WorldWideScience

Sample records for single-phase gas-liquid solids

  1. Acoustic probe for solid-gas-liquid suspensions. 1998 annual progress report

    International Nuclear Information System (INIS)

    Greenwood, M.S.; Sangani, A.S.; Tavlarides, L.L.

    1998-01-01

    'The proposed research will develop an acoustic probe for monitoring particle size and volume fraction in slurries in the absence and presence of gas. The goals are to commission and verify the probe components and system operation, develop theory for the forward and inverse problems for acoustic wave propagation through a three phase medium, and experimentally verify the theoretical analysis. The acoustic probe will permit measurement of solid content in gas-liquid-solid waste slurries in tanks across the DOE complex.'

  2. Functional Ceramic Ferroelectromagnetic Materials in Single Phase Solid-Solutions

    Science.gov (United States)

    2007-12-05

    PbTiO3)1-x, where x= 0.10, 0.20, 0.30, 0.40, 0.67. ( work is still going on) Introduction: Recently BaTiO3 is doped with Ni and Co to get...xBaxMnO3 was expected to enhance the magnetic properties. LaMnO3 is an antiferromagnetic insulator and have cubic perovskite structure. The doping with...research in solid solutions like x (BiFeO3)-(1-x) (PbTiO3) ( BF-PT), BiFeO3- BaTiO3 , BiFeO3- Pb(FeNb)O3, BiFeO3-ReFeO3- BaTiO3 .Mainly the aim of the

  3. 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

  4. PENGARUH SIMULASI PENGARUH KONSENTRASI SOLID DAN GEOMETRI BIOREAKTOR MEMBRAN TERENDAM TERHADAP PERPINDAHAN MASSA GAS-LIQUID DAN FLUKS MELALUI MEMBRAN

    Directory of Open Access Journals (Sweden)

    Aisyah Endah Palupi

    2012-09-01

    Full Text Available Abstract: Hydrodynamics characteristic for the mixing of gas-solid-liquid in membrane bioreactor submerged (MBRs and its influence on mass transfer was studied computationally at various solid concentration, incoming gas rate, and the baffle distance. Computational method was conducted by using software GAMBIT 2.1.6. for the making of the grid which represents the calculation domain and conduct the simulation using CFD software FLUENT commercial code 6.2.16. Multiphase flow in reactor was simulated with mixture model, while to model the turbulence characteristic of the flow standard k-ε model was used. The geometrical system investigate is bioreactor in the form of box with flat bottom, 2 baffles, submerged membrane and air passage through the reactor bottom. The membrane type used is hollow fiber, the liquid used is water, and the solid is activated sludge, and air acts as gas phase. The result indicates that closer the baffle to the membrane, the liquid dispersion process goes faster, so that fluid in tank can be mixed perfectly and it can increase the gas-liquid mass transfer rate and the flux at MBRs. The increase of the solid concentration does not significantly affect the change of gas-liquid mass transfer rate and flux through the membrane, but the increase of air flow rate can accelerate the gas-liquid mass transfer and the flux. The position of baffle 9 cm from tank wall is the best position among the others because the amount of air flow is balanced with the circulating fluid flow. Consider from the solid distribution, double inlet MBRs is better compared to that of single inlet. Flux obtained does not show significant difference. From the both approach of the membrane model, membrane model as porous media give the simulation results closer to the experimental data.

  5. Graphitized carbon in gas-liquid-solid chromatography and gas chromatography/mass spectrometric analysis of high boiling hydrocarbon mixtures

    International Nuclear Information System (INIS)

    Ciccioli, P.; Hayes, J.M.; Rinaldi, G.; Denson, K.B.; Meinschein, W.G.

    1979-01-01

    Gas--liquid--solid chromatography (GLSC) employing a poly(phenyl ether) (PPE 20) liquid phase on graphitized carbon black (GCB) is applicable to the analyses of crude oils and distillates of sedimentary rocks. The elution of C 4 to C 40 hydrocarbons which consist of n-alkanes, isoprenoid-type alkanes, steranes, olefins, and aromatic hydrocarbons can be handled in a single GC run. A GLSC column in tandem with a mass spectrometer provides an excellent means for the identification of geochemically significant organic compounds in complex natural mixtures. 8 figures, 4 tables

  6. Energetics analysis of interstitial loops in single-phase concentrated solid-solution alloys

    Science.gov (United States)

    Wang, Xin-Xin; Niu, Liang-Liang; Wang, Shaoqing

    2018-04-01

    Systematic energetics analysis on the shape preference, relative stability and radiation-induced segregation of interstitial loops in nickel-containing single-phase concentrated solid-solution alloys have been conducted using atomistic simulations. It is shown that the perfect loops prefer rhombus shape for its low potential energy, while the Frank faulted loops favor ellipse for its low potential energy and the possible large configurational entropy. The decrease of stacking fault energy with increasing compositional complexity provides the energetic driving force for the formation of faulted loops, which, in conjunction with the kinetic factors, explains the experimental observation that the fraction of faulted loops rises with increasing compositional complexity. Notably, the kinetics is primarily responsible for the absence of faulted loops in nickel-cobalt with a very low stacking fault energy. We further demonstrate that the simultaneous nickel enrichment and iron/chromium depletion on interstitial loops can be fully accounted for by their energetics.

  7. Towards building a robust computational framework to simulate multi-physics problems - a solution technique for three-phase (gas-liquid-solid) interactions

    Science.gov (United States)

    Zhang, Lucy

    In this talk, we show a robust numerical framework to model and simulate gas-liquid-solid three-phase flows. The overall algorithm adopts a non-boundary-fitted approach that avoids frequent mesh-updating procedures by defining independent meshes and explicit interfacial points to represent each phase. In this framework, we couple the immersed finite element method (IFEM) and the connectivity-free front tracking (CFFT) method that model fluid-solid and gas-liquid interactions, respectively, for the three-phase models. The CFFT is used here to simulate gas-liquid multi-fluid flows that uses explicit interfacial points to represent the gas-liquid interface and for its easy handling of interface topology changes. Instead of defining different levels simultaneously as used in level sets, an indicator function naturally couples the two methods together to represent and track each of the three phases. Several 2-D and 3-D testing cases are performed to demonstrate the robustness and capability of the coupled numerical framework in dealing with complex three-phase problems, in particular free surfaces interacting with deformable solids. The solution technique offers accuracy and stability, which provides a means to simulate various engineering applications. The author would like to acknowledge the supports from NIH/DHHS R01-2R01DC005642-10A1 and the National Natural Science Foundation of China (NSFC) 11550110185.

  8. A variational approach to multi-phase motion of gas, liquid and solid based on the level set method

    Science.gov (United States)

    Yokoi, Kensuke

    2009-07-01

    We propose a simple and robust numerical algorithm to deal with multi-phase motion of gas, liquid and solid based on the level set method [S. Osher, J.A. Sethian, Front propagating with curvature-dependent speed: Algorithms based on Hamilton-Jacobi formulation, J. Comput. Phys. 79 (1988) 12; M. Sussman, P. Smereka, S. Osher, A level set approach for capturing solution to incompressible two-phase flow, J. Comput. Phys. 114 (1994) 146; J.A. Sethian, Level Set Methods and Fast Marching Methods, Cambridge University Press, 1999; S. Osher, R. Fedkiw, Level Set Methods and Dynamics Implicit Surface, Applied Mathematical Sciences, vol. 153, Springer, 2003]. In Eulerian framework, to simulate interaction between a moving solid object and an interfacial flow, we need to define at least two functions (level set functions) to distinguish three materials. In such simulations, in general two functions overlap and/or disagree due to numerical errors such as numerical diffusion. In this paper, we resolved the problem using the idea of the active contour model [M. Kass, A. Witkin, D. Terzopoulos, Snakes: active contour models, International Journal of Computer Vision 1 (1988) 321; V. Caselles, R. Kimmel, G. Sapiro, Geodesic active contours, International Journal of Computer Vision 22 (1997) 61; G. Sapiro, Geometric Partial Differential Equations and Image Analysis, Cambridge University Press, 2001; R. Kimmel, Numerical Geometry of Images: Theory, Algorithms, and Applications, Springer-Verlag, 2003] introduced in the field of image processing.

  9. Using of acoustic technologies for detection of explosives in gas, liquid and solid medium

    International Nuclear Information System (INIS)

    Valyaev, A. N.; Yanushkevich, V.A.

    2004-01-01

    Full text: Some industrial nuclear power objects are very attractive for the realization of radiological and chemical terrorism acts with using of explosives. Although up today this type of terrorism is not revealed itself, but the problem of detection of explosives at these objects is becoming very actual one, for example, in connection with the implementation of the urgent decommissioning of nuclear powered vessels. Such decommissioning includes the utilization the dangerous radioactive and chemical elements, contained in submarines and vessels. This actual problem is existed not only in Russia, but also in abroad. It is noticed that catastrophes at these objects will have in addition the great negative mental effect on population of all over the world, as it was after the Chernobyl accident. The using of the modern nuclear physics methods for detection and analysis of explosives is connected with the following difficulties: (1) we have to have the unique and the expensive equipment; (2) the special preparation of sample probes; (3) a long time is often necessary for analysis; (4) the high qualification of service personal is needed. We proposed to use for these purposes the complex of acoustic techniques, that are based on the high sensitivity of acoustic characteristics of any matter to their physical and chemical properties.Any acoustic signal has the following main parameters: (1) frequency (ω); (2) amplitude of pressure (ρ); (3) wave and amplitude bands; (4) velocity of acoustic wave propagation (sound velocity) (C); (5) space and temporal signal evolution, that is determined by the values of coefficients of temporal attenuation (α), space adsorption (β) and sound dispersion on obstacles and impurities. Our acoustic analysis is included the determination of C, α and β values for solid and liquid explosives. The exact measurements of these parameters and their dependences from frequency and temperature are conducted in the special acoustic cells, that

  10. Lattice model theory of the equation of state covering the gas, liquid, and solid phases

    Science.gov (United States)

    Bonavito, N. L.; Tanaka, T.; Chan, E. M.; Horiguchi, T.; Foreman, J. C.

    1975-01-01

    The three stable states of matter and the corresponding phase transitions were obtained with a single model. Patterned after Lennard-Jones and Devonshires's theory, a simple cubic lattice model containing two fcc sublattices (alpha and beta) is adopted. The interatomic potential is taken to be the Lennard-Jones (6-12) potential. Employing the cluster variation method, the Weiss and the pair approximations on the lattice gas failed to give the correct phase diagrams. Hybrid approximations were devised to describe the lattice term in the free energy. A lattice vibration term corresponding to a free volume correction is included semi-phenomenologically. The combinations of the lattice part and the free volume part yield the three states and the proper phase diagrams. To determine the coexistence regions, the equalities of the pressure and Gibbs free energy per molecule of the coexisting phases were utilized. The ordered branch of the free energy gives rise to the solid phase while the disordered branch yields the gas and liquid phases. It is observed that the triple point and the critical point quantities, the phase diagrams and the coexistence regions plotted are in good agreement with the experimental values and graphs for argon.

  11. Single-Phase PLLs

    DEFF Research Database (Denmark)

    Golestan, Saeed; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

    2017-01-01

    Single-phase phase-locked loops (PLLs) are popular for the synchronization and control of single-phase gridconnected converters. They are also widely used for monitoring and diagnostic purposes in the power and energy areas. In recent years, a large number of single-phase PLLs with different...... structures and properties have been proposed in the literature. The main aim of this paper is to provide a review of these PLLs. To this end, the single-phase PLLs are first classified into two major categories: 1) power-based PLLs (pPLLs), and 2) quadrature signal generation-based PLLs (QSG......-PLLs). The members of each category are then described and their pros and cons are discussed. This work provides a deep insight into characteristics of different single-phase PLLs and, therefore, can be considered as a reference for researchers and engineers....

  12. Optimisation of single-phase dry-thermophilic anaerobic digestion under high organic loading rates of industrial municipal solid waste: population dynamics.

    Science.gov (United States)

    Zahedi, S; Sales, D; Romero, L I; Solera, R

    2013-10-01

    Different high feed organic loading rates (OLRs) (from 5.7 g to 46.0 g TVS/l/d) or hydraulic retention times (HRTs) (from 15 d to 2 d) in single-phase dry-thermophilic anaerobic digestion (AD) of organic fraction municipal solid waste (OFMSW) were investigated. The specific gas production (SGP) values (0.25-0.53 m(3)/kg TVS) and the percentages of Eubacteria, Archaea, H2-utilising methanogens (HUMs) and acetate-utilising methanogens (AUMs) were stable within the ranges 80.2-91.1%, 12.4-18.5%, 4.4-9.8% and 5.5-10.9%, respectively. A HUM/AUM ratio greater than 0.7 seems to be necessary to maintain very low partial pressures of H2 required for dry AD process. Increasing OLR resulted in an increase in all the populations, except for propionate-utilising acetogens (PUAs). Optimal conditions were obtained at 3d HRT (OLR=30.7 g TVS/l/d), which is lower than the doubling time of acetogens and methanogens. The methane production (MP) was clearly higher than those reported in AD of OFMSW. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

    International Nuclear Information System (INIS)

    Li Xiaoyan; Kuang Bo; Zhou Guoliang; Xu Jijun

    1998-01-01

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

  14. A review of solid-fluid selection options for optical-based measurements in single-phase liquid, two-phase liquid-liquid and multiphase solid-liquid flows

    Science.gov (United States)

    Wright, Stuart F.; Zadrazil, Ivan; Markides, Christos N.

    2017-09-01

    Experimental techniques based on optical measurement principles have experienced significant growth in recent decades. They are able to provide detailed information with high-spatiotemporal resolution on important scalar (e.g., temperature, concentration, and phase) and vector (e.g., velocity) fields in single-phase or multiphase flows, as well as interfacial characteristics in the latter, which has been instrumental to step-changes in our fundamental understanding of these flows, and the development and validation of advanced models with ever-improving predictive accuracy and reliability. Relevant techniques rely upon well-established optical methods such as direct photography, laser-induced fluorescence, laser Doppler velocimetry/phase Doppler anemometry, particle image/tracking velocimetry, and variants thereof. The accuracy of the resulting data depends on numerous factors including, importantly, the refractive indices of the solids and liquids used. The best results are obtained when the observational materials have closely matched refractive indices, including test-section walls, liquid phases, and any suspended particles. This paper reviews solid-liquid and solid-liquid-liquid refractive-index-matched systems employed in different fields, e.g., multiphase flows, turbomachinery, bio-fluid flows, with an emphasis on liquid-liquid systems. The refractive indices of various aqueous and organic phases found in the literature span the range 1.330-1.620 and 1.251-1.637, respectively, allowing the identification of appropriate combinations to match selected transparent or translucent plastics/polymers, glasses, or custom materials in single-phase liquid or multiphase liquid-liquid flow systems. In addition, the refractive indices of fluids can be further tuned with the use of additives, which also allows for the matching of important flow similarity parameters such as density and viscosity.

  15. Gas-liquid annular flow in vertical circular tubes with liquid penetrated in nucleus

    International Nuclear Information System (INIS)

    Nogueira, E.; Brum, N.C.L.; Cotta, R.M.

    1990-01-01

    A semi-analytical model is proposed for fully developed upward gas-liquid annular flow inside vertical circular tubes, by utilizing wall-known turbulence algebraic models for single-phase flows, within both streams, combined with empirical correlations for the gas-liquid interface friction factor. Direct integration of the associated momentum equations provide the velocity distribution for each phase, as well as overall quantities of practical interest such as liquid film thickness and pressure gradient. The effects of liquid droplets entrainment in the gas is specialized empirical correlations. Extensive comparisons with experimental results are made in order to demonstrate the consistency of the proposed model. (author)

  16. Gas-Liquid Precipitation of water dissolved heavy metal ions using hydrogen sulfide gas

    NARCIS (Netherlands)

    Al Tarazi, M.Y.M.

    2004-01-01

    Precipitation of solids promoted by gas-liquid reactions is applied in many industrial processes such as the production of ammonium phosphate, ammonium sulphate, barium carbonate, calcium carbonate, calcium fluoride, ypsum (calcium sulphate), goethite, sodium bicarbonate, strontium carbonate and

  17. Local Nusselt number enhancement during gas-liquid Taylor bubble flow in a square mini-channel: An experimental study

    International Nuclear Information System (INIS)

    Majumder, Abhik; Mehta, Balkrishna; Khandekar, Sameer

    2013-01-01

    Taylor bubble flow takes place when two immiscible fluids (liquid-liquid or gas-liquid) flow inside a tube of capillary dimensions within specific range of volume flow ratios. In the slug flows where gas and liquid are two different phases, liquid slugs are separated by elongated Taylor bubbles. This singular flow pattern is observed in many engineering mini-/micro-scale devices like pulsating heat pipes, gas-liquid-solid monolithic reactors, micro-two-phase heat exchangers, digital micro-fluidics, micro-scale mass transfer process, fuel cells, etc. The unique and complex flow characteristics require understanding on local, as well as global, spatio-temporal scales. In the present work, the axial stream-wise profile of the fluid and wall temperature for air-water (i) isolated single Taylor bubble and, (ii) a train of Taylor bubbles, in a horizontal square channel of size 3.3 mm x 3.3 mm x 350 mm, heated from the bottom (heated length = 175 mm), with the other three sides kept insulated, are reported at different gas volume flow ratios. The primary aim is to study the enhancement of heat transfer due to the Taylor bubble train flow, in comparison with thermally developing single-phase flows. Intrusion of a bubble in the liquid flow drastically changes the local temperature profiles. The axial distribution of time-averaged local Nusselt number (Nu z ) shows that Taylor bubble train regime increases the transport of heat up to 1.2-1.6 times more as compared with laminar single-phase liquid flow. In addition, for a given liquid flow Reynolds number, the heat transfer enhancement is a function of the geometrical parameters of the unit cell, i.e., the length of adjacent gas bubble and water plug. (authors)

  18. Calcination and solid state reaction of ceramic-forming components to provide single-phase superconducting materials having fine particle size

    Science.gov (United States)

    Balachandran, Uthamalingam; Poeppel, Roger B.; Emerson, James E.; Johnson, Stanley A.

    1992-01-01

    An improved method for the preparation of single phase, fine grained ceramic materials from precursor powder mixtures where at least one of the components of the mixture is an alkali earth carbonate. The process consists of heating the precursor powders in a partial vacuum under flowing oxygen and under conditions where the partial pressure of CO.sub.2 evolved during the calcination is kept to a very low level relative to the oxygen. The process has been found particularly suitable for the preparation of high temperature copper oxide superconducting materials such as YBa.sub.2 Cu.sub.3 O.sub.x "123" and YBa.sub.2 Cu.sub.4 O.sub.8 "124".

  19. Undiscovered Natural Gas Liquids Colorado Plateau

    Data.gov (United States)

    Department of the Interior — This dataset is based on U.S. Geological Survey (USGS) resource assessments for “undiscovered” natural gas liquid resources, which are resources that have not yet...

  20. FSU's natural gas liquids business needs investment

    International Nuclear Information System (INIS)

    Plotnikov, V.S.; Berman, M.; Angerinos, G.F.

    1995-01-01

    Production of natural gas liquids has fallen seriously behind its potential in the former Soviet Union (FSU). Restoration of the gas liquids business thus represents a rich investment opportunity. Capital, however, must come from international sources, which remain uncertain about the FSU's legal, commercial, and political systems. If these hurdles can be overcome, FSU output of liquid petroleum gas alone might double between 1990 and 2010. In the FSU, LPG is produced from associated and nonassociated natural gas, condensate, and refinery streams. It also comes from what is known in the FSU as ShFLU--a mixture of propane, butane, pentane, and hexane produced at gas processing plants in Western Siberia and fractionated elsewhere. The paper reviews FSU production of gas liquids focusing on West Siberia, gives a production outlook, and describes LPG use and business development

  1. Gas-liquid contacting in mixing vessels

    International Nuclear Information System (INIS)

    Mann, R.

    1983-01-01

    This report by Dr. R. Mann of UMIST presents a critical survey of literature on the contacting of gases with liquids in stirred vessels. Research undertaken in the last fifteen years in analysed, and promising areas for future research are identified. The report deals with physical contacting, mass transfer between the gas and liquid phases and the utilisation of the stirred vessel as a gas-liquid reactor. Three sections are given on gas-liquid contacting: physical aspects; interphase mass transfer; and chemical reactions. It also discusses recent new approaches and includes a summary of conclusions, nomenclature and references

  2. 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).

  3. Part A. Chemical neutron activation analysis of aluminum in biological samples. Part B. Stereochemical consequences of chlorine substitution reactions with (2S,3S)dl-2-chloro-3-fluoropentane and (2S,3S)dl-3-chloro-2-fluoropentane in the gas, liquid and solid phase

    International Nuclear Information System (INIS)

    Roman, F.R.

    1989-01-01

    A method was developed for determination of aluminum in biological samples by anion exchange chromatography and neutron activation analysis (NAA). The samples were digested with nitric acid at 65 degree C, converting the aluminum to Al +3 . The remaining solids were dissolved with dilute tiron solution, and the pH adjusted to six with ammonium hydroxide. The tiron forms a negative complex with aluminum, which is retained on the anion exchange resin. To remove the interfering ions ( 31 P, 24 Na, 37 Cl) present in biological material, ammonium citrate was eluted through the resin. The aluminum was stripped from the resin with nitric acid. Fractions eluting from the column were assayed for aluminum content using NAA. The aluminum recoveries were determined to be quantitative by the method of additive spikes. Urine, bone and tissue samples were analyzed for aluminum content. Previously reported recoil halogen-for-halogen substitution reactions of diastereomeric compounds in the gas, liquid and solid phases occurred predominantly with retention of configuration. The stereo-chemical consequences of translationally excited chlorine-for-halogen substitution reactions in 2,3-dihalopentanes were studied in the gas, liquid and solid phases, (2S,3S)-dl-3-chloro-2-fluoropentane and (2S,3S)dl-2-chloro-3-fluoropentane were prepared stereospecifically from cis-2-pentane. The purified diastereomers were individually activated by thermal neutrons, and the 38 Cl-labeled substitution products separated by capillary-radio-gas chromatography. Two substitution reactions pathways were found. Retention of configuration was determined to be the dominant pathway for 38 Cl-for-X (X = Cl,F) substitution reactions. The percent retention of configuration in the 38 Cl-for-Cl substitution was found to be phase-dependent, while the 38 Cl-for-F substitution was found to be relatively phase-independent

  4. Single Pellet String Reactor for Intensification of Catalyst Testing in Gas/Liquid/Solid Configuration Réacteur catalytique de type “filaire” pour l’intensification de tests catalytiques en configuration gaz/liquide/solide

    Directory of Open Access Journals (Sweden)

    Hipolito A.I.

    2010-09-01

    has been shown that the pressure drop is controlled by the liquid/solid friction surface and that the pressure drop is not a limiting parameter in the reactor’s operation (values always lower than 0.1 bar. So, from a hydrodynamic point of view, this new reactor exhibits characteristics suitable for its use in catalytic tests. Finally, this reactor was implemented under reaction conditions to study hydrogenation reactions with a real industrial catalyst. The selective hydrogenation of allene was studied. The string reactor was shown to run isothermal kinetic tests with a very small amount of industrial-sized catalyst particles (less than 2 cc and to explore kinetics of fast reaction at high space velocities impossible to achieve in standard fixed bed units with appropriate hydrodynamic conditions. For constant residence time, the allene conversion does not vary with pressure and feed flow rate, which confirms that the string reactor allows one to perform catalytic tests with such a fast reaction without external mass transfer resistance. L’optimisation du catalyseur est une etape cle pour l’optimisation d’un procede catalytique du point de vue des rendements, de l’efficacite energetique et de la selectivite des reactions. La strategie de developpement d’un catalyseur comprend des tests effectues sur des reacteurs pilotes avec des charges reelles ou modeles. Cette etape a fait l’objet de nombreuses etudes ces dernieres decennies portant sur le dimensionnement des reacteurs, l’amelioration des outils d’analyses et les procedures operatoires. La plupart des etudes ont pour but de determiner l’activite catalytique de catalyseur sous forme de grain dans des conditions isothermes de facon a pouvoir determiner les parametres cinetiques de la reaction. Avec l’optimisation des catalyseurs, les flux de transfert de matieres externes aux grains peuvent devenir l’etape limitante, dans les reacteurs de laboratoire standard, par rapport aux flux de reaction

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

    International Nuclear Information System (INIS)

    Minemura, Kiyoshi; Yamashita, Masato

    2000-01-01

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

  6. Global weak solutions for a compressible gas-liquid model with well-formation interaction

    Science.gov (United States)

    Evje, Steinar

    The objective of this work is to explore a compressible gas-liquid model designed for modeling of well flow processes. We build into the model well-reservoir interaction by allowing flow of gas between well and formation (surrounding reservoir). Inflow of gas and subsequent expansion of gas as it ascends towards the top of the well (a so-called gas kick) represents a major concern for various well operations in the context of petroleum engineering. We obtain a global existence result under suitable assumptions on the regularity of initial data and the rate function that controls the flow of gas between well and formation. Uniqueness is also obtained by imposing more regularity on the initial data. The key estimates are to obtain appropriate lower and upper bounds on the gas and liquid masses. For that purpose we introduce a transformed version of the original model that is highly convenient for analysis of the original model. In particular, in the analysis of the transformed model additional terms, representing well-formation interaction, can be treated by natural extensions of arguments that previously have been employed for the single-phase Navier-Stokes model. The analysis ensures that transition to single-phase regions do not appear when the initial state is a true gas-liquid mixture.

  7. 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.

  8. Fluid dynamics of gas-liquid bubble columns

    NARCIS (Netherlands)

    Delnoij, E.

    1999-01-01

    Gas-liquid bubble columns are used extensively in the process industries. The gas-liquid twophase flow prevailing in this type of process equipment is extremely complex, inherently unsteady and dominated by phenomena with widely varying time- and length-scales. it is for this reason that many

  9. Thermal transistor utilizing gas-liquid transition

    KAUST Repository

    Komatsu, Teruhisa S.

    2011-01-25

    We propose a simple thermal transistor, a device to control heat current. In order to effectively change the current, we utilize the gas-liquid transition of the heat-conducting medium (fluid) because the gas region can act as a good thermal insulator. The three terminals of the transistor are located at both ends and the center of the system, and are put into contact with distinct heat baths. The key idea is a special arrangement of the three terminals. The temperature at one end (the gate temperature) is used as an input signal to control the heat current between the center (source, hot) and another end (drain, cold). Simulating the nanoscale systems of this transistor, control of heat current is demonstrated. The heat current is effectively cut off when the gate temperature is cold and it flows normally when it is hot. By using an extended version of this transistor, we also simulate a primitive application for an inverter. © 2011 American Physical Society.

  10. A single-phase all-solid-state lithium battery based on Li1.5Cr0.5Ti1.5(PO4)3for high rate capability and low temperature operation.

    Science.gov (United States)

    Inoishi, Atsushi; Nishio, Akira; Yoshioka, Yuto; Kitajou, Ayuko; Okada, Shigeto

    2018-03-28

    We report a battery made from a single material using Li 1.5 Cr 0.5 Ti 1.5 (PO 4 ) 3 as the anode, cathode and electrolyte. A high rate capability at room temperature and very low-temperature operation (233 K) were possible as a result of the superior ionic conductivity and low interfacial resistance obtained from the single-phase cell design.

  11. Application of the penetration theory for gas - Liquid mass transfer without liquid bulk : Differences with system with a bulk

    NARCIS (Netherlands)

    van Elk, E. P.; Knaap, M. C.; Versteeg, G. F.

    2007-01-01

    Frequently applied micro models for gas-liquid mass transfer all assume the presence of a liquid bulk. However, some systems are characterized by the absence of a liquid bulk, a very thin layer of liquid flows over a solid surface. An example of such a process is absorption in a column equipped with

  12. MIGRATION OF GAS-LIQUID INCLUSIONS IN KCl AND NaCl SINGLE CRYSTALS

    Energy Technology Data Exchange (ETDEWEB)

    Olander, Donald R.; Machiels, Albert J.; Muchowski, Eugen

    1980-08-01

    Natural salt deposits contain small brine inclusions which can be set into motion by a temperature gradient arising from storage of nuclear wastes in the salt. Inclusions totally filled with liquid move up the temperature gradient, but cavities which are filled partly with liquid and partly by an insoluble gas move in the opposite direction. The velocities of these gas-liquid inclusions are calculated from a model which includes: heat transport in the gas/liquid/solid composite medium; vapor transport of water in the gas bubble as the principal mechanism causing cavity motion; and the effect of molecular and thermal diffusion on transport of salt in the liquid phase. An analytical expression for the inclusion velocity is obtainable with certain simplifications, which include: approximating the cubical cavity in the solid as a spherical hole containing a central gas bubble and an annular shell of liquid; neglecting interface kinetics (i.e., slow dissolution and crystallization steps) and assuming the process to be diffusion-controlled and disregarding fluid motion generated by surface tension gradients at the gas/liquid interface. The theory predicts a change in the migration direction at a critical volume fraction gas in the cavity. For gas fractions greater than this critical value, the theory gives the velocities of migration down the temperature gradient which are in satisfactory agreement with available experimental data.

  13. Gas-liquid transfer of aroma compounds during winemaking fermentations

    OpenAIRE

    Mouret, J. R.; Morakul, S.; Nicolle, P.; Athes, V.; Sablayrolles, J. M.

    2012-01-01

    We precisely monitored the production kinetics of 16 volatile carbon compounds corresponding to the predominant higher alcohols and esters produced during the alcoholic fermentation of wine using an online GC system. We studied the gas-liquid partitioning of isobutanol, isoamyl acetate and ethyl hexanoate and showed that CO2 stripping had no impact on the partition coefficient (k(i)). We formulated a predictive model for k(i) changes during the fermentation and calculated the gas-liquid balan...

  14. Gas-liquid separator and method of operation

    Science.gov (United States)

    Soloveichik, Grigorii Lev [Latham, NY; Whitt, David Brandon [Albany, NY

    2009-07-14

    A system for gas-liquid separation in electrolysis processes is provided. The system includes a first compartment having a liquid carrier including a first gas therein and a second compartment having the liquid carrier including a second gas therein. The system also includes a gas-liquid separator fluidically coupled to the first and second compartments for separating the liquid carrier from the first and second gases.

  15. Hollow fiber membrane contactor as a gas-liquid model contactor

    OpenAIRE

    Dindore, V. Y.; Brilman, D. W. F.; Versteeg, G. F.

    2005-01-01

    Microporous hollow fiber gas-liquid membrane contactors have a fixed and well-defined gas-liquid interfacial area. The liquid flow through the hollow fiber is laminar, thus the liquid side hydrodynamics are well known. This allows the accurate calculation of the fiber side physical mass transfer coefficient from first principles. Moreover, in the case of gas-liquid membrane contactor, the gas-liquid exposure time can be varied easily and independently without disturbing the gas-liquid interfa...

  16. Synthesis and magnetic properties of single phase titanomagnetites

    Energy Technology Data Exchange (ETDEWEB)

    Schoenthal, W., E-mail: wms@andrew.cmu.edu; Liu, X.; Cox, T.; Laughlin, D. E.; McHenry, M. E. [Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Mesa, J. L.; Diaz-Michelena, M. [Instituto Nacional de Tecnica Aeroespacial, Madrid (Spain); Maicas, M. [Universidad Politecnica de Madrid, ISOM-ETSIT, Madrid (Spain)

    2014-05-07

    The focus of this paper is the study of cation distributions and resulting magnetizations in titanomagnetites (TMs), (1−x)Fe{sub 3}O{sub 4−x}Fe{sub 2}TiO{sub 4} solid solutions. TM remnant states are hypothesized to contribute to planetary magnetic field anomalies. This work correlates experimental data with proposed models for the TM pseudobinary. Improved synthesis procedures are reported for single phase Ulvöspinel (Fe{sub 2}TiO{sub 4}), and TM solid solutions were made using solid state synthesis techniques. X-ray diffraction and scanning electron microscopy show samples to be single phase solid solutions. M-H curves of TM75, 80, 85, 90, and 95 (TMX where X = at. % of ulvöspinel) were measured using a Physical Property Measurement System at 10 K, in fields of 0 to 8 T. The saturation magnetization was found to be close to that predicted by the Neel model for cation distribution in TMs. M-T curves of the remnant magnetization were measured from 10 K to 350 K. The remnant magnetization was acquired at 10 K by applying an 8 T field and then releasing the field. Experimental Neel temperatures are reported for samples in the Neel model ground state.

  17. Gas-liquid flow filed in agitated vessels

    International Nuclear Information System (INIS)

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

    2001-01-01

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

  18. 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.

  19. Preparation of single phase molybdenum boride

    International Nuclear Information System (INIS)

    Camurlu, Hasan Erdem

    2011-01-01

    Highlights: → Formation of Mo and a mixture of molybdenum boride phases take place in preparation of molybdenum borides. → It is intricate to prepare single phase molybdenum borides. → Formation of single phase MoB from MoO 3 + B 2 O 3 + Mg mixtures has not been reported previously. → Single phase MoB was successfully prepared through a combination of mechanochemical synthesis and annealing process. - Abstract: The formation of MoB through volume combustion synthesis (VCS), and through mechanochemical synthesis (MCS) followed by annealing has been investigated. MoO 3 , B 2 O 3 and Mg were used as reactants while MgO and NaCl were introduced as diluents. Products were leached in dilute HCl solution and were subjected to X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) examinations. Mo was the major phase component in the VCS products under all the experimental conditions. Mo 2 B, MoB, MoB 2 and Mo 2 B 5 were found as minor phases. Products of MCS contained a mixture of Mo 2 B, MoB, MoB 2 and Mo. After annealing the MCS product at 1400 deg. C for 3 h, single phase α-MoB was obtained.

  20. Single phase induction motor with starting performance

    Energy Technology Data Exchange (ETDEWEB)

    Popescu, M.; Demeter, E. [Research Institute for Electrical Machines, ICPE-ME, Bucharest (Romania); Navrapescu, V. [University `Politehnica` Bucharest, Electrical Engineering Faculty Splaiul Independentei, Bucharest (Romania)

    1997-12-31

    The paper presents problems related to a special type of single phase induction motor. The main novelty consists in the use of a conducting (aluminium casted) shell distributed on the periferic region of the rotor. As a result the starting performance, as well as the rated ones, is much improved in comparison with the conventional construction. (orig.) 4 refs.

  1. Generation of Local Concentration Gradients by Gas-Liquid Contacting

    NARCIS (Netherlands)

    de Jong, J.; Verheijden, Pascal W.; Lammertink, Rob G.H.; Wessling, Matthias

    2008-01-01

    We present a generic concept to create local concentration gradients, based on the absorption of gases or vapors in a liquid. A multilayer microfluidic device with crossing gas and liquid channels is fabricated by micromilling and used to generate multiple gas-liquid contacting regions, separated by

  2. Computational fluid dynamics applied to gas-liquid contactors.

    NARCIS (Netherlands)

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

    1997-01-01

    In this paper a `hierarchy of models¿ is discussed to study the fluid dynamic behaviour of gas-liquid bubble columns. This `hierarchy of models¿ consists of a Eulerian-Eulerian two fluid model, a Eulerian-Lagrangian discrete bubble model and a Volume Tracking or Marker Particle model. These models

  3. 21 CFR 862.2250 - Gas liquid chromatography system for clinical use.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Gas liquid chromatography system for clinical use... Instruments § 862.2250 Gas liquid chromatography system for clinical use. (a) Identification. A gas liquid chromatography system for clinical use is a device intended to separate one or more drugs or compounds from a...

  4. Visualization of velocity field and phase distribution in gas-liquid two-phase flow by NMR imaging

    International Nuclear Information System (INIS)

    Matsui, G.; Monji, H.; Obata, J.

    2004-01-01

    NMR imaging has been applied in the field of fluid mechanics, mainly single phase flow, to visualize the instantaneous flow velocity field. In the present study, NMR imaging was used to visualize simultaneously both the instantaneous phase structure and velocity field of gas-liquid two-phase flow. Two methods of NMR imaging were applied. One is useful to visualize both the one component of liquid velocity and the phase distribution. This method was applied to horizontal two-phase flow and a bubble rising in stagnant oil. It was successful in obtaining some pictures of velocity field and phase distribution on the cross section of the pipe. The other is used to visualize a two-dimensional velocity field. This method was applied to a bubble rising in a stagnant water. The velocity field was visualized after and before the passage of a bubble at the measuring cross section. Furthermore, the distribution of liquid velocity was obtained. (author)

  5. Design and Control of a 13.2 kV/10 kVA Single-Phase Solid-State-Transformer with 1.7 kV SiC Devices

    Directory of Open Access Journals (Sweden)

    Jeong-Woo Lim

    2018-01-01

    Full Text Available This paper describes the power stage design, control, and performance evaluation of a 13.2 kV/10 kVA solid-state-transformer (SST for a power distribution system. The proposed SST consists of 10 modules where each individual module contains a unidirectional three-level power factor correction (PFC converter for the active-front-end (AFE stage and an LLC resonant converter for the isolated DC-DC stage. The operating principles of the converters are analyzed and the modulation and the control schemes for the entire module are described in detail. The DC-link voltage imbalance is also less than other SST topologies due to the low number of uncontrollable switching states. In order to simplify the control of the power stage, a modulation strategy for the AFE stage is proposed, and the modulation frequency of the LLC converter is also fixed. In addition, a compensation algorithm is suggested to eliminate the current measurement offset in the AFE stage. The proposed SST achieves the unity power factor at the input AC current regardless of the reactive or nonlinear load and a low voltage regulation at the AC output. In order to verify the effectiveness of the SST, the 13.2 kV/10 kV SST prototype is built and tested. Both the simulation and the experimental results under actual 13.2 kV line show the excellent performance of the proposed SST scheme.

  6. The gas-liquid mass transfer coefficient (k(L)a) in the gas-liquid Multi-stage Agitated Contactor (MAC)

    NARCIS (Netherlands)

    Breman, B.B; Beenackers, A.A C M; Bouma, M.J; VanderWerf, M.H.

    1996-01-01

    Data on the volumetric liquid-side gas-liquid mass transfer coefficient, k(L)a, in a Multi-stage Agitated Contractor (MAC) are reported for three gas-liquid systems (air-water, helium-n-octane, and air-Monoethylene Glycol (MEG)). k(L)a (s(-1)) was determined using a dynamic method with moderately

  7. Instability of single-phase natural circulation

    International Nuclear Information System (INIS)

    Xie Heng; Zhang Jinling; Jia Dounan

    1997-01-01

    The author has investigated the instability of single-phase flows in natural circulation loops. The momentum equation and energy equation are made dimensionless according to some definitions, and some important dimensionless parameters are gotten. The authors decomposed the mean mass flowrate and temperature into a steady solution and a small disturbance equations. Through solving the disturbance equations, the authors get the neutral stability curves. The authors have studied the effect of the two parameters which represent the ratio of buoyancy force to the friction loss in the loop on the stability of loops. The authors also have studied the effect of the difference of height between the center of heat source and the heat sink on the stability

  8. About the statistical description of gas-liquid flows

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-09-01

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

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

    International Nuclear Information System (INIS)

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

    1980-01-01

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

  10. Searching for Next Single-Phase High-Entropy Alloy Compositions

    Directory of Open Access Journals (Sweden)

    David E. Alman

    2013-10-01

    Full Text Available There has been considerable technological interest in high-entropy alloys (HEAs since the initial publications on the topic appeared in 2004. However, only several of the alloys investigated are truly single-phase solid solution compositions. These include the FCC alloys CoCrFeNi and CoCrFeMnNi based on 3d transition metals elements and BCC alloys NbMoTaW, NbMoTaVW, and HfNbTaTiZr based on refractory metals. The search for new single-phase HEAs compositions has been hindered by a lack of an effective scientific strategy for alloy design. This report shows that the chemical interactions and atomic diffusivities predicted from ab initio molecular dynamics simulations which are closely related to primary crystallization during solidification can be used to assist in identifying single phase high-entropy solid solution compositions. Further, combining these simulations with phase diagram calculations via the CALPHAD method and inspection of existing phase diagrams is an effective strategy to accelerate the discovery of new single-phase HEAs. This methodology was used to predict new single-phase HEA compositions. These are FCC alloys comprised of CoFeMnNi, CuNiPdPt and CuNiPdPtRh, and HCP alloys of CoOsReRu.

  11. The Hydrodynamic Characteristics of Cocurrent Downflow and Cocurrent Upflow Gas-Liquid-Solid Catalytic Fixed Bed Reactors: the Effect of Pressure Les caractéristiques hydrodynamiques des réacteurs gaz-liquide-solide à lit de catalyseur fixe à écoulement cocourant montant et descendant : l'influence de la pression

    Directory of Open Access Journals (Sweden)

    Wild G.

    2006-11-01

    Full Text Available While most catalytic fixed bed gas-liquid reactors of the petrol industry work at quite high pressures, the academic scientific work in this field concerned itself almost exclusively with the domain of approximatively atmospheric pressures. The authors present the results of some years of experimental investigations on the hydrodynamic characteristics of trickle bed reactors and lately of cocurrent upflow reactors. During the last years, results were also obtained under pressures up to 8 MPa. The measurements were made in a small scale cold flow equipment (diameter 23 mm. Different aqueous and organic more or less viscous, eventually coalescence inhibiting liquids, four gases and a number of non porous more or less wettable particles were used. The liquid holdup was determined in all cases by measuring liquid phase residence time distribution by different tracers. The following conclusions may be drawn:(a In the high interaction regime, it is the inertia of the gas and the liquid phases which is the main cause of the dissipation of mechanical energy. In this regime, results obtained in cocurrent upflow and downflow are approximately equal. (b Most correlations of literature are unable to predict the effect of pressure on the pressure drop or the liquid holdup. (c The gas viscosity has no influence on the hydrodynamics. It is therefore possible to simulate for example hydrogen under high pressure conditions by another gas of the same density (at a much lower pressures. A critical evaluation of the correlations and/or models of literature is presented, concerning their ability to represent the different characteristics as a function of pressure. Tandis que la plupart des réacteurs industriels gaz-liquide à lit de catalyseur fixe fonctionnent à assez hautes pressions, les travaux scientifiques académiques sont, dans ce domaine, presque exclusivement consacrés aux pressions avoisinant la pression atmosphérique. Les auteurs présentent les r

  12. Centrifugal pumping of gas-liquid mixtures: a mechanistic approach

    Energy Technology Data Exchange (ETDEWEB)

    Estevam, Valdir [PETROBRAS, Rio de Janeiro, RJ (Brazil); Franca, Fernando A. [Universidade Estadual de Campinas, SP (Brazil); Alhanati, Francisco J.S. [C-Fer Technologies, Edmonton, Alberta (Canada)

    2004-07-01

    Centrifugal pumps are known to show a 'surging' behavior at certain conditions of free gas and liquid flow rate at the intake. In the 'surging region' on a pump characteristic curve, the head generated is significantly lower than if the pump were handling a gas-liquid homogeneous mixture. The surging happens, as one shows in this paper, due to the existence of a gas pocket, referred as 'elongated bubble', at the pump impeller inlet region. Therefore, to be able to predict the performance of centrifugal pumps under two-phase conditions, one has to disclose and model the mechanisms that set existence of the elongated bubble at the impeller inlet, besides calculating its length inside the impeller. This paper reports on the results of experimental and mechanistic modelling work conducted with the objective of better predicting the gas-liquid performance of centrifugal pumps under all range of conditions, including those characterized by 'surging'. The focus was on small diameter centrifugal pumps used to produce oil wells. A mechanistic two-fluid model devised to calculate the head generated by the pump was developed. The predictions of the model show good agreement with data collected for this study, and with data recently collected by other research organizations. (author)

  13. U.S. natural gas liquids supply and demand

    International Nuclear Information System (INIS)

    Urquhart, W.L.

    1996-01-01

    United States supply and demand situation for natural gas liquids (NGL) was reviewed. The presentation was in four parts: (1) key assumptions for U.S. NGL supply and demand, (2) specific balances for ethane, propane, and butane, (3) some of the key changes now occurring at the customer level, and how these might affect NGLs, and (4) a suggestion of where the future might deviate from projections so severely that projections could be fundamentally wrong. Despite such 'exogenous variables' higher demand projections downstream in the chemical industry were said to be appearing, albeit in scattered fashion. It was estimated that even fractionally higher economic growth could add 3.5 billion pounds to ethylene demand in the USA in the year 2005. 15 figs

  14. Transport evaluation of a gas-liquid scrubber

    International Nuclear Information System (INIS)

    Brodner, A.J.; Bistline, J.E.; Weber, S.E.

    1982-10-01

    The hydraulics and the mass-transfer behavior of a five-tray, single-bubble-cap, single-downcomer, gas-liquid contactor were studied for use as a gas scrubber. Flooding was not observed at the maximum available liquid and gas flow rates of 0.32 and 464 L/min, respectively. The maximum liquid entrainment was 33% at a gross liquid flow rate of 0.05 L/min. The Murphree-tray efficiencies for absorption of CO 2 (5000 ppM in air) into demineralized water ranged from 0.14 to 0.74 for volumetric liquid-to-gas ratios of 4 x 10 -4 and 2 x 10 -4 , respectively, for k/sub L/a values ranging from 0.088 to 0.36 min -1 . 12 figures, 10 tables

  15. Hollow fiber membrane contactor as a gas-liquid model contactor

    NARCIS (Netherlands)

    Dindore, V. Y.; Brilman, D. W. F.; Versteeg, G. F.

    2005-01-01

    Microporous hollow fiber gas-liquid membrane contactors have a fixed and well-defined gas-liquid interfacial area. The liquid flow through the hollow fiber is laminar, thus the liquid side hydrodynamics are well known. This allows the accurate calculation of the fiber side physical mass transfer

  16. Canadian natural gas liquids : market outlook 2000 - 2010

    International Nuclear Information System (INIS)

    Gill, L.; Mortensen, P.

    2001-01-01

    This study provides a comprehensive analysis of the availability of Canadian natural gas liquids. The analysis was developed from production profiles and gas compositions for individual gas pools and takes into account the effects of market factors. On the demand side, the effects of new infrastructure and changes in corporate structures have been evaluated. The study was initiated at a time when energy prices were stable and the major concern was to see how the addition of the Alliance pipeline, the Aux Sable gas processing plant, the Empress V straddle plant and the Nova/UCC E3 ethylene plant would affect the Canadian liquids business. The study was complicated by the advent of unexpected factors affecting the supply and demand of natural gas liquids (NGLs). These included extremely high prices for natural gas, an apparent inability of the supply basin to respond to the high gas prices with increased supply, and the very high electricity costs in Alberta. The weak supply of NGLs coincides with the increase in ethane demand from the start-up of Alberta's fourth ethylene facility and the addition of the high vapour pressure Alliance pipeline. This weak supply suggests there will be an ethane shortage for at least the next few years. The longer term outlook, however, is less certain and will require an analysis of the outlook for gas production, gas composition and NGL extraction capacity. This study developed two forecasts for natural gas prices. Both presume rising gas demand across North America driven by increased gas use for power generation. The Low Case assumes modest growth in domestic Canadian gas demand and the High case predicts strong growth in domestic demand as higher levels of exports to the United States, resulting in a doubling in growth for Canadian gas production from 2000-2015 compared to the Low Case. Both High and Low Case scenarios suggest that prices will decline from current levels so that Alberta plant gate prices fall by 2005 and will then

  17. 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

  18. Outlook for natural gas liquids sales in North America

    International Nuclear Information System (INIS)

    Anderson, A.B.

    1991-01-01

    The outlook for natural gas liquids (NGL) markets in North America is forecast, with a focus on NGL sourced from Canada. The supply of NGL from Canada is first discussed, showing that Canadian NGL production is typically a function of natural gas production. Over the period ending in the year 2001, Canadian propane and butanes production is expected to peak at ca 275,000 bbl/d and ethane at ca 175,000 bbl/d. The processing, transport, and storage infrastructure for NGL in Canada has been regarded as being matured. A historical overview of the NGL market has shown large swings in demand, linked to such factors as crude oil prices and the drop in butanes demand caused by changes in gasoline specifications in the USA. On the other hand, oxygenates required for reformulated gasolines need butanes as a raw material for their manufacture, signifying a new market for butanes when such gasolines are mandated in clean air programs. Prospects for propane are good in the transportation market because of its clean burning properties. Prospects for expanding ethylene production are favorable to NGL producers; major Canadian petrochemical producers are located close to the source of ethane and petrochemical demand for ethane is forecast to increase by 40,000 bbl/d due to a new plant coming on line and to larger exports to the USA. Results of some forecasts of Canadian propane, butane, and ethane supply and demand are included. 8 figs

  19. Physical investigation of square cylinder array dynamical response under single-phase cross-flow

    International Nuclear Information System (INIS)

    Longatte, E.; Baj, F.

    2014-01-01

    Fluid structure interaction and flow-induced vibration in square cylinder arrangement under single-phase incompressible laminar cross flow are investigated in the present paper. Dynamic instability governed by damping generation is studied without any consideration about mixing with turbulence effects. Conservative and non-conservative effects are pointed out and dynamical stability limit sensitivity to physical parameters is analyzed. Finally the influence of key physical parameters on fluid solid dynamics interaction is quantified. (authors)

  20. A re-look at critical factors influencing single-phase formation of Ba2 ...

    Indian Academy of Sciences (India)

    TECS

    BaSnO3, B2O3 etc, single-phase 2: 9 has been achieved through solid-state route (Yu et al 1994; Lin and Robert. 1999; Wang et al 2003). It is recorded in literature that phase pure 2:9 ceramics without any stabilizing agent will result in better material for microwave dielectric applica- tions (Lin et al 1997; Lin and Robert ...

  1. 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.

  2. Current Harmonics from Single-Phase Grid-Connected Inverters

    DEFF Research Database (Denmark)

    Yang, Yongheng; Zhou, Keliang; Blaabjerg, Frede

    2016-01-01

    factor, or in the low voltage ride through mode with reactive current injection. In this paper, the mechanism of the harmonic current injection from grid-connected single-phase inverter systems is thus explored, and the analysis is conducted on single-phase PV systems. In particular, the analysis......-phase applications as a promising harmonic mitigation solution. Experiments on single-phase grid-connected systems have verified the correctness of the relevant analysis and also the effectiveness of the tailor-made control solution in terms of good harmonic mitigation....

  3. 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.

  4. Natural gas liquids markets in the United States

    International Nuclear Information System (INIS)

    Anderson, W.E.

    1991-01-01

    Changes in natural gas liquids (NGL) markets in the USA, brought about primarily by environmental issues and actions, are reviewed. Three aspects of the Clean Air Act amendments are exerting a powerful influence on NGL product demands. Regulatory limits on Reed vapor pressure (RVP) reduce the amount of evaporative hydrocarbon emissions, and lower-RVP gasoline is leaner in the more volatile hydrocarbons. This means primarily a lower n-butane content, and during the 1990-91 summer blending season it is estimated that half of total U.S. gas plant production of n-butane was being eliminated from the traditional refinery blending market. N-butane prices fell, making n-butane attractive as a petrochemical feedstock. Regulatory requirements for reformulated and oxygenated gasolines, for which methyl tertiary butyl ether (MTBE) will be the largest single source of oxygenate, have increased demand for NGL butanes used as the basic raw material in MBTE manufacture. This demand should increase enough to absorb all the n-butane dislodged from the gasoline blending market. The amendments also specify that in selected metropolitan areas having severe air quality problems, an alternative fuels program must be established. In the alternative fuels market, propane is already well-established due to favorable economics and proven performance, and significant new demand for propane in metropolitan markets is expected. Ethylene, the basic raw material for plastics manufacture, is mainly derived from NGLs and the continued strong demand for plastics will have a positive effect on the NGL market. NGL product demand profiles and projections are presented in graph form for ethane, propane, butanes, and pentanes plus. 4 figs

  5. Flow visualization and characteristics of vertical gas-liquid bubbly flow around a rectangular cylinder (bubble size effect)

    International Nuclear Information System (INIS)

    Voutsinas, A; Shakouchi, T; Tsujimoto, K; Ando, T

    2009-01-01

    The present study deals with the effect of the bubble size, from small bubble scale to normal scale (d b =0.25∼2.6 mm), on the flow passing through a rectangular cylinder in an upward gas-liquid bubbly flow. Extensive visualization experiments are conducted and a digital camera and a high-speed camera analyzed the flow, while PIV analysis by the volume cross-correlation method is conducted to observe the differences in the flow pattern. In order to further understand the effect of bubble size, the pressure distribution along the pipe and the cylinder surface are measured. From the results taken, the drag force is calculated and compared to the case of single phase-flow. Furthermore, the fluctuation phenomena generating from the Karman vortex street downstream the cylinder are investigated, and how the intensity and frequency are affected by the bubble size and gas fraction is presented. The experiments are conducted under two different Reynolds number Re, and volumetric gas fraction ranging from α v =0∼5%, giving valuable information regarding the changes that occur due to bubble size differences and the relation it has with volumetric gas fraction.

  6. MPC of Single Phase Inverter for PV System

    OpenAIRE

    Irtaza M. Syed; Kaamran Raahemifar

    2014-01-01

    This paper presents a model predictive control (MPC) of a utility interactive (UI) single phase inverter (SPI) for a photovoltaic (PV) system at residential/distribution level. The proposed model uses single-phase phase locked loop (PLL) to synchronize SPI with the grid and performs MPC control in a dq reference frame. SPI model consists of boost converter (BC), maximum power point tracking (MPPT) control, and a full bridge (FB) voltage source inverter (VSI). No PI regula...

  7. Single-phase to three-phase power conversion interface

    Science.gov (United States)

    Wu, Jinn-Chang; Wang, Yung-Shan; Jou, Hurng-Liahng; Lu, Wei-Tso

    2016-07-01

    This study proposes a single-phase to three-phase power conversion interface which converts the power from a single-phase utility to three-phase power for a three-phase load. The proposed single-phase to three-phase power conversion interface comprises a bridge-type switch set, a set of three-phase inductors, a transformer set and a set of three-phase capacitors. A current-mode control controls the switching of bridge-type switch set, to generate a set of nonzero-sequence (NZS) currents and a set of zero-sequence (ZS) currents. The transformer set is used to decouple the NZS currents and the ZS currents. The NZS currents are used to generate a high-quality three-phase voltage that supplies power to a three-phase load. The ZS currents flow to the single-phase utility so that the utility current is sinusoidal and in phase with the utility voltage. Accordingly, only a bridge-type switch set is used in the single-phase to three-phase power conversion interface to simply the power circuit. A prototype is developed and tested to verify the performance of the proposed single-phase to three-phase power conversion interface.

  8. Microgravity Compatible Gas-Liquid Separation using Capillary Pressure Gradients Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An innovative microgravity and hypogravity compatible Gas-Liquid Separator (GLS) is proposed. This novel GLS consists of an ordered array of variable sized water...

  9. Enhanced Membrane System for Recovery of Water from Gas-Liquid Mixtures, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Gas-Liquid separation is an acute microgravity problem. Existing devices use centrifugal motion on microporous membranes to separate the two phases. Centrifugal...

  10. Enhanced Membrane System for Recovery of Water from Gas-Liquid Mixtures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Gas-Liquid separation is an acute microgravity problem. Existing devices use centrifugal motion on microporous membranes to separate the two phases. Centrifugal...

  11. Mass transfer and chemical reaction in gas-liquid-liquid systems

    NARCIS (Netherlands)

    Brilman, Derk Willem Frederik

    1998-01-01

    Gas-liquid-liquid reaction systems may be encountered in several important fields of application as e.g. hydroformylation, alkylation, carboxylation, polymerisation, hydrometallurgy, biochemical processes and fine chemicals manufacturing. However, the reaction engineering aspects of these systems

  12. Gas-liquid chromatography of bacterial fatty acids with a fused-silica capillary column.

    OpenAIRE

    Moss, C W; Dees, S B; Guerrant, G O

    1980-01-01

    The use of flexible, fused-silica capillary column for gas-liquid chromatographic analysis of bacterial fatty acids is illustrated with Propionibacterium acnes, Propionibacterium shermanii, and a standard methyl ester mixture.

