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1

Improved Magnus` form approximation of saturation vapor pressure  

SciTech Connect

Relative humidity is usually measured in aerological observations and dew point depression is usually reported in upper-air reports. These variables must frequently be converted to other moisture variables in meteorological analysis. If relative humidity is converted to vapor pressure, most humidity variables can then be determined. Elliott and Gaffen reviewed the practices and procedures of the US radiosonde system. In their paper, a comparison of the relative errors was made between the saturation vapor pressure formulations of Tetens (1930), Goff-Gratch (1946), Wexler (1976), and Buck (1981). In this paper, the authors will expand the analysis of Elliott and Gaffen by deriving several new saturation vapor pressure formulas, and reviewing the various errors in these formulations. They will show that two of the new formulations of vapor pressure over water and ice are superior to existing formulas. Upper air temperature data are found to vary from about +50 C to {minus}80 C. This large variation requires a saturation vapor pressure equation to be accurate over a large temperature range. While the errors introduced by the use of relatively inaccurate conversion equations are smaller than the errors due to the instruments, dewpoint coding errors, and dewpoint conversion algorithms (Elliott and Gaffen, 1993); they introduce additional systematic errors in humidity data. The most precise formulation of vapor pressure over a plane surface of water was given by Wexler (1976). The relative errors of Tetens` (1930) formula and one due to Buck (1981) (Buck`s equation is recommended in the Federal Meteorological Handbook No. 3, 1991) are shown. The relative errors in this table are the predicted value minus the Wexler value divided by the Wexler value.

Alduchov, O.A.; Eskridge, R.E. [National Oceanic and Atmospheric Administration, Asheville, NC (United States). National Climatic Data Center

1997-11-01

2

Saturated vapor pressure above the amalgam of alkali metals in discharge lamps  

NASA Astrophysics Data System (ADS)

A theoretical and numerical analysis of the evaporation process of two-component compounds in vapors of alkali metals in discharge lamps is presented. Based on the developed mathematical model of calculation of saturated vapor pressure of the metal above the amalgam, dependences of mass fractions of the components in the discharge volume on design parameters and thermophysical characteristics of the lamp are obtained.

Gavrish, S. V.

2011-12-01

3

A novel thermogravimetric method for estimating the saturated vapor pressure of low-volatility compounds.  

PubMed

Thermogravimetric analysis is used to measure accelerated vaporization rates at elevated temperatures and reduced pressures for several compounds. Multiple linear regression is used to generate empirical coefficients of an equation that relates these parameters. The vaporization rates of the compounds at standard ambient temperature and pressure (SATP) are estimated by extrapolation to 10(5) Pa (1 atm) and 298 K. The estimated vaporization rates are then correlated with literature values of saturated vapor pressure (Psat). The results of twenty four compounds with vapor pressures that span 10 orders of magnitude indicate that p25 degrees C (sat) is directly proportional to the rate of vaporization at SATP. The average error of an estimate of p25 degrees C (sat) based on this relationship is less than a factor of 2.1. PMID:10189258

Tesconi, M; Yalkowsky, S H

1998-12-01

4

a Property of the Saturated Vapor Pressure:. Results from Equations of State  

NASA Astrophysics Data System (ADS)

Experimentally, a maximum point in the curve of the saturated property ?=(1-Tr)Pr versus the saturated temperature was postulated (High Temp.-High Press. 26 (1994) 427). Here, Tr is the saturated temperature reduced by the critical temperature and Pr is the saturated pressure reduced by the critical pressure. Later, this behavior was applied to assure the saturated vapor pressure critical amplitudes (Appl. Phys. Lett. 90 (2007) 141905). In this paper, we indicate that theory of equation of state (EOS) can predict this maximum point. The EOSs we study are the combinations of the hard sphere repulsions and some normally used attractions such as the Redlich-Kwong attraction. We find the EOSs with Redlich-Kwong attractive terms give out the results in the experimental range.

Tian, Jianxiang; Jiang, Hua; Xu, Yi

5

The Observed Properties of Liquid Helium at the Saturated Vapor Pressure  

Microsoft Academic Search

The equilibrium and transport properties of liquid 4He are deduced from experimental observations at the saturated vapor pressure. In each case, the bibliography lists all known measurements. Quantities reported here include density, thermal expansion coefficient, dielectric constant, superfluid and normal fluid densities, first, second, third, and fourth sound velocities, specific heat, enthalpy, entropy, surface tension, ion mobilities, mutual friction, viscosity

Russell J. Donnelly; Carlo F. Barenghi

1998-01-01

6

Absorption cross sections, saturated vapor pressures, sublimation energies, and evaporation energies of some organic laser dye vapors  

NASA Astrophysics Data System (ADS)

A new technique of transmission measurement of overheated dye vapors is applied to determine absolute absorption cross-section spectra of three active dyes for vapor phase dye lasers. The investigated compounds are 1,4-di/2-(5-phenyloxazolyl)/-benzene (POPOP), 1,4-di/2-(4-methyl-5-phenyl-oxazolyl)/-benzene (dimethyl-POPOP), and 2,5-diphenylfuran (PPF). The vapor absorption spectra are compared with liquid solution spectra in order to obtain information on the dye-solvent interaction. The saturated vapor densities are determined by transmission measurements after knowing the absolute absorption cross-section spectra. The latent heats of sublimation, evaporation, and melting are derived by analyzing the dependences of the saturated vapor densities on the vapor temperature.

Schmidt, J.; Penzkofer, A.

1989-08-01

7

Vapor Pressure of GD.  

National Technical Information Service (NTIS)

The vapor pressure of pinacolyl methyl phosphonofluoridate O-(I ,2, 2-trimethylpropyl)-methyl phosphonofluoridate. GD has been measured between - 20 and 50 C, using vapor saturation methodology. The current data are in good agreement with data previously ...

A. Balboa D. E. Tevault J. H. Buchanan L. C. Buettner T. Sewell

2007-01-01

8

Measurement of the vapor pressure of several low-volatility organochlorine chemicals at low temperatures with a gas saturation method  

SciTech Connect

The vapor pressures of hexachlorobenzene, [gamma]-hexachlorocyclohexane, p,p[prime]-DDT, i.e., 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane, 4-monochlorobiphenyl, 4,4[prime]-dichlorobiphenyl, 2,3,4,5-tetrachlorobiphenyl, and 2,2[prime],4,4[prime],6,6[prime]-hexachlorobiphenyl were measured in the temperature range [minus]30 to +40 C with a gas saturation technique. Coefficients describing the temperature dependence of these vapor pressures are reported. Enthalpies of sublimation derived from these data show no significant temperature dependence in the temperature range investigated.

Wania, F.; Shiu, W.Y.; Mackay, D. (Univ. of Toronto, Ontario (Canada). Dept. of Chemical Engineering and Applied Chemistry)

1994-07-01

9

The roles of the saturation vapor pressure and water vapor partial pressure in controlling different stages of the polar mesospheric cloud season  

NASA Astrophysics Data System (ADS)

SOFIE (Solar Occultation For Ice Experiment) daily zonal mean temperature (T), water vapor (H2O), and PMC measurements made from the AIM satellite, have been used to study the roles of temperature and water vapor in controlling the start, end, and PMC variability during the 2007 to 2009 northern summer PMC seasons. A necessary condition for PMCs to exist is that the ratio of PH2O (water vapor partial pressure) to Psat (saturation vapor pressure of the environment) must be greater than one. The start or end date of the season is defined here as the day when the first or last PMC is detected. SOFIE measurements show that these detections generally coincide with days when the daily maximum PH2O/Psat enters or exits the PH2O/Psat>1 domain. At the start or end of the PMC season, Psat, which is controlled only by temperature, rapidly changes by several orders of magnitude from above/below to below/above PH2O, signaling that temperature is in dominant control of entry to or exit from the PMC season. Similar to Psat, the SOFIE measured PMC frequency of occurrence rises/drops rapidly to/from ~100% within a few days, at the start/end of the PMC season. During the main period of the PMC season, on the other hand, Psat is negligibly small compared to PH2O, despite significant changes in temperature. As a result PH2O is in dominant control of the ice mass density variation. At the daily mean SOFIE PMC centroid height, PH2O correlates with the observed ice mass density on a range of intra-seasonal time scales both short and long (i.e., ~daily to monthly). Correlation on a seasonal scale is poor at the start and end of the season, reinforcing the argument that Psat dominates in these stages.

Rong, P.; Russell, J.; Hervig, M. E.; Bailey, S. M.

2010-12-01

10

Electrical conductivity measurements of aqueous boric acid at 25--350{degree}C at saturation vapor pressure. Final report  

SciTech Connect

Electrical conductance measurements of aqueous boric acid solutions (15-110 g/kg-H{sub 2}O {equivalent_to} 0.251--1.815 mol/kg-H{sub 2}O) were measured over the temperature range 25 to 75 C at saturation vapor pressures in glass cells with parallel platinum electrodes. Sixteen series of measurements were made involving three samples of boric acid from different sources. Conductance measurements were also made at 15.5 and 30.5 g/kg-H{sub 2}O over the temperature range 100 to 350 C at 50 C intervals with a metallic cell fitted with concentric platinum electrodes. The specific conductances of H{sub 3}BO{sub 3} (aq)were calculated after correction for the conductance of the solvent (water) and are tabulated in this report. At the specific conditions requested in the project description, namely a concentration of 110 g/kg-H{sub 2}O and 65 C, the specific conductance of boric acid is 293.2 {+-} 1.8 microSiemens/cm based on duplicate measurements of four independent solutions. The results from these tests will be utilized by the Tokamak Physics Experimental Project (TPX).

Ho, P.C.; Palmer, D.A.

1995-09-01

11

The roles of the saturation vapor pressure and water vapor partial pressure in controlling different stages of the polar mesospheric cloud season  

Microsoft Academic Search

SOFIE (Solar Occultation For Ice Experiment) daily zonal mean temperature (T), water vapor (H2O), and PMC measurements made from the AIM satellite, have been used to study the roles of temperature and water vapor in controlling the start, end, and PMC variability during the 2007 to 2009 northern summer PMC seasons. A necessary condition for PMCs to exist is that

P. Rong; J. Russell; M. E. Hervig; S. M. Bailey

2010-01-01

12

Assessment of feldspar solubility constants in water in the range of 0 to 350 C at vapor saturation pressures  

SciTech Connect

The equilibrium constants for endmember feldspar hydrolysis for the following reactions: NaAlSi{sub 3}O{sub 8} + 8H{sub 2}O = Na{sup +} + Al(OH){sub 4}{sup {minus}} + 3H{sub 4}SiO{sub 4}{sup 0}; KAlSi{sub 3}O{sub 8} + 8H{sub 2}O = K{sup +} + Al(OH){sub 4}{sup {minus}} + 3H{sub 4}SiO{sub 4}{sup 0}; CaAl{sub 2}Si{sub 2}O{sub 8} + 8H{sub 2}O = Ca{sup +2} + 2Al(OH){sub 4}{sup {minus}} + 2H{sub 4}SiO{sub 4}{sup 0} are accurately described by five equations where temperature is in K. They are valid in the range 0 to 350 C, at 1 bar below 100 C and at vapor saturation pressures (P{sub sat}) at higher temperatures. The equations for low-albite and microcline are valid for Amelia albite and for microcline with the same degree of Al-Si order (Z = 0.95), respectively. The same kind of log K-temperature equations have also been retrieved for alkali-feldspar and plagioclase solid solutions. The calculated feldspar equilibrium constants of this study indicate much higher solubility under weathering conditions than generally accepted to date, the difference being more than one and a half orders of magnitude at 0 C for both high- and low-albite, but somewhat less for microcline, sanidine, and anorthite. This higher solubility is largely a consequence of new data for the thermodynamic properties of H{sub 4}SiO{sub 4}{sup 0}. The present results have a particularly important bearing on the stability of feldspars under weathering conditions and the study of interaction between water and rock/soil in this environment. They are, however, also important for the study of equilibrium/dis-equilibrium conditions in active geothermal systems.

Arnorsson, S.; Stefansson, A. [Univ. of Iceland, Reykjavik (Iceland). Science Inst.

1999-03-01

13

Progress of serpentinization in olivine-H2O system at 250 C and vapor-saturated pressure  

NASA Astrophysics Data System (ADS)

Fluids play a crucial role in global-scale mass transfer, metamorphism, volcanism, and seismic processes in subduction zones. Serpentine minerals, which are produced by interaction between ultramafic rocks and fluids, contain about 13% water and are the greatest carrier of H2O into the deep interior of Earth. Therefore, the volume and distribution of hydrated oceanic mantle are of special interest in evaluating the effects of fluids on subduction zone processes. We conducted hydrothermal experiments in olivine (Ol; Fo91)-H2O and orthopyroxenite (Opx; composed of 95% of orthopyroxene, En66)-H2O systems under conditions of 250 C and vapor-saturated pressure (Psat) to examine the temporal evolution of the solution chemistry and products in runs of up to 1008 h in duration. The maximal degree of hydration (i.e., H2O content in the solid sample) in the Ol-H2O experiments (3.6 wt.%) was much higher than that in the Opx-H2O experiments (0.4 wt.%). In the Ol-H2O experiments, Mg and Si in solution showed an initial increase (stage 1) before decreasing (stage 2) and finally attaining a steady state after 504 h (stage 3). Following a drop in silica activity toward the level of brucite stability filed, the products also changed from serpentine + magnetite (stages 1 and 2) to serpentine + brucite + magnetite (stage 3). Serpentine minerals also changed from lizardite (stages 1 and 2) to lizardite + chrysotile (stage 3). The textures observed in this study were similar to those observed in partly serpentinized dunites. In the Opx-H2O experiments, chlorite formed after orthopyroxene grains, which differs from the formation of talc and serpentine after orthopyroxene (bastite), as observed in natural hydrated harzburgites. The Opx-H2O system maintained 10-103 times higher silica activity than Ol-H2O system, suggesting that brucite does not form after olivine during hydration of peridotites when the Ol-H2O system is linked to the Opx-H2O system. The progress of hydration reactions is affected by mechanical properties of host rocks. The hydration reactions observed in this study produced hierarchical fractures in the reactants, which became filled with reaction products, similar to mesh textures after olivine in natural peridotites. This reaction-induced fracturing produced new reaction surfaces and fluid pathways that enhanced the hydration reactions. The overall reaction producing serpentine+brucite in the Ol-H2O experiments showed the large volume expansion (V/V0 = 1.38 at stage 3), whereas that producing only serpentine proceeded with near constant volume (V/V0 = 1.09 at stage 1). The volume expansion is more difficult to occur in the oceanic lithosphere than in our experiments during serpentinization. Thus, in the case that volume expansion is prevented at reaction sites, one of the following outcomes occurs: (1) the hydration reaction stops until new fractures form, or (2) the reaction proceeds with low volume expansion (absence of brucite) by removing Mg from the system. These two outcomes would produce contrasting distributions or extent of hydration in oceanic lithosphere.

Okamoto, A.; Ogasawara, Y.; Tsuchiya, N.

2011-12-01

14

Mass spectrometric determination of partial pressures of ions in the saturated vapor over the NaF-Na3AlF6 system  

NASA Astrophysics Data System (ADS)

Mass spectrometric determination of absolute partial pressures of basic charged species Na2F+ and AlF4- in the saturated vapor over the NaF-Na3AlF6 system (1:1 molar ratio) was carried out in the 974-1090 K temperature range. The ion pressures were 5-8 orders of magnitude lower than the pressures of basic molecular components NaAlF4 and NaF. Particular attention was given to the equality of device sensitivity constants for positive and negative ions. Absolute device calibration was carried out using the measured ion currents Na2F+ and AlF4- and the equilibrium constant of heterolytic dissociation available in the literature.

Abramov, S. V.; Chilingarov, N. S.; Borshchevsky, A. Ya; Sidorov, L. N.

2004-01-01

15

The flow of butane and isobutane vapors near saturation through porous Vycor glass membranes  

Microsoft Academic Search

The pressure-driven flow of vapors through Vycor glass membranes is investigated theoretically and experimentally. The mass flow is measured for a range of pore diameters between 20nm and 200nm and for a range of upstream conditions and pressure differences. The pressures of the vapors upstream of the membrane lie between the saturation pressure and approximately half the saturation pressure. The

Thomas Loimer; Petr Uchytil; Roman Petrickovic; Katerina Setnickova

2011-01-01

16

Condensation of saturated vapor on melting surfaces  

SciTech Connect

Melting of vertical and horizontal surfaces as a result of condensation of saturated vapor was studied. For the vertical wall, employing similarity transformation, full boundary layer equations governing laminar films of melt and condensate were obtained. Depending on the magnitude of the Prandtl number, different scaling parameters are needed such that Pr appears in the momentum or energy equation. Numerical results of the heat transfer coefficient and for the meltcondensate interface temperature were obtained for a wide range of thermophysical properties of the melt and the condensate. Application of the results to condensation of UO/sub 2/ vapor on vertical surfaces of steel is discussed. However, in doing so the heat generation in UO/sub 2/ was ignored. Experiments were conducted by condensing saturated steam on vertical surfaces of slabs made of naphthalene, biphenyl, stearic acid, and Wood's metal. Shape change of an initially vertical surface undergoing simultaneous melting-condensation was studied both analytically and experimentally. It was shown that such a surface will not stay vertical and will go through a series of transient shapes before attaining a steady stare shape. Numerical solutions are obtained both for the transient shapes of the wall and the heat transfer coefficient. The steady state shape of the wall is predicted to be the one which yields a constant melting rate along the wall. The heat transfer and shape change data obtained by condensing saturated steam on vertical surfaces of slabs made of naphthalene, biphenyl, and stearic acid were compared with the predictions. For the condensation on the downward facing horizontal melting surface, analyses for the heat transfer coefficient were made by invoking an analogy with simultaneous melting-condensation on vertical surfaces.

Taghavi-Tafreshi, K.

1982-01-01

17

Vapor pressures of new fluorocarbons  

SciTech Connect

The vapor pressures of four fluorocarbons have been measured at the following temperature ranges: R123 (2,2-dichloro-1,1,1-trifluoroethane), 273-457 K; R123a (1,2-dichloro-1,1,2-trifluoroethane), 303-458 K; R134a (1,1,1,2-tetrafluoroethane), 253-373 K; and R132b (1,2-dichloro-1,1-difluoroethane), 273-398 K. Determinations of the vapor pressure were carried out by a constant-volume apparatus with an uncertainty of less than 1.0%. The vapor pressures of R123 and R123a are very similar to those of R11 over the whole experimental temperature range, but the vapor pressures of R134a and R132b differ somewhat from those of R12 and R113, respectively, as the temperature increases. The numerical vapor pressure data can be fitted by an empirical equation using the Chebyshev polynomial with a mean deviation of less than 0.3%.

Kubota, H.; Yamashita, T.; Tanaka, Y.; Makita, T. (Kobe Univ. (Japan))

1989-05-01

18

Vapor pressure, heat capacity, and density along the saturation line, measurements for cyclohexanol, 2-cyclohexen-1-one, 1,2-dichloropropane, 1,4-di-tert-butylbenzene, ({+-})-2-ethylhexanoic acid, 2-(methylamino)ethanol, perfluoro-n-heptane, and sulfolane  

Microsoft Academic Search

Vapor pressures were measured to a pressure limit of 270 kPa or lower decomposition point for eight compounds using a twin ebulliometric apparatus. Liquid-phase densities along the saturation line were measured for each compound over a range of temperatures (ambient to a maximum of 548 K). A differential scanning calorimeter (DSC) was used to measure two-phase (liquid + vapor) heat

W. V. Steele; R. D. Chirico; S. E. Knipmeyer; A. Nguyen

1997-01-01

19

CC Cryostat Vapor Pressure Thermometers  

SciTech Connect

Vapor pressure thermometers will be used to measure the temperature or the liquid argon in the cryostat at two different levels. One bulb will be positioned near the top of the vessel, and a second bulb will be located near the bottom of the vessel. The volume of the bulbs is dependent upon the charge temperature and pressure chosen, the temperature range of the thermometer desired, the size and length of tubing used, and the warm volume involved.

Kurita, C.H.; /Fermilab

1987-10-01

20

Vapor Pressure Measurements in a Closed System  

ERIC Educational Resources Information Center

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

Iannone, Mark

2006-01-01

21

Thermal conductivity of R134a and R141b within the temperature range 240307 K at the saturation vapor pressure  

Microsoft Academic Search

New, absolute values of the thermal conductivity of two refrigerants, R134a and R141b, in the liquid phase at saturation are reported. The measurements have been performed in transient hot-wire instruments making use of electrically insulated tantalum wires within the temperature range 240307 K. The results are estimated to have an accuracy of 1%.

M. Papadaki; M. Schmitt; A. Seitz; K. Stephan; B. Taxis; W. A. Wakeham

1993-01-01

22

Enthalpy of Vaporization and Vapor Pressures: An Inexpensive Apparatus  

ERIC Educational Resources Information Center

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

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

2007-01-01

23

Saturated vapor properties and scaling in the lattice gas model  

SciTech Connect

A study of the lattice gas (Ising) model shows the properties of saturated vapor in coexistence with a liquid to be independent of the system's fixed mean density {rho}{sub fixed}, in keeping with standard thermodynamics. This behavior ensures that Fisher scaling plots are unique, independent of {rho}{sub fixed}, and yield a unique characterization of the liquid-vapor phase diagram. The resulting phase diagram and critical parameters for the square lattice gas model are shown to agree with accepted values to within a few percent throughout the coexistence region.

Elliott, J.B.; Moretto, L.G.; Phair, L. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2005-02-01

24

Saturated Vapour Pressure and Refrigeration - Part I  

ERIC Educational Resources Information Center

The first part of a two-part article describes an experimental approach that can be used in teaching the concept of saturated vapour pressure. This leads to a discussion of refrigeration cycles in the second part of the article. (JR)

Bunker, C. A.

1973-01-01

25

Vapor pressure, heat capacity, and density along the saturation line, measurements for cyclohexanol, 2-cyclohexen-1-one, 1,2-dichloropropane, 1,4-di-tert-butylbenzene, ({+-})-2-ethylhexanoic acid, 2-(methylamino)ethanol, perfluoro-n-heptane, and sulfolane  

SciTech Connect

Vapor pressures were measured to a pressure limit of 270 kPa or lower decomposition point for eight compounds using a twin ebulliometric apparatus. Liquid-phase densities along the saturation line were measured for each compound over a range of temperatures (ambient to a maximum of 548 K). A differential scanning calorimeter (DSC) was used to measure two-phase (liquid + vapor) heat capacities for each compound in the temperature region ambient to the critical temperature or lower decomposition point. Where possible, the critical temperature and critical density for each compound were determined experimentally. The results of the measurements were combined to derive a series of thermophysical properties including critical temperature, critical density, critical pressure, acentric factor, enthalpies of vaporization [within the temperature range ({+-}50 K) of the vapor pressures], enthalpies of fusion if solid at ambient temperature, solubility parameter, and heat capacities along the saturation line. Wagner-type vapor-pressure equations were derived for each compound. In addition, the liquid-phase densities were compared with values derived using a four-term power series in either T or [(1 {minus} T{sub r}){sup 1/3}]. All measured and derived values were compared with those obtained in a search of the literature. Recommended critical parameters are listed for each of the compounds studied. A Rule-Of-Thumb derived in the 1992 Project Year was used to estimate thermal decomposition temperatures by radical scission from a knowledge of the bond dissociation energy or vice versa.

Steele, W.V.; Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A. [National Inst. for Petroleum and Energy Research, Bartlesville, OK (United States)] [National Inst. for Petroleum and Energy Research, Bartlesville, OK (United States)

1997-11-01

26

Ice crystal growth in water vapor at high saturation  

NASA Technical Reports Server (NTRS)

A simple technique is presented for estimating the energy of formation of monolayer icelike clusters at ice-vapor interfaces. Under the assumptions that the ice surfaces are smooth and sparsely covered with monomers, dimers, etc., in near equilibrium with the vapor, and that the bond energies and configurational entropy dominate the energy of formation, it is found that the basal surfaces prefer triangular embryos with an orientation which reverses from layer to layer, whereas the most stable clusters on the prism surfaces are rectangular in configuration. The preferred prism clusters are determined to have a significantly lower critical energy of formation than the basal clusters due to differences in both corner free energy and configurational entropy. This phenomenon provides a mechanism for strongly anisotropic crystal growth at high saturations.

Bartley, D. L.

1976-01-01

27

Vapor pressure and thermodynamics of actinide metals  

Microsoft Academic Search

Precise vapor pressure measurements by target collection\\/mass spectrometric Knudsen effusion techniques were combined with crystal entropy estimates to produce self-consistent free-enrgy functions, permitting calculation of heats, entropies and free energies from 298°K to the highest temperatures of measurement. The vapor pressures and thermodyamics of vaporization of americium, curium, berkelium, and californium are compared in terms of electronic structure and bonding

J. W. Ward; P. D. Kleinschmidt; R. G. Haire; D. Brown

1980-01-01

28

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

NASA Technical Reports Server (NTRS)

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.

Nguyen, Huy H.; Martin, Michael A.

2004-01-01

29

Vapor pressure and intramolecular hydrogen bonding in fluorotelomer alcohols.  

PubMed

Vapor pressure and aqueous solubility are important parameters used to estimate the potential for transport of chemical substances in the atmosphere. For fluorotelomer alcohols (FTOHs), currently under scrutiny by environmental scientists as potential precursors of persistent perfluorocarboxylates (PFCAs), vapor pressure is the more significant property since these compounds are only very sparingly soluble in water. We have measured the vapor pressures of a homologous series of fluorotelomer alcohols, F(CF2CF2)nCH2CH2OH (n = 2-5), in the temperature range 21-250 degrees C by three independent methods: (a) a method suitable for very low vapor pressures at ambient temperatures (gas-saturation method), (b) an improved boiling point method at controlled pressures (Scott method), and (c) a novel method, requiring milligram quantities of substance, based on gas-phase NMR, a technique largely unfamiliar to chemists and holding promise for studies of relevance to environmental chemistry. The concordant values obtained indicate that recently published vapor pressure data overestimate the vapor pressure at ambient temperature, and therefore the volatility, of this series of fluorinated compounds. It was suggested that substantial intramolecular -O-H...F- hydrogen bonding between the hydroxylic proton and the two fluorines next to the ethanol moiety was responsible for their putative high volatility. Therefore, we have used gas-phase NMR, gas-phase FTIR, 2D NMR heteronuclear Overhauser effect measurements, and high-level ab initio computations to investigate the intramolecular hydrogen bonding in fluorotelomer alcohols. Our studies unequivocally show that hydrogen bonding of this type is not significant and cannot contribute to and cause unusual volatility. The substantially lower vapor pressure at ambient temperatures than previously reported resulting from our work is important in developing a valid understanding of the environmental transport behavior of this class of compounds. PMID:16833963

Krusic, Paul J; Marchione, Alexander A; Davidson, Fredric; Kaiser, Mary A; Kao, Chien-Ping C; Richardson, Raymond E; Botelho, Miguel; Waterland, Robert L; Buck, Robert C

2005-07-21

30

VAPOR PRESSURE DISTRIBUTION OF SELECTED ORGANIC CHEMICALS  

EPA Science Inventory

A tabulation of vapor pressures for organic chemical products currently considered for inclusion in fugitive emissions regulations was prepared. For each of the 378 chemicals (or groups of chemicals) identified by the Emission Standards and Engineering Division, the following dat...

31

Vapor-Pressure Measurements by Effusion Methods.  

National Technical Information Service (NTIS)

Vapor pressure measurements were made on FeCl2, FeBr2, FeI2, Sb, Bi, Cd, Mg, Pb, FeCl3, and VCl2 using the Knudsen and torsion effusion methods and on FeCl3-NaCl mixtures, Au2Cl6 and MgNi2 using only the Knudsen method. Apparent vapor pressures calculated...

A. Landsberg A. Adams S. D. Hill

1977-01-01

32

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

NASA Technical Reports Server (NTRS)

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.

Nguyen, Huy H.; Martin, Michael A.

2003-01-01

33

Vapor Pressure of Cesium Between 270 and 370 K Via Laser Absorption  

Microsoft Academic Search

For more than sixty years, experimenters have relied on the vapor pressure equations from Taylor and Langmuir's positive ion measurementsfootnote J. B. Taylor and I. Langmuir. Phys. Rev., 51:753 (1937). to calibrate the densities of saturated atomic cesium vapor for numerous spectroscopic applications. We update these results with additional data obtained via measurement of the direct absorption of narrow-band laser

Robert J. Rafac; Carol E. Tanner

1998-01-01

34

Vapor pressures of acetylene at low temperatures  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

35

46 CFR 154.451 - Design vapor pressure.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Design vapor pressure. 154.451 Section...VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Independent...Process Pressure Vessels § 154.451 Design vapor pressure. The Po...

2013-10-01

36

Pressurized vapor driven rotary engine  

Microsoft Academic Search

This patent describes a pressurized fluid rotary engine. It comprises a piston housing; first and second hubs, each hub being rotatably supported in the piston housing about a common axis; piston heads extending radially outwardly from the hubs for travel in a circular path about the axis, each piston head having a pair of working surfaces, each working surface facing

Schadeck

1992-01-01

37

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...

38

Vapor pressures and heats of vaporization of primary coal tars. Quarterly technical progress report, April 1--June 30, 1995  

SciTech Connect

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. Both the gas saturation method and the Knudsen effusion method are being used. Results are presented for anthracene, naphthacene, pentacene, and a mixture of anthracene and perylene obtained using the effusion method.

Suuberg, E.M.

1995-10-01

39

Vapor pressure measurements in the range 10 ?5 Pa to 1 Pa of four pentaerythritol esters  

Microsoft Academic Search

Vapor pressures of four pure pentaerythritol esters, PE, pentaerythritol tetrapentanoate, pentaerythritol tetraheptanoate, pentaerythritol tetranonanoate and pentaerythritol tetra 2-ethylhexanoate were measured between 334 and 476K in a recently developed gas saturation apparatus. The experimental vapor pressure values for the four polyolesters range from 5.610?5Pa to 0.94Pa. These data together with density values were used to determined SAFT and PC-SAFT characteristic parameters.

Antonio Razzouk; Ilham Mokbel; Josefa Garca; Josefa Fernandez; Nizar Msakni; Jacques Jose

2007-01-01

40

46 CFR 154.426 - Design vapor pressure.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Design vapor pressure. 154.426 Section...VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Membrane Tanks § 154.426 Design vapor pressure. The Po of a...

2013-10-01

41

46 CFR 154.438 - Design vapor pressure.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Design vapor pressure. 154.438 Section...VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Independent Tank Type A § 154.438 Design vapor pressure. (a) If the...

2013-10-01

42

46 CFR 154.445 - Design vapor pressure.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Design vapor pressure. 154.445 Section...VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Independent Tank Type B § 154.445 Design vapor pressure. If the...

2013-10-01

43

46 CFR 154.436 - Design vapor pressure.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Design vapor pressure. 154.436 Section...VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Semi-Membrane Tanks § 154.436 Design vapor pressure. The Po of...

2013-10-01

44

46 CFR 154.419 - Design vapor pressure.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Design vapor pressure. 154.419 Section...VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Integral Tanks § 154.419 Design vapor pressure. The Po of...

2013-10-01

45

On the propagation of a coupled saturation and pressure front  

SciTech Connect

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.

Vasco, D. W.

2010-12-01

46

Solubility of hydrogen sulfide in pure water and in NaCl solutions, from 20 to 320C and at saturation pressures  

Microsoft Academic Search

The solubility of hydrogen sulfide in pure water and in NaCl solutions has been studied experimentally from 20 to 320C and at saturation pressures. Hydrogen sulfide solutions in equilibrium with their vapor phase were contained in a pressurized titanium bellows of known total volume. The bellows transmitted inside-vapor pressures via a thermally stable oil (pressure medium) to a high-precision pressure

O. M. Suleimenov; R. E. Krupp

1994-01-01

47

Vapor pressures and gas-phase PVT data for 1,1,1,2-tetrafluoroethane  

SciTech Connect

The authors present new data for the vapor pressure and PVT surface of 1,1,1,2-tetrafluoroethane (Refrigerant 134a) in the temperature range 40{degree}C (313 K) to 150{degree}C (423 K). The PVT data are for the gas phase at densities up to one-half critical. Densities of the saturated vapor are derived at five temperatures from the intersections of the experimental isochores with the vapor pressure curve. The data are represented analytically in order to demonstrate experimental precision and to facilitate calculation of thermodynamic properties.

Weber, L.A. (National Institute of Standards and Technology, Gaithersburg, MD (USA))

1989-05-01

48

Pure-component vapor pressures using UNIFAC group contribution  

Microsoft Academic Search

A group-contribution model, in part based on the UNIFAC method for vapor-liquid equilibria, is developed for predicting pure-component vapor pressures. The model is applied to different hydrocarbons, alcohols, ketones, organic acids, and chloroalkanes of molecular weights below 500. Good representation is obtained for vapor pressure data in the region 10-2000 mmHg. The model may be used to estimate vapor pressures

Torben Jensen; Aage Fredenslund; Peter Rasmussen

1981-01-01

49

Dissolved air flotation (DAF) performance at low saturation pressures  

Microsoft Academic Search

Dissolved Air (Pressure) Flotation-DAF, is a well-established solid and\\/or liquid\\/liquid separation process that uses micro-bubbles as a carrier phase. Bubbles are formed by a reduction of pressure of a water stream previously saturated with air (gas) at pressures usually higher than 3 atm. In industrial practice, the supersaturated water is forced trough needle valves, and clouds of bubbles having 0.02-0.15

L. A. Fris; J. Rubio

1999-01-01

50

Vapor pressures and gas-phase PVT data for 1,1,1,2-tetrafluoroethane  

Microsoft Academic Search

We present new data for the vapor pressure and PVT surface of 1,1,1,2-tetrafluoroethane (Refrigerant 134a) in the temperature range 40 C (313 K) to 150 C (423 K). The PVT data are for the gas phase at densities up to one-half critical. Densities of the saturated vapor are derived at five temperatures from the intersections of the experimental isochores with

L. A. Weber

1989-01-01

51

High-accuracy measurements of the vapor pressure of ice referenced to the triple point  

NASA Astrophysics Data System (ADS)

vapor pressure of hexagonal (Ih) water ice was measured over the temperature range 175 K to 253.4 K and referenced to the value at the triple point of water. This experiment combined a highly accurate humidity generation system containing an ice-coated saturator (millikelvin-level temperature control) to provide humidified streams of nitrogen to a cavity-enhanced laser absorption spectrometer. The measured ice vapor pressures had relative standard uncertainties ranging from 0.4% to 0.7% over the entire temperature range. We demonstrate that these measurements validate thermodynamic correlations for ice vapor pressure based on integration of the Clapeyron equation. Moreover, they also indicate that some commonly used vapor pressure correlations are inaccurate and should be avoided.

