Sample records for saturation vapor pressure

  1. Saturated-liquid densities and vapor pressures of 1,1,1-trifluoroethane, difluoromethane, and pentafluoroethane

    Microsoft Academic Search

    Januarius V. Widiatmo; Haruki Sato; Koichi Watanabe

    1994-01-01

    Saturated-liquid densities and vapor pressures of HFC-143a (1,1,1-trifluoroethane), HFC-32(difluoromethane), and HFC-125 (pentafluoroethane) were measured by a magnetic densimeter coupled with a metallic bellows in the range of temperatures from 220 to 340 K. The experimental uncertainties for temperature, pressure, and density measurements are estimated to be not greater than [+-]15 mK, [+-]10 kPa (for HFC-143a) or [+-]2 kPa (for HFC-32

  2. Saturated-liquid densities and vapor pressures of 1,1,1-trifluoroethane, difluoromethane, and pentafluoroethane

    SciTech Connect

    Widiatmo, J.V.; Sato, Haruki; Watanabe, Koichi (Keio Univ., Yokohama (Japan). Dept. of Mechanical Engineering)

    1994-04-01

    Saturated-liquid densities and vapor pressures of HFC-143a (1,1,1-trifluoroethane), HFC-32(difluoromethane), and HFC-125 (pentafluoroethane) were measured by a magnetic densimeter coupled with a metallic bellows in the range of temperatures from 220 to 340 K. The experimental uncertainties for temperature, pressure, and density measurements are estimated to be not greater than [+-]15 mK, [+-]10 kPa (for HFC-143a) or [+-]2 kPa (for HFC-32 and HFC-125), and [+-]0.2%, respectively. The purities of HFC-143a, HFC-32, and HFC-125 used in the present measurements are 99.0 mol %, 99.998 mass %, and 99.8 mass %, respectively.

  3. Determination of saturation pressure and enthalpy of vaporization of semi-volatile aerosols: the integrated volume mentod

    EPA Science Inventory

    This study presents the integrated volume method for estimating saturation pressure and enthalpy of vaporization of a whole aerosol distribution. We measure the change of total volume of an aerosol distribution between a reference state and several heated states, with the heating...

  4. Binary nucleation of water--sulfuric acid system: Comparison of classical theories with different H sub 2 SO sub 4 saturation vapor pressures

    SciTech Connect

    Kulmala, M.; Laaksonen, A. (University of Helsinki, Department of Physics, Siltavuorenpenger 20D, SF-00170 Helsinki (Finland))

    1990-07-01

    The classical hydrates interaction model and the classical condensation model have been compared in the temperature range 153.15--363.15 K. Various expressions for the kinetic part of nucleation rate have been examined. In the present study the saturation vapor pressure values of sulfuric acid given by Ayers {ital et} {ital al}. are extrapolated to lower (stratospheric) temperatures taking into account the temperature dependence of the enthalpy of vaporization. In our model calculations we have compared the effect of three different expressions for saturation vapor pressures. The nucleation rate will differ by several orders of magnitude (depending on temperature, water and acid activity) when using different theories and/or saturation vapor pressures.

  5. Vapor Pressure Data

    NSDL National Science Digital Library

    Ohe, Shuzo.

    Created by Professor Shuzo Ohe of the Graduate School of Chemical Engineering and the Science University or Tokyo, this site offers vapor pressure data. Available in graph form, data represent vapor pressure (mmHg) as a function of temperature (C, or F). Substances are listed alphabetically and include acetaldehyde, acetic acid, benzene, butane, carbon dioxide, and water, to name a few.

  6. Configuration and testing of a saturated vapor helium compressor

    Microsoft Academic Search

    Jill L. Ludwigsen; J. L. Smith Jr.; Y. Iwasa

    1986-01-01

    A saturated vapor helium compressor was designed and tested as a component of a helium-temperature refrigeration cycle. The use of the cold compressor allows reduction of both the precooling heat exchanger area and main compressor size compared to a conventional cycle due to increased pressure of the return gas. The compressor tested was a single-piston reciprocating device which was controlled

  7. Vapor Pressure measurements for dichlorosilane

    E-print Network

    Morris, Tony Knimbula

    1997-01-01

    trichlorosilane and silicon tetrachloride, or other chemicals which are not in the silane family. Accurate information about the vapor pressure is necessary in the production of these mixtures. Measurements reported previously for the vapor pressure of pure...

  8. Vapor pressure measured with inflatable plastic bag

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Deflated plastic bag in a vacuum chamber measures initial low vapor pressures of materials. The bag captures the test sample vapors and visual observation of the vapor-inflated bag under increasing external pressures yields pertinent data.

  9. Configuration and testing of a saturated vapor helium compressor

    NASA Astrophysics Data System (ADS)

    Ludwigsen, Jill L.; Smith, J. L., Jr.; Iwasa, Y.

    A saturated vapor helium compressor was designed and tested as a component of a helium-temperature refrigeration cycle. The use of the cold compressor allows reduction of both the precooling heat exchanger area and main compressor size compared to a conventional cycle due to increased pressure of the return gas. The compressor tested was a single-piston reciprocating device which was controlled with programmable hydraulic/pneumatic logic. The compressor was mounted at the cold end of a CTI Model 1400 helium liquefier. An average compression ratio of 2.4 was obtained and an average efficiency of 82 percent was achieved. In computing compressor efficiency, external heat leaks to the compressor were neglected.

  10. A survey and new measurements of ice vapor pressure at temperatures between 170 and 250K

    Microsoft Academic Search

    James Marti; Konrad Mauersberger

    1993-01-01

    Saturated vapor pressures of ice at temperatures below 200K have become more important since the discovery of ice clouds in the polar stratosphere and upper mesosphere. Direct measurements of ice vapor pressures at such low temperatures are sparse and unreliable. This paper summarizes published vapor pressure data and presents new measurements at temperatures between 170 and 250K, extending the range

  11. Vapor Pressure Measurements in a Closed System

    ERIC Educational Resources Information Center

    Iannone, Mark

    2006-01-01

    An alternative method that uses a simple apparatus to measure vapor pressure versus temperature in a closed system, in which the total pressure is the vapor pressure of the liquid sample, is described. The use of this apparatus gives students a more direct picture of vapor pressure than the isoteniscope method and results have generally been quite…

  12. Enthalpy of Vaporization and Vapor Pressures: An Inexpensive Apparatus

    ERIC Educational Resources Information Center

    Battino, Rubin; Dolson, David A.; Hall, Michael A.; Letcher, Trevor M.

    2007-01-01

    A simple and inexpensive method to determine the enthalpy of vaporization of liquids by measuring vapor pressure as a function of temperature is described. The vapor pressures measured with the stopcock cell were higher than the literature values and those measured with the sidearm rubber septum cell were both higher and lower than literature…

  13. VAPOR PRESSURES AND HEATS OF VAPORIZATION OF PRIMARY COAL TARS

    SciTech Connect

    Eric M. Suuberg; Vahur Oja

    1997-07-01

    This project had as its main focus the determination of vapor pressures of coal pyrolysis tars. It involved performing measurements of these vapor pressures and from them, developing vapor pressure correlations suitable for use in advanced pyrolysis models (those models which explicitly account for mass transport limitations). This report is divided into five main chapters. Each chapter is a relatively stand-alone section. Chapter A reviews the general nature of coal tars and gives a summary of existing vapor pressure correlations for coal tars and model compounds. Chapter B summarizes the main experimental approaches for coal tar preparation and characterization which have been used throughout the project. Chapter C is concerned with the selection of the model compounds for coal pyrolysis tars and reviews the data available to us on the vapor pressures of high boiling point aromatic compounds. This chapter also deals with the question of identifying factors that govern the vapor pressures of coal tar model materials and their mixtures. Chapter D covers the vapor pressures and heats of vaporization of primary cellulose tars. Chapter E discusses the results of the main focus of this study. In summary, this work provides improved understanding of the volatility of coal and cellulose pyrolysis tars. It has resulted in new experimentally verified vapor pressure correlations for use in pyrolysis models. Further research on this topic should aim at developing general vapor pressure correlations for all coal tars, based on their molecular weight together with certain specific chemical characteristics i.e. hydroxyl group content.

  14. Non-LTE dust nucleation in sub-saturated vapors

    E-print Network

    Davide Lazzati

    2007-11-09

    We use the kinetic theory of nucleation to explore the properties of dust nucleation in sub-saturated vapors. Due to radiation losses, the sub-critical clusters have a smaller temperature compared to their vapor. This alters the dynamical balance between attachment and detachment of monomers, allowing for stable nucleation of grains in vapors that are sub-saturated for their temperature. We find this effect particularly important at low densities and in the absence of a strong background radiation field. We find new conditions for stable nucleation in the n-T phase diagram. The nucleation in the non-LTE regions is likely to be at much slower rate than in the super-saturated vapors. We evaluate the nucleation rate, warning the reader that it does depend on poorly substantiated properties of the macro-molecules assumed in the computation. On the other hand, the conditions for nucleation depend only on the properties of the large stable grains and are more robust. We finally point out that this mechanism may be relevant in the early universe as an initial dust pollution mechanism, since once the interstellar medium is polluted with dust, mantle growth is likely to be dominant over non-LTE nucleation in the diffuse medium.

  15. Film boiling of saturated liquid flowing upward through a heated tube : high vapor quality range

    E-print Network

    Laverty, W. F.

    1964-01-01

    Film boiling of saturated liquid flowing upward through a uniformly heated tube has been studied for the case in which pure saturated liquid enters the tube and nearly saturated vapor is discharged. Since a previous study ...

  16. Acoustics and precondensation phenomena in gas-vapor saturated mixtures

    NASA Astrophysics Data System (ADS)

    Guianvarc'h, C.; Bruneau, M.; Gavioso, R. M.

    2014-02-01

    Starting from fundamental hydrodynamics and thermodynamics equations for thermoviscous fluids, a new modeling procedure, which is suitable to describe acoustic propagation in gas mixtures, is presented. The model revises the boundary conditions which are appropriate to describe the condensation-evaporation processes taking place on a solid wall when one component of the mixture approaches saturation conditions. The general analytical solutions of these basic equations now give a unified description of acoustic propagation in an infinite, semi-infinite, or finite medium, throughout and beyond the boundary layers. The solutions account for the coupling between acoustic propagation and heat and concentration diffusion processes, including precondensation on the walls. The validity of the model and its predictive capability have been tested by a comparison with the description available in the literature of two particular systems (precondensation of propane and acoustic attenuation in a duct filled with an air-water vapor saturated mixture). The results of this comparison are discussed to clarify the relevance of the various physical phenomena that are involved in these processes. The model proposed here might be useful to develop methods for the acoustic determination of the thermodynamic and transport properties of gas mixtures as well as for practical applications involving gas and gas-vapor mixtures like thermoacoustics and acoustics in wet granular or porous media.

  17. Assessment of the Accuracy and Computing Speed of Simplified Saturation Vapor Equations Using a New Reference Dataset.

    NASA Astrophysics Data System (ADS)

    Gueymard, Christian

    1993-07-01

    A revised saturation vapor dataset is proposed for use in meteorology. Based on new engineering data of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers for temperatures above 0°C, it should supersede the older Smithsonian and World Meteorological Organization meteorological tables.Simple new equations are proposed to compute the saturation vapor pressure over water between 50° and 50°C. Their accuracy is shown to be excellent over this range, with an nns error of 3 × 103 mb and an average relative error of 0.02%. Detailed statistics descrbing the accuracy performance of 22 other equations are presented and the speed performance of all these equations is assessed. Nested polynomials are shown to provide both good accuracy and computational speed. On a modern minicomputer, a single evaluation of saturation vapor pressure may take less than 1 µs of CPU time, 15 times less than required by the Goff Gratch equations that were used to construct the meteorological tables.

  18. New Equations for Computing Vapor Pressure and Enhancement Factor.

    NASA Astrophysics Data System (ADS)

    Buck, Arden L.

    1981-12-01

    Equations are presented which relate saturation vapor pressure to temperature for moist air. The equations are designed to be easily implemented on a calculator or computer and can be used to convert in either direction. They are more accurate than the commonly used Goff-Gratch equations for the meteorologically interesting region of 80 to +50°C. Equations also are given for the enhancement factor.

  19. Ultrasonic speeds in compressed liquid and vapor pressures for pentafluoroethane

    Microsoft Academic Search

    Toshiharu Takagi; Toshiharu

    1996-01-01

    Ultrasonic speeds in the liquid phase of pentafluoroethane, CHFâCFâ, have been measured from 243.11 K to 333.15 K and pressures from near the saturation line to about 30 MPa. The measurement was carried out by means of a sing-around technique operated at a frequency of 2 MHz with an uncertainty no greater than {+-}0.2% in the high-density region. The vapor

  20. 40 CFR 796.1950 - Vapor pressure.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...airborne than chemicals with high vapor pressures or with low water solubility or low adsorptivity to solids and sediments...likely to be gases at ambient temperatures and which have low water solubility and low adsorptive tendencies are less...

  1. An Interpolation Method for Obtaining Thermodynamic Properties Near Saturated Liquid and Saturated Vapor Lines

    NASA Technical Reports Server (NTRS)

    Nguyen, Huy H.; Martin, Michael A.

    2004-01-01

    The two most common approaches used to formulate thermodynamic properties of pure substances are fundamental (or characteristic) equations of state (Helmholtz and Gibbs functions) and a piecemeal approach that is described in Adebiyi and Russell (1992). This paper neither presents a different method to formulate thermodynamic properties of pure substances nor validates the aforementioned approaches. Rather its purpose is to present a method to generate property tables from existing property packages and a method to facilitate the accurate interpretation of fluid thermodynamic property data from those tables. There are two parts to this paper. The first part of the paper shows how efficient and usable property tables were generated, with the minimum number of data points, using an aerospace industry standard property package. The second part describes an innovative interpolation technique that has been developed to properly obtain thermodynamic properties near the saturated liquid and saturated vapor lines.

  2. High temperature vapor pressure of pure plutonium

    Microsoft Academic Search

    M. H. Bradbury; R. W. Ohse

    1979-01-01

    High temperature vapor pressure measurements have been made on pure plutonium metal by the Knudsen effusion technique. The reported experimental results extend into the transition region between molecular and viscous or hydrodynamic flow. Under the conditions used, linearity was observed up to temperatures in excess of 2200 K where pressures approaching 100 Pa were measured. The results over the temperature

  3. Clausius-Clapeyron Equation and Saturation Vapour Pressure: Simple Theory Reconciled with Practice

    ERIC Educational Resources Information Center

    Koutsoyiannis, Demetris

    2012-01-01

    While the Clausius-Clapeyron equation is very important as it determines the saturation vapour pressure, in practice it is replaced by empirical, typically Magnus-type, equations which are more accurate. It is shown that the reduced accuracy reflects an inconsistent assumption that the latent heat of vaporization is constant. Not only is this…

  4. Vapor pressures of acetylene at low temperatures

    NASA Technical Reports Server (NTRS)

    Masterson, C. M.; Allen, John E., Jr.; Kraus, G. F.; Khanna, R. K.

    1990-01-01

    The atmospheres of many of the outer planets and their satellites contain a large number of hydrocarbon species. In particular, acetylene (C2H2) has been identified at Jupiter, Saturn and its satellite Titan, Uranus and Neptune. In the lower atmospheres of these planets, where colder temperatures prevail, the condensation and/or freezing of acetylene is probable. In order to obtain accurate models of the acetylene in these atmospheres, it is necessary to have a complete understanding of its vapor pressures at low temperatures. Vapor pressures at low temperatures for acetylene are being determined. The vapor pressures are measured with two different techniques in order to cover a wide range of temperatures and pressures. In the first, the acetylene is placed in a sample tube which is immersed in a low temperature solvent/liquid nitrogen slush bath whose temperature is measured with a thermocouple. The vapor pressure is then measured directly with a capacitance manometer. For lower pressures, a second technique which was called the thin-film infrared method (TFIR) was developed. It involves measuring the disappearance rate of a thin film of acetylene at a particular temperature. The spectra are then analyzed using previously determined extinction coefficient values, to determine the disappearance rate R (where R = delta n/delta t, the number of molecules that disappear per unit time). This can be related to the vapor pressure directly. This technique facilitates measurement of the lower temperatures and pressures. Both techniques have been calibrated using CO2, and have shown good agreement with the existing literature data.

  5. The Vapor Pressure of Plutonium Halides

    Microsoft Academic Search

    T. E. Phipps; G. W. Sears; R. L. Seifert; O. C. Simpson

    1950-01-01

    Vapor pressure measurements have been made with three halides of plutonium by a modification of the Knudsen effusion method. Measurements with solid plutonium trifluoride from 1200°K to 1440°K give the vapor pressure-temperature relation log10pmm=12.468–21,120\\/T. Measurements with liquid plutonium trifluoride from 1440°K to 1770°K give log10pmm=11.273–19,400\\/T. Measurements with solid plutonium trichloride from 850°K to 1007°K give log10pmm=12.726–15,910\\/T; with liquid trichloride from

  6. An Interpolation Method for Obtaining Thermodynamic Properties Near Saturated Liquid and Saturated Vapor Lines

    NASA Technical Reports Server (NTRS)

    Nguyen, Huy H.; Martin, Michael A.

    2003-01-01

    The availability and proper utilization of fluid properties is of fundamental importance in the process of mathematical modeling of propulsion systems. Real fluid properties provide the bridge between the realm of pure analytiis and empirical reality. The two most common approaches used to formulate thermodynamic properties of pure substances are fundamental (or characteristic) equations of state (Helmholtz and Gibbs functions) and a piecemeal approach that is described, for example, in Adebiyi and Russell (1992). This paper neither presents a different method to formulate thermodynamic properties of pure substances nor validates the aforementioned approaches. Rather its purpose is to present a method to be used to facilitate the accurate interpretation of fluid thermodynamic property data generated by existing property packages. There are two parts to this paper. The first part of the paper shows how efficient and usable property tables were generated, with the minimum number of data points, using an aerospace industry standard property package (based on fundamental equations of state approach). The second part describes an innovative interpolation technique that has been developed to properly obtain thermodynamic properties near the saturated liquid and saturated vapor lines.

  7. Ultrasonic speeds in compressed liquid and vapor pressures for pentafluoroethane

    SciTech Connect

    Takagi, Toshiharu [Kyoto Inst. of Tech. (Japan). Dept. of Chemistry] [Kyoto Inst. of Tech. (Japan). Dept. of Chemistry

    1996-11-01

    Ultrasonic speeds in the liquid phase of pentafluoroethane, CHF{sub 2}CF{sub 3}, have been measured from 243.11 K to 333.15 K and pressures from near the saturation line to about 30 MPa. The measurement was carried out by means of a sing-around technique operated at a frequency of 2 MHz with an uncertainty no greater than {+-}0.2% in the high-density region. The vapor pressures have also been measured by monitoring the difference in the absorption quantity of the acoustic wave, excited in the sample fluid, between the liquid and gas phases with an uncertainty of {+-} 10 kPa. From these results, the ultrasonic speeds for the saturated liquid were estimated with reasonable accuracy.

  8. MISTING OF LOW VAPOR PRESSURE HALOCARBONS

    EPA Science Inventory

    The paper gives results of a laboratory-scale study of the use of misting systems to provide total-flood fire protection with lower vapor pressure halocarbons. (NOTE: Several candidate Halon 1301 replacements with a low ozone-depletion potential have higher boiling points (usuall...

  9. On the propagation of a coupled saturation and pressure front

    Microsoft Academic Search

    2010-01-01

    Using an asymptotic technique, valid for a medium with smoothly varying heterogeneity, I derive an expression for the velocity of a propagating, coupled saturation and pressure front. Due to the nonlinearity of the governing equations, the velocity of the propagating front depends upon the magnitude of the saturation and pressure changes across the front in addition to the properties of

  10. Vapor pressure of pentafluoroethane and trifluoroiodomethane

    NASA Astrophysics Data System (ADS)

    Zhang, Chang; Duan, Yuanyuan; Shi, Lin; Zhu, Mingshan; Han, Lizhong

    2001-07-01

    Pentafluoroethane (HFC-125) and trifluoroiodomethane (CF3I) are considered as promising refrigerant alternatives, especially as components in mixtures, to replace CFCs or HCFCs. Effective uses of HFC-125 and CF3I require that the thermophysical properties be accurately measured. In the present work, vapor pressure data of HFC-125 and CF3I have been measured in the temperature range from 292 to 337 K and 288 to 336 K, respectively. Maximum total pressure uncertainty of HFC-125 data is estimated to be within ±1.2 kPa and ±780 Pa for CF3I. Based on the data set and literature values, the vapor pressure equations for HFC-125 and CF3I have been developed. The relative deviation of the equations correlate the measurements within 0.022% for HFC-125 and 0.068% for CF3I, respectively.

  11. A practical vapor pressure equation for helium-3 from 0.01 K to the critical point

    Microsoft Academic Search

    Y. H. Huang; G. B. Chen

    2006-01-01

    A saturation vapor pressure equation, p(T), is an essential component in the 3He state equation currently under development. The state equation is valid over the range 0.01–20K with pressures from 0 to the melting pressure or 15MPa. The vapor pressure equation consequently must be valid from 0.01K to the critical temperature. This paper surveys available 3He critical temperature and pressure

  12. Heating of a fully saturated darcian half-space: Pressure generation, fluid expulsion, and phase change

    USGS Publications Warehouse

    Delaney, P.

    1984-01-01

    Analytical solutions are developed for the pressurization, expansion, and flow of one- and two-phase liquids during heating of fully saturated and hydraulically open Darcian half-spaces subjected to a step rise in temperature at its surface. For silicate materials, advective transfer is commonly unimportant in the liquid region; this is not always the case in the vapor region. Volume change is commonly more important than heat of vaporization in determining the position of the liquid-vapor interface, assuring that the temperatures cannot be determined independently of pressures. Pressure increases reach a maximum near the leading edge of the thermal front and penetrate well into the isothermal region of the body. Mass flux is insensitive to the hydraulic properties of the half-space. ?? 1984.

  13. Topical and vapor toxicity of saturated fatty acids to the German cockroach (Dictyoptera: Blattellidae).

    PubMed

    Sims, Steven R; Balusu, Rammohan R; Ngumbi, Esther N; Appel, Arthur G

    2014-04-01

    Topical and fumigant toxicity of saturated aliphatic fatty acids with chain lengths of C1 through C14 were determined against the German cockroach, Blattella germanica (L.). In the C1 to C11 series, topical toxicity (LD50 in milligram per adult male) ranged from 0.145 (C1) to 0.322 mg (C2). Toxicity declined dramatically with C12 and C14 acids whose LD50 values could not be calculated. The relative fumigation toxicity (LC50 in microliter per liter) of C1 through C5 acids was positively correlated with topical toxicity with values ranging from 6.159 (C3) to 12.302 microl/liter (C2). Fumigant toxicity decreased sharply with C6 (LC50 = 37.691 microl/liter) and there was no mortality of cockroaches exposed to vapors from C7 to C14 acids. The low fumigant toxicity of the C6 to C11 acids was correlated with their relatively low vapor pressure, but differences in diffusion of the vapors into the spiracles and subsequent passage to the target sites may have also been involved. PMID:24772558

  14. Vapor pressure of pentafluoroethane and trifluoroiodomethane

    Microsoft Academic Search

    Chang Zhang; Yuanyuan Duan; Lin Shi; Mingshan Zhu; Lizhong Han

    2001-01-01

    Pentafluoroethane (HFC-125) and trifluoroiodomethane (CF3I) are considered as promising refrigerant alternatives, especially as components in mixtures, to replace CFCs or HCFCs. Effective\\u000a uses of HFC-125 and CF3I require that the thermophysical properties be accurately measured. In the present work, vapor pressure data of HFC-125 and\\u000a CF3I have been measured in the temperature range from 292 to 337 K and 288

  15. Vaporization Enthalpy and Vapor Pressure of Valproic Acid by Correlation Gas Chromatography

    E-print Network

    Chickos, James S.

    Vaporization Enthalpy and Vapor Pressure of Valproic Acid by Correlation Gas Chromatography Joe A by correlation-gas chromatography. This resulted in a vaporization enthalpy, Hvap(298.15 K) of (74.8 ± 2.4) k at T/K = 298.15, both derived by correlation-gas chromatography. The measurement of vaporization

  16. On the propagation of a coupled saturation and pressure front

    SciTech Connect

    Vasco, D. W.

    2010-12-01

    Using an asymptotic technique, valid for a medium with smoothly varying heterogeneity, I derive an expression for the velocity of a propagating, coupled saturation and pressure front. Due to the nonlinearity of the governing equations, the velocity of the propagating front depends upon the magnitude of the saturation and pressure changes across the front in addition to the properties of the medium. Thus, the expression must be evaluated in conjunction with numerical reservoir simulation. The propagation of the two-phase front is governed by the background saturation distribution, the saturation-dependent component of the fluid mobility, the porosity, the permeability, the capillary pressure function, the medium compressibility, and the ratio of the slopes of the relative permeability curves. Numerical simulation of water injection into a porous layer saturated with a nonaqueous phase liquid indicates that two modes of propagation are important. The fastest mode of propagation is a pressure-dominated disturbance that travels through the saturated layer. This is followed, much later, by a coupled mode with a large saturation change. These two modes are also observed in a simulation using a heterogeneous porous layer. A comparison between the propagation times estimated from the results of the numerical simulation and predictions from the asymptotic expression indicates overall agreement.

  17. Experimental critical constants, vapor pressures, and vapor and liquid densities for pentafluoroethane (R-125)

    Microsoft Academic Search

    Horacio A. Duarte-Garza; Carleton E. Stouffer; Kenneth R. Hall; James C. Holste; Kenneth N. Marsh; Bruce E. Gammon

    1997-01-01

    This paper presents measurements of vapor pressure from 220 K to 338 K, liquid density from 180 K to 350 K and up to 70 MPa and vapor density from 310 K to 480 K and up to 12 MPa for pentafluoroethane (R-125). Extrapolating the observed vapor pressures to the measured critical temperature (339.41 {+-} 0.01) K provides a critical

  18. Oxidation of trichloroethylene, toluene, and ethanol vapors by a partially saturated permeable reactive barrier

    NASA Astrophysics Data System (ADS)

    Mahmoodlu, Mojtaba G.; Hassanizadeh, S. Majid; Hartog, Niels; Raoof, Amir

    2014-08-01

    The mitigation of volatile organic compound (VOC) vapors in the unsaturated zone largely relies on the active removal of vapor by ventilation. In this study we considered an alternative method involving the use of solid potassium permanganate to create a horizontal permeable reactive barrier for oxidizing VOC vapors. Column experiments were carried out to investigate the oxidation of trichloroethylene (TCE), toluene, and ethanol vapors using a partially saturated mixture of potassium permanganate and sand grains. Results showed a significant removal of VOC vapors due to the oxidation. We found that water saturation has a major effect on the removal capacity of the permeable reactive layer. We observed a high removal efficiency and reactivity of potassium permanganate for all target compounds at the highest water saturation (Sw = 0.6). A change in pH within the reactive layer reduced oxidation rate of VOCs. The use of carbonate minerals increased the reactivity of potassium permanganate during the oxidation of TCE vapor by buffering the pH. Reactive transport of VOC vapors diffusing through the permeable reactive layer was modeled, including the pH effect on the oxidation rates. The model accurately described the observed breakthrough curve of TCE and toluene vapors in the headspace of the column. However, miscibility of ethanol in water in combination with produced water during oxidation made the modeling results less accurate for ethanol. A linear relationship was found between total oxidized mass of VOC vapors per unit volume of permeable reactive layer and initial water saturation. This behavior indicates that pH changes control the overall reactivity and longevity of the permeable reactive layer during oxidation of VOCs. The results suggest that field application of a horizontal permeable reactive barrier can be a viable technology against upward migration of VOC vapors through the unsaturated zone.

  19. Oxidation of trichloroethylene, toluene, and ethanol vapors by a partially saturated permeable reactive barrier.

    PubMed

    Mahmoodlu, Mojtaba G; Hassanizadeh, S Majid; Hartog, Niels; Raoof, Amir

    2014-08-01

    The mitigation of volatile organic compound (VOC) vapors in the unsaturated zone largely relies on the active removal of vapor by ventilation. In this study we considered an alternative method involving the use of solid potassium permanganate to create a horizontal permeable reactive barrier for oxidizing VOC vapors. Column experiments were carried out to investigate the oxidation of trichloroethylene (TCE), toluene, and ethanol vapors using a partially saturated mixture of potassium permanganate and sand grains. Results showed a significant removal of VOC vapors due to the oxidation. We found that water saturation has a major effect on the removal capacity of the permeable reactive layer. We observed a high removal efficiency and reactivity of potassium permanganate for all target compounds at the highest water saturation (Sw=0.6). A change in pH within the reactive layer reduced oxidation rate of VOCs. The use of carbonate minerals increased the reactivity of potassium permanganate during the oxidation of TCE vapor by buffering the pH. Reactive transport of VOC vapors diffusing through the permeable reactive layer was modeled, including the pH effect on the oxidation rates. The model accurately described the observed breakthrough curve of TCE and toluene vapors in the headspace of the column. However, miscibility of ethanol in water in combination with produced water during oxidation made the modeling results less accurate for ethanol. A linear relationship was found between total oxidized mass of VOC vapors per unit volume of permeable reactive layer and initial water saturation. This behavior indicates that pH changes control the overall reactivity and longevity of the permeable reactive layer during oxidation of VOCs. The results suggest that field application of a horizontal permeable reactive barrier can be a viable technology against upward migration of VOC vapors through the unsaturated zone. PMID:24992709

  20. On the propagation of a coupled saturation and pressure front

    NASA Astrophysics Data System (ADS)

    Vasco, D. W.

    2011-03-01

    Using an asymptotic technique, valid for a medium with smoothly varying heterogeneity, I derive an expression for the velocity of a propagating, coupled saturation and pressure front. The asymptotic approach produces an explicit expression for the slowness, the inverse of the velocity, of a propagating two-phase front. Because of the nonlinearity of the governing equations, the velocity of the propagating front depends upon the magnitude of the saturation and pressure changes across the front in addition to the properties of the medium. Thus, the expression must be evaluated in conjunction with numerical reservoir simulation. The slowness is governed by the background saturation distribution, the saturation-dependent component of the fluid mobility, the porosity, the permeability, the capillary pressure function, the medium compressibility, and the ratio of the slopes of the relative permeability curves. Numerical simulation of water injection into a porous layer saturated with a nonaqueous phase liquid indicates that two modes of propagation are important. The fastest mode of propagation is a disturbance that is dominated by the change in fluid pressure. This is followed, much later, by a coupled mode associated with a much larger saturation change. These two modes are also observed in a numerical simulation using a heterogeneous porous layer. A comparison between the propagation times estimated from the results of the numerical simulation and predictions from the asymptotic expression indicates overall agreement.

  1. 46 CFR 154.451 - Design vapor pressure.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Design vapor pressure. 154.451 Section 154.451 Shipping...Equipment Independent Tank Type C and Process Pressure Vessels § 154.451 Design vapor pressure. The Po (kPa) of an...

  2. 46 CFR 154.451 - Design vapor pressure.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Design vapor pressure. 154.451 Section 154.451 Shipping...Equipment Independent Tank Type C and Process Pressure Vessels § 154.451 Design vapor pressure. The Po (kPa) of an...

  3. 46 CFR 154.451 - Design vapor pressure.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 false Design vapor pressure. 154.451 Section 154.451 Shipping...Equipment Independent Tank Type C and Process Pressure Vessels § 154.451 Design vapor pressure. The Po (kPa) of an...

  4. 46 CFR 154.451 - Design vapor pressure.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 false Design vapor pressure. 154.451 Section 154.451 Shipping...Equipment Independent Tank Type C and Process Pressure Vessels § 154.451 Design vapor pressure. The Po (kPa) of an...

  5. 46 CFR 154.451 - Design vapor pressure.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 2013-10-01 false Design vapor pressure. 154.451 Section 154.451 Shipping...Equipment Independent Tank Type C and Process Pressure Vessels § 154.451 Design vapor pressure. The Po (kPa) of an...

  6. Using Monte Carlo simulation to compute liquid-vapor saturation properties of ionic liquids.

    PubMed

    Rane, Kaustubh S; Errington, Jeffrey R

    2013-07-01

    We discuss Monte Carlo (MC) simulation methods for calculating liquid-vapor saturation properties of ionic liquids. We first describe how various simulation tools, including reservoir grand canonical MC, growth-expanded ensemble MC, distance-biasing, and aggregation-volume-biasing, are used to address challenges commonly encountered in simulating realistic models of ionic liquids. We then indicate how these techniques are combined with histogram-based schemes for determining saturation properties. Both direct methods, which enable one to locate saturation points at a given temperature, and temperature expanded ensemble methods, which provide a means to trace saturation lines to low temperature, are discussed. We study the liquid-vapor phase behavior of the restricted primitive model (RPM) and a realistic model for 1,3-dimethylimidazolium tetrafluoroborate ([C1mim][BF4]). Results are presented to show the dependence of saturation properties of the RPM and [C1mim][BF4] on the size of the simulation box and the boundary condition used for the Ewald summation. For [C1mim][BF4] we also demonstrate the ability of our strategy to sample ion clusters that form in the vapor phase. Finally, we provide the liquid-vapor saturation properties of these models over a wide range of temperature. Overall, we observe that the choice of system size and boundary condition have a non-negligible effect on the calculated properties, especially at high temperature. Also, we find that the combination of grand canonical MC simulation and isothermal-isobaric temperature expanded ensemble MC simulation provides a computationally efficient means to calculate liquid-vapor saturation properties of ionic liquids. PMID:23734733

  7. Fuel Vapor Pressures and the Relation of Vapor Pressure to the Preparation of Fuel for Combustion in Fuel Injection Engines

    NASA Technical Reports Server (NTRS)

    Joachim, William F; Rothrock, A M

    1930-01-01

    This investigation on the vapor pressure of fuels was conducted in connection with the general research on combustion in fuel injection engines. The purpose of the investigation was to study the effects of high temperatures such as exist during the first stages of injection on the vapor pressures of several fuels and certain fuel mixtures, and the relation of these vapor pressures to the preparation of the fuel for combustion in high-speed fuel injection engines.

  8. On the propagation of a coupled saturation and pressure front

    Microsoft Academic Search

    D. W. Vasco

    2011-01-01

    Using an asymptotic technique, valid for a medium with smoothly varying heterogeneity, I derive an expression for the velocity of a propagating, coupled saturation and pressure front. The asymptotic approach produces an explicit expression for the slowness, the inverse of the velocity, of a propagating two-phase front. Because of the nonlinearity of the governing equations, the velocity of the propagating

  9. A last-saturation diagnosis of subtropical water vapor response to global warming

    Microsoft Academic Search

    John V. Hurley; Joseph Galewsky

    2010-01-01

    We used boreal winter output from an IPCC AR4 GCM simulation to drive an atmospheric tracer transport model with water vapor last saturation tracers over the northern hemisphere in order to identify processes that contribute to the projected increase in specific humidity of the subtropical relative humidity minimum. Most of the increase in specific humidity at the relative humidity minimum

  10. Preliminary assessment of condensation behavior for hydrocarbon-vapor expansions which cross the saturation line near the critical point

    SciTech Connect

    Demuth, O.J.

    1982-07-01

    Previous analyses of binary cycles for conversion of geothermal energy from moderate temperature resources to electrical energy have shown potential gains in net geofluid effectiveness of on the order of 8%, resulting from selection of turbine-expansion processes whose equilibrium states pass through the two-phase region (assuming major condensation does not occur). If condensation occurs, this gain could be reduced or eliminated by the resulting loss in turbine efficiency. Experience with many fluids, however, indicates that vapor supersaturation (or subcooling) permits metastable pure-vapor states to exist at temperatures considerably below the saturation temperature at a given pressure; thus, by better understanding the condensation process, and properly structuring the cycle, substantial performance gains may be achievable. The present study assessed, qualitatively, the probability for attaining this performance gain.

  11. Measurements of gaseous PVTx properties and saturated vapor densities of refrigerant mixture R-125 + R-143a

    SciTech Connect

    Uchida, H.; Sato, H.; Watanabe, K. [Keio Univ., Yokohama (Japan). Dept. of System Design Engineering] [Keio Univ., Yokohama (Japan). Dept. of System Design Engineering

    1999-01-01

    The experimental PVTx properties of a binary refrigerant mixture, R-125 (pentafluoroethane) + R-143a (1,1,1-trifluoroethane), have been measured for a composition of 50 mass% R-125 by a constant-mass method coupled with an expansion procedure in a range of temperatures from 305 to 400 K, pressures from 1.5 to 6.1 MPa, and densities from 92 to 300 kg {center_dot} m{sup {minus}3}. The experimental uncertainties of the present measurements are estimated to be within {+-} 7.2 mK in temperature, {+-} 3.0 ,Pa in pressure, {+-} 0.12 kg {center_dot} m{sup {minus}3} in density, and {+-} 0.040 mass% in composition. The sample purities are 99.953 mass% for R-125 and 99.998% for R-143a. Seven saturated vapor densities and dew point pressures of the R-125 + r-143a system were determined, on the basis of rather detailed PVTx properties measured in the vicinity of the saturation boundary as well as the thermodynamic behavior of isochores near saturation. The second and third virial coefficients for temperatures from 330 to 400 K were also determined.

  12. Vapor pressures and heats of vaporization of primary coal tars. Quarterly technical progress report, 1 October--31 December 1994

    SciTech Connect

    Suuberg, E.M.

    1995-04-01

    The vapor pressure correlations that exist at present for coal tars are very crude and they are not considered reliable to even an order of magnitude when applied to tars. The present project seeks to address this important gap in the near term by direct measurement of vapor pressures of coal tar fractions, by application of well-established techniques and modifications thereof. The principal objectives of the program are to: (1) obtain data on the vapor pressures and heats of vaporization of tars from a range of ranks of coal, (2) develop correlations based on a minimum set of conveniently measurable characteristics of the tars, and (3) develop equipment that would allow performing such measurements in a reliable, straightforward fashion. A significant amount of time has been devoted during this quarter to testing the equipment for measurements by the gas saturation method and the Knudsen effusion method. These techniques are beginning to yield reliable results. Some key features of the methods are summarized, and sample results presented.

  13. Experimental critical constants, vapor pressures, and vapor and liquid densities for pentafluoroethane (R-125)

    SciTech Connect

    Duarte-Garza, H.A.; Stouffer, C.E.; Hall, K.R.; Holste, J.C. [Texas A and M Univ., College Station, TX (United States). Dept. of Chemical Engineering] [Texas A and M Univ., College Station, TX (United States). Dept. of Chemical Engineering; Marsh, K.N.; Gammon, B.E. [Texas A and M Univ. System, College Station, TX (United States). Thermodynamics Research Center] [Texas A and M Univ. System, College Station, TX (United States). Thermodynamics Research Center

    1997-07-01

    This paper presents measurements of vapor pressure from 220 K to 338 K, liquid density from 180 K to 350 K and up to 70 MPa and vapor density from 310 K to 480 K and up to 12 MPa for pentafluoroethane (R-125). Extrapolating the observed vapor pressures to the measured critical temperature (339.41 {+-} 0.01) K provides a critical pressure of (3.6391 {+-} 0.002) MPa. Using these values with the law of rectilinear diameters indicates a critical density of (4,768{+-} 7) mol/m{sup 3}. Correlations provide values which agree with the measured values for the vapor densities within {+-}0.05%, the liquid densities within {+-}0.1%, and the vapor pressures within {+-}0.05%. The results are compared with values from the literature.

  14. Controlling the vapor pressure of a mercury lamp

    DOEpatents

    Grossman, M.W.; George, W.A.

    1988-05-24

    The invention described herein discloses a method and apparatus for controlling the Hg vapor pressure within a lamp. This is done by establishing and controlling two temperature zones within the lamp. One zone is colder than the other zone. The first zone is called the cold spot. By controlling the temperature of the cold spot, the Hg vapor pressure within the lamp is controlled. Likewise, by controlling the Hg vapor pressure of the lamp, the intensity and linewidth of the radiation emitted from the lamp is controlled. 2 figs.

  15. Pressure swing adsorption cycles for improved solvent vapor enrichment

    Microsoft Academic Search

    Yujun Liu; James A. Ritter; Bal K. Kaul

    2000-01-01

    A pressure swing adsorption (PSA)-solvent vapor recovery (SVR) process simulator was used to investigate new PSA cycle configurations designed for higher solvent vapor enrichment. These cycles were modifications of the four-step Skarstrom cycle used commercially for PSA-SVR and include the addition of a cocurrent blowdown step, and combinations of cocurrent blowdown and continuous\\/batch reflux steps. The recovery of gasoline vapor

  16. Two-phase pressure drop during CO 2 vaporization in horizontal smooth minichannels

    Microsoft Academic Search

    A. S. Pamitran; Kwang-Il Choi; Jong-Taek Oh; Hoo-Kyu Oh

    2008-01-01

    Pressure drop experiments for a natural refrigerant vaporization of CO2 were performed in horizontal minichannels. The test section was made of stainless steel tubes with inner diameters of 1.5mm and 3.0mm and with lengths of 2000 and 3000mm. This test section was uniformly heated by applying electric current directly to the tubes. Experiments were performed at inlet saturation temperatures of

  17. Optimal pressures and temperatures for isobaric, isothermal chemical vapor infiltration

    Microsoft Academic Search

    John Y. Ofori; Stratis V. Sotirchos

    1996-01-01

    Chemical vapor infiltration (CVI) is a method of ceramic or carbon matrix composite fabrication in which chemical vapor deposition reactions are employed to deposit the matrix material (ceramic or carbon) on the internal surface of a porous preform. This study addresses the possibility of identifying optimal pressure and temperature pairs that can be used to give the least processing time

  18. Water Vapor Saturation at Low Altitudes around Mars Aphelion: A Key to Mars Climate?

    Microsoft Academic Search

    R. T. Clancy; A. W. Grossman; M. J. Wolff; P. B. James; D. J. Rudy; Y. N. Billawala; B. J. Sandor; S. W. Lee; D. O. Muhleman

    1996-01-01

    The combined analysis of microwave temperature and water profiling of the Mars atmosphere indicates that low- to mid-latitude water vapor saturation typically occurs at much lower altitudes (below 10 km) during northern spring\\/summer than observed during this Mars aphelion season in the dusty, warm period of Viking observations (above 25 km). Temperatures profiles of the 0–60 km global Mars atmosphere

  19. Vapor pressures and vapor compositions in equilibrium with hypostoichiometric plutonium dioxide at high temperatures

    Microsoft Academic Search

    D. W. Green; J. K. Fink; L. Leibowitz

    1983-01-01

    Vapor pressures and vapor compositions in equilibrium with a hypostoichiometric plutonium dioxide condensed phase have been calculated for the temperature range 1500 less than or equal to T less than or equal to 4000 K. Thermodynamic functions for the condensed phase and for each of the gaseous species were combined with an oxygen-potential model, which has been extended from the

  20. A Simple Experiment for Determining Vapor Pressure and Enthalpy of Vaporization of Water.

    ERIC Educational Resources Information Center

    Levinson, Gerald S.

    1982-01-01

    Laboratory procedures, calculations, and sample results are described for a freshman chemistry experiment in which the Clausius-Clapeyron equation is introduced as a means of describing the variation of vapor pressure with temperature and for determining enthalpy of vaporization. (Author/SK)

  1. Using Dalton's Law of Partial Pressures to Determine the Vapor Pressure of a Volatile Liquid

    ERIC Educational Resources Information Center

    Hilgeman, Fred R.; Bertrand, Gary; Wilson, Brent

    2007-01-01

    This experiment, designed for a general chemistry laboratory, illustrates the use of Dalton's law of partial pressures to determine the vapor pressure of a volatile liquid. A predetermined volume of air is injected into a calibrated tube filled with a liquid whose vapor pressure is to be measured. The volume of the liquid displaced is greater than…

  2. Vapor Pressure of Caesium by the Positive Ion Method

    Microsoft Academic Search

    John Bradshaw Taylor; Irving Langmuir

    1937-01-01

    The positive ion currents from pure tungsten filaments in saturated caesium vapor at bulb temperatures from -35°C to +73°C were measured for filament temperatures from 1000° to 1800°K. The results were corrected for the cooling effect of the leads and for photoelectric emission from the caesium film on the platinum deposited on the bulb which was used as an ion

  3. Vapor pressure determination of hydroxy-cyclo-pentyl-butadiyne

    SciTech Connect

    Garza, R.G.; Colmenares, C.A.

    1983-10-18

    The vapor pressure for the hydrogen getter, Hydroxy-cyclo-pentyl-Butadiyne (HCPB), was determined thermogravimetrically by the Knudsen technique. Effusion rates were measured in the temperature range of 50 to 100/sup 0/C.

  4. 46 CFR 154.445 - Design vapor pressure.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Design, Construction and Equipment Independent Tank Type B § 154.445 Design vapor pressure. If the surfaces of an independent tank type B are mostly flat surfaces, the Po must not exceed 69 kPa gauge (10...

  5. 46 CFR 154.445 - Design vapor pressure.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...Design, Construction and Equipment Independent Tank Type B § 154.445 Design vapor pressure. If the surfaces of an independent tank type B are mostly flat surfaces, the Po must not exceed 69 kPa gauge (10...

  6. Development of a quasi-adiabatic calorimeter for the determination of the water vapor pressure curve

    NASA Astrophysics Data System (ADS)

    Mokdad, S.; Georgin, E.; Hermier, Y.; Sparasci, F.; Himbert, M.

    2012-07-01

    Progress in the knowledge of the water saturation curve is required to improve the accuracy of the calibrations in humidity. In order to achieve this objective, the LNE-CETIAT and the LNE-CNAM have jointly built a facility dedicated to the measurement of the saturation vapor pressure and temperature of pure water. The principle is based on a static measurement of the pressure and the temperature of pure water in a closed, temperature-controlled thermostat, conceived like a quasi-adiabatic calorimeter. A copper cell containing pure water is placed inside a temperature-controlled copper shield, which is mounted in a vacuum-tight stainless steel vessel immersed in a thermostated bath. The temperature of the cell is measured with capsule-type standard platinum resistance thermometers, calibrated with uncertainties below the millikelvin. The vapor pressure is measured by calibrated pressure sensors connected to the cell through a pressure tube whose temperature is monitored at several points. The pressure gauges are installed in a thermostatic apparatus ensuring high stability of the pressure measurement and avoiding any condensation in the tubes. Thanks to the employment of several technical solutions, the thermal contribution to the overall uncertainty budget is reduced, and the remaining major part is mainly due to pressure measurements. This paper presents a full description of this facility and the preliminary results obtained for its characterization.

  7. Development of a quasi-adiabatic calorimeter for the determination of the water vapor pressure curve.

    PubMed

    Mokdad, S; Georgin, E; Hermier, Y; Sparasci, F; Himbert, M

    2012-07-01

    Progress in the knowledge of the water saturation curve is required to improve the accuracy of the calibrations in humidity. In order to achieve this objective, the LNE-CETIAT and the LNE-CNAM have jointly built a facility dedicated to the measurement of the saturation vapor pressure and temperature of pure water. The principle is based on a static measurement of the pressure and the temperature of pure water in a closed, temperature-controlled thermostat, conceived like a quasi-adiabatic calorimeter. A copper cell containing pure water is placed inside a temperature-controlled copper shield, which is mounted in a vacuum-tight stainless steel vessel immersed in a thermostated bath. The temperature of the cell is measured with capsule-type standard platinum resistance thermometers, calibrated with uncertainties below the millikelvin. The vapor pressure is measured by calibrated pressure sensors connected to the cell through a pressure tube whose temperature is monitored at several points. The pressure gauges are installed in a thermostatic apparatus ensuring high stability of the pressure measurement and avoiding any condensation in the tubes. Thanks to the employment of several technical solutions, the thermal contribution to the overall uncertainty budget is reduced, and the remaining major part is mainly due to pressure measurements. This paper presents a full description of this facility and the preliminary results obtained for its characterization. PMID:22852731

  8. Apparatus of the Vapor-pressure Measurements for Natural Refrigerants

    NASA Astrophysics Data System (ADS)

    Higuchi, Satoru; Higashi, Yukihiro

    An apparatus for measuring the vapor-pressures was newly designed and constructed in order to make the basic thermodynamic properties for environmentally acceptable refrigerants clear. The temperature of sample fluid was measured with 100? platinum resistance thermometer calibrated against ITS-90 using a 25? standard platinum resistance thermometer. With respect to the pressure measurement, two kinds of presure transducer were adopted. One is a diaphragm semi-conductor strain pressure transducer with the uncertainty of ±0.09%. This pressure transducer was calibrated against quartz crystal pressure transducer with the uncertainty of ±0.01% after every series of experiments. Another is a quartz crystal pressure transducer with the uncertainty of ±0.01%. A quartz crystal pressure transducer was calibrated against the dead weight pressure gauge and barometer. The vapor-pressures for R-32, R-134a, R-290 (propane), R-600a (iso-butane) and n-pentane were measured in the temperature range between273.15 and 323.15K. As the results of vapor-pressure measurements, the reliability of the experimental apparatus as well as the reproducibility of the experimental data were confirmed. In addition, coefficients of Antoine vapor pressure equation were determined from the experimental data. Normal boiling points for environmentally acceptable refrigerants were also determined with high accuracy.

  9. The Effect of Films on the Capillary Pressure - Saturation Relationship

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Pyrak-Nolte, L. J.; Nolte, D. D.; Giordano, N. J.

    2009-12-01

    The hysteretic dependence of capillary pressure (Pc) on saturation (S) indicates that additional state variables are needed to describe multiphase flow behavior in porous media. Previous studies have shown that the observed hysteresis is a projection of a higher-dimensional surface that depends on interfacial area per volume, as an additional state variable. However, these studies have not addressed the affected of films on the Pc-S relationship. In this study, we use laser scanning confocal microscopy to image the three-dimensional (3D) fluid distributions of two immiscible fluids in a simple wedge-shaped channel. We find that entrained films of wetting phase affect the P-S relationship during both drainage and imbibition and that these extensions of the fluid-fluid interface increase the interaction among the wetting, non-wetting, and solid phases.
    Smooth-walled and rough-walled wedge-shaped channels were fabricated using two different approaches: 1) two-photon polymerization by femtosecond laser and 2) broadband photolithography. Both techniques use UV-sensitive photoresist (SU-8) to construct an all-SU-8 micromodel containing a wedge-shaped channel that is 100 ?m wide at the outlet and 20 ?m wide at the inlet with a constant depth of 40 ?m. A Zeiss LSM 710 Confocal Microscope was used for image the water (wetting phase) and air (non-wetting phase) distributions within the micromodel. By labeling the wetting phase with a fluorophore (Alex Fluor-488 water solution 1%w.t.), the water-air interfaces are clearly visible in the confocal microscopy images. The samples were initially saturated with water. A series of drainage and imbibition cycles were performed by incrementing or decrementing the air pressure. At each pressure, the system was allowed to equilibrate and then a stack of scans in depth was collected to acquire the 3D fluid distribution for a given pressure. The confocal images were analyzed to extract the volume saturation of air and water, the curvature of the three-dimensional fluid-air interface, as well as the interfacial area per volume.
    Hysteretic dependence of the capillary pressure (Pc) on the volume saturation (Sv) was observed even though the wedge-shaped channel has no complex geometry. The Pc - Sv hysteresis with and without films was compared. When films were present, higher capillary pressure was needed to drain the wetting phase. The film provided additional resistance during drainage and additional forces during imbibition.
    Because Sv indicates the wetting phase volume variation, the energy ?E cost to move the interface was calculated from the Pc - Sv graph between pressure steps. The change in surface area ?A between pressure steps was calculated from the saturation Sv. Linear relationships were found between ?E and ?A for drainage and imbibition. The slopes of the ?E - ?A lines with film are higher than that without film, suggesting that the system expends additional energy to move fluid-fluid interfaces when films are present.
    Acknowledgments: This research is supported by the National Science Foundation (0509759-EAR and 0911284-EAR).

  10. 40 CFR 264.1054 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 264.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

  11. 40 CFR 63.165 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 63.165 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure...

  12. 40 CFR 63.165 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 63.165 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure...

  13. 40 CFR 61.242-4 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 false Standards: Pressure relief devices in gas/vapor service...Sources) § 61.242-4 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

  14. 40 CFR 265.1054 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 265.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

  15. 40 CFR 61.242-4 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false Standards: Pressure relief devices in gas/vapor service...Sources) § 61.242-4 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

  16. 40 CFR 61.242-4 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 false Standards: Pressure relief devices in gas/vapor service...Sources) § 61.242-4 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

  17. 40 CFR 61.242-4 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Standards: Pressure relief devices in gas/vapor service...Sources) § 61.242-4 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

  18. 40 CFR 63.165 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 63.165 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure...

  19. 40 CFR 264.1054 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 264.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

  20. 40 CFR 264.1054 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 264.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

  1. 40 CFR 61.242-4 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 false Standards: Pressure relief devices in gas/vapor service...Sources) § 61.242-4 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

  2. 40 CFR 63.165 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 63.165 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure...

  3. 40 CFR 265.1054 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 265.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

  4. 40 CFR 265.1054 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 265.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

  5. 40 CFR 265.1054 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 265.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

  6. 40 CFR 264.1054 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 264.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

  7. 40 CFR 63.165 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 63.165 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure...

  8. 40 CFR 264.1054 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 264.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

  9. 40 CFR 265.1054 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 265.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

  10. Subatmospheric vapor pressures evaluated from internal-energy measurements

    NASA Astrophysics Data System (ADS)

    Duarte-Garza, H. A.; Magee, J. W.

    1997-01-01

    Vapor pressures were evaluated from measured internal-energy changes in the vapor+liquid two-phase region, ? U (2). The method employed a thermodynamic relationship between the derivative quantity (? U (2)/? V) T and the vapor pressure ( p ?) and its temperature derivative (? p/? T)?. This method was applied at temperatures between the triple point and the normal boiling point of three substances: 1,1,1,2-tetrafluoroethane (R134a), pentafluoroethane (R125), and difluoromethane (R32). Agreement with experimentally measured vapor pressures near the normal boiling point (101.325 kPa) was within the experimental uncertainty of approximately ±0.04 kPa (±0.04%). The method was applied to R134a to test the thermodynamic consistency of a published p-p-T equation of state with an equation for p ? for this substance. It was also applied to evaluate published p ? data which are in disagreement by more than their claimed uncertainty.

  11. Evaluation of vapor intrusion using controlled building pressure.

    PubMed

    McHugh, Thomas E; Beckley, Lila; Bailey, Danielle; Gorder, Kyle; Dettenmaier, Erik; Rivera-Duarte, Ignacio; Brock, Samuel; MacGregor, Ian C

    2012-05-01

    The use of measured volatile organic chemical (VOC) concentrations in indoor air to evaluate vapor intrusion is complicated by (i) indoor sources of the same VOCs and (ii) temporal variability in vapor intrusion. This study evaluated the efficacy of utilizing induced negative and positive building pressure conditions during a vapor intrusion investigation program to provide an improved understanding of the potential for vapor intrusion. Pressure control was achieved in five of six buildings where the investigation program was tested. For these five buildings, the induced pressure differences were sufficient to control the flow of soil gas through the building foundation. A comparison of VOC concentrations in indoor air measured during the negative and positive pressure test conditions was sufficient to determine whether vapor intrusion was the primary source of VOCs in indoor air at these buildings. The study results indicate that sampling under controlled building pressure can help minimize ambiguity caused by both indoor sources of VOCs and temporal variability in vapor intrusion. PMID:22486634

  12. Autogenous pressurization of cryogenic vessels using submerged vapor injection

    NASA Technical Reports Server (NTRS)

    Stochl, Robert J.; Vandresar, Neil T.; Lacovic, Raymond F.

    1991-01-01

    Experimental results are reported for submerged injection pressurization and expulsion tests of a 4.89 cu m liquid hydrogen tank. The pressurant injector was positioned near the bottom of the test vessel to simulate liquid engulfment of the pressurant gas inlet; a condition that may occur in low-gravity conditions. Results indicate a substantial reduction in pressurization efficiency, with pressurant gas requirements approximately five times greater than ideal amounts. Consequently, submerged vapor injection should be avoided as a low-gravity autogenous pressurization method whenever possible. The work presented herein validates that pressurent requirements are accurately predicted by a homogeneous thermodynamic model when the submerged injection technique is employed.

  13. Autogenous pressurization of cryogenic vessels using submerged vapor injection

    NASA Technical Reports Server (NTRS)

    Stochl, Robert J.; Van Dresar, Neil T.; Lacovic, Raymond F.