  13. Receptivity of a Cryogenic Coaxial Gas-Liquid Jet to Acoustic Disturbances (Briefing Charts)

    Science.gov (United States)

    2014-03-01

    Gas-Liquid Jet to Acoustic Disturbances 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Wegener , Forliti, Leyva...of a Cryogenic Coaxial Gas-Liquid Jet to Acoustic Disturbances 50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference Jeff Wegener , UCLA David Forliti...DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited. Previous injectors (Sophonias, 2012) New injector ( Wegener , 2013) 13Place

  14. Rare-gas liquids - Equation of state and reduced-pressure, reduced-bulk-modulus, and reduced-sound-velocity functions

    Science.gov (United States)

    Schlosser, Herbert

    1990-01-01

    This paper is concerned with verification of the applicability of the Vinet et al. (1987) universal equation of state to the liquid phase of the rare-gas elements under pressure. As previously observed in solids and liquids metals, to a good approximation, in the absence of phase transitions, plots of the logarithms of the reduced pressure function, of the reduced sound velocity, and of the reduced bulk modulus, are all linear functions of 1 - X over the entire experimental pressure range. The results obtained on the rare-gas liquids are comparable in accuracy to those obtained in previous work on solids and liquid metals.

  15. A Novel Single Phase Hybrid Switched Reluctance Motor Drive System

    DEFF Research Database (Denmark)

    Liang, Jianing; Xu, Guoqing; Jian, Linni

    2011-01-01

    phase boost converter is applied to improve the performance of this motor. It is easy to generate a double dclink voltage and dc-link voltage and switch both of them. The voltage of boost capacitor is self balance, so the protective circuit is not need to consider. The fast excitation mode helps hybrid......In this paper, a novel single phase hybrid switched reluctance motor(SRM) drive system is proposed. It integrated a single phase hybrid SRM and a novel single phase boost converter. This motor can reduce the number of phase switch. And the permanent magnet which is used in the motor can improve...... the performance and efficiency of SR motor. However, the inherent characteristic of this motor is that the negative torque is very sensitive with the excitation current near the turn-on angle. The slow excitation current limits the torque generation region and reduces the average torque. Therefore, a novel single...

  16. Ultrafast Switching Superjunction MOSFETs for Single Phase PFC Applications

    DEFF Research Database (Denmark)

    Hernandez Botella, Juan Carlos; Petersen, Lars Press; Andersen, Michael A. E.

    2014-01-01

    This paper presents a guide on characterizing state-of-the-art silicon superjunction (SJ) devices in the 600V range for single phase power factor correction (PFC) applications. The characterization procedure is based on a minimally inductive double pulse tester (DPT) with a very low intrusive...... investigates the latest SJ devices in order to set a reference for future research on improvement over silicon (Si) attained with the introduction of wide bandgap devices in single phase PFC applications. The obtained results show that the latest generation of SJ devices set a new benchmark for its wide...

  17. The Single-Phase ProtoDUNE Technical Design Report

    Energy Technology Data Exchange (ETDEWEB)

    Abi, B. [Univ. of Padova (Italy); et al.

    2017-06-21

    ProtoDUNE-SP is the single-phase DUNE Far Detector prototype that is under construction and will be operated at the CERN Neutrino Platform (NP) starting in 2018. ProtoDUNE-SP, a crucial part of the DUNE effort towards the construction of the first DUNE 10-kt fiducial mass far detector module (17 kt total LAr mass), is a significant experiment in its own right. With a total liquid argon (LAr) mass of 0.77 kt, it represents the largest monolithic single-phase LArTPC detector to be built to date. It's technical design is given in this report.

  18. Application of exergy analysis for improving energy efficiency of natural gas liquids recovery processes

    International Nuclear Information System (INIS)

    Shin, Jihoon; Yoon, Sekwang; Kim, Jin-Kuk

    2015-01-01

    Thermodynamic analysis and optimization method is applied to provide design guidelines for improving energy efficiency and cost-effectiveness of natural gas liquids recovery processes. Exergy analysis is adopted in this study as a thermodynamic tool to evaluate the loss of exergy associated with irreversibility in natural gas liquids recovery processes, with which conceptual understanding on inefficient design feature or equipment can be obtained. Natural gas liquids processes are modeled and simulated within UniSim ® simulator, with which detailed thermodynamic information are obtained for calculating exergy loss. The optimization framework is developed by minimizing overall exergy loss, as an objective function, subject to product specifications and engineering constraints. The optimization is carried out within MATLAB ® with the aid of a stochastic solver based on genetic algorithms. The process simulator is linked and interacted with the optimization solver, in which optimal operating conditions can be determined. A case study is presented to illustrate the benefit of using exergy analysis for the design and optimization of natural gas liquids processes and to demonstrate the applicability of design method proposed in this paper. - Highlights: • Application of exergy analysis for natural gas liquids (NGL) recovery processes. • Minimization of exergy loss for improving energy efficiency. • A systematic optimization framework for the design of NGL recovery processes

  19. Microfluidic Manufacturing of Polymeric Nanoparticles: Comparing Flow Control of Multiscale Structure in Single-Phase Staggered Herringbone and Two-Phase Reactors.

    Science.gov (United States)

    Xu, Zheqi; Lu, Changhai; Riordon, Jason; Sinton, David; Moffitt, Matthew G

    2016-12-06

    We compare the microfluidic manufacturing of polycaprolactone-block-poly(ethylene oxide) (PCL-b-PEO) nanoparticles (NPs) in a single-phase staggered herringbone (SHB) mixer and in a two-phase gas-liquid segmented mixer. NPs generated from two different copolymer compositions in both reactors and at three different flow rates, along with NPs generated using a conventional bulk method, are compared with respect to morphologies, dimensions, and internal crystallinities. Our work, the first direct comparison between alternate microfluidic NP synthesis methods, shows three key findings: (i) NP morphologies and dimensions produced in the bulk are different from those produced in a microfluidic mixer, whereas NP crystallinities produced in the bulk and in the SHB mixer are similar; (ii) NP morphologies, dimensions, and crystallinities produced in the single-phase SHB and two-phase mixers at the lowest flow rate are similar; and (iii) NP morphologies, dimensions, and crystallinities change with flow rate in the two-phase mixer but not in the single-phase SHB mixer. These findings provide new insights into the relative roles of mixing and shear in the formation and flow-directed processing of polymeric NPs in microfluidics, informing future reactor designs for manufacturing NPs of low polydispersity and controlled multiscale structure and function.

  20. Mass transfer in gas-liquid slurry reactors

    NARCIS (Netherlands)

    Beenackers, A.A.C.M.; van Swaaij, Willibrordus Petrus Maria

    1993-01-01

    A critical review is presented on the mass transfer characteristics of gas¿liquid slurry reactors. The recent findings on the influence of the presence of solid particles on the following mass transfer parameters in slurry reactors are discussed: volumetric gas¿liquid mass transfer coefficients

  1. the steady-state performance characteristics of single phase transfer

    African Journals Online (AJOL)

    2012-11-03

    Nov 3, 2012 ... The paper reports the derivation of the steady- state equivalent circuit of a single phase transfer ... series opposition between the two halves of the ma- ..... from its equivalent circuit of fig 6 for different values of slip. Impedance due to forward field. Zf = Rf + jXf = Rr. 2(2s - 1). + jxr. 2. (19) in parallel with jxm. 2.

  2. An Asymmetrical Space Vector Method for Single Phase Induction Motor

    DEFF Research Database (Denmark)

    Cui, Yuanhai; Blaabjerg, Frede; Andersen, Gert Karmisholt

    2002-01-01

    Single phase induction motors are the workhorses in low-power applications in the world, and also the variable speed is necessary. Normally it is achieved either by the mechanical method or by controlling the capacitor connected with the auxiliary winding. Any above method has some drawback which...

  3. Improvement of Torque Production in Single-Phase Induction Motors ...

    African Journals Online (AJOL)

    Existing single phase induction motors exhibit low starting torque. Moreover, during accelerating time and at steady state, they produce a significant level of torque pulsations which gives rise to noise and vibration in the machine. As part of efforts to mitigate these problems, a performance improvement strategy using a PWM ...

  4. A simple output voltage control scheme for single phase wavelet ...

    African Journals Online (AJOL)

    DR OKE

    Wavelet based techniques have been extensively used in various power engineering applications. Recently, wavelet has also been proposed to generate switching signal for single-phase pulse-width-modulated (PWM) dc-ac inverter. The main advantage of the wavelet modulated (WM) scheme is that a single synthesis ...

  5. experimental implementation of single-phase, three-level, sinusoidal

    African Journals Online (AJOL)

    Experimental Implementation of SPWM VSI with R-L Load. 3. Figure 2: Switching pattern of the proposed single-phase, three-level PWM inverter. Figure 3: Prototype setup. (a) Power circuits for both inverters. (b) Logic and Driver circuits. Nigerian Journal of Technology. Vol. 31, No. 1, March 2012.

  6. A single phase photovoltaic inverter control for grid connected system

    Indian Academy of Sciences (India)

    This paper presents a control scheme for single phase grid connected photovoltaic (PV) system operating under both grid connected and isolated grid mode. The control techniques include voltage and current control of grid-tie PV inverter. During grid connected mode, grid controls the amplitude and frequency of the PV ...

  7. Load compensation for single phase system using series active filter ...

    African Journals Online (AJOL)

    In this paper a new control strategy for series active filter has been proposed for improvement of power quality problems in single phase system. Since the non linear loads in the system comprises of both voltage source harmonic and current source harmonic loads and the dominancy of each type of load varies from time to ...

  8. Control of Single-Stage Single-Phase PV inverter

    DEFF Research Database (Denmark)

    Ciobotaru, Mihai; Teodorescu, Remus; Blaabjerg, Frede

    2005-01-01

    In this paper the issue of control strategies for single-stage photovoltaic (PV) inverter is addressed. Two different current controllers have been implemented and an experimental comparison between them has been made. A complete control structure for the single-phase PV system is also presented...

  9. Reaction kinetics of oxygen on single-phase alloys, oxidation of nickel and niobium alloys

    International Nuclear Information System (INIS)

    Lalauze, Rene

    1973-01-01

    This research thesis first addresses the reaction kinetics of oxygen on alloys. It presents some generalities on heterogeneous reactions (conventional theory, theory of jumps), discusses the core reaction (with the influence of pressure), discusses the influence of metal self-diffusion on metal oxidation kinetics (equilibrium conditions at the interface, hybrid diffusion regime), reports the application of the hybrid diffusion model to the study of selective oxidation of alloys (Wagner model, hybrid diffusion model) and the study of the oxidation kinetics of an alloy forming a solid solution of two oxides. The second part reports the investigation of the oxidation of single phase nickel and niobium alloys (phase α, β and γ)

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

    DEFF Research Database (Denmark)

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

    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......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......-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...

  11. Measurement of pressure fluctuation in gas-liquid two-phase vortex street

    International Nuclear Information System (INIS)

    Sun Zhiqiang; Sang Wenhui; Zhang Hongjian

    2009-01-01

    The pressure fluctuation in the wake is an important parameter to characterize the shedding process of gas-liquid two-phase Karman vortex street. This paper investigated such pressure fluctuations in a horizontal pipe using air and water as the tested fluid media. The dynamic signal representing the pressure fluctuation was acquired by the duct-wall differential pressure method. Results show that in the wake of the gas-liquid two-phase Karman vortex street, the frequency of the pressure fluctuation is linear with the Reynolds number when the volume void fraction is within the range of 18%. Moreover, the mean amplitude of the pressure fluctuation decreases with the volume void fraction, and the mean amplitude is larger at higher water flowrates under the same volume void fraction. These findings contribute to an in-depth understanding of the gas-liquid two-phase Karman vortex street.

  12. Numerical Simulation and Analysis of Gas-Liquid Flow in a T-Junction Microchannel

    Directory of Open Access Journals (Sweden)

    Hongtruong Pham

    2012-01-01

    Full Text Available Gas-liquid flow in microchannels is widely used in biomedicine, nanotech, sewage treatment, and so forth. Particularly, owing to the high qualities of the microbubbles and spheres produced in microchannels, it has a great potential to be used in ultrasound imaging and controlled drug release areas; therefore, gas-liquid flow in microchannels has been the focus in recent years. In this paper, numerical simulation of gas-liquid flows in a T-junction microchannel was carried out with computational fluid dynamics (CFD software FLUENT and the Volume-of-Fluid (VOF model. The distribution of velocity, pressure, and phase of fluid in the microchannel was obtained, the pressure distribution along the channel walls was analyzed in order to give a better understanding on the formation of microbubbles in the T-junction microchannel.

  13. [CFD numerical simulation onto the gas-liquid two-phase flow behavior during vehicle refueling process].

    Science.gov (United States)

    Chen, Jia-Qing; Zhang, Nan; Wang, Jin-Hui; Zhu, Ling; Shang, Chao

    2011-12-01

    With the gradual improvement of environmental regulations, more and more attentions are attracted to the vapor emissions during the process of vehicle refueling. Research onto the vehicle refueling process by means of numerical simulation has been executed abroad since 1990s, while as it has never been involved so far domestically. Through reasonable simplification about the physical system of "Nozzle + filler pipe + gasoline storage tank + vent pipe" for vehicle refueling, and by means of volume of fluid (VOF) model for gas-liquid two-phase flow and Re-Normalization Group kappa-epsilon turbulence flow model provided in commercial computational fluid dynamics (CFD) software Fluent, this paper determined the proper mesh discretization scheme and applied the proper boundary conditions based on the Gambit software, then established the reasonable numerical simulation model for the gas-liquid two-phase flow during the refueling process. Through discussing the influence of refueling velocity on the static pressure of vent space in gasoline tank, the back-flowing phenomenon has been revealed in this paper. It has been demonstrated that, the more the flow rate and the refueling velocity of refueling nozzle is, the higher the gross static pressure in the vent space of gasoline tank. In the meanwhile, the variation of static pressure in the vent space of gasoline tank can be categorized into three obvious stages. When the refueling flow rate becomes higher, the back-flowing phenomenon of liquid gasoline can sometimes be induced in the head section of filler pipe, thus making the gasoline nozzle pre-shut-off. Totally speaking, the theoretical work accomplished in this paper laid some solid foundation for self-researching and self-developing the technology and apparatus for the vehicle refueling and refueling emissions control domestically.

  14. Overview of Single-Phase Grid-Connected Photovoltaic Systems

    DEFF Research Database (Denmark)

    Yang, Yongheng; Blaabjerg, Frede

    2017-01-01

    A continuous booming installation of solar photovoltaic (PV) systems has been witnessed worldwide. It is mainly driven by the imperative demand of “clean” power generation from renewables. Grid-connected PV systems will thus become an even more active player in the future mixed power systems, which...... systems. This chapter thus gives an overview of the advancement of power electronics converters in single-phase grid-connected PV systems, being commonly used in residential applications. Demands to single-phase grid-connected PV systems and the general control strategies are also addressed...... are linked together by a vast of power electronics converters and the power grid. In order to achieve a reliable and efficient power generation from PV systems, more stringent demands have been imposed on the entire PV system. It, in return, advances the development of the power converter technology in PV...

  15. Instantaneous power flow determination for single-phase UPFC

    Energy Technology Data Exchange (ETDEWEB)

    Dobrucky, B.; Drozdy, S.; Pokorny, M.; Pavlanin, R. [Zilina Univ., Zilina (Slovakia)

    2007-07-01

    The parallel shunt active filter in a unified power flow conditioner (UPFC) can filter and compensate the reactive power of basic and higher current harmonics. This paper reported on a study in which a new theory of orthogonal transform was used to control a single-phase UPFC system and transform it into a two-axes system. In addition to estimating the load current phase shifts, the study also determined the instantaneous active and reactive powers. The new theory is based on the premise that ordinary single-phase quantity can be complemented by a virtual fictitious phase so that both of them will create an orthogonal system, as is usual in three-phase systems. The theory uses efficient methods of analysis, such as time-sub-optimal determination of fundamental harmonics; average- and/or root-mean-square values; or instantaneous reactive power methods. The load current phase shift can be used to compensate for voltage drops. This paper outlined a practical application of the method in a case of active and reactive power determination for single-phase UPFC. It also presented some examples of the successful simulation experiments results focused on regulation output voltage of UPFC. 9 refs., 13 figs., 1 appendix.

  16. 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.

  17. MULTIFUNCTIONAL ALTERNATIVE ENERGY SYSTEMS ON THE BASIS OF GAS-LIQUID SOLAR COLLECTORS

    Directory of Open Access Journals (Sweden)

    Doroshenko A.V.

    2012-12-01

    Full Text Available The basic circuits of multifunctional solar systems of drainage of air, heating (hot water supply and heating, cooling and air conditioning are developed on the basis of open absorption cycle with direct absorbent regeneration. The basic solutions for new generation of gas-liquid solar collectors are developed.

  18. Density and viscosity behavior of a North Sea crude oil, natural gas liquid, and their mixtures

    DEFF Research Database (Denmark)

    Schmidt, KAG; Cisneros, Sergio; Kvamme, B

    2005-01-01

    to accurately model the saturation pressures, densities, and viscosities of petroleum systems ranging from natural gases to heavy crude oils. The applicability of this overall modeling technique to reproduce measured bubble points, densities, and viscosities of a North Sea crude oil, a natural gas liquid...

  19. Amine-based solvents regeneration in gas-liquid membrane contactor based on asymmetric PVTMS

    NARCIS (Netherlands)

    Volkov, A.V.; Tsarkov, S.E.; Goetheer, E.L.V.; Volkov, V.V.

    2015-01-01

    Asymmetric flat-sheet membranes made of poly(vinyltrimethylsilane) (PVTMS) were studied for the regeneration of amine-based absorption solvents in a membrane gas-liquid contactor at 100°C. It was shown that PVTMS membrane possesses good mechanical and chemical stability in contact with 4 M

  20. Characterisation of Liquid Slugs in Gas-Liquid Taylor Flow in Microchannels

    Czech Academy of Sciences Publication Activity Database

    Záloha, Petr; Křišťál, Jiří; Jiřičný, Vladimír; Völkel, N.; Xuereb, C.; Aubin, J.

    2012-01-01

    Roč. 68, č. 1 (2012), s. 640-649 ISSN 0009-2509 Grant - others:IMPULSE(XE) NMP2-CT-2005-011816 Institutional research plan: CEZ:AV0Z40720504 Keywords : gas-liquid * micro-piv * microreactor Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.386, year: 2012

  1. Gas/liquid sensing via chemotaxis of Euglena cells confined in an isolated micro-aquarium.

    Science.gov (United States)

    Ozasa, Kazunari; Lee, Jeesoo; Song, Simon; Hara, Masahiko; Maeda, Mizuo

    2013-10-21

    We demonstrate on-chip gas/liquid sensing by using the chemotaxis of live bacteria (Euglena gracilis) confined in an isolated micro-aquarium, and gas/liquid permeation through porous polydimethylsiloxane (PDMS). The sensing chip consisted of one closed micro-aquarium and two separated bypass microchannels along the perimeter of the micro-aquarium. Test gas/liquid and reference samples were introduced into the two individual microchannels separately, and the gas/liquid permeated through the PDMS walls and dissolved in the micro-aquarium water, resulting in a chemical concentration gradient in the micro-aquarium. By employing the closed micro-aquarium isolated from sample flows, we succeeded in measuring the chemotaxis of Euglena for a gas substance quantitatively, which cannot be achieved with the conventional flow-type or hydro-gel-type microfluidic devices. We found positive (negative) chemotaxis for CO2 concentrations below (above) 15%, with 64 ppm as the minimum concentration affecting the cells. We also observed chemotaxis for ethanol and H2O2. By supplying culture medium via the microchannels, the Euglena culture remained alive for more than 2 months. The sensing chip is thus useful for culturing cells and using them for environmental toxicity/nutrition studies by monitoring their motion.

  2. Detection of Griseofulvin and Dechlorogriseofulvin by Thin-Layer Chromatography and Gas-Liquid Chromatography

    Science.gov (United States)

    Cole, R. J.; Kirksey, J. W.; Holaday, C. E.

    1970-01-01

    A rapid and accurate method is described for the determination of griseofulvin and dechlorogriseofulvin extracted from Penicillium urticae with chloroform. Thinlayer chromatography was used to tentatively identify griseofulvin or dechlorogriseofulvin, or both. Two gas-liquid chromatographic systems provided additional qualitative information and simultaneous quantitation of the individual compounds. PMID:5415206

  3. Axial liquid mixing in a gas-liquid Multi-Stage Agitated Contactor (MAC)

    NARCIS (Netherlands)

    Breman, B.B; Beenackers, A.A C M; Bouma, M.J; VanderWerf, M.H.

    Data on interstage liquid mixing are reported for a gas-liquid Multi-stage Agitated Contactor (MAC). A dynamic method using heat as a tracer was applied for water, n-octane and monoethylene glycol as liquids both with and without the presence of a dispersed gas phase (air). In all cases, the axial

  4. 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

  5. Residence time distribution of the gas phase in a mechanically agitated gas-liquid reactor

    NARCIS (Netherlands)

    Thijert, M.P.G.; Oyevaar, M.H.; Kuper, W.J.; Westerterp, K.R.

    1992-01-01

    In this study we present a measuring method and extensive experimental data on the gas phase RTD in a mechanically agitated gas-liquid reactor with standard dimensions over a wide range of superficial gas velocities, agitation rates and agitator sizes. The results are modelled successfully, using

  6. Mass transfer accompanied with complete reversible chemical reactions in gas-liquid systems: an overview

    NARCIS (Netherlands)

    van Swaaij, Willibrordus Petrus Maria; Versteeg, Geert

    1992-01-01

    In many processes in the chemical industry mass transfer accompanied with reversible, complex chemical reactions in gas-liquid systems are frequently encountered. In point of view of design purposes it is very important that the absorption rates of the transferred reactants can estimated

  7. Microporous hollow fibre membrane modules as gas-liquid contactors. Part 1. Physical mass transfer processes : A specific application

    NARCIS (Netherlands)

    Kreulen, H.; Versteeg, G.F.; Swaaij, W.P.M. van

    1993-01-01

    Gas-liquid mass transfer has been studied in a membrane module with non-wetted microporous fibres in the laminar flow regime. This new type of gas/liquid contactor can be operated stabily over a large range of gas and liquid flows because gas and liquid phase do not influence each other directly.

  8. 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

  9. Investigation on a Novel Discontinuous Pulse-Width Modulation Algorithm for Single-phase Voltage Source Rectifier

    DEFF Research Database (Denmark)

    Qu, Hao; Yang, Xijun; Guo, Yougui

    2014-01-01

    Single-phase voltage source converter (VSC) is an important power electronic converter (PEC), including single-phase voltage source inverter (VSI), single-phase voltage source rectifier (VSR), single-phase active power filter (APF) and single-phase grid-connection inverter (GCI). Single-phase VSC...

  10. Investigation of effect of single phase electrical faults at LOFT

    International Nuclear Information System (INIS)

    Yeates, J.A.

    1978-01-01

    This LTR presents the general basic engineering facts related to an open phase fault in a three phase power system commonly referred to as a single phase condition. It describes the probable results to electrical motors and describes the LOFT system design factors which minimize the likelihood of such a fault occurring at LOFT. It recognizes that the hazard of such a fault is a realistic threat and notes the types of relays designed to provide protection. Recommendations are made to perform a detailed engineering study to determine the most advantageous protective relay design, and to implement such a design by installation of the necessary devices and controls

  11. Improved PLL structures for single-phase grid inverters

    DEFF Research Database (Denmark)

    Ciobotaru, Mihai; Teodorescu, Remus; Blaabjerg, Frede

    2005-01-01

    of the reference signals. This paper presents two improved phase-locked-loop (PLL) methods for single-phase grid connected systems. The investigated PLL methods are based on a transport delay method and an inverse Park transformation method. The improvements in the case of using the delay-based PLL are: non......-frequency dependent and better filtering of the harmonics. For the other investigated PLL method based on inverse Park transformation the improvement consists of better filtering of the harmonics. Experimental results validate the effectiveness of the two proposed methods....

  12. Dynamics Assessment of Advanced Single-Phase PLL Structures

    DEFF Research Database (Denmark)

    Golestan, Saeed; Monfarad, Mohammad; Freijedo, Francisco D.

    2013-01-01

    , and desired performance under frequency-varying and harmonically distorted grid conditions. Despite the wide acceptance and use of these two advanced PLLs, no comprehensive design guidelines to fine-tune their parameters have been reported yet. Through a detailed mathematical analysis it is shown......Recently, several advanced phase locked loop (PLL) techniques have been proposed for single-phase applications. Among these, the Park-PLL, and the second order generalized integrator (SOGI) based PLL are very attractive, owing to their simple digital implementation, low computational burden...

  13. Solution Concept of Modular Single Phase Active Power Filters

    Directory of Open Access Journals (Sweden)

    Marek Roch

    2006-01-01

    Full Text Available This paper investigates a modular or a decentralised single-phase active power filter control strategy. It is based on the evaluation of the harmonic reference load currents for the active power filter blocks operating under specific harmonic frequencies. The underlying principle of the modular active power filter is explained and it is shown how the required reference harmonic currents can be evaluated. Simulation results demonstrated the improvement in the dynamic performance of the modular active power filter presented here in comparison with the conventional type.

  14. A Transformer-less Single Phase Inverter For photovoltaic Systems

    DEFF Research Database (Denmark)

    Mostaan, Ali; Alizadeh, Ebrahim; Qu, Ying

    2017-01-01

    A single phase transformer-less inverter is introduced in this paper. The negative polarities of the input voltage and output terminal have common ground. Therefore, the leakage current problem that is common in PV systems is eliminated naturally. In addition, the proposed inverter has fewer...... components compared with its counterparts and only one switch conducts during the active states which enhance the inverter efficiency. The proposed inverter is analyzed in details and compared with some existing topologies. The performance of the proposed inverter is validated using the simulation results....

  15. Numerical simulations of gas-liquid-solid flows in a hydrocyclone separator

    Energy Technology Data Exchange (ETDEWEB)

    Mousavian, S.M.; Najafi, A.F. [Power and Water University of Technology, School of Energy Engineering, P.O. Box: 16765-1719, Tehran (Iran)

    2009-05-15

    The flow behavior in hydrocyclones is quite complex. In this study, the computational fluid dynamics (CFD) method was used to simulate the flow fields inside a hydrocyclone in order to investigate its separation efficiency. In the computational fluid dynamics study of hydrocyclones, the air-core dimension is a key to predicting the mass split between the underflow and overflow. In turn, the mass split influences the prediction of the size classification curve. Three models, the k-{epsilon} model, the Reynolds stress model (RSM) without considering the air-core, and the Reynolds stress turbulence model with the volume of fluid (VOF) multiphase model for simulating the air-core, were compared in terms of their predictions of velocity, axial and tangential velocity distributions, and separation proportion. The RSM with air-core simulation model, since it reproduces some detailed features of the turbulence and multiphase, clearly predicted the experimental data more closely than did the other two models. (orig.)

  16. 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.

  17. Gas-liquid flow splitting in T-junction with inclined lateral arm

    Science.gov (United States)

    Yang, Le-le; Liu, Shuo; Li, Hua; Zhang, Jian; Wu, Ying-xiang; Xu, Jing-yu

    2018-02-01

    This paper studies the gas-liquid flow splitting in T-junction with inclined lateral arm. The separation mechanism of the T-junction is related to the pressure distribution in the T-junction. It is shown that the separation efficiency strongly depends on the inclination angle, when the angle ranges from 0° to 30°, while not so strongly for angles in the range from 30° to 90° Increasing the number of connecting tubes is helpful for the gas-liquid separation, and under the present test conditions, with four connecting tubes, a good separation performance can be achieved. Accordingly, a multi-tube Y-junction separator with four connecting tubes is designed for the experimental investigation. A good agreement between the simulated and measured data shows that there is an optimal split ratio to achieve the best performance for the multi-tube Y-junction separator.

  18. Measurements of interfacial dynamics of gas-liquid displacement in a capillary

    Science.gov (United States)

    Yan, Changfei; Qiu, Huihe

    2016-06-01

    Measurement of liquid film thickness in gas-liquid plug/slug flows is a challenging task. A novel laser interference method for measuring the interfacial film thickness of gas-liquid displacement in a plug flow has been developed. This novel technique utilizes light scattering from different liquid/gas interfaces in forming interference fringes. The interference fringes are used for calculating the film thickness. A set of simultaneous equations is derived based on geometrical optics. The experiment set up is not complex and is easy to install. The fringes are recorded by a charge-coupled device high speed camera and the image data are calculated using fast Fourier transform (FFT) and a non-linear least squares Levenberg-Marquardt algorithm. The uncertainty of this measurement technique is quite small (0.3 μm) and the entire film thickness profile can be measured at the same time.

  19. Phase diagram and universality of the Lennard-Jones gas-liquid system

    KAUST Repository

    Watanabe, Hiroshi

    2012-01-01

    The gas-liquid phase transition of the three-dimensional Lennard-Jones particles system is studied by molecular dynamics simulations. The gas and liquid densities in the coexisting state are determined with high accuracy. The critical point is determined by the block density analysis of the Binder parameter with the aid of the law of rectilinear diameter. From the critical behavior of the gas-liquid coexisting density, the critical exponent of the order parameter is estimated to be β = 0.3285(7). Surface tension is estimated from interface broadening behavior due to capillary waves. From the critical behavior of the surface tension, the critical exponent of the correlation length is estimated to be ν = 0.63(4). The obtained values of β and ν are consistent with those of the Ising universality class. © 2012 American Institute of Physics.

  20. Hollow fiber gas-liquid membrane contactors for acid gas capture: a review.

    Science.gov (United States)

    Mansourizadeh, A; Ismail, A F

    2009-11-15

    Membrane contactors using microporous membranes for acid gas removal have been extensively reviewed and discussed. The microporous membrane acts as a fixed interface between the gas and the liquid phase without dispersing one phase into another that offers a flexible modular and energy efficient device. The gas absorption process can offer a high selectivity and a high driving force for transport even at low concentrations. Using hollow fiber gas-liquid membrane contactors is a promising alternative to conventional gas absorption systems for acid gas capture from gas streams. Important aspects of membrane contactor as an efficient energy devise for acid gas removal including liquid absorbents, membrane characteristics, combination of membrane and absorbent, mass transfer, membrane modules, model development, advantages and disadvantages were critically discussed. In addition, current status and future potential in research and development of gas-liquid membrane contactors for acid gas removal were also briefly discussed.

  1. Efficient gas-liquid contact using microfluidic membrane devices with staggered herringbone mixers.

    Science.gov (United States)

    Femmer, Tim; Eggersdorfer, Max L; Kuehne, Alexander J C; Wessling, Matthias

    2015-08-07

    We describe a novel membrane based gas-liquid-contacting device with increased mass transport and reduced pressure loss by combining a membrane with a staggered herringbone static mixer. Herringbone structures are imposed on the microfluidic channel geometry via soft lithography, acting as mixers which introduce secondary flows at the membrane interface. Such flows include Dean vortices and Taylor flows generating effective mixing while improving mass transport and preventing concentration polarization in microfluidic channels. Furthermore, our static herringbone mixer membranes effectively reduce pressure losses leading to devices with enhanced transfer properties for microfluidic gas-liquid contact. We investigate the red blood cell distribution to tailor our devices towards miniaturised extracorporeal membrane oxygenation and improved comfort of patients with lung insufficiencies.

  2. The spray characteristic of gas-liquid coaxial swirl injector by experiment

    Directory of Open Access Journals (Sweden)

    Chen Chen

    2017-01-01

    Full Text Available Using the laser phase Doppler particle analyzer (PDPA, the spray characteristics of gas-liquid coaxial swirl injector were studied. The Sauter mean diameter (SMD, axial velocity and size data rate were measured under different gas injecting pressure drop and liquid injecting pressure drop. Comparing to a single liquid injection, SMD with gas presence is obviously improved. So the gas presence has a significant effect on the atomization of the swirl injector. What’s more, the atomization effect of gas-liquid is enhanced with the increasing of the gas pressure drop. Under the constant gas pressure drop, the injector has an optimal liquid pressure drop under which the atomization performance is best.

  3. US crude oil, natural gas, and natural gas liquids reserves, 1992 annual report

    Energy Technology Data Exchange (ETDEWEB)

    1993-10-18

    This report presents estimates of proved reserves of crude oil, natural gas, and natural gas liquids as of December 31, 1992, as well as production volumes for the United States, and selected States and State subdivisions for the year 1992. Estimates are presented for the following four categories of natural gas: total gas (wet after lease separation), its two major components (nonassociated and associated-dissolved gas), and total dry gas (wet gas adjusted for the removal of liquids at natural gas processing plants). In addition, two components of natural gas liquids, lease condensate and natural gas plant liquids, have their reserves and production data presented. Also included is information on indicated additional crude oil reserves and crude oil, natural gas, and lease condensate reserves in nonproducing reservoirs. A discussion of notable oil and gas exploration and development activities during 1992 is provided.

  4. Nonequilibrium gas-liquid transition in the driven-dissipative photonic lattice

    Science.gov (United States)

    Biondi, Matteo; Blatter, Gianni; Türeci, Hakan E.; Schmidt, Sebastian

    2017-10-01

    We study the nonequilibrium steady state of the driven-dissipative Bose-Hubbard model with Kerr nonlinearity. Employing a mean-field decoupling for the intercavity hopping J , we find that the steep crossover between low and high photon-density states inherited from the single cavity transforms into a gas-liquid bistability at large cavity-coupling J . We formulate a van der Waals-like gas-liquid phenomenology for this nonequilibrium setting and determine the relevant phase diagrams, including a new type of diagram where a lobe-shaped boundary separates smooth crossovers from sharp, hysteretic transitions. Calculating quantum trajectories for a one-dimensional system, we provide insights into the microscopic origin of the bistability.

  5. US crude oil, natural gas, and natural gas liquids reserves, 1992 annual report

    International Nuclear Information System (INIS)

    1993-01-01

    This report presents estimates of proved reserves of crude oil, natural gas, and natural gas liquids as of December 31, 1992, as well as production volumes for the United States, and selected States and State subdivisions for the year 1992. Estimates are presented for the following four categories of natural gas: total gas (wet after lease separation), its two major components (nonassociated and associated-dissolved gas), and total dry gas (wet gas adjusted for the removal of liquids at natural gas processing plants). In addition, two components of natural gas liquids, lease condensate and natural gas plant liquids, have their reserves and production data presented. Also included is information on indicated additional crude oil reserves and crude oil, natural gas, and lease condensate reserves in nonproducing reservoirs. A discussion of notable oil and gas exploration and development activities during 1992 is provided

  6. Hydrogen extraction from liquid lithium-lead alloy by gas-liquid contact method

    International Nuclear Information System (INIS)

    Xie Bo; Weng Kuiping; Hou Jianping; Yang Guangling; Zeng Jun

    2013-01-01

    Hydrogen extraction experiment from liquid lithium-lead alloy by gas-liquid contact method has been carried out in own liquid lithium-lead bubbler (LLLB). Experimental results show that, He is more suitable than Ar as carrier gas in the filler tower. The higher temperature the tower is, the greater hydrogen content the tower exports. Influence of carrier gas flow rate on the hydrogen content in the export is jagged, no obvious rule. Although the difference between experimental results and literature data, but it is feasible that hydrogen isotopes extraction experiment from liquid lithium-lead by gas-liquid contact method, and the higher extraction efficiency increases with the growth of the residence time of the alloy in tower. (authors)

  7. U.S. crude oil, natural gas, and natural gas liquids reserves 1997 annual report

    Energy Technology Data Exchange (ETDEWEB)

    Wood, John H.; Grape, Steven G.; Green, Rhonda S.

    1998-12-01

    This report presents estimates of proved reserves of crude oil, natural gas, and natural gas liquids as of December 31, 1997, as well as production volumes for the US and selected States and State subdivisions for the year 1997. Estimates are presented for the following four categories of natural gas: total gas (wet after lease separation), nonassociated gas and associated-dissolved gas (which are the two major types of wet natural gas), and total dry gas (wet gas adjusted for the removal of liquids at natural gas processing plants). In addition, reserve estimates for two types of natural gas liquids, lease condensate and natural gas plant liquids, are presented. Also included is information on indicated additional crude oil reserves and crude oil, natural gas, and lease condensate reserves in nonproducing reservoirs. A discussion of notable oil and gas exploration and development activities during 1997 is provided. 21 figs., 16 tabs.

  8. Nonequilibrium Thermodynamics of Hydrate Growth on a Gas-Liquid Interface

    Science.gov (United States)

    Fu, Xiaojing; Cueto-Felgueroso, Luis; Juanes, Ruben

    2018-04-01

    We develop a continuum-scale phase-field model to study gas-liquid-hydrate systems far from thermodynamic equilibrium. We design a Gibbs free energy functional for methane-water mixtures that recovers the isobaric temperature-composition phase diagram under thermodynamic equilibrium conditions. The proposed free energy is incorporated into a phase-field model to study the dynamics of hydrate formation on a gas-liquid interface. We elucidate the role of initial aqueous concentration in determining the direction of hydrate growth at the interface, in agreement with experimental observations. Our model also reveals two stages of hydrate growth at an interface—controlled by a crossover in how methane is supplied from the gas and liquid phases—which could explain the persistence of gas conduits in hydrate-bearing sediments and other nonequilibrium phenomena commonly observed in natural methane hydrate systems.

  9. Receptivity of a Cryogenic Coaxial Gas-Liquid Jet to Acoustic Disturbances

    Science.gov (United States)

    2014-06-01

    Gas-Liquid Jet to Acoustic Disturbances 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Wegener , J; Forliti, D...range of transverse acoustic conditions.4-6 A new experimental facility for reacting coaxial jet flows has been developed as described by Wegener et...the inner and outer injector flows. Further details on the experimental facility can be found in Wegener et al.7 A single coaxial jet injector was

  10. Gas liquid sampling for closed canisters in KW Basin - test plan

    International Nuclear Information System (INIS)

    Pitkoff, C.C.

    1995-01-01

    Test procedures for the gas/liquid sampler. Characterization of the Spent Nuclear Fuel, SNF, sealed in canisters at KW-Basin is needed to determine the state of storing SNF wet. Samples of the liquid and the gas in the closed canisters will be taken to gain characterization information. Sampling equipment has been designed to retrieve gas and liquid from the closed canisters in KW basin. This plan is written to outline the test requirements for this developmental sampling equipment

  11. Micromethod for measuring hexachlorophene in whole blood by gas-liquid chromatography.

    Science.gov (United States)

    Dodson, W E; Tyrala, E E; Hillman, R E

    1977-06-01

    We describe a micromethod for measuring hexachlorophene by use of gas-liquid chromatography with a 63Ni electron capture detector. The procedure requires 100 micronl of blood for extractions of hexachlorophene, and dichlorophene is added as an internal standard. CV is 3.4% over the concentration range of 500 to 1300 microng of hexachlorophene per liter of whole blood. This procedure permits repeated measurements of hexachlorophene in newborns who are being washed with soap containing hexachlorophene.

  12. The spray characteristic of gas-liquid coaxial swirl injector by experiment

    OpenAIRE

    Chen Chen; Zhihui Yan; Yang Yang; Hongli Gao; Shunhua Yang; Lei Zhang

    2017-01-01

    Using the laser phase Doppler particle analyzer (PDPA), the spray characteristics of gas-liquid coaxial swirl injector were studied. The Sauter mean diameter (SMD), axial velocity and size data rate were measured under different gas injecting pressure drop and liquid injecting pressure drop. Comparing to a single liquid injection, SMD with gas presence is obviously improved. So the gas presence has a significant effect on the atomization of the swirl injector. What’s more, the atomization eff...

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

    OpenAIRE

    Zangana, Mohammed Haseeb Sedeeq

    2011-01-01

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

  14. An analytical study by gas liquid chromatography and radiochromatography of tritium labelled lebaycid

    International Nuclear Information System (INIS)

    Perez Garcia, M. M.

    1969-01-01

    The stability and purity of the syntheses products of Lebaycid: 0,0 dime thylfosfochlorothionate and 4 methyl-thio-m-cresol were investigated by gas liquid chromatography. The study on (CH 3 O) 2 PSC1 was made in a column of Silicone SE-30, Reoplex 400 using a thermal conductivity detector. The 99,4% pure product obtained from the preparative gas chromatograph was found to be stable within the duration of the experiment: seven months. (Author) 23 refs

  15. Reducing Electromagnetic Interference in a Grid Tied Single Phase Power Inverter

    Science.gov (United States)

    2016-09-01

    ELECTROMAGNETIC INTERFERENCE IN A GRID TIED SINGLE PHASE POWER INVERTER by Jason Hassan Valiani September 2016 Thesis Advisor: Giovanna Oriti...3. REPORT TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE REDUCING ELECTROMAGNETIC INTERFERENCE IN A GRID TIED SINGLE PHASE POWER...The addition of a passive filter proved to minimize the conducted EMI for a single -phase grid-tied inverter. 14. SUBJECT TERMS single -phase

  16. Modelling of stratified gas-liquid two-phase flow in horizontal circular pipes

    International Nuclear Information System (INIS)

    Sampaio, P.A.B. de; Faccini, J.L.H.; Su, J.

    2006-01-01

    This paper reports numerical and experimental investigation of stratified gas-liquid two-phase flow in horizontal circular pipes. The Reynolds average Navier-Stokes equations (RANS) with κ ω model development stratified gas-liquid two-phase flow are solved by using the finite element methods. A smooth interface surface is assumed without considered the effects of the interfacial waves. The continuity of the shear stress across the interface is enforced with the continuity of the velocity being automatically satisfied by the variational formulation. For it is given position and interface and longitudinal pressure gradient, an inner iteration loop runs to solve nonlinear equations the Newton-Raphson scheme is used to solve the transcendental equations by an outer iteration to determinate the interface position in a 5.2 mm ID circular pipe was measured experimentally by the ultrasonic ultra pulse-echo technique. The numeral were also compared with results in 21 mm ID circular pipe report by Masala (2004). The good agreement between the numerical and experimental results indicates that κ ω model can be applied for the numerical simulation of stratified gas-liquid two phase flow. (author)

  17. Stripping of acetone from water with microfabricated and membrane gas-liquid contactors.

    Science.gov (United States)

    Constantinou, Achilleas; Ghiotto, Francesco; Lam, Koon Fung; Gavriilidis, Asterios

    2014-01-07

    Stripping of acetone from water utilizing nitrogen as a sweeping gas in co-current flow was conducted in a microfabricated glass/silicon gas-liquid contactor. The chip consisted of a microchannel divided into a gas and a liquid chamber by 10 μm diameter micropillars located next to one of the channel walls. The channel length was 35 mm, the channel width was 220 μm and the microchannel depth 100 μm. The micropillars were wetted by the water/acetone solution and formed a 15 μm liquid film between them and the nearest channel wall, leaving a 195 μm gap for gas flow. In addition, acetone stripping was performed in a microchannel membrane contactor, utilizing a hydrophobic PTFE membrane placed between two microstructured acrylic plates. Microchannels for gas and liquid flows were machined in the plates and had a depth of 850 μm and 200 μm respectively. In both contactors the gas/liquid interface was stabilized: in the glass/silicon contactor by the hydrophilic micropillars, while in the PTFE/acrylic one by the hydrophobic membrane. For both contactors separation efficiency was found to increase by increasing the gas/liquid flow rate ratio, but was not affected when increasing the inlet acetone concentration. Separation was more efficient in the microfabricated contactor due to the very thin liquid layer employed.

  18. U.S. crude oil, natural gas, and natural gas liquids reserves 1995 annual report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-11-01

    The EIA annual reserves report series is the only source of comprehensive domestic proved reserves estimates. This publication is used by the Congress, Federal and State agencies, industry, and other interested parties to obtain accurate estimates of the Nation`s proved reserves of crude oil, natural gas, and natural gas liquids. These data are essential to the development, implementation, and evaluation of energy policy and legislation. This report presents estimates of proved reserves of crude oil, natural gas, and natural gas liquids as of December 31, 1995, as well as production volumes for the US and selected States and State subdivisions for the year 1995. Estimates are presented for the following four categories of natural gas: total gas (wet after lease separation), nonassociated gas and associated-dissolved gas (which are the two major types of wet natural gas), and total dry gas (wet gas adjusted for the removal of liquids at natural gas processing plants). In addition, reserve estimates for two types of natural gas liquids, lease condensate and natural gas plant liquids, are presented. Also included is information on indicated additional crude oil reserves and crude oil, natural gas, and lease condensate reserves in nonproducing reservoirs. A discussion of notable oil and gas exploration and development activities during 1995 is provided. 21 figs., 16 tabs.

  19. US crude oil, natural gas, and natural gas liquids reserves 1996 annual report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-01

    The EIA annual reserves report series is the only source of comprehensive domestic proved reserves estimates. This publication is used by the Congress, Federal and State agencies, industry, and other interested parties to obtain accurate estimates of the Nation`s proved reserves of crude oil, natural gas, and natural gas liquids. These data are essential to the development, implementation, and evaluation of energy policy and legislation. This report presents estimates of proved reserves of crude oil, natural gas, and natural gas liquids as of December 31, 1996, as well as production volumes for the US and selected States and State subdivisions for the year 1996. Estimates are presented for the following four categories of natural gas: total gas (wet after lease separation), nonassociated gas and associated-dissolved gas (which are the two major types of wet natural gas), and total dry gas (wet gas adjusted for the removal of liquids at natural gas processing plants). In addition, reserve estimates for two types of natural gas liquids, lease condensate and natural gas plant liquids, are presented. Also included is information on indicated additional crude oil reserves and crude oil, natural gas, and lease condensate reserves in nonproducing reservoirs. A discussion of notable oil and gas exploration and development activities during 1996 is provided. 21 figs., 16 tabs.

  20. Numerical simulation of the gas-liquid interaction of a liquid jet in supersonic crossflow

    Science.gov (United States)

    Li, Peibo; Wang, Zhenguo; Sun, Mingbo; Wang, Hongbo

    2017-05-01

    The gas-liquid interaction process of a liquid jet in supersonic crossflow with a Mach number of 1.94 was investigated numerically using the Eulerian-Lagrangian method. The KH (Kelvin-Helmholtz) breakup model was used to calculate the droplet stripping process, and the secondary breakup process was simulated by the competition of RT (Rayleigh-Taylor) breakup model and TAB (Taylor Analogy Breakup) model. A correction of drag coefficient was proposed by considering the compressible effects and the deformation of droplets. The location and velocity models of child droplets after breakup were improved according to droplet deformation. It was found that the calculated spray features, including spray penetration, droplet size distribution and droplet velocity profile agree reasonably well with the experiment. Numerical results revealed that the streamlines of air flow could intersect with the trajectory of droplets and are deflected towards the near-wall region after they enter into spray zone around the central plane. The analysis of gas-liquid relative velocity and droplet deformation suggested that the breakup of droplets mainly occurs around the front region of the spray where gathered a large number of droplets with different sizes. The liquid trailing phenomenon of jet spray which has been discovered by the previous experiment was successfully captured, and a reasonable explanation was given based on the analysis of gas-liquid interaction process.

  1. US crude oil, natural gas, and natural gas liquids reserves: 1990 annual report

    International Nuclear Information System (INIS)

    1991-09-01

    The primary focus of this report is to provide an accurate estimate of US proved reserves of crude oil, natural gas, and natural gas liquids. These estimates were considered essential to the development, implementation, and evaluation of natural energy policy and legislation. In the past, the government and the public relied upon industry estimates of proved reserves. These estimates were prepared jointly by the American Petroleum Institute (API) and the American Gas Association (AGA) and published in their annual report, Reserves of Crude Oil, Natural Gas Liquids, and Natural Gas in the United States and Canada. However, API and AGA ceased publication of reserves estimates after their 1979 report. By the mid-1970's, various federal agencies had separately established programs to collect data on, verify, or independently estimate domestic proved reserves of crude oil or natural gas. Each program was narrowly defined to meet the particular needs of the sponsoring agency. In response to recognized need for unified, comprehensive proved reserves estimates, Congress in 1977 required the Department of Energy to prepare such estimates. To meet this requirement, the EIA's reserves program was undertaken to establish a unified, verifiable, comprehensive, and continuing statistical series for proved reserves of crude oil and natural gas. The program was expanded to include proved reserves of natural gas liquids in the 1979 report. 36 refs., 11 figs., 16 tabs

  2. Third-order gas-liquid phase transition and the nature of Andrews critical point

    Directory of Open Access Journals (Sweden)

    Tian Ma

    2011-12-01

    Full Text Available The main objective of this article is to study the nature of the Andrews critical point in the gas-liquid transition in a physical-vapor transport (PVT system. A dynamical model, consistent with the van der Waals equation near the Andrews critical point, is derived. With this model, we deduce two physical parameters, which interact exactly at the Andrews critical point, and which dictate the dynamic transition behavior near the Andrews critical point. In particular, it is shown that 1 the gas-liquid co-existence curve can be extended beyond the Andrews critical point, and 2 the transition is first order before the critical point, second-order at the critical point, and third order beyond the Andrews critical point. This clearly explains why it is hard to observe the gas-liquid phase transition beyond the Andrews critical point. Furthermore, the analysis leads naturally the introduction of a general asymmetry principle of fluctuations and the preferred transition mechanism for a thermodynamic system. The theoretical results derived in this article are in agreement with the experimental results obtained in (K. Nishikawa and T. Morita, Fluid behavior at supercritical states studied by small-angle X-ray scattering, Journal of Supercritical Fluid, 13 (1998, pp. 143-148. Also, the derived second-order transition at the critical point is consistent with the result obtained in (M. Fisher, Specific heat of a gas near the critical point, Physical Review, 136:6A (1964, pp. A1599-A1604.

  3. Model Based Control of Single-Phase Marine Cooling Systems

    DEFF Research Database (Denmark)

    Hansen, Michael

    2014-01-01

    these systems. Traditionally, control for this type of cooling system has been limited to open-loop control of pumps combined with a couple of local PID controllers for bypass valves to keep critical temperatures within design limits. This research considers improvements in a retrofit framework to the control...... linearization, an H∞-control design is applied to the resulting linear system. Disturbance rejection capabilities and robustness of performance for this control design methodology is compared to a baseline design derived from classical control theory. This shows promising results for the nonlinear robust design......This thesis is concerned with the problem of designing model-based control for a class of single-phase marine cooling systems. While this type of cooling system has been in existence for several decades, it is only recently that energy efficiency has become a focus point in the design and operation...

  4. Modeling of a single-phase photovoltaic inverter

    Energy Technology Data Exchange (ETDEWEB)

    Maris, T.I. [Department of Electrical Engineering, Technological Educational Institute of Chalkida, 334 40 Psachna Evias (Greece); Kourtesi, St. [Hellenic Public Power Corporation S.A., 22 Chalcocondyli Str., 104 32 Athens (Greece); Ekonomou, L. [Hellenic American University, 12 Kaplanon Str., 106 80 Athens (Greece); Fotis, G.P. [National Technical University of Athens, School of Electrical and Computer Engineering, High Voltage Laboratory, 9 Iroon Politechniou St., Zografou, 157 80 Athens (Greece)

    2007-11-06

    The paper presents the design of a single-phase photovoltaic inverter model and the simulation of its performance. Furthermore, the concept of moving real and reactive power after coupling this inverter model with an a.c. source representing the main power distribution grid was studied. Brief technical information is given on the inverter design, with emphasis on the operation of the circuit used. In the technical information section, a description of real and reactive power components is given with special reference to the control of these power components by controlling the power angle or the difference in voltage magnitudes between two voltage sources. This a.c. converted voltage has practical interest, since it is useful for feeding small house appliances. (author)

  5. Control of Single-Stage Single-Phase PV inverter

    DEFF Research Database (Denmark)

    Ciobotaru, Mihai; Teodorescu, Remus; Blaabjerg, Frede

    2005-01-01

    In this paper the issue of control strategies for single-stage photovoltaic (PV) inverter is addressed. Two different current controllers have been implemented and an experimental comparison between them has been made. A complete control structure for the single-phase PV system is also presented......-forward; - and the grid current controller implemented in two different ways, using the classical proportional integral (PI) and the novel proportional resonant (PR) controllers. The control strategy was tested experimentally on 1.5 kW PV inverter........ The main elements of the PV control structure are: - a maximum power point tracker (MPPT) algorithm using the incremental conductance method; - a synchronization method using the phase-locked-loop (PLL), based on delay; - the input power control using the dc voltage controller and power feed...

  6. Benchmarks for single-phase flow in fractured porous media

    Science.gov (United States)

    Flemisch, Bernd; Berre, Inga; Boon, Wietse; Fumagalli, Alessio; Schwenck, Nicolas; Scotti, Anna; Stefansson, Ivar; Tatomir, Alexandru

    2018-01-01

    This paper presents several test cases intended to be benchmarks for numerical schemes for single-phase fluid flow in fractured porous media. A number of solution strategies are compared, including a vertex and two cell-centred finite volume methods, a non-conforming embedded discrete fracture model, a primal and a dual extended finite element formulation, and a mortar discrete fracture model. The proposed benchmarks test the schemes by increasing the difficulties in terms of network geometry, e.g. intersecting fractures, and physical parameters, e.g. low and high fracture-matrix permeability ratio as well as heterogeneous fracture permeabilities. For each problem, the results presented are the number of unknowns, the approximation errors in the porous matrix and in the fractures with respect to a reference solution, and the sparsity and condition number of the discretized linear system. All data and meshes used in this study are publicly available for further comparisons.

  7. Single-phase and two-phase anaerobic digestion of fruit and vegetable waste: Comparison of start-up, reactor stability and process performance

    International Nuclear Information System (INIS)

    Ganesh, Rangaraj; Torrijos, Michel; Sousbie, Philippe; Lugardon, Aurelien; Steyer, Jean Philippe; Delgenes, Jean Philippe

    2014-01-01

    Highlights: • Single-phase and two-phase systems were compared for fruit and vegetable waste digestion. • Single-phase digestion produced a methane yield of 0.45 m 3 CH 4 /kg VS and 83% VS removal. • Substrate solubilization was high in acidification conditions at 7.0 kg VS/m 3 d and pH 5.5–6.2. • Energy yield was lower by 33% for two-phase system compared to the single-phase system. • Simple and straight-forward operation favored single phase process over two-phase process. - Abstract: Single-phase and two-phase digestion of fruit and vegetable waste were studied to compare reactor start-up, reactor stability and performance (methane yield, volatile solids reduction and energy yield). The single-phase reactor (SPR) was a conventional reactor operated at a low loading rate (maximum of 3.5 kg VS/m 3 d), while the two-phase system consisted of an acidification reactor (TPAR) and a methanogenic reactor (TPMR). The TPAR was inoculated with methanogenic sludge similar to the SPR, but was operated with step-wise increase in the loading rate and with total recirculation of reactor solids to convert it into acidification sludge. Before each feeding, part of the sludge from TPAR was centrifuged, the centrifuge liquid (solubilized products) was fed to the TPMR and centrifuged solids were recycled back to the reactor. Single-phase digestion produced a methane yield of 0.45 m 3 CH 4 /kg VS fed and VS removal of 83%. The TPAR shifted to acidification mode at an OLR of 10.0 kg VS/m 3 d and then achieved stable performance at 7.0 kg VS/m 3 d and pH 5.5–6.2, with very high substrate solubilization rate and a methane yield of 0.30 m 3 CH 4 /kg COD fed. The two-phase process was capable of high VS reduction, but material and energy balance showed that the single-phase process was superior in terms of volumetric methane production and energy yield by 33%. The lower energy yield of the two-phase system was due to the loss of energy during hydrolysis in the TPAR and the

  8. Thermal gradient brine inclusion migration in salt study: gas-liquid inclusions, preliminary model

    International Nuclear Information System (INIS)

    Olander, D.R.; Machiels, A.J.

