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Sample records for accurate gas mixtures

  1. Time-accurate analysis of nonequilibrium gas-particle mixtures using upwind/implicit finite-volume methodology

    SciTech Connect

    Hosangadi, A.; Sinha, N.; Dash, S.M. )

    1992-01-01

    A new Eulerian particulate solver whose numerical formulation is compatible with the numerics in state-of-the-art finite-volume upwind/implicit gas dynamic computer codes is presented. The heat transfer, drag, thermodynamic, and phase-change procedures in this code are derived from earlier, well established data fits and procedures. Performance for numerous flow problems with one- and two-way coupling is quite good. The solutions are nonoscillatory and robust and conserve flux balances very well. 18 refs.

  2. TEA laser gas mixture optimization

    NASA Astrophysics Data System (ADS)

    Lipchak, W. Michael; Luck, Clarence F.

    1982-11-01

    The topographical plot of an optimized parameter, such as pulse energy or peak power, on the gas mixture plane is presented as a useful aid in realizing optimum mixtures of helium, carbon dioxide, and nitrogen, for operation of CO2 TEA lasers. A method for generating such a plot is discussed and an example is shown. The potential benefits of this graphical technique are also discussed.

  3. TEA laser gas mixture optimization

    SciTech Connect

    Lipchak, W.M.; Luck, C.F.

    1982-11-01

    The topographical plot of an optimized parameter, such as pulse energy or peak power, on the gas mixture plane is presented as a useful aid in realizing optimum mixtures of helium, carbon dioxide, and nitrogen, for operation of CO/sub 2/ TEA lasers. A method for generating such a plot is discussed and an example is shown. The potential benefits of this graphical technique are also discussed.

  4. Ionization coefficients in gas mixtures

    NASA Astrophysics Data System (ADS)

    Marić, D.; Šašić, O.; Jovanović, J.; Radmilović-Rađenović, M.; Petrović, Z. Lj.

    2007-03-01

    We have tested the application of the common E/N ( E—electric field, N—gas number density) or Wieland approximation [Van Brunt, R.J., 1987. Common parametrizations of electron transport, collision cross section, and dielectric strength data for binary gas mixtures. J. Appl. Phys. 61 (5), 1773-1787.] and the common mean energy (CME) combination of the data for pure gases to obtain ionization coefficients for mixtures. Test calculations were made for Ar-CH4, Ar-N2, He-Xe and CH4-N2 mixtures. Standard combination procedure gives poor results in general, due to the fact that the electron energy distribution is considerably different in mixtures and in individual gases at the same values of E/N. The CME method may be used for mixtures of gases with ionization coefficients that do not differ by more than two orders of magnitude which is better than any other technique that was proposed [Marić, D., Radmilović-Rađenović, M., Petrović, Z.Lj., 2005. On parametrization and mixture laws for electron ionization coefficients. Eur. Phys. J. D 35, 313-321.].

  5. Line gas sampling system ensures accurate analysis

    SciTech Connect

    Not Available

    1992-06-01

    Tremendous changes in the natural gas business have resulted in new approaches to the way natural gas is measured. Electronic flow measurement has altered the business forever, with developments in instrumentation and a new sensitivity to the importance of proper natural gas sampling techniques. This paper reports that YZ Industries Inc., Snyder, Texas, combined its 40 years of sampling experience with the latest in microprocessor-based technology to develop the KynaPak 2000 series, the first on-line natural gas sampling system that is both compact and extremely accurate. This means the composition of the sampled gas must be representative of the whole and related to flow. If so, relative measurement and sampling techniques are married, gas volumes are accurately accounted for and adjustments to composition can be made.

  6. Equilibrium gas flow computations. I - Accurate and efficient calculation of equilibrium gas properties

    NASA Technical Reports Server (NTRS)

    Liu, Yen; Vinokur, Marcel

    1989-01-01

    This paper treats the accurate and efficient calculation of thermodynamic properties of arbitrary gas mixtures for equilibrium flow computations. New improvements in the Stupochenko-Jaffe model for the calculation of thermodynamic properties of diatomic molecules are presented. A unified formulation of equilibrium calculations for gas mixtures in terms of irreversible entropy is given. Using a highly accurate thermo-chemical data base, a new, efficient and vectorizable search algorithm is used to construct piecewise interpolation procedures with generate accurate thermodynamic variable and their derivatives required by modern computational algorithms. Results are presented for equilibrium air, and compared with those given by the Srinivasan program.

  7. Gas mixtures for spark gap closing switches

    DOEpatents

    Christophorou, Loucas G.; McCorkle, Dennis L.; Hunter, Scott R.

    1988-01-01

    Gas mixtures for use in spark gap closing switches comprised of fluorocarbons and low molecular weight, inert buffer gases. To this can be added a third gas having a low ionization potential relative to the buffer gas. The gas mixtures presented possess properties that optimized the efficiency spark gap closing switches.

  8. Gas mixtures for spark gap closing switches

    DOEpatents

    Christophorou, L.G.; McCorkle, D.L.; Hunter, S.R.

    1987-02-20

    Gas mixtures for use in spark gap closing switches comprised of fluorocarbons and low molecular weight, inert buffer gases. To this can be added a third gas having a low ionization potential relative to the buffer gas. The gas mixtures presented possess properties that optimized the efficiency spark gap closing switches. 6 figs.

  9. Ternary gas mixture for diffuse discharge switch

    DOEpatents

    Christophorou, Loucas G.; Hunter, Scott R.

    1988-01-01

    A new diffuse discharge gas switch wherein a mixture of gases is used to take advantage of desirable properties of the respective gases. There is a conducting gas, an insulating gas, and a third gas that has low ionization energy resulting in a net increase in the number of electrons available to produce a current.

  10. Dielectric gas mixtures containing sulfur hexafluoride

    DOEpatents

    Cooke, Chathan M.

    1979-01-01

    Electrically insulating gaseous media of unexpectedly high dielectric strength comprised of mixtures of two or more dielectric gases are disclosed wherein the dielectric strength of at least one gas in each mixture increases at less than a linear rate with increasing pressure and the mixture gases are present in such proportions that the sum of their electrical discharge voltages at their respective partial pressures exceeds the electrical discharge voltage of each individual gas at the same temperature and pressure as that of the mixture.

  11. Further gas mixtures with low environment impact

    NASA Astrophysics Data System (ADS)

    Liberti, B.; Aielli, G.; Camarri, P.; Cardarelli, R.; Di Ciaccio, A.; Di Stante, L.; Pastori and, E.; Santonico, R.

    2016-09-01

    Further gas mixtures with low environment impact have been tested. For the best RPC performance the main effort was to look for a mixture giving a comfortable avalanche-streamer separation and a gas density ensuring sufficient primary ionization. The measurements have been carried out on small size chambers at cosmic ray rates using the waveforms recorded on the oscilloscope. Efficiencies and distributions of amplitude and charge will be presented.

  12. Improved gas mixtures for gas-filled radiation detectors

    DOEpatents

    Christophorou, L.G.; McCorkle, D.L.; Maxey, D.V.; Carter, J.G.

    1980-03-28

    Improved binary and ternary gas mixtures for gas-filled radiation detectors are provided. The components are chosen on the basis of the principle that the first component is one molecular gas or mixture of two molecular gases having a large electron scattering cross section at energies of about 0.5 eV and higher, and the second component is a noble gas having a very small cross section at and below about 1.0 eV, whereby fast electrons in the gaseous mixture are slowed into the energy range of about 0.5 eV where the cross section for the mixture is small and hence the electron mean free path is large. The reduction in both the cross section and the electron energy results in an increase in the drift velocity of the electrons in the gas mixtures over that for the separate components for a range of E/P (pressure-reduced electric field) values. Several gas mixtures are provided that provide faster response in gas-filled detectors for convenient E/P ranges as compared with conventional gas mixtures.

  13. Gas mixtures for gas-filled radiation detectors

    DOEpatents

    Christophorou, Loucas G.; McCorkle, Dennis L.; Maxey, David V.; Carter, James G.

    1982-01-05

    Improved binary and ternary gas mixtures for gas-filled radiation detectors are provided. The components are chosen on the basis of the principle that the first component is one molecular gas or mixture of two molecular gases having a large electron scattering cross section at energies of about 0.5 eV and higher, and the second component is a noble gas having a very small cross section at and below about 1.0 eV, whereby fast electrons in the gaseous mixture are slowed into the energy range of about 0.5 eV where the cross section for the mixture is small and hence the electron mean free path is large. The reduction in both the cross section and the electron energy results in an increase in the drift velocity of the electrons in the gas mixtures over that for the separate components for a range of E/P (pressure-reduced electric field) values. Several gas mixtures are provided that provide faster response in gas-filled detectors for convenient E/P ranges as compared with conventional gas mixtures.

  14. Improved gas mixtures for gas-filled particle detectors

    DOEpatents

    Christophorou, L.G.; McCorkle, D.L.; Maxey, D.V.; Carter, J.G.

    Improved binary and tertiary gas mixture for gas-filled particle detectors are provided. The components are chosen on the basis of the principle that the first component is one gas or mixture of two gases having a large electron scattering cross section at energies of about 0.5 eV and higher, and the second component is a gas (Ar) having a very small cross section at and below about 0.5 eV; whereby fast electrons in the gaseous mixture are slowed into the energy range of about 0.5 eV where the cross section for the mixture is small and hence the electron mean free path is large. The reduction in both the cross section and the electron energy results in an increase in the drift velocity of the electrons in the gas mixtures over that for the separate components for a range of E/P (pressure-reduced electron field) values. Several gas mixtures are provided that provide faster response in gas-filled detectors for convenient E/P ranges as compared with conventional gas mixtures.

  15. Gas mixtures for gas-filled particle detectors

    DOEpatents

    Christophorou, Loucas G.; McCorkle, Dennis L.; Maxey, David V.; Carter, James G.

    1980-01-01

    Improved binary and tertiary gas mixtures for gas-filled particle detectors are provided. The components are chosen on the basis of the principle that the first component is one gas or mixture of two gases having a large electron scattering cross section at energies of about 0.5 eV and higher, and the second component is a gas (Ar) having a very small cross section at and below aout 0.5 eV, whereby fast electrons in the gaseous mixture are slowed into the energy range of about 0.5 eV where the cross section for the mixture is small and hence the electron mean free path is large. The reduction in both the cross section and the electron energy results in an increase in the drift velocity of the electrons in the gas mixtures over that for the separate components for a range of E/P (pressure-reduced electron field) values. Several gas mixtures are provided that provide faster response in gas-filled detectors for convenient E/P ranges as compared with conventional gas mixtures.

  16. SEPARATION OF GAS MIXTURES BY THERMOACOUSTIC WAVES

    SciTech Connect

    G.W. SWIFT; D.A. GELLER; P.S. SPOOR

    2001-06-01

    Imposing sound on a binary gas mixture in a duct separates the two gases along the acoustic-propagation axis. Mole-fraction differences as large as 10% and separation fluxes as high as 0.001 M-squared c, where M is Mach number and c is sound speed, are easily observed. We describe the accidental discovery of this phenomenon in a helium-xenon mixture, subsequent experiments with a helium-argon mixture, and theoretical developments. The phenomenon occurs because a thin layer of the gas adjacent to the wall is immobilized by viscosity while the rest of the gas moves back and forth with the wave, and the heat capacity of the wall holds this thin layer of the gas at constant temperature while the rest of the gas experiences temperature oscillations due to the wave's oscillating pressure. The oscillating temperature gradient causes the light and heavy atoms in the gas to take turns diffusing into and out of the immobilized layer, so that the oscillating motion of the wave outside the immobilized layer tends to carry light-enriched gas in one direction and heavy-enriched gas in the opposite direction. Experiment and theory are in very good agreement for the initial separation fluxes and the saturation mole-fraction differences.

  17. TOPICAL REVIEW: Thermal plasmas in gas mixtures

    NASA Astrophysics Data System (ADS)

    Murphy, A. B.

    2001-10-01

    The calculation and measurement of the properties of thermal plasmas in mixtures of different gases are reviewed. The calculation of composition, thermodynamic properties and transport coefficients is described. Particular attention is given to the calculation of diffusion coefficients, which is a significant problem in mixed-gas plasmas. The combined diffusion coefficient formulation is shown to be a useful method for the treatment of diffusion. Computational fluid dynamic modelling of thermal plasmas in gas mixtures is considered, using the examples of demixing in welding arcs, the turbulent mixing of atmospheric air into a plasma jet and a plasma waste destruction process. Diagnostic techniques for mixed-gas plasmas, in particular emission spectroscopy, laser scattering and laser-induced fluorescence, are discussed.

  18. IGNITION IMPROVEMENT OF LEAN NATURAL GAS MIXTURES

    SciTech Connect

    Jason M. Keith

    2005-02-01

    This report describes work performed during a thirty month project which involves the production of dimethyl ether (DME) on-site for use as an ignition-improving additive in a compression-ignition natural gas engine. A single cylinder spark ignition engine was converted to compression ignition operation. The engine was then fully instrumented with a cylinder pressure transducer, crank shaft position sensor, airflow meter, natural gas mass flow sensor, and an exhaust temperature sensor. Finally, the engine was interfaced with a control system for pilot injection of DME. The engine testing is currently in progress. In addition, a one-pass process to form DME from natural gas was simulated with chemical processing software. Natural gas is reformed to synthesis gas (a mixture of hydrogen and carbon monoxide), converted into methanol, and finally to DME in three steps. Of additional benefit to the internal combustion engine, the offgas from the pilot process can be mixed with the main natural gas charge and is expected to improve engine performance. Furthermore, a one-pass pilot facility was constructed to produce 3.7 liters/hour (0.98 gallons/hour) DME from methanol in order to characterize the effluent DME solution and determine suitability for engine use. Successful production of DME led to an economic estimate of completing a full natural gas-to-DME pilot process. Additional experimental work in constructing a synthesis gas to methanol reactor is in progress. The overall recommendation from this work is that natural gas to DME is not a suitable pathway to improved natural gas engine performance. The major reasons are difficulties in handling DME for pilot injection and the large capital costs associated with DME production from natural gas.

  19. Temperature and vibrational distribution function in high-pressure diatomic gas mixture

    NASA Astrophysics Data System (ADS)

    Lou, Guofeng; Lempert, Walter R; Adamovich, Igor V; Rich, William J

    2009-03-01

    Temperatures and vibrational populations are investigated experimentally and numerically in a CO-N2-O2 gas mixture. By spatially resolved Raman Q-branch spectra measurement, the strong vibrational excitation was observed in the gas mixtures at a high gas pressure. Numerical calculation, which incorporates both major processes of molecular energy transfer and diffusion of vibrationally excited species across the spatially nonuniform excitation region, provides indepth perception of vibrational kinetics of these diatomic molecular gas mixtures and is verified by the experimental data. The results demonstrate that strong vibrational nonequilibrium for all diatomic species can be sustained by the optical pumping method with a focused CO laser in a relatively cold (300-400 K) molecular gas mixture up to one atmospheric pressure. However, the results also demand further investigations on determining accurate rates of the V-V exchange gas mixture such as for N2-O2.

  20. Precursors in gas-liquid mixtures

    NASA Astrophysics Data System (ADS)

    Gasenko, V. G.; Gorelik, R. S.; Nakoryakov, V. E.; Timkin, L. S.

    2013-10-01

    Two types of precursors propagating at the speed of sound in a pure liquid have been revealed in the experiments on the evolution of pressure pulses in a gas-liquid mixture; at the same time, the main pressure pulse propagates at a low equilibrium speed of sound and its evolution is described by the Burgers-Korteweg-de Vries equation. The first high-frequency precursor is a complete analog of a classical Sommerfeld precursor, because the resonance dispersion equation for a bubble mixture coincides with that for insulators in the Lorentz model, and oscillates at a frequency close to the "plasma frequency." The second low-frequency precursor has been revealed in this work. The frequency of the low-frequency precursor is close to the resonance frequency of pulsations of bubbles, which is almost an order of magnitude lower than the frequency of the high-frequency precursor. The low-frequency precursor has a much larger amplitude of pulsations and smaller damping and is not described within the homogeneous model of the gas-liquid mixture. The observed phenomenon of low-frequency precursors has been explained within a simple heterogeneous model of a bubble liquid.

  1. Dusty Plasma Structures in Gas Mixtures

    SciTech Connect

    Popova, D. V.; Antipov, S. N.; Petrov, O. F.; Fortov, V. E.

    2008-09-07

    The possibility of attainment of large Mach numbers is analyzed for the case of heavy ions drifting in a light gas. Under conditions of typical experiments with dust structures in plasmas, the use of the mixture of light and heavy gases is shown to make it possible to suppress the ion heating in the electric field and to form supersonic flows characterized by large Mach numbers. The drift of krypton ions in helium is considered as an example. Experiments with dc glow discharge at 1-10% of Kr show that the transition to the discharge in mixture leads to increase of interaction anisotropy and reinforcement of coupling of dust particles in the direction of ion drift. On the other hand, under certain conditions the phenomenon of abnormal 'heating' of dust particles was observed when the particles can obtain high kinetic energy which is several orders of magnitude higher than typical.

  2. Gettering of hydrogen and methane from a helium gas mixture

    SciTech Connect

    Cárdenas, Rosa Elia; Stewart, Kenneth D.; Cowgill, Donald F.

    2014-11-01

    In this study, the authors developed an approach for accurately quantifying the helium content in a gas mixture also containing hydrogen and methane using commercially available getters. The authors performed a systematic study to examine how both H{sub 2} and CH{sub 4} can be removed simultaneously from the mixture using two SAES St 172{sup ®} getters operating at different temperatures. The remaining He within the gas mixture can then be measured directly using a capacitance manometer. The optimum combination involved operating one getter at 650 °C to decompose the methane, and the second at 110 °C to remove the hydrogen. This approach eliminated the need to reactivate the getters between measurements, thereby enabling multiple measurements to be made within a short time interval, with accuracy better than 1%. The authors anticipate that such an approach will be particularly useful for quantifying the He-3 in mixtures that include tritium, tritiated methane, and helium-3. The presence of tritiated methane, generated by tritium activity, often complicates such measurements.

  3. Gettering of Hydrogen and Methane from a Helium Gas Mixture

    SciTech Connect

    Cardenas, Rosa E.; Stewart, Kenneth D.; Cowgill, Donald F.

    2014-10-21

    In our study, the authors developed an approach for accurately quantifying the helium content in a gas mixture also containing hydrogen and methane using commercially available getters. The authors performed a systematic study to examine how both H2 and CH4 can be removed simultaneously from the mixture using two SAES St 172® getters operating at different temperatures. The remaining He within the gas mixture can then be measured directly using a capacitance manometer. Moreover, the optimum combination involved operating one getter at 650°C to decompose the methane, and the second at 110°C to remove the hydrogen. Finally, this approach eliminated the need to reactivate the getters between measurements, thereby enabling multiple measurements to be made within a short time interval, with accuracy better than 1%. The authors anticipate that such an approach will be particularly useful for quantifying the He-3 in mixtures that include tritium, tritiated methane, and helium-3. The presence of tritiated methane, generated by tritium activity, often complicates such measurements.

  4. Gettering of Hydrogen and Methane from a Helium Gas Mixture

    DOE PAGES

    Cardenas, Rosa E.; Stewart, Kenneth D.; Cowgill, Donald F.

    2014-10-21

    In our study, the authors developed an approach for accurately quantifying the helium content in a gas mixture also containing hydrogen and methane using commercially available getters. The authors performed a systematic study to examine how both H2 and CH4 can be removed simultaneously from the mixture using two SAES St 172® getters operating at different temperatures. The remaining He within the gas mixture can then be measured directly using a capacitance manometer. Moreover, the optimum combination involved operating one getter at 650°C to decompose the methane, and the second at 110°C to remove the hydrogen. Finally, this approach eliminatedmore » the need to reactivate the getters between measurements, thereby enabling multiple measurements to be made within a short time interval, with accuracy better than 1%. The authors anticipate that such an approach will be particularly useful for quantifying the He-3 in mixtures that include tritium, tritiated methane, and helium-3. The presence of tritiated methane, generated by tritium activity, often complicates such measurements.« less

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

    NASA Technical Reports Server (NTRS)

    Branum, L. W.

    1966-01-01

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

  6. Spark decomposition studies of dielectric gas mixtures

    NASA Astrophysics Data System (ADS)

    Sauers, I.; Christophorou, L. G.

    The ultimate usefulness of a high voltage insulating gas depends not only on the ability of the gas to withstand high voltages, but also on the degradation of the gas resulting from spark discharges, corona or prolonged electrical stress and the effect(s) of the by-products on the equipment and, possibly, the environment. In view of these considerations, the study of long-range spark decomposition was undertaken in an effort to improve the decomposition characteristics of dielectric gases through proper tailoring of gas mixtures while maintaining high breakdown strengths. The data reported are on the analyses of gases sparked by capactive (0.1 micro F) discharge into a 0.5-mm gap, resulting in an energy input of approximately 5 J per spark. The nature of the decomposition products of SF6 formed by high voltage discharges observed is found to be critically dependent on impurities (particularly H2O), electrode material and insulating materials present in the system.

  7. Smoothed particle hydrodynamics simulations of gas and dust mixtures

    NASA Astrophysics Data System (ADS)

    Booth, R. A.; Sijacki, D.; Clarke, C. J.

    2015-10-01

    We present a `two-fluid' implementation of dust in smoothed particle hydrodynamics (SPH) in the test particle limit. The scheme is able to handle both short and long stopping times and reproduces the short friction time limit, which is not properly handled in other implementations. We apply novel tests to verify its accuracy and limitations, including multidimensional tests that have not been previously applied to the drag-coupled dust problem and which are particularly relevant to self-gravitating protoplanetary discs. Our tests demonstrate several key requirements for accurate simulations of gas-dust mixtures. First, in standard SPH particle jitter can degrade the dust solution, even when the gas density is well reproduced. The use of integral gradients, a Wendland kernel and a large number of neighbours can control this, albeit at a greater computational cost. Secondly, when it is necessary to limit the artificial viscosity we recommend using the Cullen & Dehnen switch, since the alternative, using α ˜ 0.1, can generate a large velocity noise up to σv ≲ 0.3cs in the dust particles. Thirdly, we find that an accurate dust density estimate requires >400 neighbours, since, unlike the gas, the dust particles do not feel regularization forces. This density noise applies to all particle-based two-fluid implementations of dust, irrespective of the hydro solver and could lead to numerically induced fragmentation. Although our tests show accurate dusty gas simulations are possible, care must be taken to minimize the contribution from numerical noise.

  8. Electrical Breakdown in a Martian Gas Mixture

    NASA Technical Reports Server (NTRS)

    Buhler, C. R.; Calle, C. I.; Nelson, E.

    2003-01-01

    The high probability for dust interactions during Martian dust storms and dust devils combined with the cold, dry climate of Mars most likely result in airborne dust that is highly charged. On Earth, potential gradients up to 5 kV/m have been recorded and in some cases resulted in lightning. Although the Martian atmosphere is not conducive to lightning generation, it is widely believed that electrical discharge in the form of a corona occurs. In order to understand the breakdown of gases, Paschen measurements are taken which relate the minimum potential required to spark across a gap between two electrodes. The minimum potential is plotted versus the pressure-distance value for electrodes of a given geometry. For most gases, the potential decreases as the pressure decreases. For CO2, the minimum in the curve happens to be at Mars atmospheric pressures (5-7 mm Hg) for many distances and geometries. However, a very small amount (<0.1%) of mixing gases radically changes the curve, as noted by Leach. Here, we present the first experimental results of a Paschen curve for a Mars gas mixture compared with 100% pure CO2.

  9. Separation of gas mixtures by supported complexes

    SciTech Connect

    Lilga, M.A.

    1987-05-29

    The current project centers on the preparation and characterization of complexes that can be used to separate H/sub 2/ from gas mixtures. Of interest are complexes which are inexpensive and which reversibly bind H/sub 2/. In particular, dimeric complexes of chromium, ((C/sub 5/H/sub 4/R)Cr(CO)/sub 3/)/sub 2/ (R = H, CO/sub 2/CH/sub 3/, alkyl), are being studied in this project. The basic methodology used is to prepare various derivatives containing substitution on the cyclopentadienyl ligand and to screen these derivatives for reversible reaction with H/sub 2/. Once reversibility is achieved, kinetic and equilibrium data will be collected to fully characterize the system and possibly elucidate the effects of substituents on H/sub 2/ binding. Also of interest are complexes which reversibly and catalytically incorporate H/sub 2/ into an organic ketone substrate. An Rh/Sn complex which reversibly hydrogenates/dehydrogenates cyclohexanone will be discussed. Although Rh is not inexpensive, it is present in very low concentration and represents a potentially inexpensive yet selective H/sub 2/ separation method. 5 refs.

  10. SNP-microarrays can accurately identify the presence of an individual in complex forensic DNA mixtures.

    PubMed

    Voskoboinik, Lev; Ayers, Sheri B; LeFebvre, Aaron K; Darvasi, Ariel

    2015-05-01

    Common forensic and mass disaster scenarios present DNA evidence that comprises a mixture of several contributors. Identifying the presence of an individual in such mixtures has proven difficult. In the current study, we evaluate the practical usefulness of currently available "off-the-shelf" SNP microarrays for such purposes. We found that a set of 3000 SNPs specifically selected for this purpose can accurately identify the presence of an individual in complex DNA mixtures of various compositions. For example, individuals contributing as little as 5% to a complex DNA mixture can be robustly identified even if the starting DNA amount was as little as 5.0ng and had undergone whole-genome amplification (WGA) prior to SNP analysis. The work presented in this study represents proof-of-principle that our previously proposed approach, can work with real "forensic-type" samples. Furthermore, in the absence of a low-density focused forensic SNP microarray, the use of standard, currently available high-density SNP microarrays can be similarly used and even increase statistical power due to the larger amount of available information.

  11. Chemical recognition of gases and gas mixtures with terahertz waves

    NASA Astrophysics Data System (ADS)

    Jacobsen, R. H.; Mittleman, D. M.; Nuss, M. C.

    1996-12-01

    A time-domain chemical-recognition system for classifying gases and analyzing gas mixtures is presented. We analyze the free induction decay exhibited by gases excited by far-infrared (terahertz) pulses in the time domain, using digital signal-processing techniques. A simple geometric picture is used for the classification of the waveforms measured for unknown gas species. We demonstrate how the recognition system can be used to determine the partial pressures of an ammonia-water gas mixture.

  12. THE RECOVERY OF URANIUM FROM GAS MIXTURE

    DOEpatents

    Jury, S.H.

    1964-03-17

    A method of separating uranium from a mixture of uranium hexafluoride and other gases is described that comprises bringing the mixture into contact with anhydrous calcium sulfate to preferentially absorb the uranium hexafluoride on the sulfate. The calcium sulfate is then leached with a selective solvent for the adsorbed uranium. (AEC)

  13. Inferential determination of various properties of a gas mixture

    DOEpatents

    Morrow, Thomas B.; Behring, II, Kendricks A.

    2007-03-27

    Methods for inferentially determining various properties of a gas mixture, when the speed of sound in the gas is known at an arbitrary temperature and pressure. The method can be applied to natural gas mixtures, where the known parameters are the sound speed, temperature, pressure, and concentrations of any dilute components of the gas. The method uses a set of reference gases and their calculated density and speed of sound values to estimate the density of the subject gas. Additional calculations can be made to estimate the molecular weight of the subject gas, which can then be used as the basis for heating value calculations. The method may also be applied to inferentially determine density and molecular weight for gas mixtures other than natural gases.

  14. Devices for the Production of Reference Gas Mixtures.

    PubMed

    Fijało, Cyprian; Dymerski, Tomasz; Gębicki, Jacek; Namieśnik, Jacek

    2016-09-01

    For many years there has been growing demand for gaseous reference materials, which is connected with development in many fields of science and technology. As a result, new methodological and instrumental solutions appear that can be used for this purpose. Appropriate quality assurance/quality control (QA/QC) must be used to make sure that measurement data are a reliable source of information. Reference materials are a significant element of such systems. In the case of gas samples, such materials are generally called reference gas mixtures. This article presents the application and classification of reference gas mixtures, which are a specific type of reference materials, and the methods for obtaining them are described. Construction solutions of devices for the production of reference gas mixtures are detailed, and a description of a prototype device for dynamic production of reference gas mixtures containing aroma compounds is presented. PMID:27437588

  15. Devices for the Production of Reference Gas Mixtures.

    PubMed

    Fijało, Cyprian; Dymerski, Tomasz; Gębicki, Jacek; Namieśnik, Jacek

    2016-09-01

    For many years there has been growing demand for gaseous reference materials, which is connected with development in many fields of science and technology. As a result, new methodological and instrumental solutions appear that can be used for this purpose. Appropriate quality assurance/quality control (QA/QC) must be used to make sure that measurement data are a reliable source of information. Reference materials are a significant element of such systems. In the case of gas samples, such materials are generally called reference gas mixtures. This article presents the application and classification of reference gas mixtures, which are a specific type of reference materials, and the methods for obtaining them are described. Construction solutions of devices for the production of reference gas mixtures are detailed, and a description of a prototype device for dynamic production of reference gas mixtures containing aroma compounds is presented.

  16. Ion mobilities in Xe/Ne and other rare-gas mixtures.

    PubMed

    Piscitelli, D; Phelps, A V; de Urquijo, J; Basurto, E; Pitchford, L C

    2003-10-01

    The ion mobility or drift velocity data important for modeling glow discharges in rare gas mixtures are not generally available, nor are the ion-neutral scattering cross sections needed to calculate these data. In this paper we propose a set of cross sections for Xe+ and Ne+ collisions with Xe and Ne atoms. Ion mobilities at 300 K calculated using this cross section set in a Monte Carlo simulation are reported for reduced field strengths, E/N, up to 1500 x 10(-21) V m(2), in pure gases and in Xe/Ne mixtures containing 5% and 20% Xe/Ne, which are mixtures of interest for plasma display panels (PDPs). The calculated Xe+ mobilities depend strongly on the mixture composition, but the Ne+ mobility varies only slightly with increasing Xe in the mixture over the range studied here. The mobilities in pure gases compare well with available experimental values, and mobilities in gas mixtures at low E/N compare well with our recent measurements which will be published separately. Results from these calculations of ion mobilities are used to evaluate the predictions of Blanc's law and of the mixture rule proposed by Mason and Hahn [Phys. Rev. A 5, 438 (1972)] for determining the ion mobilities in mixtures from a knowledge of the mobilities in each of the pure gases. The mixture rule of Mason and Hahn is accurate to better than 10% at high field strengths over a wide range of conditions of interest for modeling PDPs. We conclude that a good estimate of ion mobilities at high E/N in Xe/Ne and other binary rare gas mixtures can be obtained using this mixture rule combined with known values of mobilities in parent gases and with the Langevin form for mobility of rare gas ions ion in other gases. This conclusion is supported by results in Ar/Ne mixtures which are also presented here.

  17. Thermal Conductivity of Gas Mixtures in Chemical Equilibrium

    NASA Technical Reports Server (NTRS)

    Brokaw, Richard S.

    1960-01-01

    The expression for the thermal conductivity of gas mixtures in chemical equilibrium is presented in a simpler and less restrictive form. This new form is shown to be equivalent to the previous equations.

  18. Composition for absorbing hydrogen from gas mixtures

    DOEpatents

    Heung, Leung K.; Wicks, George G.; Lee, Myung W.

    1999-01-01

    A hydrogen storage composition is provided which defines a physical sol-gel matrix having an average pore size of less than 3.5 angstroms which effectively excludes gaseous metal hydride poisons while permitting hydrogen gas to enter. The composition is useful for separating hydrogen gas from diverse gas streams which may have contaminants that would otherwise render the hydrogen absorbing material inactive.

  19. Lattice Boltzmann equation for microscale gas flows of binary mixtures.

    PubMed

    Guo, Zhaoli; Asinari, Pietro; Zheng, Chuguang

    2009-02-01

    Modeling and simulating gas flows in and around microdevices are a challenging task in both science and engineering. In practical applications, a gas is usually a mixture made of different components. In this paper we propose a lattice Boltzmann equation (LBE) model for microscale flows of a binary mixture based on a recently developed LBE model for continuum mixtures [P. Asinari and L.-S. Luo, J. Comput. Phys. 227, 3878 (2008)]. A consistent boundary condition for gas-solid interactions is proposed and analyzed. The LBE is validated and compared with theoretical results or other reported data. The results show that the model can serve as a potential method for flows of binary mixture in the microscale.

  20. Reduced viscosity interpreted for fluid/gas mixtures

    NASA Technical Reports Server (NTRS)

    Lewis, D. H.

    1981-01-01

    Analysis predicts decrease in fluid viscosity by comparing pressure profile of fluid/gas mixture with that of power-law fluid. Fluid is taken to be viscous, non-Newtonian, and incompressible; the gas to be ideal; the flow to be inertia-free, isothermal, and one dimensional. Analysis assists in design of flow systems for petroleum, coal, polymers, and other materials.

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    Studies of heat transfer and pressure drop of binary inert gas mixtures flowing through smooth concentric circular annuli, tubes with fully developed velocity profiles, and constant heating rate are described. There is a general lack of agreement among the constant property heat transfer correlations for such mixtures. No inert gas mixture data exist for annular channels. The intent of this study was to develop highly accurate and benchmarked pressure drop and heat transfer correlations that can be used to size heat exchangers and cores for direct gas Brayton nuclear power plants. The inside surface of the annular channel is heated while the outer surface of the channel is insulated. Annulus ratios range 0.5 < r* < 0.83. These smooth tube data may serve as a reference to the heat transfer and pressure drop performance in annuli, tubes, and channels having helixes or spacer ribs, or other surfaces.

  2. A novel technique for highly accurate gas exchange measurements

    NASA Astrophysics Data System (ADS)

    Kalkenings, R. K.; Jähne, B. J.

    2003-04-01

    The Heidelberg Aeolotron is a circular wind-wave facility for investigating air-sea gas exchange. In this contribution a novel technique for measuring highly accurate transfer velocities k of mass transfer will be presented. Traditionally, in mass balance techniques the constant of decay for gas concentrations over time is measured. The major drawback of this concept is the long time constant. At low wind speeds and a water height greater than 1 m the period of observation has to be several days. In a gas-tight facility such as the Aeolotron, the transfer velocity k can be computed from the concentration in the water body and the change of concentration in the gas space. Owing to this fact, transfer velocities are gained while greatly reducing the measuring times to less than one hour. The transfer velocity k of a tracer can be parameterized as k=1/β \\cdot u_* \\cdot Sc^n, with the Schmidt Number Sc, shear velocity u_* and the dimensionless transfer resistance β. The Schmidt Number exponent n can be derived from simultaneous measurements of different tracers. Since these tracers are of different Schmidt number, the shear velocity is not needed. To allow for Schmidt numbers spanning a hole decade, in our experiments He, H_2, N_2O and F12 are used. The relative accuracy of measuring the transfer velocity was improved to less than 2%. In 9 consecutive experiments conducted at a wind speed of 6.2 m/s, the deviation of the Schmidt number exponent was found to be just under 0.02. This high accuracy will allow precisely determining the transition of the Schmidt number exponent from n=2/3 to n=0.5 from a flat to wavy water surface. In order to quantify gas exchange not only the wind speed is important. Surfactants have a pronounced effect on the wave field and lead to a drastic reduction in the transfer velocity. In the Aeolotron measurements were conducted with a variety of measuring devices, ranging from an imaging slope gauge (ISG) to thermal techniques with IR

  3. Accurate measurement of the relative abundance of different DNA species in complex DNA mixtures.

    PubMed

    Jeong, Sangkyun; Yu, Hyunjoo; Pfeifer, Karl

    2012-06-01

    A molecular tool that can compare the abundances of different DNA sequences is necessary for comparing intergenic or interspecific gene expression. We devised and verified such a tool using a quantitative competitive polymerase chain reaction approach. For this approach, we adapted a competitor array, an artificially made plasmid DNA in which all the competitor templates for the target DNAs are arranged with a defined ratio, and melting analysis for allele quantitation for accurate quantitation of the fractional ratios of competitively amplified DNAs. Assays on two sets of DNA mixtures with explicitly known compositional structures of the test sequences were performed. The resultant average relative errors of 0.059 and 0.021 emphasize the highly accurate nature of this method. Furthermore, the method's capability of obtaining biological data is demonstrated by the fact that it can illustrate the tissue-specific quantitative expression signatures of the three housekeeping genes G6pdx, Ubc, and Rps27 by using the forms of the relative abundances of their transcripts, and the differential preferences of Igf2 enhancers for each of the multiple Igf2 promoters for the transcription.

  4. Accurate Measurement of the Relative Abundance of Different DNA Species in Complex DNA Mixtures

    PubMed Central

    Jeong, Sangkyun; Yu, Hyunjoo; Pfeifer, Karl

    2012-01-01

    A molecular tool that can compare the abundances of different DNA sequences is necessary for comparing intergenic or interspecific gene expression. We devised and verified such a tool using a quantitative competitive polymerase chain reaction approach. For this approach, we adapted a competitor array, an artificially made plasmid DNA in which all the competitor templates for the target DNAs are arranged with a defined ratio, and melting analysis for allele quantitation for accurate quantitation of the fractional ratios of competitively amplified DNAs. Assays on two sets of DNA mixtures with explicitly known compositional structures of the test sequences were performed. The resultant average relative errors of 0.059 and 0.021 emphasize the highly accurate nature of this method. Furthermore, the method's capability of obtaining biological data is demonstrated by the fact that it can illustrate the tissue-specific quantitative expression signatures of the three housekeeping genes G6pdx, Ubc, and Rps27 by using the forms of the relative abundances of their transcripts, and the differential preferences of Igf2 enhancers for each of the multiple Igf2 promoters for the transcription. PMID:22334570

  5. Determination of the concentration of SF 6 in an accelerator gas mixture by measuring the velocity of sound

    NASA Astrophysics Data System (ADS)

    Wilburn, W. S.; Gould, C. R.; Haase, D. G.; Hoffenberg, R. S.; Mioduszewski, S.; Roberson, N. R.

    1995-02-01

    A simple and reliable method for determining the concentration of SF 6 in an accelerator gas mixture with N 2 and CO 2 is described. The technique makes use of the low velocity of sound in SF 6 (approximately {1}/{3} that of air). The sound velocity of the mixture is determined by measuring the spacing of acoustic resonances in a tube filled with the gas. Data from standard gas mixtures containing 0-10% SF 6 are presented, showing that the technique is accurate to approximately 0.5% absolute.

  6. High severity pyrolysis of shale and petroleum gas oil mixtures

    SciTech Connect

    Leftin, H.P.; Newsome, D.S.

    1986-01-01

    Light gas oil and heavy gas oil from Paraho shale oil and their mixtures with a petroleum light gas oil were pyrolyzed in the presence of steam at 880-900/sup 0/C and contact times between 60 and 90 ms in a nonisothermal bench-scale pyrolysis reactor. Blending of petroleum LGO into the shale oil feeds provided product yields that were the weighted linear combination of the yields of the individual components of the blends. Partial denitrogenation and a pronounced decrease in the rate of coke deposition on the reactor walls were observed when petroleum gas oil was blended with the shale gas oils.

  7. Recovery of purified helium or hydrogen from gas mixtures

    DOEpatents

    Merriman, J.R.; Pashley, J.H.; Stephenson, M.J.; Dunthorn, D.I.

    1974-01-15

    A process is described for the removal of helium or hydrogen from gaseous mixtures also containing contaminants. The gaseous mixture is contacted with a liquid fluorocarbon in an absorption zone maintained at superatomspheric pressure to preferentially absorb the contaminants in the fluorocarbon. Unabsorbed gas enriched in hydrogen or helium is withdrawn from the absorption zone as product. Liquid fluorocarbon enriched in contaminants is withdrawn separately from the absorption zone. (10 claims)

  8. Gas sampling system for reactive gas-solid mixtures

    DOEpatents

    Daum, Edward D.; Downs, William; Jankura, Bryan J.; McCoury, Jr., John M.

    1989-01-01

    An apparatus and method for sampling a gas containing a reactive particulate solid phase flowing through a duct and for communicating a representative sample to a gas analyzer. A sample probe sheath 32 with an angular opening 34 extends vertically into a sample gas duct 30. The angular opening 34 is opposite the gas flow. A gas sampling probe 36 concentrically located within sheath 32 along with calibration probe 40 partly extend in the sheath 32. Calibration probe 40 extends further in the sheath 32 than gas sampling probe 36 for purging the probe sheath area with a calibration gas during calibration.

  9. Gas sampling system for reactive gas-solid mixtures

    DOEpatents

    Daum, Edward D.; Downs, William; Jankura, Bryan J.; McCoury, Jr., John M.

    1990-01-01

    An apparatus and method for sampling gas containing a reactive particulate solid phase flowing through a duct and for communicating a representative sample to a gas analyzer. A sample probe sheath 32 with an angular opening 34 extends vertically into a sample gas duct 30. The angular opening 34 is opposite the gas flow. A gas sampling probe 36 concentrically located within sheath 32 along with calibration probe 40 partly extends in the sheath 32. Calibration probe 40 extends further in the sheath 32 than gas sampling probe 36 for purging the probe sheath area with a calibration gas during calibration.

  10. Pulsed electron beam propagation in argon and nitrogen gas mixture

    NASA Astrophysics Data System (ADS)

    Kholodnaya, G. E.; Sazonov, R. V.; Ponomarev, D. V.; Remnev, G. E.; Zhirkov, I. S.

    2015-10-01

    The paper presents the results of current measurements for the electron beam, propagating inside a drift tube filled in with a gas mixture (Ar and N2). The experiments were performed using the TEA-500 pulsed electron accelerator. The main characteristics of electron beam were as follows: 60 ns pulse duration, up to 200 J energy, and 5 cm diameter. The electron beam propagated inside the drift tube assembled of three sections. Gas pressures inside the drift tube were 760 ± 3, 300 ± 3, and 50 ± 1 Torr. The studies were performed in argon, nitrogen, and their mixtures of 33%, 50%, and 66% volume concentrations, respectively.

  11. A new carrier gas type for accurate measurement of N2O by GC-ECD

    NASA Astrophysics Data System (ADS)

    Wang, Yinghong; Wang, Yuesi; Ling, Hong

    2010-11-01

    The accurate measurement of concentration is the basis for determining emission sources and sinks of nitrous oxide (N2O). The detection of N2O showed that the presence of carbon dioxide (CO2) biased the N2O response when pure nitrogen (N2) was used as a carrier gas for gas chromatography (GC) equipped with an electron capture detector (GC-ECD). In this study, laboratory experiments were carried out to explore how the presence of CO2 interferes with the accurate determination of N2O. The aims were to address the extent of the influence to try and explain the underlying mechanism, and to uncover technical options for solving the problem. Three GC carrier gases are discussed: pure nitrogen (DN); a mixture of argon and methane (AM); and a high concentration CO2, which was introduced into the ECD cell with a low flow rate based on DN (DN-CO2). The results show that when DN was used, the existence of CO2 in the ECD cell greatly enhanced the response of N2O, which increased with CO2 content and remained constant when the content reached a limit. Comparisons between the three methods show that the DN method is defective for the accurate determination of N2O. The bias is caused by different electron capture mechanisms of CO2 and N2O and depends heavily on the detector temperature. New GC carrier gas types with make-up gases that can remove the CO2-induced influence, such as the DN-CO2 and DN-CH4 methods reported in this paper, are recommended for the accurate measurement of N2O.

  12. Gas mixture studies for streamer operated Resistive Plate Chambers

    NASA Astrophysics Data System (ADS)

    Paoloni, A.; Longhin, A.; Mengucci, A.; Pupilli, F.; Ventura, M.

    2016-06-01

    Resistive Plate Chambers operated in streamer mode are interesting detectors in neutrino and astro-particle physics applications (like OPERA and ARGO experiments). Such experiments are typically characterized by large area apparatuses with no stringent requirements on detector aging and rate capabilities. In this paper, results of cosmic ray tests performed on a RPC prototype using different gas mixtures are presented, the principal aim being the optimization of the TetraFluoroPropene concentration in Argon-based mixtures. The introduction of TetraFluoroPropene, besides its low Global Warming Power, is helpful because it simplifies safety requirements allowing to remove also isobutane from the mixture. Results obtained with mixtures containing SF6, CF4, CO2, N2 and He are also shown, presented both in terms of detectors properties (efficiency, multiple-streamer probability and time resolution) and in terms of streamer characteristics.

  13. Handheld calculator program simplifies calculation of data for gas mixtures

    SciTech Connect

    Karger, W.

    1982-01-11

    For natural gases having several components, Elliott Co.'s handheld calculator program can characterize the gas mixture with a printout that provides its molecular weight, molar specific heat at constant pressure, pseudocritical pressure and temperature, ratio of specific heats, and adiabatic compression exponent. The program also provides for further calculations that yield specific gravity, specific heat/lb, and compressibility.

  14. Regularized moment equations for binary gas mixtures: Derivation and linear analysis

    NASA Astrophysics Data System (ADS)

    Gupta, Vinay Kumar; Struchtrup, Henning; Torrilhon, Manuel

    2016-04-01

    The applicability of the order of magnitude method [H. Struchtrup, "Stable transport equations for rarefied gases at high orders in the Knudsen number," Phys. Fluids 16, 3921-3934 (2004)] is extended to binary gas mixtures in order to derive various sets of equations—having minimum number of moments at a given order of accuracy in the Knudsen number—for binary mixtures of monatomic-inert-ideal gases interacting with the Maxwell interaction potential. For simplicity, the equations are derived in the linear regime up to third order accuracy in the Knudsen number. At zeroth order, the method produces the Euler equations; at first order, it results into the Fick, Navier-Stokes, and Fourier equations; at second order, it yields a set of 17 moment equations; and at third order, it leads to the regularized 17-moment equations. The transport coefficients in the Fick, Navier-Stokes, and Fourier equations obtained through order of magnitude method are compared with those obtained through the classical Chapman-Enskog expansion method. It is established that the different temperatures of different constituents do not play a role up to second order accurate theories in the Knudsen number, whereas they do contribute to third order accurate theory in the Knudsen number. Furthermore, it is found empirically that the zeroth, first, and second order accurate equations are linearly stable for all binary gas mixtures; however, although the third order accurate regularized 17-moment equations are linearly stable for most of the mixtures, they are linearly unstable for mixtures having extreme difference in molecular masses.

  15. Electrochemical separation and concentration of hydrogen sulfide from gas mixtures

    DOEpatents

    Winnick, Jack; Sather, Norman F.; Huang, Hann S.

    1984-10-30

    A method of removing sulfur oxides of H.sub.2 S from high temperature gas mixtures (150.degree.-1000.degree. C.) is the subject of the present invention. An electrochemical cell is employed. The cell is provided with inert electrodes and an electrolyte which will provide anions compatible with the sulfur containing anions formed at the anode. The electrolyte is also selected to provide inert stable cations at the temperatures encountered. The gas mixture is passed by the cathode where the sulfur gases are converted to SO.sub.4 -- or, in the case of H.sub.2 S, to S--. The anions migrate to the anode where they are converted to a stable gaseous form at much greater concentration levels (>10X). Current flow may be effected by utilizing an external source of electrical energy or by passing a reducing gas such as hydrogen past the anode.

  16. ELECTROCHEMICAL SEPARATION AND CONCENTRATION OF HYDROGEN SULFIDE FROM GAS MIXTURES

    DOEpatents

    Winnick, Jack; Sather, Norman F.; Huang, Hann S.

    1984-10-30

    A method of removing sulfur oxides of H.sub.2 S from high temperature gas mixtures (150.degree.-1000.degree. C.) is the subject of the present invention. An electrochemical cell is employed. The cell is provided with inert electrodes and an electrolyte which will provide anions compatible with the sulfur containing anions formed at the anode. The electrolyte is also selected to provide inert stable cations at the temperatures encountered. The gas mixture is passed by the cathode where the sulfur gases are converted to SO.sub.4 -- or, in the case of H.sub.2 S, to S--. The anions migrate to the anode where they are converted to a stable gaseous form at much greater concentration levels (>10X). Current flow may be effected by utilizing an external source of electrical energy or by passing a reducing gas such as hydrogen past the anode.

  17. Gravimetric methods for the preparation of standard gas mixtures

    NASA Astrophysics Data System (ADS)

    Milton, M. J. T.; Vargha, G. M.; Brown, A. S.

    2011-10-01

    The most widely used method for the preparation of primary standard gas mixtures involves weighing the individual components into a cylinder. We present a new mathematical description of the method and its uncertainties. We use this to demonstrate how strategies for serial dilution can be identified that minimize the uncertainty in the final mixture and show how they can be implemented practically. We review published reports of high accuracy gravimetry and give examples of relative uncertainties in the composition of standards approaching 1 part-per-million in the best cases and in the range of 100 to 1000 parts-per-million more typically.

  18. Calibration and uncertainty assessment for certified reference gas mixtures.

    PubMed

    Guenther, Franklin R; Possolo, Antonio

    2011-01-01

    The weighted least squares method to build an analysis function described in ISO 6143, Gas analysis--Comparison methods for determining and checking the composition of calibration gas mixtures, is modified to take into account the typically small number of instrumental readings that are obtained for each primary standard gas mixture used in calibration. The theoretical basis for this modification is explained, and its superior performance is illustrated in a simulation study built around a concrete example, using real data. The corresponding uncertainty assessment is obtained by application of a Monte Carlo method consistent with the guidance in the Supplement 1 to the Guide to the expression of uncertainty in measurement, which avoids the need for two successive applications of the linearizing approximation of the conventional method for uncertainty propagation. The three main steps that NIST currently uses to certify a reference gas mixture (homogeneity study, calibration, and assignment of value and uncertainty assessment), are described and illustrated using data pertaining to an actual standard reference material.

  19. Gas adsorption and gas mixture separations using mixed-ligand MOF material

    DOEpatents

    Hupp, Joseph T.; Mulfort, Karen L.; Snurr, Randall Q.; Bae, Youn-Sang

    2011-01-04

    A method of separating a mixture of carbon dioxiode and hydrocarbon gas using a mixed-ligand, metal-organic framework (MOF) material having metal ions coordinated to carboxylate ligands and pyridyl ligands.

  20. Pulsed electron beam propagation in argon and nitrogen gas mixture

    SciTech Connect

    Kholodnaya, G. E.; Sazonov, R. V.; Ponomarev, D. V.; Remnev, G. E.; Zhirkov, I. S.

    2015-10-15

    The paper presents the results of current measurements for the electron beam, propagating inside a drift tube filled in with a gas mixture (Ar and N{sub 2}). The experiments were performed using the TEA-500 pulsed electron accelerator. The main characteristics of electron beam were as follows: 60 ns pulse duration, up to 200 J energy, and 5 cm diameter. The electron beam propagated inside the drift tube assembled of three sections. Gas pressures inside the drift tube were 760 ± 3, 300 ± 3, and 50 ± 1 Torr. The studies were performed in argon, nitrogen, and their mixtures of 33%, 50%, and 66% volume concentrations, respectively.

  1. Diffusion and viscosity coefficients for helium. [in astrophysical gas mixtures

    NASA Technical Reports Server (NTRS)

    Roussel-Dupre, R.

    1982-01-01

    The first order Boltzmann-Fokker-Planck equation is solved numerically to obtain diffusion and viscosity coefficients for a ternary gas mixture composed of electron, protons, and helium. The coefficients are tabulated for five He/H abundances ranging from 0.01 to 10 and for both He II and He III. Comparison with Burgers's thermal diffusion coefficients reveals a maximum difference of 9-10% for both He II and He III throughout the range of helium abundances considered. The viscosity coefficients are compared to those of Chapman and Cowling and show a maximum difference of only 5-6% for He II but 15-16% for He III. For the astrophysically important gas mixtures, it is concluded that the results of existing studies which employed Burgers's or Chapman and Cowling's coefficients will remain substantially unaltered.

  2. Plasma polymerization of an ethylene-nitrogen gas mixture

    NASA Technical Reports Server (NTRS)

    Hudis, M.; Wydeven, T.

    1975-01-01

    A procedure has been developed whereby nitrogen can be incorporated into an organic film from an ethylene-nitrogen gas mixture using an internal electrode capacitively coupled radio frequency reactor. The presence of nitrogen has been shown directly by infrared transmittance spectra and electron spectroscopic chemical analysis data, and further indirect evidence was provided by dielectric measurements and by the reverse osmosis properties of the film. Preparation of a nitrogen containing film did not require vapor from an organic nitrogen containing liquid monomer. Some control over the bonding and stoichiometry of the polymer film was provided by the added degree of freedom of the nitrogen partial pressure in the gas mixture. This new parameter strongly affected the dielectric properties of the plasma polymerized film and could affect the reverse osmosis behavior.

  3. Deflagration to detonation transition in combustible gas mixtures

    SciTech Connect

    Smirnov, N.N.; Panfilov, I.I.

    1995-04-01

    This paper presents the results of a computational investigation of the process of deflagration to detonation transition in a combustible gas mixture. The type of combustion (i.e., deflagration or detonation) supported by a two-step reaction scheme is studied as a function of the activation energies. It is shown that both a deflagration to detonation transition and a deflagration wave that lags behind a leading shock are possible. Two types of deflagration to detonation transitions are found theoretically: initiation of detonation from the flame zone and initiation of detonation along a contact discontinuity in the compressed gas near the primary shock wave.

  4. Predicting detection probabilities for gas mixtures over HSI backgrounds

    SciTech Connect

    Tardiff, Mark F.; Walsh, Stephen J.; Anderson, Kevin K.; Chilton, Lawrence

    2009-12-29

    Detecting and identifying weak gaseous plumes using thermal image data acquired by airborne detectors is an area of ongoing research. This contribution investigates the relative detectability of gas mixtures over different backgrounds and a range of plume temperatures that are warmer and cooler than the ground. The focus of this analysis to support mission planning. When the mission is intended to collect evidence of particular chemicals, the analysis presented is this report can be used to determine conditions under which useful data can be acquired. Initial analyses can be used to determine whether LWIR is useful for the anticipated gas, temperature, and background combination.

  5. Separation of light gas mixtures using SAPO-34 membranes

    SciTech Connect

    Poshusta, J.C.; Tuan, V.A.; Pape, E.A.; Noble, R.D.; Falconer, J.L.

    2000-04-01

    Continuous SAPO-34 membranes were prepared on porous alumina tubular supports, and shown to be useful for light gas separations at low and high temperatures. Single-gas permeances of CO{sub 2}, N{sub 2} and CH{sub 4} decreased with increasing kinetic diameter. For the best membrane at 300 K, the He and H{sub 2} permeances were less than that of CO{sub 2}, because He, H{sub 2}, and CO{sub 2} were small compared to the SAPO-34 pore, and differences in the heat of adsorption determined the permeance order. The smaller component permeated the fastest in CO{sub 2}/CH{sub 4}, CO{sub 2}/N{sub 2}, N{sub 2}/CH{sub 4}, H{sub 2}/CH{sub 4} and H{sub 2}/N{sub 2} mixtures between 300 and 470 K. For H{sub 2}/CO{sub 2} mixtures, which were separated by competitive adsorption at room temperature, the larger component permeated faster below 400 K. The CO{sub 2}/CH{sub 4} selectivity at room temperature was 36 and decreased with temperature. The H{sub 2}/CH{sub 4} mixture selectivity was 8 and constant with temperature up to 480 K. Calcination, slow temperature cycles, and exposure to water vapor had no permanent effect on membrane performance, but temperature changes of approximately 30 K/min decreased the membrane's effectiveness.

  6. Accurate evaluation of homogenous and nonhomogeneous gas emissivities

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.; Lee, K. P.

    1984-01-01

    Spectral transmittance and total band adsorptance of selected infrared bands of carbon dioxide and water vapor are calculated by using the line-by-line and quasi-random band models and these are compared with available experimental results to establish the validity of the quasi-random band model. Various wide-band model correlations are employed to calculate the total band absorptance and total emissivity of these two gases under homogeneous and nonhomogeneous conditions. These results are compared with available experimental results under identical conditions. From these comparisons, it is found that the quasi-random band model can provide quite accurate results and is quite suitable for most atmospheric applications.

  7. Ternary gas mixtures for high-voltage industrial insulation

    NASA Astrophysics Data System (ADS)

    Pace, M. O.; Chan, C. C.; Christophorou, L. G.

    1981-10-01

    Gas dielectrics for insulating power apparatus, e.g., gas insulated transmission lines (GITL), were evaluated. Particular attention was given to mixtures using large proportions of an electron moderating gas (viz., N2, CHF3, or 1,1,1-C2H3F3) and smaller quantities of two electron attaching gases: SF6 and one fluorocarbon (e.g., c-C4F8). The proportions were sought at which the three gases function best as a team, moderating free electrons from higher to lower energies and there attaching them. Small amounts of the electron attaching additives can drastically raise the dielectric strength of the moderator. Certain combinations of SF6 and fluorocarbons do not produce the undesirable spark by products associated with either SF6 or fluorocarbons alone and also show improved negative polarity impulse breakdown characteristics over pure SF6. Small scale breakdown measurements were made of various ternary mixtures in the GITL geometry. It was found that nitrogen moderates electrons to extremely low energies, where SF6 attaches; the dipolar gases moderate to somewhat higher energies, where some fluorocarbons attach best.

  8. Binary and ternary gas mixtures for use in glow discharge closing switches

    DOEpatents

    Hunter, Scott R.; Christophorou, Loucas G.

    1990-01-01

    Highly efficient binary and ternary gas mixtures for use in diffuse glow discharge closing switches are disclosed. The binary mixtures are combinations of helium or neon and selected perfluorides. The ternary mixtures are combinations of helium, neon, or argon, a selected perfluoride, and a small amount of gas that exhibits enhanced ionization characteristics. These mixtures are shown to be the optimum choices for use in diffuse glow discharge closing switches by virtue of the combined physio-electric properties of the mixture components.

  9. Accurate boundary conditions for exterior problems in gas dynamics

    NASA Technical Reports Server (NTRS)

    Hagstrom, Thomas; Hariharan, S. I.

    1988-01-01

    The numerical solution of exterior problems is typically accomplished by introducing an artificial, far field boundary and solving the equations on a truncated domain. For hyperbolic systems, boundary conditions at this boundary are often derived by imposing a principle of no reflection. However, waves with spherical symmetry in gas dynamics satisfy equations where incoming and outgoing Riemann variables are coupled. This suggests that natural reflections may be important. A reflecting boundary condition is proposed based on an asymptotic solution of the far field equations. Nonlinear energy estimates are obtained for the truncated problem and numerical experiments presented to validate the theory.

  10. Accurate boundary conditions for exterior problems in gas dynamics

    NASA Technical Reports Server (NTRS)

    Hagstrom, Thomas; Hariharan, S. I.

    1988-01-01

    The numerical solution of exterior problems is typically accomplished by introducing an artificial, far-field boundary and solving the equations on a truncated domain. For hyperbolic systems, boundary conditions at this boundary are often derived by imposing a principle of no reflection. However, waves with spherical symmetry in gas dynamics satisfy equations where incoming and outgoing Riemann variables are coupled. This suggests that natural reflections may be important. A reflecting boundary condition is proposed based on an asymptotic solution of the far-field equations. Nonlinear energy estimates are obtained for the truncated problem and numerical experiments presented to validate the theory.

  11. Asymptotic-preserving Boltzmann model equations for binary gas mixture.

    PubMed

    Liu, Sha; Liang, Yihua

    2016-02-01

    An improved system of Boltzmann model equations is developed for binary gas mixture. This system of model equations has a complete asymptotic preserving property that can strictly recover the Navier-Stokes equations in the continuum limit with the correct constitutive relations and the correct viscosity, thermal conduction, diffusion, and thermal diffusion coefficients. In this equation system, the self- and cross-collision terms in Boltzmann equations are replaced by single relaxation terms. In monocomponent case, this system of equations can be reduced to the commonly used Shakhov equation. The conservation property and the H theorem which are important for model equations are also satisfied by this system of model equations. PMID:26986408

  12. Cellular detonation diffraction in gas-particle mixtures

    NASA Astrophysics Data System (ADS)

    Fedorov, A. V.; Khmel, T. A.; Kratova, Y. V.

    2010-12-01

    Diffraction of cellular heterogeneous detonation out of a channel into open half-space in a mixture of aluminum particles and oxygen is investigated numerically. The flow is found to be very similar to gas detonation diffraction. The detonation weakening behind the step results in combustion front deceleration and decoupling from the leading shock wave. Subsequent re-initiation takes place in a transverse wave. New transverse waves are generated along the expanding front. The computations that were performed show that the critical number of cells is several times less than that for gases. This is confirmed by theoretical estimates based upon the Mitrofanov-Soloukhin approach.

  13. Slurried solid media for simultaneous water purification and carbon dioxide removal from gas mixtures

    DOEpatents

    Aines, Roger D.; Bourcier, William L.; Viani, Brian

    2013-01-29

    A slurried solid media for simultaneous water purification and carbon dioxide removal from gas mixtures includes the steps of dissolving the gas mixture and carbon dioxide in water providing a gas, carbon dioxide, water mixture; adding a porous solid media to the gas, carbon dioxide, water mixture forming a slurry of gas, carbon dioxide, water, and porous solid media; heating the slurry of gas, carbon dioxide, water, and porous solid media producing steam; and cooling the steam to produce purified water and carbon dioxide.

  14. Stochastic PArallel Rarefied-gas Time-accurate Analyzer

    SciTech Connect

    Michael Gallis, Steve Plimpton

    2014-01-24

    The SPARTA package is software for simulating low-density fluids via the Direct Simulation Monte Carlo (DSMC) method, which is a particle-based method for tracking particle trajectories and collisions as a model of a multi-species gas. The main component of SPARTA is a simulation code which allows the user to specify a simulation domain, populate it with particles, embed triangulated surfaces as boundary conditions for the flow, overlay a grid for finding pairs of collision partners, and evolve the system in time via explicit timestepping. The package also includes various pre- and post-processing tools, useful for setting up simulations and analyzing the results. The simulation code runs either in serial on a single processor or desktop machine, or can be run in parallel using the MPI message-passing library, to enable faster performance on large problems.

  15. Stochastic PArallel Rarefied-gas Time-accurate Analyzer

    2014-01-24

    The SPARTA package is software for simulating low-density fluids via the Direct Simulation Monte Carlo (DSMC) method, which is a particle-based method for tracking particle trajectories and collisions as a model of a multi-species gas. The main component of SPARTA is a simulation code which allows the user to specify a simulation domain, populate it with particles, embed triangulated surfaces as boundary conditions for the flow, overlay a grid for finding pairs of collision partners,more » and evolve the system in time via explicit timestepping. The package also includes various pre- and post-processing tools, useful for setting up simulations and analyzing the results. The simulation code runs either in serial on a single processor or desktop machine, or can be run in parallel using the MPI message-passing library, to enable faster performance on large problems.« less

  16. Superconducting cable cooling system by helium gas and a mixture of gas and liquid helium

    DOEpatents

    Dean, John W.

    1977-01-01

    Thermally contacting, oppositely streaming cryogenic fluid streams in the same enclosure in a closed cycle that changes from a cool high pressure helium gas to a cooler reduced pressure helium fluid comprised of a mixture of gas and boiling liquid so as to be near the same temperature but at different pressures respectively in go and return legs that are in thermal contact with each other and in thermal contact with a longitudinally extending superconducting transmission line enclosed in the same cable enclosure that insulates the line from the ambient at a temperature T.sub.1. By first circulating the fluid in a go leg from a refrigerator at one end of the line as a high pressure helium gas near the normal boiling temperature of helium; then circulating the gas through an expander at the other end of the line where the gas becomes a mixture of reduced pressure gas and boiling liquid at its boiling temperature; then by circulating the mixture in a return leg that is separated from but in thermal contact with the gas in the go leg and in the same enclosure therewith; and finally returning the resulting low pressure gas to the refrigerator for compression into a high pressure gas at T.sub.2 is a closed cycle, where T.sub.1 >T.sub.2, the temperature distribution is such that the line temperature is nearly constant along its length from the refrigerator to the expander due to the boiling of the liquid in the mixture. A heat exchanger between the go and return lines removes the gas from the liquid in the return leg while cooling the go leg.

  17. Chemical discrimination in turbulent gas mixtures with MOX sensors validated by gas chromatography-mass spectrometry.

    PubMed

    Fonollosa, Jordi; Rodríguez-Luján, Irene; Trincavelli, Marco; Vergara, Alexander; Huerta, Ramón

    2014-10-16

    Chemical detection systems based on chemo-resistive sensors usually include a gas chamber to control the sample air flow and to minimize turbulence. However, such a kind of experimental setup does not reproduce the gas concentration fluctuations observed in natural environments and destroys the spatio-temporal information contained in gas plumes. Aiming at reproducing more realistic environments, we utilize a wind tunnel with two independent gas sources that get naturally mixed along a turbulent flow. For the first time, chemo-resistive gas sensors are exposed to dynamic gas mixtures generated with several concentration levels at the sources. Moreover, the ground truth of gas concentrations at the sensor location was estimated by means of gas chromatography-mass spectrometry. We used a support vector machine as a tool to show that chemo-resistive transduction can be utilized to reliably identify chemical components in dynamic turbulent mixtures, as long as sufficient gas concentration coverage is used. We show that in open sampling systems, training the classifiers only on high concentrations of gases produces less effective classification and that it is important to calibrate the classification method with data at low gas concentrations to achieve optimal performance.

  18. Chemical Discrimination in Turbulent Gas Mixtures with MOX Sensors Validated by Gas Chromatography-Mass Spectrometry

    PubMed Central

    Fonollosa, Jordi; Rodríguez-Luján, Irene; Trincavelli, Marco; Vergara, Alexander; Huerta, Ramón

    2014-01-01

    Chemical detection systems based on chemo-resistive sensors usually include a gas chamber to control the sample air flow and to minimize turbulence. However, such a kind of experimental setup does not reproduce the gas concentration fluctuations observed in natural environments and destroys the spatio-temporal information contained in gas plumes. Aiming at reproducing more realistic environments, we utilize a wind tunnel with two independent gas sources that get naturally mixed along a turbulent flow. For the first time, chemo-resistive gas sensors are exposed to dynamic gas mixtures generated with several concentration levels at the sources. Moreover, the ground truth of gas concentrations at the sensor location was estimated by means of gas chromatography-mass spectrometry. We used a support vector machine as a tool to show that chemo-resistive transduction can be utilized to reliably identify chemical components in dynamic turbulent mixtures, as long as sufficient gas concentration coverage is used. We show that in open sampling systems, training the classifiers only on high concentrations of gases produces less effective classification and that it is important to calibrate the classification method with data at low gas concentrations to achieve optimal performance. PMID:25325339

  19. A fluidic device for measuring constituent masses of a flowing binary gas mixture

    NASA Technical Reports Server (NTRS)

    Prokopius, P. R.