    1991-01-01

    Experimental results are reported for submerged injection pressurization and expulsion tests of a 4.89 cu m liquid hydrogen tank. The pressurant injector was positioned near the bottom of the test vessel to simulate liquid engulfment of the pressurant gas inlet, a condition that may occur in low-gravity conditions. Results indicate a substantial reduction in pressurization efficiency with pressurant gas requirements approximately five times greater than ideal amounts. Consequently, submerged vapor injection should be avoided as a low-gravity autogenous pressurization method whenever possible. The work presented herein validates that pressurant requirements are accurately predicted by a homogeneous thermodynamic model when the submerged injection technique is employed.

  14. Autogenous pressurization of cryogenic vessels using submerged vapor injection

    NASA Astrophysics Data System (ADS)

    Stochl, Robert J.; van Dresar, Neil T.; Lacovic, Raymond F.

    Experimental results are reported for submerged injection pressurization and expulsion tests of a 4.89 cu m liquid hydrogen tank. The pressurant injector was positioned near the bottom of the test vessel to simulate liquid engulfment of the pressurant gas inlet, a condition that may occur in low-gravity conditions. Results indicate a substantial reduction in pressurization efficiency with pressurant gas requirements approximately five times greater than ideal amounts. Consequently, submerged vapor injection should be avoided as a low-gravity autogenous pressurization method whenever possible. The work presented herein validates that pressurant requirements are accurately predicted by a homogeneous thermodynamic model when the submerged injection technique is employed.

  15. Preliminary assessment of condensation behavior for hydrocarbon-vapor expansions which cross the saturation line near the critical point

    SciTech Connect

    Demuth, O.J.

    1983-01-01

    Previous analyses of binary cycles for conversion of geothermal energy from moderate temperature resources to electrical energy have shown potential gains in net geofluid effectiveness on the order of 8%, resulting from selection of turbine-expansion processes whose equilibrium states pass through the two-phase region. If condensation occurs, this gain could be reduced or eliminated by the resulting loss in turbine efficiency. Experience with many fluids, however, indicates that vapor supersaturation permits metastable pure-vapor states to exist at temperatures considerably below the saturation temperature at a given pressure; thus, by better understanding the condensation process, and properly structuring the cycle, substantial performance gains may be possible. The purpose of the present study was to assess the probability for attaining this performance gain by estimating the extent of condensation which might be expected during such an expansion of isobutane vapor. The study indicated that turbine performance should not be degraded significantly for the turbine expansions considered, and that a large fraction of the gain in geofluid effectiveness identified previously is potentially achievable.

  16. Preliminary assessment of condensation behavior for hydrocarbon vapor expansions which cross the saturation line near the critical point

    SciTech Connect

    Demuth, O.J.

    1983-08-01

    Previous analyses of binary cycles for conversion of geothermal energy from moderate temperature resources to electrical energy have shown potential gains in net geofluid effectiveness on the order of 8%, resulting from selection of turbine-expansion processes whose equilibrium states pass through the two-phase region. If condensation occurs, this gain could be reduced or eliminated by the resulting loss in turbine efficiency. Experience with many fluids, however, indicates that vapor supersaturation permits metastable pure-vapor states to exist at temperatures considerably below the saturation temperature at a given pressure; thus, by better understanding the condensation process, and properly structuring the cycle, substantial performance gains may be possible. The purpose of the present study was to assess the probability for attaining this performance gain by estimating the extent of condensation which might be expected during such an expansion of isobutane vapor. The study indicated that turbine performance should not be degraded significantly for the turbine expansions considered, and that a large fraction of the gain in geofluid effectiveness identified previously is potentially achievable.

  17. Piecewise Saturation-Dependent Capillary Pressure and Hydraulic Conductivity Models

    NASA Astrophysics Data System (ADS)

    Ghanbarian-Alavijeh, B.; Hunt, A. G.; Saville, K. C.

    2012-12-01

    Natural porous media typically show fractal behavior in a specific range of pore or particle size. Although mono-fractal models were developed for a single fractal regime, soils may have two or even more, particularly when structural as well as textural pores are considered. Therefore, in this study piecewise saturation-dependent capillary pressure and hydraulic conductivity functions were developed to model porous media showing two fractal regimes. We used the pore-solid fractal (PSF) approach to model the pore-size distribution. Critical path analysis from percolation theory was applied to find the critical radius rc as the smallest pore on an infinite cluster, the critical conductance, and consequently the hydraulic conductivity as a function of saturation. For the purpose of unsaturated hydraulic conductivity prediction from capillary pressure curve using the developed piecewise functions, 8 soil samples from the UNSODA database were selected. We found the same cross-over moisture content for both measured capillary pressure and unsaturated hydraulic conductivity curves. Comparison of the predicted hydraulic conductivity curve with the measured function indicated relatively accurate predictions only for the first regime. Results of fitting the piecewise capillary pressure and hydraulic conductivity functions to the experimental data revealed that both represented the measured curves very well, but as a rule required slightly different values for the fractal dimensionalities in the two properties. We found that the fractal dimension of the first regime of the hydraulic conductivity curve was more accurately estimated from the fractal dimension of the first regime of the capillary pressure curve (with relative error less than 1.2%). For the second regime although the relative error in the fractal dimension estimation from the capillary pressure curve was less than 4%, the discrepancy rendered several orders of magnitude difference between the predicted and measured hydraulic conductivity curve. Since the capillary pressure curve tends to measure the pore bodies, whereas the hydraulic conductivity curve deals with the pore throat radius, this implies slightly different scaling properties for the two "characteristic" radii. Therefore, we argue that 3-D soil images will likely be the more reliable means to predict the hydraulic conductivity and soil water retention curves simultaneously.

  18. Evidence of water vapor in excess of saturation in the atmosphere of Mars.

    PubMed

    Maltagliati, L; Montmessin, F; Fedorova, A; Korablev, O; Forget, F; Bertaux, J-L

    2011-09-30

    The vertical distribution of water vapor is key to the study of Mars' hydrological cycle. To date, it has been explored mainly through global climate models because of a lack of direct measurements. However, these models assume the absence of supersaturation in the atmosphere of Mars. Here, we report observations made using the SPICAM (Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars) instrument onboard Mars Express that provide evidence of the frequent presence of water vapor in excess of saturation, by an amount far surpassing that encountered in Earth's atmosphere. This result contradicts the widespread assumption that atmospheric water on Mars cannot exist in a supersaturated state, directly affecting our long-term representation of water transport, accumulation, escape, and chemistry on a global scale. PMID:21960630

  19. Pressure swing adsorption cycles for improved solvent vapor enrichment

    SciTech Connect

    Liu, Y.; Ritter, J.A.; Kaul, B.K.

    2000-03-01

    A pressure swing adsorption (PSA)-solvent vapor recovery (SVR) process simulator was used to investigate new PSA cycle configurations designed for higher solvent vapor enrichment. These cycles were modifications of the four-step Skarstrom cycle used commercially for PSA-SVR and include the addition of a cocurrent blowdown step, and combinations of cocurrent blowdown and continuous/batch reflux steps. The recovery of gasoline vapor from tank filling operations was simulated with n-butane, n-heptane, and nitrogen as representatives of the light and heavy components in gasoline vapor, and carrier gas, respectively. Adding a cocurrent blowdown step increased the solvent vapor enrichment, depending mainly on the step ending pressure, not the step time. Both the continuous and batch reflux steps also increased the solvent vapor enrichment, but at the expense of an increased bed capacity factor. For similar increases in the solvent vapor enrichment, batch reflux led to significantly smaller bed capacity factors compared to continuous reflux and was thus superior for PSA-SVR. Overall PSA-SVR process performance improved markedly by adding cocurrent blowdown and batch reflux steps compared to the conventional four-step cycle.

  20. Water-vapor pressure control in a volume

    NASA Technical Reports Server (NTRS)

    Scialdone, J. J.

    1978-01-01

    The variation with time of the partial pressure of water in a volume that has openings to the outside environment and includes vapor sources was evaluated as a function of the purging flow and its vapor content. Experimental tests to estimate the diffusion of ambient humidity through openings and to validate calculated results were included. The purging flows required to produce and maintain a certain humidity in shipping containers, storage rooms, and clean rooms can be estimated with the relationship developed here. These purging flows are necessary to prevent the contamination, degradation, and other effects of water vapor on the systems inside these volumes.

  1. Vaporizing high pressure fluids: Energy release comparisons

    SciTech Connect

    Aggarwal, M.C. [Gannon Univ., Erie, PA (United States); Fryer, D.M. [High Pressure Engineering and Safety, Fairview, PA (United States)

    1995-11-01

    This paper utilizes a method previously presented for estimating potential energy which might be released as a shock wave from sudden failure of vessels containing fluids at high pressure supercritical conditions. Data are presented for several fluids and comparisons are made illustrating the relative hazard of these fluids at a typical condition of high pressure and temperature.

  2. Evaporation rate and vapor pressure of selected polymeric lubricating oils.

    NASA Technical Reports Server (NTRS)

    Gardos, M. N.

    1973-01-01

    A recently developed ultrahigh-vacuum quartz spring mass sorption microbalance has been utilized to measure the evaporation rates of several low-volatility polymeric lubricating oils at various temperatures. The evaporation rates are used to calculate the vapor pressures by the Langmuir equation. A method is presented to accurately estimate extended temperature range evaporation rate and vapor pressure data for polymeric oils, incorporating appropriate corrections for the increases in molecular weight and the change in volatility of the progressively evaporating polymer fractions. The logarithms of the calculated data appear to follow linear relationships within the test temperature ranges, when plotted versus 1000/T. These functions and the observed effusion characteristics of the fluids on progressive volatilization are useful in estimating evaporation rate and vapor pressure changes on evaporative depletion.

  3. 40 CFR 65.111 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 2010-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 65.111 Standards: Pressure relief devices in gas/vapor service...Compliance standard. Except during pressure releases as provided for in...

  4. 40 CFR 65.111 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 2012-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 65.111 Standards: Pressure relief devices in gas/vapor service...Compliance standard. Except during pressure releases as provided for in...

  5. 40 CFR 65.111 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 2011-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 65.111 Standards: Pressure relief devices in gas/vapor service...Compliance standard. Except during pressure releases as provided for in...

  6. 40 CFR 65.111 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 2013-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 65.111 Standards: Pressure relief devices in gas/vapor service...Compliance standard. Except during pressure releases as provided for in...

  7. 40 CFR 65.111 - Standards: Pressure relief devices in gas/vapor service.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 2014-07-01 false Standards: Pressure relief devices in gas/vapor service...Equipment Leaks § 65.111 Standards: Pressure relief devices in gas/vapor service...Compliance standard. Except during pressure releases as provided for in...

  8. Subcooled and saturated water flow boiling pressure drop in small diameter helical coils at low pressure

    SciTech Connect

    Cioncolini, Andrea; Santini, Lorenzo; Ricotti, Marco E. [Department of Nuclear Engineering, Politecnico di Milano, via Ponzio 34/3, 20133 Milano (Italy)

    2008-05-15

    Experimental pressure drop results on boiling water flow through three helical coils of tube inner diameter of 4.03 mm and 4.98 mm and coil diameter to tube diameter ratio of 26.1, 64.1 and 93.3 are presented. Both subcooled and saturated flow boiling are investigated, covering operating pressures from 120 to 660 kPa, mass fluxes from 290 to 690 kg m{sup -2} s{sup -1} and heat fluxes from 50 to 440 kW m{sup -2}. Existing correlations for subcooled flow pressure drop are found not capable to fit the present subcooled database, while the measurements in saturated flow conditions are successfully reproduced by existing correlations for both straight and coiled pipe two-phase flow. The experimental database is included in tabular form. (author)

  9. Distillation device supplies cesium vapor at constant pressure

    NASA Technical Reports Server (NTRS)

    Basiulis, A.; Shefsiek, P. K.

    1968-01-01

    Distillation apparatus in the form of a U tube supplies small amounts of pure cesium vapor at constant pressure to a thermionic converter. The upstream leg of the U tube is connected to a vacuum pump to withdraw noncondensable impurities, the bottom portion serves as a reservoir for the liquid cesium.

  10. 46 CFR 154.419 - Design vapor pressure.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Integral Tanks § 154.419 Design vapor pressure. The Po of an integral tank must not exceed 24.5 kPa gauge (3...unless special approval by the Commandant (CG-ENG) allows a Po between 24.5 kPa gauge (3.55 psig) and 69 kPa...

  11. 46 CFR 154.436 - Design vapor pressure.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...Semi-Membrane Tanks § 154.436 Design vapor pressure. The Po of a semi-membrane tank must not exceed 24.5 kPa gauge...unless special approval by the Commandant (CG-ENG) allows a Po between 24.5 kPa gauge (3.55 psig) and 69 kPa...

  12. 46 CFR 154.419 - Design vapor pressure.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Integral Tanks § 154.419 Design vapor pressure. The Po of an integral tank must not exceed 24.5 kPa gauge (3...unless special approval by the Commandant (CG-522) allows a Po between 24.5 kPa gauge (3.55 psig) and 69 kPa...

  13. 46 CFR 154.436 - Design vapor pressure.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...Semi-Membrane Tanks § 154.436 Design vapor pressure. The Po of a semi-membrane tank must not exceed 24.5 kPa gauge...unless special approval by the Commandant (CG-ENG) allows a Po between 24.5 kPa gauge (3.55 psig) and 69 kPa...

  14. 46 CFR 154.419 - Design vapor pressure.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Integral Tanks § 154.419 Design vapor pressure. The Po of an integral tank must not exceed 24.5 kPa gauge (3...unless special approval by the Commandant (CG-522) allows a Po between 24.5 kPa gauge (3.55 psig) and 69 kPa...

  15. 46 CFR 154.436 - Design vapor pressure.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Semi-Membrane Tanks § 154.436 Design vapor pressure. The Po of a semi-membrane tank must not exceed 24.5 kPa gauge...unless special approval by the Commandant (CG-522) allows a Po between 24.5 kPa gauge (3.55 psig) and 69 kPa...

  16. 46 CFR 154.436 - Design vapor pressure.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Semi-Membrane Tanks § 154.436 Design vapor pressure. The Po of a semi-membrane tank must not exceed 24.5 kPa gauge...unless special approval by the Commandant (CG-522) allows a Po between 24.5 kPa gauge (3.55 psig) and 69 kPa...

  17. 46 CFR 154.426 - Design vapor pressure.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Membrane Tanks § 154.426 Design vapor pressure. The Po of a membrane tank must not exceed 24.5 kPa gauge (3...unless special approval by the Commandant (CG-ENG) allows a Po between 24.5 kPa gauge (3.55 psig) and 69 kPa...

  18. 46 CFR 154.426 - Design vapor pressure.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Membrane Tanks § 154.426 Design vapor pressure. The Po of a membrane tank must not exceed 24.5 kPa gauge (3...unless special approval by the Commandant (CG-ENG) allows a Po between 24.5 kPa gauge (3.55 psig) and 69 kPa...

  19. 46 CFR 154.426 - Design vapor pressure.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Membrane Tanks § 154.426 Design vapor pressure. The Po of a membrane tank must not exceed 24.5 kPa gauge (3...unless special approval by the Commandant (CG-522) allows a Po between 24.5 kPa gauge (3.55 psig) and 69 kPa...

  20. 46 CFR 154.426 - Design vapor pressure.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Membrane Tanks § 154.426 Design vapor pressure. The Po of a membrane tank must not exceed 24.5 kPa gauge (3...unless special approval by the Commandant (CG-ENG) allows a Po between 24.5 kPa gauge (3.55 psig) and 69 kPa...

  1. 46 CFR 154.436 - Design vapor pressure.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...Semi-Membrane Tanks § 154.436 Design vapor pressure. The Po of a semi-membrane tank must not exceed 24.5 kPa gauge...unless special approval by the Commandant (CG-ENG) allows a Po between 24.5 kPa gauge (3.55 psig) and 69 kPa...

  2. 46 CFR 154.419 - Design vapor pressure.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Integral Tanks § 154.419 Design vapor pressure. The Po of an integral tank must not exceed 24.5 kPa gauge (3...unless special approval by the Commandant (CG-ENG) allows a Po between 24.5 kPa gauge (3.55 psig) and 69 kPa...

  3. 46 CFR 154.426 - Design vapor pressure.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Membrane Tanks § 154.426 Design vapor pressure. The Po of a membrane tank must not exceed 24.5 kPa gauge (3...unless special approval by the Commandant (CG-522) allows a Po between 24.5 kPa gauge (3.55 psig) and 69 kPa...

  4. 46 CFR 154.419 - Design vapor pressure.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Integral Tanks § 154.419 Design vapor pressure. The Po of an integral tank must not exceed 24.5 kPa gauge (3...unless special approval by the Commandant (CG-ENG) allows a Po between 24.5 kPa gauge (3.55 psig) and 69 kPa...

  5. Vapor pressures and gas-film coefficients for ketones

    USGS Publications Warehouse

    Rathbun, R.E.; Tai, D.Y.

    1987-01-01

    Comparison of handbook vapor pressures for seven ketones with more recent literature data showed large differences for four of the ketones. Gas-film coefficients for the volatilization of these ketones from water determined by two different methods were in reasonable agreement. ?? 1987.

  6. Vapor pressure of perfluoroalkylalkanes: the role of the dipole.

    PubMed

    Morgado, Pedro; Das, Gaurav; McCabe, Clare; Filipe, Eduardo J M

    2015-01-29

    The vapor pressure of four liquid perfluoroalkylalkanes (CF3(CF2)n(CH2)mCH3; n = 3, m = 4,5,7; n = 5, m = 5) was measured as a function of temperature between 278 and 328 K. Molar enthalpies of vaporization were calculated from the experimental data, and the results were compared with data from the literature for the corresponding alkanes and perfluoroalkanes. The heterosegmented statistical associating fluid theory was used to interpret the results at the molecular level both with and without the explicit inclusion of the dipolar nature of the molecules. Additionally, ab initio calculations were performed for all perfluoroalkylalkanes studied to determine the dipole moment to be used in the theoretical calculations. We demonstrate that the inclusion of a dipolar term is essential for describing the vapor-liquid equilibria of perfluoroalkylalkanes. It is also shown that vapor-liquid equilibria in these compounds result from a subtle balance between dipolar interactions, which decrease the vapor pressure, and the relatively weak dispersive interactions between the hydrogenated and fluorinated segments. PMID:25526174

  7. Subatmospheric vapor pressures evaluated from internal-energy measurements

    SciTech Connect

    Duarte-Garza, H.A. [National Inst. of Standards and Technology, Boulder, CO (United States)]|[Texas A and M Univ., Kingsville, TX (United States); Magee, J.W. [National Inst. of Standards and Technology, Boulder, CO (United States)

    1997-01-01

    Vapor pressures were calculated from measured internal-energy changes in the vapor + liquid two-phase region, {Delta}U{sup (2)}. The method employed a thermodynamic relationship between the derivative quantity ({partial_derivative}U{sup (2)}/{partial_derivative}V){sub T} and the vapor pressure (p{sub {sigma}}) and its temperature derivative ({partial_derivative}p/{partial_derivative}T){sub {sigma}}. This method was applied at temperatures between the triple point and the normal boiling point of three substances: 1,1,1,2-tetrafluoroethane (R134a), pentafluoroethane (R125), and difluoromethane (R32). Agreement with experimentally measured vapor pressures near the normal boiling point (101.325 kPa) was within the experimental uncertainty of approximately {+-}0.04 kPa ({+-}0.04%). The method was applied to R134a to test the thermodynamic consistency of a published p-p-T equation of state with an equation for p{sub {sigma}} for this substance. It was also applied to evaluate published p{sub {sigma}} data which are in disagreement by more than their claimed uncertainty.

  8. Controlling Vapor Pressure In Hanging-Drop Crystallization

    NASA Technical Reports Server (NTRS)

    Carter, Daniel C.; Smith, Robbie

    1988-01-01

    Rate of evaporation adjusted to produce larger crystals. Device helps to control vapor pressure of water and other solvents in vicinity of hanging drop of solution containing dissolved enzyme protein. Well of porous frit (sintered glass) holds solution in proximity to drop of solution containing protein or enzyme. Vapor from solution in frit controls evaporation of solvent from drop to control precipitation of protein or enzyme. With device, rate of nucleation limited to decrease number and increase size (and perhaps quality) of crystals - large crystals of higher quality needed for x-ray diffraction studies of macromolecules.

  9. Estimating Water Saturation at The Geysers Based on Historical Pressure and Temperature Production

    E-print Network

    Stanford University

    SGP-TR-174 Estimating Water Saturation at The Geysers Based on Historical Pressure and Temperature from 503 wells at The Geysers geothermal field were analyzed to estimate in-situ water saturation using developed and used in the saturation calculations. Effects of reinjection of The Geysers were analyzed

  10. Method and apparatus to measure vapor pressure in a flow system

    DOEpatents

    Grossman, Mark W. (Belmont, MA); Biblarz, Oscar (Swampscott, MA)

    1991-01-01

    The present invention is directed to a method for determining, by a condensation method, the vapor pressure of a material with a known vapor pressure versus temperature characteristic, in a flow system particularly in a mercury isotope enrichment process.

  11. A precise measurement method of each component gas pressures in rubidium vapor cell based on atom absorption spectra

    NASA Astrophysics Data System (ADS)

    Feng, Wei; Xiao, Guangzong; Liu, Xiaohu; Wang, Zhiguo; Yang, Kaiyong

    2014-12-01

    A new method and its principle are presented for measuring the each component gas pressures in Rubidium (Rb) by the analysis of absorption spectral profile. The experiment system is set up to obtain Rb absorption spectra. And then each component gas pressures in atom vapor cell is estimated. First, the relationships between transmittance of probe light, atom density and absorption cross section are introduced, and the factors which influence the absorption spectral profile and methods to measure gas pressures are given. Second, the frequency-dependence curves of transmittance and the absorption spectra are obtained through tuning the laser frequency through the Rb D1 transition. Finally, the gas pressures of Rb, N2 and He are achieved, through fitting absorption spectral profile referring to half-width and minimum transmittance value of absorption spectra. The experiment results show that gas pressures in Rb atom vapor cell can be accurately measured by absorption spectrometric methods, which will be helpful for the following study of atom vapor cell. The gas pressures of N2 and He measured by the experiments are well matched with design values. The Rb gas pressure is 30%~50% less than the saturated vapor pressure and the suppression may be due to the adsorption of the cell surfaces coated with octadecyltrichlorosilane (OTS) film.

  12. 40 CFR 63.7944 - How do I determine the maximum HAP vapor pressure of my remediation material?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...I determine the maximum HAP vapor pressure of my remediation material? 63...I determine the maximum HAP vapor pressure of my remediation material? ...determine the maximum HAP vapor pressure of your remediation...

  13. Solar radiation and water vapor pressure to forecast chickenpox epidemics.

    PubMed

    Hervás, D; Hervás-Masip, J; Nicolau, A; Reina, J; Hervás, J A

    2015-03-01

    The clear seasonality of varicella infections in temperate regions suggests the influence of meteorologic conditions. However, there are very few data on this association. The aim of this study was to determine the seasonal pattern of varicella infections on the Mediterranean island of Mallorca (Spain), and its association with meteorologic conditions and schooling. Data on the number of cases of varicella were obtained from the Network of Epidemiologic Surveillance, which is composed of primary care physicians who notify varicella cases on a compulsory basis. From 1995 to 2012, varicella cases were correlated to temperature, humidity, rainfall, water vapor pressure, atmospheric pressure, wind speed, and solar radiation using regression and time-series models. The influence of schooling was also analyzed. A total of 68,379 cases of varicella were notified during the study period. Cases occurred all year round, with a peak incidence in June. Varicella cases increased with the decrease in water vapor pressure and/or the increase of solar radiation, 3 and 4 weeks prior to reporting, respectively. An inverse association was also observed between varicella cases and school holidays. Using these variables, the best fitting autoregressive moving average with exogenous variables (ARMAX) model could predict 95 % of varicella cases. In conclusion, varicella in our region had a clear seasonality, which was mainly determined by solar radiation and water vapor pressure. PMID:25265908

  14. Pore-scale modeling of transient and steady-state vapor diffusion in partially-saturated porous media

    SciTech Connect

    Webb, S.W.

    1998-05-01

    Vapor diffusion in porous media in the presence of its own liquid may be enhanced due to pore-scale processes, such as condensation and evaporation across isolated liquid islands. Webb and Ho (1997) developed a mechanistic pore-scale model of these processes under steady-state conditions in which condensation and evaporation on the liquid island were equal. The vapor diffusion rate was significantly enhanced by these liquid island processes by up to an order of magnitude compared to a dry porous media. However, vapor transport by diffusion is often complicated by transient effects, such as in drying applications, in which net evaporation of liquid may further augment the vapor flux from diffusion. The influence of transient effects on the enhancement factors for vapor diffusion is evaluated in this paper. In addition, the effect of vapor pressure lowering on the enhancement factor and on porescale vapor fluxes is shown.

  15. Vapor pressure and vapor fractionation of silicate melts of tektite composition

    USGS Publications Warehouse

    Walter, L.S.; Carron, M.K.

    1964-01-01

    The total vapor pressure of Philippine tektite melts of approximately 70 per cent silica has been determined at temperatures ranging from 1500 to 2100??C. This pressure is 190 ?? 40 mm Hg at 1500??C, 450 ?? 50 mm at 1800??C and 850 ?? 70 mm at 2100?? C. Determinations were made by visually observing the temperature at which bubbles began to form at a constant low ambient pressure. By varying the ambient pressure, a boiling point curve was constructed. This curve differs from the equilibrium vapor pressure curve due to surface tension effects. This difference was evaluated by determining the equilibrium bubble size in the melt and calculating the pressure due to surface tension, assuming the latter to be 380 dyn/cm. The relative volatility from tektite melts of the oxides of Na, K, Fe, Al and Si has been determined as a function of temperature, total pressure arid roughly, of oxygen fugacity. The volatility of SiO2 is decreased and that of Na2O and K2O is increased in an oxygen-poor environment. Preliminary results indicate that volatilization at 2100??C under atmospheric pressure caused little or no change in the percentage Na2O and K2O. The ratio Fe3 Fe2 of the tektite is increased in ambient air at a pressure of 9 ?? 10-4 mm Hg (= 106.5 atm O2, partial pressure) at 2000??C. This suggests that tektites were formed either at lower oxygen pressures or that they are a product of incomplete oxidation of parent material with a still lower ferricferrous ratio. ?? 1964.

  16. 46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405 Section 154...Systems § 154.405 Design vapor pressure (Po ) of a cargo tank. (a) The design vapor pressure (Po ) of a cargo tank must be equal to or...

  17. 46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405 Section 154...Systems § 154.405 Design vapor pressure (Po ) of a cargo tank. (a) The design vapor pressure (Po ) of a cargo tank must be equal to or...

  18. 46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405 Section 154...Systems § 154.405 Design vapor pressure (Po ) of a cargo tank. (a) The design vapor pressure (Po ) of a cargo tank must be equal to or...

  19. 46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405 Section 154...Systems § 154.405 Design vapor pressure (Po ) of a cargo tank. (a) The design vapor pressure (Po ) of a cargo tank must be equal to or...

  20. 46 CFR 154.405 - Design vapor pressure (Po) of a cargo tank.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 false Design vapor pressure (Po) of a cargo tank. 154.405 Section 154...Systems § 154.405 Design vapor pressure (Po ) of a cargo tank. (a) The design vapor pressure (Po ) of a cargo tank must be equal to or...

  1. Optimal determination of the vapor pressure critical exponent

    E-print Network

    Walton, Clifford Wayne

    1977-01-01

    depending on the compound, method and equation analyzed, though there was a tendency toward a value of 0. 20. The compounds analyzed included carbon dioxide, ethane, ethylene, helium-4, methane, oxygen, and water. iv ACKNONLEDGMFNTS The author would... Derivative Method (NDM) Weighting Fa. ctor. Vapor Pressure Data Selection j 3 RESULTS AND DISCUSSION Carbon Dioxide. Ethane. Ethylene. Helium. Methane Oxygen. Water SUMMARY. NOTATION LITERATURE CITED APPEN DICKS APPENDIX A: RESULTS OF LINEAR...

  2. Chemical Vapor Deposition at High Pressure in a Microgravity Environment

    NASA Technical Reports Server (NTRS)

    McCall, Sonya; Bachmann, Klaus; LeSure, Stacie; Sukidi, Nkadi; Wang, Fuchao

    1999-01-01

    In this paper we present an evaluation of critical requirements of organometallic chemical vapor deposition (OMCVD) at elevated pressure for a channel flow reactor in a microgravity environment. The objective of using high pressure is to maintain single-phase surface composition for materials that have high thermal decomposition pressure at their optimum growth temperature. Access to microgravity is needed to maintain conditions of laminar flow, which is essential for process analysis. Based on ground based observations we present an optimized reactor design for OMCVD at high pressure and reduced gravity. Also, we discuss non-intrusive real-time optical monitoring of flow dynamics coupled to homogeneous gas phase reactions, transport and surface processes. While suborbital flights may suffice for studies of initial stages of heteroepitaxy experiments in space are essential for a complete evaluation of steady-state growth.

  3. Vapor pressures and heats of vaporization of primary coal tars. Quarterly technical progress report, July 1 - September 31, 1996

    SciTech Connect

    Suuberg, E.M.; Oja, V.; Lilly, W.D. [Brown Univ., Providence, RI (United States)

    1996-12-31

    The vapor pressure correlations that exist at present for coal tars are very crude and they are not considered reliable to even an order of magnitude. This project seeks to address this important gap in the near term by direct measurement of vapor pressures of coal tar fractions, by application of well-established techniques and modifications thereof. The principal objectives of the program are to: (1) obtain data on the vapor pressures and heats of vaporization of tars from a range of ranks of coal; (2) develop correlations based on a minimum set of conveniently measurable characteristics of the tars; and (3) develop equipment that would allow performing such measurements in a reliable, straightforward fashion. During this quarter we have extended the work on measurements of vapor pressures of coal tars, using the continuous Knudsen effusion technique. These results need further analysis and therefore in this report we describe only the general idea behind the technique, and also show some typical results.

  4. Acoustic and mechanical response of reservoir rocks under variable saturation and effective pressure.

    PubMed

    Ravazzoli, C L; Santos, J E; Carcione, J M

    2003-04-01

    We investigate the acoustic and mechanical properties of a reservoir sandstone saturated by two immiscible hydrocarbon fluids, under different saturations and pressure conditions. The modeling of static and dynamic deformation processes in porous rocks saturated by immiscible fluids depends on many parameters such as, for instance, porosity, permeability, pore fluid, fluid saturation, fluid pressures, capillary pressure, and effective stress. We use a formulation based on an extension of Biot's theory, which allows us to compute the coefficients of the stress-strain relations and the equations of motion in terms of the properties of the single phases at the in situ conditions. The dry-rock moduli are obtained from laboratory measurements for variable confining pressures. We obtain the bulk compressibilities, the effective pressure, and the ultrasonic phase velocities and quality factors for different saturations and pore-fluid pressures ranging from normal to abnormally high values. The objective is to relate the seismic and ultrasonic velocity and attenuation to the microstructural properties and pressure conditions of the reservoir. The problem has an application in the field of seismic exploration for predicting pore-fluid pressures and saturation regimes. PMID:12703693

  5. A modeling approach to represent hysteresis in capillary pressure-saturation relationship based on fluid connectivity in void space

    E-print Network

    Zhou, Quanlin

    A modeling approach to represent hysteresis in capillary pressure- saturation relationship based presents a new model for description of hysteretic constitutive relationships between capillary pressure and saturation under capillary-dominated multiphase flow conditions in porous media. Hysteretic relationships

  6. Laboratory measurements of the microwave opacity and vapor pressure of sulfuric acid vapor under simulated conditions for the middle atmosphere of Venus

    NASA Technical Reports Server (NTRS)

    Steffes, P. G.

    1985-01-01

    Microwave absorption measurements at wavelengths of 13.4 and 3.6 cm were made in gaseous H2SO4 in a CO2 atmosphere under simulated conditions for the Venus middle atmosphere. The results suggest that abundances of gaseous H2SO4 on the order of 15-30 ppm could account for the absorption observed by radio occultation measurements at these wavelengths. They also imply that such abundances would correspond to saturation vapor pressure existing at or above the 46-48-km range, which correlates with the observed cloud base.

  7. Effect of pressure on the electrical resistivity of water-saturated crystalline rocks

    Microsoft Academic Search

    W. F. Brace; A. S. Orange; T. R. Madden

    1965-01-01

    Electrical r.esistivity of eight igneous rocks and two crystalline limestones was measured at pressures to 10 kb. The rocks were saturated with tap water or salt solution, and the pore pressure was maintained near zero. The dependence of resistivity on temperature, porosity, and pore fluid salinity suggested that conduction was primarily electrolytic through- out the .entire pressure range, even though

  8. A qualitative analysis of the dynamics of a sheared and pressurized layer of saturated soil

    E-print Network

    Paris-Sud XI, Université de

    A qualitative analysis of the dynamics of a sheared and pressurized layer of saturated soil; accepted 13 January 1998 A layer of a saturated binary mixture of soil and water, both of which are true processes along the top and bottom interfaces, as well as deformational creep of the sediment and water

  9. Ignitability of DMSO vapors at elevated temperature and reduced pressure

    SciTech Connect

    Bergman, W; Ural, E A; Weisgerber, W

    1999-03-08

    Ignitability of DMSO vapors have been evaluated at 664 mm Hg pressure. The minimum temperature at which the DMSO vapors that are in equilibrium with liquid DMSO has been determined using two types of strong ignition sources. This temperature is 172 F for chemical igniters, and 178 F for spark ignition. Numerous tests have been conducted using controlled intensity sparks to define the shape of the minimum ignition energy curve as a function of temperature. The ignition energies spanned four orders of magnitude (approximately from 20,000 to 2 mJ) while the DMSO vapor mixture temperature varied from 185 to 207 F. The Sandia Generator was used to simulate worst case electrostatic sparks that can be produced by the human body. Although it was not designed for air discharges, this device had been used by LLNL for 1 mm spark gap and the resultant spark energy had been measured to fall within the range from 3.2 to 8.8 mJ. CRC tests using this device showed that the minimum ignition temperature strongly depends on the spark gap. The minimum ignition temperature was 207 F at 1 mm spark gap, 203 F at 3 mm spark gap, and 197 F at 6 mm spark gap. This strong dependence on the spark gap is believed to be partly due to the changes in the spark energy as the spark gap changes.

  10. New Nickel Vapor Pressure Measurements: Possible Implications for Nebular Condensates

    NASA Technical Reports Server (NTRS)

    Johnson, N. M.; Meibom, A.; Ferguson, F. T.; Nuth, J. A., III

    2004-01-01

    Temperatures high enough to vaporize even refractory solids existed in the midplane of the solar nebula during its earliest evolutionary stages and played an important role in the processing of materials that went into the formation of the inner planets and asteroids. A variety of such high-T materials have been identified in primitive chondritic meteorites. These include chemically zoned FeNi metal grains that are generally believed to have formed directly by gas-solid condensation from a gas of approximately solar composition. These FeNi particles provide important information about the times scales of formation and physical transport mechanisms in the nebula, as well as formation temperature, pressure and gas chemistry. Currently, however, the interpretation of the chemical signatures in these FeNi particles rests on less than perfect information about the condensation sequence of siderophile elements. For example much, if not all, of the thermodynamic data for the vapor pressures of moderately refractory metals , such as Fe, Ni and Co, do not cover the desired temperature range. As a result, quite large extrapolations are needed. These extrapolations can be complex and uncertain due to factors such as oxygen fugacity or the presence of hydrogen gas.

  11. Vapor pressures and vapor compositions in equilibrium with hypostoichiometric uranium-plutonium dioxide at high temperatures

    SciTech Connect

    Green, D.W.; Fink, J.K.; Leibowitz, L.

    1982-01-01

    Vapor pressures and vapor compositions in equilibrium with a hypostoichiometric uranium-plutonium dioxide condensed phase (U/sub 1-y/Pu/sub y/)O/sub 2-x/, as functions of T, x, and y, have been calculated for 0.0 less than or equal to x less than or equal to 0.1, 0.0 less than or equal to y less than or equal to 0.3, and for the temperature range 2500 less than or equal to T less than or equal to 6000 K. The range of compositions and temperatures was limited to the region of interest to reactor safety analysis. Thermodynamic functions for the condensed phase and for each of the gaseous species were combined with an oxygen potential model to obtain partial pressures of O, O/sub 2/, Pu, PuO, PuO/sub 2/, U, UO, UO/sub 2/, and UO/sub 3/ as functions of T, x, and y.

  12. Reappraisal of disparities between osmolality estimates by freezing point depression and vapor pressure deficit methods

    Microsoft Academic Search

    Donald J. Winzor

    2004-01-01

    As a response to recent expression of concern about possible unreliability of vapor pressure deficit measurements (K. Kiyosawa, Biophys. Chem. 104 (2003) 171–188), the results of published studies on the temperature dependence of the osmotic pressure of aqueous polyethylene glycol solutions are shown to account for the observed discrepancies between osmolality estimates obtained by freezing point depression and vapor pressure

  13. 40 CFR 63.1011 - Pressure relief devices in gas and vapor service standards.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Pressure relief devices in gas and vapor service...Leaks-Control Level 1 § 63.1011 Pressure relief devices in gas and vapor service...Compliance standard. Except during pressure releases as provided for in...

  14. 40 CFR 63.1011 - Pressure relief devices in gas and vapor service standards.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 false Pressure relief devices in gas and vapor service...Leaks-Control Level 1 § 63.1011 Pressure relief devices in gas and vapor service...Compliance standard. Except during pressure releases as provided for in...

  15. 46 CFR 39.2013 - High and low vapor pressure protection for tankships-T/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 false High and low vapor pressure protection for tankships-T/ALL...Installation § 39.2013 High and low vapor pressure protection for tankships—T/ALL...collection system must be fitted with a pressure-sensing device, located as...

  16. 40 CFR 63.1011 - Pressure relief devices in gas and vapor service standards.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 2012-07-01 false Pressure relief devices in gas and vapor service...Leaks-Control Level 1 § 63.1011 Pressure relief devices in gas and vapor service...Compliance standard. Except during pressure releases as provided for in...

  17. 40 CFR 63.1030 - Pressure relief devices in gas and vapor service standards.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 2012-07-01 false Pressure relief devices in gas and vapor service...Leaks-Control Level 2 Standards § 63.1030 Pressure relief devices in gas and vapor service...Compliance standard. Except during pressure releases as provided for in...

  18. 40 CFR 63.1030 - Pressure relief devices in gas and vapor service standards.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Pressure relief devices in gas and vapor service...Leaks-Control Level 2 Standards § 63.1030 Pressure relief devices in gas and vapor service...Compliance standard. Except during pressure releases as provided for in...

  19. 40 CFR 63.1030 - Pressure relief devices in gas and vapor service standards.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 2014-07-01 false Pressure relief devices in gas and vapor service...Leaks-Control Level 2 Standards § 63.1030 Pressure relief devices in gas and vapor service...Compliance standard. Except during pressure releases as provided for in...

  20. 40 CFR 63.1011 - Pressure relief devices in gas and vapor service standards.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 2014-07-01 false Pressure relief devices in gas and vapor service...Leaks-Control Level 1 § 63.1011 Pressure relief devices in gas and vapor service...Compliance standard. Except during pressure releases as provided for in...

  1. 40 CFR 63.1030 - Pressure relief devices in gas and vapor service standards.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 false Pressure relief devices in gas and vapor service...Leaks-Control Level 2 Standards § 63.1030 Pressure relief devices in gas and vapor service...Compliance standard. Except during pressure releases as provided for in...

  2. 46 CFR 39.2013 - High and low vapor pressure protection for tankships-T/ALL.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false High and low vapor pressure protection for tankships-T/ALL...Installation § 39.2013 High and low vapor pressure protection for tankships—T/ALL...collection system must be fitted with a pressure-sensing device, located as...

  3. 40 CFR 63.1030 - Pressure relief devices in gas and vapor service standards.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 2013-07-01 false Pressure relief devices in gas and vapor service...Leaks-Control Level 2 Standards § 63.1030 Pressure relief devices in gas and vapor service...Compliance standard. Except during pressure releases as provided for in...

  4. 40 CFR 63.1011 - Pressure relief devices in gas and vapor service standards.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 2013-07-01 false Pressure relief devices in gas and vapor service...Leaks-Control Level 1 § 63.1011 Pressure relief devices in gas and vapor service...Compliance standard. Except during pressure releases as provided for in...

  5. Atmospheric pressure laser-induced acoustic desorption chemical ionization mass spectrometry for analysis of saturated hydrocarbons.

    PubMed

    Nyadong, Leonard; Quinn, John P; Hsu, Chang S; Hendrickson, Christopher L; Rodgers, Ryan P; Marshall, Alan G

    2012-08-21

    We present atmospheric pressure laser-induced acoustic desorption chemical ionization (AP/LIAD-CI) with O(2) carrier/reagent gas as a powerful new approach for the analysis of saturated hydrocarbon mixtures. Nonthermal sample vaporization with subsequent chemical ionization generates abundant ion signals for straight-chain, branched, and cycloalkanes with minimal or no fragmentation. [M - H](+) is the dominant species for straight-chain and branched alkanes. For cycloalkanes, M(+•) species dominate the mass spectrum at lower capillary temperature (<100 °C) and [M - H](+) at higher temperature (>200 °C). The mass spectrum for a straight-chain alkane mixture (C(21)-C(40)) shows comparable ionization efficiency for all components. AP/LIAD-CI produces molecular weight distributions similar to those for gel permeation chromatography for polyethylene polymers, Polywax 500 and Polywax 655. Coupling of the technique to Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) for the analysis of complex hydrocarbon mixtures provides unparalleled mass resolution and accuracy to facilitate unambiguous elemental composition assignments, e.g., 1754 peaks (rms error = 175 ppb) corresponding to a paraffin series (C(12)-C(49), double-bond equivalents, DBE = 0) and higher DBE series corresponding to cycloparaffins containing one to eight rings. Isoabundance-contoured plots of DBE versus carbon number highlight steranes (DBE = 4) of carbon number C(27)-C(30) and hopanes of C(29)-C(35) (DBE = 5), with sterane-to-hopane ratio in good agreement with field ionization (FI) mass spectrometry analysis, but performed at atmospheric pressure. The overall speciation of nonpolar, aliphatic hydrocarbon base oil species offers a promising diagnostic probe to characterize crude oil and its products. PMID:22881221

  6. The Vapor Pressures and Derived Thermal Properties of Hydrogen and Deuterium

    Microsoft Academic Search

    R. B. Scott; F. G. Brickwedde; Harold C. Urey; M. H. Wahl

    1934-01-01

    (1) The vapor pressure equations of liquid and solid, normal deuterium were determined by comparison of the vapor pressure of deuterium with that of liquid, normal hydrogen between 13.9° and 20.40°K. The triple and boiling points of deuterium were found to be 18.58° and 23.5°K, respectively. (2) The changes with time in the vapor pressures of liquid hydrogen and liquid

  7. The influence of confining pressure and water saturation on dynamic elastic properties of some Permian coals

    SciTech Connect

    Gang Yu; Vozoff, K. (Macquarie Univ., New South Wales (Australia). Centre for Geophysical Exploration Research); Durney, D.W. (Macquarie Univ., New South Wales (Australia). School of Earth Sciences)

    1993-08-01

    Laboratory measurements are described on Permian coals from Wollongong, New South Wales, Australia related to the dependence of ultrasonic P- and S-wave velocities, attenuation, anisotropy and the dynamic elastic moduli on confining pressure, water saturation, and pore pressure. Five independent stiffness constants are used to represent the elastic anisotropy of the specimens as a function of confining pressure and water saturation. The anisotropy is believed to be controlled mainly by the internal structure of the coals, while the pressure dependence of the constants is controlled mainly by randomly oriented cracks. P-wave and S-wave dispersions were measured on water-saturated specimens as confining pressures increased from 2 MPa to 40 MPa. The samples represented cores taken both parallel and perpendicular to bedding planes. Velocities along bedding planes are marginally higher than those across bedding planes. This anisotropy is insensitive to confining pressure. Attenuation was also measured, both normal and parallel to bedding planes, on dry and water-saturated specimens from 2 MPa to 40 MPa confining pressures. The experimental results show that dynamic elastic properties are potential indicators of the states of stress and saturation in coal seams, and provide necessary information for computer modeling and interpreting seismic surveys carried out to assist mine development.

  8. Bubble-point pressures and saturated- and compressed-liquid densities of the binary R-125 + R-143a system

    SciTech Connect

    Fujimine, T.; Sato, H.; Watanabe, K.

    1999-05-01

    Bubble-point pressures and saturated- and compressed-liquid densities of the binary R-125 (pentafluoroethane) + R-143a (1,1,1-trifluoroethane) system have been measured for several compositions at temperatures from 280 to 330 K by means of a magnetic densimeter coupled with a variable-volume cell mounted with a metallic bellows. The experimental uncertainties of the temperature, pressure, density, and composition were estimated to be within {+-}10 mK, {+-}12 kPa, {+-}0.2%, and {+-}0.2 mass %, respectively. The purities of the samples used throughout the measurements are 99.96 area % for R-125 and 99.94 area % for R-143a. Based on these measurements, the thermodynamic behavior of the vapor-liquid equilibria of this binary refrigerant mixture has been represented using the Peng-Robinson equation for the bubble-point pressures, a correlation for the saturated-liquid densities, and an equation of state for the compressed-liquid densities.

  9. Saturating controllers for pressure control with an electrohydraulic servovalve

    Microsoft Academic Search

    Alexander Fink; Tarunraj Singh

    1997-01-01

    Electrohydraulic servovalves are the most commonly used control devices for hydraulic systems. However, electrohydraulic servo systems are difficult to control because they are in essence highly nonlinear. In this study, the pressure control loop including the electrohydraulic servovalve is modeled and the major nonlinearities are pointed out. A nonlinear transformation is presented to convert the system dynamics to a linear

  10. Hypothetical Thermodynamic Properties: Vapor Pressures and Vaporization Enthalpies of the Even n-Alkanes from C40 to C76 at T ) 298.15 K by

    E-print Network

    Chickos, James S.

    -Alkanes from C40 to C76 at T ) 298.15 K by Correlation-Gas Chromatography. Are the Vaporization Enthalpies-alkanes from T ) (298.15 to 540) K. The vapor pressure and vaporization enthalpy results obtained are compared for the measure- ment of vaporization enthalpies of hydrocarbons at T ) 298.15 K, regardless of the physical state

  11. Vapor pressure dependence of spectral width of EIT in Lambda-level cesium molecular system

    E-print Network

    Hui Chen; Hebin Li; Yuri V. Rostovtsev; Mikhail A. Gubin; Vladimir A. Sautenkov; Marlan O. Scully

    2009-02-16

    We have studied electromagnetically induced transparency (EIT) in diatomic cesium molecules in a vapor cell by using tunable diode lasers. We have observed a sub-natural Lambda-resonance in an absorption molecular band at different cesium vapor pressures. The width of the EIT resonance shows a linear dependence on cesium vapor pressure. Narrow Lambda-resonances in molecules can be used as frequency references for femtosecond laser frequency combs.

  12. Method and apparatus to measure vapor pressure in a flow system

    DOEpatents

    Grossman, M.W.; Biblarz, O.

    1991-10-15

    The present invention is directed to a method for determining, by a condensation method, the vapor pressure of a material with a known vapor pressure versus temperature characteristic, in a flow system particularly in a mercury isotope enrichment process. 2 figures.

  13. The Observed Relationship Between Water Vapor and Ozone in the Tropical Tropopause Saturation Layer and the Influence of Meridional Transport

    NASA Technical Reports Server (NTRS)

    Selkirk, Henry B.; Schoeberl, M. R.; Olsen, M. A.; Douglass, A. R.

    2011-01-01

    We examine balloonsonde observations of water vapor and ozone from three Ticosonde campaigns over San Jose, Costa Rica [10 N, 84 W] during northern summer and a fourth during northern winter. The data from the summer campaigns show that the uppermost portion of the tropical tropopause layer between 360 and 380 K, which we term the tropopause saturation layer or TSL, is characterized by water vapor mixing ratios from proximately 3 to 15 ppmv and ozone from approximately 50 ppbv to 250 ppbv. In contrast, the atmospheric water vapor tape recorder at 380 K and above displays a more restricted 4-7 ppmv range in water vapor mixing ratio. From this perspective, most of the parcels in the TSL fall into two classes - those that need only additional radiative heating to rise into the tape recorder and those requiring some combination of additional dehydration and mixing with drier air. A substantial fraction of the latter class have ozone mixing ratios greater than 150 ppbv, and with water vapor greater than 7 ppmv this air may well have been transported into the tropics from the middle latitudes in conjunction with high-amplitude equatorial waves. We examine this possibility with both trajectory analysis and transport diagnostics based on HIRDLS ozone data. We apply the same approach to study the winter season. Here a very different regime obtains as the ozone-water vapor scatter diagram of the sonde data shows the stratosphere and troposphere to be clearly demarcated with little evidence of mixing in of middle latitude air parcels.

  14. Velocity-dependent capillary pressure in theory for variably-saturated liquid infiltration into porous media

    NASA Astrophysics Data System (ADS)

    Hilpert, Markus

    2012-03-01

    Standard theory for liquid infiltration into porous media cannot explain saturation overshoot at an infiltration front. Based on a recent generalization of the Green-Ampt approach, a new theory for variably-saturated flow is presented that assumes that capillary pressure does not only depend on liquid content but also on the flow velocity. The Eulerian expression for the nonequilibrium capillary pressure is rotationally invariant and attempts to capture the conjecture that dynamic effects are more pronounced if flow is associated with moving fluid-fluid interfaces which cause a dynamic contact angle. The new theory correctly predicts how overshoot depends on the downstream and upstream liquid contents as well as on grain size. The theory also yields the hydrostatic pressure distribution in the liquid and allows for liquid contents exceeding the saturated liquid content of the main imbibition curve that may occur for overshoot.

  15. Vapor pressure, vapor density, and liquid density for 1,1-dichloro-1-fluoroethane (R-141b)

    SciTech Connect

    Duarte-Garza, H.A.; Hwang, C.A.; Kellerman, S.A.; Miller, R.C.; Hall, K.R.; Holste, J.C.; Marsh, K.N.; Gammon, B.E. [Texas A and M Univ., College Station, TX (United States)] [Texas A and M Univ., College Station, TX (United States)

    1997-05-01

    This paper presents measurements of vapor pressures from 250 K to 450 K, liquid densities from 180 K to 370 K at pressures up to 70 MPa, vapor densities at 400 K at pressures up to 1 MPa, and the critical temperature for 1,1-dichloro-1-fluoroethane (R-141b). The derived second and third virial coefficients at 400 K are {minus}459.5 {times} 10{sup {minus}6} m{sup 3}/mol and 1.93 {times} 10{sup {minus}8} m{sup 6}/mol{sup 2}. Extrapolating the observed vapor pressures to be measured critical temperature (477.5 {+-} 0.4) K provides a critical pressure of (4.194 {+-} 0.002) MPa. Using these values with the law of rectilinear diameters indicates a critical density of (3921 {+-} 6) mol/m{sup 3}. Correlations provide values which agree with the measured values for liquid densities within {+-}0.1% and vapor pressures within {+-}0.05%. All uncertainties reported in the paper are 3{sigma}.

  16. Influence of pore geometry, pressure and partial water saturation to electrical properties of reservoir rock: Measurement and model development

    Microsoft Academic Search

    Hilfan Khairy; Zuhar Zahir Tn. Harith

    2011-01-01

    Pressure and saturation are of two important parameters to be considered to evaluate the electrical properties of reservoir rock. As confining pressure can cause pore space of rock to collapse as well as rock properties to change, it for some reason is necessary to examine the degree of the pressure and saturation changes in affecting the electrical properties in detail.

  17. Cloudiness and its relationship to saturation pressure differences during a developing east coast winter storm

    SciTech Connect

    Alliss, R.J.; Raman, S. [North Carolina State Univ., Raleigh, NC (United States)] [North Carolina State Univ., Raleigh, NC (United States)

    1995-11-01

    Cloudiness derived from surface observations and the Geostationary Operational Environmental Satellite VISSR (Visible-Infrared Spin Scan Radiometer) Atmospheric Sounder (VAS) are compared with thermodynamic properties derived from upper-air soundings over the Gulf Stream locale during a developing winter storm. Cloud-top pressures are derived from VAS using the CO{sub 2} slicing technique and a simple threshold procedure. Cloud-base heights and cloud fractions are obtained from National Weather Service hourly reporting stations. Saturation pressure differences, defined as differences between air parcel pressure and saturation-level pressure (lifted condensation level), are derived from upper-air soundings. Collocated comparisons with VAS and surface observations are also made. Results indicate that cloudiness is observed nearly all of the time during the 6-day period, well above the 8-yr mean. High, middle, and low opaque cloudiness are found approximately equally. Of the high- and midlevel cloudiness observed, a considerable amount is semitransparent to terrestrial radiation. Comparisons of satellite-inferred cloudiness with surface observations indicate that the satellite can complement surface observations of cloud cover, particularly above 700 mb. Surface-observed cloudiness is segregated according to a composite cloud fraction and compared to the mean saturation pressure difference for a 1000-600-mb layer. The analysis suggests that this conserved variable may be a good indicator for estimating cloud fraction. Large negative values of saturation pressure difference correlate highly with clear skies, while those approaching zero correlate with overcast conditions. Scattered and broken cloud fractions are associated with increasing values of the saturation pressure difference. Furthermore, cloud fractions observed in this study are considerably higher than those reported in similar studies and by other cloud fraction formulations. 22 refs., 16 figs., 2 tabs.

  18. A new ozone standard - The vapor pressure of ozone at liquid argon temperatures

    NASA Technical Reports Server (NTRS)

    Mauersberger, K.; Hanson, D.; Morton, J.

    1985-01-01

    The vapor pressure of ozone has been measured at liquid argon temperatures. At the normal boiling point of argon (-185.9 C) an ozone pressure of 0.0405 torr was obtained with an accuracy of + or - 1.5 percent. Increases and decreases in liquid argon temperatures raised and lowered the ozone vapor pressure, respectively. During the vapor pressure measurements the purity of ozone was monitored with a mass spectrometer. The proposed ozone standard will considerably improve the calibration of experiments for atmospheric research, the determination of absorption cross sections and other laboratory ozone studies.

  19. Comparison of average and point capillary pressure-saturation functions determined by steady-state centrifugation

    SciTech Connect

    Cropper, Clark [University of Tennessee, Knoxville (UTK); Perfect, Edmund [ORNL; van den Berg, Dr. Elmer [University of Tennessee, Knoxville (UTK); Mayes, Melanie [ORNL

    2010-01-01

    The capillary pressure-saturation function can be determined from centrifuge drainage experiments. In soil physics, the data resulting from such experiments are usually analyzed by the 'averaging method.' In this approach, average relative saturation, , is expressed as a function of average capillary pressure, <{psi}>, i.e., (<{psi}>). In contrast, the capillary pressure-saturation function at a physical point, i.e., S({psi}), has been extracted from similar experiments in petrophysics using the 'integral method.' The purpose of this study was to introduce the integral method applied to centrifuge experiments to a soil physics audience and to compare S({psi}) and (<{psi}>) functions, as parameterized by the Brooks-Corey and van Genuchten equations, for 18 samples drawn from a range of porous media (i.e., Berea sandstone, glass beads, and Hanford sediments). Steady-state centrifuge experiments were performed on preconsolidated samples with a URC-628 Ultra-Rock Core centrifuge. The angular velocity and outflow data sets were then analyzed using both the averaging and integral methods. The results show that the averaging method smoothes out the drainage process, yielding less steep capillary pressure-saturation functions relative to the corresponding point-based curves. Maximum deviations in saturation between the two methods ranged from 0.08 to 0.28 and generally occurred at low suctions. These discrepancies can lead to inaccurate predictions of other hydraulic properties such as the relative permeability function. Therefore, we strongly recommend use of the integral method instead of the averaging method when determining the capillary pressure-saturation function by steady-state centrifugation. This method can be successfully implemented using either the van Genuchten or Brooks-Corey functions, although the latter provides a more physically precise description of air entry at a physical point.

  20. Effects of Average and Point Capillary Pressure-Saturation Function Parameters on Multiphase Flow Simulations

    NASA Astrophysics Data System (ADS)

    Cheng, C.; Perfect, E.; Cropper, C.