    1979-10-01

    Natural salt deposits contain small cubical inclusions of brine distributed through the salt. Temperature gradients, resulting from storing heat-generating wastes in the salt, can cause the inclusions to move through the salt. Prediction of the rate and amount of brine-inclusion migration is necessary for the evaluation of bedded or domed salts as possible media for waste repositories. Inclusions filled exclusively with liquid migrate up the temperature gradient towards the heat source. The solubility of salt in the brine inclusion increases with temperature. Consequently, salt dissolves into the inclusion across the hot surface and crystallizes out at the cold surface. Diffusion of salt within the liquid phase from the hot to the cold faces causes the inclusions to move in the opposite direction. In so doing, they change shape and eventually become rectangular parallelipipeds with a width (dimension perpendicular to the thermal gradient) much larger than the thickness (dimension in the direction of the thermal gradient). The inclusions may also contain a gas phase predominantly consisting of water vapor. These entities are termed two-phase or gas-liquid inclusions. The two-phase inclusions usually migrate down the temperature gradient away from the heat source remaining more-or-less cubical. A two-phase inclusion also forms when an all-liquid inclusion reaches the waste package; upon opening up at the salt-package interface, the brine partially evaporates and the inclusion reseals with some insoluble gas trapped inside. These gas-liquid inclusions proceed to move down the temperature gradient, in the opposite sense of the all-liquid inclusions. The gas-liquid inclusions phenomenon provides a pathway by which radionuclides leached from the wasteform by the brine can be transported away from the waste package and thus might have greater access to the biosphere

  9. Two-Phase Gas-Liquid Flow Structure Characteristics under Periodic Cross Forces Action

    Directory of Open Access Journals (Sweden)

    V. V. Perevezentsev

    2015-01-01

    Full Text Available The article presents a study of two-phase gas-liquid flow under the action of periodic cross forces. The work objective is to obtain experimental data for further analysis and have structure characteristics of the two-phase flow movement. For research, to obtain data without disturbing effect on the flow were used optic PIV (Particle Image Visualization methods because of their noninvasiveness. The cross forces influence was provided by an experimental stand design to change the angular amplitudes and the periods of channel movement cycle with two-phase flow. In the range of volume gas rates was shown a water flow rate versus the inclination angle of immovable riser section and the characteristic angular amplitudes and periods of riser section inclination cycle under periodic cross forces. Data on distribution of average water velocity in twophase flow in abovementioned cases were also obtained. These data allowed us to draw a conclusion that a velocity distribution depends on the angular amplitude and on the period of the riser section roll cycle. This article belongs to publications, which study two-phase flows with no disturbing effect on them. Obtained data give an insight into understanding a pattern of twophase gas-liquid flow under the action of periodic cross forces and can be used to verify the mathematical models of the CFD thermo-hydraulic codes. In the future, the work development expects taking measurements with more frequent interval in the ranges of angular amplitudes and periods of the channel movement cycle and create a mathematical model to show the action of periodic cross forces on two-phase gas-liquid flow.

  10. Contribution to complex gas-liquid flows: Development and validation of a mathematical model

    Science.gov (United States)

    Selma, Brahim

    This study describes the development and validation of Computational Fluid Dynamics (CFD) model for the simulation of dispersed two-phase flows taking in the account the population balance of particles size distribution. A two-fluid (Euler-Euler) methodology previously developed for complex flows is adapted to the present project. The continuous phase turbulence is represented using a two-equation k --- epsilon turbulence model which contains additional terms to account for the effects of the dispersed on the continuous phase turbulence and the effects of the gas-liquid interface. The inter-phase momentum transfer is determined from the instantaneous forces acting on the dispersed phase, comprising drag, lift, virtual mass and drift velocity. These forces are phase fraction dependent and in this work revised modelling is put forward in order to capture a good accuracy for gas hold-up, liquid velocity profiles and turbulence parameters. Furthermore, a correlation for the effect of the drift velocity on the turbulence behaviour is proposed. The revised modelling is based on an extensive survey of the existing literature. The conservation equations are discretised using the finite-volume method and solved in a solution procedure, which is loosely based on the PISO algorithm. Special techniques are employed to ensure the stability of the procedure when the phase fraction is high or changing rapidely [61]. Finally, assessment of the model is made with reference to experimental data for gas-liquid bubbly flow in a rectangular bubble column [133; 134; 135; 18], in a double-turbine stirred tank reactor [126; 127] and in an air-lift bioreacator [101]. Key words: mathematical modelling, complex flow gas-liquid, turbulence, population balance, computational fluids dynamics CFD, OpenFOAM, moments method, method of classes, QMOM, DQMOM.

  11. A grid-connected single-phase photovoltaic micro inverter

    Science.gov (United States)

    Wen, X. Y.; Lin, P. J.; Chen, Z. C.; Wu, L. J.; Cheng, S. Y.

    2017-11-01

    In this paper, the topology of a single-phase grid-connected photovoltaic (PV) micro-inverter is proposed. The PV micro-inverter consists of DC-DC stage with high voltage gain boost and DC-AC conversion stage. In the first stage, we apply the active clamp circuit and two voltage multipliers to achieve soft switching technology and high voltage gain. In addition, the flower pollination algorithm (FPA) is employed for the maximum power point tracking (MPPT) in the PV module in this stage. The second stage cascades a H-bridge inverter and LCL filter. To feed high quality sinusoidal power into the grid, the software phase lock, outer voltage loop and inner current loop control method are adopted as the control strategy. The performance of the proposed topology is tested by Matlab/Simulink. A PV module with maximum power 300W and maximum power point voltage 40V is applied as the input source. The simulation results indicate that the proposed topology and the control strategy are feasible.

  12. Performance Improvement of Single Phase Inverter using SPWM

    Science.gov (United States)

    Gavaskar Reddy, B., Dr; Maheswari, L., Dr; Ganeswari Kale, Adi

    2017-08-01

    This paper concentrates on modelling and simulation of single phase inverter as a frequency changer modulated by Pulse Width Modulation (PWM). An inverter is a circuit that converts DC sources to AC sources. Pulse Width Modulation is a method that utilization as an approach to abatement add up to harmonic distortion in inverter circuit. The model is executed utilizing MATLAB/Simulink software with the SimPower System Block Set in light of PC simulation. PC simulation assumes an imperative part in the plan, investigation, and assessment of force electronic converter and their controller. MATLAB is a successful instrument to examine a PWM inverter. Preferences of utilizing MATLAB are the accompanying: Faster reaction, accessibility of different simulation devices and utilitarian squares and the nonappearance of joining issues. Safe-replacement methodology need be actualized is to explain exchanging Transients. In this way, Insulated Gate Bipolar Transistor (IGBT) is use as exchanging gadgets. IGBT is ideal since it is anything but difficult to control and low misfortunes. The outcome from Simulink was checked utilizing MATLAB simulation.

  13. Self-assembled single-phase perovskite nanocomposite thin films.

    Science.gov (United States)

    Kim, Hyun-Suk; Bi, Lei; Paik, Hanjong; Yang, Dae-Jin; Park, Yun Chang; Dionne, Gerald F; Ross, Caroline A

    2010-02-10

    Thin films of perovskite-structured oxides with general formula ABO(3) have great potential in electronic devices because of their unique properties, which include the high dielectric constant of titanates, (1) high-T(C) superconductivity in cuprates, (2) and colossal magnetoresistance in manganites. (3) These properties are intimately dependent on, and can therefore be tailored by, the microstructure, orientation, and strain state of the film. Here, we demonstrate the growth of cubic Sr(Ti,Fe)O(3) (STF) films with an unusual self-assembled nanocomposite microstructure consisting of (100) and (110)-oriented crystals, both of which grow epitaxially with respect to the Si substrate and which are therefore homoepitaxial with each other. These structures differ from previously reported self-assembled oxide nanocomposites, which consist either of two different materials (4-7) or of single-phase distorted-cubic materials that exhibit two or more variants. (8-12) Moreover, an epitaxial nanocomposite SrTiO(3) overlayer can be grown on the STF, extending the range of compositions over which this microstructure can be formed. This offers the potential for the implementation of self-organized optical/ferromagnetic or ferromagnetic/ferroelectric hybrid nanostructures integrated on technologically important Si substrates with applications in magnetooptical or spintronic devices.

  14. Global weak solutions for a gas liquid model with external forces and general pressure law

    OpenAIRE

    Evje, Steinar; Friis, Helmer André

    2011-01-01

    This is a copy of an article previously published in; SIAM journal on applied mathematics, which has been made available here with permission. Original article; http://dx.doi.org/10.1137/100813336. In this work we show existence of global weak solutions for a two-phase gas-liquid model where the gas phase is represented by a general isothermal pressure law, whereas the liquid is assumed to be incompressible. To make the model relevant for pipe and well-flow applications we have included ex...

  15. A Lagrangian Slug Capturing Scheme for Gas-Liquid Flows in Pipes

    Energy Technology Data Exchange (ETDEWEB)

    Renault, Fabien

    2007-06-15

    In this thesis a new Lagrangian numerical scheme for the simulation of gas-liquid flows in pipelines is presented. Based on an approximate two-fluid model, this new scheme, called LASSI (Lagrangian Approximate Scheme for Slug Initiation) is dedicated to the modelling of the transition between stratified and slug flow. It is able to capture directly the slug initiation process and to track the motion of every single slug in the pipe without numerical diffusion. It can thus be qualified as a slug capturing and slug tracking scheme

  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

    method to monitor severe slugging by means of low cost instrumentation, in particular, by replacing a cumbersome instrument such as a gamma-densitometer with a differential pressure transmitter. In field operation, the multiphase orifice used in these experiments can be replaced by a calibrated control......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. 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...

  18. 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.

  19. 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.

  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. Decolorization of Acid Orange 7 solution by gas-liquid gliding arc discharge plasma.

    Science.gov (United States)

    Du, ChangMing; Shi, TaiHong; Sun, YuWei; Zhuang, XiaoFeng

    2008-06-15

    The decolorization of 180 microM aqueous solutions of Acid Orange 7 (AO7) by means of a non-thermal plasma technique (i.e., the gas-liquid gliding arc discharge, which is generated between at least two metal electrodes with AC high voltage) was investigated in this paper. The effects of the plasma treatment time and the type of feeding gas, including air, oxygen, nitrogen and argon of the dye removal were determined. It is found that the voltage cycles of the gas-liquid gliding arc discharge are characterized by a moderate increase in the tension which is represented by a peak followed by an abrupt decrease and a current peak in the half period (10 ms); the concentration of AO7 solution decreases exponentially to reach 58.9, 77.4, 89.1, 95.1 and 99% in 25, 50, 75, 100 and 125 min, respectively, and the ln(Ct/C0) varies linearly with the treatment time t, indicating that decolorization reaction follow first pseudo-order kinetics with a constant rate of 0.03327 min(-1) when air was used as feeding gas; the decolorization rate during the plasma treatment is the greatest for oxygen as the feeding gas, in turn followed by air and argon, and was the least when using nitrogen. The variations of pH and conductivity and the formations of hydrogen peroxide and ozone are measured.

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

    Science.gov (United States)

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

    2018-01-01

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

  3. Gas-liquid hybrid discharge-induced degradation of diuron in aqueous solution.

    Science.gov (United States)

    Feng, Jingwei; Zheng, Zheng; Luan, Jingfei; Li, Kunquan; Wang, Lianhong; Feng, Jianfang

    2009-05-30

    Degradation of diuron in aqueous solution by gas-liquid hybrid discharge was investigated for the first time. The effect of output power intensity, pH value, Fe(2+) concentration, Cu(2+) concentration, initial conductivity and air flow rate on the degradation efficiency of diuron was examined. The results showed that the degradation efficiency of diuron increased with increasing output power intensity and increased with decreasing pH values. In the presence of Fe(2+), the degradation efficiency of diuron increased with increasing Fe(2+) concentration. The degradation efficiency of diuron was decreased during the first 4 min and increased during the last 10 min with adding of Cu(2+). Decreasing the initial conductivity and increasing the air flow rate were favorable for the degradation of diuron. Degradation of diuron by gas-liquid hybrid discharge fitted first-order kinetics. The pH value of the solution decreased during the reaction process. Total organic carbon removal rate increased in the presence of Fe(2+) or Cu(2+). The generated Cl(-1), NH(4)(+), NO(3)(-), oxalic acid, acetic acid and formic acid during the degradation process were also detected. Based on the detected Cl(-1) and other intermediates, a possible degradation pathway of diuron was proposed.

  4. Tracking gas-liquid coexistence in fluids of charged soft dumbbells.

    Science.gov (United States)

    Braun, Heiko; Hentschke, Reinhard

    2009-10-01

    The existence of gas-liquid coexistence in dipolar fluids with no other contribution to attractive interaction than dipole-dipole interaction is a basic and open question in the theory of fluids. Recent Monte Carlo work by Camp and co-workers indicates that a fluid of charged hard dumbbells does exhibit gas-liquid (g-l) coexistence. This system has the potential to answer the above fundamental question because the charge-to-charge separation, d , on the dumbbells may be reduced to, at least in principle, yield the dipolar fluid limit. Using the molecular-dynamics technique we present simulation results for the g-l critical point of charged soft dumbbells at fixed dipole moment as function of d . We do find a g-l critical point at finite temperature even at the smallest d value (10;{-4}) . Reversible aggregation appears to play less a role than in related model systems as d becomes small. Consequently attempts to interpret the simulation results using either an extension of Flory's lattice theory for polymer systems, which includes reversible assembly of monomers into chains, or the defect model for reversible networks proposed by Tlusty and Safran are not successful. The overall best qualitative interpretation of the critical parameters is obtained by considering the dumbbells as dipoles immersed in a continuum dielectric.

  5. Measurement of gas-liquid two-phase flow in bubble columns using ensemble correlation PIV

    NARCIS (Netherlands)

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

    2000-01-01

    This paper highlights the development of a new ensemble correlation, multiphase flow PIV technique. The particular approach discussed in this paper is a straightforward extension of single-phase PIV and one of the major advantages of the technique is that it employs a single CCD camera. This

  6. Servo characteristics of single-phase spindle motor in DVD-ROM

    Science.gov (United States)

    Wang, KingYin; Kuei, ChingPing; Chang, SungSan; Lee, YaoYu; Kuo, YuHung

    2000-07-01

    The single-phase DC motor has the low-cost advantage over 3- phase DC motor owing to its easy-assembling and high yield- rate, however, it has larger torque ripple and cogging torque. Single-phase DC motor is currently applied to low profit margin products such as cooling fan. In order to utilize single-phase DC motor to high precision system, for instance, DVD (Digital Versatile Disk), the vibration caused by torque ripple and cogging torque needs to be solved. In this paper, focusing error, tracking error, seeking ability and some velocity control performances are studied when single-phase DC motor is used in DVD related products.

  7. Equivalence of two models in single-phase multicomponent flow simulations

    KAUST Repository

    Wu, Yuanqing

    2016-02-28

    In this work, two models to simulate the single-phase multicomponent flow in reservoirs are introduced: single-phase multicomponent flow model and two-phase compositional flow model. Because the single-phase multicomponent flow is a special case of the two-phase compositional flow, the two-phase compositional flow model can also simulate the case. We compare and analyze the two models when simulating the single-phase multicomponent flow, and then demonstrate the equivalence of the two models mathematically. An experiment is also carried out to verify the equivalence of the two models.

  8. Using artificial intelligence to improve identification of nanofluid gas-liquid two-phase flow pattern in mini-channel

    Science.gov (United States)

    Xiao, Jian; Luo, Xiaoping; Feng, Zhenfei; Zhang, Jinxin

    2018-01-01

    This work combines fuzzy logic and a support vector machine (SVM) with a principal component analysis (PCA) to create an artificial-intelligence system that identifies nanofluid gas-liquid two-phase flow states in a vertical mini-channel. Flow-pattern recognition requires finding the operational details of the process and doing computer simulations and image processing can be used to automate the description of flow patterns in nanofluid gas-liquid two-phase flow. This work uses fuzzy logic and a SVM with PCA to improve the accuracy with which the flow pattern of a nanofluid gas-liquid two-phase flow is identified. To acquire images of nanofluid gas-liquid two-phase flow patterns of flow boiling, a high-speed digital camera was used to record four different types of flow-pattern images, namely annular flow, bubbly flow, churn flow, and slug flow. The textural features extracted by processing the images of nanofluid gas-liquid two-phase flow patterns are used as inputs to various identification schemes such as fuzzy logic, SVM, and SVM with PCA to identify the type of flow pattern. The results indicate that the SVM with reduced characteristics of PCA provides the best identification accuracy and requires less calculation time than the other two schemes. The data reported herein should be very useful for the design and operation of industrial applications.

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

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  10. Microporous hollow fibre membrane modules as gas-liquid contactors. Part 1. Physical mass transfer processes: A specific application

    OpenAIRE

    Kreulen, H.; Versteeg, G.F.; Swaaij, W.P.M. van

    1993-01-01

    Gas-liquid mass transfer has been studied in a membrane module with non-wetted microporous fibres in the laminar flow regime. This new type of gas/liquid contactor can be operated stabily over a large range of gas and liquid flows because gas and liquid phase do not influence each other directly. Therefore foam is not formed in the module, gas bubbles are not entrained in the liquid flowing out of the reactor and the separation of both phases can be achieved very easily. These phenomena often...

  11. Experimental investigation on distribution of mass flux and gas/liquid mixture ratio of airblast coaxial atomizers

    Science.gov (United States)

    Wu, Jinxiang; Liu, Weidong; Zhuang, Fengchen

    1993-06-01

    Airblast coaxial atomizers are widely used in combustion chambers of liquid rocket engines, and the distributions of mass flux and gas/liquid mixture ratio in the downstream of the atomizers are one of the important parameters which influence the performance of combustion. A two-phase impact probe designed by the authors was employed to measure these parameters in a type of airblast coaxial atomizer. Graphs from experimental results show the details of the distribution in the downstream of the atomizers and the influences of the configuration parameters on distribution. The results provides important references for understanding the structure of gas/liquid flow fields and for designing and improving such atomizers.

  12. Structure and magnetism of single-phase epitaxial gamma '-Fe4N

    NARCIS (Netherlands)

    Costa-Kramer, JL; Borsa, DM; Garcia-Martin, JM; Martin-Gonzalez, MS; Boerma, DO; Briones, F

    Single phase epitaxial pure gamma(')-Fe4N films are grown on MgO (001) by molecular beam epitaxy of iron in the presence of nitrogen obtained from a radio frequency atomic source. The epitaxial, single phase nature of the films is revealed by x-ray diffraction and by the local magnetic environment

  13. new topology for single-phase, three-level, spwm vsi with lc filter

    African Journals Online (AJOL)

    level PWM inverter. However, this is not the case with single-phase PWM inverters. In these days, the popular single-phase inverters adopt the full-bridge type using approximate sinusoidal modulation technique. The output voltage in them has two values: zero and pos- itive supply dc voltage levels in the positive half cycle.

  14. Torque Analysis With Saturation Effects for Non-Salient Single-Phase Permanent-Magnet Machines

    DEFF Research Database (Denmark)

    Lu, Kaiyuan; Ritchie, Ewen

    2011-01-01

    The effects of saturation on torque production for non-salient, single-phase, permanent-magnet machines are studied in this paper. An analytical torque equation is proposed to predict the instantaneous torque with saturation effects. Compared to the existing methods, it is computationally faster......-element results, and experimental results obtained on a prototype single-phase permanent-magnet machine....

  15. Experimental study of gas-liquid flow local characteristics in rectangular microchannel

    Directory of Open Access Journals (Sweden)

    Bartkus German

    2017-01-01

    Full Text Available Using high-speed video recording and the method of dual laser scanning the gas-liquid flow was investigated in a rectangular microchannel with an aspect ratio of 0.74 (cross section 269×362 μm. The T-mixer was used at the channel’s inlet for the two-phase flow formation. The peculiarity of this work is using a number of liquids (ethanol, distilled water, 40% aqueous ethanol with different physical properties, including surface tension, viscosity, and density, with nitrogen. Experiments were carried out for the vertically upward and horizontal flow. Using laser scanning method the maps of flow patterns were obtained for all mixtures.

  16. Finite-time thermodynamics and the gas-liquid phase transition.

    Science.gov (United States)

    Santoro, M; Schön, J C; Jansen, M

    2007-12-01

    In this paper, we study the application of the concept of finite-time thermodynamics to first-order phase transitions. As an example, we investigate the transition from the gaseous to the liquid state by modeling the liquification of the gas in a finite time. In particular, we introduce, state, and solve an optimal control problem in which we aim at achieving the gas-liquid first-order phase transition through supersaturation within a fixed time in an optimal fashion, in the sense that the work required to supersaturate the gas, called excess work, is minimized by controlling the appropriate thermodynamic parameters. The resulting set of coupled nonlinear differential equations is then solved for three systems, nitrogen N2, oxygen O2, and water vapor H2O.

  17. 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.

  18. Characterization of free and bound fatty acids in human gallstones by capillary gas liquid chromatography

    International Nuclear Information System (INIS)

    Channa, N.A.; Khand, F.D.; Noorani, M.A.; Bhanger, M.I.

    2002-01-01

    Forty-four human gallstone samples either of pure cholesterol or cholesterol and bilirubin were randomly selected and analyzed by capillary gas liquid chromatography for the relative percentage composition of free and total fatty acids. The results showed that bound fatty acids were present in higher amounts than the free fatty acids. Amongst the bound fatty acids the percentage occurrence for palmitic acid was highest followed by stearic, oleic, linoleic and myristic acids. Fatty acids myristic, palmitic and linoleic were present in higher amounts in cholesterol gallstones, whereas stearic acid in cholesterol and bilirubin gallstones. When compared, no significant difference (p < 0.05) in the levels of free and bound fatty acids were seen in gallstones of males and females. The results suggest that bound fatty acids have a role to play in the structure of gallstones. (author)

  19. Simulating gas-liquid flow in a micro-channel with the lattice Boltzmann method

    Science.gov (United States)

    Shi, Grace; Lazouskaya, Volha; Jin, Yan; Wang, Lian-Ping

    2007-11-01

    The flows of water in natural soil porous media with air-water interface are important to colloid-facilitated transport of contaminants and other phenomena with groundwater as the carrier. These flows are complex in terms of the geometrical feature and physical and chemical forces involved. As first step, we here demonstrate that a gas-liquid interfacial viscous flow in a 3D micro-channel with a square cross-section can be simulated using the lattice Boltzmann method. The talk will cover the detailed ingredients of the two-phase LBE model including the proper equation of state, surface tension, and the triple-phase boundary conditions. Methods to improve the stability of the code such as using multiple relaxation times will be tested. Preliminary results will be presented and compared to parallel experimental observations using confocal laser scanning microscopy.

  20. Coupled Gas-Liquid Diffusion in Porous Media Using the Dusty Gas Model

    Science.gov (United States)

    Webb, S. W.; Pruess, K.

    2001-12-01

    Numerous problems involve the simultaneous diffusion of chemical species in both aqueous and gaseous phases. Applications include diffusion of non-condensible gases including carbon sequestration, volatile organic compounds (VOCs), and chemicals from buried landmines. Diffusion in the unsaturated zone involves simultaneous transport in the aqueous and gaseous pathways. Calculation of diffusion in the individual phases is straightforward. However, for simultaneous diffusion in both phases, simply adding diffusive fluxes in gas and liquid phases will in general not be correct. Proper treatment of diffusion in multiphase conditions must take into account the coupling between diffusion and phase partitioning. Coupled gas-liquid diffusion was previously considered using Fick's law for both aqueous and gaseous diffusion. The diffusive strength term was harmonically weighted at the interface to enforce mass conservation. Results showed that the coupling effects are significant, and that uncoupled results can seriously underestimate diffusion across a capillary fringe. In the present work, the Dusty Gas Model (DGM) has been used to model gas diffusion. The DGM is a more fundamentally sound model for gas diffusion than Fick's law. However, the formulation of multiphase diffusion coupled with gas-liquid phase partitioning becomes considerably more complicated, and mass conservation must be explicitly imposed on each component through solution for the appropriate interface conditions. For higher permeability and trace gas conditions, the two models (Fick's law and DGM) give similar results as expected. However, for lower permeability media and non-trace gas conditions, significant differences exist. This work was supported by the U.S Department of Energy under Contracts No. DE-AC04-94AL85000 and DE-AC03-76SF00098.

  1. Structure of the gas-liquid annular two-phase flow in a nozzle section

    International Nuclear Information System (INIS)

    Yoshida, Kenji; Kataoka, Isao; Ohmori, Syuichi; Mori, Michitsugu

    2006-01-01

    Experimental studies on the flow behavior of gas-liquid annular two-phase flow passing through a nozzle section were carried out. This study is concerned with the central steam jet injector for a next generation nuclear reactor. In the central steam jet injector, steam/water annular two-phase flow is formed at the mixing nozzle. To make an appropriate design and to establish the high-performance steam injector system, it is very important to accumulate the fundamental data of the thermo-hydro dynamic characteristics of annular flow passing through a nozzle section. On the other hand, the transient behavior of multiphase flow, in which the interactions between two-phases occur, is one of the most interesting scientific issues and has attracted research attention. In this study, the transient gas-phase turbulence modification in annular flow due to the gas-liquid phase interaction is experimentally investigated. The annular flow passing through a throat section is under the transient state due to the changing cross sectional area of the channel and resultantly the superficial velocities of both phases are changed compared with a fully developed flow in a straight pipe. The measurements for the gas-phase turbulence were precisely performed by using a constant temperature hot-wire anemometer, and made clear the turbulence structure such as velocity profiles, fluctuation velocity profiles. The behavior of the interfacial waves in the liquid film flow such as the ripple or disturbance waves was also observed. The measurements for the liquid film thickness by the electrode needle method were also performed to measure the base film thickness, mean film thickness, maximum film thickness and wave height of the ripple or the disturbance waves. (author)

  2. Design And Development Of An Automatic Single Phase Protective Device Using Ssr

    Directory of Open Access Journals (Sweden)

    Michael E.

    2017-10-01

    Full Text Available Since the discovery of energy safety has been a paramount subject matter. This we can see in todays electrical systems where protective devices such as fuse and circuit breakers are used to prevent fire hazards resulting from overload overvoltage and short circuits. However with all the revolution in technology these options may be considered less smart since the fuse made with wire strands calculated for specific current capacity faults permanently when the specified current rating is exceeded. While the circuit breaker which is made up of mechanical switch fails as a result of carbon forming and the wearing away of the contacts because of arcing. As a means of improvement this paper presents the design and development of an automatic single phase protective device using solid state relay SSR. This study is to ensure automatic cut off from power supply in cases of overvoltage above 240 V AC or when overload and short circuit current above 8amps is detected without permanent damage of a fuse placed along current path. Also the design will ensure that there is an automatic close circuit whenever the trigger switch is momentary switch is closed. The system is achieved via the use of PIC micro-controller current sensor and other discrete components. The system is tested and works well inhibiting the frequent faulting of fuses. It also helps to prevent hazard as a result of overvoltage overload and short circuit and ensures a close circuit when the trigger switch is closed.

  3. 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

  4. Microporous hollow fibre membrane modules as gas-liquid contactors. Part 1: Physical mass transfer processes. A specific application: mass transfer in highly viscous liquids

    NARCIS (Netherlands)

    Kreulen, H.; Kreulen, H.; Versteeg, Geert; Smolders, C.A.; Smolders, C.A.; van Swaaij, Willibrordus Petrus Maria

    1993-01-01

    Gas-liquid mass transfer has been studied in a membrane module with non-wetted microporous fibres in the laminar flow regime. This new type of gas/liquid contactor can be operated stabily over a large range of gas and liquid flows because gas and liquid phase do not influence each other directly.

  5. Trigeneration scheme for a natural gas liquids extraction plant in the Middle East

    International Nuclear Information System (INIS)

    Eveloy, Valérie; Rodgers, Peter; Popli, Sahil

    2014-01-01

    Highlights: • Trigeneration scheme tailored to natural gas liquids extraction plant. • High ambient temperature and RH conditions in the Persian Gulf. • Absorption refrigeration powered by gas turbine (GT) exhaust gas waste heat. • GT compressor inlet air- and process gas cooling, process gas heating. • Significant OPEX and primary energy savings, favorable payback period and net present value. - Abstract: Natural gas processing plants in the Persian Gulf face extreme climatic conditions that constrain their gas turbine (GT) power generation and cooling capacities. However, due to a past history of low hydrocarbon prices, such plants have not fully exploited their waste heat recovery potential to date. The techno-economic performance of a combined cooling, heating and power (CCHP) scheme designed to enhance the energy efficiency of a major natural gas liquids extraction plant in the Persian Gulf is assessed. The trigeneration scheme utilizes double-effect water–lithium bromide absorption refrigeration powered by steam generated from GT exhaust gas waste heat to provide both GT compressor inlet air- and process gas cooling. Part of the generated steam is also used for process gas heating. Thermodynamic modeling reveals that recovery of 82 MW of GT waste heat would provide additional cooling and heating capacities of 75 MW and 24 MW to the plant, respectively, thereby permitting elimination of a 28 MW GT, and existing cooling and heating equipment. GT compressor inlet air cooling alone yields approximately 151 GW h of additional electric power annually, highlighting the effectiveness of absorption refrigeration in meeting compressor inlet air cooling loads throughout the year in the Gulf climate. The overall net annual operating expenditure savings contributed by the CCHP system would average approximately 14.6 million US$ over its lifespan, which corresponds to average yearly savings of 190 MMSCM of natural gas. The CCHP scheme economic payback period is

  6. A Novel Model Predictive Control for Single-Phase Grid-Connected Photovoltaic Inverters

    DEFF Research Database (Denmark)

    Zangeneh Bighash, Esmaeil; Sadeghzadeh, Seyed Mohammad; Ebrahimzadeh, Esmaeil

    2017-01-01

    Single-phase grid-connected inverters with LCL filter are widely used to connect photovoltaic systems to the utility grid. Among the existing control schemes, predictive control methods are faster and more accurate but also more complicated to implement. Recently, the Model Predictive Control (MPC......) algorithm for single-phase inverter has been presented, where the algorithm implementation is straightforward. In the MPC approach, all switching states are considered in each switching period to achieve the control objectives. However, since the number of switching states in single-phase inverters is small...... vectors. Simulation results show that the proposed approach lead to a lower THD in the injected current combined with fast dynamics. The proposed predictive control has been simulated and implemented on a 1 kW single-phase HERIC (highly efficient and reliable inverter concept) inverter with an LCL filter...

  7. Light-Weight, Low-Cost, Single-Phase, Liquid-Cooled Cold Plate (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Narumanchi, S.

    2013-07-01

    This presentation, 'Light-Weight, Low-Cost, Single-Phase Liquid-Cooled Cold Plate,' directly addresses program goals of increased power density, specific power, and lower cost of power electronics components through improved thermal management.

  8. Standard Specification for Sampling Single-Phase Geothermal Liquid or Steam for Purposes of Chemical Analysis

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1983-01-01

    1.1 This specification covers the basic requirements for equipment to be used for the collection of uncontaminated and representative samples from single-phase geothermal liquid or steam. Geopressured liquids are included. See Fig 1.

  9. Effect of increasing proportions of lignocellulosic cosubstrate on the single-phase and two-phase digestion of readily biodegradable substrate

    International Nuclear Information System (INIS)

    Ganesh, Rangaraj; Torrijos, Michel; Sousbie, Philippe; Lugardon, Aurelien; Steyer, Jean Philippe; Delgenes, Jean Philippe

    2015-01-01

    The influence of different proportions of lignocellulosic substrate (cow manure with straw, CM) on the single-phase (conventional reactor) and two-phase (acidification/methanation with solids and liquid recirculation) digestion of a readily biodegradable substrate (fruit and vegetable waste, FVW) was investigated in order to determine the optimum cosubstrate ratio and the process best suited for codigestion. Both processes were fed initially with FVW, followed by FVW and CM at 80%:20% and 60%:40% (on volatile solids, VS basis) during an experiment run over eleven months. For the single-phase process, energy yield and VS destruction decreased by 11% and 9% with the 80%:20% FVW and CM ratio and by 16% and 17% with the 60%:40% feed ratio when compared to 100% FVW feed. For the two-phase process, energy yield and VS destruction decreased by 21% and 14% with 80%:20% feed ratio and by 48% and 33% with 60%:40% feed ratio compared to 100% FVW. Substrate solubilization in the acidification reactor was very efficient for all the feed proportions but it resulted in compounds other than volatile fatty acid (non-VFA COD) which were not easily amenable to methane generation. This led to a lower energy yield per kg of VS fed in the two-phase process compared to the single-phase process for the respective waste combination. For single-phase digestion, both 80%:20% and 60%:40% ratios were effective co-substrate combinations due to their higher energy yield. The two-phase process can be used for these ratios if higher VS reduction and a higher loading rate are the objectives. - Highlights: • Effect of cow manure addition on the digestion of fruit and vegetable waste studied. • Single and two-phase processes were compared for three different waste ratios. • Methane and energy yields were higher by single-phase than the two-phase process. • FVW-Cow manure ratios of 80%:20% and 60%:40% found effective for single-phase digestion. • Two-phase process resulted in higher solids

  10. Transition of Gas-Liquid Stratified Flow in Oil Transport Pipes

    Directory of Open Access Journals (Sweden)

    D. Lakehal

    2011-12-01

    Full Text Available Large-Scale Simulation results of the transition of a gas-liquid stratified flow to slug flow regime in circular 3D oil transport pipes under turbulent flow conditions expressed. Free surface flow in the pipe is treated using the Level Set method. Turbulence is approached via the LES and VLES methodologies extended to interfacial two-phase flows. It is shown that only with the Level Set method the flow transition can be accurately predicted, better than with the two-fluid phase-average model. The transition from stratified to slug flow is found to be subsequent to the merging of the secondary wave modes created by the action of gas shear (short waves with the first wave mode (high amplitude long wave. The model is capable of predicting global flow features like the onset of slugging and slug speed. In the second test case, the model predicts different kinds of slugs, the so-called operating slugs formed upstream that fill entirely the pipe with water slugs of length scales of the order of 2-4 D, and lower size (1-1.5 D disturbance slugs, featuring lower hold-up (0.8-0.9. The model predicts well the frequency of slugs. The simulations revealed important parameter effects on the results, such as two-dimensionality, pipe length, and water holdup.

  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. Pigging analysis for gas-liquid two phase flow in pipelines

    International Nuclear Information System (INIS)

    Kohda, K.; Suzukawa, Y.; Furukawa, H.

    1988-01-01

    A new method to analyze transient phenomena caused by pigging in gas-liquid two-phase flow is developed. During pigging, a pipeline is divided into three sections by two moving boundaries, namely the pig and the leading edge of the liquid slug in front of the pig. The basic equations are mass, momentum and energy conservation equations. The boundary conditions at the moving boundaries are determined from the mass conservation across the boundaries, etc. A finite difference method is used to solve the equations numerically. The method described above is also capable of analyzing transient two-phase flow caused by pressure and flow rate changes. Thus the over-all analysis of transient two-phase flow in pipelines becomes possible. A series of air-water two-phase flow pigging experiments was conducted using 105.3 mm diameter and 1436.5 m long test pipeline. The agreement between the measured and the calculated results is very good

  13. Gas-liquid Phase Distribution and Void Fraction Measurements Using the MRI

    Science.gov (United States)

    Daidzic, N. E.; Schmidt, E.; Hasan, M. M.; Altobelli, S.

    2004-01-01

    We used a permanent-magnet MRI system to estimate the integral and spatially- and/or temporally-resolved void-fraction distributions and flow patterns in gas-liquid two-phase flows. Air was introduced at the bottom of the stagnant liquid column using an accurate and programmable syringe pump. Air flow rates were varied between 1 and 200 ml/min. The cylindrical non-conducting test tube in which two-phase flow was measured was placed in a 2.67 kGauss MRI with MRT spectrometer/imager. Roughly linear relationship has been obtained for the integral void-fraction, obtained by volume-averaging of the spatially-resolved signals, and the air flow rate in upward direction. The time-averaged spatially-resolved void fraction has also been obtained for the quasi-steady flow of air in a stagnant liquid column. No great accuracy is claimed as this was an exploratory proof-of-concept type of experiment. Preliminary results show that MRI a non-invasive and non-intrusive experimental technique can indeed provide a wealth of different qualitative and quantitative data and is especially well suited for averaged transport processes in adiabatic and diabatic multi-phase and/or multi-component flows.

  14. Research into the group composition of tar using the gas liquid chromatography method

    Energy Technology Data Exchange (ETDEWEB)

    Lisin, S.N.; Stepanov, Yu.V.; Lisina, L.A.; Chistyakov, A.N.

    1986-03-01

    This paper first gives a brief review of current methods used for determining chemical composition of tars, then describes experiments using gas liquid chromatography (GLC) to determine the chemical composition of delta/sub 1/, delta/sub 2/, delta, and delta fractions of medium temperature tars obtained during normal solvent processing (isooctane, toluene, quinoline). For delta and delta fractions, a Tsvet-104 chromatograph was used with a flame-ionization detector under the following conditions: column height 3 m, diameter 3 mm, AW-HMDS filler, 0.25-0.36 mm fractions with 5% SE-30, linear column temperature increase from 50-310/sup 0/C, velocity 6 C/min, condenser temperature 350/sup 0/C, velocity of carrier gas (helium) and hydrogen 100 ml/min, air consumption 1.5 l/min. delta/sub 1/ and delta/sub 2/ fractions were determined using a GC-IC chromatograph (manufactured by Shimatsu) under conditions analogous to those given above. Conclusion is that the yield of chromatographable compounds from tar by the GLC method with temperature programming is practically constant for each tar and can be characterized by the delta fraction content and its chemical composition. A method of determining the group composition of tars and the chemical composition of the delta fraction using GLC is proposed. 13 refs.

  15. Gas-Liquid Two-Phase Flows Through Packed Bed Reactors in Microgravity

    Science.gov (United States)

    Motil, Brian J.; Balakotaiah, Vemuri

    2001-01-01

    The simultaneous flow of gas and liquid through a fixed bed of particles occurs in many unit operations of interest to the designers of space-based as well as terrestrial equipment. Examples include separation columns, gas-liquid reactors, humidification, drying, extraction, and leaching. These operations are critical to a wide variety of industries such as petroleum, pharmaceutical, mining, biological, and chemical. NASA recognizes that similar operations will need to be performed in space and on planetary bodies such as Mars if we are to achieve our goals of human exploration and the development of space. The goal of this research is to understand how to apply our current understanding of two-phase fluid flow through fixed-bed reactors to zero- or partial-gravity environments. Previous experiments by NASA have shown that reactors designed to work on Earth do not necessarily function in a similar manner in space. Two experiments, the Water Processor Assembly and the Volatile Removal Assembly have encountered difficulties in predicting and controlling the distribution of the phases (a crucial element in the operation of this type of reactor) as well as the overall pressure drop.

  16. 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)

  17. North American natural gas liquids pricing and convergence : an energy market assessment

    International Nuclear Information System (INIS)

    2001-05-01

    A background on natural gas liquids (NGL) pricing was presented along with a discussion regarding the impact of energy price convergence. The high energy prices in the fall of 2000 were a result of many factors, including the high price of NGLs. All NGL components such as ethane, propane and butane can be used as petrochemical feedstock. In the winter of 2000/2001 the relationship between liquids and crude oil prices collapsed when high energy prices led to a situation where, for a short while, extraction of liquids from natural gas became uneconomic since producers got more value for NGLs left in the gas stream. As a result, when the supply and demand balances for NGL tightened in many regions of North America, NGL prices were reflecting the unprecedented high natural gas prices. This paper also explained how the four major North American NGL trading hubs in Alberta, Ontario, Kansas and Texas operate. The pricing events of 2000 have impacted on the NGL industry and energy prices remain an issue since both crude oil and natural gas price are forecasted to remain strong in the near future. 5 figs

  18. An inverse gas chromatographic methodology for studying gas-liquid mass transfer.

    Science.gov (United States)

    Paloglou, A; Martakidis, K; Gavril, D

    2017-01-13

    A novel methodology of reversed flow inverse gas chromatography (RF-IGC) is presented. It permits the simultaneous determination of mass transfer coefficients across the gas liquid interface as well as the respective solubility parameters and thermodynamic functions of dissolution of gases into liquids. The standard deviation of the experimentally determined parameters is estimated for first time, which combined with the successful comparison of the values of the present parameters with other literature ones ascertain the reliability of the methodology. Another novelty of the present work is that the chromatographic sampling of the physicochemical phenomena is done without performing the usual flow reversals procedure. Vinyl chloride monomer's (VCM) interaction with various composition liquid foods: orange juice, milk and olive oil was used as model system. The present transfer rates are controlled by the gas film at lower temperatures, but at higher temperatures the resistances in both films tend to become equal. The found liquid diffusivity values express the total mass transfer from the gas phase into the liquid's bulk and they decrease with rising temperature, as the solubilities of gases in liquids do. Solubility, expressed by Henry's law constant and the mean values of interfacial thickness are of the same order of magnitude to literature ones. From the thermodynamic point of view, VCM dissolution in all liquids is accompanied by significant heat release and it is a slightly non-spontaneous process, near equilibrium, while the entropy change values are negative. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Hydrodynamics and axial mixing in a packed gas-liquid column

    Directory of Open Access Journals (Sweden)

    Barjaktarović Branislava G.

    2003-01-01

    Full Text Available The objective of this study was to investigate the pilot-plant gas absorption packed column hydrodynamics, as well as axial mixing in the system air-water. The pressure drop and the gas phase holdup data were determined in dependence on the flow rates of gas and liquid phases. The influence of superficial velocities of liquid and gas phases on the liquid axial dispersion in a gas-liquid packed bed column (ID 15 cm consisting of Raschig rings (15x15x2 mm were investigated. The pressure drop was measured with a U-type manometer, connected to the bottom and the top of the working part of the column. The gas phase holdup data in the air-water two-phase system was calculated as a ratio of the gas phase volume to the total volume of the two-phase system. Axial dispersion in the water phase has been determined by examining of the distribution of residence times of a salt tracer (NaCl in the packed bed. The tracer was injected in the liquid flow above the packed bed; samples of liquid were simultaneously taken from two sites at 1 m distance along the bed. Salt concentrations in the samples were determined by conductivity measurements. The mean residence time and the axial dispersion number were calculated by the moment method. The axial dispersion increases with an increase of liquid flow velocities and decrease of superficial air velocities.

  20. Single-phase and two-phase anaerobic digestion of fruit and vegetable waste: Comparison of start-up, reactor stability and process performance

    Energy Technology Data Exchange (ETDEWEB)

    Ganesh, Rangaraj [INRA, UR50, Laboratoire de Biotechnologie de l’Environnement, Avenue des Etangs, Narbonne F-11100 (France); Torrijos, Michel, E-mail: michel.torrijos@supagro.inra.fr [INRA, UR50, Laboratoire de Biotechnologie de l’Environnement, Avenue des Etangs, Narbonne F-11100 (France); Sousbie, Philippe [INRA, UR50, Laboratoire de Biotechnologie de l’Environnement, Avenue des Etangs, Narbonne F-11100 (France); Lugardon, Aurelien [Naskeo Environnment, 52 rue Paul Vaillant Couturier, F-92240 Malakoff (France); Steyer, Jean Philippe; Delgenes, Jean Philippe [INRA, UR50, Laboratoire de Biotechnologie de l’Environnement, Avenue des Etangs, Narbonne F-11100 (France)

    2014-05-01

    Highlights: • Single-phase and two-phase systems were compared for fruit and vegetable waste digestion. • Single-phase digestion produced a methane yield of 0.45 m{sup 3} CH{sub 4}/kg VS and 83% VS removal. • Substrate solubilization was high in acidification conditions at 7.0 kg VS/m{sup 3} d and pH 5.5–6.2. • Energy yield was lower by 33% for two-phase system compared to the single-phase system. • Simple and straight-forward operation favored single phase process over two-phase process. - Abstract: Single-phase and two-phase digestion of fruit and vegetable waste were studied to compare reactor start-up, reactor stability and performance (methane yield, volatile solids reduction and energy yield). The single-phase reactor (SPR) was a conventional reactor operated at a low loading rate (maximum of 3.5 kg VS/m{sup 3} d), while the two-phase system consisted of an acidification reactor (TPAR) and a methanogenic reactor (TPMR). The TPAR was inoculated with methanogenic sludge similar to the SPR, but was operated with step-wise increase in the loading rate and with total recirculation of reactor solids to convert it into acidification sludge. Before each feeding, part of the sludge from TPAR was centrifuged, the centrifuge liquid (solubilized products) was fed to the TPMR and centrifuged solids were recycled back to the reactor. Single-phase digestion produced a methane yield of 0.45 m{sup 3} CH{sub 4}/kg VS fed and VS removal of 83%. The TPAR shifted to acidification mode at an OLR of 10.0 kg VS/m{sup 3} d and then achieved stable performance at 7.0 kg VS/m{sup 3} d and pH 5.5–6.2, with very high substrate solubilization rate and a methane yield of 0.30 m{sup 3} CH{sub 4}/kg COD fed. The two-phase process was capable of high VS reduction, but material and energy balance showed that the single-phase process was superior in terms of volumetric methane production and energy yield by 33%. The lower energy yield of the two-phase system was due to the loss of

  1. 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

  2. Approximating the nonlinear density dependence of electron transport coefficients and scattering rates across the gas-liquid interface

    Science.gov (United States)

    Garland, N. A.; Boyle, G. J.; Cocks, D. G.; White, R. D.

    2018-02-01

    This study reviews the neutral density dependence of electron transport in gases and liquids and develops a method to determine the nonlinear medium density dependence of electron transport coefficients and scattering rates required for modeling transport in the vicinity of gas-liquid interfaces. The method has its foundations in Blanc’s law for gas-mixtures and adapts the theory of Garland et al (2017 Plasma Sources Sci. Technol. 26) to extract electron transport data across the gas-liquid transition region using known data from the gas and liquid phases only. The method is systematically benchmarked against multi-term Boltzmann equation solutions for Percus-Yevick model liquids. Application to atomic liquids highlights the utility and accuracy of the derived method.

  3. Velocity field measurement in gas-liquid metal two-phase flow with use of PIV and neutron radiography techniques

    International Nuclear Information System (INIS)

    Saito, Y.; Mishima, K.; Tobita, Y.; Suzuki, T.; Matsubayashi, M.

    2001-01-01

    Neutron radiography and PIV (Particle Image Velocimetry) techniques were applied to measurements of velocity field in gas-liquid metal two-phase flow. Visualization and measurements of two-phase flow were conducted using molten lead bismuth and nitrogen gas as working fluids and particles made of gold-cadmium (AuCd 3 ) inter-metallic alloy were employed as the tracer. Discrimination method between bubble and tracer images in two-phase flow was developed based on the σ-scaling method. Time-averaged liquid velocity fields, gas velocity fields and void profile were calculated from discriminated images, respectively. From these measurements, the basic characteristics of gas-liquid metal two-phase mixture were clarified. (author)

  4. Mass spectral identification and gas-liquid chromatographic determination of methyl 4-chloroindolyl-3-acetate in canned and frozen peas.

    Science.gov (United States)

    Heikes, D L

    1980-11-01

    Methyl 4-chloroindolyl-3-acetate (MCIA), a naturally occurring auxin, has been identified in canned and frozen peas by gas-liquid chromatography (GLC)/mass spectrometry. Eight samples were analyzed for MCIA using slightly modified official AOAC multiple pesticide residue procedures employing GLC with microcoulometric detection. Levels of MCIA averaged 0.20 ppm for canned peas and 0.16 ppm for frozen peas. Recovery of MCIA from a fortified sample was 40%.

  5. Numerical simulation of interface movement in gas-liquid two-phase flows with Level Set method

    International Nuclear Information System (INIS)

    Li Huixiong; Chinese Academy of Sciences, Beijing; Deng Sheng; Chen Tingkuan; Zhao Jianfu; Wang Fei

    2005-01-01

    Numerical simulation of gas-liquid two-phase flow and heat transfer has been an attractive work for a quite long time, but still remains as a knotty difficulty due to the inherent complexities of the gas-liquid two-phase flow resulted from the existence of moving interfaces with topology changes. This paper reports the effort and the latest advances that have been made by the authors, with special emphasis on the methods for computing solutions to the advection equation of the Level set function, which is utilized to capture the moving interfaces in gas-liquid two-phase flows. Three different schemes, i.e. the simple finite difference scheme, the Superbee-TVD scheme and the 5-order WENO scheme in combination with the Runge-Kutta method are respectively applied to solve the advection equation of the Level Set. A numerical procedure based on the well-verified SIMPLER method is employed to numerically calculate the momentum equations of the two-phase flow. The above-mentioned three schemes are employed to simulate the movement of four typical interfaces under 5 typical flowing conditions. Analysis of the numerical results shows that the 5-order WENO scheme and the Superbee-TVD scheme are much better than the simple finite difference scheme, and the 5-order WENO scheme is the best to compute solutions to the advection equation of the Level Set. The 5-order WENO scheme will be employed as the main scheme to get solutions to the advection equations of the Level Set when gas-liquid two-phase flows are numerically studied in the future. (authors)

  6. Prediction on Droplet Sauter Mean Diameter in Gas-Liquid Mist Flow Based on Droplet Fractal Theory

    Directory of Open Access Journals (Sweden)

    Jian-Yi Liu

    2015-01-01

    Full Text Available We present a fractal model for droplet Sauter mean diameter in gas-liquid mist flow, based on the droplet fractal theory and the balance relationship between total droplet surface energy and total gas turbulent kinetic energy. The present model is expressed as functions of the droplet fractal dimension, gas superficial velocity, liquid superficial velocity, and other fluid characteristics. Agreement between the present model predictions and experimental measurements is obtained. Results verify the reliability of the present model.

  7. Atomizing industrial gas-liquid flows – Development of an efficient hybrid VOF-LPT numerical framework

    International Nuclear Information System (INIS)

    Ström, Henrik; Sasic, Srdjan; Holm-Christensen, Olav; Shah, Louise Jivan

    2016-01-01

    Highlights: • Modelling of turbulent atomizing gas-liquid flows in real industrial devices. • A combined VOF-LPT framework with statistical coupling. • Regions of separated and dispersed multiphase flow treated simultaneously. • Statistical model based on a limited amount of highly resolved VOF data. - Abstract: Atomizing gas-liquid flows are used in industrial applications where high interphase heat and mass transfer rates and good mixing are of primary importance. Today, there is no single mathematical framework available to predict the entire liquid breakup process at an acceptable computational cost for a typical problem of industrial size. In this work, we develop a volume-of-fluid (VOF) framework that is combined with Lagrangian particle tracking (LPT) to take advantage of the respective strengths of these two approaches. The two frameworks are coupled via a statistical model that enables a transition from the VOF to the LPT formulation using input data about the primary breakup process obtained from detailed VOF simulations in dedicated switching zones. LPT-to-VOF transitions are handled directly by analyzing the proximity of LPT parcels to larger VOF structures. The combined framework is specifically designed to accommodate situations where atomization occurs in several locations simultaneously and when separated and dispersed turbulent gas-liquid flows co-exist in the same industrial unit. The procedure in which the statistical model is derived is presented and discussed, its performance is verified and the computational efficiency of the combined VOF-LPT model is assessed. Finally, the application of the coupled framework to the simulation of an industrial gas-liquid mixer with four separate atomization regions is presented.

  8. High efficiency chlorine removal from polyvinyl chloride (PVC) pyrolysis with a gas-liquid fluidized bed reactor.

    Science.gov (United States)

    Yuan, G; Chen, D; Yin, L; Wang, Z; Zhao, L; Wang, J Y

    2014-06-01

    In this research a gas-liquid fluidized bed reactor was developed for removing chlorine (Cl) from polyvinyl chloride (PVC) to favor its pyrolysis treatment. In order to efficiently remove Cl within a limited time before extensive generation of hydrocarbon products, the gas-liquid fluidized bed reactor was running at 280-320 °C, where hot N2 was used as fluidizing gas to fluidize the molten polymer, letting the molten polymer contact well with N2 to release Cl in form of HCl. Experimental results showed that dechlorination efficiency is mainly temperature dependent and 300 °C is a proper reaction temperature for efficient dechlorination within a limited time duration and for prevention of extensive pyrolysis; under this temperature 99.5% of Cl removal efficiency can be obtained within reaction time around 1 min after melting is completed as the flow rate of N2 gas was set around 0.47-0.85 Nm(3) kg(-1) for the molten PVC. Larger N2 flow rate and additives in PVC would enhance HCl release but did not change the final dechlorination efficiency; and excessive N2 flow rate should be avoided for prevention of polymer entrainment. HCl is emitted from PVC granules or scraps at the mean time they started to melt and the melting stage should be taken into consideration when design the gas-liquid fluidized bed reactor for dechlorination. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Single-phase ProtoDUNE, the Prototype of a Single-Phase Liquid Argon TPC for DUNE at the CERN Neutrino Platform

    CERN Document Server

    Cavanna, F; Touramanis, C

    2017-01-01

    ProtoDUNE-SP is the single-phase DUNE Far Detector prototype that is under construction and will be operated at the CERN Neutrino Platform (NP) starting in 2018. It was proposed to the CERN SPSC in June 2015 (SPSC-P-351) and was approved in December 2015 as experiment NP04 (ProtoDUNE). ProtoDUNE-SP, a crucial part of the DUNE effort towards the construction of the first DUNE 10-kt fiducial mass far detector module (17 kt total LAr mass), is a significant experiment in its own right. With a total liquid argon (LAr) mass of 0.77 kt, it represents the largest monolithic single phase LArTPC detector to be built to date. It is housed in an extension to the EHN1 hall in the North Area, where the CERN NP is providing a new dedicated charged-particle test beamline. ProtoDUNE-SP aims to take its first beam data before the LHC long shutdown (LS2) at the end of 2018. ProtoDUNE-SP prototypes the designs of most of the single-phase DUNE far detector module (DUNE-SP) components at a 1:1 scale, with an extrapolation of abo...

  10. Coordinated single-phase control scheme for voltage unbalance reduction in low voltage network.

    Science.gov (United States)

    Pullaguram, Deepak; Mishra, Sukumar; Senroy, Nilanjan

    2017-08-13

    Low voltage (LV) distribution systems are typically unbalanced in nature due to unbalanced loading and unsymmetrical line configuration. This situation is further aggravated by single-phase power injections. A coordinated control scheme is proposed for single-phase sources, to reduce voltage unbalance. A consensus-based coordination is achieved using a multi-agent system, where each agent estimates the averaged global voltage and current magnitudes of individual phases in the LV network. These estimated values are used to modify the reference power of individual single-phase sources, to ensure system-wide balanced voltages and proper power sharing among sources connected to the same phase. Further, the high X / R ratio of the filter, used in the inverter of the single-phase source, enables control of reactive power, to minimize voltage unbalance locally. The proposed scheme is validated by simulating a LV distribution network with multiple single-phase sources subjected to various perturbations.This article is part of the themed issue 'Energy management: flexibility, risk and optimization'. © 2017 The Author(s).

