (molecule-wall) collision term in the Stefan-Maxwell equation which is based on unlike-molecule collisions. Commonly made approximations are avoided in order to obtain more exact results. One such approximation is the assumption of uniform total gas pressure across the anode. Another such approximation is the assumption of zero fuel gas concentration at the anode-electrolyte interface under the anode saturation condition for which the SOFC output voltage goes to zero. Elimination of this approximation requires use of a model we developed (published elsewhere) for terminal voltage V as a function of electrolyte current density i. Key formulae from this model are presented. The formulae developed herein for gas flow and tortuosity are applied to the results of a series of careful experiments performed by another group, who used binary and ternary gas mixtures on the anode side of an SOFC. Our values for tortuosity are in a physically reasonable low range, from 1.7 to 3.3. They are in fair agreement with those obtained by the other group, once a difference in nomenclature is taken into account. This difference consists in their definition of tortuosity being what some call tortuosity factor, which is the square of what we and some others call tortuosity. The results emphasize the need for careful design of anode pore structures, especially in anode-supported SOFCs which require thicker anodes.

  13. FUSE Observations of Warm Gas in the Cooling Flow Clusters A1795 and A2597

    Science.gov (United States)

    Oegerle, W. R.; Cowie, L.; Davidsen, A.; Hu, E.; Hutchings, J.; Murphy, E.; Sembach, K.; Woodgate, B.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    We present far-ultraviolet spectroscopy of the cores of the massive cooling flow clusters Abell 1795 and 2597 obtained with FUSE. As the intracluster gas cools through 3 x 10(exp 5)K, it should emit strongly in the O VI lambda(lambda)1032,1038 resonance lines. We report the detection of O VI (lambda)1032 emission in A2597, with a line flux of 1.35 +/- 0.35 x 10(exp -15) erg/sq cm s, as well as detection of emission from C III (lambda)977. A marginal detection of C III (lambda)977 emission is also reported for A1795. These observations provide evidence for a direct link between the hot (10(exp 7) K) cooling flow gas and the cool (10(exp 4) K) gas in the optical emission line filaments. Assuming simple cooling flow models, the O VI line flux in A2597 corresponds to a mass deposition rate of approx. 40 solar mass /yr within the central 36 kpc. Emission from O VI (lambda)1032 was not detected in A1795, with an upper limit of 1.5 x 10(exp -15) erg/sq cm s, corresponding to a limit on the mass cooling flow rate of M(28 kpc) less than 28M solar mass/ yr. We have considered several explanations for the lack of detection of O VI emission in A1795 and the weaker than expected flux in A2597, including extinction by dust in the outer cluster, and quenching of thermal conduction by magnetic fields. We conclude that a turbulent mixing model, with some dust extinction, could explain our O VI results while also accounting for the puzzling lack of emission by Fe(sub XVII) in cluster cooling flows.

  14. 3D CFD modeling of flowing-gas DPALs with different pumping geometries and various flow velocities

    Science.gov (United States)

    Yacoby, Eyal; Waichman, Karol; Sadot, Oren; Barmashenko, Boris D.; Rosenwaks, Salman

    2017-01-01

    Scaling-up flowing-gas diode pumped alkali lasers (DPALs) to megawatt class power is studied using accurate three-dimensional computational fluid dynamics model, taking into account the effects of temperature rise and losses of alkali atoms due to ionization. Both the maximum achievable power and laser beam quality are estimated for Cs and K lasers. We examined the influence of the flow velocity and Mach number M on the maximum achievable power of subsonic and supersonic lasers. For Cs DPAL devices with M = 0.2 - 3 the output power increases with increasing M by only 20%, implying that supersonic operation mode has only small advantage over subsonic. In contrast, the power achievable in K DPALs strongly depends on M. The output power increases by 100% when M increases from 0.2 to 4, showing a considerable advantage of supersonic device over subsonic. The reason for the increase of the power with M in both Cs and K DPALs is the decrease of the temperature due to the gas expansion in the flow system. However, the power increase for K lasers is much larger than for the Cs devices mainly due to the much smaller fine-structure splitting of the 2P states ( 58 cm-1 for K and 554 cm-1 for Cs), which results in a much stronger effect of the temperature decrease in K DPALs. For pumping by beams of the same rectangular cross section, comparison between end-pumping and transverse-pumping shows that the output power is not affected by the pump geometry. However, the intensity of the output laser beam in the case of transverse-pumped DPALs is strongly non-uniform in the laser beam cross section resulting in higher brightness and better beam quality in the far field for the end-pumping geometry where the intensity of the output beam is uniform.

  15. Net Locality

    DEFF Research Database (Denmark)

    de Souza e Silva, Adriana Araujo; Gordon, Eric

    Provides an introduction to the new theory of Net Locality and the profound effect on individuals and societies when everything is located or locatable. Describes net locality as an emerging form of location awareness central to all aspects of digital media, from mobile phones, to Google Maps...... of emerging technologies, from GeoCities to GPS, Wi-Fi, Wiki Me, and Google Android....

  16. Net Neutrality

    DEFF Research Database (Denmark)

    Savin, Andrej

    2017-01-01

    Repealing “net neutrality” in the US will have no bearing on Internet freedom or security there or anywhere else.......Repealing “net neutrality” in the US will have no bearing on Internet freedom or security there or anywhere else....

  17. Effects of tillage practices and straw returning methods on greenhouse gas emissions and net ecosystem economic budget in rice-wheat cropping systems in central China

    Science.gov (United States)

    Zhang, Z. S.; Guo, L. J.; Liu, T. Q.; Li, C. F.; Cao, C. G.

    2015-12-01

    Significant efforts have been devoted to assess the effects of conservation tillage (no-tillage [NT] and straw returning) on greenhouse gas (GHG) emissions, global warming potential (GWP), greenhouse gas intensity (GHGI), and net economic budget in crop growing seasons. However, only a few studies have evaluated the effects conservation tillage on the net ecosystem economic budget (NEEB) in a rice-wheat cropping system. Therefore, a split-plot field experiment was performed to comprehensively evaluate the effects of tillage practices (i.e., conventional intensive tillage [CT] and NT) and straw returning methods (i.e., straw returning or removal of preceding crop) on the soil total organic carbon (TOC), GHG emissions, GWP, GHGI, and NEEB of sandy loam soil in a rice-wheat cropping system in central China. Conservation tillage did not affect rice and wheat grain yields. Compared with CT and straw removal, NT and straw returning significantly increased the TOC of 0-5 cm soil layer by 2.9% and 7.8%, respectively. However, the TOC of 0-20 cm soil layer was not affected by tillage practices and straw returning methods. NT did not also affect the N2O emissions during the rice and wheat seasons; NT significantly decreased the annual CH4 emissions by 7.5% and the annual GWP by 7.8% compared with CT. Consequently, GHGI under NT was reduced by 8.1%. Similar to NT, straw returning did not affect N2O emissions during the rice and wheat seasons. Compared with straw removal, straw returning significantly increased annual CH4 emissions by 35.0%, annual GWP by 32.0%, and annual GHGI by 31.1%. Straw returning did not also affect NEEB; by contrast, NT significantly increased NEEB by 15.6%. NT without straw returning resulted in the lowest GWP, the lowest GHGI, and the highest NEEB among all treatments. This finding suggested that NT without straw returning may be applied as a sustainable technology to increase economic and environmental benefits. Nevertheless, environmentally straw

  18. Net global warming potential and greenhouse gas intensity in a double-cropping cereal rotation as affected by nitrogen and straw management

    Science.gov (United States)

    Huang, T.; Gao, B.; Christie, P.; Ju, X.