Bielska, Katarzyna; Havey, Daniel K.; Scace, Gregory E.; Lisak, Daniel; Harvey, Allan H.; Hodges, Joseph T.

2013-12-01

52

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

PubMed

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

Rane, Kaustubh S; Errington, Jeffrey R

2013-07-01

53

Heavily p-type doped chemical vapor deposition graphene field-effect transistor with current saturation  

NASA Astrophysics Data System (ADS)

Current saturation in graphene field-effect transistor (GFET) is of significant importance to improve the maximum oscillation frequency (fmax). We investigated the direct current (dc) and radio frequency (rf) characteristics of a heavily p-type doped GFET based on chemical vapor deposition grown material. The drain current saturation is found in our device. It cannot be explained by the "pinch-off" effect associated with ambipolar transport, but can be attributed to nonlinear channel conductance and velocity saturation in unipolar channel. This study promotes understanding the behaviors of heavily doped GFETs and their radio frequency applications.

Peng, Song-ang; Jin, Zhi; Ma, Peng; Yu, Guang-hui; Shi, Jing-yuan; Zhang, Da-yong; Chen, Jiao; Liu, Xin-yu; Ye, Tian-chun

2013-11-01

54

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)

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.

Joachim, William F; Rothrock, A M

1930-01-01

55

Vapor-liquid equilibrium for carbon dioxide + 1-butanol at high pressure  

Microsoft Academic Search

Phase equilibrium properties of mixtures at high pressures are required for practical use such as in the design and operation of separation equipment in the petroleum natural gas, and related industries. Vapor-liquid equilibria and saturated densities for carbon dioxide + 1-butanol at high pressures were measured at 313.15 K including in the vicinity of the critical region with the static-circulation

Katsuo Ishihara; Akira Tsukajima; Hiroyuki Tanaka; Masahiro Kato; Takeshi Sako; Masahito Sato; Toshikatsu Hakuta

1996-01-01

56

Evaluation of a gas-chromatographic method for estimating vapor pressures with organic pollutants  

SciTech Connect

The vapor pressures of 58 organic compounds of environmental concern - 20 organophosphorus, 14 carbamate and 11 organochlorine pesticides, 3 chlorinated biphenyls, 5 phthalates, and 5 polynuclear aromatic hydrocarbons - vary widely in chemical structure, polarity, and volatility - were estimated using a method based upon GC retention data. The GC method provided vapor pressures agreeing with an average factor of error of 3.1 with experimental vapor pressures which were determined experimentally by a standard gas saturation method or selected from literature values. The agreement between the GC-estimated vapor pressure and the experimental value improved when the comparison was with test compounds which are liquids at room temperature and when the polarity of the GC reference compound approximated that of the test compounds, especially for organophosphorus compounds. Melting point correction for both the test and reference compound gave the best estimates of vapor pressure of solid compounds with the GC method. At least 5 temperatures with at least 5/sup 0/C difference between them, or 3 temperatures with at least 15/sup 0/C difference gave an acceptable precision in the GC method. The necessity of future work on the accurate determination of vapor pressure of reference compounds using conventional methods and refinement of the melting point correction procedure was emphasized.

Kim, Y.H.

1985-01-01

57

Pure-component vapor pressures using UNIFAC group contribution  

SciTech Connect

A group-contribution model, in part based on the UNIFAC method for vapor-liquid equilibria, is developed for predicting pure-component vapor pressures. The model is applied to different hydrocarbons, alcohols, ketones, organic acids, and chloroalkanes of molecular weights below 500. Good representation is obtained for vapor pressure data in the region 10-2000 mmHg. The model may be used to estimate vapor pressures within the above category of compounds for which no experimental data are available. 12 refs.

Jensen, T.; Fredenslund, A.; Rasmussen, P.

1981-08-01

58

Stress dependent thermal pressurization of a fluid-saturated rock  

NASA Astrophysics Data System (ADS)

Temperature increase in saturated porous materials under undrained conditions leads to thermal pressurization of the pore fluid due to the discrepancy between the thermal expansion coefficients of the pore fluid and of the solid matrix. This increase in the pore fluid pressure induces a reduction of the effective mean stress and can lead to shear failure or hydraulic fracturing. The equations governing the phenomenon of thermal pressurization are presented and this phenomenon is studied experimentally for a saturated granular rock in an undrained heating test under constant isotropic stress. Careful analysis of the effect of mechanical and thermal deformations of the drainage and pressure measurement system is performed and a correction of the measured pore pressure is introduced. The test results are modelled using a non-linear thermo-poro-elastic constitutive model of the granular rock with emphasis on the stress-dependent character of the rock compressibility. The effects of stress and temperature on thermal pressurization observed in the test are correctly reproduced by the model.

Ghabezloo, S.; Sulem, J.

2009-02-01

59

Vapor Pressure of Bis-(2-chloroethyl)ethylamine (HN1).  

National Technical Information Service (NTIS)

Previous laboratory measurements of the vapor pressure of bis-(2- chloroethyl)ethylamine (HN1) were done in the 1940s and were only measured down to a temperature of 10 C. We have recently made additional measurements of the vapor pressure of the vesicant...

A. C. Samuels B. R. Williams J. R. Miles M. S. Hulet

2013-01-01

60

Vapor pressure of phenethyl alcohol in an aqueous hydrotrope solution  

Microsoft Academic Search

The vapor pressures of phenethyl alcohol in aqueous solutions of sodium xylene sulfonate were determined by headspace gas chromatography analysis. The results, surprisingly, showed the vapor pressure to be a function of only the fragrance-hydrotrope mole fraction and independent of hydrotrope concentration, when the latter exceeded a critical concentration.

Stig E. Friberg; Lin Fei; Samuel Campbell; Huafang Yang; Yingchun Lu

1997-01-01

61

The Vapor Pressure of Tetrafluoromethane from 86-146K.  

National Technical Information Service (NTIS)

The vapor pressure of CF, has been measured from 86-146K. The equation log p(torr) = 8.5019 - 769.89/T represents the data for the solid. Above the triple point, 89.55K, the vapor pressure is represented by the equation, log p(torr) = 6.836841 - 511.69474...

M. Simon C. M. Knobler A. G. Duncan

1966-01-01

62

The hysteretic evapotranspiration - vapor pressure deficit relation  

NASA Astrophysics Data System (ADS)

Diurnal hysteresis between evapotranspiration (ET) and vapor pressure deficit (VPD) was reported in many ecosystems but justification for its onset and magnitude remain incomplete with biotic and abiotic factors invoked as possible explanations. To place these explanations within a mathematical framework, ';rate-dependent' hysteresis originating from a phase angle difference between periodic input and output time series is first considered. Lysimeter evaporation (E) measurements from wet bare soils and model calculations using the Penman equation demonstrate that the E-VPD hysteresis emerges without any biotic effects due to a phase angle difference (or time lag) between net radiation the main driver of E, and VPD. Modulations originating from biotic effects on the ET-VPD hysteresis were then considered. The phase angle difference representation earlier employed was mathematically transformed into a storage problem and applied to the soil-plant system. The transformed system shows that soil moisture storage within the root zone can produce an ET-VPD hysteresis prototypical of those generated by phase-angle differences. To explore the interplay between all the lags in the soil-plant-atmosphere system and phase angle differences among forcing and response variables, a detailed soil-plant-atmosphere continuum (SPAC) model was developed and applied to a grassland ecosystem. The results of the SPAC model suggest that the hysteresis magnitude depends on the radiation-VPD lag. The soil moisture dry-down simulations also suggest that modeled root water potential and leaf water potential are both better indicators of the hysteresis magnitude than soil moisture, suggesting that plant water status is the main factor regulating the hysteretic relation between ET and VPD. Hence, the genesis and magnitude of the ET-VPD hysteresis are controlled directly by both biotic factors and abiotic factors such as time lag between radiation and VPD originating from boundary layer processes. Measured eddy covariance evapotranspiration (ET) and vapor pressure deficit (VPD) time series normalized by their maximum values collected in a grassland ecosystem. The magnitude of the hysteresis is quantified as the area enveloped by the ET-VPD relation (Ahys). The arrows together with time ticks indicate the progression of the diurnal cycle from sunrise to sunset.

Zhang, Q.; Manzoni, S.; Katul, G. G.; Porporato, A. M.; Yang, D.

2013-12-01

63

Measuring the Two?Phase Capillary Pressure?Saturation Curves of Soil Samples Saturated with Nonpolar Liquids  

Microsoft Academic Search

The simulation of multiphase fluid flow in the subsurface of soil requires that the pressure?saturation (P?S) relations of the porous medium be known for all fluid pairs. The objective of this study was 1) to develop a technique for routinely measuring the pressure?saturation (PS) curves of undisturbed soil samples saturated with NAPL 2) to build a database using the measured

Andrs Mak

2005-01-01

64

Broadband ultrafast saturable absorber based on thin and dense alkaline molecular vapors  

NASA Astrophysics Data System (ADS)

A Saturable Absorber based on thin and dense Cs2 + Rb2 + K2 molecular vapor mixture has been investigated. It is revealed that relaxation time of photobleaching effect in dense Cs2 + Rb2 + K2 is decreased with the mixture density and achieves 280 ps. It is demonstrated experimentally that a train of 3 - 5 pulses with the pulse duration of approximately 300 ps is generated as a result of passive Q-switching of YAG:Nd3+ laser. Such experiments are possible to perform due to development of unique sapphire cell containing the mixture of molecular vapor. There are several advantages of the mixture usage as a Saturable Absorber for passive Q-switching of solid state lasers.

Sarkisyan, David G.; Sarkisyan, A. S.

1999-12-01

65

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

SciTech Connect

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.

Suuberg, E.M.

1995-04-01

66

Vapor pressures of C3-C9 dicarboxylic acids  

NASA Astrophysics Data System (ADS)

Partitioning of organic compounds between gas and particle phase is determined by many factors including solubility in water, adsorption onto available particle surfaces, and dissolution into a potential organic aerosol phase. Pankow (1994) has derived the governing equations for the last two effects and shown that the vapor pressure is a key parameter in describing partitioning of low volatility organic compounds between gas and particle phase. As recently pointed out by Asher et al. (2002) the lack of experimental data on vapor pressures is very unfortunate since compounds with low vapor pressures partition to the particulate phase to the greatest extend. In this work we derive vapor pressures, heats of vaporization and surface free energies of a series of secondary organic aerosol components from measurements of evaporation rates of sub-micron particles (TDMA--technique). We focus on straight chain and methyl substituted aliphatic dicarboxylic acids, which have been identified as common water-soluble organic components of atmospheric sub-micron aerosols. We show that the TDMA technique can capture odd-even variations of vapor pressures of dicarboxylic acids and discuss how molecular symmetry and solid-state structure influence vapor pressures and heats of vaporization.

Rosenrn, T.; Mnster, J.; Svenningsson, B.; Bilde, M.

2003-04-01

67

Ultrasonic speeds in compressed liquid and vapor pressures for 1,1,1,2-tetrafluoroethane  

SciTech Connect

Ultrasonic speeds in the liquid phase of 1,1,1,2-tetrafluoroethane (CF{sub 3}CH{sub 2}F) have been measured from 243.11 K to 333.15 K and from near the saturation line to about 30 MPa. The measurements were made using a sing-around technique employing a fixed path acoustic interferometer operated at a frequency of 2 MHz. The probable uncertainty in the results was no greater than {+-}0.2% except in the low-density region at near the saturation line at higher temperatures. The vapor pressures have also been observed to within {+-}10 kPa by monitoring the acoustic signal at vapor-liquid equilibrium. When these results were combined, the ultrasonic speeds for the saturated liquid were estimated to within {+-}1 m/s.

Takagi, T. [Kyoto Inst. of Tech. (Japan)] [Kyoto Inst. of Tech. (Japan)

1996-09-01

68

Combined Effects of Saturation Pressure and Gas Desorption on Foaming Characteristics of Microcellular Plastics  

Microsoft Academic Search

The microcellular foaming process consists of the saturation process for dissolving gas molecules into plastic and the subsequent foaming process for cell formation. Foaming characteristics of microcellular plastics (MCPs) such as foaming ratio and cell morphology are largely determined by the saturation conditions, particularly by the saturation pressure. In this study, we investigate the effects of saturation pressure on the

Jung-Hwan Seo; Won-Suk Ohm; Soo-Hyun Cho; Sung W. Cha

2011-01-01

69

Experimental measurement of vapor pressures and (vapor + liquid) equilibrium for {1,1,1,2-tetrafluoroethane (R134a) + propane (R290)} by a recirculation apparatus with view windows  

Microsoft Academic Search

The saturated vapor pressures of 1,1,1,2-tetrafluoroethane (R134a) and propane (R290), and the (vapor+liquid) equilibrium (VLE) data at (255.000, 265.000, 275.000, and 285.000)K for the (R134a+R290) system were measured by a recirculation apparatus with view windows. The uncertainty of the temperatures, pressures, and compositions are less than 5mK, 0.0005MPa, and 0.005, respectively. The saturated vapor pressures data were correlated by a

Xueqiang Dong; Maoqiong Gong; Junsheng Liu; Jianfeng Wu

2011-01-01

70

Controlling the vapor pressure of a mercury lamp  

DOEpatents

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.

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

1988-05-24

71

Diode laser study of high-pressure water vapor spectroscopy  

Microsoft Academic Search

Measurements of water vapor are relevant to combustion, since water vapor concentration can be related to performance parameters such as combustion and propulsion efficiencies, and heat release. The development of a diode-laser based diagnostic to monitor water vapor and temperature in high-pressure and -temperature environments relevant to combustion by probing near-IR H 2O absorption features near 7117 and 7185 cm-1

Venu Nagali

1999-01-01

72

Development of vapor pressure in FR4-copper composite material during solder reflow process  

NASA Astrophysics Data System (ADS)

This paper presents a finite element (FE) methodology for predicting the distribution of vapor pressure in a simple FR4-copper composite material when it is heated up to 215C. A general purpose finite element software was used to develop a two-dimensional plane strain model of the composite material. FE simulation of transient moisture absorption was performed to predict the distribution of wetness fraction in the material after pre-conditioning at an 85C/85%RH environment for 15 days. FE simulation of transient moisture desorption was carried out at the peak solder reflow temperature of 215C to predict new distribution of wetness fraction in the material. The results of the moisture desorption analysis were used to compute the magnitude of vapor pressure in the material and its distribution at 215C. It was found that the moisture in the material redistributes itself during solder reflow. The moisture concentration in the area close to the FR4-copper interface below the longer copper trace increases during the solder reflow. The magnitude of the vapor pressure in 70% of the FR4 and near the FR4-copper interface below the lower copper trace is closed to the saturation pressure of water vapor at 215C. The distribution of the vapor pressure in the material is in similar fashion as the new distribution of wetness fraction after the moisture desorption analysis.

Kamsah, Nazri; Tamin, Mohd Nasir; Kamar, Haslinda Mohamed; Lahuri, Hidayatunnur; Wagiman, Amir Nur Rashid

2012-06-01

73

Measurements of the vapor pressure of cesium by absorption of resonance radiation, lambda = 8521  

Microsoft Academic Search

We have measured using optical means the absolute density of the saturated vapor pressure of cesium by absorption of resonance radiation corresponding to the 62P3\\/2-->62S1\\/2 transition. Experimental results are compared with those obtained with a surface-ionization gauge and with the Taylor-Langmuir equations. Density was measured between 12.5C and 39.2C in this temperature range the experimental error is about 10%. For

P. Pradel; F. Roussel; G. Spiess

1974-01-01

74

The vapour pressures over saturated aqueous solutions of dl-2-aminobutyric acid, 4-aminobutyric acid, sodium- d-gluconate, sodium hippurate, and potassium magnesium- l-aspartate  

Microsoft Academic Search

Vapour pressures of water over saturated solutions of dl-2-aminobutyric acid, 4-aminobutyric acid, sodium-d-gluconate, sodium hippurate, and potassium magnesium-l-aspartate were determined over the (278 to 322)K temperature range. The determined vapour pressures were used to obtain the water activities, the molar enthalpies of vaporization, and the osmotic coefficients of sodium-d-gluconate.

Alexander Apelblat; Eli Korin

2008-01-01

75

Optimal pressures and temperatures for isobaric, isothermal chemical vapor infiltration  

Microsoft Academic Search

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

John Y. Ofori; Stratis V. Sotirchos

1996-01-01

76

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

ERIC Educational Resources Information Center

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)

Levinson, Gerald S.

1982-01-01

77

Pressure Effects of Homogeneous Rubidium Vapor on Its Resonance Lines  

Microsoft Academic Search

The broadening of the resonance lines of rubidium in absorption under pressures up to 150 mm of its own homogeneous vapor was studied by means of a 21-foot grating. Under pressures below 1 mm the broadening of the lines was very symmetrical and the line contours could be described by the dispersion formula, but when the pressure was high the

Ch'en Shang-Yi

1940-01-01

78

Vapor pressure determination of hydroxy-cyclo-pentyl-butadiyne  

Microsoft Academic Search

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°C.

R. G. Garza; C. A. Colmenares

1983-01-01

79

THE VAPOR PRESSURES OF LIQUID Bi-BiCl SOLUTIONS  

Microsoft Academic Search

The vapor pressures of pure BiCl and of Bi--BiCl mixtures ; were redetermined wtth the quasi-static and spiral gage methods and compared with ; data by the transpiration method. The agreement ts within experi;

F. J. Jr. Keneshea; W. Wilson; D. Cubicciotti

1960-01-01

80

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

ERIC Educational Resources Information Center

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

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

2007-01-01

81

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

NASA Astrophysics Data System (ADS)

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.

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

2012-07-01

82

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

PubMed

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

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

2012-07-01

83

Piecewise Saturation-Dependent Capillary Pressure and Hydraulic Conductivity Models  

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

84

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

NASA Astrophysics Data System (ADS)

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 are retrieved from microwave CO spectra around Mars aphelions in 1980, 1982, 1989, 1991, 1993, and 1995. These microwave temperature retrievals are 15-20 K colder than the Viking temperature measurements at the same season in 1976 and 1978, implying dust-free, radiative-convective conditions for the global Mars atmosphere at the aphelions of the microwave measurements. Mars water profiling from very large array water and Kitt Peak water isotope spectra were obtained in the 1993 and 1995 Mars aphelion periods. Their analysis indicates that Mars water vapor at low to mid latitudes was confined to altitudes below 10 km during these aphelion periods, in agreement with the low altitude of water vapor saturation predicted by the cold microwave temperature profiles. The existence of such low-altitude water vapor saturation for the aphelion Mars atmosphere is corroborated by HST ultraviolet and violet cloud imaging of the Mars atmosphere in 1991, 1993, and 1995. These images display a previously unidentified, global belt of moderate opacity (? 0.2-0.6) clouds covering the 10S-30N latitude region around Mars aphelion (solar longitude, Ls 60-100) for three consecutive Mars years. The center of this low-latitude cloud belt corresponds to the region of upward advection within the summer solstice Hadley circulation. These cold atmospheric temperatures, low altitudes of water vapor saturation, and low-latitude cloud belts are observed only around Mars aphelion, which presently occurs during northern late spring/early summer (L s= 71). This behavior reflects the highly elliptical Mars orbit in which global surface and atmospheric temperatures vary by 20 K with orbital distance from the sun. The perihelion of Mars (southern late spring/early summer, Ls= 251) is recognized as the season of global dust storms, which result from the higher solar flux incident at perihelion (e.g., Zurek and Martin 1993). We argue that the aphelion period exhibits a similarly distinct climate (cloudy and cold), which was not as apparent during the unusually dusty Mars years of the Viking observations. We further argue that this aphelion climate may be the key to understanding the large north-south hemispheric asymmetries of Mars water vapor and the residual polar ice caps. The orbital dependence of the altitude of water vapor saturation can couple with the solstice Hadley circulations of the Mars atmosphere to create a non-linear atmospheric water pump toward the aphelion summer hemisphere. It is even possible that this process accounts for the origin of the polar layered deposits, as the hemispheric direction of this water pump alternates every 25,000 years due to the orbital progression of the season of Mars perihelion. We also point out that an increased importance for global cloud formation in the Mars atmosphere suggests important non-linear relationships between atmospheric water and dust in the current Mars climate, which may contribute to the extreme interannual variations of Mars dust storm behavior and the current albedo and compositional differences of the north and south polar ice deposits.

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

1996-07-01

85

Vapor pressures and heats of vaporization of primary coal tars. Quarterly technical progress report, 1 January 1993--31 March 1993  

SciTech Connect

The vapor pressure correlations that exist at present for high molecular weight organics 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. It has been concluded that the saturation method holds significant promise as technique for measuring vapor pressures of pure components in the correct molecular weight regime. There are several aspects of experimental design that need further work in to improve performance. Most critical is the saturator device.

Suuberg, E.M.

1993-07-01

86

Subatmospheric vapor pressures evaluated from internal-energy measurements  

NASA Astrophysics Data System (ADS)

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.

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

1997-01-01

87

Experimental Studies on Characteristics of Pressure Attenuation and Recovery to Saturation for Decompressive Disturbances in Low Pressurized Water  

Microsoft Academic Search

Slightly pressurized water (Psat = 1.26.0 bar) was flashed into steam void by step decompression to atmospheric pressure, using a shock tube type device with vertical test section, made of stainless steel pipe about 2 m long, with an inner diameter of 40 mm. The transient pressure depression below saturation and the time constant of pressure recovery to the saturation

Keiji MIYAZAKI; Kazuo MUKAI; Yoichi FUJII-E; Tokuo SUITA

1974-01-01

88

Autogenous pressurization of cryogenic vessels using submerged vapor injection  

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

89

A numerical study of high-pressure droplet vaporization  

SciTech Connect

This paper reports that the evaporation of single, spherical fuel droplets in a high-pressure, high-temperature environment has been studied numerically. The model is fully transient in both the liquid and the vapor phases. Transport properties are functions of temperature, pressure, and composition, and vary throughout the liquid droplet and the vapor boundary layer. Equilibrium at the liquid-vapor interface is calculated using the Peng-Robinson equation of state, and accounts for diffusion of the gas into the liquid droplet. The Peng-Robinson equation of state is also used to calculate the enthalpy of vaporization of the fuel species as well as the liquid and vapor mixture densities. The proposed model is compared with data obtained for a variety of liquids. The comparisons include the predictions of the critical mixing state, droplet vaporization rate, and droplet temperature. Transient effects in both the liquid and vapor phases are found to have a large effect on the droplet heatup and vaporization process.

Curtis, E.W.; Farrell, P.V. (Wisconsin Univ., Madison, WI (United States). Dept. of Mechanical Engineering)

1992-08-01

90

A numerical study of high-pressure droplet vaporization  

NASA Astrophysics Data System (ADS)

The evaporation of single, spherical fuel droplets in a high-pressure, high-temperature environment has been studied numerically. The model is fully transient in both the liquid and the vapor phases. Transport properties are functions of temperature, pressure, and composition, and vary throughout the liquid droplet and the vapor boundary layer. Equilibrium at the liquid-vapor interface is calculated using the Peng-Robinson equation of state, and accounts for diffusion of the gas into the liquid droplet. The Peng-Robinson equation of state is also used to calculate the enthalpy of vaporization of the fuel species as well as the liquid and vapor mixture densities. The proposed model is compared with data obtained for a variety of liquids. Transient effects in both the liquid and vapor phases are found to have a large effect on the droplet heatup and vaporization process. At very high temperature and pressure conditions the droplets were found to reach their thermodynamic critical mixing point in a totally transient process.

Curtis, E. W.; Farrell, P. V.

1992-08-01

91

Vapor pressure scanning implications of CdTe crystal growth  

NASA Astrophysics Data System (ADS)

Vapor pressure scanning (VPS) is a direct high precision method of investigation of the composition of non-stoichiometric crystals at high temperatures. It is based on experimental measurements of the vapor pressure, from which three-dimensional P- T- X (pressure-temperature-composition) range of existence of the crystalline phase is constructed. For CdTe the accuracy of the VPS determination of nonstoichiometry was proved to be within 10 -4 at% for temperatures up to the melting point (1365 K). In this communication it is shown how to apply experimental P- T- X phase equilibrium data for preparation of the material with controlled composition, either stoichiometric or with a certain deviation from stoichiometry. Different technologies are analyzed: vapor phase growth, vertical, horizontal and high pressure Bridgman.

Greenberg, Jacob H.

1999-02-01

92

Water-vapor pressure control in a volume  

NASA Technical Reports Server (NTRS)

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.

Scialdone, J. J.

1978-01-01

93

Experimental Characterization of Redox Changes During Degassing of a Vapor Saturated Magma: Redox Exchanges Between H-O-Fe Species  

NASA Astrophysics Data System (ADS)

The redox state of a magma reaching the surface is generally thought to be buffered by its iron redox ratio during ascent, reflecting therefore that of its source region. Only recently, the role of volatiles degassing on redox state of silicic magmas has been quantitatively addressed using numerical modelling. In these iron-poor magmatic systems, oxygen fugacity (fO2) is almost dominated by the chemical potential of the H2 and H2O volatile components. Because water is several orders of magnitude more soluble than molecular hydrogen in molten silicate, it was found that the ratio of their chemical potential dramatically changes during closed system degassing leading to an increase in fO2 of 2 orders of magnitude. We present here the results of an experimental test of such an oxidation event associated to the decompression of silicic melts saturated in volatiles. A peralkaline synthetic composition containing 2-4wt percent of dissolved iron oxides is used as starting material. Experiments are performed in cold seal pressure vessels pressurized with pre-mixed argon and hydrogen bottles. All experiments are equilibrated under water-saturated conditions at 800C and variable pressures between 200 MPa and 25 MPa. Experiments were ended by rapid drop quench. Three oxygen fugacity conditions were investigated by using pure Argon (NNO+3) and two Ar-H2 mixtures buffering fO2 conditions at NNO+1.5 and NNO. Water content was determined using infrared spectroscopy and Karl-Fisher titration and the iron redox ratio was measured by wet chemistry. All run products are free of crystals. Time series experiments at fixed pressure were performed to determine the equilibrium dependence of iron redox ratios on pressure. Decompression experiments were performed from an equilibrated vapor-saturated melt at 200 MPa, lasted from few minutes to few hours, and were quenched at 100 MPa to 25 MPa. The measured iron redox ratios after decompression do not considerably differ from the ones before decompression. A slight oxidation is however noticed for some experiments, which can correspond to 0.7 log- units of fO2 increase in the most favorable cases. We conclude that a "Le Chatelier effect" most likely dominates and restricts the fO2 increase that is otherwise expected to be of ~2 log units in an iron-free melt: The increase in the fugacity ratios of H2O/H2 due to degassing upon decompression is restricted by H2 produced during oxidation of ferrous iron by water. The importance of this "Le Chatelier effect" strongly depends on the fO2 conditions prior to degassing.

Mollard, E.; Gaillard, F.; Scaillet, B.

2007-12-01

94

Vapor pressures and vapor compositions in equilibrium with hypostoichiometric uranium dioxide at high temperatures  

NASA Astrophysics Data System (ADS)

Thermodynamic functions of the gaseous species, thermodynamic functions of the condensed phase, and an oxygen-potential model have been combined to calculate the vapor pressures and vapor compositions in equilibrium with condensed-phase UO 2-x for 1500?T?6000 K and 0? x ?0.5. A method for extending the oxygen-potential model of Blackburn to the liquid region has been derived and evaluated. Results of these calculations show that the oxygen-to-uranium ratio of the vapor is larger than that of the condensed phase with which it is in equilibrium for most of the ranges of T and x of interest. Near 6000 K the vapor is very oxygen-rich so that the composition of the condensed phase would be changed considerably by even a few percent vaporization. In general, the vapor in equilibrium with UO 2-x is poorly approximated at UO 2(g); the species U, UO, UO 3, O 2, and O each have higher partial pressures than UO 2 for some conditions. The calculated total pressures at high temperatures are in good agreement with those recommended by the International Working Group on Fast Reactors (IWGFR).

Green, David W.; Leibowitz, Leonard

1982-02-01

95

40 CFR 796.1950 - Vapor pressure.  

Code of Federal Regulations, 2010 CFR

...68-01-5117 with SRI International, Menlo Park, California...Density of Dieldrin, Journal of Agricultural and Food Chemistry, 3:664-670...Pressure of Lindane, Journal of Agricultural and Food Chemistry,...

2010-07-01

96

40 CFR 796.1950 - Vapor pressure.  

Code of Federal Regulations, 2010 CFR

...68-01-5117 with SRI International, Menlo Park, California...Density of Dieldrin, Journal of Agricultural and Food Chemistry, 3:664-670...Pressure of Lindane, Journal of Agricultural and Food Chemistry,...

2009-07-01

97

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

SciTech Connect

Vapor pressures and vapor compositions have been calculated for 1500 less than or equal to T less than or equal to 4000/sup 0/K. Thermodynamic functions for the condensed phase and for each of the gaseous species were combined with an oxygen-potential model extended into the liquid region to obtain the partial pressures of O/sub 2/, O, Pu, PuO and PuO/sub 2/. The calculated oxygen pressures increase very rapidly as stoichiometry is approached. At least part of this increase is a consequence of the exclusion of Pu/sup 6 +/ from the oxygen-potential model. No reliable method was found to estimate the importance of this ion. As a result of large oxygen potentials at high temperatures, extremely high total pressures that produced unreasonably high vapor densities were calculated. The highest temperature was therefore limited to 400 K, and the range of oxygen-to-metal ratios was limited to 1.994 to 1.70. These calculations show that vapor in equilibrium with hypostoichiometric plutonium dioxide is poorly approximated as PuO/sub 2/ for most of the temperture and composition range of interest. The vapor is much more oxygen-rich than the condensed phase. Implications for the (U,Pu)O/sub 2-x/ system are discussed. (DLC)

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

1982-01-01

98

Pump for Saturated Liquids  

NASA Technical Reports Server (NTRS)

Boiling liquids pumped by device based on proven components. Expanding saturated liquid in nozzle and diverting its phases along separate paths in liquid/vapor separator raises pressure of liquid. Liquid cooled in process. Pump makes it unnecessary to pressurize cryogenic liquids in order to pump them. Problems of introducing noncondensable pressurizing gas avoided.

Elliott, D. G.

1986-01-01

99

Vapor saturation and accumulation in magmas of the 1989-1990 eruption of Redoubt Volcano, Alaska  

USGS Publications Warehouse

The 1989-1990 eruption of Redoubt Volcano, Alaska, provided an opportunity to compare petrologic estimates of SO2 and Cl emissions with estimates of SO2 emissions based on remote sensing data and estimates of Cl emissions based on plume sampling. In this study, we measure the sulfur and chlorine contents of melt inclusions and matrix glasses in the eruption products to determine petrologic estimates of SO2 and Cl emissions. We compare the results with emission estimates based on COSPEC and TOMS data for SO2 and data for Cl/SO2 in plume samples. For the explosive vent clearing period (December 14-22, 1989), the petrologic estimate for SO2 emission is 21,000 tons, or ~12% of a TOMS estimate of 175,000 tons. For the dome growth period (December 22, 1989 to mid-June 1990), the petrologic estimate for SO2 emission is 18,000 tons, or ~3% of COSPEC-based estimates of 572,000-680,000 tons. The petrologic estimates give a total SO2 emission of only 39,000 tons compared to an integrated TOMS/COSPEC emission estimate of ~1,000,000 tons for the whole eruption, including quiescent degassing after mid-June 1990. Petrologic estimates also appear to underestimate Cl emissions, but apparent HCl scavenging in the plume complicates Cl emission comparisons. Several potential sources of 'excess sulfur' often invoked to explain petrologic SO2 deficits are concluded to be unlikely for the 1989-1990 Redoubt eruption - e.g., breakdown of sulfides, breakdown of anhydrite, release of SO2 from a hydrothermal system, degassing of commingled infusions of basalt in the magma chamber, and syn-eruptive degassing of sulfur from melt present in non-erupted magma. Leakage and/or diffusion of sulfur from melt inclusions do not provide convincing explanations for the petrologic SO2 deficits either. The main cause of low petrologic estimates for SO2 is that melt inclusions do not represent the total sulfur content of the Redoubt magmas, which were vapor-saturated magmas carrying most of their sulfur in an accumulated vapor phase. Almost all the sulfur of the SO2 emissions was present prior to emission as accumulated magmatic vapor at 6-10 km depth in the magma that supplied the eruption; whole-rock normalized concentrations of gaseous excess S in these magmas remained at ~0.2 wt.% throughout the eruption, equivalent to ~0.7 vol.% at depth. Data for CO2 emissions during the eruption indicate that CO2 at whole-rock concentrations of ~0.6 wt.% in the erupted magma was a key factor in creating the vapor saturation and accumulation condition making a vapor phase source of excess sulfur possible at depth. When explosive volcanism involves magma with accumulated vapor, melt inclusions do not provide a sufficient basis for predicting SO2 emissions. Thus, petrologic estimates made for SO2 emissions during explosive eruptions of the past may be too low and may significantly underestimate impacts on climate and the chemistry of the atmosphere. ?? 1994.