  11. Reliability Evaluation of a Single-phase H-bridge Inverter with Integrated Active Power Decoupling

    DEFF Research Database (Denmark)

    Tang, Junchaojie; Wang, Haoran; Ma, Siyuan

    2016-01-01

    Various power decoupling methods have been proposed recently to replace the DC-link Electrolytic Capacitors (E-caps) in single-phase conversion system, in order to extend the lifetime and improve the reliability of the DC-link. However, it is still an open question whether the converter level...... reliability becomes better or not, since additional components are introduced and the loading of the existing components may be changed. This paper aims to study the converter level reliability of a single-phase full-bridge inverter with two kinds of active power decoupling module and to compare...... it with the traditional passive DC-link solution. The converter level reliability is obtained by component level electro-thermal stress modeling, lifetime model, Weibull distribution, and Reliability Block Diagram (RBD) method. The results are demonstrated by a 2 kW single-phase inverter application....

  12. Field-circuit analysis and measurements of a single-phase self-excited induction generator

    Science.gov (United States)

    Makowski, Krzysztof; Leicht, Aleksander

    2017-12-01

    The paper deals with a single-phase induction machine operating as a stand-alone self-excited single-phase induction generator for generation of electrical energy from renewable energy sources. By changing number of turns and size of wires in the auxiliary stator winding, an improvement of performance characteristics of the generator were obtained as regards no-load and load voltage of the stator windings as well as stator winding currents of the generator. Field-circuit simulation models of the generator were developed using Flux2D software package for the generator with shunt capacitor in the main stator winding. The obtained results have been validated experimentally at the laboratory setup using the single-phase capacitor induction motor of 1.1 kW rated power and 230 V voltage as a base model of the generator.

  13. Benchmarking of grid fault modes in single-phase grid-connected photovoltaic systems

    DEFF Research Database (Denmark)

    Yang, Yongheng; Blaabjerg, Frede; Zou, Zhixiang

    2012-01-01

    Pushed by the booming installations of single-phase photovoltaic (PV) systems, the grid demands regarding the integration of PV systems are expected to be modified. Hence, the future PV systems should become more active with functionalities of low voltage ride-through (LVRT) and the grid support...... capability. The control methods, together with grid synchronization techniques, are responsible for the generation of appropriate reference signals in order to handle ride-through grid faults. Thus, it is necessary to evaluate the behaviors of grid synchronization methods and control possibilities in single...... phase systems under grid faults. The intent of this paper is to present a benchmarking of grid fault modes that might come in future single-phase PV systems. In order to map future challenges, the relevant detection and control strategies are discussed. Some faulty modes are studied experimentally...

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

    OpenAIRE

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

    2015-01-01

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

  15. 16 channel WDM regeneration in a single phase-sensitive amplifier through optical Fourier transformation

    DEFF Research Database (Denmark)

    Guan, Pengyu; Da Ros, Francesco; Lillieholm, Mads

    2016-01-01

    We demonstrate simultaneous phase regeneration of 16-WDM DPSK channels using optical Fourier transformation and a single phase-sensitive amplifier. The BERs of 16-WDM×10-Gbit/s phase noise degraded DPSK signals are improved by 0.4-1.3 orders of magnitude......We demonstrate simultaneous phase regeneration of 16-WDM DPSK channels using optical Fourier transformation and a single phase-sensitive amplifier. The BERs of 16-WDM×10-Gbit/s phase noise degraded DPSK signals are improved by 0.4-1.3 orders of magnitude...

  16. Single-phase power distribution system power flow and fault analysis

    Science.gov (United States)

    Halpin, S. M.; Grigsby, L. L.

    1992-01-01

    Alternative methods for power flow and fault analysis of single-phase distribution systems are presented. The algorithms for both power flow and fault analysis utilize a generalized approach to network modeling. The generalized admittance matrix, formed using elements of linear graph theory, is an accurate network model for all possible single-phase network configurations. Unlike the standard nodal admittance matrix formulation algorithms, the generalized approach uses generalized component models for the transmission line and transformer. The standard assumption of a common node voltage reference point is not required to construct the generalized admittance matrix. Therefore, truly accurate simulation results can be obtained for networks that cannot be modeled using traditional techniques.

  17. Common-Ground-Type Tansformerless Inverters for Single-Phase Solar Photovoltaic Systems

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Blaabjerg, Frede

    2018-01-01

    This paper proposes a family of novel flying capacitor transformerless inverters for single-phase photovoltaic (PV) systems. Each of the new topologies proposed is based on a flying capacitor principle and requires only four power switches and/or diodes, one capacitor, and a small filter at the o......This paper proposes a family of novel flying capacitor transformerless inverters for single-phase photovoltaic (PV) systems. Each of the new topologies proposed is based on a flying capacitor principle and requires only four power switches and/or diodes, one capacitor, and a small filter...

  18. Challenges in thermal design of industrial single-phase power inverter

    Directory of Open Access Journals (Sweden)

    Ninković Predrag

    2016-01-01

    Full Text Available This paper presents the influence of thermal aspects in design process of an industrial single-phase inverter, choice of its topology and components. Stringent design inputs like very high overload level, demand for natural cooling and very wide input voltage range have made conventional circuit topology inappropriate therefore asking for alternative solution. Different power losses calculations in semiconductors are performed and compared, outlining the guidelines how to choose the final topology. Some recommendations in power magnetic components design are given. Based on the final project, a 20kVA single-phase inverter for thermal power plant supervisory and control system is designed and commissioned.

  19. Stability boundary analysis in single-phase grid-connected inverters with PLL by LTP theory

    OpenAIRE

    Salis, Valerio; Costabeber, Alessando; Cox, Stephen M.; Zanchetta, Pericle; Formentini, Andrea

    2017-01-01

    Stability analysis of power converters in AC net¬works is complex due to the non-linear nature of the conversion systems. Whereas interactions of converters in DC networks can be studied by linearising about the operating point, the extension of the same approach to AC systems poses serious challenges, especially for single-phase or unbalanced three-phase systems. A general method for stability analysis of power converters suitable for single-phase or unbalanced AC networks is presented in th...

  20. Soft-Switched Neutral-Point-Clamped Single-Phase Boost Rectifier

    Science.gov (United States)

    Itoh, Ryozo; Ishizaka, Kouichi

    A soft-switched neutral-point-clamped single-phase boost rectifier capable of compensating the imbalance load voltage is studied. This is based on a single-phase rectifier, in which an inductor is placed in series with the AC supply to resonate with a capacitor connected across the DC output of a full-bridge rectifier and the switching transition is mainly governed by a series resonance. The experimental prototype using insulated-gate bipolar transistors is implemented to investigate the operation under the charge control. The experimental results confirm that the rectifier has a neutral-point-clamp feature providing a good quality AC current.

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

    International Nuclear Information System (INIS)

    Schmidt, Patrick; Lucquiaud, Mathieu; Valluri, Prashant; Ó Náraigh, Lennon

    2016-01-01

    We consider the genesis and dynamics of interfacial instability in vertical 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 two main flow parameters on the interfacial dynamics, namely the film thickness and pressure drop applied to drive the gas stream. To make contact with existing studies in the literature, the effect of various density contrasts is also examined. 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 interfacial mode for low density contrast. A study of absolute and convective instability for low density contrast shows that the system is absolutely unstable for all but two narrow regions of the investigated parameter space. Direct numerical simulations of the same system (low density contrast) show that linear theory holds up remarkably well upon the onset of large-amplitude waves as well as the existence of weakly nonlinear waves. For high density contrasts, corresponding more closely to an air-water-type system, linear stability theory is also successful at determining the most-dominant features in the interfacial wave dynamics at early-to-intermediate times. Nevertheless, the short waves selected by the linear theory undergo secondary instability and the wave train is no longer regular but rather exhibits chaotic motion. The same linear stability theory predicts when the direction of travel of the waves changes — from downwards to upwards. We outline the practical implications of this change in terms of loading and flooding. The change in direction of the

  2. A Novel Flying Capacitor Transformerless Inverter for Single-Phase Grid Connected Solar Photovoltaic System

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Blaabjerg, Frede

    2016-01-01

    This paper proposes a new single-phase flying capacitor transformerless PV inverter for grid-connected photovoltaic (PV) systems. The neutral of the grid can be directly connected to the negative terminal of the source (PV). It consists of four power switches, one diode, one capacitor and a small...

  3. A single phase multilevel inverter as power converter for 3-phase ...

    African Journals Online (AJOL)

    A single phase multilevel inverter as power converter for 3-phase electric loads. ... m-phase maker was simulated using MATLAB and the results confirmed the excellent perfor-mance of the RBNPS. The listed advantages attained could be incorporated in the design and operation of a converter for an electric drive of a car.

  4. Low Voltage Ride-Through of Single-Phase Transformerless Photovoltaic Inverters

    DEFF Research Database (Denmark)

    Yang, Yongheng; Blaabjerg, Frede; Wang, Huai

    2014-01-01

    , e.g. Low Voltage Ride-Through (LVRT) under grid faults and grid support service. In order to map future challenges, the LVRT capability of three mainstream single-phase transformerless PV inverters under grid faults are explored in this paper. Control strategies with reactive power injections...

  5. PI and repetitive control for single phase inverter based on virtual rotating coordinate system

    Science.gov (United States)

    Li, Mengqi; Tong, Yibin; Jiang, Jiuchun; Liang, Jiangang

    2018-03-01

    Microgrid technology developed rapidly and nonlinear loads were connected increasingly. A new control strategy was proposed for single phase inverter when connected nonlinear loads under island condition. PI and repetitive compound controller was realized under synchronous rotating coordinate system and acquired high quality sinusoidal voltage output without voltage spike when loads step changed. Validity and correctness were verified by simulation using MATLAB/Simulink.

  6. Pressure Drop Correlations of Single-Phase and Two-Phase Flow in Rolling Tubes

    International Nuclear Information System (INIS)

    Xia-xin Cao; Chang-qi Yan; Pu-zhen Gao; Zhong-ning Sun

    2006-01-01

    A series of experimental studies of frictional pressure drop for single phase and two-phase bubble flow in smooth rolling tubes were carried out. The tube inside diameters were 15 mm, 25 mm and 34.5 mm respectively, the rolling angles of tubes could be set as 10 deg. and 20 deg., and the rolling periods could be set as 5 s, 10 s and 15 s. Combining with the analysis of single-phase water motion, it was found that the traditional correlations for calculating single-phase frictional coefficient were not suitable for the rolling condition. Based on the experimental data, a new correlation for calculating single-phase frictional coefficient under rolling condition was presented, and the calculations not only agreed well with the experimental data, but also could display the periodically dynamic characteristics of frictional coefficients. Applying the new correlation to homogeneous flow model, two-phase frictional pressure drop of bubble flow in rolling tubes could be calculated, the results showed that the relative error between calculation and experimental data was less than ± 25%. (authors)

  7. Single-Phase 3L PR Controlled qZS Inverter Connected to the Distorted Grid

    DEFF Research Database (Denmark)

    Makovenko, Elena; Husev, Oleksandr; Roncero-Clemente, Carlos

    2016-01-01

    This paper presents a single-phase three-level NPC qZS inverter connected to a distorted grid using PID and PR regulators. A case study system along with the control strategy are described. Tuning approaches for PID and PR regulators are addressed and validated by means of simulation results...

  8. Hybrid Control Method for a Single Phase PFC using a Low Cost Microcontroller

    DEFF Research Database (Denmark)

    Jakobsen, Lars Tønnes; Nielsen, Nils; Wolf, Christian

    2005-01-01

    This paper presents a hybrid control method for single phase boost PFCs. The high bandwidth current loop is analog while the voltage loop is implemented in an 8-bit microcontroller. The design focuses on minimizing the number of calculations done in the microcontroller. A 1kW prototype has been...

  9. Novel Motion Sensorless Control of Single Phase Brushless D.C. PM Motor Drive, with experiments

    DEFF Research Database (Denmark)

    Lepure, Liviu Ioan; Boldea, Ion; Andreescu, Gheorghe Daniel

    2010-01-01

    A motion sensorless control for single phase permanent magnet brushless d.c. (PM-BLDC) motor drives, based on flux integration and prior knowledge of the PM flux/position characteristic is proposed here and an adequate correction algorithm is adopted, in order to increase the robustness to noise...

  10. Single phase inverter for a three phase power generation and distribution system

    Science.gov (United States)

    Lindena, S. J.

    1976-01-01

    A breadboard design of a single-phase inverter with sinusoidal output voltage for a three-phase power generation and distribution system was developed. The three-phase system consists of three single-phase inverters, whose output voltages are connected in a delta configuration. Upon failure of one inverter the two remaining inverters will continue to deliver three-phase power. Parallel redundancy as offered by two three-phase inverters is substituted by one three-phase inverter assembly with high savings in volume, weight, components count and complexity, and a considerable increase in reliability. The following requirements must be met: (1) Each single-phase, current-fed inverter must be capable of being synchronized to a three-phase reference system such that its output voltage remains phaselocked to its respective reference voltage. (2) Each single-phase, current-fed inverter must be capable of accepting leading and lagging power factors over a range from -0.7 through 1 to +0.7.

  11. Control Method of Single-phase Inverter Based Grounding System in Distribution Networks

    DEFF Research Database (Denmark)

    Wang, Wen; Yan, L.; Zeng, X.

    2016-01-01

    of neutral-to-ground voltage is critical for the safety of distribution networks. An active grounding system based on single-phase inverter is proposed to achieve this objective. Relationship between output current of the system and neutral-to-ground voltage is derived to explain the principle of neutral...

  12. protoDUNE-Single Phase and protDUNE-DualPhase

    CERN Multimedia

    Brice, Maximilien

    2016-01-01

    At the EHN1 two big 8m x 8m x8m detector prototypes (protoDUNE-Single Phase and protDUNE-DualPhase) are being constructed. The aim is to test technologies and detector performances for DUNE, a new generation of LBN neutr

  13. Single phase cascaded H5 inverter with leakage current elimination for transformerless photovoltaic system

    DEFF Research Database (Denmark)

    Guo, Xiaoqiang; Jia, X.; Lu, Z.

    2016-01-01

    Leakage current reduction is one of the important issues for the transformelress PV systems. In this paper, the transformerless single-phase cascaded H-bridge PV inverter is investigated. The common mode model for the cascaded H4 inverter is analyzed. And the reason why the conventional cascade H...

  14. A Generic Topology Derivation Method for Single-phase Converters with Active Capacitive DC-links

    DEFF Research Database (Denmark)

    Wang, Haoran; Wang, Huai; Zhu, Guorong

    2016-01-01

    capacitive DCDC- link solutions, but important aspects of the topology assess-ment, such as the total energy storage, overall capacitive energy buffer ratio, cost, and reliability are still not available. This paper proposes a generic topology derivation method of single-phase power converters...

  15. Modeling and Control of a Single-Phase Marine Cooling System

    DEFF Research Database (Denmark)

    Hansen, Michael; Stoustrup, Jakob; Bendtsen, Jan Dimon

    2013-01-01

    This paper presents two model-based control design approaches for a single-phase marine cooling system. Models are derived from first principles and aim at describing significant system dynamics including nonlinearities and transport delays, while keeping the model complexity low. The two...

  16. Single-Phase Phase-Locked Loop Based on Derivative Elements

    DEFF Research Database (Denmark)

    Guan, Qingxin; Zhang, Yu; Kang, Yong

    2017-01-01

    High-performance phase-locked loops (PLLs) are critical for power control in grid-connected systems. This paper presents a new method of designing a PLL for single-phase systems based on derivative elements (DEs). The quadrature signal generator (QSG) is constructed by two DEs with the same...

  17. A review of single-phase grid-connected inverters for photovoltaic modules

    DEFF Research Database (Denmark)

    Kjaer, Soren Baekhoej; Pedersen, John Kim; Blaabjerg, Frede

    2005-01-01

    This review focuses on inverter technologies for connecting photovoltaic (PV) modules to a single-phase grid. The inverters are categorized into four classifications: 1) the number of power processing stages in cascade; 2) the type of power decoupling between the PV module(s) and the single...

  18. A Direct Maximum Power Point Tracking Method for Single-Phase Grid Connected PV Inverters

    DEFF Research Database (Denmark)

    EL Aamri, Faicel; Maker, Hattab; Sera, Dezso

    2018-01-01

    in dynamic conditions, especially in low irradiance when the measurement of signals becomes more sensitive to noise. The proposed MPPT is designed for single-phase single-stage grid-connected PV inverters, and is based on estimating the instantaneous PV power and voltage ripples, using second...

  19. A re-look at critical factors influencing single-phase formation of Ba2 ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 30; Issue 4. A re-look at critical factors influencing single-phase formation of Ba2Ti9O20 microwave dielectrics. Unnikrishnan Gopinath Dhanya Chandran Seema Ansari Bindu Krishnan Rani Panicker Raghu Natarajan. Electrical Properties Volume 30 Issue 4 August ...

  20. Regeneration of phase unlocked serial multiplexed DPSK signals in a single phase sensitive amplifier

    DEFF Research Database (Denmark)

    Guan, Pengyu; Da Ros, Francesco; Kjøller, Niels-Kristian

    2017-01-01

    We demonstrate phase-regeneration of phase unlocked OTDM-DPSK serial signals in a single phase sensitive amplifier through optical cross-phase modulation. The BER of an 8×10 Gbit/s OTDM-DPSK signal is improved by 2 orders of magnitude....

  1. Analysis of Variable-Speed Operation of Drives with Single-Phase Machines

    Czech Academy of Sciences Publication Activity Database

    Chomát, Miroslav; Schreier, Luděk; Bendl, Jiří

    2007-01-01

    Roč. 52, č. 2 (2007), s. 139-147 ISSN 0001-7043 R&D Projects: GA ČR GA102/06/0215 Institutional research plan: CEZ:AV0Z20570509 Keywords : single-phase machines * induction machines * variable-speed drives Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  2. Flux Concentration and Pole Shaping in a Single Phase Hybrid Switched Reluctance Motor Drive

    DEFF Research Database (Denmark)

    Jakobsen, Uffe; Lu, Kaiyuan

    2010-01-01

    The single phase hybrid switched reluctance motor (HSRM) may be a good candidate for low-cost drives used for pump applications. This paper presents a new design of the HSRM with improved starting torque achieved by stator pole shaping, and a better arrangement of the embedded stator permanent...

  3. Synchronization in single-phase grid-connected photovoltaic systems under grid faults

    DEFF Research Database (Denmark)

    Yang, Yongheng; Blaabjerg, Frede

    2012-01-01

    under grid faults. The focus of this paper is put on the benchmarking of synchronization techniques, mainly about phase locked loop (PLL) based methods, in single-phase PV power systems operating under grid faults. Some faulty mode cases are studied at the end of this paper in order to compare...

  4. Derivation of simplified basic equations of gas-liquid two-phase dispersed flow based on two-fluid model

    International Nuclear Information System (INIS)

    Kataoka, Isao; Tomiyama, Akio

    2004-01-01

    The simplified and physically reasonable basic equations for the gas-liquid dispersed flow were developed based on some appropriate assumptions and the treatment of dispersed phase as isothermal rigid particles. Based on the local instant formulation of mass, momentum and energy conservation of the dispersed flow, time-averaged equations were obtained assuming that physical quantities in the dispersed phase are uniform. These assumptions are approximately valid when phase change rate and/or chemical reaction rate are not so large at gas-liquid interface and there is no heat generation in within the dispersed phase. Detailed discussions were made on the characteristics of obtained basic equations and physical meanings of terms consisting the basic equations. It is shown that, in the derived averaged momentum equation, the terms of pressure gradient and viscous momentum diffusion do not appear and, in the energy equation, the term of molecular thermal diffusion heat flux does not appear. These characteristics of the derived equations were shown to be very consistent concerning the physical interpretation of the gas-liquid dispersed flow. Furthermore, the obtained basic equations are consistent with experiments for the dispersed flow where most of averaged physical quantities are obtained assuming that the distributions of those are uniform within the dispersed phase. Investigation was made on the problem whether the obtained basic equations are well-posed or ill-posed for the initial value problem. The eigenvalues of the simplified mass and momentum equations are calculated for basic equations obtained here and previous two-fluid basic equations with one pressure model. Well-posedness and ill-posedness are judged whether the eigenvalues are real or imaginary. The result indicated the newly developed basic equations always constitute the well-posed initial value problem while the previous two-fluid basic equations based on one pressure model constitutes ill

  5. Development of a single-phase thermosiphon for cold collection and storage of radiative cooling

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Dongliang; Martini, Christine Elizabeth; Jiang, Siyu; Ma, Yaoguang; Zhai, Yao; Tan, Gang; Yin, Xiaobo; Yang, Ronggui

    2017-11-01

    A single-phase thermosiphon is developed for cold collection and storage of radiative cooling. Compared to the conventional nocturnal radiative cooling systems that use an electric pump to drive the heat transfer fluid, the proposed single-phase thermosiphon uses the buoyancy force to drive heat transfer fluid. This solution does not require electricity, therefore improving the net gain of the radiative cooling system. A single-phase thermosiphon was built, which consists of a flat panel, a cold collection tank, a water return tube, and a water distribution tank. Considering that outdoor radiative cooling flux is constantly changing (i.e. uncontrollable), an indoor testing facility was developed to provide a controllable cooling flux (comparable to a radiative cooling flux of 100 W/m2) for the evaluation of thermosiphon performance. The testing apparatus is a chilled aluminum flat plate that has a controlled air gap separation relative to the flat panel surface of the thermosiphon to emulate radiative cooling. With an average of 105 W/m2 cooling flux, the 18 liters of water in the thermosiphon was cooled to an average temperature of 12.5 degrees C from an initial temperature of 22.2 degrees C in 2 h, with a cold collection efficiency of 96.8%. The results obtained have demonstrated the feasibility of using a single-phase thermosiphon for cold collection and storage of radiative cooling. Additionally, the effects of the thermosiphon operation conditions, such as tilt angle of the flat panel, initial water temperature, and cooling energy flux, on the performance have been experimentally investigated. Modular design of the single-phase thermosiphon gives flexibility for its scalability. A radiative cooling system with multiple thermosiphon modules is expected to play an important role in cooling buildings and power plant condensers.

  6. Bubble parameters analysis of gas-liquid two-phase sparse bubbly flow based on image method

    International Nuclear Information System (INIS)

    Zhou Yunlong; Zhou Hongjuan; Song Lianzhuang; Liu Qian

    2012-01-01

    The sparse rising bubbles of gas-liquid two-phase flow in vertical pipe were measured and studied based on image method. The bubble images were acquired by high-speed video camera systems, the characteristic parameters of bubbles were extracted by using image processing techniques. Then velocity variation of rising bubbles were drawn. Area and centroid variation of single bubble were also drawn. And then parameters and movement law of bubbles were analyzed and studied. The test results showed that parameters of bubbles had been analyzed well by using image method. (authors)

  7. Synthesis of nano-bio conjugates for drug delivery systems using gas-liquid interfacial discharge plasmas

    International Nuclear Information System (INIS)

    Kaneko, Toshiro; Chen, Qiang; Hatakeyama, Rikizo

    2012-01-01

    Size-controlled gold nanoparticles (AuNPs) covered with DNA are synthesized by using a pulse driven gas-liquid interfacial discharge plasma (GLIDP) to reduce an aqueous solution of chloroauric acid trihydrate with DNA. The size and the assembly of the AuNPs are found to be easily controlled by changing the DNA concentration in the aqueous solution. The synthesized AuNP-DNA conjugates are forced to be encapsulated into double-walled carbon nanotubes (DWNTs) by superimposing a positive DC voltage on the pulse voltage. The AuNP-DNA-conjugate encapsulated DWNTs can be utilized in drug delivery systems when DNA is used as a drug molecule.

  8. Effects of wettability on forced convective and gas-liquid two-phase flow heat transfer of mercury

    International Nuclear Information System (INIS)

    Nakagawa, Yusuke; Kawakita, Keisuke; Takenaka, Nobuyuki

    2003-01-01

    High-energy proton beam is irradiated to a target made of high atomic number materials to initiate nuclear spallation reaction to obtain neutron source. A mercury target is now a candidate of the target for the intense proton beam. It is important to study thermal hydraulics of the mercury target. In this study, mercury was used as a working fluid in a stainless steel tube heated by direct electrical current in similar thermal hydraulic situation to the actual target. The effects of mercury wettability on forced convective heat transfer and gas-liquid two-phase flow heat transfer were verified. (author)

  9. Summary on experimental methods for statistical transient analysis of two-phase gas-liquid flow. [BWR, PWR, and LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Delhaye, J M; Jones, Jr, O C

    1976-06-01

    Much work has been done in the study of two-phase gas-liquid flows. Although it has been recognized superficially that such flows are not homogeneous in general, little attention has been paid to the inherent discreteness of the two-phase systems. Only relatively recently have fluctuating characteristics of two-phase flows been studied in detail. As a result, new experimental devices and techniques have been developed for use in measuring quantities previously ignored. This report reviews and summarizes most of these methods in an effort to emphasize the importance of the fluctuating nature of these flows and as a guide to further research in this field.

  10. Simultaneous determination of oxalic, citric, nitrilotriacetic and ethylenediamenetetraacetic acids by gas liquid chromatography of their methyl esters

    International Nuclear Information System (INIS)

    Eskell, C.J.; Pick, M.E.

    1980-04-01

    A procedure for simultaneous determination of ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), citric acid and oxalic acid by gas liquid chromatography is described. The involatile acids are first concerted to their volatile methyl ester derivatives by reaction with boron trifluoride in methanol. Transition metal ions (Fe 3+ , Cr 3+ and Ni 2+ ) which will be present in decontamination liquors from nuclear reactors, and form strong chelates with the acids, have been shown to cause no interference to the esterification reaction. The esters were separated by temperature programming on a 3.5 metre capillary column packed with 3% OV1 on Diatomite CQ and were detected by flame ionisation. (author)

  11. Numerical modelling of isothermal gas-liquid two-phase bubbly flow in vertical pipes

    International Nuclear Information System (INIS)

    Yamoah, S.

    2014-07-01

    In order to qualify CFD codes for accurate numerical predictions of transient evolution of flow regimes in a vertical gas-liquid two-phase flow, suitable closure models are needed. The current study focuses on detailed numerical investigation of the interfacial driving force models and assessment of two population balance model approaches viz. the MUltiple-Size-Group (MUSIG) and one-group Interfacial Area Transport Equation (lATE) using the two-fluid modelling approach. Numerical predictions of five primitive variables: gas volume fraction, interfacial area concentration, Sauter mean bubble diameter, gas velocity and liquid velocity; have been validated against experimental data of Monros et al., (2013). Three specific objectives have been completed in this study. Firstly, under the assumption of mono-disperse bubbles, a consistent set of interfacial force models have been investigated. The effect of drag, lift, wall lubrication and turbulent dispersion forces has been assessed. New parameters have been introduced in the wall lubrication force models of Antal et al., (1991) and Frank et al., (2004, 2008) as well as implementing additional drag coefficient models using CFX Expression Language (CEl). The Tomiyama, (1998) lift coefficient model has been modified in this study. In general, the predictions from the sets of interfacial force models yielded satisfactory agreement with the experimental data. A set of Grace drag coefficient model, Tomiyama lift coefficient model, Antal wall force model, and Favre averaged turbulent dispersion force were found to provide the best agreement with the experimental data. Secondly, a model validation study to assess the performance of existing coalescence and breakup models of the MUSIG model in simulating bubbly flow in vertical configuration has been conducted. The breakup model of Luo and Svendsen, (1996) and coalescence model of Prince and Blanch, (1990) have been implemented. Detailed analysis has been performed for the wall

  12. A New Method for Ultrasound Detection of Interfacial Position in Gas-Liquid Two-Phase Flow

    Directory of Open Access Journals (Sweden)

    Fábio Rizental Coutinho

    2014-05-01

    Full Text Available Ultrasonic measurement techniques for velocity estimation are currently widely used in fluid flow studies and applications. An accurate determination of interfacial position in gas-liquid two-phase flows is still an open problem. The quality of this information directly reflects on the accuracy of void fraction measurement, and it provides a means of discriminating velocity information of both phases. The algorithm known as Velocity Matched Spectrum (VM Spectrum is a velocity estimator that stands out from other methods by returning a spectrum of velocities for each interrogated volume sample. Interface detection of free-rising bubbles in quiescent liquid presents some difficulties for interface detection due to abrupt changes in interface inclination. In this work a method based on velocity spectrum curve shape is used to generate a spatial-temporal mapping, which, after spatial filtering, yields an accurate contour of the air-water interface. It is shown that the proposed technique yields a RMS error between 1.71 and 3.39 and a probability of detection failure and false detection between 0.89% and 11.9% in determining the spatial-temporal gas-liquid interface position in the flow of free rising bubbles in stagnant liquid. This result is valid for both free path and with transducer emitting through a metallic plate or a Plexiglas pipe.

  13. CdS QDs-chitosan microcapsules with stimuli-responsive property generated by gas-liquid microfluidic technique.

    Science.gov (United States)

    Chen, Yanjun; Yao, Rongyi; Wang, Yifeng; Chen, Ming; Qiu, Tong; Zhang, Chaocan

    2015-01-01

    This article describes a straightforward gas-liquid microfluidic approach to generate uniform-sized chitosan microcapsules containing CdS quantum dots (QDs). CdS QDs are encapsulated into the liquid-core of the microcapsules. The sizes of the microcapsules can be conveniently controlled by gas flow rate. QDs-chitosan microcapsules show good fluorescent stability in water, and exhibit fluorescent responses to chemical environmental stimuli. α-Cyclodextrin (α-CD) causes the microcapsules to deform and even collapse. More interestingly, α-CD induces obvious changes on the fluorescent color of the microcapsules. However, β-cyclodextrin (β-CD) has little influence on the shape and fluorescent color of the microcapsules. Based on the results of scanning electron microscopy, the possible mechanism about the effects of α-CD on the chitosan microcapsules is analyzed. These stimuli-responsive microcapsules are low-cost and easy to be prepared by gas-liquid microfluidic technique, and can be applied as a potential micro-detector to chemicals, such as CDs. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. CFD Modeling of Gas-Liquid Bubbly Flow in Horizontal Pipes: Influence of Bubble Coalescence and Breakup

    Directory of Open Access Journals (Sweden)

    K. Ekambara

    2012-01-01

    Full Text Available Modelling of gas-liquid bubbly flows is achieved by coupling a population balance equation with the three-dimensional, two-fluid, hydrodynamic model. For gas-liquid bubbly flows, an average bubble number density transport equation has been incorporated in the CFD code CFX 5.7 to describe the temporal and spatial evolution of the gas bubbles population. The coalescence and breakage effects of the gas bubbles are modeled. The coalescence by the random collision driven by turbulence and wake entrainment is considered, while for bubble breakage, the impact of turbulent eddies is considered. Local spatial variations of the gas volume fraction, interfacial area concentration, Sauter mean bubble diameter, and liquid velocity are compared against experimental data in a horizontal pipe, covering a range of gas (0.25 to 1.34 m/s and liquid (3.74 to 5.1 m/s superficial velocities and average volume fractions (4% to 21%. The predicted local variations are in good agreement with the experimental measurements reported in the literature. Furthermore, the development of the flow pattern was examined at three different axial locations of L/D = 25, 148, and 253. The first location is close to the entrance region where the flow is still developing, while the second and the third represent nearly fully developed bubbly flow patterns.

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

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  16. Characterizing the correlations between local phase fractions of gas-liquid two-phase flow with wire-mesh sensor.

    Science.gov (United States)

    Tan, C; Liu, W L; Dong, F

    2016-06-28

    Understanding of flow patterns and their transitions is significant to uncover the flow mechanics of two-phase flow. The local phase distribution and its fluctuations contain rich information regarding the flow structures. A wire-mesh sensor (WMS) was used to study the local phase fluctuations of horizontal gas-liquid two-phase flow, which was verified through comparing the reconstructed three-dimensional flow structure with photographs taken during the experiments. Each crossing point of the WMS is treated as a node, so the measurement on each node is the phase fraction in this local area. An undirected and unweighted flow pattern network was established based on connections that are formed by cross-correlating the time series of each node under different flow patterns. The structure of the flow pattern network reveals the relationship of the phase fluctuations at each node during flow pattern transition, which is then quantified by introducing the topological index of the complex network. The proposed analysis method using the WMS not only provides three-dimensional visualizations of the gas-liquid two-phase flow, but is also a thorough analysis for the structure of flow patterns and the characteristics of flow pattern transition. This article is part of the themed issue 'Supersensing through industrial process tomography'. © 2016 The Author(s).

  17. Measurement of gas-liquid two-phase flow in micro-pipes by a capacitance sensor.

    Science.gov (United States)

    Ji, Haifeng; Li, Huajun; Huang, Zhiyao; Wang, Baoliang; Li, Haiqing

    2014-11-26

    A capacitance measurement system is developed for the measurement of gas-liquid two-phase flow in glass micro-pipes with inner diameters of 3.96, 2.65 and 1.56 mm, respectively. As a typical flow regime in a micro-pipe two-phase flow system, slug flow is chosen for this investigation. A capacitance sensor is designed and a high-resolution and high-speed capacitance measurement circuit is used to measure the small capacitance signals based on the differential sampling method. The performance and feasibility of the capacitance method are investigated and discussed. The capacitance signal is analyzed, which can reflect the voidage variation of two-phase flow. The gas slug velocity is determined through a cross-correlation technique using two identical capacitance sensors. The simulation and experimental results show that the presented capacitance measurement system is successful. Research work also verifies that the capacitance sensor is an effective method for the measurement of gas liquid two-phase flow parameters in micro-pipes.

  18. The Development of a Gas-Liquid Two-Phase Flow Sensor Applicable to CBM Wellbore Annulus.

    Science.gov (United States)

    Wu, Chuan; Wen, Guojun; Han, Lei; Wu, Xiaoming

    2016-11-18

    The measurement of wellbore annulus gas-liquid two-phase flow in CBM (coalbed methane) wells is of great significance for reasonably developing gas drainage and extraction processes, estimating CBM output, judging the operating conditions of CBM wells and analyzing stratum conditions. Hence, a specially designed sensor is urgently needed for real-time measurement of gas-liquid two-phase flow in CBM wellbore annulus. Existing flow sensors fail to meet the requirements of the operating conditions of CBM wellbore annulus due to such factors as an inapplicable measurement principle, larger size, poor sealability, high installation accuracy, and higher requirements for fluid media. Therefore, based on the principle of a target flowmeter, this paper designs a new two-phase flow sensor that can identify and automatically calibrate different flow patterns of two-phase flows. Upon the successful development of the new flow sensor, lab and field tests were carried out, and the results show that the newly designed sensor, with a measurement accuracy of ±2.5%, can adapt to the operating conditions of CBM wells and is reliable for long-term work.

  19. A new method for ultrasound detection of interfacial position in gas-liquid two-phase flow.

    Science.gov (United States)

    Coutinho, Fábio Rizental; Ofuchi, César Yutaka; de Arruda, Lúcia Valéria Ramos; Neves, Flávio; Morales, Rigoberto E M

    2014-05-22

    Ultrasonic measurement techniques for velocity estimation are currently widely used in fluid flow studies and applications. An accurate determination of interfacial position in gas-liquid two-phase flows is still an open problem. The quality of this information directly reflects on the accuracy of void fraction measurement, and it provides a means of discriminating velocity information of both phases. The algorithm known as Velocity Matched Spectrum (VM Spectrum) is a velocity estimator that stands out from other methods by returning a spectrum of velocities for each interrogated volume sample. Interface detection of free-rising bubbles in quiescent liquid presents some difficulties for interface detection due to abrupt changes in interface inclination. In this work a method based on velocity spectrum curve shape is used to generate a spatial-temporal mapping, which, after spatial filtering, yields an accurate contour of the air-water interface. It is shown that the proposed technique yields a RMS error between 1.71 and 3.39 and a probability of detection failure and false detection between 0.89% and 11.9% in determining the spatial-temporal gas-liquid interface position in the flow of free rising bubbles in stagnant liquid. This result is valid for both free path and with transducer emitting through a metallic plate or a Plexiglas pipe.

  20. A New Void Fraction Measurement Method for Gas-Liquid Two-Phase Flow in Small Channels.

    Science.gov (United States)

    Li, Huajun; Ji, Haifeng; Huang, Zhiyao; Wang, Baoliang; Li, Haiqing; Wu, Guohua

    2016-01-27

    Based on a laser diode, a 12 × 6 photodiode array sensor, and machine learning techniques, a new void fraction measurement method for gas-liquid two-phase flow in small channels is proposed. To overcome the influence of flow pattern on the void fraction measurement, the flow pattern of the two-phase flow is firstly identified by Fisher Discriminant Analysis (FDA). Then, according to the identification result, a relevant void fraction measurement model which is developed by Support Vector Machine (SVM) is selected to implement the void fraction measurement. A void fraction measurement system for the two-phase flow is developed and experiments are carried out in four different small channels. Four typical flow patterns (including bubble flow, slug flow, stratified flow and annular flow) are investigated. The experimental results show that the development of the measurement system is successful. The proposed void fraction measurement method is effective and the void fraction measurement accuracy is satisfactory. Compared with the conventional laser measurement systems using standard laser sources, the developed measurement system has the advantages of low cost and simple structure. Compared with the conventional void fraction measurement methods, the proposed method overcomes the influence of flow pattern on the void fraction measurement. This work also provides a good example of using low-cost laser diode as a competent replacement of the expensive standard laser source and hence implementing the parameter measurement of gas-liquid two-phase flow. The research results can be a useful reference for other researchers' works.

  1. A simple microfluidic chlorine gas sensor based on gas-liquid chemiluminescence of luminol-chlorine system.

    Science.gov (United States)

    Gao, Zhao-Xin; Li, Hai-Fang; Liu, Jiangjiang; Lin, Jin-Ming

    2008-08-01

    In this work, a microfluidic chlorine gas sensor based on gas-liquid interface absorption and chemiluminescence detection was described. The liquid chemiluminescence reagent-alkaline luminol solution can be stably sandwiched between two convex halves of a microchannel by surface tension. When chlorine gas was introduced into the micro device, it was dissolved into the interfacial luminol solution and transferred to ClO(-), and simultaneously luminol was excited and chemiluminescence emitted. The emitted chemiluminescence light was perpendicularly detected by a photomultiplier tube on a certain detection region. The remarkable advantage of the detection system is that both adsorption and detection were carried out at the gas-liquid interface, which avoids the appearance of bubbles. The whole analytical cycle including filling CL reagent, sample injection, CL detection and emptying the device was as short as 30 s. The linear concentration range of chlorine gas detection with direct introduction of sample method is from 0.5 to 478 ppm. The detection limit of this method is 0.2 ppm for standard chlorine gas and the relative standard deviation of five determinations of 3.19 ppm spiked chlorine sample was 5.2%.

  2. Measurement of Gas-Liquid Two-Phase Flow in Micro-Pipes by a Capacitance Sensor

    Directory of Open Access Journals (Sweden)

    Haifeng Ji

    2014-11-01

    Full Text Available A capacitance measurement system is developed for the measurement of gas-liquid two-phase flow in glass micro-pipes with inner diameters of 3.96, 2.65 and 1.56 mm, respectively. As a typical flow regime in a micro-pipe two-phase flow system, slug flow is chosen for this investigation. A capacitance sensor is designed and a high-resolution and high-speed capacitance measurement circuit is used to measure the small capacitance signals based on the differential sampling method. The performance and feasibility of the capacitance method are investigated and discussed. The capacitance signal is analyzed, which can reflect the voidage variation of two-phase flow. The gas slug velocity is determined through a cross-correlation technique using two identical capacitance sensors. The simulation and experimental results show that the presented capacitance measurement system is successful. Research work also verifies that the capacitance sensor is an effective method for the measurement of gas liquid two-phase flow parameters in micro-pipes.

  3. Determination of gas-liquid partition coefficients of several organic solutes in trihexyl(tetradecyl)phosphonium bromide using capillary gas chromatography columns.

    Science.gov (United States)

    Ronco, Nicolás R; Menestrina, Fiorella; Romero, Lílian M; Castells, Cecilia B

    2017-06-09

    In this paper, we report gas-liquid partition constants for thirty-five volatile organic solutes in the room temperature ionic liquid trihexyl(tetradecyl)phosphonium bromide measured by gas-liquid chromatography using capillary columns. The relative contribution of gas-liquid partition and interfacial adsorption to retention was evaluated through the use of columns with different the phase ratio. Four capillary columns with exactly known phase ratios were constructed and employed to measure the solute retention factors at four temperatures between 313.15 and 343.15K. The partition coefficients were calculated from the slopes of the linear regression between solute retention factors and the reciprocal of phase ratio at a given temperature according to the gas-liquid chromatographic theory. Gas-liquid interfacial adsorption was detected for a few solutes and it has been considered for the calculations of partition coefficient. Reliable solute's infinite dilution activity coefficients can be obtained when retention data are determined by a unique partitioning mechanism. The partial molar excess enthalpies at infinite dilution have been estimated from the dependence of experimental values of solute activity coefficients with the column temperature. A thorough discussion of the uncertainties of the experimental measurements and the main advantages of the use of capillary columns to acquire the aforementioned relevant thermodynamic information was performed. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Microcontroller Based SPWM Single-Phase Inverter For Wind Power Application

    Directory of Open Access Journals (Sweden)

    Khin Ohmar Lin

    2017-04-01

    Full Text Available In this paper microcontroller based sinusoidal pulse width modulation SPWM single-phase inverter is emphasized to constant frequency conversion scheme for wind power application. The wind-power generator output voltage and frequency are fluctuated due to the variation of wind velocity. Therefore the AC output voltage of wind-generator is converted into DC voltage by using rectifier circuit and this DC voltage is converted back to AC voltage by using inverter circuit. SPWM technique is used in inverter to get nearly sine wave and reduce harmonic content. The rating of inverter is 500W single-phase 220V 50 Hz. The required SPWM timing pulses for the inverter are generated from the PIC16F877A microcontroller. Circuit simulation was done by using Proteus 7 Professional and MATLABR 2008 software. The software for microcontroller is implemented by using MPASM assembler.

  5. An Open-Loop Grid Synchronization Approach for Single-Phase Applications

    DEFF Research Database (Denmark)

    Golestan, Saeed; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

    2018-01-01

    in the presence of frequency drifts. This is particularly true in single-phase applications, where the lack of multiple independent input signals makes the implementation of the synchronization technique difficult. The aim of this paper is to develop an effective OLS technique for single-phase power and energy...... applications. The proposed OLS method benefits from a straightforward implementation, a fast dynamic response (a response time less than two cycles of the nominal frequency), and a complete immunity against the DC component in the grid voltage. In addition, the designed OLS method totally blocks (significantly...... attenuates) all harmonics up to the aliasing point under a nominal (off-nominal) frequency. The effectiveness of the designed OLS technique is verified using comparative experimental results....

  6. Single-Phase Hybrid Switched Reluctance Motor for Low-Power Low-Cost Applications

    DEFF Research Database (Denmark)

    Lu, Kaiyuan; Rasmussen, Peter Omand; Jakobsen, Uffe

    2011-01-01

    This paper presents a new single-phase, Hybrid Switched Reluctance (HSR) motor for low-cost, low-power, pump or fan drive systems. Its single-phase configuration allows use of a simple converter to reduce the system cost. Cheap ferrite magnets are used and arranged in a special flux concentration...... manner to increase effectively the torque density and efficiency of this machine. The efficiency of this machine is comparable to the efficiency of a traditional permanent magnet machine in the similar power range. The cogging torque, due to the existence of the permanent magnetic field, is beneficially...... used to reduce the torque ripple and enable self-starting of the machine. The starting torque of this machine is significantly improved by a slight extension of the stator pole-arc. A prototype machine and a complete drive system has been manufactured and tested. Results are given in this paper....

  7. Evaluation of 600V Superjunction Devices in Single Phase PFC Applications under CCM Operation

    DEFF Research Database (Denmark)

    Hernandez Botella, Juan Carlos; Petersen, Lars Press; Andersen, Michael A. E.

    2014-01-01

    This paper pr esents a power density/efficiency evaluation in single phase power factor correction (PFC) applications operating in continuous conduction mode (CCM). The comparison is based on semiconductor dynamic characterization and a mathematical model for prediction of the conducted electroma......This paper pr esents a power density/efficiency evaluation in single phase power factor correction (PFC) applications operating in continuous conduction mode (CCM). The comparison is based on semiconductor dynamic characterization and a mathematical model for prediction of the conducted...... electromagnetic interference (EMI). The dynamic characterization is based on a low inductive double pulse tester (DPT). The measured switching energy is used in order to evaluate the devices performance in a conventional PFC. This data is used together with the mathematical model for prediction of the conducted...... electromagnetic interference. The method allows comparing different devices and evaluating the performance as a function of the PFC power density and efficiency....

  8. Power decoupling with autonomous reference generation for single-phase differential inverters

    DEFF Research Database (Denmark)

    Yao, Wenli; Zhang, Xiaobin; Wang, Xiongfei

    2015-01-01

    The second-harmonic power ripple in single-phase inverter may introduce the issue of low reliability and low power density. In order to replace the bulky dc-link capacitor, an alternative approach is to use active power decoupling so that the ripple power can be diverted into other energy storages...... are used for realizing an improved power decoupling control, capacitor voltage and inductor current regulation. By substituting the corresponding parameter into unified model, the proposed control loop can be applied to different inverter types (Buck, Buck-Boost and Boost). Finally, detailed laboratory....... However, the performance of existing active power decoupling methods depends heavily on certain control references, which unfortunately are parameter dependent. In this paper an autonomous reference generation technique is proposed for single phase differential inverter without relying on the system...

  9. DQ reference frame modeling and control of single-phase active power decoupling circuits

    DEFF Research Database (Denmark)

    Tang, Yi; Qin, Zian; Blaabjerg, Frede

    2015-01-01

    Power decoupling circuits can compensate the inherent double line frequency ripple power in single-phase systems and greatly facilitate their dc-link capacitor design. Example applications of power decoupling circuit include photovoltaic, light-emitting diode, fuel cell, and motor drive systems....... This paper presents the dq synchronous reference frame modeling of single-phase power decoupling circuits and a complete model describing the dynamics of dc-link ripple voltage is presented. The proposed model is universal and valid for both inductive and capacitive decoupling circuits, and the input...... of decoupling circuits can be either dependent or independent of its front-end converters. Based on this model, a dq synchronous reference frame controller is designed which allows the decoupling circuit to operate in two different modes because of the circuit symmetry. Simulation and experimental results...

  10. Ion beam induced single phase nanocrystalline TiO2 formation

    Science.gov (United States)

    Rukade, Deepti A.; Tribedi, L. C.; Bhattacharyya, Varsha

    2014-06-01

    Single phase TiO2 nanostructures are fabricated by oxygen ion implantation (60 keV) at fluence ranging from 1×1016 ions/cm2 to 1×1017 ions/cm2 in titanium thin films deposited on fused silica substrate and subsequent thermal annealing in argon atmosphere. GAXRD and Raman spectroscopy study reveals formation of single rutile phases of TiO2. Particle size is found to vary from 29 nm to 35 nm, establishing nanostructure formation. Nanostructure formation is also confirmed by the quantum confinement effect manifested by the blueshift of the UV-vis absorption spectra. Photoluminescence spectra show peaks corresponding to TiO2 rutile phase and reveal the presence of oxygen defects due to implantation. The controlled synthesis of single phase nanostructure is attributed to ion induced defects and post-implantation annealing. It is observed that the size of the nanostructures formed is strongly dependent on the ion fluence.

  11. A New Power Calculation Method for Single-Phase Grid-Connected Systems

    DEFF Research Database (Denmark)

    Yang, Yongheng; Blaabjerg, Frede

    2013-01-01

    A new method to calculate average active power and reactive power for single-phase systems is proposed in this paper. It can be used in different applications where the output active power and reactive power need to be calculated accurately and fast. For example, a grid-connected photovoltaic...... system in low voltage ride through operation mode requires a power feedback for the power control loop. Commonly, a Discrete Fourier Transform (DFT) based power calculation method can be adopted in such systems. However, the DFT method introduces at least a one-cycle time delay. The new power calculation...... method, which is based on the adaptive filtering technique, can achieve a faster response. The performance of the proposed method is verified by experiments and demonstrated in a 1 kW single-phase grid-connected system operating under different conditions.Experimental results show the effectiveness...

  12. An efficiency improved single-phase PFC converter for electric vehicle charger applications

    DEFF Research Database (Denmark)

    Zhu, Dexuan; Tang, Yi; Jin, Chi

    2013-01-01

    This paper presents an efficiency improved single-phase power factor correction (PFC) converter with its target application to plug-in hybrid electric vehicle (PHEV) charging systems. The proposed PFC converter features sinusoidal input current, three-level output characteristic, and wide range...... of output DC voltage. Moreover, the involved DC/DC buck conversion stage may only need to convert partial input power rather than full scale of input power, and therefore the system overall efficiency can be much improved. Through proper control of the buck converter, it is also possible to mitigate...... the double-line frequency ripple power that is inherent in a single-phase AC/DC system. Both simulation and experimental results are presented to show the effectiveness of this converter....

  13. Benchmarking of Grid Fault Modes in Single-Phase Grid-Connected Photovoltaic Systems

    DEFF Research Database (Denmark)

    Yang, Yongheng; Blaabjerg, Frede; Zou, Zhixiang

    2013-01-01

    Pushed by the booming installations of singlephase photovoltaic (PV) systems, the grid demands regarding the integration of PV systems are expected to be modified. Hence, the future PV systems should become more active with functionalities of Low Voltage Ride-Through (LVRT) and grid support...... capability. The control methods, together with grid synchronization techniques, are responsible for the generation of appropriate reference signals in order to handle ride-through grid faults. Thus, it is necessary to evaluate the behaviors of grid synchronization methods and control possibilities in single...... phase systems under grid faults. The intent of this paper is to present a benchmarking of grid fault modes that might come in future single-phase PV systems. In order to map future challenges, the relevant synchronization and control strategies are discussed. Some faulty modes are studied experimentally...

  14. 100-nm thick single-phase wurtzite BAlN films with boron contents over 10%

    KAUST Repository

    Li, Xiaohang

    2017-01-11

    Growing thicker BAlN films while maintaining single-phase wurtzite structure and boron content over 10% has been challenging. In this study, we report on the growth of 100 nm-thick single-phase wurtzite BAlN films with boron contents up to 14.4% by MOCVD. Flow-modulated epitaxy was employed to increase diffusion length of group-III atoms and reduce parasitic reactions between the metalorganics and NH3. A large growth efficiency of ∼2000 μm mol−1 was achieved as a result. Small B/III ratios up to 17% in conjunction with high temperatures up to 1010 °C were utilized to prevent formation of the cubic phase and maintain wurtzite structure.

  15. Comparison of available analytical methods to measure trans-octadecenoic acid isomeric profile and content by gas-liquid chromatography in milk fat.

    Science.gov (United States)

    Destaillats, Frédéric; Golay, Pierre-Alain; Joffre, Florent; de Wispelaere, Maureen; Hug, Bernadette; Giuffrida, Francesca; Fauconnot, Laetitia; Dionisi, Fabiola

    2007-03-23

    Accurate quantification of trans-fatty acids (TFAs) could be achieved by infrared spectroscopy or by gas-liquid chromatography (GLC). Accurate quantification by GLC should be achieved using specific highly polar capillary columns such as 100 m CP-Sil 88 or equivalent. A pre-fractionation of cis and trans-fatty acids could be performed by silver-ion thin-layer chromatography (Ag-TLC), silver-ion solid-phase extraction (Ag-SPE), or by high-performance liquid-chromatography (HPLC). A pre-fractionation step allows accurate determination of the isomeric profile but it is not essential to achieve quantification of total trans-18:1 isomers nor to determine the level of vaccenic (trans-11 18:1) acid in dairy fat. TFA content could also be calculated in milk fat based on the TAG profile determined by GLC. In this paper, different GLC methods suitable to measure the total of trans-18:1 isomers, vaccenic acid and trans-18:1 acid isomeric distribution in milk fat were compared. Pre-separation of cis- and trans-18:1 isomers by Ag-TLC followed by GLC analysis under optimal conditions was selected as the reference method. Results obtained using alternative methods including pre-separation by HPLC followed by GLC analysis, direct quantification by GLC or calculation from the triacylglycerol (TAG) profile were compared to data acquired using the reference method. Results showed that accurate quantification of total trans-18:1 isomers and vaccenic acid could be achieved by direct quantification by GLC under optimal chromatographic conditions. This method represents a very good alternative to Ag-TLC followed by GLC analysis. On the other hand, we showed that pre-fractionation of fatty acid methyl esters (FAMEs) by HPLC represents a good alternative to Ag-TLC, even if some minor isomers are not selectively purified using this procedure.

  16. CFD simulation of gas-liquid floating particles mixing in an agitated vessel

    Directory of Open Access Journals (Sweden)

    Li Liangchao

    2017-01-01

    Full Text Available Gas dispersion and floating particles suspension in an agitated vessel were studied numerically by using computational fluid dynamics (CFD. The Eulerian multi-fluid model along with standard k-ε turbulence model was used in the simulation. A multiple reference frame (MRF approach was used to solve the impeller rotation. The velocity field, gas and floating particles holdup distributions in the vessel were first obtained, and then, the effects of operating conditions on gas dispersion and solid suspension were investigated. The simulation results show that velocity field of solid phase and gas phase are quite different in the agitated vessel. Floating particles are easy to accumulate in the center of the surface region and the increasing of superficial gas velocity is in favor of floating particles off-surface suspension. With increasing solids loading, the gas dispersion becomes worse, while relative solid holdup distribution changes little. The limitations of the present modeling are discussed and further research in the future is proposed.

  17. Simulation of the phenomenon of single-phase and two-phase natural circulation

    International Nuclear Information System (INIS)

    Castrillo, Lazara Silveira

    1998-02-01

    Natural convection phenomenon is often used to remove the residual heat from the surfaces of bodies where the heat is generated e.g. during accidents or transients of nuclear power plants. Experimental study of natural circulation can be done in small scale experimental circuits and the results can be extrapolated for larger operational facilities. The numerical analysis of transients can be carried out by using large computational codes that simulate the thermohydraulic behavior in such facilities. The computational code RELAP5/MOD2, (Reactor Excursion and Leak Analysis Program) was developed by U.S. Nuclear Regulatory Commissions's. Division of Reactor Safety Research with the objective of analysis of transients and postulated accidents in the light water reactor (LWR) systems, including small and large ruptures with loss of coolant accidents (LOCA's). The results obtained by the simulation of single-phase and two-phase natural circulation, using the RELAP5/MOD2, are presented in this work. The study was carried out using the experimental circuit built at the 'Departamento de Engenharia Quimica da Escola Politecnica da Universidade de Sao Paulo'. In the circuit, two experiments were carried out with different conditions of power and mass flow, obtaining a single-phase regime with a level of power of 4706 W and flow of 5.10 -5 m 3 /s (3 l/min) and a two-phase regime with a level of power of 6536 W and secondary flow 2,33.10 -5 m 3 /s (1,4 l/min). The study allowed tio evaluate the capacity of the code for representing such phenomena as well as comparing the transients obtained theoretically with the experimental results. The comparative analysis shows that the code represents fairly well the single-phase transient, but the results for two-phase transients, starting from the nodalization and calibration used for the case single-phase transient, did not reproduce faithfully some experimental results. (author)

  18. Strain-hardening in nano-structured single phase steels: mechanisms and control.

    Science.gov (United States)

    Bouaziz, O; Barbier, D

    2012-11-01

    The detrimental effect of grain size refinement on the strain hardening is highlighted in single phase steels. A physical based approach for understanding the underlying mechanisms is presented. In order to overcome this limitation a promising metallurgical route exploiting the thermal stability of mechanically induced twins in austenitic steels has been successfully applied to a stainless grade confirming the opportunity to get nano-structured alloys exhibiting high yield stress with high strain-hardening.

  19. A New Synchronous Reference Frame-Based Method for Single-Phase Shunt Active Power Filters

    DEFF Research Database (Denmark)

    Monfared, Mohammad; Golestan, Saeed; Guerrero, Josep M.