    1973-01-01

    A continuous reading mass flow device was developed to measure the component flow of a binary gas mixture. The basic components of the device are a fluidic humidity sensor and a specially designed flow calorimeter. These components provide readings of gas mixture ratio, mixture heat capacity, heat dissipated by the calorimeter and the gas temperature rise across the calorimeter. These parameter values, applied in the general definitions of specific heat capacity and the heat capacity of a gas mixture, produce calculated component flow rates of the mixture being metered. A test program was conducted to evaluate both the steady state and dynamic performance of the device.

  20. Operation of gas electron multiplier (GEM) with propane gas at low pressure and comparison with tissue-equivalent gas mixtures

    NASA Astrophysics Data System (ADS)

    De Nardo, L.; Farahmand, M.

    2016-05-01

    A Tissue-Equivalent Proportional Counter (TEPC), based on a single GEM foil of standard geometry, has been tested with pure propane gas at low pressure, in order to simulate a tissue site of about 1 μm equivalent size. In this work, the performance of GEM with propane gas at a pressure of 21 and 28 kPa will be presented. The effective gas gain was measured in various conditions using a 244Cm alpha source. The dependence of effective gain on the electric field strength along the GEM channel and in the drift and induction region was investigated. A maximum effective gain of about 5×103 has been reached. Results obtained in pure propane gas are compared with gas gain measurements in gas mixtures commonly employed in microdosimetry, that is propane and methane based Tissue-Equivalent gas mixtures.

  1. Enantiomeric separation in comprehensive two-dimensional gas chromatography with accurate mass analysis.

    PubMed

    Chin, Sung-Tong; Nolvachai, Yada; Marriott, Philip J

    2014-11-01

    Chiral comprehensive two-dimensional gas chromatography (eGC×GC) coupled to quadrupole-accurate mass time-of-flight mass spectrometry (QTOFMS) was evaluated for its capability to report the chiral composition of several monoterpenes, namely, α-pinene, β-pinene, and limonene in cardamom oil. Enantiomers in a standard mixture were fully resolved by direct enantiomeric-GC analysis with a 2,3-di-O-methyl-6-t-butylsilyl derivatized β-cyclodextrin phase; however, the (+)-(R)-limonene enantiomer in cardamom oil was overlapped with other background components including cymene and cineole. Verification of (+)-(R)-limonene components based on characteristic ions at m/z 136, 121, and 107 acquired by chiral single-dimension GC-QTOFMS in the alternate MS/MSMS mode of operation was unsuccessful due to similar parent/daughter ions generated by interfering or co-eluting cymene and cineole. Column phases SUPELCOWAX, SLB-IL111, HP-88, and SLB-IL59, were incorporated as the second dimension column ((2)D) in chiral GC×GC analysis; the SLB-IL59 offered the best resolution for the tested monoterpene enantiomers from the matrix background. Enantiomeric ratios for α-pinene, β-pinene, and limonene were determined to be 1.325, 2.703, and 1.040, respectively, in the cardamom oil sample based on relative peak area data. PMID:24420979

  2. Universal model for accurate calculation of tracer diffusion coefficients in gas, liquid and supercritical systems.

    PubMed

    Lito, Patrícia F; Magalhães, Ana L; Gomes, José R B; Silva, Carlos M

    2013-05-17

    In this work it is presented a new model for accurate calculation of binary diffusivities (D12) of solutes infinitely diluted in gas, liquid and supercritical solvents. It is based on a Lennard-Jones (LJ) model, and contains two parameters: the molecular diameter of the solvent and a diffusion activation energy. The model is universal since it is applicable to polar, weakly polar, and non-polar solutes and/or solvents, over wide ranges of temperature and density. Its validation was accomplished with the largest database ever compiled, namely 487 systems with 8293 points totally, covering polar (180 systems/2335 points) and non-polar or weakly polar (307 systems/5958 points) mixtures, for which the average errors were 2.65% and 2.97%, respectively. With regard to the physical states of the systems, the average deviations achieved were 1.56% for gaseous (73 systems/1036 points), 2.90% for supercritical (173 systems/4398 points), and 2.92% for liquid (241 systems/2859 points). Furthermore, the model exhibited excellent prediction ability. Ten expressions from the literature were adopted for comparison, but provided worse results or were not applicable to polar systems. A spreadsheet for D12 calculation is provided online for users in Supplementary Data.

  3. Enantiomeric separation in comprehensive two-dimensional gas chromatography with accurate mass analysis.

    PubMed

    Chin, Sung-Tong; Nolvachai, Yada; Marriott, Philip J

    2014-11-01

    Chiral comprehensive two-dimensional gas chromatography (eGC×GC) coupled to quadrupole-accurate mass time-of-flight mass spectrometry (QTOFMS) was evaluated for its capability to report the chiral composition of several monoterpenes, namely, α-pinene, β-pinene, and limonene in cardamom oil. Enantiomers in a standard mixture were fully resolved by direct enantiomeric-GC analysis with a 2,3-di-O-methyl-6-t-butylsilyl derivatized β-cyclodextrin phase; however, the (+)-(R)-limonene enantiomer in cardamom oil was overlapped with other background components including cymene and cineole. Verification of (+)-(R)-limonene components based on characteristic ions at m/z 136, 121, and 107 acquired by chiral single-dimension GC-QTOFMS in the alternate MS/MSMS mode of operation was unsuccessful due to similar parent/daughter ions generated by interfering or co-eluting cymene and cineole. Column phases SUPELCOWAX, SLB-IL111, HP-88, and SLB-IL59, were incorporated as the second dimension column ((2)D) in chiral GC×GC analysis; the SLB-IL59 offered the best resolution for the tested monoterpene enantiomers from the matrix background. Enantiomeric ratios for α-pinene, β-pinene, and limonene were determined to be 1.325, 2.703, and 1.040, respectively, in the cardamom oil sample based on relative peak area data.

  4. Accurate values of some thermodynamic properties for carbon dioxide, ethane, propane, and some binary mixtures.

    PubMed

    Velasco, Inmaculada; Rivas, Clara; Martínez-López, José F; Blanco, Sofía T; Otín, Santos; Artal, Manuela

    2011-06-30

    Quasicontinuous PρT data of CO(2), ethane, propane, and the [CO(2) + ethane] mixture have been determined along subcritical, critical, and supercritical regions. These data have been used to develop the optimal experimental method and to determine the precision of the results obtained when using an Anton Paar DMA HPM vibrating-tube densimeter. A comparison with data from reference EoS and other authors confirm the quality of our experimental setup, its calibration, and testing. For pure compounds, the value of the mean relative deviation is MRD(ρ) = 0.05% for the liquid phase and for the extended critical and supercritical region. For binary mixtures the mean relative deviation is MRD(ρ) = 0.70% in the range up to 20 MPa and MRD(ρ) = 0.20% in the range up to 70 MPa. The number of experimental points measured and their just quality have enable us to determine some derivated properties with satisfactory precision; isothermal compressibilities, κ(T), have been calculated for CO(2) and ethane (MRD(κ(T)) = 1.5%), isobaric expasion coefficients, α(P), and internal pressures, π(i), for CO(2) (MRD(α(P)) = 5% and MRD(π(i)) = 7%) and ethane (MRD(α(P)) = 7.5% and MRD(π(i)) = 8%). An in-depth discussion is presented on the behavior of the properties obtained along subcritical, critical, and supercritical regions. In addition, PuT values have been determined for water and compressed ethane from 273.19 to 463.26 K up to pressures of 190.0 MPa, using a device based on a 5 MHz pulsed ultrasonic system (MRD(u) = 0.1%). With these data we have calibrated the apparatus and have verified the adequacy of the operation with normal liquids as well as with some compressed gases. From density and speed of sound data of ethane, isentropic compressibilities, κ(s), have been obtained, and from these and our values for κ(T) and α(P), isobaric heat capacities, C(p), have been calculated with MRD(C(p)) = 3%, wich is within that of the EoS. PMID:21639086

  5. Fermion-fermion interaction in a dilute gas-mixture Bose condensate

    SciTech Connect

    Mogilyuk, T. I.

    2011-11-15

    A mixture of a one-component Bose gas and two-component Fermi gas is considered at temperatures at which the Bose gas is completely condensed. Two fermions in such a mixture can interact with each other exchanging bosons from the condensate or supercondensate. The interaction potential, a change in the effective mass, the decay, and fermion spectrum are calculated in this quantum Fermi-Bose mixture.

  6. Development of traceable precision dynamic dilution method to generate dimethyl sulphide gas mixtures at sub-nanomole per mole levels for ambient measurement.

    PubMed

    Kim, Mi Eon; Kim, Yong Doo; Kang, Ji Hwan; Heo, Gwi Suk; Lee, Dong Soo; Lee, Sangil

    2016-04-01

    Dimethyl sulphide (DMS) is an important compound in global atmospheric chemistry and climate change. Traceable international standards are essential for measuring accurately the long-term global trend in ambient DMS. However, developing accurate gas standards for sub-nanomole per mole (nmol/mol) mole fractions of DMS in a cylinder is challenging, because DMS is reactive and unstable. In this study, a dynamic dilution method that is traceable and precise was developed to generate sub-nmol/mol DMS gas mixtures with a dynamic dilution system based on sonic nozzles and a long-term (>5 years) stable 10 μmol/mol parent DMS primary standard gas mixtures (PSMs). The dynamic dilution system was calibrated with traceable methane PSMs, and its estimated dilution factors were used to calculate the mole fractions of the dynamically generated DMS gas mixtures. A dynamically generated DMS gas mixture and a 6 nmol/mol DMS PSM were analysed against each other by gas chromatography with flame-ionisation detection (GC/FID) to evaluate the dilution system. The mole fractions of the dynamically generated DMS gas mixture determined against a DMS PSM and calculated with the dilution factor agreed within 1% at 6 nmol/mol. In addition, the dynamically generated DMS gas mixtures at various mole fractions between 0.4 and 11.7 nmol/mol were analysed by GC/FID and evaluated for their linearity. The analytically determined mole fractions showed good linearity with the mole fractions calculated with the dilution factors. Results showed that the dynamic dilution method generates DMS gas mixtures ranging between 0.4 nmol/mol and 12 nmol/mol with relative expanded uncertainties of less than 2%. Therefore, the newly developed dynamic dilution method is a promising reference method for generating sub-nmol/mol DMS gas standards for accurate ambient measurements.

  7. Microwave-assisted generation of standard gas mixtures.

    PubMed

    Xiong, Guohua; Pawliszyn, Janusz

    2002-05-15

    Microwave heating was employed for preparation of the standard gas of volatile organic compounds (VOCs) and semivolatile organic compounds (semi-VOCs) by using a 1000 W commercial domestic microwave oven and 1 L gas-sampling bulbs. The VOCs investigated were benzene, chloroform, 1,3-dichlorobenzene, tetrachloroethylene, toluene, and 1,1,2-trichloroethane, and the semi-VOCs used were the polychlorinated biphenyls (PCBs) PCB 1016 and PCB 1248. Since these weakly or nonpolar molecules are very poor absorbers of microwave energy, an appropriate amount of water was introduced to accept microwave radiation and act as the thermal source to accelerate their evaporation. The glass bulb may also contribute thermal energy to the VOCs/semi-VOCs by accepting microwave energy to a small degree. For 0.5 microL of liquid VOCs on 10 mg of glass wool, it was shown that 15 microL of H2O and 60 s of microwave heating yielded a very efficient evaporation [97.2-106.4%, compared with a classic method (Muller, L; Gorecki, T.; Pawliszyn, J. Fresenius' J. Anal. Chem. 1999, 364, 610-616)]. For 1 microL of PCB solution (1000 microg/mL in hexane), 15 microL of H2O and 90 s of microwave heating also provided a complete evaporation. The addition of water was particularly significant for microwave-assisted evaporation of PCBs because semi-VOCs are much more difficult to evaporate than VOCs. This developed microwave technique proved to be quite simple, powerful, rapid, accurate, and safe for the preparation of VOC/semi-VOC standard gas. Solid- phase microextraction combined with gas chromatography was used for the gas analysis.

  8. 10 CFR 503.38 - Permanent exemption for certain fuel mixtures containing natural gas or petroleum.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... these regulations. (c) Solar mixtures. OFE will grant a permanent mixtures exemption for the use of a mixture of solar energy (including wind, tide, and other intermittent sources) and petroleum or natural gas, where: (1) Solar energy will account for at least 20 percent of the total annual Btu heat...

  9. 10 CFR 503.38 - Permanent exemption for certain fuel mixtures containing natural gas or petroleum.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... these regulations. (c) Solar mixtures. OFE will grant a permanent mixtures exemption for the use of a mixture of solar energy (including wind, tide, and other intermittent sources) and petroleum or natural gas, where: (1) Solar energy will account for at least 20 percent of the total annual Btu heat...

  10. Simultaneous resonant enhanced multiphoton ionization and electron avalanche ionization in gas mixtures

    SciTech Connect

    Shneider, Mikhail N.; Zhang Zhili; Miles, Richard B.

    2008-07-15

    Resonant enhanced multiphoton ionization (REMPI) and electron avalanche ionization (EAI) are measured simultaneously in Ar:Xe mixtures at different partial pressures of mixture components. A simple theory for combined REMPI+EAI in gas mixture is developed. It is shown that the REMPI electrons seed the avalanche process, and thus the avalanche process amplifies the REMPI signal. Possible applications are discussed.

  11. Quantitative Fourier transform infrared analysis of gas phase cigarette smoke and other gas mixtures

    SciTech Connect

    Cueto, R.; Church, D.F.; Pryor, W.A. )

    1989-03-01

    A new method for the analysis of selected components in complex gas mixtures has been developed utilizing a relatively inexpensive Fourier transform infrared spectrometer and a continuous flow gas cell. The method was used to monitor nitric oxide and nitrogen dioxide concentrations in cigarette smoke with time. Using multivariate least-square regression analysis, it is possible to simultaneously quantitate both NO and NO{sub 2}, even in the presence of overlapping peaks. Using this method, the oxidation of nitric oxide in the presence of isoprene in cigarette smoke and in a model system was followed with time. The method also can be applied to other compounds in smoke or to any other gaseous mixture.

  12. Binary and ternary gas mixtures for use in glow discharge closing switches

    DOEpatents

    Hunter, S.R.; Christophorou, L.G.

    1988-04-27

    Highly efficient binary and ternary gas mixtures for use in diffuse glow discharge closing switches are disclosed. The binary mixtures are combinations of helium or neon and selected perfluorides. The ternary mixtures are combinations of helium, neon, or argon, a selected perfluoride, and a small amount of gas that exhibits enhanced ionization characteristics. These mixtures are shown to be the optimum choices for use in diffuse glow discharge closing switches by virtue if the combines physio-electric properties of the mixture components. 9 figs.

  13. Argon-Hydrogen Shielding Gas Mixtures for Activating Flux-Assisted Gas Tungsten Arc Welding

    NASA Astrophysics Data System (ADS)

    Huang, Her-Yueh

    2010-11-01

    Using activating flux for gas tungsten arc welding (GTAW) to improve penetration capability is a well-established technique. Argon is an inert gas and the one most widely used as a shielding gas for GTAW. For the most austenitic stainless steels, pure argon does not provide adequate weld penetration. Argon-hydrogen mixtures give a more even heat input to the workpiece, increasing the arc voltage, which tends to increase the volume of molten material in the weld pool as well as the weld depth-to-width ratio. Great interest has been shown in the interaction between activating flux and the hydrogen concentration in an argon-based shielding gas. In this study, the weld morphology, the arc profile, the retained delta ferrite content, the angular distortion, and the microstructures were examined. The application of an activating flux combining argon and hydrogen for GTAW is important in the industry. The results of this study are presented here.

  14. Catalyst functionalized buffer sorbent pebbles for rapid separation of carbon dioxide from gas mixtures

    SciTech Connect

    Aines, Roger D

    2015-03-31

    A method for separating CO.sub.2 from gas mixtures uses a slurried media impregnated with buffer compounds and coating the solid media with a catalyst or enzyme that promotes the transformation of CO.sub.2 to carbonic acid. Buffer sorbent pebbles with a catalyst or enzyme coating are provided for rapid separation of CO.sub.2 from gas mixtures.

  15. Catalyst functionalized buffer sorbent pebbles for rapid separation of carbon dioxide from gas mixtures

    DOEpatents

    Aines, Roger D.

    2013-03-12

    A method for separating CO.sub.2 from gas mixtures uses a slurried media impregnated with buffer compounds and coating the solid media with a catalyst or enzyme that promotes the transformation of CO.sub.2 to carbonic acid. Buffer sorbent pebbles with a catalyst or enzyme coating are provided for rapid separation of CO.sub.2 from gas mixtures.

  16. Accurate coarse-grained models for mixtures of colloids and linear polymers under good-solvent conditions

    SciTech Connect

    D’Adamo, Giuseppe; Pelissetto, Andrea; Pierleoni, Carlo

    2014-12-28

    A coarse-graining strategy, previously developed for polymer solutions, is extended here to mixtures of linear polymers and hard-sphere colloids. In this approach, groups of monomers are mapped onto a single pseudoatom (a blob) and the effective blob-blob interactions are obtained by requiring the model to reproduce some large-scale structural properties in the zero-density limit. We show that an accurate parametrization of the polymer-colloid interactions is obtained by simply introducing pair potentials between blobs and colloids. For the coarse-grained (CG) model in which polymers are modelled as four-blob chains (tetramers), the pair potentials are determined by means of the iterative Boltzmann inversion scheme, taking full-monomer (FM) pair correlation functions at zero-density as targets. For a larger number n of blobs, pair potentials are determined by using a simple transferability assumption based on the polymer self-similarity. We validate the model by comparing its predictions with full-monomer results for the interfacial properties of polymer solutions in the presence of a single colloid and for thermodynamic and structural properties in the homogeneous phase at finite polymer and colloid density. The tetramer model is quite accurate for q ≲ 1 (q=R{sup ^}{sub g}/R{sub c}, where R{sup ^}{sub g} is the zero-density polymer radius of gyration and R{sub c} is the colloid radius) and reasonably good also for q = 2. For q = 2, an accurate coarse-grained description is obtained by using the n = 10 blob model. We also compare our results with those obtained by using single-blob models with state-dependent potentials.

  17. Dissipation process of binary gas mixtures in thermally relativistic flow

    NASA Astrophysics Data System (ADS)

    Yano, Ryosuke

    2016-04-01

    In this paper, dissipation process of binary gas mixtures in thermally relativistic flows is discussed with focus on characteristics of diffusion flux. As an analytical object, we consider the relativistic rarefied-shock layer around a triangular prism. Numerical results for the diffusion flux are compared with the Navier–Stokes–Fourier (NSF) order approximation of the diffusion flux, which is calculated using the diffusion and thermal-diffusion coefficients by Kox et al (1976 Physica A 84 165–74). In the case of uniform flow with small Lorentz contraction, the diffusion flux, which is obtained by calculating the relativistic Boltzmann equation, is roughly approximated by the NSF order approximation inside the shock wave, whereas the diffusion flux in the vicinity of a wall is markedly different from the NSF order approximation. The magnitude of the diffusion flux, which is obtained by calculating the relativistic Boltzmann equation, is similar to that of the NSF order approximation inside the shock wave, unlike the pressure deviator, dynamic pressure and heat flux, even when the Lorentz contraction in the uniform flow becomes large, because the diffusion flux does not depend on the generic Knudsen number from its definition in Eckart’s frame. Finally, the author concludes that for accuracy diffusion flux must be calculated using the particle four-flow and averaged four velocity, which are formulated using the four velocity defined by each species of hard spherical particles.

  18. Dissipation process of binary gas mixtures in thermally relativistic flow

    NASA Astrophysics Data System (ADS)

    Yano, Ryosuke

    2016-04-01

    In this paper, dissipation process of binary gas mixtures in thermally relativistic flows is discussed with focus on characteristics of diffusion flux. As an analytical object, we consider the relativistic rarefied-shock layer around a triangular prism. Numerical results for the diffusion flux are compared with the Navier-Stokes-Fourier (NSF) order approximation of the diffusion flux, which is calculated using the diffusion and thermal-diffusion coefficients by Kox et al (1976 Physica A 84 165-74). In the case of uniform flow with small Lorentz contraction, the diffusion flux, which is obtained by calculating the relativistic Boltzmann equation, is roughly approximated by the NSF order approximation inside the shock wave, whereas the diffusion flux in the vicinity of a wall is markedly different from the NSF order approximation. The magnitude of the diffusion flux, which is obtained by calculating the relativistic Boltzmann equation, is similar to that of the NSF order approximation inside the shock wave, unlike the pressure deviator, dynamic pressure and heat flux, even when the Lorentz contraction in the uniform flow becomes large, because the diffusion flux does not depend on the generic Knudsen number from its definition in Eckart’s frame. Finally, the author concludes that for accuracy diffusion flux must be calculated using the particle four-flow and averaged four velocity, which are formulated using the four velocity defined by each species of hard spherical particles.

  19. Metastable sound speed in gas-liquid mixtures

    NASA Technical Reports Server (NTRS)

    Bursik, J. W.; Hall, R. M.

    1979-01-01

    A new method of calculating speed of sound for two-phase flow is presented. The new equation assumes no phase change during the propagation of an acoustic disturbance and assumes that only the total entropy of the mixture remains constant during the process. The new equation predicts single-phase values for the speed of sound in the limit of all gas or all liquid and agrees with available two-phase, air-water sound speed data. Other expressions used in the two-phase flow literature for calculating two-phase, metastable sound speed are reviewed and discussed. Comparisons are made between the new expression and several of the previous expressions -- most notably a triply isentropic equation as used, a triply isentropic equation as used, among others, by Karplus and by Wallis. Appropriate differences are pointed out and a thermodynamic criterion is derived which must be satisfied in order for the triply isentropic expression to be thermodynamically consistent. This criterion is not satisfied for the cases examined, which included two-phase nitrogen, air-water, two-phase parahydrogen, and steam-water. Consequently, the new equation derived is found to be superior to the other equations reviewed.

  20. Flammability of selected heat resistant alloys in oxygen gas mixtures

    SciTech Connect

    Zawierucha, R.; McIlroy, K.; Million, J.F.

    1995-12-31

    Within recent years, the use of oxygen has increased in applications where elevated temperatures and corrosion may be significant factors. In such situations, traditional alloys used in oxygen systems will not be adequate. Where alternative alloys must be utilized, based upon environmental requirements, it is essential that they may be characterized with respect to their ignition and combustion resistance in oxygen. Promoted ignition and promoted ignition-combustion are terms which have been used to describe a situation where a substance with low oxygen supports the combustion of a compatibility ignites and more ignition resistant material. In this paper, data will be presented on the promoted ignition-combustion behavior of selected heat resistant engineering alloys that may be considered for gaseous oxygen applications in severe environments. In this investigation, alloys have been evaluated via both flowing and static (fixed volume) approaches using a rod configuration. Oxygen-nitrogen gas mixtures with compositions ranging from approximately 40 to 99.7% oxygen at pressures of 3.55 to 34.6 MPa were used in the comparative studies.

  1. Response of tomato plants to simulated landfill gas mixtures

    SciTech Connect

    Arthur, J.J.; Leone, I.A.; Flower, F.B.

    1985-01-01

    The roots of tomato plants were fumigated with simulated refuse-generated gas mixtures at levels of methane (CH/sub 4/), carbon dioxide (CO/sub 2/), and oxygen (O/sub 2/) previously measured in the atmospheres of landfill cover soils associated with poor growth or death of plants. A concentration of 18% CO/sub 2/ or greater, exceeded in almost 30% of thirty-two landfills examined throughout the US, caused reduced growth and visible symptoms on tomato after 1 wk, regardless of O/sub 2/ level. Doubling the CO/sub 2/ level to that encountered in a typical local site (Edgeboro Landfill) resulted in more severe symptom development and the subsequent death of plants. Methane, in concentrations of 20% and above, found in more than 25% of the landfills visited, while not observed to be toxic per se; was associated with drastic O/sub 2/ depletion in the soil atmosphere, which activity was believed to be the cause of the plant decline.

  2. Stability assessment of gas mixtures containing monoterpenes in varying cylinder materials and treatments.

    PubMed

    Rhoderick, George C; Lin, Janice

    2013-05-01

    Studies of climate change increasingly recognize the diverse influences exerted by monoterpenes in the atmosphere, including roles in particulates, ozone formation, and oxidizing potential. Measurements of key monoterpenes suggest atmospheric mole fractions ranging from low pmol/mol (parts-per-trillion; ppt) to nmol/mol (parts-per-billion; ppb), depending on location and compound. To accurately establish the mole fraction trends, assess the role of monoterpenes in atmospheric chemistry, and relate measurement records from many laboratories and researchers, it is essential to have good calibration standards. The feasibility of preparing well-characterized, stable gas cylinder standards for monoterpenes at the nmol/mol level was previously tested using treated (Aculife IV) aluminum gas cylinders at NIST. Results for 4 of the 11 monoterpenes, monitored versus an internal standard of benzene, indicated stability in these treated aluminum gas cylinders for over 6 months and projected long-term (years) stability. However, the mole fraction of the key monoterpene β-pinene decreased, while the mole fractions of α-pinene, d-limonene (R-(+)-limonene), p-cymene, and camphene (a terpene not present in the initial gas mixture) increased, indicating a chemical transformation of β-pinene to these species. A similar pattern of decreasing mole fraction was observed in α-pinene where growth of d-limonene, p-cymene, and camphene has been observed in treated gas cylinders prepared with a mixture of just α-pinene and benzene as the internal standard. The current research discusses the testing of other cylinders and treatments for the potential of long-term stability of monoterpenes in a gas mixture. In this current study, a similar pattern of decreasing mole fraction, although somewhat improved short-term stability, was observed for β-pinene and α-pinene, with growth of d-limonene, p-cymene, and camphene, in nickel-plated carbon steel cylinders. β-Pinene and α-pinene showed

  3. The nonlinear model for emergence of stable conditions in gas mixture in force field

    NASA Astrophysics Data System (ADS)

    Kalutskov, Oleg; Uvarova, Liudmila

    2016-06-01

    The case of M-component liquid evaporation from the straight cylindrical capillary into N - component gas mixture in presence of external forces was reviewed. It is assumed that the gas mixture is not ideal. The stable states in gas phase can be formed during the evaporation process for the certain model parameter valuesbecause of the mass transfer initial equationsnonlinearity. The critical concentrations of the resulting gas mixture components (the critical component concentrations at which the stable states occur in mixture) were determined mathematically for the case of single-component fluid evaporation into two-component atmosphere. It was concluded that this equilibrium concentration ratio of the mixture components can be achieved by external force influence on the mass transfer processes. It is one of the ways to create sustainable gas clusters that can be used effectively in modern nanotechnology.

  4. Gas-phase detonation propagation in mixture composition gradients.

    PubMed

    Kessler, D A; Gamezo, V N; Oran, E S

    2012-02-13

    The propagation of detonations through several fuel-air mixtures with spatially varying fuel concentrations is examined numerically. The detonations propagate through two-dimensional channels, inside of which the gradient of mixture composition is oriented normal to the direction of propagation. The simulations are performed using a two-component, single-step reaction model calibrated so that one-dimensional detonation properties of model low- and high-activation-energy mixtures are similar to those observed in a typical hydrocarbon-air mixture. In the low-activation-energy mixture, the reaction zone structure is complex, consisting of curved fuel-lean and fuel-rich detonations near the line of stoichiometry that transition to decoupled shocks and turbulent deflagrations near the channel walls where the mixture is extremely fuel-lean or fuel-rich. Reactants that are not consumed by the leading detonation combine downstream and burn in a diffusion flame. Detonation cells produced by the unstable reaction front vary in size across the channel, growing larger away from the line of stoichiometry. As the size of the channel decreases relative to the size of a detonation cell, the effect of the mixture composition gradient is lessened and cells of similar sizes form. In the high-activation-energy mixture, detonations propagate more slowly as the magnitude of the mixture composition gradient is increased and can be quenched in a large enough gradient. PMID:22213660

  5. 49 CFR 173.305 - Charging of cylinders with a mixture of compressed gas and other material.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... nonflammable mixtures. Mixtures containing compressed gas or gases including insecticides, which mixtures are... relief devices of a type examined by the Bureau of Explosives and approved by the Associate...

  6. 49 CFR 173.305 - Charging of cylinders with a mixture of compressed gas and other material.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... nonflammable mixtures. Mixtures containing compressed gas or gases including insecticides, which mixtures are... relief devices of a type examined by the Bureau of Explosives and approved by the Associate...

  7. 49 CFR 173.305 - Charging of cylinders with a mixture of compressed gas and other material.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... nonflammable mixtures. Mixtures containing compressed gas or gases including insecticides, which mixtures are... relief devices of a type examined by the Bureau of Explosives and approved by the Associate...

  8. 49 CFR 173.305 - Charging of cylinders with a mixture of compressed gas and other material.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... nonflammable mixtures. Mixtures containing compressed gas or gases including insecticides, which mixtures are... relief devices of a type examined by the Bureau of Explosives and approved by the Associate...

  9. 49 CFR 173.305 - Charging of cylinders with a mixture of compressed gas and other material.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... nonflammable mixtures. Mixtures containing compressed gas or gases including insecticides, which mixtures are... relief devices of a type examined by the Bureau of Explosives and approved by the Associate...

  10. The impact of air-fuel mixture composition on SI engine performance during natural gas and producer gas combustion

    NASA Astrophysics Data System (ADS)

    Przybyła, G.; Postrzednik, S.; Żmudka, Z.

    2016-09-01

    The paper summarizers results of experimental tests of SI engine fuelled with gaseous fuels such as, natural gas and three mixtures of producer gas substitute that simulated real producer gas composition. The engine was operated under full open throttle and charged with different air-fuel mixture composition (changed value of air excess ratio). The spark timing was adjusted to obtain maximum brake torque (MBT) for each fuel and air-fuel mixture. This paper reports engine indicated performance based on in-cylinder, cycle resolved pressure measurements. The engine performance utilizing producer gas in terms of indicated efficiency is increased by about 2 percentage points when compared to fuelling with natural gas. The engine power de-rating when producer gas is utilized instead the natural gas, varies from 24% to 28,6% under stoichiometric combustion conditions. For lean burn (λ=1.5) the difference are lower and varies from 22% to 24.5%.

  11. Analysis of Trace Gas Mixtures Using an External Cavity Quantum Cascade Laser Sensor

    SciTech Connect

    Phillips, Mark C.; Taubman, Matthew S.; Brumfield, Brian E.; Kriesel, Jason M.

    2015-07-01

    We measure and analyze mixtures of trace gases at ppb-ppm levels using an external cavity quantum cascade laser sensor with a 1-second response time. Accurate spectral fits are obtained in the presence of overlapping spectra.

  12. 30 CFR 75.1106-6 - Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures. 75.1106-6 Section 75.1106-6 Mineral Resources MINE... STANDARDS-UNDERGROUND COAL MINES Fire Protection § 75.1106-6 Exemption of small low pressure gas...

  13. 30 CFR 75.1106-6 - Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures. 75.1106-6 Section 75.1106-6 Mineral Resources MINE... STANDARDS-UNDERGROUND COAL MINES Fire Protection § 75.1106-6 Exemption of small low pressure gas...

  14. 30 CFR 75.1106-6 - Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures. 75.1106-6 Section 75.1106-6 Mineral Resources MINE... STANDARDS-UNDERGROUND COAL MINES Fire Protection § 75.1106-6 Exemption of small low pressure gas...

  15. 30 CFR 75.1106-6 - Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures. 75.1106-6 Section 75.1106-6 Mineral Resources MINE... STANDARDS-UNDERGROUND COAL MINES Fire Protection § 75.1106-6 Exemption of small low pressure gas...

  16. 30 CFR 75.1106-6 - Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures. 75.1106-6 Section 75.1106-6 Mineral Resources MINE... STANDARDS-UNDERGROUND COAL MINES Fire Protection § 75.1106-6 Exemption of small low pressure gas...

  17. Falling microbead counter-flow process for separating gas mixtures

    SciTech Connect

    Hornbostel, Marc D.; Krishnan, Gopala N.; Sanjurjo, Angel

    2015-07-07

    A method and reactor for removing a component from a gas stream is provided. In one embodiment, the method includes providing the gas stream containing the component that is to be removed and adsorbing the component out of the gas stream as the gas stream rises via microbeads of a sorbent falling down an adsorber section of a reactor.

  18. Falling microbead counter-flow process for separating gas mixtures

    SciTech Connect

    Hornbostel, Marc D.; Krishnan, Gopala N.; Sanjurjo, Angel

    2015-10-27

    A method and reactor for removing a component from a gas stream is provided. In one embodiment, the method includes providing the gas stream containing the component that is to be removed and adsorbing the component out of the gas stream as the gas stream rises via microbeads of a sorbent falling down an adsorber section of a reactor.

  19. Calculation of the relative speed of sound in a gas mixture.

    PubMed

    Ackerman, M J; Maitland, G

    1975-12-01

    Since the frequency spectrum of a voice signal is directly dependent on the velocity of sound, studies of speech spectra include the problem of calculating the speed of sound in the gas mixture being used. A computer program written in BASIC has been developed to calculate the speed of sound relative to air in various diving gas mixtures. In addition, a set of tables available as a separate technical report has been generated using this program. These tables are designed to provide a standard reference for reporting spectral shifts in speech due to different gas mixtures under normal diving conditions. PMID:1226588

  20. Process for the separation of components from gas mixtures

    DOEpatents

    Merriman, J.R.; Pashley, J.H.; Stephenson, M.J.; Dunthorn, D.I.

    1973-10-01

    A process for the removal, from gaseous mixtures of a desired component selected from oxygen, iodine, methyl iodide, and lower oxides of carbon, nitrogen, and sulfur is described. The gaseous mixture is contacted with a liquid fluorocarbon in an absorption zone maintained at superatmospheric pressure to preferentially absorb the desired component in the fluorocarbon. Unabsorbed constituents of the gaseous mixture are withdrawn from the absorption zone. Liquid fluorocarbon enriched in the desired component is withdrawn separately from the zone, following which the desired component is recovered from the fluorocarbon absorbent. (Official Gazette)

  1. Modeling high-pressure adsorption of gas mixtures on activated carbon and coal using a simplified local-density model.

    PubMed

    Fitzgerald, James E; Robinson, Robert L; Gasem, Khaled A M

    2006-11-01

    The simplified local-density (SLD) theory was investigated regarding its ability to provide accurate representations and predictions of high-pressure supercritical adsorption isotherms encountered in coalbed methane (CBM) recovery and CO2 sequestration. Attention was focused on the ability of the SLD theory to predict mixed-gas adsorption solely on the basis of information from pure gas isotherms using a modified Peng-Robinson (PR) equation of state (EOS). An extensive set of high-pressure adsorption measurements was used in this evaluation. These measurements included pure and binary mixture adsorption measurements for several gas compositions up to 14 MPa for Calgon F-400 activated carbon and three water-moistened coals. Also included were ternary measurements for the activated carbon and one coal. For the adsorption of methane, nitrogen, and CO2 on dry activated carbon, the SLD-PR can predict the component mixture adsorption within about 2.2 times the experimental uncertainty on average solely on the basis of pure-component adsorption isotherms. For the adsorption of methane, nitrogen, and CO2 on two of the three wet coals, the SLD-PR model can predict the component adsorption within the experimental uncertainties on average for all feed fractions (nominally molar compositions of 20/80, 40/60, 60/40, and 80/20) of the three binary gas mixture combinations, although predictions for some specific feed fractions are outside of their experimental uncertainties. PMID:17073487

  2. GAS CHROMATOGRAPHIC RETENTION PARAMETERS DATABASE FOR REFRIGERANT MIXTURE COMPOSITION MANAGEMENT

    EPA Science Inventory

    Composition management of mixed refrigerant systems is a challenging problem in the laboratory, manufacturing facilities, and large refrigeration machinery. Ths issue of composition management is especially critical for the maintenance of machinery that utilizes zeotropic mixture...

  3. Effect of noble gas mixtures on the performance of regenerative-type cryocoolers analytical estimate

    NASA Astrophysics Data System (ADS)

    Daney, D. E.

    1990-09-01

    The performance of regenerators that use noble gas mixtures is compared to the performance of those that use pure helium gas. Both helium-argon and helium-krypton mixtures are investigated. For some heat transfer surfaces, a modest gain in heat transfer can be achieved with these mixtures. The concomitant increase in pressure drop, however, more than offsets the heat transfer gain so the net regenerator loss increases for all evaluated cases. The dependence of heat transfer on Prandtl number (Pr) was not measured for the range associated with noble gas mixtures, 0.2 less than Pr less than 0.5, and it is estimated that the uncertainty from the source can exceed 20 percent. The estimates for the transport properties (Prandtl number, viscosity, and thermal conductivity) of helium-argon and helium-krypton mixtures because of the absence of experimental data at low temperature are given.

  4. Minimum Error Fickian Diffusion Coefficients for Mass Diffusion in Multicomponent Gas Mixtures

    NASA Astrophysics Data System (ADS)

    Subramaniam, S.

    1999-04-01

    Mass diffusion in multicomponent gas mixtures is governed by a coupled system of linear equations for the diffusive mass fluxes in terms of thermodynamic driving forces, known as the generalized Stefan-Maxwell equation. In computations of mass diffusion in multicomponent gas mixtures, this coupling between the different components results in considerable computational overhead. Consequently, simplified diffusion models for the diffusive mass fluxes as explicit functions of the driving forces are an attractive alternative. These models can be interpreted as an approximate solution to the Stefan-Maxwell equation. Simplified diffusion models require the specification of “effective” diffusion coefficients which are usually expressed as functions of the binary diffusion coefficients of each species pair in the mixture. Current models for the effective diffusion coefficients are incapable of providing a priori control over the error incurred in the approximate solution. In this paper a general form for diagonal approximations is derived, which accounts for the requirement imposed by the special structure of the Stefan-Maxwell equation that such approximations be constructed in a reduced-dimensional subspace. In addition, it is shown that current models can be expressed as particular cases of two general forms, but not all these models correspond to the general form for diagonal approximations. A new minimum error diagonal approximation (MEDA) model is proposed, based on the criterion that the diagonal approximation minimize the error in the species velocities. Analytic expressions are derived for the MEDA model's effective diffusion coefficients based on this criterion. These effective diffusion coefficients automatically give the correct solution in two important limiting cases: for that of a binary mixture, and for the case of arbitrary number of components with identical binary diffusivities. Although these minimum error effective diffusion

  5. PolyPole-1: An accurate numerical algorithm for intra-granular fission gas release

    NASA Astrophysics Data System (ADS)

    Pizzocri, D.; Rabiti, C.; Luzzi, L.; Barani, T.; Van Uffelen, P.; Pastore, G.

    2016-09-01

    The transport of fission gas from within the fuel grains to the grain boundaries (intra-granular fission gas release) is a fundamental controlling mechanism of fission gas release and gaseous swelling in nuclear fuel. Hence, accurate numerical solution of the corresponding mathematical problem needs to be included in fission gas behaviour models used in fuel performance codes. Under the assumption of equilibrium between trapping and resolution, the process can be described mathematically by a single diffusion equation for the gas atom concentration in a grain. In this paper, we propose a new numerical algorithm (PolyPole-1) to efficiently solve the fission gas diffusion equation in time-varying conditions. The PolyPole-1 algorithm is based on the analytic modal solution of the diffusion equation for constant conditions, combined with polynomial corrective terms that embody the information on the deviation from constant conditions. The new algorithm is verified by comparing the results to a finite difference solution over a large number of randomly generated operation histories. Furthermore, comparison to state-of-the-art algorithms used in fuel performance codes demonstrates that the accuracy of PolyPole-1 is superior to other algorithms, with similar computational effort. Finally, the concept of PolyPole-1 may be extended to the solution of the general problem of intra-granular fission gas diffusion during non-equilibrium trapping and resolution, which will be the subject of future work.

  6. Chemically accurate energy barriers of small gas molecules moving through hexagonal water rings.

    PubMed

    Hjertenæs, Eirik; Trinh, Thuat T; Koch, Henrik

    2016-07-21

    We present chemically accurate potential energy curves of CH4, CO2 and H2 moving through hexagonal water rings, calculated by CCSD(T)/aug-cc-pVTZ with counterpoise correction. The barriers are extracted from a potential energy surface obtained by allowing the water ring to expand while the gas molecule diffuses through. State-of-the-art XC-functionals are evaluated against the CCSD(T) potential energy surface.

  7. Oxygen sensor for monitoring gas mixtures containing hydrocarbons

    DOEpatents

    Ruka, Roswell J.; Basel, Richard A.

    1996-01-01

    A gas sensor measures O.sub.2 content of a reformable monitored gas containing hydrocarbons H.sub.2 O and/or CO.sub.2, preferably in association with an electrochemical power generation system. The gas sensor has a housing communicating with the monitored gas environment and carries the monitored gas through an integral catalytic hydrocarbon reforming chamber containing a reforming catalyst, and over a solid electrolyte electrochemical cell used for sensing purposes. The electrochemical cell includes a solid electrolyte between a sensor electrode that is exposed to the monitored gas, and a reference electrode that is isolated in the housing from the monitored gas and is exposed to a reference gas environment. A heating element is also provided in heat transfer communication with the gas sensor. A circuit that can include controls operable to adjust operations via valves or the like is connected between the sensor electrode and the reference electrode to process the electrical signal developed by the electrochemical cell. The electrical signal varies as a measure of the equilibrium oxygen partial pressure of the monitored gas. Signal noise is effectively reduced by maintaining a constant temperature in the area of the electrochemical cell and providing a monitored gas at chemical equilibria when contacting the electrochemical cell. The output gas from the electrochemical cell of the sensor is fed back into the conduits of the power generating system.

  8. Oxygen sensor for monitoring gas mixtures containing hydrocarbons

    DOEpatents

    Ruka, R.J.; Basel, R.A.

    1996-03-12

    A gas sensor measures O{sub 2} content of a reformable monitored gas containing hydrocarbons, H{sub 2}O and/or CO{sub 2}, preferably in association with an electrochemical power generation system. The gas sensor has a housing communicating with the monitored gas environment and carries the monitored gas through an integral catalytic hydrocarbon reforming chamber containing a reforming catalyst, and over a solid electrolyte electrochemical cell used for sensing purposes. The electrochemical cell includes a solid electrolyte between a sensor electrode that is exposed to the monitored gas, and a reference electrode that is isolated in the housing from the monitored gas and is exposed to a reference gas environment. A heating element is also provided in heat transfer communication with the gas sensor. A circuit that can include controls operable to adjust operations via valves or the like is connected between the sensor electrode and the reference electrode to process the electrical signal developed by the electrochemical cell. The electrical signal varies as a measure of the equilibrium oxygen partial pressure of the monitored gas. Signal noise is effectively reduced by maintaining a constant temperature in the area of the electrochemical cell and providing a monitored gas at chemical equilibria when contacting the electrochemical cell. The output gas from the electrochemical cell of the sensor is fed back into the conduits of the power generating system. 4 figs.

  9. 10 CFR 503.38 - Permanent exemption for certain fuel mixtures containing natural gas or petroleum.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... mixture of solar energy (including wind, tide, and other intermittent sources) and petroleum or natural gas, where: (1) Solar energy will account for at least 20 percent of the total annual Btu heat input... 10 Energy 4 2013-01-01 2013-01-01 false Permanent exemption for certain fuel mixtures...

  10. 10 CFR 503.38 - Permanent exemption for certain fuel mixtures containing natural gas or petroleum.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... mixture of solar energy (including wind, tide, and other intermittent sources) and petroleum or natural gas, where: (1) Solar energy will account for at least 20 percent of the total annual Btu heat input... 10 Energy 4 2014-01-01 2014-01-01 false Permanent exemption for certain fuel mixtures...

  11. 10 CFR 503.38 - Permanent exemption for certain fuel mixtures containing natural gas or petroleum.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... mixture of solar energy (including wind, tide, and other intermittent sources) and petroleum or natural gas, where: (1) Solar energy will account for at least 20 percent of the total annual Btu heat input... 10 Energy 4 2012-01-01 2012-01-01 false Permanent exemption for certain fuel mixtures...

  12. Graphical arterial blood gas visualization tool supports rapid and accurate data interpretation.

    PubMed

    Doig, Alexa K; Albert, Robert W; Syroid, Noah D; Moon, Shaun; Agutter, Jim A

    2011-04-01

    A visualization tool that integrates numeric information from an arterial blood gas report with novel graphics was designed for the purpose of promoting rapid and accurate interpretation of acid-base data. A study compared data interpretation performance when arterial blood gas results were presented in a traditional numerical list versus the graphical visualization tool. Critical-care nurses (n = 15) and nursing students (n = 15) were significantly more accurate identifying acid-base states and assessing trends in acid-base data when using the graphical visualization tool. Critical-care nurses and nursing students using traditional numerical data had an average accuracy of 69% and 74%, respectively. Using the visualization tool, average accuracy improved to 83% for critical-care nurses and 93% for nursing students. Analysis of response times demonstrated that the visualization tool might help nurses overcome the "speed/accuracy trade-off" during high-stress situations when rapid decisions must be rendered. Perceived mental workload was significantly reduced for nursing students when they used the graphical visualization tool. In this study, the effects of implementing the graphical visualization were greater for nursing students than for critical-care nurses, which may indicate that the experienced nurses needed more training and use of the new technology prior to testing to show similar gains. Results of the objective and subjective evaluations support the integration of this graphical visualization tool into clinical environments that require accurate and timely interpretation of arterial blood gas data.

  13. Gas gain limitation in low pressure proportional counters filled with TEG mixtures

    NASA Astrophysics Data System (ADS)

    Kowalski, T. Z.

    2014-12-01

    Proportional counters filled with tissue equivalent gas mixtures (TEPC) can be used to simulate interactions and energy transferred to small tissue volumes. One criteria which allows to use TEPC as the dose meter is that the particle ranges are larger compared to the gas volume. TEPC achieve this by operating at low gas pressures. Single ionization events dominate the distribution of low-LET radiation at low gas pressure and therefore their detection is of primary importance, a high gas gain is necessary. Therefore gas gain factor has been measured for Methane- and Propane-based tissue equivalent gas mixtures. The highest stable gas gains, second ionization Townsend coefficient and electron avalanche dimensions have been determined.

  14. Grad's moment method for relativistic gas mixtures of Maxwellian particles

    NASA Astrophysics Data System (ADS)

    Kremer, Gilberto M.; Marques, Wilson

    2013-01-01

    Mixtures of relativistic gases are analyzed within the framework of Boltzmann equation by using Grad's moment method. A relativistic mixture of r constituent is characterized by the moments of the distribution function: particle four-flows, energy-momentum tensors, and third-order moment tensors. By using Eckart's decomposition and introducing 13r + 1 scalar fields - related with the four-velocity, temperature of the mixture, particle number densities, diffusion fluxes, non-equilibrium pressures, heat fluxes, and pressure deviator tensors - Grad's distribution functions are obtained. Grad's distribution functions are used to determine the third-order tensors and their production terms for mixtures whose constituent's rest masses are not too disparate, so that it follows a system of 13r + 1 scalar field equations. By restricting to a binary mixture characterized by the six fields of partial particle number densities, four-velocity and temperature, the remainder 21 scalar equations are used to determine the constitutive equations for the non-equilibrium pressures, diffusion fluxes, pressure deviator tensors, and heat fluxes. Hence the Navier-Stokes and generalized Fourier and Fick laws are obtained and the transport coefficients of bulk and shear viscosities, thermal conductivity, diffusion, thermal-diffusion, and diffusion-thermal are determined. Analytic expressions for the transport coefficients in the non-relativistic and ultra-relativistic limiting cases are given. Furthermore, solutions of the relativistic field equations for the binary mixture are obtained in form of forced and free waves. In the low frequency limiting case the phase velocity and the attenuation coefficient are determined for forced waves. In the small wavenumber limiting case it is shown that there exist four longitudinal eigenmodes, two of them corresponding to propagating sound modes and two associated with non-propagating diffusive modes.

  15. Measurements of laminar burning velocities for natural gas-hydrogen-air mixtures

    SciTech Connect

    Huang, Zuohua; Zhang, Yong; Zeng, Ke; Liu, Bing; Wang, Qian; Jiang, Deming

    2006-07-15

    Laminar flame characteristics of natural gas-hydrogen-air flames were studied in a constant-volume bomb at normal temperature and pressure. Laminar burning velocities and Markstein lengths were obtained at various ratios of hydrogen to natural gas (volume fraction from 0 to 100%) and equivalence ratios (f from 0.6 to 1.4). The influence of stretch rate on flame was also analyzed. The results show that, for lean mixture combustion, the flame radius increases with time but the increasing rate decreases with flame expansion for natural gas and for mixtures with low hydrogen fractions, while at high hydrogen fractions, there exists a linear correlation between flame radius and time. For rich mixture combustion, the flame radius shows a slowly increasing rate at early stages of flame propagation and a quickly increasing rate at late stages of flame propagation for natural gas and for mixtures with low hydrogen fractions, and there also exists a linear correlation between flame radius and time for mixtures with high hydrogen fractions. Combustion at stoichiometric mixture demonstrates the linear relationship between flame radius and time for natural gas-air, hydrogen-air, and natural gas-hydrogen-air flames. Laminar burning velocities increase exponentially with the increase of hydrogen fraction in mixtures, while the Markstein length decreases and flame instability increases with the increase of hydrogen fractions in mixture. For a fixed hydrogen fraction, the Markstein number shows an increase and flame stability increases with the increase of equivalence ratios. Based on the experimental data, a formula for calculating the laminar burning velocities of natural gas-hydrogen-air flames is proposed. (author)

  16. Electron temperature and density measurement of tungsten inert gas arcs with Ar-He shielding gas mixture

    NASA Astrophysics Data System (ADS)

    Kühn-Kauffeldt, M.; Marques, J.-L.; Forster, G.; Schein, J.

    2013-10-01

    The diagnostics of atmospheric welding plasma is a well-established technology. In most cases the measurements are limited to processes using pure shielding gas. However in many applications shielding gas is a mixture of various components including metal vapor in gas metal arc welding (GMAW). Shielding gas mixtures are intentionally used for tungsten inert gas (TIG) welding in order to improve the welding performance. For example adding Helium to Argon shielding gas allows the weld geometry and porosity to be influenced. Yet thermal plasmas produced with gas mixtures or metal vapor still require further experimental investigation. In this work coherent Thomson scattering is used to measure electron temperature and density in these plasmas, since this technique allows independent measurements of electron and ion temperature. Here thermal plasmas generated by a TIG process with 50% Argon and 50% Helium shielding gas mixture have been investigated. Electron temperature and density measured by coherent Thomson scattering have been compared to the results of spectroscopic measurements of the plasma density using Stark broadening of the 696.5 nm Argon spectral line. Further investigations of MIG processes using Thomson scattering technique are planned.

  17. Emission spectroscopic study on gas-gas interactions in glow discharge plasmas using several binary gas mixtures.

    PubMed

    Wagatsuma, Kazuaki

    2010-01-01

    Emission spectra of constituent gas species from glow discharge plasmas using argon-helium, krypton-helium, argon-krypton, and krypton-argon gas mixtures were analyzed to elucidate collisional energy transfer between these gas species occurring in the plasma. In the argon-helium mixed gas plasma, the enhancement or quenching of particular Ar II lines was observed when helium was added to an argon-matrix glow discharge plasma, meaning that a redistribution in the population among the excited levels could be induced through argon-helium collisions. On the other hand, the krypton-helium plasma showed little change in the emission intensities of Kr II lines when helium was added to a krypton-matrix glow discharge plasma, meaning that energy exchanges between krypton and helium excited species occur inactively. These phenomena are principally because the excitation energy as well as the spin multiplicity between collision partners follow both the energy resonance conditions and the spin conservation rule in collisions of the second kind in the argon-helium system, but not in the krypton-helium system. In the argon-krypton and krypton-argon mixed gas plasmas, significant intensity changes of particular Ar II or Kr II lines could not be found; therefore, there were no dominant channels for energy exchanges between argon and krypton species in the mixed gas plasmas.

  18. Method of and apparatus for measuring the mean concentration of thoron and/or radon in a gas mixture

    DOEpatents

    Lucas, Henry

    1990-01-01

    A method of and an apparatus for detecting and accurately measuring the mean concentrations of .sup.222 Rn and .sup.220 Tn in a gas mixture, such as the ambient atmosphere in a mine, is provided. The apparatus includes an alpha target member which defines at least one operative target surface and which is preferably fabricated from a single piece of an alpha particle sensitive material. At least one portion of the operative target surface is covered with an alpha particle filter. The uncovered and filter covered operative surface is exposed to the gas mixture containing the .sup.222 Rn and .sup.220 Tn. In the radioactive decay series of these isotopes the maximum kinetic energy emitted by the alpha decay of .sup.222 Rn is about 1.1 MeV less than the maximum kinetic energy emitted by the alpha decay of a .sup.220 Tn. The alpha particle filter has a predetermined mass per unit area of the covered portion of the operative target surface that prevents penetration of alpha particles which originate from .sup.222 Rn decay, but which allows passage therethrough of the maximum kinetic energy alpha particles from .sup.220 Tn decay. Thus, a count of the alpha particle tracks in the uncovered portion of the target member is proportional to the mean concentration of sum of .sup.222 Rn and .sup.220 Tn in the gas mixture, while the count of alpha tracks in the target member under the filter is proportional to the concentration of only the .sup.220 Tn in the gas mixture.

  19. Prediction of acute toxicity of chemicals in mixtures: worms Tubifex tubifex and gas/liquid distribution.

    PubMed

    Tichý, M; Borek-Dohalský, V; Matousová, D; Rucki, M; Feltl, L; Roth, Z

    2002-03-01

    The aim of this contribution is to support our proposal of the procedure for predicting acute toxicity of binary mixtures by QSAR analysis techniques. The changes of a mixture composition are described by molar ratio R and visualized in the R-plot (QCAR--quantitative composition-activity relationships). The approach was inspired by Rault and Dalton's laws, their positive and negative deviations in the behavior of a mixture of real gases, by Loewe and Muischnek isoboles and by the Finney test of additivity. Acute toxicity was determined by the laboratory test with woms Tubifex tubifex. The additivity of the acute toxicity in the binary mixture benzene + nitrobenzene was confirmed and a new interaction is described: "mixed interaction" with the binary mixture aniline + ethanol. The "mixed interaction" means that depending on mixture composition, both potentiation and inhibition can occur. As the first physicochemical descriptor of the changes caused by the changing composition of binary mixtures, the gas/liquid equilibrium was studied and a composition of the gaseous phase was determined by a gas chromatographic method. The method for determination of concentrations in the gaseous phase was described. The gaseous phase composition of benzene + nitrobenzene. benzene + ethanol, benzene + aniline and ethanol + aniline mixtures was analyzed. It was found that if the concentrations of the mixture's components in the gaseous phase behave nonideally (they are not additive), the acute toxicity of the same mixture is not additive as well. Another descriptor to distinguish between potentiation and inhibition will be, however, necessary. The properties, both gaseous phase composition and the acute toxicity, of the benzene + nitrobenzene mixture are additive. In mixtures with the mixed interaction, the R-plot of the composition of the gaseous phase is complex with a large variation of results.

  20. Accurate quadrupole MS peak reconstruction in optimized gas-flow comprehensive two-dimensional gas chromatography.

    PubMed

    Tranchida, Peter Quinto; Purcaro, Giorgia; Sciarrone, Danilo; Dugo, Paola; Dugo, Giovanni; Mondello, Luigi

    2010-09-01

    In the present research, a split-flow comprehensive 2-D GC-quadrupole MS (qMS) method was developed using: a primary apolar 30 m×0.25 mm id×0.25 μm d(f) capillary linked, via a T-union, to a secondary polar 1.0 m×0.05 mm id×0.05 μm d(f) capillary and to a 0.10 m×0.05 mm id×0.05 μm d(f) uncoated column segment. The GC×GC-qMS instrument was equipped with two GC ovens and a loop-type modulator. The polar column was connected to the MS, whereas the uncoated column directed most of the first-dimension effluent to waste and enabled the generation of optimum gas velocities in both dimensions, namely circa 20 and 80 cm/s in the first and second dimensions, respectively. The rapid-scanning qMS was operated at a scan speed of 10,000 amu/s, a 25-Hz data acquisition frequency (scan time+interscan time: 40 ms), and with a normal GC mass range (m/z 40-360). Chromatography bands at the second-dimension outlet were never less than 360 ms wide (6σ), enabling the acquisition of at least 10 spectra/peak.

  1. Rayleigh-Brillouin Scattering in Binary-Gas Mixtures.

    PubMed

    Gu, Z; Ubachs, W; Marques, W; van de Water, W

    2015-06-19

    Precise measurements are performed on spectral line shapes of spontaneous Rayleigh-Brillouin scattering in mixtures of the noble gases Ar and Kr, with He. Admixture of a light He atomic fraction results in marked changes of the spectra, although in all experiments He is merely a spectator atom: it affects the relaxation of density fluctuations of the heavy constituent, but its contribution to the scattered light intensity is negligibly small. The results are compared to a theory for the spectral line shape without adjustable parameters, yielding excellent agreement for the case of binary monatomic gases, signifying a step towards modeling and understanding of light scattering in more complex molecular media. PMID:26196978

  2. Ion swarm data for electrical discharge modeling in air and flue gas mixtures

    NASA Astrophysics Data System (ADS)

    Nelson, D.; Benhenni, M.; Eichwald, O.; Yousfi, M.

    2003-07-01

    The first step of this work is the determination of the elastic and inelastic ion-molecule collision cross sections for the main ions (N2+, O2+, CO2+, H2O+ and O-) usually present either in the air or flue gas discharges. The obtained cross section sets, given for ion kinetic energies not exceeding 100 eV, correspond to the interactions of each ion with its parent molecule (symmetric case) or nonparent molecule (asymmetric case). Then by using these different cross section sets, it is possible to obtain the ion swarm data for the different gas mixtures involving N2, CO2, H2O and O2 molecules whatever their relative proportions. These ion swarm data are obtained from an optimized Monte Carlo method well adapted for the ion transport in gas mixtures. This also allows us to clearly show that the classical linear approximations usually applied for the ion swarm data in mixtures such as Blanc's law are far to be valid. Then, the ion swarm data are given in three cases of gas mixtures: a dry air (80% N2, 20% O2), a ternary gas mixture (82% N2, 12% CO2, 6% O2) and a typical flue gas (76% N2, 12% CO2, 6% O2, 6% H2O). From these reliable ion swarm data, electrical discharge modeling for a wire to plane electrode configuration has been carried out in these three mixtures at the atmospheric pressure for different applied voltages. Under the same discharge conditions, large discrepancies in the streamer formation and propagation have been observed in these three mixture cases. They are due to the deviations existing not only between the different effective electron-molecule ionization rates but also between the ion transport properties mainly because of the presence of a highly polar molecule such as H2O. This emphasizes the necessity to properly consider the ion transport in the discharge modeling.

  3. Some possibilities of using gas mixtures other than air in aerodynamic research

    NASA Technical Reports Server (NTRS)

    Chapman, Dean R

    1956-01-01

    A study is made of the advantages that can be realized in compressible-flow research by employing a substitute heavy gas in place of air. The present report is based on the idea that by properly mixing a heavy monatomic gas with a suitable heavy polyatomic gas, it is possible to obtain a heavy gas mixture which has the correct ratio of specific heats and which is nontoxic, nonflammable, thermally stable, chemically inert, and comprised of commercially available components. Calculations were made of wind-tunnel characteristics for 63 gas pairs comprising 21 different polyatomic gases properly mixed with each of three monatomic gases (argon, krypton, and zenon).

  4. Proton irradiation of simple gas mixtures: Influence of irradiation parameters

    NASA Technical Reports Server (NTRS)

    Sack, Norbert J.; Schuster, R.; Hofmann, A.

    1990-01-01

    In order to get information about the influence of irradiation parameters on radiolysis processes of astrophysical interest, methane gas targets were irradiated with 6.5 MeV protons at a pressure of 1 bar and room temperature. Yields of higher hydrocarbons like ethane or propane were found by analysis of irradiated gas samples using gas chromatography. The handling of the proton beam was of great experimental importance for determining the irradiation parameters. In a series of experiments current density of the proton beam and total absorbed energy were shown to have a large influence on the yields of produced hydrocarbons. Mechanistic interpretations of the results are given and conclusions are drawn with regard to the chemistry and the simulation of various astrophysical systems.

  5. Influence of the gas mixture temperature on the efficiency of synthesis gas production from ethanol in a nonequilibrium plasma

    NASA Astrophysics Data System (ADS)

    Tsymbalyuk, A. N.; Levko, D. S.; Chernyak, V. Ya.; Martysh, E. V.; Nedybalyuk, O. A.; Solomenko, E. V.

    2013-08-01

    The mechanism behind the plasma conversion of a mixture of ethanol vapor, water vapor, air, and carbon dioxide CO2 in the nonequilibrium plasma of a tornado discharge is studied. The influence of the CO2 flow rate, the current through the discharge, and the gas temperature in the discharge on the concentrations of molecular hydrogen and carbon monoxide CO is studied. Comparison between the concentrations of the gaseous mixture's main components at the output from the reactor obtained experimentally and by numerical simulation shows that the adopted kinetic mechanism adequately describes the plasma kinetics in the mixture.

  6. Measurement of nitrogen content in a gas mixture by transforming the nitrogen into a substance detectable with nondispersive infrared detection

    DOEpatents

    Owen, Thomas E.; Miller, Michael A.

    2007-03-13

    A method of determining the amount of nitrogen in a gas mixture. The constituent gases of the mixture are dissociated and transformed to create a substance that may measured using nondispersive infrared adsorption techniques.

  7. Measurement of nitrogen content in a gas mixture by transforming the nitrogen into a substance detectable with nondispersive infrared detection

    DOEpatents

    Owen, Thomas E.; Miller, Michael A.

    2010-08-24

    A method of determining the amount of nitrogen in a gas mixture. The constituent gases of the mixture are dissociated and transformed to create a substance that may measured using nondispersive infrared adsorption techniques.

  8. Inflammable gas mixture detection with a single catalytic sensor based on the electric field effect.

    PubMed

    Tong, Ziyuan; Tong, Min-Ming; Meng, Wen; Li, Meng

    2014-01-01

    This paper introduces a new way to analyze mixtures of inflammable gases with a single catalytic sensor. The analysis technology was based on a new finding that an electric field on the catalytic sensor can change the output sensitivity of the sensor. The analysis of mixed inflammable gases results from processing the output signals obtained by adjusting the electric field parameter of the catalytic sensor. For the signal process, we designed a group of equations based on the heat balance of catalytic sensor expressing the relationship between the output signals and the concentration of gases. With these equations and the outputs of different electric fields, the gas concentration in a mixture could be calculated. In experiments, a mixture of methane, butane and ethane was analyzed by this new method, and the results showed that the concentration of each gas in the mixture could be detected with a single catalytic sensor, and the maximum relative error was less than 5%. PMID:24717635

  9. Operation of static and flowing Cs DPAL with different buffer gas mixtures

    NASA Astrophysics Data System (ADS)

    Knize, R. J.; Zhdanov, B. V.; Rotondaro, M. T.; Shaffer, M. K.

    2016-03-01

    Cs DPAL operation using Ethane, Methane and mixtures of these hydrocarbons with noble gases He and Ar as a buffer gases for spin-orbit relaxation was studied in this work. The best Cs DPAL performance in continuous wave operation with flowing gain medium was achieved using pure Methane, pure Ethane or a mixture of Ethane (minimum of 200 Torr) and He with a total buffer gas pressure of 300 torr.

  10. Weak discontinuity waves in a relativistic mixture of two stiffened gas components

    NASA Astrophysics Data System (ADS)

    Conforto, F.; Giambò, S.

    2010-11-01

    A simple interface-capturing approach is developed in order to deduce the relativistic fluid equations for a two-component mixture, using a stiffened gas equation of state. The two species are assumed to be at thermal equilibrium and the total pressure of the mixture is expressed in terms of the pressures of the two components by Dalton's law. Moreover, weak discontinuity waves compatible with such a fluid are examined.

  11. Sub-shock formation in Grad 10-moment equations for a binary gas mixture

    NASA Astrophysics Data System (ADS)

    Bisi, Marzia; Conforto, Fiammetta; Martalò, Giorgio

    2016-09-01

    The shock structure problem for Grad 10-moment equations for an inert binary mixture is investigated: necessary conditions for the formation of sub-shocks in fields of only one gas or of both components are rigorously obtained, and a detailed comparison with the shock-wave structure of its principal sub-system (deduced assuming vanishing viscous stress tensors) and of the equilibrium Euler sub-system is performed. Some numerical simulations for a mixture of argon and helium are presented.

  12. Numerical simulation of the passive gas mixture flow

    NASA Astrophysics Data System (ADS)

    Kyncl, Martin; Pelant, Jaroslav

    2016-03-01

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

  13. Two-phase turbine engines. [using gas-liquid mixture accelerated in nozzles

    NASA Technical Reports Server (NTRS)

    Elliott, D. G.; Hays, L. G.

    1976-01-01

    A description is given of a two-phase turbine which utilizes a uniform mixture of gas and liquid accelerated in nozzles of the types reported by Elliott and Weinberg (1968). The mixture acts directly on an axial flow or tangential impulse turbine or is separated into gas and liquid streams which operate separately on a gas turbine and a hydraulic turbine. The basic two-phase cycles are examined, taking into account working fluids, aspects of nozzle expansion, details of turbine cycle operation, and the effect of mixture ratio variation. Attention is also given to two-phase nozzle efficiency, two-phase turbine operating characteristics and efficiencies, separator turbines, and impulse turbine experiments.