Gerlach, T. M.; Westrich, H. R.; Casadevall, T. J.; Finnegan, D. L.

1994-01-01

100

Vapor pressures and gas-film coefficients for ketones  

USGS Publications Warehouse

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.

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

1987-01-01

101

Distillation device supplies cesium vapor at constant pressure  

NASA Technical Reports Server (NTRS)

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.

Basiulis, A.; Shefsiek, P. K.

1968-01-01

102

Molecular weight of aquatic fulvic acids by vapor pressure osmometry  

Microsoft Academic Search

The molecular weights of aquatic fulvic acids extracted from five rivers were determined by vapor pressure osmometry with water and tetrahydrofuran as solvents. The values obtained ranged form 500 to 950 daltons, indicating that the molecular weights of aquatic fulvic acids are not as great as has been suggested in some other molecular weight studies. The samples were shown to

G. R. Aiken; R. L. Malcolm

1987-01-01

103

The liquefaction and displacement of highly saturated sand under water pressure oscillation  

Microsoft Academic Search

In order to investigate the characteristics of water wave induced liquefaction in highly saturated sand in vertical direction, a one-dimensional model of highly saturated sand to water pressure oscillation is presented based on the two-phase continuous media theory. The development of the effective stresses and the liquefaction thickness are analyzed. It is shown that water pressure oscillating loading affects liquefaction

Xiaobing Lu; Peng Cui

2004-01-01

104

Subatmospheric vapor pressures evaluated from internal-energy measurements  

SciTech Connect

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.

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

105

Accurate Vaporizing Gas-Drive Minimum Miscibility Pressure prediction  

SciTech Connect

Prediction of The Minimum Miscibility Pressure (MMP) of the Vaporizing Gas Drive (VGD) process is modeled using an equation of state with different mixing rules joined with a newly formulated expression for the unlike-three-body interactions between the injection gas and the reservoir fluid. The comparison of the numerical results with the available experimental data indicates that an equation of state alone overestimates the MMP. However, when the equation of state is joined with the unlike-three-body interaction term, the MMP will be predicted accurately. The proposed technique is used to develop a simple and reliable correlation for the accurate vaporizing gas drive MMR prediction.

Benmekki, E.H.; Mansoori, G.A.

1986-01-01

106

Vapor-liquid equilibria of cyclohexanol with carbon dioxide, ethane, or nitrogen at elevated pressures  

SciTech Connect

Vapor-liquid equilibrium (VLE) data were measured for the binary systems of cyclohexanol with carbon dioxide, ethane, or nitrogen at temperatures from 333.15 K to 453.15 K and pressures up to 190 bar. The saturated vapor compositions were correlated with the density of the light components. Henry`s constants of the gases dissolved in cyclohexanol were calculated with the aid of the Krichevsky-Ilinskaya equation. The new VLE data were also correlated by the Peng-Robinson and the Patel-Teja equations of state. In general, the Patel-Teja equation incorporating the one-fluid, two-parameter van der Waals mixing rule yielded the best representation.

Chen, J.T.; Lee, M.J. [National Taiwan Inst. of Tech., Taipei (Taiwan, Province of China). Dept. of Chemical Engineering] [National Taiwan Inst. of Tech., Taipei (Taiwan, Province of China). Dept. of Chemical Engineering

1996-03-01

107

Vapor saturation of sodium: Key to unlocking the origin of chondrules  

NASA Astrophysics Data System (ADS)

Sodium saturation of the vapor coexisting with chondrules at their liquidus temperatures implies that vapor-condensed phase equilibrium was reached at those temperatures for all elements more refractory than sodium. In order to investigate the possibility that chondrules formed in impact-generated plumes, equilibrium calculations were applied to droplets made from two different target compositions. Combinations of dust enrichment and Ptot were found that lead to sodium saturation, and the subsequent chemical and mineralogical evolution of the droplets was explored at those conditions. If an impact on a body of CI composition caused instantaneous heating, melting and devolatilization of the target rock and ejection of a plume of gaseous, liquid and solid matter that mixed with residual nebular gas at conditions where 50% or 90% of the sodium was retained by the resulting droplets at their liquidus temperature, their mineralogical and chemical properties would strongly resemble those of Type II chondrules. If the droplets cooled and equilibrated with the mixture of residual nebular gas and their devolatilized water, sulfur and alkalis, the fayalite content of the olivine and the chemical compositions of the bulk droplets and their glasses would closely resemble those of Types IIA and IIAB chondrules at CI dust enrichments between 400 and 800. For 50% sodium retention, the corresponding values of Ptot are 2 bars (for 400) and 1 bar (for 800). For 90% retention, they are 25 and 10 bars, respectively. If, instead, the target has an anhydrous, ordinary chondrite-like composition, called H', the ejected droplets are bathed in a gas mix consisting mostly of devolatilized sulfur and alkalis with residual nebular gas, a much more reducing plume. If the conditions were such that sodium were retained by the resulting droplets at their liquidus temperature, the fayalite contents of the olivine and the chemical compositions of the bulk droplets and their glasses would closely resemble those of Types IA and IAB chondrules at H' dust enrichments between 103 and 4 103. For 90% sodium retention, the corresponding values of Ptot are 15 bars (for 103) and 2 bars (for 4 103). For 50% retention, they are 2 and 8 10-2 bars, respectively.

Fedkin, Alexei V.; Grossman, Lawrence

2013-07-01

108

Method and apparatus to measure vapor pressure in a flow system  

DOEpatents

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.

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

1991-01-01

109

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...VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Containment Systems § 154.405 Design vapor pressure (Po ) of a...

2013-10-01

110

Vapor pressure and vapor fractionation of silicate melts of tektite composition  

USGS Publications Warehouse

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.

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

1964-01-01

111

A nonlinear regression analysis for estimating low-temperature vapor pressures and enthalpies of vaporization applied to refrigerants  

NASA Astrophysics Data System (ADS)

A new method is presented to extrapolate experimental vapor pressures down to the triple Point. The method involves a nonlinear regression analysis based on the Clausius Clapeyron equation and a simple relation for the enthalpy of vaporization Triple-point pressures and vapor pressures up to 0.1 0.2 MPa are estimated for R125, R32, R143a, R134a, R152a, R123, R124, and ammonia; they generally agree with available experimental data within their uncertainty, Equations for the enthalpy of vaporization which describe this property fairly well at low temperatures are obtained as a byproduct.

Tillner-Roth, R.

1996-11-01

112

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

Code of Federal Regulations, 2010 CFR

...2009-10-01 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...

2009-10-01

113

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

Code of Federal Regulations, 2010 CFR

...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...

2010-10-01

114

U.S. Strategic Petroleum Reserve Vapor Pressure Committee 2009 annual report  

Microsoft Academic Search

This report comprises an annual summary of activities under the U.S. Strategic Petroleum Reserve (SPR) Vapor Pressure Committee in FY2009. The committee provides guidance to senior project management on the issues of crude oil vapor pressure monitoring nd mitigation. The principal objectives of the vapor pressure program are, in the event of an SPR drawdown, to minimize the impact on

Ray Allen; Lisa Eldredge; Charles DeLuca; Patrick Mihalik; Julio Maldonado; David L. Lord; David Keith Rudeen; Gerard Berndsen

2010-01-01

115

Radiative and nonradiative processes in naphthoquinone vapors at low pressure  

NASA Astrophysics Data System (ADS)

Emission and excitation spectra and emission lifetimes have been investigated for 1,4-naphthoquinone (NQ) and 2-methyl-1,4-naphthoquinone (MNQ) vapors at low pressure (10-3-10-1 Torr). The vapors emit prompt fluorescence from the S1(n, ?*) state in addition to the phosphorescence and E-type delayed fluorescence. In the case of excitation into the S2(?, ?*) state, the quantum yield of the prompt fluorescence increases as the pressure is lowered, whereas the phosphorescence quantum yield decreases down to zero. For both NQ and MNQ vapors, the phosphorescence quantum yield shows characteristic excitation-energy dependence: the yield varies markedly according to the nature of the singlet state to which the molecule is initially excited. On the basis of the pressure and excitation-energy dependence of the emission quantum yields and lifetimes, the occurrence of the prompt fluorescence is interpreted in terms of a mechanism involving reversible intersystem crossing between S1 and a triplet state. It is shown that the prompt fluorescence consists of fast and slow components.

Itoh, Takao; Baba, Hiroaki

1980-09-01

116

Vapor-Phase Thermal Conductivity, Vapor Pressure, and Liquid Density of R365mfc  

Microsoft Academic Search

The thermal conductivity of a new fluoroalkane, R365mfc (1,1,1,3,3-pentafluorobutane), important for the production of polyurethane rigid foams, was measured using a transient hot wire method, at temp- eratures between 336.85 K and 377.4 K. The extended corresponding states theory was used successfully to predict the results, with an average absolute deviation of 0.5%. The vapor pressure (302.90 K to 358.15

Isabel M. Marrucho; Nelson S. Oliveira; Ralf Dohrn

2002-01-01

117

Chemical Vapor Deposition at High Pressure in a Microgravity Environment  

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

118

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

Microsoft Academic Search

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

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

1965-01-01

119

Optimal pressures and temperatures for isobaric, isothermal chemical vapor infiltration  

SciTech Connect

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 during isobaric isothermal CVI within a window of operating conditions. Optimal pressure-temperature pairs are determined as the solution of an optimization problem that seeks to minimize the processing time predicted by a CVI model under the constraint that the maximum density difference in the preform at the end of the densification does not exceed a preset limit. Results are presented on the dependence of the optimum processing time on the type of structure of the preform, the specifications that the final product has to conform to, and the kinetics of the chemical reaction. The results show that operation at low pressure affects adversely the processing time and that a dramatic reduction in the processing time can be achieved by operating in the vicinity of the optimal pressure.

Ofori, J.Y.; Sotirchos, S.V. [Univ. of Rochester, NY (United States). Dept. of Chemical Engineering] [Univ. of Rochester, NY (United States). Dept. of Chemical Engineering

1996-10-01

120

Saturated Fluorescence Measurements of the Hydroxyl Radical in Laminar High-Pressure Flames.  

National Technical Information Service (NTIS)

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...

C. D. Carter G. B. King N. M. Laurendeau

1990-01-01

121

Effect of relative vapor pressure on separation of nanoscale contact in atomic force microscope  

NASA Astrophysics Data System (ADS)

The separation of nanoscale contact junction is investigated in an atomic force microscope at various relative vapor pressure conditions. Gradual increase in adhesion force is observed as the relative vapor pressure increases. However, the force-deformation behaviors of the water-mediated nanoscale contacts vary extensively with the relative vapor pressure conditions. At low relative vapor pressure (p/ps<0.06), water molecules play a role as a weak glue contributing solid extension. In contrast, at high relative vapor pressure (p/ps=0.8), the highest adhesion force is observed without indication of the solid extension. The meniscus collapses and forms a water column after solids separates at an intermediate relative vapor pressure condition (p/ps=0.4). The detailed analysis revealed the transition of adhesion mechanism from the solid-dominant adhesion to liquid-dominant adhesion as the relative vapor pressure increases.

Kim, Doo-In; Jeong, Young-Keun; Kang, Myung-Chang; Ahn, Hyo-Sok; Kim, Kwang Ho

2010-12-01

122

Vapor pressures and vapor compositions in equilibrium with hypostoichiometric uranium dioxide at high temperatures  

SciTech Connect

Thermodynamic functions of the gaseous species, thermodynamic functions of the condensed phase, and an oxygen-potential model have been combined to calculate the vapor pressures and vapor compositions in equilibrium with condensed-phase UO/sub 2-x/ for 1500 less than or equal to T less than or equal to 6000 K and 0 less than or equal to x less than or equal to 0.5. A method for extending the oxygen-potential model of Blackburn to the liquid region has been derived and evaluated. New thermodynamic functions of the UO/sub 2/ condensed phase have been derived from the best available data, including the heat capacity recommended by Fink.

Green, D.W.; Leibowitz, L.

1981-06-01

123

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)

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.

Steffes, P. G.

1985-01-01

124

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

PubMed

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

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

2012-08-21

125

Ignitability of DMSO vapors at elevated temperature and reduced pressure  

SciTech Connect

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.

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

1999-03-08

126

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

SciTech Connect

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.

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

1999-05-01

127

Elasticity of Water-Saturated Rocks as a Function of Temperature and Pressure  

Microsoft Academic Search

Compressional and shear wave velocities of water-saturated rocks were measured as a function of both pressure and temperature near the melting point of ice to confining pres- sure of 2 kb. The pore pressure was kept at about 1 bar before the water froze. The pres- ence of a liquid phase (rather than ice) in microcracks of about 0.3% porosity

Shozaburo Takeuchi; Gene Simmons

1973-01-01

128

Analysis of the Saturation Phenomena of the Neutralization Rate of Positively Charged 218Po in Water Vapor.  

PubMed

Generally, 88% of the freshly generated Po ions decayed from Rn are positively charged. These positive ions become neutralized by recombination with negative ions, and the main source of the negative ions is the OH ions formed by radiolysis of water vapor. However, the neutralization rate of positively charged Po versus the square root of the concentration of H2O will be a constant when the concentration of H2O is sufficiently high. Since the electron affinity of the hydroxyl radical formed by water vapor is high, the authors propose that the hydroxyl radical can grab an electron to become OH. Because the average period of collision with other positively charged ions and the average life of the OH are much longer than those of the electron, the average concentration of negative ions will grow when the water vapor concentration increases. The authors obtained a model to describe the growth of OH ions. From this model, it was found that the maximum value of the OH ion concentration is limited by the square root of the radon concentration. If the radon concentration is invariant, the OH ion concentration should be approximately a constant when the water vapor concentration is higher than a certain value. The phenomenon that the neutralization rate of positively charged Po versus the square root of the water vapor concentration will be saturated when the water vapor concentration is sufficiently high can be explained by this mechanism. This mechanism can be used also to explain the phenomenon that the detection efficiency of a radon monitor based on the electrostatic collection method seems to be constant when the water vapor concentration is high. PMID:25068963

Tan, Yanliang; Xiao, Detao; Shan, Jian; Zhou, Qingzhi; Qu, Jingnian

2014-09-01

129

Temperature/pressure and water vapor sounding with microwave spectroscopy  

NASA Technical Reports Server (NTRS)

Two intense microwave spectra lines exist in the martian atmosphere that allow unique sounding capabilities: water vapor at 183 GHz and the (2-1) rotational line of CO at 230 GHz. Microwave spectra line sounding is a well-developed technique for the Earth's atmosphere for sounding from above from spacecraft and airplanes, and from below from fixed surface sites. Two simple instruments for temperature sounding on Mars (the CO line) and water vapor measurements are described. The surface sounder proposed for the MESUR sites is designed to study the boundary layer water vapor distribution and the temperature/pressure profiles with vertical resolution of 0.25 km up to 1 km with reduced resolution above approaching a scale height. The water channel will be sensitive to a few tenths of a micrometer of water and the temperature profile will be retrieved to an accuracy between 1 and 2 K. The latter is routinely done on the Earth using oxygen lines near 60 GHz. The measurements are done with a single-channel heterodyne receiver looking into a 10-cm mirror that is canned through a range of elevation angles plus a target load. The frequency of the receiver is sweep across the water and CO lines generating the two spectra at about 1-hr intervals throughout the mission. The mass and power for the proposed instrument are 2 kg and 5-8 W continuously. The measurements are completely immune to the atmospheric dust and ice particle loads. It was felt that these measurements are the ultimate ones to properly study the martian boundary layer from the surface to a few kilometers. Sounding from above requires an orbiting spacecraft with multichannel microwave spectrometers such as the instrument proposed for MO by a subset of the authors, a putative MESUR orbiter, and a proposed Discovery mission called MOES. Such an instrument can be built with less than 10 kg and use less than 15 W. The obvious advantage of this approach is that the entire atmosphere can be sounded for temperature and water vapor in a few hours with somewhat better than a scale height resolution. If a bigger mirror is used (greater than 30 cm) limb sounding geometry can be employed and half scale height resolution achieved to altitudes up to at least 60 km. Again, the measurements are immune to dust and ice loads. Water vapor sensitivity of 0.1 micrometer can be achieved (even with a nadir instrument) and temperature profiles retrieved to an accuracy of better than 2 K from the surface to about 60 km. Winds can be measured from the doppler shifts of CO lines in the limb sounding mode.

Muhleman, D. O.; Janssen, M. A.; Clancy, R. T.; Gulkis, S.; Mccleese, D. J.; Zurek, R.; Haberle, R. M.; Frerking, M.

1992-01-01

130

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

Code of Federal Regulations, 2013 CFR

...practicable to the vessel vapor connection, that measures the pressure in the main vapor collection line, which...controlled; (2) Activates an alarm when the pressure-sensing device measures a high pressure of not more than 90 percent of the...

2013-10-01

131

Online dynamic measurement of saturation-capillary pressure relation in sandy medium under water level fluctuation  

Microsoft Academic Search

An online dynamic method based on electrical conductivity probe, tensiometer and datataker was presented to measure saturation-capillary\\u000a pressure (S-p) relation in water-light nonaqueous phase liquid (LNAPL) two-phase sandy medium under water level fluctuation. Three-electrode\\u000a electrical conductivity probe (ECP) was used to measure water saturation. Hydrophobic tensiometer was obtained by spraying\\u000a waterproof material to the ceramic cup of commercially available hydrophilic

Yan Li; Jin-feng Zhou; Jun Xu; M. Kamon

2010-01-01

132

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)

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.

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

2011-01-01

133

250W diode laser for low pressure Rb vapor pumping  

NASA Astrophysics Data System (ADS)

The diode pumped alkali vapor lasers operating at subatmospheric pressure require developing of a new generation of high-power laser diode sources with about 10 GHz wide emission spectrum. The latest achievements in the technology of volume Bragg gratings (VBGs) recorded in photo-thermo-refractive glass opened new opportunities for the design and fabrication of compact external cavity laser diodes, diode bars and stacks with reflecting VBGs as output couplers. We present a diode laser system providing up to 250 W output power and emission spectral width of 20 pm (FWHM) at the wavelength of 780 nm. The stability and position of an emission wavelength is determined by the resonant wavelength of a VBG which is controlled by temperature. Stability of an emitting wavelength is within 5 pm. Thermal tuning of the wavelength provides maximum overlapping of emitting line with absorption spectrum of a Rb (rubidium)- cell. The designed system consists of 7 modules tuned to the same wavelength corresponding to D2 spectral line of Rb87 or Rb85 and coupled to a single output fiber. Analogous systems could be used for other Rb isotopes spectral lines as well as for lasers based on other alkali metal vapors (Cs and K) or any agents with narrow absorption lines.

Podvyaznyy, A.; Venus, G.; Smirnov, V.; Mokhun, O.; Koulechov, V.; Hostutler, D.; Glebov, L.

2010-02-01

134

Comparison of pressure-saturation characteristics derived from computed tomography and lattice Boltzmann simulations  

NASA Astrophysics Data System (ADS)

A Shan-Chen-type multiphase lattice Boltzmann (LB) model was applied to observed computed microtomography data from water-air and water-Soltrol displacement experiments in a glass bead porous medium. Analysis of the Bond, Reynolds, and Capillary numbers for these systems showed that capillary forces were dominant removing the need to model viscous, gravitational, and density effects. A numerical parameterization of the LB model yielded lattice surface tension and contact angle, and appropriate pressure boundary conditions. Two scaling relations provided a link between lattice pressure and physical pressure and lattice time and physical time. Results showed that there was a good match between measured and simulated pressure-saturation data for the water-air system, but that there were large differences between the simulations and observations for the water-Soltrol system. The discrepancies for the water-Soltrol system were probably due to inconsistencies between experimental conditions and simulated conditions such as nonzero contact angle in the experiments. Analysis of saturation profiles indicated increasing saturation near the wetting boundary and decreasing saturations near the nonwetting boundary. We attribute these saturation transitions to pore-neck and percolation effects. While computationally intensive, results of this study were very encouraging for the application of LB simulations to microscale interfacial phenomena. Future studies will carry out a further validation in terms of interfacial areas, contact lines, and fluid distributions.

Schaap, Marcel G.; Porter, Mark L.; Christensen, Britt S. B.; Wildenschild, Dorthe

2007-12-01

135

Molecular weight of aquatic fulvic acids by vapor pressure osmometry  

USGS Publications Warehouse

The molecular weights of aquatic fulvic acids extracted from five rivers were determined by vapor pressure osmometry with water and tetrahydrofuran as solvents. The values obtained ranged from 500 to 950 dallons, indicating that the molecular weights of aquatic fulvic acids are not as great as has been suggested in some other molecular weight studies. The samples were shown to be relatively monodisperse from radii of gyration measurements determined by small angle x-ray scattering. THF affords greater precision and accuracy than H2O in VPO measurements, and was found to be a suitable solvent for the determination of molecular weight of aquatic fulvic acid because it obviates the dissociation problem. An inverse correlation was observed with these samples between the concentration of Ca++ and Mg++ in the river water and the radii of gyration and molecular weights of the corresponding fulvic acid samples. ?? 1987.

Aiken, G. R.; Malcolm, R. L.

1987-01-01

136

Molecular weight of aquatic fulvic acids by vapor pressure osmometry  

SciTech Connect

The molecular weights of aquatic fulvic acids extracted from five rivers were determined by vapor pressure osmometry with water and tetrahydrofuran as solvents. The values obtained ranged form 500 to 950 daltons, indicating that the molecular weights of aquatic fulvic acids are not as great as has been suggested in some other molecular weight studies. The samples were shown to be relatively monodisperse from radii of gyration measurements determined by small angle x-ray scattering. THF affords greater precision and accuracy than H/sub 2/O in VPO measurements, and was found to be a suitable solvent for the determination of molecular weight of aquatic fulvic acid because it obviates the dissociation problem. An inverse correlation was observed with these samples between the concentration of Ca/sup + +/ and Mg/sup + +/ in the river water and the radii of gyration and molecular weights of the corresponding fulvic acid samples.

Aiken, G.R.; Malcolm, R.L.

1987-08-01

137

Vapor pressure and viscosity of 1,1,1,5,5,5-hexafluoro-2,4-pentanedione  

SciTech Connect

1,1,1,5,5,5-Hexafluoro-2,4-pentanedione (H{sup +}hfac) is a potential vapor-phase cleaning agent for removing trace transition metals from silicon wafer surfaces and for in situ removal of spurious bulk copper in Cu CVD chamber cleaning applications. The viscosity and vapor pressure of the reactive chelating ligand, H{sup +}hfac have been determined. The viscosity of liquid H{sup +}hfac was determined to be (1.39 {+-} 0.19) {times} 10{sup {minus}3} Pa{center_dot}s at 24 C and (8.35 {+-} 0.25) {times} 10{sup {minus}4} Pa{center_dot}s at 35 C. The vapor pressure of H{sup +}hfac was found to range from 4 kPa at 0 C to 49.5 kPa at 57 C. The viscosity was measured using a capillary tube viscometer, and the vapor pressure was measured using a mass transfer gas saturation apparatus. These methods were employed because conventional methodologies would have produced unreliable data due to the formation of the tetrol hydrate of H{sup +}hfac inside the apparatus and potentially exposed laboratory personnel to hazardous working conditions.

George, M.A.; Young, K.M.; Robertson, E.A. III; Beck, S.E. [Air Products and Chemicals, Inc., Allentown, PA (United States)] [Air Products and Chemicals, Inc., Allentown, PA (United States); Voloshin, G. [Schumacher Co., Carlsbad, CA (United States)] [Schumacher Co., Carlsbad, CA (United States)

1998-01-01

138

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

SciTech Connect

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.

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

1995-11-01

139

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

140

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

SciTech Connect

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.

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

141

Arterial blood oxygen saturation during blood pressure cuff-induced hypoperfusion  

NASA Astrophysics Data System (ADS)

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.

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

2007-10-01

142

High pressure vapor-liquid and vapor-liquid-liquid equilibria for systems containing supercritical carbon dioxide, water and furfural  

Microsoft Academic Search

We measured vapor-liquid equilibrium for a binary system CO2?furfural at temperatures of 303 and 323 K and vapor-liquid-liquid equilibrium for a ternary system CO2?water?furfural at temperatures of 303, 323 and 343 K and pressure of 5 MPa to obtain fundamental data for concentration of furfural by using three phase separation technique. Furthermore the experimental data were compared with results calculated

Takeshi Sako; Tsutomu Sugeta; Noriaki Nakazawa; Katsuto Otake; Masahito Sato; Katsuo Ishihara; Masahiro Kato

1995-01-01

143

Metal Vapor Condensation under High Pressure (Mercury Vapor to 500 Psia).  

National Technical Information Service (NTIS)

Mercury vapor up to 500 psia was condensed outside a cylindrical tube in both horizontal and vertical positions. Results show consistently low heat transfer coefficients compared to Nusselt's theory. Two auxiliary mercury vapor condensers downstream of th...

S. Hsieh C. F. Bonilla

1975-01-01

144

Tests of a Low-Pressure Switch Protected by a Saturating Inductor.  

National Technical Information Service (NTIS)

A triggered low-pressure switch has been tested switching a charged capacitor across a damping resistor simulating a transformer. A series saturating inductor protected the switch from electron beam anode damage. The capacitor was 15 mu F and charge volta...

E. J. Lauer D. L. Birx

1981-01-01

145

Molecular dynamics simulation of the structure of liquid rubidium along the saturated vapour-pressure curve  

Microsoft Academic Search

The structure and the thermal motion of ions in liquid rubidium are simulated for six states including the critical point along the saturated vapour-pressure curve using the molecular dynamics method. The effective pair potential between rubidium ions in expanded liquid states is calculated by extrapolating the optimised model potential parameters proposed by Cowley (1976) and the screening parameters of Singwi

M. Tanaka

1980-01-01

146

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...

147

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

NASA Astrophysics Data System (ADS)

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.

Gao, L.; Morozov, I. B.

2011-12-01

148

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...

149

Method and apparatus to measure vapor pressure in a flow system  

DOEpatents

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.

Grossman, M.W.; Biblarz, O.

1991-10-15

150

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

SciTech Connect

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.

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

1994-12-15

151

Solubility of hydrogen sulfide in pure water and in NaCl solutions, from 20 to 320C and at saturation pressures  

NASA Astrophysics Data System (ADS)

The solubility of hydrogen sulfide in pure water and in NaCl solutions has been studied experimentally from 20 to 320C and at saturation pressures. Hydrogen sulfide solutions in equilibrium with their vapor phase were contained in a pressurized titanium bellows of known total volume. The bellows transmitted inside-vapor pressures via a thermally stable oil (pressure medium) to a high-precision pressure sensor. Temperatures were measured by a sheathed thermocouple immersed into the oil surrounding the bellows. Values for the Henry constants were derived from measurements of equilibrium vapor pressure, volume, temperature, and bulk composition. The Henry constants agree well with previously published data up to about 200C, but then deviate towards lower values (higher solubilities) at higher temperatures. Henry constants from 20 to 320C and at saturation pressures may be obtained from the correlation log kH( T, Psat,1 ) = +0.6342702616 e + 3 + 0.2709284796 e + 0 T - 0.1 113202904 e - 3 T2 - 0.1671907660 e + 5/ T -0.2619219571 e + 3 logT, where khis in units of bar/molality and T in Kelvin. The experimental Henry constants have been fitted to a scaled particle theory model and have been tested by a recently proposed linearization procedure. The salting-out effect of NaCl on H 2S solubility is nearly independent of temperature up to about 250C, but then increases sharply as temperatures approach the critical point of water. Skeleton tables to 365C and for ionic strengths ? = 0, 1, 2, 3 have been prepared.

Suleimenov, O. M.; Krupp, R. E.

1994-06-01

152

Saturation effects in the sub-Doppler spectroscopy of cesium vapor confined in an extremely thin cell  

SciTech Connect

Saturation effects affecting absorption and fluorescence spectra of an atomic vapor confined in an extremely thin cell (cell thickness L<1 {mu}m) are investigated experimentally and theoretically. The study is performed on the D{sub 2} line ({lambda}=852 nm) of Cs and concentrates on the two situations L={lambda}/2 and L={lambda}, the most contrasted ones with respect to the length dependence of the coherent Dicke narrowing. For L={lambda}/2, the Dicke-narrowed absorption profile simply broadens and saturates in amplitude when increasing the light intensity, while for L={lambda}, sub-Doppler dips of reduced absorption at the line-center appear on the broad absorption profile. For a fluorescence detection at L={lambda}, saturation induces narrow dips, but only for hyperfine components undergoing a population loss through optical pumping. These experimental results are interpreted with the help of the various existing models and are compared with numerical calculations based upon a two-level modeling that considers both a closed and an open system.

Andreeva, C.; Cartaleva, S.; Petrov, L.; Saltiel, S. M.; Sarkisyan, D.; Varzhapetyan, T.; Bloch, D.; Ducloy, M. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tzarigradsko Shosse Boulevard, 1784 Sofia (Bulgaria); Faculty of Physics, Sofia University, 5 J. Bourchier Boulevard, 1164 Sofia (Bulgaria); Institute for Physical Research, NAS of Armenia, Ashtarak-2 (Armenia); Laboratoire de Physique des Lasers UMR 7538 du CNRS, Universite Paris-13, F-93430 Villetaneuse (France)

2007-07-15

153

Chemically enhanced mixed region vapor stripping of TCE-contaminated saturated peat and silty clay soils  

SciTech Connect

The objective of this study was to conduct further testing of MRVS, chemically enhanced with calcium oxide conditioning, on field- contaminated soils collected from beneath the NASA Michoud Rinsewater Impoundment. In this study, residual soil VOC levels as a function of vapor stripping time were measured to quantify VOC removal rates. Physical and chemical soil parameters expected to affect MRVS efficiency were measures. The effects of varying the calcium oxide loadings as well as varying the vapor stripping flow rates on VOC removal were also evaluated. The results of this study will be used to determine whether acceptable removals can be achieved within reasonable treatment times, remediation costs being directly proportional to the latter. The purpose of this report is to document the experimental results of this study, as well as to address issues that were raised after completion of the previous Michoud treatability work.

West, O.R.; Cameron, P.A.; Lucero, A.J.; Koran, L.J. Jr.

1996-01-01

154

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

PubMed

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

Kertsz, K; Piszter, G; Jakab, E; Blint, Zs; Vrtesy, Z; Bir, L P

2014-06-01

155

Reducing deuterium-tritium ice roughness by electrical heating of the saturated vapor  

SciTech Connect

High gain targets for inertial confinement fusion (ICF) contain a layer of deuterium-tritium (DT) ice which surrounds a volume of DT gas in thermal equilibrium with the solid. The roughness of the cryogenic fuel layer inside of ICF targets is one of the sources of imperfections which cause implosions to deviate from perfect one dimensional performance. Experiments at Lawrence Livermore National Laboratory have shown that applying a heat flux across the inner surface of a hydrogen layer such as that inside an ICF target reduces the intrinsic roughness of the surface. We have developed a technique to generate this heat flux by applying and electric field to the DT vapor in the center of these shells. This vapor has a small but significant conductivity due to ionization caused by beta decay of tritium in the vapor and the solid. We describe here experiments using a 1.15 GHz cavity to apply an electric field to frozen DT inside of a sapphire test cell. The cell and cavity geometry allows visual observation of the frozen layers.

Mapoles, E.R. [Lawrence Livermore National Lab., CA (United States); Sater, J.D.; Monsler, E. [Schafer (W.J.) Associates, Inc., Livermore, CA (United States); Pipes, J. [Allied-Signal Inc., Livermore, CA (United States)

1996-06-14

156

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

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

157

In-pile measurement of the total vapor pressure of liquid-oxide fuels. [No data  

SciTech Connect

Total vapor pressure measurements on liquid oxide fuels were performed in the Annular Core Research Reactor (ACRR). The extensive improvements in experiment design, test preparation and data analysis, achieved since the first in-pile experiments at Sandia, are described. Results are given for the total vapor pressure as a function of internal energy for ultra-pure UO/sub 2/. These baseline data are then compared to the total pressure from reactor-typical UO/sub 2/, containing known levels of impurities. Fianlly, total vapor pressure data for reactor typical mixed (U, Pu) oxide are presented. (No data are given in this paper).

Reil, K.O.; Breitung, W.

1982-01-01

158

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

SciTech Connect

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.

Suuberg, E.M.

1995-12-31

159

Influence of viscous fingering on dynamic saturation-pressure curves in porous media  

NASA Astrophysics Data System (ADS)

We study drainage-imbibition experiments on quasi-two-dimensional porous models. The models are transparent, allowing the displacement process and structure to be monitored in space and time. Results obtained in the case of quasi-static drainage cycles are compared to standard water retention experiments. We show that the so-called dynamic effects referred in the literature of experimentally measured capillary pressure curves might be explained by the combined effect of capillary pressure along the invasion front of the gaseous phase and pressure changes caused by viscous effects. A detailed study of the structure optically followed shows that the geometry of the invader is self-similar with two different behaviors at small and large scales: the structure corresponds to the ones of invasion percolation models at small scales (capillary fingering structures with fractal dimension D=1.83), whereas at large scales, viscous pressure drops dominate over the capillary threshold variations, and the structures are self-similar fingering structures with a fractal dimension corresponding to Dielectric Breakdown Models (variants of the DLA model), with D??1.5. The cross-over scale is set by the scale at which capillary fluctuations are of the order of the viscous pressure drops. This leads physically to the fact that cross-over scale between the two fingering dimensions, goes like the inverse of the capillary number. This study utilizes these geometrical characteristics of the viscous fingers forming in dynamic drainage, to obtain a meaningfull scaling law for the saturation-pressure curve at finite speed, i.e. the so-called dynamic capillary pressure relations. We thus show how the micromechanical interplay between viscous and capillary forces leads to some pattern formation, which results in a general form of dynamic capillary pressure relations. By combining these detailed informations on the displacement structure with global measures of pressure, saturation and controlling the capillary number Ca, a scaling relation relating pressure, saturation, system size and capillary number is developed. By applying this scaling relation, pressure-saturation curves for a wide range of capillary numbers can be collapsed.