    2013-12-01

    The effects of nitrogen and straw management on global warming potential (GWP) and greenhouse gas intensity (GHGI) in a winter wheat-summer maize double-cropping system on the North China Plain were investigated. We measured nitrous oxide (N2O) emissions and studied net GWP (NGWP) and GHGI by calculating the net exchange of CO2 equivalent (CO2-eq) from greenhouse gas emissions, agricultural inputs and management practices, as well as changes in soil organic carbon (SOC), based on a long-term field experiment established in 2006. The field experiment includes six treatments with three fertilizer N levels (zero N (control), optimum and conventional N) and straw removal (i.e. N0, Nopt and Ncon) or return (i.e. SN0, SNopt and SNcon). Optimum N management (Nopt, SNopt) saved roughly half of the fertilizer N compared to conventional agricultural practice (Ncon, SNcon), with no significant effect on grain yields. Annual mean N2O emissions reached 3.90 kg N2O-N ha-1 in Ncon and SNcon, and N2O emissions were reduced by 46.9% by optimizing N management of Nopt and SNopt. Straw return increased annual mean N2O emissions by 27.9%. Annual SOC sequestration was 0.40-1.44 Mg C ha-1 yr-1 in plots with N application and/or straw return. Compared to the conventional N treatments the optimum N treatments reduced NGWP by 51%, comprising 25% from decreasing N2O emissions and 75% from reducing N fertilizer application rates. Straw return treatments reduced NGWP by 30% compared to no straw return because the GWP from increments of SOC offset the GWP from higher emissions of N2O, N fertilizer and fuel after straw return. The GHGI trends from the different nitrogen and straw management practices were similar to the NGWP. In conclusion, optimum N and straw return significantly reduced NGWP and GHGI and concomitantly achieved relatively high grain yields in this important winter wheat-summer maize double-cropping system.

  19. Net global warming potential and greenhouse gas intensity in a double cropping cereal rotation as affected by nitrogen and straw management

    Science.gov (United States)

    Huang, T.; Gao, B.; Christie, P.; Ju, X.

    2013-08-01

    The effects of nitrogen and straw management on global warming potential (GWP) and greenhouse gas intensity (GHGI) in a winter wheat-summer maize double-cropping system on the North China Plain were investigated. We measured nitrous oxide (N2O) emissions and studied net GWP (NGWP) and GHGI by calculating the net exchange of CO2 equivalent (CO2-eq) from greenhouse gas emissions, agricultural inputs and management practices, and changes in soil organic carbon (SOC), based on a long-term field experiment established in 2006. The field experiment includes six treatments with three fertilizer N levels (zero-N control, optimum and conventional N) and straw removal (i.e. N0, Nopt and Ncon) or return (i.e. N0, Nopt and SNcon). Optimum N management (Nopt, SNopt) saved roughly half of the fertilizer N compared to conventional agricultural practice (Ncon, SNcon) with no significant effect on grain yields. Annual mean N2O emissions reached 3.90 kg N2O-N ha-1 in Ncon and SNcon, and N2O emissions were reduced by 46.9% by optimizing N management of Nopt and SNopt. Straw return increased annual mean N2O emissions by 27.9%. Annual SOC sequestration was 0.40-1.44 Mg C ha-1 yr-1 in plots with N application and/or straw return. Compared to the conventional N treatments the optimum N treatments reduced NGWP by 51%, comprising 25% from decreasing N2O emissions and 75% from reducing N fertilizer application rates. Straw return treatments reduced NGWP by 30% compared to no straw return because the GWP from increments of SOC offset the GWP from higher emissions of N2O, N fertilizer and fuel after straw return. The GHGI trends from the different nitrogen and straw management practices were similar to the NGWP. In conclusion, optimum N and straw return significantly reduced NGWP and GHGI and concomitantly achieved relatively high grain yields in this important winter wheat-summer maize double-cropping system.

  20. Channel-width dependent pressure-driven flow characteristics of shale gas in nanopores

    Directory of Open Access Journals (Sweden)

    Jie Chen

    2017-04-01

    Full Text Available Understanding the flow characteristics of shale gas especially in nanopores is extremely important for the exploitation. Here, we perform molecular dynamics (MD simulations to investigate the hydrodynamics of methane in nanometre-sized slit pores. Using equilibrium molecular dynamics (EMD, the static properties including density distribution and self-diffusion coefficient of the confined methane are firstly analyzed. For a 6 nm slit pore, it is found that methane molecules in the adsorbed layer diffuse more slowly than those in the bulk. Using nonequilibrium molecular dynamics (NEMD, the pressure-driven flow behavior of methane in nanopores is investigated. The results show that velocity profiles manifest an obvious dependence on the pore width and they translate from parabolic flow to plug flow when the width is decreased. In relatively large pores (6 – 10 nm, the parabolic flow can be described by the Navier-Stokes (NS equation with appropriate boundary conditions because of its slip flow characteristic. Based on this equation, corresponding parameters such as viscosity and slip length are determined. Whereas, in small pores (∼ 2 nm, the velocity profile in the center exhibits a uniform tendency (plug flow and that near the wall displays a linear increase due to the enhanced mechanism of surface diffusion. Furthermore, the profile is analyzed and fitted by a piecewise function. Under this condition, surface diffusion is found to be the root of this anomalous flow characteristic, which can be negligible in large pores. The essential tendency of our simulation results may be significant for revealing flow mechanisms at nanoscale and estimating the production accurately.

  1. Effect of stratified inequality of blood flow on gas exchange in liquid-filled lungs.

    Science.gov (United States)

    West, J. B.; Maloney, J. E.; Castle, B. L.

    1972-01-01

    This investigation set out to answer two questions: (1) are the distal alveoli in the terminal lung units less well perfused than the proximal alveoli, i.e., is there stratification of blood flow; and (2) if so, does this enhance gas exchange in the presence of stratified inequality of ventilation. Excised dog lungs were ventilated with saline and perfused with blood. Following single inspirations of xenon 133 in saline and various periods of breath holding, the expired xenon concentration against volume was measured and it confirmed marked stratified inequality of ventilation under these conditions. By measuring the rate of depletion of xenon from alveoli during a period of blood flow, we showed that the alveoli which emptied at the end of expiration had 16% less blood flow than those exhaling earlier. However, by measuring the xenon concentration in pulmonary venous blood, we found that about 10% less tracer was transferred from the alveoli into the blood when the inspired xenon was stratified within the respiratory zone. Thus while stratification of blood flow was confirmed, it was shown to impair rather than enhance the efficiency of gas transfer.

  2. Steady flows of a highly rarefied gas induced by nonuniform wall temperature

    Science.gov (United States)

    Kosuge, Shingo; Aoki, Kazuo; Takata, Shigeru; Hattori, Ryosuke; Sakai, Daisuke

    2011-03-01

    Steady behavior of a rarefied gas between parallel plates with sinusoidal temperature distribution is investigated on the basis of the Boltzmann equation. The Cercignani-Lampis (CL) model or the Lord model for diffuse scattering with incomplete energy accommodation is adopted as the boundary condition on the plates. Most of the analysis is carried out numerically with special interest in the free-molecular limit. In the case of the CL model, the nonuniform temperature distribution of the plates may induce a steady free-molecular flow, which is in contrast with the earlier results for the Maxwell-type model [Y. Sone, J. Méc. Théor. Appl. 3, 315 (1984); J. Méc. Théor. Appl. 4, 1 (1985)]. This fact is confirmed through an accurate deterministic computation based on an integral equation. In addition, computations for a wide range of parameters by means of the direct simulation Monte Carlo method reveal that the flow field changes according to the accommodation coefficients and is classified into four types. The effect of intermolecular collisions on the flow is also examined. In the case of the Lord model, no steady flow of the free-molecular gas is induced as in the case of the Maxwell-type model. This result is extended to the case of a more general boundary condition that gives the cosine law (Lambert's law) for the reflected molecular flux.