  14. General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures

    SciTech Connect

    Liu, Yen Vinokur, Marcel; Panesi, Marco; Sahai, Amal

    2015-04-07

    relaxation model, which can only be applied to molecules, the new model is applicable to atoms, molecules, ions, and their mixtures. Numerical examples and model validations are carried out with two gas mixtures using the maximum entropy linear model: one mixture consists of nitrogen molecules undergoing internal excitation and dissociation and the other consists of nitrogen atoms undergoing internal excitation and ionization. Results show that the original hundreds to thousands of microscopic equations can be reduced to two macroscopic equations with almost perfect agreement for the total number density and total internal energy using only one or two groups. We also obtain good prediction of the microscopic state populations using 5-10 groups in the macroscopic equations.

  15. General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures.

    PubMed

    Liu, Yen; Panesi, Marco; Sahai, Amal; Vinokur, Marcel

    2015-04-01

    relaxation model, which can only be applied to molecules, the new model is applicable to atoms, molecules, ions, and their mixtures. Numerical examples and model validations are carried out with two gas mixtures using the maximum entropy linear model: one mixture consists of nitrogen molecules undergoing internal excitation and dissociation and the other consists of nitrogen atoms undergoing internal excitation and ionization. Results show that the original hundreds to thousands of microscopic equations can be reduced to two macroscopic equations with almost perfect agreement for the total number density and total internal energy using only one or two groups. We also obtain good prediction of the microscopic state populations using 5-10 groups in the macroscopic equations.

  16. General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures.

    PubMed

    Liu, Yen; Panesi, Marco; Sahai, Amal; Vinokur, Marcel

    2015-04-01

    relaxation model, which can only be applied to molecules, the new model is applicable to atoms, molecules, ions, and their mixtures. Numerical examples and model validations are carried out with two gas mixtures using the maximum entropy linear model: one mixture consists of nitrogen molecules undergoing internal excitation and dissociation and the other consists of nitrogen atoms undergoing internal excitation and ionization. Results show that the original hundreds to thousands of microscopic equations can be reduced to two macroscopic equations with almost perfect agreement for the total number density and total internal energy using only one or two groups. We also obtain good prediction of the microscopic state populations using 5-10 groups in the macroscopic equations. PMID:25854230

  17. CO2 + N2O mixture gas hydrate formation kinetics and effect of soil minerals on mixture-gas hydrate formation process

    NASA Astrophysics Data System (ADS)

    Enkh-Amgalan, T.; Kyung, D.; Lee, W.

    2012-12-01

    CO2 mitigation is one of the most pressing global scientific topics in last 30 years. Nitrous oxide (N2O) is one of the main greenhouse gases (GHGs) defined by the Kyoto Protocol and its global warming potential (GWP) of one metric ton is equivalent to 310 metric tons of CO2. They have similar physical and chemical properties and therefore, mixture-gas (50% CO2 + 50% N2O) hydrate formation process was studied experimentally and computationally. There were no significant research to reduce N20 gas and we tried to make hydrate to mitigate N20 and CO2 in same time. Mixture gas hydrate formation periods were approximately two times faster than pure N2O hydrate formation kinetic in general. The fastest induction time of mixture-gas hydrate formation observed in Illite and Quartz among various soil mineral suspensions. It was also observed that hydrate formation kinetic was faster with clay mineral suspensions such as Nontronite, Sphalerite and Montmorillonite. Temperature and pressure change were not significant on hydrate formation kinetic; however, induction time can be significantly affected by various chemical species forming under the different suspension pHs. The distribution of chemical species in each mineral suspension was estimated by a chemical equilibrium model, PHREEQC, and used for the identification of hydrate formation characteristics in the suspensions. With the experimental limitations, a study on the molecular scale modeling has a great importance for the prediction of phase behavior of the gas hydrates. We have also performed molecular dynamics computer simulations on N2O and CO2 hydrate structures to estimate the residual free energy of two-phase (hydrate cage and guest molecule) at three different temperature ranges of 260K, 273K, and 280K. The calculation result implies that N2O hydrates are thermodynamically stable at real-world gas hydrate existing condition within given temperature and pressure. This phenomenon proves that mixture-gas could be

  18. Dose Addition Models Based on Biologically Relevant Reductions in Fetal Testosterone Accurately Predict Postnatal Reproductive Tract Alterations by a Phthalate Mixture in Rats.

    PubMed

    Howdeshell, Kembra L; Rider, Cynthia V; Wilson, Vickie S; Furr, Johnathan R; Lambright, Christy R; Gray, L Earl

    2015-12-01

    Challenges in cumulative risk assessment of anti-androgenic phthalate mixtures include a lack of data on all the individual phthalates and difficulty determining the biological relevance of reduction in fetal testosterone (T) on postnatal development. The objectives of the current study were 2-fold: (1) to test whether a mixture model of dose addition based on the fetal T production data of individual phthalates would predict the effects of a 5 phthalate mixture on androgen-sensitive postnatal male reproductive tract development, and (2) to determine the biological relevance of the reductions in fetal T to induce abnormal postnatal reproductive tract development using data from the mixture study. We administered a dose range of the mixture (60, 40, 20, 10, and 5% of the top dose used in the previous fetal T production study consisting of 300 mg/kg per chemical of benzyl butyl (BBP), di(n)butyl (DBP), diethyl hexyl phthalate (DEHP), di-isobutyl phthalate (DiBP), and 100 mg dipentyl (DPP) phthalate/kg; the individual phthalates were present in equipotent doses based on their ability to reduce fetal T production) via gavage to Sprague Dawley rat dams on GD8-postnatal day 3. We compared observed mixture responses to predictions of dose addition based on the previously published potencies of the individual phthalates to reduce fetal T production relative to a reference chemical and published postnatal data for the reference chemical (called DAref). In addition, we predicted DA (called DAall) and response addition (RA) based on logistic regression analysis of all 5 individual phthalates when complete data were available. DA ref and DA all accurately predicted the observed mixture effect for 11 of 14 endpoints. Furthermore, reproductive tract malformations were seen in 17-100% of F1 males when fetal T production was reduced by about 25-72%, respectively. PMID:26350170

  19. Shock wave processes in collisional gas particle mixtures

    NASA Astrophysics Data System (ADS)

    Khmel, T. A.; Fedorov, A. V.

    2016-06-01

    Structures and propagation of shock waves in high density particle suspensions in gas are investigated theoretically and numerically. A physical and mathematical model which takes into account integral collisions between the particles on the basis of molecular-kinetic approaches of theory of granular materials is applied. The possibility of different types of shock waves, including double front structures is revealed. The role of particle collisions in the dynamics of particle dense layer expansion under an influence of divergent shock wave and in processes of shock wave diffraction past a backward-facing step is analyzed.

  20. Accurate sampling of PCDD/F in high temperature flue-gas using cooled sampling probes.

    PubMed

    Phan, Duong Ngoc Chau; Weidemann, Eva; Lundin, Lisa; Marklund, Stellan; Jansson, Stina

    2012-08-01

    In a laboratory-scale combustion reactor, flue-gas samples were collected at two temperatures in the post-combustion zone, 700°C and 400°C, using two different water-cooled sampling probes. The probes were the cooled probe described in the European Standard method EN-1948:1, referred to as the original probe, and a modified probe that contained a salt/ice mixture to assist the cooling, referred to as the sub-zero probe. To determine the efficiency of the cooling probes, internal temperature measurements were recorded at 5cm intervals inside the probes. Flue-gas samples were analyzed for polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs). Samples collected at 700°C using the original cooling probe showed higher concentrations of PCDD/Fs compared to samples collected using the sub-zero probe. No significant differences were observed between samples collected at 400°C. The results indicated that artifact formation of PCDD/Fs readily occurs during flue-gas sampling at high temperatures if the cooling within the probe is insufficient, as found for the original probe at 700°C. It was also shown that this problem could be alleviated by using probes with an enhanced cooling capacity, such as the sub-zero probe. Although this may not affect samples collected for regulatory purposes in exit gases, it is of great importance for research conducted in the high-temperature region of the post-combustion zone.

  1. Modeling of the gas-phase chemistry in C-H-O gas mixtures for diamond chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Petherbridge, James R.; May, Paul W.; Ashfold, Michael N. R.

    2001-05-01

    The boundaries of the diamond deposition region in the C-H-O (Bachmann) atomic phase composition diagram have been reproduced successfully for 38 different C, H, and O containing gas mixtures using the CHEMKIN computer package, together with just two criteria—a minimum mole fraction of methyl radicals [CH3] and a limiting value of the [H]/[C2H2] ratio. The diamond growth/no-growth boundary coincides with the line along which the input mole fractions of C and O are equal. For every gas mixture studied, no-growth regions are found to coincide with a negligible (<10-10) mole fraction of CH3 radicals, while for gas mixtures lying within the diamond growth region the CH3 mole fraction is ˜10-7. Each no-growth→diamond growth boundary is seen to be accompanied by a 2-3 order of magnitude step in CH3 mole fraction. The boundary between diamond and nondiamond growth is less clearly defined, but can be reproduced by assuming a critical, temperature dependent [H]/[C2H2] ratio (0.2, in the case that Tgas=2000 K) that reflects the crucial role of H atoms in the etching of nondiamond phases. The analysis allows prediction of the composition process window for good quality diamond growth for all stable input gas mixtures considered in this study.

  2. Accurate determination of fiber water-retaining capability at process conditions by headspace gas chromatography.

    PubMed

    Zhang, Shu-Xin; Chai, Xin-Sheng; He, Liang

    2016-09-16

    This work reports on a method for the accurate determination of fiber water-retaining capability at process conditions by headspace gas chromatography (HS-GC) method. The method was based the HS-GC measurement of water vapor on a set closed vials containing in a given amount pulp with different amounts of water addition, from under-saturation to over-saturation. By plotting the equilibrated water vapor signal vs. the amount of water added in pulp, two different trend lines can be observed, in which the transition of the lines corresponds to fiber water-retaining capability. The results showed that the HS-GC method has good measurement precision (much better than the reference method) and good accuracy. The present method can be also used for determining pulp fiber water-retaining capability at the process temperatures in both laboratory research and mill applications. PMID:27554029

  3. Numerical Methodology for Coupled Time-Accurate Simulations of Primary and Secondary Flowpaths in Gas Turbines

    NASA Technical Reports Server (NTRS)

    Przekwas, A. J.; Athavale, M. M.; Hendricks, R. C.; Steinetz, B. M.

    2006-01-01

    Detailed information of the flow-fields in the secondary flowpaths and their interaction with the primary flows in gas turbine engines is necessary for successful designs with optimized secondary flow streams. Present work is focused on the development of a simulation methodology for coupled time-accurate solutions of the two flowpaths. The secondary flowstream is treated using SCISEAL, an unstructured adaptive Cartesian grid code developed for secondary flows and seals, while the mainpath flow is solved using TURBO, a density based code with capability of resolving rotor-stator interaction in multi-stage machines. An interface is being tested that links the two codes at the rim seal to allow data exchange between the two codes for parallel, coupled execution. A description of the coupling methodology and the current status of the interface development is presented. Representative steady-state solutions of the secondary flow in the UTRC HP Rig disc cavity are also presented.

  4. Variable-temperature cryogenic trap for the separation of gas mixtures

    NASA Technical Reports Server (NTRS)

    Des Marais, D. J.

    1978-01-01

    The paper describes a continuous variable-temperature U-shaped cold trap which can both purify vacuum-line combustion products for subsequent stable isotopic analysis and isolate the methane and ethane constituents of natural gases. The canister containing the trap is submerged in liquid nitrogen, and, as the gas cools, the gas mixture components condense sequentially according to their relative vapor pressures. After the about 12 min required for the bottom of the trap to reach the liquid-nitrogen temperature, passage of electric current through the resistance wire wrapped around the tubing covering the U-trap permits distillation of successive gas components at optimal temperatures. Data on the separation achieved for two mixtures, the first being typical vacuum-line combustion products of geochemical samples such as rocks and the second being natural gas, are presented, and the thermal behavior and power consumption are reported.

  5. A Study for Health Hazard Evaluation of Methylene Chloride Evaporated from the Tear Gas Mixture

    PubMed Central

    Chung, Eun-Kyo; Yi, Gwang-Yong; Chung, Kwang-Jae; Shin, Jung-Ah; Lee, In-Seop

    2010-01-01

    This study explored the health hazard of those exposed to methylene chloride by assessing its atmospheric concentration when a tear gas mixture was aerially dispersed. The concentration of methylene chloride ranged from 311.1-980.3 ppm (geometric mean, 555.8 ppm), 30 seconds after the dispersion started. However, the concentration fell rapidly to below 10 ppm after dispersion was completed. The concentration during the dispersion did not surpass the National Institute for Occupational Safety and Health 'immediately dangerous to life or health' value of 2,300 ppm, but did exceed the American Conference of Governmental Industrial Hygienists excursion limit of 250 ppm. Since methylene chloride is highly volatile (vapor pressure, 349 mmHg at 20℃), the postdispersion atmospheric concentration can rise instantaneously. Moreover, the o-chlorobenzylidenemalononitrile formulation of tear gas (CS gas) is an acute upper respiratory tract irritant. Therefore, tear gas mixtures should be handled with delicate care. PMID:22953168

  6. The measurement of oxygen fugacities in flowing gas mixtures at temperatures below 1200°C

    NASA Astrophysics Data System (ADS)

    Beckett, J. R.; Mendybaev, R. A.

    1997-10-01

    We measured oxygen fugacities in H 2CO 2 and COCO 2 gas mixtures in the temperature interval 700-1350°C using an yttria-stabilized zirconia (YSZ) oxygen sensor. At high temperatures in excess of 1200°C, measured emfs are consistent with expectations based on the gas composition. At lower temperatures in H 2CO 2 gas mixtures, the oxygen fugacity ( fO 2) obtained assuming Nernstian behavior of the oxygen sensor is as much as two log units more reducing (˜900°C) to one log unit more oxidizing (˜700°C) than expected by assuming equilibrium speciation. The deviations in H 2CO 2 gas mixtures arise from two sources: (1) poor contact between the electrode and the zirconia electrolyte, leading to apparent fO 2 values that are higher than expected and (2) disequilibrium in the vapor, leading to lower than expected fO 2 values in the temperature range ˜700-1200°C (for experiments near the iron-wustite (IW) buffer) and higher than expected fO 2 at lower temperatures. The first problem can be alleviated by spring-loading and lightly sintering a Pt mesh internal electrode against the electrolyte and the second by forcing the entire gas stream to equilibrate by passing it through a Pt catalyst. With these measures, experiments employing H 2CO 2 gas mixtures can be conducted routinely in the temperature range 700-1200°C and the fO 2 determined with an accuracy comparable to that obtained at higher temperatures (2σ < ±0.1 log units). Above ˜770°C, apparent oxygen fugacities measured using an oxygen sensor in COCO 2 gas mixtures near IW are consistent with equilibration in the vapor regardless of whether or not a Pt catalyst is present. At lower temperatures, however, the measured values are more oxidizing than the expected equilibrium values. Under more reducing conditions, the deviations begin to occur at even higher temperatures, ˜930°C for IW-3. The anomalously high fO 2 values are probably related to the condensation of graphite, which removes C

  7. Effective diffusion coefficients of gas mixture in heavy oil under constant-pressure conditions

    NASA Astrophysics Data System (ADS)

    Li, Huazhou Andy; Sun, Huijuan; Yang, Daoyong

    2016-09-01

    We develop a method to determine the effective diffusion coefficient for each individual component of a gas mixture in a non-volatile liquid (e.g., heavy oil) at high pressures with compositional analysis. Theoretically, a multi-component one-way diffusion model is coupled with the volume-translated Peng-Robinson equation of state to quantify the mass transfer between gas and liquid (e.g., heavy oil). Experimentally, the diffusion tests have been conducted with a PVT setup for one pure CO2-heavy oil system and one C3H8-CO2-heavy oil system under constant temperature and pressure, respectively. Both the gas-phase volume and liquid-phase swelling effect are simultaneously recorded during the measurement. As for the C3H8-CO2-heavy oil system, the gas chromatography method is employed to measure compositions of the gas phase at the beginning and end of the diffusion measurement, respectively. The effective diffusion coefficients are then determined by minimizing the discrepancy between the measured and calculated gas-phase composition at the end of diffusion measurement. The newly developed technique can quantify the contributions of each component of mixture to the bulk mass transfer from gas into liquid. The effective diffusion coefficient of C3H8 in the C3H8-CO2 mixture at 3945 ± 20 kPa and 293.85 K, i.e., 18.19 × 10^{ - 10} m^{ 2} / s, is found to be much higher than CO2 at 3950 ± 18 kPa and 293.85 K, i.e., 8.68 × 10^{ - 10} m^{ 2} / s. In comparison with pure CO2, the presence of C3H8 in the C3H8-CO2 mixture contributes to a faster diffusion of CO2 from the gas phase into heavy oil and consequently a larger swelling factor of heavy oil.

  8. Ideal gas solubilities and solubility selectivities in a binary mixture of room-temperature ionic liquids

    SciTech Connect

    Finotello Alexia; Bara Jason E.; Narayan Suguna; Campder Dean; Noble Richard D.

    2008-07-01

    This study focuses on the solubility behaviors of CO{sub 2}, CH{sub 4}, and N{sub 2} gases in binary mixtures of imidazolium-based room-temperature ionic liquids (RTILs) using l-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-imide ((C{sub 2}mim)(Tf{sub 2}N)) and l-ethyl-3-methylimidazolium tetrafluoroborate ((C{sub 2}mim)(BF{sub 4})) at 40{sup o}C and low pressures (about 1 atm). The mixtures tested were 0, 25, 50, 75, 90, 95, and 100 mol % (C{sub 2}mim)(BF{sub 4}) in (C{sub 2}-mim)(Tf2{sub N}). Results show that regular solution theory (RST) can be used to describe the gas solubility and selectivity behaviors in RTIL mixtures using an average mixture solubility parameter or an average measured mixture molar volume. Interestingly, the solubility selectivity, defined as the ratio of gas mole fractions in the RTIL mixture, of CO{sub 2} with N{sub 2} or CH{sub 4} in pure (C{sub 2}mim)(BF4) can be enhanced by adding 5 mol% (C{sub 2}-mim)(Tf{sub 2}N).

  9. New SI-traceable reference gas mixtures for fluorinated gases at atmospheric concentration

    NASA Astrophysics Data System (ADS)

    Guillevic, Myriam; Wyss, Simon A.; Pascale, Céline; Vollmer, Martin K.; Niederhauser, Bernhard; Reimann, Stefan

    2016-04-01

    In order to better support the monitoring of greenhouse gases in the atmosphere, we develop a method to produce reference gas mixtures for fluorinated gases (F-gases, i.e. gases containing fluorine atoms) in a SI-traceable way, meaning that the amount of substance fraction in mole per mole is traceable to SI-units. These research activities are conducted in the framework of the HIGHGAS and AtmoChem-ECV projects. First, single-component mixtures in synthetic air at ~85 nmol/mol (ppb) are generated for HFC-125 (pentafluoroethane, a widely used HFC) and HFC-1234yf (2,3,3,3-tetrafluoropropene, a car air conditioner fluid of growing importance). These mixtures are first dynamically produced by permeation: a permeator containing the pure substance loses mass linearly over time under a constant gas flow, in the permeation chamber of a magnetic suspension balance, which is regularly calibrated. This primary mixture is then pressurised into Silconert2000-coated stainless steel cylinders by cryo-filling. In a second step these mixtures are dynamically diluted using 2 subsequent dilution steps piloted by mass flow controllers (MFC) and pressure controllers. The assigned mixture concentration is calculated mostly based on the permeator mass loss, on the carrier gas purity and on the MFCs flows. An uncertainty budget is presented, resulting in an expanded uncertainty of 2% for the HFC-125 reference mixture and of 2.5% for the HFC-1234yf mixture (95% confidence interval). The final gas, with near-atmospheric concentration (17.11 pmol/mol for HFC-125, 2.14 pmol/mol for HFC-1234yf) is then measured with Medusa-GC/MS technology against standards calibrated on existing reference scales. The assigned values of the dynamic standards are in excellent agreement with measurements vs the existing reference scales, SIO-14 from the Scripps Institution of Oceanography for HFC-125 and Empa-2013 for HFC-1234yf. Moreover, the Medusa-GC/MS measurements show the excellent purity of the SI

  10. Microstructure-Dependent Gas Adsorption: Accurate Predictions of Methane Uptake in Nanoporous Carbons

    SciTech Connect

    Ihm, Yungok; Cooper, Valentino R; Gallego, Nidia C; Contescu, Cristian I; Morris, James R

    2014-01-01

    We demonstrate a successful, efficient framework for predicting gas adsorption properties in real materials based on first-principles calculations, with a specific comparison of experiment and theory for methane adsorption in activated carbons. These carbon materials have different pore size distributions, leading to a variety of uptake characteristics. Utilizing these distributions, we accurately predict experimental uptakes and heats of adsorption without empirical potentials or lengthy simulations. We demonstrate that materials with smaller pores have higher heats of adsorption, leading to a higher gas density in these pores. This pore-size dependence must be accounted for, in order to predict and understand the adsorption behavior. The theoretical approach combines: (1) ab initio calculations with a van der Waals density functional to determine adsorbent-adsorbate interactions, and (2) a thermodynamic method that predicts equilibrium adsorption densities by directly incorporating the calculated potential energy surface in a slit pore model. The predicted uptake at P=20 bar and T=298 K is in excellent agreement for all five activated carbon materials used. This approach uses only the pore-size distribution as an input, with no fitting parameters or empirical adsorbent-adsorbate interactions, and thus can be easily applied to other adsorbent-adsorbate combinations.

  11. Program on the combustion chemistry of low- and intermediate-Btu gas mixtures

    SciTech Connect

    Not Available

    1981-11-30

    Low and intermediate Btu (LBTU and IBTU) gas mixtures are essentially mixtures of CO, H/sub 2/ and CH/sub 4/ diluted with nitrogen and CO/sub 2/. Although the combustion properties of these three fuels have been extensively investigated and their individual combustion kinetics are reasonably well established, prediction techniques for applying these gas mixtures remain for the most part empirical. This program has aimed to bring together and apply some of the fundamental combustion parameters to the CO-H/sub 2/-CH/sub 4/ flame system with the hope of reducing some of this empiricism. Four topical reports have resulted from this program. This final report summarizes these reports and other activities undertaken in this program. This program was initiated June 22, 1976 under ERDA Contract No. E(49-18)-2406 and was later continued under DOE/PETC and DOE Contract No. DE-AC22-76ET10653.

  12. Ignition of a combustible gas mixture by a laser spark excited in the reactor volume

    NASA Astrophysics Data System (ADS)

    Kazantsev, S. Yu.; Kononov, I. G.; Kossyi, I. A.; Tarasova, N. M.; Firsov, K. N.

    2009-03-01

    Ignition of a stoichiometric CH4: O2 mixture by a laser spark excited in the reactor volume is studied experimentally. It is found that the spark initiates a feebly radiating incomplete-combustion wave, which is much faster than the combustion wave, but is substantially slower than the detonation wave. With a time delay of 500-700 μs, a bright optical flash occupying the entire chamber volume is observed, which indicates fast (involving branching chain reactions) ignition of the gas mixture. A conclusion is drawn regarding the common nature of the process of ignition of a combustible gas mixture by a laser spark excited in the reactor volume and the previously investigated initiation of combustion by laser sparks excited at solid targets, high-power microwave discharges, and high-current gliding discharges.

  13. Ignition of a combustible gas mixture by a laser spark excited in the reactor volume

    SciTech Connect

    Kazantsev, S. Yu.; Kononov, I. G.; Kossyi, I. A.; Tarasova, N. M.; Firsov, K. N.

    2009-03-15

    Ignition of a stoichiometric CH{sub 4}: O{sub 2} mixture by a laser spark excited in the reactor volume is studied experimentally. It is found that the spark initiates a feebly radiating incomplete-combustion wave, which is much faster than the combustion wave, but is substantially slower than the detonation wave. With a time delay of 500-700 {mu}s, a bright optical flash occupying the entire chamber volume is observed, which indicates fast (involving branching chain reactions) ignition of the gas mixture. A conclusion is drawn regarding the common nature of the process of ignition of a combustible gas mixture by a laser spark excited in the reactor volume and the previously investigated initiation of combustion by laser sparks excited at solid targets, high-power microwave discharges, and high-current gliding discharges.

  14. Hovering performance of hummingbirds in hyperoxic gas mixtures.

    PubMed

    Altshuler, D L; Chai, P; Chen, J S

    2001-06-01

    Hummingbirds evolved during a period of decline in atmospheric oxygen concentration and currently encounter varying levels of oxygen availability along their elevational distribution. We tested the hypothesis that inspiration of hyperoxic gas increases hummingbird hovering performance when birds are simultaneously challenged aerodynamically. We measured the maximum duration of hovering flight while simultaneously monitoring the rate of oxygen consumption of ruby-throated hummingbirds (Archilochus colubris) in low-density heliox that was either normoxic (21% O2) or hyperoxic (35% O2). As air density decreased below 0.85 kg x m(-3), hummingbirds hovered significantly longer in hyperoxia than in normoxia, but the air density at which the birds could no longer sustain hovering flight was independent of oxygen concentration. At low air densities in hyperoxia flight trials, hummingbirds appeared to increase their rate of oxygen consumption relative to flight sequences at equivalent densities in normoxia trials, but these differences were not significant. We tested the hypothesis that hummingbirds can discriminate between environments that differ in oxygen concentration. In another density-reduction experiment, hummingbirds were allowed to choose between artificial feeders infused with either normoxic or hyperoxic gases. The hypothesis was not supported because birds failed to associate oxygen concentration with a particular feeder independently of air density. Supplemental oxygen thus yields increased hovering duration at intermediate air densities, but the minimum density at which birds can fly is limited exclusively by aerodynamic considerations.

  15. Removal of carbon dioxide from gas mixtures by wollastonite

    NASA Astrophysics Data System (ADS)

    Engelsht, V. S.; Muratalieva, V. Zh.

    2013-09-01

    Wollastonite synthesis and decomposition were analyzed from the viewpoint of thermodynamics (using the TERRA software). It is shown that wollastonite synthesis from limestone and silica takes place at a minimum content of nitrogen (10-5 N2) with a release of carbon dioxide. The synthesis temperature is T ≥ 560 K. Wollastonite is decomposed in the presence of flue gas (4N2) with limestone and silica formation and burial of carbon dioxide in the form of CaCO3(c). Wollastonite decomposition temperature is T ≤ 420 K. The cyclic reciprocating process for complete removal of carbon dioxide by wollastonite is suggested. Four strokes of the reciprocating system with the fixed temperatures of wollastonite decomposition (T=300 K) and wollastonite synthesis (T=560 K) are presented. Total energy consumption (T = 560 K) is Δ I ≈ 130 kJ/mole, 30 % of energy is spent for heating and 70 % of energy is spent for chemical reaction. This is comparable with the heat of CO2 solution in ethanolamin.

  16. Hydrocracking of vacuum gas oil-vegetable oil mixtures for biofuels production.

    PubMed

    Bezergianni, Stella; Kalogianni, Aggeliki; Vasalos, Iacovos A

    2009-06-01

    Hydrocracking of vacuum gas oil (VGO)--vegetable oil mixtures is a prominent process for the production of biofuels. In this work both pre-hydrotreated and non-hydrotreated VGO are assessed whether they are suitable fossil components in a VGO-vegetable oil mixture as feed-stocks to a hydrocracking process. This assessment indicates the necessity of a VGO pre-hydrotreated step prior to hydrocracking the VGO-vegetable oil mixture. Moreover, the comparison of two different mixing ratios suggests that higher vegetable oil content favors hydrocracking product yields and qualities. Three commercial catalysts of different activity are utilized in order to identify a range of products that can be produced via a hydrocracking route. Finally, the effect of temperature on hydrocracking VGO-vegetable oil mixtures is studied in terms of conversion and selectivity to diesel, jet/kerosene and naphtha.

  17. Approximation of flammability region for natural gas-air-diluent mixture.

    PubMed

    Liao, S Y; Jiang, D M; Huang, Z H; Cheng, Q; Gao, J; Hu, Y

    2005-10-17

    The growing implementation of exhaust gas recirculation (EGR) in reducing NO(x) emissions of engine is of paramount motivation to perform a fundamental research on the flammability characteristics of fuel-air-diluent mixtures. In this work, the influences of EGR on the flammability region of natural gas-air-diluent flames were experimentally studied in a constant volume bomb. An assumption of critical burning velocity at flammability limit is proposed to approximately determine the flammability region of these mixtures. Based on this assumption, an estimation of the flammability map for natural gas-air-diluent mixtures was obtained by using the empirical formula of burning velocity data. The flammability regions of natural gas-air mixtures with EGR are plotted versus the EGR rate. From the comparison of estimated results and experimental measurements, it is suggested that the accuracy of prediction is largely dependent upon the formula of burning velocity used. Meanwhile, the influence of pressure on the critical burning velocity at flammability limit is also investigated. On the basis of the pressure dependence criterion, the estimation was performed for the circumstance of high temperature and pressure, and the prediction results still agree well with those of experiments.

  18. Concentration measurement systems with stable solutions for binary gas mixtures using two flowmeters

    NASA Astrophysics Data System (ADS)

    Youn, Chongho; Kawashima, Kenji; Kagawa, Toshiharu

    2011-06-01

    The previously proposed gas concentration measurement system (Yamazaki et al 2007 Meas. Sci. Technol. 18 2762-8) shows a considerable error for some combinations of gases. The error increases when the system of equations determining mole fractions becomes a mathematically ill-conditioned system. Because the parameters of the equations reflect the material properties of the gases, the current paper considers flowmeters whose flow rate indication does not involve any gas property. This paper firstly illustrates the ill condition for the combination of venturi meter and laminar flowmeters. The paper then discusses the simultaneous measurement of flow rate and mole fractions by flowmeter combinations: an ultrasonic flowmeter and a venturi meter, an ultrasonic flowmeter and a laminar flowmeter. Experiments are conducted for a mixture of argon and air. When a venturi meter and a laminar flowmeter are used, the equations to evaluate the gas mixture ratio become an ill-conditioned system, and hence the evaluated mixture ratio shows a considerable error. On the other hand, the combination of an ultrasonic flowmeter and a laminar flowmeter detects the gas mixture ratio with proper accuracy.

  19. Ignition of a combustible gas mixture by a high-current electric discharge in a closed volume

    SciTech Connect

    Berezhetskaya, N. K.; Gritsinin, S. I.; Kop'ev, V. A.; Kossyi, I. A.; Kuleshov, P. S.; Popov, N. A.; Starik, A. M.; Tarasova, N. M.

    2009-06-15

    Results are presented from experimental studies and numerical calculations of the ignition of a stoichiometric CH{sub 4}: O{sub 2} gas mixture by a high-current gliding discharge. It is shown that this type of discharge generates an axially propagating thermal wave (precursor) that penetrates into the gas medium and leads to fast gas heating. This process is followed by an almost simultaneous ignition of the gas mixture over the entire reactor volume.

  20. The CPA Equation of State and an Activity Coefficient Model for Accurate Molar Enthalpy Calculations of Mixtures with Carbon Dioxide and Water/Brine

    SciTech Connect

    Myint, P. C.; Hao, Y.; Firoozabadi, A.

    2015-03-27

    Thermodynamic property calculations of mixtures containing carbon dioxide (CO2) and water, including brines, are essential in theoretical models of many natural and industrial processes. The properties of greatest practical interest are density, solubility, and enthalpy. Many models for density and solubility calculations have been presented in the literature, but there exists only one study, by Spycher and Pruess, that has compared theoretical molar enthalpy predictions with experimental data [1]. In this report, we recommend two different models for enthalpy calculations: the CPA equation of state by Li and Firoozabadi [2], and the CO2 activity coefficient model by Duan and Sun [3]. We show that the CPA equation of state, which has been demonstrated to provide good agreement with density and solubility data, also accurately calculates molar enthalpies of pure CO2, pure water, and both CO2-rich and aqueous (H2O-rich) mixtures of the two species. It is applicable to a wider range of conditions than the Spycher and Pruess model. In aqueous sodium chloride (NaCl) mixtures, we show that Duan and Sun’s model yields accurate results for the partial molar enthalpy of CO2. It can be combined with another model for the brine enthalpy to calculate the molar enthalpy of H2O-CO2-NaCl mixtures. We conclude by explaining how the CPA equation of state may be modified to further improve agreement with experiments. This generalized CPA is the basis of our future work on this topic.

  1. Full-spectrum k-distribution look-up table for nonhomogeneous gas-soot mixtures

    NASA Astrophysics Data System (ADS)

    Wang, Chaojun; Modest, Michael F.; He, Boshu

    2016-06-01

    Full-spectrum k-distribution (FSK) look-up tables provide great accuracy combined with outstanding numerical efficiency for the evaluation of radiative transfer in nonhomogeneous gaseous media. However, previously published tables cannot be used for gas-soot mixtures that are found in most combustion scenarios since it is impossible to assemble k-distributions for a gas mixed with nongray absorbing particles from gas-only full-spectrum k-distributions. Consequently, a new FSK look-up table has been constructed by optimizing the previous table recently published by the authors and then adding one soot volume fraction to this optimized table. Two steps comprise the optimization scheme: (1) direct calculation of the nongray stretching factors (a-values) using the k-distributions (k-values) rather than tabulating them; (2) deletion of unnecessary mole fractions at many thermodynamic states. Results show that after optimization, the size of the new table is reduced from 5 GB (including the k-values and the a-values for gases only) to 3.2 GB (including the k-values for both gases and soot) while both accuracy and efficiency remain the same. Two scaled flames are used to validate the new table. It is shown that the new table gives results of excellent accuracy for those benchmark results together with cheap computational cost for both gas mixtures and gas-soot mixtures.

  2. Characterization of a GEM-based scintillation detector with He-CF4 gas mixture in clinical proton beams.

    PubMed

    Nichiporov, D; Coutinho, L; Klyachko, A V

    2016-04-21

    Accurate, high-spatial resolution dosimetry in proton therapy is a time consuming task, and may be challenging in the case of small fields, due to the lack of adequate instrumentation. The purpose of this work is to develop a novel dose imaging detector with high spatial resolution and tissue equivalent response to dose in the Bragg peak, suitable for beam commissioning and quality assurance measurements. A scintillation gas electron multiplier (GEM) detector based on a double GEM amplification structure with optical readout was filled with a He/CF4 gas mixture and evaluated in pristine and modulated proton beams of several penetration ranges. The detector's performance was characterized in terms of linearity in dose rate, spatial resolution, short- and long-term stability and tissue-equivalence of response at different energies. Depth-dose profiles measured with the GEM detector in the 115-205 MeV energy range were compared with the profiles measured under similar conditions using the PinPoint 3D small-volume ion chamber. The GEM detector filled with a He-based mixture has a nearly tissue equivalent response in the proton beam and may become an attractive and efficient tool for high-resolution 2D and 3D dose imaging in proton dosimetry, and especially in small-field applications. PMID:26992243

  3. Characterization of a GEM-based scintillation detector with He-CF4 gas mixture in clinical proton beams

    NASA Astrophysics Data System (ADS)

    Nichiporov, D.; Coutinho, L.; Klyachko, A. V.

    2016-04-01

    Accurate, high-spatial resolution dosimetry in proton therapy is a time consuming task, and may be challenging in the case of small fields, due to the lack of adequate instrumentation. The purpose of this work is to develop a novel dose imaging detector with high spatial resolution and tissue equivalent response to dose in the Bragg peak, suitable for beam commissioning and quality assurance measurements. A scintillation gas electron multiplier (GEM) detector based on a double GEM amplification structure with optical readout was filled with a He/CF4 gas mixture and evaluated in pristine and modulated proton beams of several penetration ranges. The detector’s performance was characterized in terms of linearity in dose rate, spatial resolution, short- and long-term stability and tissue-equivalence of response at different energies. Depth-dose profiles measured with the GEM detector in the 115-205 MeV energy range were compared with the profiles measured under similar conditions using the PinPoint 3D small-volume ion chamber. The GEM detector filled with a He-based mixture has a nearly tissue equivalent response in the proton beam and may become an attractive and efficient tool for high-resolution 2D and 3D dose imaging in proton dosimetry, and especially in small-field applications.

  4. Electrochemical separation and concentration of sulfur containing gases from gas mixtures

    DOEpatents

    Winnick, Jack

    1981-01-01

    A method of removing sulfur oxides of H.sub.2 S from high temperature gas mixtures (150.degree.-1000.degree. C.) is the subject of the present invention. An electrochemical cell is employed. The cell is provided with inert electrodes and an electrolyte which will provide anions compatible with the sulfur containing anions formed at the anode. The electrolyte is also selected to provide inert stable cations at the temperatures encountered. The gas mixture is passed by the cathode where the sulfur gases are converted to SO.sub.4.sup.= or, in the case of H.sub.2 S, to S.sup.=. The anions migrate to the anode where they are converted to a stable gaseous form at much greater concentration levels (>10X). Current flow may be effected by utilizing an external source of electrical energy or by passing a reducing gas such as hydrogen past the anode.

  5. Binary and ternary gas mixtures with temperature enhanced diffuse glow discharge characteristics for use in closing switches

    DOEpatents

    Christophorou, L.G.; Hunter, S.R.

    1988-06-28

    An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc. 11 figs.

  6. Binary and ternary gas mixtures with temperature enhanced diffuse glow discharge characteristics for use in closing switches

    DOEpatents

    Christophorou, Loucas G.; Hunter, Scott R.

    1990-01-01

    An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc.

  7. Binary and ternary gas mixtures with temperature enhanced diffuse glow discharge characteristics for use in closing switches

    DOEpatents

    Christophorou, L.G.; Hunter, S.R.

    1990-06-26

    An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc. 11 figs.

  8. An experimental setup with ultrasonic gas analyzers and real time analysis of the composition of a binary gas mixture

    NASA Astrophysics Data System (ADS)

    Vacek, V.; Vítek, M.; Doubek, M.

    2013-04-01

    This paper describes an automated measuring apparatus with an ultrasonic gas analyzer and realtime analysis of the composition of the gas. The apparatus is designed for preparing binary gas mixtures and making measurements in a wide range of pressures (from 0.8 bara to 15 bara) and temperatures (between -15°C and 80°C). The apparatus was developed to determine the thermophysical properties of fluorocarbon mixtures for potential use in the cooling circuits of several Large Hadron Collider projects at CERN. The design of its control system took into account the safety and reliability o the gas analyzer, and the need to limit the presence of laboratory personnel. The control system was implemented in PVSS-II, the Supervisory, Control and Data Acquisition standard chosen for LHC and its experiments at CERN. The second part of the paper describes the implementation and verification of the algorithm for continuous real-time determination of the composition of the refrigerant mixture. The algorithm is based on minimizing the quadratic norm fromthe measured data and from the pre-generated look-up tables acquired from the NIST REFPROP software package.

  9. Transport Properties of a Rarefied Ch4-N2 Gas Mixture

    NASA Astrophysics Data System (ADS)

    Fokin, L. R.; Kalashnikov, A. N.

    2016-01-01

    The area of application of the rarefied neutral methane-nitrogen gas mixture is considered. Experimental data on the transport properties of this mixture and its components were analyzed and generalized on the basis of molecular-kinetic theory relations with the use of the potentials of pair uniform and cross interactions of CH4 and N2 molecules. The parameters of three spherical symmetric three-parameter m-6 Lennard-Jones interaction potentials with a repulsive branch of varying rigidity were determined with the use of the nonlinear weight method of least squares. Tables of reference data on the viscosity of the indicated mixture and the coefficients of interdiffusion of its components were calculated for the concentration range 0-1 at temperatures 100-1150 K. Estimates of the confidential errors in determining the properties of this mixture have been made with the use of the error matrix of parameters of the indicated potentials. The results of calculations were compared with the corresponding reference data obtained earlier for the CH4-N2 gas mixture.

  10. Bubbling behaviors induced by gas-liquid mixture permeating through a porous medium

    NASA Astrophysics Data System (ADS)

    Hu, Liang; Li, Mingbo; Chen, Wenyu; Xie, Haibo; Fu, Xin

    2016-08-01

    This paper investigates the bubbling behaviors induced by gas-liquid mixture permeating through porous medium (PM), which was observed in developing immersion lithography system and was found having great differences with traditional bubbling behaviors injected with only gas phase through the PM. An experimental setup was built up to investigate the bubbling characteristics affected by the mixed liquid phase. Both the flow regimes of gas-liquid mixture in micro-channel (upstream of the PM) and the bubbling flow regimes in water tank (downstream of the PM) were recorded synchronously by high-speed camera. The transitions between the flow regimes are governed by gas and liquid Weber numbers. Based on the image analysis, the characteristic parameters of bubbling region, including the diameter of bubbling area on PM surface, gas-phase volume flux, and dispersion angle of bubbles in suspending liquid, were studied under different proportions of gas and liquid flow rate. Corresponding empirical correlations were developed to describe and predict these parameters. Then, the pertinent bubble characteristics in different bubbling flow regimes were systematically investigated. Specifically, the bubble size distribution and the Sauter mean diameter affected by increasing liquid flow rate were studied, and the corresponding analysis was given based on the hydrodynamics of bubble-bubble and bubble-liquid interactions. According to dimensionless analysis, the general prediction equation of Sauter mean diameter under different operating conditions was proposed and confirmed by experimental data. The study of this paper is helpful to improve the collection performance of immersion lithography and aims to reveal the differences between the bubbling behaviors on PM caused by only gas flow and gas-liquid mixture flow, respectively, for the researches of fluid flow.

  11. Flash pyrolysis of New Mexico sub-bituminous coal in helium-methane gas mixtures

    SciTech Connect

    Sundaram, M.S.; Fallon, P.T.; Steinberg, M.

    1986-04-01

    A New Mexico sub-bituminous coal was flash pyrolyzed in gas mixtures of helium and methane at 1000/sup 0/C and 50 psi in an 1-in. I.D. entrained down-flow tubular reactor. The mixture contained 0 to 40% helium in methane. Under tested experimental conditions, pyrolysis in gas mixtures resulted in higher yields of ethylene and BTX than in pure methane. For example, under a coal flow rate of 1.0 lb/hr and methane flow rate of 4.0 lb/hr, pyrolysis in pure methane produced 7.7% C/sub 2/H/sub 4/ and 9.0% BTX on the basis of carbon contained in coal; under similar coal and methane flow rates, as high as 14.8% C/sub 2/H/sub 4/ and 15.3% BTX were obtained on pyrolysis in 25% He + 75% CH/sub 4/ gas mixture. The data show that the coal flow rate and methane flow rate both independently effect the yields of C/sub 2/H/sub 4/ and BTS. At constant methane flow rate, increase in coal flow rate decreases the yields of C/sub 2/H/sub 4/ and BTX; at constant coal flow rate, increase in methane flow rate increases the yields of C/sub 2/H/sub 4/ and BTX. 6 refs., 2 tabs.

  12. Flash pyrolysis of New Mexico sub-bituminous coal in helium-methane gas mixtures

    SciTech Connect

    Sundaram, M.S.; Fallon, P.T.; Steinberg, M.

    1986-01-01

    A New Mexico sub-bituminous coal was flash pyrolyzed in gas mixtures of helium and methane at 1000/sup 0/C and 50 psi in an 1-in. I.D. entrained down-flow tubular reactor. The mixture contained 0 to 40% helium in methane. Under tested experimental conditions, pyrolysis in gas mixtures resulted in higher yields of ethylene and BTX than in pure methane. For example, under a coal flow rate of 1.0 lb/hr and methane flow rate of 4.0 lb/hr, pyrolysis in pure methane produced 7.7% C/sub 2/H/sub 4/ and 9.0% BTX on the basis of carbon contained in coal; under similar coal and methane flow rates, as high as 14.8% C/sub 2/H/sub 4/ and 15.3% BTX were obtained on pyrolysis in 25% He + 75% CH/sub 4/ gas mixture. The data show that the coal flow rate and methane flow rate both independently affect the yields of C/sub 2/H/sub 4/ and BTX. At constant methane flow rate, increase in coal flow rate decreases the yields of C/sub 2/H/sub 4/ and BTX; at constant coal flow rate, increase in methane flow rate increases the yields of C/sub 2/H/sub 4/ and BTX.

  13. A study of non-flammable gas mixture for resistive plate counter

    SciTech Connect

    Takamatsu, H.; Hoshi, Y.; Abe, K.

    1996-06-01

    The RPC (resistive plate counter) has good time and position resolution. These factors make it an attractive candidate for trigger system at collider experiment. The standard gas mixtures (Ar+iso-C{sub 4}H{sub 10}+Freon) used in RPC are very flammable when leaked into air. In view of safety issue, the authors have studied non-flammable gas of Ar+CO{sub 2}+iso-C{sub 4}H{sub 10}+Freon as a function of ratio Ar:CO{sub 2} allowed in non-flammable gas mixtures for the RPC with ABS electrodes. The basic performance of the various mixtures have been measured; singles (untriggered) count rate, detection efficiency and charge spectra versus operating voltage. They have found a set of non-flammable mixtures of the kind of AR+CO{sub 2}+Freon contained less than {approximately}8.4% of iso-C{sub 4}H{sub 10} for K{sub L}/muon counter of KEK B-factory at KEK.

  14. The structure of variable property, compressible mixing layers in binary gas mixtures

    NASA Technical Reports Server (NTRS)

    Kozusko, F.; Grosch, C. E.; Jackson, T. L.; Kennedy, Christipher A.; Gatski, Thomas B.

    1996-01-01

    We present the results of a study of the structure of a parallel compressible mixing layer in a binary mixture of gases. The gases included in this study are hydrogen (H2), helium (He), nitrogen (N2), oxygen (02), neon (Ne) and argon (Ar). Profiles of the variation of the Lewis and Prandtl numbers across the mixing layer for all thirty combinations of gases are given. It is shown that the Lewis number can vary by as much as a factor of eight and the Prandtl number by a factor of two across the mixing layer. Thus assuming constant values for the Lewis and Prandtl numbers of a binary gas mixture in the shear layer, as is done in many theoretical studies, is a poor approximation. We also present profiles of the velocity, mass fraction, temperature and density for representative binary gas mixtures at zero and supersonic Mach numbers. We show that the shape of these profiles is strongly dependent on which gases are in the mixture as well as on whether the denser gas is in the fast stream or the slow stream.

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    The viscous slip coefficient for helium-argon binary gas mixture is extracted from the experimental values of the mass flow rate through a microtube. The mass flow rate is measured by the constant-volume method. The viscous slip coefficient was obtained by identifying the measured mass flow rate through a microtube with the corresponding analytical expression, which is a function of the Knudsen number. The measurements were carried out in the slip flow regime where the first-order slip boundary condition can be applied. The measured viscous slip coefficients of binary gas mixtures exhibit a concave function of the molar ratio of the mixture, showing a similar profile with numerical results. However, from the detailed comparison between the measured and numerical values with the complete and incomplete accommodation at a surface, it is inappropriate to estimate the viscous slip coefficient for the mixture numerically by employing separately measured tangential momentum accommodation coefficient for each component. The time variation of the molar ratio in the downstream chamber was measured by sampling the gas from the chamber using the quadrupole mass spectrometer. In our measurements, it is indicated that the volume flow rate of argon is larger than that of helium because of the difference in the tangential momentum accommodation coefficient.

  16. Thermophysical properties of CF4/O2 and SF6/O2 gas mixtures

    NASA Astrophysics Data System (ADS)

    Damyanova, M.; Hohm, U.; Balabanova, E.; Barton, D.

    2016-03-01

    Fitting formulae are presented for the calculation of the second interaction virial coefficients, mixture viscosities and binary diffusion coefficients for CF4/O2 and SF6/O2 gas mixtures in the temperature range between 200 K and 1000 K. The data recommended are obtained from the isotropic (n-6) Lennard-Jones intermolecular interaction potentials of the pure substances by using the Hohm-Zarkova-Damyanova mixing rules. In general, a good agreement is observed between our results and the experimental and theoretical data found in the literature.

  17. Reactive sputtering of titanium in Ar/CH4 gas mixture: Target poisoning and film characteristics

    SciTech Connect

    Fouad, O.A.; Rumaiz, A.; Shah, S.

    2009-03-01

    Reactive sputtering of titanium target in the presence of Ar/CH{sub 4} gas mixture has been investigated. With the addition of methane gas to above 1.5% of the process gas a transition from the metallic sputtering mode to the poison mode was observed as indicated by the change in cathode current. As the methane gas flow concentration increased up to 10%, the target was gradually poisoned. The hysteresis in the cathode current could be plotted by first increasing and then subsequently decreasing the methane concentration. X-ray diffraction and X-ray photoelectron spectroscopy analyses of the deposited films confirmed the formation of carbide phases and the transition of the process from the metallic to compound sputtering mode as the methane concentration in the sputtering gas is increased. The paper discusses a sputtering model that gives a rational explanation of the target poisoning phenomenon and shows an agreement between the experimental observations and calculated results.

  18. Evolution of ideal gas mixtures confined in an insulated container by two identical pistons

    NASA Astrophysics Data System (ADS)

    Amor, Rumelo C.; Esguerra, Jose Perico H.

    2010-09-01

    We study the quasistatic adiabatic expansion of monatomic-diatomic ideal gas mixtures bounded by identical pistons and obtain closed form expressions for the temperature of the gas as a function of the time. We find that the temperature decreases as an inverse power of the time for large times, with the exponent as a function of the monatomic to diatomic gas ratio. The piston speeds increase from zero to a maximum value determined by the heat capacity of the gas and the masses of the pistons. Plots of the temperature and piston speed versus the logarithm of the time show points of inflection, which are interpreted as signaling the onset of steady state behavior. These points shift to later times as the monatomic to diatomic gas ratio is varied from purely monatomic to purely diatomic.

  19. Methods to produce calibration mixtures for anesthetic gas monitors and how to perform volumetric calculations on anesthetic gases.

    PubMed

    Christensen, P L; Nielsen, J; Kann, T

    1992-10-01

    A simple procedure for making calibration mixtures of oxygen and the anesthetic gases isoflurane, enflurane, and halothane is described. One to ten grams of the anesthetic substance is evaporated in a closed, 11,361-cc glass bottle filled with oxygen gas at atmospheric pressure. The carefully mixed gas is used to calibrate anesthetic gas monitors. By comparison of calculated and measured volumetric results it is shown that at atmospheric conditions the volumetric behavior of anesthetic gas mixtures can be described with reasonable accuracy using the ideal gas law. A procedure is described for calculating the deviation from ideal gas behavior in cases in which this is needed. PMID:1453187

  20. Implementation of Ultrasonic Sensing for High Resolution Measurement of Binary Gas Mixture Fractions

    PubMed Central

    Bates, Richard; Battistin, Michele; Berry, Stephane; Bitadze, Alexander; Bonneau, Pierre; Bousson, Nicolas; Boyd, George; Bozza, Gennaro; Crespo-Lopez, Olivier; Riva, Enrico Da; Degeorge, Cyril; Deterre, Cecile; DiGirolamo, Beniamino; Doubek, Martin; Favre, Gilles; Godlewski, Jan; Hallewell, Gregory; Hasib, Ahmed; Katunin, Sergey; Langevin, Nicolas; Lombard, Didier; Mathieu, Michel; McMahon, Stephen; Nagai, Koichi; Pearson, Benjamin; Robinson, David; Rossi, Cecilia; Rozanov, Alexandre; Strauss, Michael; Vitek, Michal; Vacek, Vaclav; Zwalinski, Lukasz

    2014-01-01

    We describe an ultrasonic instrument for continuous real-time analysis of the fractional mixture of a binary gas system. The instrument is particularly well suited to measurement of leaks of a high molecular weight gas into a system that is nominally composed of a single gas. Sensitivity < 5 × 10−5 is demonstrated to leaks of octaflouropropane (C3F8) coolant into nitrogen during a long duration (18 month) continuous study. The sensitivity of the described measurement system is shown to depend on the difference in molecular masses of the two gases in the mixture. The impact of temperature and pressure variances on the accuracy of the measurement is analysed. Practical considerations for the implementation and deployment of long term, in situ ultrasonic leak detection systems are also described. Although development of the described systems was motivated by the requirements of an evaporative fluorocarbon cooling system, the instrument is applicable to the detection of leaks of many other gases and to processes requiring continuous knowledge of particular binary gas mixture fractions. PMID:24961217

  1. Fundamental equations of a mixture of gas and small spherical solid particles from simple kinetic theory.

    NASA Technical Reports Server (NTRS)

    Pai, S. I.

    1973-01-01

    The fundamental equations of a mixture of a gas and pseudofluid of small spherical solid particles are derived from the Boltzmann equation of two-fluid theory. The distribution function of the gas molecules is defined in the same manner as in the ordinary kinetic theory of gases, but the distribution function for the solid particles is different from that of the gas molecules, because it is necessary to take into account the different size and physical properties of solid particles. In the proposed simple kinetic theory, two additional parameters are introduced: one is the radius of the spheres and the other is the instantaneous temperature of the solid particles in the distribution of the solid particles. The Boltzmann equation for each species of the mixture is formally written, and the transfer equations of these Boltzmann equations are derived and compared to the well-known fundamental equations of the mixture of a gas and small solid particles from continuum theory. The equations obtained reveal some insight into various terms in the fundamental equations. For instance, the partial pressure of the pseudofluid of solid particles is not negligible if the volume fraction of solid particles is not negligible as in the case of lunar ash flow.

  2. A study of nonflammable gas mixtures for limited streamer tubes in the VENUS detector at TRISTAN

    NASA Astrophysics Data System (ADS)

    Uebayashi, T.; Haba, J.; Kamitani, T.; Kanematsu, N.; Nagashima, Y.; Osabe, H.; Sakamoto, S.; Sugimoto, S.; Suzuki, Y.; Tsukamoto, A.; Yamashita, Y.; Sumiyoshi, T.; Takasaki, F.; Homma, Y.; Hojyo, Y.; Sakae, H.

    1988-03-01

    Performances of limited streamer tubes operated with nonflammable gas mixtures composed of argon (Ar), carbon-dioxide (CO2) and isobutane (i-C4H10) with ratios of 1:1.5:0.15, 1:2:0.2, 1:3:0.3, 1:4:0.4 and 1:6:0.6 were studied. It was found that these mixtures were very suitable for the VENUS detector. The charge spectra exhibited very sharp distributions and indicated the possibility for the limited streamer tubes to be applied to calorimetry use. A mixture of 1:2:0.2 was chosen for the VENUS streamer tubes because of its moderate gain and long efficiency plateau.

  3. A study of nonflammable gas mixtures for limited streamer tubes in the VENUS detector at TRISTAN

    NASA Astrophysics Data System (ADS)

    Uebayashi, T.; Haba, J.; Kamitani, T.; Kanematsu, N.; Nagashima, Y.; Osabe, H.; Sakamoto, S.; Sugimoto, S.; Suzuki, Y.; Tsukamoto, A.; Yamashita, Y.; Sumiyoshi, T.; Takasaki, F.; Homma, Y.; Hojyo, Y.; Sakae, H.

    1998-03-01

    Performances of limited streamer tubes operated with nonflammable gas mixtures composed of argon (Ar), carbon-dioxide (CO2) and isobutane (i-C4H10) with ratios of 1:1.5:0.15, 1:2:0.2, 1:3:0.3, 1:4:0.4 and 1:6:0.6 were studied. It was found that these mixtures were very suitable for the VENUS detector. The charge spectra exhibited very sharp distributions and indicated the possibility for the limited streamer tubes to be applied to calorimetry use. A mixture of 1:2:0.2 was chosen for the VENUS streamer tubes because of its moderate gain and long efficiency plateau.

  4. Study of thermite mixture consolidated by the cold gas dynamic spray process

    NASA Astrophysics Data System (ADS)

    Bacciochini, A.; Maines, G.; Poupart, C.; Akbarnejad, H.; Radulescu, M.; Jodoin, B.; Zhang, F.; Lee, J. J.

    2014-05-01

    The present study focused on the cold gas dynamic spray process for manufacturing porosity free, finely structured energetic materials with high reactivity and structural integrity. The experiments have focused the reaction between the aluminium and metal oxide, such as Al-CuO system. The consolidation of the materials used the cold gas dynamic spray technique, where the particles are accelerated to high speeds and consolidated via plastic deformation upon impact. Reactive composites are formed in arbitrary shapes with close to zero porosity and without any reactions during the consolidation phase. Reactivity of mixtures has been investigated through flame propagation analysis on cold sprayed samples and compacted powder mixture. Deflagration tests showed the influence of porosity on the reactivity.

  5. A Method for Calculating Viscosity and Thermal Conductivity of a Helium-Xenon Gas Mixture

    NASA Technical Reports Server (NTRS)

    Johnson, Paul K.

    2006-01-01

    A method for calculating viscosity and thermal conductivity of a helium-xenon (He-Xe) gas mixture was employed, and results were compared to AiResearch (part of Honeywell) analytical data. The method of choice was that presented by Hirschfelder with Singh's third-order correction factor applied to thermal conductivity. Values for viscosity and thermal conductivity were calculated over a temperature range of 400 to 1200 K for He-Xe gas mixture molecular weights of 20.183, 39.94, and 83.8 kg/kmol. First-order values for both transport properties were in good agreement with AiResearch analytical data. Third-order-corrected thermal conductivity values were all greater than AiResearch data, but were considered to be a better approximation of thermal conductivity because higher-order effects of mass and temperature were taken into consideration. Viscosity, conductivity, and Prandtl number were then compared to experimental data presented by Taylor.

  6. [Effect of krypton-containing gas mixture on Japanese quail embryo development].

    PubMed

    Kussmaul', A R; Gur'eva, T S; Dadasheva, O A; Pavlov, N B; Pavlov, B N

    2008-01-01

    Investigated were effects of gas mixture with up to 3.0 kgs/cm2 of krypton on the embryonic development of domesticated Japanese quail (Coturnix coturnix japonica dom.). Results demonstrated absence of a serious krypton effect on Japanese quail embryos. Development of embryos proceeded in due course; morphometrically the experimental embryos were essentially similar to controls. It should be noted that despite exposure to acute hypoxic hypoxia during the initial 12 hours of development in the krypton-containing gas mixture, viability of quail embryos was high enough which can be ascribed to the krypton protective action. Besides, an additional experiment showed that krypton partial pressure of 5-5.5 kgs/cm2 produces the narcotic effect on adult Japanese quails.

  7. Atomically detailed models of gas mixture diffusion through CuBTC membranes

    SciTech Connect

    Keskin S; Liu JC; Johnson JK.

    2009-10-01

    Metal–organic frameworks are intriguing crystalline nanoporous materials that have potential applications in adsorption-based and membrane-based gas separations. We describe atomically detailed simulations of gas adsorption and diffusion in CuBTC that have been used to predict the performance of CuBTC membranes for separation of H2/CH4, CO2/CH4 and CO2/H2 mixtures. CuBTC membranes are predicted to have higher selectivities for all three mixtures than MOF-5 membranes, the only other metal–organic framework material for which detailed predictions of membrane selectivities have been made. Our results give insight into the physical properties that will be desirable in tuning the pore structure of MOFs for specific membrane-based separations

  8. Study of thermite mixtures consolidated by cold gas dynamic spray process

    NASA Astrophysics Data System (ADS)

    Bacciochini, Antoine; Maines, Geoffrey; Poupart, Christian; Radulescu, Matei; Jodoin, Bertrand; Lee, Julian

    2013-06-01

    The present study focused on the cold gas dynamic spray process for manufacturing finely structured energetic materials with high reactivity, vanishing porosity, as well as structural integrity and arbitrary shape. The experiments have focused the reaction between the aluminum and metal oxides, such as Al-CuO and Al-MoO3 systems. To increase the reactivity, an initial mechanical activation was achieved through interrupted ball milling. The consolidation of the materials used the supersonic cold gas spray technique, where the particles are accelerated to high speeds and consolidated via plastic deformation upon impact, forming activated nano-composites in arbitrary shapes with close to zero porosity. This technique permits to retain the feedstock powder micro-structure and prevents any reactions during the consolidation phase. Reactivity of mixtures has been investigated through flame propagation analysis on cold sprayed samples and compacted powder mixture. Deflagration tests showed the influence of porosity on the reactivity.

  9. Eco-friendly gas mixtures for Resistive Plate Chambers based on tetrafluoropropene and Helium

    NASA Astrophysics Data System (ADS)

    Abbrescia, M.; Benussi, L.; Piccolo, D.; Bianco, S.; Ferrini, M.; Muhammad, S.; Passamonti, L.; Pierluigi, D.; Piccolo, D.; Primavera, F.; Russo, A.; Saviano, G.

    2016-08-01

    Due to the recent restrictions deriving from the application of the Kyoto protocol, the main components of the gas mixtures presently used in the Resistive Plate Chambers systems of the LHC experiments will be most probably phased out of production in the coming years. Identifying possible replacements with the adequate characteristics requires an intense R&D activity, which was recently started, in collaborations with various experiments. Possible new gases have been proposed and are thoroughly investigated. Some tests on one of the most promising candidate—HFO-1234ze, an allotropic form of tetrafluoropropane—have already been reported. Here an innovative approach, based on the use of Helium, to solve the problem related to the high operating voltage needed to operate the chambers with HFO-1234ze based gas mixtures, is discussed and the first results are shown.

  10. Cryotrapping assisted mass spectrometry for the analysis of complex gas mixtures

    SciTech Connect

    Ferreira, Jose A.; Tabares, Francisco L.

    2007-03-15

    A simple method is described for the unambiguous identification of the individual components in a gas mixture showing strong overlapping of their mass spectrometric cracking patterns. The method, herein referred to as cryotrapping assisted mass spectrometry, takes advantage of the different vapor pressure values of the individual components at low temperature (78 K for liquid nitrogen traps), and thus of the different depletion efficiencies and outgassing patterns during the fast cooling and slow warming up of the trap, respectively. Examples of the use of this technique for gas mixtures with application to plasma enhanced chemical vapor deposition of carbon and carbon-nitrogen hard films are shown. Detection of traces of specific C{sub 3} hydrocarbons (<50 ppm of initial methane) in methane/hydrogen plasmas and the possible trapping of thermally unstable C-N compounds in N{sub 2} containing deposition plasmas are addressed as representative examples of specific applications of the technique.

  11. Viscous shock layer solutions for turbulent flow of radiating gas mixtures in chemical equilibrium

    NASA Technical Reports Server (NTRS)

    Anderson, E. C.; Moss, J. N.

    1975-01-01

    The viscous shock layer equations for hypersonic laminar and turbulent flows of radiating or nonradiating gas mixtures in chemical equilibrium are presented for two-dimensional and axially symmetric flow fields. Solutions are obtained using an implicit finite difference scheme and results are presented for hypersonic flow over spherically blunted cone configurations at free stream conditions representative of entry into the atmosphere of Venus. These data are compared with solutions obtained using other methods of analysis.

  12. Viscous-shock-layer solutions for turbulent flow of radiating gas mixtures in chemical equilibrium

    NASA Technical Reports Server (NTRS)

    Anderson, E. C.; Moss, J. N.

    1975-01-01

    The viscous-shock-layer equations for hypersonic laminar and turbulent flows of radiating or nonradiating gas mixtures in chemical equilibrium are presented for two-dimensional and axially-symmetric flow fields. Solutions were obtained using an implicit finite-difference scheme and results are presented for hypersonic flow over spherically-blunted cone configurations at freestream conditions representative of entry into the atmosphere of Venus. These data are compared with solutions obtained using other methods of analysis.

  13. Adsorption process to recover hydrogen from feed gas mixtures having low hydrogen concentration

    DOEpatents

    Golden, Timothy Christopher; Weist, Jr., Edward Landis; Hufton, Jeffrey Raymond; Novosat, Paul Anthony

    2010-04-13

    A process for selectively separating hydrogen from at least one more strongly adsorbable component in a plurality of adsorption beds to produce a hydrogen-rich product gas from a low hydrogen concentration feed with a high recovery rate. Each of the plurality of adsorption beds subjected to a repetitive cycle. The process comprises an adsorption step for producing the hydrogen-rich product from a feed gas mixture comprising 5% to 50% hydrogen, at least two pressure equalization by void space gas withdrawal steps, a provide purge step resulting in a first pressure decrease, a blowdown step resulting in a second pressure decrease, a purge step, at least two pressure equalization by void space gas introduction steps, and a repressurization step. The second pressure decrease is at least 2 times greater than the first pressure decrease.

  14. Process and catalyst for converting synthesis gas to liquid hydrocarbon mixture

    DOEpatents

    Rao, V. Udaya S.; Gormley, Robert J.

    1987-01-01

    Synthesis gas containing CO and H.sub.2 is converted to a high-octane hydrocarbon liquid in the gasoline boiling point range by bringing the gas into contact with a heterogeneous catalyst including, in physical mixture, a zeolite molecular sieve, cobalt at 6-20% by weight, and thoria at 0.5-3.9% by weight. The contacting occurs at a temperature of 250.degree.-300.degree. C., and a pressure of 10-30 atmospheres. The conditions can be selected to form a major portion of the hydrocarbon product in the gasoline boiling range with a research octane of more than 80 and less than 10% by weight aromatics.

  15. Comparison of primary standard gas mixtures: gravimetric production of carbon monoxide in nitrogen (3 μmol/mol)

    NASA Astrophysics Data System (ADS)

    Konopelko, L. A.; Kustikov, Y. A.; Kolobova, A. V.; Pankratov, V. V.; Pankov, A. A.; Efremova, O. V.; Augusto, Cristiane R.; Fioravante, Andreia L.; Ribeiro, Claudia C.; Teixeira, Denise C. G. S.; Elias, Elizandra C. S.; Oudwater, Rutger J.; Fagundes, Fátima A.; Silva, Marceli C.