    2011-12-01

    Numerical models are an important tool in petroleum engineering, geoscience, and environmental applications, e.g. feasibility evaluation and prediction for enhanced oil recovery, enhanced geothermal systems, geological carbon storage, and remediation of contaminated sites. Knowledge of capillary pressure-saturation functions is essential in such applications for simulating multiphase fluid flow and chemical transport in variably-saturated rocks and soils in the subsurface. Parameters from average capillary pressure-saturation functions are sometimes employed due to their relative ease of measurement in the laboratory. However, the use of average capillary pressure-saturation function parameters instead of point capillary pressure-saturation function parameters for numerical simulations of flow and transport can result in significant errors, especially in the case of coarse-grained sediments and fractured rocks. Such erroneous predications can impose great risks and challenges to decision-making. In this paper we present a comparison of simulation results based on average and point estimates of van Genuchten model parameters (Sr, ?, and n) for Berea sandstone, packed glass beads, and Hanford sediments. The capillary pressure-saturation functions were measured using steady-state centrifugation. Average and point parameters were estimated for each sample using the averaging and integral methods, respectively. Results indicated that the Sr and ? parameters estimated using averaging and integral methods were close to a 1-to-1 correspondence, with R-squared values of 0.958 and 0.994, respectively. The n parameter, however, showed a major curvilinear deviation from the 1-to-1 line for the two estimation methods. This trend indicates that the averaging method systematically underestimates the n parameter relative to the point-based estimates of the integral method leading to an over predication of the breadth of the pore size distribution. Forward numerical simulations using STOMP will be employed to illustrate the magnitudes of the errors in flow and transport predictions resulting from the use of average instead of point hydraulic parameters.

  1. Arterial blood oxygen saturation during blood pressure cuff-induced hypoperfusion

    NASA Astrophysics Data System (ADS)

    Kyriacou, P. A.; Shafqat, K.; Pal, S. K.

    2007-10-01

    Pulse oximetry has been one of the most significant technological advances in clinical monitoring in the last two decades. Pulse oximetry is a non-invasive photometric technique that provides information about the arterial blood oxygen saturation (SpO2) and heart rate, and has widespread clinical applications. When peripheral perfusion is poor, as in states of hypovolaemia, hypothermia and vasoconstriction, oxygenation readings become unreliable or cease. The problem arises because conventional pulse oximetry sensors must be attached to the most peripheral parts of the body, such as finger, ear or toe, where pulsatile flow is most easily compromised. Pulse oximeters estimate arterial oxygen saturation by shining light at two different wavelengths, red and infrared, through vascular tissue. In this method the ac pulsatile photoplethysmographic (PPG) signal associated with cardiac contraction is assumed to be attributable solely to the arterial blood component. The amplitudes of the red and infrared ac PPG signals are sensitive to changes in arterial oxygen saturation because of differences in the light absorption of oxygenated and deoxygenated haemoglobin at these two wavelengths. From the ratios of these amplitudes, and the corresponding dc photoplethysmographic components, arterial blood oxygen saturation (SpO2) is estimated. Hence, the technique of pulse oximetry relies on the presence of adequate peripheral arterial pulsations, which are detected as photoplethysmographic (PPG) signals. The aim of this study was to investigate the effect of pressure cuff-induced hypoperfusion on photoplethysmographic signals and arterial blood oxygen saturation using a custom made finger blood oxygen saturation PPG/SpO2 sensor and a commercial finger pulse oximeter. Blood oxygen saturation values from the custom oxygen saturation sensor and a commercial finger oxygen saturation sensor were recorded from 14 healthy volunteers at various induced brachial pressures. Both pulse oximeters showed gradual decrease of saturations during induced hypoperfusion which demonstrate the direct relation between blood volumes (PPG amplitudes), arterial vessel stenosis and blood oxygen saturation. The custom made pulse oximeter was found to be more sensitive to SpO2 changes than the commercial pulse oximeter especially at high occluding pressures.

  2. Vapor pressures and heats of vaporization of primary coal tars. Quarterly technical progress report, July 1--September 30, 1995

    SciTech Connect

    Suuberg, E.M.

    1995-12-31

    There is significant current interest in general area of coal pyrolysis, particularly because of the central role of pyrolysis in all thermally driven coal conversion processes-gasification, combustion, liquefaction, mild gasification, or thermal beneficiation. There remain several key data needs in these application areas. Among them is a need for more reliable correlation for prediction of vapor pressure of heavy, primary coal tars. The vapor pressure correlations that exist at present for coal tars are very crude and they are not considered reliable to even an order of magnitude when applied to tars. The present project seeks to address this important gap in the near term by direct measurement of vapor pressures of coal tar fractions, by application of well-established techniques and modifications thereof. The principal objectives of the program are to: (1) obtain data on the vapor pressures and heats of vaporization of tars from a range of ranks of coal, (2) develop correlations based on a minimum set of conveniently measurable characteristics of the tars, (3) develop equipment that would allow performing such measurements in a reliable, straightforward fashion. A significant amount of time has been devoted during this quarter to extending the work on measurements of vapor pressures of tars. For this purpose, cellulose tar and cellulose tar related compounds have been selected as model systems. Cellulose tar has a much narrower distribution of molecular weight than does coal tar, and it is much more homogeneous. Thus it is better to develop the methods to be used for coal tars on this simpler model system first.

  3. H2SO4 vapor pressure of sulfuric acid and ammonium sulfate solutions

    Microsoft Academic Search

    James J. Marti; Anne Jefferson; Xiao Ping Cai; Chad Richert; Peter H. McMurry; Fred Eisele

    1997-01-01

    Few measurements of H2SO4 vapor pressure have been made for sulfuric acid in the temperature and concentration ranges of atmospheric interest because of the very low pressures involved (below 10-4Pa, or 10-6torr); no such measurements appear to have been made for sulfuric acid solutions neutralized with ammonia. This work presents measurements of H2SO4 vapor pressure for aqueous sulfuric acid solutions

  4. Rapid measurements of boiling point and vapor pressure of short-chain triglycerides by thermogravimetric analysis

    Microsoft Academic Search

    J. W. Goodrum

    1997-01-01

    Temperature dependence of vapor pressure and the boiling points for tricaproin (Tcap) and tricaprylin (Tcpy) were measured\\u000a by a new rapid thermogravimetric analysis (TGA) method. Results were in agreement with data from other references. The Clausius\\/Clapeyron\\u000a model fitted Tcap and Tcpy vapor pressure data with errors of 6% or less for pressures ranging from ambient down to 20 mmHg.\\u000a This

  5. The hysteretic evapotranspiration—Vapor pressure deficit relation

    NASA Astrophysics Data System (ADS)

    Zhang, Quan; Manzoni, Stefano; Katul, Gabriel; Porporato, Amilcare; Yang, Dawen

    2014-02-01

    Diurnal hysteresis between evapotranspiration (ET) and vapor pressure deficit (VPD) was reported in many ecosystems, but justification for its onset and magnitude remains incomplete with biotic and abiotic factors invoked as possible explanations. To place these explanations within a holistic framework, the occurrence of hysteresis was theoretically assessed along a hierarchy of model systems where both abiotic and biotic components are sequentially added. Lysimeter evaporation (E) measurements and model calculations using the Penman equation were used to investigate the effect of the time lag between net radiation and VPD on the hysteresis in the absence of any biotic effects. Modulations from biotic effects on the ET-VPD hysteresis were then added using soil-plant-atmosphere models of different complexities applied to a grassland ecosystem. The results suggest that the hysteresis magnitude depends on the radiation-VPD lag, while the plant and soil water potentials are both key factors modulating the hysteretic ET-VPD relation as soil moisture declines. In particular, larger hysteresis magnitude is achieved at less negative leaf water potential, root water potential, and soil water potential. While plant hydraulic capacitance affects the leaf water potential-ET relation, it has negligible effects on the ET-VPD hysteresis. Therefore, the genesis and magnitude of the ET-VPD hysteresis are controlled directly by both abiotic factors such as soil water availability, biotic factors (leaf and root water potentials, which in turn depend on soil moisture), and the time lag between radiation and VPD.

  6. MEASUREMENT AND PREDICTION OF SATURATION-PRESSURE RELATIONSHIPS IN THREE-PHASE POROUS MEDIA SYSTEMS

    EPA Science Inventory

    Scaled multiphase versions of the Brooks-Corey and van Genuchten retention functions were used to describe saturation-capillary pressure curves measured in air-water, air-organic liquid and organic liquid-water systems in a sandy porous medium for four organic liquids during mono...

  7. MODEL FOR HYSTERETIC CONSTITUTIVE RELATIONS GOVERNING MULTIPHASE FLOW. 1. SATURATION-PRESSURE RELATIONS

    EPA Science Inventory

    In these companion papers, a general theoretical model is presented for the description of functional relationships between relative permeability k, fluid saturation S, and pressure P in two- or three-phase (e.g., air-water or air-oil-water) porous media systems subject to arbitr...

  8. Pressure-Saturation Effects from AVO Attributes in CO2 Monitoring of Weyburn Reservoir, Saskatchewan, Canada

    NASA Astrophysics Data System (ADS)

    Gao, L.; Morozov, I. B.

    2011-12-01

    In order to measure pore-pressure and saturation effects due to CO2 injection, amplitude variation with offset (AVO) could be a most valuable discriminator. The AVO technique is applied to monitoring the Weyburn reservoir, located in southeast Saskatchewan, using 3D/3C surface seismic datasets. A baseline (1999) and two monitor surveys (2001 and 2002) acquired by EnCana as part of the International Energy Agency GHG Weyburn-Midale CO2 Monitoring and Storage Project are included in this study. Two-term linear AVO attributes including the intercept (I), gradient (G), S-wave reflectivity (I-G)/2 and I+G are derived. Attribute I - G is shown to be most sensitive to pressure variations, and I + G - to CO2 saturation. In addition, several secondary attributes based on statistical distributions of (I, G) values are also examined. The time-lapse AVO attributes indicate areas of pore-pressure and potentially CO2 saturation variations between the horizontal injection wells. The results indicate that AVO technology allows estimating reservoir pressure and fluid saturation variations from time-lapse seismic data.

  9. Effect of reactor pressure on the electrical and structural properties of InN epilayers grown by high-pressure chemical vapor deposition

    E-print Network

    Nabben, Reinhard

    by high-pressure chemical vapor deposition M. K. Indika Senevirathna, Sampath Gamage, Ramazan Atalay by high-pressure chemical vapor deposition M. K. Indika Senevirathna,a) Sampath Gamage, Ramazan Atalay on GaN/sapphire (0001) templates by high-pressure chemical vapor deposition has been studied

  10. Total sulfur dioxide emissions and pre-eruption vapor-saturated magma at Mount St. Helens, 1980-88

    SciTech Connect

    Gerlach, T.M.; McGee, K.A. [Geological Survey, Vancouver, WA (United States)] [Geological Survey, Vancouver, WA (United States)

    1994-12-15

    SO{sub 2} from explosive volcanism can cause significant climatic and atmospheric impacts, but the source of the sulfur is controversial. TOMS, COSPEC, and ash leachate data for Mount St. Helens from the time of the climactic eruption on 18 May 1980 to the final stages of non-explosive degassing in 1988 give a total SO{sub 2} emission of 2 Mt. COSPEC data show a sharp drop in emission rate that was apparently controlled by a decreasing rate of magma supply. A total SO{sub 2} emission of only 0.08 Mt is estimated from melt inclusion data and the conventional assumption that the main sulfur source was pre-eruption melt; commonly invoked sources of {open_quotes}excess sulfur{close_quotes} (anhydrite decomposition, basaltic magma, and degassing of non-erupted magma) are unlikely in this case. Thus melt inclusions may significantly underestimate SO{sub 2} emissions and impacts of explosive volcanism on climate and the atmosphere. Measured CO{sub 2} emissions, together with the H{sub 2}O content of melt inclusions and experimental solubility data, indicate the Mount St. Helens dacite was vapor-saturated at depth prior to ascent and suggest that a vapor phase was the main source of sulfur for the 2-Mt of SO{sub 2}. A vapor source is consistent with experimental studies on the Mount St. Helens dacite and removes the need for a much debated shallow magma body. 23 refs., 3 figs.

  11. Thermodynamic Properties of Nitrogen Including Liquid and Vapor Phases from 63K to 2000K with Pressures to 10,000 Bar

    NASA Technical Reports Server (NTRS)

    Jacobsen, Richard T.; Stewart, Richard B.

    1973-01-01

    Tables of thermodynamic properties of nitrogen are presented for the liquid and vapor phases for temperatures from the freezing line to 2000K and pressures to 10,000 bar. The tables include values of density, internal energy, enthalpy, entropy, isochoric heat capacity, isobaric heat capacity velocity of sound, the isotherm derivative, and the isochor derivative. The thermodynamic property tables are based on an equation of state, P=P (p,T), which accurately represents liquid and gaseous nitrogen for the range of pressures and temperatures covered by the tables. Comparisons of property values calculated from the equation of state with measured values for P-p-T, heat capacity, enthalpy, latent heat, and velocity of sound are included to illustrate the agreement between the experimental data and the tables of properties presented here. The coefficients of the equation of state were determined by a weighted least squares fit to selected P-p-T data and, simultaneously, to isochoric heat capacity data determined by corresponding states analysis from oxygen data, and to data which define the phase equilibrium criteria for the saturated liquid and the saturated vapor. The vapor pressure equation, melting curve equation, and an equation to represent the ideal gas heat capacity are also presented. Estimates of the accuracy of the equation of state, the vapor pressure equation, and the ideal gas heat capacity equation are given. The equation of state, derivatives of the equation, and the integral functions for calculating derived thermodynamic properties are included.

  12. Evaporation monitoring and composition control of alloy systems with widely differing vapor pressures

    SciTech Connect

    Anklam, T.M.; Berzins, L.V.; Braun, D.G.; Haynam, C.; McClelland, M.A.; Meier, T.

    1994-10-01

    Lawrence Livermore National Laboratory is developing sensors and controls to improve and extend electron beam materials processing technology to alloy systems with constituents of widely varying vapor pressure. The approach under development involves using tunable lasers to measure the density and composition of the vapor plume. A laser based vaporizer control system for vaporization of a uranium-iron alloy has been previously demonstrated in multi-hundred hour, high rate vaporization experiments at LLNL. This paper reviews the design and performance of the uranium vaporization sensor and control system and discusses the extension of the technology to monitoring of uranium vaporization. Data is presented from an experiment in which titanium wire was fed into a molten niobium pool. Laser data is compared to deposited film composition and film cross sections. Finally, the potential for using this technique for composition control in melting applications is discussed.

  13. Temperature and saturation dependence in the vapor sensing of butterfly wing scales.

    PubMed

    Kertész, K; Piszter, G; Jakab, E; Bálint, Zs; Vértesy, Z; Biró, L P

    2014-06-01

    The sensing of gasses/vapors in the ambient air is the focus of attention due to the need to monitor our everyday environment. Photonic crystals are sensing materials of the future because of their strong light-manipulating properties. Natural photonic structures are well-suited materials for testing detection principles because they are significantly cheaper than artificial photonic structures and are available in larger sizes. Additionally, natural photonic structures may provide new ideas for developing novel artificial photonic nanoarchitectures with improved properties. In the present paper, we discuss the effects arising from the sensor temperature and the vapor concentration in air during measurements with a photonic crystal-type optical gas sensor. Our results shed light on the sources of discrepancy between simulated and experimental sensing behaviors of photonic crystal-type structures. Through capillary condensation, the vapors will condensate to a liquid state inside the nanocavities. Due to the temperature and radius of curvature dependence of capillary condensation, the measured signals are affected by the sensor temperature as well as by the presence of a nanocavity size distribution. The sensing materials used are natural photonic nanoarchitectures present in the wing scales of blue butterflies. PMID:24863219

  14. Accurate determination of the vapor pressure of potassium using optical absorption

    NASA Technical Reports Server (NTRS)

    Shirinzadeh, B.; Wang, C. C.

    1983-01-01

    The vapor pressure of potassium has been measured in absorption using a CW tunable laser and calibrated against the accurate radiative lifetime of the 4s-4p doublet of potassium. An accurate value of 20,850 + or - 30 cal/mol for the heat of vaporization (from the liquid phase) at the melting point was determined.

  15. Vaporizing Vapor

    NSDL National Science Digital Library

    2012-08-03

    In this demonstration, relative humidity is modeled using a sponge and a pan of water, and the concept of saturation is depicted. Students answer questions examining the relationship between temperature and the capacity of air to hold water vapor. The resource is part of the teacher's guide accompanying the video, NASA Sci Files: The Case of the Phenomenal Weather. Lesson objectives supported by the video, additional resources, teaching tips and an answer sheet are included in the teacher's guide.

  16. OPTIMAL DESIGN OF A HIGH PRESSURE ORGANOMETALLIC CHEMICAL VAPOR DEPOSITION REACTOR

    E-print Network

    OPTIMAL DESIGN OF A HIGH PRESSURE ORGANOMETALLIC CHEMICAL VAPOR DEPOSITION REACTOR K.J. BACHMANN simulations as a fundamental design tool in developing a new prototype high pressure organometallic chemical and costly experimental design was the central paradigm. 1.1 High Pressure OMCVD A simplified view

  17. Method and system for determining vapor pressure or composition of hydrocarbon liquids

    Microsoft Academic Search

    L. A. Baillie; J. L. Skinner

    1988-01-01

    A method for determining the vapor pressure of a liquid composition of crude oil and natural gas liquids at a given temperature is described comprising the steps of: causing the liquid composition to flow through eductor means while measuring the total pressure of the liquid at a location in the eductor means which comprises the minimum pressure point of fluid

  18. Static method to measure vapor pressure in the temperature range below 1100 K

    NASA Astrophysics Data System (ADS)

    Nishimura, Jiro; Numata, Takashi; Ogasawara, Hiromitsu; Sakanoue, Yoshio

    1985-12-01

    In this paper, a static method of measuring vapor pressure with an optically flat glass-membrane pressure sensor in the temperature range below 1100 K is described. The furnace is designed so that the pressure can be measured contactlessly by the null method. A method of automatic pressure control using this sensor is described as well. The method is capable of controlling the pressure to the order of the sensitivity of the membrane.

  19. Determination of Vapor Pressure-Temperature Relationships of Current Use Pesticides and Transformation Products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sub-cooled liquid vapor pressures of current use organochlorine and organophosphate pesticides (chlorothalonil, chlorpyrifos methyl, diazinon, fipronil) and selected transformation products (chlorpyrifos oxon, heptachlor epoxide, oxychlordane, 3,5,6-trichloro-2-pyridinol) were determined at multiple...

  20. Single- and few-layer graphene by ambient pressure chemical vapor deposition on nickel

    E-print Network

    Reina Ceeco, Alfonso

    2010-01-01

    An ambient pressure chemical vapor deposition (APCVD) process is used to fabricate graphene based films consisting of one to several graphene layers across their area. Polycrystalline Ni thin films are used and the graphene ...

  1. MEASUREMENT OF PARTIAL VAPOR PRESSURE OF AMMONIA OVER ACID AMMONIUM SULFATE SOLUTIONS BY AN INTEGRAL METHOD

    EPA Science Inventory

    We present a simple, integral, passive method for measuring partial vapor pressure. ntegral methods are useful tools when dealing with very low concentrations because collection over extended periods increases the analytical sensitivity. assive methods have the advantage of not i...

  2. Calculation of the Dimer Equilibrium Constant of Heavy Water Saturated Vapor

    E-print Network

    L. A. Bulavin; S. V. Khrapatiy; V. N. Makhlaichuk

    2015-03-13

    Water is the most common substance on Earth.The discovery of heavy water and its further study have shown that the change of hydrogen for deuterium leads to the significant differences in their properties.The triple point temperature of heavy water is higher,at the same time the critical temperature is lower.Experimental values of the second virial coefficient of the EOS for the vapor of normal and heavy water differ at all temperatures.This fact can influence the values of the dimerization constant for the heavy water vapor.The equilibrium properties of the dimerization process are described with the methods of chemical thermodynamics.The chemical potentials for monomers (m) and dimers (d)are the functions of their concentrations.The interactions of monomer-dimer and dimer-dimer types are taken into account within the solution of equation for chemical potentials.The obtained expression for the dimerization constant contains the contributions of these types.The averaged potentials are modeled by the Sutherland potential.Theoretical values of the dimerization constant for the heavy water vapor at different temperatures are compared to those for normal water.We see the exceeding of the values for the heavy water at all temperatures.This fact is in good agreement with all experimental data that is available.The excess is related to the differences in the character of the heat excitations of the dimers of normal and heavy water,their rotational constants and energy of their vibrational excitations.Significant role is also played by the monomer-dimer and dimer-dimer interactions.

  3. Sound Propagation in Saturated Gas-Vapor-Droplet Suspensions Considering the Effect of Transpiration on Droplet Evaporation

    NASA Technical Reports Server (NTRS)

    Kandula, Max

    2012-01-01

    The Sound attenuation and dispersion in saturated gas-vapor-droplet mixtures with evaporation has been investigated theoretically. The theory is based on an extension of the work of Davidson (1975) to accommodate the effects of transpiration on the linear particle relaxation processes of mass, momentum and energy transfer. It is shown that the inclusion of transpiration in the presence of mass transfer improves the agreement between the theory and the experimental data of Cole and Dobbins (1971) for sound attenuation in air-water fogs at low droplet mass concentrations. The results suggest that transpiration has an appreciable effect on both sound absorption and dispersion for both low and high droplet mass concentrations.

  4. Vapor Pressure of the 1,1,1,2-Tetrafluoroethane (R-134a) + Polyalkylene Glycol System

    Microsoft Academic Search

    Y. M. Park; J. O. Kang; J. Yoo; J. W. Lee

    2004-01-01

    Vapor pressures of the 1,1,1,2-tetrafluoroethane + polyalkylene glycol system were obtained at 72 points over the temperature range from 253.15 to 333.15 K at 10 K intervals and the composition range from 0 to 90 mass % polyalkylene glycol. It was found that below 273.15 K, the effect of the polyalkylene glycol on the vapor pressure was negligible up to 30 mass % polyalkylene

  5. Equilibrium vapor pressure and capillary ring formation of adhering spherical aerosol particles

    E-print Network

    Crouzet, Yoan

    1993-01-01

    EQUILIBRIUM VAPOR PRESSURE AND CAPILLARY RING FORMATION OF ADHERING SPHERICAL AEROSOL PARTICLES A Thesis by YOAN CROUZET Submitted to the Office of Graduate Studies of Texas ARM University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE August 1993 Major Subject: Nuclear Engineering EQUILIBRIUM VAPOR PRESSURE AND CAPILLARY RING FORMATION OF ADHERING SPHERICAL AEROSOL PARTICI ES A Thesis by YOAN CROUZET Approved as to style and content by: William H...

  6. Vapour pressures of saturated aqueous solutions of ammonium iodide, potassium iodide, potassium nitrate, strontium chloride, lithium sulphate, sodium thiosulphate, magnesium nitrate, and uranyl nitrate from T =(278 to 323) K

    Microsoft Academic Search

    Alexander Apelblat; Eli Korin

    1998-01-01

    Vapour pressures of saturated aqueous solutions of NH4I, KI, KNO3, SrCl2, Li2SO4, Na2S2O3, Mg(NO3)2, and UO2(NO3)2were determined in the temperature range (278 to 323) K using an electronic hygrometer with an electrolyte sensor, and compared with literature data. Water activities, osmotic coefficients, and molar enthalpies of vaporization and solution at saturation point were evaluated from the determined vapour pressures.

  7. Experimental studies on the enhanced flow boiling heat transfer and pressure drop of organic fluid with high saturation temperature in vertical porous coated tube

    NASA Astrophysics Data System (ADS)

    Yang, Dong; Shen, Zhi; Chen, Tingkuan; Zhou, Chenn Q.

    2013-07-01

    The characteristics of flow boiling heat transfer and pressure drop of organic fluid with high saturation temperature in a vertical porous coated tube are experimentally studied in this paper. The experiments are performed at evaporation pressure of 0.16-0.31MPa, mass flux of 390-790kg/m2s, and vapor quality of 0.06-0.58. The variations of heat transfer coefficient and pressure drop with vapor quality are measured and compared to the results of smooth tube. Boiling curves are generated at mass flux of 482 and 675kg/m2s. The experimental results indicate that the heat transfer coefficients of the porous tube are 1.8-3.5 times those of smooth tube, and that the frictional pressure drops of the porous tube are 1.1-2.9 times those of smooth tube. The correlations for heat transfer coefficient and frictional pressure drop are derived, in which the effect of fluid molecular weight is included. The experiments show that significant heat transfer enhancement is accompanied by a little pressure drop penalty, the application of the porous coated tube is promising in the process industries.

  8. Autogenous pressurization of cryogenic vessels using submerged vapor injection

    Microsoft Academic Search

    Robert J. Stochl; Neil T. van Dresar; Raymond F. Lacovic

    1991-01-01

    Experimental results are reported for submerged injection pressurization and expulsion tests of a 4.89 cu m liquid hydrogen tank. The pressurant injector was positioned near the bottom of the test vessel to simulate liquid engulfment of the pressurant gas inlet, a condition that may occur in low-gravity conditions. Results indicate a substantial reduction in pressurization efficiency with pressurant gas requirements

  9. Calculation of the Dimer Equilibrium Constant of Heavy Water Saturated Vapor

    E-print Network

    Bulavin, L A; Makhlaichuk, V N

    2015-01-01

    Water is the most common substance on Earth.The discovery of heavy water and its further study have shown that the change of hydrogen for deuterium leads to the significant differences in their properties.The triple point temperature of heavy water is higher,at the same time the critical temperature is lower.Experimental values of the second virial coefficient of the EOS for the vapor of normal and heavy water differ at all temperatures.This fact can influence the values of the dimerization constant for the heavy water vapor.The equilibrium properties of the dimerization process are described with the methods of chemical thermodynamics.The chemical potentials for monomers (m) and dimers (d)are the functions of their concentrations.The interactions of monomer-dimer and dimer-dimer types are taken into account within the solution of equation for chemical potentials.The obtained expression for the dimerization constant contains the contributions of these types.The averaged potentials are modeled by the Sutherlan...

  10. Determination of vapor pressures for nonpolar and semipolar organic compounds from gas chromatographic retention data

    USGS Publications Warehouse

    Hinckley, D.A.; Bidleman, T.F.; Foreman, W.T.; Tuschall, J.R.

    1990-01-01

    Vapor pressures for nonpolar and moderately polar organochlorine, pyrethroid, and organophosphate insecticides, phthalate esters, and organophosphate flame retardants were determined by capillary gas chromatography (GC). Organochlorines and polycyclic aromatic hydrocarbons with known liquid-phase vapor pressures (P??L) (standard compounds) were chromatographed along with two reference compounds n-C20 (elcosane) and p,p???-DDT on a 1.0-m-long poly(dimethylsiloxane) bonded-phase (BP-1) column to determine their vapor pressures by GC (P??GC). A plot of log P??L vs log P??GC for standard compounds was made to establish a correlation between measured and literature values, and this correlation was then used to compute P??L of test compounds from their measured P??GC. P??L of seven major components of technical chlordane, endosulfan and its metabolites, ??-hexachlorocyclohexane, mirex, and two components of technical toxaphene were determined by GC. This method provides vapor pressures within a factor of 2 of average literature values for nonpolar compounds, similar to reported interlaboratory precisions of vapor pressure determinations. GC tends to overestimate vapor pressures of moderately polar compounds. ?? 1990 American Chemical Society.

  11. Prediction of arterial partial pressure of oxygen with pulse oxygen saturation measurements

    Microsoft Academic Search

    Julia Brockway; William W. Hay

    1998-01-01

    Objectives: We studied 22 neonates with gestational ages from 26 to 40 weeks to determine how accurately pulse oxygen saturation (SpO2) could predict arterial partial pressure of oxygen (PaO2) and how much time and effort would be required to achieve and maintain a desired SpO2 value.Study design: SpO2 was maintained at 90%, 92%, 94%, 96%, and 98% by adjustment of

  12. Temperature and water vapor pressure effects on the friction coefficient of hydrogenated diamondlike carbon films.

    SciTech Connect

    Dickrell, P. L.; Sawyer, W. G.; Eryilmaz, O. L.; Erdemir, A.; Energy Technology; Univ. of Florida

    2009-07-01

    Microtribological measurements of a hydrogenated diamondlike carbon film in controlled gaseous environments show that water vapor plays a significant role in the friction coefficient. These experiments reveal an initial high friction transient behavior that does not reoccur even after extended periods of exposure to low partial pressures of H{sub 2}O and O{sub 2}. Experiments varying both water vapor pressure and sample temperature show trends of a decreasing friction coefficient as a function of both the decreasing water vapor pressure and the increasing substrate temperature. Theses trends are examined with regard to first order gas-surface interactions. Model fits give activation energies on the order of 40 kJ/mol, which is consistent with water vapor desorption.

  13. Integrated rig for the production of boron nitride nanotubes via the pressurized vapor-condenser method

    DOEpatents

    Smith, Michael W; Jordan, Kevin C

    2014-03-25

    An integrated production apparatus for production of boron nitride nanotubes via the pressure vapor-condenser method. The apparatus comprises: a pressurized reaction chamber containing a continuously fed boron containing target having a boron target tip, a source of pressurized nitrogen and a moving belt condenser apparatus; a hutch chamber proximate the pressurized reaction chamber containing a target feed system and a laser beam and optics.

  14. Integrated Rig for the Production of Boron Nitride Nanotubes via the Pressurized Vapor-Condenser Method

    NASA Technical Reports Server (NTRS)

    Smith, Michael W. (Inventor); Jordan, Kevin C. (Inventor)

    2014-01-01

    An integrated production apparatus for production of boron nitride nanotubes via the pressure vapor-condenser method. The apparatus comprises: a pressurized reaction chamber containing a continuously fed boron containing target having a boron target tip, a source of pressurized nitrogen and a moving belt condenser apparatus; a hutch chamber proximate the pressurized reaction chamber containing a target feed system and a laser beam and optics.

  15. Saturated fluorescence measurements of the hydroxyl radical in laminar high-pressure flames

    NASA Technical Reports Server (NTRS)

    Carter, Campbell D.; King, Galen B.; Laurendeau, Normand M.

    1990-01-01

    The efficacy of laser saturated fluorescence (LSF) for OH concentration measurements in high pressure flames was studied theoretically and experimentally. Using a numerical model describing the interaction of hydroxyl with nonuniform laser excitation, the effect of pressure on the validity of the balanced cross-rate model was studied along with the sensitivity of the depopulation of the laser-coupled levels to the ratio of rate coefficients describing: (1) electronic quenching to (sup 2) Sigma (+) (v double prime greater than 0), and (2) vibrational relaxation from v double prime greater than 0 to v double prime = 0. At sufficiently high pressures and near-saturated conditions, the total population of the laser-coupled levels reaches an asymptotic value, which is insensitive to the degree of saturation. When the ratio of electronic quenching to vibrational relaxation is small and the rate of coefficients for rotational transfer in the ground and excited electronic states are nearly the same, the balanced cross-rate model remains a good approximation for all pressures. When the above ratio is large, depopulation of the laser-coupled levels becomes significant at high pressures, and thus the balanced cross-rate model no longer holds. Under these conditions, however, knowledge of the depletion of the laser-coupled levels can be used to correct the model. A combustion facility for operation up to 20 atm was developed to allow LSF measurements of OH in high pressure flames. Using this facility, partial saturation in laminar high pressure (less than or equal to 12.3 atm) C2H6/O2/N2 flames was achieved. To evaluate the limits of the balanced cross-rate model, absorption and calibrated LSF measurements at 3.1 and 6.1 atm were compared. The fluorescence voltages were calibrated with absorption measurements in an atmospheric flame and corrected for their finite sensitivity to quenching with: (1) estimated quenching rate coefficients, and (2) an in situ measurement from a technique employing two fluorescence detection geometries.

  16. Measurements on Melting Pressure, Metastable Solid Phases, and Molar Volume of Univariant Saturated Helium Mixture

    NASA Astrophysics Data System (ADS)

    Rysti, J.; Manninen, M. S.; Tuoriniemi, J.

    2014-06-01

    A concentration-saturated helium mixture at the melting pressure consists of two liquid phases and one or two solid phases. The equilibrium system is univariant, whose properties depend uniquely on temperature. Four coexisting phases can exist on singular points, which are called quadruple points. As a univariant system, the melting pressure could be used as a thermometric standard. It would provide some advantages compared to the current reference, namely pure He, especially at the lowest temperatures below 1 mK. We have extended the melting pressure measurements of the concentration-saturated helium mixture from 10 to 460 mK. The density of the dilute liquid phase was also recorded. The effect of the equilibrium crystal structure changing from hcp to bcc was clearly seen at mK at the melting pressure MPa. We observed the existence of metastable solid phases around this point. No evidence was found for the presence of another, disputed, quadruple point at around 400 mK. The experimental results agree well with our previous calculations at low temperatures, but deviate above 200 mK.

  17. On fluid reserves and the production of superheated steam from fractured, vapor-dominated geothermal reservoirs

    Microsoft Academic Search

    K. Pruess; T. N. Narasimhan

    1982-01-01

    Vapor-dominated geothermal reservoirs produce saturated or superheated steam, and vertical pressure gradients are close to vapor static. These observations have been generally accepted as providing conclusive evidence that the liquid saturation must be rather small (<50%) in order that liquid may be nearly immobile. This conclusion ignores the crucial role of conductive heat transfer mechanisms in fractured reservoirs for vaporizing

  18. Atmospheric Pressure Plasma Enhanced Chemical Vapor Deposition of Borophosphosilicate Glass Films

    Microsoft Academic Search

    Minghui Yin; Lingli Zhao; Xiangyu Xu; Shouguo Wang

    2008-01-01

    Borophosphosilicate glass (BPSG) films have been grown on silicon wafers by plasma enhanced chemical vapor deposition at atmospheric pressure (AP-PECVD). Tetraethoxysilane (TEOS), triethylborate (TEB), and trimethylphosphite (TMPI) were adopted as precursors, and argon and oxygen were respectively used as the carrier and reactive gases to produce stable plasma at atmospheric pressure. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS),

  19. Feasibility of hydroxyl concentration measurements by laser-saturated fluorescence in high-pressure flames

    NASA Technical Reports Server (NTRS)

    Carter, Campbell D.; King, Galen B.; Laurendeau, Normand M.; Salmon, J. Thaddeus

    1987-01-01

    The effect of pressure on the laser-saturated fluorescence method for measuring OH concentration in high-pressure flames is studied using calculations for the burned-gas region of a stoichiometric H2-O2 flame at 2000 K. A numerical model of the excitation dynamics of OH is developed to explore the validity of the balanced cross-rate model at higher pressures. It is shown that depopulation of the laser-coupled levels is sensitive to collisions which depopulate v-double-prime (VDP) = 0 and to rate coefficients for rotational transfer in the ground state which are smaller than those in the excited state. In particular, it is shown that the depopulation of VDP = 0, and hence the laser-coupled levels, depends on the probability of electronic quenching to vibrational levels for which VDP is greater than 0 and vibrational relaxation to VDP = 0.

  20. Vapor pressure and void size effects on failure of a constrained ductile film

    NASA Astrophysics Data System (ADS)

    Guo, T. F.; Cheng, L.

    2003-06-01

    To achieve certain properties, semiconductor adhesives and molding compounds are made by blending filler particles with polymer matrix. Moisture collects at filler particle/polymer matrix interfaces and within voids of the composite. At reflow temperatures, the moisture vaporizes. The rapidly expanding vapor creates high internal pressure on pre-existing voids and particle/matrix interfaces. The simultaneous action of thermal stresses and internal vapor pressure drives both pre-existing and newly nucleated voids to grow and coalesce causing material failure. Particularly susceptible are polymeric films and adhesives joining elastic substrates, e.g. Ag filled epoxy. Several competing failure mechanisms are studied including: near-tip void growth and coalescence with the crack; extensive void growth and formation of an extended damaged zone emanating from the crack; and rapid void growth at highly stressed sites at large distances ahead of the crack, leading to multiple damaged zones. This competition is driven by the interplay between stress elevation induced by constrained plastic flow and stress relaxation due to vapor pressure assisted void growth. A model problem of a ductile film bonded between two elastic substrates, with a centerline crack, is studied. The computational study employs a Gurson porous material model incorporating vapor pressure effects. The formation of multiple damaged zones is favored when the film contains small voids or dilute second-phase particle distribution. The presence of large voids or high vapor pressure favor the growth of a self-similar damage zone emanating from the crack. High vapor pressure accelerates film cracking that can cause device failures.

  1. Fractional-calculus model for temperature and pressure waves in fluid-saturated porous rocks

    NASA Astrophysics Data System (ADS)

    Garra, Roberto

    2011-09-01

    We study a fractional time derivative generalization of a previous Natale-Salusti model about nonlinear temperature and pressure waves, propagating in fluid-saturated porous rocks. Their analytic solutions, i.e., solitary shock waves characterized by a sharp front, are here generalized, introducing a formalism that allows memory mechanisms. In realistic wave propagation in porous media we must take into account spatial or temporal variability of permeability, diffusivity, and other coefficients due to the system “history.” Such a rock fracturing or fine particulate migration could affect the rock and its pores. We therefore take into account these phenomena by introducing a fractional time derivative to simulate a memory-conserving formalism. We also discuss this generalized model in relation to the theory of dynamic permeability and tortuosity in fluid-saturated porous media. In such a realistic model we obtain exact solutions of Burgers’ equation with time fractional derivatives in the inviscid case.

  2. Sulfide saturation of basalt and andesite melts at high pressures and temperatures

    NASA Technical Reports Server (NTRS)

    Wendlandt, R. F.

    1982-01-01

    When the sulfur content of an Fe-bearing magma exceeds the saturation limit for the bulk composition, an immiscible iron sulfide melt fraction separates. For an understanding of the geochemistry of sulfur-bearing magmatic systems, more information is needed regarding the solubility of metal sulfide in silicate melt at its source and the solubility changes as a function of changing intensive and extensive variables. In the present investigation, the sulfur saturation surface is determined for the pressure range from 12.5 to 30 kbar and the temperature range from 1300 to 1460 C for three silicate melt compositions representing a range of SiO2 and FeO compositions.

  3. Measurements of Capillary Pressure-Saturation Relationships for Silica Sands Using Light Transmission Visualization and a Rapid Pseudo Static Methods

    EPA Science Inventory

    Measurement of water saturation in porous media is essential for many types of studies including subsurface water flow, subsurface colloids transport and contaminant remediation to name a few. Water saturation (S) in porous media is dependent on the capillary pressure (Pc) which,...

  4. Vapor Pressure of Tektite Glass and Its Bearing on Tektite Trajectories Determined from Aerodynamic Analysis

    Microsoft Academic Search

    FRANK J. CENTOLANZI; DEAN R. CHAPMAN

    1966-01-01

    Various experiments have been conducted to resolve a large discrepancy be- tween two measurements that have been reported for the vapor pressure of tektite glass. This discrepancy significantly affects the trajectories and mode of tektite origin as determined from calculations oœ aerodynamic ablation. Measurements in a furnace oœ vaporization rate relative to that of four different standards (SiO2, TiO_, Au,

  5. Meteorological Tables for Determination of Precipitable Water, Temperatures and Pressures Aloft for a Saturated Pseudoadiabatic Atmosphere -- in the Metric System

    E-print Network

    Eihle, W. O.; Powers, R. J.; Clark, R.A.

    TR-16 1968 Meteorological Tables for Determination of Precipitable Water, Temperatures and Pressures Aloft for a Saturated Pseudoadiabatic Atmosphere?in the Metric System W.O. Eihle R.J. Powers R.A. Clark...

  6. Evaluation of model approximations in simulating pressure swing adsorption-solvent vapor recovery

    Microsoft Academic Search

    Yujun Liu; James A. Ritter

    1997-01-01

    Sixteen different mathematical models, based on all combinations of four major assumptions (i.e., frozen solid phase during pressurization\\/blowdown, isothermal, equilibrium, and constant gas phase velocity during constant pressure steps), were evaluated in simulating a pressure swing adsorption-solvent vapor recovery process, which was representative of any Langmuirian system utilizing a Skarstrom-type cycle. The evaluation was based on the bed dynamics and

  7. Loudness discomfort level for speech: comparison of two instructional sets for saturation sound pressure level selection.

    PubMed

    Beattie, R C; Svihovec, D A; Carmen, R E; Kunkel, H A

    1980-01-01

    This study was undertaken to compare the speech loudness discomfort levels (LDL's) with two instructional sets which have been proposed for saturation sound pressure level selection of hearing aids. The phraseology recommended by McCandless and by Berger was presented to normal-hearing and hearing-impaired listeners. The normal-hearing subjects obtained mean LDL's of 94.6 and 111.9 dB SPL for these respective instructions, which was statistically significant. The hearing-impaired listeners also showed LDL's with Berger's instructions (114.7 dB SPL) to be significantly higher than with McCandless' instructional set (109.3 dB SPL). Consequently, this investigation suggests that these two instructional sets may lead to substantially different saturation sound pressure levels. Further studies are needed to determine the most appropriate phraseology for LDL measurement, including the assessment of speech intelligibility at various saturation sound pressure levels. Another instructional set was constructed which (1) includes an explanation to patients of the purpose and importance of the test, (2) requests listeners to indicate the upper level they are "willing" to listen as opposed to the level they are "able" to listen, (3) instructs patients to search thoroughly around their LDL before making a final judgment, and (4) contains a statement that the LDL should be made with the understanding that the speech could be listened to for a period of time. Whatever instructions are used, clinicians are advised to interpret their LDL's very cautiously until validational studies are available. PMID:7409356

  8. Establishing a quantitative functional relationship between capillary pressure saturation and interfacial area. 1998 annual progress report

    SciTech Connect

    Montemagno, C.D. [Cornell Univ., Ithaca, NY (US); Celia, M. [Princeton Univ., NJ (US); Gray, W.G. [Univ. of Notre Dame, IN (US)

    1998-06-01

    'Through an integrated and focused research program that is comprised of theoretical, computational and experimental efforts this research effort is directed at: (1) improving on newly developed laboratory techniques to quantify and directly measure the functional relationship between phase interfacial area (a), saturation (S) and capillary pressure (Pc), (2) developing new computational algorithms in conjunction with laboratory measurements to predict Pc, S and a, (3) testing existing theory and developing new theory to describe the relationship between Pc, S and a at the large scale, and (4) synthesizing the results of the experimental, computational and theoretical investigative efforts to develop a generic model based upon an intrinsic soil metric to describe the functional dependence of Pc, S and a. The results of this research could be used to generate a site specific soil moisture characteristic surface. Ultimately the results of this research could serve as the foundation upon which the true health and safety risk of a site could be evaluated, the applicability of various remediation technologies examined, and the performance of implemented treatment strategies controlled. This report summarizes work after 18 months of a 3-year project. The authors are working to integrate the theory, experiments, and numerical simulations into a coherent approach to study the role of interfacial areas in porous media flow physics. The recent efforts have focused on quantifying the relationship between capillary pressure, saturation, and interfacial areas. The theory developed by Gray et al. (1998) indicates clearly that the traditional relationship between capillary pressure and saturation is incomplete, and interfacial area per unit volume must be added to the functional dependence. The theory does not, however, provide the form of that functional dependence; determination of this relationship must be done experimentally. To this end, both the network modelling and the PVI approach are being pursued.'

  9. Pore pressure diffusion and the hydrologic response of nearly saturated, thin landslide deposits of rainfall

    SciTech Connect

    Haneberg, W.C. (New Mexico Bureau of Mines and Mineral Resources, New Mexico Institute of Mining and Technology, Socorro, NM (United States))

    1991-11-01

    Previous workers have correlated slope failures during rainstorms with rainfall intensity, rainfall duration, and seasonal antecedent rainfall. This note shows how such relationships can be interpreted using a periodic steady-state solution to the well-known linear pressure diffusion equation. Normalization of the governing equation yields a characteristic response time that is a function of soil thickness, saturated hydraulic conductivity, and pre-storm effective porosity, and which is analogous to the travel time of a piston wetting front. The effects of storm frequency and magnitude are also successfully quantified using dimensionless attenuation factors and lag times.

  10. A simple grand canonical approach to compute the vapor pressure of bulk and finite size systems

    SciTech Connect

    Factorovich, Matías H.; Scherlis, Damián A. [Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, Buenos Aires C1428EHA (Argentina)] [Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, Buenos Aires C1428EHA (Argentina); Molinero, Valeria [Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850 (United States)] [Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112-0850 (United States)

    2014-02-14

    In this article we introduce a simple grand canonical screening (GCS) approach to accurately compute vapor pressures from molecular dynamics or Monte Carlo simulations. This procedure entails a screening of chemical potentials using a conventional grand canonical scheme, and therefore it is straightforward to implement for any kind of interface. The scheme is validated against data obtained from Gibbs ensemble simulations for water and argon. Then, it is applied to obtain the vapor pressure of the coarse-grained mW water model, and it is shown that the computed value is in excellent accord with the one formally deduced using statistical thermodynamics arguments. Finally, this methodology is used to calculate the vapor pressure of a water nanodroplet of 94 molecules. Interestingly, the result is in perfect agreement with the one predicted by the Kelvin equation for a homogeneous droplet of that size.

  11. Preconcentrator with high volume chiller for high vapor pressure particle detection

    DOEpatents

    Linker, Kevin L

    2013-10-22

    Apparatus and method for collecting particles of both high and low vapor pressure target materials entrained in a large volume sample gas stream. Large volume active cooling provides a cold air supply which is mixed with the sample gas stream to reduce the vapor pressure of the particles. In embodiments, a chiller cools air from ambient conditions to 0-15.degree. C. with the volumetric flow rate of the cold air supply being at least equal to the volumetric flow rate of the sample gas stream. In further embodiments an adsorption media is heated in at least two stages, a first of which is below a threshold temperature at which decomposition products of the high vapor pressure particle are generated.

  12. Microfluidic vapor-diffusion barrier for pressure reduction in fully closed PCR modules.

    PubMed

    Czilwik, G; Schwarz, I; Keller, M; Wadle, S; Zehnle, S; von Stetten, F; Mark, D; Zengerle, R; Paust, N

    2015-02-01

    Microfluidic systems for polymerase chain reaction (PCR) should be fully closed to avoid vapor loss and to exclude the risk of contaminating the laboratory environment. In closed systems however, the high temperatures of up to 95 °C associated with PCR cause high overpressures up to 100 kPa, dominated by the increase of vapor partial pressure upon evaporation. Such high overpressures pose challenges to the mechanical stability of microfluidic chips as well as to the liquid handling in integrated sample-to-answer systems. In this work, we drastically reduce the pressure increase in fully closed PCR systems by integrating a microchannel that serves as a vapor-diffusion barrier (VDB), separating the liquid-filled PCR chamber from an auxiliary air chamber. In such configurations, propagation of vapor from the PCR chamber into the auxiliary air chamber and as a consequence the increase of pressure is limited by the slow diffusion process of vapor through the VDB. At temperature increase from 23 °C to 95 °C, we demonstrate the reduction of overpressure from more than 80 kPa without the VDB to only 35 kPa with the VDB. We further demonstrate proper function of VDB and its easy integration with downstream processes for PCR based nucleic acid amplification within centrifugal microfluidics. Without integration of the VDB, malfunction due to pressure-induced delamination of the microfluidic chip occurred. PMID:25524461

  13. Theoretical and experimental studies on freezing point depression and vapor pressure deficit as methods to measure osmotic pressure of aqueous polyethylene glycol and bovine serum albumin solutions.

    PubMed

    Kiyosawa, Keitaro

    2003-05-01

    For survival in adverse environments where there is drought, high salt concentration or low temperature, some plants seem to be able to synthesize biochemical compounds, including proteins, in response to changes in water activity or osmotic pressure. Measurement of the water activity or osmotic pressure of simple aqueous solutions has been based on freezing point depression or vapor pressure deficit. Measurement of the osmotic pressure of plants under water stress has been mainly based on vapor pressure deficit. However, differences have been noted for osmotic pressure values of aqueous polyethylene glycol (PEG) solutions measured by freezing point depression and vapor pressure deficit. For this paper, the physicochemical basis of freezing point depression and vapor pressure deficit were first examined theoretically and then, the osmotic pressure of aqueous ethylene glycol and of PEG solutions were measured by both freezing point depression and vapor pressure deficit in comparison with other aqueous solutions such as NaCl, KCl, CaCl(2), glucose, sucrose, raffinose, and bovine serum albumin (BSA) solutions. The results showed that: (1) freezing point depression and vapor pressure deficit share theoretically the same physicochemical basis; (2) theoretically, they are proportional to the molal concentration of the aqueous solutions to be measured; (3) in practice, the osmotic pressure levels of aqueous NaCl, KCl, CaCl(2), glucose, sucrose, and raffinose solutions increase in proportion to their molal concentrations and there is little inconsistency between those measured by freezing point depression and vapor pressure deficit; (4) the osmotic pressure levels of aqueous ethylene glycol and PEG solutions measured by freezing point depression differed from the values measured by vapor pressure deficit; (5) the osmotic pressure of aqueous BSA solution measured by freezing point depression differed slightly from that measured by vapor pressure deficit. PMID:12834836

  14. VAPOR PRESSURE ISOTOPE EFFECTS IN THE MEASUREMENT OF ENVIRONMENTAL TRITIUM SAMPLES.

    SciTech Connect

    Kuhne, W.

    2012-12-03

    Standard procedures for the measurement of tritium in water samples often require distillation of an appropriate sample aliquot. This distillation process may result in a fractionation of tritiated water and regular light water due to the vapor pressure isotope effect, introducing either a bias or an additional contribution to the total tritium measurement uncertainty. The magnitude of the vapor pressure isotope effect is characterized as functions of the amount of water distilled from the sample aliquot and the heat settings for the distillation process. The tritium concentration in the distillate is higher than the tritium concentration in the sample early in the distillation process, it then sharply decreases due to the vapor pressure isotope effect and becomes lower than the tritium concentration in the sample, until the high tritium concentration retained in the boiling flask is evaporated at the end of the process. At that time, the tritium concentration in the distillate again overestimates the sample tritium concentration. The vapor pressure isotope effect is more pronounced the slower the evaporation and distillation process is conducted; a lower heat setting during the evaporation of the sample results in a larger bias in the tritium measurement. The experimental setup used and the fact that the current study allowed for an investigation of the relative change in vapor pressure isotope effect in the course of the distillation process distinguish it from and extend previously published measurements. The separation factor as a quantitative measure of the vapor pressure isotope effect is found to assume values of 1.034 {+-} 0.033, 1.052 {+-} 0.025, and 1.066 {+-} 0.037, depending on the vigor of the boiling process during distillation of the sample. A lower heat setting in the experimental setup, and therefore a less vigorous boiling process, results in a larger value for the separation factor. For a tritium measurement in water samples, this implies that the tritium concentration could be underestimated by 3 - 6%.

  15. Use of temporal patterns in vapor pressure deficit to explain spatial autocorrelation dynamics in tree transpiration.

    PubMed

    Adelman, Jonathan D; Ewers, Brent E; Mackay, D Scott

    2008-04-01

    To quantify the relationship between temporal and spatial variation in tree transpiration, we measured sap flow in 129 trees with constant-heat sap flow sensors in a subalpine forest in southern Wyoming, USA. The forest stand was located along a soil water gradient from a stream side to near the top of a ridge. The stand was dominated by Pinus contorta Dougl. ex Loud. with Picea engelmannii Parry ex Engelm and Abies lasiocarpa (Hook.) Nutt. present near the stream and scattered individuals of Populus tremuloides Michx. throughout the stand. We used a cyclic sampling design that maximized spatial information with a minimum number of samples for semivariogram analyses. All species exhibited previously established responses to environmental variables in which the dominant driver was a saturating response to vapor pressure deficit (D). This response to D is predictable from tree hydraulic theory in which stomatal conductance declines as D increases to prevent excessive cavitation. The degree to which stomatal conductance declines with D is dependent on both species and individual tree physiology and increases the variability in transpiration as D increases. We quantified this variability spatially by calculating the spatial autocorrelation within 0.2-kPa D bins. Across 11 bins of D, spatial autocorrelation in individual tree transpiration was inversely correlated to D and dropped from 45 to 20 m. Spatial autocorrelation was much less for transpiration per unit leaf area and not significant for transpiration per unit sapwood area suggesting that spatial autocorrelation within a particular D bin could be explained by tree size. Future research should focus on the mechanisms underlying tree size spatial variability, and the potentially broad applicability of the inverse relationship between D and spatial autocorrelation in tree transpiration. PMID:18244950

  16. Vapor-modulated heat pipe for improved temperature control

    NASA Technical Reports Server (NTRS)

    Edwards, D. K.; Eninger, J. E.; Ludeke, E. E.

    1978-01-01

    Dryout induced by vapor throttling makes control of equipment temperature less dependent on variations in sink environment. Mechanism controls flow of vapor in heat pipe by using valve in return path to build difference in pressure and also difference in saturation temperature of the vapor. In steady state, valve closes just enough to produce partial dryout that achieves required temperature drop.

  17. Vapor pressure and normal boiling point predictions for pure methyl esters and biodiesel fuels

    Microsoft Academic Search

    W. Yuan; A. C. Hansen; Q. Zhang

    2005-01-01

    Temperature dependent vapor pressures of the methyl esters of fourteen fatty acids that are commonly present in biodiesel fuels were predicted by the Antoine equation and a group contribution method. The predicted boiling points of these esters up to a pressure of 100mmHg were within ±1.0% of reported data for these two methods. Normal boiling points were determined from both

  18. Prediction of the liquid-vapor equilibrium pressure using the quasi-Gaussian entropy theory

    NASA Astrophysics Data System (ADS)

    Amadei, A.; Roccatano, D.; Apol, M. E. F.; Berendsen, H. J. C.; Di Nola, A.

    1996-10-01

    We derived a method to evaluate the liquid-vapor equilibrium pressure, with high accuracy over a large range of temperature, using the quasi-Gaussian entropy theory. The final expression that we obtain for the equilibrium pressure as a function of the temperature can be considered as a very accurate approximate solution of the Clausius-Clapeyron equation. The method was applied to water, methanol and mercury, and was compared to two usual approximations of the Clausius-Clapeyron equation.

  19. Rotating plasma discharges of high-pressure molecular vapor using circularly polarized microwaves

    Microsoft Academic Search

    Jin Joong Kim; Jung Tae Ko; Dong Ho Won; Jeong Won Kim; S. S. Kim; Hong-Young Chang

    2004-01-01

    We report an experimental demonstration of rotating plasma discharges of diatomic molecular vapor at pressures of a few hundred kPa, i.e., above atmospheric pressure, using circularly polarized microwaves at 2.45 GHz with no external magnetic fields. The active zone of discharges is observed to rotate at frequency of the order of 0.1-20 Hz, which is equivalent to a linear speed

  20. CONTAMINANT VAPOR TRANSPORT IN A DEEP VADOSE ZONE: INFLUENCES OF BAROMETRIC PRESSURE, DIFFUSION, AND DENSITY-DRIVEN FLOW

    Microsoft Academic Search

    John E. McCray; Wayne Downs; Ronald W. Falta; L. Todd Housley

    Daily atmospheric pressure fluctuations cause gas-pressure variations in the subsurface. These pressure variations serve as driving forces for vapor transport. The objective of this research is to investigate the influence and relative importance of barometric-pressure fluctuations in deep vadose zones on transport of organic-contaminant vapors compared to gas-phase diffusion and density-driven transport. A numerical three-dimensional multiphase- fluid-flow model is calibrated

  1. Equilibrium theory for solvent vapor recovery by pressure swing adsorption: analytical solution for process performance

    Microsoft Academic Search

    Dharmashankar Subramanian; James A. Ritter

    1997-01-01

    A simple, analytic, equilibrium theory model based on wave interactions that occur in adsorption columns, has been formulated to predict directly the periodic state and to analyze the application of pressure swing adsorption (PSA) for solvent vapor recovery (SVR). The analysis of this cyclic process has been carried out using a fully convex, Langmuirian isotherm, with and without breakthrough of

  2. Vapor Pressures and Thermodynamics of Oxygen-Containing Polycyclic Aromatic Hydrocarbons Measured Using Knudsen Effusion

    PubMed Central

    Goldfarb, Jillian L.