  3. Gas Bubbles and Slugs Crossover in Air-Water Two-phase Flow by Multifractals

    Science.gov (United States)

    Gorski, Grzegorz; Litak, Grzegorz; Mosdorf, Romuald; Rysak, Andrzej

    2017-05-01

    Slugs and bubbles two-phase flow patterns dynamics in a minichannel are analysed. During the experiment, the volume flow rates of air and water were changed. We study transition of bubbles to slugs two-phase flow patterns using Fourier and multifractal approaches to optical transitivity signal. The sequences of light transmission time series are recorded by a laser-phototransistor sensor. Multifractal analysis helps to identify the two-phase structure and estimate the signal complexity. Especially, we discuss occurrence and identification of a self-aggregation phenomenon. These results are compared to corresponding Fourier spectra. The results indicate that the fractality is a an important factor influencing the distribution of the gas phase in water.

  4. GeoSteamNet: A computer code to simulate geothermal steam flow in a pipeline network; GeoSteamNet: Programa de computo para simular el flujo de vapor geotermico de una red de vaporductos

    Energy Technology Data Exchange (ETDEWEB)

    Verma P., Mahendra; Aragon A., Alfonso [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)]. E-mail: mahendra@iie.org.mx; Ruiz L., Alejando; Mendoza C., Alfredo [Comision Federal de Electricidad, Campo Geotermico Los Azufres, Campamento Agua Fria, Michoacan (Mexico)

    2011-07-15

    A computer package, GeoSteamNet, was developed to simulate steam transport in a pipeline network of a geothermal field. The fluid motion is governed by the following basic principles: conservation of mass, linear momentum principle (Newton's second law or the Navier Stokes equations), and the first and second laws of thermodynamics. The second law of thermodynamics defines the direction of a spontaneous process, which is indirectly validated in the algorithm as vapor flows from high-to-low pressure, and heat flows from high-to-low temperatures. The nonlinear equations are solved with the Newton-Raphson method. Using the ActiveX component OrificeMeter, the steam-flow balance was calculated for power plants U-15 and U-16 in Los Azufres Geothermal Field, Mich., in February 2009. U-15 was fed by the production wells AZ-04, AZ-28, AZ-30, AZ-65D, and AZ-66, whereas wells AZ-28A, AZ-45, AZ-56, AZ-67, AZ-69D were connected to U-16. The analytical error is within {+-}4%, which is acceptable for practical purposes for steam-supply management, considering the uncertainties in parameters, such as pressure, temperature, pressure fluctuation at the wellhead, etc. The steam simulation results by GeoSteamNet for a hypothetical-pipeline network in a geothermal system with two production wells and a power plant illustrate its functionality. Several points need to be emphasized. For a specific geometry-pipeline network, there is only a certain amount of mass (vapor) that can be transported at a given pressure at the wellheads and the power plant. The construction and modification of a pipeline network is very expensive and the production of geothermal wells depends on many natural factors; therefore, there is need to conduct a tolerance study for each component of the network. A simulation study of the virtual-pipeline network for the design of a geothermal power plant can save money, effort, and time. [Spanish] Se desarrollo un paquete de computo, GeoSteamNet, para simular el

  5. Determination of cholesterol and triglycerides in serum lipoproteins using flow field-flow fractionation coupled to gas chromatography-mass spectrometry

    NARCIS (Netherlands)

    Qureshi, R.N.; Kaal, E.; Janssen, H.-G.; Schoenmakers, P.J.; Kok, W.Th.

    2011-01-01

    Asymmetric flow field flow fractionation (AsFlFFF) was combined with pyrolysis-gas chromatography mass spectrometry for a sized based fractionation and a detailed compositional study of the triglycerides and cholesterol associated with the various lipoprotein subclasses present in human serum. Serum

  6. Assessment of gas-surface interaction models for computation of rarefied hypersonic flows

    Science.gov (United States)

    Padilla, Jose Fernando

    Over the next few decades, spaceflight is expected to become more common through the resurgence of manned space exploration and the rise of commercial manned spaceflight. An essential role for the efficient research and development of suborbital spaceflight is played by computational simulation of rarefied hypersonic flows. Among the few classes of computational approaches for examining rarefied gas dynamics, the most widely used approach, for spatial scales relevant to suborbital spaceflight, is the direct simulation Monte Carlo (DSMC) method. Although the DSMC method has been under development for over forty years, there are still many areas where improvements can be made. One particular area is the associated numerical modeling of interactions between gas molecules and solid surfaces. Gas-surface interactions are not well understood for rarefied hypersonic conditions, although various models have been developed. This thesis ultimately focuses on assessing two common gas-surface interaction models in use with the DSMC method, the Maxwell model and the Cercignani, Lampis and Lord (CLL) model. In the search for a definitive thesis goal and as a consequence of the analysis tools developed for achieving the definitive thesis goal, several aspects of DSMC analysis are examined. Initially, procedures to determine aerodynamic coefficients from DSMC simulations are validated against certain windtunnel test data and an independent DSMC code. Then, sensitivity studies are performed involving aerothermodynamics predictions for the Apollo 6, at the 110 km altitude return trajectory point. This reveals the significance of gas-surface surface interaction models in rarefied hypersonic flows. A review of existing gas-surface interaction models motivates the assessment of the Maxwell and CLL models. The two models are scrutinized with the help of relatively recent windtunnel test measurements and procedures to extract surface scattering distributions. Both models yield similar

  7. Numerical investigation of oxygen impurity distribution during multicrystalline silicon crystal growth using a gas flow guidance device

    Science.gov (United States)

    Teng, Ying-Yang; Chen, Jyh-Chen; Lu, Chung-Wei; Chen, Chi-Yung

    2012-12-01

    Oxygen is one of the most important types of impurities that can cause thermal donor or light-induced degradation in mc-Si solar cells. The objective of this study is to investigate the effect that installing a gas flow guidance device in a mc-Si crystal-growth furnace would have on the oxygen impurity distribution in the melt during the growth process. The installation of such a gas flow guidance device can enhance the gas flow near the free surface, which would allow the argon to carry a greater amount of evaporated SiO gas outside the furnace. Furthermore, the enhanced motion of the gas flow also improves heat transfer near the free surface, which would make the melt vortex separate more easily. The separated melt vortex, which is located near the central region of the melt-crystal interface, directs any oxygen impurity towards the central region of the melt-crystal interface. This is why the oxygen concentration can be reduced by installing the gas flow guidance device. The effectiveness of the gas flow guidance device depends on the vertical distance between it and the free surface (h) as well as the gap between the crucible sidewall and the tip of the device (d). The effect on the oxygen concentration in the melt is significant when smaller values for h and d are adopted.

  8. Resolving Gas Flows in the Ultraluminous Starburst IRAS 23365+3604 with Keck LGSAO/OSIRIS

    Science.gov (United States)

    Martin, Crystal L.; Soto, Kurt T.