    2016-01-01

    COOMET.QM-S3 is a supplementary comparison of primary standard gas mixtures—'Carbon monoxide in Nitrogen (3 μmol/mol)'. This is a bilateral comparison between VNIIM and INMETRO and it was conducted in 2013. Carbon monoxide is a toxic gas and in concentrations higher than 3-5 μmol/mol it is hazardous to human health. Therefore, it is important for NMIs to have the capability of an accurate carbon monoxide measurements. This comparison has shown that primary standard gas mixtures of carbon monoxide in nitrogen on the level of 3 μmol/mol, prepared in VNIIM and Inmetro, do not agree—the pair-wise degree of equivalence D (0.77%) is higher than the appropriate expanded uncertainty U(D) (0.29%). Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  16. Plasma nitriding using high H2 content gas mixtures for a cavitation erosion resistant steel

    NASA Astrophysics Data System (ADS)

    Allenstein, A. N.; Lepienski, C. M.; Buschinelli, A. J. A.; Brunatto, S. F.

    2013-07-01

    Plasma nitriding using high H2 content gas mixtures in CA-6NM martensitic stainless steel was studied in the present work. Nitriding was performed in H2 + N2 gas mixtures for 5, 10 and 20% N2, in volume, at 773 K (500 °C), during 2 h. Changes in the surface morphology and nitrided layer constitution were characterized by SEM, XRD, roughness analysis, and nanoindentation technique. Cavitation erosion behavior of the nitrided samples was also investigated by means of a 20 kHz ultrasonic vibrator. The study was emphasized for the three first cavitation stages (incubation, acceleration, and maximum erosion rate stage) of the cumulative erosion-time curve. Results indicate that the gas mixture nitrogen content strongly influences the phases' formation and its distribution on the nitrided layer. Better cavitation erosion resistance which was attributed to the finer and more homogeneous distribution of the nitrided layer phases was verified for samples treated at 5% N2. Otherwise, worse cavitation erosion behavior for samples nitrided at 20% N2 is supposed to be due to the formation of multiphase compound layer constituted by Fe4N + Fe2-3N + CrN, which can infer residual stress in treated surface.

  17. A general stagnation-point convective heating equation for arbitrary gas mixtures

    NASA Technical Reports Server (NTRS)

    Sutton, K.; Graves, R. A., Jr.

    1971-01-01

    The stagnation-point convective heat transfer to an axisymmetric blunt body for arbitrary gases in chemical equilibrium was investigated. The gases considered were base gases of nitrogen, oxygen, hydrogen, helium, neon, argon, carbon dioxide, ammonia, and methane and 22 gas mixtures composed of the base gases. Enthalpies ranged from 2.3 to 116.2 MJ/kg, pressures ranged from 0.001 to 100 atmospheres, and the wall temperatures were 300 and 1111 K. A general equation for the stagnation-point convective heat transfer in base gases and gas mixtures was derived and is a function of the mass fraction, the molecular weight, and a transport parameter of the base gases. The relation compares well with present boundary-layer computer results and with other analytical and experimental results. In addition, the analysis verified that the convective heat transfer in gas mixtures can be determined from a summation relation involving the heat transfer coefficients of the base gases. The basic technique developed for the prediction of stagnation-point convective heating to an axisymmetric blunt body could be applied to other heat transfer problems.

  18. Extremely low flow tracheal gas insufflation of helium-oxygen mixture improves gas exchange in a rabbit model of piston-type high-frequency oscillatory ventilation

    PubMed Central

    2013-01-01

    Objective The purpose of this study was to show the effects of the tracheal gas insufflation (TGI) technique on gas exchange using helium-oxygen mixtures during high-frequency oscillatory ventilation (HFOV). We hypothesized that a helium-oxygen mixture delivered into the trachea using the TGI technique (0.3 L/min) would enhance gas exchange during HFOV. Methods Three rabbits were prepared and ventilated by HFOV with carrier 70% helium/oxygen or 70% nitrogen/oxygen gas mixture with TGI in a crossover study. Changing the gas mixture from nitrogen70% to helium70% and back was performed three times per animal with constant ventilation parameters. Results Compared with the nitrogen-oxygen mixture, the helium-oxygen mixture of TGI reduced PaCO2 by 7.6 mmHg (p < 0.01) and improved PaO2 by 14 mmHg (p < 0.01). Amplitude during TGI was significantly lower with the helium-oxygen mixture than with the nitrogen-oxygen mixture (p < 0.01) and did not significantly affect mean airway pressure. Conclusions This study demonstrated that a helium-oxygen mixture delivered into the trachea using the TGI technique would enhance CO2 elimination and improve oxygenation during HFOV. PMID:23566050

  19. Carbon ion pump for removal of carbon dioxide from combustion gas and other gas mixtures

    DOEpatents

    Aines, Roger D.; Bourcier, William L.

    2010-11-09

    A novel method and system of separating carbon dioxide from flue gas is introduced. Instead of relying on large temperature or pressure changes to remove carbon dioxide from a solvent used to absorb it from flue gas, the ion pump method, as disclosed herein, dramatically increases the concentration of dissolved carbonate ion in solution. This increases the overlying vapor pressure of carbon dioxide gas, permitting carbon dioxide to be removed from the downstream side of the ion pump as a pure gas. The ion pumping may be obtained from reverse osmosis, electrodialysis, thermal desalination methods, or an ion pump system having an oscillating flow in synchronization with an induced electric field.

  20. Carbon ion pump for removal of carbon dioxide from combustion gas and other gas mixtures

    DOEpatents

    Aines, Roger D.; Bourcier, William L.

    2014-08-19

    A novel method and system of separating carbon dioxide from flue gas is introduced. Instead of relying on large temperature or pressure changes to remove carbon dioxide from a solvent used to absorb it from flue gas, the ion pump method, as disclosed herein, dramatically increases the concentration of dissolved carbonate ion in solution. This increases the overlying vapor pressure of carbon dioxide gas, permitting carbon dioxide to be removed from the downstream side of the ion pump as a pure gas. The ion pumping may be obtained from reverse osmosis, electrodialysis, thermal desalination methods, or an ion pump system having an oscillating flow in synchronization with an induced electric field.

  1. Adiabatic temperature changes of magma-gas mixtures during ascent and eruption

    USGS Publications Warehouse

    Mastin, L.G.; Ghiorso, M.S.

    2001-01-01

    Most quantitative studies of flow dynamics in eruptive conduits during volcanic eruptions use a simplified energy equation that ignores either temperature changes, or the thermal effects of gas exsolution. In this paper we assess the effects of those simplifications by analyzing the influence of equilibrium gas exsolution and expansion on final temperatures, velocities, and liquid viscosities of magma-gas mixtures during adiabatic decompression. For a given initial pressure (p1), temperature (T1) and melt composition, the final temperature (Tf) and velocity (Umax) will vary depending on the degree to which friction and other irreversible processes reduce mechanical energy within the conduit. The final conditions range between two thermodynamic end members: (1) Constant enthalpy (dh=0), in which Tf is maximal and no energy goes into lifting or acceleration; and (2) constant entropy (ds=0), in which Tf is minimal and maximum energy goes into lifting and acceleration. For ds=0, T1=900 ??C and p1=200 MPa, a water-saturated albitic melt cools by ???200 ??C during decompression, but only about 250 ??C of this temperature decrease can be attributed to the energy of gas exsolution per se: The remainder results from expansion of gas that has already exsolved. For the same T1 and p1, and dh=0, Tf is 10-15 ??C hotter than T1 but is about 10-25 ??C cooler than Tf in similar calculations that ignore the energy of gas exsolution. For ds=0, p1=200 MPa and T1= 9,000 ??C, assuming that all the enthalpy change of decompression goes into kinetic energy, a water-saturated albitic mixture can theoretically accelerate to ???800 m/s. Similar calculations that ignore gas exsolution (but take into account gas expansion) give velocities about 10-15% higher. For the same T1, p1 = 200 MPa, and ds = 0, the cooling associated with gas expansion and exsolution increases final melt viscosity more than 2.5 orders of magnitude. For dh = 0, isenthalpic heating decreases final melt viscosity by about

  2. [Fire disaster due to deflagration of a propane gas-air mixture].

    PubMed

    Nadjem, Hadi; Vogt, Susanne; Simon, Karl-Heinz; Pollak, Stefan; Geisenberger, Dorothee; Kramer, Lena; Pircher, Rebecca; Perdekampl, Markus Große; Thierauf-Emberger, Annette

    2015-01-01

    On 26 Nov 2012, a serious fire occurred at Neustadt/Black Forest in which 14 persons in a sheltered workshop died and 10 other individuals were injured. The fire was caused by the unbridled escape of propane gas due to accidental disconnection of the screw fixing between a gas bottle and a catalytic heater. Deflagration of the propane gas-air mixture set the workshop facilities on fire. In spite of partly extensive burns the fatally injured victims could be rapidly identified. The results of the fire investigations at the scene and the autopsy findings are presented. Carboxyhemoglobin concentrations ranged between 8 and 56 % and signs of fire fume inhalation were present in all cases. Three victims had eardrum ruptures due to the sudden increase in air pressure during the deflagration. PMID:26548032

  3. [Fire disaster due to deflagration of a propane gas-air mixture].

    PubMed

    Nadjem, Hadi; Vogt, Susanne; Simon, Karl-Heinz; Pollak, Stefan; Geisenberger, Dorothee; Kramer, Lena; Pircher, Rebecca; Perdekampl, Markus Große; Thierauf-Emberger, Annette

    2015-01-01

    On 26 Nov 2012, a serious fire occurred at Neustadt/Black Forest in which 14 persons in a sheltered workshop died and 10 other individuals were injured. The fire was caused by the unbridled escape of propane gas due to accidental disconnection of the screw fixing between a gas bottle and a catalytic heater. Deflagration of the propane gas-air mixture set the workshop facilities on fire. In spite of partly extensive burns the fatally injured victims could be rapidly identified. The results of the fire investigations at the scene and the autopsy findings are presented. Carboxyhemoglobin concentrations ranged between 8 and 56 % and signs of fire fume inhalation were present in all cases. Three victims had eardrum ruptures due to the sudden increase in air pressure during the deflagration.

  4. Electron Density Measurements in UV-Preionized XeCl and CO2 Laser Gas Mixtures

    NASA Astrophysics Data System (ADS)

    Takagi, Shigeyuki; Sato, Saburo; Goto, Tatsumi

    1989-11-01

    A Langmuir probe technique has been used to measure electron densities and temperatures in UV-preionized XeCl excimer and CO2 laser gas mixtures in a laser tube. For this experiment, only pin electrodes (preionization sparks) were operated with no discharge between the main electrodes. The measured electron densities were about 108 cm-3 in both the excimer and CO2 laser gases, compared with 1010 cm-3 in pure He gas. The electron density was found to increase due to the proximity of the main electrodes. The coefficients of absorption for excimer and CO2 laser gas were obtained from the characteristics of the electron densities vs the distance from the UV source. Based on the absorption coefficient for XeCl, 0.9 cm-1 atm-1, we propose pin-electrode arrangements for spatially uniform preionization.

  5. Additional development of large diameter carbon monofilament. [from boron, hydrogen, and methane gas mixture

    NASA Technical Reports Server (NTRS)

    Jacob, B. A.; Veltri, R. D.

    1974-01-01

    The chemical vapor process for preparing a large diameter carbon-base monofilament from a BCl3, Ch4 and H2 gas mixture with a carbon substrate fiber was studied. The effect of reactor geometry, total gas flows and deposition temperature on the tensile strength of the monofilament were investigated. It was noted that consistent results could only be obtained when the carbon substrate fiber was cleaned. The strength of the monofilament was found to depend on the highest temperature and the temperature profile of the monofilament in the reactor. The strength of monofilament produced in the dc and RF reactors were found to be similar and similar alloy compositions in the monofilament were attained when the same gas ratios were used. The tensile strength of the monofilament at 500 C was found to be 60 to 70% of the room temperature tensile strength. No degradation was noted after exposure to molten aluminum.

  6. A computational investigation of the effectiveness of different shielding gas mixtures for arc welding

    NASA Astrophysics Data System (ADS)

    Murphy, A. B.; Tanaka, M.; Tashiro, S.; Sato, T.; Lowke, J. J.

    2009-06-01

    Tungsten-inert-gas welding arcs are modelled using a two-dimensional axisymmetric computational code. Both electrodes (the tungsten cathode and the metal anode workpiece) and the arc plasma are included self-consistently in the computational domain. The influence of adding helium, hydrogen and nitrogen to the argon shielding gas is investigated. It is found that addition of any of the gases increases the heat flow to and the current density at the anode. The shear stress and the arc pressure at the anode surface are increased by adding hydrogen or nitrogen or up to about 50 mol% helium, but decrease when more helium is added. It is predicted that the effect of adding any of the gases is to increase the depth of the weld pool, in agreement with the experimental evidence. The results are explained by referring to the thermodynamic and transport properties of the gas mixtures.

  7. Atmospheric pressure glow discharge generated in nitrogen-methane gas mixture: PTR-MS analyzes of the exhaust gas

    NASA Astrophysics Data System (ADS)

    Torokova, Lucie; Mazankova, Vera; Krcma, Frantisek; Mason, Nigel J.; Matejcik, Stefan

    2015-07-01

    This paper reports the results of an extensive study of with the in situ mass spectrometry analysis of gaseous phase species produced by an atmospheric plasma glow discharge in N2-CH4 gas mixtures (with methane concentrations ranging from 1% to 4%). The products are studied using proton-transfer-reaction mass spectrometry (PTR-MS). HCN and CH3CN are identified as the main gaseous products. Hydrazine, methanimine, methyldiazene, ethylamine, cyclohexadiene, pyrazineacetylene, ethylene, propyne and propene are identified as minor compounds. All the detected compounds and their relative abundances are determined with respect to the experimental conditions (gas composition and applied power). The same molecules were observed by the Cassini-Huygens probe in Titan's atmosphere (which has same N2-CH4 gas mixtures). Such, experiments show that the formation of such complex organics in atmospheres containing C, N and H, like that of Titan, could be a source of prebiotic molecules. Contribution to the topical issue "The 14th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XIV)", edited by Nicolas Gherardi, Ronny Brandenburg and Lars Stollenwark

  8. Industrial Compositional Streamline Simulation for Efficient and Accurate Prediction of Gas Injection and WAG Processes

    SciTech Connect

    Margot Gerritsen

    2008-10-31

    Gas-injection processes are widely and increasingly used for enhanced oil recovery (EOR). In the United States, for example, EOR production by gas injection accounts for approximately 45% of total EOR production and has tripled since 1986. The understanding of the multiphase, multicomponent flow taking place in any displacement process is essential for successful design of gas-injection projects. Due to complex reservoir geometry, reservoir fluid properties and phase behavior, the design of accurate and efficient numerical simulations for the multiphase, multicomponent flow governing these processes is nontrivial. In this work, we developed, implemented and tested a streamline based solver for gas injection processes that is computationally very attractive: as compared to traditional Eulerian solvers in use by industry it computes solutions with a computational speed orders of magnitude higher and a comparable accuracy provided that cross-flow effects do not dominate. We contributed to the development of compositional streamline solvers in three significant ways: improvement of the overall framework allowing improved streamline coverage and partial streamline tracing, amongst others; parallelization of the streamline code, which significantly improves wall clock time; and development of new compositional solvers that can be implemented along streamlines as well as in existing Eulerian codes used by industry. We designed several novel ideas in the streamline framework. First, we developed an adaptive streamline coverage algorithm. Adding streamlines locally can reduce computational costs by concentrating computational efforts where needed, and reduce mapping errors. Adapting streamline coverage effectively controls mass balance errors that mostly result from the mapping from streamlines to pressure grid. We also introduced the concept of partial streamlines: streamlines that do not necessarily start and/or end at wells. This allows more efficient coverage and avoids

  9. Kinetic model for the vibrational energy exchange in flowing molecular gas mixtures. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Offenhaeuser, F.

    1987-01-01

    The present study is concerned with the development of a computational model for the description of the vibrational energy exchange in flowing gas mixtures, taking into account a given number of energy levels for each vibrational degree of freedom. It is possible to select an arbitrary number of energy levels. The presented model uses values in the range from 10 to approximately 40. The distribution of energy with respect to these levels can differ from the equilibrium distribution. The kinetic model developed can be employed for arbitrary gaseous mixtures with an arbitrary number of vibrational degrees of freedom for each type of gas. The application of the model to CO2-H2ON2-O2-He mixtures is discussed. The obtained relations can be utilized in a study of the suitability of radiation-related transitional processes, involving the CO2 molecule, for laser applications. It is found that the computational results provided by the model agree very well with experimental data obtained for a CO2 laser. Possibilities for the activation of a 16-micron and 14-micron laser are considered.

  10. Separation of Fischer-Tropsch catalyst/wax mixtures using dense gas extraction

    SciTech Connect

    Eyring, M.W.; Rohar, P.C.; Hickey, R.F.

    1995-12-01

    The separation of a Fischer-Tropsch catalyst from wax products is an important issue when the synthesis is conducted in a slurry bubble column reactor. This paper describes a new technique based on dense gas extraction of the soluble hydrocarbon components from the insoluble catalyst particles using light hydrocarbons as propane, butane, and pentane as the solvent. The extractions were conducted in a continuous unit operated near the critical point of the extraction gas on a catalyst/wax mixture containing about 4.91 wt% catalyst. The catalyst-free wax was collected in the second stage collector while the catalyst and some insoluble wax components were collected in the first stage collector. The yield of catalyst-free wax was about 60 wt% of the feed mixture. The catalyst content of the catalyst/wax mixture in the first stage was about 14.8 wt%. The catalyst content in the second stage collector was less than 1 part in 100,000.

  11. Separation of Fischer-Tropsch catalyst/wax mixtures using dense gas extraction

    SciTech Connect

    Eyring, M.W.; Rohar, P.C.; Hickey, R.F.; White, C.M.; Quiring, M.S.

    1995-12-31

    The separation of a Fischer-Tropsch catalyst from wax products is an important issue when the synthesis is conducted in a slurry bubble column reactor. This paper describes a new technique based on dense gas extraction of the soluble hydrocarbon components from the insoluble catalyst particles using light hydrocarbons as propane, butane, and pentane an the solvent. The extractions were conducted in a continuous unit operated near the critical point of the extraction gas on a catalyst/wax mixture containing about 4.91 wt% catalyst. The catalyst-free wax was collected in the second stage collector while the catalyst and some insoluble wax components were collected in the first stage collector. The yield of catalyst-free wax was about 60 wt% of the food mixture. The catalyst content of the catalyst/wax mixture in the first stage was about 14.8 wt%. The catalyst content in the second stage collector was less than 1 part in 100,000.

  12. Study on a pulse tube cryocooler using gas mixture as its working fluid

    NASA Astrophysics Data System (ADS)

    Gao, C. M.; He, Y. L.; Chen, Z. Q.

    2000-01-01

    In order to improve the performance of a one-stage pulse tube cryocooler, gas mixtures are used for comparison, which have been used in other cryocoolers. A mixture of hydrogen and helium was investigated in this study. When the structure of the pulse tube is the same as mentioned in [C. Wang, P.Y. Wu, Zh.Q. Chen, Numerical modeling of an orifice pulse tube cryocooler, Cryogenics 32 (1992) 785] and the working conditions are: frequency 15 Hz, average pressure 1.1 MPa, hot end temperature 300 K and cold end temperature 80 K, it has been found that there are optimal molar percentage for the maximal cooling power and the maximal-coefficient of performance (COP) of this cryocooler.

  13. Discrete velocity computations with stochastic variance reduction of the Boltzmann equation for gas mixtures

    SciTech Connect

    Clarke, Peter; Varghese, Philip; Goldstein, David

    2014-12-09

    We extend a variance reduced discrete velocity method developed at UT Austin [1, 2] to gas mixtures with large mass ratios and flows with trace species. The mixture is stored as a collection of independent velocity distribution functions, each with a unique grid in velocity space. Different collision types (A-A, A-B, B-B, etc.) are treated independently, and the variance reduction scheme is formulated with different equilibrium functions for each separate collision type. The individual treatment of species enables increased focus on species important to the physics of the flow, even if the important species are present in trace amounts. The method is verified through comparisons to Direct Simulation Monte Carlo computations and the computational workload per time step is investigated for the variance reduced method.

  14. Helium detection in gas mixtures by laser-induced breakdown spectroscopy.

    PubMed

    Eseller, Kemal E; Yueh, Fang-Yu; Singh, Jagdish P; Melikechi, Noureddine

    2012-03-01

    Laser-induced breakdown spectroscopy (LIBS) has been evaluated as a tool for monitoring trace levels of helium in gas mixtures consisting mostly of hydrogen. Calibration data for helium in hydrogen was investigated at different helium concentration levels. At high concentrations of helium (>7.25%), the LIBS signal is quenched due to Penning ionization. The hydrogen alpha line (656.28 nm) was observed to broaden as the concentration of helium impurities in the hydrogen gas mixture increased. The helium line at 587.56 nm was selected as the analyte line for helium impurity detection. The effects of laser energy, the delay time between the laser pulse and data acquisition, and the gas pressure on the LIBS signal of helium were investigated to determine the optimum conditions for helium detection. The LIBS signal from the helium line at 587.56 nm shows good linear correlation with helium concentration for He concentrations below 1%. Thus, LIBS can be reliably used to detect the low levels of helium. The limit of detection for helium was found to be 78 ppm.

  15. Precision measurement of timing RPC gas mixtures with laser-beam induced electrons

    NASA Astrophysics Data System (ADS)

    Naumann, L.; Siebold, M.; Kaspar, M.; Kämpfer, B.; Kotte, R.; Laso Garcia, A.; Löser, M.; Schramm, U.; Wüstenfeld, J.

    2014-10-01

    The main goals of a new test facility at Helmholtz-Zentrum Dresden-Rossendorf are precision measurements of the electron drift velocity and the Townsend coefficient of gases at atmospheric pressure in the strongest ever used homogenous electrical fields and the search for new RPC gas mixtures to substitute the climate harmful Freon. Picosecond UV laser pulses were focused into a sub-millimeter gas gap to initialize a defined tiny charge. These gaps are formed by electrodes of low-resistive ceramics or high-resistive float glass. The charge multiplication occurs in a strong homogeneous electric field of up to 100 kV/cm. Electron-ion pairs were generated in a cylindrical micro-volume by multi-photon ionization. The laser-pulse repetition rate ranges from 1 Hz to a few kHz. The RPC time resolution has been measured for different gases. First results of the Townsend coefficient at 100 kV/cm show a strong disagreement between the present measurement and Magboltz simulations for the typical timing RPC gas mixture C2F4H2/SF6/i-C4H10, while the measured electron drift velocities are in a good agreement with the model predictions.

  16. Implementing an Inexpensive and Accurate Introductory Gas Density Activity with High School Students

    ERIC Educational Resources Information Center

    Cunningham, W. Patrick; Joseph, Christopher; Morey, Samantha; Santos Romo, Ana; Shope, Cullen; Strang, Jonathan; Yang, Kevin

    2015-01-01

    A simplified activity examined gas density while employing cost-efficient syringes in place of traditional glass bulbs. The exercise measured the density of methane, with very good accuracy and precision, in both first-year high school and AP chemistry settings. The participating students were tasked with finding the density of a gas. The…

  17. Evaluation of the age of landfill gas methane in landfill gas-natural gas mixtures using co-occurring constituents.

    PubMed

    Kerfoot, Henry B; Hagedorn, Benjamin; Verwiel, Mark

    2013-06-01

    At a municipal solid waste landfill in southern California (USA) overlying a natural gas reservoir, methane was detected at concentrations of up to 40% (by volume) in perimeter soil gas probes. Stable isotope and (14)C values of methane together with gas composition (major components and volatile organic compounds) data were evaluated to assess the relative contributions of landfill gas and natural gas to the measured methane concentrations. The data was further used to estimate the residence time of the landfill gas in the probes. Results showed that up to 37% of the measured methane was derived from landfill gas. In addition, the landfill gas in the probe samples has undergone extensive alteration due to dissolution of carbon dioxide in pore water. Data further indicates that the measured methane was released from the waste approximately 1.2 to 9.4 years ago, rather than representing evidence of an ongoing release.

  18. An investigation of condensation from steam-gas mixtures flowing downward inside a vertical tube

    SciTech Connect

    Kuhn, S.Z.; Schrock, V.E.; Peterson, P.F.

    1995-09-01

    Previous experiments have been carried out by Vierow, Ogg, Kageyama and Siddique for condensation from steam/gas mixtures in vertical tubes. In each case the data scatter relative to the correlation was large and there was not close agreement among the three investigations. A new apparatus has been designed and built using the lessons learned from the earlier studies. Using the new apparatus, an extensive new data base has been obtained for pure steam, steam-air mixtures and steam-helium mixtures. Three different correlations, one implementing the degradation method initially proposed by Vierow and Schrock, a second diffusion layer theory initially proposed by Peterson, and third mass transfer conductance model are presented in this paper. The correlation using the simple degradation factor method has been shown, with some modification, to give satisfactory engineering accuracy when applied to the new data. However, this method is based on very simplified arguments that do not fully represent the complex physical phenomena involved. Better representation of the data has been found possible using modifications of the more complex and phenomenologically based method which treats the heat transfer conductance of the liquid film in series with the conductance on the vapor-gas side with the latter comprised of mass transfer and sensible heat transfer conductance acting in parallel. The mechanistic models, based on the modified diffusion layer theory or classical mass transfer theory for mass transfer conductance with transpiration successfully correlate the data for the heat transfer of vapor-gas side. Combined with the heat transfer of liquid film model proposed by Blangetti, the overall heat transfer coefficients predicted by the correlations from mechanistic models are in close agreement with experimental values.

  19. [Quantitative Analysis of the Hydration Process of Mine Gas Mixture Based on Raman Spectroscopy].

    PubMed

    Zhang, Bao-yong; Yu, Yue; Wu, Qiang; Gao, Xia

    2015-07-01

    The research on micro crystal structure of mine gas hydrate is especially significant for the technology of gas hydrate separation. Using Raman spectroscopy to observe hydration process of 3 kinds of mine gas mixture on line which contains high concentration of carbon dioxide, this experiment obtained the information of the hydrate crystals including large and small cage occupancy. Meanwhile obtained the hydration number indirectly based on the statistical thermodynamic model of van der Waals and Platteeuw. The results show that cage occupancy and hydration number of mine gas hydrates change little during different growth stages. The large cages of hydrate phases are nearly full occupied by carbon dioxide and methane molecules together, with the occupancy ratios between 97.70% and 98.68%. Most of the guest molecules in large cages is carbon dioxide (78.58%-94.09%) and only a few (4.52%-19.12%) is filled with methane, it is because carbon dioxide concentration in the gas sample is higher than methane and there is competition between them. However the small cage occupancy ratios is generally low in the range from 17.93% to 82.41%, and the guest molecules are all methane. With the increase of methane concentration in gas sample, the cage occupancy both large and small which methane occupied has increased, meanwhile the large cage occupancy which methane occupied is lower than small cage. The hydration numbers of mine gas hydrate during different growth stages are between 6.13 and 7.33. Small cage occupancy has increased with the increase of methane concentration, this lead to hydration number decreases. Because of the uneven distribution of hydrate growth, the hydration numbers of 3 kinds of gas samples show irregular change during different growth stages. PMID:26717751

  20. [Quantitative Analysis of the Hydration Process of Mine Gas Mixture Based on Raman Spectroscopy].

    PubMed

    Zhang, Bao-yong; Yu, Yue; Wu, Qiang; Gao, Xia

    2015-07-01

    The research on micro crystal structure of mine gas hydrate is especially significant for the technology of gas hydrate separation. Using Raman spectroscopy to observe hydration process of 3 kinds of mine gas mixture on line which contains high concentration of carbon dioxide, this experiment obtained the information of the hydrate crystals including large and small cage occupancy. Meanwhile obtained the hydration number indirectly based on the statistical thermodynamic model of van der Waals and Platteeuw. The results show that cage occupancy and hydration number of mine gas hydrates change little during different growth stages. The large cages of hydrate phases are nearly full occupied by carbon dioxide and methane molecules together, with the occupancy ratios between 97.70% and 98.68%. Most of the guest molecules in large cages is carbon dioxide (78.58%-94.09%) and only a few (4.52%-19.12%) is filled with methane, it is because carbon dioxide concentration in the gas sample is higher than methane and there is competition between them. However the small cage occupancy ratios is generally low in the range from 17.93% to 82.41%, and the guest molecules are all methane. With the increase of methane concentration in gas sample, the cage occupancy both large and small which methane occupied has increased, meanwhile the large cage occupancy which methane occupied is lower than small cage. The hydration numbers of mine gas hydrate during different growth stages are between 6.13 and 7.33. Small cage occupancy has increased with the increase of methane concentration, this lead to hydration number decreases. Because of the uneven distribution of hydrate growth, the hydration numbers of 3 kinds of gas samples show irregular change during different growth stages.

  1. Method of testing gas insulated systems for the presence of conducting particles utilizing a gas mixture of nitrogen and sulfur hexafluoride

    DOEpatents

    Wootton, Roy E.

    1979-01-01

    A method of testing a gas insulated system for the presence of conducting particles. The method includes inserting a gaseous mixture comprising about 98 volume percent nitrogen and about 2 volume percent sulfur hexafluoride into the gas insulated system at a pressure greater than 60 lb./sq. in. gauge, and then applying a test voltage to the system. If particles are present within the system, the gaseous mixture will break down, providing an indicator of the presence of the particles.

  2. Lasing characteristics of gas mixtures involving UFG: Application to nuclear pumping of lasers

    NASA Technical Reports Server (NTRS)

    Verdeyen, J. T.; Eden, J. G.

    1980-01-01

    Intense blue-green fluorescence from a structured band centered at lambda approximately 484 nm was observed from Ar, CF3I and NF3 gas mixtures excited by an electron beam. This emission was tentatively assigned to the E yields A transition of the iodine monofluoride (IF) molecule. The fluorescence efficiency of the IF(E yields A) band and the IF (E) state radiative lifetime were estimated to be approximately 6% and 15 ns, respectively. The emission band structure, the short IF(E) radiative lifetime and the Franck-Condon shift between the E and A states suggest that IF is an attractive candidate for a blue-green laser.

  3. Gas viscosities of azeotropic mixtures of the halogenated hydrocarbons R500, R502, and R503

    SciTech Connect

    Takahashi, M.; Yokoyama, C.; Takahashi, S.

    1988-07-01

    Gas viscosities of azeotropic mixtures R500 (dichlorodifluoromethane (R12)-1, 1-difluoroethane (R152a)), R 502 (chlorodifluoromethane (R22)-chloropentafluoroethane (R115)), and R503 (chlorotrifluoromethane (R13)-trifluoromethane (R23)) were measured with an oscillating disk viscometer of the Maxwell type at 273.15-423.15 K up to 7.5 MPa. Two empirical equations for the viscosities were obtained; one is for the atmospheric viscosities as a function of temperature, and the other is for the viscosities in the whole range of the present measurement as a function of temperature and density.

  4. Role of thermal diffusion in cw IR laser absorption in gas mixtures.

    PubMed

    Maleissye, J T; Lempereur, F

    1982-01-15

    The absorption of radiation from a cw CO(2) laser by a mixture of absorbing SF(6) and transparent buffer gases has been measured as a function of pressure of added transparent gas (C(4)H(10)). The results are analyzed in terms of thermal diffusion of excited SF6 molecules out of the irradiation zone. In the 60-400-Torr pressure range, thermal difusion depletes the concentration of SF(6) so that the overall absorption is decreased and competes with the various channels of collisional relaxation which enhance absorption. An approximate semiempirical expression is used to determine the transient perturbation of concentration which occurs inside the laser beam.

  5. Conversion of air mixture with ethanol and water vapors in nonequilibrium gas-discharge plasma

    NASA Astrophysics Data System (ADS)

    Shchedrin, A. I.; Levko, D. S.; Chernyak, V. Ya.; Yukhimenko, V. V.; Naumov, V. V.

    2009-05-01

    In search for an alternative fuel for internal combustion engines, we have studied the possibility of obtaining molecular hydrogen via the conversion of air mixture with ethanol and water vapors in a new plasma reactor. It is shown that, in agreement with experimental data, the H2 concentration is a linear function of the discharge current and decreases with increasing gas flow rate in the interelectrode gap. It is established that the proposed approach provides higher molecular hydrogen concentrations as compared to those achieved with other methods.

  6. A computer program for calculation of spectral radiative properties of gas mixtures

    NASA Technical Reports Server (NTRS)

    Nealy, J. E.

    1975-01-01

    A computer code is described whereby calculations of radiative properties of gas mixtures may be made. The program is arranged so that distinct radiative processes for each species are computed in individual subroutines. Provision is made for calculating radiative properties in nonequilibrium situations - separate rotational, vibrational, and electronic temperatures may be used. These features should provide a flexibility not currently available in such programs. The basic equations and the program listing in FORTRAN 4 language are presented. Sample calculations are given for high temperature air and carbon dioxide and are compared to calculations made with previously developed programs.

  7. Quenching of Particle-Gas Combustible Mixtures Using Electric Particulate Suspension (EPS) and Dispersion Methods

    NASA Technical Reports Server (NTRS)

    Colver, Gerald M.; Goroshin, Samuel; Lee, John H. S.

    2001-01-01

    A cooperative study is being carried out between Iowa State University and McGill University. The new study concerns wall and particle quenching effects in particle-gas mixtures. The primary objective is to measure and interpret flame quenching distances, flammability limits, and burning velocities in particulate suspensions. A secondary objective is to measure particle slip velocities and particle velocity distribution as these influence flame propagation. Two suspension techniques will be utilized and compared: (1) electric particle suspension/EPS; and (2) flow dispersion. Microgravity tests will permit testing of larger particles and higher and more uniform dust concentrations than is possible in normal gravity.

  8. Adsorption of a binary gas mixture which laterally interacts on a random heterogeneous surface

    SciTech Connect

    Ritter, J.A.

    1992-10-01

    Analytical expressions for the adsorption of a binary gas mixture which laterally interacts on a heterogeneous surface are developed. The lateral interactions are of the Bragg-Williams type and the surface heterogeneity is modeled via a random distribution of sites described by a uniform distribution of Henry`s Law constants. The parametric study shows that complex phase behavior can be predicted, including azeotropes and sigmoidal shaped X-Y diagrams. Also, this model may be useful for modeling and designing adsorption processes as it requires few iterations to simultaneously solve the implicit and coupled algebraic expressions.

  9. Adsorption of a binary gas mixture which laterally interacts on a random heterogeneous surface

    SciTech Connect

    Ritter, J.A.

    1992-01-01

    Analytical expressions for the adsorption of a binary gas mixture which laterally interacts on a heterogeneous surface are developed. The lateral interactions are of the Bragg-Williams type and the surface heterogeneity is modeled via a random distribution of sites described by a uniform distribution of Henry's Law constants. The parametric study shows that complex phase behavior can be predicted, including azeotropes and sigmoidal shaped X-Y diagrams. Also, this model may be useful for modeling and designing adsorption processes as it requires few iterations to simultaneously solve the implicit and coupled algebraic expressions.

  10. Effects of temperature on the carbonation of flue gas desulphurization gypsum using a CO2/N2 gas mixture.

    PubMed

    Lee, Myung Gyu; Ryu, Kyung Won; Chae, Soo Chun; Jang, Young Nam

    2015-01-01

    The carbonation of flue gas desulphurization (FGD) gypsum using a CO2/N2 gas mixture was investigated to study the feasibility of using the flue gas directly in the gypsum carbonation. The effect of the reaction temperature on the carbonation reaction and the carbonation conversion efficiency of the samples were considered. In this study, the carbonation conversion efficiency was calculated using a new method for decreasing the error range from a sample containing unreacted gypsum. The carbonation reaction at 40°C was nearly twice as fast as the reaction at room temperature. In addition, the carbonation conversion efficiency at 40°C (96%) was nearly the same as that at room temperature. However, the efficiency decreased significantly with temperature, especially above 60°C. It can, therefore, be concluded that the direct use of flue gas in gypsum carbonation is most feasible at 40°C. The temperature of carbonation strongly affected the CaCO3 polymorphs and the morphological characteristics. Calcite with various shapes was the dominant (40-90%) phase at all temperatures. At temperatures below 40°C, spherical-shaped vaterite was pronounced, while needle-flower-shaped aragonite was dominant at temperatures above 80°C.

  11. Investigation of mass dependence effects for the accurate determination of molybdenum isotope amount ratios by MC-ICP-MS using synthetic isotope mixtures.

    PubMed

    Malinovsky, Dmitry; Dunn, Philip J H; Petrov, Panayot; Goenaga-Infante, Heidi

    2015-01-01

    Methodology for absolute Mo isotope amount ratio measurements by multicollector inductively coupled plasma-mass spectrometry (MC-ICP-MS) using calibration with synthetic isotope mixtures (SIMs) is presented. For the first time, synthetic isotope mixtures prepared from seven commercially available isotopically enriched molybdenum metal powders ((92)Mo, (94)Mo, (95)Mo, (96)Mo, (97)Mo, (98)Mo, and (100)Mo) are used to investigate whether instrumental mass discrimination of Mo isotopes in MC-ICP-MS is consistent with mass-dependent isotope distribution. The parent materials were dissolved and mixed as solutions to obtain mixtures with accurately known isotope amount ratios. The level of elemental impurities in the isotopically enriched molybdenum metal powders was quantified by ICP-MS by using both high-resolution and reaction cell instruments to completely resolve spectral interferences. The Mo isotope amount ratio values with expanded uncertainty (k = 2), determined by MC-ICP-MS for a high-purity Mo rod from Johnson Matthey, were as follows: (92)Mo/(95)Mo = 0.9235(9), (94)Mo/(95)Mo = 0.5785(8), (96)Mo/(95)Mo = 1.0503(9), (97)Mo/(95)Mo = 0.6033(6), (98)Mo/(95)Mo = 1.5291(20), and (100)Mo/(95)Mo = 0.6130(7). A full uncertainty budget for the measurements is presented which shows that the largest contribution to the uncertainty budget comes from correction for elemental impurities (∼51%), followed by the contribution from weighing operations (∼26 %). The atomic weight of molybdenum was calculated to be 95.947(2); the uncertainty in parentheses is expanded uncertainty with the coverage factor of 2. A particular advantage of the developed method is that calibration factors for all six Mo isotope amount ratios, involving the (95)Mo isotope, were experimentally determined. This allows avoiding any assumption on mass-dependent isotope fractions in MC-ICP-MS, inherent to the method of double spike previously used for Mo isotope amount ratio

  12. Transport Properties of He-N{sub 2} Binary Gas Mixtures for CBC Space Applications

    SciTech Connect

    Tournier, Jean-Michel P.; El-Genk, Mohamed S.

    2008-01-21

    In order to reduce the size and mass of the single-shaft turbo-machines, with little impact on the size of the heat transfer components in the CBC loop, He-Xe binary mixture with a molecular weight of 40 g/mole has been the working fluid of choice in space nuclear reactor power systems with Close Brayton Cycle (CBC) for energy conversion. This working fluid is also a suitable coolant for the fission reactors heat source designed with fast neutron energy spectra. For space nuclear reactors with thermal neutron energy spectra, however, the high capture neutron cross-section of Xe will reduce the beginning-of-life excess reactivity of the reactor, decreasing its effective operation lifetime. In addition, the neutron activation of Xe in the reactor will introduce a radioactivity source term in the CBC loop. Alternative working fluids with no activation concerns and comparable performance are N{sub 2} and the binary mixtures of He-N{sub 2}. This paper calculates the transport properties of these working fluids and compares their values to those of noble gas binary mixtures at the temperatures and pressures expected in CBC space reactor power system applications. Also investigated is the impact of using these working fluids on the pressure losses, heat transfer coefficient, and the aerodynamic loading of the blades in the CBC turbo-machines.

  13. 10 CFR 504.7 - Prohibition against excessive use of petroleum or natural gas in mixtures-electing powerplants.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Prohibition against excessive use of petroleum or natural...) ALTERNATE FUELS EXISTING POWERPLANTS § 504.7 Prohibition against excessive use of petroleum or natural gas... technically and financially feasible for a unit to use a mixture of petroleum or natural gas and an...

  14. 10 CFR 504.7 - Prohibition against excessive use of petroleum or natural gas in mixtures-electing powerplants.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 4 2011-01-01 2011-01-01 false Prohibition against excessive use of petroleum or natural...) ALTERNATE FUELS EXISTING POWERPLANTS § 504.7 Prohibition against excessive use of petroleum or natural gas... technically and financially feasible for a unit to use a mixture of petroleum or natural gas and an...

  15. 10 CFR 504.7 - Prohibition against excessive use of petroleum or natural gas in mixtures-electing powerplants.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 4 2012-01-01 2012-01-01 false Prohibition against excessive use of petroleum or natural...) ALTERNATE FUELS EXISTING POWERPLANTS § 504.7 Prohibition against excessive use of petroleum or natural gas... technically and financially feasible for a unit to use a mixture of petroleum or natural gas and an...

  16. 10 CFR 504.7 - Prohibition against excessive use of petroleum or natural gas in mixtures-electing powerplants.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 4 2014-01-01 2014-01-01 false Prohibition against excessive use of petroleum or natural...) ALTERNATE FUELS EXISTING POWERPLANTS § 504.7 Prohibition against excessive use of petroleum or natural gas... technically and financially feasible for a unit to use a mixture of petroleum or natural gas and an...

  17. 10 CFR 504.7 - Prohibition against excessive use of petroleum or natural gas in mixtures-electing powerplants.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 4 2013-01-01 2013-01-01 false Prohibition against excessive use of petroleum or natural...) ALTERNATE FUELS EXISTING POWERPLANTS § 504.7 Prohibition against excessive use of petroleum or natural gas... technically and financially feasible for a unit to use a mixture of petroleum or natural gas and an...

  18. Novel simulated moving-bed adsorber for the fractionation of gas mixtures.

    PubMed

    Rao, D P; Sivakumar, S V; Mandal, Susmita; Kota, Sridevi; Ramaprasad, B S G

    2005-03-25

    The separation of propylene-propane mixture is an energy intensive operation commercially practiced using cryogenic distillation. The separation by pressure swing adsorption has been studied as an alternative. A fixed-bed pressure swing adsorption yields the heavy component as a pure product. The product recovery and the productivity are not high. In a moving-bed process, because of the counter-current solid-gas contact, the separation achieved is similar to that of the fractionation by distillation. Although the moving-bed operation offers the upper limit for the performance of a cyclic adsorptive process, due to mechanical complexities in the handling of solids the 'simulated' moving-bed is preferred. By moving the inlet and outlet ports of streams located along the length of the bed, a moving-bed process can be realized in a fixed bed. We describe here a 'moving-port' system which permits injection or withdrawal of the fluid along the axial direction in a fixed bed. A fixed bed embedded with the moving-port systems emulates a simulated moving-bed adsorber. The proposed adsorber can fractionate a binary gas mixture into two product streams with high purities. It is similar to the Sorbex process of UOP but does not have the eluent as an additional separating agent. A parametric study indicates that high purity products and a higher productivity by an order of magnitude can be achieved with simulated moving-beds compared to the fixed beds.

  19. Gas energy meter for inferential determination of thermophysical properties of a gas mixture at multiple states of the gas

    DOEpatents

    Morrow, Thomas B.; Kelner, Eric; Owen, Thomas E.

    2008-07-08

    A gas energy meter that acquires the data and performs the processing for an inferential determination of one or more gas properties, such as heating value, molecular weight, or density. The meter has a sensor module that acquires temperature, pressure, CO2, and speed of sound data. Data is acquired at two different states of the gas, which eliminates the need to determine the concentration of nitrogen in the gas. A processing module receives this data and uses it to perform a "two-state" inferential algorithm.

  20. Cs vapor microcells with Ne-He buffer gas mixture for high operation-temperature miniature atomic clocks.

    PubMed

    Kroemer, E; Abdel Hafiz, M; Maurice, V; Fouilland, B; Gorecki, C; Boudot, R

    2015-07-13

    We report on the characterization of Cs vapor microfabricated cells filled with a Ne-He buffer gas mixture using coherent population trapping (CPT) spectroscopy. The temperature dependence of the Cs clock frequency is found to be canceled at the first order around a so-called inversion temperature higher than 80°C whose value depends on the buffer gas partial pressure ratio. This buffer gas mixture could be well-adapted for the development of miniature atomic clocks devoted to be used in specific applications such as defense and avionic systems with high operating temperature environment (typically higher than 85°C). This solution suggests an alternative to buffer gas mixtures generally used in optically-pumped vapor cell atomic clocks.

  1. Cs vapor microcells with Ne-He buffer gas mixture for high operation-temperature miniature atomic clocks.

    PubMed

    Kroemer, E; Abdel Hafiz, M; Maurice, V; Fouilland, B; Gorecki, C; Boudot, R

    2015-07-13

    We report on the characterization of Cs vapor microfabricated cells filled with a Ne-He buffer gas mixture using coherent population trapping (CPT) spectroscopy. The temperature dependence of the Cs clock frequency is found to be canceled at the first order around a so-called inversion temperature higher than 80°C whose value depends on the buffer gas partial pressure ratio. This buffer gas mixture could be well-adapted for the development of miniature atomic clocks devoted to be used in specific applications such as defense and avionic systems with high operating temperature environment (typically higher than 85°C). This solution suggests an alternative to buffer gas mixtures generally used in optically-pumped vapor cell atomic clocks. PMID:26191895

  2. Separation Analysis in a High-Speed Rotating Cylinder for a Binary Gas Mixture

    NASA Astrophysics Data System (ADS)

    Pradhan, Sahadev; Kumaran, Viswanathan

    2015-11-01

    The solutions of the species balance equations linked with the generalized Onsager model for the secondary gas flow in a high-speed rotating cylinder are compared with the direct simulation Monte Carlo (DSMC) simulations for a binary gas mixture. The concentration fields are obtained three different types of driving mechanism. These are: (a) wall thermal forcing, (b) inflow/outflow of gas along the axis, and (c) momentum source/sink inside the flow domain, for the stratification parameter (A) in the range (0.707- 3.535), and Reynolds number (Re) in the range (102 - 106 with aspect ratio (length / diameter) = 2, 4, 8. Two different types of cases have been considered, (a) no mass difference (ɛa = (2 Δm/(m1 + m2)) = 0), and (b) with mass difference (ɛa = 0.2 and 0.5) while calculating the secondary flow field in the analytical solution. Here, the stratification prameter A = √((mavΩ2 R2)/(2 kB T)), and the Reynolds number Re = ρw Ω R2)/ μ, where m is the molecular mass, Ω and R are the angular velocity and radius of the cylinder, ρw is the wall density, μ is the gas viscosity and T is the gas temperature. The comparison between numerical and analytical solution reveals that the boundary conditions in the numerical simulations and analytical model have to be matched with care. The commonly used ``diffuse reflection'' boundary conditions at the solid walls in DSMC simulations result in a non-zero slip velocity as well as a ``temperature slip'' (gas temperature at the wall is different from wall temperature).

  3. 2D fluid simulations of discharges at atmospheric pressure in reactive gas mixtures

    NASA Astrophysics Data System (ADS)

    Bourdon, Anne

    2015-09-01

    Since a few years, low-temperature atmospheric pressure discharges have received a considerable interest as they efficiently produce many reactive chemical species at a low energy cost. This potential is of great interest for a wide range of applications as plasma assisted combustion or biomedical applications. Then, in current simulations of atmospheric pressure discharges, there is the need to take into account detailed kinetic schemes. It is interesting to note that in some conditions, the kinetics of the discharge may play a role on the discharge dynamics itself. To illustrate this, we consider the case of the propagation of He-N2 discharges in long capillary tubes, studied for the development of medical devices for endoscopic applications. Simulation results put forward that the discharge dynamics and structure depend on the amount of N2 in the He-N2 mixture. In particular, as the amount of N2 admixture increases, the discharge propagation velocity in the tube increases, reaches a maximum for about 0 . 1 % of N2 and then decreases, in agreement with experiments. For applications as plasma assisted combustion with nanosecond repetitively pulsed discharges, there is the need to handle the very different timescales of the nanosecond discharge with the much longer (micro to millisecond) timescales of combustion processes. This is challenging from a computational point of view. It is also important to better understand the coupling of the plasma induced chemistry and the gas heating. To illustrate this, we present the simulation of the flame ignition in lean mixtures by a nanosecond pulsed discharge between two point electrodes. In particular, among the different discharge regimes of nanosecond repetitively pulsed discharges, a ``spark'' regime has been put forward in the experiments, with an ultra-fast local heating of the gas. For other discharge regimes, the gas heating is much weaker. We have simulated the nanosecond spark regime and have observed shock waves

  4. Reactive ion-etching-induced damage in silicon using SF/sub 6/ gas mixtures

    SciTech Connect

    Arora, B.M.; Pinto, R.; Sachidananda Babu, R.

    1987-07-01

    Damage introduced in silicon during reactive-ion etching (RIE) in SI/sub 6/ gas containing 10 Vol % of H/sub 2/, He, N/sub 2/, O/sub 2/, or Ar has been investigated using Schottky barrier measurements and Rutherford backscattering. RIE was performed at 0.1 Watt cm/sup -2/ power density with the radio frequancy (rf) cathode covered with a quartz plate. The annealing effect on damage was studied at various temperatures up to 800 /sup 0/C in dry N/sub 2/. The results indicate that the damage has two components namely, a shallow near-surface region with lattice damage and a deep layer containing discrete defect centers which act as donors. The extent of the deep damage layer is the net balance between two competing processes: (a) the etch rate, and (b) the rate of damage migration into silicon. However, the damage has been found to reach a saturation level after RIE for 1 min in all the gas mixtures studied. The results also suggest that RIE in SF/sub 6/+10% H/sub 2/ gas mixture causes a deep damage layer which could, however, be annealed at 150 /sup 0/C aided significantly by the passivation of defect centers by hydrogen permeated during RIE. On the other hand, the damage induced in SF/sub 6/+10% Ar-etched samples has been found to anneal at 800 /sup 0/C indicating there by a higher level of lattice damage or amorphization of the near-surface layer of silicon. Therefore, the mass of the bombarding ion significantly affects the nature of the damage layers.

  5. Communication: Simple and accurate uniform electron gas correlation energy for the full range of densities

    NASA Astrophysics Data System (ADS)

    Chachiyo, Teepanis

    2016-07-01

    A simple correlation energy functional for the uniform electron gas is derived based on the second-order Moller-Plesset perturbation theory. It can reproduce the known correlation functional in the high-density limit, while in the mid-density range maintaining a good agreement with the near-exact correlation energy of the uniform electron gas to within 2 × 10-3 hartree. The correlation energy is a function of a density parameter rs and is of the form a * ln ( 1 + /b r s + /b rs 2 ) . The constants "a" and "b" are derived from the known correlation functional in the high-density limit. Comparisons to the Ceperley-Alder's near-exact Quantum Monte Carlo results and the Vosko-Wilk-Nusair correlation functional are also reported.

  6. Describing and compensating gas transport dynamics for accurate instantaneous emission measurement

    NASA Astrophysics Data System (ADS)

    Weilenmann, Martin; Soltic, Patrik; Ajtay, Delia

    Instantaneous emission measurements on chassis dynamometers and engine test benches are becoming increasingly usual for car-makers and for environmental emission factor measurement and calculation, since much more information about the formation conditions can be extracted than from the regulated bag measurements (integral values). The common exhaust gas analysers for the "regulated pollutants" (carbon monoxide, total hydrocarbons, nitrogen oxide, carbon dioxide) allow measurement at a rate of one to ten samples per second. This gives the impression of having after-the-catalyst emission information with that chronological precision. It has been shown in recent years, however, that beside the reaction time of the analysers, the dynamics of gas transport in both the exhaust system of the car and the measurement system last significantly longer than 1 s. This paper focuses on the compensation of all these dynamics convoluting the emission signals. Most analysers show linear and time-invariant reaction dynamics. Transport dynamics can basically be split into two phenomena: a pure time delay accounting for the transport of the gas downstream and a dynamic signal deformation since the gas is mixed by turbulence along the way. This causes emission peaks to occur which are smaller in height and longer in time at the sensors than they are after the catalyst. These dynamics can be modelled using differential equations. Both mixing dynamics and time delay are constant for modelling a raw gas analyser system, since the flow in that system is constant. In the exhaust system of the car, however, the parameters depend on the exhaust volume flow. For gasoline cars, the variation in overall transport time may be more than 6 s. It is shown in this paper how all these processes can be described by invertible mathematical models with the focus on the more complex case of the car's exhaust system. Inversion means that the sharp emission signal at the catalyst out location can be

  7. Analysis of an activated-carbon sorption compressor operating with gas mixtures

    NASA Astrophysics Data System (ADS)

    Tzabar, N.; Grossman, G.

    2012-10-01

    Sorption compressors elevate the pressure of gases and can provide a more or less continuous mass flow. Unlike mechanical compressors, sorption compressors have no moving parts, and therefore do not emit vibrations and are highly reliable. There exist different sorption compressors for different operating conditions and various gases. However, there are no published reports of sorption compressors for mixed gases. Such compressors, among other applications, may drive mixed-refrigerant Joule-Thomson cryocoolers. The adsorption of mixed gases is usually investigated under steady conditions, mainly for storage and separation processes. However, the sorption process in a compressor goes through varying states and mass changes; therefore, it differs from the common mixed gases adsorption applications. In this research a numerical analysis for mixed gas sorption compressors is developed, based on pure gas adsorption characteristics and the ideal adsorbed solution theory. Two pure gas adsorption models are used for calculating the conditions of the adsorbed phase: Langmuir and Sips; and the Peng-Robinson equation of state is used to calculate the conditions of the vapor phase. Two mixtures are investigated; nitrogen-methane and nitrogen-ethane. Finally, the analysis is verified against experimental results. This research provides initiatory observation for mixed gases sorption compressor in which each component is differently adsorbed.

  8. On-farm euthanasia of broiler chickens: effects of different gas mixtures on behavior and brain activity.

    PubMed

    Gerritzen, M A; Lambooij, B; Reimert, H; Stegeman, A; Spruijt, B

    2004-08-01

    The purpose of this study was to investigate the suitability of gas mixtures for euthanasia of groups of broilers in their housing by increasing the percentage of CO2. The suitability was assessed by the level of discomfort before loss of consciousness, and the killing rate. The gas mixtures injected into the housing were 1) 100% CO2, 2) 50% N2 + 50% CO2, and 3) 30% O2 + 40% CO2 + 30% N2, followed by 100% CO2. At 2 and 6 wk of age, groups of 20 broiler chickens per trial were exposed to increasing CO2 percentages due to the injection of these gas mixtures. Behavior and killing rate were examined. At the same time, 2 broilers per trial equipped with brain electrodes were observed for behavior and brain activity. Ten percent of the 2-wk-old broilers survived the increasing CO2 percentage due to the injection of 30% O2 + 40% CO2 + 30% N2 mixture, therefore this mixture was excluded for further testing at 6 wk of age. At 6 wk of age, 30% of the broilers survived in the 50% N2 + 50% CO2 group. The highest level of CO2 in the breathing air (42%) was reached by the injection of the 100% CO2 mixture, vs. 25% for the other 2 mixtures. In all 3 gas mixtures, head shaking, gasping, and convulsions were observed before loss of posture. Loss of posture and suppression of electrical activity of the brain (n = 7) occurred almost simultaneously. The results of this experiment indicate that euthanasia of groups of 2- and 6-wk-old broilers by gradually increasing the percentage of CO2 in the breathing air up to 40% is possible. PMID:15339003

  9. Laser induced avalanche ionization in gases or gas mixtures with resonantly enhanced multiphoton ionization or femtosecond laser pulse pre-ionization

    SciTech Connect

    Shneider, Mikhail N.; Miles, Richard B.

    2012-08-15

    The paper discusses the requirements for avalanche ionization in gas or gas mixtures initiated by REMPI or femtosecond-laser pre-ionization. Numerical examples of dependencies on partial composition for Ar:Xe gas mixture with REMPI of argon and subsequent classic avalanche ionization of Xe are presented.

  10. Effect Of Gas Mixture Composition On Tar Removal Process In A Pulsed Corona Discharge Reactor

    NASA Astrophysics Data System (ADS)

    Filimonova E.; Naidis, G.

    2010-07-01

    The simulation of naphthalene (C10H8) removal from several gas mixtures (pure nitrogen, mixtures containing N2 with CO2, CO, H2, H2O, and biogas - the product of biomass gasification), has been investigated. The modeling is based on the experimental data obtained in the reactor with a pulsed positive corona discharge. The problem of simulation of the cleaning process includes description of two stages. The first, fast stage is generation of primary active species during streamer propagation. The second, slow stage is the chain of chemical transformations triggered by these species. The input parameters for the modeling of the second stage are G-values for generation of primary active species, obtained under consideration of streamer dynamics. Simulation of the second stage of the removal process takes into account the processes of chemical kinetics and diffusion outside and inside of streamer traces during multi-pulsed treatment. Besides neutral active species, streamer discharges produce electrons and ions. Primary positive ions (N2+, CO+, CO2+, H2+, H2O+) in a chain of fast ion-molecule reactions transform into more stable positive ions. The ions recombine with electrons. Both ion-molecule reactions and electron-ion recombination process are additional (to dissociation of gas molecules by electron impact in the streamer head) sources of neutral active species. The relative contribution of these sources to the G-values for H, OH and O is rather large. In our modeling two approaches have been used. At the first approach the contribution of ion-molecule reactions is estimated approximately assuming that the dominating stable ion is N4+ (in pure N2 and its mixtures with H2) or CO2+ (in mixtures including CO2). Other way is the calculations with kinetic scheme including the molecular ions, aquated ions such as H3O(H2O)m+, NO2(H2O)-, NO2(H2O)+ and other. The comparison of results of two approaches is presented. Only full kinetic scheme allowed describing the

  11. Gas-phase purification enables accurate, large-scale, multiplexed proteome quantification with isobaric tagging

    PubMed Central

    Wenger, Craig D; Lee, M Violet; Hebert, Alexander S; McAlister, Graeme C; Phanstiel, Douglas H; Westphall, Michael S; Coon, Joshua J

    2011-01-01

    We describe a mass spectrometry method, QuantMode, which improves the accuracy of isobaric tag–based quantification by alleviating the pervasive problem of precursor interference—co-isolation of impurities—through gas-phase purification. QuantMode analysis of a yeast sample ‘contaminated’ with interfering human peptides showed substantially improved quantitative accuracy compared to a standard scan, with a small loss of spectral identifications. This technique will allow large-scale, multiplexed quantitative proteomics analyses using isobaric tagging. PMID:21963608

  12. Fast and accurate numerical method for predicting gas chromatography retention time.

    PubMed

    Claumann, Carlos Alberto; Wüst Zibetti, André; Bolzan, Ariovaldo; Machado, Ricardo A F; Pinto, Leonel Teixeira

    2015-08-01

    Predictive modeling for gas chromatography compound retention depends on the retention factor (ki) and on the flow of the mobile phase. Thus, different approaches for determining an analyte ki in column chromatography have been developed. The main one is based on the thermodynamic properties of the component and on the characteristics of the stationary phase. These models can be used to estimate the parameters and to optimize the programming of temperatures, in gas chromatography, for the separation of compounds. Different authors have proposed the use of numerical methods for solving these models, but these methods demand greater computational time. Hence, a new method for solving the predictive modeling of analyte retention time is presented. This algorithm is an alternative to traditional methods because it transforms its attainments into root determination problems within defined intervals. The proposed approach allows for tr calculation, with accuracy determined by the user of the methods, and significant reductions in computational time; it can also be used to evaluate the performance of other prediction methods.

  13. Methodology for Predicting Flammable Gas Mixtures in Double Contained Receiver Tanks [SEC 1 THRU SEC 3

    SciTech Connect

    HEDENGREN, D.C.

    2000-01-31

    This methodology document provides an estimate of the maximum concentrations of flammable gases (ammonia, hydrogen, and methane) which could exist in the vapor space of a double-contained receiver tank (DCRT) from the simultaneous saltwell pumping of one or more single-shell tanks (SSTs). This document expands Calculation Note 118 (Hedengren et a1 1997) and removes some of the conservatism from it, especially in vapor phase ammonia predictions. The methodologies of Calculation Note 118 (Hedengren et a1 1997) are essentially identical for predicting flammable gas mixtures in DCRTs from saltwell pumping for low DCRT ventilation rates, 1e, < 1 cfm. The hydrogen generation model has also been updated in the methodology of this document.

  14. The equivalent electrical permittivity of gas-solid mixtures at intermediate solid volume fractions.

    SciTech Connect

    Torczynski, John Robert; Ceccio, Steven Louis; Tortora, Paul Richard

    2005-07-01

    Several mixture models are evaluated for their suitability in predicting the equivalent permittivity of dielectric particles in a dielectric medium for intermediate solid volume fractions (0.4 to 0.6). Predictions of the Maxwell, Rayleigh, Bottcher and Bruggeman models are compared to computational simulations of several arrangements of solid particles in a gas and to the experimentally determined permittivity of a static particle bed. The experiment uses spherical glass beads in air, so air and glass permittivity values (1 and 7, respectively) are used with all of the models and simulations. The experimental system used to measure the permittivity of the static particle bed and its calibration are described. The Rayleigh model is found to be suitable for predicting permittivity over the entire range of solid volume fractions (0-0.6).

  15. An Improved Analytical Approach to Determine the Explosive Effects of Flammable Gas-Air Mixtures

    SciTech Connect

    Yang, J M

    2005-11-10

    The U.S. Department of Energy (DOE) Complex includes many sites and laboratories that store quantities of low-level, solid nuclear waste in drums and other types of shipping containers. The drums may be stored for long periods of time prior to being transported and final dispositioning. Based on the radioactivity (e.g., Pu{sup 239} equivalent), chemical nature (e.g. volatile organic compounds) and other characteristics of the stored waste, flammable gases may evolve. Documented safety analyses (DSAs) for storage of these drums must address storage and safety management issues to protect workers, the general public, and the environment. This paper discusses an improved analytical method for determining the explosion effects flammable gas-air mixtures as well as the subsequent accident phenomenology.

  16. Spontaneous symmetry breaking and inversion-line spectroscopy in gas mixtures

    NASA Astrophysics Data System (ADS)

    Presilla, Carlo; Jona-Lasinio, Giovanni

    2015-02-01

    According to quantum mechanics, chiral molecules, that is, molecules that rotate the polarization of light, should not exist. The simplest molecules which can be chiral have four or more atoms with two arrangements of minimal potential energy that are equivalent up to a parity operation. Chiral molecules correspond to states localized in one potential energy minimum and can not be stationary states of the Schrödinger equation. A possible solution of the paradox can be founded on the idea of spontaneous symmetry breaking. This idea was behind work we did previously involving a localization phase transition: at low pressure, the molecules are delocalized between the two minima of the potential energy while at higher pressure they become localized in one minimum due to the intermolecular dipole-dipole interactions. Evidence for such a transition is provided by measurements of the inversion spectrum of ammonia and deuterated ammonia at different pressures. A previously proposed model gives a satisfactory account of the empirical results without free parameters. In this paper, we extend this model to gas mixtures. We find that also in these systems a phase transition takes place at a critical pressure which depends on the composition of the mixture. Moreover, we derive formulas giving the dependence of the inversion frequencies on the pressure. These predictions are susceptible to experimental test.

  17. Measurement of activity coefficients of mixtures by head-space gas chromatography: general procedure.

    PubMed

    Luis, Patricia; Wouters, Christine; Van der Bruggen, Bart; Sandler, Stanley I

    2013-08-01

    Head-space gas chromatography (HS-GC) is an applicable method to perform vapor-liquid equilibrium measurements and determine activity coefficients. However, the reproducibility of the data may be conditioned by the experimental procedure concerning to the automated pressure-balanced system. The study developed in this work shows that a minimum volume of liquid in the vial is necessary to ensure the reliability of the activity coefficients since it may become a parameter that influences the magnitude of the peak areas: the helium introduced during the pressurization step may produce significant variations of the results when too small volume of liquid is selected. The minimum volume required should thus be evaluated prior to obtain experimentally the concentration in the vapor phase and the activity coefficients. In this work, the mixture acetonitrile-toluene is taken as example, requiring a sample volume of more than 5mL (about more than 25% of the vial volume). The vapor-liquid equilibrium and activity coefficients of mixtures at different concentrations (0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 molar fraction) and four temperatures (35, 45, 55 and 70°C) have been determined. Relative standard deviations (RSD) lower than 5% have been obtained, indicating the good reproducibility of the method when a sample volume larger than 5mL is used. Finally, a general procedure to measure activity coefficients by means of pressure-balanced head-space gas chromatography is proposed. PMID:23809803

  18. Synthesis of formamide and isocyanic acid after ion irradiation of frozen gas mixtures

    NASA Astrophysics Data System (ADS)

    Kaňuchová, Z.; Urso, R. G.; Baratta, G. A.; Brucato, J. R.; Palumbo, M. E.; Strazzulla, G.

    2016-01-01

    Context. Formamide (NH2HCO) and isocyanic acid (HNCO) have been observed as gaseous species in several astronomical environments such as cometary comae and pre- and proto-stellar objects. A debate is open on the formation route of those molecules, in particular if they are formed by chemical reactions in the gas phase and/or on grains. In this latter case it is relevant to understand if the formation occurs through surface reactions or is induced by energetic processing. Aims: We present arguments that support the formation of formamide in the solid phase by cosmic-ion-induced energetic processing of ices present as mantles of interstellar grains and on comets. Formamides, along with other molecules, are expelled in the gas phase when the physical parameters are appropriate to induce the desorption of ices. Methods: We have performed several laboratory experiments in which ice mixtures (H2O:CH4:N2, H2O:CH4:NH3, and CH3OH:N2) were bombarded with energetic (30-200 keV) ions (H+ or He+). FTIR spectroscopy was performed before, during, and after ion bombardment. In particular, the formation of HNCO and NH2HCO was measured quantiatively. Results: Energetic processing of ice can quantitatively reproduce the amount of NH2HCO observed in cometary comae and in many circumstellar regions. HNCO is also formed, but additional formation mechanisms are requested to quantitatively account for the astronomical observations. Conclusions: We suggest that energetic processing of ices in the pre- and proto-stellar regions and in comets is the main mechanism to produce formamide, which, once it is released in the gas phase because of desorption of ices, is observed in the gas phase in these astrophysical environments.

  19. Obtaining the cumulative k-distribution of a gas mixture from those of its components. [radiative transfer in stratosphere

    NASA Technical Reports Server (NTRS)

    Gerstell, M. F.