Lvoll, G.; Toussaint, R.; Mly, K. J.; Schaefer, G.; Schmittbuhl, J.; Jankov, M.; Mheust, Y.

2009-04-01

160

Oxygen saturation changes in the optic nerve head during acute intraocular pressure elevation in monkeys  

NASA Astrophysics Data System (ADS)

Background and Objective: To evaluate the effect of an acute elevated intraocular pressure (IOP) on oxygen saturation of structures of the optic nerve head. Study Design/Materials and Methods: In the cynomolgus monkey eye, IOP was set to 10 mm Hg, and then raised to 30, 45, and 55 mm Hg. The ONH and overlying vessels were imaged using a fundus camera attached to a hyperspectral imaging system (HSI) at 10 and 30 minutes after IOP elevation. Results: Raising IOP from 10 to 30 mm Hg did not significantly (P < 0.0001) change saturation in vessels or ONH tissue structures but at 55 mm Hg, all structures showed significant reduction. Conclusions: Quantitative assay of the blood oxygen saturation in structures on the surface and overlying the optic nerve head is possible using hyperspectral imaging techniques.

Khoobehi, Bahram; Kawano, Hiroyuki; Ning, Jinfeng; Burgoyne, Claude F.; Rice, David A.; Khan, Fareeha; Thompson, Hilary W.; Beach, James M.

2009-02-01

161

Pluto's atmosphere - Models based on refraction, inversion, and vapor-pressure equilibrium  

NASA Technical Reports Server (NTRS)

Viking spacecraft radio-occultation measurements indicate that, irrespective of substantial differences, the polar ice cap regions on Mars have inversions similar to those of Pluto, and may also share vapor pressure equilibrium characteristics at the surface. This temperature-inversion phenomenon occurs in a near-surface boundary layer; surface pressure-temperature may correspond to the vapor-pressure equilibrium with CH4 ice, or the temperature may be slightly higher to match the value derived from IRAS data.

Eshleman, Von R.

1989-01-01

162

H2SO4 vapor pressure of sulfuric acid and ammonium sulfate solutions  

Microsoft Academic Search

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

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

1997-01-01

163

Deep Level in InP Crystal Grown by the Horizontal Bridgman Method under Controlled Phosphorus Vapor Pressure  

Microsoft Academic Search

InP crystals were grown by the horizontal Bridgman (HB) method under a controlled ambient phosphorus vapor pressure. The relationship between the phosphorus vapor pressure and crystal defects was investigated. Crystals grown under a lower phosphorus vapor pressure have an In-rich composition. P-vacancy related photoluminescence (PL) emission at 1.1 eV decreased in growth under a higher phosphorus vapor pressure. The ion

Atsushi Shimizu; Jun-ichi Nishizawa; Yutaka Oyama; Ken Suto

2000-01-01

164

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

NASA Technical Reports Server (NTRS)

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.

Jacobsen, Richard T.; Stewart, Richard B.

1973-01-01

165

Detection and measurement of sulfur mustard offgassing from the weanling pig following exposure to saturated sulfur mustard vapor.  

PubMed

Animal models are employed to investigate mechanisms of injury and to evaluate protective measures against sulfur mustard (HD) exposure. The ability to detect and quantify HD enables the researcher to follow safe procedures in handling skin samples. We designed an experimental procedure to measure HD offgassing from animal models. A Minicams--a portable gas chromatograph equipped with a flame photometric detector and on-line 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 off-line and then transferred the sample by means of an ACEM 900 to a gas chromatograph equipped with either a flame photometric detector or a mass spectrometer. Sulfur mustard offgassing data are presented from three experiments in which weanling pigs were exposed to saturated HD vapor via vapor caps containing 10 microl of HD. The HD concentration was measured in time-weighted-average (TWA) units at a specific HD application site. The current 8-h maximum exposure limit for HD is 3-ng l(-1), (1 TWA unit). The largest TWA value measured near a 3 h time point was a Minicams measurement of 0.48 TWA at 2 h and 53 min after removal of a vapor cap containing HD from a single exposure site on an animal that had 24 concurrent dorsal exposure sites. Gas chromatography/flame photometric detection and gas chromatography/mass spectrometry were used to confirm the Minicams data and to provide greater sensitivity and selectivity down to 0.1 TWA. The gas chromatography/mass spectrometry data confirmed that HD concentrations fell below 0.1 TWA in <5 h for a specific site. These measurements of HD concentrations provided information on the expeditious and safe handling of HD-exposed tissue. PMID:11428637

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

2000-12-01

166

Vaporizing Vapor  

NSDL National Science Digital Library

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.

167

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

Microsoft Academic Search

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

Julia Brockway; William W. Hay

1998-01-01

168

Scaling procedures for capillary pressure data at low wetting-phase saturations  

Microsoft Academic Search

In this paper capillary pressure data, applicable to the saturation range below 5% are reported. The method used to obtain these data involved the determination of low-temperature nitrogen adsorption\\/desorption isotherms. Three types of samples were studied: Berea sandstone, a producing-reservoir sandstone, and microporous chert extracted from the producing-reservoir sandstone. The data for Berea sandstone, when scaled according toe the usual

Melrose

1991-01-01

169

Atomic-layer adsorption of P on Si(100) and Ge(100) by PH 3 using an ultraclean low-pressure chemical vapor deposition  

Microsoft Academic Search

Atomic-layer adsorption of P on Si(100) and Ge(100) at 200750C by PH3 was investigated using an ultraclean low-pressure chemical vapor deposition (CVD) system. At 300C, the PH3 adsorption was suppressed on the H-terminated Si surface, but PH3 was adsorbed dissociatively on the H-free Si surface with saturation tendency to subatomic layer. At 450750C, the P atom concentration on the Si

Yosuke Shimamune; Masao Sakuraba; Takashi Matsuura; Junichi Murota

2000-01-01

170

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

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.

Alexander Apelblat; Eli Korin

1998-01-01

171

Elasticity of water-saturated rocks as a function of temperature and pressure.  

NASA Technical Reports Server (NTRS)

Compressional and shear wave velocities of water-saturated rocks were measured as a function of both pressure and temperature near the melting point of ice to confining pressure of 2 kb. The pore pressure was kept at about 1 bar before the water froze. The presence of a liquid phase (rather than ice) in microcracks of about 0.3% porosity affected the compressional wave velocity by about 5% and the shear wave velocity by about 10%. The calculated effective bulk modulus of the rocks changes rapidly over a narrow range of temperature near the melting point of ice, but the effective shear modulus changes gradually over a wider range of temperature. This phenomenon, termed elastic anomaly, is attributed to the existence of liquid on the boundary between rock and ice due to local stresses and anomalous melting of ice under pressure.

Takeuchi, S.; Simmons, G.

1973-01-01

172

Accurate determination of the vapor pressure of potassium using optical absorption  

NASA Technical Reports Server (NTRS)

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.

Shirinzadeh, B.; Wang, C. C.

1983-01-01

173

Vapor Pressures of Zinc Chloride and Zinc Bromide and Their Gaseous Dimerization  

Microsoft Academic Search

The absolute vapor pressures of zinc chloride and zinc bromide have been measured by a quasistatic method. In addition, transpiration experiments have been made to determine the vapor density of the gas. Mass spectrometric observations of the gas over the liquid salts have indicated that the gas consists mainly of zinc halide monomer with some dimer also present. The individual

F. J. Keneshea; Daniel Cubicciotti

1964-01-01

174

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

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

175

The Oxidation Rate of SiC in High Pressure Water Vapor Environments  

NASA Technical Reports Server (NTRS)

CVD SiC and sintered alpha-SiC samples were exposed at 1316 C in a high pressure burner rig at total pressures of 5.7, 15, and 25 atm for times up to 100h. Variations in sample emittance for the first nine hours of exposure were used to determine the thickness of the silica scale as a function of time. After accounting for volatility of silica in water vapor, the parabolic rate constants for Sic in water vapor pressures of 0.7, 1.8 and 3.1 atm were determined. The dependence of the parabolic rate constant on the water vapor pressure yielded a power law exponent of one. Silica growth on Sic is therefore limited by transport of molecular water vapor through the silica scale.

Opila, Elizabeth J.; Robinson, R. Craig

1999-01-01

176

Scaling procedures for capillary pressure data at low wetting-phase saturations  

SciTech Connect

In this paper capillary pressure data, applicable to the saturation range below 5% are reported. The method used to obtain these data involved the determination of low-temperature nitrogen adsorption/desorption isotherms. Three types of samples were studied: Berea sandstone, a producing-reservoir sandstone, and microporous chert extracted from the producing-reservoir sandstone. The data for Berea sandstone, when scaled according toe the usual Leverett J-function procedure, did not agree with previously reported data for the air/brine system. Because saturation resulting from wetting films is not expected to scale according to the J-function procedure, one cause of the disagreement could be a significant contribution of wetting films to the total saturation in the low-saturation region. Other contributing causes appear to be a 20% difference in surface area between the two sample sets used in the scaling test and a difference in the clay mineral fabric (pore structure) established under two different test conditions.

Melrose, J.C. (Stanford Univ., CA (United States))

1991-06-01

177

The emission characteristics of low-pressure water vapor discharge UV emitters  

Microsoft Academic Search

We have studied the characteristics of UV emission sources operating on low-pressure normal (H2O) and heavy (D2O) water vapor excited by periodic-pulsed and glow discharges. The emission in a 300330 nm wavelength interval has been studied\\u000a in detail for water vapor pressures ranging from 50 to 2500 Pa. A comparison of the characteristics of emission from discharge\\u000a plasma at low

A. K. Shuaibov; A. A. General; V. A. Kelman; I. V. Shevera

2008-01-01

178

The emission characteristics of low-pressure water vapor discharge UV emitters  

Microsoft Academic Search

We have studied the characteristics of UV emission sources operating on low-pressure normal (H2O) and heavy (D2O) water vapor excited by periodic-pulsed and glow discharges. The emission in a 300 330 nm wavelength interval has been studied in detail for water vapor pressures ranging from 50 to 2500 Pa. A comparison of the characteristics of emission from discharge plasma at

A. K. Shuaibov; A. A. General; V. A. Kel'Man; I. V. Shevera

2008-01-01

179

Modeling of Moisture Diffusion and Whole-Field Vapor Pressure in Plastic Packages of IC Devices  

Microsoft Academic Search

\\u000a Moisture diffusion and vapor pressure development analyses are the key to understand the moisture-induced failure mechanisms\\u000a in electronic packages. In this chapter, theories and applications of moisture diffusion modeling and vapor pressure analysis\\u000a are reviewed. The unique characteristics of moisture diffusion in multi-material system are described. The commonly used normalization\\u000a methods to remove interfacial discontinuity are presented, and the details

X. J. Fan; T. Y. Tee; X. Q. Shi; B. Xie

180

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

Microsoft Academic Search

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 333.15K at 10K intervals and the composition range from 0 to 90 mass % polyalkylene glycol. It was found that below 273.15K, the effect of the polyalkylene glycol on the vapor pressure was negligible up to 30 mass% polyalkylene

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

2004-01-01

181

Vapor pressures and enthalpies of sublimation of D-glucose, D-xylose, cellobiose, and levoglucosan  

Microsoft Academic Search

The vapor pressures of α-D-glucose (or dextrose), D-xylose, D-cellobiose (or 4-β-D-glucopyranosyl-D-glucopyranose), and levoglucosan (or 1,6-anhydro-β-D-glucopyranose) have been measured using the Knudsen effusion technique, in the range of temperatures from 344 to 488 K. The measurements were all made in the solid sublimation regime, and enthalpies of sublimation were calculated from the Clausius-Claperon equation. The vapor pressures may be correlated by

V. Oja; E. M. Suuberg

1999-01-01

182

InP single crystal growth by the horizontal Bridgman method under controlled phosphorus vapor pressure  

Microsoft Academic Search

InP single crystals were grown by the horizontal Bridgman method under controlled ambient phosphorus vapor pressure. The relationship between melt composition and crystal defects was investigated. The InP grown under phosphorus vapor pressure of 25 atm has EPD levels of 103cm?2 through the ingot. In the InP grown at 12 or 29 atm, the EPD increased more than 2 orders

Atsushi Shimizu; Jun-ichi Nishizawa; Yutaka Oyama; Ken Suto

2001-01-01

183

Liquid-propellant droplet vaporization and combustion in high pressure environments  

NASA Technical Reports Server (NTRS)

In order to correct the deficiencies of existing models for high-pressure droplet vaporization and combustion, a fundamental investigation into this matter is essential. The objective of this research are: (1) to acquire basic understanding of physical and chemical mechanisms involved in the vaporization and combustion of isolated liquid-propellant droplets in both stagnant and forced-convective environments; (2) to establish droplet vaporization and combustion correlations for the study of liquid-propellant spray combustion and two-phase flowfields in rocket motors; and (3) to investigate the dynamic responses of multicomponent droplet vaporization and combustion to ambient flow oscillations.

Yang, Vigor

1991-01-01

184

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

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

185

Pressure-Saturation Curves and the Critical Volume Fraction for Percolation: Accessibility Function of Percolation Theory  

NASA Astrophysics Data System (ADS)

The pressure-saturation curves of porous media give fundamental information about the pore space. In equilibrium, ignoring effects due to hysteresis and pore accessibility, it should be possible to extract a pore-size distribution from h(?) data, as described in Chap. 3. However, a number of percolation effects complicate the analysis and make such a simple inference impossible. The pressure-saturation relation is affected by both the lack of continuity of the air phase near saturation and by a similar lack of continuity of the water phase near the dry end. Given that these effects are due to phase transitions (in the percolation sense), small changes in experimental conditions can produce major (and sometimes puzzling) changes in the results. Further, since the correlation length diverges near these transitions, numerical simulations under both wet and dry conditions are amenable to finite-size scaling analysis. Since the critical volume fractions for percolation of air and water are critical to the discussion, experimental evidence regarding these values is presented toward the end of this chapter.

Hunt, Allen; Ewing, Robert

186

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

USGS Publications Warehouse

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.

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

1990-01-01

187

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

NASA Technical Reports Server (NTRS)

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.

Wendlandt, R. F.

1982-01-01

188

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

PubMed

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. PMID:22060520

Garra, Roberto

2011-09-01

189

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

NASA Astrophysics Data System (ADS)

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.

Garra, Roberto

2011-09-01

190

A Modification of ? in SRK Equation of State and Vapor-Liquid Equilibria Prediction  

Microsoft Academic Search

Based on results of saturated vapor pressures of pure substances calculated by SRK equation of state, the factor ? in attractive pressure term was modified. Vapor-liquid equilibria of mixtures were calculated by original and modified SRK equation of state combined with MHV1 mixing rule and UNIFAC model, respectively. For 1447 saturated pressure points of 37 substance including alkanes; organics containing

LUO Mingjian; MA Peisheng; XIA Shuqian

2007-01-01

191

Vapor pressure prediction for alkenoic and aromatic organic compounds by a UNIFAC-based group contribution method  

NASA Astrophysics Data System (ADS)

A UNIFAC-based group contribution method is developed for predicting liquid vapor pressure (pLo) values of organic compounds, including molecules containing C dbnd C bonds. The method is an extension of UNIFAC- pLo.1 as developed by Asher et al. [2002. Estimating the vapor pressures of multi-functional oxygen-containing organic compounds using group contribution methods, Atmospheric Environment 36, 1483-1498] in which C dbnd O is the only type of sp 2-bonded carbon considered. The current work is important due to the widespread interest in the physical behavior of organic compounds with sp 2 carbon-carbon bonds, e.g., alkenes and aromatics. In the context of particulate matter (PM) formation in the atmosphere, condensable molecules of interest that contain sp 2 bonds include initial oxidation products such as 4-oxo-but-2-enoic acid and 2,6-dihydroxybenzoic acid. UNIFAC- pLo.2 as developed here was based on experimentally determined, temperature-dependent pLo data for 39 alkene compounds, 26 aromatic compounds, and 81 saturated compounds. In order to check the method, an independent set of 22 alkene and 40 aromatic compounds with known volatilities was assembled. Vapor pressures for these compounds were estimated using UNIFAC- pLo.2 and the results compared to known values. The UNIFAC- pLo.2 method was found to predict vapor pressure within a factor of 1.8 and this accuracy was equal across the volatility range of the basis set (310 -10 - 310 -1 atm). The SPARC method [Hilal, S.H., Carreira, L.A., Karickhoff, S.W., 1994. Estimation of chemical reactivity parameters and physical properties of organic molecules using SPARC. In: Murray, P.P.A.J.S. (Ed.), Quantitative Treatments of Solute/Solvent Interactions. Elsevier, Amsterdam] was also used to estimate pLo for the 22 alkene and 40 aromatic compounds in the test set. Comparing the results of SPARC with UNIFAC- pLo.2 shows that the UNIFAC- pLo.2 method was on average 50% more accurate than the SPARC. The combined basis and test sets totaled 81 saturated, 61 alkene, and 66 aromatic compounds which were then used to generate an overall set of UNIFAC- pLo.2 method coefficients.

Asher, William E.; Pankow, James F.

192

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

SciTech Connect

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.

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

2009-07-01

193

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,...

194

Gas chromatographic vapor pressure determination of atmospherically relevant oxidation products of ?-caryophyllene and ?-pinene  

NASA Astrophysics Data System (ADS)

Vapor pressures (subcooled liquid, pliquid) of atmospherically relevant oxidation products of ?-caryophyllene (?-caryophyllene aldehyde 0.18 0.03 Pa and ?-nocaryophyllene aldehyde 0.17 0.03 Pa), and ?-pinene (pinonaldehyde 16.8 0.20 Pa, cis-pinic acid 0.12 0.06 Pa, and cis-pinonic acid 0.99 0.19 Pa) at 298 K were obtained by gas chromatography with flame ionization detection (FID) and mass spectrometric (MS) detection. The effects of stationary phase polarity and column film thickness on the vapor pressure values were investigated. Increase in stationary phase polarity provided smaller values, while increase in film thickness gave slightly higher values. Values for vapor pressure were at least two orders of magnitude lower when obtained by a method utilizing vaporization enthalpy (determined by gas chromatography-mass spectrometry) than by retention index method. Finally, the results were compared with values calculated by group contribution theory. For the ?-caryophyllene oxidation products, the values measured by gas chromatography were slightly lower than those obtained by theoretical calculations. The opposite trend was observed for the ?-pinene oxidation products. The methods based on gas chromatography are concluded to be highly useful for the determination of vapor pressures of semi-volatile compounds. Except for the most polar pinic and pinonic acids, differences between vapor pressure values obtained by GC-FID and GC-MS were small. Since GC-MS provides structural information simultaneously, the use of GC-MS is recommended.

Hartonen, Kari; Parshintsev, Jevgeni; Vilja, Vesa-Pekka; Tiala, Heidi; Knuuti, Sinivuokko; Lai, Ching Kwan; Riekkola, Marja-Liisa

2013-12-01

195

Capillary Pressure-Saturation Curves of Glass Bead Systems: Experimental Data and Lattice Boltzmann Simulations  

NASA Astrophysics Data System (ADS)

Recent progress in observational and computational techniques has invigorated studies of of fluid dynamics and interfacial geometry in porous media. Computational advances largely concern Lattice Boltzmann (LB) method that has been shown to be useful in simulating microscale flow in porous media. With some phenomenological or thermodynamic extensions, the LB method is also able to deal with microscale interfacial phenomena in single or multiphase systems. The goal of this presentation is to provide insight into what is needed to make a link between 3D experimental observations of interfacial geometry and LB simulations. The experimental data consist of computed tomography observations of several air-water displacements inside a glass bead system with a resolution of 17 microns. Also available are capillary pressure-saturation curves between 0 and 1kPa. The LB model is that of Shan-Chen as modified by Martys and Chen (1996). We present a comprehensive approach for calibrating surface tension and contact angle and to define space, pressure and time scaling. The analyses are partly performed on idealized systems and finally applied to large scale (107 voxels) simulations of the real physical systems. We demonstrate that there is a close agreement between that observed and measured pressure-saturation curves.

Schaap, M. G.; Porter, M. L.; Christensen, B. S.; Wildenschild, D.

2006-12-01

196

Parameter estimation of two-fluid capillary pressure-saturation and permeability functions  

NASA Astrophysics Data System (ADS)

Accurate characterization and modeling of subsurface flow in multi-fluid soil systems require development of a rapid, reproducible experimental method that yields the information necessary to determine the parameters of the capillary pressure-saturation and permeability functions. Previous work has demonstrated that parameter optimization using inverse modeling is a powerful approach to indirectly determine these constitutive relationships for air-water systems. We consider extension of the inverse parameter estimation method to the modified multi-step outflow method for two-fluid (air-water, air-oil and oil-water) flow systems. The wellposedness of the proposed parameter estimation problem is evaluated by its accuracy, uniqueness and parameter uncertainty. Seven different parametric models for the capillary pressure-saturation and permeability functions were tested in their ability to fit the multi-step outflow experimental data; these included the van Genuchten-Mualem (VGM) model, van Genuchten-Burdine (VGB), Brooks-Corey-Mualem (BCM), Brooks-Corey-Burdine (BCB), Brutsaert-Burdine (BRB), Gardner-Mualem (GDM) and Lognormal Distribution-Mualem (LNM) models. The VGB, BCM and BCB models fitted the multi-step outflow data poorly, and resulted in relatively large values for the root-mean-squared residuals. It was concluded that the remaining VGM, LNM, BRB and GDM models successfully characterized the multi-step experimental data for two-fluid flow systems. Although having one parameter less than the other models, the GDM model's performance was excellent. Finally, we conclude that optimized capillary pressure-saturation functions for the oil-water and air-oil could be predicted from the respective air-water function using interfacial tension ratios.

Chen, J.; Hopmans, J. W.; Grismer, M. E.

197

Establishing a quantitative functional relationship between capillary pressure, saturation and interfacial area. 1997 annual progress report  

SciTech Connect

'There is a fundamental knowledge gap associated with the in situ remediation of non-aqueous phase pollutants. Currently it is not possible to accurately determine the interfacial surface area of non-aqueous contaminants. As a result it is impossible to (1) accurately establish the health and environmental risk associated with the pollution: (2) precisely quantify and evaluate the potential efficacy of various in situ treatment technologies; and (3) conduct reliable performance assessments of the applied remediation technology during and after the clean-up. The global goal of this investigation is to try to remedy these shortcomings through the development of a formalized functional relationship between interfacial area (a), phase saturation (S) and capillary pressure (P). The development of this relationship will allow the direct determination of the fluid-fluid interfacial area from field measurements. Quantitative knowledge of the surface area of the non-aqueous phase pollutant facilitates accurate predictions of both the rate of dissolution and the contact area available for treatment. In addition. if saturation and capillary pressure measurements are made during the remediation process. both the spatial and temporal effectiveness of the remediation technology can be quantified. This information can then be used to optimize the restoration program. The project objective will be achieved through an integrated and focused research program that is comprised of theoretical computational and experimental efforts. These efforts are organized into a framework of four tasks: (1) improve on newly developed laboratory techniques to quantify and directly measure the functional relationship between phase interfacial area (a), saturation (S) and capillary pressure (P). (2) Develop new computational algorithms in conjunction with laboratory measurements to predict P, S and a. (3) Test existing theory and develop new theory to describe the relationship between P, S and a at the large scale. (4) Synthesize 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 P, S and a.'

Montemagno, C.D.

1997-01-01

198

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

SciTech Connect

'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.'

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

199

Determining the saturation vapour pressures of keto-dicarboxylic acids in aqueous solutions  

NASA Astrophysics Data System (ADS)

A two-compartment binary mass transport model with group contribution methods parametrizations for the physical properties of the organic acids (UNIFAC Dortmund method for activity coefficients, GCVOL-OL-60 method for the pure liquid acid density, GC-MG method for the pure acid surface tension at room temperature, Fuller et al. method for the diffusion coefficients) was used to interpret the evaporation experiments of 100 nm sized ketodicarboxylic acid aqueous solutions droplets at ambient temperature. The determined values for the saturation vapour pressure of liquid 2-keto-glutaric acid are in the order of 10-5 Pa.

Crljenica, Ivica; Yli-Juuti, Taina; Zardini, Alessandro A.; Julin, Jan; Bilde, Merete; Riipinen, Ilona

2013-05-01

200

Lack of an effect of dietary saturated fat and cholesterol on blood pressure in normotensives.  

PubMed

The effect on blood pressure (BP) levels of modifying the saturated fat and cholesterol content in the diet was studied in two separate protocols in normotensive volunteers. For 3 months, 19 men and women, aged 14 to 54 years, adhered to a diet that eliminated meat, poultry, eggs, and dairy fat from the subjects' customary nonvegetarian diet, which had included 71 g/day (35%) of dietary fat. The experimental diet reduced the consumption of saturated fat from 21 to 10 g, dietary cholesterol was lowered from 398 to 69 mg per day, but consumption of polyunsaturated fatty acids, carbohydrates, and dietary fiber was unchanged. Body weight and urinary sodium and potassium excretion were not significantly altered. Mean BP before and after the low fat diet was 116/74 and 115/74 mm Hg, respectively. A second double-blind study tested the effect on BP of dietary cholesterol at levels of 155 and 471 mg/day. Seventeen semivegetarian college students consumed one egg per day concealed in desserts for 3 weeks, and identical desserts containing no eggs for an additional 3 weeks. Mean BP at the end of the egg and eggless periods was 108/69 and 107/69 mm Hg, respectively. Thus, in short-term nutritional studies, dietary saturated fat and cholesterol at low-to-moderate levels of intake have no significant effects on BP in normotensive adults. PMID:6724660

Sacks, F M; Marais, G E; Handysides, G; Salazar, J; Miller, L; Foster, J M; Rosner, B; Kass, E H

1984-01-01

201

Atmospheric Pressure Plasma Enhanced Chemical Vapor Deposition of Borophosphosilicate Glass Films  

Microsoft Academic Search

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),

Minghui Yin; Lingli Zhao; Xiangyu Xu; Shouguo Wang

2008-01-01

202

Assessment of the Accuracy of Pharmacy Students' Compounded Solutions Using Vapor Pressure Osmometry  

PubMed Central

Objective. To assess the effectiveness of using a vapor pressure osmometer to measure the accuracy of pharmacy students compounding skills. Design. Students calculated the theoretical osmotic pressure (mmol/kg) of a solution as a pre-laboratory exercise, compared their calculations with actual values, and then attempted to determine the cause of any errors found. Assessment. After the introduction of the vapor pressure osmometer, the first-time pass rate for solution compounding has varied from 85% to 100%. Approximately 85% of students surveyed reported that the instrument was valuable as a teaching tool because it objectively assessed their work and provided immediate formative assessment. Conclusions. This simple technique of measuring compounding accuracy using a vapor pressure osmometer allowed students to see the importance of quality control and assessment in practice for both pharmacists and technicians.

McPherson, Timothy B.

2013-01-01

203

Vapor Pressure and Mean Adsorption Time of Pyromellitic Dianhydride and 4,4?-Oxidianiline  

NASA Astrophysics Data System (ADS)

Thermogravimetry (TG) measurements taken at pressures ranging from 10-1 to 10-3 Pa are used to calculate the vapor pressure of pyromellitic dianhydride (PMDA) and 4,4?-oxidianiline (ODA). The vapor pressure calculated for PMDA is closely agrees with to those reported by Pethe et al.., Elshazly and Salem. For ODA, the calculated vapor pressure fits exactly on the curve obtained by Salem. The enthalpy is also calculated. The activation energy of desorption is found to be nearly equal to the enthalpy. The adsorption and desorption rates for both PMDA and ODA at various substrate temperatures are also observed. The mean adsorption time, ? calculated for ODA is several orders of magnitude larger than that for PMDA. 1:1 doses of ODA and PMDA therefore produce imine bonds which lead to the formation of thermally unstable films.

Dutt, Radhika; Takahashi, Yoshikazu; Iijima, Masayuki

1999-06-01

204

Pulmonary atresia with ventricular septal defect: a case for central venous pressure and oxygen saturation monitoring.  

PubMed

A 21-year-old patient with pulmonary atresia and ventricular septal defect (PA-VSD) was admitted to the hospital for tubal ligation. Invasive arterial and central venous (CVP) pressure, pulse oximetric oxygen saturation (SpO2), and (from the tip of oximetric central venous catheter) central venous oxygen saturation (ScvO2) and oxygen extraction rate (ExO2) were continuously monitored. Heart rate (range: 68-75 beat/min), mean arterial pressure (80-90 mmHg), CVP (7-10 mmHg), SpO2 (79-90 percent), ScvO2 (57-70 percent), and ExO2 (21-30 percent) remained stable during epidural anesthesia and transvaginal sterilization. Following an overnight stay (peak SpO2 92 percent; peak ScvO2 71 percent; through ExO2 21 percent), the oxygen data returned to baseline on awakening (SpO2 < 80 percent, ScvO2 < 55 percent, ExO2 > 35 percent), and the patient was discharged. In PA-VSD, a single-outlet double-ventricle anomaly, CVP reflects the preload of systemic ventricle. As the mixed venous oxygen saturation cannot be defined, ScvO2 is the best available indicator of the whole body oxygen consumption. Continuous monitoring of CVP, ScvO2 and ExO2 in the superior vena cava may provide more insight into the response to anesthesia and surgery in patients with PA-VSD. PMID:9713951

Weiss, B M; Atanassoff, P G; Jenni, R; Walder, B; Wight, E

1998-01-01

205

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

Microsoft Academic Search

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

K. Pruess; T. N. Narasimhan

1982-01-01

206

Vapor pressures of substituted polycarboxylic acids are much lower than previously reported  

NASA Astrophysics Data System (ADS)

The partitioning of compounds between the aerosol and gas phase is a primary focus in the study of the formation and fate of secondary organic aerosol. We present measurements of the vapor pressure of 2-Methylmalonic (isosuccinic) acid, 2-Hydroxymalonic (tartronic) acid, 2-Methylglutaric acid, 3-Hydroxy-3-carboxy-glutaric (citric) acid and 2,3-Dihydroxysuccinic (tartaric) acid which were obtained from the evaporation rate of supersaturated liquid particles levitated in an electrodynamic balance. Our measurements indicate that the pure component liquid vapor pressures at 298.15 K for tartronic, citric and tartaric acids are much lower than the same quantity which was derived from solid state measurements in the only other room temperature measurement of these materials (made by Booth et al., 2010). This strongly suggests that empirical correction terms in vapor pressure estimation models to account for the inexplicably high vapor pressures of these and similar compounds should be revisited, and that due caution should be used when the estimated vapor pressures of these and similar compounds are used as inputs for other studies.

Huisman, A. J.; Krieger, U. K.; Zuend, A.; Marcolli, C.; Peter, T.

2013-01-01

207

Vapor pressures of substituted polycarboxylic acids are much lower than previously reported  

NASA Astrophysics Data System (ADS)

The partitioning of compounds between the aerosol and gas phase is a primary focus in the study of the formation and fate of secondary organic aerosol. We present measurements of the vapor pressure of 2-methylmalonic (isosuccinic) acid, 2-hydroxymalonic (tartronic) acid, 2-methylglutaric acid, 3-hydroxy-3-carboxy-glutaric (citric) acid and DL-2,3-dihydroxysuccinic (DL-tartaric) acid, which were obtained from the evaporation rate of supersaturated liquid particles levitated in an electrodynamic balance. Our measurements indicate that the pure component liquid vapor pressures at 298.15 K for tartronic, citric and tartaric acids are much lower than the same quantity that was derived from solid state measurements in the only other room temperature measurement of these materials (made by Booth et al., 2010). This strongly suggests that empirical correction terms in a recent vapor pressure estimation model to account for the inexplicably high vapor pressures of these and similar compounds should be revisited, and that due caution should be used when the estimated vapor pressures of these and similar compounds are used as inputs for other studies.

Huisman, A. J.; Krieger, U. K.; Zuend, A.; Marcolli, C.; Peter, T.

2013-07-01

208

Effect of Water Vapor Pressure on the Thermal Decomposition of 2-Chloroethylphosphonic Acid 1  

PubMed Central

Decomposition of 2-chloroethylphosphonic acid (Ethephon) was studied in dried films at various water vapor pressures (0.6 to 86.9 millimeters Hg, 3.2 to 93.9% relative humidity) and temperatures (20, 30, 40, and 50 C) at pH 6.3 and 7.0. The rate of decomposition could be determined equally well by [14C]Ethephon or ethylene measurements. The rate increases at increasing water vapor pressures at a constant temperature and pH, up to an optimum. The optimum vapor pressure for decomposition approximately doubles for each 10 C increase. The activation energy for the decomposition reaction in water vapor pressures of 3.2 to 12 millimeters Hg is 8.7 and 14.3 kilocalories per mole at pH 6.3 and 7.0, respectively. Decomposition of Ethephon is inhibited above an optimum vapor pressure. The inhibition is stronger at lower temperatures and at pH 6.3 than at pH 7.0. The rate of decomposition and the inhibition observed at a low temperature (20 C) was found to be similar on various surfaces, including olive leaves. Failure to induce olive (Olea europaea L.) fruit abscission under certain environmental conditions can be readily attributed to rapid breakdown of Ethephon at elevated temperatures and low relative humidities.