    2013-01-01

    This paper deals with the design of a novel method in the synchronous reference frame (SRF) to extract the reference compensating current for single-phase shunt active power filters (APFs). Unlike previous works in the SRF, the proposed method has an innovative feature that it does not need the f...... the excellent performance of the suggested approach. Theoretical evaluations are confirmed by experimental results....

  20. Decoupling of Fluctuating Power in Single-Phase Systems Through a Symmetrical Half-Bridge Circuit

    DEFF Research Database (Denmark)

    Tang, Yi; Blaabjerg, Frede; Loh, Poh Chiang

    2015-01-01

    Single-phase ac/dc or dc/ac systems are inherently subject to the harmonic disturbance that is caused by the well-known double-line frequency ripple power. This issue can be eased through the installation of bulky electrolytic capacitors in the dc link. Unfortunately, such passive filtering...... power decoupling method, and both the input current and output voltage of the converter can be well regulated even when very small dc-link capacitors are employed....

  1. Single-phase DECT with VNCT compared with three-phase CTU in patients with haematuria

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jung Jae; Park, Byung Kwan; Kim, Chan Kyo [Sungkyunkwan University School of Medicine, Department of Radiology, Samsung Medical Center, Seoul (Korea, Republic of)

    2016-10-15

    To retrospectively evaluate the diagnostic performance of single-phase dual-energy CT (DECT) with virtual non-contrast CT (VNCT) compared with three-phase CT urography (CTU) in patients with haematuria. A total of 296 patients underwent three-phase CTU (NCT at 120 kVp; nephrographic phase and excretory phase DECTs at 140 kVp and 80 kVp) owing to haematuria. Diagnostic performances of CT scans were compared for detecting urothelial tumours and urinary stones. Dose-length product (DLP) was compared in relation to single-phase DECT and three-phase CTU Dose-length product (DLP) was compared in relation to single-phase DECT and three-phase CTU. Sensitivity and specificity for tumour were 95 % (19/20) and 98.9 % (273/276) on CTU, 95 % (19/20) and 98.2 % (271/276) on nephrographic phase DECT, and 90 % (18/20) and 98.2 % (271/276) on excretory phase DECT (P > 0.1). Of the 148 stones detected on NCT, 108 (73 %) and 100 (67.6 %) were detected on nephrographic phase and excretory phase VNCTs, respectively. The mean size of stones undetected on nephrographic and excretory VNCTs was measured as 1.5 ± 0.5 mm and 1.6 ± 0.6 mm, respectively. The mean DLPs of three-phase CTU, nephrographic phase DECT and excretory phase DECT were 1076 ± 248 mGy . cm, 410 ± 98 mGy . cm, and 360 ± 87 mGy . cm, respectively (P < 0.001). Single-phase DECT has a potential to replace three-phase CTU for detecting tumours with a lower radiation dose. (orig.)

  2. Modeling and analysis of variable speed single phase induction motors with iron loss

    International Nuclear Information System (INIS)

    Vaez-Zadeh, S.; Zahedi, B.

    2009-01-01

    Despite their usual low power ratings of single phase induction motors, they consume a considerable part of total motors energy consumption due to their large and ever-increasing quantity. The recent rising of oil prices and environmental crises has fortified the idea of energy saving practices in all applications; particularly in single phase induction motors due to their typical low efficiency. An essential requirement for this practice is the modeling and analysis of machine electrical losses under variable frequency operation. In this paper an improved steady state model of single phase induction motors is derived to investigate major motor characteristics like torque-speed, input power, output power, etc. A special emphasis is placed on accurately representing core losses at variable frequency. The winding currents phase difference is reintroduced as a fundamental motor variable to determine motor performances including losses and efficiency. An advanced computerized motor test setup is designed and built for on-line measurement of motor characteristics at different supply and operating conditions. The extensive experimental results, in good agreement with the simulation results based on the mentioned analysis, confirm the validity of the proposed model.

  3. SINGLE-PHASE AND TWO-PHASE SECONDARY COOLANTS: SIMULATION AND EVALUATION OF THEIR THERMOPHYSICAL PROPERTIES

    Directory of Open Access Journals (Sweden)

    Pedro Samuel Gomes Medeiros

    2011-09-01

    Full Text Available This paper makes a comparative analysis of the thermophysical properties of ice slurry with conventional single-phase secondary fluids used in thermal storage cooling systems. The ice slurry is a two-phase fluid consisting of water, antifreeze and ice crystals. It is a new technology that has shown great energy potential. In addition to transporting energy as a heat transfer fluid, it has thermal storage properties due to the presence of ice, storing coolness by latent heat of fusion. The single-phase fluids analyzed are water-NaCl and water-propylene glycol solutions, which also operate as carrier fluids in ice slurry. The presence of ice changes the thermophysical properties of aqueous solutions and a number of these properties were determined: density, thermal conductivity and dynamic viscosity. Data were obtained by software simulation. The results show that the presence of 10% by weight of ice provides a significant increase in thermal conductivity and dynamic viscosity, without causing changes in density. The rheological behavior of ice slurries, associated with its high viscosity, requires higher pumping power; however, this was not significant because higher thermal conductivity allows a lower mass flow rate without the use of larger pumps. Thus, the ice slurry ensures its high potential as a secondary fluid in thermal storage cooling systems, proving to be more efficient than single-phase secondary fluids.

  4. A DAB Converter with Common-Point-Connected Winding Transformers Suitable for a Single-Phase 5-Level SST System

    Directory of Open Access Journals (Sweden)

    Hyeok-Jin Yun

    2018-04-01

    Full Text Available One of the main disadvantages of the multi-level solid-state transformer (SST system is the voltage imbalance on the output of the rectifier modules. This voltage imbalance can be caused by parameter mismatch of the active and passive components, different loads, and the floating structure of the high voltage DC-links. Some studies have been done to solve this voltage imbalance problem. A common way to avoid this imbalance is to balance the voltage of DC-links at the AC/DC conversion stage and balance the power between the modules at the DC/DC conversion stage. Most of these methods require a complex balancing controller or additional circuits. This paper proposes a novel dual active bridge (DAB converter specialized in power balancing in a single-phase 5-level SST system. The proposed DAB converter does not require any additional balancing controllers or techniques for power balancing. The performance of the proposed DAB converter was verified by simulation and experiments using a 3 kW 5-level SST prototype system.

  5. Multiphase Transport in Porous Media: Gas-Liquid Separation Using Capillary Pressure Gradients International Space Station (ISS) Flight Experiment Development

    Science.gov (United States)

    Wheeler, Richard R., Jr.; Holtsnider, John T.; Dahl, Roger W.; Deeks, Dalton; Javanovic, Goran N.; Parker, James M.; Ehlert, Jim

    2013-01-01

    Advances in the understanding of multiphase flow characteristics under variable gravity conditions will ultimately lead to improved and as of yet unknown process designs for advanced space missions. Such novel processes will be of paramount importance to the success of future manned space exploration as we venture into our solar system and beyond. In addition, because of the ubiquitous nature and vital importance of biological and environmental processes involving airwater mixtures, knowledge gained about fundamental interactions and the governing properties of these mixtures will clearly benefit the quality of life here on our home planet. The techniques addressed in the current research involving multiphase transport in porous media and gas-liquid phase separation using capillary pressure gradients are also a logical candidate for a future International Space Station (ISS) flight experiment. Importantly, the novel and potentially very accurate Lattice-Boltzmann (LB) modeling of multiphase transport in porous media developed in this work offers significantly improved predictions of real world fluid physics phenomena, thereby promoting advanced process designs for both space and terrestrial applications.This 3-year research effort has culminated in the design and testing of a zero-g demonstration prototype. Both the hydrophilic (glass) and hydrophobic (Teflon) media Capillary Pressure Gradient (CPG) cartridges prepared during the second years work were evaluated. Results obtained from ground testing at 1-g were compared to those obtained at reduced gravities spanning Martian (13-g), Lunar (16-g) and zero-g. These comparisons clearly demonstrate the relative strength of the CPG phenomena and the efficacy of its application to meet NASAs unique gas-liquid separation (GLS) requirements in non-terrestrial environments.LB modeling software, developed concurrently with the zero-g test effort, was shown to accurately reproduce observed CPG driven gas-liquid separation

  6. Microporous hollow fibre membrane modules as gas-liquid contactors. Part 1: Physical mass transfer processes. A specific application: mass transfer in highly viscous liquids

    OpenAIRE

    Kreulen, H.; Kreulen, H.; Versteeg, Geert; Smolders, C.A.; Smolders, C.A.; van Swaaij, Willibrordus Petrus Maria

    1993-01-01

    Gas-liquid mass transfer has been studied in a membrane module with non-wetted microporous fibres in the laminar flow regime. This new type of gas/liquid contactor can be operated stabily over a large range of gas and liquid flows because gas and liquid phase do not influence each other directly. Therefore foam is not formed in the module, gas bubbles are not entrained in the liquid flowing out of the reactor and the separation of both phases can be achieved very easily. These phenomena often...

  7. Hydrodynamic characteristics of a two-phase gas-liquid flow upward through a fixed bed of spherical particles

    Directory of Open Access Journals (Sweden)

    VELIZAR D. STANKOVIC

    2001-01-01

    Full Text Available The influence of an electrochemically generated gas phase on the hydrodynamic characteristics of a three-phase system has been examined. The two-phase fluid, (gas-liquid, in which the liquid phase is the continuous one, flows through a packed bed with glass spheres. The influence of the liquid velocity was examined, as well as the gas velocity and particle diameter on the pressure drop through the fixed bed. It was found that with increasing liquid velocity (wl = 0.0162–0.03 m/s, the relative pressure drop decreases through the fixed bed. With increasing current density, the pressure drop increases, since greater gas quantities stay behind in the fixed bed. Besides, it was found that with decreasing diameter of the glass particles, the relative pressure drop also decreases. The relationship betweeen the experimentally obtained friction factor and the Reynolds number was established.

  8. Effect of turbulent gas-liquid contact in a static mixer on Cryptosporidium parvum oocyst inactivation by ozone.

    Science.gov (United States)

    Craik, Stephen A; Smith, Daniel W; Chandrakanth, Mysore; Belosevic, Miodrag

    2003-09-01

    Static mixers may be used to dissolve gaseous ozone in water treatment facilities in order to provide protection against the waterborne parasite Cryptosporidium parvum. The objective of this study was to determine the effect of a brief exposure to turbulent gas-liquid mixing conditions in a static mixer on inactivation of C. parvum oocysts by ozone. Inactivation measured in an ozone contacting apparatus that employed a static mixer for ozone dissolution was compared to predictions based on a previously published kinetic model of C. parvum inactivation by dissolved ozone in gently stirred batch reactors. Although initial contact in the static mixer had no immediate effect on the oocysts, a 20% increase in the rate of inactivation during subsequent contact with dissolved ozone was observed. Increasing the degree of turbulence within the static mixer did not yield additional inactivation. Use of static mixers for dissolution of ozone in drinking water treatment systems may provide limited enhancement of C. parvum inactivation by dissolved ozone.

  9. Finite element method for transient flow of homogeneous gas-liquid mixtures in rigid and quasi-rigid pipelines

    International Nuclear Information System (INIS)

    Haj Kacem, Yassine; Hadj-Taieb, Ezzedine

    2017-01-01

    A numerical solution based on the finite element method is presented to describe wave propagations in the transient flow of homogeneous gas-liquid mixtures in rigid and quasi-rigid pipes. The rigid model is deduced by neglecting the liquid compressibility and the pipe wall elasticity against the gas compressibility. But, these two parameters are taken into consideration in the quasi-rigid model. The effect of fluid compressibility on the pressure waves of transient flow is then analyzed and confronted to the pipe wall elasticity. To validate the reliability of the model presented herein, the numerical results are compared with those obtained by the finite difference method and experiment. The results show that the pressure wave propagation is significantly influenced by gas-fluid mass ratio and pipe wall elasticity. (authors)

  10. A Combined Algorithm for Optimization: Application for Optimization of the Transition Gas-Liquid in Stirred Tank Bioreactors

    Directory of Open Access Journals (Sweden)

    Mitko Petrov

    2005-12-01

    Full Text Available A combined algorithm for static optimization is developed. The algorithm includes a method for random search of optimal an initial point and a method based on fuzzy sets theory, combined in order to be found for the best solution of the optimization problem. The application of the combined algorithm eliminates the main disadvantage of the used fuzzy optimization method, namely decreases the number of discrete values of control variables. In this way, the algorithm allows problems with larger scale to be solved. The combined algorithm is used for optimization of gas-liquid transition in dependence on some constructive and regime parameters of a laboratory scale stirred tank bioreactor. After the application of developed optimization algorithm significant increase of mass-transfer effectiveness, aeration and mixing processes in the bioreactor are observed.

  11. Void fraction and interfacial velocity in gas-liquid upward two-phase flow across tube bundles

    International Nuclear Information System (INIS)

    Ueno, T.; Tomomatsu, K.; Takamatsu, H.; Nishikawa, H.

    1997-01-01

    Tube failures due to flow-induced vibration are a major problem in heat exchangers and many studies on the problem of such vibration have been carried out so far. Most studies however, have not focused on two-phase flow behavior in tube bundles, but have concentrated mainly on tube vibration behavior like fluid damping, fluid elastic instability and so on. Such studies are not satisfactory for understanding the design of heat exchangers. Tube vibration behavior is very complicated, especially in the case of gas-liquid two-phase flow, so it is necessary to investigate two-phase flow behavior as well as vibration behavior before designing heat exchangers. This paper outlines the main parameters that characterize two-phase behavior, such as void fraction and interfacial velocity. The two-phase flow analyzed here is gas-liquid upward flow across a horizontal tube bundle. The fluids tested were HCFC-123 and steam-water. HCFC-123 stands for Hydrochlorofluorocarbon. Its chemical formula is CHCl 2 CF 3 , which has liquid and gas densities of 1335 and 23.9 kg/m 3 at a pressure of 0.40 MPa and 1252 and 45.7 kg/m 3 at a pressure of 0.76 MPa. The same model tube bundle was used in the two tests covered in this paper, to examine the similarity law of two-phase flow behavior in tube bundles using HCFC-123 and steam-water two-phase flow. We also show numerical simulation results for the two fluid models in this paper. We do not deal with vibration behavior and the relationship between vibration behavior and two-phase flow behavior. (author)

  12. Pore-scale analysis of the minimum liquid film thickness around elongated bubbles in confined gas-liquid flows

    Science.gov (United States)

    Magnini, M.; Beisel, A. M.; Ferrari, A.; Thome, J. R.

    2017-11-01

    The fluid mechanics of elongated bubbles in confined gas-liquid flows in micro-geometries is important in pore-scale flow processes for enhanced oil recovery and mobilization of colloids in unsaturated soil. The efficiency of such processes is traditionally related to the thickness of the liquid film trapped between the elongated bubble and the pore's wall, which is assumed constant. However, the surface of long bubbles presents undulations in the vicinity of the rear meniscus, which may significantly decrease the local thickness of the liquid film, thus impacting the process of interest. This study presents a systematic analysis of these undulations and the minimum film thickness induced in the range Ca = 0.001- 0.5 and Re = 0.1- 2000 . Pore-scale Computational Fluid Dynamics (CFD) simulations are performed with a self-improved version of the opensource solver ESI OpenFOAM which is based on a Volume of Fluid method to track the gas-liquid interface. A lubrication model based on the extension of the classical axisymmetric Bretherton theory is utilized to better understand the CFD results. The profiles of the rear meniscus of the bubble obtained with the lubrication model agree fairly well with those extracted from the CFD simulations. This study shows that the Weber number of the flow, We = Ca Re , is the parameter that best describes the dynamics of the interfacial waves. When We 0.1, a larger number of wave crests becomes evident on the surface of the rear meniscus of the bubble. The liquid film thickness at the crests of the undulations thins considerably as the Reynolds number is increased, down to less than 60% of the value measured in the flat film region. This may significantly influence important environmental processes, such as the detachment and mobilization of micron-sized pollutants and pathogenic micro-organisms adhering at the pore's wall in unsaturated soil.

  13. A New Void Fraction Measurement Method for Gas-Liquid Two-Phase Flow in Small Channels

    Directory of Open Access Journals (Sweden)

    Huajun Li

    2016-01-01

    Full Text Available Based on a laser diode, a 12 × 6 photodiode array sensor, and machine learning techniques, a new void fraction measurement method for gas-liquid two-phase flow in small channels is proposed. To overcome the influence of flow pattern on the void fraction measurement, the flow pattern of the two-phase flow is firstly identified by Fisher Discriminant Analysis (FDA. Then, according to the identification result, a relevant void fraction measurement model which is developed by Support Vector Machine (SVM is selected to implement the void fraction measurement. A void fraction measurement system for the two-phase flow is developed and experiments are carried out in four different small channels. Four typical flow patterns (including bubble flow, slug flow, stratified flow and annular flow are investigated. The experimental results show that the development of the measurement system is successful. The proposed void fraction measurement method is effective and the void fraction measurement accuracy is satisfactory. Compared with the conventional laser measurement systems using standard laser sources, the developed measurement system has the advantages of low cost and simple structure. Compared with the conventional void fraction measurement methods, the proposed method overcomes the influence of flow pattern on the void fraction measurement. This work also provides a good example of using low-cost laser diode as a competent replacement of the expensive standard laser source and hence implementing the parameter measurement of gas-liquid two-phase flow. The research results can be a useful reference for other researchers’ works.

  14. Effect of duration of the pause single-phase auto-reclosing on electro-power transmission capacitance

    Directory of Open Access Journals (Sweden)

    Krasil'nikova Tatyana

    2017-01-01

    Full Text Available This paper discusses the problem associated with accidents in the aerial line (AL ultra-high voltage (UHV due to its big length. In lines with a voltage of 500-1150 kV the overwhelming proportion of trips (98% is caused by single-phase short circuit (SPSC. A substantial portion (70% single-phase short circuits is erratic arc accidents which can be successfully eliminated in a high-speed auto-reclosing (HSAR or single-phase auto-reclosing (SPAR. Success single-phase auto-reclosing (SPAR at liquidation by single-phase short circuit (SPSC, on the one hand, is determined by the characteristics of the secondary arc current, and on the other hand the effectiveness of ways to reduce secondary arc current and recovery voltage development. The minimum dead time, at a HSAR it is usually taken as 0.5 s., at single-phase autoreclosing (SPAR it depends on the current value of the arc support is in the range of 0.5-3.0 s. The article shows high efficiency of use single-phase auto reclosing (SPAR at liquidation SPSC in a single-chain AL voltage of 500 kV, the dependence of the bandwidth of transmission in maintaining the dynamic stability from the length of the pause SPAR.

  15. Apparent dynamic contact angle of an advancing gas--liquid meniscus

    International Nuclear Information System (INIS)

    Kalliadasis, S.; Chang, H.

    1994-01-01

    The steady motion of an advancing meniscus in a gas-filled capillary tube involves a delicate balance of capillary, viscous, and intermolecular forces. The limit of small capillary numbers Ca (dimensionless speeds) is analyzed here with a matched asymptotic analysis that links the outer capillary region to the precursor film in front of the meniscus through a lubricating film. The meniscus shape in the outer region is constructed and the apparent dynamic contact angle Θ that the meniscus forms with the solid surface is derived as a function of the capillary number, the capillary radius, and the Hamaker's constant for intermolecular forces, under conditions of weak gas--solid interaction, which lead to fast spreading of the precursor film and weak intermolecular forces relative to viscous forces within the lubricating film. The dependence on intermolecular forces is very weak and the contact angle expression has a tight upper bound tan Θ=7.48 Ca 1/3 for thick films, which is independent of the Hamaker constant. This upper bound is in very good agreement with existing experimental data for wetting fluids in any capillary and for partially wetting fluids in a prewetted capillary. Significant correction to the Ca 1/3 dependence occurs only at very low Ca, where the intermolecular forces become more important and tan Θ diverges slightly from the above asymptotic behavior toward lower values

  16. High Performance Harmonic Isolation By Means of The Single-phase Series Active Filter Employing The Waveform Reconstruction Method

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk; Hava, Ahmet M.

    2009-01-01

    This paper proposes the Waveform Reconstruction Method (WRM), which is utilized in the single-phase Series Active Filter's (SAF's) control algorithm, in order to extract the load harmonic voltage component of voltage harmonic type single-phase diode rectifier loads. Employing WRM and the line...... current sampling delay reduction method (SDRM), a single-phase SAF compensated system provides higher harmonic isolation performance and higher stability margins compared to the system using conventional synchronous reference frame based methods. The analytical, simulation, and experimental studies of a 2...

  17. Fabrication of single phase 2D homologous perovskite microplates by mechanical exfoliation

    Science.gov (United States)

    Li, Junze; Wang, Jun; Zhang, Yingjun; Wang, Haizhen; Lin, Gaoming; Xiong, Xuan; Zhou, Weihang; Luo, Hongmei; Li, Dehui

    2018-04-01

    The two-dimensional (2D) Ruddlesden-Popper type perovskites have attracted intensive interest for their great environmental stability and various potential optoelectronic applications. Fundamental understanding of the photophysical and electronic properties of the 2D perovskites with pure single phase is essential for improving the performance of the optoelectronic devices and designing devices with new architectures. Investigating the optical and electronic properties of these materials with pure single phase is required to obtain pure single phase 2D perovskites. Here, we report on an alternative approach to fabricate (C4H9NH3)2(CH3NH3) n-1Pb n I3n+1 microplates with pure single n-number perovskite phase for n  >  2 by mechanical exfoliation. Micro-photoluminescence and absorption spectroscopy studies reveal that the as-synthesized 2D perovskite plates for n  >  2 are comprised by dominant n-number phase and small inclusions of hybrid perovskite phases with different n values, which is supported by excitation power dependent photoluminescence. By mechanical exfoliation method, 2D perovskite microplates with the thickness of around 20 nm are obtained, which surprisingly have single n-number perovskite phase for n  =  2-5. In addition, we have demonstrated that the exfoliated 2D perovskite microplates can be integrated with other 2D layered materials such as boron nitride, and are able to be transferred to prefabricated electrodes for photodetections. Our studies not only provide a strategy to prepare 2D perovskites with a single n-number perovskite phase allowing us to extract the basic optical and electronic parameters of pure phase perovskites, but also demonstrate the possibility to integrate the 2D perovskites with other 2D layered materials to extend the device’s functionalities.

  18. Reliable Grid Condition Detection and Control of Single-Phase Distributed Power Generation Systems

    DEFF Research Database (Denmark)

    Ciobotaru, Mihai

    to the utility grid but also to sustain it. This thesis was divided into two main parts, namely "Grid Condition Detection" and "Control of Single-Phase DPGS". In the first part, the main focus was on reliable Phase Locked Loop (PLL) techniques for monitoring the grid voltage and on grid impedance estimation...... of the entire system. Regarding the advance control of DPGS, an active damping technique for grid-connected systems using inductor-capacitorinductor (LCL) filters was proposed in the thesis. The method is based on a notch filter, whose stopband can be automatically adjusted in relation with an estimated value...

  19. Power quality improvement of single-phase photovoltaic systems through a robust synchronization method

    DEFF Research Database (Denmark)

    Hadjidemetriou, Lenos; Kyriakides, Elias; Yang, Yongheng

    2014-01-01

    An increasing amount of single-phase photovoltaic (PV) systems on the distribution network requires more advanced synchronization methods in order to meet the grid codes with respect to power quality and fault ride through capability. The response of the synchronization technique selected...... to the harmonic voltage distortion without affecting the dynamic response of the synchronization. Therefore, the accurate response of the proposed MHDC-PLL enhances the power quality of the PV inverter systems and additionally, the proper fault ride-through operation of PV systems can be enabled by the fast...

  20. Frequency Adaptive Repetitive Control of Grid-Tied Single-Phase PV Inverters

    DEFF Research Database (Denmark)

    Zhou, Keliang; Yang, Yongheng; Blaabjerg, Frede

    2015-01-01

    . This paper thus explores a frequency adaptive repetitive control strategy for grid converters, which employs fractional delay filters in order to adapt to the change of the grid frequency. Case studies with experimental results of a single-phase grid-connected PV inverter system are provided to verify......The internal model principle based Repetitive Control (RC) offers an accurate control strategy for grid-tied power converters to feed sinusoidal current into the grid. However, in the presence of grid frequency variations, the conventional RC fails to produce high quality feeding current...... the proposed controller....

  1. Design and analysis of sensorless torque optimization for single phase induction motors

    International Nuclear Information System (INIS)

    Vaez-Zadeh, S.; Payman, A.

    2006-01-01

    Single phase induction motors are traditionally used in constant speed applications and suffer from unsymmetrical performance. A reliable speed signal can improve their performance and extend their applications as variable speed drives. In this paper, a speed estimation method for these motors is proposed based on a machine model in the stator flux reference frame. The method is examined in a sensorless torque optimization system over a wide operating range. Extensive simulation results prove the validity of the proposed method. Also, the motor performance under the torque optimization system is analyzed

  2. Indirect Control of a low power Single-Phase Active Power Filter

    Directory of Open Access Journals (Sweden)

    SILVIU EPURE

    2010-12-01

    Full Text Available This paper deals with a low power, single phase active filter used to compensate nonlinear loads. The filter uses the indirect control method and it is based on a particular connection between filter, polluting load and grid to avoid timeconsuming mathematic operations or signal processing computations and assures good rejection of harmonic currents injected by the nonlinear load into the grid. A scale model was first simulated in Simulink and then physically implemented. The paper presents simulation and experimental results, and highlight problems encountered during experiments.

  3. Pressure drop and heat transfer of lithium single-phase flow under transverse magnetic field

    International Nuclear Information System (INIS)

    Takahashi, Minoru; Aritomi, Masanori; Inoue, Akira; Matsuzaki, Mitsuo

    1996-01-01

    Pressure drop and heat transfer characteristics of a lithium single-phase flow in a rectangular channel was investigated experimentally in the presence of a magnetic field. Friction loss coefficient under non-magnetic field and skin friction coefficient under magnetic field agreed well with the Blasius formula and a simple analytical expression, respectively. Nusselt number under non-magnetic field was slightly lower than the correlation by Hartnett and Irvine. Heat transfer was enhanced by increasing magnetic field above the Hartmann number of about 200. (author)

  4. Benchmarking of small-signal dynamics of single-phase PLLs

    DEFF Research Database (Denmark)

    Zhang, Chong; Wang, Xiongfei; Blaabjerg, Frede

    2015-01-01

    Phase-looked Loop (PLL) is a critical component for the control and grid synchronization of grid-connected power converters. This paper presents a benchmarking study on the small-signal dynamics of three commonly used PLLs for single-phase converters, including enhanced PLL, second......-order generalized integrator based PLL, and the inverse-PLL. First, a unified small-signal model of those PLLs is established for comparing their dynamics. Then, a systematic design guideline for parameters tuning of the PLLs is formulated. To confirm the validity of theoretical analysis, nonlinear time...

  5. An LLCL Power Filter for Single-Phase Grid-Tied Inverter

    DEFF Research Database (Denmark)

    Wu, Weimin; He, Yuanbin; Blaabjerg, Frede

    2012-01-01

    This paper presents a new topology of higher order power filter for grid-tied voltage-source inverters, named the LLCL filter, which inserts a small inductor in the branch loop of the capacitor in the traditional LCL filter to compose a series resonant circuit at the switching frequency...... to the inverter system control. The parameter design criteria of the proposed LLCL filter is also introduced. The comparative analysis and discussions regarding the traditional LCL filter and the proposed LLCL filter have been presented and evaluated through experiment on a 1.8-kW-single-phase grid-tied inverter...

  6. A MPPT Algorithm Based PV System Connected to Single Phase Voltage Controlled Grid

    Science.gov (United States)

    Sreekanth, G.; Narender Reddy, N.; Durga Prasad, A.; Nagendrababu, V.

    2012-10-01

    Future ancillary services provided by photovoltaic (PV) systems could facilitate their penetration in power systems. In addition, low-power PV systems can be designed to improve the power quality. This paper presents a single-phase PV systemthat provides grid voltage support and compensation of harmonic distortion at the point of common coupling thanks to a repetitive controller. The power provided by the PV panels is controlled by a Maximum Power Point Tracking algorithm based on the incremental conductance method specifically modified to control the phase of the PV inverter voltage. Simulation and experimental results validate the presented solution.

  7. A control strategy for induction motors fed from single phase supply

    DEFF Research Database (Denmark)

    Søndergård, Lars Møller

    1993-01-01

    It is often required that a three-phased asynchronous motor can run at variable speed, which makes it necessary to use a three-phase inverter driven from a DC-source. Today, most inverters are driven from the network using a simple diode bridge and an electrolytic capacitor. The problem...... with the simple diode bridge and the electrolytic capacitor is that current is only drawn for short periods, which gives rise to harmonic currents in the network. For small drive systems (motor+inverter), i.e. less than 1.5 kW, a single phase network outlet is often used. The author describes a method whereby...

  8. Novel Position and Speed Estimator for PM Single Phase Brushless D.C. Motor Drives

    DEFF Research Database (Denmark)

    Lepure, Liviu I.; Andreescu, Gheorghe-Daniel; Iles, Doris

    2010-01-01

    A novel position and speed estimator for single phase permanent magnet brushless d.c. (PMBLDC) motor drives, based on flux integration and prior knowledge of ΨPM (θ) is proposed here and an adequate correction algorithm is adopted in order to increase the robustness to noise and to reduce...... the sensitivity to accuracy of flux linkage estimation. A speed and current close loop control is employed based on the Hall signal and the motor is controlled at different speeds in order to validate the proposed estimation algorithm with satisfying results. The position correction effect is analyzed...

  9. Single Phase Transformer-less Buck-Boost Inverter with Zero Leakage Current for PV Systems

    DEFF Research Database (Denmark)

    Mostaan, Ali; Abdelhakim, Ahmed; N. Soltani, Mohsen

    2017-01-01

    In this paper, a novel single-stage single-phase transformer-less buck-boost inverter is proposed, in which a reduced number of passive components is used. The proposed inverter combines the conventional buck, boost, and buck-boost converters in one converter in order to obtain a sinusoidal output...... voltage. In the proposed inverter, the input DC source and the load or grid have the same ground. Therefore, the leakage current problem in photovoltaic (PV) systems is eliminated. Furthermore, the proposed inverter supports the bi-directional power flow capability and it can inject reactive power...

  10. Single phase and two-phase flow pressure losses through restrictions, expansions and inserts

    International Nuclear Information System (INIS)

    Glenat, P.; Solignac, P.

    1984-11-01

    We give a selection of methods to predict pressure losses through retrictions, expansions and inserts. In single phase flow, we give the classical method based on the one-dimensional momentum and mass balances. In two-phase flow, we propose the method given by Harshe et al. and an empirical approach suggested by Chisholm. We notice the distinction between long and short inserts depends upon wether or not the vena contracta lies within insert. Finally, we propose three correlations to calculate void fraction through the singularities which have been considered [fr

  11. A low capacitance single-phase AC-DC converter with inherent power ripple decoupling

    OpenAIRE

    Gottardo, Davide; De Lillo, Liliana; Empringham, Lee; Costabeber, Alessando

    2016-01-01

    This paper proposes a new single-phase AC-DC conversion topology with inherent power ripple decoupling, based on the combination of a PWM H-bridge inverter, an AC side LC filter and a ZVS line commutated H-bridge. A capacitor on the AC side is used as power decoupling element. By appropriate selection of the capacitor voltage, the power ripple at twice the AC frequency can be cancelled from the DC side instantaneous power, achieving negligible DC voltage ripple using a smaller total capacitan...

  12. Single Phase Current-Source Active Rectifier for Traction: Control System Design and Practical Problems

    Directory of Open Access Journals (Sweden)

    Jan Michalik

    2006-01-01

    Full Text Available This research has been motivated by industrial demand for single phase current-source active rectifier dedicated for reconstruction of older types of dc machine locomotives. This paper presents converters control structure design and simulations. The proposed converter control is based on the mathematical model and due to possible interaction with railway signaling and required low switching frequency employs synchronous PWM. The simulation results are verified by experimental tests performed on designed laboratory prototype of power of 7kVA

  13. Dynamics Assessment of Grid-Synchronization Algorithms for Single-Phase Grid-Connected Converters

    DEFF Research Database (Denmark)

    Han, Yang; Luo, Mingyu; Guerrero, Josep M.

    2015-01-01

    and low computational burden. Meanwhile, some other techniques have been proposed to enhance system robustness and stability characteristics. In this paper, a comprehensive comparison among the OSG-based PLLs and the advanced single-phase PLLs is presented when the grid voltage undergoes disturbances......, and the performance comparison of transient response and disturbance rejection capabilities are presented. Finally, the moving average filter (MAF) is applied to enhance steady state and dynamic response of the delayed-type PLL, derivator-based PLL and the complex-coefficient filter (CCF-PLL) under grid frequency...

  14. High Quality Model Predictive Control for Single Phase Grid Connected Photovoltaic Inverters

    DEFF Research Database (Denmark)

    Zangeneh Bighash, Esmaeil; Sadeghzadeh, Seyed Mohammad; Ebrahimzadeh, Esmaeil

    2018-01-01

    Single phase grid-connected inverters with LCL filter are widely used to connect the photovoltaic systems to the utility grid. Among the presented control schemes, predictive control methods are faster and more accurate but are more complex to implement. Recently, the model-predictive control...... is low, the inverter output current has a high total harmonic distortions. In order to reduce the total harmonic distortions of the injected current, this paper presents a high-quality model-predictive control for one of the newest structure of the grid connected photovoltaic inverter, i.e., HERIC...

  15. A new type of single-phase five-level inverter

    Science.gov (United States)

    Xu, Zhi; Li, Shengnan; Qin, Risheng; Zhao, Yanhang

    2017-11-01

    At present, Neutral Point Clamped (NPC) multilevel inverter is widely applied in new energy field. However, it has some disadvantages including low utilization rate of direct current (DC) voltage source and the unbalance of neutral potential. Therefore, a new single-phase five level inverter is proposed in this paper. It has two stage structure, the former stage is equivalent to three level DC/DC converter, and the back stage uses H bridge to realize inverter. Compared with the original central clamp type inverter, the new five level inverter can improve the utilization of DC voltage, and realize the neutral point potential balance with hysteresis comparator.

  16. Dispersed single-phase-step Michelson interferometer for Doppler imaging using sunlight.

    Science.gov (United States)

    Wan, Xiaoke; Ge, Jian

    2012-09-15

    A Michelson interferometer is dispersed with a fiber array-fed spectrograph, providing 59 Doppler sensing channels using sunlight in the 510-570 nm wavelength region. The interferometer operates at a single-phase-step mode, which is particularly advantageous in multiplexing and data processing compared to the phase-stepping mode of other interferometer spectrometer instruments. Spectral templates are prepared using a standard solar spectrum and simulated interferometer modulations, such that the correlation function with a measured 1D spectrum determines the Doppler shift. Doppler imaging of a rotating cylinder is demonstrated. The average Doppler sensitivity is ~12 m/s, with some channels reaching ~5 m/s.

  17. Determination of valproic acid (DI-N-propyl acetic acid) in plasma by gas-liquid chromatography with pre-column butylation

    NARCIS (Netherlands)

    Hulshoff, A.; Roseboom, H.

    1979-01-01

    A gas-liquid chromatographic procedure for the determination of the anticonvulsant drug valproic acid in plasma or serum is described. Valproic acid is extracted from acidified plasma (or serum) into toluene containing octanoic acid as the internal standard. The toluene layer is back extracted with

  18. ARSENIC DETERMINATION IN SALINE WATERS UTILIZING A TUBULAR MEMBRANE AS A GAS-LIQUID SEPATRATOR FOR HYDRIDE GENERATION INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY

    Science.gov (United States)

    A tubular silicone rubber membrane is evaluated as a gas-liquid separator for the determination of arsenic in saline waters via HG-ICP-MS. The system was optimized in terms of NaBH and HCI concentrations. The intermediate gas and carrier gas were optimized in terms of sensitiity ...

  19. Modelling of gas-liquid, two-phase flow in porous media and channels of a PEM water electrolysis cell using the Euler-Euler framework of OpenFOAM

    DEFF Research Database (Denmark)

    Olesen, Anders Christian; Kær, Søren Knudsen

    , it also secures an even heat removal of the cell. In a previous research effort, the gas-liquid, two-phase flow was investigated in the commercial CFD framework of ANSYS CFX using the Euler-Euler model. Particularly, the treatment of gas-liquid flow in a porous medium domain subject to capillary pressure...

  20. Single-phased CaAl2Si2O8:Tm3+, Dy3+ white-light phosphors under ultraviolet excitation

    International Nuclear Information System (INIS)

    Yang, Penghui; Yu, Xue; Xu, Xuhui; Jiang, Tingming; Yu, Hongling; Zhou, Dacheng; Yang, Zhengwen; Song, Zhiguo; Qiu, Jianbei

    2013-01-01

    A novel white-light-emitting phosphor CaAl 2 Si 2 O 8 :Tm, Dy was synthesized in ambient atmosphere by solid-state reaction. The energy transfer from Tm 3+ to Dy 3+ ions via a dipole–quadrupole reaction was observed and investigated. Upon UV excitation, white light emission was achieved by integrating a blue emission band located at 455 nm and an orange one located at 574 nm attributed to Tm 3+ and Dy 3+ ions, respectively. In addition, the energy-transfer efficiency and critical distance were calculated. Results suggested that the phosphor might be promising as a single-phased white-light-emitting phosphor for UV white-light LED. - Graphical abstract: The results indicate the existence of energy transfer from Tm 3+ to Dy 3+ . By tuning the concentration of Dy 3+ , single-phased white light can be realized. - Highlights: ► Energy transfer from Tm 3+ to Dy 3+ was investigated. ► Color tunable from blue to white can be achieved. ► White light can be realized in CaAl 2 Si 2 O 8 :Tm 3+ , Dy 3+ phosphor

  1. Novel Family of Single-Phase Modified Impedance-Source Buck-Boost Multilevel Inverters with Reduced Switch Count

    DEFF Research Database (Denmark)

    Husev, Oleksandr; Strzelecki, Ryszard; Blaabjerg, Frede

    2016-01-01

    This paper describes novel single-phase solutions with increased inverter voltage levels derived by means of a nonstandard inverter configuration and impedance source networks. Operation principles based on special modulation techniques are presented. Detailed component design guidelines along wi...

  2. A Nonadaptive Window-Based PLL for Single-Phase Applications

    DEFF Research Database (Denmark)

    Golestan, Saeed; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

    2018-01-01

    The rectangular window filter, typically known as the moving average filter (MAF), is a quasi-ideal low-pass filter that has found wide application in designing advanced single-phase phase-locked loops (PLLs). Most often, the MAF is employed as an in-loop filter within the control loop of the sin......The rectangular window filter, typically known as the moving average filter (MAF), is a quasi-ideal low-pass filter that has found wide application in designing advanced single-phase phase-locked loops (PLLs). Most often, the MAF is employed as an in-loop filter within the control loop...... response is avoided. Nevertheless, the PLL implementation complexity considerably increases as MAFs are frequency-adaptive and, therefore, they require an additional frequency detector for estimating the grid frequency. To reduce the implementation complexity while maintaining a good performance, using...... a nonadaptive MAF-based QSG with some error compensators is suggested in this letter. The effectiveness of the resultant PLL, which is briefly called the nonadaptive MAF-based PLL, is verified using experimental results....

  3. A note on similarity in single-phase and porous-medium natural convection

    International Nuclear Information System (INIS)

    Lyall, H.G.

    1981-03-01

    The similarity laws for single-phase and porous-medium natural convection are developed. For single-phase flow Nu = Nu(Ra) implies that inertial effects are negligible, while Nu = Nu(Ra.Pr) implies that viscous effects are. The first correlation is adequate for Pr>10, while the second applies for Pr<0.01. For intermediate values of Pr, a more general correlation, Nu = Nu(Ra,Pr) is necessary. For a porous-medium, if inertial effects and dispersion are negligible, Nu* = Nu*(Ra*). However dispersion will only be negligible if the ratio of grain size d to the width of the region L is very small (d/L<< l). If this condition does not hold it is necessary to model d/L. If inertial effects are significant, i.e. the Reynolds number is too large for Darcy's law to apply, a group containing the effective Prandtl number, Pr*, also needs to be modelled for similarity. (author)

  4. Ion beam induced single phase nanocrystalline TiO{sub 2} formation

    Energy Technology Data Exchange (ETDEWEB)

    Rukade, Deepti A. [Department of Physics, University of Mumbai, Mumbai 400098 (India); Tribedi, L.C. [Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005 (India); Bhattacharyya, Varsha, E-mail: varsha.b1.physics@gmail.com [Department of Physics, University of Mumbai, Mumbai 400098 (India)

    2014-06-15

    Single phase TiO{sub 2} nanostructures are fabricated by oxygen ion implantation (60 keV) at fluence ranging from 1×10{sup 16} ions/cm{sup 2} to 1×10{sup 17} ions/cm{sup 2} in titanium thin films deposited on fused silica substrate and subsequent thermal annealing in argon atmosphere. GAXRD and Raman spectroscopy study reveals formation of single rutile phases of TiO{sub 2}. Particle size is found to vary from 29 nm to 35 nm, establishing nanostructure formation. Nanostructure formation is also confirmed by the quantum confinement effect manifested by the blueshift of the UV–vis absorption spectra. Photoluminescence spectra show peaks corresponding to TiO{sub 2} rutile phase and reveal the presence of oxygen defects due to implantation. The controlled synthesis of single phase nanostructure is attributed to ion induced defects and post-implantation annealing. It is observed that the size of the nanostructures formed is strongly dependent on the ion fluence.

  5. FUZZY LOGIC BASED OPTIMIZATION OF CAPACITOR VALUE FOR SINGLE PHASE OPEN WELL SUBMERSIBLE INDUCTION MOTOR

    Directory of Open Access Journals (Sweden)

    R. Subramanian

    2011-01-01

    Full Text Available Purpose – The aim of this paper is to optimize the capacitor value of a single phase open well submersible motor operating under extreme voltage conditions using fuzzy logic optimization technique and compared with no-load volt-ampere method. This is done by keeping the displacement angle (a between main winding and auxiliary winding near 90o, phase angle (f between the supply voltage and line current near 0o. The optimization work is carried out by using Fuzzy Logic Toolbox software built on the MATLAB technical computing environment with Simulink software. Findings – The optimum capacitor value obtained is used with a motor and tested for different supply voltage conditions. The vector diagrams obtained from the experimental test results indicates that the performance is improved from the existing value. Originality/value – This method will be highly useful for the practicing design engineers in selecting the optimum capacitance value for single phase induction motors to achieve the best performance for operating at extreme supply voltage conditions.

  6. MECHANICAL CHARACTERISTICS OF THREE-PHASE INDUCTION MOTORS WITH SINGLE-PHASE POWER SUPPLY

    Directory of Open Access Journals (Sweden)

    V.S. Malyar

    2016-06-01

    Full Text Available Aim. Development of a method for calculating mechanical characteristics of three-phase induction motors with single-phase power supply. Methods. The developed algorithm is based on the high-adequacy mathematical model of motor and projection method for solving the boundary problem for equations of electrical circuits balance presented in the three-phase coordinate system. As a result of asymmetry of power supply to the stator windings, in steady state, flux-linkage and current change according to the periodic law. They are determined by solving the boundary problem. Results. The developed mathematical model allows determining periodic dependence of coordinates as a function of slip and, based on them, mechanical characteristics of motors. Academic novelty. The developed method relies on a completely new mathematical approach to calculation of stationary modes of nonlinear electromagnetic circuits, which allows obtaining periodic solution in a timeless domain. Practical value. Using the developed calculation algorithm, one can select capacitance required to start an induction motor with single-phase power supply and calculate static mechanical characteristics at a given capacitance.

  7. Simplified thermal-hydraulic analysis of single phase natural circulation circuit with two heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Pinheiro, Larissa Cunha; Su, Jian, E-mail: larissa@lasme.coppe.ufrj.br, E-mail: sujian@lasme.coppe.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenhraria Nuclear; Cotta, Renato Machado, E-mail: cotta@mecanica.coppe.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (POLI/COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Dept. de Engenharia Mecanica

    2015-07-01

    Single phase natural circulation circuits composed of two convective heat exchangers and connecting tubes are important for the passive heat removal from spent fuel pools (SFP). To keep the structural integrity of the stored spent fuel assemblies, continuously cooling has to be provided in order to avoid increase at the pool temperature and subsequent uncovering of the fuel and enhanced reaction between water and metal releasing hydrogen. Decay heat can achieve considerably high amounts of energy e.g. in the AP1000, considering the emergency fuel assemblies, the maximum heat decay will reach 13 MW in the 15th day (Westinghouse Electric Company, 2010). A highly efficient alternative to do so is by means of natural circulation, which is cost-effective compared to active cooling systems and is inherently safer since presents less associated devices and no external work is required. Many researchers have investigated safety and stability aspects of natural circulation loops (NCL). However, there is a lack of literature concerning the improvement of NCL through a standard unified methodology, especially for natural circulation circuits with two heat exchangers. In the present study, a simplified thermal-hydraulic analysis of single phase natural circulation circuit with two heat exchanges is presented. Relevant dimensionless key groups were proposed to for the design and safety analysis of a scaled NCL for the cooling of spent fuel storage pool with convective cooling and heating. (author)

  8. Experimental study of single-phase pressure drops in coarse particle beds

    Energy Technology Data Exchange (ETDEWEB)

    Clavier, R., E-mail: remi.clavier@irsn.fr [IRSN Cadarache, Saint Paul-lez-Durance (France); Chikhi, N., E-mail: nourdine.chikhi@irsn.fr [IRSN Cadarache, Saint Paul-lez-Durance (France); Fichot, F., E-mail: florian.fichot@irsn.fr [IRSN Cadarache, Saint Paul-lez-Durance (France); Quintard, M., E-mail: Michel.Quintard@imft.fr [Université de Toulouse, Allée Camille Soula, F-31400 Toulouse (France); INPT, UPS, Allée Camille Soula, F-31400 Toulouse (France); IMFT (Institut de Mécanique des Fluides de Toulouse), Allée Camille Soula, F-31400 Toulouse (France); CNRS, F-31400 Toulouse (France)

    2017-02-15

    Motivated by uncertainty reduction in nuclear debris beds coolability, experiments have been conducted on the CALIDE facility in order to investigate single-phase pressure losses in representative debris beds, i.e., high sphericity (>80%) particle beds with small size dispersion (from 1 mm to 10 mm), for which no validated model exists. In this paper, experimental results are presented and analyzed in order to identify a simple correlation for single-phase flow pressure losses generated in this kind of porous media in reflooding flowing conditions, which cover Darcy to weakly turbulent regimes. In the literature, it has been observed that their behavior can be accurately described by a Darcy–Forchheimer law, involving the sum of a linear term and a quadratic non-linear deviation, with respect to the filtration velocity. Expressions for the coefficients of the linear and quadratic terms are determined by assessing the possibility to evaluate equivalent diameters, i.e., characteristic lengths allowing correct predictions of the linear and quadratic terms by the Ergun equation. It has been observed that the Sauter diameter of particles allows a very precise prediction of the linear term, while the quadratic term can be predicted using the product of the Sauter diameter and a sphericity coefficient as an equivalent diameter.

  9. Numerical investigation of refrigeration machine compressor operation considering single-phase electric motor dynamic characteristics

    Science.gov (United States)

    Baidak, Y.; Smyk, V.

    2017-08-01

    Using as the base the differential equations system which was presented in relative units for generalized electric motor of hermetic refrigeration compressor, mathematical model of the software for dynamic performance calculation of refrigeration machine compressors drive low-power asynchronous motors was developed. Performed on its ground calculations of the basic model of two-phase electric motor drive of hermetic compressor and the proposed newly developed model of the motor with single-phase stator winding, which is an alternative to the industrial motor winding, have confirmed the benefits of the motor with innovative stator winding over the base engine. Given calculations of the dynamic characteristics of compressor drive motor have permitted to determine the value of electromagnetic torque swinging for coordinating compressor and motor mechanical characteristics, and for taking them into consideration in choosing compressor elements construction materials. Developed and used in the process of investigation of refrigeration compressor drive asynchronous single-phase motor mathematical and software can be considered as an element of computer-aided design system for design of the aggregate of refrigeration compression unit refrigerating machine.

  10. Validation of CATHENA MOD-3.5/Rev0 for single-phase water hammer

    International Nuclear Information System (INIS)

    Beuthe, T.G.

    2000-01-01

    This paper describes work performed to validate the system thermalhydraulics code CATHENA MOD-3.5c/Rev0 for single-phase water hammer. Simulations were performed and are compared quantitatively against numerical tests and experimental results from the Seven Sisters Water Hammer Facility to demonstrate CATHENA can predict the creation and propagation of pressure waves when valves are opened and closed. Simulations were also performed to show CATHENA can model the behaviour of reflected and transmitted pressure waves at area changes, dead ends, tanks, boundary conditions, and orifices in simple and more complex piping systems. The CATHENA results are shown to calculate pressure and wave propagation speeds to within 0.2% and 0.5% respectively for numerical tests and within 3.3% and 5% for experimental results respectively. These results are used to help validate CATHENA for use in single-phase water hammer analysis. They also provide assurance that the fundamental parameters needed to successfully model more complex forms of water hammer are accounted for in the MOD-3.5c/Rev0 version of CATHENA, and represent the first step in the process to validate the code for use in modelling two-phase water hammer and condensation-induced water hammer. (author)

  11. The multiple gas-liquid subsea separation system: development and qualification of a novel solution for deep water field production

    Energy Technology Data Exchange (ETDEWEB)

    Abrand, Stephanie; Butin, Nicolas; Shaiek, Sadia; Hallot, Raymond [Saipem S.p.A., Milano (Italy)

    2012-07-01

    Subsea processing is more and more considered as a viable solution for the development of deep and ultra deep water fields. SAIPEM has developed a deep water gas separation and liquid boosting system, based on its proprietary 'Multi pipe' separator concept, providing a good flexibility in handling a wide range of steady and un-steady multiphase input streams using a relatively simple mechanical arrangement. The Multi pipe Concept features an array of vertical pipes for gas/liquid separation by gravity and adequate liquid hold up volumes. The operating principle is the same as standard gravity vessels. Specific inlet pipe arrangements have been worked out to enhance the separation efficiency and internals can be implemented to further optimize the performances. The limited diameter and wall thickness of the vertical pipes make the Multi pipe Concept particularly suited for deep and ultra-deep water applications and/or high pressure conditions where the selection of a single separator vessel could lead to unpractical wall thicknesses. In most cases, standard API or ASME pipes can be utilized for the Multi pipe Separator, thus enabling conventional fabrication methods, and in turn reducing cost and delivery time and opening opportunities for local content. The qualification testing program has seen two subsequent phases. The first qualification phase aimed at the confirmation of the hydrodynamic behavior of the system. In particular, the homogeneous distribution of the multiphase stream into the pipes and the stability of the liquid levels under un-steady inlet conditions were continuously assessed during the tests. This first qualification phase gave confidence in the viability of the Multi pipe and in its good hydrodynamic behavior under the different inlet conditions that can be encountered during field production. It proved that, having the same liquid level in all the separator pipes, whatever the inlet conditions are, the Multi pipe separator can be

  12. Computational-fluid-dynamics (CFD) analysis of mixing and gas-liquid mass transfer in shake flasks.

    Science.gov (United States)

    Zhang, Hu; Williams-Dalson, Wellae; Keshavarz-Moore, Eli; Shamlou, Parviz Ayazi

    2005-02-01

    CFD (computational fluid dynamics) techniques were used to predict mixing and gas-liquid mass transfer in a 250 ml shake flask operating over a range of shaking frequencies between 100 and 300 rev./min, shaking diameters between 20 and 60 mm, and fill volumes between 25 and 100 ml. Interfacial area, a, volumetric mass-transfer coeffcient, kLa, and the power input per unit volume, epsilonv, of the liquid were predicted to be 300bioreactors used in the fermentation of bacterial and fungal micro-organisms (100bioreactors. Bacterial and fungal micro-organisms require dissolved oxygen concentrations typically in the range 50-250 mmol of O2 . h(-1) . litre(-1), corresponding to volumetric mass-transfer coefficients, kLa, in the range of 250-400 h(-1). Poor mixing and dissolved-oxygen limitation in shake flasks may limit their use in process design and media optimization in fermentation. In contrast, mammalian cells have relatively low demand for oxygen and consequently require a lower specific power input, this being typically between 1 and 10 W . m(-3), allowing efficient operation in shake flasks. Experimental data presented as part of the present study showed that mammalian cell growth in shake flasks was essentially independent of the specific power input, the maximum specific cell growth rate being 0.056 h(-1). The corresponding maximum oxygen-uptake rate was 0.74 mmol of O2 . h(-1) . litre(-1) for a viable cell count of 1.3 x 10(6) cells . ml(-1). These values are comparable with reported values for laboratory and pilotscale bioreactors. This analysis suggests that growth of mammalian cells in shake flasks (and hence in laboratory bioreactors) is not limited by the gas-liquid mass-transfer rate. In mammalian cell cultures, the requirement for good mixing is driven by other considerations, including the need for good cell suspension and reduction in heterogeneity, for example, in pH, temperature, nutrient concentration, osmolality and lactate/glucose ratio.

  13. Studies of Two-Phase Gas-Liquid Flow in Microgravity. Ph.D. Thesis, Dec. 1994

    Science.gov (United States)

    Bousman, William Scott

    1995-01-01

    Two-phase gas-liquid flows are expected to occur in many future space operations. Due to a lack of buoyancy in the microgravity environment, two-phase flows are known to behave differently than those in earth gravity. Despite these concerns, little research has been conducted on microgravity two-phase flow and the current understanding is poor. This dissertation describes an experimental and modeling study of the characteristics of two-phase flows in microgravity. An experiment was operated onboard NASA aircraft capable of producing short periods of microgravity. In addition to high speed photographs of the flows, electronic measurements of void fraction, liquid film thickness, bubble and wave velocity, pressure drop and wall shear stress were made for a wide range of liquid and gas flow rates. The effects of liquid viscosity, surface tension and tube diameter on the behavior of these flows were also assessed. From the data collected, maps showing the occurrence of various flow patterns as a function of gas and liquid flow rates were constructed. Earth gravity two-phase flow models were compared to the results of the microgravity experiments and in some cases modified. Models were developed to predict the transitions on the flow pattern maps. Three flow patterns, bubble, slug and annular flow, were observed in microgravity. These patterns were found to occur in distinct regions of the gas-liquid flow rate parameter space. The effect of liquid viscosity, surface tension and tube diameter on the location of the boundaries of these regions was small. Void fraction and Weber number transition criteria both produced reasonable transition models. Void fraction and bubble velocity for bubble and slug flows were found to be well described by the Drift-Flux model used to describe such flows in earth gravity. Pressure drop modeling by the homogeneous flow model was inconclusive for bubble and slug flows. Annular flows were found to be complex systems of ring-like waves and a

  14. Single-phase cadmium telluride thin films deposited by electroless electrodeposition

    International Nuclear Information System (INIS)

    Khrypunov, G.; Klochko, N.; Lyubov, V.; Li, T.; Volkova, N.