    2013-01-01

    Polycyclic aromatic hydrocarbons (PAHs) and their oxygenated derivatives (OPAHs) are ubiquitous environmental pollutants resulting from the incomplete combustion of coal and fossil fuels. Their vapor pressures are key thermodynamic data essential for modeling fate and transport within the environment. The present study involved nine PAHs containing oxygen heteroatoms, including aldehyde, carboxyl and nitro groups, specifically: 2-nitrofluorene; 9-fluorenecarboxylic acid; 2-fluorenecarboxaldehyde; 2-anthracenecarboxylic acid; 9-anthracenecarboxylic acid; 9-anthraldehyde; 1-nitropyrene; 1-pyrenecarboxaldehyde and 1-bromo-2-naphthoic acid. The vapor pressures of these compounds, with molecular weights ranging from 194 to 251 grams per mole, were measured using the isothermal Knudsen effusion technique in the temperature range of 329 to 421. The corresponding enthalpies of sublimation, calculated via the Clausius-Clapeyron equation, are compared to parent, non-oxygenated PAH compound data to determine the effect of the addition of these oxygen-containing heteroatoms. As expected, the addition of –CHO,–COOH, and –NO2 groups onto these PAHs increases the enthalpy of sublimation and decreases the vapor pressure as compared to the parent PAH; the position of substitution also plays a significant role in determining the vapor pressure of these OPAHs. PMID:18220445

  3. Vapor pressures and thermodynamics of oxygen-containing polycyclic aromatic hydrocarbons measured using Knudsen effusion

    SciTech Connect

    Goldfarb, J.L.; Suuberg, E.M. [Brown University, Providence, RI (United States). Division of Engineering

    2008-06-15

    Polycyclic aromatic hydrocarbons (PAHs) and their oxygenated derivatives (OPAHs) are ubiquitous environmental pollutants resulting from the incomplete combustion of coal and fossil fuels. Their vapor pressures are key thermodynamic data essential for modeling fate and transport within the environment. The present study involved nine PAHs containing oxygen heteroatoms, including aldehyde, carboxyl, and nitro groups, specifically 2-nitrofluorene, 9-fluorenecarboxylic acid, 2-fluorenecarboxaldehyde, 2-anthracenecarboxylic acid, 9-anthracenecarboxylic acid, 9-anthraldehyde, 1-nitropyrene, 1-pyrenecarboxaldehyde, and 1-bromo-2-naphthoic acid. The vapor pressures of these compounds, with molecular weights ranging from 194 to 251 g/mol, were measured using the isothermal Knudsen effusion technique in the temperature range of 329 to 421 K. The corresponding enthalpies of sublimation, calculated via the Clausius-Clapeyron equation, are compared to parent, nonoxygenated PAH compound data to determine the effect of the addition of these oxygen-containing heteroatoms. As expected, the addition of -CHO, -COOH, and -NO{sub 2} groups onto these PAHs increases the enthalpy of sublimation and decreases the vapor pressure as compared to the parent PAH; the position of substitution also plays a significant role in determining the vapor pressure of these OPAHs.

  4. Geometric Phase in the Condensed Vapor of rb Under Pressure and External Magnetic Field

    NASA Astrophysics Data System (ADS)

    Yu, Zhao-Xian; Jiao, Zhi-Yong; Li, Xiang-Gui

    By using the Lewis-Riesenfeld invariant theory, we have studied the geometric phase in the condensed vapor of Rb under pressure and external time-dependent magnetic field. We find that the geometric phase in the cycle case has nothing to do with the coupling constant between electron and atomic nucleus, and the external time-dependent magnetic field.

  5. Effect of additives on the antiknock properties and Reid vapor pressure of gasoline

    Microsoft Academic Search

    Rosângela da Silva; Renato Cataluña; Eliana Weber de. Menezes; Dimitrios Samios; Clarisse M. Sartori Piatnicki

    2005-01-01

    An evaluation was made of the effect produced by the addition of oxygenates such as ethanol, ETBE and MTBE and nonoxygenates such as isooctane and toluene on the Reid vapor pressure (RVP) and octane number of two types of gasoline with different chemical compositions. Locally produced gasoline was blended with five different percentages (v\\/v) of the additives, i.e. 5, 10,

  6. VAPOR PRESSURE AND MELTING BEHAVIOR OF SULFURIC ACID-WATER SYSTEMS

    EPA Science Inventory

    An experimental apparatus was designed and constructed to use high vacuum and mass spectrometric techniques to determine total and partial vapor pressures above bulk liquid samples in the temperature range between -65C and 25C. Observations on the sulfuric acid-water system revea...

  7. Influence of water vapor pressure on the apparent capacity for physiological thermoregulation in reptiles

    Microsoft Academic Search

    Wesley W. Weathers

    1972-01-01

    The rate of body temperature change was determined as lizards,Dipsosaurus dorsalis, were heated and cooled between 20 and 40 ° C, at various ambient water vapor pressures (WVP). While changes in WVP did not affect the rate of cooling, the rate of temperature change during heating increased exponentially with increasing WVP (Fig. 4). The ratio of the rate of body

  8. Vapor pressures and thermodynamics of oxygen-containing polycyclic aromatic hydrocarbons measured using Knudsen effusion.

    PubMed

    Goldfarb, Jillian L; Suuberg, Eric M

    2008-06-01

    Polycyclic aromatic hydrocarbons (PAHs) and their oxygenated derivatives (OPAHs) are ubiquitous environmental pollutants resulting from the incomplete combustion of coal and fossil fuels. Their vapor pressures are key thermodynamic data essential for modeling fate and transport within the environment. The present study involved nine PAHs containing oxygen heteroatoms, including aldehyde, carboxyl, and nitro groups, specifically 2-nitrofluorene, 9-fluorenecarboxylic acid, 2-fluorenecarboxaldehyde, 2-anthracenecarboxylic acid, 9-anthracenecarboxylic acid, 9-anthraldehyde, 1-nitropyrene, 1-pyrenecarboxaldehyde, and 1-bromo-2-naphthoic acid. The vapor pressures of these compounds, with molecular weights ranging from 194 to 251 g/mol, were measured using the isothermal Knudsen effusion technique in the temperature range of 329 to 421 K. The corresponding enthalpies of sublimation, calculated via the Clausius-Clapeyron equation, are compared to parent, nonoxygenated PAH compound data to determine the effect of the addition of these oxygen-containing heteroatoms. As expected, the addition of -CHO, -COOH, and -NO(2) groups onto these PAHs increases the enthalpy of sublimation and decreases the vapor pressure as compared to the parent PAH; the position of substitution also plays a significant role in determining the vapor pressure of these OPAHs. PMID:18220445

  9. Thermodynamic properties and vapor pressures of polar fluids from a four-parameter corresponding-states method

    SciTech Connect

    Wilding, W.V.; Johnson, J.K.; Rowley, R.L.

    1987-11-01

    A recently proposed extended Lee-Kesler corresponding-states method (ELK) for polar fluids which accurately predicts compressibility factors and departure functions is considered. Tables of polar deviation functions have been generated and values of the shape/size and polar parameters for 52 polar fluids have been calculated, allowing the method to be used for quick hand calculation in addition to the previous, more accurate, computer applications. Additionally, vapor pressures of 44 pure polar fluids were computed using the full version of the ELK and the equality of the Gibbs free energy criterion for phase equilibrium. An ELK vapor pressure correlation is proposed which is essentially numerically equivalent to, but computationally simpler than, the former method. Computed vapor pressures agree with experimental values as well or better than other vapor pressure equations designed exclusively for vapor pressure prediction of polar fluids.

  10. Angular Momentum Transport by MHD Turbulence in Accretion Disks: Gas Pressure Dependence of the Saturation Level of the Magnetorotational Instability

    E-print Network

    Takayoshi Sano; Shu-ichiro Inutsuka; Neal J. Turner; James M. Stone

    2003-12-18

    The saturation level of the magnetorotational instability (MRI) is investigated using three-dimensional MHD simulations. The shearing box approximation is adopted and the vertical component of gravity is ignored, so that the evolution of the MRI is followed in a small local part of the disk. We focus on the dependence of the saturation level of the stress on the gas pressure, which is a key assumption in the standard alpha disk model. From our numerical experiments it is found that there is a weak power-law relation between the saturation level of the Maxwell stress and the gas pressure in the nonlinear regime; the higher the gas pressure, the larger the stress. Although the power-law index depends slightly on the initial field geometry, the relationship between stress and gas pressure is independent of the initial field strength, and is unaffected by Ohmic dissipation if the magnetic Reynolds number is at least 10. The relationship is the same in adiabatic calculations, where pressure increases over time, and nearly-isothermal calculations, where pressure varies little with time. Our numerical results are qualitatively consistent with an idea that the saturation level of the MRI is determined by a balance between the growth of the MRI and the dissipation of the field through reconnection. The quantitative interpretation of the pressure-stress relation, however, may require advances in the theoretical understanding of non-steady magnetic reconnection.

  11. Non-invasive Positive Pressure Ventilation during Sleep at 3800m: relationship to Acute Mountain Sickness and sleeping oxyhemoglobin saturation

    PubMed Central

    Johnson, PL; Popa, DA; Prisk, GK; Sullivan, CE; Edwards, N

    2014-01-01

    Background and objectives Ascent to high altitude results in hypobaric hypoxia and some individuals will develop Acute Mountain Sickness, which has been shown to be associated with low oxyhemoglobin saturation during sleep. Previous research has shown that positive end-expiratory pressure by use of expiratory valves in a face mask while awake, results in a reduction in AMS symptoms and higher oxyhemoglobin saturation. We aimed to test whether pressure ventilation during sleep would prevent AMS by keeping oxyhaemoglobin higher during sleep. Methods We compared sleeping oxyhemoglobin saturation and the incidence and severity of Acute Mountain Sickness in seven subjects sleeping for two consecutive nights at 3800m above sea level using either non-invasive positive pressure ventilation that delivered positive inspiratory and expiratory airway pressure via a face mask, or sleeping without assisted ventilation. The presence and severity of Acute Mountain Sickness was assessed by administration of the Lake Louise questionnaire. Results We found significant increases in the mean and minimum sleeping oxyhemoglobin saturation and decreases in AMS symptoms in subjects who used positive pressure ventilation during sleep. Mean and minimum sleeping SaO2 was lower in subjects who developed AMS after the night spent without positive pressure ventilation. Conclusion The use of positive pressure ventilation during sleep at 3800m significantly increased the sleeping oxygen saturation; we suggest that the marked reduction in symptoms of AMS is due to this higher sleeping SaO2. We agree with the findings from previous studies that the development of AMS is associated with a lower sleeping oxygen saturation. PMID:20051046

  12. Advanced Computational Modeling of Vapor Deposition in a High-Pressure Reactor

    NASA Technical Reports Server (NTRS)

    Cardelino, Beatriz H.; Moore, Craig E.; McCall, Sonya D.; Cardelino, Carlos A.; Dietz, Nikolaus; Bachmann, Klaus

    2004-01-01

    In search of novel approaches to produce new materials for electro-optic technologies, advances have been achieved in the development of computer models for vapor deposition reactors in space. Numerical simulations are invaluable tools for costly and difficult processes, such as those experiments designed for high pressures and microgravity conditions. Indium nitride is a candidate compound for high-speed laser and photo diodes for optical communication system, as well as for semiconductor lasers operating into the blue and ultraviolet regions. But InN and other nitride compounds exhibit large thermal decomposition at its optimum growth temperature. In addition, epitaxy at lower temperatures and subatmospheric pressures incorporates indium droplets into the InN films. However, surface stabilization data indicate that InN could be grown at 900 K in high nitrogen pressures, and microgravity could provide laminar flow conditions. Numerical models for chemical vapor deposition have been developed, coupling complex chemical kinetics with fluid dynamic properties.

  13. Advanced Computational Modeling of Vapor Deposition in a High-pressure Reactor

    NASA Technical Reports Server (NTRS)

    Cardelino, Beatriz H.; Moore, Craig E.; McCall, Sonya D.; Cardelino, Carlos A.; Dietz, Nikolaus; Bachmann, Klaus

    2004-01-01

    In search of novel approaches to produce new materials for electro-optic technologies, advances have been achieved in the development of computer models for vapor deposition reactors in space. Numerical simulations are invaluable tools for costly and difficult processes, such as those experiments designed for high pressures and microgravity conditions. Indium nitride is a candidate compound for high-speed laser and photo diodes for optical communication system, as well as for semiconductor lasers operating into the blue and ultraviolet regions. But InN and other nitride compounds exhibit large thermal decomposition at its optimum growth temperature. In addition, epitaxy at lower temperatures and subatmospheric pressures incorporates indium droplets into the InN films. However, surface stabilization data indicate that InN could be grown at 900 K in high nitrogen pressures, and microgravity could provide laminar flow conditions. Numerical models for chemical vapor deposition have been developed, coupling complex chemical kinetics with fluid dynamic properties.

  14. Evaluation of model approximations in simulating pressure swing adsorption-solvent vapor recovery

    SciTech Connect

    Liu, Y.; Ritter, J.A. [Univ. of South Carolina, Columbia, SC (United States)] [Univ. of South Carolina, Columbia, SC (United States)

    1997-05-01

    Sixteen different mathematical models, based on all combinations of four major assumptions (i.e., frozen solid phase during pressurization/blowdown, isothermal, equilibrium, and constant gas phase velocity during constant pressure steps), were evaluated in simulating a pressure swing adsorption-solvent vapor recovery process, which was representative of any Langmuirian system utilizing a Skarstrom-type cycle. The evaluation was based on the bed dynamics and process performance predicted by each model, and obtained from a 2{sup 4} full factorial design. Overwhelmingly, the results showed that the predictions of the process dynamics and performance from the 16 different models varied widely, and depended on which combination of assumptions was applied. Qualitative trends, based on the factorial analysis, indicated that both the constant velocity and frozen assumptions caused an overprediction in the solvent vapor enrichment and the bed capacity factor; and significant interaction effects existed between these two assumptions. Also, all of the models that assumed local equilibrium and underestimated both the solvent vapor enrichment and the bed capacity factor, whereas all of the isothermal models overestimated the solvent vapor enrichment but underestimated the bed capacity factor.

  15. The vapor pressures of supercooled NHO3/H2O solutions. [in polar stratospheric clouds

    NASA Technical Reports Server (NTRS)

    Hanson, David R.

    1990-01-01

    A procedure utilizing the Gibbs-Duhem relation is used to extrapolate vapor pressures of supercooled HNO3 mixtures to 190 K. Values of A and B from the equation logP = A - B/T are presented for solutions between 0.20 and 0.25 mole fraction HNO3. In the stratosphere, if sufficient HNO3 vapor is present because it has not come into equilibrium with the nitric acid trihydrate, supercooled nitric acid solutions could condense at temperatures up to 1.5 + or - 0.8 K above the ice point.

  16. Measurements of blast waves from bursting frangible spheres pressurized with flash-evaporation vapor or liquid

    NASA Technical Reports Server (NTRS)

    Esparaza, E. D.; Baker, W. E.

    1977-01-01

    Incident overpressure data from frangible spheres pressurized with a flash-evaporating fluid in liquid and vapor form were obtained in laboratory experiments. Glass spheres under higher than ambient internal pressure of Freon-12 were purposely burst to obtain time histories of overpressure. Nondimensional peak pressures, arrival and duration times, and impulses are presented, and whenever possible plotted and compared with compiled data for Pentolite high-explosive. The data are generally quite repeatable and show differences from blast data produced by condensed high-explosives.

  17. 46 CFR 39.20-13 - High and low vapor pressure protection for tankships-T/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false High and low vapor pressure protection for tankships-T...controlled; and (b) Has a high pressure and a low pressure alarm that...controlled; (2) Alarms at a high pressure of not more than 90...

  18. 46 CFR 39.20-13 - High and low vapor pressure protection for tankships-T/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false High and low vapor pressure protection for tankships-T...controlled; and (b) Has a high pressure and a low pressure alarm that...controlled; (2) Alarms at a high pressure of not more than 90...

  19. 46 CFR 39.20-13 - High and low vapor pressure protection for tankships-T/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 false High and low vapor pressure protection for tankships-T...controlled; and (b) Has a high pressure and a low pressure alarm that...controlled; (2) Alarms at a high pressure of not more than 90...

  20. Method and system for determining vapor pressure or composition of hydrocarbon liquids

    SciTech Connect

    Baillie, L.A.; Skinner, J.L.

    1988-03-29

    A method for determining the vapor pressure of a liquid composition of crude oil and natural gas liquids at a given temperature is described comprising the steps of: causing the liquid composition to flow through eductor means while measuring the total pressure of the liquid at a location in the eductor means which comprises the minimum pressure point of fluid flow in the eductor means for selected pressure differentials measured across the eductor means; determining the slope of a curve represented by the locus of the total pressure of the fluid at the minimum pressure point in the eductor means as a function of the selected pressure differential across the eductor means which produces the total pressure, respectively; and determining the intercept of the curve with a curve representing the relationship of total pressure at the minimum pressure point in the eductor means versus the pressure differential across the eductor means for a degassed liquid composition, which intercept comprises the bubble point pressure of the liquid composition.

  1. Pressure adaptation is linked to thermal adaptation in salt-saturated marine habitats.

    PubMed

    Alcaide, María; Stogios, Peter J; Lafraya, Álvaro; Tchigvintsev, Anatoli; Flick, Robert; Bargiela, Rafael; Chernikova, Tatyana N; Reva, Oleg N; Hai, Tran; Leggewie, Christian C; Katzke, Nadine; La Cono, Violetta; Matesanz, Ruth; Jebbar, Mohamed; Jaeger, Karl-Erich; Yakimov, Michail M; Yakunin, Alexander F; Golyshin, Peter N; Golyshina, Olga V; Savchenko, Alexei; Ferrer, Manuel

    2015-02-01

    The present study provides a deeper view of protein functionality as a function of temperature, salt and pressure in deep-sea habitats. A set of eight different enzymes from five distinct deep-sea (3040-4908?m depth), moderately warm (14.0-16.5°C) biotopes, characterized by a wide range of salinities (39-348 practical salinity units), were investigated for this purpose. An enzyme from a 'superficial' marine hydrothermal habitat (65°C) was isolated and characterized for comparative purposes. We report here the first experimental evidence suggesting that in salt-saturated deep-sea habitats, the adaptation to high pressure is linked to high thermal resistance (P value?=?0.0036). Salinity might therefore increase the temperature window for enzyme activity, and possibly microbial growth, in deep-sea habitats. As an example, Lake Medee, the largest hypersaline deep-sea anoxic lake of the Eastern Mediterranean Sea, where the water temperature is never higher than 16°C, was shown to contain halopiezophilic-like enzymes that are most active at 70°C and with denaturing temperatures of 71.4°C. The determination of the crystal structures of five proteins revealed unknown molecular mechanisms involved in protein adaptation to poly-extremes as well as distinct active site architectures and substrate preferences relative to other structurally characterized enzymes. PMID:25330254

  2. Calculations of Freezing Point Depression, Boiling Point Elevation, Vapor Pressure and Enthalpies of Vaporization of Electrolyte Solutions by a Modified Three-Characteristic Parameter Correlation Model

    Microsoft Academic Search

    Xinlei Ge; Xidong Wang

    2009-01-01

    A method was proposed for calculating the thermodynamic properties, freezing point depression, boiling point elevation, vapor\\u000a pressure and enthalpy of vaporization for single solute electrolyte solutions, including aqueous and nonaqueous solutions,\\u000a based on a modified three-characteristic-parameter correlation model. When compared with the corresponding literature values,\\u000a the calculated results show that this method gives a very good approximation, especially for 1-1

  3. Observations on vapor pressure in SPR caverns : sources.

    SciTech Connect

    Munson, Darrell Eugene

    2010-05-01

    The oil of the Strategic Petroleum Reserve (SPR) represents a national response to any potential emergency or intentional restriction of crude oil supply to this country, and conforms to International Agreements to maintain such a reserve. As assurance this reserve oil will be available in a timely manner should a restriction in supply occur, the oil of the reserve must meet certain transportation criteria. The transportation criteria require that the oil does not evolve dangerous gas, either explosive or toxic, while in the process of transport to, or storage at, the destination facility. This requirement can be a challenge because the stored oil can acquire dissolved gases while in the SPR. There have been a series of reports analyzing in exceptional detail the reasons for the increases, or regains, in gas content; however, there remains some uncertainty in these explanations and an inability to predict why the regains occur. Where the regains are prohibitive and exceed the criteria, the oil must undergo degasification, where excess portions of the volatile gas are removed. There are only two known sources of gas regain, one is the salt dome formation itself which may contain gas inclusions from which gas can be released during oil processing or storage, and the second is increases of the gases release by the volatile components of the crude oil itself during storage, especially if the stored oil undergoes heating or is subject to biological generation processes. In this work, the earlier analyses are reexamined and significant alterations in conclusions are proposed. The alterations are based on how the fluid exchanges of brine and oil uptake gas released from domal salt during solutioning, and thereafter, during further exchanges of fluids. Transparency of the brine/oil interface and the transfer of gas across this interface remains an important unanswered question. The contribution from creep induced damage releasing gas from the salt surrounding the cavern is considered through computations using the Multimechanism Deformation Coupled Fracture (MDCF) model, suggesting a relative minor, but potentially significant, contribution to the regain process. Apparently, gains in gas content can be generated from the oil itself during storage because the salt dome has been heated by the geothermal gradient of the earth. The heated domal salt transfers heat to the oil stored in the caverns and thereby increases the gas released by the volatile components and raises the boiling point pressure of the oil. The process is essentially a variation on the fractionation of oil, where each of the discrete components of the oil have a discrete temperature range over which that component can be volatized and removed from the remaining components. The most volatile components are methane and ethane, the shortest chain hydrocarbons. Since this fractionation is a fundamental aspect of oil behavior, the volatile component can be removed by degassing, potentially prohibiting the evolution of gas at or below the temperature of the degas process. While this process is well understood, the ability to describe the results of degassing and subsequent regain is not. Trends are not well defined for original gas content, regain, and prescribed effects of degassing. As a result, prediction of cavern response is difficult. As a consequence of this current analysis, it is suggested that solutioning brine of the final fluid exchange of a just completed cavern, immediately prior to the first oil filling, should be analyzed for gas content using existing analysis techniques. This would add important information and clarification to the regain process. It is also proposed that the quantity of volatile components, such as methane, be determined before and after any degasification operation.

  4. Temperature dependence of the vapor pressure and evaporation coefficient of supercooled water

    NASA Astrophysics Data System (ADS)

    Davies, James F.; Miles, Rachael E. H.; Haddrell, Allen E.; Reid, Jonathan P.

    2014-09-01

    We report measurements of the vapor pressure of water over the supercooled temperature range 248 to 273 K derived from evaporation kinetics measurements of single water droplets. Accurate measurements of the relative humidity of the surrounding gas phase are derived from comparative and sequential measurements of the evaporation kinetics of droplets containing sodium chloride. The temperature dependence of the vapor pressure of supercooled water is shown to conform closely to the parameterization provided by Murphy and Koop (2005) once the uncertainties in experimental and thermophysical parameters are accounted for by ensuring an accurate representation of evaporation rates at temperatures above 273 K. Further, from a sensitivity analysis of all of the data over the full temperature range from 248 to 293 K, we can conclude that the evaporation coefficient of water, and thus the mass accommodation coefficient, is greater than, or equal to, 0.5.

  5. Initial Measurement of the Vapor Pressures of Simple Refractory Materials: Cu and Fe

    NASA Technical Reports Server (NTRS)

    Nuth, Joseph A., III; Ferguson, Frank T.; Johnson, Natasha; Martinez, Daniel

    2003-01-01

    It has become increasingly clear over the past decade that high temperature processes played important roles in the Primitive Solar Nebula. Unfortunately, basic data, such as the vapor pressures of iron or SiO have not been measured over the appropriate temperature range (near T approximately equal to 2000K), but must be extrapolated from lower temperature measurements often made more than 50 years ago. The extrapolation of the available data to higher temperatures can be quite complex and can depend on other factors such as the oxygen fugacity or the presence of hydrogen gas. Moreover, modern technology has made possible more accurate measurements of such quantities over a wider temperature range. We recently acquired a commercial Thermo-Cahn Thermogravimetric system capable of vacuum operation to 1700 C and measurement of mass change with microgram accuracy in a 100g sample or smaller. In this paper, we will report our progress in learning to make vapor pressure measurements using this system.

  6. Network model investigation of interfacial area, capillary pressure and saturation relationships in granular porous media

    NASA Astrophysics Data System (ADS)

    Joekar-Niasar, V.; Prodanovi?, M.; Wildenschild, D.; Hassanizadeh, S. M.

    2010-06-01

    We have developed a new approach for generating pore throat cross sections of various shapes based on distributions of shape factors and radii of inscribed circles. These distributions are obtained from analysis of grains packing. General formulas for calculating geometrical properties and entry capillary pressure for given shape factor and inscribed circle radius are developed. These relationships are employed in a pore network, which has a number of special features. In particular, it is highly flexible in terms of location of pore bodies, variable coordination number, as well as variable cross-sectional shapes. The pore network model is employed for simulating the equilibrium distribution of two fluids in a granular porous medium, under both drainage and imbibition conditions. The pore network model is verified by comparing simulation results with experimental data of quasi-static drainage and imbibition experiments in a glass bead medium. The pore-level topology and geometrical description of pore bodies and pore throats, essential for building the network, are rigorously extracted from experimental data using image analysis (3DMA-Rock software). Calculated capillary pressure-saturation (Pc - Sw) and specific interfacial area-saturation (anw - Sw) curves show very good agreement with measured ones, for both drainage and imbibition. We show that the shape factor can significantly influence the form of macroscopic Pc - Sw and anw - Sw curves, if the length and volumes associated to the pore throats are considerable. Furthermore, using continuous generation of shape factor distribution, the model can be validated against the grain size distribution. After validating the model against experiments, in addition to primary and main curves, we simulate many scanning curves to generate Pc - Sw - anw surfaces for drainage and imbibition, separately. Results show that these two surfaces lie very close to each other, and the average normalized difference is small, in the range of simulations uncertainty. Our results illustrate that Pc - Sw - anw surfaces show very little hysteresis and, therefore, specific interfacial area can be considered as an essential variable for reducing or eliminating the hysteresis observed in Pc - Sw curves.

  7. Characterization of High-Pressure Vapor-Phase Silicon Etching for MEMS Processing

    Microsoft Academic Search

    Clayton Easter; Chad B. O'Neal

    2009-01-01

    Typical release for structures in microelectromechanical systems (MEMS) devices requires the use of sacrificial layers and wet etchants. As an alternative, bulk Si can be utilized for nonsilicon MEMS or structures as the sacrificial material when exposed to vapor-phase XeF2 . This paper presents the results of using relatively high pressures (> 3.0 torr) for the purpose of MEMS processing,

  8. Elimination of phosphorus vaporizing from molten silicon at finite reduced pressure

    Microsoft Academic Search

    Song-sheng ZHENG; Jafar SAFARIAN; Seongho SEOK; Sungwook KIM; Tangstad MERETE; Xue-tao LUO

    2011-01-01

    Elimination of phosphorus vaporizing from silicon was investigated. Si-P alloy made from electronic grade silicon was used. All the samples were analyzed by GD-MS. Theory calculation determines that phosphorus evaporates from molten silicon as gas species P and P2 at a finite reduced pressure. The experimental results show that phosphorus mass fraction can be decreased from 0.046% (460ppmw) to around

  9. Fractional factorial design study of a pressure swing adsorption-solvent vapor recovery process

    Microsoft Academic Search

    Yujun Liu; James A. Ritter

    1997-01-01

    A two-level fractional factorial study was performed by computer simulation on the periodic state process performance of a pressure swing adsorption-solvent vapor recovery process (PSA-SVR). The goal was to investigate factor (parameter) interaction effects on the process performance, i.e., interaction effects that cannot be ascertained from the conventional “one-at-a-time” approach. Effects of seven factors, i.e., the purge to feed ratio,

  10. Periodic State Heat Effects in Pressure Swing Adsorption-Solvent Vapor Recovery

    Microsoft Academic Search

    Yujun Liu; James A. Ritter

    1998-01-01

    Heat effects in the pressure swing adsorption (PSA)-n-butane vapor recovery process were investigated at the periodic state by computer simulation. The PSA process utilized a two-bed, four-step, vacuum swing cycle and BAX activated carbon as the adsorbent. The heat effects were manifested by varying the heat transfer coefficient (h) from isothermal to adiabatic, while simultaneously varying the adsorbed phase heat

  11. Pressure drop in fully developed, duct flow of dispersed liquid-vapor mixture at zero gravity

    Microsoft Academic Search

    K. R. Sridhar; B. T. Chao; S. L. Soo

    1990-01-01

    The dynamics of steady, fully developed dispersed liquid-vapor flow in a straight duct at 0-g is simulated by flowing water containing n-butyl benzoate droplets. Water and benzoate are immiscible and have identical density at room temperature. The theoretical basis of the simulation is given. Experiments showed that, for a fixed combined flow rate of water and benzoate, the frictional pressure

  12. Composite chemical vapor deposition diamond anvils for high-pressure\\/high-temperature experiments

    Microsoft Academic Search

    Chang-Sheng Zha; Szczesny Krasnicki; Yu-Fei Meng; Chih-Shiue Yan; Joseph Lai; Qi Liang; Ho-Kwang Mao; Russell J. Hemley

    2009-01-01

    Composite diamond anvils have been developed for high-pressure\\/high-temperature measurements of diamond anvil cells. The anvils are fabricated using single-crystal chemical vapor deposition (CVD) from previously used and\\/or slightly damaged anvils made of natural or synthetic diamond. These composite anvils can be fabricated to possess optical characteristics at least comparable to conventional diamond anvils, whereas the single-crystal CVD portion is more

  13. Some possible filler alloys with low vapor pressures for refractory-metal brazing

    NASA Technical Reports Server (NTRS)

    Morris, J. F.

    1973-01-01

    A compilation of eutectics and melting-point minima for binary combinations of metals having vapor pressures below 10 to the minus 10th power torr at 1500 degrees K and .00005 torr at 2000 degree K is presented. These compositions and others near them on their phase diagrams are potential special brazing fillers for refractory metals. Some possible problems and advantages for fusion bonds of such mixtures are indicated. Evaluations of brazing fillers containing refractory metals are reported.

  14. AIR PURIFICATION AND VAPOR RECOVERY BY PRESSURE SWING ADSORPTION: A COMPARISON OF SILICALITE AND ACTIVATED CARBON

    Microsoft Academic Search

    JAMES A. RITTER; RALPH T. YANG

    1991-01-01

    Air purification and vapor recovery by pressure swing adsorption (PSA) were experimentally investigated using the silicalite-DMMP-air system. The results from several cyclic steady-state PSA runs were compared at constant throughput with those from a previous study on the BPL activated carbon-DMMP-air system. The performance of BPL activated carbon was superior to that of silicalite because it demonstrated complete cleanup of

  15. High pressure metal vapor discharge lamp with radioactive material impregrated in ceramic

    SciTech Connect

    Iroue, A.; Ishigami, T.; Kamei, T.; Kamiya, A.; Kanoh, T.; Kohno, A.; Sasaki, H.

    1984-04-24

    A high pressure metal vapor discharge lamp including an arc tube having opposed ends at which are provided respective main electrodes and a fill including mercury and a starting gas, a radioactive source material including a radioactive substance having a half-life less than 1X10/sup 4/ years sealed in the arc tube, an outer tube enclosing the arc tube and a circuit for starting the arc tube.

  16. Vapor–liquid equilibria of carbon dioxide with isopropyl acetate, diethyl carbonate and ethyl butyrate at elevated pressures

    Microsoft Academic Search

    Chen-His Cheng; Yan-Ping Chen

    2005-01-01

    Vapor–liquid equilibria for carbon dioxide with three esters of isopropyl acetate, diethyl carbonate and ethyl butyrate were measured in this study at 308.45, 313.45 and 318.55K and at elevated pressures up to 8.9MPa. A static type phase equilibrium apparatus with visual sapphire windows was used in the experimental measurements. Equilibrium compositions in both vapor and liquid phases and the vapor–liquid

  17. Methods of Measuring Vapor Pressures of Lubricants With Their Additives Using TGA and/or Microbalances

    NASA Technical Reports Server (NTRS)

    Scialdone, John J.; Miller, Michael K.; Montoya, Alex F.

    1996-01-01

    The life of a space system may be critically dependent on the lubrication of some of its moving parts. The vapor pressure, the quantity of the available lubricant, the temperature and the exhaust venting conductance passage are important considerations in the selection and application of a lubricant. In addition, the oil additives employed to provide certain properties of low friction, surface tension, antioxidant and load bearing characteristics, are also very important and need to be known with regard to their amounts and vapor pressures. This paper reports on the measurements and analyses carried out to obtain those parameters for two often employed lubricants, the Apiezon(TM)-C and the Krytox(TM) AB. The measurements were made employing an electronic microbalance and a thermogravimetric analyzer (TGA) modified to operate in a vacuum. The results have been compared to other data on these oils when available. The identification of the mass fractions of the additives in the oil and their vapor pressures as a function of the temperature were carried out. These may be used to estimate the lubricant life given its quantity and the system vent exhaust conductance. It was found that the Apiezon(TM)-C has three main components with different rates of evaporation while the Krytox(TM) did not indicate any measurable additive.

  18. Pressure drop in fully developed, duct flow of dispersed liquid-vapor mixture at zero gravity

    NASA Astrophysics Data System (ADS)

    Sridhar, K. R.; Chao, B. T.; Soo, S. L.

    1990-09-01

    The dynamics of steady, fully developed dispersed liquid-vapor flow in a straight duct at 0-g is simulated by flowing water containing n-butyl benzoate droplets. Water and benzoate are immiscible and have identical density at room temperature. The theoretical basis of the simulation is given. Experiments showed that, for a fixed combined flow rate of water and benzoate, the frictional pressure drop is unaffected by large changes in the volume fraction of benzoate drops and their size distribution. Measured power spectra of the static wall pressure fluctuations induced by the turbulent water-benzoate flow also revealed that their dynamics is essentially unaltered by the presence of the droplets. These experimental findings, together with the theoretical analysis, led to the conclusion that the pressure drop in fully developed, dispersed liquid-vapor flow in straight ducts of constant cross section at 0-g is identical to that due to liquid flowing alone at the same total volumetric flow rate of the liquid-vapor mixture and, therefore, can be readily determined.

  19. Pressure drop in fully developed, duct flow of dispersed liquid-vapor mixture at zero gravity

    NASA Technical Reports Server (NTRS)

    Sridhar, K. R.; Chao, B. T.; Soo, S. L.

    1990-01-01

    The dynamics of steady, fully developed dispersed liquid-vapor flow in a straight duct at 0-g is simulated by flowing water containing n-butyl benzoate droplets. Water and benzoate are immiscible and have identical density at room temperature. The theoretical basis of the simulation is given. Experiments showed that, for a fixed combined flow rate of water and benzoate, the frictional pressure drop is unaffected by large changes in the volume fraction of benzoate drops and their size distribution. Measured power spectra of the static wall pressure fluctuations induced by the turbulent water-benzoate flow also revealed that their dynamics is essentially unaltered by the presence of the droplets. These experimental findings, together with the theoretical analysis, led to the conclusion that the pressure drop in fully developed, dispersed liquid-vapor flow in straight ducts of constant cross section at 0-g is identical to that due to liquid flowing alone at the same total volumetric flow rate of the liquid-vapor mixture and, therefore, can be readily determined.

  20. In-reactor oxidation of zircaloy-4 under low water vapor pressures

    SciTech Connect

    Walter G. Luscher; David J. Senor; Keven K. Clayton; Glen R. Longhurst

    2015-01-01

    Complementary in- and ex-reactor oxidation tests have been performed to evaluate the oxidation and hydrogen absorption performance of Zircaloy-4 (Zr-4) under relatively low partial pressures (300 and 1000 Pa) of water vapor at specified test temperatures (330 and 370 C). Data from these tests will be used to support the fabrication of components intended for isotope-producing targets and provide information regarding the temperature and pressure dependence of oxidation and hydrogen absorption of Zr- 4 over the specified range of test conditions. Comparisons between in- and ex-reactor test results were performed to evaluate the influence of irradiation.

  1. In-reactor oxidation of zircaloy-4 under low water vapor pressures

    NASA Astrophysics Data System (ADS)

    Luscher, Walter G.; Senor, David J.; Clayton, Kevin K.; Longhurst, Glen R.

    2015-01-01

    Complementary in- and ex-reactor oxidation tests have been performed to evaluate the oxidation and hydrogen absorption performance of Zircaloy-4 (Zr-4) under relatively low partial pressures (300 and 1000 Pa) of water vapor at specified test temperatures (330 and 370 °C). Data from these tests will be used to support the fabrication of components intended for isotope-producing targets and provide information regarding the temperature and pressure dependence of oxidation and hydrogen absorption of Zr-4 over the specified range of test conditions. Comparisons between in- and ex-reactor test results were performed to evaluate the influence of irradiation.

  2. A new formula for saturated water steam pressure within the temperature range -25 to 220°C

    NASA Astrophysics Data System (ADS)

    Romanov, N. P.

    2009-12-01

    Instead of approximation formula ln( E( t)/ E(0)) = [( a - bt) t/( c + T)] commonly used at present for representing dependence of pressure of saturated streams of liquid water E upon temperature we suggested new approximation formula of greater accuracy in the form ln( E( t)/ E(0)) = [( A - Bt + Ct 2) t/ T], where t and T are temperature in °C and K respectively. For this formula with parameters A = 19.846, B = 8.97 × 10-3, C = 1.248 × 10-5 and E(0) = 6.1121 GPa with ITS-90 temperature scale and for temperature range from 0°C to 110°C relative difference of approximation applying six parameter formula by W. Wagner and A. Pruß 2002, developed for positive temperatures, is less than 0.005%, that is approximately 15 times less than accuracy obtained with the firs formula. Increase of temperature range results in relative difference increasing, but for even temperature range from 0°C to 220°C it does not higher than 0.1%. For negative temperatures relative difference between our formula and a formula of D. M. Murphy and T. Koop, 2005, is less than 0.1% for temperatures higher than -25°C. This paper also presents values of coefficients for approximation of Goff and Grach formula recommended by IMO. The procedure of finding dew point T d for known water steam pressure e n based on our formula adds up to solving an algebraic equation of a third degree, which coefficients are presented in this paper. For simplifying this procedure this paper also includes approximation ratio applying a coefficient A noted above, in the form T d ( e n ) = frac{{AT_0 }} {{A - \\varepsilon }} + 0.0866?2 + 0.0116?10/3, where ? = ln( e n / E( T 0)). Error of dew point recovery in this ratio is less than 0.005 K within the range from 0 to 50°C.

  3. Theoretical and experimental studies on freezing point depression and vapor pressure deficit as methods to measure osmotic pressure of aqueous polyethylene glycol and bovine serum albumin solutions

    Microsoft Academic Search

    Keitaro Kiyosawa

    2003-01-01

    For survival in adverse environments where there is drought, high salt concentration or low temperature, some plants seem to be able to synthesize biochemical compounds, including proteins, in response to changes in water activity or osmotic pressure. Measurement of the water activity or osmotic pressure of simple aqueous solutions has been based on freezing point depression or vapor pressure deficit.

  4. Investigations of analyte-specific response saturation and dynamic range limitations in atmospheric pressure ionization mass spectrometry.

    PubMed

    Alfaro, Clint M; Uwakweh, Agbo-Oma; Todd, Daniel A; Ehrmann, Brandie M; Cech, Nadja B

    2014-11-01

    With this study, we investigated why some small molecules demonstrate narrow dynamic ranges in electrospray ionization-mass spectrometry (ESI-MS) and sought to establish conditions under which the dynamic range could be extended. Working curves were compared for eight flavonoids and two alkaloids using ESI, atmospheric pressure chemical ionization (APCI), and heated electrospray ionization (HESI) sources. Relative to reserpine, the flavonoids exhibited narrower linear dynamic ranges with ESI-MS, primarily due to saturation in response at relatively low concentrations. Saturation was overcome by switching from ESI to APCI, and our experiments utilizing a combination HESI/APCI source suggest that this is due in part to the ability of APCI to protonate neutral quercetin molecules in the gas phase. Thermodynamic equilibrium calculations indicate that quercetin should be fully protonated in solution, and thus, it appears that some factor inherent in the ESI process favors the formation of neutral quercetin at high concentration. The flavonoid saturation concentration was increased with HESI as compared to ESI, suggesting that inefficient transfer of ions to the gas phase can also contribute to saturation in ESI-MS response. In support of this conclusion, increasing auxiliary gas pressure or switching to a more volatile spray solvent also increased the ESI dynamic range. Among the sources investigated herein, the HESI source achieved the best analytical performance (widest linear dynamic range, lowest LOD), but the APCI source was less subject to saturation in response at high concentration. PMID:25268329

  5. Status of the CNRS-LCSR program on high pressure droplet vaporization and burning

    NASA Technical Reports Server (NTRS)

    Chauveau, Christian; Goekalp, Iskender

    1993-01-01

    Depending on the surrounding flow and thermodynamic conditions, a single droplet may experience several gasification regimes, ranging from the envelope flame regime to pure vaporization. In practical situations, such as rocket propulsion or diesel combustion, the size distribution of droplets is, at best, bimodal, so that the possibility exists for the simultaneous presence of various regimes. For example, very small droplets are transported by the gas phase with zero relative velocity. This picture validates then the spherical symmetry hypothesis applied to the droplet and to the diffusion flame enveloping it. On the other hand, for larger droplets, a relative velocity exists due to drag forces. The most important influence of forced convection on droplet burning is the possibility to extinguish globally the envelope flame, or to establish a flame stabilized in the wake region. The burning rates of these regimes differ strongly. The characteristic time of droplet gasification is also influenced by the surrounding pressure and temperature. A parametric investigation of single droplet burning regimes is then helpful in providing the necessary physical ideas for sub-grid models used in spray combustion numerical prediction codes. The CNRS-LCSR experimental program on droplet vaporization and burning deals with these various regimes: stagnant and convective monocomponent droplet burning convective mono and bicomponent droplet vaporization; high temperature convective mono and biocomponent droplet vaporization; burning regimes of hydrazine and hydroxyl-ammonium-nitrate based monopropellant droplets and the vaporization regimes of liquid oxygen droplets. Studies on interacting droplets and on liquid aluminum droplets will start in the near future. The influence of high pressure is a common feature of all these studies. This paper summarizes the status of the CNRS-LCSR program on the effects of high pressure on monocomponent single droplet burning and vaporization, and some recent results obtained under normal and reduced gravity conditions with suspended droplets are presented. In the work described here, parabolic flights of an aircraft is used to create a reduced gravity environment of the order of 10(exp -2) g.

  6. Solvent Vapor Recovery by Pressure Swing Adsorption. II. Experimental Periodic Performance of the Butane-Activated Carbon System

    Microsoft Academic Search

    Yujun Liu; Charles E. Holland; James A. Ritter

    1998-01-01

    An experimental investigation was carried out for the separation and recovery of butane vapor (10 to 40 vol%) from nitrogen using Westvaco BAX activated carbon and a unique pressure swing adsorption (PSA)-solvent vapor recovery (SVR) system. The effects of six important process and operating parameters on the periodic process performance were obtained, i.e., the purge-to-feed ratio, purge pressure, volumetric feed

  7. Rapid measurement of boiling points and vapor pressure of binary mixtures of short-chain triglycerides by TGA method

    Microsoft Academic Search

    J. W Goodrum; D. P Geller; S. A Lee

    1998-01-01

    Thermogravimetric analysis (TGA), has been used to rapidly obtain data on the temperature dependence of vapor pressure (760, down to 20mmHg) and the boiling points for simple binary mixtures of tributyrin (C4:0), tricaproin (C6:0) and\\/or tricaprylin (C8:0). Vapor-pressure measurements were taken for binary mixtures of the aforementioned compounds as a function of mole fraction. Additional measurements of methyl esters of

  8. Measurements of the vapor pressures of difluoromethane, 1-chloro-1,2,2,2-tetrafluoroethane, and pentafluoroethane

    Microsoft Academic Search

    L. A. Weber; A. M. Silva

    1994-01-01

    Information about vapor pressures is important initially to qualify potential candidates as working fluids in refrigeration machinery. Later, it is also very useful in calculating the thermodynamic properties necessary for the design of that machinery. The authors present new measurements of the vapor pressures of difluoromethane (R32) from 235 to 265 K, of 1-chloro-1, 2, 2, 2-tetrafluoroethane (R124) from 220

  9. Dynamic hydrocarbon separation in high-temperature, high-pressure, liquid n-alkane water vapor systems by steam distillation

    E-print Network

    Vlierboom, Casper-Maarten

    1987-01-01

    DYNAMIC HYDROCARBON SEPARA1'ION IN HIGH-TEMPERATURE, HIGH-PRESSURE, LIQUID N-ALKANE ? WATER ? VAPOR SYSTEMS BY STEAM DISTILLATION A Thesis by CASPER-MAARTEN VLIERBOOM Submitted to the Graduate College of Texas AGM University in partial... fulfillment of the requirements for the degree of MASTER OF SCIENCE December 1987 Major Subject: Petroleum Engineering DYNAMIC HYDROCARBON SEPARATION IN HIGH TEMPERATURE HIGH PRESSURE, LIQUID N-ALKANE ? WATER ? VAPOR SYSTEMS BY STEAM DISTILLATION A...

  10. Border control! Capillary pressure / saturation relationships in a diphasic flow in a random medium: Influence of the boundary conditions

    NASA Astrophysics Data System (ADS)

    Fiorentino, Eve-Agnès; Toussaint, Renaud; Moura, Marcel; Jankov, Mihailo; Schäfer, Gerhard; Jørgen Måløy, Knut

    2013-04-01

    Solving problems involving biphasic flows in porous media, at a scale larger than the pore one, normally requires the use of relationships between pressure and saturation. These allow the closure of generalized Darcy flow models for two phases, commonly used in hydrology or large scale problems of diphasic flow in porous media. There are mathematical models which approximate experimental records with curve-fitting equations. The two most common models are the Brooks-Corey and van Genüchten ones, they are used to complete a system of generalized Darcy equations. The purpose of the current study is the influence of the boundary conditions on the relationship between pressure and saturation. We perform numerical simulations of drainage experiments. Water is the wetting fluid and air is the non wetting fluid. The results highlight the fact that a filter which allows only water to flow at the exit face of the system modifies both the shape of the curve and the value of the residual saturation. The pressure of the models that are commonly used does not match with the pressure of real flows since there is no filter to cross, to flow from an elementary volume to another. Experiments performed in transparent Hele-Shaw cells exhibit the same features, showing the influence of the semi permeable boundary conditions on the pressure-saturation measures obtained. This effect corresponding to the formation of localized plugging clusters at the boundaries, is obtained in slow flow conditions, and is independent of any dynamic fingering, also known to affect such relations (1,2,3). Modeling flows in open media thus would require to use the central part of the curves pressure saturation where the effect of the boundaries is the least important, or to modify properly these relationships to extract the behavior unaffected by boundaries. References: (1) Two-phase flow: structure, upscaling, and consequences for macroscopic transport properties Renaud Toussaint ; Knut Jørgen Måløy; Yves Méheust; Grunde Løvoll; Mihailo Jankov; Gerhard Schäfer; Jean Schmittbuhl Vadose Zone Journal, 2012, 11 (3), pp. vzj2011.0123 (2) Løvoll, G., M. Jankov, K.J. Måløy, R. Toussaint, J. Schmittbuhl, G. Schaefer and Y. Méheust, Influence of viscous fingering on dynamic saturation-pressure curves in porous media, Transport in Porous Media, 86, 1, 305-324, 2010 (3) Toussaint, R., G. Løvoll, Y. Méheust, K.J. Måløy and J. Schmittbuhl, Influence of pore-scale disorder on viscous fingering during drainage, Europhys. Lett., 71, 583 (2005).

  11. Pressure intelligent control strategy of Waste heat recovery system of converter vapors

    NASA Astrophysics Data System (ADS)

    Feng, Xugang; Wu, Zhiwei; Zhang, Jiayan; Qian, Hong

    2013-01-01

    The converter gas evaporative cooling system is mainly used for absorbing heat in the high temperature exhaust gas which produced by the oxygen blowing reaction. Vaporization cooling steam pressure control system of converter is a nonlinear, time-varying, lagging behind, close coupling of multivariable control object. This article based on the analysis of converter operation characteristics of evaporation cooling system, of vaporization in a production run of pipe pressure variation and disturbance factors.For the dynamic characteristics of the controlled objects,we have improved the conventional PID control scheme.In Oxygen blowing process, we make intelligent control by using fuzzy-PID cascade control method and adjusting the Lance,that it can realize the optimization of the boiler steam pressure control.By design simulation, results show that the design has a good control not only ensures drum steam pressure in the context of security, enabling efficient conversion of waste heat.And the converter of 1800 flue gas through pipes and cool and dust removal also can be cooled to about 800. Therefore the converter haze evaporative cooling system has achieved to the converter haze temperature decrease effect and enhanced to the coal gas returns-ratio.

  12. Disjoining pressure and capillarity in the constrained vapor bubble heat transfer system.

    PubMed

    Chatterjee, Arya; Plawsky, Joel L; Wayner, Peter C

    2011-10-14

    Using the disjoining pressure concept in a seminal paper, Derjaguin, Nerpin and Churaev demonstrated that isothermal liquid flow in a very thin film on the walls of a capillary tube enhances the rate of evaporation of moisture by several times. The objective of this review is to present the evolution of the use of Churaev's seminal research in the development of the Constrained Vapor Bubble (CVB) heat transfer system. In this non-isothermal "wickless heat pipe", liquid and vapor flow results from gradients in the intermolecular force field, which depend on the disjoining pressure, capillarity and temperature. A Kelvin-Clapeyron model allowed the use of the disjoining pressure to be expanded to describe non-isothermal heat, mass and momentum transport processes. The intermolecular force field described by the convenient disjoining pressure model is the boundary condition for "suction" and stability at the leading edge of the evaporating curved flow field. As demonstrated by the non-isothermal results, applications that depend on the characteristics of the evaporating meniscus are legion. PMID:21470588

  13. Effect of substrate roughness on D spacing supports theoretical resolution of vapor pressure paradox.

    PubMed Central

    Tristram-Nagle, S; Petrache, H I; Suter, R M; Nagle, J F

    1998-01-01

    The lamellar D spacing has been measured for oriented stacks of lecithin bilayers prepared on a variety of solid substrates and hydrated from the vapor. We find that, when the bilayers are in the L(alpha) phase near 100% relative humidity, the D spacing is consistently larger when the substrate is rougher than when it is smooth. The differences become smaller as the relative humidity is decreased to 80% and negligible differences are seen in the L(beta') phase. Our interpretation is that rough substrates frustrate the bilayer stack energetically, thereby increasing the fluctuations, the fluctuational repulsive forces, and the water spacing compared with stacks on smooth surfaces. This interpretation is consistent with and provides experimental support for a recently proposed theoretical resolution of the vapor pressure paradox. PMID:9512038

  14. Parametric study of a commercial pressure swing adsorption-solvent vapor recovery process

    SciTech Connect

    Liu, Y.; Ritter, J.A. [Univ. of South Carolina, Columbia, SC (United States)

    1996-12-31

    The performance of a pressure swing adsorption (PSA) - solvent vapor recovery (SVR) process was examined at the periodic state by computer simulation. A four step, vacuum swing cycle was employed for the removal of benzene vapor from nitrogen using activated charcoal. The feed concentration, feed flow rate, cycle time, adsorption step time, and bed length to diameter ratio were investigated to ascertain their effects on the process performance. The trends showed that the process performance was affected significantly by all of these parameters, and that the non-idealities included in the rigorous model, in most cases, had a marked effect on the process performance, beyond that which could be explained by an idealized, equilibrium PSA model. 13 refs., 5 figs., 2 tabs.

  15. Partial Pressures of In-Se from Optical Absorbance of the Vapor

    NASA Technical Reports Server (NTRS)

    Brebrick, R. F.; Su, Ching-Hua; Curreri, Peter A. (Technical Monitor)

    2001-01-01

    The optical absorbance of the vapor phase over various In-Se compositions between 33.3 and 61 atomic percent and 673 and 1418K has been measured and used to obtain the partial pressures of Se2(g) and In2Se(g). The results are in agreement with silica Bourdon gage measurements for compositions between 50 and 61 atomic percent but significantly higher than those from Knudsen cell and simultaneous Torsion-Knudsen cell measurements. The sequiselenide is found to sublime incongruently. Congruent vaporization occurs for the liquid above 1000 K between 50.08 and 56 at. percent Se. The Gibbs energy of formation of the liquid from its pure liquid elements between 1000 and 1300K is essentially independent of temperature and falls between -36 and -38 kJ per gram atomic weight for 50 and 56 percent Se at 1200 and 1300K.

  16. Vapor pressure isotope fractionation effects in planetary atmospheres: application to deuterium

    E-print Network

    Thierry Fouchet; Emmanuel Lellouch

    1999-11-15

    The impact of the vapor pressure difference between deuterated and nondeuterated condensing molecules in planetary atmospheres is quantitatively assessed. This difference results in a loss of deuterium in the vapor phase above the condensation level. In Titan, Uranus and Neptune, the effect on CH3D is too subtle to alter current D/H ratio determinations. In Mars, the effect can induce a large depletion of HDO, starting about one scale height above the condensation level. Although the current infrared measurements of the D/H ratio appear to be almost unaffected, the intensity of disk-averaged millimetric HDO lines can be modified by about 10%. The effect is much stronger in limb sounding, and can be easily detected from orbiter observations.

  17. Analysis based on the diffusion model for saturation silica gel with water vapor at conservation units steam circuit TPP

    NASA Astrophysics Data System (ADS)

    Goldaev, Sergey; Khushvaktov, Alisher

    2015-01-01

    A quantitative analysis of the diffusion model dehumidifying air in the steam circuit of TPP, with a layer of silica gel. Showed that such an approximation, supplemented the experimental value of the coefficient of free diffusion identified by the developed method gives reliable values for the concentration of water vapor absorption over time.

  18. Examination of Stability of Boundary Conditions in Water Vapor Transmission Tests

    Microsoft Academic Search

    Marcin Pazera; Mikael Salonvaara

    2009-01-01

    The diffusion of water vapor through construction materials is driven by the gradient of partial water vapor pressure. Traditionally, water vapor transmission tests (WVT), the `dry cup', and the `wet cup' tests have been conducted with 0 to 50% RH, and from 50% to 100% RH, respectively. Often, desiccants, saturated salt solutions or distilled water are used to generate the

  19. Measurements and Correlations of cis-1,3,3,3-Tetrafluoroprop-1-ene (R1234ze(Z)) Saturation Pressure

    NASA Astrophysics Data System (ADS)

    Fedele, Laura; Di Nicola, Giovanni; Brown, J. Steven; Bobbo, Sergio; Zilio, Claudio

    2014-01-01

    cis-1,3,3,3-Tetrafluoroprop-1-ene (R1234ze(Z)) is being investigated as a working fluid possessing a low global warming potential (GWP) for high-temperature heat pumping applications, organic Rankine cycles, and air-conditioning and refrigeration applications, and as a potential solvent, propellant, and foam blowing agent. Its GWP is less than one. The open literature contains a total of 79 vapor-pressure data from three sources and the critical state properties from a single source. The current paper provides 64 vapor-pressure data from two different laboratories over the temperature range from 238.13 K to 372.61 K. These data are regressed using Wagner and extended Antoine vapor-pressure correlations and then compared to the existing open literature data and correlations. The normal-boiling-point temperature and acentric factor for R1234ze(Z) are estimated to be 282.73 K and 0.3257, respectively.

  20. On optimum interstage pressure for two-stage and mechanical-subcooling vapor-compression refrigeration cycles

    SciTech Connect

    Zubair, S.M.; Khan, S.H. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia). Dept. of Mechanical Engineering

    1995-02-01

    The objective of the present study is to demonstrate that the optimum interstage pressure for a two-stage refrigeration system can be approximated by the saturation pressure corresponding to the arithmetic mean of the condensing and evaporating temperatures. It is also shown that the optimum performance of a refrigeration system with mechanical sub-cooling occurred when the subcooler compressor (saturation suction) temperature corresponds to the arithmetic mean of the condensing and evaporating temperatures.

  1. Influence of the helium-pressure on diode-pumped alkali-vapor laser

    NASA Astrophysics Data System (ADS)

    Gao, Fei; Chen, Fei; Xie, Ji-jiang; Zhang, Lai-ming; Li, Dian-jun; Yang, Gui-long; Guo, Jing

    2013-05-01

    Diode-pumped alkali-vapor laser (DPAL) is a kind of laser attracted much attention for its merits, such as high quantum efficiency, excellent beam quality, favorable thermal management, and potential scalability to high power and so on. Based on the rate-equation theory of end-pumped DPAL, the performances of DPAL using Cs-vapor collisionally broadened by helium are simulated and studied. With the increase of helium pressure, the numerical results show that: 1) the absorption line-width increases and the stimulated absorption cross-section decreases contrarily; 2) the threshold pumping power decreases to minimum and then rolls over to increase linearly; 3) the absorption efficiency rises to maximum initially due to enough large stimulated absorption cross-section in the far wings of collisionally broadened D2 transition (absorption transition), and then begins to reduce; 4) an optimal value of helium pressure exists to obtain the highest output power, leading to an optimal optical-optical efficiency. Furthermore, to generate the self-oscillation of laser, a critical value of helium pressure occurs when small-signal gain equals to the threshold gain.