    2016-03-01

    Keck OSIRIS/LGSAO observations of the ultraluminous galaxy IRAS 23365+3604 resolve a circumnuclear bar (or irregular disk) of semimajor axis 0.″42 (520 pc) in Paα emission. The line-of-sight velocity of the ionized gas increases from the northeast toward the southwest; this gradient is perpendicular to the photometric major axis of the infrared emission. Two pairs of bends in the zero-velocity line are detected. The inner bend provides evidence for gas inflow onto the circumnuclear disk/bar structure. We interpret the gas kinematics on kiloparsec scales in relation to the molecular gas disk and multiphase outflow discovered previously. In particular, the fast component of the ouflow (detected previously in line wings) is not detected, adding support to the conjecture that the fast wind originates well beyond the nucleus. These data directly show the dynamics of gas inflow and outflow in the central kiloparsec of a late-stage, gas-rich merger and demonstrate the potential of integral field spectroscopy to improve our understanding of the role of gas flows during the growth phase of bulges and supermassive black holes. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The data were obtained with the OH Supressing Infrared Spectrograph (OSIRIS) behind the Laser Guide Star Adaptive Optics System.

  9. Market evaluation and investment planning in natural gas industry in Brazil: development of the net distribution pipeline; Avaliacao de mercado e planejamento de investimentos na industria de gas natural no Brasil: perspectivas de crescimento da malha de gasodutos de distribuicao

    Energy Technology Data Exchange (ETDEWEB)

    Avila, Pedro L.; Pamplona, Edson O. [Universidade Federal de Itajuba (UNIFEI), MG (Brazil)

    2008-07-01

    This paper proposes to develop a real options model to decision-making investments in flexible technologies. As a result, finding a closed-form solution, derived from the partial differential equation of the value of flexibility provided by alternative fuels. However, you can present and analysis the results of a practical application using the method to solve real options problems known as binomial model. Initially presents a brief explanation on the method of discounted cash flow, its failures and changes to the real options analysis. In the sequence chart an overview of the natural gas industry on Brazil, emphasizing the need for consistent investments evaluations in the sector. The next section shows the proposed development of mathematical model for assessing the flexibility to choose, obtained by the exchange of fuel for transport of gas pipeline distribution of natural gas. The model takes as the case scenario where the flexible pipeline can carry both natural gas and hydrogen, and the evaluation of the option of exchanging input gives more value to the investment opportunity, and consider the optimum conditions where the option to be exercised. Keywords: Decision Making, Real Options; Natural Gas, Flexible Technology. (author)

  10. Direct simulation Monte Carlo method for gas flows in micro-channels with bends with added curvature

    Directory of Open Access Journals (Sweden)

    Tisovský Tomáš

    2017-01-01

    Full Text Available Gas flows in micro-channels are simulated using an open source Direct Simulation Monte Carlo (DSMC code dsmcFOAM for general application to rarefied gas flow written within the framework of the open source C++ toolbox called OpenFOAM. Aim of this paper is to investigate the flow in micro-channel with bend with added curvature. Results are compared with flows in channel without added curvature and equivalent straight channel. Effects of micro-channel bend was already thoroughly investigated by White et al. Geometry proposed by White is also used here for refference.

  11. Numerical simulations of the Macondo well blowout reveal strong control of oil flow by reservoir permeability and exsolution of gas.

    Science.gov (United States)

    Oldenburg, Curtis M; Freifeld, Barry M; Pruess, Karsten; Pan, Lehua; Finsterle, Stefan; Moridis, George J

    2012-12-11

    In response to the urgent need for estimates of the oil and gas flow rate from the Macondo well MC252-1 blowout, we assembled a small team and carried out oil and gas flow simulations using the TOUGH2 codes over two weeks in mid-2010. The conceptual model included the oil reservoir and the well with a top boundary condition located at the bottom of the blowout preventer. We developed a fluid properties module (Eoil) applicable to a simple two-phase and two-component oil-gas system. The flow of oil and gas was simulated using T2Well, a coupled reservoir-wellbore flow model, along with iTOUGH2 for sensitivity analysis and uncertainty quantification. The most likely oil flow rate estimated from simulations based on the data available in early June 2010 was about 100,000 bbl/d (barrels per day) with a corresponding gas flow rate of 300 MMscf/d (million standard cubic feet per day) assuming the well was open to the reservoir over 30 m of thickness. A Monte Carlo analysis of reservoir and fluid properties provided an uncertainty distribution with a long tail extending down to 60,000 bbl/d of oil (170 MMscf/d of gas). The flow rate was most strongly sensitive to reservoir permeability. Conceptual model uncertainty was also significant, particularly with regard to the length of the well that was open to the reservoir. For fluid-entry interval length of 1.5 m, the oil flow rate was about 56,000 bbl/d. Sensitivity analyses showed that flow rate was not very sensitive to pressure-drop across the blowout preventer due to the interplay between gas exsolution and oil flow rate.

  12. Wavy liquid films in interaction with a strongly confined laminar gas flow: Modeling and direct numerical simulations

    Science.gov (United States)

    Dietze, Georg F.; Ruyer-Quil, Christian

    2013-11-01

    Different technological settings concern the flow of a wavy liquid film in contact with a strongly confined gas flow. Micro-gaps for instance, which are employed for the cooling of electronic equipment, involve a pressure-driven evaporating liquid film flowing co-currently to its own vapor. In packed columns used for distillation, falling liquid films sheared by a counter-current gas flow occur within narrow channels. Surface waves on the liquid-gas interface of these flows play an important role as they intensify scalar transfer and may cause flooding of the channel. However, their accurate prediction by full numerical simulation is associated with a substantial computational cost. We evaluate an alternative approach based on a low-dimensional integral boundary layer formulation applied to both fluid layers. The resulting model captures the long-wave (Yih and Kapitza) instabilities of the flow accurately and allows calculations on long domains at low computational cost. These evince a number of intricate wave-induced flow structures within the film and gas as well as a possible route to the flooding of narrow channels under counter-current gas flow conditions. Comparisons with direct numerical simulations using the VOF-CSF approach as well as experiments are convincing. GFD acknowledges support from DAAD (Deutscher Akademischer Austauschdienst).

  13. Numerical Simulations of Liquid-Gas-Solid Three-Phase Flows in Microgravity

    Directory of Open Access Journals (Sweden)

    Xinyu Zhang

    2012-03-01

    Full Text Available Three-phase liquid-gas-solid flows under microgravity condition are studied. An Eulerian-Lagrangian computational model was developed and used in the simulations. In this approach, the liquid flow was modeled by a volume-averaged system of governing equations, whereas motions of particles and bubbles were evaluated using the Lagrangian trajectory analysis procedure. It was assumed that the bubbles remained spherical, and their shape variations were neglected. The bubble-liquid, particle-liquid and bubbl-particle two-way interactions were accounted for in the analysis. The discrete phase equations used included drag, lift, buoyancy, and virtual mass forces. Particle-particle interactions and bubble-bubble interactions were accounted for by the hard sphere model. Bubble coalescence was also included in the model. The transient flow characteristics of the three-phase flow were studied; and the effects of gravity, inlet bubble size and g-jitter acceleration on variation of flow characteristics were discussed. The low gravity simulations showed that most bubbles are aggregated in the inlet region. Also, under microgravity condition, bubble transient time is much longer than that in normal gravity. As a result, the Sauter mean bubble diameter, which is proportional to the transient time of the bubble, becomes rather large, reaching to more than 9 mm. The bubble plume in microgravity exhibits a plug type flow behavior. After the bubble plume reaches the free surface, particle volume fraction increases along the height of the column. The particles are mainly located outside the bubble plume, with very few particles being retained in the plume. In contrast to the normal gravity condition, the three phases in the column are poorly mixed under microgravity conditions. The velocities of the three phases were also found to be of the same order. Bubble size significantly affects the characteristics of the three-phase flows under microgravity conditions. For

  14. Gas-Kinetic Navier-Stokes Solver for Hypersonic Flows in Thermal and Chemical Non-Equilibrium Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR project proposes to develop a gas-kinetic Navier-Stokes solver for simulation of hypersonic flows in thermal and chemical non-equilibrium. The...