    2010-01-01

    Full text : Today cadmium telluride (CdTe) is a leading base material for the fabrication of thin film solar cells. Equally with the creation of traditional thin film photovoltaic devices on the base of CdTe in recent years several approaches have been investigated to develop solar cells with extremely thin (80-500 nm) CdTe absorber (so-called ηE(eta)-solar cells) that offer the potential to reduce recombination losses in the base layers and thus use low cost materials. Until today the CdTe depositions for the η-solar cells manufacture were performed by vapour phase epitaxy under dynamical vacuum at working temperature 750 degrees Celsium or by electrodeposition in the special electrochemical cell equipped with the potentiostat. Development research of simple and inexpensive method for obtaining of the single-phase stoichiometric cadmium telluride films has required an improvement of the electroless electrodeposition technique, which theretofore was characterized by some disadvantages, namely, the CdTe films were polluted by free tellurium additions and the composition of the films was Cd:Te=55:45. So, for the showing up the synthesis of doped or stoichiometric cadmium telluride films conditions and in order to decide the problem of the deposition of single-phase CdTe layers it was researched the electrochemical processes going during electroless electrolysis in sulfate solutions with different acidities and CdSO 4 concentrations. Some film samples during deposition were illuminated by 500 W halogen lamp. Deposition time was 10-15 min. The phase composition and structure of the deposited films were determined by XRD-method, the average sizes of the crystalline grains in the films were estimated using Debye-Scherer formula. The transmittance spectra of the samples were measured by double beam spectrophotometer in the spectral range of 0.6-1.1 μm. Surface morphology of the films was researched by scanning electron microscopy. By means of analysis of the

  15. COMMIX-1AR/P: A three-dimensional transient single-phase computer program for thermal hydraulic analysis of single and multicomponent systems

    Energy Technology Data Exchange (ETDEWEB)

    Garner, P.L.; Blomquist, R.N.; Gelbard, E.M.

    1992-09-01

    The COMMIX-LAR/P computer program is designed for analyzing the steady-state and transient aspects of single-phase fluid flow and heat transfer in three spatial dimensions. This version is an extension of the modeling in COMMIX-lA to include multiple fluids in physically separate regions of the computational domain, modeling descriptions for pumps, radiation heat transfer between surfaces of the solids which are embedded in or surround the fluid, a keg model for fluid turbulence, and improved numerical techniques. The porous-medium formulation in COMMIX allows the program to be applied to a wide range of problems involving both simple and complex geometrical arrangements. The internal aspects of the COMMIX-LAR/P program are presented, covering descriptions of subprograms, variables, and files.

  16. COMMIX-1AR/P: A three-dimensional transient single-phase computer program for thermal hydraulic analysis of single and multicomponent systems

    International Nuclear Information System (INIS)

    Garner, P.L.; Blomquist, R.N.; Gelbard, E.M.

    1992-09-01

    The COMMIX-1AR/P computer program is designed for analyzing the steady-state and transient aspects of single-phase fluid flow and heat transfer in three spatial dimensions. This version is an extension of the modeling in COMMIX-1A to include multiple fluids in physically separate regions of the computational domain, modeling descriptions for pumps, radiation heat transfer between surfaces of the solids which are embedded in or surround the fluid, a k-var-epsilon model for fluid turbulence, and improved numerical techniques. The porous-medium formulation in COMMIX allows the program to be applied to a wide range of problems involving both simple and complex geometrical arrangements. The input preparation and execution procedures are presented for the COMMIX-1AR/P program and several postprocessor programs which produce graphical displays of the calculated results

  17. COMMIX-1AR/P: A three-dimensional transient single-phase computer program for thermal hydraulic analysis of single and multicomponent systems

    Energy Technology Data Exchange (ETDEWEB)

    Garner, P.L.; Blomquist, R.N.; Gelbard, E.M.

    1992-09-01

    The COMMIX-1AR/P computer program is designed for analyzing the steady-state and transient aspects of single-phase fluid flow and heat transfer in three spatial dimensions. This version is an extension of the modeling in COMMIX-1A to include multiple fluids in physically separate regions of the computational domain, modeling descriptions for pumps, radiation heat transfer between surfaces of the solids which are embedded in or surround the fluid, a k-[var epsilon] model for fluid turbulence, and improved numerical techniques. The porous-medium formulation in COMMIX allows the program to be applied to a wide range of problems involving both simple and complex geometrical arrangements. The input preparation and execution procedures are presented for the COMMIX-1AR/P program and several postprocessor programs which produce graphical displays of the calculated results.

  18. On Thermodynamics Problems in the Single-Phase-Lagging Heat Conduction Model

    Directory of Open Access Journals (Sweden)

    Shu-Nan Li

    2016-11-01

    Full Text Available Thermodynamics problems for the single-phase-lagging (SPL model have not been much studied. In this paper, the violation of the second law of thermodynamics by the SPL model is studied from two perspectives, which are the negative entropy production rate and breaking equilibrium spontaneously. The methods for the SPL model to avoid the negative entropy production rate are proposed, which are extended irreversible thermodynamics and the thermal relaxation time. Modifying the entropy production rate positive or zero is not enough to avoid the violation of the second law of thermodynamics for the SPL model, because the SPL model could cause breaking equilibrium spontaneously in some special circumstances. As comparison, it is shown that Fourier’s law and the CV model cannot break equilibrium spontaneously by analyzing mathematical energy integral.

  19. Single-Phase Microgrid with Seamless Transition Capabilities between Modes of Operation

    DEFF Research Database (Denmark)

    Micallef, Alexander; Apap, Maurice; Spiteri-Staines, Cyril

    2015-01-01

    Microgrids are an effective way to increase the penetration of DG into the grid. They are capable of operating either in grid-connected or in islanded mode thereby increasing the supply reliability for the end user. This paper focuses on achieving seamless transitions from islanded to grid......-connected and vice versa for a single phase microgrid made up from voltage controlled voltage source inverters (VC-VSIs) and current controlled voltage source inverters (CC-VSIs) working together in both modes of operation. The primary control structures for the VC-VSIs and CC-VSIs is considered together...... with the secondary control loops that are used to synchronize the microgrid as a single unit to the grid. Simulation results are given that show the seamless transitions between the two modes without any disconnection times for the CC-VSIs and VC-VSIs connected to the microgrid....

  20. Single-phase pump model for analysis of LMFBR heat transport systems

    International Nuclear Information System (INIS)

    Madni, I.K.; Cazzoli, E.

    1978-05-01

    A single-phase pump model for transient and steady-state analysis of LMFBR heat transport systems is presented. Fundamental equations of the model are angular momentum balance to determine transient impeller speed and mass balance (including thermal expansion effects) to determine the level of sodium in the pump tank. Pump characteristics are modeled by homologous head and torque relations. All regions of pump operation are represented with reverse rotation allowed. The model also includes option for enthalpy rise calculations and pony motor operation. During steady state, the pump operating speed is determined by matching required head with total load in the circuit. Calculated transient results are presented for pump coastdown and double-ended pipe break accidents. The report examines the influence of frictional torque and specific speed on predicted response for the pump coastdown to natural circulation transient. The results for a double-ended pipe break accident indicate the necessity of including all regions of operation for pump characteristics

  1. Single-phase sodium pump model for LMFBR thermal-hydraulic analysis

    International Nuclear Information System (INIS)

    Madni, I.K.; Cazzoli, E.G.; Agrawal, A.K.

    1979-01-01

    A single-phase, homologous pump model has been developed for simulation of safety-related transients in LMFBR systems. Pump characteristics are modeled by homologous head and torque relations encompassing all regimes of operation. These relations were derived from independent model test results with a centrifugal pump of specific speed equal to 35 (SI units) or 1800 (gpm units), and are used to analyze the steady-state and transient behavior of sodium pumps in a number of LMFBR plants. Characteristic coefficients for the polynomials in all operational regimes are provided in a tabular form. The speed and flow dependence of head is included through solutions of the impeller and coolant dynamic equations. Results show the model to yield excellent agreement with experimental data in sodium for the FFTF prototype pump, and with vendor calculations for the CRBR pump. A sample pipe rupture calculation is also performed to demonstrate the necessity for modeling the complete pump characteristics

  2. Analytical Determining Of The Steinmetz Equivalent Diagram Elements Of Single-Phase Transformer

    Directory of Open Access Journals (Sweden)

    T. Aly Saandy

    2015-08-01

    Full Text Available This article presents to an analytical calculation methodology of the Steinmetz Equivalent Diagram Elements applied to the prediction of Eddy current loss in a single-phase transformer. Based on the electrical circuit theory the active and reactive powers consumed by the core are expressed analytically in function of the electromagnetic parameters as resistivity permeability and the geometrical dimensions of the core. The proposed modeling approach is established with the duality parallel series. The equivalent diagram elements empirically determined by Steinmetz are analytically expressed using the expressions of the no loaded transformer consumptions. To verify the relevance of the model validations both by simulations with different powers and measurements were carried out to determine the resistance and reactance of the core. The obtained results are in good agreement with the theoretical approach and the practical results.

  3. Analytical Modeling Of The Steinmetz Coefficient For Single-Phase Transformer Eddy Current Loss Prediction

    Directory of Open Access Journals (Sweden)

    T. Aly Saandy

    2015-08-01

    Full Text Available Abstract This article presents to an analytical calculation methodology of the Steinmetz coefficient applied to the prediction of Eddy current loss in a single-phase transformer. Based on the electrical circuit theory the active power consumed by the core is expressed analytically in function of the electrical parameters as resistivity and the geometrical dimensions of the core. The proposed modeling approach is established with the duality parallel series. The required coefficient is identified from the empirical Steinmetz data based on the experimented active power expression. To verify the relevance of the model validations both by simulations with two in two different frequencies and measurements were carried out. The obtained results are in good agreement with the theoretical approach and the practical results.

  4. Low voltage ride-through of single-phase transformerless photovoltaic inverters

    DEFF Research Database (Denmark)

    Yang, Yongheng; Blaabjerg, Frede; Wang, Huai

    2013-01-01

    Transformerless photovoltaic (PV) inverters are going to be more widely adopted in order to achieve high efficiency, as the penetration level of PV systems is continuously booming. However, problems may arise in highly PV-integrated distribution systems. For example, a sudden stoppage of all PV...... systems due to anti-islanding protection may trigger grid disturbances. Thus, standards featuring with ancillary services for the next generation PV systems are under a revision in some countries. The future PV systems have to provide a full range of services as what the conventional power plants do, e...... discussed. The selected inverters are the full-bridge inverter with bipolar modulation, full-bridge inverter with DC bypass and the Highly Efficient and Reliable Inverter Concept (HERIC). A 1 kW single-phase grid-connected PV system is analyzed to verify the discussions. The tests confirmed that, although...

  5. Modelling and Simulation of Single-Phase Series Active Compensator for Power Quality Improvement

    Science.gov (United States)

    Verma, Arun Kumar; Mathuria, Kirti; Singh, Bhim; Bhuvaneshwari, G.

    2017-10-01

    A single-phase active series compensator is proposed in this work to reduce harmonic currents at the ac mains and to regulate the dc link voltage of a diode bridge rectifier (DBR) that acts as the front end converter for a voltage source inverter feeding an ac motor. This ac motor drive is used in any of the domestic, commercial or industrial appliances. Under fluctuating ac mains voltages, the dc link voltage of the DBR depicts wide variations and hence the ac motor is used at reduced rating as compared to its name-plate rating. The active series compensator proposed here provides dual functions of improving the power quality at the ac mains and regulating the dc link voltage thus averting the need for derating of the ac motor.

  6. Reactive Power Injection Strategies for Single-Phase Photovoltaic Systems Considering Grid Requirements

    DEFF Research Database (Denmark)

    Yang, Yongheng; Wang, Huai; Blaabjerg, Frede

    2014-01-01

    .g. Germany and Italy. Those advanced features can be provided by next generation PV systems, and will be enhanced in the future to ensure an even efficient and reliable utilization of PV systems. In light of this, Reactive Power Injection (RPI) strategies for single-phase PV systems are explored...... like what the conventional power plants do today in the grid regulation participation. Requirements of ancillary services like Low-Voltage Ride-Through (LVRT) associated with reactive current injection and voltage support through reactive power control, have been in effectiveness in some countries, e...... in this paper. The RPI possibilities are: a) constant average active power control, b) constant active current control, c) constant peak current control and d) thermal optimized control strategy. All those strategies comply with the currently active grid codes, but are with different objectives. The proposed...

  7. Reactive Power Injection Strategies for Single-Phase Photovoltaic Systems Considering Grid Requirements

    DEFF Research Database (Denmark)

    Yang, Yongheng; Wang, Huai; Blaabjerg, Frede

    2014-01-01

    . Those advanced features can be provided by next-generation PV systems, and will be enhanced in the future to ensure an even efficient and reliable utilization of PV systems. In the light of this, Reactive Power Injection (RPI) strategies for single-phase PV systems are explored in this paper. The RPI...... like what the conventional power plants do today in the grid regulation participation. Requirements of ancillary services like Low-Voltage Ride-Through (LVRT) associated with reactive current injection and voltage support through reactive power control, have been in effectiveness in some countries...... possibilities are: a) constant average active power control, b) constant active current control, c) constant peak current control and d) thermal optimized control strategy. All those strategies comply with the currently active grid codes, but are with different objectives. The thermal optimized control strategy...

  8. Abrasion resistance, microhardness and microstructures of single-phase niobium nitride films

    International Nuclear Information System (INIS)

    Singer, I.L.; Bolster, R.N.; Wolf, S.A.; Skelton, E.F.; Jeffries, R.A.

    1983-01-01

    The relative abrasive wear resistance of single-phase niobium nitride films deposited at 900 and 500 0 C was measured. Wear resistance versus depth profiles of films abraded against 1-5 μm diamond were obtained by weight loss methods. A β phase Nb 2 N film was five to 20 times more abrasion resistant, but only slightly (40%) harder, than the delta phase NbN films made at the same temperature. The β-Nb 2 N film was deformed plastically during wear, reorienting the [002] c axis perpendicular to the plane of the substrate. The abrasion resistance of the delta-NbN films was initially proportional to the microhardness. Two films had changes in their abrasion resistance as wear proceeded: for one film the change was attributable to deviations in stoichiometry and for the other film it was attributable to increased lattice distortion. (Auth.)

  9. Influence of modulation method on using LC-traps with single-phase voltage source converters

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Min, Huang; Bai, Haofeng

    2015-01-01

    The switching-frequency LC-trap filter has recently been employed with high-order passive filters for Voltage Source Inverters (VSIs). This paper investigates the influence of modulation method on using the LC-traps with single-phase VSIs. Two-level (bipolar) and three-level (unipolar) modulations...... that include phase distortion and alternative phase opposition distortion methods are analyzed. Harmonic filtering performances of four LC-trap-based filters with different locations of LC-traps are compared. It is shown that the use of parallel-LC-traps in series with filter inductors, either grid...... or converter side, has a worse harmonic filtering performance than using series-LC-trap in the shunt branch. Simulations and experimental results are presented for verifications....

  10. Condition monitoring of shaft of single-phase induction motor using optical sensor

    Science.gov (United States)

    Fulzele, Asmita G.; Arajpure, V. G.; Holay, P. P.; Patil, N. M.

    2012-05-01

    Transmission type of optical technique is developed to sense the condition of rotating shafts from a distance. A parallel laser beam is passed tangential over the surface of rotating shaft of a single phase induction motor and its flickering shadow is received on a photo sensor. Variations in sensor voltage output are observed on a digital storage oscilloscope. It is demonstrated that this signal carries information about shaft defects like miss alignment, play and impacts in bearings along with surface deformities. Mathematical model of signals corresponding to these shaft defects is developed. During the development and testing of the sensor, effects of reflections are investigated, sensing phenomenon is simulated, frequency response of the sensor is obtained and its performance is compared with conventional accelerometer.

  11. POD-Galerkin Model for Incompressible Single-Phase Flow in Porous Media

    KAUST Repository

    Wang, Yi

    2017-01-25

    Fast prediction modeling via proper orthogonal decomposition method combined with Galerkin projection is applied to incompressible single-phase fluid flow in porous media. Cases for different configurations of porous media, boundary conditions and problem scales are designed to examine the fidelity and robustness of the model. High precision (relative deviation 1.0 x 10(-4)% similar to 2.3 x 10(-1)%) and large acceleration (speed-up 880 similar to 98454 times) of POD model are found in these cases. Moreover, the computational time of POD model is quite insensitive to the complexity of problems. These results indicate POD model is especially suitable for large-scale complex problems in engineering.

  12. Broadband single-phase hyperbolic elastic metamaterials for super-resolution imaging.

    Science.gov (United States)

    Dong, Hao-Wen; Zhao, Sheng-Dong; Wang, Yue-Sheng; Zhang, Chuanzeng

    2018-02-02

    Hyperbolic metamaterials, the highly anisotropic subwavelength media, immensely widen the engineering feasibilities for wave manipulation. However, limited by the empirical structural topologies, the reported hyperbolic elastic metamaterials (HEMMs) suffer from the limitations of the relatively narrow frequency width, inflexible adjustable operating subwavelength scale and difficulty to further improve the imaging resolution. Here, we show an inverse-design strategy for HEMMs by topology optimization. We design broadband single-phase HEMMs supporting multipolar resonances at different prescribed deep-subwavelength scales, and demonstrate the super-resolution imaging for longitudinal waves. Benefiting from the extreme enhancement of the evanescent waves, an optimized HEMM at an ultra-low frequency can yield an imaging resolution of ~λ/64, representing the record in the field of elastic metamaterials. The present research provides a novel and general design methodology for exploring the HEMMs with unrevealed mechanisms and guides the ultrasonography and general biomedical applications.

  13. Pressure drop characteristics of single-phase flow in vertical rolling pipes

    International Nuclear Information System (INIS)

    Cao Xiaxin; Yan Changqi; Sun Licheng; Sun Zhongning

    2007-01-01

    Experimental studies of single-phase pressure drop in rolling pipes were carried out. The inside diameters of three pipes which were fixed on the rolling platform were 15 mm, 25 mm, and 34.5 mm respectively, the rolling periods of the rolling platform could be set as 5s, 10s, 15s, and rolling angles of the rolling platform were 10 degree and 20 degree. The experimental results showed that the frictional factor periodically fluctuated with the time variable, and its amplitude was obviously affected by the change of Reynolds number and pipe diameters. The amplitude and average value of frictional factor both decreased with the increase of Re number, but the bigger the tube diameter was, the larger the amplitude of frictional factor was. At any moment, the transient frictional factor increased with the increase of rolling period. However, the effect of changing rolling angles on the frictional factor was not obvious. (authors)

  14. Green synthesis of isopropyl myristate in novel single phase medium Part I: Batch optimization studies.

    Science.gov (United States)

    Vadgama, Rajeshkumar N; Odaneth, Annamma A; Lali, Arvind M

    2015-12-01

    Isopropyl myristate finds many applications in food, cosmetic and pharmaceutical industries as an emollient, thickening agent, or lubricant. Using a homogeneous reaction phase, non-specific lipase derived from Candida antartica, marketed as Novozym 435, was determined to be most suitable for the enzymatic synthesis of isopropyl myristate. The high molar ratio of alcohol to acid creates novel single phase medium which overcomes mass transfer effects and facilitates downstream processing. The effect of various reaction parameters was optimized to obtain a high yield of isopropyl myristate. Effect of temperature, agitation speed, organic solvent, biocatalyst loading and batch operational stability of the enzyme was systematically studied. The conversion of 87.65% was obtained when the molar ratio of isopropyl alcohol to myristic acid (15:1) was used with 4% (w/w) catalyst loading and agitation speed of 150 rpm at 60 °C. The enzyme has also shown good batch operational stability under optimized conditions.

  15. Rotor Design for an Efficient Single-Phase Induction Motor for Refrigerator Compressors

    Directory of Open Access Journals (Sweden)

    Hyun-Jin Ahn

    2016-03-01

    Full Text Available This article describes a rotor making technology for the production of high-efficiency single-phase induction motors (SPIMs to be used in refrigerator compressors. Rotors can have different aluminum fill factors according to the fabrication method. In order to examine the association between the fill factor and the efficiency of the rotor, we analyzed the distribution of magnetic flux density using the finite element method (FEM. Next, we made prototype rotors by conventional casting methods and by the proposed casting method and compared their fill factors. In addition, SPIMs were made using the rotors, and their efficiencies were measured using a dynamometer. Moreover, the SPIMs were put to use in a compressor, for testing, and for each SPIM the refrigerating capacity of the compressor was measured with a calorimeter. Based on the results of the FEM analysis of the magnetic flux density and the experiments, the reliability and validity of the proposed method were proven.

  16. Control of single-phase islanded PV/battery minigrids based on power-line signaling

    DEFF Research Database (Denmark)

    Quintana, Pablo; Guerrero, Josep M.; Dragicevic, Tomislav

    2014-01-01

    Power regulation of all converter units in a micro-grid should not be only determined by load demand, but also by the available power of each unit, i.e. a converter fed by a battery. Energy management control is essential in order to handle the variety of prime movers which may include different...... should be utilized as efficiently as possible. This paper proposes a coordinated control strategy based on power-line signaling (PLS), instead of common communications, for a single-phase minigrid in which each unit can operate in different operation modes taking into account the resource limitation....... The whole system is explained ahead and finally, Hardware in the loop results obtained with a dSPACE are presented in order to validate the proposed control strategy....

  17. Reliability assessment of single-phase grid-connected PV microinverters considering mission profile and uncertainties

    DEFF Research Database (Denmark)

    Zare, Mohammad Hadi; Mohamadian, Mustafa; Wang, Huai

    2017-01-01

    Microinverters usually connect a PV panel to a Single-phase power grid. In such system, the input power is constant while the output power oscillates twice the line frequency. Thus, the input and output power differences should be stored in a storage component, which is typically an electrolytic...... capacitor. However, electrolytic capacitors are usually blamed for their short lifetime. Recently, some active power decoupling methods are introduced in the literature which can takes advantage of high reliable film capacitors. However, some extra switches and diodes are added to the microinverter which...... can influence the microinverter lifetime. This paper investigates the microinverter reliability according to mission profile where it is installed. To get more accurate results, uncertainties in both lifetime model and manufacturing process are considered. The effect of ambient temperature and solar...

  18. Decoupling of fluctuating power in single-phase systems through a symmetrical half-bridge circuit

    DEFF Research Database (Denmark)

    Tang, Yi; Blaabjerg, Frede; Loh, Poh Chiang

    2014-01-01

    Single-phase AC/DC or DC/AC systems inherently subject to harmonic disturbance which is caused by the well-known double line frequency ripple power. This issue can be eased through the installation of bulky electrolytic capacitors in the dc-link, but such passive filtering approach may inevitably...... or film capacitors to store the ripple power, and this again leads to increased component costs. In view of this, this paper presents a symmetrical half-bridge circuit which utilizes the dc-link capacitors to absorb the ripple power, and the only additional components are a pair of switches and a small...... filtering inductor. A design example is presented and the proposed circuit concept is also verified with simulation and experimental results. It shows that at least ten times capacitance reduction can be achieved with the proposed active power decoupling method, which proves its effectiveness....

  19. Pattern formation in single-phase FAC. A stability analysis of an oxide layer

    Energy Technology Data Exchange (ETDEWEB)

    Zinemanas, Daniel [The Israel Electric Corp., Haifa (Israel). Dept. of Chemistry; Herszage, Amiel [The Israel Electric Corp., Haifa (Israel). Dept. of Energy Technologies Development

    2013-03-15

    Pattern formation is a salient characteristic of the flow-accelerated corrosion process, particularly in single-phase flow, where a typical ''orange peel'' surface texture is normally formed. The process of such pattern formation is, however, not well understood. In order to gain some insight into the role of the various processes and parameters involved in this process, a linear stability analysis of an oxide layer based on the Sanchez-Caldera model was performed. According to the results obtained in this study, it follows that the oxide layer is stable regarding perturbations of the oxide thickness or the reaction constant, but it is unstable in respect to perturbations of the mass transfer coefficient. These results suggest therefore that the flow, and not local surface in homogeneities, plays a central role in the pattern formation process. (orig.)

  20. Realization of single-phase single-stage grid-connected PV system

    Directory of Open Access Journals (Sweden)

    Osama M. Arafa

    2017-05-01

    Full Text Available This paper presents a single phase single stage grid-tied PV system. Grid angle detection is introduced to allow operation at any arbitrary power factor but unity power factor is chosen to utilize the full inverter capacity. The system ensures MPPT using the incremental conductance method and it can track the changes in insolation level without oscillations. A PI voltage controller and a dead-beat current controller are used to ensure high quality injected current to the grid. The paper investigates the system structure and performance through numerical simulation using Matlab/Simulink. An experimental setup controlled by the MicrolabBox DSP prototyping platform is utilized to realize the system and study its performance. The precautions for smooth and safe system operation including the startup sequence are fully considered in the implementation.

  1. Adaptive fuzzy sliding control of single-phase PV grid-connected inverter.

    Directory of Open Access Journals (Sweden)

    Juntao Fei

    Full Text Available In this paper, an adaptive fuzzy sliding mode controller is proposed to control a two-stage single-phase photovoltaic (PV grid-connected inverter. Two key technologies are discussed in the presented PV system. An incremental conductance method with adaptive step is adopted to track the maximum power point (MPP by controlling the duty cycle of the controllable power switch of the boost DC-DC converter. An adaptive fuzzy sliding mode controller with an integral sliding surface is developed for the grid-connected inverter where a fuzzy system is used to approach the upper bound of the system nonlinearities. The proposed strategy has strong robustness for the sliding mode control can be designed independently and disturbances can be adaptively compensated. Simulation results of a PV grid-connected system verify the effectiveness of the proposed method, demonstrating the satisfactory robustness and performance.

  2. Rapid synthesis of single-phase bismuth ferrite by microwave-assisted hydrothermal method

    International Nuclear Information System (INIS)

    Cao, Wenqian; Chen, Zhi; Gao, Tong; Zhou, Dantong; Leng, Xiaonan; Niu, Feng; Zhu, Yuxiang; Qin, Laishun; Wang, Jiangying; Huang, Yuexiang

    2016-01-01

    This paper describes on the fast synthesis of bismuth ferrite by the simple microwave-assisted hydrothermal method. The phase transformation and the preferred growth facets during the synthetic process have been investigated by X-ray diffraction. Bismuth ferrite can be quickly prepared by microwave hydrothermal method by simply controlling the reaction time, which is further confirmed by Fourier Transform infrared spectroscopy and magnetic measurement. - Graphical abstract: Single-phase BiFeO 3 could be realized at a shortest reaction time of 65 min. The reaction time has strong influences on the phase transformation and the preferred growth facets. - Highlights: • Rapid synthesis (65 min) of BiFeO 3 by microwave-assisted hydrothermal method. • Reaction time has influence on the purity and preferred growth facets. • FTIR and magnetic measurement further confirm the pure phase.

  3. S4 Grid-Connected Single-Phase Transformerless Inverter for PV Application

    DEFF Research Database (Denmark)

    Ardashir, Jaber Fallah; Siwakoti, Yam Prasad; Sabahi, Mehran

    2016-01-01

    This paper introduces a new single-phase transformerless inverter for grid-connected photovoltaic systems with low leakage current. It consists of four power switches, two diodes, two capacitors and a filter at the output stage. The neutral of the grid is directly connected to the negative terminal...... of the PV source. This results in a constant common-mode voltage and almost zero leakage current. A unipolar Sinusoidal Pulse-Width Modulation (SPWM) technique is used to modulate the inverter to reduce the output current ripple and the filter requirements. The main advantages of this inverter are compact...... clearly verify the performance of the proposed inverter and its practical application for grid-connected PV systems....

  4. Modelling of the modified-LLCL-filter-based single-phase grid-tied Aalborg inverter

    DEFF Research Database (Denmark)

    Liu, Zifa; Wu, Huiyun; Liu, Yuan

    2017-01-01

    Owing to less conduction and switching power losses, the recently proposed Aalborg inverter has high efficiency within a wide range of input DC voltage for single-phase DC/AC power conversion. In theory, the conduction power losses can be further decreased, if an LLCL-filter is adopted instead....... In this study, the small signal analysis for the modified-LLCL-filter-based Aalborg inverter is addressed. Through the modelling, it can be proven that compared with the LCL-filter, the modified-LLCL-filter causes no extra control challenge for the Aalborg inverter, and therefore more inductance in the power...... of an LCL-filter for a voltage source inverter, mainly due to the reduced inductance. The Aalborg inverter shows the characteristic of a current source inverter, when working in the `boost' state. Whether the LLCL-filter can meet the control requirement of this type inverter needs to be further explored...

  5. Compact ASD Topologies for Single-Phase Integrated Motor Drives with Sinusoidal Input Current

    DEFF Research Database (Denmark)

    Klumpner, Christian; Blaabjerg, Frede; Thoegersen, Paul

    2005-01-01

    A standard configuration of an Adjustable Speed Drive (ASD) consists of two separate units: an AC motor, which runs with fixed speed when it is supplied from a constant frequency grid voltage and a frequency converter, which is used to provide the motor with variable voltage-variable frequency......-density integration of the converter caused by the large size of the passive components (electrolytic capacitors and iron chokes) and vibration of the converter enclosure. This paper analyzes the implementation aspects for obtaining a compact and cost effective single-phase ASD with sinusoidal input current...... for high frequency operation, higher core losses will occur, but outside the converter enclosure. The advantages are: the reduction of the number of active semiconductor devices, the reduction of the ASD size and the better integration potential....

  6. A Rotor Flux and Speed Observer for Sensorless Single-Phase Induction Motor Applications

    Directory of Open Access Journals (Sweden)

    Massimo Caruso

    2012-01-01

    Full Text Available It is usual to find single-phase induction motor (SPIM in several house, office, shopping, farm, and industry applications, which are become each time more sophisticated and requiring the development of efficient alternatives to improve the operational performance of this machine. Although the rotor flux and rotational speed are essential variables in order to optimize the operation of a SPIM, the use of conventional sensors to measure them is not a viable option. Thus, the adoption of sensorless strategies is the more reasonable proposal for these cases. This paper presents a rotor flux and rotational speed observer for sensorless applications involving SPIMs. Computer simulations and the experimental results are used to verify the performance of the proposed observer.

  7. Factors that affect the calibration of turbines in single-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Piper, T. C.

    1977-05-01

    Basic turbine operation in single-phase flow is related. Causes and relative magnitudes of retarding torque are given for two sizes of turbines when used for water flow measurement. An equation for slip caused by retarding torques is given. Evaluation of turbine slip behavior at the turbine low flow region shows that bearing retarding torques, change in flow patterns, or other effects can predominate in the relatively large changes in the calibration ''constant'' that occurs there. Fluid lubricity is singled out as an important fluid property in certain types of bearings and flow. Temperature induced changes in turbine size are shown to cause calibration changes if a turbine is used at a temperature significantly different than that at which it was calibrated.

  8. Factors that affect the calibration of turbines in single-phase flow

    International Nuclear Information System (INIS)

    Piper, T.C.

    1977-05-01

    Basic turbine operation in single-phase flow is related. Causes and relative magnitudes of retarding torque are given for two sizes of turbines when used for water flow measurement. An equation for slip caused by retarding torques is given. Evaluation of turbine slip behavior at the turbine low flow region shows that bearing retarding torques, change in flow patterns, or other effects can predominate in the relatively large changes in the calibration ''constant'' that occurs there. Fluid lubricity is singled out as an important fluid property in certain types of bearings and flow. Temperature induced changes in turbine size are shown to cause calibration changes if a turbine is used at a temperature significantly different than that at which it was calibrated

  9. Single-phase pressure-drop measurements over low void reactivity fuel

    International Nuclear Information System (INIS)

    Senaratne, U.P.M.; Leung, L.K.H.; Doria, F.J.; Lau, J.H.

    2006-01-01

    An experiment has been performed to obtain pressure-drop measurements over Low Reactivity Fuel (LVRF) bundles in Refrigerant-134a flow. Production LVRF bundles inserted into the test station with either an uncrept or a 5.1% crept flow channel. For comparison purposes, several production Bruce 37-element bundles were also included in the test string. Overall, the single-phase pressure drop of the LVRF bundle is slightly higher than that Bruce 37-element bundle. Pressure-drop measurements were used to derive bundle and loss coefficients for hydraulic calculations in safety analyses. Applying these loss coefficients, an assessment showed that the overall pressure drop over a string of 12 LVRF bundles (after conversion) remains less than that over a string of 13 Bruce 37-element fuel bundles (before conversion) at the Bruce Nuclear Generating Station. (author)

  10. Calculation of single phase AC and monopolar DC hybrid corona effects

    International Nuclear Information System (INIS)

    Zhao, T.; Sebo, S.A.; Kasten, D.G.

    1996-01-01

    Operating a hybrid HVac and HVdc line is an option for increasing the efficiency of power transmission and overcoming the difficulties in obtaining a new right-of-way. This paper proposes a new calculation method for the study of hybrid line corona. The proposed method can be used to calculate dc corona losses and corona currents in dc or ac conductors for single phase ac and monopolar dc hybrid lines. Profiles of electric field strength and ion current density at ground level can be estimated. The effects of the presence of an energized ac conductor on dc conductor corona and dc voltage on ac conductor corona are included in the method. Full-scale and reduced-scale experiments were utilized to investigate the hybrid line corona effects. Verification of the proposed calculation method is given

  11. Hybrid Three-Phase/Single-Phase Microgrid Architecture with Power Management Capabilities

    DEFF Research Database (Denmark)

    Sun, Qiuye; Zhou, Jianguo; Guerrero, Josep M.

    2015-01-01

    With the fast proliferation of single-phase distributed generation (DG) units and loads integrated into residential microgrids, independent power sharing per phase and full use of the energy generated by DGs have become crucial. To address these issues, this paper proposes a hybrid microgrid...... control of load power sharing among phases, as well as to allow fully utilization of the energy generated by DGs. Meanwhile, the method combining the modified adaptive backstepping-sliding mode control approach and droop control is also proposed to design the SPBTB system controllers. With the application...... of the proposed PSU and its power management strategy, the loads among different phases can be properly supplied and the energy can be fully utilized as well as obtaining better load sharing. Simulation and experimental results are provided to demonstrate the validity of the proposed hybrid microgrid structure...

  12. Comparative study of Nusselt number for a single phase fluid flow using plate heat exchanger

    Directory of Open Access Journals (Sweden)

    Shanmugam Rajasekaran

    2016-01-01

    Full Text Available In this study, the plate heat exchangers are used for various applications in the industries for heat exchange process such as heating, cooling and condensation. The performance of plate heat exchanger depends on many factors such as flow arrangements, plate design, chevron angle, enlargement factor, type of fluid used, etc. The various Nusselt number correlations are developed by considering that the water as a working fluid. The main objective of the present work is to design the experimental set-up for a single phase fluid flow using plate heat exchanger and studied the heat transfer performance. The experiments are carried out for various Reynolds number between 500 and 2200, the heat transfer coefficients are estimated. Based on the experimental results the new correlation is developed for Nusselt number and compared with an existing correlation.

  13. Scaling analysis for the ocean motions in single phase natural circulation

    International Nuclear Information System (INIS)

    Yan, B.H.; Wen, Q.L.

    2015-01-01

    Highlights: • The scaling criteria for ocean motions are obtained. • The optimization and selection of the scaling criteria is also analyzed. • The oscillating period in experiments is determined by the time scale. - Abstract: The effects of ocean motions should be analyzed properly in order to guarantee the safety margin of facilities in the engineering design of floating nuclear reactor system. The scaling analysis for the ocean motions in single phase natural circulation is performed. The scaling criteria for both single ocean motions and compound ocean motions are obtained. The selection and optimization of scaling criteria is also analyzed. The oscillating amplitude in experiments should be kept to be identical to that in actual ocean motions. The oscillating period is determined by the time scale. The length scale, oscillating period and experimental power should be taken into consideration synthetically to obtain a reasonable experimental period

  14. Harmonics Suppression for Single-Phase Grid-Connected Photovoltaic Systems in Different Operation Modes

    DEFF Research Database (Denmark)

    Yang, Yongheng; Zhou, Keliang; Blaabjerg, Frede

    2013-01-01

    -connected PV inverters may be severely affected in different operation modes. In this paper, a detailed analysis is conducted to reveal the relationship between the harmonics level with the power factor and the current level in the PV systems. A current control solution which employs an Internal Model...... Principle (IMP) is proposed to suppress the harmonic currents injected into the grid. Experiments are carried out to verify the analysis and the performance of the proposed control method. It is demonstrated that the proposed method presents an effective solution to harmonics suppression for single......-phase grid-connected PV systems in different operation modes. Especially, it can remove higher order harmonics effectively leading to a better power quality compared to the Proportional plus Multi-Resonant Controller, and it has less computational burden....

  15. Time domain spectral phase encoding/DPSK data modulation using single phase modulator for OCDMA application.

    Science.gov (United States)

    Wang, Xu; Gao, Zhensen; Kataoka, Nobuyuki; Wada, Naoya

    2010-05-10

    A novel scheme using single phase modulator for simultaneous time domain spectral phase encoding (SPE) signal generation and DPSK data modulation is proposed and experimentally demonstrated. Array- Waveguide-Grating and Variable-Bandwidth-Spectrum-Shaper based devices can be used for decoding the signal directly in spectral domain. The effects of fiber dispersion, light pulse width and timing error on the coding performance have been investigated by simulation and verified in experiment. In the experiment, SPE signal with 8-chip, 20GHz/chip optical code patterns has been generated and modulated with 2.5 Gbps DPSK data using single modulator. Transmission of the 2.5 Gbps data over 34km fiber with BEROCDMA) and secure optical communication applications. (c) 2010 Optical Society of America.

  16. Simulation of the remanence influence on the transient states in a single-phase multiwinding transformer

    Directory of Open Access Journals (Sweden)

    Wilk Andrzej

    2017-03-01

    Full Text Available This paper presents the mathematical model of a single-phase multi-winding core type transformer taking into account magnetic hysteresis phenomenon based on the feedback Preisach model (FPM. The set of loop differential equations was developed for a K-th winding transformer model where the flux linkages of each winding includes flux Φ common to all windings as a function of magneto motive force Θ of all windings. The first purpose of this paper is to implement a hysteresis nonlinearity involved in the Φ(Θ function which also accounts residual magnetic flux. The second purpose of this paper is experimental validation of the developed transformer model in a capacitor discharge test and several different values of residual magnetic flux.

  17. Adaptive fuzzy sliding control of single-phase PV grid-connected inverter.

    Science.gov (United States)

    Fei, Juntao; Zhu, Yunkai

    2017-01-01

    In this paper, an adaptive fuzzy sliding mode controller is proposed to control a two-stage single-phase photovoltaic (PV) grid-connected inverter. Two key technologies are discussed in the presented PV system. An incremental conductance method with adaptive step is adopted to track the maximum power point (MPP) by controlling the duty cycle of the controllable power switch of the boost DC-DC converter. An adaptive fuzzy sliding mode controller with an integral sliding surface is developed for the grid-connected inverter where a fuzzy system is used to approach the upper bound of the system nonlinearities. The proposed strategy has strong robustness for the sliding mode control can be designed independently and disturbances can be adaptively compensated. Simulation results of a PV grid-connected system verify the effectiveness of the proposed method, demonstrating the satisfactory robustness and performance.

  18. Effects of rolling on single-phase water forced convective heat transfer characteristics

    International Nuclear Information System (INIS)

    Guo Yanming; Gao Puzhen; Huang Zhen

    2010-01-01

    A series of single-phase forced circulation tests in a vertical tube with rolling motion were performed in order to investigate effects of rolling motion on thermal-hydraulic characteristics. The amplitudes of the rolling motion in the tests were 10 degree, 15 degree and 20 degree. The rolling periods were 7.5 s, 10 s, 15 s and 20 s. The Reynolds number was from 6000 to 15000. Heat transfer in the test tube is bated by the rolling motion. As the test-bed rolling more acutely, the heat transfer coefficient of the test tube becomes smaller when the mass flow rate in the test tube is a constant. The heat transfer coefficient calculated by the formula which is for stable state doesn't fit very well with that from experiments. At last a formula for calculating heat transfer in rolling motion was introduced. (authors)

  19. A Robust DC-Split-Capacitor Power Decoupling Scheme for Single-Phase Converter

    DEFF Research Database (Denmark)

    Yao, Wenli; Loh, Poh Chiang; Tang, Yi

    2017-01-01

    , instead of the usual single dc-link capacitor bank. Methods for regulating this power decoupler have earlier been developed, but almost always with equal capacitances assumed for forming the dc-split capacitor, even though it is not realistic in practice. The assumption should, hence, be evaluated more......Instead of bulky electrolytic capacitors, active power decoupling circuit can be introduced to a single-phase converter for diverting second harmonic ripple away from its dc source or load. One possible circuit consists of a half-bridge and two capacitors in series for forming a dc-split capacitor...... thoroughly, especially when it is shown in the paper that even a slight mismatch can render the power decoupling scheme ineffective and the IEEE 1547 standard to be breached. A more robust compensation scheme is, thus, needed for the dc-split capacitor circuit, as proposed and tested experimentally...

  20. Zero-voltage ride-through capability of single-phase grid-connected photovoltaic systems

    DEFF Research Database (Denmark)

    Zhang, Zhen; Yang, Yongheng; Ma, Ruiqing

    2017-01-01

    Distributed renewable energy systems play an increasing role in today’s energy paradigm. Thus, intensive research activities have been centered on improving the performance of renewable energy systems, including photovoltaic (PV) systems, which should be of multiple-functionality. That is, the PV...... systems should be more intelligent in the consideration of grid stability, reliability, and fault protection. Therefore, in this paper, the performance of single-phase grid-connected PV systems under an extreme grid fault (i.e., when the grid voltage dips to zero) is explored. It has been revealed...... that combining a fast and accurate synchronization mechanism with appropriate control strategies for the zero-voltage ride-through (ZVRT) operation is mandatory. Accordingly, the representative synchronization techniques (i.e., the phase-locked loop (PLL) methods) in the ZVRT operation are compared in terms...

  1. A unified active damping control for single-phase differential buck inverter with LCL-filter

    DEFF Research Database (Denmark)

    Yao, Wenli; Wang, Xiongfei; Zhang, Xiaobin

    2015-01-01

    and control of a grid-connected differential mode buck inverter with an LCL filter. A generalized small-signal model of the inverter is built first with the averaged switching model. It is shown that the LCL filter resonance merely occurs in the differential mode, while an LC filter resonance exists......The single-phase differential mode buck inverter is recently introduced with a differential mode for power transfer and a common mode for actively decoupling the second-order power oscillation. However, it is limited to islanded applications with an LC filter. This paper addresses the stability...... in the common mode, provided that the filter parameters of the two bridges are kept the same. A unified active damping control approach is then proposed for stabilizing the inverter and improving the transient performance under a wide range of grid impedance. Lastly, experimental tests are carried out...

  2. Single-phase dual-energy CT urography in the evaluation of haematuria.

    Science.gov (United States)

    Ascenti, G; Mileto, A; Gaeta, M; Blandino, A; Mazziotti, S; Scribano, E

    2013-02-01

    To assess the value of a single-phase dual-energy computed tomography (DECT) urography protocol with synchronous nephrographic-excretory phase enhancement and to calculate the potential dose reduction by omitting the unenhanced scan. Eighty-four patients referred for haematuria underwent CT urography using a protocol that included single-energy unenhanced and dual-energy contrast-enhanced with synchronous nephrographic-excretory phase scans. DECT-based images [virtual unenhanced (VUE), weighted average, and colour-coded iodine overlay] were reconstructed. Opacification degree by contrast media of the upper urinary tract, and image quality of virtual unenhanced images were independently evaluated using a four-point scale. The diagnostic accuracy in detecting urothelial tumours on DECT-based images was determined. The dose of a theoretical dual-phase single-energy protocol was obtained by multiplying the effective dose of the unenhanced single-energy acquisition by two. Radiation dose saving by omitting the unenhanced scan was calculated. The degree of opacification was scored as optimal or good in 86.9% of cases (k = 0.72); VUE image quality was excellent or good in 83.3% of cases (k = 0.82). Sensitivity, specificity, positive predictive value, and negative predictive value for urothelial tumours detection were 85.7, 98.6, 92.3, and 97.1%. Omission of the unenhanced scan led to a mean dose reduction of 42.7 ± 5%. Single-phase DECT urography with synchronous nephrographic-excretory phase enhancement represents an accurate "all-in-one'' approach with a radiation dose saving up to 45% compared with a standard dual-phase protocol. Copyright © 2012 The Royal College of Radiologists. All rights reserved.

  3. Single-phase dual-energy CT urography in the evaluation of haematuria

    International Nuclear Information System (INIS)

    Ascenti, G.; Mileto, A.; Gaeta, M.; Blandino, A.; Mazziotti, S.; Scribano, E.

    2013-01-01

    Aim: To assess the value of a single-phase dual-energy computed tomography (DECT) urography protocol with synchronous nephrographic–excretory phase enhancement and to calculate the potential dose reduction by omitting the unenhanced scan. Materials and methods: Eighty-four patients referred for haematuria underwent CT urography using a protocol that included single-energy unenhanced and dual-energy contrast-enhanced with synchronous nephrographic–excretory phase scans. DECT-based images [virtual unenhanced (VUE), weighted average, and colour-coded iodine overlay] were reconstructed. Opacification degree by contrast media of the upper urinary tract, and image quality of virtual unenhanced images were independently evaluated using a four-point scale. The diagnostic accuracy in detecting urothelial tumours on DECT-based images was determined. The dose of a theoretical dual-phase single-energy protocol was obtained by multiplying the effective dose of the unenhanced single-energy acquisition by two. Radiation dose saving by omitting the unenhanced scan was calculated. Results: The degree of opacification was scored as optimal or good in 86.9% of cases (k = 0.72); VUE image quality was excellent or good in 83.3% of cases (k = 0.82). Sensitivity, specificity, positive predictive value, and negative predictive value for urothelial tumours detection were 85.7, 98.6, 92.3, and 97.1%. Omission of the unenhanced scan led to a mean dose reduction of 42.7 ± 5%. Conclusion: Single-phase DECT urography with synchronous nephrographic–excretory phase enhancement represents an accurate “all-in-one’’ approach with a radiation dose saving up to 45% compared with a standard dual-phase protocol.

  4. Multi-scale Modeling of Compressible Single-phase Flow in Porous Media using Molecular Simulation

    KAUST Repository

    Saad, Ahmed Mohamed

    2016-05-01

    In this study, an efficient coupling between Monte Carlo (MC) molecular simulation and Darcy-scale flow in porous media is presented. The cell-centered finite difference method with a non-uniform rectangular mesh were used to discretize the simulation domain and solve the governing equations. To speed up the MC simulations, we implemented a recently developed scheme that quickly generates MC Markov chains out of pre-computed ones, based on the reweighting and reconstruction algorithm. This method astonishingly reduces the required computational time by MC simulations from hours to seconds. In addition, the reweighting and reconstruction scheme, which was originally designed to work with the LJ potential model, is extended to work with a potential model that accounts for the molecular quadrupole moment of fluids with non-spherical molecules such as CO2. The potential model was used to simulate the thermodynamic equilibrium properties for single-phase and two-phase systems using the canonical ensemble and the Gibbs ensemble, respectively. Comparing the simulation results with the experimental data showed that the implemented model has an excellent fit outperforming the standard LJ model. To demonstrate the strength of the proposed coupling in terms of computational time efficiency and numerical accuracy in fluid properties, various numerical experiments covering different compressible single-phase flow scenarios were conducted. The novelty in the introduced scheme is in allowing an efficient coupling of the molecular scale and Darcy scale in reservoir simulators. This leads to an accurate description of the thermodynamic behavior of the simulated reservoir fluids; consequently enhancing the confidence in the flow predictions in porous media.

  5. Effects of rolling on characteristics of single-phase water flow in narrow rectangular ducts

    International Nuclear Information System (INIS)

    Xing Dianchuan; Yan Changqi; Sun Licheng; Xu Chao

    2012-01-01

    Highlights: ► Mass flow rate and friction pressure drop with different pressure head are compared. ► The effect of pressure head on flow fluctuation is considered theoretically. ► Time-mean and real-time friction pressure drop in different rolling motion are studied. ► Rolling motion influences the fluctuation of friction pressure drop in two aspects. ► New correlation for frictional coefficient in rolling motion is achieved. - Abstract: Experimental and theoretical studies of rolling effects on characteristics of single-phase water flow in narrow rectangular ducts are performed under ambient temperature and pressure. Two types of pressure head are supplied by elevate water tank and pump respectively. The results show that the frictional pressure drop under rolling condition fluctuates periodically, with its amplitude decaying as mean Reynolds number increase and the rolling amplitude decrease, while the amplitude is nearly invariable with rolling period. Rolling motion influences the fluctuation amplitude of frictional pressure drop in two aspects, on the one hand, rolling reduced periodical pulsing flow leads to the fluctuation of the frictional pressure drop, on the other hand, additional force acting on fluid near the wall due to the rolling motion makes local frictional resistance oscillate periodically. The mass flow rate oscillates periodically in rolling motion with the pressure head supplied by water tank, while its fluctuation is so weak that could be neglected for the case of the pressure head supplied by pump. An empirical correlation for the frictional coefficient under rolling condition is achieved, and the experimental data is well correlated. A mathematical model is also developed to study the effect of pressure head on mass flow rate fluctuation in rolling motion. The fluctuation amplitude of the mass flow rate decreases rapidly with a higher pressure head. Comparing with the vertical condition, rolling motion nearly has no effects on

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

    International Nuclear Information System (INIS)

    Yoneda, Kimitoshi; Inada, Fumio

    2004-01-01

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

  7. Will the supply meet the demand? The future of the natural gas liquids market in the WCSB

    International Nuclear Information System (INIS)

    Stauft, T.

    2004-01-01

    Natural Gas Liquids (NGL) price influences were reviewed in this presentation, as well as issues concerning North American propane demand and waterborne imports. A review of U.S. propane stocks was provided as well as regional temperature outlooks for 2004-2005. A cracking feedstock parity forecast was presented, as well as United States gross gas plant margins and propane prices to July 2005. Canadian propane inventories and prices were reviewed. A propane supply and demand forecast to 2020 was presented. Alberta's natural gas supply and intra-Alberta oil sand gas demand growth were discussed. Various market uncertainties include higher levels of activity; the potential of petroleum prices falling due to a reduction of geopolitical risk; the possibility of a U.S. recession; and the growth of Alberta's oil sands industry, with resulting demand for natural gas. It was concluded that the NGL market in North America will continue to be balanced, with waterborne imports becoming more critical. It was suggested that inventories are adequate for the expected winter season. It was also suggested that Canadian NGL supplies are expected to decline, and that prices are expected to soften in the spring of 2005, with falling natural gas and crude oil prices. refs., tabs., figs

  8. The effect of microbubbles on gas-liquid mass transfer coefficient and degradation rate of COD in wastewater treatment.

    Science.gov (United States)

    Yao, Kangning; Chi, Yong; Wang, Fei; Yan, Jianhua; Ni, Mingjiang; Cen, Kefa

    2016-01-01

    A commonly used aeration device at present has the disadvantages of low mass transfer rate because the generated bubbles are several millimeters in diameter which are much bigger than microbubbles. Therefore, the effect of a microbubble on gas-liquid mass transfer and wastewater treatment process was investigated. To evaluate the effect of each bubble type, the volumetric mass transfer coefficients for microbubbles and conventional bubbles were determined. The volumetric mass transfer coefficient was 0.02905 s(-1) and 0.02191 s(-1) at a gas flow rate of 0.67 L min(-1) in tap water for microbubbles and conventional bubbles, respectively. The degradation rate of simulated municipal wastewater was also investigated, using aerobic activated sludge and ozone. Compared with the conventional bubble generator, the chemical oxygen demand (COD) removal rate was 2.04, 5.9, 3.26 times higher than those of the conventional bubble contactor at the same initial COD concentration of COD 200 mg L(-1), 400 mg L(-1), and 600 mg L(-1), while aerobic activated sludge was used. For the ozonation process, the rate of COD removal using microbubble generator was 2.38, 2.51, 2.89 times of those of the conventional bubble generator. Based on the results, the effect of initial COD concentration on the specific COD degradation rate were discussed in different systems. Thus, the results revealed that microbubbles could enhance mass transfer in wastewater treatment and be an effective method to improve the degradation of wastewater.

  9. 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)

  10. Investigations of the Gas-Liquid Multiphase System Involving Macro-Instability in a Baffled Stirred Tank Reactor

    Directory of Open Access Journals (Sweden)

    Shuo Zhang

    2016-01-01

    Full Text Available Bubble Sauter Mean Diameter (SMD in gas-liquid multiphase system is of particular interest and the quantification of gas characteristics is still a challenge today. In this contribution, multiphase Computational Fluid Dynamic (CFD simulations are combined with Population Balance Model (PBM to investigate the bubble SMD in baffled stirred tank reactor (STR. Hereby, special attention is given to the phenomenon known as the fluid macro-instability (MI, which is a large-scale low-frequency fluid velocity variation in baffled STRs, since the fluid MIs have a dominating influence on the bubble breakage and coalescence processes. The simulations, regarding the fluid velocity, are validated with Laser Doppler Anemometry (LDA experiments, in which the instant radial velocity is analyzed through Fast Fourier Transform (FFT spectrum. The frequency peaks of the fluid MIs are found both in the simulation and in the experiment with a high degree of accuracy. After the validation, quantitative predictions of overall bubble SMD with and without MIs are carried out. Due to the accurate prediction of the fluid field, the influence of the fluid MI to bubble SMD is presented. This result provides more adequate information for engineers working in the field of estimating bubble SMDs in baffled STRs.

  11. Design and Development of Gas-Liquid Cylindrical Cyclone Compact Separators for Three-Phase Flow; SEMIANNUAL

    International Nuclear Information System (INIS)

    Mohan, Ram S.; Shoham, Ovadia

    1999-01-01

    The objective of this five-year project (October, 1997-September, 2002) is to expand the current research activities of Tulsa University Separation Technology Projects (TUSTP) to multiphase oil/water/gas separation. This project will be executed in two phases. Phase I (1997-2000) will focus on the investigations of the complex multiphase hydrodynamic flow behavior in a three-phase Gas-Liquid Cylindrical Cyclone (GLCC) Separator. The activities of this phase will include the development of a mechanistic model, a computational fluid dynamics (CFD) simulator, and detailed experimentation on the three-phase GLCC. The experimental and CFD simulation results will be suitably integrated with the mechanistic model. In Phase II (2000-2002), the developed GLCC separator will be tested under high pressure and real crudes conditions. This is crucial for validating the GLCC design for field application and facilitating easy and rapid technology deployment. Design criteria for industrial applications will be developed based on these results and will be incorporated into the mechanistic model by TUSTP

  12. Gas-liquid mass transfer and flow phenomena in the Peirce-Smith converter: a water model study

    Science.gov (United States)

    Zhao, Xing; Zhao, Hong-liang; Zhang, Li-feng; Yang, Li-qiang

    2018-01-01

    A water model with a geometric similarity ratio of 1:5 was developed to investigate the gas-liquid mass transfer and flow characteristics in a Peirce-Smith converter. A gas mixture of CO2 and Ar was injected into a NaOH solution bath. The flow field, volumetric mass transfer coefficient per unit volume ( Ak/V; where A is the contact area between phases, V is the volume, and k is the mass transfer coefficient), and gas utilization ratio ( η) were then measured at different gas flow rates and blow angles. The results showed that the flow field could be divided into five regions, i.e., injection, strong loop, weak loop, splashing, and dead zone. Whereas the Ak/V of the bath increased and then decreased with increasing gas flow rate, and η steadily increased. When the converter was rotated clockwise, both Ak/V and η increased. However, the flow condition deteriorated when the gas flow rate and blow angle were drastically increased. Therefore, these parameters must be controlled to optimal conditions. In the proposed model, the optimal gas flow rate and blow angle were 7.5 m3·h-1 and 10°, respectively.

  13. Visualization and measurement of gas-liquid metal two-phase flow with large density difference using thermal neutrons as microscopic probes

    International Nuclear Information System (INIS)

    Saito, Y.; Hibiki, T.; Mishima, K.; Nishihara, H.; Yamamoto, A.; Kanda, K.; Tobita, Y.; Konishi, K.; Matsubayashi, M.