    1993-01-01

    A review of the convolution theorem for obtaining the cumulative k-distribution of a gas mixture proven in Goody et al. (1989) and a discussion of its application to natural spectra are presented. Computational optimizations for use in analyzing high-altitude gas mixtures are introduced. Comparisons of the results of the optimizations, and criteria for deciding what altitudes are 'high' in this context are given. A few relevant features of the testing support software are examined. Some spectrally integrated results, and the circumstances the might permit substituting the method of principal absorbers are examined.

  20. Fast gas heating in N2/O2 mixtures under nanosecond surface dielectric barrier discharge: the effects of gas pressure and composition.

    PubMed

    Nudnova, M M; Kindysheva, S V; Aleksandrov, N L; Starikovskii, A Yu

    2015-08-13

    The fractional electron power quickly transferred to heat in non-equilibrium plasmas was studied experimentally and theoretically in N(2)/O(2) mixtures subjected to high electric fields. Measurements were performed in and after a nanosecond surface dielectric barrier discharge at various (300-750 Torr) gas pressures and (50-100%) N(2) percentages. Observations showed that the efficiency of fast gas heating is almost independent of pressure and becomes more profound when the fraction of O(2) in N(2)/O(2) mixtures increases. The processes that contribute towards the fast transfer of electron energy to thermal energy were numerically simulated under the conditions considered. Calculations were compared with measurements and the main channels of fast gas heating were analysed at the gas pressures, compositions and electric fields under study. It was shown that efficient fast gas heating in the mixtures with high fraction of O(2) is due to a notable contribution of heat release during quenching of electronically excited N(2) states in collisions with O(2) molecules and to ion-ion recombination. The effect of hydrocarbon addition to air on fast gas heating was numerically estimated. It was concluded that the fractional electron power transferred to heat in air, as a first approximation, could be used to estimate this effect in lean and stoichiometric hydrocarbon-air mixtures.

  1. Fast gas heating in N2/O2 mixtures under nanosecond surface dielectric barrier discharge: the effects of gas pressure and composition

    PubMed Central

    Nudnova, M. M; Kindysheva, S. V; Aleksandrov, N. L; Starikovskii, A. Yu

    2015-01-01

    The fractional electron power quickly transferred to heat in non-equilibrium plasmas was studied experimentally and theoretically in N2/O2 mixtures subjected to high electric fields. Measurements were performed in and after a nanosecond surface dielectric barrier discharge at various (300–750 Torr) gas pressures and (50–100%) N2 percentages. Observations showed that the efficiency of fast gas heating is almost independent of pressure and becomes more profound when the fraction of O2 in N2/O2 mixtures increases. The processes that contribute towards the fast transfer of electron energy to thermal energy were numerically simulated under the conditions considered. Calculations were compared with measurements and the main channels of fast gas heating were analysed at the gas pressures, compositions and electric fields under study. It was shown that efficient fast gas heating in the mixtures with high fraction of O2 is due to a notable contribution of heat release during quenching of electronically excited N2 states in collisions with O2 molecules and to ion–ion recombination. The effect of hydrocarbon addition to air on fast gas heating was numerically estimated. It was concluded that the fractional electron power transferred to heat in air, as a first approximation, could be used to estimate this effect in lean and stoichiometric hydrocarbon–air mixtures. PMID:26170431

  2. Supersonic Flow of Chemically Reacting Gas-Particle Mixtures. Volume 2: RAMP - A Computer Code for Analysis of Chemically Reacting Gas-Particle Flows

    NASA Technical Reports Server (NTRS)

    Penny, M. M.; Smith, S. D.; Anderson, P. G.; Sulyma, P. R.; Pearson, M. L.

    1976-01-01

    A computer program written in conjunction with the numerical solution of the flow of chemically reacting gas-particle mixtures was documented. The solution to the set of governing equations was obtained by utilizing the method of characteristics. The equations cast in characteristic form were shown to be formally the same for ideal, frozen, chemical equilibrium and chemical non-equilibrium reacting gas mixtures. The characteristic directions for the gas-particle system are found to be the conventional gas Mach lines, the gas streamlines and the particle streamlines. The basic mesh construction for the flow solution is along streamlines and normals to the streamlines for axisymmetric or two-dimensional flow. The analysis gives detailed information of the supersonic flow and provides for a continuous solution of the nozzle and exhaust plume flow fields. Boundary conditions for the flow solution are either the nozzle wall or the exhaust plume boundary.

  3. Accurate Exchange-Correlation Energies for the Warm Dense Electron Gas.

    PubMed

    Malone, Fionn D; Blunt, N S; Brown, Ethan W; Lee, D K K; Spencer, J S; Foulkes, W M C; Shepherd, James J

    2016-09-01

    The density matrix quantum Monte Carlo (DMQMC) method is used to sample exact-on-average N-body density matrices for uniform electron gas systems of up to 10^{124} matrix elements via a stochastic solution of the Bloch equation. The results of these calculations resolve a current debate over the accuracy of the data used to parametrize finite-temperature density functionals. Exchange-correlation energies calculated using the real-space restricted path-integral formalism and the k-space configuration path-integral formalism disagree by up to ∼10% at certain reduced temperatures T/T_{F}≤0.5 and densities r_{s}≤1. Our calculations confirm the accuracy of the configuration path-integral Monte Carlo results available at high density and bridge the gap to lower densities, providing trustworthy data in the regime typical of planetary interiors and solids subject to laser irradiation. We demonstrate that the DMQMC method can calculate free energies directly and present exact free energies for T/T_{F}≥1 and r_{s}≤2.

  4. Accurate Exchange-Correlation Energies for the Warm Dense Electron Gas

    NASA Astrophysics Data System (ADS)

    Malone, Fionn D.; Blunt, N. S.; Brown, Ethan W.; Lee, D. K. K.; Spencer, J. S.; Foulkes, W. M. C.; Shepherd, James J.

    2016-09-01

    The density matrix quantum Monte Carlo (DMQMC) method is used to sample exact-on-average N -body density matrices for uniform electron gas systems of up to 10124 matrix elements via a stochastic solution of the Bloch equation. The results of these calculations resolve a current debate over the accuracy of the data used to parametrize finite-temperature density functionals. Exchange-correlation energies calculated using the real-space restricted path-integral formalism and the k -space configuration path-integral formalism disagree by up to ˜10 % at certain reduced temperatures T /TF≤0.5 and densities rs≤1 . Our calculations confirm the accuracy of the configuration path-integral Monte Carlo results available at high density and bridge the gap to lower densities, providing trustworthy data in the regime typical of planetary interiors and solids subject to laser irradiation. We demonstrate that the DMQMC method can calculate free energies directly and present exact free energies for T /TF≥1 and rs≤2 .

  5. Accurate Zero Parameter Correlation Energy Functional Obtained from the Homogeneous Electron Gas with an Energy Gap

    NASA Astrophysics Data System (ADS)

    Krieger, J. B.; Chen, Jiqiang; Iafrate, G. J.; Savin, A.

    1998-03-01

    We have obtained an analytic approximation to E_c(r_g, ζ,G) where G is an energy gap separating the occupied and unoccupied states of a homogeneous electron gas for ζ=3D0 and ξ=3D1. When G=3D0, E_c(r_g, ζ) reduces to the usual LSD result. This functional is employed in calculating correlation energies for unpolarized atoms and ions for Z <= 18 by taking G[n]=3D1/8|nabla ln n|^2, which reduces to the ionization energy in the large r limit in an exact Kohn-Sham (KS) theory. The resulting functional is self-interaction-corrected employing a method which is invariant under a unitary transformation. We find that the application of this approach to the calculation of the Ec functional reduces the error in the LSD result by more than 95%. When the value of G is approximately corrected to include the effect of higher lying unoccupied localized states, the resulting values of Ec are within a few percent of the exact results.

  6. Accurate Exchange-Correlation Energies for the Warm Dense Electron Gas.

    PubMed

    Malone, Fionn D; Blunt, N S; Brown, Ethan W; Lee, D K K; Spencer, J S; Foulkes, W M C; Shepherd, James J

    2016-09-01

    The density matrix quantum Monte Carlo (DMQMC) method is used to sample exact-on-average N-body density matrices for uniform electron gas systems of up to 10^{124} matrix elements via a stochastic solution of the Bloch equation. The results of these calculations resolve a current debate over the accuracy of the data used to parametrize finite-temperature density functionals. Exchange-correlation energies calculated using the real-space restricted path-integral formalism and the k-space configuration path-integral formalism disagree by up to ∼10% at certain reduced temperatures T/T_{F}≤0.5 and densities r_{s}≤1. Our calculations confirm the accuracy of the configuration path-integral Monte Carlo results available at high density and bridge the gap to lower densities, providing trustworthy data in the regime typical of planetary interiors and solids subject to laser irradiation. We demonstrate that the DMQMC method can calculate free energies directly and present exact free energies for T/T_{F}≥1 and r_{s}≤2. PMID:27661699

  7. Gas-particle partitioning of semivolatile organic compounds (SOCs) on mixtures of aerosols in a smog chamber.

    PubMed

    Chandramouli, Bharadwaj; Jang, Myoseon; Kamens, Richard M

    2003-09-15

    The partitioning behavior of a set of diverse SOCs on two and three component mixtures of aerosols from different sources was studied using smog chamber experimental data. A set of SOCs of different compound types was introduced into a system containing a mixture of aerosols from two or more sources. Gas and particle samples were taken using a filter-filter-denuder sampling system, and a partitioning coefficient Kp was estimated using Kp = Cp/(CgTSP). Particle size distributions were measured using a differential mobility analyzer and a light scattering detector. Gas and particle samples were analyzed using GCMS. The aerosol composition in the chamber was tracked chemically using a combination of signature compounds and the organic matter mass fraction (f(om)) of the individual aerosol sources. The physical nature of the aerosol mixture in the chamber was determined using particle size distributions, and an aggregate Kp was estimated from theoretically calculated Kp on the individual sources. Model fits for Kp showed that when the mixture involved primary sources of aerosol, the aggregate Kp of the mixture could be successfully modeled as an external mixture of the Kp on the individual aerosols. There were significant differences observed for some SOCs between modeling the system as an external and as an internal mixture. However, when one of the aerosol sources was secondary, the aggregate model Kp required incorporation of the secondary aerosol products on the preexisting aerosol for adequate model fits. Modeling such a system as an external mixture grossly overpredicted the Kp of alkanes in the mixture. Indirect evidence of heterogeneous, acid-catalyzed reactions in the particle phase was also seen, leading to a significant increase in the polarity of the resulting aerosol mix and a resulting decrease in the observed Kp of alkanes in the chamber. The model was partly consistent with this decrease but could not completely explain the reduction in Kp because of

  8. Quantifying the impact of nitric oxide calibration gas mixture oxidation on reported nitrogen dioxide concentrations

    NASA Astrophysics Data System (ADS)

    Sweeney, Bryan P.; Quincey, Paul G.; Green, David; Fuller, Gary W.

    2015-03-01

    Chemiluminescent analysers for measuring nitric oxide (NO) and nitrogen dioxide (NO2) in ambient air are generally calibrated with certified gas standard cylinders of NO in nitrogen. Verification of the NOx and NO amount fractions has been carried out on many such 'on-site' calibration cylinders at air quality monitoring stations. These measurements indicate that significant numbers of these gas mixtures have become somewhat degraded, with several percent of the NO oxidised to NO2. The effect of not compensating for this degradation on reported concentrations is discussed. If such degradation is not quantified and corrected for, there will be a systematic under-reporting of NO2 concentrations, which, due to the non-linearity of the effect, could reduce high reported NO2 concentrations at kerbside sites by around 20%. This could significantly reduce the number of reported exceedances of the NO2 limit value at such sites, compared to results obtained where there is no degradation of the NO cylinder.

  9. Density functional theory of gas-liquid phase separation in dilute binary mixtures.

    PubMed

    Okamoto, Ryuichi; Onuki, Akira

    2016-06-22

    We examine statics and dynamics of phase-separated states of dilute binary mixtures using density functional theory. In our systems, the difference of the solvation chemical potential between liquid and gas [Formula: see text] (the Gibbs energy of transfer) is considerably larger than the thermal energy [Formula: see text] for each solute particle and the attractive interaction among the solute particles is weaker than that among the solvent particles. In these conditions, the saturated vapor pressure increases by [Formula: see text], where [Formula: see text] is the solute density added in liquid. For [Formula: see text], phase separation is induced at low solute densities in liquid and the new phase remains in gaseous states, even when the liquid pressure is outside the coexistence curve of the solvent. This explains the widely observed formation of stable nanobubbles in ambient water with a dissolved gas. We calculate the density and stress profiles across planar and spherical interfaces, where the surface tension decreases with increasing interfacial solute adsorption. We realize stable solute-rich bubbles with radius about 30 nm, which minimize the free energy functional. We then study dynamics around such a bubble after a decompression of the surrounding liquid, where the bubble undergoes a damped oscillation. In addition, we present some exact and approximate expressions for the surface tension and the interfacial stress tensor.

  10. Flame generation and maintenance by non-stationary discharge in mixture of air and natural gas

    NASA Astrophysics Data System (ADS)

    Medeiros, Henrique De Souza; Sagas, Julio; Lacava, Pedro

    2013-09-01

    Plasma assisted combustion is a promising research field, where the high generation of reactive species by non-equilibrium plasmas is used to modify the combustion kinetics in order to improve the process either by increasing the production of specific species (like molecular hydrogen) or by decreasing pollutant emission. One typical issue observed in plasma assisted combustion is the increase of inflammability limits, i.e the observation of combustion and flame in situation where it is not observed in conventional combustion. To study the effect of a non-stationary discharge in flame generation and maintenance in a mixture for air and natural gas, the air mass flow rate was fixed in 0.80 g/s and the natural gas flow rate was varied between 0.02 and 0.14 g/s, resulting in a variation of equivalence ratio from 0.4 to 3.0. It is observed a dependence of inflammability limits with the applied power. The analysis by mass spectrometry indicates that the increase of inflammability limits with plasma is due not only applied power, but also to hydrogen production in the discharge. Visual analysis together with high speed camera measurements show a modification in spatial distribution of the flame, probably due to modifications both in flow velocity and flame velocity. Supported by FAPESP PRONEX project grant 11/50773-0.

  11. Hydrogen generation in a microhollow cathode discharge in high-pressure ammonia-argon gas mixtures

    NASA Astrophysics Data System (ADS)

    Qiu, H.; Martus, K.; Lee, W. Y.; Becker, K.

    2004-04-01

    We explored the feasibility of using a single flow-through microhollow cathode discharge (MHCD) as a non-thermal plasma source for hydrogen (H2) production for portable fuel cell applications. The MHCD device consisted of two thin metal electrodes separated by a mica spacer with a single-hole, roughly 100 [mu]m in diameter, through all three layers. The efficiency of the MHCD reactor for H2 generation from NH3 was analyzed by monitoring the products formed in the discharge in a mass spectrometer. Using a gas mixture of up to 10% NH3 in Ar at pressures up to one atmosphere, the MHCD reactor achieved a maximum ammonia conversion of slightly more than 20%. The overall power efficiency of the MHCD reactor reached a peak value of about 11%. The dependence of NH3 conversion and power efficiency on the residence time of the gas in the MHCD plasma was studied. Experiments using pulsed excitation of the MHCD plasma indicated that pulsing can increase the power efficiency. Design and operating criteria are proposed for a microplasma-based H2 generator that can achieve a power efficiency above the break-even point, i.e., a microplasma reactor that requires less electrical power to generate and maintain the plasma than the power that can be obtained from the conversion of the H2 generated in the microplasma reactor.

  12. Detection of a CO and NH3 gas mixture using carboxylic acid-functionalized single-walled carbon nanotubes.

    PubMed

    Dong, Ki-Young; Choi, Jinnil; Lee, Yang Doo; Kang, Byung Hyun; Yu, Youn-Yeol; Choi, Hyang Hee; Ju, Byeong-Kwon

    2013-01-01

    Carbon nanotubes (CNT) are extremely sensitive to environmental gases. However, detection of mixture gas is still a challenge. Here, we report that 10 ppm of carbon monoxide (CO) and ammonia (NH3) can be electrically detected using a carboxylic acid-functionalized single-walled carbon nanotubes (C-SWCNT). CO and NH3 gases were mixed carefully with the same concentrations of 10 ppm. Our sensor showed faster response to the CO gas than the NH3 gas. The sensing properties and effect of carboxylic acid group were demonstrated, and C-SWCNT sensors with good repeatability and fast responses over a range of concentrations may be used as a simple and effective detection method of CO and NH3 mixture gas.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  14. Separation of gas mixtures by supported complexes. Final report, 1 October 1982-30 September 1984

    SciTech Connect

    Nelson, D.A.; Hallen, R.T.; Lilga, M.A.

    1985-01-01

    This final report covers research performed to identify and demonstrate advantageous procedures for the chemical separation of gases, such as CO, CO/sub 2/, and H/sub 2/, from medium-Btu gas mixtures by use of supported complexes. Three complexes were chosen for rapid gas uptake and selectivity at 25/sup 0/C from among a group of 22 coordination complexes synthesized during this program. The three complexes showed considerable selectivity toward individual gases. For instance, Pd/sub 2/(dpm)/sub 2/Cl/sub 2/ or bis-..mu..-(bisdiphenylphosphinomethane)-dichlorodipalladium (Pd-Pd), rapidly bound carbon monoxide from solution. This complex could be regenerated, with the carbon monoxide reversibly removed, by warming to 40/sup 0/C. The presence of other gases, such as carbon dioxide, oxygen, nitrogen, hydrogen, ethylene, or acetylene, had no effect upon the rapid uptake of carbon monoxide or its removal. Such selectivity was also noted with Ru(CO)/sub 2/(PPh/sub 3/)/sub 3/, biscarbonyltris(triphenylphosphine)ruthenium. Although this complex bound hydrogen, carbon monoxide, and oxygen in solution, the hydrogen was taken up twice as fast as carbon monoxide and seven times faster than oxygen. These gases could be removed from the complex with mild heat or decreased pressure. Crystalline Rh(OH)(CO)(PPh/sub 3/)/sub 2/, hydroxocarbonylbis(triphenylphosphine)rhodium, rapidly bound carbon dioxide; the complex was regenerated at 50/sup 0/C under reduced pressure. The rapid uptake of carbon dioxide by this complex was not changed in the presence of oxygen. In general the three selected crystalline or solvent dissolved complexes performed well in the absence of polymeric support. The stability and favorable kinetics of the three complexes suggest that they could be utilized in a solution system for gas separation (Conceptual Analyses and Preliminary Economics). Further, these complexes appear to be superb candidates as transport agents for facilitated-transport, membrane systems

  15. Mie scattering from submicron-sized CO2 clusters formed in a supersonic expansion of a gas mixture.

    PubMed

    Jinno, S; Fukuda, Y; Sakaki, H; Yogo, A; Kanasaki, M; Kondo, K; Faenov, A Ya; Skobelev, I Yu; Pikuz, T A; Boldarev, A S; Gasilov, V A

    2013-09-01

    A detailed mathematical model is presented for a submicron-sized cluster formation in a binary gas mixture flowing through a three-staged conical nozzle. By measuring the angular distribution of light scattered from the clusters, the size of CO(2) clusters, produced in a supersonic expansion of the mixture gas of CO(2)(30%)/H(2)(70%) or CO(2)(10%)/He(90%), has been evaluated using the Mie scattering method. The mean sizes of CO(2) clusters are estimated to be 0.28 ± 0.03 μm for CO(2)/H(2) and 0.26 ± 0.04 μm for CO(2)/He, respectively. In addition, total gas density profiles in radial direction of the gas jet, measuring the phase shift of the light passing through the target by utilizing an interferometer, are found to be agreed with the numerical modeling within a factor of two. The dryness (= monomer/(monomer + cluster) ratio) in the targets is found to support the numerical modeling. The apparatus developed to evaluate the cluster-gas targets proved that our mathematical model of cluster formation is reliable enough for the binary gas mixture.

  16. Start-up, performance and optimization of a compost biofilter treating gas-phase mixture of benzene and toluene.

    PubMed

    Rene, Eldon R; Kar, Saurajyoti; Krishnan, Jagannathan; Pakshirajan, K; López, M Estefanía; Murthy, D V S; Swaminathan, T

    2015-08-01

    The performance of a compost biofilter inoculated with mixed microbial consortium was optimized for treating a gas-phase mixture of benzene and toluene. The biofilter was acclimated to these VOCs for a period of ∼18d. The effects of concentration and flow rate on the removal efficiency (RE) and elimination capacity (EC) were investigated by varying the inlet concentration of benzene (0.12-0.95g/m(3)), toluene (0.14-1.48g/m(3)) and gas-flow rate (0.024-0.072m(3)/h). At comparable loading rates, benzene removal in the mixture was reduced in the range of 6.6-41% in comparison with the individual benzene degradation. Toluene removal in mixture was even more affected as observed from the reductions in REs, ranging from 18.4% to 76%. The results were statistically interpreted by performing an analysis of variance (ANOVA) to elucidate the main and interaction effects.

  17. Simulation of the transition radiation detection conditions in the ATLAS TRT detector filled with argon and krypton gas mixtures

    SciTech Connect

    Boldyrev, A. S.; Maevskiy, A. S.

    2015-12-15

    Performance of the Transition Radiation Tracker (TRT) at the ATLAS experiment with argon and krypton gas mixtures was simulated. The efficiency of transition radiation registration, which is necessary for electron identification, was estimated along with the electron identification capabilities under such conditions.

  18. Introducing Students to Gas Chromatography-Mass Spectrometry Analysis and Determination of Kerosene Components in a Complex Mixture

    ERIC Educational Resources Information Center

    Pacot, Giselle Mae M.; Lee, Lyn May; Chin, Sung-Tong; Marriott, Philip J.

    2016-01-01

    Gas chromatography-mass spectrometry (GC-MS) and GC-tandem MS (GC-MS/MS) are useful in many separation and characterization procedures. GC-MS is now a common tool in industry and research, and increasingly, GC-MS/MS is applied to the measurement of trace components in complex mixtures. This report describes an upper-level undergraduate experiment…

  19. Effect of Alumina on the Gaseous Reduction of Magnetite in CO/CO2 Gas Mixtures

    NASA Astrophysics Data System (ADS)

    Kapelyushin, Yury; Xing, Xing; Zhang, Jianqiang; Jeong, Sunkwang; Sasaki, Yasushi; Ostrovski, Oleg

    2015-03-01

    Reduction of magnetite doped with alumina (3, 6 and 12 mass pct Al2O3) was studied using CO/CO2 gas mixture (80 vol pct CO) at 1023 K and 1123 K (750 °C and 850 °C). The reduction rate and degree of reduction were evaluated from the weight loss of a sample with time. The reduction behavior was analyzed using the results of XRD and SEM-EDS measurements and thermodynamic analysis. Effect of alumina on the magnetite reduction depended on the alumina content and temperature. Magnetite reduction at 1023 K (750 °C) was accelerated by the addition of 3 mass pct Al2O3, however, the rate of reduction significantly decreased with the further increase in the alumina content to 6 and 12 mass pct. Different effect of alumina was observed in reduction at 1123 K (850 °C); the rate of reduction of the Fe3O4-Al2O3 mixture with 6 mass pct Al2O3 was the fastest. Reduction of un-doped magnetite was developed topochemically with the formation of a dense iron shell. However, reduction of alumina-doped magnetite to wüstite started along certain lattice planes with the formation of network-like structure. In the course of reduction, Al3+ ions diffused from wüstite to the Fe3O4-FeAl2O4 solution enriching hercynite content in the solution at the reaction interface. Further reduction of alumina-rich Fe3O4-FeAl2O4 solution resulted in the formation of micro-cracks which enhanced the rate of the reduction process.

  20. Supersonic flow of chemically reacting gas-particle mixtures. Volume 1: A theoretical analysis and development of the numerical solution

    NASA Technical Reports Server (NTRS)

    Penny, M. M.; Smith, S. D.; Anderson, P. G.; Sulyma, P. R.; Pearson, M. L.

    1976-01-01

    A numerical solution for chemically reacting supersonic gas-particle flows in rocket nozzles and exhaust plumes was described. The gas-particle flow solution is fully coupled in that the effects of particle drag and heat transfer between the gas and particle phases are treated. Gas and particles exchange momentum via the drag exerted on the gas by the particles. Energy is exchanged between the phases via heat transfer (convection and/or radiation). Thermochemistry calculations (chemical equilibrium, frozen or chemical kinetics) were shown to be uncoupled from the flow solution and, as such, can be solved separately. The solution to the set of governing equations is obtained by utilizing the method of characteristics. The equations cast in characteristic form are shown to be formally the same for ideal, frozen, chemical equilibrium and chemical non-equilibrium reacting gas mixtures. The particle distribution is represented in the numerical solution by a finite distribution of particle sizes.

  1. FAST TRACK COMMUNICATION: Effects of reducing interferers in a binary gas mixture on NO2 gas adsorption using carbon nanotube networked films based chemiresistors

    NASA Astrophysics Data System (ADS)

    Penza, M.; Rossi, R.; Alvisi, M.; Signore, M. A.; Serra, E.

    2009-04-01

    Analysis of binary gas mixtures using chemiresistors based on carbon nanotubes (CNTs) networked films has been performed for chemical detection up to a sub-ppm level. The effects of individual interfering analytes of reducing H2S and NH3 gases on oxidizing NO2 gas adsorption in CNTs tangled films are considered. The CNTs are grown by plasma-enhanced chemical vapour deposition technology onto inexpensive alumina substrates, coated by cobalt nanosized catalyst. Charge transfer between adsorbed gas molecules and CNT networks, characterized by a semiconducting p-type electrical transport, occurs depending on opposite trend in the sensor response to the electron-donating interfering gases (H2S, NH3) and target electron-withdrawing NO2 gas causing a compensation of the charge transport, upon given working conditions. This compensated exchange of electrical charge affects the limit of detection of the targeted NO2 gas sensed in different real-world binary gas mixtures of reducing interferers of H2S and NH3. In addition, the functionalization of the CNT films with Au nanoclusters enhanced the sensitivity of the chemiresistor and tuned the compensation of electrical charge crossover in the selected binary oxido-reducing mixtures.

  2. Accurate ab initio potential for the krypton dimer and transport properties of the low-density krypton gas.

    PubMed

    Waldrop, Jonathan M; Song, Bo; Patkowski, Konrad; Wang, Xiaopo

    2015-05-28

    A new highly accurate potential energy curve for the krypton dimer was constructed using coupled-cluster calculations up to the singles, doubles, triples, and perturbative quadruples level, including corrections for core-core and core-valence correlation and for relativistic effects. The ab initio data points were fitted to an analytic potential which was used to compute the most important transport properties of the krypton gas. The viscosity, thermal conductivity, self-diffusion coefficient, and thermal diffusion factor were calculated by the kinetic theory at low density and temperatures from 116 to 5000 K. The comparisons with literature experimental data as well as with values from other pair potentials indicate that our new potential is superior to all previous ones. The transport property values computed in this work are recommended as standard values over the complete temperature range.

  3. Accurate ab initio potential for the krypton dimer and transport properties of the low-density krypton gas.

    PubMed

    Waldrop, Jonathan M; Song, Bo; Patkowski, Konrad; Wang, Xiaopo

    2015-05-28

    A new highly accurate potential energy curve for the krypton dimer was constructed using coupled-cluster calculations up to the singles, doubles, triples, and perturbative quadruples level, including corrections for core-core and core-valence correlation and for relativistic effects. The ab initio data points were fitted to an analytic potential which was used to compute the most important transport properties of the krypton gas. The viscosity, thermal conductivity, self-diffusion coefficient, and thermal diffusion factor were calculated by the kinetic theory at low density and temperatures from 116 to 5000 K. The comparisons with literature experimental data as well as with values from other pair potentials indicate that our new potential is superior to all previous ones. The transport property values computed in this work are recommended as standard values over the complete temperature range. PMID:26026447

  4. Effect of Non-Condensable Gas Mass Fraction on Condensation Heat Transfer for Water-Ethanol Vapor Mixture

    NASA Astrophysics Data System (ADS)

    Wang, Shixue; Utaka, Yoshio

    The condensation heat transfer characteristic curves for a ternary vapor mixture of water, ethanol and air (or nitrogen) under several ethanol concentrations and relatively low concentrations of air (or nitrogen) were measured. The effect of non-condensable gas on several different domains in the condensation curves was discussed. The effect of non-condensable gas in the domains controlled by the diffusion resistance and the filmwise condensation was not notable; whereas that in the domain dominated by the condensate resistance of dropwise mode was remarkable. Moreover, variations due to changes in non-condensable gas concentration of several characteristic points representing the curves were discussed.

  5. Kinetic Equation for Two-Particle Distribution Function in Boltzmann Gas Mixtures and Equation of Motion for Quasiparticle Pairs

    NASA Astrophysics Data System (ADS)

    Saveliev, V. L.

    2011-05-01

    Pair collisions is the main interaction process in the Boltzmann gas dynamics. By making use of exactly the same physical assumptions as was used by Ludwig Boltzmann we write the kinetic equation for two-particle distribution function of molecules in the gas mixtures. Instead of the collision integral, there are the linear scattering operator and the chaos projector in the right part of this equation. Because the scattering operator is more simple then Boltzmann collision integral this equation opens new opportunities for mathematical description of the Boltzmann gas dynamics.

  6. Preliminary results of Resistive Plate Chambers operated with eco-friendly gas mixtures for application in the CMS experiment

    NASA Astrophysics Data System (ADS)

    Abbrescia, M.; Van Auwegem, P.; Benussi, L.; Bianco, S.; Cauwenbergh, S.; Ferrini, M.; Muhammad, S.; Passamonti, L.; Pierluigi, D.; Piccolo, D.; Primavera, F.; Russo, A.; Saviano, G.; Tytgat, M.

    2016-09-01

    The operations of Resistive Plate Chambers in LHC experiments require Fluorine based (F-based) gases for optimal performance. Recent European regulations demand the use of environmentally unfriendly F-based gases to be limited or banned. In view of the CMS experiment upgrade, several tests are ongoing to measure the performance of the detector with these new ecological gas mixtures, in terms of efficiency, streamer probability, induced charge and time resolution. Prototype chambers with readout pads and with the standard CMS electronic setup are under test. In this paper preliminary results on performance of RPCs operated with a potential eco-friendly gas candidate 1,3,3,3-Tetrafluoropropene, commercially known as HFO-1234ze, with CO2 and CF3I based gas mixtures are presented and discussed for the possible application in the CMS experiment.

  7. Similarity solutions of a strong shock wave propagation in a mixture of a gas and dusty particles

    NASA Technical Reports Server (NTRS)

    Pai, S. I.; Menon, S.; Fan, Z. Q.

    1980-01-01

    The similarity solutions of a strong shock wave propagation in a mixture of a gas and small solid particles have been investigated. Similarity solution exists only when the shock is very strong and the surrounding medium is of a constant density and at rest and with negligible counterpressure. The non-dimensional fundamental equations are derived and studied. The results depend on three non-dimensional parameters; i.e. (1) the ratio of the specific heats of the gas, (2) the mass concentration of the solid particles in the mixture and (3) the ratio of the density of the solid to that of initial density of the gas. Numerical solutions for various values of these parameters are presented and discussed. The speeds of the shock wave front and its location with various energy releases are given.

  8. Density functional theory of gas-liquid phase separation in dilute binary mixtures

    NASA Astrophysics Data System (ADS)

    Okamoto, Ryuichi; Onuki, Akira

    2016-06-01

    We examine statics and dynamics of phase-separated states of dilute binary mixtures using density functional theory. In our systems, the difference of the solvation chemical potential between liquid and gas Δ {μ\\text{s}} (the Gibbs energy of transfer) is considerably larger than the thermal energy {{k}\\text{B}}T for each solute particle and the attractive interaction among the solute particles is weaker than that among the solvent particles. In these conditions, the saturated vapor pressure increases by {{k}\\text{B}}Tn2\\ell\\exp ≤ft(Δ {μ\\text{s}}/{{k}\\text{B}}T\\right) , where n2\\ell is the solute density added in liquid. For \\exp ≤ft(Δ {μ\\text{s}}/{{k}\\text{B}}T\\right)\\gg 1 , phase separation is induced at low solute densities in liquid and the new phase remains in gaseous states, even when the liquid pressure is outside the coexistence curve of the solvent. This explains the widely observed formation of stable nanobubbles in ambient water with a dissolved gas. We calculate the density and stress profiles across planar and spherical interfaces, where the surface tension decreases with increasing interfacial solute adsorption. We realize stable solute-rich bubbles with radius about 30 nm, which minimize the free energy functional. We then study dynamics around such a bubble after a decompression of the surrounding liquid, where the bubble undergoes a damped oscillation. In addition, we present some exact and approximate expressions for the surface tension and the interfacial stress tensor.

  9. Multiclass semi-volatile compounds determination in wine by gas chromatography accurate time-of-flight mass spectrometry.

    PubMed

    Rodríguez-Cabo, T; Rodríguez, I; Ramil, M; Silva, A; Cela, R

    2016-04-15

    The performance of gas chromatography (GC) with accurate, high resolution mass spectrometry (HRMS) for the determination of a group of 39 semi-volatile compounds related to wine quality (pesticide residues, phenolic off-flavours, phenolic pollutants and bioactive stilbenes) is investigated. Solid-phase extraction (SPE) was used as extraction technique, previously to acetylation (phenolic compounds) and dispersive liquid-liquid microextraction (DLLME) concentration. Compounds were determined by GC coupled to a quadrupole time-of-flight (QTOF) MS system through an electron ionization (EI) source. The final method attained limits of quantification (LOQs) at the very low ng mL(-1) level, covering the range of expected concentrations for target compounds in red and white wines. For 38 out of 39 compounds, performance of sample preparation and determination steps were hardly affected by the wine matrix; thus, accurate recoveries were achieved by using pseudo-external calibration. Levels of target compounds in a set of 25 wine samples are reported. The capabilities of the described approach for the post-run identification of species not considered during method development, without retention time information, are illustrated and discussed with selected examples of compounds from different classes.

  10. Analysis of siloxanes in hydrocarbon mixtures using comprehensive two-dimensional gas chromatography.

    PubMed

    Ghosh, Abhijit; Seeley, Stacy K; Nartker, Steven R; Seeley, John V

    2014-09-19

    A comprehensive two-dimensional gas chromatography (GC×GC) method for separating siloxanes from hydrocarbons has been developed using a systematic process. First, the retention indices of a set of siloxanes and a set of hydrocarbons were determined on 6 different stationary phases. The retention indices were then used to model GC×GC separation on 15 different stationary phase pairs. The SPB-Octyl×DB-1 pair was predicted to provide the best separation of the siloxanes from the hydrocarbons. The efficacy of this stationary phase pair was experimentally tested by performing a GC×GC analysis of gasoline spiked with siloxanes and by analyzing biogas obtained from a local wastewater treatment facility. The model predictions agreed well with the experimental results. The SPB-Octyl×DB-1 stationary phase pair constrained the hydrocarbons to a narrow range of secondary retention times and fully isolated the siloxanes from the hydrocarbon band. The resulting GC×GC method allows siloxanes to be resolved from complex mixtures of hydrocarbons without requiring the use of a selective detector.

  11. Hovering flight mechanics of neotropical flower bats (Phyllostomidae: Glossophaginae) in normodense and hypodense gas mixtures.

    PubMed

    Dudley, Robert; Winter, York

    2002-12-01

    Existing estimates of flight energetics in glossophagine flower bats, the heaviest hovering vertebrate taxon, suggest disproportionately high expenditure of mechanical power. We determined wingbeat kinematics and mechanical power expenditure for one of the largest flower bats (Leptonycteris curasoae Martinez and Villa) during hovering flight in normodense and hypodense gas mixtures. Additional experiments examined the effects of supplemental oxygen availability on maximum flight performance. Bats failed to sustain hovering flight at normoxic air densities averaging 63% that of normodense air. Kinematic responses to hypodense aerodynamic challenge involved increases in wing positional angles and in total stroke amplitude; wingbeat frequency was unchanged. At near-failure air densities, total power expenditure assuming perfect elastic energy storage was 17-42% greater than that for hovering in normodense air, depending on the assumed value for the profile drag coefficient. Assuming a flight muscle ratio of 26%, the associated muscle-mass-specific power output at the point of near-failure varied between 90.8 W kg(-1) (profile drag coefficient of 0.02) to 175.6 W kg(-1) (profile drag coefficient of 0.2). Hyperoxia did not enhance hovering performance in hypodense air, and, with the exception of a small increase (10%) in stroke plane angle, yielded no significant change in any of the kinematic parameters studied. Revised energetic estimates suggest that mechanical power expenditure of hovering glossophagines is comparable with that in slow forward flight.

  12. Spectral Characteristics of Deuterium-, Helium- and Gas-Mixture-Discharges within PF-1000 Facility

    SciTech Connect

    Tsarenko, A.; Malinowski, K.; Skladnik-Sadowska, E.; Sadowski, M. J.; Scholz, M.; Paduch, M.; Tomaszewski, K.

    2006-01-15

    The paper reports on spectroscopic studies of high-current plasma discharges performed at different gas fillings within the large PF-1000 facility. To study visible radiation (VR) the use was made of a MECHELLE registered 900-spectrometer equipped with the CCD readout. The observations of a PF pinch column were performed at an angle of about 65 deg. to the z-axis, and the viewing field was at a distance of 40-50 mm from the electrode ends. Optical measurements were carried out at 0.5-{mu}s exposition synchronized with a chosen period of the investigated discharge. Differences in the optical spectra, recorded at various deuterium-helium mixtures, were analyzed. Intensities of HeI lines were computed for an assumed electron temperature and compared with the experiment. Estimated plasma concentration in pure-deuterium discharges amounted to 8x1018 cm-3, while that in pure helium shots was (4-7)x1017 cm-3 only. Estimates of the electron temperature, from the ratio of intensities of the chosen spectral lines and the continuum, gave values ranging from 5 eV to 50 eV. The paper presents also some spectra from 'weak shots', which show distinct impurity lines caused by different reasons.

  13. Shell Perturbations of an Acoustic Thermometer Determined from Speed of Sound in Gas Mixtures

    NASA Astrophysics Data System (ADS)

    Gavioso, R. M.; Madonna Ripa, D.; Guianvarc'h, C.; Benedetto, G.; Giuliano Albo, P. A.; Cuccaro, R.; Pitre, L.; Truong, D.

    2010-09-01

    With the goal of achieving a better understanding of gas-shell coupling perturbations in the acoustic resonators used at INRiM for the determination of the Boltzmann constant, we measured the variation of their acoustic and microwave resonances induced by changing the composition of a binary He-Ar mixture which filled the cavity at constant temperature and pressure. As a consequence of the progressive dilution of a sample of initially pure He with Ar, the radial acoustic modes of the resonator spanned decreasing frequency intervals, partially overlapping, for several modes. In addition to the expected breathing mode of the shell, the results evidenced the presence of several other shell resonances at lower and higher frequencies, confirming that the elastic response of the assembled resonator significantly differs from that of a simple spherical shell. Experimental results are reported for two resonators which differ in design, dimensions, and constructing material. In spite of their being preliminary and susceptible of significant improvement, these results favor the interpretation of acoustic thermometry measurements with pure gases.

  14. Improvement in methanol production by regulating the composition of synthetic gas mixture and raw biogas.

    PubMed

    Patel, Sanjay K S; Mardina, Primata; Kim, Dongwook; Kim, Sang-Yong; Kalia, Vipin C; Kim, In-Won; Lee, Jung-Kul

    2016-10-01

    Raw biogas can be an alternative feedstock to pure methane (CH4) for methanol production. In this investigation, we evaluated the methanol production potential of Methylosinus sporium from raw biogas originated from an anaerobic digester. Furthermore, the roles of different gases in methanol production were investigated using synthetic gas mixtures of CH4, carbon dioxide (CO2), and hydrogen (H2). Maximum methanol production was 5.13, 4.35, 6.28, 7.16, 0.38, and 0.36mM from raw biogas, CH4:CO2, CH4:H2, CH4:CO2:H2, CO2, and CO2:H2, respectively. Supplementation of H2 into raw biogas increased methanol production up to 3.5-fold. Additionally, covalent immobilization of M. sporium on chitosan resulted in higher methanol production from raw biogas. This study provides a suitable approach to improve methanol production using low cost raw biogas as a feed containing high concentrations of H2S (0.13%). To our knowledge, this is the first report on methanol production from raw biogas, using immobilized cells of methanotrophs. PMID:27371792

  15. Dust and gas mixtures with multiple grain species - a one-fluid approach

    NASA Astrophysics Data System (ADS)

    Laibe, Guillaume; Price, Daniel J.

    2014-10-01

    We derive the single-fluid evolution equations describing a mixture made of a gas phase and an arbitrary number of dust phases, generalizing the approach developed by Laibe & Price. A generalization for continuous dust distributions as well as analytic approximations for strong drag regimes is also provided. This formalism lays the foundation for numerical simulations of dust populations in a wide range of astrophysical systems while avoiding limitations associated with a multiple-fluid treatment. The usefulness of the formalism is illustrated on a series of analytical problems, namely the DUSTYBOX, DUSTYSHOCK and DUSTYWAVE problems as well as the radial drift of grains and the streaming instability in protoplanetary discs. We find physical effects specific to the presence of several dust phases and multiple drag time-scales, including non-monotonic evolution of the differential velocity between phases and increased efficiency of the linear growth of the streaming instability. Interestingly, it is found that under certain conditions, large grains can migrate outwards in protoplanetary discs. This may explain the presence of small pebbles at several hundreds of astronomical units from their central star.

  16. Recovery of methane from gas hydrates intercalated within natural sediments using CO(2) and a CO(2)/N(2) gas mixture.

    PubMed

    Koh, Dong-Yeun; Kang, Hyery; Kim, Dae-Ok; Park, Juwoon; Cha, Minjun; Lee, Huen

    2012-08-01

    The direct recovery of methane from massive methane hydrates (MHs), artificial MH-bearing clays, and natural MH-bearing sediments is demonstrated, using either CO(2) or a CO(2)/N(2) gas mixture (20 mol % of CO(2) and 80 mol % of N(2), reproducing flue gas from a power plant) for methane replacement in complex marine systems. Natural gas hydrates (NGHs) can be converted into CO(2) hydrate by a swapping mechanism. The overall process serves a dual purpose: it is a means of sustainable energy-source exploitation and greenhouse-gas sequestration. In particular, scant attention has been paid to the natural sediment clay portion in deep-sea gas hydrates, which is capable of storing a tremendous amount of NGH. The clay interlayer provides a unique chemical-physical environment for gas hydrates. Herein, for the first time, we pull out methane from intercalated methane hydrates in a clay interlayer using CO(2) and a CO(2)/N(2) gas mixture. The results of this study are expected to provide an essential physicochemical background required for large-scale NGH production under the seabed. PMID:22730158

  17. Dose addition models based on biologically-relevant reductions in fetal testosterone accurately predict postnatal reproductive tract alterations by a phthalate mixture in rats

    EPA Science Inventory

    Challenges in cumulative risk assessment of anti-androgenic phthalate mixtures include a lack of data on all the individual phthalates and difficulty determining the biological relevance of reduction in fetal testosterone (T) on postnatal development. The objectives of the curren...

  18. Gas chromatography

    NASA Astrophysics Data System (ADS)

    Guiochon, Georges; Guillemin, Claude L.

    1990-11-01

    Gas chromatography is a powerful separation technique for gas and vapor mixtures. Combining separation and on-line detection permits accurate quantitative analysis of complex mixtures, including traces of compounds down to parts per trillions in some particular cases. The importance of gas chromatography in quality control and process control in the chemical and drug industry, in environmental pollution investigations and in clinical analysis is critical. The principles of the technique are discussed, the main components of a gas chromatograph are described and some idea of the importance of the applications is given.

  19. COOMET.QM-S5 (COOMET project No 576/RU/12) 'Supplementary comparison of national standards in the field of analysis of gas mixtures containing CO2, CO, C3H8 in nitrogen ("automotive" gas mixtures)'

    NASA Astrophysics Data System (ADS)

    Konopelko, L. A.; Kolobova, A. V.; Rozhnov, M. S.; Melnyk, D. M.; Petryshyn, P. V.; Shpilnyi, S. A.; Iakubov, S. E.; Bakovec, N. V.; Kluchits, A. S.; Kipphardt, H.; Aleksandrov, V. V.

    2016-01-01

    The relevance of the COOMET.QM-S5 comparison is founded on tightening of requirements to a control of automobile emissions (realization of environmental standards of EURO 4, EURO-5). Participating laboratories: VNIIM, BAM, BelGIM, Ukrmetrteststandart, KazInMetr. This comparison was carried out in 2013-2014. This supplementary comparison supports CMC claims for: CO2 in the range (4-16) . 10-2 mol/mol; CO in the range (0.5-5) . 10-2 mol/mol; C3H8 in the range (0.01-0.3) . 10-2 mol/mol. Results: Component CO: All laboratories identified the values of carbon monoxide mole fraction in the gas mixture within +/-0.9134%. Component CO2: All laboratories identified the values of carbon dioxide mole fraction in the gas mixture within +/-0.3042%. Component C3H8: All laboratories identified the values of propane mole fraction in the gas mixture within +/-0.443%. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  20. Mathematical Modeling of Non-Stationary Hydraulic Process Occurring in the Gas Centrifuge Cascade During the Separation of Multicomponent Isotope Mixtures

    NASA Astrophysics Data System (ADS)

    Orlov, A. A.; Ushakov, A. A.; Sovach, V. P.

    2016-08-01

    This article presents results of development of the mathematical model of nonstationary separation processes occurring in gas centrifuge cascades for separation of multicomponent isotope mixtures. This model was used for the calculation parameters of gas centrifuge cascade for separation of germanium isotopes. Comparison of obtained values with results of other authors revealed that developed mathematical model is adequate to describe nonstationary separation processes in gas centrifuge cascades for separation of multicomponent isotope mixtures.

  1. A hydrogen gas-water equilibration method produces accurate and precise stable hydrogen isotope ratio measurements in nutrition studies.

    PubMed

    Wong, William W; Clarke, Lucinda L

    2012-11-01

    Stable hydrogen isotope methodology is used in nutrition studies to measure growth, breast milk intake, and energy requirement. Isotope ratio MS is the best instrumentation to measure the stable hydrogen isotope ratios in physiological fluids. Conventional methods to convert physiological fluids to hydrogen gas (H(2)) for mass spectrometric analysis are labor intensive, require special reagent, and involve memory effect and potential isotope fractionation. The objective of this study was to determine the accuracy and precision of a platinum catalyzed H(2)-water equilibration method for stable hydrogen isotope ratio measurements. Time to reach isotopic equilibrium, day-to-day and week-to-week reproducibility, accuracy, and precision of stable hydrogen isotope ratio measurements by the H(2)-water equilibration method were assessed using a Thermo DELTA V Advantage continuous-flow isotope ratio mass spectrometer. It took 3 h to reach isotopic equilibrium. The day-to-day and week-to-week measurements on water and urine samples with natural abundance and enriched levels of deuterium were highly reproducible. The method was accurate to within 2.8 (o)/oo and reproducible to within 4.0 (o)/oo based on analysis of international references. All the outcome variables, whether in urine samples collected in 10 doubly labeled water studies or plasma samples collected in 26 body water studies, did not differ from those obtained using the reference zinc reduction method. The method produced highly accurate estimation on ad libitum energy intakes, body composition, and water turnover rates. The method greatly reduces the analytical cost and could easily be adopted by laboratories equipped with a continuous-flow isotope ratio mass spectrometer.

  2. A Hydrogen Gas-Water Equilibration Method Produces Accurate and Precise Stable Hydrogen Isotope Ratio Measurements in Nutrition Studies12

    PubMed Central

    Wong, William W.; Clarke, Lucinda L.

    2012-01-01

    Stable hydrogen isotope methodology is used in nutrition studies to measure growth, breast milk intake, and energy requirement. Isotope ratio MS is the best instrumentation to measure the stable hydrogen isotope ratios in physiological fluids. Conventional methods to convert physiological fluids to hydrogen gas (H2) for mass spectrometric analysis are labor intensive, require special reagent, and involve memory effect and potential isotope fractionation. The objective of this study was to determine the accuracy and precision of a platinum catalyzed H2-water equilibration method for stable hydrogen isotope ratio measurements. Time to reach isotopic equilibrium, day-to-day and week-to-week reproducibility, accuracy, and precision of stable hydrogen isotope ratio measurements by the H2-water equilibration method were assessed using a Thermo DELTA V Advantage continuous-flow isotope ratio mass spectrometer. It took 3 h to reach isotopic equilibrium. The day-to-day and week-to-week measurements on water and urine samples with natural abundance and enriched levels of deuterium were highly reproducible. The method was accurate to within 2.8 o/oo and reproducible to within 4.0 o/oo based on analysis of international references. All the outcome variables, whether in urine samples collected in 10 doubly labeled water studies or plasma samples collected in 26 body water studies, did not differ from those obtained using the reference zinc reduction method. The method produced highly accurate estimation on ad libitum energy intakes, body composition, and water turnover rates. The method greatly reduces the analytical cost and could easily be adopted by laboratories equipped with a continuous-flow isotope ratio mass spectrometer. PMID:23014490

  3. Numerical Prediction of Radiation Measurements Taken in the X2 Facility for Mars and Titan Gas Mixtures

    NASA Technical Reports Server (NTRS)

    Palmer, Grant; Prabhu, Dinesh; Brandis, Aaron; McIntyre, Timothy J.

    2011-01-01

    Thermochemical relaxation behind a normal shock in Mars and Titan gas mixtures is simulated using a CFD solver, DPLR, for a hemisphere of 1 m radius; the thermochemical relaxation along the stagnation streamline is considered equivalent to the flow behind a normal shock. Flow simulations are performed for a Titan gas mixture (98% N2, 2% CH4 by volume) for shock speeds of 5.7 and 7.6 km/s and pressures ranging from 20 to 1000 Pa, and a Mars gas mixture (96% CO2, and 4% N2 by volume) for a shock speed of 8.6 km/s and freestream pressure of 13 Pa. For each case, the temperatures and number densities of chemical species obtained from the CFD flow predictions are used as an input to a line-by-line radiation code, NEQAIR. The NEQAIR code is then used to compute the spatial distribution of volumetric radiance starting from the shock front to the point where thermochemical equilibrium is nominally established. Computations of volumetric spectral radiance assume Boltzmann distributions over radiatively linked electronic states of atoms and molecules. The results of these simulations are compared against experimental data acquired in the X2 facility at the University of Queensland, Australia. The experimental measurements were taken over a spectral range of 310-450 nm where the dominant contributor to radiation is the CN violet band system. In almost all cases, the present approach of computing the spatial variation of post-shock volumetric radiance by applying NEQAIR along a stagnation line computed using a high-fidelity flow solver with good spatial resolution of the relaxation zone is shown to replicate trends in measured relaxation of radiance for both Mars and Titan gas mixtures.

  4. Low-pressure equilibrium binary argon-methane gas mixture adsorption on exfoliated graphite: Experiments and simulations

    NASA Astrophysics Data System (ADS)

    Albesa, Alberto; Russell, Brice; Vicente, José Luis; Rafti, Matías

    2016-04-01

    Adsorption equilibrium measurements of pure methane, pure argon, and binary mixtures over exfoliated graphite were carried for different initial compositions, temperatures, and total pressures in the range of 0.1-1.5 Torr using the volumetric static method. Diagrams for gas and adsorbed phase compositions were constructed for the conditions explored, and isosteric heats of adsorption were calculated. Experimental results were compared with predictions obtained with Monte Carlo simulations and using the Ideal Adsorbed Solution Theory (IAST).

  5. Dry etching of CdTe/GaAs epilayers using CH{sub 4}H{sub 2} gas mixtures

    SciTech Connect

    Neswal, M.; Gresslehner, K.H.; Lischka, K.

    1993-05-01

    A CH{sub 4}/H{sub 2} gas mixture has been used for the dry etching of (100) and (111) oriented CdTe epilayers in a barrel reactor. The effects of various process parameters on etch rate and surface morphology were studied with special attention paid to the gas composition and the total chamber pressure as well as the crystallographic orientation of the sample. Clear evidence is found for both isotropic and preferential etching along crystalolographic planes depending on the set of etch parameters used. 14 refs., 7 figs.

  6. Response of electrochemical oxygen sensors to inert gas-air and carbon dioxide-air mixtures: measurements and mathematical modelling.

    PubMed

    Walsh, P T; Gant, S E; Dowker, K P; Batt, R

    2011-02-15

    Electrochemical oxygen gas sensors are widely used for monitoring the state of inertisation of flammable atmospheres and to warn of asphyxiation risks. It is well established but not widely known by users of such oxygen sensors that the response of the sensor is affected by the nature of the diluent gas responsible for the decrease in ambient oxygen concentration. The present work investigates the response of electrochemical sensors, with either acid or alkaline electrolytes, to gas mixtures comprising air with enhanced levels of nitrogen, carbon dioxide, argon or helium. The measurements indicate that both types of sensors over-read the oxygen concentrations when atmospheres contain high levels of helium. Sensors with alkaline electrolytes are also shown to underestimate the severity of the hazard in atmospheres containing high levels of carbon dioxide. This deviation is greater for alkaline electrolyte sensors compared to acid electrolyte sensors. A Computational Fluid Dynamics (CFD) model is developed to predict the response of an alkaline electrolyte, electrochemical gas sensor. Differences between predicted and measured sensor responses are less than 10% in relative terms for nearly all of the gas mixtures tested, and in many cases less than 5%. Extending the model to simulate responses of sensors with acid electrolytes would be straightforward.

  7. Influence of gas temperature on self-sustained volume discharge characteristics in working mixtures of a repetitively pulsed COIL

    SciTech Connect

    Aksinin, V I; Kazantsev, S Yu; Kononov, I G; Podlesnykh, S V; Firsov, K N; Antsiferov, S A; Velikanov, S D; Kalinovskii, V V; Konovalov, V V; Mikhalkin, V N; Sevryugin, I V

    2014-02-28

    The influence of gas temperature on the characteristics of a self-sustained volume discharge was studied in the working mixtures of a chemical oxygen – iodine laser with pulsed electricdischarge production of iodine atoms. In experiments, laser working mixtures were modelled by the mixture of air and iodide C{sub 2}H{sub 5}I. It was established that mixture heating is accompanied by an increase in the voltage across the discharge plasma and by a decrease in the discharge current. By varying the temperature of the mixture with the iodine content of ∼2.7% and initial pressure p=12 Torr from 22 °C to 96 °C, the current amplitude falls by ∼12%, and at the instant corresponding to a maximal current the voltage raises by ∼22%. Such a change in the discharge characteristics is explained by a higher rate of electron attachment to vibrationally excited iodide molecules at elevated temperatures. (active media)

  8. Tunable integration of absorption-membrane-adsorption for efficiently separating low boiling gas mixtures near normal temperature

    PubMed Central

    Liu, Huang; Pan, Yong; Liu, Bei; Sun, Changyu; Guo, Ping; Gao, Xueteng; Yang, Lanying; Ma, Qinglan; Chen, Guangjin

    2016-01-01

    Separation of low boiling gas mixtures is widely concerned in process industries. Now their separations heavily rely upon energy-intensive cryogenic processes. Here, we report a pseudo-absorption process for separating low boiling gas mixtures near normal temperature. In this process, absorption-membrane-adsorption is integrated by suspending suitable porous ZIF material in suitable solvent and forming selectively permeable liquid membrane around ZIF particles. Green solvents like water and glycol were used to form ZIF-8 slurry and tune the permeability of liquid membrane surrounding ZIF-8 particles. We found glycol molecules form tighter membrane while water molecules form looser membrane because of the hydrophobicity of ZIF-8. When using mixing solvents composed of glycol and water, the permeability of liquid membrane becomes tunable. It is shown that ZIF-8/water slurry always manifests remarkable higher separation selectivity than solid ZIF-8 and it could be tuned to further enhance the capture of light hydrocarbons by adding suitable quantity of glycol to water. Because of its lower viscosity and higher sorption/desorption rate, tunable ZIF-8/water-glycol slurry could be readily used as liquid absorbent to separate different kinds of low boiling gas mixtures by applying a multistage separation process in one traditional absorption tower, especially for the capture of light hydrocarbons. PMID:26892255

  9. Tunable integration of absorption-membrane-adsorption for efficiently separating low boiling gas mixtures near normal temperature.

    PubMed

    Liu, Huang; Pan, Yong; Liu, Bei; Sun, Changyu; Guo, Ping; Gao, Xueteng; Yang, Lanying; Ma, Qinglan; Chen, Guangjin

    2016-02-19

    Separation of low boiling gas mixtures is widely concerned in process industries. Now their separations heavily rely upon energy-intensive cryogenic processes. Here, we report a pseudo-absorption process for separating low boiling gas mixtures near normal temperature. In this process, absorption-membrane-adsorption is integrated by suspending suitable porous ZIF material in suitable solvent and forming selectively permeable liquid membrane around ZIF particles. Green solvents like water and glycol were used to form ZIF-8 slurry and tune the permeability of liquid membrane surrounding ZIF-8 particles. We found glycol molecules form tighter membrane while water molecules form looser membrane because of the hydrophobicity of ZIF-8. When using mixing solvents composed of glycol and water, the permeability of liquid membrane becomes tunable. It is shown that ZIF-8/water slurry always manifests remarkable higher separation selectivity than solid ZIF-8 and it could be tuned to further enhance the capture of light hydrocarbons by adding suitable quantity of glycol to water. Because of its lower viscosity and higher sorption/desorption rate, tunable ZIF-8/water-glycol slurry could be readily used as liquid absorbent to separate different kinds of low boiling gas mixtures by applying a multistage separation process in one traditional absorption tower, especially for the capture of light hydrocarbons.

  10. Molecular dynamics investigation of separation of hydrogen sulfide from acidic gas mixtures inside metal-doped graphite micropores.

    PubMed

    Huang, Pei-Hsing

    2015-09-21

    The separation of poisonous compounds from various process fluids has long been highly intractable, motivating the present study on the dynamic separation of H2S in acidic-gas-mixture-filled micropores. The molecular dynamics approach, coupled with the isothermal-isochoric ensemble, was used to model the molecular interactions and adsorption of H2S/CO2/CO/H2O mixtures inside metal-doped graphite slits. Due to the difference in the adsorption characteristics between the two distinct adsorbent materials, the metal dopant in the graphitic micropores leads to competitive adsorption, i.e. the Au and graphite walls compete to capture free adsorbates. The effects of competitive adsorption, coupled with changes in the gas temperature, concentration, constituent ratio and slit width on the constituent separation of mixtures were systematically studied. The molecule-wall binding energies calculated in this work (those of H2S, H2O and CO on Au walls and those of H2O, CO and CO2 on graphite walls) show good agreement with those obtained using density functional theory (DFT) and experimental results. The z-directional self-diffusivities (Dz) for adsorbates inside the slit ranged from 10(-9) to 10(-7) m(2) s(-1) as the temperature was increased from 10 to 500 K. The values are comparable with those for a typical microporous fluid (10(-8)-10(-9) m(2) s(-1) in a condensed phase and 10(-6)-10(-7) m(2) s(-1) in the gaseous state). The formation of H-bonding networks and hydrates of H2S is disadvantageous for the separation of mixtures. The results indicate that H2S can be efficiently separated from acidic gas mixtures onto the Au(111) surface by (i) reducing the mole fraction of H2S and H2O in the mixtures, (ii) raising the gas temperature to the high temperature limit (≥400 K), and (iii) lowering the slit width to below the threshold dimension (≤23.26 Å).

  11. Estimating the gas transfer velocity: a prerequisite for more accurate and higher resolution GHG fluxes (lower Aare River, Switzerland)

    NASA Astrophysics Data System (ADS)

    Sollberger, S.; Perez, K.; Schubert, C. J.; Eugster, W.; Wehrli, B.; Del Sontro, T.

    2013-12-01

    Currently, carbon dioxide (CO2) and methane (CH4) emissions from lakes, reservoirs and rivers are readily investigated due to the global warming potential of those gases and the role these inland waters play in the carbon cycle. However, there is a lack of high spatiotemporally-resolved emission estimates, and how to accurately assess the gas transfer velocity (K) remains controversial. In anthropogenically-impacted systems where run-of-river reservoirs disrupt the flow of sediments by increasing the erosion and load accumulation patterns, the resulting production of carbonic greenhouse gases (GH-C) is likely to be enhanced. The GH-C flux is thus counteracting the terrestrial carbon sink in these environments that act as net carbon emitters. The aim of this project was to determine the GH-C emissions from a medium-sized river heavily impacted by several impoundments and channelization through a densely-populated region of Switzerland. Estimating gas emission from rivers is not trivial and recently several models have been put forth to do so; therefore a second goal of this project was to compare the river emission models available with direct measurements. Finally, we further validated the modeled fluxes by using a combined approach with water sampling, chamber measurements, and highly temporal GH-C monitoring using an equilibrator. We conducted monthly surveys along the 120 km of the lower Aare River where we sampled for dissolved CH4 (';manual' sampling) at a 5-km sampling resolution, and measured gas emissions directly with chambers over a 35 km section. We calculated fluxes (F) via the boundary layer equation (F=K×(Cw-Ceq)) that uses the water-air GH-C concentration (C) gradient (Cw-Ceq) and K, which is the most sensitive parameter. K was estimated using 11 different models found in the literature with varying dependencies on: river hydrology (n=7), wind (2), heat exchange (1), and river width (1). We found that chamber fluxes were always higher than boundary

  12. Gas emissions and engine behavior when gasoline-alcohol mixtures are used.

    PubMed

    Arapatsakos, C I; Karkanis, A N; Sparis, P D

    2003-09-01

    This paper deals with the use of gasoline-methanol and gasoline-ethanol mixtures in a small four-stroke engine of internal combustion that is used for the movement of a small alternative generator. It was observed that CO and HC emissions decrease compared to gasoline when the percentage of methanol, ethanol in the fuel was increased, under different load conditions (without load conditions and under full electrical load conditions). The use of gasoline-methanol mixtures showed a higher decrease of emissions. When the mixtures of gasoline-70%methanol and gasoline-90%ethanol and 100%ethanol for which the engine malfunctioned, the rpm of the engine were not constant and the emissions were increased. It is also important that (with the existing regulation of the fuel/air ratio that refers to gasoline) the engine functioned for the case of gasoline-methanol mixtures up to a concentration of -70%methanol mixture, while for the case of gasoline-ethanol mixtures until the use of 100%ethanol. Furthermore, during the use of the mixtures of gasoline-methanol and gasoline-ethanol there was a small increase of fuel consumption when the percentage of the methanol or ethanol in the fuel was increased.

  13. ANALYTICAL METHOD FOR MEASURING TOTAL PROTIUM AND TOTAL DEUTERIUM IN A GAS MIXTURE CONTAINING H2, D2,AND HD VIA GAS CHAROMATOGRAPHY

    SciTech Connect

    Sessions, H

    2007-08-07

    The most common analytical method of identifying and quantifying non-radioactive isotopic species of hydrogen is mass spectrometry. A low mass, high resolution mass spectrometer with adequate sensitivity and stability to identify and quantify hydrogen isotopes in the low ppm range is an expensive, complex instrument. A new analytical technique has been developed that measures both total protium (H) and total deuterium (D) in a gas mixture containing H{sub 2}, D{sub 2}, and HD using an inexpensive micro gas chromatograph (GC) with two molecular sieve columns. One column uses D{sub 2} as the carrier gas and the other uses H{sub 2} as the carrier gas. Laboratory tests have shown that when used in this configuration the GC can measure both total protium and total deuterium each with a detection and quantification limit of less than 20 ppm.

  14. Final report on EURAMET.QM-S10/1274: supplementary comparison of preparative capabilities for automotive gas mixtures

    NASA Astrophysics Data System (ADS)

    Val'ková, M.; Ďurišová, Z.; Szilágyi, Z. N.; Büki, T.; Fükű, J.

    2016-01-01

    This bilateral supplementary preparative comparison involves standard gas mixtures of automotive gas containing carbon monoxide, carbon dioxide and propane in nitrogen. Two laboratories (SMU, Slovakia and MKEH, Hungary) participated in this supplementary comparison. SMU was the coordinating laboratory, responsible for collecting and reporting measurement results. The participants have established facilities for automotive gas gravimetric preparation and analysis. The agreement of the results in this supplementary comparison is good. All the results with their reported uncertainties are in agreement with the reference values for the participants. SMU participated and obtained good results in the previous preparative comparison organised within EURAMET in this field. Both laboratories have existing claims for their Calibration and Measurement Capabilities (CMCs) for automotive gas mixtures. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  15. Parameters, limits, attenuation, and suppression of detonation in mixtures of an explosive gas with chemically inert microparticles

    NASA Astrophysics Data System (ADS)

    Fedorov, A. V.; Fomin, P. A.; Tropin, D. A.; Chen, Z.-R.

    2012-03-01

    Chapman-Jouguet parameters and the cell size of a detonation wave in mixtures of an explosive gas with chemically inert particles have been calculated. The algorithm of calculation of the minimum mass and characteristic dimension of a particle cloud ensuring successful suppression of detonation in the gas has been proposed. The calculation results are in good agreement with the available experimental data. The influence of the initial composition of the gas on the efficiency of suppression of the detonation wave has been analyzed. The issue of the dependence of the concentration limits of detonation on the mass fraction of particles has been investigated. It has been established that the increase in the concentration of the condensed phase leads to a narrowing of the existence domain of detonation and that the propagation of the detonation wave becomes impossible when the concentration of the particles is fairly high.

  16. Optical and electrical analyses of DC positive corona discharge in N2/O2/CO2 gas mixtures

    NASA Astrophysics Data System (ADS)

    Merbahi, N.; Abahazem, A.; Dubois, D.; Eichwald, O.; Yousfi, M.

    2008-04-01

    This paper presents an experimental analysis of the electrical and optical behaviour of positive point-plane corona discharges. The measurements of the instantaneous corona current and the current-voltage characteristics are used with the imagery analyses (CCD and streak camera) to determine the streamer properties such as the streamer morphology and velocity with the primary and secondary streamer developments. These analyses are performed first in synthetic air as a function of operating parameters such the applied voltage. Then the effect of gas mixtures (several proportions of N{2}, O{2} with or without CO{2}) is analysed. When the gas concentration is varied the discharge morphology, the shape and amplitude of the corona current are significantly affected due to the variation of the gas electronegativity following its composition and concentration.