  15. Analysis of Water Hammer with Different Closing Valve Laws on Transient Flow of Hydrogen-Natural Gas Mixture

    National Research Council Canada - National Science Library

    Subani, Norazlina; Amin, Norsarahaida

    2015-01-01

      Water hammer on transient flow of hydrogen-natural gas mixture in a horizontal pipeline is analysed to determine the relationship between pressure waves and different modes of closing and opening of valves...

  16. Study of the motion and deposition of micro particles in a vertical tube containing uniform gas flow

    Science.gov (United States)

    Abolpour, Bahador; Afsahi, M. Mehdi; Soltani Goharrizi, Ataallah; Azizkarimi, Mehdi

    2017-12-01

    In this study, effects of a gaseous jet, formed in a vertical tube containing a uniform gas flow, on the injected micro particles have been investigated. A CFD model has been developed to simulate the particle motion in the tube. This simulation is very close to the experimental data. The results show that, increasing the flow rate of carrier gas or decreasing the flow rate of surrounding gas increases the effect of gaseous jet and also increases trapping rate of the particles by the tube wall. The minimum and maximum residence times of particles approach together with increasing the size of solid particles. Particles larger than 60 μm have a certain and fixed residence time at different flow rates of the carrier or surrounding gas. About 40 μm particle size has minimal trapping by the tube wall at various experimental conditions.

  17. multiUQ: An intrusive uncertainty quantification tool for gas-liquid multiphase flows

    Science.gov (United States)

    Turnquist, Brian; Owkes, Mark

    2017-11-01

    Uncertainty quantification (UQ) can improve our understanding of the sensitivity of gas-liquid multiphase flows to variability about inflow conditions and fluid properties, creating a valuable tool for engineers. While non-intrusive UQ methods (e.g., Monte Carlo) are simple and robust, the cost associated with these techniques can render them unrealistic. In contrast, intrusive UQ techniques modify the governing equations by replacing deterministic variables with stochastic variables, adding complexity, but making UQ cost effective. Our numerical framework, called multiUQ, introduces an intrusive UQ approach for gas-liquid flows, leveraging a polynomial chaos expansion of the stochastic variables: density, momentum, pressure, viscosity, and surface tension. The gas-liquid interface is captured using a conservative level set approach, including a modified reinitialization equation which is robust and quadrature free. A least-squares method is leveraged to compute the stochastic interface normal and curvature needed in the continuum surface force method for surface tension. The solver is tested by applying uncertainty to one or two variables and verifying results against the Monte Carlo approach. NSF Grant #1511325.

  18. A Radiative Transfer Modeling Methodology in Gas-Liquid Multiphase Flow Simulations

    Directory of Open Access Journals (Sweden)

    Gautham Krishnamoorthy

    2014-01-01

    Full Text Available A methodology for performing radiative transfer calculations in computational fluid dynamic simulations of gas-liquid multiphase flows is presented. By considering an externally irradiated bubble column photoreactor as our model system, the bubble scattering coefficients were determined through add-on functions by employing as inputs the bubble volume fractions, number densities, and the fractional contribution of each bubble size to the bubble volume from four different multiphase modeling options. The scattering coefficient profiles resulting from the models were significantly different from one another and aligned closely with their predicted gas-phase volume fraction distributions. The impacts of the multiphase modeling option, initial bubble diameter, and gas flow rates on the radiation distribution patterns within the reactor were also examined. An increase in air inlet velocities resulted in an increase in the fraction of larger sized bubbles and their contribution to the scattering coefficient. However, the initial bubble sizes were found to have the strongest impact on the radiation field.

  19. Existence for a global pressure formulation of water-gas flow in porous media

    Directory of Open Access Journals (Sweden)

    Brahim Amaziane

    2012-06-01

    Full Text Available We consider a model of water-gas flow in porous media with an incompressible water phase and a compressible gas phase. Such models appear in gas migration through engineered and geological barriers for a deep repository for radioactive waste. The main feature of this model is the introduction of a new global pressure and it is fully equivalent to the original equations. The system is written in a fractional flow formulation as a degenerate parabolic system with the global pressure and the saturation potential as the main unknowns. The major difficulties related to this model are in the nonlinear degenerate structure of the equations, as well as in the coupling in the system. Under some realistic assumptions on the data, including unbounded capillary pressure function and non-homogeneous boundary conditions, we prove the existence of weak solutions of the system. Furthermore, it is shown that the weak solution has certain desired properties, such as positivity of the saturation. The result is proved with the help of an appropriate regularization and a time discretization of the coupled system. We use suitable test functions to obtain a priori estimates and a compactness result in order to pass to the limit in nonlinear terms.

  20. A flow reactor setup for photochemistry of biphasic gas/liquid reactions

    Directory of Open Access Journals (Sweden)

    Josef Schachtner

    2016-08-01

    Full Text Available A home-built microreactor system for light-mediated biphasic gas/liquid reactions was assembled from simple commercial components. This paper describes in full detail the nature and function of the required building elements, the assembly of parts, and the tuning and interdependencies of the most important reactor and reaction parameters. Unlike many commercial thin-film and microchannel reactors, the described set-up operates residence times of up to 30 min which cover the typical rates of many organic reactions. The tubular microreactor was successfully applied to the photooxygenation of hydrocarbons (Schenck ene reaction. Major emphasis was laid on the realization of a constant and highly reproducible gas/liquid slug flow and the effective illumination by an appropriate light source. The optimized set of conditions enabled the shortening of reaction times by more than 99% with equal chemoselectivities. The modular home-made flow reactor can serve as a prototype model for the continuous operation of various other reactions at light/liquid/gas interfaces in student, research, and industrial laboratories.

  1. Aerosol flow in a tube furnace reactor of gas-phase synthesised silver nanoparticles

    Science.gov (United States)

    Mitrakos, D.; Jokiniemi, J.; Backman, U.; Housiadas, C.

    2008-12-01

    In a previous work, gas-phase synthesis of silver nanoparticles through evaporation of silver powder and subsequent particle nucleation by cooling was shown to be a viable method for achieving high purity silver nanoparticles (Backman et al. J Nanopart Res 4:325-335, 2002). In order to control the size of the produced nanoparticles, careful design of the reactor is required with respect to thermal and flow characteristics. In the present work, the silver nanoparticle reactor is rigorously simulated by means of multidimensional computational fluid and particle dynamics. The CFD-computed flow is input for a combined simulation of the vapour field and particle homogeneous nucleation, growth and coagulation. The results are compared with the experimental data and with the predictions from the usually employed simple model of an idealized plug flow reactor. The multidimensional CFD-based analysis is shown to explain and help understand different aspects of the reactor operation and size distribution of the particles produced. Yet the simple plug flow method is found to provide reasonable accuracy when an appropriate correction factor is used for the nucleation rate. Considering its robustness and computational simplicity, the plug flow method can be qualified as adequate from the engineering practical point of view for the case of silver nanoparticle reactors.