  2. A differential vapor-pressure equipment for investigations of biopolymer interactions.

    PubMed

    Andersen, Kim B; Koga, Yoshikata; Westh, Peter

    2002-01-01

    The design and performance of an equipment for the measurement of vapor pressures over liquid or solid samples is presented. The equilibrium pressure difference, DeltaP, between a sample and a reference of known vapor pressure is recorded as a function of composition and/or temperature. Through the use of high-accuracy capacitance manometers and a leak-tight system of stainless steel pipes, below-sealed valves and metal-gasket fittings, DeltaP can be measured with a resolution of about 0.5 micro bar (0.05 Pa) in some applications. This sensitivity level, along with other features of the equipment, particularly a "gas-phase titration" routine for changing the cell composition, makes it effective for the investigations of several types of biopolymer interactions. These include isothermal studies of net affinities such as the adsorption of water to proteins or membranes, the preferential interaction of biopolymers with the components of a mixed solvent, the partitioning of solutes between a membrane and the aqueous bulk and the weak, specific binding of ligands to macromolecules. Furthermore, a temperature-scanning mode allows real-time elucidation of such interactions at thermally induced conformational changes in biopolymers. Selected examples of these applications are presented and discussed. PMID:11741714

  3. Two-phase heat transfer and pressure drop of LNG during saturated flow boiling in a horizontal tube

    NASA Astrophysics Data System (ADS)

    Chen, Dongsheng; Shi, Yumei

    2013-12-01

    Two-phase heat transfer and pressure drop of LNG (liquefied natural gas) have been measured in a horizontal smooth tube with an inner diameter of 8 mm. The experiments were conducted at inlet pressures from 0.3 to 0.7 MPa with a heat flux of 8-36 kW m-2, and mass flux of 49.2-201.8 kg m-2 s-1. The effect of vapor quality, inlet pressure, heat flux and mass flux on the heat transfer characteristic are discussed. The comparisons of the experimental data with the predicted value by existing correlations are analyzed. Zou et al. (2010) correlation shows the best accuracy with 24.1% RMS deviation among them. Moreover four frictional pressure drop methods are also chosen to compare with the experimental database.

  4. Methodology for Integrated Vapor Pressure, Hygroswelling, and Thermomechanical Stress Modeling of IC Packages

    Microsoft Academic Search

    T. Y. Tee

    \\u000a A comprehensive and integrated approach is established to simulate the package reliability of IC packages with detailed considerations\\u000a of effects of moisture diffusion, heat transfer, thermo-mechanical stress, hygro-mechanical stress, and vapor pressure under\\u000a combined temperature\\/humidity conditions. QFN (quad flat non-lead) and FCBGA (flip chip ball grid array) packages are used\\u000a as test vehicles. The critical plastic materials, i.e., mold compound,

  5. Vapor Pressure of Solid Polybrominated Diphenyl Ethers Determined via Knudsen Effusion Method

    PubMed Central

    Fu, Jinxia; Suuberg, Eric M.

    2013-01-01

    Polybrominated diphenyl ethers (PBDEs) are flame retardants used in a variety of consumer products. The solid vapor pressures of BDE15 and BDE209 were determined by use of the Knudsen effusion method, and the values measured extrapolated to 298.15 K are 3.12×10?3 and 9.02×10?13 Pa, respectively. The enthalpies of sublimation for these compounds have also been estimated by using the Clausius-Clapeyron equation and are 102.0 ± 3.5 and 157.1 ± 3.5 kJ/mol, respectively. Additionally, the melting points and enthalpies of fusion were measured by differential scanning calorimetry. PMID:21766320

  6. The control of purity and stoichiometry of compound semiconductors by high vapor pressure transport

    NASA Technical Reports Server (NTRS)

    Bachmann, Klaus J.; Ito, Kazufumi; Scroggs, Jeffery S.; Tran, Hien T.

    1995-01-01

    In this report we summarize the results of a three year research program on high pressure vapor transport (HPVT) of compound semiconductors. Most of our work focused onto pnictides, in particular ZnGeP2, as a model system. Access to single crystals of well controlled composition of this material is desired for advancing the understanding and control of its point defect chemistry in the contest of remote, real-time sensing of trace impurities, e.g., greenhouse gases, in the atmosphere by ZnGeP2 optical parametric oscillators (OPO's).

  7. Solubility parameter and activity coefficient of HDEHP dimer in select organic diluents by vapor pressure osmometry

    SciTech Connect

    Gray, M.; Nilsson, M. [University of California Irvine, 916 Engineering Tower, UC Irvine, Irvine, CA 92697-2575 (United States); Zalupski, P. [Idaho National Laboratory, 2525 Fremont Avenue, Idaho Falls, ID 83415 (United States)

    2013-07-01

    A thorough understanding of the non-ideal behavior of the chemical components utilized in solvent extraction contributes to the success of any large-scale spent nuclear fuel treatment. To address this, our current work uses vapor pressure osmometry to characterize the non-ideal behavior of the solvent extraction agent di-(2-ethylhexyl) phosphoric acid (HDEHP), a common extractant in proposed separation schemes. Solubility parameters were fit to data on HDEHP at four temperatures using models based on Scatchard Hildebrand regular solution theory with Flory Huggins entropic corrections. The results are comparable but not identical to the activity coefficients from prior slope analysis in the literature. (authors)

  8. Track studies in water vapor using a low-pressure cloud chamber. II. Microdosimetric measurements.

    PubMed

    Stonell, G P; Marshall, M; Simmons, J A

    1993-12-01

    A low-pressure cloud chamber has been adapted to operate with pure water vapor. Photographs were obtained of tracks arising from the passage of ionizing radiation. The sources used were low-energy X rays, 242Cm alpha particles, and low-energy protons. Distributions of lineal energy, radial distances around an ion track, and interdroplet distances were measured and compared with the predictions of Monte Carlo calculations. After allowing for diffusion and the limitations of the geometry of the system, the measured and calculated distributions were found to be in good agreement. PMID:8278576

  9. Deposition and properties of low-pressure chemical-vapor deposited polycrystalline silicon-germanium films

    Microsoft Academic Search

    Tsu-Jae King; Krishna C. Saraswat

    1994-01-01

    The deposition of undoped polycrystalline silicon-germanium (poly-Si(1-x)Ge(x)) alloy films onto SiO2 by the pyrolysis of SiH4 and GeH4 in a low-pressure chemical vapor deposition system is described. The deposited films are compatible with standard wet-cleaning baths, and their formation and patterning are very controllable processes; therefore, their application should not introduce significant process complexity into silicon-based technologies. Depending upon their

  10. Preliminary results for the 5-20 cm wavelength opacity of ammonia pressure broadened by water vapor under jovian conditions

    NASA Astrophysics Data System (ADS)

    Devaraj, K.; Duong, D.; Steffes, P.

    2011-10-01

    At least one laboratory measurement study indicates that water vapor can efficiently broaden the 572 GHz rotational transition of ammonia [1], and this could be true for the inversion transitions of ammonia as well. Water vapor is the fourth most abundant constituent deep in the atmospheres of the jovian planets after hydrogen, helium, and methane [2]. While the broadening effects of the first three constituents on the ammonia absorption spectrum are now well characterized, it is critical to investigate any possible pressure broadening effects of water vapor on the ammonia absorption spectrum. Experimental investigation of the pressure broadening of the inversion lines of ammonia by water vapor in the microwave region is currently being performed. Over 500 measurements of the microwave properties of ammonia broadened by water vapor in a hydrogen/helium atmosphere have been conducted at pressures up to 100 bars and temperatures in the 375- 500 K range. On the basis of the data obtained in this work, an empirical estimation of the broadening of ammonia by water vapor has been obtained. These measurements will directly aid in the accurate interpretation of the observed microwave emission spectra of the jovian planets, and also improve retrievals of the atmospheric abundance of water vapor at Jupiter from the Juno microwave radiometer (MWR) measurements.

  11. Properties of refractories after exposure to high pressure gases: III—Effect of percent saturation

    Microsoft Academic Search

    A. Fakhr; D. E. Day

    1980-01-01

    The dimensional stability, density, porosity and flexural strength of several cement and phosphatebonded refractories were\\u000a determined before and after exposure to steam and CO containing atmospheres at ?0, 13.5, 30.5, 32.5, 85 and 100 pct saturation.\\u000a The flexural strength and compounds present in a neat, high alumina cement were also determined as a function of the percent\\u000a saturation of pure

  12. Vapors and Droplets Mixture Deposition of Metallic Coatings by Very Low Pressure Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Vautherin, B.; Planche, M.-P.; Bolot, R.; Quet, A.; Bianchi, L.; Montavon, G.

    2014-04-01

    In recent years, the very low pressure plasma-spraying (VLPPS) process has been intensely developed and implemented to manufacture thin, dense and finely structured ceramic coatings for various applications, such as Y2O3 for diffusion barriers, among other examples. This paper aims at presenting developments carried out on metallic coatings. Aluminum was chosen as a demonstrative material due to its "moderate" vaporization enthalpy (i.e., 38.23 KJ cm-3) compared to the one of copper (i.e., 55.33 KJ cm-3), cobalt (i.e., 75.03 KJ cm-3), or even tantalum (i.e., 87.18 KJ cm-3). The objective of this work is primarily to better understand the behavior of a solid precursor injected into the plasma jet leading to the formation of vapors and to better control the factors affecting the coating structure. Nearly dense aluminum coatings were successfully deposited by VLPPS at 100 Pa with an intermediate power plasma torch (i.e., Sulzer Metco F4 type gun with maximum power of 45 kW). Optical emission spectroscopy (OES) was implemented to study and analyze the vapor behavior into the plasma jet. Simplified CFD modeling allowed better understanding of some of the thermo-physical mechanisms. The effect of powder-size distribution, substrate temperature and spray distance were studied. The phase composition and microstructural features of the coatings were characterized by XRD and SEM. Moreover, Vickers microhardness measurements were implemented.

  13. Vapor pressures and heats of vaporization of primary coal tars. Quarterly technical progress report, 1 October 1993--31 December 1993

    SciTech Connect

    Suuberg, E.M.

    1993-12-31

    The vapor pressure correlations that exist at present for coal tars are very crude and they are not considered reliable to even an order of magnitude when applied to tars. Sophisticated general correlative approaches are slowly being developed, based upon group contribution methods, or based upon some key functional features of the molecules. These are as yet difficult to apply to coal tars. The detailed group contribution methods, in which fairly precise structural information is needed, do not lend themselves well for application to very complex, poorly characterized coal tars. The methods based upon more global types of characterizations have not yet dealt much with the question of oxygenated functional groups. In short, only very limited correlations exist, and these are not considered reliable to even an order of magnitude when applied to tars. The present project seeks to address this important gap in the near term by direct measurement of vapor pressures of coal tar fractions, by application of well-established techniques and modifications thereof. The principal objectives of the program are to: (1) obtain data on the vapor pressures and heats of vaporization of tars from a range of ranks of coal, (2) develop correlations based on a minimum set of conveniently measurable characteristics of the tars, (3) develop equipment that would allow performing such measurements in a reliable, straightforward fashion.

  14. Vapor pressures and heats of vaporization of primary coal tars. Quarterly technical progress report, 1 July 1993--30 September 1993

    SciTech Connect

    Suuberg, E.M.; Oja, V.; Lilly, W.D.

    1993-12-31

    There is significant current interest in general area of coal pyrolysis, particularly with respect to comprehensive models of this complicated phenomenon. This interest derives from the central role of pyrolysis in all thermally driven coal conversion processes -- gasification, combustion, liquefaction, mild gasification, or thermal benefication. There remain several key data needs in these application areas. Among them is a need for more reliable correlation for prediction of vapor pressure of heavy, primary coal tars. Such information is important in design of all coal conversion processes, in which the volatility of tarry products is of major concern. Only very limited correlations exist, and these are not considered reliable to even an order of magnitude when applied to tars. The present project seeks to address this important gap in the near term by direct measurement of vapor pressures of coal tar fractions, by application of well-established techniques and modifications thereof. The principal objectives of the program are to: (1) obtain data on the vapor pressures and heats of vaporization of tars from a range of ranks of coal, (2) develop correlations based on a minimum set of conveniently measurable characteristics of the tars, (3) develop equipment that would allow performing such measurements in a reliable, straightforward fashion. Results of the literature survey are compiled. The experimental tasks have been concerned with setup and calibration.

  15. Measurements of the vapor pressures of difluoromethane, 1-chloro-1,2,2,2-tetrafluoroethane, and pentafluoroethane

    SciTech Connect

    Weber, L.A.; Silva, A.M. (National Inst. of Standards and Technology, Gaithersburg, MD (United States). Chemical Science and Technology Lab.)

    1994-10-01

    Information about vapor pressures is important initially to qualify potential candidates as working fluids in refrigeration machinery. Later, it is also very useful in calculating the thermodynamic properties necessary for the design of that machinery. The authors present new measurements of the vapor pressures of difluoromethane (R32) from 235 to 265 K, of 1-chloro-1, 2, 2, 2-tetrafluoroethane (R124) from 220 to 286 K, and of pentafluoroethane (R125) from 218 to 286 K. Measurements were made in two ebulliometers, one of glass and one of metal. Overall, pressures ranged from 13 to about 950 kPa. The authors also present vapor pressures of R125, calculated via thermodynamic relationships, for temperature down to 170 K (2.3 kPa). They study the azeotropic mixture of R125 with chloropentafluoroethane (R115), and they correct the data for a small R115 impurity.

  16. Atmospheric Pressure Plasma Enhanced Chemical Vapor Deposition of Borophosphosilicate Glass Films

    NASA Astrophysics Data System (ADS)

    Yin, Minghui; Zhao, Lingli; Xu, Xiangyu; Wang, Shouguo

    2008-03-01

    Borophosphosilicate glass (BPSG) films have been grown on silicon wafers by plasma enhanced chemical vapor deposition at atmospheric pressure (AP-PECVD). Tetraethoxysilane (TEOS), triethylborate (TEB), and trimethylphosphite (TMPI) were adopted as precursors, and argon and oxygen were respectively used as the carrier and reactive gases to produce stable plasma at atmospheric pressure. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and refractive index and stress measurements were employed to characterize BPSG films. The effects of input radio-frequency (RF) power and precursor (TEB and TMPI) flow rate on deposition rate were studied. Results indicated that the deposition rate of BPSG films increases with increasing input RF power and precursor flow rate. In addition, reactive gaseous species were detected by optical emission spectroscopy to reveal the possible reaction process of BPSG film deposition.

  17. Pressure drop in fully developed, turbulent, liquid-vapor annular flows in zero gravity

    NASA Technical Reports Server (NTRS)

    Sridhar, K. R.; Chao, B. T.; Soo, S. L.

    1992-01-01

    The prediction of frictional pressure drop in fully developed, turbulent, annular liquid-vapor flows in zero gravity using simulation experiments conducted on earth is described. The scheme extends the authors' earlier work on dispersed flows. The simulation experiments used two immiscible liquids of identical density, namely, water and n-butyl benzoate. Because of the lack of rigorous analytical models for turbulent, annular flows, the proposed scheme resorts to existing semiempirical correlations. Results based on two different correlations are presented and compared. Others may be used. It was shown that, for both dispersed and annular flow regimes, the predicted frictional pressure gradients in 0-g are lower than those in 1-g under otherwise identical conditions. The physical basis for this finding is given.

  18. Effect of Hydrogen in Size-Limited Growth of Graphene by Atmospheric Pressure Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Zhang, Haoran; Zhang, Yanhui; Wang, Bin; Chen, Zhiying; Sui, Yanping; Zhang, Yaqian; Tang, Chunmiao; Zhu, Bo; Xie, Xiaoming; Yu, Guanghui; Jin, Zhi; Liu, Xinyu

    2015-01-01

    Analysis of graphene domain synthesis explains the main graphene growth process. Size-limited graphene growth caused by hydrogen is studied to achieve efficient graphene synthesis. Graphene synthesis on Cu foils via the chemical vapor deposition method using methane as carbon source is limited by high hydrogen concentration. Results indicate that hydrogen affects graphene nucleation, the growth rate, and the final domain size. Considering the role of hydrogen as both activator and etching reagent, we build a model to explain the cause of this low graphene growth rate for high hydrogen partial pressure. A two-step method is proposed to control the graphene nucleation and growth rate separately. Half the time is required to obtain similar domain size compared with single-step synthesis, indicating improved graphene synthesis efficiency. The change of the partial pressure and transmission time between the two steps is a factor that cannot be ignored to control the graphene growth.

  19. Contribution of water vapor pressure to pressurization of plutonium dioxide storage containers

    Microsoft Academic Search

    D. Kirk Veirs; John S. Morris; Dane R. Spearing

    2000-01-01

    Pressurization of long-term storage containers filled with materials meeting the US DOE storage standard is of concern.1,2 For example, temperatures within storage containers packaged according to the standard and contained in 9975 shipping packages that are stored in full view of the sun can reach internal temperatures of 250 °C.3 Twenty five grams of water (0.5 wt.%) at 250 °C

  20. A unified equation for calculating methane vapor pressures in the CH4-H2O system with measured Raman shifts

    USGS Publications Warehouse

    Lu, W.; Chou, I.-M.; Burruss, R.C.; Song, Y.

    2007-01-01

    A unified equation has been derived by using all available data for calculating methane vapor pressures with measured Raman shifts of C-H symmetric stretching band (??1) in the vapor phase of sample fluids near room temperature. This equation eliminates discrepancies among the existing data sets and can be applied at any Raman laboratory. Raman shifts of C-H symmetric stretching band of methane in the vapor phase of CH4-H2O mixtures prepared in a high-pressure optical cell were also measured at temperatures between room temperature and 200 ??C, and pressures up to 37 MPa. The results show that the CH4 ??1 band position shifts to higher wavenumber as temperature increases. We also demonstrated that this Raman band shift is a simple function of methane vapor density, and, therefore, when combined with equation of state of methane, methane vapor pressures in the sample fluids at elevated temperatures can be calculated from measured Raman peak positions. This method can be applied to determine the pressure of CH4-bearing systems, such as methane-rich fluid inclusions from sedimentary basins or experimental fluids in hydrothermal diamond-anvil cell or other types of optical cell. ?? 2007 Elsevier Ltd. All rights reserved.

  1. An antiresonant Fabry-Perot saturable absorber for passive mode-locking fabricated by metal-organic vapor phase epitaxy and ion implantation design, characterization, and mode-locking

    Microsoft Academic Search

    M. J. Lederer; B. Luther-Davies; H. H. Tan; C. Jagadish

    1998-01-01

    We have fabricated GaAs-based antiresonant Fabry-Perot saturable absorbers (A-FPSAs) for passive mode-locking near infrared solid-state lasers using metal-organic vapor phase epitaxy (MOVPE) growth followed by ion implantation and optional thermal annealing. We present differential reflectivity measurements showing the effect of ion implantation and annealing. The devices were characterized for their large-signal response including saturation fluence, modulation depth, and nonbleachable losses-important

  2. Correction factors for saturation effects in white light and laser absorption spectroscopy for application to low pressure plasmas

    SciTech Connect

    Briefi, S. [Lehrstuhl fuer Experimentelle Plasmaphysik, Universitaet Augsburg, Universitaetsstr. 1, 86135 Augsburg (Germany); Wimmer, C.; Fantz, U. [Lehrstuhl fuer Experimentelle Plasmaphysik, Universitaet Augsburg, Universitaetsstr. 1, 86135 Augsburg (Germany); Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstr. 2, 85748 Garching (Germany)

    2012-05-15

    In white light absorption spectroscopy, the broadening of the absorption signal due to the apparatus profile of the spectrometer may lead to an underestimation of the determined density as one measures an apparent optical depth. This is in particular true for high optical depth where saturation effects of the transmitted intensity occur. Provided that the line profile of the absorption line is known, the apparent optical depth effect can be accounted for by introducing a correction factor. The impact of the saturation and the approach of considering the effect are demonstrated for argon and indium lines in low pressure plasmas where correction factors of one order of magnitude or even higher are reached very easily. For the indium line, the hyperfine splitting has been taken into account. In laser absorption, the line profile is resolved. However, the weak but rather broad background emission of the laser diode can cause a saturation signal at the photo diode resulting also in an underestimation of the density obtained from the analysis. It is shown that this can be taken into account by fitting the theoretical line profile to the measured absorption signal which yields also a correction factor. The method is introduced and demonstrated at the example of the cesium resonance line including the hyperfine splitting. Typical correction factors around two are obtained for the cesium ground state density at conditions of a low pressure negative hydrogen ion source in which cesium is evaporated to enhance the negative ion production.

  3. What is the significance of pore pressure in a saturated shale layer?

    Microsoft Academic Search

    J. Gonçalvès; P. Rousseau-Gueutin; G. de Marsily; P. Cosenza; S. Violette

    2010-01-01

    Electrostatic interactions, associated with negatively charged surfaces of clay minerals, produce a so-called “disjoining pressure” when diffuse layers overlap, i.e., at low porosity. Disjoining pressure is the pressure difference between the water in the clay pore space and that in a bulk solution at the same depth. Another widely used concept in clay-rocks is the “swelling pressure.” It corresponds in

  4. Atmospheric pressure synthesis of photoluminescent hybrid materials by sequential organometallic vapor infiltration into polyethylene terephthalate fibers

    NASA Astrophysics Data System (ADS)

    Akyildiz, Halil I.; Mousa, Moataz Bellah M.; Jur, Jesse S.

    2015-01-01

    Exposing a polymer to sequential organometallic vapor infiltration (SVI) under low pressure conditions can significantly modify the polymer's chemical, mechanical, and optical properties. We demonstrate that SVI of trimethylaluminum into polyethylene terephthalate (PET) can also proceed readily at atmospheric pressure, and at 60 °C the extent of reaction determined by mass uptake is independent of pressure between 2.5 Torr and 760 Torr. At 120 °C, however, the mass gain is 50% larger at 2.5 Torr relative to that at 760 Torr, indicating that the precursor diffusion in the chamber and fiber matrix decreases at higher source pressure. Mass gain decreases, in general, as the SVI process temperature increases both at 2.5 Torr and 760 Torr attributed to the faster reaction kinetics forming a barrier layer, which prevents further diffusion of the reactive species. The resulting PET/Al-Ox product shows high photoluminescence compared to untreated fibers. A physical mask on the polymer during infiltration at 760 Torr is replicated in the underlying polymer, producing an image in the polymer that is visible under UV illumination. Because of the reduced precursor diffusivity during exposure at 760 Torr, the image shows improved resolution compared to SVI performed under typical 2.5 Torr conditions.

  5. Measurements of near-IR water vapor absorption at high pressure and temperature

    NASA Astrophysics Data System (ADS)

    Rieker, G. B.; Liu, X.; Li, H.; Jeffries, J. B.; Hanson, R. K.

    2007-03-01

    Tunable diode lasers (TDLs) are used to measure high resolution (0.1 cm-1), near-infrared (NIR) water vapor absorption spectra at 700 K and pressures up to 30 atm within a high-pressure and -temperature optical cell in a high-uniformity tube furnace. Both direct absorption and wavelength modulation with second harmonic detection (WMS-2f) spectra are obtained for 6 cm-1 regions near 7204 cm-1 and 7435 cm-1. Direct absorption measurements at 700 K and 10 atm are compared with simulations using spectral parameters from HITRAN and a hybrid database combining HITRAN with measured spectral constants for transitions in the two target spectral regions. The hybrid database reduces RMS error between the simulation and the measurements by 45% for the 7204 cm-1 region and 28% for the 7435 cm-1 region. At pressures above 10 atm, the breakdown of the impact approximation inherent to the Lorentzian line shape model becomes apparent in the direct absorption spectra, and measured results are in agreement with model results and trends at elevated temperatures reported in the literature. The wavelength-modulation spectra are shown to be less affected by the breakdown of the impact approximation and measurements agree well with the hybrid database predictions to higher pressures (30 atm).

  6. Measurement of soil saturated hydraulic conductivity: The method of constant pressure tubes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Field method to measure the saturated soil hydraulic conductivity is presented that does not require expensive equipment and preserves natural water flow pathways that may be bloked during soil core sampling for laboratory measurements. Vegetation must be removed from the plot prior the measurement...

  7. Detection and measurement of sulfur mustard (HD) offgassing from the weanling pig following exposure to saturated HD vapor. Technical report, September-October 1994

    SciTech Connect

    Logan, T.P.; Graham, J.S.; Martin, J.L.; Zallnick, J.E.; Jakubowski, E.M.

    1997-11-01

    Sulfur mustard (HD) is a chemical warfare agent for which there is neither antidote nor adequate therapeutic protection. Animal models are employed to investigate mechanisms of injury and to evaluate protective measures against HD exposure. Researchers whose experiments involve cutaneous application of HD vapor to animals benefit from the detection and quantitation of HD at the exposed site. The ability to detect and quantify HD enables the researcher to follow safe procedures in handling skin samples. We have designed an experimental procedure to measure HD offgassing from animal models. A Minicams(R), which is a portable gas chromatograph (GC) equipped with a flame photometric detector (FPD) and with online sorbent collection and desorption, was used to monitor the HD concentration. Confirming measurements were made using a two-step process that trapped HD on a Tenax sorbent offline and then transferred the sample by means of an ACEM 900 to a OC equipped with either FPD or a mass spectrometer (MS). We collected data from six experiments in which weanling pigs were exposed to saturated HD vapor via vapor caps containing 10 micro of HD. HD concentration was measured in time-weighted-average (TWA) units at a specific HD application site. The currently recommended exposure value for HD is 3 ng/l, 1 TWA unit. In five of the six experiments, Minicams HD concentration values were less than 0.5 TWA, 2 hours postexposure, and in one of the experiments, TWA Minicams concentration was less than 0.5 TWA, 5 hours post-exposure. OCIMS detection was used in three of the experiments to confirm Minicams data and to provide greater sensitivity and selectivity at 0.1 TWA. GC/MS data confirmed that HD concentrations fell below 0.1 TWA in less than S hours for a specific site.

  8. D0 Silicon Upgrade: Vapor Pressure Thermometry System Near LN2 Subcooler

    SciTech Connect

    Kuwazaki, Andrew; /Fermilab

    1996-07-01

    Fermi National Accelerator Laboratory (Fermilab) is in the process of upgrading its detectors. Among these upgrades is the need for more transfer lines containing both liquid nitrogen and helium gas. These two fluids are used to provide the necessary operating cryogenic temperatures for the various detectors, such as the Visible Light Photon Counter (VLPC) and the solenoid inside the detector's calorimeter. With additional piping, it is important to monitor the temperatures to assure that the detectors can operate correctly. This can be done two ways. The first method is to use a Resistance Temperature Device, called a RTD, which is made using either a carbon resistor or a platinum resistor and measures the temperature based on resistance. The second method is to use a vapor-pressure thermometry system. This design will focus on the second method. A nitrogen Vapor Pressure Thermometer (VPT) system is designed to determine the temperature of the liquid nitrogen (LN{sub 2}) supply line, after exiting the LN{sub 2} subcooler, inside the D-Zero Assembly Hall. The operating temperature range is designed from 77 to 300 Kelvin with an initial charge pressure of 100 psia. A cylindrical bulb with a 0.1875-inch diameter and 0.625-inch length allows for minimum cold and warm 1/4-inch O.D. SS 304L tubing lengths, 12-inch and 18-inch respectively, and maintains a liquid level of 50% inside the bulb during cold operation. The amount of nitrogen needed to fill the cylindrical bulb approximately half full is 0.149 grams. In order to conform to the conventional cold volume and warm volume VPT systems, we need to enlarge the existing 1/2-inch x 2-inch SCH. 10 LN{sub 2} supply line over a one foot section to 1-inch x 3-inch SCH. 10 piping.

  9. Germanium determination by flame atomic absorption spectrometry: an increased vapor pressure-chloride generation system.

    PubMed

    Kaya, Murat; Volkan, Mürvet

    2011-03-15

    A new chloride generation system was designed for the direct, sensitive, rapid and accurate determination of the total germanium in complex matrices. It was aimed to improve the detection limit of chloride generation technique by increasing the vapor pressure of germanium tetrachloride (GeCl(4)). In order to do so, a novel joint vapor production and gas-liquid separation unit equipped with a home-made oven was incorporated to an ordinary nitrous oxide-acetylene flame atomic absorption spectrometer. Several variables such as reaction time, temperature and acid concentration have been investigated. The linear range for germanium determination was 0.1-10 ng mL(-1) for 1 mL sampling volume with a detection limit (3s) of 0.01 ng mL(-1). The relative standard deviation (RSD) was 2.4% for nine replicates of a 1 ng mL(-1) germanium solution. The method was validated by the analysis of one non-certified and two certified geochemical reference materials, respectively, CRM GSJ-JR-2 (Rhyolite), and GSJ-JR-1 (Rhyolite), and GBW 07107 (Chinese Rock). Selectivity of the method was investigated for Cd(2+), Co(2+), Cu(2+), Fe(3+), Ga(3+), Hg(2+), Ni(2+), Pb(2+), Sn(2+), and Zn(2+) ions and ionic species of As(III), Sb(III), Te(IV), and Se(IV). PMID:21315908

  10. Track studies in water vapor using a low-pressure cloud chamber. I. Macroscopic measurements.

    PubMed

    Stonell, G P; Marshall, M; Simmons, J A

    1993-12-01

    Techniques have been developed to operate a low-pressure cloud chamber with pure water vapor. Photographs have been obtained of the tracks arising in this medium from the passage of ionizing radiation. The sources used were low-energy X rays, 242Cm alpha particles, and low-energy protons. Track lengths of the electrons were similar to those found previously in tissue-equivalent gas. W values of 35.6 +/- 0.4 and 32.6 +/- 0.6 eV per ion pair for carbon and aluminum X rays also compare closely with those in tissue-equivalent gas, but are somewhat higher than the predictions of Monte Carlo calculations. Differential w values were obtained: for alpha particles of energy 5.3 MeV the value was 33.0 +/- 3.0 eV per ion pair; for protons of energy 390, 230, and 85 keV the values were 30.6 +/- 1.9, 31.9 +/- 2.0, and 33.6 +/- 3.4 eV per ion pair. The energy losses of protons in water vapor were measured in a second (dummy) chamber used for energy calibration. Results support Janni's values of stopping power for protons in the energy range 40-480 keV. PMID:8278575

  11. Velocities of elastic waves and v P \\/ v S ratios in dry and water-saturated rock samples at high pressure

    Microsoft Academic Search

    M. P. Volarovich; V. A. Budnikov

    1978-01-01

    Elastic wave velocities and the ratiovP\\/vS were studied for dry and initially saturated samples of carbonate and crystalline rocks at pressures to 2 kbar. In initially saturated samplesvP increases in crystalline rock, whereas in sedimentary rock it may either increase or decrease with increasing pressure. Under the same conditionsvS remains approximately constant in crystalline rocks and decreases in sedimentary samples.

  12. Vapor pressure and boiling point elevation of slash pine black liquors: Predictive models with statistical approach

    SciTech Connect

    Zaman, A.A.; McNally, T.W.; Fricke, A.L. [Univ. of Florida, Gainesville, FL (United States)] [Univ. of Florida, Gainesville, FL (United States)

    1998-01-01

    Vapor-liquid equilibria and boiling point elevation of slash pine kraft black liquors over a wide range of solid concentrations (up to 85% solids) has been studied. The liquors are from a statistically designed pulping experiment for pulping slash pine in a pilot scale digester with four cooking variables of effective alkali, sulfidity, cooking time, and cooking temperature. It was found that boiling point elevation of black liquors is pressure dependent, and this dependency is more significant at higher solids concentrations. The boiling point elevation data at different solids contents (at a fixed pressure) were correlated to the dissolved solids (S/(1 {minus} S)) in black liquor. Due to the solubility limit of some of the salts in black liquor, a change in the slope of the boiling point elevation as a function of the dissolved solids was observed at a concentration of around 65% solids. An empirical method was developed to describe the boiling point elevation of each liquor as a function of pressure and solids mass fraction. The boiling point elevation of slash pine black liquors was correlated quantitatively to the pulping variables, using different statistical procedures. These predictive models can be applied to determine the boiling point rise (and boiling point) of slash pine black liquors at processing conditions from the knowledge of pulping variables. The results are presented, and their utility is discussed.

  13. Luminescence of mesoporous silicon powders treated by high-pressure water vapor annealing

    NASA Astrophysics Data System (ADS)

    Gelloz, Bernard; Loni, Armando; Canham, Leigh; Koshida, Nobuyoshi

    2012-07-01

    We have studied the photoluminescence of nanocrystalline silicon microparticle powders fabricated by fragmentation of PSi membranes. Several porosities were studied. Some powders have been subjected to further chemical etching in HF in order to reduce the size of the silicon skeleton and reach quantum sizes. High-pressure water vapor annealing was then used to enhance both the luminescence efficiency and stability. Two visible emission bands were observed. A red band characteristic of the emission of Si nanocrystals and a blue band related to localized centers in oxidized powders. The blue band included a long-lived component, with a lifetime exceeding 1 sec. Both emission bands depended strongly on the PSi initial porosity. The colors of the processed powders were tunable from brown to off-white, depending on the level of oxidation. The surface area and pore volume of some powders were also measured and discussed. The targeted applications are in cosmetics and medicine.

  14. Vapor Pressure of Three Brominated Flame Retardants Determined via Knudsen Effusion Method

    PubMed Central

    Fu, Jinxia; Suuberg, Eric M.

    2012-01-01

    Brominated flame retardants (BFRs) have been used in a variety of consumer products in the past four decades. The vapor pressures for three widely used BFRs, that is, tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD), and octabromodiphenyl ethers (octaBDEs) mixtures, were determined using the Knudsen effusion method and compared to those of decabromodiphenyl ether (BDE209). The values measured extrapolated to 298.15 K are 8.47 × 10?9, 7.47 × 10?10, and 2.33 × 10?9 Pa, respectively. The enthalpies of sublimation for these BFRs were estimated using the Clausius-Clapeyron equation and are 143.6 ± 0.4, 153.7 ± 3.1, and 150.8 ± 3.2 kJ/mole, respectively. In addition, the enthalpies of fusion and melting temperatures for these BFRs were also measured in the present study. PMID:22213441

  15. Partial Pressures for Several In-Se Compositions from Optical Absorbance of the Vapor

    NASA Technical Reports Server (NTRS)

    Brebrick, R. F.; Su, Ching-Hua

    2001-01-01

    The optical absorbance of the vapor phase over various In-Se compositions between 33.3-60.99 at.% Se and 673-1418 K was measured and used to obtain the partial pressures of Se2(g) and In2Se(g). The results are in agreement with silica Bourdon gauge measurements for compositions between 50-61 at.%, but significantly higher than those from Knudsen cell and simultaneous Knudsen-torsion cell measurements. It is found that 60.99 at.% Se lies outside the sesquiselenide homogeneity range and 59.98 at.% Se lies inside and is the congruently melting composition. The Gibbs energy of formation of the liquid from its pure liquid elements between 1000-1300 K is essentially independent of temperature and falls between -36 to -38 kJ per g atomic weight for 50 and 56% Se at 1200 and 1300 K.

  16. Effect of Vapor Pressure Scheme on Multiday Evolution of SOA in an Explicit Model

    NASA Astrophysics Data System (ADS)

    Lee-Taylor, J.; Madronich, S.; Aumont, B.; Camredon, M.; Emmons, L. K.; Tyndall, G. S.; Valorso, R.

    2011-12-01

    Recent modeling of the evolution of Secondary Organic Aerosol (SOA) has led to the critically important prediction that SOA mass continues to increase for several days after emission of primary pollutants. This growth of organic aerosol in dispersing plumes originating from urban point sources has direct implications for regional aerosol radiative forcing. We investigate the robustness of predicted SOA mass growth downwind of Mexico City in the model GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere), by assessing its sensitivity to the choice of vapor pressure prediction scheme. We also explore the implications for multi-day SOA mass growth of glassification / solidification of SOA constituents during aging. Finally we use output from the MOZART-4 chemical transport model to evaluate our results in the regional and global context.

  17. A search for chemical laser action in low pressure metal vapor flames. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Zwillenberg, M. L.

    1975-01-01

    Optical emissions were studied from low pressure (approximately 1 torr) dilute diffusion flames of Ca and Mg vapor with O2, N2O and mixtures of CCl4 and O2. The Ca flames with O2 and N2O revealed high vibrational excitation of the product CaO molecule (up to v=30). The flames with CCl4 revealed extreme nonequilibrium metal atom electronic excitation, up to the metal atom ionization limit (6.1 eV for Ca, 7.6 eV for Mg). The metal atom excited electronic state populations did not follow a Boltzmann distribution, but the excitation rates ('pumping rate') were found to obey an Arrhenius-type expression, with the electronic excitation energy playing the role of activation energy and a temperature of about 5000 K for triplet excited states and 2500 K for singlets (vs. approximately 500 K translational temperature).

  18. Epitaxial Growth of Zinc Oxide Whiskers by Chemical-Vapor Deposition under Atmospheric Pressure

    Microsoft Academic Search

    Minoru Satoh; Norio Tanaka; Yoshikazu Ueda; Shigeo Saitoh; Hidetoshi Saitoh

    1999-01-01

    ZnO whiskers were epitaxially grown by a chemical-vapor deposition technique employed at atmospheric pressure. Highly oriented ZnO whiskers grew at a substrate temperature of 550°C on (0001)alpha-Al2O3 substrates with a growth rate of 3.7 nm\\/s. X-ray diffractometry revealed that the epitaxial relationship between the whiskers and the substrate was determined as ZnO[\\\\bar{1}010](0001)\\/\\/Al2O3[\\\\bar{1}2\\\\bar{1}0](0001) or ZnO[\\\\bar{1}2\\\\bar{1}0](0001)\\/\\/Al2O3[\\\\bar{1}010](0001). In addition, the full-width at half

  19. Vapor Pressure Measurement for 4He Films Adsorbed on 2D Mesoporous Hectorite

    NASA Astrophysics Data System (ADS)

    Asano, Ryota; Toda, Ryo; Matsushita, Yuki; Hieda, Mitsunori; Matsushita, Taku; Wada, Nobuo

    2006-09-01

    The vapor-pressure measurement for adsorbed films is equivalent to the measurement of the chemical potential. By the measurement of 4He films adsorbed on two-dimensional (2D) mesoporous Hectorite, we obtained the 2D isothermal compressibility, the isosteric heat, and the effective thickness deduced from the FHH model, mainly above a coverage of 15 ?mol/m2. The compressibility shows two dips at n1 = 17.5±0.5 ?mol/m2 and n2 = 22.7±0.5 ?mol/m2 which correspond to the first layer completion and appearance of the quantum-Bose-fluid layer, respectively. For the quantum-Bose-fluid layer, the phonon velocity deduced from the compressibility is on the order of 100 m/s, and it reasonably agrees with that obtained from the 2D phonon heat capacity.

  20. Reid vapor-pressure regulation of gasoline, 1987-1990. Master's thesis

    SciTech Connect

    Butters, R.A.

    1990-09-30

    Although it is generally only a summertime problem, smog, as represented by its criteria pollutant, ozone, is currently the number one air pollution problem in the United States. Major contributors to smog formation are the various Volatile Organic Compounds (VOC's) which react with other chemicals in the atmosphere to form the ozone and other harmful chemicals known as smog. Gasoline is a major source of VOC's, not only as it is burned in car engines, but as it evaporates. Gasoline evaporates in storage tanks, as it is transferred during loading and refueling operations, and in automobiles, both while they are running and while parked in the driveway. In 1987, the United States Environmental Protection Agency began an almost unprecedented effort to reduce the evaporative quality of commercial gasolines by mandating reductions in its Reid Vapor Pressure (RVP).

  1. QSPR for prediction of subcooled vapor pressures (log PL) of polychlorinated trans-azobenzenes.

    PubMed

    Wilczy?ska-Piliszek, Agata J; Piliszek, S?awomir; Falandysz, Jerzy

    2012-01-01

    In this study the values of subcooled vapor pressures (log P(L)) were estimated for 209 trans chloroazobenzenes (Ct-ABs) that fill some gaps in analytical and experimental data on these compounds. There are 209 chloro derivatives of trans azobenzenes that are relatively stable and more environmentally relevant than 209 chloro cis congeners. The calculations models were based on the Quantitative Structure-Property Relationship (QSPR) scheme using the semi-empirical method (PM6) in molecular package (MOPAC) software and density functional theory (DFT) method using B3LYP functional and 6-311++G** basis set) in Gaussian 03 software method and the artificial neural networks (ANNs) prediction. The values of log P(L) predicted by models used varied between -3.94 to -2.66 for Mono-; -4.85 to -2.97 for Di-; -5.18 to -3.17 for Tri-; -6.02 to -3.77 for Tetra-; -6.64 to -4.64 for Penta-; -7.36 to -4.76 for Hexa-; -7.54 to -5.79 for Hepta-; -7.75 to -6.64 for Octa-; -7.89 to -7.44 for Nona-Ct-Abs; and -8.09 and -8.13 for Deca-Ct-AB. Based on these values Ct-ABs can be grouped localized among relatively low (log P(L) -4 to -2) and low (log P(L) < -4) mobile Persistent Organic Pollutants (POPs). Both the calculation methods employed were characterized by similar prediction ability of subcooled vapor pressure values of Ct-ABs, while those of PM6 are much more efficient due to a cheaper hardware used and around 300-fold less time spent on calculations. PMID:22560028

  2. An improved satellite-based approach for estimating vapor pressure deficit from MODIS data

    NASA Astrophysics Data System (ADS)

    Zhang, Hongmei; Wu, Bingfang; Yan, Nana; Zhu, Weiwei; Feng, Xueliang

    2014-11-01

    Vapor pressure deficit (VPD) is an important variable widely used in ecosystem and climate models. In this paper, an improved satellite-based approach to estimating VPD was presented that uses several remote sensing products coupled with field measured data. The proposed method exploits an optimized algorithm to derive near-surface actual vapor pressure (ea) from Moderate Resolution Imaging Spectroradiometer (MODIS) data and upgrades Smith's (1966) methodology for estimating ea. The proposed new algorithm for calculating ea was evaluated against in situ measurements at 119 validation sites in China for 2 months in 2013. The mean absolute error (MAE) and root-mean-square error (RMSE) were less than 0.25 kPa and 0.33 kPa, respectively. The near-surface air temperature (Ta), which is an important input data for calculating VPD, was estimated from satellite-retrieved land surface temperature, and had an RMSE of less than 2.5 K. The estimated VPD values were validated with ground observation data from the Heihe River Basin for 5 months in 2012 and for all of China for August 2013. A coefficient of determination (R2) of 0.912, MAE of 0.27 kPa, and RMSE value of 0.32 kPa were achieved for the 2012 test data, and corresponding values of 0.88, 0.278 kPa, and 0.367 kPa for the 2013 test data. These results are promising, especially considering the comparatively high spatial resolution (1 km) of the VPD map estimated from the satellite data. Potential applications include global evapotranspiration estimation, fire warning, and vegetation analysis.

  3. [Effect of saturation and velocity selective population in 6S1/2 --> 6P3/2 laser excitation in Cs vapor mixed with Ar].

    PubMed

    Liu, Jing; Zhou, Heng-wei; Zhang, Guo-liang; Dai, Kang; Shen, Yi-fan

    2008-09-01

    The excited state population distribution created by 6S1/2 --> 6P3/2 laser excitation in room temperature cesium vapor mixed with Ar was quantitatively analyzed applying absorption and saturation spectroscopy. A simple method for the determination of the excited state population in a single excitation step based on the measurements of the saturated and unsaturated absorption coefficients was tested. When the line profile is nearly pure Doppler and the laser linewidth is much smaller than the inhomogeneous linewidth but comparable with homogeneous linewidth, the fraction N(v(z)) of the atoms in the ground state that are able to absorb under inhomogeneous broadening conditions can be determined. The transmission of the medium in the center of the Doppler envelope of the strong h. f. component of the CsD2 line due to hyperfine pumping alone amounts to approximately 5%. The assumption that has been made is that the lower-state hyperfine levels are populated in a statistical ratio. The absorption coefficients were measured for a series of P852 powers between 20 microW and 2. 5 mW. The velocity selective population density in the 6P3/2 state was obtained. The population in the 6P3/2 level obtained from the saturation measurements was also determined by the absorption measurement of narrow spectral line from a Cs hollow cathode lamp. The agreement between the results obtained in these two ways is very good. It was shown that 5% of the ground state population could be transferred to the first excited state by pumping the Doppler broadened line with a single-mode narrow-band laser. The argon caused line broadening and therefore increased the effective pumping rate in the first excitation step. The dependence of the 852 nm line fluorescence intensity was plotted against the population in the 6P3/2 level determined from the saturation absorption. This can serve as confirmation of the reliability of the method used for the determination of the excited state population. PMID:19093539

  4. Influence of Pore-Fluid Pressure on Elastic Wave Velocity and Electrical Conductivity in Water-Saturated Rocks

    NASA Astrophysics Data System (ADS)

    Higuchi, A.; Watanabe, T.

    2013-12-01

    Pore-fluid pressure in seismogenic zones can play a key role in the occurrence of earthquakes (e.g., Sibson, 2009). Its evaluation via geophysical observations can lead to a good understanding of seismic activities. The evaluation requires a thorough understanding of the influence of the pore-fluid pressure on geophysical observables like seismic velocity and electrical conductivity. We have studied the influence of pore-fluid pressure on elastic wave velocity and electrical conductivity in water-saturated rocks. Fine grained (100-500?m) biotite granite (Aji, Kagawa pref., Japan) was used as rock samples. The density is 2.658-2.668 g/cm3, and the porosity 0.68-0.87%. The sample is composed of 52.8% plagioclase, 36.0% Quartz, 3.0% K-feldspar, 8.2% biotite. SEM images show that a lot of grain boundaries are open. Few intracrystalline cracks were observed. Following the method proposed by David and Zimmerman (2012), the distribution function of crack aspect ratio was evaluated from the pressure dependence of compressional and shear wave velocities in a dry sample. Cylindrical sample has dimensions of 25 mm in diameter and 30 mm in length, and saturated with 0.01 mol/l KCl aqueous solution. Compressional and shear wave velocities were measured with the pulse transmission technique (PZT transducers, f=2 MHz), and electrical conductivity the two-electrode method (Ag-AgCl electrodes, f=1 Hz-100 kHz). Simultaneous measurements of velocities and conductivity were made using a 200 MPa hydrostatic pressure vessel, in which confining and pore-fluid pressures can be separately controlled. The pore-fluid is electrically insulated from the metal work of the pressure vessel by using a newly designed plastic device (Watanabe and Higuchi, 2013). The confining pressure was progressively increased up to 25 MPa, while the pore-fluid pressure was kept at 0.1 MPa. It took five days or longer for the electrical conductivity to become stationary after increasing the confining pressure. Elastic wave velocities and electrical conductivity showed reproducibly contrasting changes for a small increase in the confining pressure. The elastic wave velocities increased only by 5% as the confining pressure increased from 0.1 MPa to 25 MPa, while the electrical conductivity decreased by an order of magnitude. Based on the SEM examinations, open grain boundaries work as cracks. The changes in elastic wave velocities and electrical conductivity must be caused by the closure of open grain boundaries. Most (˜80%) of the decrease in electrical conductivity occurred below the confining pressure of 5 MPa. As the confining pressure increased from 0.1 MPa to 5 MPa, cracks with the aspect ratio smaller than 7.5×10-5 were closed. The decrease in porosity was only 0.0005%. Such a small change in porosity caused a large change in electrical conductivity. The connectivity of fluid was maintained at the confining pressure of 25 MPa by cracks with the aspect ratio larger than 3.7×10-4. Simultaneous measurements have provided us a lot of information on the microstructure of fluid-bearing rocks.

  5. CO(2) partial pressure and calcite saturation in springs - useful data for identifying infiltration areas in mountainous environments.

    PubMed

    Hilberg, Sylke; Brandstätter, Jennifer; Glück, Daniel

    2013-04-01

    Mountainous regions such as the Central European Alps host considerable karstified or fractured groundwater bodies, which meet many of the demands concerning drinking water supply, hydropower or agriculture. Alpine hydrogeologists are required to describe the dynamics in fractured aquifers in order to assess potential impacts of human activities on water budget and quality. Delineation of catchment areas by means of stable isotopes and hydrochemical data is a well established method in alpine hydrogeology. To achieve reliable results, time series of (at least) one year and spatial and temporal close-meshed data are necessary. In reality, test sites in mountainous regions are often inaccessible due to the danger of avalanches in winter. The aim of our work was to assess a method based on the processes within the carbonic acid system to delineate infiltration areas by means of single datasets consisting of the main hydrochemical parameters of each spring. In three geologically different mountainous environments we managed to classify the investigated springs into four groups. (1) High PCO2 combined with slight super-saturation in calcite, indicating relatively low infiltration areas. (2) Low PCO2 near atmospheric conditions in combination with calcite saturation, which is indicative of relatively high infiltration areas and a fractured aquifer which is not covered by topsoil layers. (3) High PCO2 in combination with sub-saturation in calcite, representing a shallow aquifer with a significant influence of the topsoil layer. (4) The fourth group of waters is characterized by low PCO2 and sub-saturation in calcite, which is interpreted as evidence for a shallow aquifer without significant influence of any hard rock aquifer or topsoil layer. This study shows that CO2-partial pressure can be an ideal natural tracer to estimate the elevation of infiltration areas, especially in non-karstified fractured groundwater bodies. PMID:23429574

  6. Chemical vapor infiltration of pyrocarbon —II. The influence of increasing methane partial pressure at constant total pressure on infiltration rate and degree of pore filling

    Microsoft Academic Search

    W. Benzinger; K. J. Hüttinger

    1998-01-01

    Chemical vapor infiltration of pyrocarbon with methane as the carbon source was studied at a total pressure of 20 kPa, a temperature of 1100 °C and methane partial pressures from 2.5 to 20 kPa. A cylindrically-shaped porous alumina ceramic, 20 mm in height and 16 mm in diameter, was used as the substrate. The pore entrance diameters of the porous

  7. Peripheral oxygen saturation, heart rate, and blood pressure during dental treatment of children with cyanotic congenital heart disease

    PubMed Central

    Dutra, Rosane Menezes Faria; Neves, Itamara Lucia Itagiba; Neves, Ricardo Simões; Atik, Edmar; de Paula Santos, Ubiratan

    2014-01-01

    OBJECTIVES: In this observational study, we evaluated the peripheral oxygen saturation (SpO2), heart rate, and blood pressure of children with cyanotic congenital heart disease who were undergoing dental extraction. METHODS: Forty-four patients between the ages of 6 and 12 years who underwent upper primary tooth extraction were included in the study. Of these, 20 patients were in the cyanotic congenital heart disease group and 24 were in the control group. RESULTS: Peripheral oxygen saturation, heart rate, and systolic blood pressure in the cyanotic congenital heart disease group varied quite significantly during the treatment protocol (p<0.05), with values of 80.5% (±7.6) to 82.8% (±7.8), 95.3 beats per minute (bpm) (±11.3) to 101.3 bpm (±9.8), and 93.6 mm Hg (±13,3) to 103.8 mm Hg (±12.7), respectively. The variations in the control group during the procedure were also significant. CONCLUSIONS: The changes observed during the study protocol, although statistically significant, were mild and lacked clinical relevance. The results indicate that dental treatment of children with cyanotic heart disease using a standardized protocol in decentralized offices without the support of a surgical center is safe. PMID:24838895

  8. Solvent vapor recovery by pressure swing adsorption. 3: Comparison of simulation with experiment for the butane-activated carbon system

    Microsoft Academic Search

    J. Liu; CHARLES HOLLAND; JAMES RITTER

    1999-01-01

    A fully predictive (no adjustable parameters), nonisothermal, multicomponent mathematical model was developed and used to simulate a pressure swing adsorption (PSA) process designed for the separation and recovery of concentrated butane vapor from nitrogen using BAX activated carbon. Nearly quantitative agreement with experiment was realized with this model over a wide range of process conditions, and for both the transient

  9. Run to run control in tungsten chemical vapor deposition using H2 WF6 at low pressures

    E-print Network

    Gougousi, Theodosia

    through the use of the microbalance. A set of simulations in Matlab® preceded the control implementationRun to run control in tungsten chemical vapor deposition using H2 ÕWF6 at low pressures Ramaswamy Sreenivasan Institute for Systems Research and Department of Chemical Engineering, University of Maryland

  10. COMPUTATIONAL CHEMISTRY METHOD FOR PREDICTING VAPOR PRESSURES AND ACTIVITY COEFFICIENTS OF POLAR ORGANIC OXYGENATES IN PM2.5

    EPA Science Inventory

    Parameterizations of interactions of polar multifunctional organic oxygenates in PM2.5 must be included in aerosol chemistry models for evaluating control strategies for reducing ambient concentrations of PM2.5 compounds. Vapor pressures and activity coefficients of these compo...

  11. Atmospheric pressure chemical vapor deposition of transparent conducting films of fluorine doped zinc oxide and their application

    E-print Network

    Atmospheric pressure chemical vapor deposition of transparent conducting films of fluorine doped+Business Media, LLC 2007 Abstract Transparent conducting ZnO:F was deposited as thin films on soda lime glass the other transparent conducting oxides. Cadmium in all its compounds is toxic and carcinogenic

  12. DETERMINATION OF THE VAPOR PRESSURES OF SELECT POLYCHLORINATED DIBENZO-P-DIOXINS AND DIBENZOFURANS AT 75–275°C

    EPA Science Inventory

    Vapor pressures were determined for several polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) at 75–275°C, extending the available literature data to more relevant temperature regions and providing the first experimental data for 2,3,7...

  13. An Integrated Approach to Introducing Biofuels, Flash Point, and Vapor Pressure Concepts into an Introductory College Chemistry Lab

    ERIC Educational Resources Information Center

    Hoffman, Adam R.; Britton, Stephanie L.; Cadwell, Katie D.; Walz, Kenneth A.

    2011-01-01

    Students explore the fundamental chemical concepts of vapor pressure and flash point in a real-world technical context, while gaining insight into the contemporary societal issue of biofuels. Lab activities were developed using a closed-cup instrument to measure the flash point of various biodiesel samples. Pre- and post-tests revealed that the…

  14. Determination of octane numbers and Reid vapor pressure in commercial gasoline using dispersive fiber-optic Raman spectroscopy

    Microsoft Academic Search

    Philip E. Flecher; William T. Welch; Sacharia Albin; John B. Cooper

    1997-01-01

    Dispersive fiber-optic Raman spectroscopy utilizing CCD detection and near-IR DBR diode laser excitation is used to remotely analyze 205 petroleum fuels of varying composition for pump octane number, motor octane number (MON), research octane number (RON), and Reid vapor pressure (RVP). Partial least squares regression analysis in tandem with several preprocessing techniques was used to model pump octane, MON, RON,

  15. Photosynthetic photon flux density, carbon dioxide concentration, and vapor pressure deficit effects on photosynthesis in cacao seedlings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cacao (Theobroma cacao) is a shade plant, native to the under-story of the evergreen rain forest of the Amazon basin and adapted to low levels of photosynthetic photon flux density (PPFD). The influence of PPFD, leaf to air water vapor pressure deficit (VPD) and external carbon dioxide concentration...

  16. Transport of Carbon Tetrachloride in a Fractured Vadose Zone due to Atmospheric Pressure Fluctuations, Diffusion, and Vapor Density

    NASA Astrophysics Data System (ADS)

    McCray, J. E.; Downs, W.; Falta, R. W.; Housley, T.

    2005-12-01

    DNAPL sources of carbon tetrachloride (CT) vapors are of interest at the Radioactive Waste Management Complex (RWMC) at the Idaho National Engineering and Environmental Laboratory (INEEL). The site is underlain by thick fractured basalt that includes sedimentary interbeds, each are a few meters thick. Daily atmospheric pressure fluctuations serve as driving forces for CT vapor transport in the subsurface. Other important transport processes for vapor movement include gas-phase diffusion and density-driven transport. The objective of this research is to investigate the influence and relative importance of these processes on gaseous transport of CT. Gas pressure and vapor concentration measurements were conducted at various depths in two wells. A numerical multiphase flow model (TOUGH2), calibrated to field pressure data, is used to conduct sensitivity analyses to elucidate the importance of the different transport mechanisms. Results show that the basalt is highly permeable to vertical air flow. The pressure dampening occurs mainly in the sedimentary interbeds. Model-calibrated permeability values for the interbeds are similar to those obtained in a study by the U.S. Geological Survey for shallow sediments, and an order of magnitude higher than column-scale values obtained by previous studies conducted by INEEL scientists. The transport simulations indicate that considering the effect of barometric pressure changes is critical to simulating transport of pollutants in the vadose zone above the DNAPL source. Predicted concentrations can be orders of magnitude smaller than actual concentrations if the effect is not considered. Below the DNAPL vapor source, accounting for density and diffusion alone would yield acceptable results provided that a 20% error in concentrations are acceptable, and that simulating concentrations trends (and not actual concentrations) is the primary goal.

  17. Comprehensive characterization of temperature- and pressure-induced bilayer phase transitions for saturated phosphatidylcholines containing longer chain homologs.