    1998-01-01

    In a core melt accident of a fast breeder reactor there is a possibility of boiling of fuel-steel mixture in the containment pool. In relation to safety evaluation on severe accident, it is indispensable to evaluate the recriticality of melted core. Gas-liquid two-phase flow with a large density difference is formed due to the boiling of fuel-steel mixture. Although the large density difference may affect the basic characteristics of two-phase flow, little work has been performed so far on two-phase flow with large density difference has not been performed well. In this study, visualization and void fraction measurement of gas-liquid metal two-phase flow were performed by using neutron radiography. The effect of the large density difference between gas and liquid phases on the basic flow characteristics of two-phase flow was clarified. (author)

  14. A method for identifying gas-liquid two-phase flow patterns on the basis of wavelet packet multi-scale information entropy and HMM

    International Nuclear Information System (INIS)

    Zhou Yunlong; Zhang Xueqing; Gao Yunpeng; Cheng Yue

    2009-01-01

    For studying flow regimes of gas/liquid two-phase in a vertical upward pipe, the conductance fluctuation information of four typical flow regimes was collected by a measuring the system with self-made multiple conductivity probes. Owing to the non-stationarity of conductance fluctuation signals of gas-liquid two-phase flow, a kind of' flow regime identification method based on wavelet packet Multi-scale Information Entropy and Hidden Markov Model (HMM) was put forward. First of all, the collected conductance fluctuation signals were decomposed into eight different frequency bands signals. Secondly, the wavelet packet multi-scale information entropy of different frequency bands signals were regarded as the input characteristic vectors of all states HMM which had been trained. In the end the regime identification of' the gas-liquid two-phase flow could be performed. The study showed that the method that HMM was applied to identify the flow regime was superior to the one that BP neural network was used, and the results proved that the method was efficient and feasible. (authors)

  15. Low Cost Chemical Feedstocks Using an Improved and Energy Efficient Natural Gas Liquid (NGL) Removal Process, Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Howard, S.; Lu, Yingzhong

    2012-08-10

    The overall objective of this project is to develop a new low-cost and energy efficient Natural Gas Liquid (NGL) recovery process - through a combination of theoretical, bench-scale and pilot-scale testing - so that it could be offered to the natural gas industry for commercialization. The new process, known as the IROA process, is based on U.S. patent No. 6,553,784, which if commercialized, has the potential of achieving substantial energy savings compared to currently used cryogenic technology. When successfully developed, this technology will benefit the petrochemical industry, which uses NGL as feedstocks, and will also benefit other chemical industries that utilize gas-liquid separation and distillation under similar operating conditions. Specific goals and objectives of the overall program include: (i) collecting relevant physical property and Vapor Liquid Equilibrium (VLE) data for the design and evaluation of the new technology, (ii) solving critical R&D issues including the identification of suitable dehydration and NGL absorbing solvents, inhibiting corrosion, and specifying proper packing structure and materials, (iii) designing, construction and operation of bench and pilot-scale units to verify design performance, (iv) computer simulation of the process using commercial software simulation platforms such as Aspen-Plus and HYSYS, and (v) preparation of a commercialization plan and identification of industrial partners that are interested in utilizing the new technology. NGL is a collective term for C2+ hydrocarbons present in the natural gas. Historically, the commercial value of the separated NGL components has been greater than the thermal value of these liquids in the gas. The revenue derived from extracting NGLs is crucial to ensuring the overall profitability of the domestic natural gas production industry and therefore of ensuring a secure and reliable supply in the 48 contiguous states. However, rising natural gas prices have dramatically reduced

  16. Short-term outlook for natural gas and natural gas liquids to 2006 : an energy market assessment

    International Nuclear Information System (INIS)

    2005-10-01

    In recent years, natural gas markets in North America have seen a close balance between supply and demand, resulting in high and volatile natural gas prices. The National Energy Board monitors the supply of all energy commodities in Canada along with the demand for Canadian energy commodities in domestic and export markets. This is the NEB's first energy market assessment report that presents a combined short-term analysis and outlook of natural gas and natural gas liquids (NGLs), such as ethane, propane and butane. It provides comprehensive information on the complexity of natural gas and NGL industries and highlights recent developments and topical issues. As a major producer of natural gas, western Canada has a correspondingly large natural gas processing capability that was developed specifically to extract NGLs. A world-scale petrochemical industry was developed in Alberta to convert NGLs into even higher valued products such as ethylene. Since NGLs in Canada are sourced mostly from natural gas, changes to the supply and demand for natural gas would impact NGL supply. This report addressed the issue of commodity prices with reference to crude oil, natural gas and NGL prices. Natural gas supply in terms of North American production and natural gas from coal (NGC) was also reviewed along with natural gas demand for residential and commercial heating, industrial use, power generation, and enhanced recovery for oil sand operations. There are about 692 gas plants in Canada that process raw natural gas into marketable gas and NGLs. Most are small field plants that process raw natural gas production to remove impurities such as sulphur, water and other contaminants. This report also discussed this infrastructure, with reference to field plants, straddle plants, pipelines, distribution and storage, including underground NGL storage. 3 tabs., 27 figs., 5 appendices

  17. [Research on diagnosis of gas-liquid detonation exhaust based on double optical path absortion spectroscopy technique].

    Science.gov (United States)

    Lü, Xiao-Jing; Li, Ning; Weng, Chun-Sheng

    2014-03-01

    The effect detection of detonation exhaust can provide measurement data for exploring the formation mechanism of detonation, the promotion of detonation efficiency and the reduction of fuel waste. Based on tunable diode laser absorption spectroscopy technique combined with double optical path cross-correlation algorithm, the article raises the diagnosis method to realize the on-line testing of detonation exhaust velocity, temperature and H2O gas concentration. The double optical path testing system is designed and set up for the valveless pulse detonation engine with the diameter of 80 mm. By scanning H2O absorption lines of 1343nm with a high frequency of 50 kHz, the on-line detection of gas-liquid pulse detonation exhaust is realized. The results show that the optical testing system based on tunable diode laser absorption spectroscopy technique can capture the detailed characteristics of pulse detonation exhaust in the transient process of detonation. The duration of single detonation is 85 ms under laboratory conditions, among which supersonic injection time is 5.7 ms and subsonic injection time is 19.3 ms. The valveless pulse detonation engine used can work under frequency of 11 Hz. The velocity of detonation overflowing the detonation tube is 1,172 m x s(-1), the maximum temperature of detonation exhaust near the nozzle is 2 412 K. There is a transitory platform in the velocity curve as well as the temperature curve. H2O gas concentration changes between 0-7% during detonation under experimental conditions. The research can provide measurement data for the detonation process diagnosis and analysis, which is of significance to advance the detonation mechanism research and promote the research of pulse detonation engine control technology.

  18. Development of a gas-liquid chromatographic method for the analysis of fatty acid tryptamides in cocoa products.

    Science.gov (United States)

    Hug, Bernadette; Golay, Pierre-Alain; Giuffrida, Francesca; Dionisi, Fabiola; Destaillats, Frédéric

    2006-05-03

    The determination of the occurrence and level of cocoa shells in cocoa products and chocolate is an important analytical issue. The recent European Union directive on cocoa and chocolate products (2000/36/EC) has not retained the former limit of a maximum amount of 5% of cocoa shells in cocoa nibs (based on fat-free dry matter), previously authorized for the elaboration of cocoa products such as cocoa mass. In the present study, we report a reliable gas-liquid chromatography procedure suitable for the determination of the occurrence of cocoa shells in cocoa products by detection of fatty acid tryptamides (FATs). The precision of the method was evaluated by analyzing nine different samples (cocoa liquors with different ranges of shells) six times (replicate repeatability). The variations of the robust coefficient of variation of the repeatability demonstrated that FAT(C22), FAT(C24), and total FATs are good markers for the detection of shells in cocoa products. The trueness of the method was evaluated by determining the FAT content in two spiked matrices (cocoa liquors and cocoa shells) at different levels (from 1 to 50 mg/100 g). A good relation was found between the results obtained and the spiking (recovery varied between 90 and 130%), and the linearity range was established between 1 and 50 mg/100 g in cocoa products. For total FAT contents of cocoa liquor containing 5% shells, the measurement uncertainty allows us to conclude that FAT is equal to 4.01 +/- 0.8 mg/100 g. This validated method is perfectly suitable to determine shell contents in cocoa products using FAT(C22), FAT(C24), and total FATs as markers. The results also confirmed that cocoa shells contain FAT(C24) and FAT(C22) in a constant ratio of nearly 2:1.

  19. Power Based Phase-Locked Loop Under Adverse Conditions with Moving Average Filter for Single-Phase System

    OpenAIRE

    Menxi Xie; CanYan Zhu; BingWei Shi; Yong Yang

    2017-01-01

    High performance synchronization methord is citical for grid connected power converter. For single-phase system, power based phase-locked loop(pPLL) uses a multiplier as phase detector(PD). As single-phase grid voltage is distorted, the phase error information contains ac disturbances oscillating at integer multiples of fundamental frequency which lead to detection error. This paper presents a new scheme based on moving average filter(MAF) applied in-loop of pPLL. The signal characteristic of...

  20. Reliability-Oriented Design and Analysis of Input Capacitors in Single-Phase Transformer-less Photovoltaic Inverters

    DEFF Research Database (Denmark)

    Wang, Huai; Yang, Yongheng; Blaabjerg, Frede

    2013-01-01

    . A reliability-oriented design guideline is proposed in this paper for the input capacitors in single-phase transformer-less PV inverters. The guideline ensures that the service time requirement is to be accomplished under different power levels and ambient temperature profiles. The theoretical analysis has been......While 99% efficiency has been reported, the target of 20 years of service time imposes new challenge to cost-effective solutions for grid-connected photovoltaic (PV) inverters. Aluminum electrolytic capacitors are the weak-link in terms of reliability and lifetime in single-phase PV systems...

  1. Thermal Optimized Operation of the Single-Phase Full-Bridge PV Inverter under Low Voltage Ride-Through Mode

    DEFF Research Database (Denmark)

    Wang, Huai; Yang, Yongheng; Blaabjerg, Frede

    2013-01-01

    . At the same time, the target of a long service time (25 years or more) imposes new challenges to grid-connected transformer-less PV systems. Achieving more reliable PV inverters is of intense interest in recent research. As one of the most critical stresses that induce failures, the thermal stresses...... on the power devices of a single-phase full-bridge PV inverter are analyzed in different operational modes in this paper. The low voltage grid condition is specially taken into account in this paper. The analysis is demonstrated by a 3 kW single-phase full-bridge grid-connected PV system by simulations...

  2. Lifetime Estimation of DC-link Capacitors in a Single-phase Converter with an Integrated Active Power Decoupling Module

    DEFF Research Database (Denmark)

    Ma, Siyuan; Wang, Haoran; Tang, Junchaojie

    2016-01-01

    In single-phase inverters, DC-link capacitors are installed at the DC-link to buffer the ripple power between the AC side and DC side. Active decoupling methods introduce additional circuits at the DC side or AC side to partially or fully supply the ripple power. So that the demanded DC-link capa......In single-phase inverters, DC-link capacitors are installed at the DC-link to buffer the ripple power between the AC side and DC side. Active decoupling methods introduce additional circuits at the DC side or AC side to partially or fully supply the ripple power. So that the demanded DC...

  3. Natural Gas Liquid Pipelines

    Data.gov (United States)

    Department of Homeland Security — Natural gas interstate and intrastate pipelines in the United States. Based on a variety of sources with varying scales and levels of accuracy and therefore accuracy...

  4. Design of single phase inverter using microcontroller assisted by data processing applications software

    Science.gov (United States)

    Ismail, K.; Muharam, A.; Amin; Widodo Budi, S.

    2015-12-01

    Inverter is widely used for industrial, office, and residential purposes. Inverter supports the development of alternative energy such as solar cells, wind turbines and fuel cells by converting dc voltage to ac voltage. Inverter has been made with a variety of hardware and software combinations, such as the use of pure analog circuit and various types of microcontroller as controller. When using pure analog circuit, modification would be difficult because it will change the entire hardware components. In inverter with microcontroller based design (with software), calculations to generate AC modulation is done in the microcontroller. This increases programming complexity and amount of coding downloaded to the microcontroller chip (capacity flash memory in the microcontroller is limited). This paper discusses the design of a single phase inverter using unipolar modulation of sine wave and triangular wave, which is done outside the microcontroller using data processing software application (Microsoft Excel), result shows that complexity programming was reduce and resolution sampling data is very influence to THD. Resolution sampling must taking ½ A degree to get best THD (15.8%).

  5. Synthesis of single phase of CuTl-1234 thin films

    CERN Document Server

    Khan, N A; Ishida, K; Tateai, F; Kojima, T; Terada, N; Ihara, H

    1999-01-01

    Thin films of CuTl-1234 superconductor have been prepared for the first time using an amorphous phase epitaxy method (APE). In this method, an amorphous phase is sputtered from a target of stoichiometric composition CuBa/sub 2/Ca/sub 3/Cu/sub 4/O/sub x/. Thin films on the SrTiO/sub 3/ substrate after the thallium treatment are biaxially oriented. The XRD reflected a predominant single phase with c-axis 18.7 AA and pole figure measurements of (103) reflections showed a-axis oriented films with Delta phi =0.8 degrees . Resistivity measurements showed T/sub c/=113 K and preliminary J/sub c/ measurements manifested a current density of 1.0*10/sup 6/ A/cm (77 K, 0 T). The composition of films after EDX measurements is Cu /sub 0.3/Tl/sub 0.7/CuBa/sub 2/Ca/sub 3/Cu/sub 4/O/sub 12-y/. (8 refs).

  6. Single-phased Fault Location on Transmission Lines Using Unsynchronized Voltages

    Directory of Open Access Journals (Sweden)

    ISTRATE, M.

    2009-10-01

    Full Text Available The increased accuracy into the fault's detection and location makes it easier for maintenance, this being the reason to develop new possibilities for a precise estimation of the fault location. In the field literature, many methods for fault location using voltages and currents measurements at one or both terminals of power grids' lines are presented. The double-end synchronized data algorithms are very precise, but the current transformers can limit the accuracy of these estimations. The paper presents an algorithm to estimate the location of the single-phased faults which uses only voltage measurements at both terminals of the transmission lines by eliminating the error due to current transformers and without introducing the restriction of perfect data synchronization. In such conditions, the algorithm can be used with the actual equipment of the most power grids, the installation of phasor measurement units with GPS system synchronized timer not being compulsory. Only the positive sequence of line parameters and sources are used, thus, eliminating the incertitude in zero sequence parameter estimation. The algorithm is tested using the results of EMTP-ATP simulations, after the validation of the ATP models on the basis of registered results in a real power grid.

  7. A single-phase model for liquid-feed DMFCs with non-Tafel kinetics

    Science.gov (United States)

    Vera, Marcos

    An isothermal single-phase 3D/1D model for liquid-feed direct methanol fuel cells (DMFC) is presented. Three-dimensional (3D) mass, momentum and species transport in the anode channels and gas diffusion layer is modeled using a commercial, finite-volume based, computational fluid dynamics (CFD) software complemented with user supplied subroutines. The 3D model is locally coupled to a one-dimensional (1D) model accounting for the electrochemical reactions in both the anode and the cathode, which provides a physically sound boundary condition for the velocity and methanol concentration fields at the anode gas diffusion layer/catalyst interface. The 1D model - comprising the membrane-electrode assembly, cathode gas diffusion layer, and cathode channel - assumes non-Tafel kinetics to describe the complex kinetics of the multi-step methanol oxidation reaction at the anode, and accounts for the mixed potential associated with methanol crossover, induced both by diffusion and electro-osmotic drag. Polarization curves computed for various methanol feed concentrations, temperatures, and methanol feed velocities show good agreement with recent experimental results. The spatial distribution of methanol in the anode channels, together with the distributions of current density, methanol crossover and fuel utilization at the anode catalyst layer, are also presented for different opperating conditions.

  8. Benchmarking of Constant Power Generation Strategies for Single-Phase Grid-Connected Photovoltaic Systems

    DEFF Research Database (Denmark)

    Sangwongwanich, Ariya; Yang, Yongheng; Blaabjerg, Frede

    2016-01-01

    With a still increase of grid-connected Photovoltaic (PV) systems, challenges have been imposed on the grid due to the continuous injection of a large amount of fluctuating PV power, like overloading the grid infrastructure (e.g., transformers) during peak power production periods. Hence, advanced...... strategies based on: 1) a power control (P-CPG), 2) a current limit method (I-CPG) and 3) the Perturb and Observe algorithm (P&O-CPG). However, the operational mode changes (e.g., from the maximum power point tracking to a CPG operation) will affect the entire system performance. Thus, a benchmarking...... of the proposed CPG strategies is also conducted on a 3-kW single-phase grid-connected PV system. Comparisons reveal that either the P-CPG or I-CPG strategies can achieve fast dynamics and satisfactory steady-state performance. In contrast, the P&OCPG algorithm is the most suitable solution in terms of high...

  9. Benchmarking of Constant Power Generation Strategies for Single-Phase Grid-Connected Photovoltaic Systems

    DEFF Research Database (Denmark)

    Sangwongwanich, Ariya; Yang, Yongheng; Blaabjerg, Frede

    2018-01-01

    With a still increase of grid-connected Photovoltaic (PV) systems, challenges have been imposed on the grid due to the continuous injection of a large amount of fluctuating PV power, like overloading the grid infrastructure (e.g., transformers) during peak power production periods. Hence, advanced...... strategies based on: 1) a power control method (P-CPG), 2) a current limit method (I-CPG) and 3) the Perturb and Observe algorithm (P&O-CPG). However, the operational mode changes (e.g., from the maximum power point tracking to a CPG operation) will affect the entire system performance. Thus, a benchmarking...... of the presented CPG strategies is also conducted on a 3-kW single-phase grid-connected PV system. Comparisons reveal that either the P-CPG or I-CPG strategies can achieve fast dynamics and satisfactory steady-state performance. In contrast, the P&O-CPG algorithm is the most suitable solution in terms of high...

  10. ASSERT validation against the Stern Laboratories' single-phase pressure drop tests

    International Nuclear Information System (INIS)

    Waddington, G.M.; Kiteley, J.C.; Carver, M.B.

    1995-01-01

    This paper describes the preliminary validation of ASSERT-IV against the single-phase pressure drop tests from the 37-element CHF (critical heat flux) experiments conducted at Stern Laboratories, and shows how this study fits into the overall ASSERT validation plan. The effects on the pressure drop of several friction and form loss models are evaluated, including the geometry-based K-factor model. The choice of friction factor has a small effect on the predicted channel pressure drop, compared to the form loss model choice. Using the uniform K-factors of Hameed, the computed pressure drops are in excellent agreement with the experimental results from the nominal pressure tube tests. For future ASSERT applications, either Hameed's uniform K-factors or the geometry-based model using Idelchik's thick-edged orifice equation are recommended, as are the friction factor correlations of Colebrook-White, Selander, and Aly and Groeneveld. More analysis of the geometry-based K-factor model is required. (author). 23 refs., 4 tabs., 9 figs

  11. Adaptive Hysteresis Band Current Control for Transformerless Single-Phase PV Inverters

    DEFF Research Database (Denmark)

    Vázquez, Gerardo; Rodriguez, Pedro; Ordoñez, Rafael

    2009-01-01

    Current control based on hysteresis algorithms are widely used in different applications, such as motion control, active filtering or active/reactive power delivery control in distributed generation systems. The hysteresis current control provides to the system a fast and robust dynamic response,...... different single-phase PV inverter topologies, by means of simulations performed with PSIM. In addition, the behavior of the thermal losses when using each control structure in such converters has been studied as well.......Current control based on hysteresis algorithms are widely used in different applications, such as motion control, active filtering or active/reactive power delivery control in distributed generation systems. The hysteresis current control provides to the system a fast and robust dynamic response......, and requires a simple implementation in standard digital signal platforms. On the other hand, the main drawback of classical hysteresis current control lies in the fact that the switching frequency is variable, as the hysteresis band is fixed. In this paper a variable band hysteresis control algorithm...

  12. Green synthesis of isopropyl myristate in novel single phase medium Part I: Batch optimization studies

    Directory of Open Access Journals (Sweden)

    Rajeshkumar N. Vadgama

    2015-12-01

    Full Text Available Isopropyl myristate finds many applications in food, cosmetic and pharmaceutical industries as an emollient, thickening agent, or lubricant. Using a homogeneous reaction phase, non-specific lipase derived from Candida antartica, marketed as Novozym 435, was determined to be most suitable for the enzymatic synthesis of isopropyl myristate. The high molar ratio of alcohol to acid creates novel single phase medium which overcomes mass transfer effects and facilitates downstream processing. The effect of various reaction parameters was optimized to obtain a high yield of isopropyl myristate. Effect of temperature, agitation speed, organic solvent, biocatalyst loading and batch operational stability of the enzyme was systematically studied. The conversion of 87.65% was obtained when the molar ratio of isopropyl alcohol to myristic acid (15:1 was used with 4% (w/w catalyst loading and agitation speed of 150 rpm at 60 °C. The enzyme has also shown good batch operational stability under optimized conditions.

  13. POWER FACTOR CORRECTION IN PERMANENT MAGNET BRUSHLESS DC MOTOR DRIVE USING SINGLE-PHASE CUK CONVERTER

    Directory of Open Access Journals (Sweden)

    SANJEEV SINGH

    2010-12-01

    Full Text Available Permanent magnet brushless DC motor (PMBLDCM drives are being employed in many variable speed applications due to their high efficiency, silent operation, compact size, high reliability, ease of control, and low maintenance requirements. These drives have power quality problems and poor power factor at input AC mains as they are mostly fed through diode bridge rectifier based voltage source inverters. To overcome such problems a single-phase single-switch power factor correction AC-DC converter topology based on a Cuk converter is proposed to feed voltage source inverters based PMBLDCM. It focuses on the analysis, design and performance evaluation of the proposed PFC converter topology for a 1.5 kW, 1500 rpm, 400 V PMBLDCM drive used for an air-conditioning system. The proposed PFC converter topology is modelled and its performance is simulated in Matlab-Simulink environment and results show an improved power quality and good power factor in wide speed range of the drive.

  14. Modified Dual Three-Pulse Modulation technique for single-phase inverter topology

    Science.gov (United States)

    Sree Harsha, N. R.; Anitha, G. S.; Sreedevi, A.

    2016-01-01

    In a recent paper, a new modulation technique called Dual Three Pulse Modulation (DTPM) was proposed to improve the efficiency of the power converters of the Electric/Hybrid/Fuel-cell vehicles. It was simulated in PSIM 9.0.4 and uses analog multiplexers to generate the modulating signals for the DC/DC converter and inverter. The circuit used is complex and many other simulation softwares do not support the analog multiplexers as well. Also, the DTPM technique produces modulating signals for the converter, which are essentially needed to produce the modulating signals for the inverter. Hence, it cannot be used efficiently to switch the valves of a stand-alone inverter. We propose a new method to generate the modulating signals to switch MOSFETs of a single phase Dual-Three pulse Modulation based stand-alone inverter. The circuits proposed are simulated in Multisim 12.0. We also show an alternate way to switch a DC/DC converter in a way depicted by DTPM technique both in simulation (MATLAB/Simulink) and hardware. The circuitry is relatively simple and can be used for the further investigations of DTPM technique.

  15. Single Scattering Detection in Turbin Media Using Single-Phase Structured Illumination Filtering

    Science.gov (United States)

    Berrocal, E.; Johnsson, J.; Kristensson, E.; Alden, M.

    2012-05-01

    This work shows a unique possibility of visualizing the exponential intensity decay due to light extinction, when laser adiation propagates through a homogeneous scattering edium. This observation implies that the extracted intensity mostly riginates from single scattering events. The filtering of this single light scattering intensity is performed by means of a single-phase structured illumination filtering approach. Results from numerical Monte Carlo simulation confirm the experimental findings for an extinction coefficient of μ_e = 0.36 mm^-1. This article demonstrates an original and reliable way of measuring the extinction coefficient of particulate turbid media based on sidescattering imaging. Such an approach has capabilities to replace the commonly used transmission measurement within the intermediate single-to multiple scattering regime where the optical depth ranges between 1 procedure and set-up. Applications of the technique has potential in probing challenging homogeneous scattering media, such as biomedical tissues, turbid emulsions, etc, in situations where dilution cannot be applied and where conventional transmission measurements fail.

  16. Low-temperature synthesis of single-phase Co7Sb2O12

    International Nuclear Information System (INIS)

    Brito, M.S.L.; Escote, M.T.; Santos, C.O.P.; Lisboa-Filho, P.N.; Leite, E.R.; Oliveira, J.B.L.; Gama, L.; Longo, E.

    2004-01-01

    Polycrystalline Co 7 Sb 2 O 12 compounds have been synthesized by a chemical route, which is based on a modified polymeric precursor method. In order to study the physical properties of the samples, X-ray diffraction (XRD), thermal analyses (TG and DSC), infrared spectroscopy (IR), specific surface area (BET), and magnetization measurements were performed on these materials. Characterization through XRD revealed that the samples are single-phase after a heat-treatment at 1100 deg. C for 2 h, while the X-ray patterns of the samples heat-treated at lower temperatures revealed the presence of additional Bragg reflections belonging to the Co 6 Sb 2 O 6 phase. These data were analyzed by means of Rietveld refinement and further analyze showed that Co 7 Sb 2 O 12 displays an inverse spinel crystalline structure. In this structure, the Co 2+ ions occupy the eight tetrahedral positions, and the sixteen octahedral positions are randomly occupied by the Sb 5+ and Co 2+ ions. IR studies disclosed two strong absorption bands, ν 1 and ν 2 , in the expected spectral range for a spinel-type binary oxide with space group Fd3m. Exploratory studies concerning the magnetic properties indicated that this sample presents a spin-glass transition at T f ∼ 64 K

  17. Anaerobic co-digestion of food waste and landfill leachate in single-phase batch reactors

    International Nuclear Information System (INIS)

    Liao, Xiaofeng; Zhu, Shuangyan; Zhong, Delai; Zhu, Jingping; Liao, Li

    2014-01-01

    Highlights: • Anaerobic co-digestion strategy for food waste treatment at OLR 41.8 g VS/L. • A certain amount of raw leachate effectively relieved acidic inhibition. • The study showed that food waste was completely degraded. - Abstract: In order to investigate the effect of raw leachate on anaerobic digestion of food waste, co-digestions of food waste with raw leachate were carried out. A series of single-phase batch mesophilic (35 ± 1 °C) anaerobic digestions were performed at a food waste concentration of 41.8 g VS/L. The results showed that inhibition of biogas production by volatile fatty acids (VFA) occurred without raw leachate addition. A certain amount of raw leachate in the reactors effectively relieved acidic inhibition caused by VFA accumulation, and the system maintained stable with methane yield of 369–466 mL/g VS. Total ammonia nitrogen introduced into the digestion systems with initial 2000–3000 mgNH 4 –N/L not only replenished nitrogen for bacterial growth, but also formed a buffer system with VFA to maintain a delicate biochemical balance between the acidogenic and methanogenic microorganisms. UV spectroscopy and fluorescence excitation–emission matrix spectroscopy data showed that food waste was completely degraded. We concluded that using raw leachate for supplement water addition and pH modifier on anaerobic digestion of food waste was effective. An appropriate fraction of leachate could stimulate methanogenic activity and enhance biogas production

  18. Cost Optimal Design of a Single-Phase Dry Power Transformer

    Directory of Open Access Journals (Sweden)

    Raju Basak

    2015-08-01

    Full Text Available The Dry type transformers are preferred to their oil-immersed counterparts for various reasons, particularly because their operation is hazardless. The application of dry transformers was limited to small ratings in the earlier days. But now these are being used for considerably higher ratings.  Therefore, their cost-optimal design has gained importance. This paper deals with the design procedure for achieving cost optimal design of a dry type single-phase power transformer of small rating, subject to usual design constraints on efficiency and voltage regulation. The selling cost for the transformer has been taken as the objective function. Only two key variables have been chosen, the turns/volt and the height: width ratio of window, which affects the cost function to high degrees. Other variables have been chosen on the basis of designers’ experience. Copper has been used as conductor material and CRGOS as core material to achieve higher efficiency, lower running cost and compact design. The electrical and magnetic loadings have been kept at their maximum values without violating the design constraints. The optimal solution has been obtained by the method of exhaustive search using nested loops.

  19. A single-phase embedded Z-source DC-AC inverter.

    Science.gov (United States)

    Kim, Se-Jin; Lim, Young-Cheol

    2014-01-01

    In the conventional DC-AC inverter consisting of two DC-DC converters with unipolar output capacitors, the output capacitor voltages of the DC-DC converters must be higher than the DC input voltage. To overcome this weakness, this paper proposes a single-phase DC-AC inverter consisting of two embedded Z-source converters with bipolar output capacitors. The proposed inverter is composed of two embedded Z-source converters with a common DC source and output AC load. Though the output capacitor voltages of the converters are relatively low compared to those of a conventional inverter, an equivalent level of AC output voltages can be obtained. Moreover, by controlling the output capacitor voltages asymmetrically, the AC output voltage of the proposed inverter can be higher than the DC input voltage. To verify the validity of the proposed inverter, experiments were performed with a DC source voltage of 38 V. By controlling the output capacitor voltages of the converters symmetrically or asymmetrically, the proposed inverter can produce sinusoidal AC output voltages. The experiments show that efficiencies of up to 95% and 97% can be achieved with the proposed inverter using symmetric and asymmetric control, respectively.

  20. Single-phase and two phase bubbly flow in a T connection: theoretical and experimental study

    International Nuclear Information System (INIS)

    Hervieu, Eric

    1988-01-01

    The objective of this research thesis is to highlight the driving factors of the separation of phases of a bubbly flow in a T junction, and to develop a prediction model. In a first part, the author reports the rigorous formulation of equations averaged on the T volume. He shows that it's not possible to solve globally the problem with these equations. Then, he reports a bibliographical study on the modelling of a bubbly flow, and, based upon this study, highlights intrinsic characteristics of the flow, and explains its dynamic mechanisms. He reports the development of the theoretical model, and describes the experimental installation used to validate it. In the third part, he reports the study of the liquid-gas interaction, and presents the adopted approach: study of the behaviour of an isolated bubble within a single-phase flow. Experimentation is used to check theoretical predictions. Results are used to compute phase separation. The obtained results are again compared with experimental results to validate the global relevance of the model [fr

  1. Even distribution/dividing of single-phase fluids by symmetric bifurcation of flow channels

    International Nuclear Information System (INIS)

    Liu, Hong; Li, Peiwen

    2013-01-01

    Highlights: ► We addressed an issue of distributing a flow to a number of flow channels uniformly. ► The flow distribution is accomplished through bifurcation of channels. ► Some key parameters to the flow distribution uniformity have been identified. ► Flow uniformity was studied for several versions of flow distributor designs. ► A novel fluid packaging device of high efficiency was provided. -- Abstract: This study addresses a fundamental issue of distributing a single-phase fluid flow into a number of flow channels uniformly. A basic mechanism of flow distribution is accomplished through bifurcation of channels that symmetrically split one flow channel into two downstream channels. Applying the basic mechanism, cascades flow distributions are designed to split one flow into a large number of downstream flows uniformly. Some key parameters decisive to the flow distribution uniformity in such a system have been identified, and the flow distribution uniformity of air was studied for several versions of flow distributor designs using CFD analysis. The effect of the key parameters of the flow channel designs to the flow distribution uniformity was investigated. As an example of industrial application, a novel fluid packaging device of high efficiency was proposed and some CFD analysis results for the device were provided. The optimized flow distributor makes a very good uniform flow distribution which will significantly improve the efficiency of fluid packaging. The technology is expected to be of great significance to many industrial devices that require high uniformity of flow distribution

  2. A single-phase model for liquid-feed DMFCs with non-Tafel kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Vera, Marcos [Area de Mecanica de Fluidos, Universidad Carlos III de Madrid, Avda. de la Universidad 30, 28911 Leganes (Spain)

    2007-09-27

    An isothermal single-phase 3D/1D model for liquid-feed direct methanol fuel cells (DMFC) is presented. Three-dimensional (3D) mass, momentum and species transport in the anode channels and gas diffusion layer is modeled using a commercial, finite-volume based, computational fluid dynamics (CFD) software complemented with user supplied subroutines. The 3D model is locally coupled to a one-dimensional (1D) model accounting for the electrochemical reactions in both the anode and the cathode, which provides a physically sound boundary condition for the velocity and methanol concentration fields at the anode gas diffusion layer/catalyst interface. The 1D model - comprising the membrane-electrode assembly, cathode gas diffusion layer, and cathode channel - assumes non-Tafel kinetics to describe the complex kinetics of the multi-step methanol oxidation reaction at the anode, and accounts for the mixed potential associated with methanol crossover, induced both by diffusion and electro-osmotic drag. Polarization curves computed for various methanol feed concentrations, temperatures, and methanol feed velocities show good agreement with recent experimental results. The spatial distribution of methanol in the anode channels, together with the distributions of current density, methanol crossover and fuel utilization at the anode catalyst layer, are also presented for different opperating conditions. (author)

  3. Thermodynamic models to predict gas-liquid solubilities in the methanol synthesis, the methanol-higher alcohol synthesis, and the Fischer-Tropsch synthesis via gas-slurry processes

    NARCIS (Netherlands)

    Breman, B.B; Beenackers, A.A C M

    1996-01-01

    Various thermodynamic models were tested concerning their applicability to predict gas-liquid solubilities, relevant for synthesis gas conversion to methanol, higher alcohols, and hydrocarbons via gas-slurry processes. Without any parameter optimization the group contribution equation of state

  4. An Islanding Detection Method by Using Frequency Positive Feedback Based on FLL for Single-Phase Microgrid

    DEFF Research Database (Denmark)

    Sun, Qinfei; Guerrero, Josep M.; Jing, Tianjun

    2017-01-01

    An active islanding detection method based on Frequency-Locked Loop (FLL) for constant power controlled inverter in single-phase microgrid is proposed. This method generates a phase shift comparing the instantaneous frequency obtained from FLL unit with the nominal frequency to modify the reference...

  5. A Single-Phase Transformerless Inverter With Charge Pump Circuit Concept for Grid-Tied PV Applications

    DEFF Research Database (Denmark)

    Ardashir, Jaber Fallah; Sabahi, Mehran; Hosseini, Seyed Hossein

    2017-01-01

    This paper proposes a new single-phase transformerless photovoltaic (PV) inverter for grid-tied PV systems. The topology is derived from the concept of a charge pump circuit in order to eliminate the leakage current. It is composed of four power switches, two diodes, two capacitors, and an LCL ou...

  6. Analysis of phase-locked loop influence on the stability of single-phase grid-connected inverter

    DEFF Research Database (Denmark)

    Zhang, Chong; Wang, Xiongfei; Blaabjerg, Frede

    2015-01-01

    A controlled power inverter can cause instability at the point of common coupling (PCC) with its output filter and the grid. This paper analyzes the influence of the Phase-Locked Loop (PLL) on the output admittance of single-phase current-controlled inverters with different grid stiffness. It shows...

  7. Performance Evaluation of the Single-Phase Split-Source Inverter Using an Alternative DC-AC Configuration

    DEFF Research Database (Denmark)

    Abdelhakim, Ahmed; Mattavelli, Paolo; Davari, Pooya

    2018-01-01

    This paper investigates and evaluates the performance of a single-phase split-source inverter (SSI), where an alternative unidirectional dc-ac configuration is used. Such configuration is utilized in order to use two common-cathode diodes in a single-device instead of using two separate diodes, r...

  8. Research on High Efficient Single-Phase Multi-Stage Interleaved Bridgeless PFC Frontend for Class-D Amplifiers

    DEFF Research Database (Denmark)

    Li, Qingnan; Thomsen, Ole Cornelius; Andersen, Michael A. E.

    2012-01-01

    In this paper, a 3.5kW single-phase high efficient interleaved Bridgeless PFC (IBPFC) is proposed for class-D amplifiers. This topology achieves a relatively higher efficiency in a wide output power range, which helps to reduce the energy consuming of the whole system. In addition, a detailed...

  9. Hybrid I-f starting and observer-based Ssnsorless control of single-phase BLDC-PM motor drives

    DEFF Research Database (Denmark)

    Iepure, Liviu Ioan; Boldea, Ion; Blaabjerg, Frede

    2012-01-01

    A motion sensorless control for single-phase permanent magnet brushless dc motor based on an I-f starting sequence and a real-time permanent magnet flux estimation is proposed here. The special calculation for extracting the position and speed used here implies the generating of an orthogonal flux......-speed blower-motor (40 W, 10 krpm, 12 Vdc)....

  10. A Novel Neural Network Vector Control for Single-Phase Grid-Connected Converters with L, LC and LCL Filters

    Directory of Open Access Journals (Sweden)

    Xingang Fu

    2016-04-01

    Full Text Available This paper investigates a novel recurrent neural network (NN-based vector control approach for single-phase grid-connected converters (GCCs with L (inductor, LC (inductor-capacitor and LCL (inductor-capacitor-inductor filters and provides their comparison study with the conventional standard vector control method. A single neural network controller replaces two current-loop PI controllers, and the NN training approximates the optimal control for the single-phase GCC system. The Levenberg–Marquardt (LM algorithm was used to train the NN controller based on the complete system equations without any decoupling policies. The proposed NN approach can solve the decoupling problem associated with the conventional vector control methods for L, LC and LCL-filter-based single-phase GCCs. Both simulation study and hardware experiments demonstrate that the neural network vector controller shows much more improved performance than that of conventional vector controllers, including faster response speed and lower overshoot. Especially, NN vector control could achieve very good performance using low switch frequency. More importantly, the neural network vector controller is a damping free controller, which is generally required by a conventional vector controller for an LCL-filter-based single-phase grid-connected converter and, therefore, can overcome the inefficiency problem caused by damping policies.

  11. Space Vector Pulse Width Modulation Strategy for Single-Phase Three-Level CIC T-source Inverter

    DEFF Research Database (Denmark)

    Shults, Tatiana E.; Husev, Oleksandr O.; Blaabjerg, Frede

    2016-01-01

    This paper presents a novel space vector pulse-width modulation strategy for a single-phase three-level buck-boost inverter based on an impedance-source network. The case study system is based on T-source inverter with continuous input current. To demonstrate the improved performance of the inver...

  12. Analysis and MPPT control of a wind-driven three-phase induction generator feeding single-phase utility grid

    Directory of Open Access Journals (Sweden)

    Krishnan Arthishri

    2017-05-01

    Full Text Available In this study, a three-phase diode bridge rectifier and a single-phase voltage source inverter topology has been proposed for feeding single-phase utility grid employing a three-phase induction generator fed from wind energy. A self-excited induction generator configuration has been chosen for wide speed operation of wind turbine system, which gives the scope for extracting maximum power available in the wind. In addition to maximum power point tracking (MPPT, the generator can be loaded to its rated capacity for feeding single-phase utility grid using a three-phase induction machine, whereas it is not possible with existing configurations because of the absence of power converters. For the proposed system, MPPT algorithm has been devised by continuously monitoring the grid current and a proportional resonant controller has been employed for grid synchronisation of voltage source inverter with single-phase grid. A MATLAB/Simulink model of the proposed system has been developed to ascertain its successful working by predetermining the overall performance characteristics. The present proposal has also been tested with sag, swell and distortion in the grid voltage. The control strategy has been implemented using field programmable gate array (FPGA controller with modularised programming approach. The efficacy of the system has been demonstrated with the results obtained from an experimental set-up in the laboratory.

  13. Low-Complexity Model Predictive Control of Single-Phase Three-Level Rectifiers with Unbalanced Load

    DEFF Research Database (Denmark)

    Ma, Junpeng; Song, Wensheng; Wang, Xiongfei

    2018-01-01

    The fluctuation of the neutral-point potential in single-phase three-level rectifiers leads to coupling between the line current regulation and dc-link voltage balancing, deteriorating the quality of line current. For addressing this issue, this paper proposes a low-complexity model predictive...

  14. Adjusting output impedance using a PI controller to improve the stability of a single-phase inverter under weak grid

    Directory of Open Access Journals (Sweden)

    Jiao Jiao

    2016-11-01

    Full Text Available Explored in this paper is the grid impedance effect on the stability of a single-phase grid connected inverter with an LC filter based on an analysis of the inverter output impedance. For a single-phase grid connected inverter, a PI controller is often used to regulate the current injected into the grid. However, the control performance can be influenced when the inverter is connected to a weak grid. Also, the utility grid has background harmonic noise, which can make the injected current distorted. Therefore, analysis of the output impedance of a single-phase grid connected inverter is important for the robustness and stability of the system. By modeling the output impedance of inverter, it can be determined that the proportional gain and integral gain of the controller have an effect on the output impedance. Analytical results show that by adjusting the PI controller parameters, the ability for harmonic reduction and stability of the system can be improved. Simulation and experiments using a 1 kW single-phase grid connected inverter verify the effectiveness of the theoretical analysis.

  15. Safe-commutation principle for direct single-phase AC-AC converters for use in audio power amplification

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2004-01-01

    This paper presents an alternative safe commutation principle for a single phase bidirectional bridge, for use in the new generation of direct single-stage AC-AC audio power amplifiers. As compared with the bridge commutation with load current or source voltage sensing, in this approach...

  16. Natural circulation in single-phase and two-phase flow

    International Nuclear Information System (INIS)

    Cheung, F.B.; El-Genk, M.S.

    1989-01-01

    Natural circulation usually arises in a closed loop between a heat source and a heat sink were the fluid motion is driven by density difference. It may also occur in enclosures or cavities where the flow is induced primarily by temperature or concentration gradients within the fluid. The subject has recently received special attention by the heat transfer and nuclear reactor safety communities because of it importance to the areas of energy extraction, decay, heat removal in nuclear reactors, solar and geothermal heating, and cooling of electronic equipment. Although many new results and physical insights have been gained of the various natural circulation phenomena, a number of critical issues remain unresolved. These include, for example, transition from laminar to turbulent flow, buoyancy-induced turbulent flow modeling, change of flow regimes, flow field visualization, variable property effects, and flow instability. This symposium volume contains papers presented in the Natural Circulation in Single-Phase and Two-Phase Flow session at the 1989 Winter Annual Meeting of ASME, by authors from different countries including the United States, Japan, Canada, and Brazil. The papers deal with experimental and theoretical studies as well as state-of-the-art reviews, covering a broad spectrum of topics in natural circulation including: variable-conductance thermosyphons, microelectronic chip cooling, natural circulation in anisotropic porous media and in cavities, heat transfer in flat plat solar collectors, shutdown heat removal in fast reactors, cooling of light-water and heavy-water reactors. The breadth of papers contained in this volume clearly reflect the importance of the current interest in natural circulation as a means for passive cooling and heating

  17. A Single-Phase Multilevel PV Generation System with an Improved Ripple Correlation Control MPPT Algorithm

    Directory of Open Access Journals (Sweden)

    Manel Hammami

    2017-12-01

    Full Text Available The implementation of maximum power point tracking (MPPT schemes by the ripple correlation control (RCC algorithm is presented in this paper. A reference is made to single-phase single-stage multilevel photovoltaic (PV generation systems, when the inverter input variables (PV voltage and PV current have multiple low-frequency (ripple harmonics. The harmonic analysis is carried out with reference to a multilevel configuration consisting of an H-bridge inverter and level doubling network (LDN cell, leading to the multilevel inverter having double the output voltage levels as compared to the basic H-bridge inverter topology (i.e., five levels vs. three levels. The LDN cell is basically a half-bridge fed by a floating capacitor, with self-balancing voltage capability. The multilevel configuration introduces additional PV voltage and current low-frequency harmonics, perturbing the basic implementation of the RCC scheme (based on the second harmonic component, leading to malfunctioning. The proposed RCC algorithm employs the PV current and voltage harmonics at a specific frequency for the estimation of the voltage derivative of power dP/dV (or dI/dV, driving the PV operating point toward the maximum power point (MPP in a faster and more precise manner. The steady-state and transient performances of the proposed RCC-MPPT schemes have been preliminarily tested and compared using MATLAB/Simulink. Results have been verified by experimental tests considering the whole multilevel PV generation system, including real PV modules, multilevel insulated-gate bipolar transistor (IGBT inverters, and utility grids.

  18. ESTABLISHED MODES AND STATIC CHARACTERISTICS OF THREE-PHASE ASYNCHRONOUS MOTOR POWERED WITH SINGLE PHASE NETWORK

    Directory of Open Access Journals (Sweden)

    V. S. Malyar

    2016-01-01

    Full Text Available A mathematical model is developed to study the operation of three-phase asynchronous motor with squirrel-cage rotor when the stator winding is powered from a single phase network. To create a rotating magnetic field one of the phases is fed through the capacitor. Due to the asymmetry of power feed not only transients, but the steady-state regimes are dynamic, so they are described by differential equations in any coordinate system. Their study cannot be carried out with sufficient adequacy on the basis of known equivalent circuits and require the use of dynamic parameters. In the mathematical model the state equations of the circuits of the stator and rotor are composed in the stationary three phase coordinate system. Calculation of the established mode is performed by solving the boundary problem that makes it possible to obtain the coordinate dependences over the period, without calculation of the transient process. In order to perform it, the original nonlinear differential equations are algebraized by approximating the variables with the use of cubic splines. The resulting nonlinear system of algebraic equations is a discrete analogue of the initial system of differential equations. It is solved by parameter continuation method. To calculate the static characteristics as a function of a certain variable, the system is analytically differentiated, and then numerically integrated over this variable. In the process of integration, Newton's refinement is performed at each step or at every few steps, making it possible to implement the integration in just a few steps using Euler's method. Jacobi matrices in both cases are the same. To account for the current displacement in the rods of the squirrel-cage rotor, each of them, along with the squirrel-cage rings, is divided in height into several elements. This results in several squirrel-cage rotor windings which are represented by three-phase windings with magnetic coupling between them.

  19. Multilevel markov chain monte carlo method for high-contrast single-phase flow problems

    KAUST Repository

    Efendiev, Yalchin R.

    2014-12-19

    In this paper we propose a general framework for the uncertainty quantification of quantities of interest for high-contrast single-phase flow problems. It is based on the generalized multiscale finite element method (GMsFEM) and multilevel Monte Carlo (MLMC) methods. The former provides a hierarchy of approximations of different resolution, whereas the latter gives an efficient way to estimate quantities of interest using samples on different levels. The number of basis functions in the online GMsFEM stage can be varied to determine the solution resolution and the computational cost, and to efficiently generate samples at different levels. In particular, it is cheap to generate samples on coarse grids but with low resolution, and it is expensive to generate samples on fine grids with high accuracy. By suitably choosing the number of samples at different levels, one can leverage the expensive computation in larger fine-grid spaces toward smaller coarse-grid spaces, while retaining the accuracy of the final Monte Carlo estimate. Further, we describe a multilevel Markov chain Monte Carlo method, which sequentially screens the proposal with different levels of approximations and reduces the number of evaluations required on fine grids, while combining the samples at different levels to arrive at an accurate estimate. The framework seamlessly integrates the multiscale features of the GMsFEM with the multilevel feature of the MLMC methods following the work in [26], and our numerical experiments illustrate its efficiency and accuracy in comparison with standard Monte Carlo estimates. © Global Science Press Limited 2015.

  20. Single phase flow pressure drop and heat transfer in rectangular metallic microchannels

    International Nuclear Information System (INIS)

    Sahar, Amirah M.; Özdemir, Mehmed R.; Fayyadh, Ekhlas M.; Wissink, Jan; Mahmoud, Mohamed M.; Karayiannis, Tassos G.

    2016-01-01

    Numerical simulations were performed using Fluent 14.5 to investigate single phase flow and conjugate heat transfer in copper rectangular microchannels. Two different configurations were simulated: (1) single channel with hydraulic diameter of 0.561 mm and (2) multichannel configuration consisting of inlet and outlet manifolds and 25 channels with hydraulic diameter of 0.409 mm. In the single channel configuration, four numerical models were investigated namely, 2D thin-wall, 3D thin-wall (heated from the bottom), 3D thin-wall (three side heated) and 3D full conjugate models. In the multichannel configuration, only 3D full conjugate model was used. The simulation results of the single channel configuration were validated using experimental data of water as a test fluid while the results of the multichannel configuration were validated using experimental data of R134a refrigerant. In the multichannel configuration, flow distribution among the channels was also investigated. The 3D thin-wall model simulation was conducted at thermal boundary conditions similar to those assumed in the experimental data reduction (uniform heat flux) and showed excellent agreement with the experimental data. However, the results of the 3D full conjugate model demonstrated that there is a significant conjugate effect and the heat flux is not uniformly distributed along the channel resulting in significant deviation compared to the experimental data (more than 50%). Also, the results demonstrated that there is a significant difference between the 3D thin-wall and full conjugate models. The simulation of the multichannel configuration with an inlet manifold having gradual decrease in cross sectional area achieved very reasonable uniform flow distribution among the channels which will provide uniform heat transfer rates across the base of the microchannels.

  1. Single-phase cross-mixing measurements in a 4 x 4 rod bundle

    International Nuclear Information System (INIS)

    Yloenen, Arto; Bissels, Wilhelm-Martin; Prasser, Horst-Michael

    2011-01-01

    Highlights: → The wire-mesh sensor technique has been successfully introduced into a fuel rod bundle geometry. → Quantitative information on the turbulent dispersion of the fluid was obtained. → In full spatial and temporal resolution, the data is interesting for the unsteady CFD validation. - Abstract: The wire-mesh sensor technique has been successfully introduced into a fuel rod bundle geometry for the first time. In this context, a dedicated test facility (SUBFLOW) has been designed and constructed at Paul Scherrer Institut (PSI) in a co-operation with the Swiss Federal Institute of Technology (ETH Zuerich). Two wire-mesh sensors designed and built in-house were installed in the upper part of the vertical test section of SUBFLOW, and single-phase experiments on the turbulent mass exchange between neighboring sub-channels were performed. For this purpose, salt tracer was injected locally in one of the sub-channels and conductivity distributions in the bundle measured by the wire-mesh sensor. Both flow rate and distance from the injection point were varied. The latter was achieved by using injection nozzles at different heights. In this way, the sensor located in the upper part of the channel could be used to characterize the progress of the mixing along the flow direction, and the degree of cross-mixing assessed using the quantity of tracer arriving in the neighboring sub-channels. Fluctuations of the tracer concentration in time were used for statistical evaluations, such as the calculation of standard deviations and two-point correlations.

  2. On the prediction of single-phase forced convection heat transfer in narrow rectangular channels

    International Nuclear Information System (INIS)

    Ghione, Alberto; Noel, Brigitte; Vinai, Paolo; Demazière, Christophe

    2014-01-01

    In this paper, selected heat transfer correlations for single-phase forced convection are assessed for the case of narrow rectangular channels. The work is of interest in the thermal-hydraulic analysis of the Jules Horowitz Reactor (JHR), which is a research reactor under construction at CEA-Cadarache (France). In order to evaluate the validity of the correlations, about 300 tests from the SULTAN-JHR database were used. The SULTAN-JHR program was carried out at CEA-Grenoble and it includes different kinds of tests for two different vertical rectangular channels with height of 600 mm and gap of 1.51 and 2.16 mm. The experimental conditions range between 2 - 9 bar for the pressure; 0.5 - 18 m/s for the coolant velocity and 0.5 - 7.5 MW/m 2 for the heat flux (whose axial distribution is uniform). Forty-two thermocouples and eight pressure taps were placed at several axial locations, measuring wall temperature and pressure respectively. The analysis focused on turbulent flow with Reynolds numbers between 5.5 x 10 3 - 2.4 x 10 5 and Prandtl numbers between 1.5 - 6. It was shown that standard correlations as the Dittus-Boelter and Seider-Tate significantly under-estimate the heat transfer coefficient, especially at high Reynolds number. Other correlations specifically designed for narrow rectangular channels were also taken into account and compared. The correlation of Popov-Petukhov in the form suggested by Siman-Tov still under-estimates the heat transfer coefficient, even if slight improvements could be seen. A better agreement for the tests with gap equal to 2.16 mm could be found with the correlation of Ma and the one of Liang. However the heat transfer coefficient when the gap is equal to 1.51 mm could not be predicted accurately. Furthermore these correlations were based on data at low Reynolds numbers (up to 13000) and low heat flux, so the use of them for SULTAN-JHR may be questionable. According to the authors’ knowledge, existing models of heat transfer

  3. Single phase and two phase erosion corrosion in broilers of gas-cooled reactors

    International Nuclear Information System (INIS)

    Harrison, G.S.; Fountain, M.J.

    1988-01-01

    Erosion-corrosion is a phenomenon causing metal wastage in a variety of locations in water and water-steam circuits throughout the power generation industry. Erosion-corrosion can occur in a number of regions of the once-through boiler designs used in the later Magnox and AGR type of gas cooled nuclear reactor. This paper will consider two cases of erosion-corrosion damage (single and two phase) in once through boilers of gas cooled reactors and will describe the solutions that have been developed. The single phase problem is associated with erosion-corrosion damage of mild steel downstream of a boiler inlet flow control orifice. With metal loss rates of up to 1 mm/year at 150 deg. C and pH in the range 9.0-9.4 it was found that 5 μg/kg oxygen was sufficient to reduce erosion-corrosion rates to less than 0.02 mm/year. A combined oxygen-ammonia-hydrazine feedwater regime was developed and validated to eliminate oxygen carryover and hence give protection from stress corrosion in the austenitic section of the AGR once through boiler whilst still providing erosion-corrosion control. Two phase erosion-corrosion tube failures have occurred in the evaporator of the mild steel once through boilers of the later Magnox reactors operating at pressures in the range 35-40 bar. Rig studies have shown that amines dosed in the feedwater can provide a significant reduction in metal loss rates and a tube lifetime assessment technique has been developed to predict potential tube failure profiles in a fully operational boiler. The solutions identified for both problems have been successfully implemented and the experience obtained following implementation including any problems or other benefits arising from the introduction of the new regimes will be presented. Methods for monitoring and evaluating the efficiency of the solutions have been developed and the results from these exercises will also be discussed. Consideration will also be given to the similarities in the metal loss

  4. Synthesis of Aluminum-Titanium Carbide Micro and Nanocomposites by the Rotating Impeller In-Situ Gas-Liquid Reaction Method

    Science.gov (United States)

    Anza, Inigo; Makhlouf, Makhlouf M.

    2018-02-01

    The Rotating Impeller In-Situ Gas-Liquid Reaction Method is employed for the production of Al-TiC composites. The method relies on injecting a carbon-bearing gas by means of a rotating impeller into a specially formulated molten aluminum-titanium alloy. Under the optimal conditions of temperature and composition, the gas reacts preferentially with titanium to form titanium carbide particles. The design of the apparatus, the process operation window, and the routes for forming titanium carbide particles with different sizes are elucidated.

  5. An optimized method for fatty acid analysis, including quantification of trans fatty acids, in human adipose tissue by gas-liquid chromatography

    DEFF Research Database (Denmark)

    Bysted, Anette; Cold, S; Hølmer, Gunhild Kofoed

    1999-01-01

    for 25 min, and finally raised at 25 degrees C/min to 225 degrees C. The trans and cis isomers of18:1 were well separated from each other, as shown by silver-ion thin-layer chromatography. Verification by standardsshowed that the trans 18:1 isomers with a double bond in position 12 or lower were......Considering the need for a quick direct method for measurement of the fatty acid composition including trans isomers ofhuman adipose tissue we have developed a procedure using gas-liquid chromatography (GLC) alone, which is thussuitable for validation of fatty acid status in epidemiological studies...

  6. Characterization of carbon dioxide transfer in a hollow fiber membrane module as a solution for gas-liquid transfer in microgravity conditions.

    Science.gov (United States)

    Farges, Berangere; Duchez, David; Dussap, Claude-Gilles; Cornet, Jean-F.