  2. Unidirectional gas flow in soil porosity resulting from barometric pressure cycles.

    Science.gov (United States)

    Neeper, Donald A; Stauffer, Philip

    2005-08-01

    During numerical simulation of air flow in the vadose zone, it was noticed that a small sinusoidal pressure would cause a gradual one-way migration of the pore gas. This was found to be a physical phenomenon, not a numerical artifact of the finite element simulation. The one-way migration occurs because the atmospheric pressure, and hence the air density, is slightly greater when air is flowing into the ground than when air is flowing out of the ground. A simple analytic theory of the phenomenon is presented, together with analytic calculations using actual barometric pressure data. In soil of one Darcy permeability, the one-way migration is of the order of a few tenths of a meter per year for either plane flow from ground surface or for radial flow from an open borehole. The migration is sufficiently small that it will have no practical consequences in most circumstances; however, investigators who conduct detailed numerical modeling should recognize that this phenomenon is not a numerical artifact in an apparently linear system.

  3. An experimental investigation of gas jets in confined swirling air flow

    Science.gov (United States)

    Mongia, H.; Ahmed, S. A.; Mongia, H. C.

    1984-01-01

    The fluid dynamics of jets in confined swirling flows which is of importance to designers of turbine combustors and solid fuel ramjets used to power missiles fired from cannons were examined. The fluid dynamics of gas jets of different densities in confined swirling flows were investigated. Mean velocity and turbulence measurements are made with a one color, one component laser velocimeter operating in the forward scatter mode. It is shown that jets in confined flow with large area ratio are highly dissipative which results in both air and helium/air jet centerline velocity decays. For air jets, the jet like behavior in the tube center disappears at about 20 diameters downstream of the jet exit. This phenomenon is independent of the initial jet velocity. The turbulence field at this point also decays to that of the background swirling flow. A jet like behavior in the tube center is noticed even at 40 diameters for the helium/air jets. The subsequent flow and turbulence field depend highly on the initial jet velocity. The jets are fully turbulent, and the cause of this difference in behavior is attributed to the combined action swirl and density difference. This observation can have significant impact on the design of turbine combustors and solid fuel ramjets subject to spin.

  4. Establishing isokinetic flow for a plasma torch exhaust gas diagnostic for a plasma hearth furnace

    Energy Technology Data Exchange (ETDEWEB)

    Pollack, Brian R. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    1996-05-01

    Real time monitoring of toxic metallic effluents in confined gas streams can be accomplished through use of Microwave Induced Plasmas to perform atomic emission spectroscopy, For this diagnostic to be viable it is necessary that it sample from the flowstream of interest in an isokinetic manner. A method of isokinetic sampling was established for this device for use in the exhaust system of a plasma hearth vitrification furnace. The flow and entrained particulate environment were simulated in the laboratory setting using a variable flow duct of the same dimensions (8-inch diameter, schedule 40) as that in the field and was loaded with similar particulate (less than 10 μm in diameter) of lake bed soil typically used in the vitrification process. The flow from the furnace was assumed to be straight flow. To reproduce this effect a flow straightener was installed in the device. An isokinetic sampling train was designed to include the plasma torch, with microwave power input operating at 2.45 GHz, to match local freestream velocities between 800 and 2400 ft/sec. The isokinetic sampling system worked as planned and the plasma torch had no difficulty operating at the required flowrates. Simulation of the particulate suspension was also successful. Steady particle feeds were maintained over long periods of time and the plasma diagnostic responded as expected.

  5. Stability of Wavy Films in Gas-Liquid Two-Phase Flows at Normal and Microgravity Conditions

    Science.gov (United States)

    Balakotaiah, V.; Jayawardena, S. S.

    1996-01-01

    For flow rates of technological interest, most gas-liquid flows in pipes are in the annular flow regime, in which, the liquid moves along the pipe wall in a thin, wavy film and the gas flows in the core region. The waves appearing on the liquid film have a profound influence on the transfer rates, and hence on the design of these systems. We have recently proposed and analyzed two boundary layer models that describe the characteristics of laminar wavy films at high Reynolds numbers (300-1200). Comparison of model predictions to 1-g experimental data showed good agreement. The goal of our present work is to understand through a combined program of experimental and modeling studies the characteristics of wavy films in annular two-phase gas-liquid flows under normal as well as microgravity conditions in the developed and entry regions.

  6. A Probabilistic Approach for Predicting Average Slug Frequency in Horizontal Gas/Liquid Pipe Flow

    Directory of Open Access Journals (Sweden)

    Kadri U.

    2013-02-01

    Full Text Available In this paper, we present a model for predicting the average slug frequency in horizontal gas/liquid pipe flow. The model considers the probability of slug formation if slugs are triggered at the antinodes of a sinusoidal perturbation, along the pipe at the frequency of oscillation of the interface. A slug is assumed to form if and only if triggered at a space-time far enough from existing slugs. The probability of forming slugs is found to decrease with distance from the inlet, since the downstream passage of existing slugs prevents the formation of new slugs. Predictions by the model are compared with air/water, freon/water and air/oil measurements found in literature, with a satisfactory agreement. However, a deviation from measurements is observed when considering high viscosity liquid. The model contributes to the prediction of slug flow regime and can act as a guideline toward the design of gas/liquid horizontal pipe flow.

  7. DEVELOPMENT OF A LOW COST INFERENTIAL NATURAL GAS ENERGY FLOW RATE PROTOTYPE RETROFIT MODULE

    Energy Technology Data Exchange (ETDEWEB)

    E. Kelner; D. George; T. Morrow; T. Owen; M. Nored; R. Burkey; A. Minachi

    2005-05-01

    In 1998, Southwest Research Institute began a multi-year project to develop a working prototype instrument module for natural gas energy measurement. The module will be used to retrofit a natural gas custody transfer flow meter for energy measurement, at a cost an order of magnitude lower than a gas chromatograph. Development and evaluation of the prototype energy meter in 2002-2003 included: (1) refinement of the algorithm used to infer properties of the natural gas stream, such as heating value; (2) evaluation of potential sensing technologies for nitrogen content, improvements in carbon dioxide measurements, and improvements in ultrasonic measurement technology and signal processing for improved speed of sound measurements; (3) design, fabrication and testing of a new prototype energy meter module incorporating these algorithm and sensor refinements; and (4) laboratory and field performance tests of the original and modified energy meter modules. Field tests of the original energy meter module have provided results in close agreement with an onsite gas chromatograph. The original algorithm has also been tested at a field site as a stand-alone application using measurements from in situ instruments, and has demonstrated its usefulness as a diagnostic tool. The algorithm has been revised to use measurement technologies existing in the module to measure the gas stream at multiple states and infer nitrogen content. The instrumentation module has also been modified to incorporate recent improvements in CO{sub 2} and sound speed sensing technology. Laboratory testing of the upgraded module has identified additional testing needed to attain the target accuracy in sound speed measurements and heating value.