    PubMed

    Goto, Masaki; Endo, Takuya; Yano, Takahiro; Tamai, Nobutake; Kohlbrecher, Joachim; Matsuki, Hitoshi

    2015-04-01

    Complete elucidation of the phase behavior of phospholipid bilayers requires information on the subtransition from the lamellar crystal (Lc) phase to the gel phase. However, for bilayers of saturated diacylphosphatidylcholines (CnPCs), especially longer chain homologs, equilibration in the Lc phase is known to be very slow. In this study, bilayer phase transitions of three CnPCs with longer acyl chains, C19PC, C20PC and C21PC, were observed by differential scanning calorimetry under atmospheric pressure and by light-transmittance measurements under high pressure. Using lipid samples treated by thermal annealing enabled the observation of the sub-, pre- and main transitions of the C19PC and C20PC bilayers under atmospheric pressure. Only the pre- and main transitions could be observed for the C21PC bilayer due to very slow kinetics of the Lc phase formation for lipids with long acyl chains. The temperature and pressure phase diagrams constructed and phase-transitions quantities (enthalpy, entropy and volume changes) evaluated for these bilayers were compared with one another and with those of bilayers of the CnPC homologs examined in previous studies. These results allowed us (1) to clarify the temperature- and pressure-dependent phase sequence and phase stability of the CnPC (n=12-22) bilayers as a function of the hydrophobicity of the molecules, (2) to prove the presence of a shorter and a longer limit (n=13 and 21) in the acyl chain length for the pressure-induced bilayer interdigitation and (3) to reveal the chain-length dependence of the thermodynamic quantities of the subtransitions including the volume change. PMID:25779604

  18. Synthetic fluid inclusions XIX. Experimental determination of the vapor-saturated liquidus of the system H2O-NaCl-FeCl2

    NASA Astrophysics Data System (ADS)

    Lecumberri-Sanchez, Pilar; Steele-MacInnis, Matthew; Bodnar, Robert J.

    2015-01-01

    Magmatic-hydrothermal fluids associated with felsic to intermediate composition magmas are generally dominated by (Na ± K)Cl, but often the fluids also contain significant concentrations of FeCl2. Previously, fluid inclusions containing such fluids were interpreted using the properties of H2O-NaCl because the effect of FeCl2 on the phase equilibrium and volumetric (PVTx) properties of aqueous fluids was essentially unknown. In this study, synthetic fluid inclusion experiments have been conducted to determine the vapor-saturated liquidus phase relations of the system H2O-NaCl-FeCl2. Microthermometric and microanalytical measurements on synthetic fluid inclusions have been combined with the limited existing data, as well as with predictions based on Pitzer's formalism, to determine the ternary cotectic and peritectic phase boundaries and liquidus fields. The liquidus is qualitatively similar to those of other ternary systems of H2O-NaCl plus divalent-cation chlorides (MgCl2 and CaCl2) and has been characterized through empirical equations that represent the liquid salinity on the ice- and halite-liquidus surfaces. The ice and halite liquidi intersect at a metastable cotectic curve, which can be used to determine fluid compositions in this system if metastable behavior is observed. Furthermore, based on the experimentally determined liquidus, bulk salinities of natural fluid inclusions can be determined from the last dissolution temperatures of ice and/or halite using the new empirical equations.

  19. The Effect of Films on the Capillary Pressure - Saturation Hysteresis in a Smooth-walled Wedge Channel

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Nolte, D.; Pyrak-Nolte, L. J.

    2010-12-01


    Thin fluid films are central to many multiphase flow applications; however, experimental investigation of films requires direct detection and measurement of films. Water film thicknesses can range from a few nanometers to several micrometers and may vary depending on local pore structures and material properties. In this study, laser confocal microscopy was employed to image volumetric fluid distribution and 3D interfaces during drainage and imbibition processes in a smooth-walled channel. Confocal microscopy provides an effective method to image directly 3D thin films and to measure film thickness, volume, and other parameters. The detection resolution is 1.19 ?m/pixel through a 10x objective lens and is 0.72 ?m/pixel through a 20x lens. A smooth-walled wedge channel was fabricated to study the generation and relaxation of water films in the non-wetting phase of air. The effect of films on contact angle, interfacial area per volume (IAV), and capillary pressure - saturation (Pc - Sw) hysteresis were also investigated.
    Micromodels were fabricated using a negative photoresist (SU-8) sandwiched between two cover glasses. An all-SU-8 smooth-walled wedge channel was fabricated by laser direct-writing two-photon polymerization, 100 ?m wide at the outlet and 20 ?m at the inlet with a constant aperture of 40 ?m. A laser scanning confocal microscope was used to image the wetting (water) and non-wetting (air) phase distributions by labeling the wetting phase with a fluorophore, Alex Fluor-488, 1.0% by wieght. The 3D air-water interfaces were imaged and then reconstructed using a stack of confocal images. The samples were initially saturated with water, the wetting phase. A series of drainage and imbibition cycles were performed by incrementing or decrementing the air pressure. At each pressure, the system was allowed to equilibrate and then a stack of scans in depth was collected to acquire the 3D fluid distribution for the given pressure. The confocal images were analyzed to extract the volume saturation of water, IAV, and contact angle.
    Thin films of water between the air and the solid phase (SU-8 channel) were observed in the wedge micro-channel. The presence of films were found to increase the capillary pressure relative to the condition with no films by 0 ~ 1300 Pa as a function of wetting phase saturation. Force balance analysis was performed based on the contact angle at the common line, which shows an additional surface tension from the film that is approximately 1/10 that of the water surface tension. The same energy expended for the hysteresis loops was found between with and without film. In addition, only partial film relaxation is observed when a hysteresis scan is paused.
    Acknowledgments: This research is supported by the National Science Foundation (0911284-EAR).

  20. Osmotic virial coefficients of hydroxyethyl starch from aqueous hydroxyethyl starch-sodium chloride vapor pressure osmometry.

    PubMed

    Cheng, Jingjiang; Gier, Martin; Ross-Rodriguez, Lisa U; Prasad, Vinay; Elliott, Janet A W; Sputtek, Andreas

    2013-09-01

    Hydroxyethyl starch (HES) is an important industrial additive in the paper, textile, food, and cosmetic industries and has been shown to be an effective cryoprotectant for red blood cells; however, little is known about its thermodynamic solution properties. In many applications, in particular those in biology, HES is used in an aqueous solution with sodium chloride (NaCl). The osmotic virial solution thermodynamics approach accurately captures the dependence of osmolality on molality for many types of solutes in aqueous systems, including electrolytes, sugars, alcohols, proteins, and starches. Elliott et al. proposed mixing rules for the osmotic virial equation to be used for osmolality of multisolute aqueous solutions [Elliott, J. A. W.; et al. J. Phys. Chem. B 2007, 111, 1775-1785] and recently applied this approach to the fitting of one set of aqueous HES-NaCl solution data reported by Jochem and Körber [Cryobiology 1987, 24, 513-536], indicating that the HES osmotic virial coefficients are dependent on HES-to-NaCl mass ratios. The current study reports new aqueous HES-NaCl vapor pressure osmometry data which are analyzed using the osmotic virial equation. HES modifications were measured after dialysis (membrane cut off: 10,000 g/mol) and freeze-drying using vapor pressure osmometry at different mass ratios of HES to NaCl for HES up to 50% and NaCl up to 25% with three different HES modifications (weight average molecular weights [g/mol]/degree of substitution: 40,000/0.5; 200,000/0.5; 450,000/0.7). Equations were then fit to the data to provide a model for HES osmotic virial coefficient dependence on mass ratio of HES to NaCl. The osmolality data of the three HES modifications were accurately described over a broad range of HES-to-NaCl mass ratios using only four parameters, illustrating the power of the osmotic virial approach in analyzing complex data sets. As expected, the second osmotic virial coefficients increase with molecular weight of the HES and increase with HES-to-NaCl mass ratio. PMID:23862979

  1. An improved method for simultaneous determination of frictional pressure drop and vapor volume fraction in vertical flow boiling

    NASA Technical Reports Server (NTRS)

    Klausner, J. F.; Chao, B. T.; Soo, S. L.

    1990-01-01

    The two-phase frictional pressure drop and vapor volume fraction in the vertical boiling and adiabatic flow of the refrigerant, R11, have been simultaneously measured by a liquid balancing column and differential magnetic reluctance pressure transducers. An account is given of the experimental apparatus and procedure, data acquisition and analysis, and error estimation employed. All values of two-phase multipliers evaluated on the basis of the measured frictional pressure drop data in vertical upflow fall in the range bounded by the predictions of the Chisholm correlation and the homogeneous model.

  2. Optical measurements of pressure transients in the rapid vaporization of liquids on a pulsed-laser-heated surface

    SciTech Connect

    Park, H.K.; Kim, D.; Grigoropoulos, C.P. [Univ. of California, Berkeley, CA (United States). Dept. of Mechanical Engineering; Poon, C.C.; Tam, A.C. [IBM Almaden Research Center, San Jose, CA (United States)

    1995-12-31

    The transient pressure generation upon rapid phase transition of liquids is studied. Liquids vaporize explosively on a solid surface that is heated by a KrF excimer laser of nanosecond pulse duration. First the physical mechanisms responsible for the pressure production are reviewed. Experiments are then performed to detect acoustic wave transients by an in-situ optical technique, the photoacoustic probe beam deflection method, as well as a piezoelectric transducer. The bubble growth kinetics is simultaneously probed by the optical specular reflectance technique. The experimental results show that bubble expansions in the superheated liquid radiate a compressional pressure wave packet of high intensity, of the order of 1 MPa.

  3. Beer Law Constants and Vapor Pressures of HgI2 over HgI2(s,l)

    NASA Technical Reports Server (NTRS)

    Su, Ching-Hua; Zhu, Shen; Ramachandran, N.; Burger, A.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    The optical absorption spectra of the vapor phase over HgI2(s,l) were measured for wavelengths between 200 and 600 nm. The spectra show that the sample sublimed congruently into HgI2 with no Hg or I2 absorption spectrum observed. The Beer's Law constants for 15 wavelengths between 200 and 440 nm were determined. From these constants the vapor pressure of H912, P, was established as a function of temperatures for the liquid and the solid Beta-phases. The expressions correspond to the enthalpies of vaporization and sublimation of 15.30 and 20.17 Kcal/mole, respectively, for the liquid and the Beta-phase HgI2. The difference in the enthalpies gives an enthalpy of fusion of 4.87 Kcal/mole and the intersection of the two expressions gives a melting point of 537 K.

  4. Solid state phase transition and vapor pressure studies in ammonium nitrate-potassium nitrate binary system

    NASA Astrophysics Data System (ADS)

    Chien, Wen-Ming

    The solid-state phase transitions in ammonium nitrate (NH4NO 3) and potassium nitrate (KNO3) solid solutions and the equilibrium NH4NO3-KNO3 (AN-KN) phase diagram have been determined. The phase transitions and phase diagram were determined by using the differential scanning calorimetry (DSC) and high temperature X-ray diffractometry. Samples of several different compositions were made for these analyses in a special "Dry Room" with very low humidity. In the X-ray diffraction experiments, the samples were heated on Pt-Rh strip and LaB6 or Si was added for internal calibration. Equilibrium phase diagram was also calculated by using the "FactSage" computer program. A single (AN III) phase region without any phase transitions between 293 to 373 K was observed for compositions between 5 to 25wt% KNO3 in NH4NO3 that is critical for air bag gas generators. The higher temperature KNO3 (KN I) phase has a wide stability range, from 100%KNO3 to 20%KNO3 solution. There is one eutectic, two eutectoids, and two peritectoids in this phase diagram. Two newly discovered solid-state phases were found in the mid-composition range of AN-KN solid solutions. Details of phase equilibria and lattice expansions during heating have been determined. Phase diagram calculations show a reasonable match of the phase boundaries. The total vapor pressures as well as the average molecular weights of pure ammonium nitrate and 16% KNO3 solid solution were measured at various temperatures by the torsion-Knudsen effusion method. The partial pressures of NH4NO3 (PNH4NO 3), NH3 (PNH3), and HNO3 (PHNO 3) have also been determined.

  5. The evolution of mechanisms driving the stomatal response to vapor pressure deficit.

    PubMed

    McAdam, Scott A M; Brodribb, Timothy J

    2015-03-01

    Stomatal responses to vapor pressure deficit (VPD) are a principal means by which vascular land plants regulate daytime transpiration. While much work has focused on characterizing and modeling this response, there remains no consensus as to the mechanism that drives it. Explanations range from passive regulation by leaf hydration to biochemical regulation by the phytohormone abscisic acid (ABA). We monitored ABA levels, leaf gas exchange, and water status in a diversity of vascular land plants exposed to a symmetrical, mild transition in VPD. The stomata in basal lineages of vascular plants, including gymnosperms, appeared to respond passively to changes in leaf water status induced by VPD perturbation, with minimal changes in foliar ABA levels and no hysteresis in stomatal action. In contrast, foliar ABA appeared to drive the stomatal response to VPD in our angiosperm samples. Increased foliar ABA level at high VPD in angiosperm species resulted in hysteresis in the recovery of stomatal conductance; this was most pronounced in herbaceous species. Increased levels of ABA in the leaf epidermis were found to originate from sites of synthesis in other parts of the leaf rather than from the guard cells themselves. The transition from a passive regulation to ABA regulation of the stomatal response to VPD in the earliest angiosperms is likely to have had critical implications for the ecological success of this lineage. PMID:25637454

  6. Threefold atmospheric-pressure annealing for suppressing graphene nucleation on copper in chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Suzuki, Seiya; Nagamori, Takashi; Matsuoka, Yuki; Yoshimura, Masamichi

    2014-09-01

    Chemical vapor deposition (CVD) is a promising method of producing a large single-crystal graphene on a catalyst, especially on copper (Cu), and a further increase in domain size is desirable for electro/optic applications. Here, we report on threefold atmospheric-pressure (ATM) annealing for suppressing graphene nucleation in atmospheric CVD. Threefold ATM annealing formed a step and terrace surface of the underlying Cu, in contrast to ATM annealing. Atomic force microscopy and Auger electron mapping revealed that Si-containing particles existed on threefold-ATM- and ATM-annealed surfaces; particles on Cu had a lower density after threefold ATM annealing than after ATM annealing. The formation of a step and terrace surface and the lower density of particles following the threefold ATM annealing would play a role in reducing graphene nucleation. By combining threefold ATM annealing and electropolishing of Cu, the nucleation of graphene was effectively suppressed, and a submillimeter-sized hexagonal single-crystal graphene was successfully obtained.

  7. Modeling chemical vapor deposition of silicon dioxide in microreactors at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Konakov, S. A.; Krzhizhanovskaya, V. V.

    2015-01-01

    We developed a multiphysics mathematical model for simulation of silicon dioxide Chemical Vapor Deposition (CVD) from tetraethyl orthosilicate (TEOS) and oxygen mixture in a microreactor at atmospheric pressure. Microfluidics is a promising technology with numerous applications in chemical synthesis due to its high heat and mass transfer efficiency and well-controlled flow parameters. Experimental studies of CVD microreactor technology are slow and expensive. Analytical solution of the governing equations is impossible due to the complexity of intertwined non-linear physical and chemical processes. Computer simulation is the most effective tool for design and optimization of microreactors. Our computational fluid dynamics model employs mass, momentum and energy balance equations for a laminar transient flow of a chemically reacting gas mixture at low Reynolds number. Simulation results show the influence of microreactor configuration and process parameters on SiO2 deposition rate and uniformity. We simulated three microreactors with the central channel diameter of 5, 10, 20 micrometers, varying gas flow rate in the range of 5-100 microliters per hour and temperature in the range of 300-800 °C. For each microchannel diameter we found an optimal set of process parameters providing the best quality of deposited material. The model will be used for optimization of the microreactor configuration and technological parameters to facilitate the experimental stage of this research.

  8. Atmospheric Pressure Spray Chemical Vapor Deposited CuInS2 Thin Films for Photovoltaic Applications

    NASA Technical Reports Server (NTRS)

    Harris, J. D.; Raffaelle, R. P.; Banger, K. K.; Smith, M. A.; Scheiman, D. A.; Hepp, A. F.

    2002-01-01

    Solar cells have been prepared using atmospheric pressure spray chemical vapor deposited CuInS2 absorbers. The CuInS2 films were deposited at 390 C using the single source precursor (PPh3)2CuIn(SEt)4 in an argon atmosphere. The absorber ranges in thickness from 0.75 - 1.0 micrometers, and exhibits a crystallographic gradient, with the leading edge having a (220) preferred orientation and the trailing edge having a (112) orientation. Schottky diodes prepared by thermal evaporation of aluminum contacts on to the CuInS2 yielded diodes for films that were annealed at 600 C. Solar cells were prepared using annealed films and had the (top down) composition of Al/ZnO/CdS/CuInS2/Mo/Glass. The Jsc, Voc, FF and (eta) were 6.46 mA per square centimeter, 307 mV, 24% and 0.35%, respectively for the best small area cells under simulated AM0 illumination.

  9. The Evolution of Mechanisms Driving the Stomatal Response to Vapor Pressure Deficit1[OPEN

    PubMed Central

    McAdam, Scott A.M.; Brodribb, Timothy J.

    2015-01-01

    Stomatal responses to vapor pressure deficit (VPD) are a principal means by which vascular land plants regulate daytime transpiration. While much work has focused on characterizing and modeling this response, there remains no consensus as to the mechanism that drives it. Explanations range from passive regulation by leaf hydration to biochemical regulation by the phytohormone abscisic acid (ABA). We monitored ABA levels, leaf gas exchange, and water status in a diversity of vascular land plants exposed to a symmetrical, mild transition in VPD. The stomata in basal lineages of vascular plants, including gymnosperms, appeared to respond passively to changes in leaf water status induced by VPD perturbation, with minimal changes in foliar ABA levels and no hysteresis in stomatal action. In contrast, foliar ABA appeared to drive the stomatal response to VPD in our angiosperm samples. Increased foliar ABA level at high VPD in angiosperm species resulted in hysteresis in the recovery of stomatal conductance; this was most pronounced in herbaceous species. Increased levels of ABA in the leaf epidermis were found to originate from sites of synthesis in other parts of the leaf rather than from the guard cells themselves. The transition from a passive regulation to ABA regulation of the stomatal response to VPD in the earliest angiosperms is likely to have had critical implications for the ecological success of this lineage. PMID:25637454

  10. Effect of Chemical Composition on Enthalpy of Evaporation and Equilibrium Vapor Pressure

    E-print Network

    Vladimir Kh. Dobruskin

    2010-04-20

    Proceeding from the Clausius-Clapeyron equation, the relation is derived that establishes a correlation between the partial enthalpy of evaporation from binary solutions, concentrations of components, and equilibrium vapor pressures. The difference between enthalpies of evaporation of components from solutions and those from the pure liquids, D(DH), depends on the chemical nature and concentrations, X, of solutions. The effect of concentrations on D(DH) makes different appearances in ideal and non-ideal solutions, although, as a whole, D(DH) increases with the growth of concentration of the second component. A model is introduced, which considers D(DH) as the sum of energetic changes of three sequential stages: passage of molecules from the bulk liquid into the surface layer, exit of the molecules on the outer side of the interface, and the following desorption into the gas phase. In the framework of the model, the main contribution to enthalpy of evaporation comes from the processes in the surface layer. It is suggested that adsorption from solutions, which changes the chemical composition of the surface layer with respect to that of the bulk solution, determines, to great extent, the difference in the forms of the curves D(DH)=f(X) for ideal and non-ideal solutions.

  11. The effect of vapor pressure deficit on water use efficiency at the subdaily time scale

    NASA Astrophysics Data System (ADS)

    Zhou, Sha; Yu, Bofu; Huang, Yuefei; Wang, Guangqian

    2014-07-01

    Water use efficiency is a critical index for describing carbon-water coupling in terrestrial ecosystems. However, the nonlinear effect of vapor pressure deficit (VPD) on carbon-water coupling has not been fully considered. To improve the relationship between gross primary production (GPP) and evapotranspiration (ET) at the subdaily time scale, we propose a new underlying water use efficiency (uWUE = GPP · VPD0.5/ET) and a hysteresis model to minimize time lags among GPP, ET, and VPD. Half-hourly data were used to validate uWUE for seven vegetation types from 42 AmeriFlux sites. Correlation analysis shows that the GPP · VPD0.5 and ET relationship (r = 0.844) is better than that between GPP · VPD and ET (r = 0.802). The hysteresis model supports the GPP · VPD0.5 and ET relationship. As uWUE is related to CO2 concentration, its use can improve estimates of GPP and ET and help understand the effect of CO2 fertilization on carbon storage and water loss.

  12. High vapor pressure deficit drives salt-stress-induced rice yield losses in India.

    PubMed

    Tack, Jesse; Singh, Rakesh K; Nalley, Lawton L; Viraktamath, Basavaraj C; Krishnamurthy, Saraswathipura L; Lyman, Nate; Jagadish, Krishna S V

    2015-04-01

    Flooded rice is grown across wide geographic boundaries from as far north as Manchuria and as far south as Uruguay and New South Wales, primarily because of its adaptability across diverse agronomic and climatic conditions. Salt-stress damage, a common occurrence in delta and coastal rice production zones, could be heightened by the interactions between high temperature and relative humidity (vapor pressure deficit - VPD). Using temporal and spatial observations spanning 107 seasons and 19 rice-growing locations throughout India with varying electrical conductivity (EC), including coastal saline, inland saline, and alkaline soils, we quantified the proportion of VPD inducing salinity damage in rice. While controlling for time-invariant factors such as trial locations, rice cultivars, and soil types, our regression analysis indicates that EC has a nonlinear detrimental effect on paddy rice yield. Our estimates suggest these yield reductions become larger at higher VPD. A one standard deviation (SD) increase in EC from its mean value is associated with 1.68% and 4.13% yield reductions at median and maximum observed VPD levels, respectively. Yield reductions increase roughly sixfold when the one SD increase is taken from the 75th percentile of EC. In combination, high EC and VPD generate near catastrophic crop loss as predicted yield approaches zero. If higher VPD levels driven by global warming materialize in conjunction with rising sea levels or salinity incursion in groundwater, this interaction becomes an important and necessary predictor of expected yield losses and global food security. PMID:25379616

  13. Organic component vapor pressures and hygroscopicities of aqueous aerosol measured by optical tweezers.

    PubMed

    Cai, Chen; Stewart, David J; Reid, Jonathan P; Zhang, Yun-Hong; Ohm, Peter; Dutcher, Cari S; Clegg, Simon L

    2015-01-29

    Measurements of the hygroscopic response of aerosol and the particle-to-gas partitioning of semivolatile organic compounds are crucial for providing more accurate descriptions of the compositional and size distributions of atmospheric aerosol. Concurrent measurements of particle size and composition (inferred from refractive index) are reported here using optical tweezers to isolate and probe individual aerosol droplets over extended timeframes. The measurements are shown to allow accurate retrievals of component vapor pressures and hygroscopic response through examining correlated variations in size and composition for binary droplets containing water and a single organic component. Measurements are reported for a homologous series of dicarboxylic acids, maleic acid, citric acid, glycerol, or 1,2,6-hexanetriol. An assessment of the inherent uncertainties in such measurements when measuring only particle size is provided to confirm the value of such a correlational approach. We also show that the method of molar refraction provides an accurate characterization of the compositional dependence of the refractive index of the solutions. In this method, the density of the pure liquid solute is the largest uncertainty and must be either known or inferred from subsaturated measurements with an error of <±2.5% to discriminate between different thermodynamic treatments. PMID:25522920

  14. Exchange of Na+ and K+ between water vapor and feldspar phases at high temperature and low vapor pressure

    USGS Publications Warehouse

    Fournier, R.O.

    1976-01-01

    In order to determine whether gas (steam) containing a small amount of dissolved alkali chloride is effective in promoting base exchange of Na+ and K+ among alkali feldspars and coexisting brine or brine plus solid salt, experiments were carried out at 400-700??C and steam densities ranging down to less than 0.05. For bulk compositions rich in potassium, the low pressure results are close to previous high-pressure results in composition of the fluid and coexisting solid phase. However, when the bulk composition is more sodic, alkali feldspars are relatively richer in potassium at low pressure than at high pressure. This behaviour corresponds to enrichment of potassium in the gas phase relative to coexisting brine and precipitation of solid NaCl when the brine plus gas composition becomes moderately sodic. The gas phase is very effective in promoting base exchange between coexisting alkali feldspars at high temperature and low water pressure. This suggests that those igneous rocks which contain coexisting alkali feldspars out of chemical equilibrium either remained very dry during the high-temperature part of their cooling history or that the pore fluid was a gas containing very little potassium relative to sodium. ?? 1976.

  15. Solvent vapor recovery by pressure swing adsorption. 2: Experimental periodic performance of the butane-activated carbon system

    SciTech Connect

    Liu, J.; Holland, C.E.; Ritter, J.A. [Univ. of South Carolina, Columbia, SC (United States)

    1998-12-01

    An experimental investigation was carried out for the separation and recovery of butane vapor (10 to 40 vol%) from nitrogen using Westvaco BAX activated carbon and a unique pressure swing adsorption (PSA)-solvent vapor recovery (SVR) system. The effects of six important process and operating parameters on the periodic process performance were obtained, i.e., the purge-to-feed ratio, purge pressure, volumetric feed flow rate, feed concentration, cycle time, and pressurization/blowdown step time. Overall, the experimental results were consistent with theoretical results in the literature for the effects of most of these parameters; however, some opposite and unique trends were observed. The experimental results verified that the concentration wave front may be contained within the bed even when the purge-to-feed ratio is less than unity, and that the process performance may be very sensitive to minor changes in the purge pressure. Moderate temperature swings (18 to 54 C) were exhibited in all cases, and they decreased with increasing bed coverage, especially when breakthrough occurred. Also, when the bed coverage increased, the mass transfer zone also increased. Finally, these experimental results provided significant insight into designing more efficient PSA-SVR processes and developing new PSA-SVR cycle configurations for improved solvent vapor enrichment.

  16. Differential equations governing slip-induced pore-pressure fluctuations in a water-saturated granular medium

    USGS Publications Warehouse

    Iverson, R.M.

    1993-01-01

    Macroscopic frictional slip in water-saturated granular media occurs commonly during landsliding, surface faulting, and intense bedload transport. A mathematical model of dynamic pore-pressure fluctuations that accompany and influence such sliding is derived here by both inductive and deductive methods. The inductive derivation shows how the governing differential equations represent the physics of the steadily sliding array of cylindrical fiberglass rods investigated experimentally by Iverson and LaHusen (1989). The deductive derivation shows how the same equations result from a novel application of Biot's (1956) dynamic mixture theory to macroscopic deformation. The model consists of two linear differential equations and five initial and boundary conditions that govern solid displacements and pore-water pressures. Solid displacements and water pressures are strongly coupled, in part through a boundary condition that ensures mass conservation during irreversible pore deformation that occurs along the bumpy slip surface. Feedback between this deformation and the pore-pressure field may yield complex system responses. The dual derivations of the model help explicate key assumptions. For example, the model requires that the dimensionless parameter B, defined here through normalization of Biot's equations, is much larger than one. This indicates that solid-fluid coupling forces are dominated by viscous rather than inertial effects. A tabulation of physical and kinematic variables for the rod-array experiments of Iverson and LaHusen and for various geologic phenomena shows that the model assumptions commonly are satisfied. A subsequent paper will describe model tests against experimental data. ?? 1993 International Association for Mathematical Geology.

  17. Aqueous solubilities, vapor pressures, and 1-octanol-water partition coefficients for C9-C14 linear alkylbenzenes

    USGS Publications Warehouse

    Sherblom, P.M.; Gschwend, P.M.; Eganhouse, R.P.

    1992-01-01

    Measurements and estimates of aqueous solubilities, 1-octanol-water partition coefficients (Kow), and vapor pressures were made for 29 linear alkylbenzenes having alkyl chain lengths of 9-14 carbons. The ranges of values observed were vapor pressures from 0.002 to 0.418 Pa, log Kow, from 6.83 to 9.95, and aqueous solubilities from 4 to 38 nmol??L-1. Measured values exhibited a relationship to both the alkyl chain length and the position of phenyl substitution on the alkyl chain. Measurement of the aqueous concentrations resulting from equilibration of a mixture of alkylbenzenes yielded higher than expected values, indicating cosolute or other interactive effects caused enhanced aqueous concentrations of these compounds. ?? 1992 American Chemical Society.

  18. Chemical vapor infiltration of pyrocarbon—III: the influence of increasing methane partial pressure at increasing total pressure on infiltration rate and degree of pore filling

    Microsoft Academic Search

    W. Benzinger; K. J. Hüttinger

    1999-01-01

    Chemical vapor infiltration of pyrocarbon was studied at 1100°C and methane pressures ranging from 5 to 100kPa. A cylindrically shaped porous alumina ceramic, 20mm in height and 16mm in diameter, was used as the substrate. The pore diameters of the porous ceramic range from 1 to 36?m and the total porosity amounts to 23%. Theoretical considerations based on the Weisz

  19. Solvent Vapor Recovery by Pressure Swing Adsorption. I. Experimental Transient and Periodic Dynamics of the Butane-Activated Carbon System

    Microsoft Academic Search

    Yujun Liu; Charles E. Holland; James A. Ritter

    1998-01-01

    An experimental investigation was carried out for the separation and recovery of butane vapor (10 to 40 vol%) from nitrogen using Westvaco BAX activated carbon in a twin-bed pressure swing adsorption (PSA) system utilizing a 4-step Skarstrom- type cycle. Twenty-four runs, covering a broad range of process and initial column conditions, were performed to investigate the transient and periodic process

  20. Transparent and Conductive ZnO Thin Films Prepared by Atmospheric-Pressure Chemical Vapor Deposition Using Zinc Acetylacetonate

    Microsoft Academic Search

    Tadatsugu Minami; Hideo Sonohara; Shinzo Takata; Hirotoshi Sato

    1994-01-01

    Highly transparent and conductive undoped and impurity-doped ZnO thin films have been prepared by atmospheric-pressure chemical vapor deposition (CVD) using Zn(C5H7O2)2 as a zinc source. A resistivity as low as 4.6×10-3 Omega · cm and an average transmittance above 85% in the visible range were obtained for undoped ZnO thin films deposited at 550°C using H2O as the oxygen source.

  1. Optical properties of wurtzite GaN grown by low-pressure metalorganic chemical-vapor deposition

    Microsoft Academic Search

    W. Shan; T. Schmidt; X. H. Yang; J. J. Song; B. Goldenberg

    1996-01-01

    We present the results of optical studies on the properties of GaN grown by low-pressure metalorganic chemical-vapor deposition, with emphasis on the issues vital to device applications such as stimulated emission and laser action as well as carrier relaxation dynamics. By optical pumping, stimulated emission and lasing were investigated over a wide temperature range up to 420 K. Using a

  2. Very long single- and few-walled boron nitride nanotubes via the pressurized vapor\\/condenser method

    Microsoft Academic Search

    Michael W. Smith; Kevin C. Jordan; Cheol Park; Jae-Woo Kim; Peter T. Lillehei; Roy Crooks; Joycelyn S. Harrison

    2009-01-01

    A new method for producing long, small-diameter, single- and few-walled, boron nitride nanotubes (BNNTs) in macroscopic quantities is reported. The pressurized vapor\\/condenser (PVC) method produces, without catalysts, highly crystalline, very long, small-diameter, BNNTs. Palm-sized, cotton-like masses of BNNT raw material were grown by this technique and spun directly into centimeters-long yarn. Nanotube lengths were observed to be 100 times that

  3. Volatile times for the very first ionic liquid: understanding the vapor pressures and enthalpies of vaporization of ethylammonium nitrate.

    PubMed

    Emel'yanenko, Vladimir N; Boeck, Gisela; Verevkin, Sergey P; Ludwig, Ralf

    2014-09-01

    A hundred years ago, Paul Walden studied ethyl ammonium nitrate (EAN), which became the first widely known ionic liquid. Although EAN has been investigated extensively, some important issues still have not been addressed; they are now tackled in this communication. By combining experimental thermogravimetric analysis with time of flight mass spectrometry (TGA-ToF-MS) and transpiration method with theoretical methods, we clarify the volatilisation of EAN from ambient to elevated temperatures. It was observed that up to 419?K, EAN evaporates as contact-ion pairs leading to very low vapour pressures of a few Pascal. Starting from 419?K, the decomposition to nitric acid and ethylamine becomes more thermodynamically favourable than proton transfer. This finding was supported by DFT calculations, which provide the free energies of all possible gas-phase species, and show that neutral molecules dominate over ion pairs above 500?K, an observation that is in nearly prefect agreement with the experimental boiling point of 513?K. This result is crucial for the ongoing practical applications of protic ionic liquids such as electrolytes for batteries and fuel cells because, in contrast to high-boiling conventional solvents, EAN exhibits no significant vapour pressure below 419?K and this property fulfils the requirements for the thermal behaviour of safe electrolytes. Overall, EAN shows the same barely measurable vapour pressures as typical aprotic ionic liquids at temperatures only 70?K lower. PMID:25077820

  4. Evaluation of Vapor Pressure and Ultra-High Vacuum Tribological Properties of Ionic Liquids (2) Mixtures and Additives

    NASA Technical Reports Server (NTRS)

    Morales, Wilfredo; Koch, Victor R.; Street, Kenneth W., Jr.; Richard, Ryan M.

    2008-01-01

    Ionic liquids are salts, many of which are typically viscous fluids at room temperature. The fluids are characterized by negligible vapor pressures under ambient conditions. These properties have led us to study the effectiveness of ionic liquids containing both organic cations and anions for use as space lubricants. In the previous paper we have measured the vapor pressure and some tribological properties of two distinct ionic liquids under simulated space conditions. In this paper we will present vapor pressure measurements for two new ionic liquids and friction coefficient data for boundary lubrication conditions in a spiral orbit tribometer using stainless steel tribocouples. In addition we present the first tribological data on mixed ionic liquids and an ionic liquid additive. Post mortem infrared and Raman analysis of the balls and races indicates the major degradation pathway for these two organic ionic liquids is similar to those of other carbon based lubricants, i.e. deterioration of the organic structure into amorphous graphitic carbon. The coefficients of friction and lifetimes of these lubricants are comparable to or exceed these properties for several commonly used space oils.

  5. Effusion Cell Measurements of the Vapor Pressure of Cobalt at Temperatures up to 2000K; Comparisons with Iron and Nickel

    NASA Technical Reports Server (NTRS)

    Nuth, J. A.; Ferguson, F. T.; Johnson, N. M.

    2004-01-01

    It has become increasingly clear over the past decade that high temperature processes played important roles in the Primitive Solar Nebula. Unfortunately, basic data, such as the vapor pressures of Fe, Ni, Co or SiO have not been measured over the appropriate temperature range (near T approx. 2000K), but must be extrapolated from lower temperature measurements often made more than 50 years ago. The extrapolation of the available data to higher temperatures can be quite complex (e.g., see [1] for SiO vapor pressures) and can depend on other factors such as the oxygen fugacity or the presence of hydrogen gas not accounted for in the original measurements. Moreover, modern technology has made possible more accurate measurements of such quantities over a wider temperature range. We have acquired a commercial Thermo-Cahn Thermogravimetric system capable of vacuum operation to 1700C and measurement of a 10g change in sample mass using up to a 100g sample, with microgram accuracy. With this new system we have initiated a series of basic vapor pressure measurements on simple metals such as Fe[2] and Ni[3] with the intention to extend such measurements to more complex systems once we gain sufficient experience.

  6. Investigation of the chaotic pressure fluctuation induced by the vapor bubble oscillation in the film boiling of superfluid helium

    NASA Astrophysics Data System (ADS)

    Zhang, P.; Murakami, M.; Wang, R. Z.

    2002-09-01

    Superfluid helium is often used in the contemporary applications. However, the cooling capacity of superfluid helium is often deteriorated due to the appearance of the vapor phase, even boiling. Experimental investigation of the boiling phenomena of superfluid helium is carried out to explore the mechanism of it. The experimental results show that film boiling of superfluid helium is very paticular. A vapor bubble as big as the heater size is seen to be expanding and crushing on the heater surface, and also a lot of noise could be heard. The pressure fluctuation caused by the expanding and crushing of the vapor bubble is measured. The amplitude of the pressure fluctuation is very large, which shows that the film boiling is rather violent. The pressure fluctuation is also investigated by various analysis methods: FFT (Fast Fourier Transformation), auto-correlation function, re-constructing of the state-space, estimation of Lyapunov exponent and the correlation dimension. The analysis results show that the film boiling of superfluid helium has some chaotic characteristic, which will lead to the full understand of the film boiling phenomena in superfluid helium and related chaotic oscillatory phenomena.

  7. Alkali vapor pressure modulation on the 100 ms scale in a single-cell vacuum system for cold atom experiments

    SciTech Connect

    Dugrain, Vincent; Reichel, Jakob [Laboratoire Kastler Brossel, ENS, UPMC, CNRS, 24 rue Lhomond, 75005 Paris (France); Rosenbusch, Peter [LNE-SYRTE, Observatoire de Paris, CNRS, UPMC, 61 av de l’Observatoire, 75014 Paris (France)

    2014-08-15

    We describe and characterize a device for alkali vapor pressure modulation on the 100 ms timescale in a single-cell cold atom experiment. Its mechanism is based on optimized heat conduction between a current-modulated alkali dispenser and a heat sink at room temperature. We have studied both the short-term behavior during individual pulses and the long-term pressure evolution in the cell. The device combines fast trap loading and relatively long trap lifetime, enabling high repetition rates in a very simple setup. These features make it particularly suitable for portable atomic sensors.

  8. Alkali vapor pressure modulation on the 100ms scale in a single-cell vacuum system for cold atom experiments

    E-print Network

    Vincent Dugrain; Peter Rosenbusch; Jakob Reichel

    2014-07-31

    We describe and characterize a device for alkali vapor pressure modulation on the 100ms timescale in a single-cell cold atom experiment. Its mechanism is based on optimized heat conduction between a current-modulated alkali dispenser and a heat sink at room temperature. We have studied both the short-term behavior during individual pulses and the long-term pressure evolution in the cell. The device combines fast trap loading and relatively long trap lifetime, enabling high repetition rates in a very simple setup. These features make it particularly suitable for portable atomic sensors.

  9. Temperature interactions with transpiration response to vapor pressure deficit among cultivated and wild soybean genotypes.

    PubMed

    Seversike, Thomas M; Sermons, Shannon M; Sinclair, Thomas R; Carter, Thomas E; Rufty, Thomas W

    2013-05-01

    A key strategy in soybean drought research is increased stomatal sensitivity to high vapor pressure deficit (VPD), which contributes to the 'slow wilting' trait observed in the field. These experiments examined whether temperature of the growth environment affected the ability of plants to respond to VPD, and thus control transpiration rate (TR). Two soybean [Glycine max (L.) Merr.] and four wild soybean [Glycine soja (Sieb. and Zucc.)] genotypes were studied. The TR was measured over a range of VPD when plants were growing at 25 or 30°C, and again after an abrupt increase of 5°C. In G. max, a restriction of TR became evident as VPD increased above 2.0?kPa when temperature was near its growth optimum of 30°C. 'Slow wilting' genotype plant introduction (PI) 416937 exhibited greater TR control at high VPD compared with Hutcheson, and only PI 416937 restrained TR after the shift to 35°C. Three of the four G. soja genotypes exhibited control over TR with increasing VPD when grown at 25°C, which is near their estimated growth optimum. The TR control became engaged at lower VPD than in G. max and was retained to differing degrees after a shift to 30°C. The TR control systems in G. max and G. soja clearly were temperature-sensitive and kinetically definable, and more restrictive in the 'slow wilting' soybean genotype. For the favorable TR control traits observed in G. soja to be useful for soybean breeding in warmer climates, the regulatory linkage with lower temperatures must be uncoupled. PMID:22989317

  10. Vapor pressure deficit controls on fire ignition and fire spread in boreal forest ecosystems

    NASA Astrophysics Data System (ADS)

    Sedano, F.; Randerson, J. T.

    2014-01-01

    Climate-driven changes in the fire regime within boreal forest ecosystems are likely to have important effects on carbon cycling and species composition. In the context of improving fire management options and developing more realistic scenarios of future change, it is important to understand how meteorology regulates different fire processes, including ignition, daily fire spread rates, and cumulative annual burned area. Here we combined MODIS active fires (MCD14ML), MODIS imagery (MOD13A1) and ancillary historic fire perimeter information to produce a dataset of daily fire spread maps of Alaska for the period 2002-2011. This approach provided a spatial and temporally continuous representation of fire progression and a precise identification of ignition and extinction locations and dates for each wildfire. The fire-spread maps were analyzed together with daily vapor pressure deficit (VPD) observations from the North American Regional Reanalysis (NARR) and lightning strikes from the Alaska Lightning Detection Network (ALDN). We found a significant relationship between daily VPD and probability that a lightning strike would develop into a fire ignition. In the first 5 days after ignition, above average VPD increased the probability that fires would grow to large or very large sizes. Strong relationships also were identified between VPD and burned area at several levels of temporal and spatial aggregation. As a consequence of regional coherence in meteorology, ignition, daily fire spread rates, and fire extinction events were often synchronized across different fires in interior Alaska. At a regional scale, the sum of positive VPD anomalies during the fire season was positively correlated with annual burned area during the NARR era (1979-2011; R2 = 0.45). Some of the largest fires we mapped had slow initial growth, indicating opportunities may exist for suppression efforts to adaptively manage these forests for climate change. The results of our spatiotemporal analysis provide new information about temporal and spatial dynamics of wildfires and have implications for modeling the terrestrial carbon cycle.

  11. Satellite Estimation of Daily Land Surface Water Vapor Pressure Deficit from AMSR- E

    NASA Astrophysics Data System (ADS)

    Jones, L. A.; Kimball, J. S.; McDonald, K. C.; Chan, S. K.; Njoku, E. G.; Oechel, W. C.

    2007-12-01

    Vapor pressure deficit (VPD) is a key variable for monitoring land surface water and energy exchanges, and estimating plant water stress. Multi-frequency day/night brightness temperatures from the Advanced Microwave Scanning Radiometer on EOS Aqua (AMSR-E) were used to estimate daily minimum and average near surface (2 m) air temperatures across a North American boreal-Arctic transect. A simple method for determining daily mean VPD (Pa) from AMSR-E air temperature retrievals was developed and validated against observations across a regional network of eight study sites ranging from boreal grassland and forest to arctic tundra. The method assumes that the dew point and minimum daily air temperatures tend to equilibrate in areas with low night time temperatures and relatively moist conditions. This assumption was tested by comparing the VPD algorithm results derived from site daily temperature observations against results derived from AMSR-E retrieved temperatures alone. An error analysis was conducted to determine the amount of error introduced in VPD estimates given known levels of error in satellite retrieved temperatures. Results indicate that the assumption generally holds for the high latitude study sites except for arid locations in mid-summer. VPD estimates using the method with AMSR-E retrieved temperatures compare favorably with site observations. The method can be applied to land surface temperature retrievals from any sensor with day and night surface or near-surface thermal measurements and shows potential for inferring near-surface wetness conditions where dense vegetation may hinder surface soil moisture retrievals from low-frequency microwave sensors. This work was carried out at The University of Montana, at San Diego State University, and at the Jet Propulsion Laboratory, California Institute of Technology, under contract to the National Aeronautics and Space Administration.

  12. Fabrication of Ferrite Thin Film using Low Pressure Metalorganic Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Yang, Yi

    This thesis is based on the research work on the multiferroic material fabrications using low pressure metalorganic chemical vapor deposition (MOCVD). Multiferroic material refers to the ones who have two or more ferroic properties, like ferroelectricity, ferromagnetism, ferroelasticity and ferrotoroidicity. Extensive research findings focused on pure nano scale thin films and composites those were related to presenting both ferroelectricity and ferromagnetism coupling within the material. BiFeO3 (BFO) was known to be the only single phase multiferroic material which exhibited magnetoelectric (ME) coupling effect at room temperature. This coupling effect provided an extra degree of freedom for designs of whole new devices and applications never thought to be possible before. Recently, large ME effect was found in its thin epitaxial-strained films. However, very few papers reported the CVD techniques for depositing BFO thin films so far. Most of these reports used direct liquid injection method to deliver the organometallic reactants during the CVD process (ie. DLICVD). Here, we introduced a novel liquid iron precursor, n-butylferrocene, delivered into the reactor by heating the precursor canisters at certain temperatures for growing BFO thin films. Other crucial MOCVD conditions (reactor's pressure, reactor's temperature, substrates...) were also discussed and optimized. Characterizations for the film composition, crystallinity, ferroelectricity, ferromagnetism and the magneto-dielectric coupling effect were analyzed in detail. The results confirmed that BFO film had multiferroic properties and could be potentially used in future tunable high-frequency devices. Although single-phase BFO exhibited ME effect, this suffered from problems such as current leakages, weak ME coupling and low ordering temperatures. Doping or ion substitution was a limited way to enhance the ME property since the compounds had definite compositions. Therefore, heterostructures such as bilayered/multilayered thin films, nanoparticles/nanopillars embedded in different materials and nanowires became more promising for the future on-chip integration applications because the coupling in such structures was many orders of magnitude stronger. Another research scientists interested in was the heterostructural magnetostrictive NiFe2O4 (NFO) with piezoelectric materials. NFO was a promising magnetic phase for ME heterostructures due to its low anisotropy, high permeability with high resistivity, low eddy current losses and smaller coercive field. In this study, the nickel ferrite thin films had been deposited using computer controlled MOCVD setup in both co-deposition mode and cyclic-deposition mode. Conditions for CVD process were discussed and optimized for growing NFO thin film. The thin films showed NFO composition, uniformity in chemical states and thickness, trevorite crystalline form, free from carbon contamination and similar magnetic property as other literature reported.

  13. On-line coating of glass with tin oxide by atmospheric pressure chemical vapor deposition.

    SciTech Connect

    Allendorf, Mark D.; Sopko, J.F. (PPF Industries, Pittsburgh, PA); Houf, William G.; Chae, Yong Kee; McDaniel, Anthony H.; Li, M. (PPF Industries, Pittsburgh, PA); McCamy, J.W. (PPF Industries, Pittsburgh, PA)

    2006-11-01

    Atmospheric pressure chemical vapor deposition (APCVD) of tin oxide is a very important manufacturing technique used in the production of low-emissivity glass. It is also the primary method used to provide wear-resistant coatings on glass containers. The complexity of these systems, which involve chemical reactions in both the gas phase and on the deposition surface, as well as complex fluid dynamics, makes process optimization and design of new coating reactors a very difficult task. In 2001 the U.S. Dept. of Energy Industrial Technologies Program Glass Industry of the Future Team funded a project to address the need for more accurate data concerning the tin oxide APCVD process. This report presents a case study of on-line APCVD using organometallic precursors, which are the primary reactants used in industrial coating processes. Research staff at Sandia National Laboratories in Livermore, CA, and the PPG Industries Glass Technology Center in Pittsburgh, PA collaborated to produce this work. In this report, we describe a detailed investigation of the factors controlling the growth of tin oxide films. The report begins with a discussion of the basic elements of the deposition chemistry, including gas-phase thermochemistry of tin species and mechanisms of chemical reactions involved in the decomposition of tin precursors. These results provide the basis for experimental investigations in which tin oxide growth rates were measured as a function of all major process variables. The experiments focused on growth from monobutyltintrichloride (MBTC) since this is one of the two primary precursors used industrially. There are almost no reliable growth-rate data available for this precursor. Robust models describing the growth rate as a function of these variables are derived from modeling of these data. Finally, the results are used to conduct computational fluid dynamic simulations of both pilot- and full-scale coating reactors. As a result, general conclusions are reached concerning the factors affecting the growth rate in on-line APCVD reactors. In addition, a substantial body of data was generated that can be used to model many different industrial tin oxide coating processes. These data include the most extensive compilation of thermochemistry for gas-phase tin-containing species as well as kinetic expressions describing tin oxide growth rates over a wide range of temperatures, pressures, and reactant concentrations.

  14. Capillary pressure and saturation relations for supercritical CO2 and brine in sand: High-pressure Pc(Sw) controller/meter measurements and capillary scaling predictions

    NASA Astrophysics Data System (ADS)

    Tokunaga, Tetsu K.; Wan, Jiamin; Jung, Jong-Won; Kim, Tae Wook; Kim, Yongman; Dong, Wenming

    2013-08-01

    In geologic carbon sequestration, reliable predictions of CO2 storage require understanding the capillary behavior of supercritical (sc) CO2. Given the limited availability of measurements of the capillary pressure (Pc) dependence on water saturation (Sw) with scCO2 as the displacing fluid, simulations of CO2 sequestration commonly rely on modifying more familiar air/H2O and oil/H2O Pc(Sw) relations, adjusted to account for differences in interfacial tensions. In order to test such capillary scaling-based predictions, we developed a high-pressure Pc(Sw) controller/meter, allowing accurate Pc and Sw measurements. Drainage and imbibition processes were measured on quartz sand with scCO2-brine at pressures of 8.5 and 12.0 MPa (45°C), and air-brine at 21°C and 0.1 MPa. Drainage and rewetting at intermediate Sw levels shifted to Pc values that were from 30% to 90% lower than predicted based on interfacial tension changes. Augmenting interfacial tension-based predictions with differences in independently measured contact angles from different sources led to more similar scaled Pc(Sw) relations but still did not converge onto universal drainage and imbibition curves. Equilibrium capillary trapping of the nonwetting phases was determined for Pc = 0 during rewetting. The capillary-trapped volumes for scCO2 were significantly greater than for air. Given that the experiments were all conducted on a system with well-defined pore geometry (homogeneous sand), and that scCO2-brine interfacial tensions are fairly well constrained, we conclude that the observed deviations from scaling predictions resulted from scCO2-induced decreased wettability. Wettability alteration by scCO2 makes predicting hydraulic behavior more challenging than for less reactive fluids.

  15. Graphene chemical vapor deposition at very low pressure: The impact of substrate surface self-diffusion in domain shape

    SciTech Connect

    Cunha, T. H. R.; Ek-Weis, J.; Lacerda, R. G.; Ferlauto, A. S., E-mail: ferlauto@fisica.ufmg.br [Department of Physics, Federal University of Minas Gerais, Belo Horizonte 31270-901 (Brazil)

    2014-08-18

    The initial stages of graphene chemical vapor deposition at very low pressures (<10{sup ?5?}Torr) were investigated. The growth of large graphene domains (?up to 100??m) at very high rates (up to 3??m{sup 2} s{sup ?1}) has been achieved in a cold-wall reactor using a liquid carbon precursor. For high temperature growth (>900?°C), graphene grain shape and symmetry were found to depend on the underlying symmetry of the Cu crystal, whereas for lower temperatures (<900?°C), mostly rounded grains are observed. The temperature dependence of graphene nucleation density was determined, displaying two thermally activated regimes, with activation energy values of 6?±?1?eV for temperatures ranging from 900?°C to 960?°C and 9?±?1?eV for temperatures above 960?°C. The comparison of such dependence with the temperature dependence of Cu surface self-diffusion suggests that graphene growth at high temperatures and low pressures is strongly influenced by copper surface rearrangement. We propose a model that incorporates Cu surface self-diffusion as an essential process to explain the orientation correlation between graphene and Cu crystals, and which can clarify the difference generally observed between graphene domain shapes in atmospheric-pressure and low-pressure chemical vapor deposition.

  16. A combined droplet train and ambient pressure photoemission spectrometer for the investigation of liquid/vapor interfaces

    SciTech Connect

    Starr, David E.; Wong, Ed K.; Worsnop, Douglas R.; Wilson, Kevin R.; Bluhm, Hendrik

    2008-05-01

    We describe a combined ambient pressure photoelectron spectroscopy/droplet train apparatus for investigating the nature and heterogeneous chemistry of liquid/vapor interfaces. In this instrument a liquid droplet train with typical droplet diameters from 50...150 {micro}m is produced by a vibrating orifice aerosol generator (VOAG). The droplets are irradiated by soft X-rays (100...1500 eV) in front of the entrance aperture of a differentially pumped electrostatic lens system that transfers the emitted electrons into a conventional hemispherical electron analyzer. The photoemission experiments are performed at background pressures of up to several Torr, which allows the study of environmentally important liquid/vapor interfaces, in particular aqueous solutions, under equilibrium conditions. The exposure time of the droplet surface to the background gases prior to the XPS measurement can be varied, which will allow future kinetic measurements of gas uptake on liquid surfaces. As an example, a measurement of the surface composition of a {chi} = 0.21 aqueous methanol solution is presented. The concentration of methanol at the vapor/liquid interface is enhanced by a factor of about 3 over the bulk value, while the expected bulk value is recovered at depths larger than about 1.5 nm.

  17. The dissolution of calcite in CO2-saturated solutions at 25??C and 1 atmosphere total pressure

    USGS Publications Warehouse

    Plummer, L.N.; Wigley, T.M.L.

    1976-01-01

    The dissolution of Iceland spar in CO2-saturated solutions at 25??C and 1 atm total pressure has been followed by measurement of pH as a function of time. Surface concentrations of reactant and product species have been calculated from bulk fluid data using mass transport theory and a model that accounts for homogeneous reactions in the bulk fluid. The surface concentrations are found to be close to bulk solution values. This indicates that calcite dissolution under the experimental conditions is controlled by the kinetics of surface reaction. The rate of calcite dissolution follows an empirical second order relation with respect to calcium and hydrogen ion from near the initial condition (pH 3.91) to approximately pH 5.9. Beyond pH 5.9 the rate of surface reaction is greatly reduced and higher reaction orders are observed. Calculations show that the rate of calcite dissolution in natural environments may be influenced by both transport and surface-reaction processes. In the absence of inhibition, relatively short times should be sufficient to establish equilibrium. ?? 1976.

  18. QSPRs for the estimation of subcooled liquid vapor pressures of polycyclic aromatic hydrocarbons, and of polychlorinated benzenes, biphenyls, dibenzo-p-dioxins, and dibenzofurans at environmentally relevant temperatures.

    PubMed

    van Noort, Paul C M

    2009-10-01

    This study aims to develop estimation procedures for subcooled liquid vapor pressures of polycyclic aromatic hydrocarbons (PAHs), and of polychlorinated benzenes, biphenyls (PCBs), dibenzo-p-dioxines (PCDDs), and dibenzofurans (PCDFs) based on quantitative structure-property relationships (QSPRs) for the subcooled liquid vaporization enthalpy and entropy in terms of simple molecular structure descriptors and the system temperature. It turned out that subcooled liquid vaporization enthalpies and entropies for these compound classes can be estimated from the number of carbon atoms, the number of chlorine atoms, the number of PCB ortho-chlorine atoms and the system temperature. Subcooled liquid vapor pressures at 298 K calculated from the estimated vaporization enthalpies and entropies were equal to directly measured experimental values as well as to experimental values determined by gas chromatographic methods within, on average, 0.15 and 0.12-0.3 log units, respectively. PMID:19709716

  19. Solvent vapor recovery by pressure swing adsorption. 3: Comparison of simulation with experiment for the butane-activated carbon system

    SciTech Connect

    Liu, J.; Holland, C.E.; Ritter, J.A. [Univ. of South Carolina, Columbia, SC (United States)] [Univ. of South Carolina, Columbia, SC (United States)

    1999-06-01

    A fully predictive (no adjustable parameters), nonisothermal, multicomponent mathematical model was developed and used to simulate a pressure swing adsorption (PSA) process designed for the separation and recovery of concentrated butane vapor from nitrogen using BAX activated carbon. Nearly quantitative agreement with experiment was realized with this model over a wide range of process conditions, and for both the transient and periodic state process dynamics and the periodic state process performance. The model also verified some unique characteristics of this PSA process, and it revealed some of the subtleties associated with accurately simulating a PSA-solvent vapor recovery (SVR) process. These subtleties included the need to account for the adsorbate heat capacity and the temperature dependence of the gas-phase physical properties. No PSA models in the literature have included both of these features, which were critical to the accurate prediction of the heat effects in this PSA-SVR process.