Klein, Isaac; Lavee, Shimon; Ben-Tal, Yosel

1979-01-01

209

THE VAPOR PRESSURES OF BiCl OVER LIQUID Bi-BiCl SOLUTIONS  

Microsoft Academic Search

A study of the pressure of BiCl vapor in equilibrium with Bi--; BiCl liquid mixtures was made by the transpiration method. The study ; covered the range of temperature of 230 to 410 deg and of composition from pure ; BlCl to about 0.4 in Bi mole fraction. The vapor was found to be ; essentially BiCl over the entire

D. Cubicciotti; F. J. Keneshea; C. M. Kelley

1958-01-01

210

Modeling atomization processes in high-pressure vaporizing sprays  

NASA Astrophysics Data System (ADS)

The theoretical basis and numerical implementation of KIVA, a multidimensional computer code for the simulation of atomization and vaporization processes in the injection of a liquid through a round hole into a compressed gas, are described. KIVA is based on the blob-injection model of Reitz and Diwakar (1987), taking into account the effects of liquid inertia, surface tension, and the aerodynamic forces on the jet, as well as drop collision and coalescence and the effect of drops on turbulence in the gas. The predictions of KIVA for different injection regimes are compared with published experimental data in extensive graphs, and good agreement is demonstrated.

Reitz, Rolf D.

211

Influence of temperature gradients on partial pressures in a low-pressure chemical-vapor-deposition reactor  

NASA Astrophysics Data System (ADS)

Measurements and calculations of the influence of temperature gradients on the partial pressures of the gas species in a cold-wall chemical-vapor-deposition reactor are presented. The experiments were performed at low pressures (300-500 Pa total pressure) and gas mixtures consisting of hydrogen, nitrogen, and tetrafluoromethane. The partial pressures were determined by Raman spectroscopy. The Soret effect (or thermal diffusion) has a large influence on the partial pressures of heavy gases in the vicinity of the heated wafer. In some cases a decrease in partial pressure of 20% compared to the inlet partial pressures was observed. Numerical calculations were performed to predict the behavior of the gas mixture. For mixtures under investigation the gas temperatures as well as the changes in partial pressures due to the Soret effect were predicted correctly.

Oosterlaken, T. G. M.; Leusink, G. J.; Janssen, G. C. A. M.; Radelaar, S.; Kuijlaars, K. J.; Kleijn, C. R.; van den Akker, H. E. A.

1994-09-01

212

Vapor pressure of n-alkanes revisited; New high-precision vapor pressure data on n-decane, n-eicosane, and n-octacosane  

SciTech Connect

The authors report new vapor pressure measurements on n-decane (268-490{Kappa}), n-eicosane (388-626{Kappa}), and n-octacosane (453-575{Kappa}) made with a modified ebulliometer and an inclined piston gauge. Benzene and water were the standards in the ebulliometric measurements on n-decane and n-eicosane, while n-decane was the standard for the measurements on n-octacosane. The high-quality data for n-decane, which were confirmed by a third-law'' analysis, suggest that reported literature data are in error. Similar concerns are raised about reported n-eicosane data. The vapor pressure data were regressed with the Cox equation, using as reference the normal boiling point.

Chirico, R.D.; Nguyen, A.; Steele, W.V.; Strube, M.M. (IIT Research Institute, National Institute for Petroleum and Energy Research, PO Box 2128, Bartlesville, OK (US)); Tsonopoulos, C. (Exxon Research and Engineering Co., Florham Park, NJ (US))

1989-04-01

213

Pressure-coupled vaporization and combustion responses of liquid-fuel droplets in high-pressure environments  

NASA Technical Reports Server (NTRS)

The dynamic responses of liquid-fuel droplet vaporization and combustion to ambient pressure oscillations are examined. The analysis is based on the complete sets of conservation equations for both gas and liquid phases, and accommodates detailed treatments of finite-rate chemical kinetics and variable properties. With a full account of thermodynamic phase equilibrium at the droplet surface, the model enables a systematic examination of the effects of ambient flow conditions on the droplet behavior. The responses of hydrocarbon fuel droplets in both sub- and super-critical environments are investigated. Results indicate that the droplet gasification and burning mechanisms depend greatly on the ambient pressure. In particular, a rapid enlargement of the vaporization and combustion responses occurs when the droplet surface reaches its critical point, mainly due to the strong variations of latent heat of vaporization and thermophysical properties at the critical state.

Yang, Vigor; Shuen, J. S.; Hsiao, C. C.

1991-01-01

214

Se vapor pressure dependence of the phase diagram of the CuGa 1? x In x Se 2 system  

Microsoft Academic Search

Phase transition points of the CuGa1?xInxSe2 system are investigated by the differential thermal analysis with varying Se vapor pressure up to 760Torr. The phase diagrams constructed under controlled Se vapor pressure show that the solidus and liquidus points decrease more than 100C with increasing Se vapor pressure, and that the temperature zone of the (sphalerite+liquid) phase narrows in the region

Hiroaki Matsushita; Takeo Takizawa

1998-01-01

215

The emission characteristics of low-pressure water vapor discharge UV emitters  

NASA Astrophysics Data System (ADS)

We have studied the characteristics of UV emission sources operating on low-pressure normal (H2O) and heavy (D2O) water vapor excited by periodic-pulsed and glow discharges. The emission in a 300 330 nm wavelength interval has been studied in detail for water vapor pressures ranging from 50 to 2500 Pa. A comparison of the characteristics of emission from discharge plasma at low (50 150 Pa) and elevated (2.0 2.5 kPa) water vapor pressures reveals significant differences in the character of emission spectra, which can be related to the different types of emitting species (hydroxy radicals versus small clusters of such radicals and water molecules). Discharge current and emission intensity pulses in the periodic-pulsed discharge regime have been measured.

Shuaibov, A. K.; General, A. A.; Kel'Man, V. A.; Shevera, I. V.

2008-07-01

216

InP single crystal growth by the horizontal Bridgman method under controlled phosphorus vapor pressure  

NASA Astrophysics Data System (ADS)

InP single crystals were grown by the horizontal Bridgman method under controlled ambient phosphorus vapor pressure. The relationship between melt composition and crystal defects was investigated. The InP grown under phosphorus vapor pressure of 25 atm has EPD levels of 10 3 cm -2 through the ingot. In the InP grown at 12 or 29 atm, the EPD increased more than 2 orders at the tail end. X-ray reciprocal maps indicated that the crystals consisted of many domains with tilt boundaries at a distance from the seeding point. The deviation of the lattice parameter measured by the X-ray diffraction angle indicated that the composition changed gradually. The composition near the seeding point was nearly stoichiometry under the influence of the composition of source polycrystalline, because a finite time was required to transition of phosphorus. Optimum phosphorus vapor pressure is necessary to obtain InP with stoichiometric composition and low defect densities.

Shimizu, Atsushi; Nishizawa, Jun-ichi; Oyama, Yutaka; Suto, Ken

2001-07-01

217

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

SciTech Connect

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%.

Kuhne, W.

2012-12-03

218

Critical parameters and vapor pressure measurements for 1,1,1-trifluoroethane (R-143a)  

SciTech Connect

An apparatus to measure the critical pressure, density, and temperature by visual observation of the meniscus in an optical cell is presented. The critical parameters and vapor pressures for 1,1,1,2-tetrafluoroethane (R-134a) were measured to confirm the reliability of the measurements with the present apparatus. The critical pressure, density, and temperature of 1,1,1-trifluoroethane (R-143a) were determined to be 3.7639 MPa, 434 kg/m{sup 3}, and 345.861 K, respectively. Thirteen vapor pressures of R-143a were obtained at temperatures from 263 K to the critical temperature. The uncertainties of pressure, density, and temperature measurements are estimated to be within {+-} 2.6 kPa, {+-} 2 kg/m{sup 3}, and {+-} 6 mK, respectively.

Fujiwara, K.; Nakamura, S.; Noguchi, M. [Daikin Industries, Ltd., Settsu, Osaka (Japan). Chemical Div.] [Daikin Industries, Ltd., Settsu, Osaka (Japan). Chemical Div.

1998-01-01

219

Organic dye effects on dense nonaqueous phase liquids (DNAPL) entry pressure in water saturated porous media  

NASA Astrophysics Data System (ADS)

Visualization of DNAPL behavior in porous media is generally accomplished using three oil-soluble dyes: SudanIII, SudanIV, or Oil-Red-O. The dyes are generally assumed to not influence that behavior. That assumption was tested in the SudanIV-tetrachloroethene (PCE)-water-glass system. The dye significantly changes surface chemistry as a function of concentration and interface age. PCE mobility increases through lower adhesion tension. Increased mobility was demonstrated using entry pressure experiments for undyed and dyed PCE entering water-saturated glass bead media. Statistically significant entry pressure reduction occurred at a dye concentration of 0.0411 g/L, approximately two orders of magnitude lower than typically used. Dye type, concentration, and surface chemistry are therefore important experimental parameters which should be reported in multiphase flow studies. Dye use increases DNAPL surface chemical complexity, making them reasonable analogs for field DNAPLs. PCE entry pressure was strongly influenced by intrinsic permeability, providing experimental support for Bond number formulations which include permeability.

Tuck, David M.; Iversen, Gary M.; Pirkle, William A.

2003-08-01

220

Experimental Investigation of the Effect of Pressure and Fluid Saturation on Carbonate Rocks  

NASA Astrophysics Data System (ADS)

Gassmann's model is commonly used to predict how changes in pore fluids affect in-situ seismic velocities. Although Gassmann's model is generally successful in medium to high porosity sandstones, its appropriateness for quantifying fluid effects in carbonate rocks is questioned in literature. Questions rice from the model assumptions which, very likely oversimplify the complex rock-fluid interaction in carbonates. Critical issues include 1) rock-fluid chemical interaction (e.g. dissolution), violating Gassmann's purely mechanical model, and 2) substantial pore fabric heterogeneity, potentially violating Gassmann's assumption of good fluid mobility in a well-connected pore space. We present the preliminary results of measurements showing the variation of Vp and Vs as a function of pressure and fluid saturation. Theoretical velocities predicted by Gassmann's equation are also shown for comparison. Different saturating fluids, an inert gas (Helium) and degassed, distilled water are used to create experimental conditions that vary one fluid interaction at a time. The goal is to identify the conditions (i.e. fluid type, pressure, pore shape distribution) under which the assumptions of Gassman's theory may apply to carbonates and evaluate which conditions appear to be responsible for the failure of the seismic property prediction. Carbonate samples (porosity range from 5% to 50%) from Gravina di Puglia (Bari, Italy), and Monte Sant'Angelo and Peschici (Foggia, Italy) have been classified based on mineralogy, pore type and connectivity. From each sample, 2 core plugs have been extracted and used for measurements. Dissolution (i.e., changes to the rock framework) is expected to be different for different pore fluids. Hence, seismic fluid substitution in carbonates is likely more than a purely mechanical problem.

Scotellaro, C.; Vanorio, T.; Mavko, G.

2006-12-01

221

Deep Level in InP Crystal Grown by the Horizontal Bridgman Method under Controlled Phosphorus Vapor Pressure  

NASA Astrophysics Data System (ADS)

InP crystals were grown by the horizontal Bridgman (HB) method under a controlled ambient phosphorus vapor pressure. The relationship between the phosphorus vapor pressure and crystal defects was investigated. Crystals grown under a lower phosphorus vapor pressure have an In-rich composition. P-vacancy related photoluminescence (PL) emission at 1.1 eV decreased in growth under a higher phosphorus vapor pressure. The ion density at Ec-1.1 eV also decreased according to results of photocapacitance measurement. It was considered that crystals became a P-rich composition from an In-rich one by growth under higher phosphorus vapor pressure of 23 or 29 atm. This corresponds to the results of coulometric titration analysis. In the InP crystal grown under the phosphorus pressure of 33 atm, the density of the deep level was undetectable by PL or photocapacitance measurement.

Shimizu, Atsushi; Nishizawa, Jun-ichi; Oyama, Yutaka; Suto, Ken

2000-07-01

222

H2SO4 vapor pressure of sulfuric acid and ammonium sulfate solutions  

NASA Astrophysics Data System (ADS)

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 10-4 Pa, or 10-6 torr); 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 between 55 and 77 wt% H2SO4 (corresponding to about 5-25% relative humidity), ammonium sulfate solids at low humidities, and partially neutralized sulfate solutions with [NH4+]: [SO4=] ratios between 0.13 and 1.0. The vapor pressure data collected over sulfuric acid solutions generally agree with the predictions of Ayers, et al. [1980], although positive deviation was observed for the more dilute solutions. The good agreement between this measurement and previous efforts by absolute techniques suggests that the evaporative coefficient for the H2SO4-H2O system is near unity. H2SO4 vapor pressures over solid ammonium sulfate were measured between 27C and 60C; the data were fitted to In p = A/T + B, with A = -5928 and B = -3.77. The H2SO4 vapor pressures of mixed H2SO4-H2O-(NH4)2SO4 solutions dropped significantly as the [NH4+]:[SO4=] ratio exceeded 0.5. The results suggest that ammonia could very effectively stabilize molecular clusters of sulfuric acid and water in the atmosphere against evaporation, leading to rates of new particle formation higher than those predicted by binary H2SO4-H2O theory.

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

1997-02-01

223

Evaluation of the Hill-Siscoe transpolar potential saturation model during a solar wind dynamic pressure pulse  

NASA Astrophysics Data System (ADS)

Theory, observations, and simulations have shown that saturation of the cross-polar-cap potential occurs for high solar wind electric field. One of the parameters that affect the saturation process is the solar wind dynamic pressure. Theoretical arguments predict that higher pressure levels lead to higher transpolar potentials and a slower saturation process. The question arises of how the transpolar potential will respond to sudden enhancements of solar wind pressure in the saturation regime, and if the theoretical model predictions can replicate the observations. We use ionospheric flow data from Defense Meteorological Satellite Program (DMSP) spacecraft to calculate the transpolar potential and compare it with theory before and after a sudden increase in solar wind pressure. We find that the model predictions fall below the observed values for both pressure levels but are particularly lower after the dynamic pressure enhancement. The inclusion of a ``viscous'' potential, or the introduction of variable ionospheric conductivity, cannot remedy the discrepancy. We suggest that modification of the existing models to include magnetotail processes might be needed to bridge the gap between theory and observations.

Boudouridis, A.; Zesta, E.; Lyons, L. R.; Anderson, P. C.

2004-12-01

224

Feasibility of Sampling Vapors of Compounds with Low Volatility by Permeation  

Microsoft Academic Search

Lindane was used as the model of low vapor pressure compounds for the study of the feasibility of sampling vapors of such compounds by permeation. A constant source of lindane vapor, a dynamic exposure chamber, and a sampler for the chamber air were all based on the permeability of polyethylene (PE) to the vapor. Lindane-saturated air was contained in a

E. D. Palmes; Eugene R. Johnson

1999-01-01

225

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...

226

Robust temperature control in the measurement of high temperature vapor pressures  

Microsoft Academic Search

The problem of measuring the vapor pressure of high temperature materials likely to be used in a space environment is considered. The purpose of this experiment is to determine whether these materials are suitable for use as protective coatings for optical components and photovoltaic materials in a space environment. An ultra high vacuum (UHV) chamber is used to measure the

J. E. Ingram; A. S. Hodel; H. Kirkici

1997-01-01

227

HIGH PRESSURE VAPOR LIQUID EQUILIBRIUM FOR CARBON DIOXIDE + ETHANOL + 2BUTANONE SYSTEM  

Microsoft Academic Search

Vapor-liquid equilibrium was measured for three binary systems, carbon dioxide + ethanol, carbon dioxide + 2-butanone, and ethanol + 2-butanone, and a ternary system, carbon dioxide + ethanol + 2-butanone, at 313.2K. A circulation type apparatus was used in case of the high pressure systems, carbon dioxide + ethanol, carbon dioxide + 2-butanone, and carbon dioxide + ethanol + 2-butanone,

Tomoya TSUJI; Masatoshi SAKAI; Toshihiko HIAKI

228

Some Possible Filler Alloys with Low Vapor Pressures for Refractory-Metal Brazing.  

National Technical Information Service (NTIS)

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 ...

J. F. Morris

1973-01-01

229

Atmosperhic Pressure Spray Chemical Vapor Deposited CulnS(2) Thin Films for Photovoltaic Applications.  

National Technical Information Service (NTIS)

Solar cells have been prepared using atmospheric pressure spray chemical vapor deposited CuInS2 absorbers. The CuInS2 films were deposited at 390 degrees C using the single source precursor (PPh3)2CuIn(SEt)(sub 4) in an argon atmosphere. The absorber rang...

J. D. Harris R. P. Raffaelle K. K. Banger M. A. Smith D. A. Scheiman A. F. Hepp

2003-01-01

230

Identification of reaction products in the low-pressure chemical vapor deposition of molybdenum silicide  

Microsoft Academic Search

The gaseous species produced by low-pressure chemical vapor deposition of molybdenum silicide in a cold wall reactor were identified by mass spectroscopy. Lowering the ionizing electron energy made possible the unambiguous assignment of the mass spectra to individual species and also permitted useful quantitative estimates to be made. Thermodynamic calculations using the computer program SOLGASMIX were carried out on the

P. J. Gaczi; G. J. Reynolds

1989-01-01

231

Unusual effect of water vapor pressure on dehydration of dibasic calcium phosphate dihydrate.  

PubMed

Dibasic calcium phosphate occurs as an anhydrate (DCPA; CaHPO?) and as a dihydrate (DCPD; CaHPO?2H?O). Our objective was to investigate the unusual behavior of these phases. Dibasic calcium phosphate dihydrate was dehydrated in a (i) differential scanning calorimeter (DSC) in different pan configurations; (ii) variable-temperature X-ray diffractometer (XRD) at atmospheric and under reduced pressure, and in sealed capillaries; and (iii) water vapor sorption analyzer at varying temperature and humidity conditions. Dehydration was complete by 210C in an open DSC pan and under atmospheric pressure in the XRD. Unlike "conventional" hydrates, the dehydration of DCPD was facilitated in the presence of water vapor. Variable-temperature XRD in a sealed capillary and DSC in a hermetic pan with pinhole caused complete dehydration by 100C and 140C, respectively. Under reduced pressure, conversion to the anhydrate was incomplete even at 300C. The increase in dehydration rate with increase in water vapor pressure has been explained by the Smith-Topley effect. Under "dry" conditions, a coating of poorly crystalline product is believed to form on the surface of particles and act as a barrier to further dehydration. However, in the presence of water vapor, recrystallization occurs, creating cracks and channels and facilitating continued dehydration. PMID:24081471

Kaushal, Aditya M; Vangala, Venu R; Suryanarayanan, Raj

2011-04-01

232

Transient-pressure analysis in geothermal steam reservoirs with an immobile vaporizing liquid phase  

USGS Publications Warehouse

A finite-difference model for the radial horizontal flow of steam through a porous medium is used to evaluate transient-pressure behavior in the presence of an immobile vaporizing or condensing liquid phase. Graphs of pressure drawdown and buildup in terms of dimensionless pressure and time are obtained for a well discharging steam at a constant mass flow rate for a specified time. The assumptions are made that the steam is in local thermal equilibrium with the reservoir rocks, that temperature changes are due only to phase change, and that effects of vapor-pressure lowering are negligible. Computations show that when a vaporizing liquid phase is present the pressure drawdown exhibits behavior similar to that observed in noncondensable gas reservoirs, but delayed in time. A theoretical analysis allows for the computation of this delay and demonstrates that it is independent of flow geometry. The response that occurs upon pressure buildup is markedly different from that in a noncondensable gas system. This result may provide a diagnostic tool for establishing the existence of phase-change phenomena within a reservoir. ?? 1979.

Moench, A. F.; Atkinson, P. G.

1978-01-01

233

Comparative study on second harmonic conversion and saturation characteristics of three copper vapor laser beams of same average power and different spatial coherence  

NASA Astrophysics Data System (ADS)

This paper presents a comparative study on second harmonic conversion and saturation behavior of three copper vapor laser (CVL) beams of same average power up to 11 W (510 nm), however with different spatial coherence width of 17%, 35%, and 100% of the full beam cross-section. The nonlinear crystal employed is beta barium borate. It is observed that the trends in second harmonic (SH) conversion efficiency and its saturation are widely different for the three CVL pump beams. As expected, the conversion efficiency scaled up with increase in pump power. However, very interesting trends are observed in SH saturation characteristics with scaling of pump beams spatial coherence. For lower coherence CVL beam, the saturation of SH efficiency is observed at lower pump flux and at higher average power. Also, the saturation occurred at lower SH efficiency for CVL beam of lower spatial coherence. The fall in the SH efficiency after the peak is more rapid for lower spatial coherence pump beam. The experimental trends are explained in terms of combined effect degree of spatial coherence of pump beams and the thermal dephasing in the nonlinear crystal by high pump average power.

Prakash, Om; Mahakud, Ramakanta; Dixit, Sudhir Kumar

2011-11-01

234

In Pursuit of Parental Arc Magmas: The effects of pressure on the composition of H2O-saturated peridotite melts  

NASA Astrophysics Data System (ADS)

In the continued pursuit to understand the mantle origin of parental arc magmas, we investigate the nature and composition of quench products in a subset of the super-solidus H2O-saturated peridotite melting experiments of Till et al. (2012) and Grove et al. (2006). We examine a variety of filtering techniques for electron microprobe analyses of the quench products that utilize published mineral-fluid and mineral-melt partition coefficients. Our results suggest melts in equilibrium with olivine, orthopyroxene, clinopyroxene and spinel between 1-2 GPa are silica-saturated quartz tholeiites at melt fractions of 11-14%. We find both a low-alkali silica-undersaturated tholeiitic melt and a high-silica vapor-phase quench in equilibrium with a garnet peridotite assemblage at melt fractions of 10-20% from 3.2-4 GPa, suggesting that the peridotite-H2O system is below the second critical end point at these conditions. Between 860 and 1100C at 3.2 GPa, the H2O-saturated peridotite melting reaction consumes olivine, clinopyroxene and garnet to produce orthopyroxene and melt, while above 1100C olivine and orthopyroxene are consumed to produce melt. The isobaric melt production rates in these experiments are extremely low (dF/dT= 0.05-0.13%/C for 10-30% melt) and may represent a minimum in peridotite melt production rates, which occur when a melt is H2O-saturated. Our melt compositions are similar to those from the landmark experimental studies of Kushiro (1972) and Mysen (1973) who also analyzed the compositions of low degree mantle melts formed in the presence of excess H2O. Together the experimental observations suggest that low-extent melts of H2O-saturated peridotite are silica-saturated at lower pressures but become increasingly silica-undersaturated at higher pressures. Our experimental results also point to the likelihood of multiple inputs into the base of the mantle wedge when melting commences near 100 km depth beneath arcs. We discuss the composition of the hydrous silicate melt input into the mantle wedge relative to that of a coexisting solute-rich H2O fluid, as documented in this and previous experimental studies.

Till, C. B.; Grove, T. L.

2012-12-01

235

Vapor pressure of n-alkanes revisited; New high-precision vapor pressure data on n-decane, n-eicosane, and n-octacosane  

Microsoft Academic Search

The authors report new vapor pressure measurements on n-decane (268-490), n-eicosane (388-626), and n-octacosane (453-575) made with a modified ebulliometer and an inclined piston gauge. Benzene and water were the standards in the ebulliometric measurements on n-decane and n-eicosane, while n-decane was the standard for the measurements on n-octacosane. The high-quality data for n-decane, which were confirmed by a third-law''

Robert D. Chirico; Nguyen An; William V. Steele; M. Michael Strube; Costa Tsonopoulos

1989-01-01

236

The vapor pressure of 1, 1, 1, 2-tetrafluoroethane (R134a) and chlorodifluoromethane (R22)  

SciTech Connect

The authors measured the vapor pressure of chlorodifluoromethane (commonly known as R22) at temperatures between 217.1 and 248.5 K and of 1,1,1,2-tetrafluoroethane (commonly known as R134a) in the temperature range 214.4 to 264.7 K using a comparative ebulliometer. For 1,1,1,2-tetrafluoroethane at pressures between 220.8 and 1017.7 kPa (corresponding to temperatures in the range 265.6 to 313.2 K), additional measurements were made with a Burnett apparatus. The results have been combined for 1, 1, 1, 2-tetrafluoroethane with those already published from this laboratory at higher pressures to obtain a smoothing equation for the vapor pressure from 215 K to the critical temperature. For chlorodifluoromethane the results have been combined with certain published results to provide an equation for the vapor pressure at temperatures from 217 K to the critical temperature. 58 refs., 6 figs., 2 tabs.

Goodwin, A.R.H.; Defibaugh, D.R.; Weber, L.A. (National Institute of Standards and Technology, Gaithersburg, MD (United States))

1992-09-01

237

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

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

238

Adiabatic pressure dependence of the 2.7 and 1.9 micron water vapor bands  

NASA Technical Reports Server (NTRS)

An acoustic excitation technique is used to determine the adiabatic pressure derivative of the spectral absorptance of the 2.7 and 1.9 micron water vapor bands, and the 3.5 micron HCl band. The dependence of this derivative on thermodynamic parameters such as temperature, concentration, and pressure is evaluated. A cross-flow water vapor system is used to measure spectral absorptance. Taking F as the ratio of nonrigid to rotor line strengths, it is found that an F factor correction is needed for the 2.7 micron band. The F factor for the 1.9 micron band is also determined. In the wings of each band a wavelength can be found where the concentration dependence is predominant. Farther out in the wings a local maximum occurs for the temperature derivative. It is suggested that the pressure derivative is significant in the core of the band.

Mathai, C. V.; Walls, W. L.; Broersma, S.

1977-01-01

239

Measurments of the Vapor Pressure for the Solutions of HFC-134a and Ester Based Oil  

NASA Astrophysics Data System (ADS)

The paper presents measurements of the vapor pressure for the solutions of HFC-134a and ester based oil. The oil employed is eater based synthetic lubricant that is thought to be one of the lubricants compatible with alternative refrigerant HFC-134a.The measurements have been carried out for the range of temperatures between 263.15 K and 323.15 K for the HFC134a/ester based oil solutions. The uncertainty of the measurments is estimated as 10mK in temperature, 5kPa in pressure and 0.5% in concentration,respectively. Correlations that interpolate the experimental vapor pressure as a function of temperature and concentration are presented for practical use.

Takaishi, Yoshinori; Nakagawa, Hajime; Oguchi, Kosei

240

Deviations from Ideal Sublimation Vapor Pressure Behavior in Mixtures of Polycyclic Aromatic Compounds with Interacting Heteroatoms  

PubMed Central

Despite the relatively small atomic fraction of a given heteroatom in a binary mixture of polycyclic aromatic compounds (PAC), the inclusion of heteroatomic substituted compounds can significantly impact mixture vapor pressure behavior over a wide range of temperatures. The vapor pressures of several binary PAC mixtures containing various heteroatoms show varying behavior, from practically ideal behavior following Raoults law to significant deviations from ideality depending on the heteroatom(s) present in the mixture. Mixtures were synthesized using the quench-cool technique with equimolar amounts of two PAC, both containing heteroatoms such as aldehyde, carboxyl, nitrogen, and sulfur substituent groups. For some mixtures, deviation from ideality is inversely related to temperature, though in other cases we see deviations from ideality increasing with temperature, whereas some appear independent of temperature. Most commonly we see lower vapor pressures than predicted by Raoults law, which indicates that the interacting heteroatoms prefer the solid mixture phase as opposed to the vapor phase. Although negative deviations predominate from Raoults Law, the varying mixtures investigated show both higher and lower enthalpies and entropies of sublimation than predicted. In each mixture, a higher enthalpy of sublimation leads to higher entropy of sublimation than predicted, and vice versa.

Goldfarb, Jillian L.; Suuberg, Eric M.

2013-01-01

241

Sampler for collection and analysis of low vapor pressure chemical (LVPC) particulates/aerosols.  

PubMed

Detection of low vapor pressure chemicals (LVPCs) such as pesticides and other toxic/hazardous materials on various environmental surfaces as well as LVPC aerosols is a significant challenge for current vapor phase detectors. We describe a novel sampling device which utilizes stainless steel screens coated with a sticky polydimethylsiloxane coating for collecting LVPCs aerosolized off of a surface. Results are presented for the collection and detection of a pesticide simulant, dimethyl methylphosphonate sorbed onto silica gel (DMMP/SG), using direct analysis in real time-cylindrical ion trap mass spectrometry (DART-CITMS). PMID:24053780

Ewing, K J; Gibson, D; Sanghera, J; Miklos, F

2013-10-15

242

Determining Pore Pressures Along a Slip Surface Within a Saturated Elastic-Plastic Porous Medium  

NASA Astrophysics Data System (ADS)

Here we consider shear rupture along a slip surface in a fluid-saturated elastic-plastic porous medium, like in landslide and earthquake modeling, and assume that there are different poro-elasto-plastic response properties on the two sides of the slip surface. This different response may be because the fault bordering materials are dissimilar, or just because one side is actively yielding and the other is not, or is yielding but in a different mode. In effect, we are representing a core about a slip surface that divides two similar or contrasting materials. This representation is especially relevant in earthquake rupture dynamics. Studies of mature fault zones have noted a trend of fractured host rock extending 10--100m from the fault, with an ultracataclastic core ~100mm about or to one side of the principal slip surface (e.g., Chester and Chester, Tectonophys, 1998; Chester et al., Columbia Univ Pr, 2004). Furthermore, there is likely to exist a material contrast that may come from accumulating km of slip and a bias in accumulated damage. The local pore pressure at the slip surface influences the rupture dynamics because, through the effective stress concept, it controls the local shear strength along the fault, a feature neglected as a simplification in our preliminary poro-elasto-plastic modeling of dynamic rupture (Viesca et al., JGR, 2008). To determine pore pressures at the slip surface under locally elastic-plastic response, we must consider pore pressure discontinuities about that surface that arise in an undrained treatment of off-fault material and their amelioration within resulting thin diffusive boundary layers, such that pore pressure and fluid mass flux in the normal direction are continuous at the slip surface. Our approach builds on previous work considering the effect of contrasts in poroelastic properties on rupture propagation (Rudnicki and Rice, JGR, 2006; Dunham and Rice, JGR, 2008). Here we find expressions for the undrained pore pressure changes in the thin damage zone adjacent to the slip surface. This expression is dependent on the local fault-normal stresses and fault- parallel strains coupled to the undrained response in the adjacent bulk. Additionally, in the process of determining the pore pressure at the slip surface, we find a diffusivity under elastic-plastic response that is different from the diffusivity of linear poroelasticity theory (e.g., Rice and Cleary, Rev Geophys, 1976). We show how the full inclusion of pore pressure changes by these considerations affects rupture dynamics in explicit dynamic numerical simulations, first checking for validation against the poroelastic results of Dunham and Rice (2008), and then examining the effects relative to the fully undrained elastic-plastic simulations of Viesca et al. (2008) which neglected pore pressure changes on the fault itself.

Viesca, R. C.; Rice, J. R.; Dunham, E. M.

2008-12-01

243

Dislocation densities in InP single crystals grown under controlled phosphorus vapor pressure by the horizontal Bridgman method  

NASA Astrophysics Data System (ADS)

InP crystals were grown by the horizontal Bridgman method under controlled ambient phosphorus vapor pressure. The relationship between melt composition and crystal defects was investigated. Crystals grown under lower phosphorus vapor pressure have an In-rich composition. Dislocation densities (etch pit densities: EPD) and FWHM of X-ray diffraction minimized at a specific phosphorus pressure between 20 and 29 atm. From the reciprocal space mapping measurements, it is also shown that crystals grown under high or low phosphorus vapor pressure consist of mosaic domains surrounded by tilted boundaries.

Shimizu, Atsushi; Nishizawa, Jun-ichi; Oyama, Yutaka; Suto, Ken

2000-01-01

244

Steam pressure induced in crack-like cavities in moisture saturated polymer matrix composites during rapid heating  

Microsoft Academic Search

The time history of steam pressure inside an isolated crack-like micro-cavity in a polymer matrix composite is studied by assuming that the chemical potential of water is continuous across the cavity\\/polymer interface. Steam pressure inside the cavity is due to rapid heating of moisture-saturated composites from its initial temperature to a final temperature Tf. Exact closed form solutions are obtained

Chung-Yuen Hui; Vijayanand Muralidharan; Michael O. Thompson

2005-01-01

245

Kinetics of hydrothermal crystallization under saturated steam pressure and the self-healing effect by nanocrystallite for hydroxyapatite coatings  

Microsoft Academic Search

Hydroxyapatite coatings (HACs) with a low crystalline state were prepared using the plasma spraying process followed by hermetic autoclaving hydrothermal treatment at 100, 150 and 200C. Experimental evidence confirmed that the HACs became significantly crystallized and the content of amorphous calcium phosphate decreased by performing the autoclaving hydrothermal treatment in an ambient saturated steam pressure system. The obvious chemisorbed hydroxy

Chung-Wei Yang; Truan-Sheng Lui

2009-01-01

246

Sildenafil Increases Systemic Saturation and Reduces Pulmonary Artery Pressure in Patients with Failing Fontan Physiology  

PubMed Central

Objective The purpose of this study was to investigate the effect of sildenafil in patients with failing Fontan physiology. Design A retrospective chart review was performed to compare history and available data in patients with Fontan circulations before and after starting sildenafil. The paired and unpaired Students t-tests were used for statistical analyses. Patients Six patients at our institution with Fontan physiology, persistent symptoms of cyanosis or effusion, and poor hemodynamics as measured in the catheterization laboratory were placed on sildenafil. One patient was not included in the analysis because of insufficient length of treatment. All patients had symptoms of failing Fontan hemodynamics with either persistent cyanosis or effusions. In this group, the mean pulmonary artery pressure was greater than 15 mm Hg (17.4 1.5 mm Hg) with mean estimated pulmonary vascular resistance of 3.5 1.0 Wood units m2 prior to starting sildenafil. Results Sildenafil significantly increased the systemic arterial oxyhemoglobin saturation in this group (82.8 7.3% pre-treatment vs. 91.0 5.5% post-treatment, P = .017). In the four out of five patients who have had follow-up catheterizations, there was a significant decrease in pulmonary artery pressure (17.4 1.5 mm Hg pre-treatment vs. 13.8 2.1 mm Hg post-treatment, P = .018) and in estimated pulmonary vascular resistance pre- and post-sildenafil treatment (3.5 1.0 Wood units m2 pre-treatment vs. 2.0 0.4 Wood units m2 post-treatment, P = .031). Conclusions Sildenafil may be a useful adjunct to therapy in patients with failing Fontan physiology likely through its function as a pulmonary vasodilator.