  8. Seismic evidence of gas hydrates, multiple BSRs and fluid flow offshore Tumbes Basin, Peru

    Science.gov (United States)

    Auguy, Constance; Calvès, Gérôme; Calderon, Ysabel; Brusset, Stéphane

    2017-12-01

    Identification of a previously undocumented hydrate system in the Tumbes Basin, localized off the north Peruvian margin at latitude of 3°20'—4°10'S, allows us to better understand gas hydrates of convergent margins, and complement the 36 hydrate sites already identified around the Pacific Ocean. Using a combined 2D-3D seismic dataset, we present a detailed analysis of seismic amplitude anomalies related to the presence of gas hydrates and/or free gas in sediments. Our observations identify the occurrence of a widespread bottom simulating reflector (BSR), under which we observed, at several sites, the succession of one or two BSR-type reflections of variable amplitude, and vertical acoustic discontinuities associated with fluid flow and gas chimneys. We conclude that the uppermost BSR marks the current base of the hydrate stability field, for a gas composition comprised between 96% methane and 4% of ethane, propane and pure methane. Three hypotheses are developed to explain the nature of the multiple BSRs. They may refer to the base of hydrates of different gas composition, a remnant of an older BSR in the process of dispersion/dissociation or a diagenetically induced permeability barrier formed when the active BSR existed stably at that level for an extended period. The multiple BSRs have been interpreted as three events of steady state in the pressure and temperature conditions. They might be produced by climatic episodes since the last glaciation associated with tectonic activity, essentially tectonic subsidence, one of the main parameters that control the evolution of the Tumbes Basin.

  9. Application of the gas tracer method for measuring oxygen transfer rates in subsurface flow constructed wetlands.

    Science.gov (United States)

    Tyroller, Lina; Rousseau, Diederik P L; Santa, Santa; García, Joan

    2010-07-01

    The oxygen transfer rate (OTR) has a significant impact on the design, optimal operation and modelling of constructed wetlands treating wastewater. Oxygen consumption is very fast in wetlands and the OTR cannot be determined using an oxygen mass balance. This problem is circumvented in this study by applying the gas tracer method. Experiments were conducted in an unplanted gravel bed (dimensions L x W x d 125 x 50 x 35 cm filled with a 30-cm layer of 10-11-mm gravel) and a planted horizontal subsurface flow constructed wetland (HSSFCW) (L x W x d 110 x 70 x 38 cm filled with a 30-cm layer of 3.5-mm gravel with Phragmites australis). Tap water saturated with propane as gas tracer (pure or commercial cooking gas, depending on the test) was used. The mass transfer ratio between oxygen and commercial propane gas was quite constant and averaged R = 1.03, which is slightly lower than the value of R = 1.39 that is usually reported for pure propane. The OTR ranged from 0.31 to 5.04 g O(2) m(-2) d(-1) in the unplanted gravel bed and from 0.3 to 3.2 g O(2) m(-2) d(-1) in the HSSFCW, depending on the hydraulic retention time (HRT). The results of this study suggest that the OTR in HSSFCW is very low for the oxygen demand of standard wastewater and the OTR calculations based on mass balances and theoretical stoichiometric considerations overestimate OTR values by a factor that ranges from 10 to 100. The gas tracer method is a promising tool for determining OTR in constructed wetlands, with commercial gas proving to be a viable low-cost alternative for determining OTR. Copyright 2010 Elsevier Ltd. All rights reserved.

  10. Gas-Solid Turbulent Flow in a Circulating Fluidized Bed Riser; Numerical Study of Binary Particle Mixtures

    NARCIS (Netherlands)

    He, Y; Deen, N.G.; van Sint Annaland, M.; Kuipers, J.A.M.

    2008-01-01

    A numerical simulation was performed on a turbulent gas-particle multi-phase flow in a circulating fluidized bed riser based on a hard-sphere discrete particle model (DPM) for the particle phase and the Navier-Stokes equations for the gas phase. The sub-grid scale stresses (SGS) were modeled with

  11. 40 CFR 86.120-94 - Gas meter or flow instrumentation calibration; particulate, methanol and formaldehyde measurement.

    Science.gov (United States)

    2010-07-01

    ... calibration; particulate, methanol and formaldehyde measurement. 86.120-94 Section 86.120-94 Protection of... 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...

  12. Modeling of filling gas centrifuge cascade for nickel isotope separation by feed flow input to different stages

    Directory of Open Access Journals (Sweden)

    Orlov Alexey A.

    2017-01-01

    Full Text Available The article presents results of research filling gas centrifuge cascade by process gas fed into different stages. The modeling of filling cascade was done for nickel isotope separation. Analysis of the research results shows that nickel isotope concentrations of light and heavy fraction flows after filling cascade depend on feed stage number.

  13. Film cooling effects on the tip flow characteristics of a gas turbine blade

    Directory of Open Access Journals (Sweden)

    Jin Wang

    2015-03-01

    Full Text Available An experimental investigation of the tip flow characteristics between a gas turbine blade tip and the shroud was conducted by a pressure-test system and a particle image velocimetry (PIV system. A three-times scaled profile of the GE-E3 blade with five film cooling holes was used as specimen. The effects on flow characteristics by the rim width and the groove depth of the squealer tip were revealed. The rim widths were (a 0.9%, (b 2.1%, and (c 3.0% of the axial chord, and the groove depths were (a 2.8%, (b 4.8%, and (c 10% of the blade span. Several pressure taps on the top plate above the blades were connected to pressure gauges. By a CCD camera the PIV system recorded the velocity field around the leading edge zone including the five cooling holes. The flow distributions both in the tip clearance and in the passage were revealed, and the influence of the inlet velocity was determined. In this work, the tip flow characteristics with and without film cooling were investigated. The effects of different global blowing ratios of M=0.5, 1.0, 1.3 and 2.5 were established. It was found that decreasing the rim width resulted in a lower mass flow rate of the leakage flow, and the pressure distributions from the leading edge to the trailing edge showed a linearly increasing trend. It was also found that if the inlet velocity was less than 1.5 m/s, the flow field in the passage far away from the suction side appeared as a stagnation zone.

  14. Multiphase Flow Behavior of Layered Methane Hydrate Reservoir Induced by Gas Production

    Directory of Open Access Journals (Sweden)

    Yilong Yuan

    2017-01-01

    Full Text Available Gas hydrates are expected to be a potential energy resource with extensive distribution in the permafrost and in deep ocean sediments. The marine gas hydrate drilling explorations at the Eastern Nankai Trough of Japan revealed the variable distribution of hydrate deposits. Gas hydrate reservoirs are composed of alternating beds of sand and clay, with various conditions of permeability, porosity, and hydrate saturation. This study looks into the multiphase flow behaviors of layered methane hydrate reservoirs induced by gas production. Firstly, a history matching model by incorporating the available geological data at the test site of the Eastern Nankai Trough, which considers the layered heterogeneous structure of hydrate saturation, permeability, and porosity simultaneously, was constructed to investigate the production characteristics from layered hydrate reservoirs. Based on the validated model, the effects of the placement of production interval on production performance were investigated. The modeling results indicate that the dissociation zone is strongly affected by the vertical reservoir’s heterogeneous structure and shows a unique dissociation front. The beneficial production interval scheme should consider the reservoir conditions with high permeability and high hydrate saturation. Consequently, the identification of the favorable hydrate deposits is significantly important to realize commercial production in the future.