  20. Low pressure chemical vapor deposited borosilicate glasses for materials integration applications

    NASA Astrophysics Data System (ADS)

    Hansen, Darren Michael

    This thesis work investigated the growth and characterization of borosilicate glasses (BSGs), (SiO2)1-x(B2O 3)x, for materials integration applications. In particular, BSG layers deposited by low-pressure chemical vapor deposition (LPCVD) were used in wafer bonding and compliant substrate applications. A reaction model for BSG film growth from tetraethylorthosilicate (TEOS) and trimethylborate (TMB) was developed that predicts the growth rate and composition of BSG films up to x = 0.70. The BSG reaction model includes a strongly adsorbed TEOS-derived intermediate that forms SiO2 and a direct surface reaction of TMB, in O2, to form B2O 3. The BSG film morphology, critical to wafer bonding, was found to have a root-mean-square roughness of ˜0.5 nm, however, the specific morphology depended on reactor conditions. The BSG film can be planarized by thermal annealing between 550--725°C in a waterfree environment. Room temperature wafer bonding of GaAs to BSG/GaAs followed by thermal annealing and thermocompression bonding were investigated. For room temperature bonding, the surfaces were treated with a pre-bonding treatment of O 2 plasma exposure and H2O rinsing to make the surfaces hydrophilic. The chemical role of this pre-bonding treatment was investigated by Fourier transform infrared (FTIR) spectroscopy. The O2 plasma sputter etched the BSG surface, resulting in the presentation of a fresh surface for bonding. The H2O rinse added H2O/OH groups, however, the selective removal of B2O3 was measured. The bonding chemistry of various GaAs-to-oxide/GaAs bonded samples was investigated using multiple internal transmission (MIT) FTIR, providing a detailed bond-chemistry model. The initial bond is formed from surface absorbed H2O/OH species. After annealing at temperatures up to 600°C, a covalent bond between BSG and As(V)-O-related and Ga-O-related oxides is formed. BSG layers were used to develop a compliant substrate, consisting of 10 nm of GaAs on a BSG layer, for lattice-mismatched epitaxial growth. A process of wafer bonding and aqueous-based etching was used to fabricate the compliant substrate. Lattice-mismatched InxGa1-xAs films grown on compliant substrates exhibit smoother surfaces and narrower strain distributions in the X-ray diffraction spectra than films grown on conventional substrates. The mechanism for compliant behavior is demonstrated to be a result of modified dislocation introduction compared to conventional substrates.

  1. Zno-based thin films synthesized by atmospheric pressure mist chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Lu, J. G.; Kawaharamura, T.; Nishinaka, H.; Kamada, Y.; Ohshima, T.; Fujita, S.

    2007-02-01

    An atmospheric pressure mist chemical vapor deposition (mist-CVD) system has been developed to prepare zinc oxide (ZnO)-based thin films. This is a promising method for large-area deposition at low temperatures taking into account of its simplicity, inexpensiveness, and safety. Nominally pure ZnO, Al-doped n-type ZnO (ZnO:Al), and N-doped p-type ZnO (ZnO:N) thin films, as well as Zn 1-xCd xO and Zn 1-yMg yO alloy films, have been deposited by this mist-CVD system. The films deposited at the temperatures ranging from 400 to 500 °C were of an acceptable crystallinity with (0 0 2) preferential orientation and homogeneous surface. All the films exhibited high transmittance of about 90% in visible regions and dominant UV emission in the photoluminescence spectra. The n-type ZnO:Al films had a low resistivity of 1.08×10 -3 ? cm at an optimal Al content of 4 at%. The p-type conductivity was obtained in ZnO:N films annealed at higher temperatures with a resistivity of 72.8 ? cm, Hall mobility of 2.28 cm 2 V -1 s -1, and hole concentration of 3.76×10 16 cm -3, as confirmed by Hall-effect measurements. A hydrogen-assisted nitrogen-doping mechanism was proposed to answer for the realization of p-type conductivity in ZnO. The films of Zn 1-xCd xO and Zn 1-yMg yO ternary alloys were also deposited by this technique. The band gap energies, for instance, were 3.05 eV for Zn 1-xCd xO ( x=0.06), 3.28 eV for ZnO, and 3.56 eV for Zn 1-yMg yO ( y=0.11), as confirmed by the optical absorption spectra. The band gap engineering could be readily realized in the ZnO system using mist-CVD.

  2. Are fern stomatal responses to different stimuli coordinated? Testing responses to light, vapor pressure deficit, and CO2 for diverse species grown under contrasting irradiances.

    PubMed

    Creese, Chris; Oberbauer, Steve; Rundel, Phil; Sack, Lawren

    2014-10-01

    The stomatal behavior of ferns provides an excellent system for disentangling responses to different environmental signals, which balance carbon gain against water loss. Here, we measured responses of stomatal conductance (gs ) to irradiance, CO2 , and vapor pressure deficit (VPD) for 13 phylogenetically diverse species native to open and shaded habitats, grown under high- and low-irradiance treatments. We tested two main hypotheses: that plants adapted and grown in high-irradiance environments would have greater responsiveness to all stimuli given higher flux rates; and that species' responsiveness to different factors would be correlated because of the relative simplicity of fern stomatal control. We found that species with higher light-saturated gs had larger responses, and that plants grown under high irradiance were more responsive to all stimuli. Open habitat species showed greater responsiveness to irradiance and CO2 , but lower responsiveness to VPD; a case of plasticity and adaptation tending in different directions. Responses of gs to irradiance and VPD were positively correlated across species, but CO2 responses were independent and highly variable. The novel finding of correlations among stomatal responses to different stimuli suggests coordination of hydraulic and photosynthetic signaling networks modulating fern stomatal responses, which show distinct optimization at growth and evolutionary time-scales. PMID:25077933

  3. Gas collisions and pressure quenching of the photoluminescence of silicon nanopowder grown by plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Roura, P.; Costa, J.; Morante, J. R.; Bertran, E.

    1997-04-01

    The quenching of the photoluminescence of Si nanopowder grown by plasma-enhanced chemical vapor deposition due to pressure was measured for various gases ( H2, O2, N2, He, Ne, Ar, and Kr) and at different temperatures. The characteristic pressure, P0, of the general dependence I(P)=I0 exp(-P/P0) is gas and temperature dependent. However, when the number of gas collisions is taken as the variable instead of pressure, then the quenching is the same within a gas family (mono- or diatomic) and it is temperature independent. So it is concluded that the effect depends on the number of gas collisions irrespective of the nature of the gas or its temperature.

  4. Liquid-vapor phase equilibrium in a tin-selenium system

    NASA Astrophysics Data System (ADS)

    Volodin, V. N.; Burabaeva, N. M.; Trebukhov, S. A.

    2014-12-01

    Based on the pressure of the saturated vapor and components over liquid alloys in a tin-selenium system, determined using the boiling points approach (isothermal variant), its boiling point and corresponding vapor phase composition are calculated in the region of liquid solutions. The phase diagram is supple-mented with the liquid-vapor phase transition under atmospheric pressure and in vacuums of 100 and 10 Pa with the boundaries of the region in which the regions of liquid and vapor coexist being determined.

  5. Determination of evaporation rates and vapor pressures of very low volatility compounds: a study of the C4-C10 diacarboxylic acids

    NASA Astrophysics Data System (ADS)

    Cappa, C. D.; Lovejoy, E. R.; Ravishankara, A. R.

    2006-12-01

    A new method for the measurement of evaporation rates and vapor pressures of low volatility compounds was developed and was applied to the homologous C4-C10 dicarboxylic acids. Proton-transfer chemical ionization mass spectrometry was used to directly measure the temperature dependent evaporation rates of aerosol samples collected on a cold plate that could be heated at a known rate. The vapor pressures of the deposited compounds were derived from the observed evaporation rates through application of the Hertz-Knudsen equation. Temperature programmed desorption allows for quantification of the enthalpy (?Hvap) and entropy (?Svap) of vaporization of the diacids and will be described. A strong odd-even effect with respect to the total carbon number is observed in the derived diacid vapor pressures, consistent with previous measurements. However, the vapor pressures from this method tend to be lower than previous measurements. Though seen in the vapor pressure, no odd-even carbon chain length effect is discernible in the measured values of ?Hvap and ?Svap. Perhaps most importantly, these experimental results also suggest that residual solvent molecules (from the aerosol generation process) trapped in the diacid samples can have a considerable influence on the measured thermodynamic parameters and, if not properly accounted for, may give extraneous results.

  6. Upgrading pyrolysis vapors to aromatic gasoline with zeolite catalysis at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Diebold, James; Scahill, John

    1987-11-01

    The effect of different by-products on the theoretical gasoline yield is examined. Preliminary results, generated with a reactor having a fixed bed of 100 g of catalyst, are examined for the continuous feeding of never-condensed primary vapors and compared to feeding methanol in the same reactor. The conversion of primary pyrolysis vapors made from biomass is a relatively new research and development area which is showing early promise. The extent to which the product slate can be manipulated by process variables will impact heavily on the viability of this process.

  7. Very Long Single and Few-Walled Boron Nitride Nanotubes via the Pressurized Vapor/Condenser Method

    NASA Technical Reports Server (NTRS)

    Smith, Michael W.; Jordan, Kevin C.; Park, Cheol; Kim, Jae-Woo; Lillehei, Peter T.; Crooks, Roy; Harrison, Joycelyn S.

    2009-01-01

    A new method for producing long, small diameter, single and few-walled, boron nitride nanotubes (BNNTs) in macroscopic quantities is reported. The pressurized vapor/condenser (PVC) method produces, without catalysts, highly crystalline, very long, small diameter, BNNTs. Palm-sized, cotton-like masses of BNNT raw material were grown by this technique and spun directly into centimeters-long yarn. Nanotube lengths were observed to be 100 times that of those grown by the most closely related method. Self-assembly and growth models for these long BNNTs are discussed.

  8. Physical and electrical properties of graphene grown under different hydrogen flow in low pressure chemical vapor deposition

    PubMed Central

    2014-01-01

    Hydrogen flow during low pressure chemical vapor deposition had significant effect not only on the physical properties but also on the electrical properties of graphene. Nucleation and grain growth of graphene increased at higher hydrogen flows. And, more oxygen-related functional groups like amorphous and oxidized carbon that probably contributed to defects or contamination of graphene remained on the graphene surface at low H2 flow conditions. It is believed that at low hydrogen flow, those remained oxygen or other oxidizing impurities make the graphene films p-doped and result in decreasing the carrier mobility. PMID:25332692

  9. Very long single- and few-walled boron nitride nanotubes via the pressurized vapor/condenser method

    SciTech Connect

    Michael W. Smith, Kevin Jordan, Cheol Park, Jae-Woo Kim, Peter Lillehei, Roy Crooks, Joycelyn Harrison

    2009-11-01

    Boron nitride nanotubes (BNNTs) are desired for their exceptional mechanical, electronic, thermal, structural, textural, optical, and quantum properties. A new method for producing long, small-diameter, single- and few-walled, boron nitride nanotubes (BNNTs) in macroscopic quantities is reported. The pressurized vapor/condenser (PVC) method produces, without catalysts, highly crystalline, very long, small-diameter, BNNTs. Palm-sized, cotton-like masses of BNNT raw material were grown by this technique and spun directly into centimeters-long yarn. Nanotube lengths were observed to be 100 times that of those grown by the most closely related method. Self-assembly and growth models for these long BNNTs are discussed.

  10. Very long single- and few-walled boron nitride nanotubes via the pressurized vapor/condenser method.

    PubMed

    Smith, Michael W; Jordan, Kevin C; Park, Cheol; Kim, Jae-Woo; Lillehei, Peter T; Crooks, Roy; Harrison, Joycelyn S

    2009-12-16

    A new method for producing long, small-diameter, single- and few-walled, boron nitride nanotubes (BNNTs) in macroscopic quantities is reported. The pressurized vapor/condenser (PVC) method produces, without catalysts, highly crystalline, very long, small-diameter, BNNTs. Palm-sized, cotton-like masses of BNNT raw material were grown by this technique and spun directly into centimeters-long yarn. Nanotube lengths were observed to be 100 times that of those grown by the most closely related method. Self-assembly and growth models for these long BNNTs are discussed. PMID:19907071

  11. Very long single- and few-walled boron nitride nanotubes via the pressurized vapor/condenser method

    NASA Astrophysics Data System (ADS)

    Smith, Michael W.; Jordan, Kevin C.; Park, Cheol; Kim, Jae-Woo; Lillehei, Peter T.; Crooks, Roy; Harrison, Joycelyn S.

    2009-12-01

    A new method for producing long, small-diameter, single- and few-walled, boron nitride nanotubes (BNNTs) in macroscopic quantities is reported. The pressurized vapor/condenser (PVC) method produces, without catalysts, highly crystalline, very long, small-diameter, BNNTs. Palm-sized, cotton-like masses of BNNT raw material were grown by this technique and spun directly into centimeters-long yarn. Nanotube lengths were observed to be 100 times that of those grown by the most closely related method. Self-assembly and growth models for these long BNNTs are discussed.

  12. Z .Thin Solid Films 392 2001 231 235 Atmospheric pressure chemical vapor deposition of

    E-print Network

    of electrochromic tungsten oxide films Roy G. Gordona,U , Sean Barryb , Jeffrey T. Bartona , Randy N.R. Broomhall oxide, WO , is a coloring layer commonly used in electrochromic windows and displays. Successful: Chemical vapor deposition; Tungsten; Oxides; Electrochromism 1. Introduction Tungsten oxide is a key

  13. Solvent vapor recovery by pressure swing adsorption. 1: Experimental transient and periodic dynamics of the butane-activated carbon system

    SciTech Connect

    Liu, Y.; Holland, C.E.; Ritter, J.A. [Univ. of South Carolina, Columbia, SC (United States)

    1998-11-01

    An experimental investigation was carried out for the separation and recovery of butane vapor (10 to 40 vol%) from nitrogen using Westvaco BAX activated carbon in a twin-bed pressure swing adsorption (PSA) system utilizing a 4-step Skarstrom-type cycle. Twenty-four runs, covering a broad range of process and initial column conditions, were performed to investigate the transient and period process dynamics. In all cases the approach to the periodic state was very slow, taking up to 160 cycles depending on the initial condition of the beds; and peak bed temperatures of up to 105 C were observed depending on both the initial condition of the beds and the process conditions. Also, the periodic state of each run was unique when approaching a new periodic state from less contaminated beds. The uniqueness of the periodic states, together with the exceedingly high peak temperatures, inferred much about the practice of preconditioning beds to avoid high temperature excursions. The periodic enriched butane vapor concentration histories also gave considerable insight into new cycle designs for improved solvent vapor enrichment.

  14. Spatial and temporal variability of water vapor pressure in the arid region of northwest China, during 1961-2011

    NASA Astrophysics Data System (ADS)

    Yao, Junqiang; Chen, Yaning; Yang, Qing

    2015-01-01

    This paper investigated the spatial and temporal variations of the water vapor pressure (WVP) of the arid region of northwest China (ARNC) from 1961 to 2011. The original daily temperature and relative humidity data were collected from 96 meteorological stations in the region and analyzed by a Mann-Kendall test and linear trend. The results showed that (1) the WVP possesses vertical zonality and longitude zonality, which decreased from the low to high with the elevation increasing, and the WVP changed obviously from the northwest and southeast to the middle of the ARNC. (2) WVP exhibited an abrupt increasing trend in most of the stations over the past 51 years; only four meteorological stations displayed upward trend in the ARNC. The WVP in the desert increased most rapidly, followed by the oasis and mountainous area. (3) The northwest of Xinjiang and northwest of the Hexi Corridor were sensitive to the water vapor change. Thus, further studies should be performed on the relations between the land use and cover and the water vapor change.

  15. Beer Law Constants and Vapor Pressures of HgI2 over HgI2(s,l)

    NASA Technical Reports Server (NTRS)

    Su, Ching-Hua; Zhu, Shen; Ramachandran, N.; Burger, A.

    2002-01-01

    Optical absorption spectra of the vapor phase over HgI2(s,l) were measured at sample temperatures between 349 and 610 K for wavelengths between 200 and 600 nm. The spectra show the samples sublimed congruently into HGI2 without any observed Hg or I2 absorption spectra. The Beer's Law constants for 15 wavelengths between 200 and 440 nm were derived. From these constants the vapor pressure of HgI2, P, was found to be a function of temperature for the liquid and the solid beta-phases: ln P(atm) = -7700/T(K) + 12.462 (liquid phase) and ln P(atm) = -10150/T(K) + 17.026 (beta-phase). The expressions match the enthalpies of vaporization and sublimation of 15.30 and 20.17 kcal/mole respectively, for the liquid and the beta-phase HgI2. The difference in the enthalpies gives an enthalpy of fusion of 4.87 kcal/mole, and the intersection of the two expressions gives a melting point of 537 K.

  16. Stimulated emission mechanism of a copper vapor laser

    Microsoft Academic Search

    P. A. Bokhan; V. A. Gerasimov; V. I. Solomonov; V. B. Shcheglov

    1978-01-01

    An investigation is made of the elementary processes and characteristics of a pulsed nanosecond discharge plasma in a copper vapor–buffer gas mixture and of their correlation with the laser energy parameters. It is shown that the saturation of the stimulated emission power with rising pressure must be associated with a drop in the effective electron temperature. The complex dependence of

  17. Energy Management - Using Steam Pressure Efficiently

    E-print Network

    Jiandani, N.

    1983-01-01

    Saturated steam contains heat in two different forms. Sensible heat and latent heat. Due to the nature of this vapor, the relative proportion of latent heat is higher at lower pressures compared to higher pressures. When steam is used for heating...

  18. Vapor pressures of 1,3-dialkylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids with long alkyl chains

    NASA Astrophysics Data System (ADS)

    Rocha, Marisa A. A.; Coutinho, João A. P.; Santos, Luís M. N. B. F.

    2014-10-01

    This work presents the vapor pressure at several temperatures for the 1,3-dialkylimidazolium bis(trifluoromethylsulfonyl)imide series, [CN/2CN/2im][NTf2] (N = 14, 16, 18, and 20), measured by a Knudsen effusion method combined with a quartz crystal microbalance. The thermodynamic properties of vaporization of the ionic liquids under study are analysed together with the results obtained previously for the shorter alkyl chain length [CN/2CN/2im][NTf2] (N = 2, 4, 6, 8, 10, and 12), in order to evaluate the effect of the alkyl side chains of the cation and to get additional insights concerning the nanostructuration of ionic liquids. The symmetry effect is explored, based on the comparison with the asymmetric imidazolium based ionic liquids, [CN-1C1im][NTf2]. A trend shift on the thermodynamic properties of vaporization along the alkyl side chains of the extended symmetric ionic liquids, around [C6C6im][NTf2], was detected. An intensification of the odd-even effect was observed starting from [C6C6im][NTf2], with higher enthalpies and entropies of vaporization for the odd numbered ionic liquids, [C7C7im][NTf2] and [C9C9im][NTf2]. Similar, but less pronounced, odd-even effect was found for the symmetric ionic liquids with lower alkyl side chains length, [CN/2CN/2im][NTf2] (with N = 4, 6, 8, 10, and 12). This effect is related with the predominant orientation of the terminal methyl group of the alkyl chain to the imidazolium ring and their influence in the cation-anion interaction. The same Critical Alkyl length at the hexyl, (C6C1and C6C6) was found for both asymmetric and symmetric series indicating that the nanostructuration of the ionic liquids is related with alkyl chain length.

  19. Vapor pressures of 1,3-dialkylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids with long alkyl chains.

    PubMed

    Rocha, Marisa A A; Coutinho, João A P; Santos, Luís M N B F

    2014-10-01

    This work presents the vapor pressure at several temperatures for the 1,3-dialkylimidazolium bis(trifluoromethylsulfonyl)imide series, [CN/2CN/2im][NTf2] (N = 14, 16, 18, and 20), measured by a Knudsen effusion method combined with a quartz crystal microbalance. The thermodynamic properties of vaporization of the ionic liquids under study are analysed together with the results obtained previously for the shorter alkyl chain length [CN/2CN/2im][NTf2] (N = 2, 4, 6, 8, 10, and 12), in order to evaluate the effect of the alkyl side chains of the cation and to get additional insights concerning the nanostructuration of ionic liquids. The symmetry effect is explored, based on the comparison with the asymmetric imidazolium based ionic liquids, [CN-1C1im][NTf2]. A trend shift on the thermodynamic properties of vaporization along the alkyl side chains of the extended symmetric ionic liquids, around [C6C6im][NTf2], was detected. An intensification of the odd-even effect was observed starting from [C6C6im][NTf2], with higher enthalpies and entropies of vaporization for the odd numbered ionic liquids, [C7C7im][NTf2] and [C9C9im][NTf2]. Similar, but less pronounced, odd-even effect was found for the symmetric ionic liquids with lower alkyl side chains length, [CN/2CN/2im][NTf2] (with N = 4, 6, 8, 10, and 12). This effect is related with the predominant orientation of the terminal methyl group of the alkyl chain to the imidazolium ring and their influence in the cation-anion interaction. The same Critical Alkyl length at the hexyl, (C6C1and C6C6) was found for both asymmetric and symmetric series indicating that the nanostructuration of the ionic liquids is related with alkyl chain length. PMID:25296816

  20. Enhanced growth of high quality single crystal diamond by microwave plasma assisted chemical vapor deposition at high gas pressures

    NASA Astrophysics Data System (ADS)

    Liang, Qi; Chin, Cheng Yi; Lai, Joseph; Yan, Chih-shiue; Meng, Yufei; Mao, Ho-kwang; Hemley, Russell J.

    2009-01-01

    Single crystals of diamond up to 18 mm in thickness have been grown by microwave plasma assisted chemical vapor deposition at gas pressures of up to 350 torr. Growth rates of up to 165 ?m/h at 300 torr at high power density have been achieved. The processes were evaluated by optical emission spectroscopy. The high-quality single-crystal diamond grown at optimized conditions was characterized by UV-visible absorption and photoluminescence spectroscopy. The measurements reveal a direct relationship between residual absorption and nitrogen content in the gas chemistry. Fabrication of high quality single-crystal diamond at higher growth rates should be possible with improved reactor design that allows still higher gas synthesis pressures.

  1. Silicate liquid-carbonatite liquid transition along the melting curve of model, vapor-saturated peridotite in the system CaO-MgO-Al2O3-SiO2-CO2 from 1.1 to 2 GPa

    NASA Astrophysics Data System (ADS)

    Keshav, Shantanu; Gudfinnsson, Gudmundur H.

    2013-07-01

    phase relations of carbon dioxide-saturated (CO2 vapor) model peridotite in the system CaO-MgO-Al2O3-SiO2-CO2 in the 1.1-2.1 GPa pressure range are reported. The solidus has a positive slope in pressure-temperature (PT) space from 1.1 to 2 GPa. Between 2 and 2.1 GPa, the melting curve changes to a negative slope. From 1.1 to 1.9 GPa, the liquid, best described as CO2-bearing silicate liquid, is in equilibrium with forsterite, orthopyroxene, clinopyroxene, spinel, and vapor. At 2 GPa, the same crystalline phase assemblage plus vapor is in equilibrium with two liquids, which are silicate and carbonatitic in composition, making the solidus at 2 GPa PT invariant. The presence of two liquids is interpreted as being due to liquid immiscibility. Melting reactions written over 1.1-1.9 GPa are peritectic, with forsterite being produced upon melting, and the liquid is silicate in composition. Upon melting at 2.1 GPa, orthopyroxene is produced, and the liquid is carbonatitic in composition. Hence, the invariance between 1.9 and 2.1 GPa is not only the reason for the dramatic change in the liquid composition over an interval of 0.2 GPa, but the carbonated peridotite solidus ledge itself most likely appears because of this PT invariance. It is suggested that because carbonatitic liquid is produced at the highest solidus temperature at 2 GPa in PT space in the system studied, such liquids, in principle, can erupt through liquid immiscibility, as near-primary magmas from depths of approximately 60 km.

  2. Absolute integrated intensities of vapor-phase hydrogen peroxide (H202) in the mid-infrared at atmospheric pressure

    SciTech Connect

    Johnson, Timothy J.; Sams, Robert L.; Burton, Sarah D.; Blake, Thomas A.

    2009-09-01

    We report quantitative broadband infrared spectra of vapor-phase hydrogen peroxide (H2O2) with all spectra pressure broadened to atmospheric pressure. The spectra were generated by flowing a concentrated solution (83 weight%) of H2O2 into a gently heated disseminator and diluting with a flow of pure nitrogen carrier gas. The water vapor lines were subtracted from the resulting spectra to yield the spectrum of pure H2O2. Comparison with previous results for the ?6 band strength (including hot bands) compares favorably with the results of Klee et al. [(1999) J. Mol. Spectr. 195, 154] as well as HITRAN. The present results are 433 and 467 cm-2 atm-1 (±8% and ±3% at 298 and 323 K, respectively) for the band strength, matching well the Klee value (S = 467 cm-2 atm-1 at 296 K) for the integrated band. Other bands in the 520-7500 cm-1 interval and their potential for atmospheric monitoring are discussed.

  3. Coal Quality Impacts on Alkali Vapor Emissions from Pressurized Fluidized Bed Coal Combustors

    Microsoft Academic Search

    S. NIKSA; J. HELBLE; M. HARADAC; T. ANDO; J. SHIGETA; I. KAJIGAYA

    2001-01-01

    This paper describes a modeling study that was undertaken to identify the major ways that coal quality affects alkali vapor emissions in PFBC exhaust systems. The central premise is that the impact of coal quality can be reliably evaluated from kinetically based predictions of the concentrations of NaCl, KC1, SO2. HCI, O2, and H2O in the exhaust from the bubbling

  4. Real-time explosives/narcotics vapor enhancement and collection systems for use with the atmospheric pressure ionization time-of-flight mass spectrometer

    NASA Astrophysics Data System (ADS)

    Hintze, M. Marx; Hansen, Byron L.; Heath, Russell L.

    1992-05-01

    This paper is a companion document to the Atmospheric Pressure Ionization Time-of-Flight Mass Spectrometer (API TOFMS) presentation (Lee, et al., 1992). Two significant technique challenges related to design and implementation of vapor collection systems are addressed. They are as follows: (1) freeing deposited or trapped explosive material particles or vapor; and (2) transportation of sample specimen from the pickup point to the detector. Addressed in this dissertation will be both hand-held collection and air shower booth accumulation.

  5. Vapor pressures and calculated heats of vaporization of concentrated nitric acid solutions in the composition range 71 to 89 percent nitrogen dioxide, 1 to 10 percent water, and in the temperature range 10 to 60 degrees C

    NASA Technical Reports Server (NTRS)

    Mckeown, A B; Belles, Frank E

    1954-01-01

    Total vapor pressures were measured for 16 acid mixtures of the ternary system nitric acid, nitrogen dioxide, and water within the temperature range 10 degrees to 60 degrees Celsius, and with the composition range 71 to 89 weight percent nitric acid, 7 to 20 weight percent nitrogen dioxide, and 1 to 10 weight percent water. Heats of vaporization were calculated from the vapor pressure measurements for each sample for the temperatures 25, 40, and 60 degrees Celsius. The ullage of the apparatus used for the measurements was 0.46. Ternary diagrams showing isobars as a function of composition of the system were constructed from experimental and interpolated data for the temperatures 25, 40, 45, and 60 degrees C and are presented herein.

  6. Investigation of diamond growth at high pressure by microwave plasma chemical vapor deposition

    Microsoft Academic Search

    V. Mortet; A. Kromka; R. Kravets; J. Rosa; V. Vorlicek; J. Zemek; M. Vanecek

    2004-01-01

    Polycrystalline diamond thin films were grown on 2-inch silicon wafers at high pressures, up to 250 mbar, in high power microwave plasma CVD rotational ellipsoidal reactor. Influence of the gas pressure and the gas mixture on the diamond growth was investigated. High growth rates, up to 4.5 ?m\\/h, were obtained at high pressure and low methane concentration. Hydrogen desorption from

  7. Strength and ductility of room-dry and water-saturated igneous rocks at low pressures and temperatures to partial melting. Final report

    SciTech Connect

    Friedman, M.; Handin, J.; Higgs, N.G.; Lantz, J.R.; Bauer, S.J.

    1980-11-01

    Rock types that are likely candidates for drilling were tested. Reported herein are the short-time ultimate strengths and ductilities determined at temperatures of 25/sup 0/ to 1050/sup 0/C and a strain rate of 10/sup -4/s/sup -1/ of (a) room-dry Mt. Hood Andesite, Cuerbio Basalt, and Charcoal (St. Cloud Gray) Granodiorite at confining pressures of 0, 50, and 100 MPa, (b) water-saturated specimens of the same three rocks at zero effective pressure (both pore and confining pressures of 50 MPa), and (c) room-dry Newberry Rhyolite Obsidian at 0 and 50 MPa. These strengths are then compared with the stresses developed at the wall of a borehole in an elastic medium at the appropriate temperatures and mean pressures to assess the problem of borehole stability. (MHR)

  8. Bridgman-type apparatus for the study of growth-property relationships - Arsenic vapor pressure-GaAs property relationship

    NASA Technical Reports Server (NTRS)

    Parsey, J. M.; Nanishi, Y.; Lagowski, J.; Gatos, H. C.

    1982-01-01

    A precision Bridgman-type apparatus is described which was designed and constructed for the investigation of relationships between crystal growth parameters and the properties of GaAs crystals. Several key features of the system are highlighted, such as the use of a heat pipe for precise arsenic vapor pressure control and seeding without the presence of a viewing window. Pertinent growth parameters, such as arsenic source temperature, thermal gradients in the growing crystal and in the melt, and the macroscopic growth velocity can be independently controlled. During operation, thermal stability better than + or - 0.02 C is realized; thermal gradients can be varied up to 30 C/cm in the crystal region, and up to 20 C/cm in the melt region; the macroscopic growth velocity can be varied from 50 microns/hr to 6.0 cm/hr. It was found that the density of dislocations depends critically on As partial pressure; and essentially dislocation-free, undoped, crystals were grown under As pressure precisely controlled by an As source maintained at 617 C. The free carrier concentration varied with As pressure variations. This variation in free carrier concentration was found to be associated with variations in the compensation ratio rather than with standard segregation phenomena.

  9. Mass Spectrometric Identification of Si-O-H(g) Species from the Reaction of Silica with Water Vapor at Atmospheric Pressure

    NASA Technical Reports Server (NTRS)

    Opila, Elizabeth J.; Fox, Dennis S.; Jacobson, Nathan S.

    1997-01-01

    A high-pressure sampling mass spectrometer was used to detect the volatile species formed from SiO2 at temperatures between 1200C and 1400C in a flowing water vapor/oxygen gas mixture at 1 bar total pressure. The primary vapor species identified was Si(OH)4. The fragment ion Si(OH)3+,' was observed in quantities 3 to 5 times larger than the parent ion Si(OH)4+. The Si(OH)3+ intensity was found to have a small temperature dependence and to increase with the water vapor partial pressure as expected. In addition, SiO(OH)+ believed to be a fragment of SiO(OH)2, was observed. These mass spectral results were compared to the behavior of silicon halides.

  10. Effects of water-saturation on strength and ductility of three igneous rocks at effective pressures to 50 MPA and temperatures to partial melting

    SciTech Connect

    Bauer, S.J.; Friedman, M.; Handin, J.

    1981-01-01

    The short-term failure strengths and strains at failure of room-dry and water-saturated, cylindrical specimens (2 by 4 cm) of Charcoal Granodiorite (CG), Mt. Hood Andesite (MHA), and Cuerbio Basalt (CB) at a strain rate of 10/sup -4/s/sup -1/, at effective confining pressures of 0, 50, and 100 MPa and at temperatures to partial melting were investigated. Data from water-saturated specimens of the granodiorite and andesite, compared to room-dry counterparts, indicate (1) the pore pressures are essentially communicated throughout each test specimen so that they are fully effective; (2) at P/sub e/ = 0 and 50 MPa the granodiorite does not water-weaken; (3) at these same effective pressures the more porous and finer-grained andesite begins to exhibit water-weakening at about 600/sup 0/C; (4) at P/sub e/ = 0 and 870 to 900/sup 0/C the andesite's strength averages 20 MPa while the strength of dry specimens at the same P and T exhibit a strength of 100 MPa; (5) at P/sub e/ = 50 MPa compared to 160 MPa dry; (6) the basalt at P/sub e/ = 0, appears to be water-weakened at 800/sup 0/C; (7) water saturated specimens deformed at temperatures less than that of melting exhibit ultimate strengths at less than 2% shortening and then work-soften along faults; (8) again as do the dry counterparts, the wet specimens deform primarily by microscopic fracturing that coalesces into one or more macroscopic faults; and (9) the temperature for incipient melting of the andesite is decreased >150/sup 0/C in the water-saturated tests.

  11. Modeling and Real-Time Process Monitoring of Organometallic Chemical Vapor Deposition of III-V Phosphides and Nitrides at Low and High Pressure

    NASA Technical Reports Server (NTRS)

    Bachmann, K. J.; Cardelino, B. H.; Moore, C. E.; Cardelino, C. A.; Sukidi, N.; McCall, S.

    1999-01-01

    The purpose of this paper is to review modeling and real-time monitoring by robust methods of reflectance spectroscopy of organometallic chemical vapor deposition (OMCVD) processes in extreme regimes of pressure. The merits of p-polarized reflectance spectroscopy under the conditions of chemical beam epitaxy (CBE) and of internal transmission spectroscopy and principal angle spectroscopy at high pressure are assessed. In order to extend OMCVD to materials that exhibit large thermal decomposition pressure at their optimum growth temperature we have designed and built a differentially-pressure-controlled (DCP) OMCVD reactor for use at pressures greater than or equal to 6 atm. We also describe a compact hard-shell (CHS) reactor for extending the pressure range to 100 atm. At such very high pressure the decomposition of source vapors occurs in the vapor phase, and is coupled to flow dynamics and transport. Rate constants for homogeneous gas phase reactions can be predicted based on a combination of first principles and semi-empirical calculations. The pressure dependence of unimolecular rate constants is described by RRKM theory, but requires variational and anharmonicity corrections not included in presently available calculations with the exception of ammonia decomposition. Commercial codes that include chemical reactions and transport exist, but do not adequately cover at present the kinetics of heteroepitaxial crystal growth.

  12. Influence of free-standing GaN substrate on ultraviolet light-emitting-diodes by atmospheric-pressure metal-organic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Shieh, C. Y.; Li, Z. Y.; Chiu, C. H.; Tu, P. M.; Kuo, H. C.; Chi, G. C.

    2013-03-01

    We reported the influence of free-standing (FS) GaN substrate on ultraviolet light-emitting-diodes (UV LEDs) by atmospheric-pressure metal-organic chemical vapor deposition (APMOCVD). The Raman spectrum shows the in-plane compressive stress of the GaN epitaxial structures grown on FS GaN substrate. Besides, the Raman spectrum reveals the relation between the crystal quality and the carrier localization degree in multi-quantum wells (MQWs). High resolution X-ray diffraction (HRXRD) analysis results show that the In0.025Ga0.975N/Al0.08Ga0.92N MQWs grown on FS GaN substrate has higher indium mole fraction than sapphire at the same growth conditions. The higher indium incorporation is corresponding with the red-shift 6 nm (387 nm) of the room temperature photoluminescence (PL) peak. The full widths at half maximum (FWHM) of omega-scan rocking curve in (002) and (102) reflectance on FS GaN substrate (83 arcsec and 77 arcsec) are narrower than UV LEDs grown on sapphire (288 arcsec and 446 arcsec). This superior quality may attribute to homoepitaxial growth structure and better strain relaxation in the FS GaN substrate. An anomalous temperature behavior of PL in UV LEDs designated as an S-shaped peak position dependence and W-shaped linewidth dependence indicate that exciton/carrier motion occurs via photon-assisted tunneling through localized states, what results in incomplete thermalization of localized excitons at low temperature. The Gaussian broadening parameters of carrier localization is about 16.98 meV from the temperature dependent photoluminescence (TDPL) measurement. The saturation temperature from the TDPL linewidth of UV LEDs on FS GaN substrate at about 175 K represents a crossover from a nonthermalized to thermalized energy distribution of excitons.

  13. Evaluation of Parameters in Atmospheric-Pressure Chemical Vapor Deposition of Borophosphosilicate Glass Using Tetraethylorthosilicate and Ozone

    NASA Astrophysics Data System (ADS)

    Nishimoto, Yuko; Tokumasu, Noboru; Maeda, Kazuo

    2001-10-01

    The effective parameters for the atmospheric-pressure chemical vapor deposition (APCVD) of borophosphosilicate glass (BPSG) using tetraethylorthosilicate (TEOS) and ozone were evaluated by designing an experiment. Source efficiencies of the deposition and doping were evaluated at constant boron and phosphorus concentrations. Each parameter was also characterized in terms of uniformity and film properties, such as thermal shrinkage and wet etch rate. Interactions between boron and phosphorus were discussed in terms of the difference in influential parameters and reaction rates. The deposition was controlled by the deposition temperature and the deposition rate, which are the dominant parameters of the film quality and deposition efficiency. The balance between gas flow rate and temperature is important to improve deposition and doping uniformity.

  14. Surface Passivation of HgCdTe Using Low-Pressure Chemical Vapor Deposition of CdTe

    NASA Astrophysics Data System (ADS)

    Banerjee, Sneha; Su, Peng-Yu; Dahal, Rajendra; Bhat, Ishwara B.; Bergeson, Jeremy D.; Blissett, Caleb; Aqariden, Fikri; Hanyaloglu, Bengi

    2014-08-01

    CdTe passivation films have been deposited on Hg1- x Cd x Te ( x = 0.35) samples used for infrared detectors by low-pressure chemical vapor deposition (LPCVD) and atomic layer deposition (ALD) at temperatures as low as 135°C to 170°C. ALD has been used to deposit an initially uniform starting surface before continuing the deposition using LPCVD. Favorable conformal coverage has been demonstrated on high-aspect-ratio HgCdTe structures. LPCVD deposition rates of 40 nm/h to 70 nm/h were obtained by varying the sample temperature from 135°C to 170°C. Lifetime measurements carried out at 300 K exhibited a significant improvement in minority-carrier lifetime from 0.9 ?s (sample without passivation) to 4.28 ?s for samples passivated at 135°C.

  15. AlN Grown on a- and n-Plane Sapphire Substrates by Low-Pressure Hydride Vapor Phase Epitaxy

    NASA Astrophysics Data System (ADS)

    Goriki, Naoki; Miyake, Hideto; Hiramatsu, Kazumasa; Akiyama, Toru; Ito, Tomonori; Eryu, Osamu

    2013-08-01

    We have studied the properties of AlN layers grown by low-pressure hydride vapor phase epitaxy (HVPE) on n-plane (11bar 23) sapphire substrates and compared them with those of AlN layers on a-plane (11bar 20) sapphire substrates. c-Plane AlN was grown on a-plane sapphire. In the case of AlN growth on n-plane sapphire, the c-axis of AlN was tilted by about 1.2° relative to the n-axis of sapphire, unlike AlN growth on a-plane sapphire. For AlN grown on a-plane sapphire, the in-plane epitaxial relationship between AlN and sapphire changed with nitridation temperature in the initial-stage of growth, but it remained constant for AlN grown on n-plane sapphire.

  16. High-Pressure Water-Vapor Annealing for Enhancement of a-Si:H Film Passivation of Silicon Surface

    NASA Astrophysics Data System (ADS)

    Guo, Chun-Lin; Wang, Lei; Zhang, Yan-Rong; Zhou, Hai-Feng; Liang, Feng; Yang, Zhen-Hui; Yang, De-Ren

    2014-10-01

    We investigate the effect of amorphous hydrogenated silicon (a-Si:H) films passivated on silicon surfaces based on high-pressure water-vapor annealing (HWA). The effective carrier lifetime of samples reaches the maximum value after 210°C, 90min HWA. Capacitance-voltage measurement reveals that the HWA not only greatly reduces the density of interface states (Dit), but also decreases the fixed charges (Qfixed) mainly caused by bulk defects. The change of hydrogen and oxygen in the film is measured by a spectroscopic ellipsometer and a Fourier-transform infrared (FTIR) spectrometer. All these results show that HWA is a useful method to improve the passivation effect of a-Si:H films deposited on silicon surfaces.

  17. The Liquid-Solid Transition of Xenon on Graphite: a Vapor Pressure Isotherm Study of Two-Dimensional Melting.

    NASA Astrophysics Data System (ADS)

    Colella, Nicholas John

    We have performed a high precision vapor-pressure isotherm study of the melting transition of near monolayer xenon adsorbed on Union Carbide's ZYX exfoliated graphite. The data are analyzed in terms of the film isothermal compressibility, K(,T). We identify a sharp peak in K(,T), which occurs in the low temperature data, as a first order melting transition. As the temperature is increased, the amplitude of the peak decreases, reaching zero at a tricritical temperature, T(,trc) = 152 (+OR-) 6 K. On the basis of our results and the results of other studies, we conclude that the melting is continuous above this temperature. A temperature independent, weak and relatively broad contribution to K(,T) underlies the sharp peak at all temperatures studied; we discuss possible origins of this component.

  18. Effect of Phase Purity on Dislocation Density of Pressurized-Reactor Metalorganic Vapor Phase Epitaxy Grown InN

    NASA Astrophysics Data System (ADS)

    Iwabuchi, Takuya; Liu, Yuhuai; Kimura, Takeshi; Zhang, Yuantao; Prasertsuk, Kiattiwut; Watanabe, Haruna; Usami, Noritaka; Katayama, Ryuji; Matsuoka, Takashi

    2012-04-01

    The effect of the metastable zincblende (ZB) InN inclusion in the stable wurtzite (WZ) InN on the threading dislocation densities (TDDs) of an InN film grown by pressurized-reactor metalorganic vapor phase epitaxy has been studied by X-ray diffraction measurements. InN films are directly grown on c-plane sapphire substrates with nitrided surfaces at 1600 Torr with the different growth temperature from 500 to 700 °C. Films including ZB-InN show the correlation between the ZB volume fraction and the edge component of TDDs, not the screw component of TDDs. This result can be crystallographically understood by a simple model explaining how the ZB structure is included, i.e., ZB domains existing side-by-side with WZ domains and twined ZB domains. This can be clearly observed by electron backscatter diffraction.

  19. Vapor pressures of solid hydrates of nitric acid - Implications for polar stratospheric clouds

    NASA Technical Reports Server (NTRS)

    Worsnop, Douglas R.; Fox, Lewis E.; Zahniser, Mark S.; Wofsy, Steven C.

    1993-01-01

    Thermodynamic data are presented for hydrates of nitric acid: HNO3.H2O, HNO3.2H2O, HNO3.3H2O, and a higher hydrate. Laboratory data indicate that nucleation and persistence of metastable HNO3.2H2O may be favored in polar stratospheric clouds over the slightly more stable HNO3.3H2O. Atmospheric observations indicate that some polar stratospheric clouds may be composed of HNO3.2H2O and HNO3.3H2O. Vapor transfer from HNO3.2H2O to HNO3.3H2O could be a key step in the sedimentation of HNO3, which plays an important role in the depletion of polar ozone.

  20. Vapor pressures of solid hydrates of nitric Acid: implications for polar stratospheric clouds.

    PubMed

    Worsnop, D R; Zahniser, M S; Fox, L E; Wofsy, S C

    1993-01-01

    Thermodynamic data are presented for hydrates of nitric acid: HNO(3).H(2)O, HNO(3).2H(2)O, HNO(3).3H(2)O, and a higher hydrate. Laboratory data indicate that nucleation and persistence of metastable HNO(3).2H(2)O may be favored in polar stratospheric clouds over the slightly more stable HNO(3).3H(2)O. Atmospheric observations indicate that some polar stratospheric clouds may be composed of HNO(3).2H(2)O and HNO(3).3H(2)O. Vapor transfer from HNO(3).2H(2)O to HNO(3).3H(2)O could be a key step in the sedimentation of HNO(3), which plays an important role in the depletion of polar ozone. PMID:17757475

  1. Considerations for osmolality measurement under elevated pCO(2): comparison of vapor pressure and freezing point osmometry.

    PubMed

    Schmelzer, A E; deZengotita, V M; Miller, W M

    2000-01-20

    Osmolality increases with pCO(2) in bioreactors with pH control, and it has been shown that osmolality compensation by decreasing the basal NaCl concentration partially mitigates the adverse effects of elevated pCO(2) on animal cell growth, protein production, and glycosylation. Thus, measurement of osmolality is important for a complete characterization of the culture environment under elevated pCO(2). However, osmolality measurement may be compromised by CO(2) evolution. Freezing point depression and vapor pressure depression osmometry were directly compared for the measurement of osmolality in samples at elevated pCO(2) (up to 250 mmHg) and at a variety of pH values (6.7-7.5). More extensive degassing may be expected with the vapor pressure osmometer due to the smaller sample volume and larger surface area employed. However, both types of osmometer yielded similar results for all pCO(2) and pH values studied. Moreover, the measured values agreed with osmolality values calculated using a semi-empirical model. Further analysis showed that, while sample degassing may result in a large decrease in pCO(2), there is little associated decrease in osmolality. The great majority of total CO(2) in solution is present as bicarbonate (HCO(3)(-)). Although a small amount of HCO(3)(-) is converted to CO(2) to compensate for CO(2) evolution, further depletion of HCO(3)(-) is inhibited by the associated increase in medium pH and by the need for HCO(3)(-) to maintain charge neutrality in solution. This explanation is consistent with the observed similarity in osmolality values for the two types of osmometer. It was also observed that osmolality did not change in samples that were frozen at -20 degrees C for up to 1 year. PMID:10592516

  2. Saturation of the surface field with external bias for metalorganic chemical vapor deposition epilayer GaAs\\/GaAs as determined by electroreflection spectroscopy

    Microsoft Academic Search

    Henry Poras; George J. Goldsmith; Noren Pan

    1992-01-01

    The strength of the surface field on GaAs epitaxial layers of various thicknesses and doping concentrations grown by metalorganic chemical vapor deposition on a semi-insulating GaAs substrate was studied as a function of applied bias using modulation spectroscopy. While for small applied potentials the square of the field strength increases linearly with respect to reverse bias, for larger values of

  3. Buoyancy-Driven Heat Transfer During Application of a Thermal Gradient for the Study of Vapor Deposition at Low Pressure Using and Ideal Gas

    NASA Technical Reports Server (NTRS)

    Frazier, D. O.; Hung, R. J.; Paley, M. S.; Penn, B. G.; Long, Y. T.

    1996-01-01

    A mathematical model has been developed to determine heat transfer during vapor deposition of source materials under a variety of orientations relative to gravitational accelerations. The model demonstrates that convection can occur at total pressures as low as 10-2 mm Hg. Through numerical computation, using physical material parameters of air, a series of time steps demonstrates the development of flow and temperature profiles during the course of vapor deposition. These computations show that in unit gravity vapor deposition occurs by transport through a fairly complicated circulating flow pattern when applying heat to the bottom of the vessel with parallel orientation with respect to the gravity vector. The model material parameters for air predict the effect of kinematic viscosity to be of the same order as thermal diffusivity, which is the case for Prandtl number approx. 1 fluids. Qualitative agreement between experiment and the model indicates that 6-(2-methyl-4-nitroanilino)-2,4-hexadiyn-l-ol (DAMNA) at these pressures indeed approximates an ideal gas at the experiment temperatures, and may validate the use of air physical constants. It is apparent that complicated nonuniform temperature distribution in the vapor could dramatically affect the homogeneity, orientation, and quality of deposited films. The experimental test i's a qualitative comparison of film thickness using ultraviolet-visible spectroscopy on films generated in appropriately oriented vapor deposition cells. In the case where heating of the reaction vessel occurs from the top, deposition of vapor does not normally occur by convection due to a stable stratified medium. When vapor deposition occurs in vessels heated at the bottom, but oriented relative to the gravity vector between these two extremes, horizontal thermal gradients induce a complex flow pattern. In the plane parallel to the tilt axis, the flow pattern is symmetrical and opposite in direction from that where the vessel is positioned vertically. The ground-based experiments are sufficient preliminary tests of theory and should be of significant interest regarding vapor deposited films in microgravity.

  4. Surface structure, composition, and polarity of indium nitride grown by high-pressure chemical vapor deposition

    E-print Network

    Dietz, Nikolaus

    Surface structure, composition, and polarity of indium nitride grown by high-pressure chemical of the surface was observed, N-polarity indium nitride is indicated. © 2006 American Institute of Physics. DOI: 10.1063/1.2187513 Research on the growth and characterization of indium nitride InN has increased

  5. EFFECTS OF WATER VAPOR PRESSURE DIFFERENCE ON LEAF GAS EXCHANGE IN A POTATO AND SORGHUM AT AMBIENT AND ELEVATED CARBON DIOXIDE UNDER FIELD CONDITIONS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    High leaf to air water vapor pressure differences (D) often substantially reduce rates of assimilation of carbon dioxide (A), especially in C3 species. Rising concentrations of carbon dioxide in the atmosphere could reduce the sensitivity of A to partial stomatal closure caused by high D by a varie...

  6. Subatmospheric vapor pressures for fluoromethane (R41), 1,1-difluoroethane (R152a), and 1,1,1-trifluoroethane (R143a) evaluated from internal-energy measurements

    SciTech Connect

    Duarte-Garza, H.A.; Magee, J.W.

    1999-09-01

    Vapor pressures were evaluated from measured internal-energy changes {Delta}U{sup (2)} in the vapor + liquid two-phase region. The method employed a thermodynamic relationship between the derivative quantity ({partial_derivative}U{sup (2)}/{partial_derivative}V){sub T}, the vapor pressure p{sub {sigma}}, and its temperature derivative ({partial_derivative}p/{partial_derivative}T){sub {sigma}}. This method was applied at temperatures between the triple point and the normal boiling point of three substances: fluoromethane (R41), 1,1-difluoroethane (R152a), and 1,1,1-trifluoroethane (R143a). In the case of R41, vapor pressures up to 1 MPa were calculated to validate the technique at higher pressures. For R152a, the calculated vapor pressure at the triple-point temperature differed from a direct experimental measurement by less than the claimed uncertainty (5 Pa) of the measurement. The calculated vapor pressures for R41 helped to resolve discrepancies in several published vapor pressure sources. Agreement with experimentally measured vapor pressures for R152a and for R143a near the normal boiling point (101.325 kPa) was within the experimental uncertainty of approximately 0.04 kPa (0.04%) for the published measurements.

  7. Vapor pressures of solid hydrates of nitric acid: Implications for polar stratospheric clouds

    SciTech Connect

    Worsnop, D.R.; Zahniser, M.S. (Aerodyne Research, Inc., Billerica, MA (United States)); Fox, L.E.; Wofsy, S.C. (Harvard Univ., Cambridge, MA (United States))

    1993-01-01

    Thermodynamic data are presented for hydrates of nitric acid: HNO[sub 3][center dot]H[sub 2]O, HNO[sub 3][center dot]2H[sub 2]O, HNO[sub 3][center dot]3H[sub 2]O, and a higher hydrate. Laboratory data indicate that nucleation and persistence of metastable HNO[sub 3][center dot]2H[sub 2]O may be favored in polar stratospheric clouds over the slightly more stable HNO[sub 3][center dot]3H[sub 2]O. Atmospheric observations indicate that some polar stratospheric clouds may be composed of HNO[sub 3][center dot]2H[sub 2]O and HNO[sub 3][center dot]3H[sub 2]O. Vapor transfer from HNO[sub 3][center dot]2H[sub 2]O to HNO[sub 3][center dot]3H[sub 2]O could be a key step in the sedimentation of HNO[sub 3], which plays an important role in the depletion of polar ozone.

  8. Studies of air, water, and ethanol vapor atmospheric pressure plasmas for antimicrobial applications.

    PubMed

    Ferrell, James R; Bogovich, Erinn R; Lee, Nicholas R; Gray, Robert L; Pappas, Daphne D

    2015-01-01

    The generation of air-based plasmas under atmospheric plasma conditions was studied to assess their antimicrobial efficacy against commonly found pathogenic bacteria. The mixture of initial gases supplied to the plasma was found to be critical for the formation of bactericidal actives. The optimal gas ratio for bactericidal effect was determined to be 99% nitrogen and 1% oxygen, which led to a 99.999% reduction of a pathogenic strain of Escherichia coli on stainless steel surfaces. The experimental substrate, soil load on the substrate, flow rate of the gases, and addition of ethanol vapor all were found to affect antimicrobial efficacy of studied plasmas. Optical emission spectroscopy was used to identify the species that were present in the plasma bulk phase for multiple concentrations of nitrogen and oxygen ratios. The collected spectra indicate a unique series of bands present in the ultraviolet region of the electromagnetic spectrum that can be attributed to nitric oxide species known to be highly antimicrobial. This intense spectral profile dramatically changes as the concentration of nitrogen decreases. PMID:25810273

  9. Dynamics of a Spherical Vapor\\/Gas Bubble in Varying Pressure Fields

    Microsoft Academic Search

    Hisanobu Kawashima; Masaharu Kameda

    2008-01-01

    A mathematical model is developed to simulate the radial motion of cavitation bubbles. The heat and mass transports including phase change are formulated precisely. In order to reduce the computational cost without loss of the important thermo-fluid phenomena, two simplifications are employed: time-dependent bubble radius is described using the Rayleigh-Plesset equation; the pressure in the bubble is assumed to be

  10. Synthesis of Ordered Mesoporous Phenanthrenequinone-Carbon via ?-? Interaction-Dependent Vapor Pressure for Rechargeable Batteries

    PubMed Central

    Kwon, Mi-Sook; Choi, Aram; Park, Yuwon; Cheon, Jae Yeong; Kang, Hyojin; Jo, Yong Nam; Kim, Young-Jun; Hong, Sung You; Joo, Sang Hoon; Yang, Changduk; Lee, Kyu Tae

    2014-01-01

    The ?-? interaction-dependent vapour pressure of phenanthrenequinone can be used to synthesize a phenanthrenequinone-confined ordered mesoporous carbon. Intimate contact between the insulating phenanthrenequinone and the conductive carbon framework improves the electrical conductivity. This enables a more complete redox reaction take place. The confinement of the phenanthrenequinone in the mesoporous carbon mitigates the diffusion of the dissolved phenanthrenequinone out of the mesoporous carbon, and improves cycling performance. PMID:25490893

  11. Calibrated vapor generator source

    DOEpatents

    Davies, John P. (Idaho Falls, ID); Larson, Ronald A. (Idaho Falls, ID); Goodrich, Lorenzo D. (Shelley, ID); Hall, Harold J. (Idaho Falls, ID); Stoddard, Billy D. (Idaho Falls, ID); Davis, Sean G. (Idaho Falls, ID); Kaser, Timothy G. (Idaho Falls, ID); Conrad, Frank J. (Albuquerque, NM)

    1995-01-01

    A portable vapor generator is disclosed that can provide a controlled source of chemical vapors, such as, narcotic or explosive vapors. This source can be used to test and calibrate various types of vapor detection systems by providing a known amount of vapors to the system. The vapor generator is calibrated using a reference ion mobility spectrometer. A method of providing this vapor is described, as follows: explosive or narcotic is deposited on quartz wool, placed in a chamber that can be heated or cooled (depending on the vapor pressure of the material) to control the concentration of vapors in the reservoir. A controlled flow of air is pulsed over the quartz wool releasing a preset quantity of vapors at the outlet.

  12. Calibrated vapor generator source

    DOEpatents

    Davies, J.P.; Larson, R.A.; Goodrich, L.D.; Hall, H.J.; Stoddard, B.D.; Davis, S.G.; Kaser, T.G.; Conrad, F.J.

    1995-09-26

    A portable vapor generator is disclosed that can provide a controlled source of chemical vapors, such as, narcotic or explosive vapors. This source can be used to test and calibrate various types of vapor detection systems by providing a known amount of vapors to the system. The vapor generator is calibrated using a reference ion mobility spectrometer. A method of providing this vapor is described, as follows: explosive or narcotic is deposited on quartz wool, placed in a chamber that can be heated or cooled (depending on the vapor pressure of the material) to control the concentration of vapors in the reservoir. A controlled flow of air is pulsed over the quartz wool releasing a preset quantity of vapors at the outlet. 10 figs.

  13. Long Term Measurement of the Vapor Pressure of Gold in the Au-C System

    NASA Technical Reports Server (NTRS)

    Copland, Evan H.

    2009-01-01

    Incorporating the {Au(s,l) + graphite} reference in component activity measurements made with the multiple effusion-cell vapor source mass spectrometry (multicell KEMS) technique provides a fixed temperature defining ITS-90 (T(sub mp)(Au) = 1337.33K) and a systematic method to check accuracy. Over a 2 year period delta H sub(298)Au was determined by the 2nd and 3rd law methods in 25 separate experiments and were in the ranges 362.2 plus or minus 3.3 kJmol(sup -1) and 367.8 plus or minus 1.1 kJmol(sup -1), respectively. This 5 kJmol-1 discrepancy is transferred directly to the measured activities. This is unacceptable and the source of this discrepancy needs to be understood and corrected. Accepting the 2nd law value increases p(Au) by about 50 percent, brings the 2nd and 3rd law values into agreement and removes the T dependence in the 3rd law values. While compelling, there is no way to independently determine instrument sensitivities, S(sub Au), with T in a single experiment with KEMS. This lack of capability is stopping a deeper understanding of this problem. In addition, the Au-C phase diagram suggests a eutectic invariant reaction: L-Au(4.7at%C) = FCC-Au(0.08at%C) + C(graphite) at T(sub e) approximately 1323K. This high C concentration in Au(l) must reduce p(Au) in equilibrium with {Au(s,l) + graphite} and raises some critical questions about the Gibbs free energy functions of Au(s,l) and the Au fixed point (T(sub mp)(Au) = 1337.33K) which is always measured in graphite.