    In microgravity, one of the major difficulties encountered in closed photosynthetic reactors is the gas-liquid transfer with the necessity to provide CO2 (carbon source, pH control) and to recover the produced O2 . Indeed, reduced gravity is expected to modify gas liquid transfer and liquid phase mixing characteristics inside photobioreactors conceived to regenerate atmosphere of closed life-support systems. To obtain efficient mass transfer conditions and mixing of phases, several solutions are possible: use of rotating reactor (centrifugal field), use of forced, co-current convective reactor with gas-liquid separator and use of membrane modules. In terms of space process engineering, the membrane reactor can be a valuable alternative in which the gas and liquid phases are separated with a selectively permeable membrane. The rate-limiting factors in this reactor were demonstrated to be the surface of membrane A needed for diffusion of gases and the CO2 and O2 mass transfer coefficients in the liquid phase kL. How-ever, the major advantages of the membrane reactor are that it is composed of a hydrophobic membrane (here PTFE) which showed a high hydrophobicity, an important chemical resis-tance, a very long term stability and overall which is favourable to gas transfer. Moreover, the volumetric mass transfer coefficients are sufficiently high to build compact systems with small footprints, no complex rotating devices and lighter weights. This paper describes first the development of a system enabling the accurate characterization of the mass transfer limiting step for a PTFE membrane module. This original technical apparatus, together with a technical assessment of membrane permeability to different gases, is associated with a balance model, determining thus completely the CO2 mass transfer problem between phases. First results are given and discussed for the CO2 mass transfer coefficient CO kL 2 obtained in case of an absorption experiment at pH = 8 using the

  7. Gas-liquid two-phase flow behavior in terrain-inclined pipelines for gathering transport system of wet natural gas

    DEFF Research Database (Denmark)

    Yang, Yan; Li, Jingbo; Wang, Shuli

    2018-01-01

    The Volume of Fluid method and Re-Normalisation Group (RNG) k-ε turbulence model were employed to predict the gas-liquid two-phase flow in a terrain-inclined pipeline with deposited liquids. The simulation was carried out in a 22.5 m terrain-inclined pipeline with a 150 mm internal diameter...... on the liquid level under the suction force which caused by the negative pressure around the elbow, and then it touched to the top of the pipe. When the liquid blocked the pipe, the pressure drop between the upstream and downstream of the elbow increased with the increase of the gas velocity. At larger gas...

  8. A High-Power-Density Single-Phase Rectifier Based on Three-Level Neutral-Point Clamped Circuits

    Directory of Open Access Journals (Sweden)

    Tao Zhou

    2017-05-01

    Full Text Available A single-phase three-level converter is suitable for medium-power applications, with an interface voltage that is higher than that of a traditional two-level configuration. The three-level neutral-point clamped converter is adopted using four switches in each bridge arm, which, compared to a two-level rectifier, leads to less voltage stress, a lower switching frequency, and switching loss on switches. The transient current control strategy is designed to control the active power. The single-phase space vector pulse width modulation (SVPWM with a voltage balance strategy is designed to solve the neutral point voltage fluctuation problem and keep the dc-link voltage stable. A 1.3 kW high-power-density prototype based on SiC MOSFET was built and tested. The experimental results verified the high performance of steady-state and dynamic responses.

  9. Impact of Intragranular Substructure Parameters on the Forming Limit Diagrams of Single-Phase B.C.C. Steels

    Directory of Open Access Journals (Sweden)

    Gérald Franz

    2013-11-01

    Full Text Available An advanced elastic-plastic self-consistent polycrystalline model, accounting for intragranular microstructure development and evolution, is coupled with a bifurcation-based localization criterion and applied to the numerical investigation of the impact of microstructural patterns on ductility of single-phase steels. The proposed multiscale model, taking into account essential microstructural aspects, such as initial and induced textures, dislocation densities, and softening mechanisms, allows us to emphasize the relationship between intragranular microstructure of B.C.C. steels and their ductility. A qualitative study in terms of forming limit diagrams for various dislocation networks, during monotonic loading tests, is conducted in order to analyze the impact of intragranular substructure parameters on the formability of single-phase B.C.C. steels.

  10. Theoretical modelling and experimental investigation of single-phase and two-phase flow division at a tee-junction

    International Nuclear Information System (INIS)

    Lemonnier, H.; Hervieu, E.

    1991-01-01

    Phase separation in a tee-junction is modelled in the particular case of bubbly-flow. The model is based on a two-dimensional approach and hence, uses local equations. The first step consists in modelling the single-phase flow in the tee-junction. The free streamline theory is used to predict the flow of the continuous phase. The two recirculation zones which are presented in this case are predicted by the model. The second step consists in predicting the gas bubble paths as a result of the actions of the single-phase flow. Finally, the trajectories of gas bubbles are used to predict the separation characteristics of the tee-junction. Each step of the modelling procedure has been carefully tested by an in-depth experimental investigation. Excellent quantitative agreement is obtained between experimental results and model predictions. Moreover, the phase separation phenomenon is found to be clearly described by the model. (orig.)

  11. Green synthesis of isopropyl myristate in novel single phase medium Part II: Packed bed reactor (PBR) studies.

    Science.gov (United States)

    Vadgama, Rajeshkumar N; Odaneth, Annamma A; Lali, Arvind M

    2015-12-01

    Isopropyl myristate is a useful functional molecule responding to the requirements of numerous fields of application in cosmetic, pharmaceutical and food industry. In the present work, lipase-catalyzed production of isopropyl myristate by esterification of myristic acid with isopropyl alcohol (molar ratio of 1:15) in the homogenous reaction medium was performed on a bench-scale packed bed reactors, in order to obtain suitable reaction performance data for upscaling. An immobilized lipase B from Candida antartica was used as the biocatalyst based on our previous study. The process intensification resulted in a clean and green synthesis process comprising a series of packed bed reactors of immobilized enzyme and water dehydrant. In addition, use of the single phase reaction system facilitates efficient recovery of the product with no effluent generated and recyclability of unreacted substrates. The single phase reaction system coupled with a continuous operating bioreactor ensures a stable operational life for the enzyme.

  12. Green synthesis of isopropyl myristate in novel single phase medium Part II: Packed bed reactor (PBR studies

    Directory of Open Access Journals (Sweden)

    Rajeshkumar N. Vadgama

    2015-12-01

    Full Text Available Isopropyl myristate is a useful functional molecule responding to the requirements of numerous fields of application in cosmetic, pharmaceutical and food industry. In the present work, lipase-catalyzed production of isopropyl myristate by esterification of myristic acid with isopropyl alcohol (molar ratio of 1:15 in the homogenous reaction medium was performed on a bench-scale packed bed reactors, in order to obtain suitable reaction performance data for upscaling. An immobilized lipase B from Candida antartica was used as the biocatalyst based on our previous study. The process intensification resulted in a clean and green synthesis process comprising a series of packed bed reactors of immobilized enzyme and water dehydrant. In addition, use of the single phase reaction system facilitates efficient recovery of the product with no effluent generated and recyclability of unreacted substrates. The single phase reaction system coupled with a continuous operating bioreactor ensures a stable operational life for the enzyme.

  13. An Adaptive Quadrature Signal Generation Based Single-Phase Phase-Locked Loop for Grid-Connected Applications

    DEFF Research Database (Denmark)

    Golestan, Saeed; Guerrero, Josep M.; Abusorrah, Abdullah

    2017-01-01

    The quadrature signal generation based phase-locked loops (QSG-PLLs) are highly popular for synchronization purposes in single-phase systems. The main difference among these PLLs often lies in the technique they use for creating the fictitious quadrature component. One of the easiest QSG approaches...... is delaying the original single-phase signal by a quarter of a cycle. The PLL with such QSG technique is often called the transfer delay based PLL (TD-PLL). The TD-PLL benefits from a simple structure, rather fast dynamic response, and a good detection accuracy when the grid frequency is at its nominal value......, but it suffers from a phase offset error and double frequency oscillatory error in the estimated phase and frequency in the presence of frequency drifts. In this paper, a simple yet effective approach to remove the aforementioned errors of the TD-PLL is proposed. The resultant PLL structure is called...

  14. The Influence of phase-locked loop on the stability of single-phase grid-connected inverter

    DEFF Research Database (Denmark)

    Zhang, Chong; Wang, Xiongfei; Blaabjerg, Frede

    2015-01-01

    admittance of single-phase current-controlled inverters with different grid stiffness is analyzed in this paper. It shows that the PLL introduces a negative paralleled admittance into the output admittance of the inverter, which may lead to unintentional low-order harmonic oscillation in a weak grid...... for avoiding the PLL induced instability in single-phase inverters. At last the relationship between PLL bandwidth and the Short Circuit Ratio (SCR) of the grid has been derived to guide the design of the PLL. Experimental results are presented in order to verify this analysis, and the resonant frequencies can...... be predicted by the method. The possible instability due to different PLL bandwidth is also demonstrated....

  15. Analysis and Mitigation of Dead Time Harmonics in the Single-Phase Full-Bridge PWM Converters with Repetitive Controllers

    DEFF Research Database (Denmark)

    Yang, Yongheng; Zhou, Keliang; Wang, Huai

    2018-01-01

    -Width Modulation (PWM) schemes. Both solutions will contribute to a degradation of the injected current quality. As a consequence, the harmonics induced by the dead time (referred to as "dead time harmonics" hereafter) have to be compensated in order to achieve a satisfactory current quality as required...... by standards. In this paper, the emission mechanism of dead time harmonics in single-phase PWM inverters is thus presented considering the modulation schemes in details. More importantly, a repetitive controller has been adopted to eliminate the dead time effect in single-phase grid-connected PWM converters....... The repetitive controller has been plugged into a proportional resonant-based fundamental current controller so as to mitigate the dead time harmonics and also maintain the control of the fundamental-frequency grid current in terms of dynamics. Simulations and experiments are provided, which confirm...

  16. Analysis, Design, and Experimental Verification of A Synchronous Reference Frame Voltage Control for Single-Phase Inverters

    DEFF Research Database (Denmark)

    Monfared, Mohammad; Golestan, Saeed; Guerrero, Josep M.

    2014-01-01

    Control of three-phase power converters in the synchronous reference frame is now a mature and well developed research topic. However, for single-phase converters, it is not as well-established as three-phase applications. This paper deals with the design of a synchronous reference frame multi......-loop control strategy for single phase inverter-based islanded distributed generation (DG) systems. The proposed controller uses a synchronous reference frame PI (SRFPI) controller to regulate the instantaneous output voltage, a capacitor current shaping loop in the stationary reference frame to provide active...... in the synchronous reference frame, it is not straightforward to fine-tune the control parameters and evaluate the stability of the whole closed loop system. To overcome this problem, the stationary reference frame equivalent of the voltage loop is derived. Then, a step-by-step systematic design procedure based...

  17. Challenges to Grid Synchronization of Single-Phase Grid-Connected Inverters in Zero-Voltage Ride-Through Operation

    DEFF Research Database (Denmark)

    Zhang, Zhen; Yang, Yongheng; Blaabjerg, Frede

    2016-01-01

    With the fast development in Photovoltaic (PV) technology, the relevant grid-connection requirements/standards are continuously being updated, and more challenges have been imposed on both single-phase and three-phase grid-connected PV systems. For instance, PV systems are currently required...... to remain connected under grid voltage sags (even zero voltage condition). In this case, much attention should be paid to the grid synchronization in such a way to properly ride-through grid faults. Thus, in this paper, the most commonly-used and recently-developed Phase Locked Loop (PLL) synchronization...... methods have been evaluated for single-phase grid-connected PV systems in the case of Zero-Voltage Ride-Through (ZVRT) operation. The performances of the prior-art PLL methods in response to zero voltage faults in terms of detection precision and dynamic response are assessed in this paper. Simulation...

  18. Power Based Phase-Locked Loop Under Adverse Conditions with Moving Average Filter for Single-Phase System

    Directory of Open Access Journals (Sweden)

    Menxi Xie

    2017-06-01

    Full Text Available High performance synchronization methord is citical for grid connected power converter. For single-phase system, power based phase-locked loop(pPLL uses a multiplier as phase detector(PD. As single-phase grid voltage is distorted, the phase error information contains ac disturbances oscillating at integer multiples of fundamental frequency which lead to detection error. This paper presents a new scheme based on moving average filter(MAF applied in-loop of pPLL. The signal characteristic of phase error is dissussed in detail. A predictive rule is adopted to compensate the delay induced by MAF, thus achieving fast dynamic response. In the case of frequency deviate from nomimal, estimated frequency is fed back to adjust the filter window length of MAF and buffer size of predictive rule. Simulation and experimental results show that proposed PLL achieves good performance under adverse grid conditions.

  19. Safe-commutation principle for direct single-phase AC-AC converters for use in audio power amplification

    Energy Technology Data Exchange (ETDEWEB)

    Ljusev, P.; Andersen, Michael A.E.

    2005-07-01

    This paper presents an alternative safe commutation principle for a single phase bidirectional bridge, for use in the new generation of direct single-stage AC-AC audio power amplifiers. As compared with the bridge commutation with load current or source voltage sensing, in this approach it is not required to do any measurements, thus making it more reliable. Initial testing made on the prototype prove the feasibility of the approach. (au)

  20. Phase Balancing by Means of Electric Vehicles Single-Phase Connection Shifting in a Low Voltage Danish Grid

    DEFF Research Database (Denmark)

    Lico, Pasqualino; Marinelli, Mattia; Knezovic, Katarina

    2015-01-01

    In Denmark, household consumers are supplied with three phase with neutral cable. In addition, the distribution service operator cannot decide to which phase electrical appliance are connected. The technician who realizes the installation connects the loads according to his technical expertise...... stations are equipped with single-phase converters. According to the designed control strategy, the charging spot can select the phase to be used for the charge. The selection is done according to a phase voltage measurement....

  1. A single-phase PWM controlled AC to DC converter based on control of unity displacement power factor

    OpenAIRE

    Funabiki, Shigeyuki

    1990-01-01

    A modified pulse-width modulation (PWM) technique that improves the displacement power factor and the input power factor of a single-phase AC to DC converter is discussed. The modified converter is shown to have a high input power factor and allows the of DC voltage from zero to more than the maximum value of the source voltage. The displacement power factor is unity, and the input power factor is almost unity in the wide range of current command

  2. Design and analysis of linear oscillatory single-phase permanent magnet generator for free-piston stirling engine systems

    OpenAIRE

    Jeong-Man Kim; Jang-Young Choi; Kyu-Seok Lee; Sung-Ho Lee

    2017-01-01

    This study focuses on the design and analysis of a linear oscillatory single-phase permanent magnet generator for free-piston stirling engine (FPSE) systems. In order to implement the design of linear oscillatory generator (LOG) for suitable FPSEs, we conducted electromagnetic analysis of LOGs with varying design parameters. Then, detent force analysis was conducted using assisted PM. Using the assisted PM gave us the advantage of using mechanical strength by detent force. To improve the effi...

  3. Application of higher harmonics in protection against single-phase earth faults in resonant grounded cable networks of medium voltage

    OpenAIRE

    Vinokurova, T. Yu.; Dobryagina, O. A.; Shagurina, E. S.; Shuin, V. A.

    2015-01-01

    Protections based by higher harmonics absolute measurements the zero sequence currents of the protected object connections against single-phase earth faults in resonant grounded cable networks of medium voltage industrial and urban energy supply systems have been widely applied in Russia since the late 60s of the 20th century. However, some operational problems connected with sufficient selectivity and sensitivity of these protection devices appeared with time. Sensitivity and selectivity of ...

  4. Performance enhancement of the single-phase series active filter by employing the load voltage waveform reconstruction and line current sampling delay reduction methods

    DEFF Research Database (Denmark)

    Senturk, O.S.; Hava, A.M.

    2011-01-01

    This paper proposes the waveform reconstruction method (WRM), which is utilized in the single-phase series active filter's (SAF's) control algorithm, in order to extract the load harmonic voltage component of voltage harmonic type single-phase diode rectifier loads. Employing WRM and the line...

  5. Analysis of free-surface flows through energy considerations: Single-phase versus two-phase modeling.

    Science.gov (United States)

    Marrone, Salvatore; Colagrossi, Andrea; Di Mascio, Andrea; Le Touzé, David

    2016-05-01

    The study of energetic free-surface flows is challenging because of the large range of interface scales involved due to multiple fragmentations and reconnections of the air-water interface with the formation of drops and bubbles. Because of their complexity the investigation of such phenomena through numerical simulation largely increased during recent years. Actually, in the last decades different numerical models have been developed to study these flows, especially in the context of particle methods. In the latter a single-phase approximation is usually adopted to reduce the computational costs and the model complexity. While it is well known that the role of air largely affects the local flow evolution, it is still not clear whether this single-phase approximation is able to predict global flow features like the evolution of the global mechanical energy dissipation. The present work is dedicated to this topic through the study of a selected problem simulated with both single-phase and two-phase models. It is shown that, interestingly, even though flow evolutions are different, energy evolutions can be similar when including or not the presence of air. This is remarkable since, in the problem considered, with the two-phase model about half of the energy is lost in the air phase while in the one-phase model the energy is mainly dissipated by cavity collapses.

  6. Identification method for gas-liquid two-phase flow regime based on singular value decomposition and least square support vector machine

    International Nuclear Information System (INIS)

    Sun Bin; Zhou Yunlong; Zhao Peng; Guan Yuebo

    2007-01-01

    Aiming at the non-stationary characteristics of differential pressure fluctuation signals of gas-liquid two-phase flow, and the slow convergence of learning and liability of dropping into local minima for BP neural networks, flow regime identification method based on Singular Value Decomposition (SVD) and Least Square Support Vector Machine (LS-SVM) is presented. First of all, the Empirical Mode Decomposition (EMD) method is used to decompose the differential pressure fluctuation signals of gas-liquid two-phase flow into a number of stationary Intrinsic Mode Functions (IMFs) components from which the initial feature vector matrix is formed. By applying the singular vale decomposition technique to the initial feature vector matrixes, the singular values are obtained. Finally, the singular values serve as the flow regime characteristic vector to be LS-SVM classifier and flow regimes are identified by the output of the classifier. The identification result of four typical flow regimes of air-water two-phase flow in horizontal pipe has shown that this method achieves a higher identification rate. (authors)

  7. Gas-liquid two-phase flow behaviors and performance characteristics of proton exchange membrane fuel cells in a short-term microgravity environment

    Science.gov (United States)

    Guo, Hang; Liu, Xuan; Zhao, Jian Fu; Ye, Fang; Ma, Chong Fang

    2017-06-01

    In this work, proton exchange membrane fuel cells (PEMFCs) with transparent windows are designed to study the gas-liquid two-phase flow behaviors inside flow channels and the performance of a PEMFC with vertical channels and a PEMFC with horizontal channels in a normal gravity environment and a 3.6 s short-term microgravity environment. Experiments are conducted under high external circuit load and low external circuit load at low temperature where is 35 °C. The results of the present experimental work demonstrate that the performance and the gas-liquid two-phase flow behaviors of the PEMFC with vertical channels exhibits obvious changes when the PEMFCs enter the 3.6 s short-term microgravity environment from the normal gravity environment. Meanwhile, the performance of the PEMFC with vertical channels increases after the PEMFC enters the 3.6 s short-term microgravity environment under high external circuit load, while under low external circuit load, the PEMFC with horizontal channels exhibits better performance in both the normal gravity environment and the 3.6 s short-term microgravity environment.

  8. Visualization and measurement of gas-liquid metal two-phase flow with large density difference using thermal neutrons as microscopic probes

    International Nuclear Information System (INIS)

    Mishima, K.; Hibiki, T.; Saito, Y.; Nishihara, H.; Tobita, Y.; Konishi, K.; Matsubayashi, M.

    1999-01-01

    In a core melt accident of a fast breeder reactor, there is a possibility of boiling of the fuel-steel mixture in the containment pool. In relation to safety evaluation on severe accident, it is indispensable to evaluate the possibility of re-criticality of melted core. Gas-liquid two-phase flow with a large liquid-to-gas density ratio is formed due to the boiling of fuel-steel mixture. Although it is anticipated that the large density ratio may affect the basic characteristics of two-phase flow, little work has been performed so far on two-phase flow with a large liquid-to-gas density ratio. In this study, visualization and void fraction measurement of gas-liquid metal two-phase flow were performed by using neutron radiography and image processing techniques. Then, the effect of large density difference between gas and liquid phases on the basic flow characteristics of two-phase flow was clarified

  9. Influence of the gas-liquid flow configuration in the absorption column on photosynthetic biogas upgrading in algal-bacterial photobioreactors.

    Science.gov (United States)

    Toledo-Cervantes, Alma; Madrid-Chirinos, Cindy; Cantera, Sara; Lebrero, Raquel; Muñoz, Raúl

    2017-02-01

    The potential of an algal-bacterial system consisting of a high rate algal pond (HRAP) interconnected to an absorption column (AC) via recirculation of the cultivation broth for the upgrading of biogas and digestate was investigated. The influence of the gas-liquid flow configuration in the AC on the photosynthetic biogas upgrading process was assessed. AC operation in a co-current configuration enabled to maintain a biomass productivity of 15gm -2 d -1 , while during counter-current operation biomass productivity decreased to 8.7±0.5gm -2 d -1 as a result of trace metal limitation. A bio-methane composition complying with most international regulatory limits for injection into natural gas grids was obtained regardless of the gas-liquid flow configuration. Furthermore, the influence of the recycling liquid to biogas flowrate (L/G) ratio on bio-methane quality was assessed under both operational configurations obtaining the best composition at an L/G ratio of 0.5 and co-current flow operation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Preliminary characterization of carbon dioxide transfer in a hollow fiber membrane module as a possible solution for gas-liquid transfer in microgravity conditions

    Science.gov (United States)

    Farges, Bérangère; Duchez, David; Dussap, Claude-Gilles; Cornet, Jean-François

    2012-01-01

    In microgravity, one of the major challenge encountered in biological life support systems (BLSS) is the gas-liquid transfer with, for instance, the necessity to provide CO2 (carbon source, pH control) and to recover the evolved O2 in photobioreactors used as atmosphere bioregenerative systems.This paper describes first the development of a system enabling the accurate characterization of the mass transfer limiting step for a PTFE membrane module used as a possible efficient solution to the microgravity gas-liquid transfer. This original technical apparatus, together with a technical assessment of membrane permeability to different gases, is associated with a balance model, determining thus completely the CO2 mass transfer problem between phases. First results are given and discussed for the CO2 mass transfer coefficient kLCO obtained in case of absorption experiments at pH 8 using the hollow fiber membrane module. The consistency of the proposed method, based on a gas and liquid phase balances verifying carbon conservation enables a very accurate determination of the kLCO value as a main limiting step of the whole process. Nevertheless, further experiments are still needed to demonstrate that the proposed method could serve in the future as reference method for mass transfer coefficient determination if using membrane modules for BLSS in reduced or microgravity conditions.

  11. Influence of gas-liquid two-phase flow on angiotensin-I converting enzyme inhibitory peptides separation by ultra-filtration.

    Science.gov (United States)

    Charoenphun, Narin; Youravong, Wirote

    2017-01-01

    Membrane fouling is a major problem in ultra-filtration systems and two-phase flow is a promising technique for permeate flux enhancement. The objective of this research was to study the use of an ultra-filtration (UF) system to enrich angiotensin-I converting enzyme (ACE) inhibitory peptides from tilapia protein hydrolysate. To select the most appropriate membrane and operating condition, the effects of membrane molecular weight cut-off (MWCO), transmembrane pressure (TMP) and cross-flow velocity (CFV) on permeate flux and ACE inhibitory peptide separation were studied. Additionally, the gas-liquid two-phase flow technique was applied to investigate its effect on the process capability. The results showed that the highest ACE inhibitory activity was obtained from permeate of the 1 kDa membrane. In terms of TMP and CFV, the permeate flux tended to increase with TMP and CFV. The use of gas-liquid two-phase flow as indicated by shear stress number could reduce membrane fouling and increase the permeate flux up to 42%, depending on shear stress number. Moreover, the use of a shear stress number of 0.039 led to an augmentation in ACE inhibitory activity of permeates. Operating conditions using a shear stress number of 0.039 were recommended for enrichment of ACE inhibitory peptides. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  12. Experimental investigation of the liquid volumetric mass transfer coefficient for upward gas-liquid two-phase flow in rectangular microchannels

    Directory of Open Access Journals (Sweden)

    X. Y. Ji

    2010-12-01

    Full Text Available The gas-liquid two-phase mass transfer process in microchannels is complicated due to the special dynamical characteristics. In this work, a novel method was explored to measure the liquid side volumetric mass transfer coefficient kLa. Pressure transducers were utilized to measure the pressure variation of upward gas-liquid two-phase flow in three vertical rectangular microchannels and the liquid side volumetric mass transfer coefficient kLa was calculated through the Pressure-Volume-Temperature correlation of the gas phase. Carbon dioxide-water, carbon dioxide-ethanol and carbon dioxide-n-propanol were used as working fluids, respectively. The dimensions of the microchannels were 40 µm×240 µm (depth×width, 100 µm×800 µm and 100 µm×2000 µm, respectively. Results showed that the channel diameter and the capillary number influence kLa remarkably and that the maximum value of kLa occurs in the annular flow regime. A new correlation of kLa was proposed based on the Sherwood number, Schmidt number and the capillary number. The predicted values of kLa agreed well with the experimental data.

  13. Floating growth of large-scale freestanding TiO2 nanorod films at the gas-liquid interface for additive-free Li-ion battery applications.

    Science.gov (United States)

    Xia, Hua-Rong; Li, Jia; Peng, Chen; Sun, Wen-Tao; Li, Long-Wei; Peng, Lian-Mao

    2014-10-22

    The floating growth process of large-scale freestanding TiO2 nanorod films at the gas-liquid interface was investigated. On the basis of the experiments, a self-templated growth scenario was developed to account for the self-assembly process. In the scenario, titanium complexes function not only as the Ti source for the growth of TiO2 but also as a soft template provider for the floating growth. According to the scenario, several new recipes of preparing freestanding TiO2 nanorod films at the gas-liquid interface were developed. The freestanding film was applied to a lithium ion battery as a binder-free and conducting agent-free anode, and good cyclability was obtained. This work may pave a new way to floating and freestanding TiO2 and other semiconductor materials, which has great potential not only in basic science but also in the applications such as materials engineering, Li-ion battery, photocatalyst, dye-sensitized solar cell, and flexible electronics.

  14. Study of Co-Current and Counter-Current Gas-Liquid Two-Phase Flow Through Packed Bed in Microgravity

    Science.gov (United States)

    Revankar, Shripad T.

    2002-11-01

    The main goal of the project is to obtain new experimental data and development of models on the co-current and counter-current gas-liquid two-phase flow through a packed bed in microgravity and characterize the flow regime transition, pressure drop, void and interfacial area distribution, and liquid hold up. Experimental data will be obtained for earth gravity and microgravity conditions. Models will be developed for the prediction of flow regime transition, void fraction distribution and interfacial area concentration, which are key parameters to characterize the packed bed performance. Thus the specific objectives of the proposed research are to: (1) Develop experiments for the study of the gas liquid two-phase flow through the packed bed with three different flow combinations: co-current down flow, co-current upflow and counter current flow. (2) Develop pore scale and bed scale two-phase instrumentation for measurement of flow regime transition, void distribution and gas-liquid interfacial area concentration in the packed bed. (3) Obtain database on flow regime transition, pressure drop, void distribution, interfacial area concentration and liquid hold up as a function of bed characteristics such as bed particle size, porosity, and liquid properties such as viscosity and surface tension. (4) Develop mathematical model for flow regime transition, void fraction distribution and interfacial area concentration for co-current gas-liquid flow through the porous bed in gravity and micro gravity conditions.(4) Develop mathematical model for the flooding phenomena in counter-current gas-liquid flow through the porous bed in gravity and micro gravity conditions. The present proposal addresses the most important topic of HEDS-specific microgravity fluid physics research identified by NASA 's one of the strategic enterprises, OBPR Enterprise. The proposed project is well defined and makes efficient use of the ground-based parabolic flight research aircraft facility. The

  15. Gas-liquid countercurrent integration process for continuous biodiesel production using a microporous solid base KF/CaO as catalyst.

    Science.gov (United States)

    Hu, Shengyang; Wen, Libai; Wang, Yun; Zheng, Xinsheng; Han, Heyou

    2012-11-01

    A continuous-flow integration process was developed for biodiesel production using rapeseed oil as feedstock, based on the countercurrent contact reaction between gas and liquid, separation of glycerol on-line and cyclic utilization of methanol. Orthogonal experimental design and response surface methodology were adopted to optimize technological parameters. A second-order polynomial model for the biodiesel yield was established and validated experimentally. The high determination coefficient (R(2)=98.98%) and the low probability value (PrKF/CaO and 105.98kPa system pressure. Under these conditions, the average yield of triplicate experiments was 93.7%, indicating the continuous-flow process has good potential in the manufacture of biodiesel. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. KINETIC ANALYSIS OF THE ALKYLATION REACTION OF ISOBUTANE WITH 1-BUTENE ON A SOLID ACID CATALYST IN GAS, LIQUID, AND SUPERCRITICAL REACTION MEDIA. (R826694C669)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  17. State-to-state dynamics at the gas-liquid metal interface: rotationally and electronically inelastic scattering of NO[2Π(1/2)(0.5)] from molten gallium.

    Science.gov (United States)

    Ziemkiewicz, Michael P; Roscioli, Joseph R; Nesbitt, David J

    2011-06-21

    Jet cooled NO molecules are scattered at 45° with respect to the surface normal from a liquid gallium surface at E(inc) from 1.0(3) to 20(6) kcal/mol to probe rotationally and electronically inelastic scattering from a gas-molten metal interface (numbers in parenthesis represent 1σ uncertainty in the corresponding final digits). Scattered populations are detected at 45° by confocal laser induced fluorescence (LIF) on the γ(0-0) and γ(1-1) A(2)Σ ← X(2)Π(Ω) bands, yielding rotational, spin-orbit, and λ-doublet population distributions. Scattering of low speed NO molecules results in Boltzmann distributions with effective temperatures considerably lower than that of the surface, in respectable agreement with the Bowman-Gossage rotational cooling model [J. M. Bowman and J. L. Gossage, Chem. Phys. Lett. 96, 481 (1983)] for desorption from a restricted surface rotor state. Increasing collision energy results in a stronger increase in scattered NO rotational energy than spin-orbit excitation, with an opposite trend noted for changes in surface temperature. The difference between electronic and rotational dynamics is discussed in terms of the possible influence of electron hole pair excitations in the conducting metal. While such electronically non-adiabatic processes can also influence vibrational dynamics, the γ(1-1) band indicates rotational energy transfer is compared from a hard cube model perspective with previous studies of NO scattering from single crystal solid surfaces. Despite a lighter atomic mass (70 amu), the liquid Ga surface is found to promote translational to rotational excitation more efficiently than Ag(111) (108 amu) and nearly as effectively as Au(111) (197 amu). The enhanced propensity for Ga(l) to transform incident translational energy into rotation is discussed in terms of temperature-dependent capillary wave excitation of the gas-liquid metal interface. © 2011 American Institute of Physics

  18. A single-phase white light emitting Pr3+ doped Ba2CaWO6 phosphor: synthesis, photoluminescence and optical properties

    Science.gov (United States)

    Sreeja, E.; Vidyadharan, Viji; Jose, Saritha K.; George, Anns; Joseph, Cyriac; Unnikrishnan, N. V.; Biju, P. R.

    2018-04-01

    Pr3+ doped Ba2CaWO6 phosphor were prepared by traditional high-temperature solid-state reaction technique. The structure evolution was systematically investigated by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. The X-ray powder diffraction patterns indicate that the prepared phosphors crystallized in the cubic double-perovskite structure. The functional groups were identified using FTIR spectra and the elements present in the composition were confirmed by the EDS profile. The morphology of the phosphor was identified using SEM and TEM analysis. The PL spectra illustrated that these phosphors could be efficiently excited by charge transfer band of host and the maximum luminescence intensity was observed at 0.06 wt% of Pr3+ ion. Upon the charge transfer band excitation, emission spectra showed peaks at 489, 532, 647, 685 and 737 nm corresponding to 3P0→3H4, 3P1→3H5, 3P0→3F2, 3P0→3F3 and 3P0→3F4 transitions respectively. The concentration quenching of Ba2CaWO6:Pr3+ phosphor can be mainly attributed to dipole-dipole interaction. The CIE coordinates were estimated to be close to the white region. The decay curves are well fitted with double exponential decay models. The standard and modified Judd-Ofelt (JO) theories were used to determine the Judd-Ofelt intensity parameters, radiative transition probabilities and branching ratios. The optical properties indicate that Ba2CaWO6:Pr3+ phosphors can produce white light emission from a single phase host and its potential application for solid-state lighting and display devices.

  19. The effect of geometry and operation conditions on the performance of a gas-liquid cylindrical cyclone separator with new structure

    Science.gov (United States)

    Han, Qing; Zhang, Chi; Xu, Bo; Chen, Jiangping

    2013-07-01

    The hydrodynamic flow behavior, effects of geometry and working conditions of a gas-liquid cylindrical cyclone separator with a new structure are investigated by computational fluid dynamic and experiment. Gas liquid cylindrical cyclone separator is widely used in oil industry, refrigeration system because of its simple structure, high separating efficiency, little maintenance and no moving parts nor internal devices. In this work, a gas liquid cylindrical cyclone separator with new structure used before evaporator in refrigeration system can remove the vapor from the mixture and make evaporator compact by improving its heat exchange efficiency with the lower inlet quality. It also decreases evaporator pressure drop and reduces compressor work. The two pipes are placed symmetrically which makes each of them can be treated as inlet. It means when the fluids flow reverse, the separator performance will not be influence. Four samples with different geometry parameters are tested by experiment with different inlet quality (0.18-0.33), inlet mass flow rate (65-100kg/h). Compared with the experimental data, CFD simulation results show a good agreement. Eulerian multiphase model and Reynolds Stress Turbulence model are applied in the CFD simulation and obtained the inner flow field such as phase path lines, tangential velocity profiles and pressure and volume of fraction distribution contours. The separator body diameter (24, 36, 48mm) and inlet diameter (3.84, 4.8, 5.76mm) decide the maximum tangential velocity which results in the centrifugal force. The tangential velocity profiles are simulated and compared among different models. The higher tangential velocity makes higher quality of gas outlet but high pressure drop at the same time. Decreasing the inlet diameter increases quality of gas outlet pipe and pressure drop. High gas outlet quality is cost at high pressure drop. Increasing of separator diameter makes gas outlet quality increase first and then decrease but

  20. A review of modern advances in analyses and applications of single-phase natural circulation loop in nuclear thermal hydraulics

    International Nuclear Information System (INIS)

    Basu, Dipankar N.; Bhattacharyya, Souvik; Das, P.K.

    2014-01-01

    Highlights: • Comprehensive review of state-of-the-art on single-phase natural circulation loops. • Detailed discussion on growth in solar thermal system and nuclear thermal hydraulics. • Systematic development in scaling methodologies for fabrication of test facilities. • Importance of numerical modeling schemes for stability assessment using 1-D codes. • Appraisal of current trend of research and possible future directions. - Abstract: A comprehensive review of single-phase natural circulation loop (NCL) is presented here. Relevant literature reported since the later part of 1980s has been meticulously surveyed, with occasional obligatory reference to a few pioneering studies originating prior to that period, summarizing the key observations and the present trend of research. Development in the concept of buoyancy-induced flow is discussed, with introduction to flow initiation in an NCL due to instability. Detailed discussion on modern advancement in important application areas like solar thermal systems and nuclear thermal hydraulics are presented, with separate analysis for various reactor designs working on natural circulation. Identification of scaling criteria for designing lab-scale experimental facilities has gone through a series of modification. A systematic analysis of the same is presented, considering the state-of-the-art knowledge base. Different approaches have been followed for modeling single-phase NCLs, including simplified Lorenz system mostly for toroidal loops, 1-D computational modeling for both steady-state and stability characterization and 3-D commercial system codes to have a better flow visualization. Methodical review of the relevant studies is presented following a systematic approach, to assess the gradual progression in understanding of the practical system. Brief appraisal of current research interest is reported, including the use of nanofluids for fluid property augmentation, marine reactors subjected to rolling waves

  1. Synthesis and reactivity of single-phase Be{sub 17}Ti{sub 2} intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae-Hwan, E-mail: kim.jaehwan@jaea.go.jp [Breeding Functional Materials Development Group, Sector of Fusion Research and Development, Japan Atomic Energy Agency (Japan); Iwakiri, Hirotomo; Furugen, Tatsuaki [Faculty of Education Elementary and Secondary School Teacher Training Program, University of the Ryukyus, Okinawa (Japan); Nakamichi, Masaru [Breeding Functional Materials Development Group, Sector of Fusion Research and Development, Japan Atomic Energy Agency (Japan)

    2016-01-15

    Highlights: • Preliminary synthesis of single-phase Be{sub 17}Ti{sub 2} was succeeded. • Reactivity difference between beryllium and beryllides may be caused by a lattice strain. • Oxidation of Be{sub 17}Ti{sub 2} at high temperatures results in the formation of TiO{sub 2}. • Simulation results reveal that a stable site for hydrogen at the center of tetrahedron exists. - Abstract: To investigate feasibility for application of Be{sub 17}Ti{sub 2} as a neutron multiplier as well as a refractory material, single-phase Be{sub 17}Ti{sub 2} intermetallic compounds were synthesized using an annealing heat treatment of the starting powder and a plasma sintering method. Scanning electron microscopic observations and X-ray diffraction measurements reveal that the single-phase Be{sub 17}Ti{sub 2} compounds were successfully synthesized. We examined the reactivity of Be{sub 17}Ti{sub 2} with 1% H{sub 2}O and discovered that a larger stoichiometric amount of Ti resulted in the formation of TiO{sub 2} on the surface at high temperatures. This oxidation may also contribute to an increase in both weight gain and generation of H{sub 2}. This suggests that the formation of the Ti-depleted Be{sub 17}Ti{sub 2−x} layer as a result of oxidation facilitates an increased reactivity with H{sub 2}O. To evaluate the safety aspects of Be{sub 17}Ti{sub 2}, we also investigated the hydrogen positions and solution energies based on the first principle. The calculations reveal that there are 10 theoretical sites, where 9 of these sites have hydrogen solution energies with a positive value (endothermic) and 1 site located at the center of a tetrahedron comprising two Be and two Ti atoms gives a negative value (exothermic).

  2. Reduction of waveform distortion in grid-injection current from single-phase utility interactive PV-inverter

    International Nuclear Information System (INIS)

    Hamid, Muhammad Imran; Jusoh, Awang

    2014-01-01

    Highlights: • A reduction scheme for harmonics from utility interactive PV-inverter is proposed. • Single-phase conditioner with 3-phase expandability structure is used. • The single-phase conditioner in 3-phase structure work independently. • The scheme works effectively within overall operation range of the PV-inverter. • Conditioner in the scheme also improves the PV-inverter and plant’s utility factor. - Abstract: As the natural behavior of energy source and design characteristic, the current generated by a grid-interactive PV-inverter may contain harmonics. This distortion component will be carried on from the PV-inverter during injection power into the grid. Excessive harmonics in a grid will lead to a variety of power quality problems. This paper presents a distortion reduction scheme, utilizing a fed forward single-phase, generation-side power conditioner with a structure that can be expanded for use in a three-phase system and can work independently under imbalanced condition. Conditioner is placed in parallel with the photovoltaic plant and it functions to compensate the plant’s output current distortion, so that the total current flow to the grid is sinusoidal. This method also includes the implementation of a simpler control system for the conditioner, which consists of a combination of distortion current extraction, synchronization and a current control system, and realized through a TMS320F28335: a 150 MHz floating point DSP controller. Testing of the conditioner prototype, which was conducted on a real operation of a PV plant, showed that the scheme worked effectively within the overall operation range of the PV plant. This paper also discusses the potential of utility factor improvement of the PV-inverter and plant due to implementation of conditioner in the scheme

  3. Design and analysis of linear oscillatory single-phase permanent magnet generator for free-piston stirling engine systems

    Directory of Open Access Journals (Sweden)

    Jeong-Man Kim

    2017-05-01

    Full Text Available This study focuses on the design and analysis of a linear oscillatory single-phase permanent magnet generator for free-piston stirling engine (FPSE systems. In order to implement the design of linear oscillatory generator (LOG for suitable FPSEs, we conducted electromagnetic analysis of LOGs with varying design parameters. Then, detent force analysis was conducted using assisted PM. Using the assisted PM gave us the advantage of using mechanical strength by detent force. To improve the efficiency, we conducted characteristic analysis of eddy-current loss with respect to the PM segment. Finally, the experimental result was analyzed to confirm the prediction of the FEA.

  4. A modified P&O MPPT algorithm for single-phase PV systems based on deadbeat control

    DEFF Research Database (Denmark)

    Yang, Yongheng; Blaabjerg, Frede

    2012-01-01

    A modified perturb and observe (P&O) algorithm is presented to improve maximum power point tracking (MPPT) performance of photovoltaic (PV) systems. This modified algorithm is applied to a single-phase PV system based on deadbeat control in order to test the tracking accuracy and its impact...... on the reliability of the whole system. Both simulations and experimental results show that the proposed algorithm offers a fast response as well as smaller steady-state oscillations even under low irradiance condition compared with classical methods....

  5. A Comparison between Boundary and Continuous Conduction Modes in Single Phase PFC Using 600V Range Devices

    DEFF Research Database (Denmark)

    Hernandez Botella, Juan Carlos; Petersen, Lars Press; Andersen, Michael A. E.

    2015-01-01

    This paper presents an analysis and comparison of boundary conduction mode (BCM) and continuous conduction mode (CCM) in single phase power factor correction (PFC) applications. The comparison is based on double pulse tester (DPT) characterization results of state-of-the-art superjunction devices...... in the 600V range. The measured switching energy is used to evaluate the devices performance in a conventional PFC. This data is used together with a mathematical model for prediction of the conducted electromagnetic interference (EMI). This allows comparing the different devices in BCM and CCM operation...... modes and evaluating the performance as a function of the PFC power density and efficiency....

  6. Analysis, Control and Experimental Verification of a Single-Phase Capacitive-Coupling Grid-Connected Inverter

    DEFF Research Database (Denmark)

    Dai, Ning-Yi; Zhang, Wen-Chen; Wong, Man-Chung

    2015-01-01

    This study proposes a capacitive-coupling grid-connected inverter (CGCI), which consists of a full-bridge single-phase inverter coupled to a power grid via one capacitor in series with an inductor. The fundamental-frequency impedance of the coupling branch is capacitive. In contrast...... reactive power at an operational voltage much lower than that of the IGCI. This reduces the system's initial cost and operational losses, as well as the energy stored in the DC-link capacitor. The CGCI has been analysed and a DC voltage selection method is proposed. Using this method, the DC-link voltage...

  7. Can the heat transfer coefficients for single-phase flow and for convective flow boiling be equivalent?

    Science.gov (United States)

    Dorao, C. A.; Drewes, S.; Fernandino, M.

    2018-02-01

    During the past few decades, heat transfer during convective flow boiling inside pipes has been widely studied with the goal of unveiling the physics of the process. Different heat transfer mechanisms have been suggested based on different assumptions. This fact has resulted in a large number of models including different dimensionless numbers and in some cases up to a dozen of adjusted parameters. Here, we show that the convective flow boiling heat transfer coefficient is equivalent to the one for single-phase flow when the influence of the vapour velocity is taken into account.

  8. Myocardial CT perfusion imaging in a large animal model: comparison of dynamic versus single-phase acquisitions.

    Science.gov (United States)

    Schwarz, Florian; Hinkel, Rabea; Baloch, Elisabeth; Marcus, Roy P; Hildebrandt, Kristof; Sandner, Torleif A; Kupatt, Christian; Hoffmann, Verena; Wintersperger, Bernd J; Reiser, Maximilian F; Theisen, Daniel; Nikolaou, Konstantin; Bamberg, Fabian

    2013-12-01

    This study sought to compare dynamic versus single-phase high-pitch computed tomography (CT) acquisitions for the assessment of myocardial perfusion in a porcine model with adjustable degrees of coronary stenosis. The incremental value of the 2 different approaches to CT-based myocardial perfusion imaging remains unclear. Country pigs received stent implantation in the left anterior descending coronary artery, in which an adjustable narrowing (50% and 75% stenoses) was created using a balloon catheter. All animals underwent CT-based rest and adenosine-stress myocardial perfusion imaging using dynamic and single-phase high-pitch acquisitions at both degrees of stenosis. Fluorescent microspheres served as a reference standard for myocardial blood flow. Segmental CT-based myocardial blood flow (MBFCT) was derived from dynamic acquisitions. Segmental single-phase enhancement (SPE) was recorded from high-pitch, single-phase examinations. MBFCT and SPE were compared between post-stenotic and reference segments, and receiver-operating characteristic curve analysis was performed. Among 6 animals (28 ± 2 kg), there were significant differences of MBFCT and SPE between post-stenotic and reference segments for all acquisitions at 75% stenosis. By contrast, although for 50% stenosis at rest, MBFCT was lower in post-stenotic than in reference segments (0.65 ± 0.10 ml/g/min vs. 0.75 ± 0.16 ml/g/min, p < 0.05), there was no difference for SPE (128 ± 27 Hounsfield units vs. 137 ± 35 Hounsfield units, p = 0.17), which also did not significantly change under adenosine stress. In receiver-operating characteristic curve analyses, segmental MBFCT showed significantly better performance for ischemia prediction at 75% stenosis and stress (area under the curve: 0.99 vs. 0.89, p < 0.05) as well as for 50% stenosis, regardless of adenosine administration (area under the curve: 0.74 vs. 0.57 and 0.88 vs. 0.61, respectively, both p < 0.05). At higher degrees of coronary stenosis, both

  9. A simple and consistent equation of state for sodium in the single phase and two phase regions

    International Nuclear Information System (INIS)

    Breton, J.P.

    1976-01-01

    An equation of state valid over an extended temperature and density range has been derived. Then, the following properties have been deduced : coefficient of thermal expansion, isothermal coefficient of bulk compressibility, thermal pressure coefficient, heat capacity at constant pressure, at constant volume, along the saturation curve for liquid, for vapor, heat of vaporization, speed of sound, and finally the Mollier diagram and the entropy diagram. All the obtained properties are thermodynamically consistent and satisfy the basic relations of thermodynamics for both single phase and two-phase regions. Experimental results were always used when available. (auth.)

  10. A Single-Phase Voltage-Controlled Grid-Connected Photovoltaic System With Power Quality Conditioner Functionality

    DEFF Research Database (Denmark)

    Kerekes, Tamas; Liserre, Marco; Mastromauro, R. A.

    2009-01-01

    Future ancillary services provided by photovoltaic (PV) systems could facilitate their penetration in power systems. Also low power PV systems can be designed to improve the power quality. This paper presents a single-phase photovoltaic system that provides grid voltage support and compensation...... of harmonic distortion at the point of common coupling (PCC) thanks to a repetitive controller. The power provided by the PV panels is controlled by a Maximum Power Point Tracking (MPPT) algorithm based on the incremental conductance method specifically modified to control the phase of the PV inverter voltage...

  11. Design and analysis of linear oscillatory single-phase permanent magnet generator for free-piston stirling engine systems

    Science.gov (United States)

    Kim, Jeong-Man; Choi, Jang-Young; Lee, Kyu-Seok; Lee, Sung-Ho

    2017-05-01

    This study focuses on the design and analysis of a linear oscillatory single-phase permanent magnet generator for free-piston stirling engine (FPSE) systems. In order to implement the design of linear oscillatory generator (LOG) for suitable FPSEs, we conducted electromagnetic analysis of LOGs with varying design parameters. Then, detent force analysis was conducted using assisted PM. Using the assisted PM gave us the advantage of using mechanical strength by detent force. To improve the efficiency, we conducted characteristic analysis of eddy-current loss with respect to the PM segment. Finally, the experimental result was analyzed to confirm the prediction of the FEA.

  12. A Hybrid Estimator for Active/Reactive Power Control of Single-Phase Distributed Generation Systems with Energy Storage

    DEFF Research Database (Denmark)

    Pahlevani, Majid; Eren, Suzan; Guerrero, Josep M.

    2016-01-01

    This paper presents a new active/reactive power closed-loop control system for a hybrid renewable energy generation system used for single-phase residential/commercial applications. The proposed active/reactive control method includes a hybrid estimator, which is able to quickly and accurately...... estimate the active/reactive power values. The proposed control system enables the hybrid renewable energy generation system to be able to perform real-time grid interconnection services such as active voltage regulation, active power control, and fault ride-through.Simulation and experimental results...... demonstrate the superior performance of the proposed closed-loop control system....

  13. Single-Phase Full-Wave Rectifier as an Effective Example to Teach Normalization, Conduction Modes, and Circuit Analysis Methods

    Directory of Open Access Journals (Sweden)

    Predrag Pejovic

    2013-12-01

    Full Text Available Application of a single phase rectifier as an example in teaching circuit modeling, normalization, operating modes of nonlinear circuits, and circuit analysis methods is proposed.The rectifier supplied from a voltage source by an inductive impedance is analyzed in the discontinuous as well as in the continuous conduction mode. Completely analytical solution for the continuous conduction mode is derived. Appropriate numerical methods are proposed to obtain the circuit waveforms in both of the operating modes, and to compute the performance parameters. Source code of the program that performs such computation is provided.

  14. Comparison between Synthetic Inertia and Fast Frequency Containment Control Based on Single Phase EVs in a Microgrid

    DEFF Research Database (Denmark)

    Rezkalla, Michel M.N.; Zecchino, Antonio; Martinenas, Sergejus

    2017-01-01

    solutions. The objective of this paper is twofold: first, it aims to implement and validate fast frequency control and synthetic (virtual) inertia control, employing single phase electric vehicles as flexibility resources. Second, it proposes a trade-off analysis between the two controllers......The increasing share of distributed and inertia-less resources entails an upsurge in balancing and system stabilisation services. In particular, the displacement of conventional generation reduces the available rotational inertia in the power system, leading to high interest in synthetic inertia...

  15. Synthesis of single-phase L10-FeNi magnet powder by nitrogen insertion and topotactic extraction

    OpenAIRE

    Goto, Sho; Kura, Hiroaki; Watanabe, Eiji; Hayashi, Yasushi; Yanagihara, Hideto; Shimada, Yusuke; Mizuguchi, Masaki; Takanashi, Koki; Kita, Eiji

    2017-01-01

    Tetrataenite (L10-FeNi) is a promising candidate for use as a permanent magnet free of rare-earth elements because of its favorable properties. In this study, single-phase L10-FeNi powder with a high degree of order was synthesized through a new method, nitrogen insertion and topotactic extraction (NITE). In the method, FeNiN, which has the same ordered arrangement as L10-FeNi, is formed by nitriding A1-FeNi powder with ammonia gas. Subsequently, FeNiN is denitrided by topotactic reaction to ...

  16. An experimental and numerical study of developed single phase axial turbulent flow in a smooth rod bundle

    International Nuclear Information System (INIS)

    Hooper, J.D.

    1977-01-01

    A combined experimental and numerical model of a turbulent single phase coolant, flowing axially along the fuel pins of a nuclear reactor, was developed. The experimental rig represented two interconnected subchannels of a square array at a pitch/diameter ratio of 1.193. Air was the working fluid, and measurements were made of the mean radial velocity profiles, wall shear stress variation, turbulence velocity spectra and intensities. The numerically predicted wall shear distribution and mean velocity profiles, obtained using an empirical two-dimensional mixing length and eddy diffusivity concept to represent fluid turbulence, showed good agreement with the experimental results. (Author)

  17. Modeling and simulation of a pseudo-two-phase gas-liquid column reactor for thermal hydrocracking of petroleum heavy fractions

    Directory of Open Access Journals (Sweden)

    E.M. Matos

    2002-07-01

    Full Text Available This work presents a model to predict the behavior of velocity, gas holdup and local concentration fields in a pseudo-two-phase gas-liquid column reactor applied for thermal hydrocracking of petroleum heavy fractions. The model is based on the momentum and mass balances for the system, using an Eulerian-Eulerian approach. Using the k-epsilon model,fluid dynamics accounts for both laminar and turbulent flows, with discrete small bubbles (hydrogen flowing in a continuous pseudohomogeneous liquid phase (oil and catalyst particles. The petroleum is assumed to be a mixture of pseudocomponents, grouped by similar chemical structural properties, and the thermal hydrocracking is taken into account using a kinetic network based on these pseudocomponents.

  18. Ultrasonic measurement process of the ratio volume of gas in an enclosure containing a gas-liquid mixture to the total volume of the enclosure

    International Nuclear Information System (INIS)

    Marini, J.; Heinrich, J.P.

    1983-01-01

    Ultrasonic waves with two different frequencies are sent through the fluid in the containment. Time of propagation are measured and the difference is calculated. If propagation times are identical the gas phase forms a layer on the top of the liquid phase and void fraction is determined from propagation speeds in the gas and in the liquid. If propagation times are different, part of the gas forms bubbles and void fraction is the sum of gas on top of the liquid and gas bubbles in the liquid determined separatly. Void fraction coming from the gas over the liquid is determined by waves reflected at the interface gas-liquid. Void fraction coming from the bubbles is determined by relations between the speed of ultrasonic waves and their frequency as a function of pressure and void fraction [fr

  19. Activity coefficients at infinite dilution for solutes in the trioctylmethylammonium bis(trifluoromethylsulfonyl)imide ionic liquid using gas-liquid chromatography

    International Nuclear Information System (INIS)

    Gwala, Nobuhle V.; Deenadayalu, Nirmala; Tumba, Kaniki; Ramjugernath, Deresh

    2010-01-01

    The activity coefficient at infinite dilution (γ 13 ∞ ) for 30 solutes: alkanes, alkenes, cycloalkanes, alkynes, ketones, alcohols, and aromatic compounds was determined from gas-liquid chromatography (glc) measurements at three temperatures (303.15, 313.15, and 323.15) K. The ionic liquid: trioctylmethylammonium bis(trifluoromethylsulfonyl)imide, was used as the stationary phase. For each temperature, γ 13 ∞ values were determined using two columns with different mass percent packing of the ionic liquid. The selectivity (S 12 ∞ ) value was calculated from the γ 13 ∞ to determine the suitability of the solvent as a potential entrainer for extractive distillation in the separation of an hexane/benzene mixture, indicative of a typical industrial separation problem for benchmarking purposes.

  20. Influence of radiolysis and gas-liquid partition of I-131 in accumulated water on late phase source terms at Fukushima NPP accident

    International Nuclear Information System (INIS)

    Hidaka, Akihide

    2014-01-01

    In the process of core cooling at Fukushima Daiichi nuclear power plants accident, large amount of contaminated water was accumulated in the basements of the reactor buildings at Units 1 to 4. The present study estimated the quantities of I-131 and Cs-137 in the water as of late March based on the press-opened data. The estimated ratios of I-131 and Cs-137 quantities to the core inventories are 0.51%, 0.85% at Unit 1, 74%, 38% at Unit 2 and 26%, 18% at Unit 3, respectively. According to the Henry's law, certain fraction of iodine in water could be released to atmosphere due to gas-liquid partition and contribute to increase in the release to environment. A lot of evaluations for I-131 release have been performed so far by severe accident codes such as MELCOR or the reverse estimation with atmospheric dispersion code such as SPEEDI using the monitoring data. The SPEEDI reverse predicted significant release until March 26 while no prediction in MELCOR after March 17. The present study showed that iodine release from accumulated water due to radiolytic conversion from I - to I 2 and gas-liquid partition of I 2 may explain the release between March 17 and 26. This strongly suggests a need for improvement of current MELCOR approach which treats the release only from containment breaks for several days after the core melt. The study also indicates that the release of radioactive iodine from accumulated water in the basements of reactor buildings could become a great concern for the consequence of Fukushima accident. (author)