  17. Effect of hydrogen ratio on plasma parameters of N{sub 2}-H{sub 2} gas mixture glow discharge

    SciTech Connect

    El-Brulsy, R. A.; Abd Al-Halim, M. A.; Abu-Hashem, A.; Rashed, U. M.; Hassouba, M. A.

    2012-05-15

    A dc plane glow discharge in a nitrogen-hydrogen (N{sub 2}-H{sub 2}) gas mixture has been operated at discharge currents of 10 and 20 mA. The electron energy distribution function (EEDF) at different hydrogen concentrations is measured. A Maxwellian EEDF is found in the positive column region, while in both cathode fall and negative glow regions, a non-Maxwellian one is observed. Langmuir electric probes are used at different axial positions, gas pressures, and hydrogen concentrations to measure the electron temperature and plasma density. The electron temperature is found to increase with increasing H{sub 2} concentration and decrease with increasing both the axial distance from the cathode and the mixture pressure. At first, with increasing distance from the cathode, the ion density decreases, while the electron density increases; then, as the anode is further approached, they remain nearly constant. At different H{sub 2} concentrations, the electron and ion densities decrease with increasing the mixture pressure. Both the electron and ion densities slightly decrease with increasing H{sub 2} concentration.

  18. On a modified Monte-Carlo method and variable soft sphere model for rarefied binary gas mixture flow simulation

    NASA Astrophysics Data System (ADS)

    Nourazar, S. S.; Jahangiri, P.; Aboutalebi, A.; Ganjaei, A. A.; Nourazar, M.; Khadem, J.

    2011-06-01

    The effect of new terms in the improved algorithm, the modified direct simulation Monte-Carlo (MDSMC) method, is investigated by simulating a rarefied binary gas mixture flow inside a rotating cylinder. Dalton law for the partial pressures contributed by each species of the binary gas mixture is incorporated into our simulation using the MDSMC method and the direct simulation Monte-Carlo (DSMC) method. Moreover, the effect of the exponent of the cosine of deflection angle (α) in the inter-molecular collision models, the variable soft sphere (VSS) and the variable hard sphere (VHS), is investigated in our simulation. The improvement of the results of simulation is pronounced using the MDSMC method when compared with the results of the DSMC method. The results of simulation using the VSS model show some improvements on the result of simulation for the mixture temperature at radial distances close to the cylinder wall where the temperature reaches the maximum value when compared with the results using the VHS model.

  19. Laser flash-photolysis and gas discharge in N2O-containing mixture: kinetic mechanism

    NASA Astrophysics Data System (ADS)

    Kosarev, Ilya; Popov, Nikolay; Starikovskaia, Svetlana; Starikovskiy, Andrey; mipt Team

    2011-10-01

    The paper is devoted to further experimental and theoretical analysis of ignition by ArF laser flash-photolysis and nanosecond discharge in N2O-containing mixture has been done. Additional experiments have been made to assure that laser emission is distributed uniformly throughout the cross-section. The series of experiments was proposed and carried out to check validity of O(1D) determination in experiments on plasma assisted ignition initiated by flash-photolysis. In these experiments, ozone density in the given mixture (mixture composition and kinetics has been preliminary analyzed) was measured using UV light absorption in Hartley band. Good coincidence between experimental data and results of calculations have been obtained Temporal behavior of energy input, electric field and electric current has been measured and analyzed. These data are considered as initial conditions for numerical modeling of the discharge in O2:N2O:H2:Ar = 0.3:1:3:5 mixture. Ion-molecular reactions and reactions of active species production in Ar:H2:O2:N2O mixture were analyzed. The set of reactions to describe chemical transformation in the system due to the discharge action has been selected.

  20. Combustion of hydrogen-based mixtures in gas-fueled reciprocating engines

    NASA Astrophysics Data System (ADS)

    Smygalina, A. E.; Zaitchenko, V. M.; Ivanov, M. F.; Kiverin, A. D.

    2015-12-01

    The research is devoted to the possibility for application of hydrogen accumulated from renewable energy sources as a fuel for a reciprocating engine, which serves as an electrical generator drive. Hydrogen combustion in the chamber of a reciprocating engine, as a rule, occurs in a detonation mode. In order to obtain less hard modes, the present research proposes the usage of steam additions to hydrogen-air mixture or lean hydrogen-air mixtures. Mathematical simulation is used for investigation of combustion of mentioned mixtures in the combustion chamber of a reciprocating engine with a spark-plug ignition. The comparison of the usage of hydrogen-steam-air mixtures and lean hydrogen-air mixtures as fuels is given. The dependence of arising combustion modes and its quantitative characteristics on hydrogen content in combustible composition is investigated. The analysis of optimal combustion is presented, which is based on the consideration of two parameters: peak pressure in one cycle and the crankshaft angle corresponding to the achievement of the peak pressure.

  1. Dynamic mean field theory for lattice gas models of fluid mixtures confined in mesoporous materials.

    PubMed

    Edison, J R; Monson, P A

    2013-11-12

    We present the extension of dynamic mean field theory (DMFT) for fluids in porous materials (Monson, P. A. J. Chem. Phys. 2008, 128, 084701) to the case of mixtures. The theory can be used to describe the relaxation processes in the approach to equilibrium or metastable equilibrium states for fluids in pores after a change in the bulk pressure or composition. It is especially useful for studying systems where there are capillary condensation or evaporation transitions. Nucleation processes associated with these transitions are emergent features of the theory and can be visualized via the time dependence of the density distribution and composition distribution in the system. For mixtures an important component of the dynamics is relaxation of the composition distribution in the system, especially in the neighborhood of vapor-liquid interfaces. We consider two different types of mixtures, modeling hydrocarbon adsorption in carbon-like slit pores. We first present results on bulk phase equilibria of the mixtures and then the equilibrium (stable/metastable) behavior of these mixtures in a finite slit pore and an inkbottle pore. We then use DMFT to describe the evolution of the density and composition in the pore in the approach to equilibrium after changing the state of the bulk fluid via composition or pressure changes. PMID:24102541

  2. Optical characteristics and parameters of gas-discharge plasma in a mixture of mercury dibromide vapor with neon

    SciTech Connect

    Malinina, A. A. Malinin, A. N.

    2013-12-15

    Results are presented from studies of the optical characteristics and parameters of plasma of a dielectric barrier discharge in a mixture of mercury dibromide vapor with neon—the working medium of a non-coaxial exciplex gas-discharge emitter. The electron energy distribution function, the transport characteristics, the specific power losses for electron processes, the electron density and temperature, and the rate constants for the processes of elastic and inelastic electron scattering by the working mixture components are determined as functions of the reduced electric field. The rate constant of the process leading to the formation of exciplex mercury monobromide molecules is found to be 1.6 × 10{sup −14} m{sup 3}/s for a reduced electric field of E/N = 15 Td, at which the maximum emission intensity in the blue-green spectral region (λ{sub max} = 502 nm) was observed in this experiment.

  3. Optical Characteristics of a Gas Discharge Plasma Based on a Mixture of Mercury Diiodide Vapor, Nitrogen, and Helium

    NASA Astrophysics Data System (ADS)

    Malinina, A. A.; Malinin, A. N.

    2016-09-01

    The results of studies of spectral, temporal, and energy characteristics of radiation in a gas discharge plasma based on a mixture of mercury diiodide vapor with helium and nitrogen in the spectral range of 350-800 nm are presented. Plasma was produced by a barrier discharge in a device with a cylindrical aperture. The electrodes 0.2 m in length were placed at a distance of 0.015 m. The amplitude of the pump pulses, their duration, and frequency were equal to 20-30 kV, 150 ns, and 1-20 kHz, respectively. Radiation of mercury monoiodide exciplex molecules was revealed in the visible spectra region. Dependences of the plasma optical characteristics on the partial pressures of the mixture components were established.

  4. Two-fluid dust and gas mixtures in smoothed particle hydrodynamics II: an improved semi-implicit approach

    NASA Astrophysics Data System (ADS)

    Lorén-Aguilar, Pablo; Bate, Matthew R.

    2015-12-01

    We present an improved version of the Lorén-Aguilar & Bate method to integrate the two-fluid dust/gas equations that correctly captures the limiting velocity of small grains in the presence of net differences (excluding the drag force) between the accelerations of the dust and the gas. A series of accelerated DUSTYBOX tests and a simulation of dust-settling in a protoplanetary disc are performed comparing the performance of the new and old methods. The modified method can accurately capture the correct limiting velocity while preserving all the conservation properties of the original method.

  5. Realization of a Strongly Interacting Bose-Fermi Mixture from a Two-Component Fermi Gas

    SciTech Connect

    Shin Yongil; Schirotzek, Andre; Schunck, Christian H.; Ketterle, Wolfgang

    2008-08-15

    We show the emergence of a strongly interacting Bose-Fermi mixture from a two-component Fermi mixture with population imbalance. By analyzing in situ density profiles of {sup 6}Li atoms in the BCS-BEC crossover regime, we identify a critical interaction strength, beyond which all minority atoms pair up with majority atoms and form a Bose condensate. This is the regime where the system can be effectively described as a boson-fermion mixture. We determine the dimer-fermion and dimer-dimer scattering lengths and beyond-mean-field contributions. Our study realizes a gedanken experiment of bosons immersed in a Fermi sea of one of their constituents, revealing the composite nature of the bosons.

  6. Effect of flow velocity and temperature on ignition characteristics in laser ignition of natural gas and air mixtures

    NASA Astrophysics Data System (ADS)

    Griffiths, J.; Riley, M. J. W.; Borman, A.; Dowding, C.; Kirk, A.; Bickerton, R.

    2015-03-01

    Laser induced spark ignition offers the potential for greater reliability and consistency in ignition of lean air/fuel mixtures. This increased reliability is essential for the application of gas turbines as primary or secondary reserve energy sources in smart grid systems, enabling the integration of renewable energy sources whose output is prone to fluctuation over time. This work details a study into the effect of flow velocity and temperature on minimum ignition energies in laser-induced spark ignition in an atmospheric combustion test rig, representative of a sub 15 MW industrial gas turbine (Siemens Industrial Turbomachinery Ltd., Lincoln, UK). Determination of minimum ignition energies required for a range of temperatures and flow velocities is essential for establishing an operating window in which laser-induced spark ignition can operate under realistic, engine-like start conditions. Ignition of a natural gas and air mixture at atmospheric pressure was conducted using a laser ignition system utilizing a Q-switched Nd:YAG laser source operating at 532 nm wavelength and 4 ns pulse length. Analysis of the influence of flow velocity and temperature on ignition characteristics is presented in terms of required photon flux density, a useful parameter to consider during the development laser ignition systems.

  7. Selective Adsorption of CO2 from Light Gas Mixtures Using a Structurally Dynamic Porous Coordination Polymer**

    SciTech Connect

    Kristi L. Kauffman, Jeffrey T. Culp, Andrew J. Allen, Laura Espinal, Winnie Wong-Ng, Thomas D. Brown, Angela Goodman, Mark P. Bernardo, Russel J. Pancoast, Danielle Chirdon, Christopher Matranga*

    2010-01-01

    The selective adsorption of CO{sub 2} from mixtures with N{sub 2}, CH{sub 4}, and N{sub 2}O in a dynamic porous coordination polymer (see monomer structure) was evaluated by ATR-FTIR spectroscopy, GC, and SANS. All three techniques indicate highly selective adsorption of CO{sub 2} from CO{sub 2}/CH{sub 4} and CO{sub 2}/N{sub 2} mixtures at 30 C, with no selectivity observed for the CO{sub 2}/N{sub 2}O system.

  8. Endocrine-Disrupting Chemicals and Oil and Natural Gas Operations: Potential Environmental Contamination and Recommendations to Assess Complex Environmental Mixtures

    PubMed Central

    Kassotis, Christopher D.; Tillitt, Donald E.; Lin, Chung-Ho; McElroy, Jane A.; Nagel, Susan C.

    2015-01-01

    Background Hydraulic fracturing technologies, developed over the last 65 years, have only recently been combined with horizontal drilling to unlock oil and gas reserves previously deemed inaccessible. Although these technologies have dramatically increased domestic oil and natural gas production, they have also raised concerns for the potential contamination of local water supplies with the approximately 1,000 chemicals that are used throughout the process, including many known or suspected endocrine-disrupting chemicals. Objectives We discuss the need for an endocrine component to health assessments for drilling-dense regions in the context of hormonal and antihormonal activities for chemicals used. Methods We discuss the literature on a) surface and groundwater contamination by oil and gas extraction operations, and b) potential human exposure, particularly in the context of the total hormonal and antihormonal activities present in surface and groundwater from natural and anthropogenic sources; we also discuss initial analytical results and critical knowledge gaps. Discussion In light of the potential for environmental release of oil and gas chemicals that can disrupt hormone receptor systems, we recommend methods for assessing complex hormonally active environmental mixtures. Conclusions We describe a need for an endocrine-centric component for overall health assessments and provide information supporting the idea that using such a component will help explain reported adverse health trends as well as help develop recommendations for environmental impact assessments and monitoring programs. Citation Kassotis CD, Tillitt DE, Lin CH, McElroy JA, Nagel SC. 2016. Endocrine-disrupting chemicals and oil and natural gas operations: potential environmental contamination and recommendations to assess complex environmental mixtures. Environ Health Perspect 124:256–264; http://dx.doi.org/10.1289/ehp.1409535 PMID:26311476

  9. An accurate measurement of the baryonic Tully-Fisher relation with heavily gas-dominated ALFALFA galaxies

    NASA Astrophysics Data System (ADS)

    Papastergis, E.; Adams, E. A. K.; van der Hulst, J. M.

    2016-09-01

    We use a sample of 97 galaxies selected from the Arecibo legacy fast ALFA (ALFALFA) 21 cm survey to make an accurate measurement of the baryonic Tully-Fisher relation (BTFR). These galaxies are specifically selected to be heavily gas-dominated (Mgas/M∗ ≳ 2.7) and to be oriented edge-on. The former property ensures that the error on the galactic baryonic mass is small, despite the large systematic uncertainty involved in galactic stellar mass estimates. The latter property means that rotational velocities can be derived directly from the width of the 21 cm emission line, without any need for inclination corrections. We measure a slope for the linewidth-based BTFR of α = 3.75 ± 0.11, a value that is somewhat steeper than (but in broad agreement with) previous literature results. The relation is remarkably tight, with almost all galaxies being located within a perpendicular distance of ± 0.1 dex from the best fit line. The low observational error budget for our sample enables us to establish that, despite its tightness, the measured linewidth-based BTFR has some small (i.e., non-zero) intrinsic scatter. We furthermore find a systematic difference in the BTFR of galaxies with "double-horned" 21 cm line profiles - suggestive of flat outer galactic rotation curves - and those with "peaked" profiles - suggestive of rising rotation curves. When we restrict our sample of galaxies to objects in the former category, we measure a slightly steeper slope of α = 4.13 ± 0.15. Overall, the high-accuracy measurement of the BTFR presented in this article is intended as a reliable observational benchmark against which to test theoretical expectations. Here we consider a representative set of semi-analytic models and hydrodynamic simulations in the lambda cold dark matter (ΛCDM) context, as well as modified Newtonian dynamics (MOND). In the near future, interferometric follow-up observations of several sample members will enable us to further refine the BTFR measurement, and

  10. Sputtering Yields for Mixtures of Organic Materials Using Argon Gas Cluster Ions.

    PubMed

    Seah, M P; Havelund, R; Shard, A G; Gilmore, I S

    2015-10-22

    The sputtering yield volumes of binary mixtures of Irganox 1010 with either Irganox 1098 or Fmoc-pentafluoro-L-phenylalanine (FMOC) have been measured for 5 keV Ar2000(+) ions incident at 45° to the surface normal. The sputtering yields are determined from the doses to sputter through various compositions of 100 nm thick, intimately mixed, layers. Because of matrix effects, the profiles for secondary ions are distorted, and profile shifts in depth of 15 nm are observed leading to errors above 20% in the deduced sputtering yield. Secondary ions are selected to avoid this. The sputtering yield volumes for the mixtures are shown to be lower than those deduced from a linear interpolation from the pure materials. This is shown to be consistent with a simple model involving the changing energy absorbed for the sputtering of intimate mixtures. Evidence to support this comes from the secondary ion data for pairs of the different molecules. Both binary mixtures behave similarly, but matrix effects are stronger for the Irganox 1010/FMOC system.

  11. On the Equipartition of Kinetic Energy in an Ideal Gas Mixture

    ERIC Educational Resources Information Center

    Peliti, L.

    2007-01-01

    A refinement of an argument due to Maxwell for the equipartition of translational kinetic energy in a mixture of ideal gases with different masses is proposed. The argument is elementary, yet it may work as an illustration of the role of symmetry and independence postulates in kinetic theory. (Contains 1 figure.)

  12. Heat/Fluid Flow Performance of Binary Gas Mixtures Formed with Helium Across Parallel-Plate Channels

    NASA Astrophysics Data System (ADS)

    Campo, Antonio; Manchu, Sreedhar

    2006-11-01

    The present study examines the trade-off between heat transfer enhancement and pressure drop increments caused by the flow of laminar binary gases in parallel-plate channels. Helium is the primary gas and carbon dioxide, methane, nitrogen, oxygen and xenon are the secondary gases. From fluid physics, two thermophysical properties: viscosity and density affect the gas flow, whereas four thermophysical properties: viscosity, density, thermal conductivity, and heat capacity at constant pressure influence the forced convection. From physical-chemistry, the collection of four thermophysical properties depends on temperature, pressure and molar gas composition. The simultaneous development of laminar velocity and temperature of each binary gas mixture is predicted using the finite volume method for two Reynolds numbers based on hydraulic diameter, i.e., 1000 and 2000. The two target parameters are the total heat transfer or mean convection coefficient and the pressure drop. The beneficial connectedness of the two target parameters changing with the molar gas composition is reported in terms of a proper figure-of-merit, the heat/fluid flow performance parameter for the two Reynolds numbers.

  13. Rapid and Accurate Analysis of an X-Ray Fluorescence Microscopy Data Set through Gaussian Mixture-Based Soft Clustering Methods

    PubMed Central

    Ward, Jesse; Marvin, Rebecca; O'Halloran, Thomas; Jacobsen, Chris; Vogt, Stefan

    2013-01-01

    X-ray fluorescence (XRF) microscopy is an important tool for studying trace metals in biology, enabling simultaneous detection of multiple elements of interest and allowing quantification of metals in organelles without the need for subcellular fractionation. Currently, analysis of XRF images is often done using manually defined regions of interest (ROIs). However, since advances in synchrotron instrumentation have enabled the collection of very large data sets encompassing hundreds of cells, manual approaches are becoming increasingly impractical. We describe here the use of soft clustering to identify cell ROIs based on elemental contents, using data collected over a sample of the malaria parasite Plasmodium falciparum as a test case. Soft clustering was able to successfully classify regions in infected erythrocytes as “parasite,”“food vacuole,”“host,” or “background.” In contrast, hard clustering using the k-means algorithm was found to have difficulty in distinguishing cells from background. While initial tests showed convergence on two or three distinct solutions in 60% of the cells studied, subsequent modifications to the clustering routine improved results to yield 100% consistency in image segmentation. Data extracted using soft cluster ROIs were found to be as accurate as data extracted using manually defined ROIs, and analysis time was considerably improved. PMID:23924688

  14. Sputter process with time-variant reactive gas mixture for the deposition of optical multilayer and gradient layer systems

    NASA Astrophysics Data System (ADS)

    Bartzsch, H.; Weber, J.; Lau, K.; Glöß, D.; Frach, P.

    2008-09-01

    Magnetron sputtering of a silicon target in a time-variant mixture of the reactive gases oxygen and nitrogen allows the deposition of optical multilayer and gradient layer systems of silicon oxinitride at one stationary sputtering station. In this paper the processes within the sputter discharge and the properties of the growing film during the change of the reactive gas composition are investigated using optical in-situ monitoring, optical plasma emission spectroscopy and plasma impedance monitoring. A time delay between the change to the reactive gas composition and the resulting change to the film composition was observed. The time delay is longer for the transition from oxide to nitride deposition then vice versa. This asymmetry is attributed to the different affinity of nitrogen and oxygen to the silicon target. Examples of deposited antireflective coatings as well as rugate filters based on silicon oxinitride multilayer and gradient layer designs are given.

  15. Biological treatment of waste gas containing mixture of monochlorobenzene (MCB) and benzene in a bench scale biofilter.

    PubMed

    Pandey, R A; Joshi, P R; Mudliar, S N; Deshmukh, S C

    2010-07-01

    The paper outlines treatment of waste gas containing monochlorobenzene (MCB) and benzene in a mixture using biofilter packed with compost and woodchips seeded with Acinetobacter calcoaceticus. The biofilter could treat waste gas containing MCB and benzene effectively with an efficiency of (99+/-5%) and (97+/-6%) at optimal empty bed contact time (EBCT) of 3 min with a loading of 57 g/m(3)/h of MCB and 2g/m(3)/h of benzene. At optimum loading of MCB and benzene, the biofilter showed total bacterial count of 13 x 10(5)CFU/g of compost, while the MCB and benzene degrading bacterial count was 71 x 10(4)CFU/g and 5 x 10(4)CFU/g compost respectively. The experimental removal efficiency of MCB and benzene were in good agreement with the model predicted value. PMID:20202831

  16. A numerical program for steady-state flow of magma-gas mixtures through vertical eruptive conduits

    USGS Publications Warehouse

    Mastin, Larry G.; Ghiorso, Mark S.

    2000-01-01

    This report presents a model that calculates flow properties (pressure, vesicularity, and some 35 other parameters) as a function of vertical position within a volcanic conduit during a steady-state eruption. The model idealizes the magma-gas mixture as a single homogeneousfluid and calculates gas exsolution under the assumption of equilibrium conditions. These are the same assumptions on which classic conduit models (e.g. Wilson and Head, 1981) have been based. They are most appropriate when applied to eruptions of rapidly ascending magma (basaltic lava-fountain eruptions, and Plinian or sub-Plinian eruptions of intermediate or silicic magmas) that contains abundant nucleation sites (microlites, for example) for bubble growth.

  17. Quantitative analysis of CO-humidity gas mixtures with self-heated nanowires operated in pulsed mode

    NASA Astrophysics Data System (ADS)

    Prades, J. D.; Hernández-Ramírez, F.; Fischer, T.; Hoffmann, M.; Müller, R.; López, N.; Mathur, S.; Morante, J. R.

    2010-12-01

    Self-heating effect in individual metal oxide nanowires can be used to activate their response to gases with power consumptions below tenths of microwatts. The thermal response time of these devices is extremely fast (a few milliseconds) and it makes it possible to observe the kinetics of the interactions between the gas molecules and the metal oxide. In this work we demonstrate that such effects enable an experimental methodology to improve the selectivity of metal oxide-based sensors based on the analysis of their fast response dynamics. Specifically, this work jointly analyzes the magnitude and response time of SnO2 nanowire-based sensors to carbon monoxide (CO) and humidity (H2O) mixtures, proving that a quantitative analysis of CO-H2O gas blends can be achieved by modulating their work temperature through the self-heating effect.

  18. Selective denitrification of flue gas by O3 and ethanol mixtures in a duct: Investigation of processes and mechanisms.

    PubMed

    Ding, Jie; Cai, Heruijing; Zhong, Qin; Lin, Jiandong; Xiao, Junjun; Zhang, Shule; Fan, Maohong

    2016-07-01

    A novel selective denitrification process, referred as O3-ethanol oxidation method, was developed by injecting O3 and ethanol mixtures into the simulated flue gas duct. The organic radicals, generated through the ethanol oxidation by O3, can oxidize NO into NO2, and finally into important industrial raw, namely, nitrate organics or aqueous nitrate acids. The residual ethanol in the tail can be recycled. The CO3(2-), HCO3(-) and SO2 in the flue gas hardly exhibit any effect on the NOX removal. Compared to the conventional O3 oxidation method, the present method shows higher selective oxidation of NO, higher NO(X) removal and less O3 consumption as well as proves lower initial investment and operating costs with more compact equipment. PMID:26989982

  19. Improved Resolution of Hydrocarbon Structures and Constitutional Isomers in Complex Mixtures Using Gas Chromatography-Vacuum Ultraviolet-Mass Spectrometry

    SciTech Connect

    Isaacman, Gabriel; Wilson, Kevin R.; Chan, Arthur W. H.; Worton, David R.; Kimmel, Joel R.; Nah, Theodora; Hohaus, Thorsten; Gonin, Marc; Kroll, Jesse H.; Worsnop, Douglas R.; Goldstein, Allen H.

    2012-01-30

    Understanding the composition of complex hydrocarbon mixtures is important for environmental studies in a variety of fields, but many prevalent compounds cannot be confidently identified using traditional gas chromatography/mass spectrometry (GC/MS) techniques. In this study, we use vacuum-ultraviolet (VUV) ionization to elucidate the structures of a traditionally “unresolved complex mixture” by separating components by GC retention time, tR, and mass-to-charge ratio, m/z, which are used to determine carbon number, NC, and the number of rings and double bonds, NDBE. Constitutional isomers are resolved on the basis of tR, enabling the most complete quantitative analysis to date of structural isomers in an environmentally relevant hydrocarbon mixture. Unknown compounds are classified in this work by carbon number, degree of saturation, presence of rings, and degree of branching, providing structural constraints. The capabilities of this analysis are explored using diesel fuel, in which constitutional isomer distribution patterns are shown to be reproducible between carbon numbers and follow predictable rules. Nearly half of the aliphatic hydrocarbon mass is shown to be branched, suggesting branching is more important in diesel fuel than previously shown. Lastly, the classification of unknown hydrocarbons and the resolution of constitutional isomers significantly improves resolution capabilities for any complex hydrocarbon mixture.

  20. Equilibrium and Transport Properties of Gas Mixtures at Low Density: Eleven Polyatomic Gases and Five Noble Gases

    NASA Astrophysics Data System (ADS)

    Bzowski, J.; Kestin, J.; Mason, E. A.; Uribe, F. J.

    1990-09-01

    This paper uses results from statistical-mechanical theory, applied through a combination of an extended principle of corresponding states with some knowledge of intermolecular potentials, to the calculation of the transport and equilibrium properties of gas mixtures at low density. The gases involved are: N2, O2, NO, CO, CO2, N2O, CH4, CF4, SF6, C2H4, C2H6, and He, Ar, Ne, Kr, Xe. The properties included are: second virial coefficient, viscosity, diffusion, and thermal diffusion, but not thermal conductivity. The calculations are internally, thermodynamically consistent and the resulting algorithms, which are fully programmable, operate in an entirely predictive mode by means of validated combination rules. This paper is a sequel to one on the five noble gases and all their possible mixtures and a second on the above eleven polyatomic gases. The paper contains ten tables (mainly intended for the checking of computer codes) and 201 graphs of deviation and comparison plots. An additional 98 tables have been deposited with the Physics Auxiliary Publication Service (PAPS) of the AIP. The algorithms presented in this paper, together with those mentioned above, make it possible to program calculations for a wide range of low-density equilibrium and transport properties of 16 gases and of all possible multicomponent mixtures formed with them, for a total of 65,535 systems. For each system, the program would cover the full range of compositions.

  1. Reacting gas mixtures in the state-to-state approach: The chemical reaction rates

    SciTech Connect

    Kustova, Elena V.; Kremer, Gilberto M.

    2014-12-09

    In this work chemically reacting mixtures of viscous flows are analyzed within the framework of Boltzmann equation. By applying a modified Chapman-Enskog method to the system of Boltzmann equations general expressions for the rates of chemical reactions and vibrational energy transitions are determined as functions of two thermodynamic forces: the velocity divergence and the affinity. As an application chemically reacting mixtures of N{sub 2} across a shock wave are studied, where the first lowest vibrational states are taken into account. Here we consider only the contributions from the first four single quantum vibrational-translational energy transitions. It is shown that the contribution to the chemical reaction rate related to the affinity is much larger than that of the velocity divergence.

  2. Combining Yb and Li: Rapid Quantum Degenerate Gas Production and Interacting Mixtures

    NASA Astrophysics Data System (ADS)

    Green, Alaina; Roy, Richard; Bowler, Ryan; Gupta, Subhadeep

    2016-05-01

    We detail a readily adaptable method for optimizing evaporative cooling efficiency in optical dipole traps (ODTs), reducing the production time of quantum degenerate gases. Utilizing the time-averaged 'painting' potential of a rapidly moving laser beam, we dynamically shape the trap over the course of evaporation to produce 174 Yb Bose-Einstein condensates of (0.5-1.0) × 105 atoms in (1.6-1.8) seconds. We also report on interaction studies in the quantum degenerate Bose-Fermi 174 Yb-6 Li mixture in the BEC-BCS crossover. Additionally, we present work on photoassociation spectroscopy on 6 Li-Yb mixtures and the production of YbLi* molecules in a dual magneto-optical trap, a first step toward coherent production of ultracold 2 Σ molecules.

  3. Accurately Modelling the Absorption of a Mixture of Gases at Low- to Medium-resolution in Exoplanetary and Brown Dwarf Atmospheric Radiative Transfer Calculations

    NASA Astrophysics Data System (ADS)

    Garland, Ryan; Irwin, Patrick Gerard Joseph

    2016-10-01

    Exoplanetary and brown dwarf atmospheres are extremely diverse environments ranging over many different temperatures, pressures, and compositions. In order to model the spectra produced by the these objects, a commonplace approach in exoplanetary science is to use cross-sections of individual gases to quickly calculate the atmospheric opacities. However, when combining multiple gases with non-monochromatic absorption coefficients, the multiplication property of transmission does not hold. The resulting spectra are hence unreliable. Extensive work was carried out on Solar System radiative transfer models to find an efficient alternative to line-by-line calculations of opacity which was more accurate than combining cross-sections, resulting in many band models and the correlated-k method. Here we illustrate the effect of using cross-sections to model typical brown dwarf and exoplanetary atmospheres (e.g. HD189733b), and compare them to the spectra calculated using the correlated-k method. We verify our correlated-k method using a line-by-line model. For the same objects, we also present the effects of pressure broadening on the resulting spectra. Considering both the method of calculation (i.e. cross-section or correlated-k) and the treatment of pressure broadening, we show that the differences in the spectra are immediately obvious and hugely significant. Entire spectral features can appear or disappear, changing the morphology of the spectra. For the inspected brown dwarfs, these spectral features can vary by up to three orders of magnitude in luminosity. For our exoplanets, the transit depth can vary by up to 1%. We conclude that each effect would change the retrieved system parameters (i.e. temperature and abundances) considerably.

  4. Optical Radiation of a Gas Discharge in an Argon-Sulfur Mixture

    NASA Astrophysics Data System (ADS)

    General, A. A.; Kelman, V. A.; Zhmenyak, Yu. V.; Zvenigorodsky, V. V.

    2016-09-01

    Plasma luminescence spectra of longitudinal repetitively pulsed discharge in a mixture of argon-sulfur were investigated in the spectral range 300-1000 nm. The major emitting plasma components, such as S2 molecules, sulfur atoms, and ions, are formed as a result of the fragmentation of clusters and sulfur molecules, which starts at energies of ~10 eV. Plasma radiation power increases three-fold on heating the discharge tube from ~50oC to 120oC.

  5. The application of a cavity ring-down spectrometer to measurements of ambient ammonia using traceable primary standard gas mixtures

    NASA Astrophysics Data System (ADS)

    Martin, Nicholas A.; Ferracci, Valerio; Cassidy, Nathan; Hoffnagle, John A.

    2016-08-01

    A correction for the undesirable effects of direct and indirect cross-interference from water vapour on ammonia (NH3) measurements was developed using an optical laser sensor based on cavity ring-down spectroscopy. This correction relied on new measurements of the collisional broadening due to water vapour of two NH3 spectral lines in the near infra-red (6548.6 and 6548.8 cm-1), and on the development of novel stable primary standard gas mixtures (PSMs) of ammonia prepared by gravimetry in passivated gas cylinders at 100 μmol mol-1. The PSMs were diluted dynamically to provide calibration mixtures of dry and humidified ammonia atmospheres of known composition in the nmol mol-1 range and were employed as part of establishing a metrological traceability chain to improve the reliability and accuracy of ambient ammonia measurements. The successful implementation of this correction will allow the extension of this rapid on-line spectroscopic technique to exposure chamber validation tests under controlled conditions and ambient monitoring in the field.

  6. Experimental and simulation studies of iron oxides for geochemical fixation of CO2-SO2 gas mixtures

    USGS Publications Warehouse

    Garcia, Susana; Rosenbauer, Robert J.; Palandri, James; Maroto-Valer, M. Mercedes

    2011-01-01

    Iron-bearing minerals are reactive phases of the subsurface environment and could potentially trap CO2–SO2gas mixtures derived from fossil fuel combustion processes by their conversion to siderite (FeCO3) and dissolved sulfate. Changes in fluid and mineral compositions resulting from reactions, involving the co-injection of SO2 with CO2 were observed both theoretically and experimentally. Experiments were conducted with a natural hematite (α-Fe2O3) sample. A high pressure-high temperature apparatus was used to simulate conditions in geologic formations deeper than 800 m, where CO2 is in the supercritical state. Solid samples were allowed to react with a NaCl–NaOH brine and SO2-bearing CO2-dominated gas mixtures. The predicted equilibrium mineral assemblage at 100 °C and 250 bar became hematite, dawsonite (NaAl(OH)2CO3), siderite (FeCO3) and quartz (SiO2). Experimentally, siderite and dawsonite, derived from the presence of kaolinite (Al2Si2O5(OH)4) in the parent material, were present in residual solids at longer reaction time intervals, which agreed well with results from the modelling work.

  7. Effect of Non-condensable gas on Solutal Marangoni Condensation Heat Transfer Characteristics for Water-Ethanol Vapor Mixture

    NASA Astrophysics Data System (ADS)

    Wang, Shixue; Utaka, Yoshio

    The condensation heat transfer characteristic curves for ternary vapor mixture of water, ethanol and air (or nitrogen) under the ethanol mass fraction of 0.01, 0.07, 0.25, 0.45 and relatively low concentrations of air (or nitrogen) were measured.The effect of air (or nitrogen) as a non-condensable gas on several different domains in the Marangoni condensation characteristic curves was discussed. It was shown that the effect of non-condensable gas in the domains controlled by the diffusion resistance and the filmwise condensation was not notable but in the domain dominated by the condensate resistance of dropwise mode was remarkable. Moreover, the variations of the several characteristic points representing the characteristic curves caused by the change in non-condensable gas concentration were discussed. The deteriorations of the maximum heat transfer coefficient and the maximum heat flux for low ethanol concentration and low concentration of non-condensable gas, in which the excellent heat transfer characteristics were exhibited, were more remarkable.

  8. Endocrine-disrupting chemicals and oil and natural gas operations: Potential environmental contamination and recommendations to assess complex environmental mixtures

    USGS Publications Warehouse

    Kassotis, Christopher D.; Tillitt, Donald E.; Lin, Chung-Ho; McElroy, Jane A.; Nagel, Susan C.

    2015-01-01

    Background: Hydraulic fracturing technologies, developed over the last 65 years, have only recently been combined with horizontal drilling to unlock oil and gas reserves previously deemed inaccessible. While these technologies have dramatically increased domestic oil and natural gas production, they have also raised concerns for the potential contamination of local water supplies with the approximately 1,000 chemicals used throughout the process, including many known or suspected endocrine-disrupting chemicals.Objectives: We discuss the need for an endocrine component to health assessments for drilling-dense regions in the context of hormonal and anti-hormonal activities for chemicals used.Methods: We discuss the literature on 1) surface and ground water contamination by oil and gas extraction operations, and 2) potential human exposure, particularly in context of the total hormonal and anti-hormonal activities present in surface and ground water from natural and anthropogenic sources, with initial analytical results and critical knowledge gaps discussed.Discussion: In light of the potential for environmental release of oil and gas chemicals that can disrupt hormone receptor systems, we recommend methods for assessing complex hormonally active environmental mixtures.Conclusions: We describe a need for an endocrine-centric component for overall health assessments and provide supporting information that using this may help explain reported adverse health trends as well as help develop recommendations for environmental impact assessments and monitoring programs.

  9. Analytical investigation of electrical breakdown properties in a nitrogen-SF{sub 6} mixture gas

    SciTech Connect

    Uhm, Han S.; Byeon, Yong S.; Song, Ki B.; Choi, Eun H.; Ryu, Han-Yong; Lee, Jaimin

    2010-11-15

    The electrical breakdown properties in nitrogen gas mixed with SF{sub 6} are analytically investigated in this article by making use of the ionization and attachment coefficients of the mixed gas. The ionization coefficients of nitrogen and SF{sub 6} gas are obtained in terms of the electron temperature T{sub e} by assuming a Maxwellian distribution of the electron energy. The attachment coefficient of SF{sub 6} gas is also obtained in terms of the gas temperature T{sub e}. An algebraic equation is obtained, relating explicitly the electron breakdown temperature T{sub b} in terms of the SF{sub 6} mole fraction {chi}. It was found from this equation that the breakdown temperature T{sub b} increases from approximately 2 to 5.3 eV as the mole fraction {chi} increases from zero to unity. The breakdown temperature T{sub b} of the electrons increases very rapidly from a small value and then approaches 5.3 eV slowly as the SF{sub 6} mole fraction increases from zero to unity. This indicates that even a small mole fraction of SF{sub 6} in the gas dominates the electron behavior in the breakdown system. The breakdown electric field E{sub b} derived is almost linearly proportional to the breakdown electron temperature T{sub b}. The experimental data agree remarkably well with the theoretical results. Therefore, it is concluded that even a small fraction of SF{sub 6} gas dominates nitrogen in determining the breakdown field. In this context, nearly 25% of the SF{sub 6} mole fraction provides a reasonable enhancement of the breakdown field for practical applications.

  10. Accurate Characterization of the Peptide Linkage in the Gas Phase: A Joint Quantum-Chemical and Rotational Spectroscopy Study of the Glycine Dipeptide Analogue.

    PubMed

    Puzzarini, Cristina; Biczysko, Malgorzata; Barone, Vincenzo; Largo, Laura; Peña, Isabel; Cabezas, Carlos; Alonso, José Luis

    2014-02-01

    Accurate structures of aminoacids in the gas phase have been obtained by joint microwave and quantum-chemical investigations. However, the structure and conformational behavior of α-aminoacids once incorporated into peptide chains are completely different and have not yet been characterized with the same accuracy. To fill this gap, we present here an accurate characterization of the simplest dipeptide analogue (N-acetyl-glycinamide) involving peptidic bonds. State-of-the-art quantum-chemical computations are complemented by a comprehensive study of the rotational spectrum using a combination of Fourier transform microwave spectroscopy with laser ablation. The coexistence of the C7 and C5 conformers has been proved and energetically as well as spectroscopically characterized. This joint theoretical-experimental investigation demonstrated the feasibility of obtaining accurate structures for flexible small biomolecules, thus paving the route to the elucidation of the inherent behavior of peptides.

  11. Gas engine bottoming cycles with ammonia-water mixtures as working fluid

    SciTech Connect

    Jonsson, M.; Thorin, E.; Svedberg, G.

    1999-07-01

    Gas engines and diesel engines can be used for power generation in small-scale industrial and utility power plants. A bottoming cycle recovering heat from the exhaust gas, charge air, jacket water and lubrication oil can increase the power output of a gas or diesel engine power plant. The current study investigates ammonia-water power cycles as bottoming cycles to natural gas fired gas engines. The engines used in the calculations are 16V25SG and 18V34SG from Wartsila NSD. The configurations of the bottoming processes have been changed in order to achieve better temperature matching in the heat exchangers. The ammonia-water cycles have been compared to a simple Rankine steam cycle. All cycles have been optimized to give maximum power output. The ammonia-water bottoming cycles generate 18--54% more power than a simple Rankine steam cycle. An economic estimation of the bottoming cycles shows that the extra equipment needed for an ammonia-water cycle may be justified by the extra amount of power generated.

  12. Ignition delay of a gas mixture above a liquid fuel pool

    NASA Technical Reports Server (NTRS)

    Schiller, D. N.; Sirignano, W. A.

    1991-01-01

    A computational study has been made of transient heat transfer and fluid flow of an axisymmetric two-layer gas-and-liquid system heated from above by a small hot spot (e.g., a hot wire or pilot flame) located close to the liquid surface. The gas phase is unconfined above the liquid pool. The effects of varying gravity level (0.0001 to 1 gn), liquid pool height, and heater height are investigated. Thermocapillary convection induced by the nonuniform heating of the liquid surface combines with buoyancy forces to affect the heat transfer and the transport of fuel vapor toward the heat source. At reduced gravity, gas-phase conduction is comparable to the incident radiation at the liquid surface, whereas at 1 gn, buoyant convection carries the heat upward from the heat source and, therefore, the liquid is heated primarily by radiation.

  13. Device for two-dimensional gas-phase separation and characterization of ion mixtures

    DOEpatents

    Tang, Keqi; Shvartsburg, Alexandre A.; Smith, Richard D.

    2006-12-12

    The present invention relates to a device for separation and characterization of gas-phase ions. The device incorporates an ion source, a field asymmetric waveform ion mobility spectrometry (FAIMS) analyzer, an ion mobility spectrometry (IMS) drift tube, and an ion detector. In one aspect of the invention, FAIMS operating voltages are electrically floated on top of the IMS drift voltage. In the other aspect, the FAIMS/IMS interface is implemented employing an electrodynamic ion funnel, including in particular an hourglass ion funnel. The present invention improves the efficiency (peak capacity) and sensitivity of gas-phase separations; the online FAIMS/IMS coupling creates a fundamentally novel two-dimensional gas-phase separation technology with high peak capacity, specificity, and exceptional throughput.

  14. Hydrogen isotope separation installation for the regeneration of tritium from gas mixtures in tritium facilities

    SciTech Connect

    Andrew, B.M.; Perevezentsev, A.N.; Selivanenko, I.L.

    1994-12-31

    The advantages and disadvantages of different methods for hydrogen isotope separation are considered in terms of their applicability for tritium regeneration in a tritium facility. Due to low inventory, simplicity of operation, flexibility, and safety the methods of separation using solid phases are preferable for tritium facility. The detail consideration of the separation processes with a solid phase reveals that highest efficiency of separation should be achieved in a counter-current separation column, which allow multiplying the thermodynamic isotopic effect. Because of difficulties of the organization of a solid phase motion in a separation column this method did not found practical application for separation of hydrogen isotopic mixtures. The main efforts of a few researches groups were devoted to improve the chromatographic separation process and equipment. The detail comparison of the separation in sectioned column with that in chromatographic as well as in cryodistillation columns show that counter-current separation in a sectioned column is more effective and has other advantages when middle throughput is required. Complete regeneration of an isotopic mixture with separation into three practically pure isotopes independently from isotopic composition of feed can be provided using two sectioned separation columns. Separation installation can operate continuously as well as periodically.

  15. Properties of Gas Mixtures and Their Use in Mixed-Refrigerant Joule-Thomson Refrigerators

    NASA Astrophysics Data System (ADS)

    Luo, E.; Gong, M.; Wu, J.; Zhou, Y.

    2004-06-01

    The Joule-Thomson (J-T) effect has been widely used for achieving low temperatures. In the past few years, much progress has been made in better understanding the working mechanism of the refrigeration method and in developing prototypes for different applications. In this talk, there are three aspects of our research work to be discussed. First, some special thermal properties of the mixtures for achieving liquid nitrogen temperature range will be presented. Secondly, some important conclusions from the optimization of various mixed-refrigerant J-T cycles such as a simple J-T cycle and an auto-cascade mixed-refrigerant J-T cycle will be presented. Moreover, an auto-cascade, mixed-refrigerant J-T refrigerator with a special mixture capable of achieving about 50K will be mentioned. Finally, various prototypes based on the mixed-refrigerant refrigeration technology will be described. These applications include miniature J-T cryocoolers for cooling infrared detectors and high-temperature superconducting devices, cryosurgical knife for medical treatment, low-temperature refrigerators for biological storage and so forth. The on-going research work and unanswered questions for this technology will be also discussed.

  16. Understanding the amorphous-to-microcrystalline silicon transition in SiF{sub 4}/H{sub 2}/Ar gas mixtures

    SciTech Connect

    Dornstetter, Jean-Christophe; Bruneau, Bastien; Bulkin, Pavel; Johnson, Erik V.; Roca i Cabarrocas, Pere

    2014-06-21

    We report on the growth of microcrystalline silicon films from the dissociation of SiF{sub 4}/H{sub 2}/Ar gas mixtures. For this growth chemistry, the formation of HF molecules provides a clear signature of the amorphous to microcrystalline growth transition. Depositing films from silicon tetrafluoride requires the removal of F produced by SiF{sub 4} dissociation, and this removal is promoted by the addition of H{sub 2} which strongly reacts with F to form HF molecules. At low H{sub 2} flow rates, the films grow amorphous as all the available hydrogen is consumed to form HF. Above a critical flow rate, corresponding to the full removal of F, microcrystalline films are produced as there is an excess of atomic hydrogen in the plasma. A simple yet accurate phenomenological model is proposed to explain the SiF{sub 4}/H{sub 2} plasma chemistry in accordance with experimental data. This model provides some rules of thumb to achieve high deposition rates for microcrystalline silicon, namely, that increased RF power must be balanced by an increased H{sub 2} flow rate.

  17. The influence of Bremsstrahlung induced photoionization for the streamer motion in various gas mixtures

    NASA Astrophysics Data System (ADS)

    Koehn, Christoph; Chanrion, Olivier; Neubert, Torsten

    2016-04-01

    Streamers, the beginning stages of electric discharges, evolve differently depending on their polarity and on the ambient gas composition. One of the well-known supporting mechanisms is "UVphotoionization" where, in air, excited nitrogen emits a UV photon subsequently ionizing oxygen. In pure nitrogen, however, this mechanism is suppressed because of the lack of oxygen; hence this mechanism strongly depends on the ambient gas medium. In this paper we introduce Bremsstrahlung induced photoionization: In the ambient electric field,electrons gain energy and produce Bremsstrahlung photons through the collision with the ambient gas molecules; similarly to "UV-photoionization", the Bremsstrahlung photons ionize the gas molecules and, as such, create electron populations detached from the initial electron patch. For the study of this process we implemented the electron-nucleus Bremsstrahlung process as well as the photoionization by individual photons into an already existing 2.5 D Monte Carlo particle code for the simulation of streamers. We initiated plasma patches of electrons and ions with varying initial electron energies and peak densities in different ambient fields in air and pure nitrogen. We will compare the temporal evolution of the electron densities as well as of the electric field with and without modelling Bremsstrahlung. In air we will test the influence of Bremsstrahlung induced photoionization against "UV-photoionization". We will show that the influence of Bremsstrahlung is negligible in air, but plays a significant role in pure nitrogen at standard temperature and pressure.

  18. A program for calculating expansion-tube flow quantities for real-gas mixtures and comparison with experimental results

    NASA Technical Reports Server (NTRS)

    Miller, C. G., III

    1972-01-01

    A computer program written in FORTRAN 4 language is presented which determines expansion-tube flow quantities for real test gases CO2 N2, O2, Ar, He, and H2, or mixtures of these gases, in thermochemical equilibrium. The effects of dissociation and first and second ionization are included. Flow quantities behind the incident shock into the quiescent test gas are determined from the pressure and temperature of the quiescent test gas in conjunction with: (1) incident-shock velocity, (2) static pressure immediately behind the incident shock, or (3) pressure and temperature of the driver gas (imperfect hydrogen or helium). The effect of the possible existence of a shock reflection at the secondary diaphragm of the expansion tube is included. Expansion-tube test-section flow conditions are obtained by performing an isentropic unsteady expansion from the conditions behind the incident shock or reflected shock to either the test-region velocity or the static pressure. Both a thermochemical-equilibrium expansion and a frozen expansion are included. Flow conditions immediately behind the bow shock of a model positioned at the test section are also determined. Results from the program are compared with preliminary experimental data obtained in the Langley 6-inch expansion tube.

  19. Influence of CO2-Ar Mixtures as Shielding Gas on Laser Welding of Al-Mg Alloys

    NASA Astrophysics Data System (ADS)

    Boukha, Zouhair; Sánchez-Amaya, José María; González-Rovira, Leandro; Rio, Eloy Del; Blanco, Ginesa; Botana, Javier

    2013-12-01

    In this study, AA5083 samples were butt welded under a conduction regime with high-power diode laser (HPDL). Various mixtures composed of Ar and CO2 were used as a shielding gas. The influence of the shielding gas composition on the microstructure and on the properties of laser welds was analyzed. The weld beads were deeply characterized by metallographic/microstructural studies, X-ray diffraction (XRD), X-ray energy dispersive spectrometry (X-EDS) chemical analyses, X-ray photoelectron spectra (XPS), microhardness, and tensile strength. The corrosion resistance of laser-remelted surfaces with different CO2/Ar ratios was also estimated by means of electrochemical tests. The addition of CO2 to the shielding gas results in a better weld penetration and oxidizes the weld pool surface. This addition also promotes the migration of Mg toward the surface of weld beads and induces the formation of magnesium aluminates spinel on the welds. The best corrosion resistance result is achieved with 20 pct CO2. The overall results indicate that the addition of small percentage of CO2 to Ar leads to improvements of the mechanical and corrosion properties of the aluminum welds.

  20. Measurements of Speed of Sound in Lean and Rich Natural Gas Mixtures at Pressures up to 37 MPa Using a Specialized Rupture Tube

    NASA Astrophysics Data System (ADS)

    Botros, K. K.

    2010-12-01

    Measurements of the speed of sound in 42 different compositions of lean, medium, and rich natural-gas mixtures using a specialized high-pressure rupture tube have been conducted. The rupture tube is made of stainless steel (internal diameter = 38.1 mm and length = 42 m), and is instrumented with 13 high-frequency-response dynamic pressure transducers (Endevco) mounted very close to the rupture end and along the length of the tube to capture the pressure-time traces of the decompression wave. Tests were conducted for initial pressures ranging from 10 MPa to 37 MPa and a temperature range from -25°C to+68°C. Gas mixture compositions were controlled by mixing conventional natural-gas mixtures from an adjacent gas pipeline with richer components of alkanes. Temperature control is achieved by a heat tracer along the tube with a set point at the desired gas temperature of the particular test. Uncertainty analysis indicated that the uncertainty in the experimentally determined speed of sound in the undisturbed gas mixture at the initial pressure and temperature is on the order of 0.306 %. The measured speeds of sound were compared to predictions by five equations of state, namely; the Benedict-Webb-Rubin-Starling (BWRS), AGA-8, Peng-Robinson (PR), Redlich-Kwong-Soave (RK-Soave), and Groupe Européen de Recherches Gaziéres (GERG-2004) equations.

  1. A conservative multi-group approach to the Boltzmann equations for reactive gas mixtures

    NASA Astrophysics Data System (ADS)

    Bisi, M.; Rossani, A.; Spiga, G.

    2015-11-01

    Starting from a simple kinetic model for a quaternary mixture of gases undergoing a bimolecular chemical reaction, multi-group integro-differential equations are derived for the particle distribution functions of all species. The procedure takes advantage of a suitable probabilistic formulation, based on the underlying collision frequencies and transition probabilities, of the relevant reactive kinetic equations of Boltzmann type. Owing to an appropriate choice of a sufficiently large number of weight functions, it is shown that the proposed multi-group equations are able to fulfil exactly, at any order of approximation, the correct conservation laws that must be inherited from the original kinetic equations, where speed was a continuous variable. Future developments are also discussed.

  2. Discharge stabilization studies of CO laser gas mixtures in quasi-steady supersonic flow

    NASA Technical Reports Server (NTRS)

    Srinivasan, G.; Smith, J. A.

    1976-01-01

    Experiments were conducted to study the applicability of a double discharge stabilization scheme in conditions appropriate for high energy CO lasers in supersonic flows. A Ludwieg tube impulse flow facility and a ballasted capacitor bank provided essentially steady flow and discharge conditions (d.c.) for times longer than ten electrode length-flow transit times. Steady, arc-free, volume discharges were produced in a Mach 3 test cavity using an auxiliary discharge to stabilize the main discharge in N2 and He/CO mixture. A signigicant result is the lack of observed plasma E/N changes in response to auxiliary discharge current changes. Also, where glow discharges were obtained, the energy loading achieved was very much less than the threshold level required for laser operation.

  3. [Hypoxic gas mixture delivery due to a defective vaporiser manifold: case report, review of the literature and suggested emergency management algorithm].

    PubMed

    Berlet, T

    2014-04-01

    A case of delivery of a hypoxic gas mixture to a patient during total intravenous anesthesia is described. A progressive fall in inspiratory oxygen concentration followed by a drop in oxygen saturation below 90 % occurred during the advanced stages of a hitherto uneventful general anesthesia of a female patient undergoing anterior cervical fusion surgery. A malfunctioning defective rubber seal of a vaporizer manifold was identified as the cause of the gas leak. The leak had not been detected during the preanesthesia leak test. The problem of hypoxic gas mixtures and uncommon leaks in modern anesthesia equipment is discussed. The importance of locating a leak in the high or low pressure circuits is explained. An algorithm for the management of an unexpected decrease of inspiratory oxygen concentration or any other manifestation of a gas leak along with a systematic approach to locating the source of a gas leak is presented. PMID:24584839

  4. Two-fluid dust and gas mixtures in smoothed particle hydrodynamics: a semi-implicit approach

    NASA Astrophysics Data System (ADS)

    Lorén-Aguilar, Pablo; Bate, Matthew R.

    2014-09-01

    A method to avoid the explicit time integration of small dust grains in the two-fluid gas/dust smoothed particle hydrodynamics (SPH) approach is proposed. By assuming a very simple exponential decay model for the relative velocity between the gas and dust components, all the effective characteristics of the drag force can be reproduced. A series of tests has been performed to compare the accuracy of the method with analytical and explicit integration results. We find that the method performs well on a wide range of tests, and can provide large speed-ups over explicit integration when the dust stopping time is small. We have also found that the method is much less dissipative than conventional explicit or implicit two-fluid SPH approaches when modelling dusty shocks.

  5. High pressure laser plasma studies. [energy pathways in He-Ar gas mixtures at low pressure

    NASA Technical Reports Server (NTRS)

    Wells, W. E.

    1980-01-01

    The operation of a nuclear pumped laser, operating at a wavelength of 1.79 micron m on the 3d(1/2-4p(3/2) transition in argon with helium-3 as the majority gas is discussed. The energy pathways in He-Ar gas were investigated by observing the effects of varying partial pressures on the emissions of levels lying above the 4p level in argon during a pulsed afterglow. An attempt is made to determine the population mechanisms of the 3d level in pure argon by observing emission from the same transition in a high pressure plasma excited by a high energy electron beam. Both collisional radiative and dissociative recombination are discussed.

  6. Process employing CO/sub 2//CH gas mixtures for secondary exploitation of oil reservoirs

    SciTech Connect

    Kiss, L.; Dolleschall, S.; Nemeth, E.; Tiszai, G.; Balint, V.; Torok, J.

    1986-12-16

    This patent describes a process for the secondary recovery of crude oil from subterranean reservoirs by injecting carbon dioxide-containing gas into the reservoir through at least one injection well penetrating into the reservoir until a desired volume of carbon dioxide has been added. Then, water is injected through at least one injection well to force such carbon dioxide through the reservoir, and oil is withdrawn through at least one production well at such a flow rate as to maintain a reservoir pressure of at least 100 atm. until the water breaks through into the production well. The improvement described here comprises diluting the carbon dioxide gas in the reservoir with from 5 to 35 vol. % of hydrocarbon gases at a reservoir pressure ranging from above 107 up to 250 atm.

  7. Oxygen/ozone as a medical gas mixture. A critical evaluation of the various methods clarifies positive and negative aspects

    PubMed Central

    2011-01-01

    Besides oxygen, several other gases such as NO, CO, H2, H2S, Xe and O3 have come to age over the past few years. With regards to O3, its mechanisms of action in medicine have been clarified during the last two decades so that now a comprehensive framework for understanding and recommending ozone therapy in various pathologies is available. O3 used within the determined therapeutic window is absolutely safe and more effective than golden standard medications in numerous pathologies, like vascular diseases. However, ozone therapy is mostly in practitioners' hands and some recent developments for increasing cost effectiveness and speed of treatment are neither standardized, nor evaluated toxicologically. Hence, the aim of this article is to emphasize the need to objectively assess the pros and cons of oxygen/ozone as a medical gas mixture in the hope that ozone therapy will be accepted by orthodox medicine in the near future. PMID:22146387

  8. A new quantum gas apparatus for ultracold mixtures of K and Cs and KCs ground-state molecules

    NASA Astrophysics Data System (ADS)

    Gröbner, M.; Weinmann, P.; Meinert, F.; Lauber, K.; Kirilov, E.; Nägerl, H.-C.

    2016-10-01

    We present a new quantum gas apparatus for ultracold mixtures of K and Cs atoms and ultracold samples of KCs ground-state molecules. We demonstrate the apparatus' capabilities by producing Bose-Einstein condensates of ? and ? in a manner that will eventually allow sequential condensation within one experimental cycle, precise sample overlap and magnetic association of atoms into KCs molecules. The condensates are created independently without relying on sympathetic cooling. Our approach is universal and applicable to other species combinations when the two species show dramatically different behavior in terms of loss mechanisms and post laser cooling temperatures, i.e. species combinations that make parallel generation of quantum degenerate samples challenging. We give an outlook over the next experiments involving e.g. sample mixing, molecule formation and transport into a science chamber for high-resolution spatial imaging of novel quantum-many body phases based on K-Cs.

  9. Observations of columnal recombination in the ionization tracks of energetic heavy nuclei in an argon-methane gas mixture

    NASA Technical Reports Server (NTRS)

    Wiedenbeck, Mark E.

    1990-01-01

    Measurements of ionization signals resulting from the passage of energetic heavy nuclei through a gas mixture consisting of 95 mol percent Ar plus 5 mol percent CH4, at an absolute pressure of 3 atm are presented. The measurements take place under a uniform electric field perpendicular to the ionization track. The signals were compared to the calculated energy losses, with an assumption of proportionality between energy loss rate and ionization rate. Significant deviations from proportionality are found for energy loss rate grater than about 3000 MeV sq cm/g, while fractional deviations are found to be proportional to the energy loss rate (dE/dx) exp m, where m is equal to about two. These results are attributed to the columnal recombination.

  10. Controlling the Neutron Yield from a Small Dense Plasma Focus using Deuterium-Inert Gas Mixtures

    SciTech Connect

    Bures, B. L.; Krishnan, M.; Eshaq, Y.

    2009-01-21

    The dense plasma focus (DPF) is a well known source of neutrons when operating with deuterium. The DPF is demonstrated to scale from 10{sup 4} n/pulse at 40 kA to >10{sup 12} n/pulse at 2 MA by non-linear current scaling as described in [1], which is itself based on the simple yet elegant model developed by Lee [2]. In addition to the peak current, the gas pressure controls the neutron yield. Recent published results suggest that mixing 1-5% mass fractions of Krypton increase the neutron yield per pulse by more than 10x. In this paper we present results obtained by mixing deuterium with Helium, Neon and Argon in a 500 J dense plasma focus operating at 140 kA with a 600 ns rise time. The mass density was held constant in these experiments at the optimum (pure) deuterium mass density for producing neutrons. A typical neutron yield for a pure deuterium gas charge is 2x10{sup 6}{+-}15% n/pulse. Neutron yields in excess of 10{sup 7}{+-}10% n/pulse were observed with low mass fractions of inert gas. Time integrated optical images of the pinch, soft x-ray measurements and optical emission spectroscopy where used to examine the pinch in addition to the neutron yield monitor and the fast scintillation detector. Work supported by Domestic Nuclear Detection Office under contract HSHQDC-08-C-00020.

  11. Numerical modeling of condensation from vapor-gas mixtures for forced down flow inside a tube

    SciTech Connect

    Yuann, R Y; Schrock, V E; Chen, Xiang

    1995-09-01

    Laminar film condensation is the dominant heat transfer mode inside tubes. In the present paper direct numerical simulation of the detailed transport process within the steam-gas core flow and in the condensate film is carried out. The problem was posed as an axisymmetric two dimensional (r, z) gas phase inside an annular condensate film flow with an assumed smooth interface. The fundamental conservation equations were written for mass, momentum, species concentration and energy in the gaseous phase with effective diffusion parameters characterizing the turbulent region. The low Reynolds number two equation {kappa}-{epsilon} model was employed to determine the eddy diffusion coefficients. The liquid film was described by similar formulation without the gas species equation. An empirical correlation was employed to correct for the effect of film waviness on the interfacial shear. A computer code named COAPIT (Condensation Analysis Program Inside Tube) was developed to implement numerical solution of the fundamental equations. The equations were solved by a marching technique working downstream from the entrance of the condensing section. COAPIT was benchmarked against experimental data and overall reasonable agreement was found for the key parameters such as heat transfer coefficient and tube inner wall temperature. The predicted axial development of radial profiles of velocity, composition and temperature and occurrence of metastable vapor add insight to the physical phenomena.

  12. Optical characteristics and parameters of gas-discharge plasma in a mixture of mercury dibromide vapor with argon

    SciTech Connect

    Malinina, A. A. Malinin, A. N.

    2015-03-15

    Results are presented from studies of the optical characteristics and parameters of the plasma of a dielectric barrier discharge in a mixture of mercury dibromide vapor with argon—the working medium of an exciplex gas-discharge emitter. It is established that the partial pressures of mercury dibromide vapor and argon at which the average and pulsed emission intensities in the blue—green spectral region (λ{sub max} = 502 nm) reach their maximum values are 0.6 and 114.4 kPa, respectively. The electron energy distribution function, the transport characteristics, the specific power spent on the processes involving electrons, the electron density and temperature, and the rate constants for the processes of elastic and inelastic electron scattering from the molecules and atoms of the working mixture are determined by numerical simulation, and their dependences on the reduced electric field strength are analyzed. The rate constant of the process leading to the formation of exciplex mercury monobromide molecules for a reduced electric field of E/N = 20 Td, at which the maximum emission intensity in the blue—green spectral region was observed in this experiment, is found to be 8.1 × 10{sup −15} m{sup 3}/s.

  13. Application of Momentum Transfer Theory for Ion and Electron Transport in Pure Gases and in Gas Mixtures

    SciTech Connect

    Jovanovic, J.V.; Vrhovac, S. B.

    2004-12-01

    In this paper we have presented two applications of Momentum Transfer Theory (MTT), which were both aimed at obtaining reliable data for modeling of non-equilibrium plasma. Transport properties of ion swarms in presence of Resonant Charge Transfer (RCT) collisions are studied using Momentum Transfer Theory (MTT). Using the developed MTT we tested a previously available anisotropic set of cross-sections for Ar++Ar collisions bay making the comparisons with the available data for the transverse diffusion coefficient. We also developed an anisotropic set of Ne++Ne integral cross-sections based on the available data for mobility, longitudinal and transverse diffusion. Anisotropic sets of cross-sections are needed for Monte Carlo simulations of ion transport and plasma models. Application of Blanc's Law for drift velocities of electrons and ions in gas mixtures at arbitrary reduced electric field strengths E/n0 was studied theoretically and by numerical examples. Corrections for Blanc's Law that include effects of inelastic collisions were derived. In addition we have derived the common mean energy procedure that was proposed by Chiflikian in a general case both for ions and electrons. Both corrected common E/n0 and common mean energy procedures provide excellent results even for electrons at moderate E/n0 where application of Blanc's Law was regarded as impossible. In mixtures of two gases that have negative differential conductivity (NDC) even when neither of the two pure gases show NDC the Blanc's Law procedure was able to give excellent predictions.

  14. Luminescence characteristics of Xe{sub 2}Cl excimer molecules under pumping the dense Xe-CCl{sub 4} gas mixtures with a pulsed electron beam

    SciTech Connect

    Mis'kevich, A I; Jinbo, Guo

    2013-05-31

    Temporal and spectral characteristics of the luminescence of dense Xe-CCl{sub 4} gas mixtures of different composition, excited by a 5-ns pulsed electron beam, were measured. The energy of the electrons amounted to 150 keV and the electron beam current pulse amplitude was 5 A. The gas mixtures were used containing Xe (38-700 Torr) and CCl{sub 4} (0.03-0.3 Torr). The studies were performed within the wavelength range 200-1200 nm using a MAYA-2000Pro diffraction grating spectrometer and a RIGOL DS 5022 ME fast digital oscilloscope. The luminescence lifetimes of the excimer molecules XeCl* (band with {lambda}{sub max} = 308 nm) and Xe{sub 2}Cl* (band with {lambda}{sub max} = 486 nm) were measured, as well as the constants of quenching by the components of the gas mixture for Xe{sub 2}Cl* molecules. A model of plasma-chemical processes for dense Xe-CCl{sub 4} gas mixtures with a very low content of the CCl{sub 4} donor is proposed. It is shown that in such 'poor' mixtures Xe{sub 2}Cl* molecules are mainly produced as a result of recombination of the Xe{sub 2}{sup +} and Cl{sup -} ions. (active media)

  15. Approximate equations of state in two-temperature plasma mixtures

    SciTech Connect

    Ramshaw, John D.; Cook, Andrew W.

    2014-02-15

    Approximate thermodynamic state relations for multicomponent atomic and molecular gas mixtures are often constructed by artificially partitioning the mixture into its constituent materials and requiring the separated materials to be in temperature and pressure equilibrium. Iterative numerical algorithms have been employed to enforce this equilibration and compute the resulting approximate state relations in single-temperature mixtures. In partially ionized gas mixtures, there is both theoretical and empirical evidence that equilibrating the chemical potentials, number densities, or partial pressures of the free electrons is likely to produce more accurate results than equilibrating the total pressures. Moreover, in many situations of practical interest the free electrons and heavy particles have different temperatures. In this paper, we present a generalized algorithm for equilibrating the heavy-particle and electron temperatures and a third user-specified independent thermodynamic variable in a two-temperature plasma mixture. Test calculations based on the equilibration of total pressure vs. electron pressure are presented for three different mixtures.