Morchi, Gira S.; Ivy, D. Dunbar; Duster, Mark C.; Claussen, Lori; Chan, Kak-Chen; Kay, Joseph

2011-01-01

247

Continuum reaction field calculation of dielectric constant and vapor pressures for water and carbon disulfide.  

PubMed Central

Continuum reaction field theory is applied to calculations of dielectric constant, contribution of intermolecular interactions to the free energy of a liquid, and heat of vaporization. Introduction of repulsive interactions and the use of one adjustable parameter, the free volume, enables prediction of vapor pressures. The calculations are illustrated for a simple nonpolar liquid, carbon disulfide, and for liquid water. It is shown that when Onsager's equation is rearranged to a quadratic equation, and a recently found value of the polarizability is employed, its solutions for liquid water yield good agreement with experimental values throughout the whole temperature range. The decrease of the dielectric constant with temperature is essentially linear with the inverse of absolute temperature, but there is additional significant decrease due to the decrease of density with temperature. The relatively high value of the heat of vaporization of liquid water is expressed in terms of large dipolar interaction of a water molecule with the environment, which is due to polarization effects.

Nir, S

1976-01-01

248

Dislocation densities in InP single crystals grown under controlled phosphorus vapor pressure by the horizontal Bridgman method  

Microsoft Academic Search

InP crystals were grown by the horizontal Bridgman method under controlled ambient phosphorus vapor pressure. The relationship between melt composition and crystal defects was investigated. Crystals grown under lower phosphorus vapor pressure have an In-rich composition. Dislocation densities (etch pit densities: EPD) and FWHM of X-ray diffraction minimized at a specific phosphorus pressure between 20 and 29atm. From the reciprocal

Atsushi Shimizu; Jun-ichi Nishizawa; Yutaka Oyama; Ken Suto

2000-01-01

249

Low pressure MOCVD (metalorganic chemical vapor deposition) growth of InSb  

SciTech Connect

Low pressure (200 Torr) metalorganic chemical vapor deposition (MOCVD) of InSb has been examined through variation of the Column III (TMIn) and Column V (TMSb or TESb) precursor partial pressures. The use of lower growth pressure significantly enhanced the range of allowable Column III Column V partial pressures in which specular morphology InSb could be obtained without the formation of In droplets or Sb crystals. In addition, a 70% improvement in the average hole mobility was obtained, compared to InSb grown in the same reactor at atmospheric pressure. SIMS analysis revealed that Si at the substrate/epitaxial layer interface is an important impurity that may contribute to degradation of the mobility. Substitution of TESb for TMSb did not result in any improvement in the purity of the InSb. 6 refs.

Cunningham, B.T.; Schneider, R.P. Jr.; Biefeld, R.M.

1990-01-01

250

Standard method for estimating apparent vapor pressures and molecular weights of lubricating oils  

SciTech Connect

This method provides a calculation procedure for converting data obtained by ASTM Method D 972, Test for Evaporation Loss of Lubricating Greases and Oils, to apparent vapor pressures and molecular weights. It has been demonstrated to be applicable to petroleum based and synthetic ester lubricating oils, at temperatures of 394 to 533 K (250 to 500/sup 0/F). However, its applicability to lubricating greases has not been established. The test is run at the selected temperature for a sufficient time to give the selected amount of evaporation, which is 5 +- 1 percent unless otherwise specified. This evaporation rate is compared with a standard value for pure m-terphenyl to yield the apparent vapor pressure and molecular weight of the lubricating oil.

Not Available

1980-01-01

251

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

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

252

Investigation of solid/vapor interfaces using ambient pressure X-ray photoelectron spectroscopy.  

PubMed

Heterogeneous chemical reactions at vapor/solid interfaces play an important role in many processes in the environment and technology. Ambient pressure X-ray photoelectron spectroscopy (APXPS) is a valuable tool to investigate the elemental composition and chemical specificity of surfaces and adsorbates on the molecular scale at pressures of up to 130 mbar. In this review we summarize the historical development of APXPS since its introduction over forty years ago, discuss different approaches to minimize scattering of electrons by gas molecules, and give a comprehensive overview about the experimental systems (vapor/solid interfaces) that have been studied so far. We also present several examples for the application of APXPS to environmental science, heterogeneous catalysis, and electrochemistry. PMID:23598709

Starr, D E; Liu, Z; Hvecker, M; Knop-Gericke, A; Bluhm, H

2013-07-01

253

Thermo-optical determination of vapor pressures of TNT and RDX nanofilms.  

PubMed

Accurate thermodynamic parameters of thin films of explosives are important for understanding their behavior in the nanometer scale as well as in standoff detection. Using UV-absorbance spectroscopy technique, accurate thermodynamic parameters such as activation energies of sublimation, sublimation rates, and vapor pressures of the explosives cyclotrimethylenetrinitramine (RDX) and 2,4,6-trinitrotoluene (TNT) were determined. The values of these parameters are in excellent agreement with those reported using traditional experiments based on gravimetry. In terms of the Clapeyron equation, the dependence of RDX and TNT vapor pressures on temperature can be described by the relations LnP (Pa)=39.6-15459/T (K) and LnP (Pa)=34.9-12058/T (K), respectively. Heats of sublimation of RDX and TNT were also determined to be 128kJ/mol and 100.2kJ/mol, respectively. PMID:22099681

Hikal, Walid M; Paden, Jeffrey T; Weeks, Brandon L

2011-12-15

254

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

NASA Astrophysics Data System (ADS)

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 Genchten 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 Jrgen Mly; Yves Mheust; Grunde Lvoll; Mihailo Jankov; Gerhard Schfer; Jean Schmittbuhl Vadose Zone Journal, 2012, 11 (3), pp. vzj2011.0123 (2) Lvoll, G., M. Jankov, K.J. Mly, R. Toussaint, J. Schmittbuhl, G. Schaefer and Y. Mheust, 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. Lvoll, Y. Mheust, K.J. Mly and J. Schmittbuhl, Influence of pore-scale disorder on viscous fingering during drainage, Europhys. Lett., 71, 583 (2005).

Fiorentino, Eve-Agns; Toussaint, Renaud; Moura, Marcel; Jankov, Mihailo; Schfer, Gerhard; Jrgen Mly, Knut

2013-04-01

255

Characterization of the TIP4P-Ew water model: Vapor pressure and boiling point  

NASA Astrophysics Data System (ADS)

The liquid-vapor-phase equilibrium properties of the previously developed TIP4P-Ew water model have been studied using thermodynamic integration free-energy simulation techniques in the temperature range of 274-400 K. We stress that free-energy results from simulations need to be corrected in order to be compared to the experiment. This is due to the fact that the thermodynamic end states accessible through simulations correspond to fictitious substances (classical rigid liquids and classical rigid ideal gases) while experiments operate on real substances (liquids and real gases, with quantum effects). After applying analytical corrections the vapor pressure curve obtained from simulated free-energy changes is in excellent agreement with the experimental vapor pressure curve. The boiling point of TIP4P-Ew water under ambient pressure is found to be at 370.3+/-1.9 K, about 7 K higher than the boiling point of TIP4P water (363.7+/-5.1 K from simulations that employ finite range treatment of electrostatic and Lennard-Jones interactions). This is in contrast to the approximately +15 K by which the temperature of the density maximum and the melting temperature of TIP4P-Ew are shifted relative to TIP4P, indicating that the temperature range over which the liquid phase of TIP4P-Ew is stable is narrower than that of TIP4P and resembles more that of real water. The quality of the vapor pressure results highlights the success of TIP4P-Ew in describing the energetic and entropic aspects of intermolecular interactions in liquid water.

Horn, Hans W.; Swope, William C.; Pitera, Jed W.

2005-11-01

256

Outcome of Vaportrode Transurethral Vaporization of the Prostate Using Pressure-Flow Urodynamic Criteria  

Microsoft Academic Search

Objectives. To use pressure-flow urodynamic parameters to evaluate the outcome of patients with benign prostatic hyperplasia (BPH) who were treated with transurethral vaporization of the prostate (TUVP) using the Vaportrode.Methods. Forty consecutive patients (mean age 71.7 years) undergoing TUVP for treatment of symptomatic obstructive BPH or urinary retention were evaluated preoperatively and postoperatively with American Urological Association (AUA) Symptom Score,

Michael G Desautel; Tracy L Burney; Patricia A Diaz; Alphonso Austria; Gopal H Badlani

1998-01-01

257

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

NASA Technical Reports Server (NTRS)

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.

Morris, J. F.

1973-01-01

258

Characterization of the TIP4P-Ew water model: vapor pressure and boiling point.  

PubMed

The liquid-vapor-phase equilibrium properties of the previously developed TIP4P-Ew water model have been studied using thermodynamic integration free-energy simulation techniques in the temperature range of 274-400 K. We stress that free-energy results from simulations need to be corrected in order to be compared to the experiment. This is due to the fact that the thermodynamic end states accessible through simulations correspond to fictitious substances (classical rigid liquids and classical rigid ideal gases) while experiments operate on real substances (liquids and real gases, with quantum effects). After applying analytical corrections the vapor pressure curve obtained from simulated free-energy changes is in excellent agreement with the experimental vapor pressure curve. The boiling point of TIP4P-Ew water under ambient pressure is found to be at 370.3+/-1.9 K, about 7 K higher than the boiling point of TIP4P water (363.7+/-5.1 K; from simulations that employ finite range treatment of electrostatic and Lennard-Jones interactions). This is in contrast to the approximately +15 K by which the temperature of the density maximum and the melting temperature of TIP4P-Ew are shifted relative to TIP4P, indicating that the temperature range over which the liquid phase of TIP4P-Ew is stable is narrower than that of TIP4P and resembles more that of real water. The quality of the vapor pressure results highlights the success of TIP4P-Ew in describing the energetic and entropic aspects of intermolecular interactions in liquid water. PMID:16321097

Horn, Hans W; Swope, William C; Pitera, Jed W

2005-11-15

259

On the application of G E models to high-pressure vaporliquid equilibrium calculations  

Microsoft Academic Search

This paper demonstrates that the two excess Gibbs free energy GE models with temperature-dependent parameters in the modified HuronVidal first-order (MHV1) mixing rule allow the PengRobinson equation of state modified by Stryjek and Vera (PRSV) to be used for calculation of vaporliquid equilibria over wide ranges of temperature and pressure. Good results are obtained for strongly non-ideal binary and ternary

Tatsuhiko Ohta

1996-01-01

260

Vapor Pressure and Evaporation Coefficient of Silicon Monoxide over a Mixture of Silicon and Silica  

NASA Technical Reports Server (NTRS)

The evaporation coefficient and equilibrium vapor pressure of silicon monoxide over a mixture of silicon and vitreous silica have been studied over the temperature range (1433 to 1608) K. The evaporation coefficient for this temperature range was (0.007 plus or minus 0.002) and is approximately an order of magnitude lower than the evaporation coefficient over amorphous silicon monoxide powder and in general agreement with previous measurements of this quantity. The enthalpy of reaction at 298.15 K for this reaction was calculated via second and third law analyses as (355 plus or minus 25) kJ per mol and (363.6 plus or minus 4.1) kJ per mol respectively. In comparison with previous work with the evaporation of amorphous silicon monoxide powder as well as other experimental measurements of the vapor pressure of silicon monoxide gas over mixtures of silicon and silica, these systems all tend to give similar equilibrium vapor pressures when the evaporation coefficient is correctly taken into account. This provides further evidence that amorphous silicon monoxide is an intimate mixture of small domains of silicon and silica and not strictly a true compound.

Ferguson, Frank T.; Nuth, Joseph A., III

2012-01-01

261

Vapor pressures and enthalpies of sublimation of D-glucose, D-xylose, cellobiose, and levoglucosan  

SciTech Connect

The vapor pressures of {alpha}-D-glucose (or dextrose), D-xylose, D-cellobiose (or 4-{beta}-D-glucopyranosyl-D-glucopyranose), and levoglucosan (or 1,6-anhydro-{beta}-D-glucopyranose) have been measured using the Knudsen effusion technique, in the range of temperatures from 344 to 488 K. The measurements were all made in the solid sublimation regime, and enthalpies of sublimation were calculated from the Clausius-Claperon equation. The vapor pressures may be correlated by ln(P/Pa) = A {minus} B/(T/K), where A = 53.16, B = 23.382 ({+-}600) for D-glucose (395--406 K), A = 46.29 and B = 19,006 ({+-} 375) for D-xylose (370--395 K), and A = 70.30 and B = 36,264 ({+-} 5,220) for cellobiose (474--488 K). Levoglucosan displayed a solid phase transition at approximately 386 K, and its vapor pressure was affected accordingly. For this material, A = 38.96 and B = 15,049 ({+-} 123) in the temperature range 344--386 K and A = 31.19 and B = 12,066 ({+-} 709) in the temperature range 386--405 K.

Oja, V.; Suuberg, E.M. [Brown Univ., Providence, RI (United States). Div. of Engineering] [Brown Univ., Providence, RI (United States). Div. of Engineering

1999-01-01

262

Vapor pressures and sublimation enthalpies of seven heteroatomic aromatic hydrocarbons measured using the Knudsen effusion technique  

PubMed Central

The vapor pressures of seven heteroatom-containing cyclic aromatic hydrocarbons, ranging in molecular weight from (168.19 to 208.21) grams?mol?1 were measured over the temperature range of (301 to 486) Kelvin using the isothermal Knudsen effusion technique. The compounds measured include: anthraquinone, 9-fluorenone, 9-fluorenone oxime, phenoxazine, phenoxathiin and 9H-pyrido[3,4-b]indole. These solid-state sublimation measurements provided values that are compared to vapor pressures of parent aromatic compounds (anthracene and fluorene) and to others with substituent groups in order to examine the effects of alcohol, ketone, pyridine, and pyrrole functionality on this property. The enthalpies and entropies of sublimation for each compound were determined from the Clausius-Clapeyron equation. Though there is no consistent trend in terms of the effects of substitutions on changes in the enthalpy or entropy of sublimation, we note that the prevalence of enthalpic or entropic driving forces on vapor pressure depend on molecule-specific factors and not merely molecular weight of the substituents.

Goldfarb, Jillian L.; Suuberg, Eric M.

2010-01-01

263

Simultaneous Heat and Momentum Transfer in Two-Phase Systems at Low Pressure and High Temperature: Vapor Phase  

Microsoft Academic Search

The heat and momentum transfer in a liquid-vapor two-phase film system at high temperature and low pressure is studied by the example of the removal of highly volatile fractions from high-boiling liquids in film evaporators. The temperature and velocity distributions in the vapor phase are determined.

V. N. Babak

2005-01-01

264

Evaluation of transurethral vaporization of prostate with pressure-flow analysis and other clinical measures.  

PubMed

Transurethral vaporization of the prostate (TUVP) is a promising new alternative modality for resection of obstructing adenomatous prostatic tissue. We evaluated the efficacy of TUVP for treatment of symptomatic benign hyperplasia (BPH) or urinary retention using pressure-flow analysis and other clinical measures. Twenty-seven men (mean age 72) with symptomatic BPH (N = 21) or urinary retention (N = 6) underwent TUVP using the VaporTrode loop. Patients were evaluated both preoperatively and postoperatively by subjective and objective criteria including AUA symptom score, uroflowmetry, postvoiding residual volume (PVR), and detrusor pressure (Pdet) at maximum flow. Complete follow-up data were available in 19 patients with an average follow-up of 9 weeks (range 4-32). The average symptom score was reduced from 19.9 to 5.58 (p < 0.0001). The average peak uroflow rate (Qmax) improved from 7.0 ml/sec to 18.1 mL/sec (p < 0.001). The average PVR was reduced from 163 mL to 14 mL (p < 0.003), and there was a similar reduction in Pdet at maximum flow from 96 cm H2O to 44 cm H2O (p < 0.001). The overall complication rate was 11%. These included meatal stenosis (N = 1), temporary urinary retention (N = 1), and residual prostate tissue causing obstruction (N = 1). In conclusion, TUVP with the VaporTrode yields a significant improvement in AUA symptom score, peak uroflow rate, PVR, and detrusor pressure at maximum flow, denoting relief of bladder outlet obstruction. This review of our experience with TUVP provides additional evidence for the use of the VaporTrode as a safe and effective alternative surgical modality for the treatment of symptomatic BPH. PMID:8905496

Burney, T L; Desautel, M G; Badlani, G H

1996-10-01

265

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

NASA Technical Reports Server (NTRS)

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.

Chauveau, Christian; Goekalp, Iskender

1993-01-01

266

Determination of capillary pressure-saturation relation by pore-morphology-based and lattice-Boltzmann simulation  

NASA Astrophysics Data System (ADS)

In this study we present two different models for the determination of the capillary pressure-saturation relation in porous media. The first one is a pore-morphology-based model where we use methods from morphological image analysis to calculate the quasi-static primary drainage curve. Compared to previous publications in this field (Hilpert and Miller 2001), we extended the method to model trapped or irreducible wetting phase (WP). Additionally, we could optimize it in a way that the computing time is significantly reduced. The second method to determine the capillary pressure-saturation relation is a two-phase lattice-Boltzmann (LB) model. Using a recently developed model for multi-phase flow (Tlke et al. 2001) we simulated the drainage of the porous medium by several pressure steps starting at total saturation. As test systems, we used generated randomly sphere packages and x-ray images of a sintered borosilicate glass. Our simulations show that the capillary pressure-saturation curves from the both methods are very similar. However the morphological model is orders of magnitude faster than the LB simulation. But we point out that the good agreement strongly depends on the geometry of the investigated porous medium. Due to the model formulation, the pore-morphology-based simulation cannot be applied if the pore structure is strongly anisotropic (e. g. cracks). References: M. Hilpert and C. T. Miller: Pore-morphology-based simulations of drainage in totally wetting porous media, Advances in Water Resources, 24, p.243 (2001) J. Tlke, M. Krafczyk, M. Schulz, E. Rank: Lattice Boltzmann simulations of binary fluid flow through porous media, Phil. Trans. R. Soc. Lond. A, Vol 360, Nr. 1792, p.535 (2002)

Schulz, V.; Toelke, J.; Vogel, H.; Krafzcyk, M.; Roth, K.

2002-12-01

267

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

NASA Astrophysics Data System (ADS)

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.

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

2013-01-01

268

Effects of ambient water vapor pressure and temperature on evaporative water loss in Peromyscus maniculatus and Mus musculus  

Microsoft Academic Search

SummaryThe effects of ambient water vapor pressure (VP) and temperature on evaporative water loss (EWL) from the head and trunk ofPeromyscus maniculatus andMus musculus were measured with dew point hygrometry. At a given ambient temperature both head and trunk EWL were directly proportional to the water vapor pressure deficit. Cutaneous EWL in both species was directly related to the difference

Richard M. Edwards; Howard Haines

1978-01-01

269

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

Microsoft Academic Search

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

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

1998-01-01

270

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

Microsoft Academic Search

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

L. A. Weber; A. M. Silva

1994-01-01

271

Vapor pressures and gas-phase PVT data for 1-Chloro-1,2,2,2-tetrafluoroethane (R124)  

Microsoft Academic Search

We present new data for the vapor pressure andPVT surface of 1-chloro-1,2,2,2-lelralluoroethane (designated R124 by the refrigeration industry) in the temperature range 278423 K. ThePVT data are for the gas phase at densities up to 1.5 times the critical density. Correlating equations are given for the vapor pressures from 220 K to the critical temperature, 395.43 K, and for thePVT

S. J. Boyes; L. A. Weber

1994-01-01

272

Lattice Parameter Deviation of InP Single Crystals Grown by the Horizontal Bridgman Method under Controlled Phosphorus Vapor Pressure  

NASA Astrophysics Data System (ADS)

InP crystals were grown by the horizontal Bridgman method under controlled ambient phosphorus vapor pressure. The lattice parameter was measured by X-ray diffraction analysis. The lattice parameter of the InP crystals increased with increasing phosphorus vapor pressure. The relationship between the lattice parameter and composition indicates that the In-rich composition is attributed to the P-vacancies. This corresponds to the photoluminescence spectra of P-vacancy-related emission.

Shimizu, Atsushi; Nishizawa, Jun-ichi; Oyama, Yutaka; Suto, Ken

2001-04-01

273

Lattice Parameter Deviation of InP Single Crystals Grown by the Horizontal Bridgman Method under Controlled Phosphorus Vapor Pressure  

Microsoft Academic Search

InP crystals were grown by the horizontal Bridgman method under controlled ambient phosphorus vapor pressure. The lattice parameter was measured by X-ray diffraction analysis. The lattice parameter of the InP crystals increased with increasing phosphorus vapor pressure. The relationship between the lattice parameter and composition indicates that the In-rich composition is attributed to the P-vacancies. This corresponds to the photoluminescence

Atsushi Shimizu; Jun-ichi Nishizawa; Yutaka Oyama; Ken Suto

2001-01-01

274

Critical mass flow rates through pressure relief valves  

Microsoft Academic Search

Simplified semi-empirical equations for the prediction of critical mass flow rates through pressure relief valves are presented. The fluid phases treated include hot and boiling liquids, liquid-vapor mixtures and saturated vapor. Predictive formulations are presented which express the critical mass flux explicitly in terms of reservoir temperature and pressure or reservoir quality, specific volumes of the liquid and vapor phases,

D. W. Sallet

1991-01-01

275

The Vapor Pressure of Environmentally Significant Organic Chemicals: A Review of Methods and Data at Ambient Temperature  

SciTech Connect

The experimental techniques and the prediction procedures for the determination or evaluation of the vapor pressure of environmentally relevant organic compounds are described; with 259 references examined. For each of them the characteristics of precision and accuracy are given, when available from the literature. The experimental methods are classified as {open_quotes}direct{close_quotes} and {open_quotes}indirect.{close_quotes} The first class includes all those which can measure directly the vapor pressure, while the second concerns those which need {open_quotes}known{close_quotes} vapor pressures of reference compounds for the calibration. Prediction methods are based on the application of the Clapeyron{endash}Clausius equation or on the quantitative structure-property relationships. Also correlation methods require a suitable calibration. The vapor pressures at ambient temperature for several polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and furans, selected pesticides, and some reference compounds are tabulated together with the vapor pressure equations and the enthalpy values in the temperature range of measurement. A critical comparison, based on a statistical analysis of the data obtained with different methods and derived from 152 references, is also carried out. {copyright} {ital 1996 American Institute of Physics and American Chemical Society.}{ital Key words:} chlorinated biphenyls; chlorinated dioxins; critically reviewed data; critically reviewed methods; pesticides; polynuclear aromatics; vapor pressure. {copyright} {ital 1996} {ital American Institute of Physics and American Chemical Society}

Delle Site, A. [ENEA, Environmental Department, AMB-TEIN, Via Anguillarese 301, 00060, Rome (Italy)

1997-01-01

276

Vapor pressures and heats of vaporization of primary coal tars. Quarterly technical progress report, 1 April 1993--30 June 1993  

SciTech Connect

A significant amount of time has been devoted during this quarter to preparing the equipment for production of the tars to be measured, and preparing the equipment for measurements by the so-called Knudsen effusion method. This method will be summarized below. The various effusion methods are based on the effusion of the vaporized substance from a surface, or through an orifice [1]. One of these is the Knudsen method [2, 3], in which the substance effuses through small holes of known area. The principal applications of this method have been in the determination of the vapor pressure of metals such as mercury, cadmium, zinc and lead. It has however been equally effective for obtaining the vapor pressure of organic crystals and compounds [4, 5, 6, 7, 8, 99, 20]. The Knudsen method is used for the measurement of low vapor pressures in the range from 1 to 10{sup {minus}6} mm Hg under molecular flow conditions (pressures inside and outside cell are low enough for gas molecules make collisions only with the walls of the cell) and involves measurement of the rate of loss of molecules of the evaporating substance, leaving the opening of an effusion cell. Measurement are made under isothermal conditions, with weight loss being recorded as a function of time simultaneously with sample temperature, and with pressure measured outside the effusion cell. The basic theory of the effusion method was reviewed in the literature [2, 39, 12]. The basic theory of method is based upon the kinetic theory of gases, from which Knudsen derived an expression for the slow isothermal flow out of a cell with a small hole in it. According to Knudsen [1] the vapor pressure of a material in the cell can be calculated from his result, using the equation given.

Suuberg, E.M.

1993-11-01

277

High-pressure vapor-liquid equilibrium measurement for the binary mixtures of carbon dioxide+n-butanol  

Microsoft Academic Search

High-pressure vapor-liquid equilibrium data for the binary mixtures of CO2+n-butanol were measured at various isotherms of (313.15, 323.15, 333.15 and 343.15) K, respectively. The equilibrium compositions\\u000a of vapor and liquid phases and pressures at each temperature were measured in a circulation-type equilibrium apparatus. To\\u000a facilitate easy equilibration, both vapor and liquid phases were circulated separately in the experimental apparatus and

Jong Sung Lim; Cheol Hun Yoon; Ki-Pung Yoo

2009-01-01

278

Highly ionized physical vapor deposition plasma source working at very low pressure  

SciTech Connect

Highly ionized discharge for physical vapor deposition at very low pressure is presented in the paper. The discharge is generated by electron cyclotron wave resonance (ECWR) which assists with ignition of high power impulse magnetron sputtering (HiPIMS) discharge. The magnetron gun (with Ti target) was built into the single-turn coil RF electrode of the ECWR facility. ECWR assistance provides pre-ionization effect which allows significant reduction of pressure during HiPIMS operation down to p = 0.05 Pa; this is nearly more than an order of magnitude lower than at typical pressure ranges of HiPIMS discharges. We can confirm that nearly all sputtered particles are ionized (only Ti{sup +} and Ti{sup ++} peaks are observed in the mass scan spectra). This corresponds well with high plasma density n{sub e} {approx} 10{sup 18} m{sup -3}, measured during the HiPIMS pulse.

Stranak, V.; Herrendorf, A.-P.; Drache, S.; Hippler, R. [Institute of Physics, University of Greifswald, Felix-Hausdorff-Str. 6, 17489 Greifswald (Germany); Cada, M.; Hubicka, Z. [Institute of Physics v. v. i., Academy of Science of the Czech Republic, Na Slovance 2, 182 21 Prague (Czech Republic); Tichy, M. [Faculty of Mathematics and Physics, Charles University in Prague, V Holesovickach 2, 180 00 Prague (Czech Republic)

2012-04-02

279

High-pressure vapor-liquid equilibria in the propane-1-propanol system  

SciTech Connect

High-pressure isothermal vapor liquid equilibrium data were measured for the propane-1-propanol system at 81.6, 105.2, and 120.1 C in a static equilibrium cell with liquid-phase sampling by a piston-driven sampling rod and homogenizing the sample with a static jet mixer. The vapor phase was sampled by releasing it into an evacuated manifold, and the gas chromatograph was calibrated with a new variable volumetric device. Satisfactory modeling was achieved with the combined method using the UNIQUAC equation with equations of sate: the group contribution EOS, Peng-Robinson EOS, or the two-parameter Virial EOS. Differences between the measured and calculated vapor-phase mole fractions, however, were significant for the lower pressure regions of the 81.6 and 120.1 C isotherms. UNIQUAC parameters, hitherto unavailable, with fairly strong temperature dependence in the 81.6 to 120.1 C range are proposed for the system. The covariance matrix indicated a significant correlation among the parameters. The classical mixing rule interaction parameters required for the original Peng-Robinson EOS in the combined method were obtained using the direct method and were temperature-independent for the isotherms for which the propane was supercritical. The possibility of propane/1-propanol immiscibility was theoretically examined according to the criteria of Baker et al. The plots of Gibbs energy of mixing vs. phase mole fractions did not indicate liquid-phase splitting, but the inferences are EOS-dependent and must await visual confirmation. The authors earlier vapor-phase thermodynamic consistency test indicated the data for all three data sets not to be inconsistent.

Muehlbauer, A.L.; Raal, J.D. (Univ. of Natal, Durban (South Africa))

1993-04-01

280

Visual Observation of Vapor Film Collapse Behavior During Vapor Explosion  

SciTech Connect

During severe accident of a light water reactor, various thermal hydraulic phenomena including vapor explosion could threaten the integrity of the containment vessel. Thermal detonation model is proposed to describe the vapor explosion. According to the model, several processes should be sequentially satisfied for the trigger phenomena of the vapor explosion. One of the most important processes for the trigger phenomena is the vapor film collapse around high temperature molten material droplets. In the present study, the vapor film collapse behavior around high temperature solid particle submerged into water was experimentally investigated by attacking a pressure pulse to the vapor film on a high temperature sold particle. The interfacial phenomena between vapor and water were measure by using a high-speed video camera of the maximum speed of 40,500 fps. The visual data obtained were processed with visual data processing techniques. That is, the average vapor film thickness was estimated, dynamic behaviors of the interfaces were analyzed with PIV technique and the interface movement was estimated with the digital auto correlation techniques from the visual data obtained. Furthermore, the transients of the temperature and pressure were simultaneously measured. The interfacial temperatures between vapor and water, and between molted liquid and water are analytically estimated by solving the heat conduction equation with the data obtained as the boundary conditions. It is clarified that vapor collapse by pressure pulse occurs homogeneously around the vapor film surface on a high temperature particle. Microscopic information are obtained from the visual data by using visual data processing technique, PIV technique and digital auto-correlation technique. At the time the vapor film surface changes to white, the saturation temperature exceeds the interfacial temperature. The microscopic vapor film collapse behavior indicates the possibility of the phase change at the vapor film collapse. (authors)

Yutaka Abe; Hideki Nariai [University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan)

2002-07-01

281

Calculation of the vapor-saturated liquidus for the NaCl-CO2-H2O system  

USGS Publications Warehouse

The polybaric liquidus surface for the H2O-rich corner of the NaCl-CO2-H2O ternary is calculated, relying heavily on 1. (1) a Henry's law equation for CO2 in brines (modified from Drummond, 1981), 2. (2) the assumption that the contributions of dissolved NaCl and CO2 in lowering the activity of H2O are additive, and 3. (3) data on the CO2 clathrate solid solution (nominally CO2 ?? 7.3H2O, but ranging from 5.75 to 8 or 9 H2O) from Bozzo et al. (1975). The variation with composition of the activity of CO2??7.3H2O, or any other composition within the clathrate field, is small, thereby simplifying the calculations appreciably. Ternary invariant points are 1. (1) ternary eutectic at -21.5??C, with ice + clathrate + hydrohalite NaCl-??H2O + brine mNaCl = 5.15, mco2 = 0.22 + vapor Ptotal ??? Pco2 = 5.7 atm; 2. (2) peritectic at -9.6??C, with clathrate + hydrohalite + liquid CO2 + brine mNaCl = 5.18, mco2 = 0.55 + vapor (Ptotal ??? Pco2 = 26.47 atm); and 3. (3) peritectic slightly below +0.1 ??C, with halite + hydrohalite + liquid CO2 + brine (mNaCl ??? 5.5, mco2 ??? 0.64) + vapor (Ptotal ??? Pco2 ??? 34 atm). CO2 isobars have been contoured on the ternary liquidus and also on the 25??C isotherm. An important caveat regarding the application of this information to the interpretation of the freezing-thawing behavior of fluid inclusions is that metastable behavior is a common characteristic of the clathrate. ?? 1993.

Barton, P. B.; I-Ming, C.

1993-01-01

282

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

SciTech Connect

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.

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

1995-02-01

283

Relationship between capillary pressure, saturation, and interfacial area from a model of mixed-wet triangular tubes  

NASA Astrophysics Data System (ADS)

A simple bundle of triangular tubes model is employed to calculate specific interfacial area for primary drainage, imbibition, and secondary drainage for mixed-wet conditions. In this model, only the interfaces between bulk and corner fluid are contributory to the interfacial area. Accurate expressions for the capillary entry pressures are employed, which account for the possibility of hinging interfaces in the corners due to contact angle hysteresis. The results show that very different trends in the specific interfacial area versus saturation curves can occur during imbibition, depending on the advancing contact angle and the reversal point after primary drainage. For water-wet conditions, interfacial area scanning curves coincide with the bounding imbibition curve, while for oil-wet conditions, the scanning curves may cross each other because of the impact that hinging interfaces in the pore corners have on the invasion order of the pore sizes. Analytical expressions for specific interfacial area as a function of saturation and capillary pressure are derived for primary drainage of triangular tubes. Approximate correlations for interfacial area as a function of saturation are suggested for the subsequent imbibition and drainage processes. The correlations are fitted to the simulated data, and good agreement is obtained. We also demonstrate that hysteresis remains present in the relationship between interfacial area, capillary pressure, and saturation when contact angle hysteresis is assumed. Hysteresis may be significant for both water-wet and mixed-wet conditions. A more sophisticated model is required to examine if this is also the case when hysteresis is caused by phase entrapment.

Helland, J. O.; SkjVeland, S. M.

2007-12-01

284

The vapor pressure of 1,1,1,2-tetrafluoroethane (R134a) and chlorodifluoromethane (R22)  

NASA Astrophysics Data System (ADS)

We measured the vapor pressure of chlorodifluoromethane (commonly known as R22) at temperatures between 217.1 and 248.5 K and of 1,1,1,2-tetrafluoroethane (commonly known as R134a) in the temperature range 214.4 to 264.7 K using a comparative ebulliometer. For 1,1,1,2-tetrafluoroethane at pressures between 220.8 and 1017.7kPa (corresponding to temperatures in the range 265.6 to 313.2K), additional measurements were made with a Burnett apparatus. We have combined our results for 1,1,1,2-tetrafluoroethane with those already published from this laboratory at higher pressures to obtain a smoothing equation for the vapor pressure from 215 K to the critical temperature. For chlorodifluoromethane our results have been combined with certain published results to provide an equation for the vapor pressure at temperatures from 217 K to the critical temperature.