  14. Cellulose ?18O is an index of leaf-to-air vapor pressure difference (VPD) in tropical plants

    PubMed Central

    Kahmen, Ansgar; Sachse, Dirk; Arndt, Stefan K.; Tu, Kevin P.; Farrington, Heraldo; Vitousek, Peter M.; Dawson, Todd E.

    2011-01-01

    Cellulose in plants contains oxygen that derives in most cases from precipitation. Because the stable oxygen isotope composition, ?18O, of precipitation is associated with environmental conditions, cellulose ?18O should be as well. However, plant physiological models using ?18O suggest that cellulose ?18O is influenced by a complex mix of both climatic and physiological drivers. This influence complicates the interpretation of cellulose ?18O values in a paleo-context. Here, we combined empirical data analyses with mechanistic model simulations to i) quantify the impacts that the primary climatic drivers humidity (ea) and air temperature (Tair) have on cellulose ?18O values in different tropical ecosystems and ii) determine which environmental signal is dominating cellulose ?18O values. Our results revealed that ea and Tair equally influence cellulose ?18O values and that distinguishing which of these factors dominates the ?18O values of cellulose cannot be accomplished in the absence of additional environmental information. However, the individual impacts of ea and Tair on the ?18O values of cellulose can be integrated into a single index of plant-experienced atmospheric vapor demand: the leaf-to-air vapor pressure difference (VPD). We found a robust relationship between VPD and cellulose ?18O values in both empirical and modeled data in all ecosystems that we investigated. Our analysis revealed therefore that ?18O values in plant cellulose can be used as a proxy for VPD in tropical ecosystems. As VPD is an essential variable that determines the biogeochemical dynamics of ecosystems, our study has applications in ecological-, climate-, or forensic-sciences. PMID:21245322

  15. Dependence of Waterflood Remaining Oil Saturation on Relative Permeability, Capillary Pressure, and Reservoir Parameters in Mixed-Wet Turbidite Sands

    Microsoft Academic Search

    G. J. Hirasaki

    1996-01-01

    The dependence of waterflood oil recovery on relative permeability, capillary pressure, and reservoir parameters was investigated by numerical simulation. The relative permeability and capillary pressure curves were based on laboratory measurements on unconsolidated sands. The water-wet case is based on the assumption that the system is water-wet and measurements were made with refined oil. The mixed-wet case assumed that the

  16. Three-dimensional modelling of horizontal chemical vapor deposition. I - MOCVD at atmospheric pressure

    NASA Technical Reports Server (NTRS)

    Ouazzani, Jalil; Rosenberger, Franz

    1990-01-01

    A systematic numerical study of the MOCVD of GaAs from trimethylgallium and arsine in hydrogen or nitrogen carrier gas at atmospheric pressure is reported. Three-dimensional effects are explored for CVD reactors with large and small cross-sectional aspect ratios, and the effects on growth rate uniformity of tilting the susceptor are investigated for various input flow rates. It is found that, for light carrier gases, thermal diffusion must be included in the model. Buoyancy-driven three-dimensional flow effects can greatly influence the growth rate distribution through the reactor. The importance of the proper design of the lateral thermal boundary conditions for obtaining layers of uniform thickness is emphasized.

  17. Effect of water vapor on sound absorption in nitrogen at low frequency/pressure ratios

    NASA Technical Reports Server (NTRS)

    Zuckerwar, A. J.; Griffin, W. A.

    1981-01-01

    Sound absorption measurements were made in N2-H2O binary mixtures at 297 K over the frequency/pressure range f/P of 0.1-2500 Hz/atm to investigate the vibrational relaxation peak of N2 and its location on f/P axis as a function of humidity. At low humidities the best fit to a linear relationship between the f/P(max) and humidity yields an intercept of 0.013 Hz/atm and a slope of 20,000 Hz/atm-mole fraction. The reaction rate constants derived from this model are lower than those obtained from the extrapolation of previous high-temperature data.

  18. A model for the effective diffusion of gas or the vapor phase in a fractured media unsaturated zone driven by periodic atmospheric pressure fluctuations

    SciTech Connect

    Vold, E.L.

    1997-03-01

    There is evidence for migration of tritiated water vapor through the tuff in the unsaturated zone from the buried disposal shafts located on a narrow mesa top at Area G, Los Alamos, NM. Field data are consistent with an effective in-situ vapor phase diffusion coefficient of 1.5x10{sup {minus}3} m{sup s}/s, or a factor of 60 greater than the binary diffusion coefficient for water vapor in air. A model is derived to explain this observation of anomolously large diffusion, which relates an effective vapor or gas phase diffusion coefficient in the fractured porous media to the subsurface propagation of atmospheric pressure fluctuations (barometric pumping). The near surface (unattenuated) diffusion coefficient is independent of mode period under the simplified assumptions of a complete {open_quote}mixing mechanism{close_quote} for the effective diffusion process. The unattenuated effective diffusion driven by this barometric pumping is proportional to an average media permeability times the sum of the square of pressure mode amplitudes, while the attenuation length is proportional to the squarer root of the product of permeability times mode period. There is evidence that the permeability needed to evaluate the pressure attenuation length is the in-situ value, approximately that of the matrix. The diffusion which results using Area G parameter values is negligible in the matrix but becomes large at the effective permeability of the fractured tuff matrix. The effective diffusion coefficient predicted by this model, due to pressure fluctuations and the observed fracture characteristics, is in good agreement with the observed in-situ diffusion coefficient for tritium field measurements. It is concluded that barometric pumping in combination with the enhanced permeability of the fractured media is a likely candidate to account for the observed in-field migration of vapor in the near surface unsaturated zone at Area G.

  19. Vapor Pressures and Vaporization Enthalpies of the n-Alkanes from C21 to C30 at T ) 298.15 K by Correlation Gas Chromatography

    E-print Network

    Chickos, James S.

    by Correlation Gas Chromatography James S. Chickos* and William Hanshaw Department of Chemistry and Biochemistry of transfer from solution to the gas phase as measured by gas chromatography.3 A plot of the vaporization interest in using the larger n-alkanes as stan- dards for correlation gas chromatography measurements (c

  20. Saturation properties of 1-alkyl-3-methylimidazolium based ionic liquids.

    PubMed

    Rane, Kaustubh S; Errington, Jeffrey R

    2014-07-24

    We study the liquid-vapor saturation properties of room temperature ionic liquids (RTILs) belonging to the homologous series 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Cnmim][NTf2]) using Monte Carlo simulation. We examine the effect of temperature and cation alkyl chain length n on the saturated densities, vapor pressures, and enthalpies of vaporization. These properties are explicitly calculated for temperatures spanning from 280 to 1000 K for RTILs with n = 2, 4, 6, 8, 10, and 12. We also explore how the identity of the anion influences saturation properties. Specifically, we compare results for [C(4)mim][NTf2] with those for 1-butyl-3-methylimidazolium tetrafluoroborate ([C(4)mim][BF4]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)mim][PF6]). Simulations are completed with a recently developed realistic united-atom force field. A combination of direct grand canonical and isothermal-isobaric temperature expanded ensemble simulations are used to construct phase diagrams. Our results are compared with experimental data and Gibbs ensemble simulation data. Overall, we find good agreement between our results and those measured experimentally. We find that the vapor pressures and enthalpies of vaporization show a strong dependence on the size of the alkyl chain at low temperatures, whereas no particular trend is observed at high temperatures. Finally, we also discuss the effect of temperature on liquid phase nanodomains observed in RTILs with large hydrophobic groups. We do not observe a drastic change in liquid phase structure upon variation of the temperature, which suggests there is not a sharp phase transition between a nanostructured and homogeneous liquid, as has been suggested in earlier studies. PMID:24986360

  1. Photosynthesis Decrease and Stomatal Control of Gas Exchange in Abies alba Mill. in Response to Vapor Pressure Difference.

    PubMed

    Guehl, J M; Aussenac, G

    1987-02-01

    The responses of steady state CO(2) assimilation rate (A), transpiration rate (E), and stomatal conductance (g(s)) to changes in leaf-to-air vapor pressure difference (DeltaW) were examined on different dates in shoots from Abies alba trees growing outside. In Ecouves, a provenance representative of wet oceanic conditions in Northern France, both A and g(s) decreased when DeltaW was increased from 4.6 to 14.5 Pa KPa(-1). In Nebias, which represented the dry end of the natural range of A. alba in southern France, A and g(s) decreased only after reaching peak levels at 9.0 and 7.0 Pa KPa(-1), respectively. The representation of the data in assimilation rate (A) versus intercellular CO(2) partial pressure (C(i)) graphs allowed us to determine how stomata and mesophyll photosynthesis interacted when DeltaW was increased. Changes in A were primarily due to alterations in mesophyll photosynthesis. At high DeltaW, and especially in Ecouves when soil water deficit prevailed, A declined, while C(i) remained approximately constant, which may be interpreted as an adjustment of g(s) to changes in mesophyll photosynthesis. Such a stomatal control of gas exchange appeared as an alternative to the classical feedforward interpretation of E versus DeltaW responses with a peak rate of E. The gas exchange response to DeltaW was also characterized by considerable deviations from the optimization theory of IR Cowan and GD Farquhar (1977 Symp Soc Exp Biol 31: 471-505). PMID:16665243

  2. Photocatalytic Functional Coating of TiO2 Thin Film Deposited by Cyclic Plasma Chemical Vapor Deposition at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Kwon, Jung-Dae; Rha, Jong-Joo; Nam, Kee-Seok; Park, Jin-Seong

    2011-08-01

    Photocatalytic TiO2 thin films were prepared with titanium tetraisopropoxide (TTIP) using cyclic plasma chemical vapor deposition (CPCVD) at atmospheric pressure. The CPCVD TiO2 films contain carbon-free impurities up to 100 °C and polycrystalline anatase phases up to 200 °C, due to the radicals and ion-bombardments. The CPCVD TiO2 films have high transparency in the visible wavelength region and absorb wavelengths below 400 nm (>3.2 eV). The photocatalytic effects of the CPCVD TiO2 and commercial sprayed TiO2 films were measured by decomposing methylene blue (MB) solution under UV irradiation. The smooth CPCVD TiO2 films showed a relatively lower photocatalytic efficiency, but superior catalyst-recycling efficiency, due to their high adhesion strength on the substrates. This CPCVD technique may provide the means to produce photocatalytic thin films with low cost and high efficiency, which would be a reasonable candidate for practical photocatalytic applications, because of the reliability and stability of their photocatalytic efficiency in a practical environment.

  3. High Temperature Nanocomposites For Nuclear Thermal Propulsion and In-Space Fabrication by Hyperbaric Pressure Laser Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Maxwell, J. L.; Webb, N. D.; Espinoza, M.; Cook, S.; Houts, M.; Kim, T.

    Nuclear Thermal Propulsion (NTP) is an indispensable technology for the manned exploration of the solar system. By using Hyperbaric Pressure Laser Chemical Vapor Deposition (HP-LCVD), the authors propose to design and build a promising next-generation fuel element composed of uranium carbide UC embedded in a latticed matrix of highly refractory Ta4HfC5 for an NTP rocket capable of sustaining temperatures up to 4000 K, enabling an Isp of up to 1250 s. Furthermore, HP-LCVD technology can also be harnessed to enable 3D rapid prototyping of a variety of materials including metals, ceramics and composites, opening up the possibility of in-space fabrication of components, replacement parts, difficult-to-launch solar sails and panels and a variety of other space structures. Additionally, rapid prototyping with HP-LCVD makes a feasible "live off the land" strategy of interplanetary and interstellar exploration ­ the precursors commonly used in the technology are found, often in abundance, on other solar system bodies either as readily harvestable gas (e.g. methane) or as a raw material that could be converted into a suitable precursor (e.g. iron oxide into ferrocene on Mars).

  4. Stability of streambanks formed in partially saturated soils and effects of negative pore water pressures: the Sieve River (Italy)

    Microsoft Academic Search

    Massimo Rinaldi; Nicola Casagli

    1999-01-01

    Streambanks of alluvial channels are usually composed of loose materials, which are unsaturated in ambient conditions. Unsaturated soils are subject to negative pore water pressures, which cause an apparent cohesion. The latter is the main factor in allowing the stability of near-vertical banks. Even during moderate in-bank flow events, the apparent cohesion can be strongly reduced as the material approaches

  5. In Situ Measurement, Characterization, and Modeling of Two-Phase Pressure Drop Incorporating Local Water Saturation in PEMFC Gas Channels

    NASA Astrophysics Data System (ADS)

    See, Evan J.

    Proton Exchange Membrane Fuel Cells (PEMFCs) have been an area of focus as an alternative for internal combustion engines in the transportation sector. Water and thermal management techniques remain as one of the key roadblocks in PEMFC development. The ability to model two-phase flow and pressure drop in PEMFCs is of significant importance to the performance and optimization of PEMFCs. This work provides a perspective on the numerous factors that affect the two-phase flow in the gas channels and presents a comprehensive pressure drop model through an extensive in situ fuel cell investigation. The study focused on low current density and low temperature operation of the cell, as these conditions present the most challenging scenario for water transport in the PEMFC reactant channels. Tests were conducted using two PEMFCs that were representative of the actual full scale commercial automotive geometry. The design of the flow fields allowed visual access to both cathode and anode sides for correlating the visual observations to the two-phase flow patterns and pressure drop. A total of 198 tests were conducted varying gas diffusion layer (GDL), inlet humidity, current density, and stoichiometry; this generated over 1500 average pressure drop measurements to develop and validate two-phase models. A two-phase 1+1 D modeling scheme is proposed that incorporates an elemental approach and control volume analysis to provide a comprehensive methodology and correlation for predicting two-phase pressure drop in PEMFC conditions. Key considerations, such as condensation within the channel, consumption of reactant gases, water transport across the membrane, and thermal gradients within the fuel cell, are reviewed and their relative importance illustrated. The modeling scheme is shown to predict channel pressure drop with a mean error of 10% over the full range of conditions and with a mean error of 5% for the primary conditions of interest. The model provides a unique and comprehensive basis for developing a fundamental adiabatic two-phase flow pressure drop predictive scheme for PEMFC reactant channels.

  6. Real-Time Optical Monitoring and Simulations of Gas Phase Kinetics in InN Vapor Phase Epitaxy at High Pressure

    NASA Technical Reports Server (NTRS)

    Dietz, Nikolaus; Woods, Vincent; McCall, Sonya D.; Bachmann, Klaus J.

    2003-01-01

    Understanding the kinetics of nucleation and coalescence of heteroepitaxial thin films is a crucial step in controlling a chemical vapor deposition process, since it defines the perfection of the heteroepitaxial film both in terms of extended defect formation and chemical integrity of the interface. The initial nucleation process also defines the film quality during the later stages of film growth. The growth of emerging new materials heterostructures such as InN or In-rich Ga(x)In(1-x)N require deposition methods operating at higher vapor densities due to the high thermal decomposition pressure in these materials. High nitrogen pressure has been demonstrated to suppress thermal decomposition of InN, but has not been applied yet in chemical vapor deposition or etching experiments. Because of the difficulty with maintaining stochiometry at elevated temperature, current knowledge regarding thermodynamic data for InN, e.g., its melting point, temperature-dependent heat capacity, heat and entropy of formation are known with far less accuracy than for InP, InAs and InSb. Also, no information exists regarding the partial pressures of nitrogen and phosphorus along the liquidus surfaces of mixed-anion alloys of InN, of which the InN(x)P(1-x) system is the most interesting option. A miscibility gap is expected for InN(x)P(1-x) pseudobinary solidus compositions, but its extent is not established at this point by experimental studies under near equilibrium conditions. The extension of chemical vapor deposition to elevated pressure is also necessary for retaining stoichiometric single phase surface composition for materials that are characterized by large thermal decomposition pressures at optimum processing temperatures.

  7. In-situ, high pressure and temperature experimental determination of hydrogen isotope fractionation between coexisting hydrous melt and silicate-saturated aqueous fluid

    NASA Astrophysics Data System (ADS)

    Mysen, B. O.

    2012-12-01

    Hydrogen isotope fractionation between water-saturated silicate melt and silicate-saturated aqueous fluid has been determined experimentally, in-situ with the samples in the 450-800C and 101-1567 MPa temperature and pressure range, respectively. The temperatures are, therefore higher than those where hydrogen bonding in fluids and melts is important [1]. The experiments were conducted with a hydrothermal diamond anvil cell (HDAC) as the high-temperature/-pressure tool and vibrational spectroscopy to determine D/H fractionation. Compositions were along the haploandesite join, Na2Si4O9 - Na2(NaAl)4O9 [Al/(Al+Si)=0-0.1], and a 50:50 (by volume) H2O:D2O fluid mixture as starting material. Platinum metal was used to enhance equilibration rate. Isotopic equilibrium was ascertained by using variable experimental duration at given temperature and pressure. In the Al-free Na-silicate system, the enthalpy change of the (D/H) equilibrium of fluid is 3.1±0.7 kJ/mol, whereas for coexisting melt, ?H=0 kJ/mol within error. With Al/(Al+Si)=0.1, ?H=5.2±0.9 kJ/mol for fluid and near 0 within error for coexisting melt melt. For the exchange equilibrium between melt and fluid, H2O(melt)+D2O(fluid)=H2O(fluid)+D2O(melt), the ?H=4.6±0.7 and 6.5±0.7 kJ/mol for the two Al-free and Al-bearing compositions, respectively, respectively. The D/H equilibration within fluids and melts and, therefore, D/H partitioning between coexisting fluid and melt reflect the influence of dissolved H2O(D2O) in melts and dissolved silicate components in H2O(D2O) fluid on their structure. The positive temperature- and pressure-dependence of silicate solubility and on silicate structure in silicate-saturated aqueous fluid governs the D/H fractionation in the fluid because increasing silicate solute concentration in fluid results in silicate polymerization [2]. These structural effects may be analogous to observed solute-dependent oxygen isotope fractionation between brine and CO2 [3]. In the temperature- and pressure range of the experiments discussed here, water in melts is much less important than silicate in aqueous fluid because even at the lowest temperature and pressure conditions studied (450C/101 MPa), the water content in the melt is so high (> 4 wt%) that further increase in total water by increasing temperature and pressure predominantly increases the concentration of molecular H2O in the melts. Water dissolved in molecular form does not affect the silicate melt structure significantly. Therefore, in the deep crust and upper mantle, isotope fractionation factors between fluid and condensed silicate materials (melts and minerals) can differ substantially from isotope fractionation between pure H2O condensed silicate materials. [1] Foustoukos, D. I., and Mysen, B. O. (2012), Geochim. Cosmochim. Acta, 86, 88-102. [2] Mysen, B. O. (2010), Amer. Mineral., 95, 1807-1816. [3] O'Neil, J. R., and Truesdell, A. E. (1993), pp. 17-25 in Stable isotope geochemistry: A tribute to Samuel Epstein, (eds.: H. P. Taylor, J. R. O'Neil and I. R. Kaplan), The Geochemical Society, Calgary.

  8. (Vapor + liquid) equilibrium data for (carbon dioxide + 1,1-difluoroethane) system at temperatures from (258 to 343) K and pressures up to about 8 MPa

    Microsoft Academic Search

    Hakim Madani; Alain Valtz; Christophe Coquelet; Abdeslam Hassen Meniai; Dominique Richon

    2008-01-01

    Accurate thermo-physical data are of utmost interest for the development of new efficient refrigeration systems. Carbon dioxide (R744) and 1,1-difluoroethane (R152a) are addressed here. Isothermal (vapor+liquid) equilibrium data are reported herein for (R744+R152a) binary system in the (258–343) K temperature range and in the (0.14 to 7.65) MPa pressure range. A reliable “static-analytic” method taking advantage of two online ROLSI™

  9. Thermodynamic Properties of Nitrogen Including Liquid and Vapor Phases from 63K to 2000K with Pressures to 10,000 Bar

    Microsoft Academic Search

    Richard T. Jacobsen; Richard B. Stewart

    1973-01-01

    Tables of thermodynamic properties of nitrogen are presented for the liquid and vapor phases for temperatures from the freezing line to 2000 K and pressures to 10,000 bar. The tables include values of density, internal energy, enthalpy, entropy, isochoric heat capacity (Cv), isobaric heat capacity (Cp), velocity of sound, the isotherm derivative (?P\\/?&rgr;)?, and the isochor derivative (?P\\/?T)&rgr;. The thermodynamic

  10. Preparation of negative electrodes for lithium-ion rechargeable battery by pressure-pulsed chemical vapor infiltration of pyrolytic carbon into electro-conductive forms

    Microsoft Academic Search

    Yoshimi Ohzawa; Masami Mitani; Takako Suzuki; Vinay Gupta; Tsuyoshi Nakajima

    2003-01-01

    The plate-type negative electrodes for lithium-ion rechargeable battery were prepared by pressure-pulsed chemical vapor infiltration of pyrolytic carbon (pyrocarbon) into two sorts of conductive porous forms, that is, the carbonized paper (A) and the TiN-coated paper (B), as the conductive fillers and\\/or current collectors. The electrodes had the three-dimensionally continuous current paths in the pyrocarbon-based anodes without the organic binders

  11. Preparation of SiC-based cellular substrate by pressure-pulsed chemical vapor infiltration into honeycomb-shaped paper preforms

    Microsoft Academic Search

    Y. Ohzawa; K. Nakane; V. Gupta; T. Nakajima

    2002-01-01

    Using a pressure-pulsed chemical vapor infiltration technique, SiC was infiltrated from a SiCl4 (4%)–CH4 (4%)–H2 gas phase into carbonized paper preforms at 1100°C. SiC-based cellular substrates with cell wall thicknesses of 25, 50 and 100 µm were obtained by using honeycomb-shaped paper preforms as the templates. The reduction of both wall thickness t and cell pitch d of SiC-based honeycomb

  12. Ionic liquids as superior solvents for headspace gas chromatography of residual solvents with very low vapor pressure, relevant for pharmaceutical final dosage forms

    Microsoft Academic Search

    Gerhard Laus; Max Andre; Gino Bentivoglio; Herwig Schottenberger

    2009-01-01

    1-n-Butyl-3-methylimidazolium dimethyl phosphate (BMIM DMP) was identified as the most suitable ionic liquid as solvent for the headspace gas chromatographic analysis of solvents with very low vapor pressure such as dimethylsulfoxide, N-methylpyrrolidone, sulfolane, tetralin, and ethylene glycol in a realistic matrix of commonly used excipients (carboxymethylcellulose, magnesium stearate, guar flour, and corn starch) in pharmaceutical products. Limits of quantification and

  13. Evaluation of Electrical Characteristics and Trap-State Density in Bottom-Gate Polycrystalline Thin Film Transistors Processed with High-Pressure Water Vapor Annealing

    Microsoft Academic Search

    Masafumi Kunii

    2006-01-01

    This paper discusses electrical characteristics and trap-state density in polycrystalline silicon (poly-Si) used in bottom-gate poly-Si thin film transistors (TFTs) processed with high-pressure water vapor annealing (HWA). The threshold voltage uniformity of the HWA-processed TFTs is improved by 42% for N-channel and 38% for P-channel TFTs in terms of standard deviation, and carrier mobility is enhanced by 10% or greater

  14. Vapor pressure determinations of 8-2 fluorortelomer alcohol and 1-H perfluorooctane by capillary gas chromatography Relative retention time versus headspace methods.

    PubMed

    Cobranchi, Daryl P; Botelho, Miguel; Buxton, L William; Buck, Robert C; Kaiser, Mary A

    2006-03-10

    Two distinctly different capillary gas chromatographic methods were used to determine the vapor pressure of 8-2 fluorotelomer alcohol (8-2 FTOH) and 1-H perfluoroheptane at several temperatures. For measurements employing the relative retention-time method, a short polymethylsiloxane column was used from 25 to 65 degrees C. For the 8-2 FTOH, hydrocarbon alcohols and perfluoroalcohols were used as reference standards. For 1-H perfluoroheptane, hydrocarbons were used as reference standards. Vapor pressure estimates could differ by as much as an order of magnitude compared to published results determined by other (nonchromatographic) methods. This variance may be a function of solvent-solute interactions within the gas chromatographic column and the infinite dilution assumption, both used in the relative retention method. For comparison, data were also gathered using headspace gas chromatography (GC) with atomic emission detection (AED). The results from this novel GC/AED method were consistent with prior nonchromatographic results. A discussion of why headspace is the preferred technique for the determination of vapor pressure for fluorinated compounds is presented. PMID:16443234

  15. Area Selective Growth of Titanium Diselenide Thin Films into Micropatterned Substrates by Low-Pressure Chemical Vapor Deposition

    PubMed Central

    2013-01-01

    The neutral, distorted octahedral complex [TiCl4(SenBu2)2] (1), prepared from the reaction of TiCl4 with the neutral SenBu2 in a 1:2 ratio and characterized by IR and multinuclear (1H, 13C{1H}, 77Se{1H}) NMR spectroscopy and microanalysis, serves as an efficient single-source precursor for low-pressure chemical vapor deposition (LPCVD) of titanium diselenide, TiSe2, films onto SiO2 and TiN substrates. X-ray diffraction patterns on the deposited films are consistent with single-phase, hexagonal 1T-TiSe2 (P3?m1), with evidence of some preferred orientation of the crystallites in thicker films. The composition and structural morphology was confirmed by scanning electron microscopy (SEM), energy dispersive X-ray, and Raman spectroscopy. SEM imaging shows hexagonal plate crystallites growing perpendicular to the substrate, but these tend to align parallel to the surface when the quantity of reagent is reduced. The resistivity of the crystalline TiSe2 films is 3.36 ± 0.05 × 10–3 ?·cm with a carrier density of 1 × 1022 cm–3. Very highly selective film growth from the reagent was observed onto photolithographically patterned substrates, with film growth strongly preferred onto the conducting TiN surfaces of SiO2/TiN patterned substrates. TiSe2 is selectively deposited within the smallest 2 ?m diameter TiN holes of the patterned TiN/SiO2 substrates. The variation in crystallite size with different diameter holes is determined by microfocus X-ray diffraction and SEM, revealing that the dimensions increase with the hole size, but that the thickness of the crystals stops increasing above ?20 ?m hole size, whereas their lengths/widths continue to increase. PMID:24489437

  16. Area Selective Growth of Titanium Diselenide Thin Films into Micropatterned Substrates by Low-Pressure Chemical Vapor Deposition.

    PubMed

    Benjamin, Sophie L; de Groot, C H Kees; Gurnani, Chitra; Hector, Andrew L; Huang, Ruomeng; Ignatyev, Konstantin; Levason, William; Pearce, Stuart J; Thomas, Fiona; Reid, Gillian

    2013-12-10

    The neutral, distorted octahedral complex [TiCl4(Se (n) Bu2)2] (1), prepared from the reaction of TiCl4 with the neutral Se (n) Bu2 in a 1:2 ratio and characterized by IR and multinuclear ((1)H, (13)C{(1)H}, (77)Se{(1)H}) NMR spectroscopy and microanalysis, serves as an efficient single-source precursor for low-pressure chemical vapor deposition (LPCVD) of titanium diselenide, TiSe2, films onto SiO2 and TiN substrates. X-ray diffraction patterns on the deposited films are consistent with single-phase, hexagonal 1T-TiSe2 (P3?m1), with evidence of some preferred orientation of the crystallites in thicker films. The composition and structural morphology was confirmed by scanning electron microscopy (SEM), energy dispersive X-ray, and Raman spectroscopy. SEM imaging shows hexagonal plate crystallites growing perpendicular to the substrate, but these tend to align parallel to the surface when the quantity of reagent is reduced. The resistivity of the crystalline TiSe2 films is 3.36 ± 0.05 × 10(-3) ?·cm with a carrier density of 1 × 10(22) cm(-3). Very highly selective film growth from the reagent was observed onto photolithographically patterned substrates, with film growth strongly preferred onto the conducting TiN surfaces of SiO2/TiN patterned substrates. TiSe2 is selectively deposited within the smallest 2 ?m diameter TiN holes of the patterned TiN/SiO2 substrates. The variation in crystallite size with different diameter holes is determined by microfocus X-ray diffraction and SEM, revealing that the dimensions increase with the hole size, but that the thickness of the crystals stops increasing above ?20 ?m hole size, whereas their lengths/widths continue to increase. PMID:24489437

  17. Multi-scale influence of vapor pressure deficit on fire ignition and spread in boreal forest ecosystems

    NASA Astrophysics Data System (ADS)

    Sedano, F.; Randerson, J. T.

    2014-07-01

    Climate-driven changes in the fire regime within boreal forest ecosystems are likely to have important effects on carbon cycling and species composition. In the context of improving fire management options and developing more realistic scenarios of future change, it is important to understand how meteorology regulates different aspects of fire dynamics, including ignition, daily fire spread, and cumulative annual burned area. Here we combined Moderate-Resolution Imaging Spectroradiometer (MODIS) active fires (MCD14ML), MODIS imagery (MOD13A1) and ancillary historic fire perimeter information to produce a data set of daily fire spread maps for Alaska during 2002-2011. This approach provided a spatial and temporally continuous representation of fire progression and a precise identification of ignition and extinction locations and dates for each wildfire. The fire-spread maps were analyzed with daily vapor pressure deficit (VPD) observations from the North American Regional Reanalysis (NARR) and lightning strikes from the Alaska Lightning Detection Network (ALDN). We found a significant relationship between daily VPD and likelihood that a lightning strike would develop into a fire ignition. In the first week after ignition, above average VPD increased the probability that fires would grow to large or very large sizes. Strong relationships also were identified between VPD and burned area at several levels of temporal and spatial aggregation. As a consequence of regional coherence in meteorology, ignition, daily fire spread, and fire extinction events were often synchronized across different fires in interior Alaska. At a regional scale, the sum of positive VPD anomalies during the fire season was positively correlated with annual burned area during the NARR era (1979-2011; R2 = 0.45). Some of the largest fires we mapped had slow initial growth, indicating opportunities may exist for suppression efforts to adaptively manage these forests for climate change. The results of our spatiotemporal analysis provide new information about temporal and spatial dynamics of wildfires and have implications for modeling the terrestrial carbon cycle.

  18. Nucleation and growth of thin film zirconia using pulsed-pressure metal-organic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Ramirez, Lynher

    Zirconia films deposited on silicon (100) substrates using pulsed-pressure metal-organic chemical vapor deposition (PP-MOCVD) with zirconium n-propoxide (ZnP) Zr(OC3H7)4 were dense and fully crystalline for substrate temperatures of 500-700°C. Film thicknesses ranged from 40 to 815 nm thick, measured after growth using ellipsometry and scanning electron microscopy (SEM). Growth rates were achieved between 0.1 mum/hr and 1 mum/hr at 500°C and 700°C, respectively. Transmission electron microscopy (TEM) and x-ray diffraction (XRD) indicated an average grain size of 10 to 20 nm. There was a random orientation of cubic/tetragonal zirconia at the highest experimental temperature of 700°C. SEM and atomic force microscopy (AFM) was used to characterize island height of discontinuous films in the initial stages of growth where defects in the substrate caused preferred nucleation of isolated particles. At later stages of growth, the average surface roughness of continuous films was 30 nm, which revealed a more uniform growth had developed. A growth model is proposed and optimal growth conditions are suggested for targeted microstructures of ZrO2 films. Zirconia films were also processed using a sol-gel spin-coating method with zirconium n-propoxide (ZnP) Zr(OC3H7)4 precursor. An evaluation between PP-MOCVD and sol-gel zirconia films derived from the same precursor reveals similar microstructures and grain sizes. Some of the sol-gel films had issues with carbon impurities, film cracking and pores, all issues non-existent in the PP-MOCVD films. The processing time for thicker films is relatively faster for the PP-MOCVD method.

  19. Synthetic fluid inclusions: VIII. Vapor-saturated halite solubility in part of the system NaCl-CaCl sub 2 -H sub 2 O, with application to fluid inclusions from oceanic hydrothermal systems

    SciTech Connect

    Vanko, D.A. (Georgia State Univ., Atlanta (USA)); Bodnar, R.J.; Sterner, S.M. (Virginia Polytechnic Institute and State Univ., Blacksburg (USA))

    1988-10-01

    Halite solubility along part of the vapor-saturated liquidus in the system NaCl-CaCl{sub 2}-H{sub 2}O has been determined using the synthetic fluid inclusion technique. Data allow the construction of liquidus isotherms for temperatures up to 500{degree}C and bulk compositions containing >60 wt% total salt and as much as 25 wt% CaCl{sub 2}. Combined with previous data for the binary system NaCl-H{sub 2}O and for the ternary system NaCl-CaCl{sub 2}-H{sub 2}O in the low-salinity, low-temperature region, a preliminary ternary phase diagram can be constructed that remains incomplete only in the CaCl{sub 2}-rich region. Results are applied to the interpretation of saline fluid inclusions from quartz veins in oceanic metagabbros, and can be applied to many other natural inclusions containing aqueous solutions with NaCl and CaCl{sub 2} the dominant solutes. Microthermometric measurements at equilibrium of the melting temperature of ice (Tm (ice)) and of the dissolution temperature of halite (Tm (halite)) are sufficient to determine the bulk composition of the NaCl-CaCl{sub 2}-H{sub 2}O fluid.

  20. Vapor phase pyrolysis

    NASA Technical Reports Server (NTRS)

    Steurer, Wolfgang

    1992-01-01

    The vapor phase pyrolysis process is designed exclusively for the lunar production of oxygen. In this concept, granulated raw material (soil) that consists almost entirely of metal oxides is vaporized and the vapor is raised to a temperature where it dissociates into suboxides and free oxygen. Rapid cooling of the dissociated vapor to a discrete temperature causes condensation of the suboxides, while the oxygen remains essentially intact and can be collected downstream. The gas flow path and flow rate are maintained at an optimum level by control of the pressure differential between the vaporization region and the oxygen collection system with the aid of the environmental vacuum.

  1. EFFECTS OF A HIGH SATURATED FAT DIET ON CARDIAC HYPERTROPHY AND DYSFUNCTION IN RESPONSE TO PRESSURE OVERLOAD

    PubMed Central

    Chess, David; Lei, Biao; Hoit, Brian; Azimzadeh, Agnes M.; Stanley, William

    2009-01-01

    Background Dietary lipid content effects activation of peroxisome proliferator-activated receptor-? (PPAR?) and may accelerate cardiac hypertrophy and dysfunction in response to pressure overload. This study investigated the effects of a high fat diet on the development of cardiac hypertrophy. Methods and Results C57BL/6J mice (n=14–16/group) underwent transverse aortic constriction (TAC) or sham surgery and were fed either standard low fat diet (STD; 10% fat) or a high fat diet (HFD; 60% fat) for 16 weeks. Sham mice showed no differences between STD and HFD for heart mass or echocardiographic parameters despite greater plasma free fatty acid and leptin concentrations with HFD. TAC increased heart mass and decreased ejection fraction similarly in both groups. Left ventricular end systolic and diastolic diameters with TAC were increased compared to shams on the HFD (p < 0.05) but were not different from STD TAC mice. High fat feeding increased expression of PPAR?-regulated genes. The activity of medium chain acyl-coenzyme A dehydrogenase (MCAD), a marker of fatty acid oxidation capacity, was increased in HFD TAC mice compared to STD, consistent with PPAR? activation. Conclusion Increased fat intake prevented the fall in MCAD activity and did not exacerbate the hypertrophic response to TAC compared to a low-fat diet. PMID:18226777

  2. Operating a radio-frequency plasma source on water vapor

    SciTech Connect

    Nguyen, Sonca V. T.; Gallimore, Alec D. [Plasmadynamics and Electric Propulsion Laboratory, University of Michigan, Ann Arbor, Michigan 48108 (United States); Foster, John E. [Plasma Science and Technology Laboratory, University of Michigan, Ann Arbor, Michigan 48108 (United States)

    2009-08-15

    A magnetically enhanced radio-frequency (rf) plasma source operating on water vapor has an extensive list of potential applications. In this work, the use of a rf plasma source to dissociate water vapor for hydrogen production is investigated. This paper describes a rf plasma source operated on water vapor and characterizes its plasma properties using a Langmuir probe, a residual gas analyzer, and a spectrometer. The plasma source operated first on argon and then on water vapor at operating pressures just over 300 mtorr. Argon and water vapor plasma number densities differ significantly. In the electropositive argon plasma, quasineutrality requires n{sub i}{approx_equal}n{sub e}, where n{sub i} is the positive ion density. But in the electronegative water plasma, quasineutrality requires n{sub i+}=n{sub i-}+n{sub e}. The positive ion density and electron density of the water vapor plasma are approximately one and two orders of magnitude lower, respectively, than those of argon plasma. These results suggest that attachment and dissociative attachment are present in electronegative water vapor plasma. The electron temperature for this water vapor plasma source is between 1.5 and 4 eV. Without an applied axial magnetic field, hydrogen production increases linearly with rf power. With an axial magnetic field, hydrogen production jumps to a maximum value at 500 W and then saturates with rf power. The presence of the applied axial magnetic field is therefore shown to enhance hydrogen production.

  3. Tested Demonstrations. Gasoline Vapor: An Invisible Pollutant

    ERIC Educational Resources Information Center

    Stephens, Edgar R.

    1977-01-01

    Describes a demonstration concerning the air pollution aspects of gasoline vapor which provides an estimation of the vapor pressure of test fuel, the molecular weight of the vapor, and illustrates a method of controlling the pollution. (SL)

  4. Vertical profile of H 2SO 4 vapor at 70–110 km on Venus and some related problems

    Microsoft Academic Search

    Vladimir A. Krasnopolsky

    2011-01-01

    The vertical profile of H2SO4 vapor is calculated using current atmospheric and thermodynamic data. The atmospheric data include the H2O profiles observed at 70–112km by the SOIR solar occultations, the SPICAV-UV profiles of the haze extinction at 220nm, the VeRa temperature profiles, and a typical profile of eddy diffusion. The thermodynamic data are the saturated vapor pressures of H2O and

  5. Supersaturation in the spontaneous formation of nuclei in water vapor

    NASA Technical Reports Server (NTRS)

    Sander, Adolf; Damkohler, Gerhard

    1953-01-01

    According to experience, a certain supersaturation is required for condensation of water vapor in the homogeneous phase; that is, for inception of the condensation, at a prescribed temperature, the water vapor partial pressure must lie above the saturation pressure. The condensation starts on so-called condensation nuclei. Solid or liquid suspended particles may serve as nuclei; these particles may either a priori be present in the gas phase (dust, soot), or may spontaneously be formed from the vapor molecules to be condensed themselves. Only the second case will be considered. Gas ions which facilitate the spontaneous formation of nuclei may be present or absent. The supersaturations necessary for spontaneous nucleus formation are in general considerable higher than those in the presence of suspended particles.

  6. Saturated Fat

    MedlinePLUS

    ... Ice cream and ice cream products Palm and coconut oils It's important to note that lower-fat ... are another source of saturated fats: palm oils, coconut oils, and cocoa butter. You may think you ...

  7. Effects of water-saturation on strength and ductility of three igneous rocks at effective pressures to 50 MPa and temperatures to partial melting

    SciTech Connect

    Bauer, S.J.; Friedman, M.; Handin, J.

    1981-01-01

    Instantaneous-failure strengths and ductilities of water-saturated cylindrical specimens of Charcoal Granodiorite, Mount Hood Andesite, and Cuerbio Basalt are determined at a strain rate of 10{sup -4}s{sup -1} and at effective confining pressures (Pe) of 0 and 50 MPa and at temperatures to partial melting. The data indicate: (1) at Pe = 0 and 50 MPa (Pc and Pp of 50 MPa and of 100 and 50 MPa, respectively) the granodiorite does not water-weaken; (2) at these same Pe the more porous and finer-grained andesite begins to exhibit water-weakening at about 600/sup 0/C; (3) at Pe = 0 and 870-900{sup 0}C the andesite's wet strength averages 20 MPa compared to 100 MPa, dry; (4) at Pe = 50 MPa and 920{sup 0}C its wet strength is 45 MPa compared to 160 MPa dry; (5) at Pe = 0, the basalt appears to be water-weakened above 800{sup 0}C; (6) water-saturated specimens deformed at temperatures less than T{sub m} exhibit ultimate strengths at less than 2 percent shortening and then work-soften along faults; and (7) both dry and wet specimens deform primarily by brittle fracture. Extrapolations indicate: (1) crystalline rocks should be drillable because they remain brittle until partial melting occurs, and penetration rates should increase with temperature because there is a corresponding decrease in brittle fracture strength; (2) boreholes in ''water-filled'' holes will be stable to >10 km at temperatures 10 km; and (4) open boreholes in the andesite are apt to be much less stable, and at similar temperatures would fail at 2 to 5-km depth.

  8. Sulfur Concentration of High-FeO* Basalts at Sulfide Saturation at High Pressures and Temperatures - Implications for Deep Sulfur Cycle on Mars (Invited)

    NASA Astrophysics Data System (ADS)

    Dasgupta, R.; Ding, S.

    2013-12-01

    One of the chief influences of magma in the mantles terrestrial planets is its role in outgassing and ingassing of key volatiles and thus affecting planetary dynamics and climate over long timescales. For Mars, magmatic release of greenhouse gases has been argued to be a major factor in creating warm ancient climate. However, the responsible magmatic gas has not been unequivocally identified. SO2 or H2S could have been the main greenhouse gases, yet the magmatic outflux of S from the martian mantle is poorly constrained. Righter et al. [1] showed that the use of sulfur content at sulfide saturation (SCSS) models based on low-FeO*, high-alumina terrestrial basalts to martian basalts leads to significant error. However, experiments on high-FeO* basalts remain limited to ?0.8 GPa [1], although the onset of melting in the martian mantle may take place at 250-400 km depth (3-5 GPa) [2]. To constrain SCSS of martian magmas at mantle conditions, we simulated basalt-sulfide melt equilibria using two synthesized meteorite compositions, i.e., Yamato980459 (FeO* ˜17 wt.%; Al2O3 ˜6 wt.%) and NWA2990 (FeO* ˜16 wt.%; Al2O3 ˜9 wt.%) in both anhydrous and hydrous conditions at 1-3 GPa and 1500-1700 °C. Experiments were conducted in graphite capsules, using an end-loaded piston cylinder device. Sulfur contents of sulfide melt-saturated experimental quenched basalts were determined using electron microprobe. Our experimental results show that SCSS decreases with increasing pressure and increases with increasing temperature and melt hydration. Based on our experimental SCSS and those from previous low-pressure experiments on high-FeO* martian basalts [2], we developed a new parameterization to predict martian basalt SCSS as a function of depth, temperature, and melt composition. Our model suggests that at the conditions of last equilibration with the sulfide-saturated mantle [2], martian basalts may contain as high as 3500-4700 ppm S and thus S-rich gases might have caused the greenhouse conditions during the late Noachian. However, modeling the fate of sulfur along the liquid line of descent of primitive martian basalts suggests that a part of the magmatic sulfur could precipitate as sulfides in the cumulates during cooling and fractional crystallization of basaltic magmas. Moreover, the existing and new data on bulk sulfur contents of martian meteorites [3,4] suggest that they can be explained by variable amount of S-bearing liquid, trapped as intercumulus phase and thus the degassed S flux to the atmosphere may be lower than that predicted by SCSS. Modeling the SCSS of martian mantle composition along the possible liquidus of Mars to the base of the martian magma ocean (MO) predicts an average S storage capacity of 3700 ppm, whereas the same for low-FeO*, deep terrestrial MO is only ~860 ppm. Lastly, pronounced inverse correlation between pressure and SCSS could have triggered a sulfur pump for the martian magma ocean where the post-core-formation bulk silicate Mars would gain sulfur through interaction with SO2/H2S rich primitive atmosphere. [1] Righter et al. (2009) EPSL 288, 235-243; [2] Filiberto and Dasgupta (2011) EPSL 304, 527-537; [3] Lodders (1998) MAPS 33, A183-A190; [4] Ding et al. (2013) Fall AGU meeting.

  9. The effect of carrier gas flow rate and source cell temperature on low pressure organic vapor phase deposition simulation by direct simulation Monte Carlo method.

    PubMed

    Wada, Takao; Ueda, Noriaki

    2013-04-21

    The process of low pressure organic vapor phase deposition (LP-OVPD) controls the growth of amorphous organic thin films, where the source gases (Alq3 molecule, etc.) are introduced into a hot wall reactor via an injection barrel using an inert carrier gas (N2 molecule). It is possible to control well the following substrate properties such as dopant concentration, deposition rate, and thickness uniformity of the thin film. In this paper, we present LP-OVPD simulation results using direct simulation Monte Carlo-Neutrals (Particle-PLUS neutral module) which is commercial software adopting direct simulation Monte Carlo method. By estimating properly the evaporation rate with experimental vaporization enthalpies, the calculated deposition rates on the substrate agree well with the experimental results that depend on carrier gas flow rate and source cell temperature. PMID:23674843

  10. The effect of carrier gas flow rate and source cell temperature on low pressure organic vapor phase deposition simulation by direct simulation Monte Carlo method

    PubMed Central

    Wada, Takao; Ueda, Noriaki

    2013-01-01

    The process of low pressure organic vapor phase deposition (LP-OVPD) controls the growth of amorphous organic thin films, where the source gases (Alq3 molecule, etc.) are introduced into a hot wall reactor via an injection barrel using an inert carrier gas (N2 molecule). It is possible to control well the following substrate properties such as dopant concentration, deposition rate, and thickness uniformity of the thin film. In this paper, we present LP-OVPD simulation results using direct simulation Monte Carlo-Neutrals (Particle-PLUS neutral module) which is commercial software adopting direct simulation Monte Carlo method. By estimating properly the evaporation rate with experimental vaporization enthalpies, the calculated deposition rates on the substrate agree well with the experimental results that depend on carrier gas flow rate and source cell temperature. PMID:23674843

  11. The effect of carrier gas flow rate and source cell temperature on low pressure organic vapor phase deposition simulation by direct simulation Monte Carlo method

    NASA Astrophysics Data System (ADS)

    Wada, Takao; Ueda, Noriaki

    2013-04-01

    The process of low pressure organic vapor phase deposition (LP-OVPD) controls the growth of amorphous organic thin films, where the source gases (Alq3 molecule, etc.) are introduced into a hot wall reactor via an injection barrel using an inert carrier gas (N2 molecule). It is possible to control well the following substrate properties such as dopant concentration, deposition rate, and thickness uniformity of the thin film. In this paper, we present LP-OVPD simulation results using direct simulation Monte Carlo-Neutrals (Particle-PLUS neutral module) which is commercial software adopting direct simulation Monte Carlo method. By estimating properly the evaporation rate with experimental vaporization enthalpies, the calculated deposition rates on the substrate agree well with the experimental results that depend on carrier gas flow rate and source cell temperature.

  12. Viscosity of Gaseous HFC125 (Pentafluoroethane) Under High Pressures

    Microsoft Academic Search

    M. Takahashi; N. Shibasaki-Kitakawa; C. Yokoyama

    1999-01-01

    This paper reports experimental results lor the viscosity of gaseous HFC-125 (pentafluoroethane) under high pressures. The measurements were carried out with an oscillating-disk viscometer of the Maxwell type at temperatures from 298.15 to 423.15 K and at pressures up to the saturated vapor pressures at each temperature at subcritical conditions or up to 9 MPa at supercritical temperatures. Intermolecular scaling

  13. Unified Application of Vapor Screen Flow Visualization and Pressure Sensitive Paint Measurement Techniques to Vortex- and Shock Wave-Dominated Flow Fields

    NASA Technical Reports Server (NTRS)

    Erickson, Gary E.

    2010-01-01

    Laser vapor screen (LVS) flow visualization and pressure sensitive paint (PSP) techniques were applied in a unified approach to wind tunnel testing of slender wing and missile configurations dominated by vortex flows and shock waves at subsonic, transonic, and supersonic speeds. The off-surface cross-flow patterns using the LVS technique were combined with global PSP surface static pressure mappings to characterize the leading-edge vortices and shock waves that coexist and interact at high angles of attack. The synthesis of LVS and PSP techniques was also effective in identifying the significant effects of passive surface porosity and the presence of vertical tail surfaces on the flow topologies. An overview is given of LVS and PSP applications in selected experiments on small-scale models of generic slender wing and missile configurations in the NASA Langley Research Center (NASA LaRC) Unitary Plan Wind Tunnel (UPWT) and 8-Foot Transonic Pressure Tunnel (8-Foot TPT).

  14. Unified Application Vapor Screen Flow Visualization and Pressure Sensitive Paint Measurement Techniques to Vortex- and Shock Wave-Dominated Flow Fields

    NASA Technical Reports Server (NTRS)

    Erickson, Gary E.

    2008-01-01

    Laser vapor screen (LVS) flow visualization and pressure sensitive paint (PSP) techniques were applied in a unified approach to wind tunnel testing of slender wing and missile configurations dominated by vortex flows and shock waves at subsonic, transonic, and supersonic speeds. The off-surface cross-flow patterns using the LVS technique were combined with global PSP surface static pressure mappings to characterize the leading-edge vortices and shock waves that coexist and interact at high angles of attack (alpha). The synthesis of LVS and PSP techniques was also effective in identifying the significant effects of passive surface porosity and the presence of vertical tail surfaces on the flow topologies. An overview is given of LVS and PSP applications in selected experiments on small-scale models of generic slender wing and missile configurations in the NASA Langley Research Center (NASA LaRC) Unitary Plan Wind Tunnel (UPWT) and 8-Foot Transonic Pressure Tunnel (8-Foot TPT).

  15. Methane hydrate pore saturation evaluation from geophysical logging and pressure core analysis, at the first offshore production test site in the eastern Nankai Trough, Japan

    NASA Astrophysics Data System (ADS)

    Fujii, T.; Suzuki, K.; Takayama, T.; Konno, Y.; Yoneda, J.; Egawa, K.; Ito, T.; Nagao, J.

    2013-12-01

    On March 2013, the first offshore production test form methane hydrate (MH) concentrated zone (MHCZ) was conducted by the Research Consortium for Methane Hydrate Resource Development in Japan (MH21) at the AT1 site located in the north-western slope of Daini-Atsumi Knoll in the eastern Nankai Trough, Japan. Before the production test, extensive geophysical logging and pressure coring using Hybrid Pressure Coring System were conducted in 2012 at monitoring well (AT1-MC) and coring well (AT1-C), in order to obtain basic information for the MH reservoir characterization. MH pore saturation (Sh) is one of the important basic parameters not only for reservoir characterization, but also the resource assessment. However, precise evaluation of Sh from geophysical logging is still challenging technical issue. The MHCZ confirmed by the geophysical logging at AT1-MC has a turbidite assemblage (from several tens of centimeters to a few meters) with 60 m of gross thickness; it is composed of lobe/sheet type sequences in the upper part, and relatively thick channel sand sequences in the lower part. In this study, the Sh evaluated from geophysical logging data were compared with those evaluated from pressure core analysis. Resistivity logs and nuclear magnetic resonance (NMR) log were used for the Sh evaluation by geophysical logging. Standard Archie equation was applied for Sh evaluation from resistivity log, while density magnetic resonance (DMR) method was used for Sh evaluation from NMR log. The Sh from pressure core samples were evaluated using the amount of dissociated gas volume, together with core sample bulk volume, measured porosity, net sand intervals, and assumed methane solubility in pore water. In the upper part of the MHCZ, Sh estimated from resistivity log showed distinct difference in value between sand and mud layers, compared to Sh from NMR log. Resistivity log has higher vertical resolution than NMR log, so it is favorable for these kinds of thin bed evaluation. In this part, 50 to 80% of Sh was observed in sandy layer, which showed fairly good agreement with core derived Sh. On the other hand, lower part of the MHCZ, Sh estimated from both resistivity and NMR log showed higher background value and relatively smoother curve than upper part. In this part, 50 to 80% of Sh was observed in sandy layer, which was also showed good agreement with core derived Sh. This study was conducted by the Research Consortium for Methane Hydrate Resource Development in Japan (MH21).

  16. Optimization of pressurized liquid extraction (PLE) for rapid determination of mineral oil saturated (MOSH) and aromatic hydrocarbons (MOAH) in cardboard and paper intended for food contact.

    PubMed

    Moret, Sabrina; Sander, Maren; Purcaro, Giorgia; Scolaro, Marianna; Barp, Laura; Conte, Lanfranco S

    2013-10-15

    Packaging can represent a primary source of food contamination with mineral oil saturated hydrocarbons (MOSH) and aromatic hydrocarbons (MOAH), especially when recycled cardboard or mineral oil based printing inks are used. A pressurized liquid extraction (PLE) method, followed by on-line LC-GC analysis, has been optimized for rapid mineral oil determination in cardboard and paper samples. The proposed method involves extraction with hexane (2 cycles) at 60°C for 5 min, and allows for the processing of up to 6 samples in parallel with minimal sample manipulation and solvent consumption. It gave good repeatability (coefficient of variation lower than 5%) and practically quantitative extraction yield (less than 2% of the total contamination found in a third separate cycle). The method was applied to different cardboards and paper materials intended for food contact. Results obtained were similar to those obtained by applying classical solvent extraction with hexane/ethanol 1:1 (v/v) as described by Lorenzini et al. [20]. PMID:24054587

  17. Prediction of the Capillary Pressure-Saturation curve from a Pore-Network Model that is Grid-Free and Based on Duality

    NASA Astrophysics Data System (ADS)

    Glantz, R.; Hilpert, M.

    2008-12-01

    Most methods for extracting pore networks from 3D gray-scale images of porous media first segment the images such that a voxel is occupied entirely either by the solid phase or pore space. This discretization represents smooth pore spaces by stairwell-type objects and may further result in inaccurate estimation of local pore size. To overcome this limitation, we developed an approach for deriving pore networks from polyhedral pore spaces, whose pore boundaries are not constrained by an underlying numerical grid. Such a smooth pore boundary can, for example, be obtained through image-analytical algorithms that are routinely used to display 3D gray-scale images of multiphase systems. Our approach is based on mathematical duality between the Delaunay and Voronoi complex with respect to points sampled on the pore boundary of a porous medium. By employing rules for simplifying the Delaunay and Voronoi complex in a way that (1) maintains the topology of the pore space, (2) maintains mathematical duality, and (3) is free of fit parameters, we are able to decompose a polyhedral pore space into polyhedral pore bodies separated by polygonal pore throats and to construct a polygonal pore network that is homotopy equivalent to the pore space. Using the network, we simulated drainage in a glass bead packing. The simulated capillary pressure-saturation curve agrees well with the measured one.

  18. Mathematical relationships between vapor pressure, water solubility, Henry's law constant, n-octanol\\/water partition coefficent and gas chromatographic retention index of polychlorinated-dibenzo-dioxins

    Microsoft Academic Search

    Y. H. Wang; P. K. Wong

    2002-01-01

    Mathematical relationships between vapor pressures (P), water solubilities (S), Henry's law constants (Hc), n-octanol\\/water partition coefficients (Kow) and gas chromatograph retention indices (GC-RIs) of polychlorinated-dibenzo-dioxins (PCDDs) were established. A model equation was established between GC-RIs (=RI) and other physico-chemical parameters (K) of PCDDs in the form of logK=aRI2+bRI+c with correlation coefficients (R2) greater than 0.97, except Hc. These equations were

  19. Ionic liquids as superior solvents for headspace gas chromatography of residual solvents with very low vapor pressure, relevant for pharmaceutical final dosage forms.

    PubMed

    Laus, Gerhard; Andre, Max; Bentivoglio, Gino; Schottenberger, Herwig

    2009-08-01

    1-n-Butyl-3-methylimidazolium dimethyl phosphate (BMIM DMP) was identified as the most suitable ionic liquid as solvent for the headspace gas chromatographic analysis of solvents with very low vapor pressure such as dimethylsulfoxide, N-methylpyrrolidone, sulfolane, tetralin, and ethylene glycol in a realistic matrix of commonly used excipients (carboxymethylcellulose, magnesium stearate, guar flour, and corn starch) in pharmaceutical products. Limits of quantification and limits of detection were in the low microgram per gram range. The detection of traces of sulfolane in a real sample of tablets containing the drug cefpodoxim proxetil demonstrated the applicability of the method. PMID:19560778

  20. Fluorescence of Naphthacene Vapor

    Microsoft Academic Search

    R. Williams; G. J. Goldsmith

    1963-01-01

    The absorption spectrum of naphthacene vapor is similar to that in solution. There is an absorption band with pronounced vibrational structure running from about 5000 to 3500 Å and a second stronger band from 2700 Å to shorter wavelengths. We have examined the fluorescence spectrum of the vapor at low pressures, such that molecules have no collisions during the lifetime