  16. Comparison of surface vacuum ultraviolet emissions with resonance level number densities. II. Rare-gas plasmas and Ar-molecular gas mixtures

    SciTech Connect

    Boffard, John B. Lin, Chun C.; Wang, Shicong; Wendt, Amy E.; Culver, Cody; Radovanov, Svetlana; Persing, Harold

    2015-03-15

    Vacuum ultraviolet (VUV) emissions from excited plasma species can play a variety of roles in processing plasmas, including damaging the surface properties of materials used in semiconductor processing. Depending on their wavelength, VUV photons can easily transmit thin upper dielectric layers and affect the electrical characteristics of the devices. Despite their importance, measuring VUV fluxes is complicated by the fact that few materials transmit at VUV wavelengths, and both detectors and windows are easily damaged by plasma exposure. The authors have previously reported on measuring VUV fluxes in pure argon plasmas by monitoring the concentrations of Ar(3p{sup 5}4s) resonance atoms that produce the VUV emissions using noninvasive optical emission spectroscopy in the visible/near-infrared wavelength range [Boffard et al., J. Vac. Sci. Technol., A 32, 021304 (2014)]. Here, the authors extend this technique to other rare-gases (Ne, Kr, and Xe) and argon-molecular gas plasmas (Ar/H{sub 2}, Ar/O{sub 2}, and Ar/N{sub 2}). Results of a model for VUV emissions that couples radiation trapping and the measured rare-gas resonance level densities are compared to measurements made with both a calibrated VUV photodiode and a sodium salicylate fluorescence detection scheme. In these more complicated gas mixtures, VUV emissions from a variety of sources beyond the principal resonance levels of the rare gases are found to contribute to the total VUV flux.

  17. Thick c-BN films deposited by radio frequency magnetron sputtering in argon/nitrogen gas mixture with additional hydrogen gas

    NASA Astrophysics Data System (ADS)

    Zhao, Yan; Gao, Wei; Xu, Bo; Li, Ying-Ai; Li, Hong-Dong; Gu, Guang-Rui; Yin, Hong

    2016-10-01

    The excellent physical and chemical properties of cubic boron nitride (c-BN) film make it a promising candidate for various industry applications. However, the c-BN film thickness restricts its practical applications in many cases. Thus, it is indispensable to develop an economic, simple and environment-friend way to synthesize high-quality thick, stable c-BN films. High-cubic-content BN films are prepared on silicon (100) substrates by radio frequency (RF) magnetron sputtering from an h-BN target at low substrate temperature. Adhesions of the c-BN films are greatly improved by adding hydrogen to the argon/nitrogen gas mixture, allowing the deposition of a film up to 5-μm thick. The compositions and the microstructure morphologies of the c-BN films grown at different substrate temperatures are systematically investigated with respect to the ratio of H2 gas content to total working gas. In addition, a primary mechanism for the deposition of thick c-BN film is proposed. Project supported by the National Natural Science Foundation of China (Grant Nos. 51572105, 61504046, and 51272224), the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry, China, the Development and Reform Commission of Jilin Province, China (Grant No. 2015Y050), and the Scientific Research Foundation for the Returned Overseas of Jilin Province, China.

  18. Propagation of a cylindrical shock wave in a mixture of a non-ideal gas and small solid particles under the action of monochromatic radiation

    NASA Astrophysics Data System (ADS)

    Sahu, Praveen Kumar; Nath, Gorakh

    2016-07-01

    Cylindrical shock wave in a dusty gas is discussed under the action of monochromatic radiation into stellar atmosphere with a constant intensity on unit area. The gas is assumed to be grey and opaque and shock to be transparent. The dusty gas is assumed to be a mixture of non-ideal gas and small solid particles. To obtain some essential features of the shock propagation, small solid particles are taken as pseudo-fluid and it is assumed that the equilibrium flow condition is maintained in the flow-field. The effects of variation of the parameters of the non-idealness of the gas, the mass concentration of solid particles in the mixture, the ratio of the density of solid particles to the initial density of the gas and the radiation parameter are investigated. It is shown that an increase in the parameters of the non-idealness of the gas and the radiation parameter have decaying effect on the shock waves; whereas with an increase in the ratio of the density of solid particles to the initial density of the gas the shock strength increases. It is found that an increase in the parameter non-idealness of the gas and the ratio of the density of solid particles to the initial density of the gas have opposite behaviour on fluid velocity, pressure and shock strength. Also, it is shown that an increase in the radiation parameter has effect to decrease the flow variables and the shock strength.

  19. On inelastic reactive collisions in kinetic theory of chemically reacting gas mixtures

    NASA Astrophysics Data System (ADS)

    Kremer, Gilberto M.; Silva, Adriano W.; Alves, Giselle M.

    2010-07-01

    A kinetic theory for a simple reversible reaction-characterized by a binary mixture of ideal gases whose constituents denoted by A and B undergo a reaction of the type A+A⇌B+B-is developed by considering the reactive collisions as inelastic ones. The geometry of the collision is taken into account in the line-of-centers differential cross section by allowing that a chemical reaction may occur only when the energy of the relative velocity in the direction of the line which joins the centers of the molecules at collision is larger than the activation energy. It is shown that the restitution coefficients: (i) depend explicitly on the reaction heat and on the relative translational energy in the direction of the line which joins the centers of the molecules during an inelastic collision; (ii) vanish when the reaction heat is zero; (iii) are larger or smaller than one depending on the direction of the reaction and on the sign of the reaction heat. First approximations to the distribution functions are determined from the system of Boltzmann equations for the last stage of a chemical reaction. It is shown that the deviations from the Maxwellian distribution functions and the production terms of the particle number densities: (i) vanish when the reaction heat is zero provided that the affinity is close to zero and (ii) are negative or positive depending on the sign of the reaction heat and on the direction of the reaction.

  20. Torsional rheometer for granular materials slurries and gas-solid mixtures and related methods

    DOEpatents

    Rajagopal, Chandrika; Rajagopal, Kumbakonam R.; Yalamanchili, Rattaya C.

    1997-01-01

    A torsional rheometer apparatus for determining rheological properties of a specimen is provided. A stationary plate and a rotatable plate are in generally coaxial position and structured to receive a specimen therebetween. In one embodiment, at least one of the plates and preferably both have roughened specimen engaging surfaces to serve to reduce undesired slippage between the plate and the specimen. A motor is provided to rotate the rotatable plate and a transducer for monitoring forces applied to the stationary plate and generating output signals to a computer which determines the desired rheological properties are provided. In one embodiment, the roughened surfaces consist of projections extending toward the specimen. Where granular material is being evaluated, it is preferred that the roughness of the plate is generally equal to the average size of the granular material being processed. In another embodiment, an air-solid mixture is processed and the roughened portions are pore openings in the plates. Air flows through the region between the two pore containing plates to maintain the solid materials in suspension. In yet another embodiment, the base of the stationary plate is provided with a deformable capacitance sensor and associated electronic means.

  1. Torsional rheometer for granular materials slurries and gas-solid mixtures and related methods

    DOEpatents

    Rajagopal, C.; Rajagopal, K.R.; Yalamanchili, R.C.

    1997-03-11

    A torsional rheometer apparatus for determining rheological properties of a specimen is provided. A stationary plate and a rotatable plate are in generally coaxial position and structured to receive a specimen there between. In one embodiment, at least one of the plates and preferably both have roughened specimen engaging surfaces to serve to reduce undesired slippage between the plate and the specimen. A motor is provided to rotate the rotatable plate and a transducer for monitoring forces applied to the stationary plate and generating output signals to a computer which determines the desired rheological properties are provided. In one embodiment, the roughened surfaces consist of projections extending toward the specimen. Where granular material is being evaluated, it is preferred that the roughness of the plate is generally equal to the average size of the granular material being processed. In another embodiment, an air-solid mixture is processed and the roughened portions are pore openings in the plates. Air flows through the region between the two pore containing plates to maintain the solid materials in suspension. In yet another embodiment, the base of the stationary plate is provided with a deformable capacitance sensor and associated electronic means. 17 figs.

  2. Analysis of polyaromatic hydrocarbon mixtures with laser ionization gas chromatography/mass spectrometry

    SciTech Connect

    Rhodes, G.; Opsal, R.B.; Meek, J.T.; Reilly, J.P.

    1983-02-01

    Excimer laser induced multiphoton ionization has been utilized for ion generation in capillary gas chromatography/mass spectrometry and the technique applied to the separation and detection of polyaromatic hydrocarbons. Detection limits as low as 200 fg and linearity over a range of 5 x 10/sup +4/ were obtained for the polyaromatic hydrocarbons examined. Multiphoton ionization mass spectra were dominated by parent ions. Selective ionization based upon small differences in ionization potentials has been demonstrated for coeluting chrysene and triphenylene. Instrumental parameters have been investigated to assess improvements in sensitivity.

  3. Combustion of ultrafine coal/water mixtures and their application in gas turbines: Final report

    SciTech Connect

    Toqan, M.A.; Srinivasachar, S.; Staudt, J.; Varela, F.; Beer, J.M.

    1987-10-01

    The feasibility of using coal-water fuels (CWF) in gas turbine combustors has been demonstrated in recent pilot plant experiments. The demands of burning coal-water fuels with high flame stability, complete combustion, low NO/sub x/ emission and a resulting fly ash particle size that will not erode turbine blades represent a significant challenge to combustion scientists and engineers. The satisfactory solution of these problems requires that the variation of the structure of CWF flames, i.e., the fields of flow, temperature and chemical species concentration in the flame, with operating conditions is known. Detailed in-flame measurements are difficult at elevated pressures and it has been proposed to carry out such experiments at atmospheric pressure and interpret the data by means of models for gas turbine combustor conditions. The research was carried out in five sequential tasks: cold flow studies; studies of conventional fine-grind CWF; combustion studies with ultrafine CWF fuel; reduction of NO/sub x/ emission by staged combustion; and data interpretation-ignition and radiation aspects. 37 refs., 61 figs., 9 tabs.

  4. Emission spectroscopy of a microhollow cathode discharge plasma in helium-water gas mixtures

    SciTech Connect

    Namba, S.; Yamasaki, T.; Hane, Y.; Fukuhara, D.; Kozue, K.; Takiyama, K.

    2011-10-01

    A dc microhollow cathode discharge (MHCD) plasma was generated inflowing helium gas containing water vapor. The cathode hole diameters were 0.3, 0.7, 1.0, and 2.0 mm, each with a length of 2.0 mm. Emission spectroscopy was carried out to investigate the discharge mode and to determine the plasma parameters. For the 0.3-mm cathode, stable MHCDs in an abnormal glow mode existed at pressures up to 100 kPa, whereas for larger diameters, a plasma was not generated at atmospheric pressure. An analysis of the lineshapes relevant to He at 667.8 nm and to H{alpha} at 656.3 nm implied an electron density and gas temperature of 2 x 10{sup 14} cm{sup -3} and 1100 K, respectively, for a 100-kPa discharge in the negative glow region. The dependence of the OH band, and H{alpha} intensities on the discharge current exhibited different behaviors. Specifically, the OH spectrum had a maximum intensity at a certain current, while the H atom intensity kept increasing with the discharge current. This observation implies that a high concentration of OH radicals results in quenching, leading to the production of H atoms via the reaction OH + e{sup -}{yields} O + H + e{sup -}.

  5. Emission spectroscopy of a microhollow cathode discharge plasma in helium-water gas mixtures

    NASA Astrophysics Data System (ADS)

    Namba, S.; Yamasaki, T.; Hane, Y.; Fukuhara, D.; Kozue, K.; Takiyama, K.

    2011-10-01

    A dc microhollow cathode discharge (MHCD) plasma was generated inflowing helium gas containing water vapor. The cathode hole diameters were 0.3, 0.7, 1.0, and 2.0 mm, each with a length of 2.0 mm. Emission spectroscopy was carried out to investigate the discharge mode and to determine the plasma parameters. For the 0.3-mm cathode, stable MHCDs in an abnormal glow mode existed at pressures up to 100 kPa, whereas for larger diameters, a plasma was not generated at atmospheric pressure. An analysis of the lineshapes relevant to He at 667.8 nm and to Hα at 656.3 nm implied an electron density and gas temperature of 2 × 1014 cm-3 and 1100 K, respectively, for a 100-kPa discharge in the negative glow region. The dependence of the OH band, and Hα intensities on the discharge current exhibited different behaviors. Specifically, the OH spectrum had a maximum intensity at a certain current, while the H atom intensity kept increasing with the discharge current. This observation implies that a high concentration of OH radicals results in quenching, leading to the production of H atoms via the reaction OH + e- → O + H + e-.

  6. Abatement of SO2-NOx binary gas mixtures using a ferruginous active absorbent: Part I. Synergistic effects and mechanism.

    PubMed

    Han, Yinghui; Li, Xiaolei; Fan, Maohong; Russell, Armistead G; Zhao, Yi; Cao, Chunmei; Zhang, Ning; Jiang, Genshan

    2015-04-01

    A novel ferruginous active absorbent, prepared by fly ash, industrial lime and the additive Fe(VI), was introduced for synchronous abatement of binary mixtures of SO2-NOx from simulated coal-fired flue gas. The synergistic action of various factors on the absorption of SO2 and NOx was investigated. The results show that a strong synergistic effect exists between Fe(VI) dose and reaction temperature for the desulfurization. It was observed that in the denitration process, the synergy of Fe(VI) dose and Ca/(S+N) had the most significant impact on the removal of NO, followed by the synergy of Fe(VI) and reaction temperature, and then the synergy of reaction temperature and flue gas humidity. A scanning electron microscope (SEM) and an accessory X-ray energy spectrometer (EDS) were used to observe the surface characteristics of the raw and spent absorbent as well as fly ash. A reaction mechanism was proposed based on chemical analysis of sulfur and nitrogen species concentrations in the spent absorbent. The Gibbs free energy, equilibrium constants and partial pressures of the SO2-NOx binary system were determined by thermodynamics.

  7. Measurement and Evaluation of the Gas Density and Viscosity of Pure Gases and Mixtures Using a Micro-Cantilever Beam.

    PubMed

    Badarlis, Anastasios; Pfau, Axel; Kalfas, Anestis

    2015-01-01

    Measurement of gas density and viscosity was conducted using a micro-cantilever beam. In parallel, the validity of the proposed modeling approach was evaluated. This study also aimed to widen the database of the gases on which the model development of the micro-cantilever beams is based. The density and viscosity of gases are orders of magnitude lower than liquids. For this reason, the use of a very sensitive sensor is essential. In this study, a micro-cantilever beam from the field of atomic force microscopy was used. Although the current cantilever was designed to work with thermal activation, in the current investigation, it was activated with an electromagnetic force. The deflection of the cantilever beam was detected by an integrated piezo-resistive sensor. Six pure gases and sixteen mixtures of them in ambient conditions were investigated. The outcome of the investigation showed that the current cantilever beam had a sensitivity of 240 Hz/(kg/m³), while the accuracy of the determined gas density and viscosity in ambient conditions reached ±1.5% and ±2.0%, respectively. PMID:26402682

  8. Measurement and Evaluation of the Gas Density and Viscosity of Pure Gases and Mixtures Using a Micro-Cantilever Beam

    PubMed Central

    Badarlis, Anastasios; Pfau, Axel; Kalfas, Anestis

    2015-01-01

    Measurement of gas density and viscosity was conducted using a micro-cantilever beam. In parallel, the validity of the proposed modeling approach was evaluated. This study also aimed to widen the database of the gases on which the model development of the micro-cantilever beams is based. The density and viscosity of gases are orders of magnitude lower than liquids. For this reason, the use of a very sensitive sensor is essential. In this study, a micro-cantilever beam from the field of atomic force microscopy was used. Although the current cantilever was designed to work with thermal activation, in the current investigation, it was activated with an electromagnetic force. The deflection of the cantilever beam was detected by an integrated piezo-resistive sensor. Six pure gases and sixteen mixtures of them in ambient conditions were investigated. The outcome of the investigation showed that the current cantilever beam had a sensitivity of 240 Hz/(kg/m3), while the accuracy of the determined gas density and viscosity in ambient conditions reached ±1.5% and ±2.0%, respectively. PMID:26402682

  9. Abatement of SO2-NOx binary gas mixtures using a ferruginous active absorbent: Part I. Synergistic effects and mechanism.

    PubMed

    Han, Yinghui; Li, Xiaolei; Fan, Maohong; Russell, Armistead G; Zhao, Yi; Cao, Chunmei; Zhang, Ning; Jiang, Genshan

    2015-04-01

    A novel ferruginous active absorbent, prepared by fly ash, industrial lime and the additive Fe(VI), was introduced for synchronous abatement of binary mixtures of SO2-NOx from simulated coal-fired flue gas. The synergistic action of various factors on the absorption of SO2 and NOx was investigated. The results show that a strong synergistic effect exists between Fe(VI) dose and reaction temperature for the desulfurization. It was observed that in the denitration process, the synergy of Fe(VI) dose and Ca/(S+N) had the most significant impact on the removal of NO, followed by the synergy of Fe(VI) and reaction temperature, and then the synergy of reaction temperature and flue gas humidity. A scanning electron microscope (SEM) and an accessory X-ray energy spectrometer (EDS) were used to observe the surface characteristics of the raw and spent absorbent as well as fly ash. A reaction mechanism was proposed based on chemical analysis of sulfur and nitrogen species concentrations in the spent absorbent. The Gibbs free energy, equilibrium constants and partial pressures of the SO2-NOx binary system were determined by thermodynamics. PMID:25872709

  10. Measurement and Evaluation of the Gas Density and Viscosity of Pure Gases and Mixtures Using a Micro-Cantilever Beam.

    PubMed

    Badarlis, Anastasios; Pfau, Axel; Kalfas, Anestis

    2015-09-22

    Measurement of gas density and viscosity was conducted using a micro-cantilever beam. In parallel, the validity of the proposed modeling approach was evaluated. This study also aimed to widen the database of the gases on which the model development of the micro-cantilever beams is based. The density and viscosity of gases are orders of magnitude lower than liquids. For this reason, the use of a very sensitive sensor is essential. In this study, a micro-cantilever beam from the field of atomic force microscopy was used. Although the current cantilever was designed to work with thermal activation, in the current investigation, it was activated with an electromagnetic force. The deflection of the cantilever beam was detected by an integrated piezo-resistive sensor. Six pure gases and sixteen mixtures of them in ambient conditions were investigated. The outcome of the investigation showed that the current cantilever beam had a sensitivity of 240 Hz/(kg/m³), while the accuracy of the determined gas density and viscosity in ambient conditions reached ±1.5% and ±2.0%, respectively.

  11. Polynomial approximations of thermodynamic properties of arbitrary gas mixtures over wide pressure and density ranges

    NASA Technical Reports Server (NTRS)

    Allison, D. O.

    1972-01-01

    Computer programs for flow fields around planetary entry vehicles require real-gas equilibrium thermodynamic properties in a simple form which can be evaluated quickly. To fill this need, polynomial approximations were found for thermodynamic properties of air and model planetary atmospheres. A coefficient-averaging technique was used for curve fitting in lieu of the usual least-squares method. The polynomials consist of terms up to the ninth degree in each of two variables (essentially pressure and density) including all cross terms. Four of these polynomials can be joined to cover, for example, a range of about 1000 to 11000 K and 0.00001 to 1 atmosphere (1 atm = 1.0133 x 100,000 N/m sq) for a given thermodynamic property. Relative errors of less than 1 percent are found over most of the applicable range.

  12. Reaction mechanism for the thermal decomposition of BCl3/CH4/H2 gas mixtures.

    PubMed

    Reinisch, Guillaume; Vignoles, Gérard L; Leyssale, Jean-Marc

    2011-10-27

    This paper presents an ab initio study of the B/C/Cl/H gas phase mechanism, featuring 10 addition-elimination reactions involving BH(i)Cl(j) (i + j ≤ 3) species and a first description of the chemical interaction between the carbon-containing and boron-containing subsystems through the three reactions BCl(3) + CH(4) ⇌ BCl(2)CH(3) + HCl, BHCl(2) + CH(4) ⇌ BCl(2)CH(3) + H(2), and BCl(2) + CH(4) ⇌ BHCl(2) + CH(3). A reaction mechanism is then proposed and used to perform some illustrative equilibrium and kinetic calculations in the context of chemical vapor deposition (CVD) of boron carbide. Our results show that the new addition-elimination reaction paths play a crucial role by lowering considerably the activation barrier with respect to previous theoretical evaluations; they also confirm that BCl(2)CH(3) is an important species in the mechanism.

  13. The inactivation of Chlorella spp. with dielectric barrier discharge in gas-liquid mixture

    NASA Astrophysics Data System (ADS)

    Song, Dan; Sun, Bing; Zhu, Xiaomei; Yan, Zhiyu; Liu, Hui; Liu, Yongjun

    2013-03-01

    The inactivation of Chlorella spp. with high voltage and frequency pulsed dielectric barrier discharge in hybrid gas-liquid reactor with a suspension electrode was studied experimentally. In the hybrid gas-liquid reactor, a steel plate was used as high voltage electrode while a quartz plate as a dielectric layer, another steel plate placing in the aqueous solution worked as a whole ground electrode. A suspension electrode is installed near the surface of solution between high voltage and ground electrode to make the dielectric barrier discharge uniform and stable, the discharge gap was between the quartz plate and the surface of the water. The effect of peak voltage, treatment time, the initial concentration of Chlorella spp. and conductivity of solution on the inactivation rate of Chlorella spp. was investigated, and the inactivation mechanism of Chlorella spp. preliminarily was studied. Utilizing this system inactivation of Chlorella spp., the inactivation rate increased with increasing of peak voltage, treatment time and electric conductivity. It was found that the inactivation rate of Chlorella spp. arrived at 100% when the initial concentration was 4 × 106 cells mL-1, and the optimum operation condition required a peak voltage of 20 kV, a treatment time of 10 min and a frequency of 7 kHz. Though the increasing of initial concentration of the Chlorella spp. contributed to the addition of interaction probability between the Chlorella spp. and O3, H2O2, high-energy electrons, UV radiation and other active substances, the total inactivation number raise, but the inactivation rate of the Chlorella spp. decreased.

  14. Analysis of algebraic reconstruction technique for accurate imaging of gas temperature and concentration based on tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Hui-Hui, Xia; Rui-Feng, Kan; Jian-Guo, Liu; Zhen-Yu, Xu; Ya-Bai, He

    2016-06-01

    An improved algebraic reconstruction technique (ART) combined with tunable diode laser absorption spectroscopy(TDLAS) is presented in this paper for determining two-dimensional (2D) distribution of H2O concentration and temperature in a simulated combustion flame. This work aims to simulate the reconstruction of spectroscopic measurements by a multi-view parallel-beam scanning geometry and analyze the effects of projection rays on reconstruction accuracy. It finally proves that reconstruction quality dramatically increases with the number of projection rays increasing until more than 180 for 20 × 20 grid, and after that point, the number of projection rays has little influence on reconstruction accuracy. It is clear that the temperature reconstruction results are more accurate than the water vapor concentration obtained by the traditional concentration calculation method. In the present study an innovative way to reduce the error of concentration reconstruction and improve the reconstruction quality greatly is also proposed, and the capability of this new method is evaluated by using appropriate assessment parameters. By using this new approach, not only the concentration reconstruction accuracy is greatly improved, but also a suitable parallel-beam arrangement is put forward for high reconstruction accuracy and simplicity of experimental validation. Finally, a bimodal structure of the combustion region is assumed to demonstrate the robustness and universality of the proposed method. Numerical investigation indicates that the proposed TDLAS tomographic algorithm is capable of detecting accurate temperature and concentration profiles. This feasible formula for reconstruction research is expected to resolve several key issues in practical combustion devices. Project supported by the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 61205151), the National Key Scientific Instrument and Equipment Development Project of China (Grant

  15. Analysis of algebraic reconstruction technique for accurate imaging of gas temperature and concentration based on tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Hui-Hui, Xia; Rui-Feng, Kan; Jian-Guo, Liu; Zhen-Yu, Xu; Ya-Bai, He

    2016-06-01

    An improved algebraic reconstruction technique (ART) combined with tunable diode laser absorption spectroscopy(TDLAS) is presented in this paper for determining two-dimensional (2D) distribution of H2O concentration and temperature in a simulated combustion flame. This work aims to simulate the reconstruction of spectroscopic measurements by a multi-view parallel-beam scanning geometry and analyze the effects of projection rays on reconstruction accuracy. It finally proves that reconstruction quality dramatically increases with the number of projection rays increasing until more than 180 for 20 × 20 grid, and after that point, the number of projection rays has little influence on reconstruction accuracy. It is clear that the temperature reconstruction results are more accurate than the water vapor concentration obtained by the traditional concentration calculation method. In the present study an innovative way to reduce the error of concentration reconstruction and improve the reconstruction quality greatly is also proposed, and the capability of this new method is evaluated by using appropriate assessment parameters. By using this new approach, not only the concentration reconstruction accuracy is greatly improved, but also a suitable parallel-beam arrangement is put forward for high reconstruction accuracy and simplicity of experimental validation. Finally, a bimodal structure of the combustion region is assumed to demonstrate the robustness and universality of the proposed method. Numerical investigation indicates that the proposed TDLAS tomographic algorithm is capable of detecting accurate temperature and concentration profiles. This feasible formula for reconstruction research is expected to resolve several key issues in practical combustion devices. Project supported by the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 61205151), the National Key Scientific Instrument and Equipment Development Project of China (Grant

  16. SEPARATION OF FLUID MIXTURES

    DOEpatents

    Lipscomb, R.; Craig, A.; Labrow, S.; Dunn, J.F.

    1958-10-28

    An apparatus is presented for separating gaseous mixtures by selectively freezing a constituent of the mixture and subsequently separating the frozen gas. The gas mixture is passed through a cylinder fltted with a cooling jacket, causing one gas to freeze on the walls of the cylinder. A set of scraper blades are provided in the interior of the cyllnder, and as the blades oscillate, the frozen gas is scraped to the bottom of the cylinder. Means are provided for the frozen material to pass into a heating chamber where it is vaporized and the product gas collected.

  17. The gas phase FTIR studies of chloroform + B and halothane + B (B = TMA, FCD3) mixtures

    NASA Astrophysics Data System (ADS)

    Rutkowski, K. S.; Melikova, S. M.; Asfin, R. E.; Czarnik-Matusewicz, B.; Rospenk, M.

    2014-08-01

    An infrared and ab initio (MP2/6-311++G(2d,2p)) study of complexes of chloroform (Cl3CH(D)) and halothane (CHClBrCF3) with weak - methyl fluoride (FCD3) and strong - trimethylamine (N(CH(D)3)3tbnd TMA) proton acceptors in the gas phase near the room temperature is presented. The so called blue shifting hydrogen bond has been identified in the former case and the formation of conventional H-bond with the red frequency shift of CH stretching vibration of the proton donors was observed in the latter case. An attempt of temperature spectroscopic measurements has been made for the systems studied to estimate the formation energy. In the case of Cl3CD…N(CH3)3 complex this value equals -23(2) kJ/mol. The results obtained in ab inito calculations generally agree with those obtained in IR spectroscopic measurements, however they overestimate the frequency shift caused by the complex formation, especially in the case of the red-shifting H-bonds. Possible origin of such overestimation is discussed shortly.

  18. Isobutanol-methanol mixtures from synthesis gas. Quarterly technical progress report, July 1--September 30, 1995

    SciTech Connect

    Eglesia, E.

    1995-10-24

    Mechanistic and kinetic studies of methanol and ethanol coupling reactions on Cs/Cu/ZnO and Cu/ZnO/MnO catalysts using isotopically-labeled compounds have confirmed that coupling reactions proceed via intermediate dehydrogenation of alcohols to aldehydes. Ethanol coupling reactions are much faster than those of methanol because ethanol forms a more thermodynamically favored intermediate (acetaldehyde), with aldol condensation pathways kinetically available for chain growth. Cs decreases the rate of formation of aldehydes in alcohol dehydrogenation reaction and inhibits the undesired conversion of methanol and ethanol to synthesis gas (CO/H{sub 2}). Construction and start-up of the Catalytic Microreactor Unit (CMRU) for high pressure isobutanol synthesis studies have been completed. Initial certification runs have reproduced catalytic CO conversion rates on a standard APCI material (Cs/Cu/ZnO/Al{sub 2}O{sub 3}). Condensation of higher alcohols in the transfer lines appears to be responsible for the observed low apparent selectivity to higher alcohols. The design and construction of the Temperature-Programmed Surface Reaction (TPSR) Unit for the study of the adsorption and reaction properties of alcohols and other oxygenates on isobutanol, synthesis catalysts and components is complete. The reduction of CuO powder and of a Cs/Cu/ZnO catalyst were used to certify the apparatus before proceeding with alcohol adsorption and reaction studies.

  19. Separation of vapour and gas mixtures using a thin zeolite MFI membrane

    SciTech Connect

    Vroon, Z.A.E.P.; Gilde, M.J.; Kiezer, K.

    1994-12-31

    Zeolite MFI composite membranes were prepared by in situ crystallisation. A very thin (L < 5 {mu}m) polycrystalline MFI layer was grown on a flat {alpha}-Al{sub 2}O{sub 3} support (pore radii 80 nm). XRD and SEM showed that the layer was built of small MFI particles ({+-}200 nm). The single gas flux of methane, n-butane and iso-butane are respectively 9.7, 2.7 and 0.032 10{sup -3} mol.m{sup -2}.s{sup -1} at 25{degrees}C and 100 kPa. The separation of n-butane/methane is reversible. At 25{degrees}C it is possible to separate n-butane from methane. At 200{degrees}C it is possible to separate methane from n-butane. The separation factor for 50 n-butane/50 iso-butane is 26 at 50{degrees}C. Experiments with large molecules showed that the zeolite MFI membrane contains no pores larger than inherent to the zeolite.

  20. NATURE OF UNRESOLVED COMPLEX MIXTURE IN SIZE-DISTRIBUTED EMISSIONS FROM RESIDENTIAL WOOD COMBUSTION AS MEASURED BY THERMAL DESORPTION-GAS CHROMATOGRAPHY-MASS SPECTROMETRY

    EPA Science Inventory

    In this study, the unresolved complex mixture (UCM) in size resolved fine aerosol emissions from residential wood combustion (RWC) is examined. The aerosols are sorted by size in an electrical low-pressure impactor (ELPI) and subsequently analyzed by thermal desorbtion/gas chroma...

  1. Mathematical simulation of gas-liquid mixture flow in a reservoir and a wellbore with allowance for the dynamical interactions in the reservoir-well system

    NASA Astrophysics Data System (ADS)

    Abbasov, E. M.; Feyzullayev, Kh. A.

    2016-01-01

    Fluid dynamic processes related to mature oil field development are simulated by applying a numerical algorithm based on the gas-liquid mixture flow equations in a reservoir and a wellbore with allowance for the dynamical interaction in the reservoir-well system. Numerical experiments are performed in which well production characteristics are determined from wellhead parameters.

  2. Easy and accurate calculation of programmed temperature gas chromatographic retention times by back-calculation of temperature and hold-up time profiles.

    PubMed

    Boswell, Paul G; Carr, Peter W; Cohen, Jerry D; Hegeman, Adrian D

    2012-11-01

    Linear retention indices are commonly used to identify compounds in programmed-temperature gas chromatography (GC), but they are unreliable unless the original experimental conditions used to measure them are stringently reproduced. However, differences in many experimental conditions may be properly taken into account by calculating programmed-temperature retention times of compounds from their measured isothermal retention vs. temperature relationships. We call this approach "retention projection". Until now, retention projection has been impractical because it required very precise, meticulous measurement of the temperature vs. time and hold-up time vs. temperature profiles actually produced by a specific GC instrument to be accurate. Here we present a new, easy-to-use methodology to precisely measure those profiles: we spike a sample with 25 n-alkanes and use their measured, programmed-temperature retention times to precisely back-calculate what the instrument profiles must have been. Then, when we use those back-calculated profiles to project retention times of 63 chemically diverse compounds, we found that the projections are extremely accurate (e.g. to ±0.9 s in a 40 min ramp). They remained accurate with different temperature programs, GC instruments, inlet pressures, flow rates, and with columns taken from different batches of stationary phase while the accuracy of retention indices became worse the more the experimental conditions were changed from the original ones used to measure them. We also developed new, open-source software (http://www.retentionprediction.org/gc) to demonstrate the system.

  3. Automated gas-phase purification for accurate, multiplexed quantification on a stand-alone ion trap mass spectrometer

    PubMed Central

    Vincent, Catherine E.; Rensvold, Jarred W.; Westphall, Michael S.; Pagliarini, David J.; Coon, Joshua J.

    2012-01-01

    Isobaric tagging enables the acquisition of highly-multiplexed proteome quantification but is hindered by the pervasive problem of precursor interference. The elimination of co-isolated contaminants prior to reporter tag generation can be achieved through the use of gas-phase purification via proton transfer ion/ion reactions (QuantMode); however, the original QuantMode technique was implemented on the high resolution linear ion trap-Orbitrap hybrid mass spectrometer enabled with electron transfer dissociation (ETD). Here we extend this technology to stand-alone linear ion trap systems (trapQuantMode). Facilitated by the use of inlet beam-type activation (i.e., trapHCD) for production and observation of the low mass-to-charge reporter region, this scan sequence comprises three separate events to maximize peptide identifications, minimize duty cycle requirements, and increase quantitative accuracy, precision, and dynamic range. Significant improvements in quantitative accuracy were attained over standard methods when using trapQuantMode (trapQM) to analyze an interference model system comprising tryptic peptides of yeast that we contaminated with human peptides. Finally, we demonstrate practical benefits of this method by analysis of the proteomic changes that occur during mouse skeletal muscle myoblast differentiation. While trapQM’s reduced duty cycle led to the identification of fewer proteins than conventional operation (4,050 vs. 2,964), trapQM identified more significant differences (>1.5 fold, 1,362 vs 1,132, respectively; P<0.05) between the proteomes of undifferentiated myoblasts and differentiated myotubes and nearly ten-fold more differences with changes greater than 5-fold (96 vs. 12). We further show that our trapQM dataset is superior for identifying changes in protein abundance that are consistent with the metabolic and structural changes known to accompany myotube formation. PMID:23046161

  4. Silicon etch using SF{sub 6}/C{sub 4}F{sub 8}/Ar gas mixtures

    SciTech Connect

    Bates, Robert L.; Stephan Thamban, P. L.; Goeckner, Matthew J.; Overzet, Lawrence J.

    2014-07-01

    While plasmas using mixtures of SF{sub 6}, C{sub 4}F{sub 8}, and Ar are widely used in deep silicon etching, very few studies have linked the discharge parameters to etching results. The authors form such linkages in this report. The authors measured the optical emission intensities of lines from Ar, F, S, SF{sub x}, CF{sub 2}, C{sub 2}, C{sub 3}, and CS as a function of the percentage C{sub 4}F{sub 8} in the gas flow, the total gas flow rate, and the bias power. In addition, the ion current density and electron temperature were measured using a floating Langmuir probe. For comparison, trenches were etched of various widths and the trench profiles (etch depth, undercut) were measured. The addition of C{sub 4}F{sub 8} to an SF{sub 6}/Ar plasma acts to reduce the availability of F as well as increase the deposition of passivation film. Sulfur combines with carbon in the plasma efficiently to create a large optical emission of CS and suppress optical emissions from C{sub 2} and C{sub 3}. At low fractional flows of C{sub 4}F{sub 8}, the etch process appears to be controlled by the ion flux more so than by the F density. At large C{sub 4}F{sub 8} fractional flows, the etch process appears to be controlled more by the F density than by the ion flux or deposition rate of passivation film. CF{sub 2} and C{sub 2} do not appear to cause deposition from the plasma, but CS and other carbon containing molecules as well as ions do.

  5. A new method for sustained generation of ultra-pure nitric oxide-containing gas mixtures via controlled UVA-photolysis of nitrite solutions.

    PubMed

    Opländer, Christian; Baschin, Marcel; van Faassen, Ernst E; Born, Matthias; Möller, Manfred; Pallua, Norbert; Suschek, Christoph V

    2010-12-15

    Exogenous gaseous nitric oxide (gNO) is an FDA approved drug for treatment of a variety of human pathologies like Persistent Pulmonary Hypertension in neonates and premature babies, skin lesions and fungal dermatophyte infections. Substantial disadvantages of current gNO-based therapies are the high therapy costs, high storage costs of the gas cylinders, and the rapid contamination of compressed NO gases with various decomposition products. Here we describe a new, very simple, and inexpensive photolytic generator of uncontaminated NO-containing gas mixtures at therapeutic concentrations. The new method bases on UVA-induced and redox-assisted decomposition of nitrite ions in aqueous solutions. NO formation via UVA-induced photolysis of nitrite is accompanied by an OH radical-dependent production of NO(2) that beside its toxic character additionally strongly reduces the NO yield by consuming NO in its reaction to N(2)O(3). During the UVA-induced photodecomposition process both, inhibition of NO(2) formation or NO(2) depletion by antioxidants hinders the NO-consuming reaction with NO(2) and ensured a maximal purity and maximal yield of NO-containing gas mixtures. Therefore, NO-containing gas mixtures generated by the described method are suitable for medical applications like inhalation or gassing of chronic non-healing wounds. Control of temperature, UVA intensity and composition of the reaction mixture allows facile control over the final NO level in the carrier gas over a wide concentration range. We demonstrate the sustained and stable release of NO over a wide dynamic range (10-5000 ppm NO) for many hours. The method avoids contamination-prone long time storage of NO gas. As such, it appears particularly relevant for applications involving the additional presence of oxygen (e.g. inhalation).

  6. Greenhouse gas production in mixtures of soil with composted and noncomposted biochars is governed by char-associated organic compounds.

    PubMed

    Borchard, Nils; Spokas, Kurt; Prost, Katharina; Siemens, Jan

    2014-05-01

    Biochar application to soil has the potential to increase soil productivity while reducing anthropogenic greenhouse gas (GHG) emissions to the atmosphere. However, techniques for conditioning this material for maximizing its effects as a soil amendment require elucidation. We examined changes of organic matter associated with two biochars after 175 d of composting and the resulting effects on GHG emissions during a 150-d incubation period. Composting decreased the amount of organic compounds that could be thermally released from the biochars and affected their molecular nature. These thermally desorbable organic compounds from initial biochars likely stimulated the oxidation of CH and inhibited the production of NO in soil-biochar mixtures. However, these reductions of GHG emissions disappeared together with thermally desorbable organic compounds after the composting of chars. Instead, addition of composted gasification coke and charcoal stimulated the formation of CH and increased NO emissions by 45 to 56%. Nitrous oxide emissions equaled 20% of the total amount of N added with composted biochars, suggesting that organic compounds and N sorbed by the chars during composting fueled GHG production. The transient nature of the suppression of CH and NO production challenges the long-term GHG mitigation potential of biochar in soil.

  7. Characterisation and fingerprinting of PCBs in flue gas and ash from waste incineration and in technical mixtures.

    PubMed

    Jansson, Stina; Lundin, Lisa; Grabic, Roman

    2011-10-01

    Congener patterns of mono- to deca-chlorinated biphenyls (PC1-10B) were evaluated in (a) waste incineration flue gases collected in the post-combustion zone of a laboratory-scale fluidized-bed reactor, (b) ashes from two different MSW incineration plants, and (c) published data of eight Aroclor formulations. The congener patterns of the flue gases, ashes, and Aroclor mixtures clearly differed from each other, likely reflecting differences in formation pathways. The flue gas congener patterns were largely dominated by the least chlorinated congeners, whereas the ashes displayed more evenly distributed patterns. The most abundant congeners indicated a preference for 3,3',4,4'-oriented substitution, which may be related to de novo-type formation involving perylene. Principal component analysis confirmed that congener patterns differed among the three matrices and also distinguished flue gases collected at 200 °C from those collected at 300 °C and 450 °C. This distinction could be partly explained by the degree of chlorination, although the substitution status of the ortho-position, and substitution in the 3,3',4,4'-positions also seemed to be influential. Injecting biphenyl into the post-combustion zone of the reactor did not alter the patterns, indicating that availability of the backbone structure is not a limiting factor for PCB formation. PMID:21885088

  8. Correction of aspect ratio dependency in deep silicon etch using SF6/C4F8/Ar gas mixture

    NASA Astrophysics Data System (ADS)

    Bates, Robert Lee

    The etch rate of deep features in silicon, such as trenches and vias, can vary significantly with the changing Aspect Ratio (AR) of the feature. Developing a better understanding of the complex volumetric and surface chemistry as well as the etching mechanisms controlling the Aspect Ratio Dependent Etch-rate (ARDE) continues to present research opportunities. Recall that ARDE is generally characterized by small AR features etching at faster rates than large AR features. The main causes of ARDE include Knudsen transport of neutrals into and out of the features as well as ion and neutral loss to the walls due to angular spread in the velocity distribution function and differential charging of insulating microstructures. This work focuses on using a continuous plasma process utilizing a gas mixture of SF6/C4F8/Ar to produce trenches of varying widths and depths. The experimental results were obtained using a Plasma-Therm Versaline processing system. Experiments were performed to show that the etch rate of low AR features can be reduced through the deposition of a passivation layer and thereby allow larger AR features to catch up. It is also possible to invert the ARDE in certain circumstances. We will present the insights we have gained into the ARDE process and the solutions we have tested.

  9. Two-dimensional simulation of the development of an inhomogeneous volume discharge in a Ne/Xe/HCl gas mixture

    SciTech Connect

    Bychkov, Yu. I. Yampolskaya, S. A.; Yastremskii, A. G.

    2013-05-15

    The kinetic processes accompanying plasma column formation in an inhomogeneous discharge in a Ne/Xe/HCl gas mixture at a pressure of 4 atm were investigated by using a two-dimensional model. Two cathode spots spaced by 0.7 cm were initiated by distorting the cathode surface at local points, which resulted in an increase in the field strength in the cathode region. Three regimes differing in the charging voltage, electric circuit inductance, and electric field strength at the local cathode points were considered. The spatiotemporal distributions of the discharge current; the electron density; and the densities of excited xenon atoms, HCl(v = 0) molecules in the ground state, and HCl(v > 0) molecules in vibrational levels were calculated. The development of the discharge with increasing the electron density from 10{sup 4} to 10{sup 16} cm{sup -3} was analyzed, and three characteristic stages in the evolution of the current distribution were demonstrated. The width of the plasma column was found to depend on the energy deposited in the discharge. The width of the plasma column was found to decrease in inverse proportion to the deposited energy due to spatiotemporal variations in the rates of electron production and loss. The calculated dependences of the cross-sectional area of the plasma column on the energy deposited in the discharge agree with the experimental results.

  10. Aqueous solubility calculation for petroleum mixtures in soil using comprehensive two-dimensional gas chromatography analysis data.

    PubMed

    Mao, Debin; Lookman, Richard; Van De Weghe, Hendrik; Vanermen, Guido; De Brucker, Nicole; Diels, Ludo

    2009-04-01

    An assessment of aqueous solubility (leaching potential) of soil contaminations with petroleum hydrocarbons (TPH) is important in the context of the evaluation of (migration) risks and soil/groundwater remediation. Field measurements using monitoring wells often overestimate real TPH concentrations in case of presence of pure oil in the screened interval of the well. This paper presents a method to calculate TPH equilibrium concentrations in groundwater using soil analysis by high-performance liquid chromatography followed by comprehensive two-dimensional gas chromatography (HPLC-GCXGC). The oil in the soil sample is divided into 79 defined hydrocarbon fractions on two GCXGC color plots. To each of these fractions a representative water solubility is assigned. Overall equilibrium water solubility of the non-aqueous phase liquid (NAPL) present in the sample and the water phase's chemical composition (in terms of the 79 fractions defined) are then calculated using Raoult's law. The calculation method was validated using soil spiked with 13 different TPH mixtures and 1 field-contaminated soil. Measured water solubilities using a column recirculation equilibration experiment agreed well to calculated equilibrium concentrations and water phase TPH composition.

  11. First fully-synthetic standard gas mixtures with atmospheric isotopic composition for global CO2 and CH4 monitoring

    NASA Astrophysics Data System (ADS)

    Brewer, Paul

    2014-05-01

    As the requirement for data that is comparable to the World Meteorological Organisation (WMO) scale increases, there is a corresponding increase in the demand for comparable reference standards. An infrastructure to disseminate gravimetric reference standards that are traceable to the International System of Units (SI) offers a means of broadening availability. These could overcome the cost and complexity of sampling air under global background conditions which can only be carried out at remote locations. It promises the possibility for the provision of standards from more than one source and would be enabled and supported by the global agreement under the International Committee for Weights and Measures (CIPM) Mutual Recognition Arrangement (MRA) to which the WMO became a signatory is 2010. We report the first fully- synthetic gaseous reference standards of CO2 and CH4 in a whole air matrix with an isotopic distribution matching that in the ambient atmosphere. The mixtures are accurately representative of the ambient atmosphere and were prepared gravimetrically. The isotopic distribution of the CO2 was matched to the abundance in the ambient atmosphere by blending 12C enriched CO2 with 13C enriched CO2 in order to avoid measurement biases, introduced by measurement instrumentation detecting only certain isotopologues. The reference standards demonstrate excellent comparability to the WMO scale. This work is a valuable step towards enabling the wider dissemination of traceability for these atmospheric components. Since these standards are prepared synthetically, they can be replicated and avoid the complexity of sampling whole air in global background locations. They are a significant step towards making suitable reference standards for global atmospheric monitoring available more widely.

  12. A new developed velocity of sound measurement device for characterization of multi-component gas mixtures under elevated temperatures and pressures.

    PubMed

    Seibel, C; Suedmeyer, J; Fieback, T M

    2014-07-01

    Inline process control by measurement of velocity of sound of fluids is a direct and comprehensive technique [J. D. N. Cheeke and Z. Wang, "Acoustic wave gas sensors," Sens. Actuators B 59, 146-153 (1999); J. W. Grate, S. J. Martin, and R. M. White, "Acoustic wave microsensors," Anal. Chem. 65, 1868 (1993)]. Depending on the varying conditions of measuring fluid(s), temperatures and pressures, it is a challenging task to find the best possible acoustic setup. Taking this background into account, a velocity of sound measurement device for temperatures up to 475 K and pressures up to 24 MPa was designed and assembled that is to be used for testing different resonator types. Two bulk acoustic wave resonators out of the commonly used lead zirconatetitanate compound (PZT) were tested at different test fluids under temperatures up to 423.15 K and pressures up to 24 MPa [S. Gebhardt, L. Seffner, F. Schlenkirch, and A. Schönecker, "PZT thick films for sensor and actuator applications," J. Eur. Ceram. Soc. 27, 4177-4180 (2007)]. Initially the pure gases methane, ethane, carbon dioxide, nitrogen, and helium were measured, followed by multi-component gas mixtures. Beside methane-based binary and ternary gas mixtures, a quaternary gas mixture comprising methane, ethane, carbon dioxide, and helium was analyzed. Results for all measurement fluids in a broad temperature and pressure range show a relative deviation to theoretical values derived from GERG-2008 smaller than 0.5%.

  13. Kinetic boundary layers in gas mixtures: Systems described by nonlinearly coupled kinetic and hydrodynamic equations and applications to droplet condensation and evaporation

    SciTech Connect

    Widder, M.E.; Titulaer, U.M. )

    1993-03-01

    The authors consider a mixture of heavy vapor molecules and a light carrier gas surrounding a liquid droplet. The vapor is described by a variant of the Klein-Kramers equation; the gas is described by the Navier-Stokes equations; the droplet acts as a heat source due to the released heat of condensation. The exchange of momentum and energy between the constituents of the mixture is taken into account by force terms in the kinetic equation and source terms in the Navier-Stokes equations. These are chosen to obtain maximal agreement with the irreversible thermodynamics of a gas mixture. The structure of the kinetic boundary layer around the sphere is determined from the self-consistent solution of this set of coupled equations with appropriate boundary conditions at the surface of the sphere. The kinetic equation is rewritten as a set of coupled moment equations. A complete set of solutions of these moment equations is constructed by numerical integration inward from the region far away from the droplet, where the background inhomogeneities are small. A technique developed earlier is used to deal with the numerical instability of the moment equations. The solutions obtained for given temperature and pressure profiles in the gas are then combined linearly such that they obey the boundary conditions at the droplet surface; from this solution source terms for the Navier-Stokes equation of the gas are constructed and used to determine improved temperature and pressure profiles for the background gas. For not too large temperature differneces between the droplet and the gas at infinity, self-consistency is reached after a few iterations. The method is applied to the condensation of droplets from a supersaturated vapor as well as to strong evaporation of droplets under the influence of an external heat source, where corrections of up to 40% are obtained.

  14. Metabolic profiling of yeast culture using gas chromatography coupled with orthogonal acceleration accurate mass time-of-flight mass spectrometry: application to biomarker discovery.

    PubMed

    Kondo, Elsuida; Marriott, Philip J; Parker, Rhiannon M; Kouremenos, Konstantinos A; Morrison, Paul; Adams, Mike

    2014-01-01

    Yeast and yeast cultures are frequently used as additives in diets of dairy cows. Beneficial effects from the inclusion of yeast culture in diets for dairy mammals have been reported, and the aim of this study was to develop a comprehensive analytical method for the accurate mass identification of the 'global' metabolites in order to differentiate a variety of yeasts at varying growth stages (Diamond V XP, Yea-Sacc and Levucell). Microwave-assisted derivatization for metabolic profiling is demonstrated through the analysis of differing yeast samples developed for cattle feed, which include a wide range of metabolites of interest covering a large range of compound classes. Accurate identification of the components was undertaken using GC-oa-ToFMS (gas chromatography-orthogonal acceleration-time-of-flight mass spectrometry), followed by principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) for data reduction and biomarker discovery. Semi-quantification (fold changes in relative peak areas) was reported for metabolites identified as possible discriminative biomarkers (p-value <0.05, fold change >2), including D-ribose (four fold decrease), myo-inositol (five fold increase), L-phenylalanine (three fold increase), glucopyranoside (two fold increase), fructose (three fold increase) and threitol (three fold increase) respectively. PMID:24356230

  15. Assessment of gas chromatography time-of-flight accurate mass spectrometry for identification of volatile and semi-volatile compounds in honey.

    PubMed

    Moniruzzaman, M; Rodríguez, I; Ramil, M; Cela, R; Sulaiman, S A; Gan, S H

    2014-11-01

    The performance of gas chromatography (GC) combined with a hybrid quadrupole time-of-flight (QTOF) mass spectrometry (MS) system for the determination of volatile and semi-volatile compounds in honey samples is evaluated. After headspace (HS) solid-phase microextraction (SPME) of samples, the accurate mass capabilities of the above system were evaluated for compounds identification. Accurate scan electron impact (EI) MS spectra allowed discriminating compounds displaying the same nominal masses, but having different empirical formulae. Moreover, the use of a mass window with a width of 0.005 Da provided highly specific chromatograms for selected ions, avoiding the contribution of interferences to their peak areas. Additional information derived from positive chemical ionization (PCI) MS spectra and ion product scan MS/MS spectra permitted confirming the identity of novel compounds. The above possibilities are illustrated with examples of honey aroma compounds, belonging to different chemical classes and containing different elements in their molecules. Examples of compounds whose structures could not be described are also provided. Overall, 84 compounds, from a total of 89 species, could be identified in 19 honey samples from 3 different geographic areas in the world. The suitability of responses measured for selected ions, corresponding to above species, for authentication purposes is assessed through principal components analysis. PMID:25127626

  16. Numerical Description of Acoustic Vibrations of a Vapor-Gas-Droplet Mixture in a Closed Channel Based on a One-Velocity, One-Temperature Model

    NASA Astrophysics Data System (ADS)

    Bayanov, R. I.; Tukmakov, A. L.

    2015-05-01

    The paper describes a mathematical model and the results of numerical calculations of resonance acoustic vibrations of a vapor-gas-droplet mixture in a closed volume under the action of periodic acoustic waves generated by a harmonically vibrating piston. The numerical method of solving the equations of the model is based on MacCormack's scheme. The model of equilibrium phase transitions used in the numerical scheme has allowed a chart of regimes of the vapor-gas-droplet mixture vibrations to be constructed depending on the initial vapor content. In accordance with the piston vibration amplitude, the limit of the critical vapor content below which vapor condensation is impossible has been found.

  17. Carbon dioxide laser with an e-beam-initiated discharge produced in the working gas mixture at a pressure up to 5 atm

    SciTech Connect

    Orlovskii, Viktor M; Alekseev, S B; Tarasenko, Viktor F

    2011-11-30

    A high-pressure CO{sub 2} laser with a discharge initiated by an electron beam of sub-nanosecond duration in the laser gas mixture at a pressure up to 5 atm is fabricated. For the 20-ns pulses the energy from the active volume {approx} 4 cm{sup 3} amounted to 40 mJ. The laser operation at a pulse repetition rate up to 5 Hz is demonstrated. In the gas mixture CO{sub 2}:N{sub 2}:He = 1:1:6 at a pressure 5 atm, the specific energy deposition of {approx} 0.07 J cm{sup -3} atm{sup -1} is obtained in the process of a non-self-sustained discharge with ionisation amplification.

  18. Transmission of complex sound signals in the human respiratory system as a function of sound velocity in the utilized gas mixture

    NASA Astrophysics Data System (ADS)

    Korenbaum, V. I.; D'Yachenko, A. I.; Nuzhdenko, A. V.; Lopatkin, N. S.; Tagil'Tsev, A. A.; Kostiv, A. E.

    2011-11-01

    The previously revealed effect of the simultaneous existence of two sound transmission paths in human lungs is confirmed on an expanded sampling of 25 people for three different types of sounding signals during respiration of three gas mixtures. The obtained dependences of sounding signal arrival times above the trachea and the lower right zone of the lungs on sound velocity in the respiratory gas mixture filling human lungs have made it possible to link the first of these paths to partial sound propagation over lumens of respiratory ways (air-structural mechanism), and the second, to sound propagation over lung tissue (structural mechanism). We have evaluated the length of the sound propagation path along the lung parenchyma for the part of the sounding signal transmitted to the lower right zone of the lungs via the air-structural mechanism; this length during respiration is within the limits of 3.6-2.0 cm.

  19. Reactor simulations of the GEC reference cell reactor with an ICP source for Ar/Cl2 and BCl3/Cl2 gas mixtures.

    NASA Astrophysics Data System (ADS)

    Veerasingam, Ramana; Choi, Seung J.; Riley, Merle; Hoekstra, Robert; Kushner, Mark

    1996-10-01

    The ICP (inductively coupled plasma) device is a widely researched plasma etching technology to meet the stringent requirements of dielectric and metal etch for the next generation semiconductor wafers. At Sandia, the GEC reference cell has been modified to include a planar coil geometry to couple the RF power to the plasma inductively. Measurements of densities of electrons, CL-, Ar+, and recently of ion current flux have been made. In this paper, we will present results of simulations modeling the GEC cell for Ar/CL2 and BCL3/Cl2 gas mixtures using the HPEM and GEMINI code packages. Results will be parametrized with power, pressure, and gas mixture. In addition, simulations of the ion current flux using a sheath model developed at Sandia and the HPEM will be performed and compared to data.

  20. Short pulse formation in a TEA CO{sub 2} laser using a CO{sub 2} - N{sub 2} - H{sub 2} gas mixture

    SciTech Connect

    Ivashchenko, M V; Karapuzikov, A I; Sherstov, I V

    2001-11-30

    The use of an optimal CO{sub 2} - N{sub 2} - H{sub 2} gas mixture with a high concentration of hydrogen (30% - 40%) was shown to allow the formation of high-power TEA CO{sub 2}-laser pulses with a base duration of {approx} 200 ns whose energy and peak power significantly exceed the parameters of pulses obtained in binary CO{sub 2} - H{sub 2} mixtures. Considering all the parameters, the helium-free 56% CO{sub 2} - 14% N{sub 2} - 30% H{sub 2} gas mixture at a pressure of 0.7 atm is optimal for the generation of short high-power pulses in the TEA CO{sub 2} laser. A small addition of nitrogen ([CO{sub 2}]/[N{sub 2}] {approx} 10 - 12) to the binary CO{sub 2} - H{sub 2} mixture not only substantially increases the pulse energy and peak power (by a factor of 3 - 3.5) but also shortens their duration at half-maximum with retention of the total (base) duration. (control of laser radiation parameters)

  1. Pressure dependence of the mixing rate for the free convection of a binary gas mixture in a two-flask apparatus

    NASA Astrophysics Data System (ADS)

    Aleksandrov, O. E.; Seleznev, V. D.

    2016-07-01

    A theoretical model of steady-state mixing is considered for a binary gas mixture under conditions of free gravitational convection in a vertical channel with impenetrable walls that connects two flasks. It is shown that the mixing rate in the supercritical regime has a peak and then deceases monotonically with increasing pressure. The experimental results are shown to be in good agreement with theoretical data.

  2. High altitude chemically reacting gas particle mixtures. Volume 1: A theoretical analysis and development of the numerical solution. [rocket nozzle and orbital plume flow fields

    NASA Technical Reports Server (NTRS)

    Smith, S. D.

    1984-01-01

    The overall contractual effort and the theory and numerical solution for the Reacting and Multi-Phase (RAMP2) computer code are described. The code can be used to model the dominant phenomena which affect the prediction of liquid and solid rocket nozzle and orbital plume flow fields. Fundamental equations for steady flow of reacting gas-particle mixtures, method of characteristics, mesh point construction, and numerical integration of the conservation equations are considered herein.

  3. A new portable generator to dynamically produce SI-traceable reference gas mixtures for VOCs and water vapour at atmospheric concentration

    NASA Astrophysics Data System (ADS)

    Guillevic, Myriam; Pascale, Céline; Ackermann, Andreas; Leuenberger, Daiana; Niederhauser, Bernhard

    2016-04-01

    In the framework of the KEY-VOCs and AtmoChem-ECV projects, we are currently developing new facilities to dynamically generate reference gas mixtures for a variety of reactive compounds, at concentrations measured in the atmosphere and in a SI-traceable way (i.e. the amount of substance fraction in mole per mole is traceable to SI-units). Here we present the realisation of such standards for water vapour in the range 1-10 μmol/mol and for volatile organic compounds (VOCs) such as limonene, alpha-pinene, MVK, MEK, in the nmol/mol range. The matrix gas can be nitrogen or synthetic air. Further development in gas purification techniques could make possible to use purified atmospheric air as carrier gas. The method is based on permeation and dynamic dilution: one permeator containing a pure substance (either water, limonene, MVK, MEK or α-pinene) is kept into a permeation chamber with a constant gas flow. The mass loss is precisely calibrated using a magnetic suspension balance. The carrier gas is purified beforehand from the compounds of interest to the required level, using commercially available purification cartridges. This primary mixture is then diluted to reach the required amount of substance fraction. All flows are piloted by mass flow controllers which makes the production process flexible and easily adaptable to generate the required concentration. All parts in contact with the gas mixture are passivated using coated surfaces, to reduce adsorption/desorption processes as much as possible. Two setups are currently developed: one already built and fixed in our laboratory in Bern as well as a portable generator that is still under construction and that could be used anywhere in the field. The permeation chamber of the portable generator has multiple individual cells allowing the generation of mixtures up to 5 different components if needed. Moreover the presented technique can be adapted and applied to a large variety of molecules (e.g., NO2, BTEX, CFCs

  4. Initiation of ignition of a combustible gas mixture in a closed volume by the radiation of a high-power pulsed CO2 laser

    NASA Astrophysics Data System (ADS)

    Kazantsev, S. Yu; Kononov, I. G.; Kossyi, I. A.; Popov, N. A.; Tarasova, N. M.; Firsov, K. N.

    2012-01-01

    The results of experiments on initiating the ignition of a CH4 — O2 — SF6 triple gas mixture in a closed volume by the radiation of a high-power CO2 laser are presented. It is shown that spatially nonuniform (in the direction of the laser beam) gas heating by the laser radiation leads to formation of a fast combustion wave, propagating along the chamber axis and giving rise to 'instantaneous' ignition. At the threshold value 16.5 J of the laser radiation energy the fast combustion wave is transformed into a detonation wave, which causes an explosion and destruction of the reaction chamber

  5. Measurement of electron drift, diffusion, and effective ionization coefficients in the SF6 CHF3 and SF6 CF4 gas mixtures

    NASA Astrophysics Data System (ADS)

    de Urquijo, J.; Basurto, E.; Hernández-Ávila, J. L.

    2003-12-01

    The electron drift velocity, the longitudinal diffusion coefficient, the effective ionization coefficient and the limiting field strength for mixtures of SF6 with CHF3 and CF4 have been measured with a pulsed Townsend technique. The overall density-reduced electric field strength, E/N, could be varied between 60 and 520 Td (1 Td = 10-17 V cm2), while the SF6 content in the gas mixtures was varied over the range 1-50%. We have found that the electron drift velocity and the density-normalized longitudinal diffusion coefficient vary weakly with the amount of SF6 in the mixture. In contrast, the effective ionization coefficient shows a strong dependence with the SF6 content, becoming more electronegative as the amount of SF6 is increased. The measured limiting field strength for these two mixtures is lower than those for SF6-N2. To our knowledge, no previous ionization or electron transport data for these mixtures have been published.

  6. Effective ionization coefficients, limiting electric fields, and electron energy distributions in CF3I + CF4 + Ar ternary gas mixtures

    NASA Astrophysics Data System (ADS)

    Tezcan, S. S.; Dincer, M. S.; Bektas, S.

    2016-07-01

    This paper reports on the effective ionization coefficients, limiting electric fields, electron energy distribution functions, and mean energies in ternary mixtures of (Trifluoroiodomethane) CF3I + CF4 + Ar in the E/N range of 100-700 Td employing a two-term solution of the Boltzmann equation. In the ternary mixture, CF3I component is increased while the CF4 component is reduced accordingly and the 40% Ar component is kept constant. It is seen that the electronegativity of the mixture increases with increased CF3I content and effective ionization coefficients decrease while the limiting electric field values increase. Synergism in the mixture is also evaluated in percentage using the limiting electric field values obtained. Furthermore, it is possible to control the mean electron energy in the ternary mixture by changing the content of CF3I component.

  7. Deposition and characterization of organic polymer thin films using a dielectric barrier discharge with different C2Hm/N2 (m = 2, 4, 6) gas mixtures

    NASA Astrophysics Data System (ADS)

    Chandrashekaraiah, Thejaswini Halethimmanahally; Bogdanowicz, Robert; Danilov, Vladimir; Schäfer, Jan; Meichsner, Jürgen; Hippler, Rainer

    2015-06-01

    Organic polymer thin films have been deposited on Si(100) and aluminum coated glass substrates by a dielectric barrier discharge (DBD) operated at medium pressure using different C2H m /N2 ( m = 2, 4, 6) gas mixtures. The deposited films were characterized by various spectroscopic techniques. Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS) revealed the chemical functional groups present in the films. The surface chemical compositions have been derived from X-ray photo electron spectroscopy (XPS). FT-IRRAS and XPS show the presence of sp, s p 2 and s p 3 bonds of carbon and nitrogen. Various functional groups such as NH containing, saturated and unsaturated alkyl groups have been identified. Thin films obtained from C2H2/N2 and C2H4/N2 gas mixtures revealed a higher N/C ratio when compared to thin films obtained from C2H6/N2. Thickness, refractive index and extinction coefficient were evaluated by spectroscopic ellipsometry (SE). Significant differences between the films obtained with different gas mixtures are observed.

  8. Deposition and characterization of organic polymer thin films using a dielectric barrier discharge with different C2Hm/N2 (m = 2, 4, 6) gas mixtures

    NASA Astrophysics Data System (ADS)

    Halethimmanahally Chandrashekaraiah, Thejaswini; Bogdanowicz, Robert; Danilov, Vladimir; Schäfer, Jan; Meichsner, Jürgen; Hippler, Rainer

    2015-06-01

    Organic polymer thin films have been deposited on Si(100) and aluminum coated glass substrates by a dielectric barrier discharge (DBD) operated at medium pressure using different C2Hm/N2 (m = 2, 4, 6) gas mixtures. The deposited films were characterized by various spectroscopic techniques. Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS) revealed the chemical functional groups present in the films. The surface chemical compositions have been derived from X-ray photo electron spectroscopy (XPS). FT-IRRAS and XPS show the presence of sp, sp2 and sp3 bonds of carbon and nitrogen. Various functional groups such as NH containing, saturated and unsaturated alkyl groups have been identified. Thin films obtained from C2H2/N2 and C2H4/N2 gas mixtures revealed a higher N/C ratio when compared to thin films obtained from C2H6/N2. Thickness, refractive index and extinction coefficient were evaluated by spectroscopic ellipsometry (SE). Significant differences between the films obtained with different gas mixtures are observed.

  9. Production of gas phase NO₂ and halogens from the photochemical oxidation of aqueous mixtures of sea salt and nitrate ions at room temperature.

    PubMed

    Richards, Nicole K; Finlayson-Pitts, Barbara J

    2012-10-01

    Nitrate and halide ions coexist in a number of environmental systems, including sea salt particles, the Arctic snowpack, and alkaline dry lakes. However, little is known about potential synergisms between halide and nitrate ions. The effect of sea salt on NO(3)(-) photochemistry at 311 nm was investigated at 298 K using thin films of deliquesced NaNO(3)-synthetic sea salt mixtures. Gas phase NO(2), NO, and halogen products were measured as a function of photolysis time using NO(y) chemiluminescence and atmospheric pressure ionization mass spectrometry (API-MS). The production of NO(2) increases with the halide-to-nitrate ratio, and is similar to that for mixtures of NaCl with NaNO(3). Gas phase halogen production also increased with the halide-to-nitrate ratio, consistent with NO(3)(-) photolysis yielding OH which oxidizes halide ions in the film. Yields of gas phase halogens and NO were strongly dependent on the acidity of the solution, while that of NO(2) was not. An additional halogen formation mechanism in the dark involving molecular HNO(3) is proposed that may be important in other systems such as reactions on surfaces. These studies show that the yield of Br(2) relative to NO(2) during photolysis of halide-nitrate mixtures could be as high as 35% under some atmospheric conditions.