Goodwin, A. R. H.; Defibaugh, D. R.; Weber, L. A.

1992-09-01

285

Measurement of vapor pressures and heats of sublimation of dicarboxylic acids using atmospheric solids analysis probe mass spectrometry.  

PubMed

Vapor pressures of low volatility compounds are important parameters in several atmospheric processes, including the formation of new particles and the partitioning of compounds between the gas phase and particles. Understanding these processes is critical for elucidating the impacts of aerosols on climate, visibility, and human health. Dicarboxylic acids are an important class of compounds in the atmosphere for which reported vapor pressures often vary by more than an order of magnitude. In this study, atmospheric solids analysis probe mass spectrometry (ASAP-MS), a relatively new atmospheric pressure ionization technique, is applied for the first time to the measurement of vapor pressures and heats of sublimation of a series of dicarboxylic acids. Pyrene was also studied because its vapor pressures and heat of sublimation are relatively well-known. The heats of sublimation measured using ASAP-MS were in good agreement with published values. The vapor pressures, assuming an evaporation coefficient of unity, were typically within a factor of ?3 lower than published values made at similar temperatures for most of the acids. The underestimation may be due to diffusional constraints resulting from evaporation at atmospheric pressure. However, this study establishes that ASAP-MS is a promising new technique for such measurements. PMID:22432524

Bruns, Emily A; Greaves, John; Finlayson-Pitts, Barbara J

2012-06-21

286

Effects of pressure and partial water saturation on gas permeability in tight sands: experimental results  

Microsoft Academic Search

Effective permeability to gas with varying degrees of brine saturation has been measured in the laboratory on several tight sandstones from the Spirit River formation of Alberta, Canada. Gas permeability as low as 2 x 10⁻⁸ darcy was successfully measured using a pulse decay permeameter with nitrogen as the mobile fluid. Results show a very strong dependence of gas permeability

J. D. Walls; A. M. Nur; T. Bourbie

1980-01-01

287

Preliminary design: duplex tube low-pressure saturated steam generator for large LMFBR plant. Final report  

Microsoft Academic Search

A preliminary design was completed for a steam generator which is applicable to a four loop LMFBR plant of 1000 MWe gross output employing dry and saturated steam conditions. Two steam generators of 364 MWt thermal capacity would be in each loop. The steam generator is a straight, duplex tube design with a shell bellows for thermal expansion and a

1979-01-01

288

PARAMETER ESTIMATION OF TWO-FLUID CAPILLARY PRESSURE-SATURATION AND PERMEABILITY FUNCTIONS  

EPA Science Inventory

Capillary pressure and permeability functions are crucial to the quantitative description of subsurface flow and transport. Earlier work has demonstrated the feasibility of using the inverse parameter estimation approach in determining these functions if both capillary pressure ...

289

Vapor pressures and enthalpies of sublimation of polycyclic aromatic hydrocarbons and their derivatives  

SciTech Connect

The vapor pressures of a series of polycyclic aromatic hydrocarbons (PAH) and heteroatom-containing PAH have been measured using the Knudsen effusion technique. Aromatic hydrocarbons examined included anthracene, phenanthrene, pyrene, 2,3-benzofluorene, naphthacene, perylene, pentacene, and coronene. Heteroatomic aromatic species examined included phenanthridine, perinaphthenone, 3-hydroxy-1-phenalen-1-one, benz[g]isoquinoline-5,10-dione, 1,2-benzodiphenylene sulfide, 1-hydroxypyrene, and 6,11-dihydroxy-5,12-naphthacenedione. The measurements were all made in the solid sublimation regime, and enthalpies of sublimation were calculated from the Clausius-Clapeyron equation.

Oja, V.; Suuberg, E.M. [Brown Univ., Providence, RI (United States). Div. of Engineering] [Brown Univ., Providence, RI (United States). Div. of Engineering

1998-05-01

290

Oxalate Ion Decomposition under UV Light from Low Pressure Mercury Vapor Lamps  

Microsoft Academic Search

Kinetics of oxalate ion decomposition under UV light from low pressure mercury vapor lamps (LPMVL) was studied in a batch reactor. The effects of UV light intensity (1.3810 to 5.2710 ELs, where E: Einstein or 1 mole of photons), temperature (15?35C), initial oxalate concentration ((2.05?21.1)??10 M), initial pH (5.45?8.94) and alkalinity (050 mg L as CaCO3) on the photodecomposition kinetics

Gonca F. Talu; Vasil Diyamandoglu; Urs Jans

2007-01-01

291

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

NASA Technical Reports Server (NTRS)

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).

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

1995-01-01

292

Growth of the microalgae Neochloris oleoabundans at high partial oxygen pressures and sub-saturating light intensity.  

PubMed

The effect of partial oxygen pressure on growth of Neochloris oleoabundans was studied at sub-saturating light intensity in a fully-controlled stirred tank photobioreactor. At the three partial oxygen pressures tested (P(O)?= 0.24; 0.63; 0.84 bar), the specific growth rate was 1.38; 1.36 and 1.06 day(-1), respectively. An increase of the P(CO)?from 0.007 to 0.02 bar at P(O?) of 0.84 bar resulted in an increase in the growth rate from 1.06 to 1.36 day(-1). These results confirm that the reduction of algal growth at high oxygen concentrations at sub-saturating light conditions is mainly caused by competitive inhibition of Rubisco. This negative effect on growth can be overcome by restoring the O(2)/CO(2) ratio by an increase in the partial carbon dioxide pressure. In comparison to general practice (P(O(2)) = 0.42 bar), working at partial O(2) pressure of 0.84 bar could reduce the energy requirement for degassing by a factor of 3-4. PMID:22079686

Sousa, Cludia; de Winter, Lenneke; Janssen, Marcel; Vermu, Marian H; Wijffels, Ren H

2012-01-01

293

Tests of a Low-Pressure Switch Protected by a Saturating Inductor.  

National Technical Information Service (NTIS)

Low-pressure switches and magnetic switches have been tested as possible replacements for the high-pressure switches currently used on Experimental Test Accelerator (ETA) and Advanced Test Accelerator (ATA). When the low-pressure switch is used with a low...

E. J. Lauer D. L. Birx

1982-01-01

294

Tuning the Morphology of Solvent Annealed Thin Films of Polystyrene-b-Polyethylene Oxide with Controlled Saturations of Water and Toluene Vapors  

NASA Astrophysics Data System (ADS)

Solvent annealing can be used to facilitate the self-assembly of block copolymer thin films and has several advantages over thermal annealing including room-temperature processing, domain orientation control and the ability to anneal polymers not amenable to thermal processing. We have developed a controlled process design for performing solvent annealing that incorporates continuous flows of solvent-saturated carrier gas, multiple simultaneous co-solvents and in-situ metrology. This new method is modular and applicable to a wide range of block copolymer and solvent systems. The control over annealing and quenching conditions afforded by this new technique allows us to reproducibly control the domain orientation and periodicity in thin films of cylinder-forming polystyrene-b-polyethylene oxide (PS-b-PEO) annealed in environments with high saturations of water and toluene vapors without modifying the block copolymer or substrate. By adjusting the humidity of the quenching gas flow we are able to control the orientation of the PEO cylinders, and by adjusting the humidity during annealing we are able to tune the domain spacing of PEO cylinders oriented perpendicular to the substrate.

Stahl, Brian C.; Kramer, Edward J.; Hawker, Craig J.

2012-02-01

295

AA Parametric Model for Predicting Relative Permeability-Saturation-Capillary Pressure Relationships of Oil?Water Systems in Porous Media with Mixed Wettability  

SciTech Connect

A parametric two-phase, oil-water relative permeability/capillary pressure model for petroleum engineering and environmental applications is developed for porous media in which the smaller pores are strongly water-wet and the larger pores tend to be intermediate- or oil-wet. A saturation index, which can vary from 0 to 1, is used to distinguish those pores that are strongly water-wet from those that have intermediate- or oil-wet characteristics. The capillary pressure submodel is capable of describing main-drainage and hysteretic saturation-path saturations for positive and negative oil-water capillary pressures. At high oil-water capillary pressures, an asymptote is approached as the water saturation approaches the residual water saturation. At low oil-water capillary pressures (i.e., negative), another asymptote is approached as the oil saturation approaches the residual oil saturation. Hysteresis in capillary pressure relations, including water entrapment, is modeled. Relative permeabilities are predicted using parameters that describe main drainage capillary pressure relations and accounting for how water and oil are distributed throughout the pore spaces of a porous medium with mixed wettability. The capillary pressure submodel is tested against published experimental data, and an example of how to use the relative permeability/capillary pressure model for a hypothetical saturation-path scenario involving several imbibition and drainage paths is given. Features of the model are also explained. Results suggest that the proposed model is capable of predicting relative permeability/capillary pressure characteristics of porous media mixed wettability.

Lenhard, Robert J.(INEEL) [INEEL; Oostrom, Mart (BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB)

1998-01-01

296

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

SciTech Connect

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.

Suuberg, E.M.

1993-12-31

297

Comparison of height-averaged and point-measured capillary pressure-saturation relations for sands using a modified Tempe cell  

NASA Astrophysics Data System (ADS)

Tempe cells and similar devices are often used for measurements of capillary pressure versus saturation relationships (retention curves) of soils. Average water saturation within the sample is often used as the representative saturation. For cases where the saturation distribution along the cell height is nonuniform, use of the height-averaged water saturation artificially smoothes the retention curve when the capillary pressure head reaches the displacement pressure head. This leads to an inaccurate representation of the retention curve in flow modeling. For nine test sands with a wide range of displacement pressure head values (6-78 cm of water), height-averaged and point-measured retention curves were simultaneously obtained to investigate the effect of the height-averaging procedure. A Tempe cell was used, which was modified by installing a small time domain reflectometry probe and a tensiometer at the midpoint of the sample height to measure water saturation and pressure, respectively. When the sample height is large relative to the displacement pressure head, the bulk drainage (initial drainage at the top of the sample) leads to inaccuracies in the determination of retention curves. For such cases, point-measured saturation should be used, otherwise height correction is necessary.

Sakaki, Toshihiro; Illangasekare, Tissa H.

2007-12-01

298

Vapor pressures and heats of vaporization of primary coal tars. Quarterly technical progress report, 1 January 1995--31 March 1995  

SciTech Connect

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. A significant amount of time has been devoted during this quarter to testing the equipment for measurements by the Knudsen effusion method. The basic technique was described in the 9th Quarterly Report how the performance of the apparatus was checked by measuring, as a function of temperature, the vapor pressures of anthracene between 25 and 130{degrees}C, pyrene between 35 and 125{degrees}C, and coronene between 145 and 235{degrees}C.

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

1995-08-01

299

Atmospheric Pressure Plasma Enhanced Chemical Vapor Deposition of Borophosphosilicate Glass Films  

NASA Astrophysics Data System (ADS)

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.

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

2008-03-01

300

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

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

301

Effects of Pressure and Partial Water Saturation on Gas Permeability in Tight Sands: Experimental Results  

Microsoft Academic Search

Effective permeability to gas with various degrees of brine saturation has been measured in the laboratory for several very tight sandstones from the Spirit River formation of Alberta, Canada. Gas permeability as low as 20x10⁻⁹ darcy was measured successfully with a pulse-decay permeameter with nitrogen as the mobile fluid. Results show that gas permeability depends very strongly on the degree

Joel Walls; Amos Nur; Thierry Bourbie

1982-01-01

302

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

SciTech Connect

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.

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

1994-10-01

303

Saturated liquid densities and bubble-point pressures of the binary HFC 152a+HCFC 142b system  

NASA Astrophysics Data System (ADS)

Forty-eight sets of the saturated liquid densities and bubble-point pressures of the binary HFC 152a + HCFC 142b system were measured with a magnetic densimeter coupled with a variable-volume cell. The measurements obtained at four compositions, 20, 40, 60, and 80 wt%, of HFC 152a cover a range of temperatures from 280 to 400 K. The experimental uncertainties in temperature, pressure, density, and composition were estimated to be within 15mK, 20kPa, 0.2%, and between -0.14 and 0.01 wt% HFC 152a (-0.01 and + 0.14 wt% HCFC 142b), respectively. The purities of the samples were 99.9 wt% for HFC 152a and 99.8 wt% for HCFC 142b. A binary interaction parameter, k ij , in the Peng-Robinson equation of state was determined as a function of temperature for representing the bubble-point pressures. On the other hand, two constant binary-interaction parameters, k ij and l ij , were introduced into the mixing rule of the Hankinson-Brobst-Thomson equation for representing the saturated liquid densities.

Maezawa, Y.; Widiatmo, J. V.; Sato, H.; Watanabe, K.

1991-11-01

304

Trends in odor intensity for human and electronic noses: Relative roles of odorant vapor pressure vs. molecularly specific odorant binding  

PubMed Central

Response data were collected for a carbon black-polymer composite electronic nose array during exposure to homologous series of alkanes and alcohols. The mean response intensity of the electronic nose detectors and the response intensity of the most strongly driven set of electronic nose detectors were essentially constant for members of a chemically homologous odorant series when the concentration of each odorant in the gas phase was maintained at a constant fraction of the odorants vapor pressure. A similar trend is observed in human odor detection threshold values for these same homologous series of odorants. Because the thermodynamic activity of an odorant at equilibrium in a sorbent phase is equal to the partial pressure of the odorant in the gas phase divided by the vapor pressure of the odorant and because the activity coefficients are similar within these homologous series of odorants for sorption of the vapors into specific polymer films, the data imply that the trends in detector response can be understood based on the thermodynamic tendency to establish a relatively constant concentration of sorbed odorant into each of the polymeric films of the electronic nose at a constant fraction of the odorants vapor pressure. Similarly, the data are consistent with the hypothesis that the odor detection thresholds observed in human psychophysical experiments for the odorants studied herein are driven predominantly by the similarity in odorant concentrations sorbed into the olfactory epithelium at a constant fraction of the odorants vapor pressure.

Doleman, Brett J.; Severin, Erik J.; Lewis, Nathan S.

1998-01-01

305

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

USGS Publications Warehouse

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.

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

2007-01-01

306

A unified equation for calculating methane vapor pressures in the CH 4-H 2O system with measured Raman shifts  

NASA Astrophysics Data System (ADS)

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 CH 4-H 2O 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 CH 4?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 CH 4-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.

Lu, Wanjun; Chou, I.-Ming; Burruss, R. C.; Song, Yucai

2007-08-01

307

Resonance fluorescence detection of mercury vapor in a supersonic jet  

Microsoft Academic Search

As resonance fluorescence at atmospheric pressure can be limited by collisional quenching and elastic scattering, supersonic jet spectroscopy is applied in this study to improve sensitivity for the detection of atomic mercury (Hg) vapor. The supersonic jet was produced by flowing argon test gas saturated with Hg vapor through a nozzle into a vacuum. The experiment used laser radiation at

Xiaomei Tong; Robert B. Barat; Arthur T. Poulos

2002-01-01

308

Characterization of Tantalum Pentoxide Dielectric Films Grown by Low-Pressure and Plasma-Enhanced Chemical Vapor Deposition  

Microsoft Academic Search

The material properties as well as the electrical behavior of tantalum pentoxide (Ta2O5) thin films prepared by low-pressure chemical vapor deposition (LPCVD) and plasma-enhanced chemical vapor deposition (PECVD), in the same reactor, were studied. Ta2O5 films were grown on Si and Pt substrates by reacting pentaethoxy tantalum [Ta(OC2H5)5] with oxygen and were annealed in an oxygen furnace at 700^\\\\circC or

Yi-Sheng Lai; Jen Sue Chen

2001-01-01

309

Equilibrium vapor pressures of the hydrogen getters DPB and DPPE. [1,4-diphenyl butadiene (DPB); 1,6-diphenoxy-2,4-hexadiyne (DPPE)  

Microsoft Academic Search

The equilibrium vapor pressure of two hydrogen getters 1,4-diphenyl butadiyne (DPB) and 1,6-diphenoxy-2, 4-hexadiyne (DPPE) have been determined in vacuum (approx. 10⁻⁷ Torr) in the temperature range 23 to 75°C by the Knudsen effusion technique. Vapor pressure values for these two getters have not been previously reported in the literature. In this study we have measured the vapor pressures of

C. A. Colmenares; R. G. Garza

1981-01-01

310

VAPORIZATION AND OXIDATION OF LIQUID FUEL DROPLETS AT HIGH TEMPERATURE AND HIGH PRESSURE: APPLICATION TO N-ALKANES AND VEGETABLE OIL METHYL ESTERS  

Microsoft Academic Search

Vaporization and oxidation of liquid fuel droplets are basic mechanisms in spray combustion for various industrial applications. In this work, coupled effects of temperature and pressure on n-alkane droplet vaporization are investigated in experiments conducted in a high-pressure and high-temperature gasification facility equipped with the fiber-suspended droplet technique. The influence of temperature and pressure on n-heptane and n-decane vaporization rates

CLINE MORIN; CHRISTIAN CHAUVEAU; PHILIPPE DAGAUT; ISKENDER GKALP; MICHEL CATHONNET

2004-01-01

311

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

NASA Astrophysics Data System (ADS)

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 7.510-5 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 3.710-4. Simultaneous measurements have provided us a lot of information on the microstructure of fluid-bearing rocks.

Higuchi, A.; Watanabe, T.

2013-12-01

312

Carbon vapor pressure in the range 3450 to 4500 K and evidence for melting at approximately 3800 K. Technical report  

SciTech Connect

The vapor pressure of carbon was determined over the temperature range 3470 to 4490 K by using a laser heating technique. The solid-liquid-vapor triple point was located at approximately 3800 K and a pressure of approximately 13,000 Pa, and the normal boiling point was found to be approximately 4140 K. Evidence for a solid-solid-vapor triple point was found at approximately 3560 K. Liquid carbon was produced in a free state, and some of its properties were determined. Superheated liquid carbon was produced at low pressure by using sufficient laser power. Spectroscopic methods were used to determine the carbon gas temperature and as a cross-check on the temperature determined by an optical pyrometer.

Whittaker, A.G.; Kintner, P.L.; Nelson, L.S.; Richardson, N.

1981-09-01

313

Vapor pressures and heats of sublimation of crystalline ?-cellobiose from classical molecular dynamics simulations with quantum mechanical corrections.  

PubMed

In this paper, we report the calculation of the enthalpy of sublimation, ?(sub)H, as a function of temperature of crystalline ?-cellobiose from molecular dynamics (MD) simulations, using two popular carbohydrate force fields. Together with the entropy difference between the solid and the vapor, ?S, evaluated at atmospheric pressure, ?(sub)H gives the vapor pressure of cellobiose over the solid phase as a function of T. It is found that when quantum mechanical corrections to the enthalpy calculated from the distribution of normal modes is applied both force fields give ?(sub)H close to experiments. The entropy change, ?S, which is calculated within a harmonic approximation becomes too small, leading to vapor pressures that are too low. These findings are relevant to MD simulations of crystalline carbohydrates in general, e.g., native cellulose. PMID:24784815

Wohlert, Jakob

2014-05-22

314

High-pressure vapor-liquid equilibria of two binary systems: Carbon dioxide + cyclohexanol and carbon dioxide + cyclohexanone  

SciTech Connect

Vapor-liquid equilibria for carbon dioxide + cyclohexanol and carbon dioxide + cyclohexanone were measured using an apparatus based on a static-analytic method with in situ samplings. P, T, x, y measurements were made at pressures up to 22 MPa. The carbon dioxide + cyclohexanol system was studied at 433 and 473 K, and carbon dioxide + cyclohexanone, at 433 and 473 K. The results are correlated by the Redlich-Kwong-Soave and Peng and Robinson equations and several mixing rules. The best fittings are obtained with the Peng-Robinson equation of state and a two-parameter mixing rule, i.e., within 1.1% for both pressures and vapor mole fractions on the carbon dioxide + cyclohexanone system and within 1.9% for pressures and 2.9% for vapor mole fractions on the carbon dioxide + cyclohexanol system. More recent equations by Patel and Teja and Salim and Trebble show no significant advantages.

Laugier, S. [Ecole Nationale Superieure de Chimie et Physique de Bordeaux, Talence (France)] [Ecole Nationale Superieure de Chimie et Physique de Bordeaux, Talence (France); Richon, D. [Ecole Nationale Superieure des Mines de Paris, Fontainebleau (France)] [Ecole Nationale Superieure des Mines de Paris, Fontainebleau (France)

1997-01-01

315

Evaluation of the electrode method for measuring H/sub 2/S vapor pressure over alkanolamine solutions  

SciTech Connect

A new electrode method for measuring the equilibrium vapor pressure of H/sub 2/S over any sulfide solution was tested. The method relates the electropotential difference produced between pH and silver/sulfide ion specific electrodes to the H/sub 2/S equilibrium vapor pressure of solution. The experimental technique is simple and time efficient. In this work, H/sub 2/S equilibrium vapor pressures were measured from 10/sup -4/ kPa to 10 kPa at 25/sup 0/C in aqueous solutions of monoethanolamine-MEA (2.5 N), diethanolamine-DEA (2.0N), and methyldiethanolamine-MDEA (1.0 N and 4.28 N). The H/sub 2/S vapor-liquid equilibria (VLE) of 4.28 N MDEA was also examined at 40/sup 0/C. The results indicate that the addition of MEA to a MDEA solution reduces the H/sub 2/S vapor pressure only at low H/sub 2/S loadings.

Austgen, D.M.; Rochelle, G.T.

1987-01-01

316

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

PubMed Central

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.

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

2014-01-01

317

Frictional behavior of diamondlike carbon films in vacuum and under varying water vapor pressure.  

SciTech Connect

In this study, we investigated the frictional behavior of both hydrogenated and hydrogen-free diamondlike carbon (DLC) films in high vacuum (10{sup -6} Pa) at room temperature. Water was also introduced into the vacuum chamber to elucidate its effects on DLC film tribology. The hydrogen-free DLC (also referred to as tetrahedral amorphous carbon, or ta-C) was produced by an arc-PVD process, and the highly hydrogenated DLC was produced by plasma-enhanced chemical-vapor deposition. Tribological measurements of these films were made with a pin-on-disc machine with coated steel balls and coated steel discs in matched pairs under a 1 N load. The ball/disk pairs were rotated at sliding speeds in the range of 0.025-0.075 m/s. In vacuum, the steady-state friction coefficient of ta-C was of the order of 0.6 and the wear was severe, whereas for the highly hydrogenated film, friction was below 0.01, and in an optical microscope no wear could be detected. Adding water vapor to the sliding ta-C system in a vacuum chamber caused friction to decrease monotonically from 0.6 to {approx}0.05. In contrast, adding water vapor to the sliding DLC system caused the friction to increase linearly with pressure from 0.01 to 0.07. The results illustrate the importance of taking into account environmental conditions, especially the presence of water, when DLC films are being considered for a given application.

Andersson, J.; Erck, R. A.; Erdemir, A.

2002-03-25

318

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

PubMed

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

Kaya, Murat; Volkan, Mrvet

2011-03-15

319

Synthesis of single phase cubic tin nitride nanoparticles by atmospheric pressure halide vapor phase epitaxy  

NASA Astrophysics Data System (ADS)

In this work tin nitride nanoparticles having controlled size have been synthesized by halide vapor phase epitaxy at atmospheric pressure. Tin nitride nanoparticles having three different sizes: 3 0.5 nm, 6 1.0 nm and 11 1.5 nm have been synthesized simultaneously in a single batch at different substrate temperatures by placing the substrate at different distances from the source. The depositions have been carried out on gold-coated silicon substrates using SnCl 45H 2O as the precursor, NH 3 as the nitrogen supplier and N 2 as the carrier gas. This is the first report on the synthesis of tin nitride in nanoparticle form.

Nand, Singh Vidya; Ankur, Khare; Brijesh, Kumar; Raj, Mehta Bodh

2008-05-01

320

Defect Characterization in Ge/(001)Si Epitaxial Films Grown by Reduced-Pressure Chemical Vapor Deposition  

NASA Astrophysics Data System (ADS)

We studied the microstructural characteristics and electrical properties of epitaxial Ge films grown on Si(001) substrates by x-ray diffraction, atomic force microscopy, and transmission electron microscopy. The films were grown using a two-step technique by reduced-pressure chemical vapor deposition, where the first step promotes two-dimensional growth at a lower substrate temperature. We observed a decrease in defect density with increasing film thickness. Ge films with thickness of 3.5 ?m exhibited threading dislocation densities of 5 106 cm-2, which yielded devices with dark current density of 5 mA cm-2 (1 V reverse bias). We also noted the presence of stacking faults in the form of lines in the films and establish that this is an important defect for Ge films grown by this deposition technique.

Bharathan, Jayesh; Narayan, Jagdish; Rozgonyi, George; Bulman, Gary E.

2013-10-01

321

Hollow-Cathode Based Electrical Discharge in Atmospheric Pressure Water Vapor at Wide Range of Temperature  

NASA Astrophysics Data System (ADS)

Atmospheric pressure water vapor, in the temperature range from 150 to 700 C, was used as the carrier gas for DC powered electrical discharge in hollow cathode configuration. The electrode assembly was constructed in usual hollow-cathode configuration by sandwiching a dielectric spacer, 200 ?m thick, with two thin metal sheets and boring a micro hole of 300 ?m diameter. The current-voltage profile of the discharge showed a positive differential resistivity characterizing an abnormal glow discharge. The power consumption for the water discharge at 700 C was less than 50% the consumption at 150 C. The reduction of the power for sustaining the discharge with increase of the gas temperature was partly explained by relating the ionic mobility and the distribution of ionic mean free path to the temperature.

Koo, Il Gyo; Lee, Woong Moo

2006-10-01

322

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

NASA Astrophysics Data System (ADS)

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.

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

2012-07-01

323

High-pressure vapor-liquid equilibria for mixtures containing a supercritical fluid  

SciTech Connect

Supercritical fluid extraction has been proven as an efficient separation method for some specific industrial applications. The knowledge of the phase behavior of supercritical systems plays an important role in the process design. High pressure vapor-liquid phase equilibrium compositions were measured for the binary systems of carbon dioxide + 2-methyl-1-pentanol, carbon dioxide + 1-octanol, and carbon dioxide + 1-decanol over a temperature range between 348.15 and 453.15 K. In addition to the new data, a variety of supercritical fluid systems was used to test the validity of the Peng-Robinson and Patel-Teja equations of state accompanied by several types of mixing rules. In general, the Peng-Robinson equation incorporated with the cubic mixing rule yielded the best representation.

Weng, W.L. (Ming-Hsin Engineering College, Hsinchu (Taiwan, Province of China). Dept. of Chemical Engineering); Chen, J.T.; Lee, M.J. (National Taiwan Inst. of Technology, Taipei (Taiwan, Province of China). Dept. of Chemical Engineering)

1994-08-01

324

High-pressure vapor-liquid equilibrium for R-22 + ethanol and R-22 + ethanol + water  

SciTech Connect

High-pressure vapor-liquid equilibrium (VLE) data for the systems CO{sub 2} + methanol at 313.05 K, CO{sub 2} + ethanol at 323.55, 325.15, and 333.35 K, R-22 (chlorodifluoromethane) + ethanol at 343.25, 361.45, and 382.45 K, and R-22 + ethanol + water at 351.55, 362.65, and 371.85 K are obtained using a circulation-type VLE apparatus. The apparatus is tested with measurements of the CO{sub 2} + methanol and CO{sub 2} + ethanol systems. The experimental data are correlated using the Peng-Robinson and Elliott-Suresh-Donohue equations of state.

Elbaccouch, M.M.; Raymond, M.B.; Elliott, J.R.

2000-04-01

325

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

NASA Technical Reports Server (NTRS)

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).

Zwillenberg, M. L.

1975-01-01

326

Generalization of vapor pressure lowering effects in an existing geothermal simulator  

SciTech Connect

Thermodynamic properties of pore water are shown to be different from those of bulk water because of interfacial forces between the aqueous and solid phases. This {open_quotes}vapor-pressure lowering{close_quotes} (VPL) effect is described through Kelvin`s equation, which relates VPL to properties of the liquid phase. An algorithm that accounts for VPL had previously been implented in the geothermal simulator TETRAD. This algorithm applies to a narrow range of reservoir properties, and in some cases leads in inconsistencies. This report presents a generalization of the VPL algorithm which removes many of its limitations. The governing equations for the generalization are presented, assumptions and limitations of the method are discussed, and the modifications are validated.

Shook, G.M.

1993-06-01

327

Analysis of mass transport in an atmospheric pressure remote plasma-enhanced chemical vapor deposition process  

SciTech Connect

In remote microwave plasma enhanced chemical vapor deposition processes operated at atmospheric pressure, high deposition rates are associated with the localization of precursors on the treated surface. We show that mass transport can be advantageously ensured by convection for the heavier precursor, the lighter being driven by turbulent diffusion toward the surface. Transport by laminar diffusion is negligible. The use of high flow rates is mandatory to have a good mixing of species. The use of an injection nozzle with micrometer-sized hole enables us to define accurately the reaction area between the reactive species. The localization of the flow leads to high deposition rates by confining the reactive species over a small area, the deposition yield being therefore very high. Increasing the temperature modifies nonlinearly the deposition rates and the coating properties.

Cardoso, R. P.; Belmonte, T.; Henrion, G.; Gries, T. [Department of Chemistry and Physics of Solids and Surfaces, Institut Jean Lamour, Nancy-Universite, CNRS, Parc de Saurupt, CS 14234, F-54042 Nancy Cedex (France); Tixhon, E. [AGC Flat Coating, 2 Rue de l'aurore, B-6040 Jumet (Belgium)

2010-01-15

328

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

SciTech Connect

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).

Butters, R.A.

1990-09-30

329

The Vapor Pressure of Palladium at Temperatures up to 1973K  

NASA Technical Reports Server (NTRS)

Understanding high-temperature processes is imperative for modeling the formation of the solar system. It is unfortunate that since the 1950 s little has been done in the area of thermodynamics to continue gaining information on metals such as iron (Fe), nickel (Ni), cobalt (Co), palladium (Pd) and many others. Although the vapor pressures of these metals can be extrapolated to higher temperatures, the data is often limited to temperature ranges too low to be applicable to processes that occur during the formation of the solar system (T approx. 2000K). Experimental techniques inhibited the data in the past by restricting the testing of metals to temperatures below their melting point. Today, higher temperature testing is possible by using a Thermo- Cahn Thermogravimetric system that is able to reach temperatures up to 1973K in vacuo and measure a 10 gram change in a sample with mass of up to 100 grams.

Gardner, K. G.; Feguson, F. T.; Nuth, J. A.

2005-01-01

330

Assessment of vapor pressure estimation methods for secondary organic aerosol modeling  

NASA Astrophysics Data System (ADS)

Vapor pressure ( Pvap) is a fundamental property controlling the gas-particle partitioning of organic species. Therefore this pure substance property is a critical parameter for modeling the formation of secondary organic aerosols (SOA). Structure-property relationships are needed to estimate Pvap because (i) very few experimental data for Pvap are available for semi-volatile organics and (ii) the number of contributors to SOA is extremely large. The Lee and Kesler method, a modified form of the Mackay equation, the Myrdal and Yalkowsky method and the UNIFAC- pLo method are commonly used to estimate Pvap in gas-particle partitioning models. The objectives of this study are (i) to assess the accuracy of these four methods on a large experimental database selected to be representative of SOA contributors and (ii) to compare the estimates provided by the various methods for compounds detected in the aerosol phase.

Camredon, Marie; Aumont, Bernard

331

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

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

332

Identification of reaction products in the low-pressure chemical vapor deposition of molybdenum silicide  

SciTech Connect

The gaseous species produced by low-pressure chemical vapor deposition of molybdenum silicide in a cold wall reactor were identified by mass spectroscopy. Lowering the ionizing electron energy made possible the unambiguous assignment of the mass spectra to individual species and also permitted useful quantitative estimates to be made. Thermodynamic calculations using the computer program SOLGASMIX were carried out on the M-Si-H-F (M = Mo, W) quaternary system. Both experiment and calculation indicate that the fluorosilanes were the major gaseous reaction by-products, with SiHF{sub 3} being the most abundant for the experimental conditions investigated here. The changes in the process with substrate temperature were also investigated and are discussed with reference to both thermodynamic and kinetic effects.

Gaczi, P.J.; Reynolds, G.J. (Varian Research Center, Palo Alto, CA (US))

1989-09-01

333

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

PubMed Central

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.

Fu, Jinxia; Suuberg, Eric M.

2012-01-01

334

Fracture toughness of low-pressure chemical-vapor-deposited polycrystalline silicon carbide thin films  

NASA Astrophysics Data System (ADS)

The fracture toughness of thin-film polycrystalline silicon carbide (poly-SiC) deposited on silicon (Si) wafers via low-pressure chemical-vapor deposition (LPCVD) has been measured on a scale useful for micromachined devices; the results are compared to previous studies on poly-SiC thin films deposited by atmospheric pressure chemical-vapor deposition (APCVD) [Bellante et al., Appl. Phys. Lett. 86, 071920 (2005)]. Samples in this study included those with and without silicon dioxide (SiO2) sacrificial release layers. The LPCVD processing technique induces residual tensile stresses in the films. Doubly clamped microtensile specimens were fabricated using standard micromachining processes, and microindentation was used to initiate atomically sharp precracks. The residual stresses in the films create stress intensity factors K at the crack tips; upon release, the precracks whose K exceeded a critical value, KIC, propagated to failure. The fracture toughness KIC was the same for both types of devices, 2.9+/-0.2 MPa m1/2 for the SiC on Si samples and 3.0+/-0.2 MPa m1/2 for the SiC on SiO2/Si samples, and similar to that found for APCVD poly-SiC, 2.8<=KIC<=3.4 MPa m1/2 [Bellante et al., Appl. Phys. Lett. 86, 071920 (2005)], indicating that KIC is truly a structure-insensitive material property. The fracture toughness of poly-SiC compares favorably with that for polysilicon, 0.85+/-0.05 MPa m1/2 [Kahn et al., Science 298, 1215 (2002)].