  15. Transfer of gas from the acinus during continuous flow and intermittent positive pressure ventilation.

    Science.gov (United States)

    Forrest, F C; Randalls, P B; Barnas, G M; Hoff, B H; Oletsky, J; Mackenzie, C F

    1994-02-01

    We used a technique of measuring Xenon133 washout (XeW) from the alveolar space to evaluate transfer of gas from the acinus (Mackenzie et al., J. Appl. Physiol. 68: 2013-2018, 1990) during 2 min of apnea, 2 min of tracheal insufflation with oxygen (TRIO) and 90 sec of intermittent positive pressure ventilation (IPPV) in 6 anesthetized and paralyzed dogs. Xenon133 dissolved in saline was injected into an occluded acinar region through a pulmonary artery catheter, and XeW was measured by gamma scintillation scanning. With this technique, XeW during apnea represents the contribution of cardiogenic oscillations in regional flow. The XeW rate constant (min-1 +/- SE) was 0.37 +/- 0.03 during apnea. This was not different (P > 0.05) with TRIO (0.29 +/- 0.04). With IPPV, the rate constant increased to 3.49 +/- 0.39, faster than with either apnea or TRIO (P < 0.001). We conclude that: (1) TRIO does not increase convective gas transfer from the acini compared to apnea; and (2) transfer of gas out of the acini due to cardiogenic oscillations is a very small portion of the total gas eliminated during IPPV.

  16. Impact of Gas Delivery Systems on Imaging Studies of Human Cerebral Blood Flow

    Directory of Open Access Journals (Sweden)

    John R. Cain

    2013-01-01

    Full Text Available Purpose. To compare a semiopen breathing circuit with a non-rebreathing (Hudson mask for MRI experiments involving gas delivery. Methods and Materials. Cerebral blood flow (CBF was measured by quantitative phase contrast angiography of the internal carotid and basilar arteries in 18 volunteers (20–31 years. In 8 subjects, gases were delivered via a standard non-rebreathing (Hudson mask. In 10 subjects, gases were delivered using a modified “Mapleson A” semiopen anesthetic gas circuit and mouthpiece. All subjects were given 100% O2, medical air, and carbogen gas (95% O2 and 5% CO2 delivered at 15 L/min in a random order. Results. The Hudson mask group showed significant increases in CBF in response to increased FiCO2 compared to air (+9.8%. A small nonsignificant reduction in CBF (−2.4% was seen in response to increased inspired concentrations of oxygen (FiO2. The Mapleson A group showed significantly larger changes in CBF in response to both increased inspired concentrations of carbon dioxide (FiCO2 (+32.2%, P<0.05 and FiO2 (−14.6%, P<0.01. Conclusions. The use of an anaesthetic gas delivery circuit avoids entrainment of room air and rebreathing effects that may otherwise adversely affect the experimental results.

  17. Impact of Gas Delivery Systems on Imaging Studies of Human Cerebral Blood Flow

    Science.gov (United States)

    Cain, John R.; Parkes, Laura M.; Eadsforth, Peter; Beards, Susan C.; Jackson, Alan

    2013-01-01

    Purpose. To compare a semiopen breathing circuit with a non-rebreathing (Hudson mask) for MRI experiments involving gas delivery. Methods and Materials. Cerebral blood flow (CBF) was measured by quantitative phase contrast angiography of the internal carotid and basilar arteries in 18 volunteers (20–31 years). In 8 subjects, gases were delivered via a standard non-rebreathing (Hudson mask). In 10 subjects, gases were delivered using a modified “Mapleson A” semiopen anesthetic gas circuit and mouthpiece. All subjects were given 100% O2, medical air, and carbogen gas (95% O2 and 5% CO2) delivered at 15 L/min in a random order. Results. The Hudson mask group showed significant increases in CBF in response to increased FiCO2 compared to air (+9.8%). A small nonsignificant reduction in CBF (−2.4%) was seen in response to increased inspired concentrations of oxygen (FiO2). The Mapleson A group showed significantly larger changes in CBF in response to both increased inspired concentrations of carbon dioxide (FiCO2) (+32.2%, P < 0.05) and FiO2 (−14.6%, P < 0.01). Conclusions. The use of an anaesthetic gas delivery circuit avoids entrainment of room air and rebreathing effects that may otherwise adversely affect the experimental results. PMID:24392225

  18. Effects of nitrogen application rates on net annual global warming potential and greenhouse gas intensity in double-rice cropping systems of the Southern China.

    Science.gov (United States)

    Chen, Zhongdu; Chen, Fu; Zhang, Hailin; Liu, Shengli

    2016-12-01

    The net global warming potential (NGWP) and net greenhouse gas intensity (NGHGI) of double-rice cropping systems are not well documented. We measured the NGWP and NGHGI including soil organic carbon (SOC) change and indirect emissions (IE) from double-crop rice fields with fertilizing systems in Southern China. These experiments with three different nitrogen (N) application rates since 2012 are as follows: 165 kgN ha -1 for early rice and 225 kgN ha -1 for late rice (N1), which was the local N application rates as the control; 135 kgN ha -1 for early rice and 180 kgN ha -1 for late rice (N2, 20 % reduction); and 105 kgN ha -1 for early rice and 135 kgN ha -1 for late rice (N3, 40 % reduction). Results showed that yields increased with the increase of N application rate, but without significant difference between N1 and N2 plots. Annual SOC sequestration rate under N1 was estimated to be 1.15 MgC ha -1  year -1 , which was higher than those under other fertilizing systems. Higher N application tended to increase CH 4 emissions during the flooded rice season and significantly increased N 2 O emissions from drained soils during the nonrice season, ranking as N1 > N2 > N3 with significant difference (P < 0.05). Two-year average IE has a huge contribution to GHG emissions mainly coming from the higher N inputs in the double-rice cropping system. Reducing N fertilizer usage can effectively decrease the NGWP and NGHGI in the double-rice cropping system, with the lowest NGHGI obtained in the N2 plot (0.99 kg CO 2 -eq kg -1 yield year -1 ). The results suggested that agricultural economic viability and GHG mitigation can be simultaneously achieved by properly reducing N fertilizer application in double-rice cropping systems.

  19. Heat and mass transfer rates during flow of dissociated hydrogen gas over graphite surface

    Science.gov (United States)

    Nema, V. K.; Sharma, O. P.

    1986-01-01

    To improve upon the performance of chemical rockets, the nuclear reactor has been applied to a rocket propulsion system using hydrogen gas as working fluid and a graphite-composite forming a part of the structure. Under the boundary layer approximation, theoretical predictions of skin friction coefficient, surface heat transfer rate and surface regression rate have been made for laminar/turbulent dissociated hydrogen gas flowing over a flat graphite surface. The external stream is assumed to be frozen. The analysis is restricted to Mach numbers low enough to deal with the situation of only surface-reaction between hydrogen and graphite. Empirical correlations of displacement thickness, local skin friction coefficient, local Nusselt number and local non-dimensional heat transfer rate have been obtained. The magnitude of the surface regression rate is found low enough to ensure the use of graphite as a linear or a component of the system over an extended period without loss of performance.

  20. On the Effect of the Boundary Conditions and the Collision Model on Rarefied Gas Flows

    Science.gov (United States)

    Vargas, M.; Stefanov, S.; Valougeorgis, D.

    2011-05-01

    In this work, the effect of the gas-surface interaction law and of the intermolecular collision model is examined by solving, using the DSMC method, the heat transfer problem between parallel plates and the non-isothermal Poiseuille flow problem. In the former one the Cercignani-Lampis model is applied to analyze the influence of the gas-surface interaction parameters, while in the latter one a comparison between the results obtained by implementing the Hard Sphere, Variable Hard Sphere, Variable Soft Sphere and Maxwellian models is performed. Calculations have been carried out for several values of the Knudsen number, temperature ratio and Froude number. A comparison between the DSMC and the corresponding discrete velocity results yields very good agreement between the two approaches. Finally, the convergence behavior of a Bernoulli trials based scheme, which allows the use of a smaller number of particles per cell, and the No Time Counter are compared for different sampling sequences.