  10. Monitoring of CO2/H2S gas mixture injection in basaltic rocks at Hellisheiði Geothermal Power Plant, Iceland

    NASA Astrophysics Data System (ADS)

    Clark, Deirdre E.; Gunnarsson, Ingvi; Aradóttir, Edda S.; Gunnlaugsson, Einar; Júlíusson, Bjarni M.; Matter, Juerg M.; Stute, Martin; Oelkers, Eric H.; Snæbjörnsdóttir, Sandra Ó.; Gíslason, Sigurður R.

    2016-04-01

    Hellisheiði geothermal power plant emits about 41,000 tonnes of CO2 and 10,000 tonnes of H2S per year as a by-product of geothermal energy production. Icelandic regulations, stricter than WHO guidelines, have been in effect in order to reduce H2S emissions of the geothermal industry, while carbon capture and storage (CCS) is one method recommended to minimise the amount of CO2 released into the atmosphere. The overall cost of CCS is dominated by that of capture and gas separation. This capture cost could be lowered by injecting gas mixtures into rocks as is now being tested at Hellisheiði geothermal power plant in SW-Iceland. There, a gas mixture of 60% CO2 and 40% H2S is dissolved in water from the plant and injected into the basaltic rocks. The CarbFix and SulFix pilot projects demonstrated solubility storage of the pure separate gases in a few minutes [1,2] and that more than 80% of the injected CO2 into basaltic rocks was mineralised within a year from its injection at 20-50°C [3]. The first phase of the gas mixture injection began on 3 June 2014, while tracer tests started three weeks later. By the end of the year 2015, approximately 6280 tonnes of CO2 and 3520 tonnes of H2S had been injected. The gases are dissolved in condensation water, mixed with waste water and injected to 750 m depth into a high temperature reservoir of 200-270°C. Water and gas samples were collected from four monitoring wells. There is a minor increase in CO2 (total dissolved carbon) and H2S (total dissolved sulphite), while the majority of major and minor elements are relatively stable. The data from monitoring wells therefore suggests that some of the injected gas mixture is already stored as minerals in the basaltic reservoir. [1] Sigfusson et al. (2015) Int. J. of Greenh. Gas Control 37, 213-219. [2] Gunnarsson et al. (2013) GRC Transactions 37, 785-789. [3] Matter et al. (2014) Energy Procedia 63, 4180-4185.

  11. Isotopic Ratio Outlier Analysis of the S. cerevisiae Metabolome Using Accurate Mass Gas Chromatography/Time-of-Flight Mass Spectrometry: A New Method for Discovery.

    PubMed

    Qiu, Yunping; Moir, Robyn; Willis, Ian; Beecher, Chris; Tsai, Yu-Hsuan; Garrett, Timothy J; Yost, Richard A; Kurland, Irwin J

    2016-03-01

    Isotopic ratio outlier analysis (IROA) is a (13)C metabolomics profiling method that eliminates sample to sample variance, discriminates against noise and artifacts, and improves identification of compounds, previously done with accurate mass liquid chromatography/mass spectrometry (LC/MS). This is the first report using IROA technology in combination with accurate mass gas chromatography/time-of-flight mass spectrometry (GC/TOF-MS), here used to examine the S. cerevisiae metabolome. S. cerevisiae was grown in YNB media, containing randomized 95% (13)C, or 5%(13)C glucose as the single carbon source, in order that the isotopomer pattern of all metabolites would mirror the labeled glucose. When these IROA experiments are combined, the abundance of the heavy isotopologues in the 5%(13)C extracts, or light isotopologues in the 95%(13)C extracts, follows the binomial distribution, showing mirrored peak pairs for the molecular ion. The mass difference between the (12)C monoisotopic and the (13)C monoisotopic equals the number of carbons in the molecules. The IROA-GC/MS protocol developed, using both chemical and electron ionization, extends the information acquired from the isotopic peak patterns for formulas generation. The process that can be formulated as an algorithm, in which the number of carbons, as well as the number of methoximations and silylations are used as search constraints. In electron impact (EI/IROA) spectra, the artifactual peaks are identified and easily removed, which has the potential to generate "clean" EI libraries. The combination of chemical ionization (CI) IROA and EI/IROA affords a metabolite identification procedure that enables the identification of coeluting metabolites, and allowed us to characterize 126 metabolites in the current study. PMID:26820234

  12. Toxicity of carbon monoxide-hydrogen cyanide gas mixtures: Expose concentration, time-to-incapacitation, carboxyhemoglobin, and blood cyanide parameters. Final report

    SciTech Connect

    Sanders, D.C.; Chaturvedi, A.K.; Endecott, B.R.; Ritter, R.M.; Vu, N.

    1994-04-01

    During aircraft interior fires, carbon monoxide (CO) and hydrogen cyanide (HCN) are produced in sufficient amounts to cause incapacitation and death. Time-to-incapacitation (ti) is a practical parameter for estimating escape time in fire environments. Exposures to CO-HCN mixtures have demonstrated that these gases have additive effects (producing shorter times to incapacitation), but the resulting concentrations of carboxyhemoglobin (COHb) and blood cyanide (CN-) at incapacitation are not well defined. These undefined relationships between COHb and blood CN- levels and the onset of incapacitation make the interpretation of postmortem levels difficult for medical accident investigators. To explore these relationships, ti was determined in laboratory rats exposed to two CO-HCN mixtures consisting of CO and HCN concentrations that produce 5- and 35-min ti in individual gas exposures; COHb and blood CN- concentrations were determined at incapacitation. In the high concentration CO-HCN mixture, the resultant ti was shortened from 5 min to 2.6 min; COHb dropped from 81% to 55% and CN- from 2.3 microns/mL to 1.1 microns/mL. At the lower concentration COHCN mixture, where the resultant ti was reduced from 35 min to 11.1 min, COHb dropped from 71% to 61% and blood CN- decreased from 4.2 microns/mL to 1.1 microns/mL. Comparison of the COHb and blood CN- values with the values from our signal gas exposure studies indicated that any alteration of the uptake of either gas in blood by the presence of the other was minimal. These findings suggest that changes in COHb and blood CN- may not be directly correlated with the onset of incapacitation and that postmortem blood levels should be carefully evaluated, particularly when both gases are present.

  13. Hessian Fly (Diptera: Cecidomyiidae) Mortality in Export Bale Compressors and Response to a Hydrogen Phosphide and Carbon Dioxide Gas Mixture.

    PubMed

    Yokoyama, Victoria Y; Cambron, Sue E; Muhareb, Jeannette

    2015-02-01

    Hessian fly, Mayetiola destructor (Say), puparial mortality was evaluated in three modern hay compressors that produce compressed standard and large-size bales for export to Asia-Pacific countries. Pressure on bales ranged from 93.4 to 139.4 kg/cm2, causing 90.0-99.9% mortality of 10,891-23,164 puparia. Puparial response to a cylinderized hydrogen phosphide (1.8-2%) and carbon dioxide (97.8-98%) gas mixture was evaluated as a potential quarantine treatment using 2-4 d-exposures to low, medium, and high doses of 0.73-0.86, 1.05-1.26, and 1.39-1.56 mg/liter, and temperatures of 5.87±1.14, 9.84±0.05, 16.14±0.14, and 20.35±0.11°C. Accumulative concentration multiplied by time products (mg h/liter) at all fumigation temperatures for low, medium, and high fumigant doses were 34.9-37.7, 52.2-54.3, and 67.9-73.1 for 2 d; 52.7-60.6, 77.9-89.2, and 102.1-110.7 for 3 d; and 69.9-82.0, 99.4-118.2, and 132.3-146.8 for 4 d, respectively. An increase in mortality was significantly related to an increase in fumigation duration at 5, 10, and 15°C, and an increase in fumigant dose at 10 and 15°C. Puparial mortality ranged from 97.2 to 100% at all doses and durations at 20°C with no survivors at the highest dose for 3 d and the mid- and highest dose for 4 d. Bale compression is currently used in the first phase of a multiple quarantine treatment to control potential Hessian fly contaminants in exported hay. The novel fumigant may have application as a single quarantine treatment for noncompressed, standard exported bales.

  14. Hessian Fly (Diptera: Cecidomyiidae) Mortality in Export Bale Compressors and Response to a Hydrogen Phosphide and Carbon Dioxide Gas Mixture.

    PubMed

    Yokoyama, Victoria Y; Cambron, Sue E; Muhareb, Jeannette

    2015-02-01

    Hessian fly, Mayetiola destructor (Say), puparial mortality was evaluated in three modern hay compressors that produce compressed standard and large-size bales for export to Asia-Pacific countries. Pressure on bales ranged from 93.4 to 139.4 kg/cm2, causing 90.0-99.9% mortality of 10,891-23,164 puparia. Puparial response to a cylinderized hydrogen phosphide (1.8-2%) and carbon dioxide (97.8-98%) gas mixture was evaluated as a potential quarantine treatment using 2-4 d-exposures to low, medium, and high doses of 0.73-0.86, 1.05-1.26, and 1.39-1.56 mg/liter, and temperatures of 5.87±1.14, 9.84±0.05, 16.14±0.14, and 20.35±0.11°C. Accumulative concentration multiplied by time products (mg h/liter) at all fumigation temperatures for low, medium, and high fumigant doses were 34.9-37.7, 52.2-54.3, and 67.9-73.1 for 2 d; 52.7-60.6, 77.9-89.2, and 102.1-110.7 for 3 d; and 69.9-82.0, 99.4-118.2, and 132.3-146.8 for 4 d, respectively. An increase in mortality was significantly related to an increase in fumigation duration at 5, 10, and 15°C, and an increase in fumigant dose at 10 and 15°C. Puparial mortality ranged from 97.2 to 100% at all doses and durations at 20°C with no survivors at the highest dose for 3 d and the mid- and highest dose for 4 d. Bale compression is currently used in the first phase of a multiple quarantine treatment to control potential Hessian fly contaminants in exported hay. The novel fumigant may have application as a single quarantine treatment for noncompressed, standard exported bales. PMID:26470109

  15. Effect of isobaric breathing gas shifts from air to heliox mixtures on resolution of air bubbles in lipid and aqueous tissues of recompressed rats.

    PubMed

    Hyldegaard, O; Kerem, D; Melamed, Y

    2011-09-01

    Deep tissue isobaric counterdiffusion that may cause unwanted bubble formation or transient bubble growth has been referred to in theoretical models and demonstrated by intravascular gas formation in animals, when changing inert breathing gas from nitrogen to helium after hyperbaric air breathing. We visually followed the in vivo resolution of extravascular air bubbles injected at 101 kPa into nitrogen supersaturated rat tissues: adipose, spinal white matter, skeletal muscle or tail tendon. Bubbles were observed during isobaric breathing-gas shifts from air to normoxic (80:20) heliox mixture while at 285 kPa or following immediate recompression to either 285 or 405 kPa, breathing 80:20 and 50:50 heliox mixtures. During the isobaric shifts, some bubbles in adipose tissue grew marginally for 10-30 min, subsequently they shrank and disappeared at a rate similar to or faster than during air breathing. No such bubble growth was observed in spinal white matter, skeletal muscle or tendon. In spinal white matter, an immediate breathing gas shift after the hyperbaric air exposure from air to both (80:20) and (50:50) heliox, coincident with recompression to either 285 or 405 kPa, caused consistent shrinkage of all air bubbles, until they disappeared from view. Deep tissue isobaric counterdiffusion may cause some air bubbles to grow transiently in adipose tissue. The effect is marginal and of no clinical consequence. Bubble disappearance rate is faster with heliox breathing mixtures as compared to air. We see no reason for reservations in the use of heliox breathing during treatment of air-diving-induced decompression sickness.

  16. Effect of isobaric breathing gas shifts from air to heliox mixtures on resolution of air bubbles in lipid and aqueous tissues of recompressed rats.

    PubMed

    Hyldegaard, O; Kerem, D; Melamed, Y

    2011-09-01

    Deep tissue isobaric counterdiffusion that may cause unwanted bubble formation or transient bubble growth has been referred to in theoretical models and demonstrated by intravascular gas formation in animals, when changing inert breathing gas from nitrogen to helium after hyperbaric air breathing. We visually followed the in vivo resolution of extravascular air bubbles injected at 101 kPa into nitrogen supersaturated rat tissues: adipose, spinal white matter, skeletal muscle or tail tendon. Bubbles were observed during isobaric breathing-gas shifts from air to normoxic (80:20) heliox mixture while at 285 kPa or following immediate recompression to either 285 or 405 kPa, breathing 80:20 and 50:50 heliox mixtures. During the isobaric shifts, some bubbles in adipose tissue grew marginally for 10-30 min, subsequently they shrank and disappeared at a rate similar to or faster than during air breathing. No such bubble growth was observed in spinal white matter, skeletal muscle or tendon. In spinal white matter, an immediate breathing gas shift after the hyperbaric air exposure from air to both (80:20) and (50:50) heliox, coincident with recompression to either 285 or 405 kPa, caused consistent shrinkage of all air bubbles, until they disappeared from view. Deep tissue isobaric counterdiffusion may cause some air bubbles to grow transiently in adipose tissue. The effect is marginal and of no clinical consequence. Bubble disappearance rate is faster with heliox breathing mixtures as compared to air. We see no reason for reservations in the use of heliox breathing during treatment of air-diving-induced decompression sickness. PMID:21318313

  17. Effects of tropical high tannin non legume and low tannin legume browse mixtures on fermentation parameters and methanogenesis using gas production technique.

    PubMed

    Seresinhe, T; Madushika, S A C; Seresinhe, Y; Lal, P K; Orskov, E R

    2012-10-01

    In vitro experiments were conducted to evaluate the suitability of several mixtures of high tanniniferous non legumes with low tanniniferous legumes on in vitro gas production (IVGP), dry matter degradation, Ammonia-N, methane production and microbial population. Eight treatments were examined in a randomized complete block design using four non-legumes and two legumes (Carallia integerrima×Leucaena leucocephala (LL) (Trt 1), C. integerrima×Gliricidia sepium (GS) (Trt 2), Aporosa lindeliyana×LL (Trt 3), A. lindeliyana×GS (Trt 4), Ceiba perntandra×LL (Trt 5), C. perntandra×GS (Trt 6), Artocarpus heterophyllus×LL (Trt 7), A. heterophyllus×GS (Trt 8). The condensed tannin (CT) content of non legumes ranged from 6.2% (Carallia integerrima) to 4.9% (Ceiba perntandra) while the CT of legumes were 1.58% (Leucaena leucocephala) and 0.78% (Gliricidia sepium). Forage mixtures contained more than 14% of crude protein (CP) while the CT content ranged from 2.8% to 4.0% respectively. Differences (p<0.05) were observed in in vitro gas production (IGVP) within treatments over a 48 h period dominated by C. perntandra×G. sepium (Trt 6). The net gas production (p<0.05) was also high with Trt6 followed by A. heterophyllus×L. leucocephala (Trt 7) and A. heterophyllus×G. sepium (Trt 8). Highest (p>0.05) NH3-N (ml/200 mg DM) production was observed with the A. heterophyllus×G. sepium (Trt 8) mixture which may be attributed with it's highest CP content. The correlation between IVGP and CT was 0.675 while IVGP and CP was 0.610. In vitro dry matter degradation (IVDMD) was highest in Trt 8 as well. Methane production ranged from 2.57 to 4.79 (ml/200 mg DM) to be synonimous with IVGP. A higher bacteria population (p<0.05) was found in C. perntandra×G. sepium (Trt 6) followed by Artocarpus heterophyllus+G. sepium (Trt 8) and the same trend was observed with the protozoa population as well. The results show that supplementing high tannin non leguminous forages by incremental

  18. Effects of tropical high tannin non legume and low tannin legume browse mixtures on fermentation parameters and methanogenesis using gas production technique.

    PubMed

    Seresinhe, T; Madushika, S A C; Seresinhe, Y; Lal, P K; Orskov, E R

    2012-10-01

    In vitro experiments were conducted to evaluate the suitability of several mixtures of high tanniniferous non legumes with low tanniniferous legumes on in vitro gas production (IVGP), dry matter degradation, Ammonia-N, methane production and microbial population. Eight treatments were examined in a randomized complete block design using four non-legumes and two legumes (Carallia integerrima×Leucaena leucocephala (LL) (Trt 1), C. integerrima×Gliricidia sepium (GS) (Trt 2), Aporosa lindeliyana×LL (Trt 3), A. lindeliyana×GS (Trt 4), Ceiba perntandra×LL (Trt 5), C. perntandra×GS (Trt 6), Artocarpus heterophyllus×LL (Trt 7), A. heterophyllus×GS (Trt 8). The condensed tannin (CT) content of non legumes ranged from 6.2% (Carallia integerrima) to 4.9% (Ceiba perntandra) while the CT of legumes were 1.58% (Leucaena leucocephala) and 0.78% (Gliricidia sepium). Forage mixtures contained more than 14% of crude protein (CP) while the CT content ranged from 2.8% to 4.0% respectively. Differences (p<0.05) were observed in in vitro gas production (IGVP) within treatments over a 48 h period dominated by C. perntandra×G. sepium (Trt 6). The net gas production (p<0.05) was also high with Trt6 followed by A. heterophyllus×L. leucocephala (Trt 7) and A. heterophyllus×G. sepium (Trt 8). Highest (p>0.05) NH3-N (ml/200 mg DM) production was observed with the A. heterophyllus×G. sepium (Trt 8) mixture which may be attributed with it's highest CP content. The correlation between IVGP and CT was 0.675 while IVGP and CP was 0.610. In vitro dry matter degradation (IVDMD) was highest in Trt 8 as well. Methane production ranged from 2.57 to 4.79 (ml/200 mg DM) to be synonimous with IVGP. A higher bacteria population (p<0.05) was found in C. perntandra×G. sepium (Trt 6) followed by Artocarpus heterophyllus+G. sepium (Trt 8) and the same trend was observed with the protozoa population as well. The results show that supplementing high tannin non leguminous forages by incremental

  19. Effects of Tropical High Tannin Non Legume and Low Tannin Legume Browse Mixtures on Fermentation Parameters and Methanogenesis Using Gas Production Technique

    PubMed Central

    Seresinhe, T.; Madushika, S. A. C.; Seresinhe, Y.; Lal, P. K.; Ørskov, E. R.

    2012-01-01

    In vitro experiments were conducted to evaluate the suitability of several mixtures of high tanniniferous non legumes with low tanniniferous legumes on in vitro gas production (IVGP), dry matter degradation, Ammonia-N, methane production and microbial population. Eight treatments were examined in a randomized complete block design using four non-legumes and two legumes (Carallia integerrima×Leucaena leucocephala (LL) (Trt 1), C. integerrima×Gliricidia sepium (GS) (Trt 2), Aporosa lindeliyana×LL (Trt 3), A. lindeliyana×GS (Trt 4), Ceiba perntandra×LL (Trt 5), C. perntandra×GS (Trt 6), Artocarpus heterophyllus×LL (Trt 7), A. heterophyllus×GS (Trt 8). The condensed tannin (CT) content of non legumes ranged from 6.2% (Carallia integerrima) to 4.9% (Ceiba perntandra) while the CT of legumes were 1.58% (Leucaena leucocephala) and 0.78% (Gliricidia sepium). Forage mixtures contained more than 14% of crude protein (CP) while the CT content ranged from 2.8% to 4.0% respectively. Differences (p<0.05) were observed in in vitro gas production (IGVP) within treatments over a 48 h period dominated by C. perntandra×G. sepium (Trt 6). The net gas production (p<0.05) was also high with Trt6 followed by A. heterophyllus×L. leucocephala (Trt 7) and A. heterophyllus×G. sepium (Trt 8). Highest (p>0.05) NH3-N (ml/200 mg DM) production was observed with the A. heterophyllus×G. sepium (Trt 8) mixture which may be attributed with it’s highest CP content. The correlation between IVGP and CT was 0.675 while IVGP and CP was 0.610. In vitro dry matter degradation (IVDMD) was highest in Trt 8 as well. Methane production ranged from 2.57 to 4.79 (ml/200 mg DM) to be synonimous with IVGP. A higher bacteria population (p<0.05) was found in C. perntandra×G. sepium (Trt 6) followed by Artocarpus heterophyllus+G. sepium (Trt 8) and the same trend was observed with the protozoa population as well. The results show that supplementing high tannin non leguminous forages by incremental

  20. Effects of temperature, pressure, and carrier gas on the cracking of coal tar over a char-dolomite mixtures and calcined dolomite in a fixed-bed reactor

    SciTech Connect

    Seshadri, K.; Shamsi, A.

    1998-10-01

    A distillation fraction of a coal-derived liquid (tar) was cracked over a char-dolomite mixture, calcined dolomite, and silicon carbide in a fixed-bed reactor. The char-dolomite mixture (FWC) was produced from Pittsburgh No. 8 coal and dolomite in a Foster Wheeler carbonizer. The experiments were conducted under nitrogen and simulated coal gas (SCG), which was a mixture of CO, CO{sub 2}, H{sub 2}S, CH{sub 4}, N{sub 2}, and steam, at 1 and 17 atm. The conversion over these materials under nitrogen was much higher at 17 atm than at 1 atm. At higher pressures, tar molecules were trapped in the pores of the bed material and underwent secondary reactions, resulting in the formation of excess char. However, when nitrogen was replaced by SCG, the reactions that induce char formation were suppressed, thus increasing the yield of gaseous products. The analysis of the gaseous products and the spent bed materials for organic and inorganic carbons suggested that the product distribution can be altered by changing the carrier gas, temperature, and pressure.

  1. Calculation of the thermal conductivity of low-density CH4-N2 gas mixtures using an improved kinetic theory approach.

    PubMed

    Hellmann, Robert; Bich, Eckard; Vesovic, Velisa

    2016-04-01

    The thermal conductivity of low-density CH4-N2 gas mixtures has been calculated by means of the classical trajectory method using state-of-the-art intermolecular potential energy surfaces for the CH4-CH4, N2-N2, and CH4-N2 interactions. Results are reported in the temperature range from 70 K to 1200 K. Since the thermal conductivity is influenced by the vibrational degrees of freedom of the molecules, which are not included in the rigid-rotor classical trajectory computations, a new correction scheme to account for vibrational degrees of freedom in a dilute gas mixture is presented. The calculations show that the vibrational contribution at the highest temperature studied amounts to 46% of the total thermal conductivity of an equimolar mixture compared to 13% for pure nitrogen and 58% for pure methane. The agreement with the available experimental thermal conductivity data at room temperature is good, within ±1.4%, whereas at higher temperatures, larger deviations up to 4.5% are observed, which can be tentatively attributed to deteriorating performance of the measuring technique employed. Results are also reported for the magnitude and temperature dependence of the rotational collision number, Z(rot), for CH4 relaxing in collisions with N2 and for N2 relaxing in collisions with CH4. Both collision numbers increase with temperature, with the former being consistently about twice the value of the latter. PMID:27059564

  2. Calculation of the thermal conductivity of low-density CH4-N2 gas mixtures using an improved kinetic theory approach.

    PubMed

    Hellmann, Robert; Bich, Eckard; Vesovic, Velisa

    2016-04-01

    The thermal conductivity of low-density CH4-N2 gas mixtures has been calculated by means of the classical trajectory method using state-of-the-art intermolecular potential energy surfaces for the CH4-CH4, N2-N2, and CH4-N2 interactions. Results are reported in the temperature range from 70 K to 1200 K. Since the thermal conductivity is influenced by the vibrational degrees of freedom of the molecules, which are not included in the rigid-rotor classical trajectory computations, a new correction scheme to account for vibrational degrees of freedom in a dilute gas mixture is presented. The calculations show that the vibrational contribution at the highest temperature studied amounts to 46% of the total thermal conductivity of an equimolar mixture compared to 13% for pure nitrogen and 58% for pure methane. The agreement with the available experimental thermal conductivity data at room temperature is good, within ±1.4%, whereas at higher temperatures, larger deviations up to 4.5% are observed, which can be tentatively attributed to deteriorating performance of the measuring technique employed. Results are also reported for the magnitude and temperature dependence of the rotational collision number, Z(rot), for CH4 relaxing in collisions with N2 and for N2 relaxing in collisions with CH4. Both collision numbers increase with temperature, with the former being consistently about twice the value of the latter.

  3. Calculation of the thermal conductivity of low-density CH4-N2 gas mixtures using an improved kinetic theory approach

    NASA Astrophysics Data System (ADS)

    Hellmann, Robert; Bich, Eckard; Vesovic, Velisa

    2016-04-01

    The thermal conductivity of low-density CH4-N2 gas mixtures has been calculated by means of the classical trajectory method using state-of-the-art intermolecular potential energy surfaces for the CH4-CH4, N2-N2, and CH4-N2 interactions. Results are reported in the temperature range from 70 K to 1200 K. Since the thermal conductivity is influenced by the vibrational degrees of freedom of the molecules, which are not included in the rigid-rotor classical trajectory computations, a new correction scheme to account for vibrational degrees of freedom in a dilute gas mixture is presented. The calculations show that the vibrational contribution at the highest temperature studied amounts to 46% of the total thermal conductivity of an equimolar mixture compared to 13% for pure nitrogen and 58% for pure methane. The agreement with the available experimental thermal conductivity data at room temperature is good, within ±1.4%, whereas at higher temperatures, larger deviations up to 4.5% are observed, which can be tentatively attributed to deteriorating performance of the measuring technique employed. Results are also reported for the magnitude and temperature dependence of the rotational collision number, Zrot, for CH4 relaxing in collisions with N2 and for N2 relaxing in collisions with CH4. Both collision numbers increase with temperature, with the former being consistently about twice the value of the latter.

  4. Improved resolution of hydrocarbon structures and constitutional isomers in complex mixtures using Gas Chromatography-Vacuum Ultraviolet-Mass Spectrometry (GC-VUV-MS)

    SciTech Connect

    Aerosol Dynamics Inc; Aerodyne Research, Inc.,; Tofwerk AG, Thun; Isaacman, Gabriel; Wilson, Kevin R.; Chan, Arthur W. H.; Worton, David R.; Kimmel, Joel R.; Nah, Theodora; Hohaus, Thorsten; Gonin, Marc; Kroll, Jesse H.; Worsnop, Doug R.; Goldstein, Allen H.

    2011-09-13

    Understanding the composition of complex hydrocarbon mixtures is important for environmental studies in a variety of fields, but many prevalent compounds cannot be confidently identified using traditional gas chromatography-mass spectrometry (GC-MS) techniques. This work uses vacuum-ultraviolet (VUV) ionization to elucidate the structures of a traditionally"unresolved complex mixture" by separating components by GC retention time, tR, and mass-to-charge ratio, m/Q, which are used to determine carbon number, NC, and the number of rings and double bonds, NDBE. Constitutional isomers are resolved based on tR, enabling the most complete quantitative analysis to date of structural isomers in an environmentally-relevant hydrocarbon mixture. Unknown compounds are classified in this work by carbon number, degree of saturation, presence of rings, and degree of branching, providing structural constraints. The capabilities of this analysis are explored using diesel fuel, in which constitutional isomer distribution patterns are shown to be reproducible between carbon numbers and follow predictable rules. Nearly half of the aliphatic hydrocarbon mass is shown to be branched, suggesting branching is more important in diesel fuel than previously shown. The classification of unknown hydrocarbons and the resolution of constitutional isomers significantly improves resolution capabilities for any complex hydrocarbon mixture.

  5. Sedimentation of a two-dimensional colloidal mixture exhibiting liquid-liquid and gas-liquid phase separation: a dynamical density functional theory study.

    PubMed

    Malijevský, Alexandr; Archer, Andrew J

    2013-10-14

    We present dynamical density functional theory results for the time evolution of the density distribution of a sedimenting model two-dimensional binary mixture of colloids. The interplay between the bulk phase behaviour of the mixture, its interfacial properties at the confining walls, and the gravitational field gives rise to a rich variety of equilibrium and non-equilibrium morphologies. In the fluid state, the system exhibits both liquid-liquid and gas-liquid phase separation. As the system sediments, the phase separation significantly affects the dynamics and we explore situations where the final state is a coexistence of up to three different phases. Solving the dynamical equations in two-dimensions, we find that in certain situations the final density profiles of the two species have a symmetry that is different from that of the external potentials, which is perhaps surprising, given the statistical mechanics origin of the theory. The paper concludes with a discussion on this.

  6. Characteristics of surface-wave plasma with air-simulated N2 O2 gas mixture for low-temperature sterilization

    NASA Astrophysics Data System (ADS)

    Xu, L.; Nonaka, H.; Zhou, H. Y.; Ogino, A.; Nagata, T.; Koide, Y.; Nanko, S.; Kurawaki, I.; Nagatsu, M.

    2007-02-01

    Sterilization experiments using low-pressure air discharge plasma sustained by the 2.45 GHz surface-wave have been carried out. Geobacillus stearothermoplilus spores having a population of 3.0 × 106 were sterilized for only 3 min using air-simulated N2-O2 mixture gas discharge plasma, faster than the cases of pure O2 or pure N2 discharge plasmas. From the SEM analysis of plasma-irradiated spores and optical emission spectroscopy measurements of the plasmas, it has been found that the possible sterilization mechanisms of air-simulated plasma are the chemical etching effect due to the oxygen radicals and UV emission from the N2 molecules and NO radicals in the wavelength range 200-400 nm. Experiment suggested that UV emission in the wavelength range less than 200 nm might not be significant in the sterilization. The UV intensity at 237.0 nm originated from the NO γ system (A 2Σ+ → X 2Π) in N2-O2 plasma as a function of the O2 percentage added to N2-O2 mixture gas has been investigated. It achieved its maximum value when the O2 percentage was roughly 10-20%. This result suggests that air can be used as a discharge gas for sterilization, and indeed we have confirmed a rapid sterilization with the actual air discharge at a sample temperature of less than 65 °C.

  7. Solubilities of methane, nitrogen, carbon dioxide, and a natural gas mixture in aqueous sodium bicarbonate solutions under high pressure and elevated temperature

    SciTech Connect

    Gao, J.; Zheng, D.Q.; Guo, T.M.

    1997-01-01

    The solubility of natural gas mixtures in formation water (brine) plays an important role in estimating the natural gas reserve, the formation/dissociation conditions of methane hydrates in situ, and the interfacial tension of the hydrocarbon-formation water system. However, solubility data at high pressure and elevated temperature conditions for aqueous electrolyte systems are rare. Recently, in the reservoirs found at the South China Sea areas, the main salt species in the formation water is sodium bicarbonate, and the solubility data of gases in aqueous sodium bicarbonate solutions under reservoir conditions have not previously been reported. An apparatus for measuring the solubility of gases in aqueous electrolyte solutions under high pressure and elevated temperature conditions is described. The solubility of methane, carbon dioxide, nitrogen, and a natural gas mixture in aqueous sodium bicarbonate solutions were measured up to 58 MPa and 403 K. The modified Patel-Teja equation of state proposed by Zuo and Guo (1991) for aqueous electrolyte systems was applied to correlate the measured solubility data, and satisfactory results were obtained.

  8. Method and apparatus for the separation of a gas-solids mixture in a circulating fluidized bed reactor

    DOEpatents

    Vimalchand, Pannalal; Liu, Guohai; Peng, WanWang

    2010-08-10

    The system of the present invention includes a centripetal cyclone for separating particulate material from a particulate laden gas solids stream. The cyclone includes a housing defining a conduit extending between an upstream inlet and a downstream outlet. In operation, when a particulate laden gas-solids stream passes through the upstream housing inlet, the particulate laden gas-solids stream is directed through the conduit and at least a portion of the solids in the particulate laden gas-solids stream are subjected to a centripetal force within the conduit.

  9. In vitro gas production in rumen fluid of buffalo as affected by urea-calcium mixture in high-quality feed block.

    PubMed

    Cherdthong, Anusorn; Wanapat, Metha

    2014-04-01

    This study aimed to determine the effect of urea-calcium sulphate mixture (U-cas) levels in high-quality feed block (HQFB) on ruminal digestibility, fermentation and gas kinetics in rumen fluid of swamp buffalo by using in vitro techniques. The treatments were seven levels of U-cas incorporated in HQFB at 0, 3, 6, 9, 12, 15 and 18% and the experimental design was a completely randomized design. Gas production rate constants for the insoluble fraction, potential extent of gas and cumulative gas were linearly increased with increasing levels of U-cas in HQFB. The in vitro dry matter digestibility, in vitro organic matter digestibility, true digestibility and microbial mass were altered by treatments and were greatest at 18% U-cas supplementation. Concentrations of propionate were linearly increased with increasing levels of U-cas and was highest with U-cas supplementation at 18%. The NH3 -N concentration was highest when urea was added in the HQFB while NH3 -N concentration tended to be reduced with increasing level of U-cas. The findings suggest supplementation of 18% U-cas in HQFB improves kinetics of gas production, rumen fermentation, digestibility and microbial mass as well as controlling the rate of N degradation in the rumen of swamp buffalo.

  10. First accurate experimental study of Mu reactivity from a state-selected reactant in the gas phase: the Mu + H2{1} reaction rate at 300 K

    NASA Astrophysics Data System (ADS)

    Bakule, Pavel; Sukhorukov, Oleksandr; Ishida, Katsuhiko; Pratt, Francis; Fleming, Donald; Momose, Takamasa; Matsuda, Yasuyuki; Torikai, Eiko

    2015-02-01

    This paper reports on the experimental background and methodology leading to recent results on the first accurate measurement of the reaction rate of the muonium (Mu) atom from a state-selected reactant in the gas phase: the Mu + H2\\{1\\}\\to MuH + H reaction at 300 K, and its comparison with rigorous quantum rate theory, Bakule et al (2012 J. Phys. Chem. Lett. 3 2755). Stimulated Raman pumping, induced by 532 nm light from the 2nd harmonic of a Nd:YAG laser, was used to produce H2 in its first vibrational (v = 1) state, H2\\{1\\}, in a single Raman/reaction cell. A pulsed muon beam (from ‘ISIS’, at 50 Hz) matched the 25 Hz repetition rate of the laser, allowing data taking in equal ‘Laser-On/Laser-Off’ modes of operation. The signal to noise was improved by over an order of magnitude in comparison with an earlier proof-of-principle experiment. The success of the present experiment also relied on optimizing the overlap of the laser profile with the extended stopping distribution of the muon beam at 50 bar H2 pressure, in which Monte Carlo simulations played a central role. The rate constant, found from the analysis of three separate measurements, which includes a correction for the loss of {{H}2}\\{1\\} concentration due to collisional relaxation with unpumped H2 during the time of each measurement, is {{k}Mu}\\{1\\} = 9.9[(-1.4)(+1.7)] × 10-13 cm3 s-1 at 300 K. This is in good to excellent agreement with rigorous quantum rate calculations on the complete configuration interaction/Born-Huang surface, as reported earlier by Bakule et al, and which are also briefly commented on herein.

  11. Accurate Analysis and Characterization of Silicon Field Effect Transistor-Based Terahertz Wave Detector with Quasi-Plasma Two-Dimensional Electron Gas.

    PubMed

    Kim, Kwan Sung; Ryu, Min Woo; Lee, Jeong Seop; Kim, Kyung Rok

    2016-05-01

    We report the nonresonant plasmonic terahertz (THz) wave detector based on the silicon (Si) field effect transistor (FET) with a technology computer-aided design (TCAD) platform. The plasma wave behavior has been modeled by a quasi-plasma electron box as a two-dimensional electron gas (2DEG) in the channel of the FET. The incoming alternating current (AC) signal as the THz wave radiation can induce the direct-current (DC) voltage difference between the source and drain, which is called the photoresponse. For accurate analysis of the modulation and propagation of the channel electron density as the plasma wave, we have characterized the quasi-plasma 2DEG model with two key parameters, such as quasi-plasma 2DEG length (I(QP)) and density (N(QP)). By using our normalization method, I(QP) and N(QP) is defined exactly as extracting the average point of the electron density. We also investigate the performance enhancement of the plasmonic terahertz wave detector based on Si FET by scaling down the gate oxide thickness (t(ox)), which is a significant parameter of FET-based plasmonic terahertz detector for the channel electron density modulation. According to scaling down t(ox), the responsivity (R(v)) and noise equivalent power (NEP), which are the important performance metrics of the THz wave detector, have been enhanced. The proposed methodologies will provide the advanced physical analysis and structural design platform for developing the plasmonic terahertz detectors operating in nonresonant regime. PMID:27483817

  12. 10 CFR 504.8 - Prohibitions against excessive use of petroleum or natural gas in mixtures-certifying powerplants.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 4 2014-01-01 2014-01-01 false Prohibitions against excessive use of petroleum or natural...) ALTERNATE FUELS EXISTING POWERPLANTS § 504.8 Prohibitions against excessive use of petroleum or natural gas... use of petroleum or natural gas in such powerplant in amounts exceeding the minimum amount...

  13. 10 CFR 504.8 - Prohibitions against excessive use of petroleum or natural gas in mixtures-certifying powerplants.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 4 2013-01-01 2013-01-01 false Prohibitions against excessive use of petroleum or natural...) ALTERNATE FUELS EXISTING POWERPLANTS § 504.8 Prohibitions against excessive use of petroleum or natural gas... use of petroleum or natural gas in such powerplant in amounts exceeding the minimum amount...

  14. 10 CFR 504.8 - Prohibitions against excessive use of petroleum or natural gas in mixtures-certifying powerplants.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 4 2012-01-01 2012-01-01 false Prohibitions against excessive use of petroleum or natural...) ALTERNATE FUELS EXISTING POWERPLANTS § 504.8 Prohibitions against excessive use of petroleum or natural gas... use of petroleum or natural gas in such powerplant in amounts exceeding the minimum amount...

  15. 10 CFR 504.8 - Prohibitions against excessive use of petroleum or natural gas in mixtures-certifying powerplants.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 4 2011-01-01 2011-01-01 false Prohibitions against excessive use of petroleum or natural...) ALTERNATE FUELS EXISTING POWERPLANTS § 504.8 Prohibitions against excessive use of petroleum or natural gas... use of petroleum or natural gas in such powerplant in amounts exceeding the minimum amount...

  16. 10 CFR 504.8 - Prohibitions against excessive use of petroleum or natural gas in mixtures-certifying powerplants.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Prohibitions against excessive use of petroleum or natural...) ALTERNATE FUELS EXISTING POWERPLANTS § 504.8 Prohibitions against excessive use of petroleum or natural gas... use of petroleum or natural gas in such powerplant in amounts exceeding the minimum amount...

  17. Initiation of ignition of a combustible gas mixture in a closed volume by the radiation of a high-power pulsed CO{sub 2} laser

    SciTech Connect

    Kazantsev, S Yu; Kononov, I G; Kossyi, I A; Popov, N A; Tarasova, N M; Firsov, K N

    2012-01-31

    The results of experiments on initiating the ignition of a CH{sub 4} - O{sub 2} - SF{sub 6} triple gas mixture in a closed volume by the radiation of a high-power CO{sub 2} laser are presented. It is shown that spatially nonuniform (in the direction of the laser beam) gas heating by the laser radiation leads to formation of a fast combustion wave, propagating along the chamber axis and giving rise to 'instantaneous' ignition. At the threshold value 16.5 J of the laser radiation energy the fast combustion wave is transformed into a detonation wave, which causes an explosion and destruction of the reaction chamber.

  18. The Combined Application of Impinger System and Permeation Tube for the Generation of Volatile Organic Compound Standard Gas Mixtures at Varying Diluent Flow Rates

    PubMed Central

    Kim, Ki-Hyun; Susaya, Janice; Cho, Jinwoo; Parker, David

    2012-01-01

    Commercial standard gas generators are often complex and expensive devices. The objective of this research was to assess the performance of a simplified glass impinger system for standard gas generation from a permeation tube (PT) device. The performance of the impinger standard gas generation system was assessed for four aromatic VOCs (benzene, toluene, ethylbenzene, and m-xylene; BTEX) at varying flow rates (FR) of 50 to 800 mL·min−1. Because actual permeation rate (APR) values deviated from those computed by the manufacturer's formula (MPR), new empirical relationships were developed to derive the predicted PR (PPR) of the target components. Experimental results corrected by such a formula indicate that the compatibility between the APR and MPR generally increased with low FR, while the reproducibility was generally reduced with decreasing flow rate. Although compatibility between different PRs is at a relatively small and narrow FR range, the use of correction formula is recommendable for the accurate use of PT. PMID:23112641

  19. Natural gas cleanup: Evaluation of a molecular sieve carbon as a pressure swing adsorbent for the separation of methane/nitrogen mixtures

    SciTech Connect

    Grimes, R.W.

    1994-06-01

    This report describes the results of a preliminary evaluation to determine the technical feasibility of using a molecular sieve carbon manufactured by the Takeda Chemical Company of Japan in a pressure owing adsorption cycle for upgrading natural gas (methane) contaminated with nitrogen. Adsorption tests were conducted using this adsorbent in two, four, and five-step adsorption cycles. Separation performance was evaluated in terms of product purity, product recovery, and sorbent productivity for all tests. The tests were conducted in a small, single-column adsorption apparatus that held 120 grams of the adsorbent. Test variables included adsorption pressure, pressurization rate, purge rate and volume, feed rate, and flow direction in the steps from which the product was collected. Sorbent regeneration was accomplished by purging the column with the feed gas mixture for all but one test series where a pure methane purge was used. The ratio between the volumes of the pressurization gas and the purge gas streams was found to be an important factor in determining separation performance. Flow rates in the various cycle steps had no significant effect. Countercurrent flow in the blow-down and purge steps improved separation performance. Separation performance appears to improve with increasing adsorption pressure, but because there are a number of interrelated variables that are also effected by pressure, further testing will be needed to verify this. The work demonstrates that a molecular sieve carbon can be used to separate a mixture of methane and nitrogen when used in a pressure swing cycle with regeneration by purge. Further work is needed to increase product purity and product recovery.

  20. Inactivation factors of spore-forming bacteria using low-pressure microwave plasmas in an N2 and O2 gas mixture

    NASA Astrophysics Data System (ADS)

    Singh, M. K.; Ogino, A.; Nagatsu, M.

    2009-11-01

    In this study, we investigated the inactivation characteristics of Geobacillus stearothermophilus spores under different plasma exposure conditions using low-pressure microwave plasma in nitrogen, oxygen and an air-simulated (N2:O2=4:1) gas mixture. The microwave-excited surface-wave plasma discharges were produced at low pressure by a large volume device. The directly plasma-exposed spores, up to 106 populations, were successfully inactivated within 15, 10 and 5 min of surface-wave plasma treatment using nitrogen, oxygen and an air-simulated gas mixture, respectively, as working gases within the temperature of 75 °C. The contribution of different inactivation factors was evaluated by placing different filters (e.g. a LiF plate, a quartz plate and a Tyvek® sheet) as indirect exposure of spores to the plasma. It was observed that optical emissions (including vacuum UV (VUV)/UV) play an important role in the inactivation process. To further evaluate the effect of VUV/UV photons, we placed an evacuated isolated chamber, inside which spores were set, into the main plasma chamber. The experimental results show that the inactivation time by VUV/UV photons alone, without working gas in the immediate vicinity of the spores, is longer than that with working gas. This suggests that the VUV/UV emission is responsible not only for direct UV inactivation of spores but also for generation of reactive neutral species by photoexcitation. The scanning electron microscopy images revealed significant changes in the morphology of directly plasma-exposed spores but no change in the spores irradiated by VUV/UV photons only.

  1. Complex mixture analysis based on gas chromatography-mass spectrometry with time array detection using a beam deflection time-of-flight mass spectrometer.

    PubMed

    Schultz, G A; Chamberlin, B A; Sweeley, C C; Watson, J T; Allison, J

    1992-01-31

    A beam deflection time-of-flight mass spectrometer was developed in conjunction with an integrating transient recorder to provide time array detection, permitting high mass spectral scan file acquisition rates for complex mixture analysis by capillary gas chromatography-mass spectrometry (GC-MS). Results are presented for the analysis of a urinary organic acid mixture by GC-MS at a scan file acquisition rate of 10 scan files per second (sf/s), showing the advantages of such data collection in the deconvolution of partially resolved components. The reconstructed total ion current (RTIC) chromatogram available from data acquired at this scan file generation rate is shown to be comparable to the profile obtained from a flame ionization detector in representing the chromatography performed under identical experimental parameters. The RTIC chromatogram available from the database obtained at 10 sf/s is compared with that available from a database obtained at 1 sf/s, the latter representing that scan rate typically used with most GC-MS instruments. The advantages of the higher scan file acquisition rate in representing the chromatographic profile and in allowing mass spectral data to be obtained for components in the complex mixture that are unresolved chromatographically are discussed.

  2. Picosecond-TALIF and VUV absorption measurements of absolute atomic nitrogen densities from an RF atmospheric pressure plasma jet with He/O2/N2 gas mixtures

    NASA Astrophysics Data System (ADS)

    West, Andrew; Niemi, Kari; Schröter, Sandra; Bredin, Jerome; Gans, Timo; Wagenaars, Erik

    2015-09-01

    Reactive Oxygen and Nitrogen species (RONS) from RF atmospheric pressure plasma jets (APPJs) are important in biomedical applications as well as industrial plasma processing such as surface modification. Atomic oxygen has been well studied, whereas, despite its importance in the plasma chemistry, atomic nitrogen has been somewhat neglected due to its difficulty of measurement. We present absolute densities of atomic nitrogen in APPJs operating with He/O2/N2 gas mixtures in open air, using picosecond Two-photon Absorption Laser Induced Fluorescence (ps-TALIF) and vacuum ultra-violet (VUV) absorption spectroscopy. In order to apply the TALIF technique in complex, He/O2/N2 mixtures, we needed to directly measure the collisional quenching effects using picosecond pulse widths (32ps). Traditional calculated quenching corrections, used in nanosecond TALIF, are inadequate due to a lack of quenching data for complex mixtures. Absolute values for the densities were found by calibrating against a known density of Krypton. The VUV absorption experiments were conducted on the DESIRS synchrotron beamline using a unique VUV Fourier-transform spectrometer. Atomic nitrogen densities were on the order of 1020 m-3 with good agreement between TALIF and VUV absorption. UK EPSRC grant EP/K018388/1.

  3. Steam-injected gas turbine analysis: steam rates

    NASA Astrophysics Data System (ADS)

    Rice, I. G.

    1995-04-01

    This paper presents an analysis of steam rates in steam-injected gas turbines (simple and reheat). In considering a gas turbine of this type, the steam-injection flow is separated from the main gas stream for analysis. Dalton's and Avogadro's laws of partial pressure and gas mixtures are applied. Results obtained provide for the accurate determination of heat input, gas expansion based on partial pressures, and heat-rejection steam-enthalpy points.

  4. Corrosion of 310 stainless steel in H2-H2O-H2S gas mixtures: Studies at constant temperature and fixed oxygen potential

    NASA Technical Reports Server (NTRS)

    Rao, D. B.; Jacob, K. T.; Nelson, H. G.

    1981-01-01

    Corrosion of SAE 310 stainless steel in H2-H2O-H2S gas mixtures was studied at a constant temperature of 1150 K. Reactive gas mixtures were chosen to yield a constant oxygen potential of approximately 6 x 10 to the minus 13th power/cu Nm and sulfur potentials ranging from 0.19 x 10 to the minus 2nd power/cu Nm to 33 x 10 to the minus 2nd power/cu Nm. The kinetics of corrosion were determined using a thermobalance, and the scales were analyzed using metallography, scanning electron microscopy, and energy dispersive X-ray analysis. Two corrosion regimes, which were dependent on sulfur potential, were identified. At high sulfur potentials (p sub S sub 2 less than or equal to 2.7 x 10 to the minus 2nd power/cu Nm) the corrosion rates were high, the kinetics obeyed a linear rate equation, and the scales consisted mainly of sulfide phases similar to those observed from pure sulfication. At low sulfur potentials (P sub S sub 2 less than or equal to 0.19 x 10 to the minus 2nd power/cu Nm) the corrosion rates were low, the kinetics obeyed a parabolic rate equation, and scales consisted mainly of oxide phases.

  5. Women candidates for diving with oxygen-enriched gas mixtures have a lower end tidal CO2 than men during moderate exercise.

    PubMed

    Eynan, Mirit; Abramovich, Amir; Arieli, Yehuda

    2013-12-01

    We have previously determined the thresholds for CO2 detection (conscious recognition of elevated CO2) and retention in male divers, beyond which a diving candidate should not continue his diving activity due to an increased risk of CNS oxygen toxicity. The purpose of the present study was to establish whether there is a difference in end tidal PCO2 between male and female divers who use oxygen-enriched gas mixtures. Ventilatory and perceptual responses to variations in inspired CO2 (range 0-42 mm Hg) were assessed during moderate exercise in 18 males and 18 females. End tidal PCO2 was lower in the female divers when breathing oxygen with 42 mm Hg CO2 (58.2±3.0 mm Hg vs. 61.5±4.5 mm Hg, P<0.03). These results suggest that female divers have a lower end tidal CO2 than males when breathing a hyperoxic gas mixture during exercise, which might imply that women are less susceptible to CNS oxygen toxicity than men.

  6. Experimental determination of the retention time of reduced temperature of gas-vapor mixture in trace of water droplets moving in counterflow of combustion products

    NASA Astrophysics Data System (ADS)

    Volkov, R. S.; Kuznetsov, G. V.; Strizhak, P. A.

    2016-06-01

    We have experimentally studied temporal variation of the temperature of gas-vapor mixture in the trace of water droplets moving in the counterflow of high-temperature combustion products. The initial gas temperature was within 500-950 K. The water droplet radius in the aerosol flow varied from 40 to 400 μm. The motion of water droplets in the counterflow of combustion products in a 1-m-high hollow quartz cylinder with an internal diameter of 20 cm was visualized by optical flow imaging techniques (interferometric particle imaging, shadow photography, particle tracking velocimetry, and particle image velocimetry) with the aid of a cross-correlation complex setup. The scale of temperature decrease in the mixture of combustion products and water droplets was determined for a pulsed (within 1 s) and continuous supply of aerosol with various droplet sizes. Retention times of reduced temperature (relative to the initial level) in trace of water droplets (aerosol temperature trace) are determined. A hypothesis concerning factors responsible for the variation of temperature in the trace of droplets moving in the counterflow of combustion products is experimentally verified.

  7. Letter: Fast detection of polycyclic aromatic hydrocarbons in complex mixtures of organic compounds based on gas chromatography-mass spectrometry with atmospheric pressure photoionization.

    PubMed

    Revelsky, Igor A; Tikhonova, I N; Yashin, Yu S

    2015-01-01

    The research is devoted to the investigation of the selectivity detection of 16 polycyclic aromatic hydrocarbons (PAHs) using gas chromatography-mass spectrometry (GC-MS), electron ionization (EI) GC-MS with atmospheric pressure photoionization (APPhI) and GC-MS atmospheric pressure photochemical ionization (APPhCI) when vapors of different substances (benzene, toluene, and naphthalene) were used as gas reagents. Capillary columns of different lengths were used for the separation of the components of the mixture of 44 semivolatile organic compounds. It was shown that the most-selective detection of 16 PAHs in a 44- component mixture was possible when GC-MS APPhCI was used. Only 16 PAHs were registered on the respective mass chromatograms and a fast detection of them was possible. The respective APPhI and APPhCI mass spectra consisted of only peak of the respective molecular ion, M⁺⁺ - the radical cation. Detection limits were 3 pg μL⁻¹ to 15 pg μL. PMID:26579932

  8. Flow pattern changes influenced by variation of viscosities of a heterogeneous gas-liquid mixture flow in a vertical channel

    SciTech Connect

    Keska, Jerry K.; Hincapie, Juan; Jones, Richard

    2011-02-15

    In the steady-state flow of a heterogeneous mixture such as an air-liquid mixture, the velocity and void fraction are space- and time-dependent parameters. These parameters are the most fundamental in the analysis and description of a multiphase flow. The determination of flow patterns in an objective way is extremely critical, since this is directly related to sudden changes in spatial and temporal changes of the random like characteristic of concentration. Flow patterns can be described by concentration signals in time, amplitude, and frequency domains. Despite the vital importance and countless attempts to solve or incorporate the flow pattern phenomena into multiphase models, it has still been a very challenging topic in the scientific community since the 1940's and has not yet reached a satisfactory solution. This paper reports the experimental results of the impact of fluid viscosity on flow patterns for two-phase flow. Two-phase flow was created in laboratory equipment using air and liquid as phase medium. The liquid properties were changed by using variable concentrations of glycerol in water mixture which generated a wide-range of dynamic viscosities ranging from 1 to 1060 MPa s. The in situ spatial concentration vs. liquid viscosity and airflow velocity of two-phase flow in a vertical ID=50.8 mm pipe were measured using two concomitant computer-aided measurement systems. After acquiring data, the in situ special concentration signals were analyzed in time (spatial concentration and RMS of spatial concentration vs. time), amplitude (PDF and CPDF), and frequency (PSD and CPSD) domains that documented broad flow pattern changes caused by the fluid viscosity and air velocity changes. (author)

  9. How to make Raman-inactive helium visible in Raman spectra of tritium-helium gas mixtures

    SciTech Connect

    Schloesser, M.; Pakari, O.; Rupp, S.; Mirz, S.; Fischer, S.

    2015-03-15

    Raman spectroscopy, a powerful method for the quantitative compositional analysis of molecular gases, e.g. mixtures of hydrogen isotopologues, is not able to detect monoatomic species like helium. This deficit can be overcome by using radioluminescence emission from helium atoms induced by β-electrons from tritium decay. We present theoretical considerations and combined Raman/radioluminescence spectra. Furthermore, we discuss the linearity of the method together with validation measurements for determining the pressure dependence. Finally, we conclude how this technique can be used for samples of helium with traces of tritium, and vice versa. (authors)

  10. Cluster Regime—The New Regime Of Flowing Of Gas-Liquid Mixture In Vertical Columns (Based On Experimental Data)

    NASA Astrophysics Data System (ADS)

    Ozerov, A. Yu.

    2010-03-01

    For the revealing of the reasons of occurrence of discrete volcanic explosions of basalt magma the Complex Apparatus for Modeling Basaltic Eruptions (CAMBE) has been developed. It consists of two major systems—modeling and recording. The device is 18 meters high. During experiments gas-saturated model liquid acts from the saturator to the vertical transparent hose in which arising two-phase structures and its kinetics are studied. The experiments resulted in detecting and describing a new, never before known, mode of gas-liquid two-phase flow in a vertical column—defined here as cluster regime, which is characterized by regular alteration of dense gas bubble clusters separated from each other by the liquid not containing free gas phase. The mechanism of the cluster regime formation is conditioned by the processes of blocking of the hose working section by one big bubble or several smaller ones. It has been demonstrated that liquid, bubble, cluster and slug regime are regularly sequential and present polymorphic modifications of gas-saturated liquids migrating within vertically oriented conduits. Analysis of data on explosions at volcanoes, given the obtained experimental data on the mechanism of this process, allows concluding that realization of cluster or slug regimes in volcanic crater produces basaltic explosions.

  11. Mixture Experiments

    SciTech Connect

    Piepel, Gregory F.

    2007-12-01

    A mixture experiment involves combining two or more components in various proportions or amounts and then measuring one or more responses for the resulting end products. Other factors that affect the response(s), such as process variables and/or the total amount of the mixture, may also be studied in the experiment. A mixture experiment design specifies the combinations of mixture components and other experimental factors (if any) to be studied and the response variable(s) to be measured. Mixture experiment data analyses are then used to achieve the desired goals, which may include (i) understanding the effects of components and other factors on the response(s), (ii) identifying components and other factors with significant and nonsignificant effects on the response(s), (iii) developing models for predicting the response(s) as functions of the mixture components and any other factors, and (iv) developing end-products with desired values and uncertainties of the response(s). Given a mixture experiment problem, a practitioner must consider the possible approaches for designing the experiment and analyzing the data, and then select the approach best suited to the problem. Eight possible approaches include 1) component proportions, 2) mathematically independent variables, 3) slack variable, 4) mixture amount, 5) component amounts, 6) mixture process variable, 7) mixture of mixtures, and 8) multi-factor mixture. The article provides an overview of the mixture experiment designs, models, and data analyses for these approaches.

  12. Performance and emission characteristics of the thermal barrier coated SI engine by adding argon inert gas to intake mixture.

    PubMed

    Karthikeya Sharma, T

    2015-11-01

    Dilution of the intake air of the SI engine with the inert gases is one of the emission control techniques like exhaust gas recirculation, water injection into combustion chamber and cyclic variability, without scarifying power output and/or thermal efficiency (TE). This paper investigates the effects of using argon (Ar) gas to mitigate the spark ignition engine intake air to enhance the performance and cut down the emissions mainly nitrogen oxides. The input variables of this study include the compression ratio, stroke length, and engine speed and argon concentration. Output parameters like TE, volumetric efficiency, heat release rates, brake power, exhaust gas temperature and emissions of NOx, CO2 and CO were studied in a thermal barrier coated SI engine, under variable argon concentrations. Results of this study showed that the inclusion of Argon to the input air of the thermal barrier coated SI engine has significantly improved the emission characteristics and engine's performance within the range studied.

  13. Performance and emission characteristics of the thermal barrier coated SI engine by adding argon inert gas to intake mixture

    PubMed Central

    Karthikeya Sharma, T.

    2014-01-01

    Dilution of the intake air of the SI engine with the inert gases is one of the emission control techniques like exhaust gas recirculation, water injection into combustion chamber and cyclic variability, without scarifying power output and/or thermal efficiency (TE). This paper investigates the effects of using argon (Ar) gas to mitigate the spark ignition engine intake air to enhance the performance and cut down the emissions mainly nitrogen oxides. The input variables of this study include the compression ratio, stroke length, and engine speed and argon concentration. Output parameters like TE, volumetric efficiency, heat release rates, brake power, exhaust gas temperature and emissions of NOx, CO2 and CO were studied in a thermal barrier coated SI engine, under variable argon concentrations. Results of this study showed that the inclusion of Argon to the input air of the thermal barrier coated SI engine has significantly improved the emission characteristics and engine’s performance within the range studied. PMID:26644918

  14. Characteristics of atmospheric-pressure non-thermal N{sub 2} and N{sub 2}/O{sub 2} gas mixture plasma jet

    SciTech Connect

    Xiao, Dezhi; Shen, Jie; Lan, Yan; Xie, Hongbing; Shu, Xingsheng; Meng, Yuedong; Li, Jiangang; Cheng, Cheng E-mail: paul.chu@cityu.edu.hk; Chu, Paul K. E-mail: paul.chu@cityu.edu.hk

    2014-01-21

    An atmospheric-pressure non-thermal plasma jet driven by high frequency alternating current and operating on N{sub 2} and N{sub 2}/O{sub 2} gas mixture is investigated. The plasma jet can reach 55 mm in length at a gas flow rate of 2500 l/h. The gas temperature at a distance of 4 mm from the nozzle is close to room temperature. Optical emission spectroscopy is employed to investigate the important plasma parameters such as the excited species, rotational temperature, vibrational temperature, and excitation temperature under different discharge conditions. The results show that the plasma source operates under non-equilibrium conditions. The absolute irradiance intensity of the vibrational band N{sub 2}(C-B) in the active region is measured. Taking into account the irradiance intensity of N{sub 2}(C-B,0-0) and N{sub 2}(B-X,0-0) as well as measured current, the electron density, which is determined by considering direct and step-wise electron impact excitation of nitrogen emission, reaches a maximum value of 5.6 × 10{sup 20}/m{sup 3}.

  15. Performance of a gas flow ionization detector filled with He-iso-C4H10 mixtures for STIM-T

    NASA Astrophysics Data System (ADS)

    Marques, A. C.; Fraga, M. M. F. R.; Fonte, P.; Beasley, D. G.; Cruz, C.; Alves, L. C.; da Silva, R. C.

    2015-04-01

    A cylindrical gas flow ionization chamber has been developed for measuring particle energy in Scanning Transmission Ion Microscopy Tomography (STIM-T) experiments due to its ability to withstand the direct beam. The response of a He-iso-C4H10 filled ionization detector to 2 MeV H+ and He+ beams was studied. Different operating parameters, such as concentration of isobutane (in the range of 55-100%), anode voltage, amplifier shaping time, the geometry of the detector entrance canal and the solid angle of the detector, were investigated. The stable operating plateau and the anode voltage at which the best energy resolution is attained were also determined for every gas mixture. The best energy resolution achieved so far for 2 MeV H+ and He+ static beams was ∼1.3%, which is comparable to that of Si PIN diode detectors (in the range of 15-30 keV). Computed tomography (CT) was applied to a set of STIM projections acquired with the gas ionization chamber at the IST/CTN microprobe beam line in order to visualize the 3D-mass distribution in a test structure.

  16. Synthesis of ZrO{sub 2} in molten salt mixtures: Control of the evolved gas and the oxide texture

    SciTech Connect

    Afanasiev, P.; Geantet, C.; Lacroix, M.; Breysse, M.

    1996-08-01

    The authors investigated a mixture of KNO{sub 3}-NaNO{sub 3}-Na{sub 2}CO{sub 3} as a reaction medium for the preparation of ZrO{sub 2}. The formation of ZrO{sub 2} in molten nitrate can be considered as an acid-base reaction in which the zirconium salt plays the role of an acid and the melt anions that of a base. The higher reactivity of the carbonate ion in comparison to that of nitrate could modify the reaction mechanism, and different physico-chemical properties of the resulting solid could be expected. Carbonate may also act as a textural modifier similarly to preparations performed in aqueous media. 20 refs.

  17. Gas-phase diffusion in porous media: Evaluation of an advective- dispersive formulation and the dusty-gas model including comparison to data for binary mixtures

    SciTech Connect

    Webb, S.W.

    1996-05-01

    Two models for gas-phase diffusion and advection in porous media, the Advective-Dispersive Model (ADM) and the Dusty-Gas Model (DGM), are reviewed. The ADM, which is more widely used, is based on a linear addition of advection calculated by Darcy`s Law and ordinary diffusion using Fick`s Law. Knudsen diffusion is often included through the use of a Klinkenberg factor for advection, while the effect of a porous medium on the diffusion process is through a porosity-tortuosity-gas saturation multiplier. Another, more comprehensive approach for gas-phase transport in porous media has been formulated by Evans and Mason, and is referred to as the Dusty- Gas Model (DGM). This model applies the kinetic theory of gases to the gaseous components and the porous media (or ``dust``) to develop an approach for combined transport due to ordinary and Knudsen diffusion and advection including porous medium effects. While these two models both consider advection and diffusion, the formulations are considerably different, especially for ordinary diffusion. The various components of flow (advection and diffusion) are compared for both models. Results from these two models are compared to isothermal experimental data for He-Ar gas diffusion in a low-permeability graphite. Air-water vapor comparisons have also been performed, although data are not available, for the low-permeability graphite system used for the helium-argon data. Radial and linear air-water heat pipes involving heat, advection, capillary transport, and diffusion under nonisothermal conditions have also been considered.

  18. Flow of polydisperse gas-particle mixture in a duct followed by coagulation in a nonlinear wave field

    NASA Astrophysics Data System (ADS)

    Tukmakov, A. L.; Bayanov, R. I.; Tukmakov, D. A.

    2015-05-01

    Numerical simulation of the flow of an aerosol of polydisperse composition in a plane duct, where the resonance acoustic oscillations are generated, which are directed across the flow, has been carried out. The peculiarities of the flow, which is followed by coagulation and alteration of the distribution of particles over their sizes, have been described. The carrying medium has been modeled with the aid of the system of Navier-Stokes equations for compressible heat-conducting gas. The polydisperse phase dynamics is described by the systems of equations involving the equations of continuity, conservation of the momentum and internal energy. Equations of the motion of carrying medium and disperse fractions are written with allowance for interphase exchange by the momentum and energy. A Lagrangian model has been used to describe the coagulation process. The dispersion alteration in the gas-particle flow under the action of acoustic oscillations, which are resonant for the duct cross section, is analyzed.

  19. Low-pressure plasma-etching of bulk polymer materials using gas mixture of CF{sub 4} and O{sub 2}

    SciTech Connect

    Nabesawa, Hirofumi; Hiruma, Takaharu; Seki, Minoru; Hitobo, Takeshi; Wakabayashi, Suguru; Asaji, Toyohisa; Abe, Takashi

    2013-11-15

    In this study, we have proposed a low-pressure reactive ion etching of bulk polymer materials with a gas mixture of CF{sub 4} and O{sub 2}, and have achieved precise fabrication of poly(methyl methacrylate) (PMMA) and perfluoroalkoxy (PFA) bulk polymer plates with high-aspect-ratio and narrow gap array structures, such as, pillar, frustum, or cone, on a nano/micro scale. The effects of the etching conditions on the shape and size of each pillar were evaluated by changing etching duration and the size/material of etching mask. The fabricated PMMA array structures indicate possibilities of optical waveguide and nanofiber array. PFA cone array structures showed super-hydrophobicity without any chemical treatments. Also, polystyrene-coated silica spheres were used as an etching mask for the pillar array structure formation to control the gap between pillars.

  20. Analysis of a mixture of polychlorinated biphenyls and chlorinated pesticides in human serum by column fractionation and dual-column capillary gas chromatography with electron capture detection.

    PubMed

    Najam, A R; Korver, M P; Williams, C C; Burse, V W; Needham, L L

    1999-01-01

    An analytical method is presented for precise identification and quantitation of 29 specific polychlorinated biphenyl (PCB) congeners and 15 chlorinated pesticides in human serum. Analyte surrogates PCB 30, PCB 204, 2,2',4,4',5,5'-hexabromo-biphenyl, perthane, alpha-hexachlorocyclohexane, and dichlorobenzophenone were added to each sample. The serum was extracted with an organic solvent and separated by adsorption chromatography into 3 elution fractions for high-resolution gas chromatographic analysis. Each fraction was analyzed by dual-column capillary chromatography followed by electron capture detection. Two capillary columns, DB-5 and DB-1701, with different polarities were used to increase selectivity for each analyte. Quantitation was performed by selecting 2 sets of calibration standard mixtures and 1,2-dichloronaphthalene as an internal standard. Mean recoveries ranged from 39 to 126% for selected analytes and from 31 to 88% for surrogates. Detection limits for specific congeners and pesticides are reported. Typical chromatographic profiles of calibration standard mixtures, as well as a human sample, are illustrated. Verification of each analyte is assessed, and results of analyses of selected human samples and quality control criteria used to ensure data validity also are presented.