Hatty, V.; Kahn, H.; Trevino, J.; Zorman, C. A.; Mehregany, M.; Ballarini, R.; Heuer, A. H.

2006-01-01

335

Dynamic Effect in the Capillary Pressure-Saturation Relationship and its Impacts on Unsaturated Flow  

Microsoft Academic Search

7 kg (or dry) soil sample, then the capillary pressure is in- (m s) 1 . In addition, recently developed pore-scale models that simu- late interface dynamics within a network of pores can also be used creased (or decreased) incrementally, and at each step to estimate the appropriate dynamic coefficients. Analyses of experi- the water content is measured after equilibrium

S. Majid Hassanizadeh; Michael A. Celia; Helge K. Dahle

2002-01-01

336

Organic Dye Effects on DNAPL Entry Pressure in Water Saturated Porous Media  

Microsoft Academic Search

One of three diazo dyes with the same fundamental structure have been used in most studies of DNAPL behavior in porous media to stain the NAPL: Sudan III, Sudan IV, or Oil-Red-O. The dyes are generally implicitly assumed to not influence DNAPL behavior. That assumption was tested using simple entry pressure experiments.

2001-01-01

337

Saturation effects in the laser ablation of stainless steel in air at atmospheric pressure  

Microsoft Academic Search

A pulsed Nd?:?YAG laser was used to generate a plasma from stainless steel targets in air at atmospheric pressure. Laser\\u000a focusing was found to be an important factor in the ablation process. The influence of focal conditions on spatial profiles\\u000a of plasma, emission intensity and averaged ablation rate (AAR, ?m pulse1) of stainless steel samples as a function of laser

L. M. Cabaln; D. Romero; J. M. Baena; J. J. Laserna

1999-01-01

338

Gain and saturation energy measurements in low pressure longitudinally excited N 2-lasers  

Microsoft Academic Search

A flat-plate Blumlein circuit has been used for operating a low pressure longitudinally excited oscillatoramplifier N2-laser at 14 kV input voltage (LELE type). For investigating the effect of the excitation length on the laser performances, various amplifiers made of glass tubes of different lengths ranging from 15.5 to 35 cm with 4 mm inner bore diameters have been used. The

S. Ghoreyshi; K. Rahimian; Akbar Hariri

2004-01-01

339

The Effect of Films on the Capillary Pressure - Saturation Hysteresis in a Smooth-walled Wedge Channel  

NASA Astrophysics Data System (ADS)


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).

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

2010-12-01

340

Complementary vapor pressure data for 2-methyl-1-propanol and 3-methyl-1-butanol at a pressure range of (15 to 177) kPa  

Microsoft Academic Search

The vapor pressure of pure 2-methyl-1-propanol and 3-methyl-1-butanol, components called congeners that are present in aroma of wine, pisco, and other alcoholic beverages, were measured with a dynamic recirculation apparatus at a pressure range of (15 to 177)kPa with an estimated uncertainty <0.2%. The measurements were performed at temperature ranges of (337 to 392)K for 2-methyl-1-propanol and (358 to 422)K

Arturo Bejarano; Nathalie Quezada; Juan C. de la Fuente

2009-01-01

341

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

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

W. Benzinger; K. J. Httinger

1998-01-01

342

Simple Methods for Calculation of Liquid-Vapor Equilibria under Pressure.  

National Technical Information Service (NTIS)

Liquid-vapor equilibria are studied by a generalization of Soave and Peng-Robinson methods. These methods are tested with petroleum fluids: hydrocarbons, carbon dioxide, nitrogen, and hydrogen sulfide. Estimations are correct for liquid-vapor equilibria b...

E. Rauzy

1982-01-01

343

A Theoretical Approach Representing Hysteresis in Capillary Pressure-Saturation Relationship Based on Connectivity in Void Space  

NASA Astrophysics Data System (ADS)

This study presents a new theoretical model for description of hysteretic constitutive relationships between capillary pressure and saturation under capillary-dominated multiphase flow conditions in porous media. Hysteretic relationships are required for the accurate prediction of the spatial and temporal distribution of multiphase fluids in response to successively occurring drainage and imbibition events in porous media. In addition to contact angle effects, the connectivity of the void space in the porous medium plays a central role for the macroscopic manifestation of hysteresis behavior and capillary entrapment of wetting and non-wetting fluids. The hysteretic constitutive model developed in this work uses void-size distribution and a measure of connectivity of void space to compute the hysteretic curves and to predict entrapped fluid phase saturations. Two functions, the probability of drainage and the probability of wetting, are introduced to characterize connectivity of fluids in void space during drainage and wetting processes. These functions can be estimated through pore-scale simulations in computer-generated porous media or from traditional experimental measurements of primary drainage and main wetting curves. The hysteresis model results are verified by comparing the model predicted scanning curves with 3D pore-scale simulations as well as with actual data sets obtained from column experiments found in the literature.

Cihan, A.; Birkholzer, J. T.; Illangasekare, T. H.; Zhou, Q.

2013-12-01

344

High-pressure vapor-liquid equilibria involving mixtures of nitrogen, carbon dioxide, and eta-butane  

Microsoft Academic Search

A new high-pressure vapor-liquid equilibrium apparatus has been constructed with the capability of measuring the compositions and densities of the coexisting equilibrium phases at constant temperature and\\/or pressure. This apparatus was tested with the carbon dioxide + n-butane system with excellent agreement observed between our results and previously published data. Data are also reported for the nitrogen + n-butane system

Steven K. Shibata; Stanley I. Sandler

1989-01-01

345

Alkali metal vapor removal from pressurized fluidized-bed combustor flue gas. Annual report, October 1982September 1983  

Microsoft Academic Search

Under the auspices of US Department of Energy, this work supports the program to develop sorbents for the cleanup of gases from pressurized fluidized-bed coal combustion (PFBC) so that these cleaned hot gases can be used to power downstream gas turbines without causing corrosion. A laboratory-scale pressurized test unit was used to continue the alkali-vapor characterization of activated bauxite and

S. H. D. Lee; K. M. Myles; A. A. Jonke

1984-01-01

346

Atmospheric-Pressure Chemical Vapor Deposition of Iron Pyrite Thin Films  

SciTech Connect

Iron pyrite (cubic FeS{sub 2}) is a promising candidate absorber material for earth-abundant thin-film solar cells. In this report, single-phase, large-grain, and uniform polycrystalline pyrite thin films are fabricated on glass and molybdenum-coated glass substrates by atmospheric-pressure chemical vapor deposition (AP-CVD) using the reaction of iron(III) acetylacetonate and tert-butyl disulfide in argon at 300 C, followed by sulfur annealing at 500--550 C to convert marcasite impurities to pyrite. The pyrite-marcasite phase composition depends strongly on the concentration of sodium in the growth substrate and the sulfur partial pressure during annealing. Phase and elemental composition of the films are characterized by X-ray diffraction, Raman spectroscopy, Auger electron spectroscopy, secondary ion mass spectrometry, Rutherford backscattering spectrometry, and X-ray photoelectron spectroscopy. The in-plane electrical properties are surprisingly insensitive to phase and elemental impurities, with all films showing p-type, thermally activated transport with a small activation energy ({approx}30 meV), a room- temperature resistivity of {approx}1 {Omega} cm, and low mobility. These ubiquitous electrical properties may result from robust surface effects. These CVD pyrite thin films are well suited to fundamental electrical studies and the fabrication of pyrite photovoltaic device stacks.

Berry, Nicholas; Cheng, Ming; Perkins, Craig L.; Limpinsel, Moritz; Hemminger, John C.; Law, Matt (NREL); (UCI)

2012-10-23

347

Determination of octane numbers and Reid vapor pressure in commercial gasoline using dispersive fiber-optic Raman spectroscopy  

Microsoft Academic Search

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,

Philip E. Flecher; William T. Welch; Sacharia Albin; John B. Cooper

1997-01-01

348

High-pressure vapor-liquid equilibria for propane + 2-butanol, propylene + 2-butanol, and propane + 2-butanol + 2-propanol  

Microsoft Academic Search

The use of dual effect solvents (near critical extractant and high-pressure water entrainer), for the recovery and dehydration of alcohols from dilute aqueous solutions, has been proposed by Brignole et al. (1987). The present work is part of an experimental program undertaken to confirm the applicability of light hydrocarbons for this separation problem. Vapor-liquid equilibria have been measured for propane

Hernn P. Gros; Marcelo S. Zabaloy; Esteban A. Brignole

1996-01-01

349

The effect of vapor pressure on stomatal control of gas exchange in Douglas fir ( Pseudotsuga menziesii ) saplings  

Microsoft Academic Search

Increasing leaf to air vapor pressure deficit (VPD) caused reductions in stomatal conductance of both current year and previous season needles of Pseudotsuga menziesii saplings. The stomata of current year needles were found to be more responsive to changes in VPD than those of previous season needles. The reductions in stomatal conductance of current year needles were not associated with

Frederick C. Meinzer

1982-01-01

350

VAPOR PRESSURE OF ALKALI METALS. RUBIDIUM, CESIUM, AND SODIUM-POTASSIUM ALLOY (NaK) UP TO 100 PSI  

Microsoft Academic Search

The vapor pressures of high-purity cesium, rubidium, and NaK (sodium--; potassium alloy) of 30.6 wt % sodium were measured from roughly 1 to 100 lb psi ; abs. The method employed boiling under argon, in a small capsule to ensure ; temperature uniformity. Recent independert results by others on sodium, in close ; agreement with earlier sodium data obtained with

C. F. Bonilla; D. L. Sawhney; M. M. Makansi

1962-01-01

351

Vapor pressures of pure compounds using the PengRobinson equation of state with three different attractive terms  

Microsoft Academic Search

Accurate representation of pure compounds vapor pressures is required to increase the robustness of equations of state when predicting phase equilibria for mixtures. Using cubic equations of state, this representation largely depends on improving the temperature-dependent attractive term of the equation of state (EOS) to cover data from the triple to critical points. With this purpose, the PengRobinson equation of

Otilio Hernndez-Garduza; Fernando Garc??a-Snchez; David pam-Mart??nez; Richart Vzquez-Romn

2002-01-01

352

The separation and characterization of a hydrogen getter product mixture: Part 2, measurement of product vapor pressures  

Microsoft Academic Search

HCPB is the acronym of an organic hydrogen getter compound used in weapon systems. When this material scavenges hydrogen by reacting with it, a number of compounds are formed, each of which is more volatile than HCPB. It is desirable to know the vapor pressure of these products in order to assess their migration potential within the weapon. In this

D. W. Fircish; T. R. Shell

1987-01-01

353

A Convenient, Inexpensive, and Environmentally Friendly Method of Measuring the Vapor Pressure of a Liquid as a Function of Temperature  

Microsoft Academic Search

The popular experiment in which students measure the vapor pressure of a liquid as a function of temperature has been modified by introducing the use of a hand-held vacuum pump. This inexpensive modification not only eliminates the need to use mercury manometers and water aspirators, but it also makes the experimental apparatus much simpler and allows more data points to

James H. Burness

1996-01-01

354

Modeling of high-pressure vaporliquid equilibrium in ionic liquids + gas systems using the PRSV equation of state  

Microsoft Academic Search

Ionic liquids are environmentally friendly solvents composed of large organic cations and relatively small inorganic anions, whose melting point is below T=373.15K. This is an arbitrary limit defined in order to organize the dramatically increasing number of possible applications in chemical processes. These compounds are regarded as potentially environmentally benign solvents due to their almost negligible vapor pressure, which essentially

Pedro F. Arce; P. Adrin Robles; Tefilo A. Graber; Martn Aznar

2010-01-01

355

Comparison of Deposition Characteristics between Triethyl and Trimethyl Borates in an Atmospheric Pressure Chemical Vapor Deposition Equipment with Tetraethyl Orthosilicate and O3  

NASA Astrophysics Data System (ADS)

The deposition characteristics of triethyl borate (TEB) and trimethyl borate (TMB) vapors are compared to investigate of boron concentration uniformity and profiles in borophosphosilicate glass (BPSG) films. Film deposition is carried out in an atmospheric pressure equipment with tetraethyl orthosilicate (TEOS) and ozone (O3) under at standard condition and four process parameters are varied around the standard condition. Uniformity values obtained with the TMB vapor at a bubbling temperature of 10C are one-third that with the TEB vapor at the same bubbling temperature, and uniformity changes due to process parameter variations from the standard condition with the TMB vapor are also smaller since the TEB vapor is cleaved by O3 at lower temperature. These results indicate that the deposition characteristics for uniformity using TMB vapor are much better. However, a decrease in the boron concentration profile in films with the TMB vapor is observed between a silicon and silicon-dioxide interface. This decrease is estimated to be due to the fact that TMB bubbling N2 flow rate to suppress the vaporization rate with TMB's higher vapor pressure is one order of magnitude lower than TEB bubbling N2 flow rate. Suppression of TMB vapor to a desired vapor pressure was achieved by cooling the TMB bubbler at -25C. Then, a uniform profile of the TMB vapor was obtained, which was equivalent to the results at 10C.

Yamamoto, Yoshito; Ikakura, Hiroshi; Ohgawara, Shoji; Furukawa, Masakazu

1999-09-01

356

Correlation and prediction of physical properties of hydrocarbons with the modified Peng-Robinson equation of state 1. Low and medium vapor pressures  

Microsoft Academic Search

A modified version of the Peng-Robinson equation of state is proposed for representing vapor pressure data on compounds currently encountered in petroleum fractions. The proposed equation is valid from the triple point up to 2-3 bar. When one parameter is adjusted using experimental data, a very accurate representation of vapor pressures is obtained, with an overall average absolute deviation of

B. Carrier; M. Rogalski; A. Peneloux

1988-01-01

357

First experimental determination of the absolute gas-phase rate coefficient for the reaction of OH with 4-hydroxy-2-butanone (4H2B) at 294 K by vapor pressure measurements of 4H2B.  

PubMed

The reaction of the OH radicals with 4-hydroxy-2-butanone was investigated in the gas phase using an absolute rate method at room temperature and over the pressure range 10-330 Torr in He and air as diluent gases. The rate coefficients were measured using pulsed laser photolysis (PLP) of H(2)O(2) to produce OH and laser induced fluorescence (LIF) to measure the OH temporal profile. An average value of (4.8 1.2) 10(-12) cm(3) molecule(-1) s(-1) was obtained. The OH quantum yield following the 266 nm pulsed laser photolysis of 4-hydroxy-2-butanone was measured for the first time and found to be about 0.3%. The investigated kinetic study required accurate measurements of the vapor pressure of 4-hydroxy-2-butanone, which was measured using a static apparatus. The vapor pressure was found to range from 0.056 to 7.11 Torr between 254 and 323 K. This work provides the first absolute rate coefficients for the reaction of 4-hydroxy-2-butanone with OH and the first experimental saturated vapor pressures of the studied compound below 311 K. The obtained results are compared to those of the literature and the effects of the experimental conditions on the reactivity are examined. The calculated tropospheric lifetime obtained in this work suggests that once emitted into the atmosphere, 4H2B may contribute to the photochemical pollution in a local or regional scale. PMID:23210721

El Dib, Gisle; Sleiman, Chantal; Canosa, Andr; Travers, Daniel; Courbe, Jonathan; Sawaya, Terufat; Mokbel, Ilham; Chakir, Abdelkhaleq

2013-01-10

358

A method for measuring vapor pressures of low-volatility organic aerosol compounds using a thermal desorption particle beam mass spectrometer.  

PubMed

A temperature-programmed thermal desorption method for measuring vapor pressures of low-volatility organic aerosol compounds has been developed. The technique employs a thermal desorption particle beam mass spectrometer we have recently developed for real-time composition analysis of organic aerosols. Particles are size selected using a differential mobility analyzer, sampled into a high-vacuum chamber as an aerodynamically focused beam, collected by impaction on a cryogenically cooled surface, slowly vaporized by resistive heating, and analyzed in a quadrupole mass spectrometer. A simple evaporation model developed from the kinetic theory of gases is used to calculate compound vapor pressures over the temperature range of evaporation. The data are fit to a Clausius-Clapeyron equation to obtain a relationship between vapor pressure and temperature and to determine the heat of vaporization. The technique has been evaluated using C13-C18 monocarboxylic and C6-C8 dicarboxylic acids, which have vapor pressures at 25 degrees C of approximately 10(-4) - 10(-6) Pa, but less volatile compounds can also be analyzed. The method is relatively simple and rapid and yields vapor pressures and heats of vaporization that are in good agreement with literature values. The technique will be used to generate a new database of vapor pressures for low-volatility atmospheric organic compounds. PMID:11534699

Chattopadhyay, S; Tobias, H J; Ziemann, P J

2001-08-15

359

Differential equations governing slip-induced pore-pressure fluctuations in a water-saturated granular medium  

USGS Publications Warehouse

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.

Iverson, R. M.

1993-01-01

360

Prediction of vapor-liquid equilibria at high pressures using activity coefficient parameters obtained from low-pressure data: A comparison of two equation of state mixing rules  

SciTech Connect

Two recent equation of state mixing rules, one by Dahl and Michelsen (MHV2) and another by Wong and Sandler (W-S), are claimed to be useful for making vapor-liquid equilibrium predictions for nonideal mixtures at high temperatures and pressures using data obtained at low pressures. Here the authors compare the performance of these two mixing rules in predicting the high-pressure phase behavior of nine binary systems using published activity coefficient parameters. They also compare the predictions for two ternary systems using mixing rule parameters obtained from low-pressure binary mixture data. They find that both mixing rules can be used to make reasonable high-pressure vapor-liquid equilibrium predictions from low-pressure data. However, the errors in the predicted pressure with the W-S mixing rule when used with either the Peng-Robinson or Soave-Redlich-Kwong equation of state are, on the average, about half or less those obtained when using the MHV2 mixing rule. Also, the predictions of the MHV2 mixing rule deteriorate significantly as the temperature and pressure range increase, which is not the case with the W-S mixing rule.

Huang, Hai; Sandler, S.I. (Univ. of Delaware, Newark (United States). Dept. of Chemical Engineering)

1993-07-01

361

Mercury vapor pressure of flue gas desulfurization scrubber suspensions: effects of pH level, gypsum, and iron.  

PubMed

Calcium-based scrubbers designed to absorb HCl and SO(2) from flue gases can also remove oxidized mercury. Dissolved mercury halides may have an appreciable partial vapor pressure. Chemical reduction of the dissolved mercury may increase the Hg emission, thereby limiting the coremoval of mercury in the wet scrubbing process. In this paper we evaluate the effects of the pH level, different gypsum qualities, and iron in flue gas desulfurization (FGD) scrubber suspensions. The impact of these parameters on mercury vapor pressure was studied under controlled laboratory conditions in model scrubber suspensions. A major influence is exerted by pH values above 7, considerably amplifying the mercury concentration in the vapor phase above the FGD scrubber suspension. Gypsum also increases the mercury re-emission. Fe(III) decreases and Fe(II) increases the vapor pressure significantly. The consequences of the findings for a reliable coremoval of mercury in FGD scrubbers are discussed. It is shown that there is an increased risk of poor mercury capture in lime-based FGD scrubbers in comparison to limestone FGD scrubbers. PMID:22324514

Schuetze, Jan; Kunth, Daniel; Weissbach, Sven; Koeser, Heinz

2012-03-01

362

Vaporization of sediments with a pulsed transverse excitation at atmospheric pressure (TEA) CO/sub 2/ laser system  

SciTech Connect

A transverse excitation at atmospheric pressure (TEA) pulsed CO/sub 2/ laser equipped with an adjunct called a Lasertrace has been used to generate vapor and/or particulates from sediment samples. The material thus obtained can be transferred to analytical systems for analysis making possible the analysis of solids by techniques previously suitable only for liquids or gases. Approximately one milligram of vapor and/or particulates was obtained in a short period of time by this method, suitable for transport to other systems.

Smyrl, N.R.; King, H.G. Jr.

1981-12-31

363

Exchange of Na+ and K+ between water vapor and feldspar phases at high temperature and low vapor pressure  

USGS Publications Warehouse

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.

Fournier, R. O.

1976-01-01

364

Atmospheric Pressure Spray Chemical Vapor Deposited CuInS2 Thin Films for Photovoltaic Applications  

NASA Technical Reports Server (NTRS)

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.

Harris, J. D.; Raffaelle, R. P.; Banger, K. K.; Smith, M. A.; Scheiman, D. A.; Hepp, A. F.

2002-01-01

365

Synthesis of phosphorous-doped graphene by ambient pressure chemical vapor deposition  

NASA Astrophysics Data System (ADS)

Although theoretical calculations have demonstrated that phosphorous (P) doping of graphene could open the largest band gap and could possess excellent properties to become an ideal toxic gas sensor, it has not been synthesized experimentally. We have successfully synthesized large-area, monolayered P-doped graphene by an ambient pressure chemical vapor deposition (AP-CVD). In particular, triphenyl phosphene (TPP) dissolved in hexane with different concentrations of TPP has been used as phosphorous-carbon precursor. Raman spectroscopy is used extensively for characterizing the different synthesized materials. The intensity ratio of D, D', 2D and G bands and their associated shifts provide information related the nature and doping levels. The strong D-band and a prominent D'-band confirms the occurrence of doping by P-substitution. The doped graphene sheets have also been characterized by high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). In addition, results on the use of these P-doped graphene in molecular sensing will be discussed.

Ghosh, Anupama; Lv, Ruitao; Perera Lopez, Nestor; Berkdemir, Ayse; Elas, Ana Laura; Terrones, Humberto; Terrones, Mauricio

2013-03-01

366

As-deposited low-strain LPCVD (low-pressure, chemical-vapor-deposition) polysilicon  

SciTech Connect

As-deposited polysilicon films with very low residual strain (lower than 5 x 10/sup -5/) are obtained by a low-pressure, chemical-vapor-deposition (LPCVD) process. Straight polysilicon bridges 300 ..mu..m long, 1.2 ..mu..m thick, and 2 to 20 ..mu..m wide, made using this process. No buckling has been observed in any of the nearly one thousand bridges of this type made in two separate process runs. In addition, no problems of sticking between the bridges and the substrate were encountered with these structures. The polysilicon films from which the beams were fabricated were deposited by pyrolyzing silane at 605/degree/C on a phosphosilicate-glass (PSG) layer (8 wt % P). The PSG layer serves as a sacrificial layer to be subsequently etched away to free the bridge. Our research is aimed at obtaining an understanding of these relationships through consideration of the role of interfacial stresses and the kinetics of initial crystalline nucleation. The technique for producing these low-strain films is significant, however, because no high-temperature annealing steps are required to produce them. 4 refs., 4 figs.

Fan, L.S.; Muller, R.S.

1988-08-01

367

Beer Law Constants and Vapor Pressures of HgI2 over HgI2(s,l)  

NASA Technical Reports Server (NTRS)

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.

Su, Ching-Hua; Zhu, Shen; Ramachandran, N.; Burger, A.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

368

Characteristics of low vapor pressure oil ignition developed with irradiation of mega hertz level ultrasonic  

Microsoft Academic Search

In liquid fuel vaporizing type combustor for civil use, large amount of the electric power is consumed in pre-heating of fuel vaporizer during a standby period. Reduction of consumed power in pre-heating is regarded as important to develop a performance of the vaporizing type combustor from the viewpoint of energy saving. We proposed the oil combustion system using the MHz-ultrasonic

Takuya Fuse; Yasuki Hirota; Noriyuki Kobayashi; Masanobu Hasatani; Yoshio Tanaka

2004-01-01

369

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

Code of Federal Regulations, 2010 CFR

... (b)(1) After each pressure release, the pressure relief device...than 5 calendar days after each pressure release, except as provided in § 61...than 5 calendar days after the pressure release, the pressure relief...

2009-07-01

370

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

Code of Federal Regulations, 2010 CFR

... (b)(1) After each pressure release, the pressure relief device...than 5 calendar days after each pressure release, except as provided in § 61...than 5 calendar days after the pressure release, the pressure relief...

2010-07-01

371

40 CFR 60.482-4 - Standards: Pressure relief devices in gas/vapor service.  

Code of Federal Regulations, 2010 CFR

... (b)(1) After each pressure release, the pressure relief device...than 5 calendar days after the pressure release, except as provided in § 60...than 5 calendar days after the pressure release, the pressure relief...

2010-07-01

372

Control of Photosynthesis and Stomatal Conductance in Ricinus communis L. (Castor Bean) by Leaf to Air Vapor Pressure Deficit 1  

PubMed Central

Castor bean (Ricinus communis L.) has a high photosynthetic capacity under high humidity and a pronounced sensitivity of photosynthesis to high water vapor pressure deficit (VPD). The sensitivity of photosynthesis to varying VPD was analyzed by measuring CO2 assimilation, stomatal conductance (gs), quantum yield of photosystem II (?II), and nonphotochemical quenching of chlorophyll fluorescence (qN) under different VPD. Under both medium (1000) and high (1800 micromoles quanta per square meter per second) light intensities, CO2 assimilation decreased as the VPD between the leaf and the air around the leaf increased. The gs initially dropped rapidly with increasing VPD and then showed a slower decrease above a VPD of 10 to 20 millibars. Over a temperature range from 20 to 40C, CO2 assimilation and gs were inhibited by high VPD (20 millibars). However, the rate of transpiration increased with increasing temperature at either low or high VPD due to an increase in gs. The relative inhibition of photosynthesis under photorespiring (atmospheric levels of CO2 and O2) versus nonphotorespiring (700 microbars CO2 and 2% O2) conditions was greater under high VPD (30 millibars) than under low VPD (3 millibars). Also, with increasing light intensity the relative inhibition of photosynthesis by O2 increased under high VPD, but decreased under low VPD. The effect of high VPD on photosynthesis under various conditions could not be totally accounted for by the decrease in the intercellular CO2 in the leaf (Ci) where Ci was estimated from gas exchange measurements. However, estimates of Ci from measurements of ?II and qN suggest that the decrease in photosynthesis and increase in photorespiration under high VPD can be totally accounted for by stomatal closure and a decrease in Ci. The results also suggest that nonuniform closure of stomata may occur in well-watered plants under high VPD, causing overestimates in the calculation of Ci from gas exchange measurements. Under low VPD, 30C, high light, and saturating CO2, castor bean (C3 tropical shrub) has a rate of photosynthesis (61 micromoles CO2 per square meter per second) that is about 50% higher than that of tobacco (C3) or maize (C4) under the same conditions. The chlorophyll content, total soluble protein, and ribulose-1,5-bisphosphate carboxylase/oxygenase level on a leaf area basis were much higher in castor bean than in maize or tobacco, which accounts for its high rates of photosynthesis under low VPD.

Dai, Ziyu; Edwards, Gerald E.; Ku, Maurice S. B.

1992-01-01

373

Structure-property relationships of (C-O-H)-saturated silicate melt coexisting with silicate-saturated C-O-H fluid at high temperature and pressure and with variable redox conditions  

NASA Astrophysics Data System (ADS)

The solubility and solution mechanisms in silicate melts of C-O-H volatiles in silicate melts in equilibrium with silicate-saturated C-O-H fluids have been determined experimentally to upper mantle temperature and pressure conditions as a function of melt composition and redox conditions (hydrogen fugacity, fH2) in the range between magnetite-hematite + H2O [fH2 (MH)] and iron wustite + H2O buffer [fH2 (IW)]. Experiments have been carried out by examining both quenched materials with MAS NMR and vibrational spectroscopies as structural tools and in-situ with the sample at high temperature and pressure in a hydrothermal diamond anvil cell (HDAC) with vibrational spectroscopy as the structural tool. In fluid+melt-COH systems, volatiles are dissolved in molecular form (CO2, CH4, H2O, H2) and as complexes that form chemical bonding with the silicate network (CO3, CH3, OH). In silicate-OH systems molecular H2O and OH-groups coexist in silicate- and aluminosilicate-saturated fluids and water-saturated melts above with their OH/H2O-ratio positively correlated with temperature. The extent of hydrogen bonding in fluids and melts diminishes with temperature so that above ~ 400C it cannot be detected. Its ?H in aqueous fluid (221 kJ/mol) is about twice that of H2O dissolved in silicate melts (102 kJ/mol). Silicate speciation in silicate-saturated fluid and hydrous silicate melts comprises similar Q-species with ?H of the solution reactions in silicate-saturated fluid, water-saturated melt, and supercritical fluid ~40050 kJ/mol. The increasing silicate content in aqueous fluids with temperature and pressure provides an explanation of positive temperature and pressure correlation of melt/fluid partitioning and Ti4+, P5+ and D/H ratio. It also explains why PVT properties of silicate-saturated aqueous fluid are significantly different from those of pure H2O under lower crustal and upper mantle temperature and pressure conditions. In oxidized [e.g., f H2(MH)] silicate-C-O-H systems the CO2 solubility is in the 1-4 wt% range between ~1 and 3 GPa and decreases the more felsic a melt. Its solution mechanism is, CO2+Qn=CO3+Qn+1. Methane solubility, CH4, in melts, in contrast, is 10-30% of that of CO2 at the same temperature, pressure and melt composition. From diamond cell (HDAC) experiments conducted in-situ to 800C and 1435 MPa, the dominant species in the fluid are CH4, H2, and H2O with the C(melt)/C(fluid) partition coefficient increasing from 0.01 to 0.08 between 400 and 800C (and pressure increasing from ~400 to ~1400 MPa). In coexisting melt, CH3 - groups linked to the silicate melt structure via Si-CH3 bonding coexist with molecular CH4 thus resulting in the solution mechanism, CH4+Qn=CH3+Qn-1. The fH2-dependent solution mechanisms of C-O-H volatile components in silicate melts result in fH2-dependent thermodynamic and transport properties of magmatic liquids in the interior of the Earth and terrestrial planets. These properties include mineral/melt minor and trace element partitioning, melt/fluid isotope fractionation, and transport and thermodynamic properties of melt saturated with variably-oxidized C-O-H volatile components.

Mysen, B. O.

2012-12-01

374

Aqueous solubilities, vapor pressures, and 1-octanol-water partition coefficients for C9-C14 linear alkylbenzenes  

USGS Publications Warehouse

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.

Sherblom, P. M.; Gschwend, P. M.; Eganhouse, R. P.

1992-01-01

375

Vapor pressures and gas-phase PVT data for 1-chloro-1,2,2,2-tetrafluoroethane (R124)  

SciTech Connect

We present new data for the vapor pressure and PVT surface of 1-chloro-1,2,2,2-tetrafluoroethane (designated R124 by the refrigeration industry) in the temperature range 278-423 K. The PVT data are for the gas phase at densities up to 1.5 times the critical density. Correlating equations are given for the vapor pressures from 220 K to the critical temperature, 395.43 K, and for the PVT surface at densities up to 2 mol [center dot] L[sup [minus]1] (approximately 0.5 times the critical density). Second and third virial coefficients have been derived from the PVT measurements. 16 refs., 4 figs., 6 tabs.

Boyes, S.J.; Weber, L.A. (National Inst. of Standards and Technology, Gaithersburg, MD (United States))

1994-05-01

376

Effect of Aerosol Generation Method on Measured Saturation Pressure and Enthalpy of Vaporization for Dicarboxylic Acid Aerosols  

Microsoft Academic Search

To date, most studies of the thermodynamic properties of organic aerosols have utilized test aerosols generated by spray atomization followed by a diffusion drying step. Some evidence points to possible biases in measured thermodynamic properties stemming from the presence of residual solvent (water or alcohol) in the dried aerosol. In the current study we compared measurements of thermodynamic properties of

Rawad Saleh; Andrey Khlystov; Alan Shihadeh

2010-01-01

377

Chemical vapor infiltration of pyrocarbonIII: the influence of increasing methane partial pressure at increasing total pressure on infiltration rate and degree of pore filling  

Microsoft Academic Search

Chemical vapor infiltration of pyrocarbon was studied at 1100C 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

W. Benzinger; K. J. Httinger

1999-01-01

378

Sulfur concentration of martian basalts at sulfide saturation at high pressures and temperatures - Implications for deep sulfur cycle on Mars  

NASA Astrophysics Data System (ADS)

To constrain sulfur concentration at sulfide saturation (SCSS) of martian magmas at mantle conditions, we simulated basalt-sulfide melt equilibria using two synthesized meteorite compositions, i.e., Yamato980459 and NWA2990 in both anhydrous and hydrous conditions at 1-5 GPa and 1500-1700 C. Our experimental results show that SCSS decreases with increasing pressure and increases with increasing temperature. Based on our experimental SCSS and those from previous low-pressure experiments on high-FeO? martian basalts, we developed a parameterization to predict martian basalt SCSS as a function of depth, temperature, and melt composition. Our model suggests that sulfur contents as high as 3500-4300 ppm can be transferred from the martian mantle to the martian exogenic system, and sulfur-rich gases might have caused the greenhouse conditions during the late Noachian. However, modeling of the behavior of sulfur along the liquid line of descent of a primitive martian basalt suggests that a fraction of the magmatic sulfur could precipitate as sulfides in the cumulates during cooling and fractional crystallization of basaltic magmas. Furthermore, the latter case is consistent with the S concentration of martian meteorites, which reflect variable amount of trapped liquid in cumulus mineral assemblage. Furthermore, our model predicts an average S storage capacity of 5700 ppm for the martian magma ocean, whereas the same for Earth is only 860 ppm. Lastly, high SCSS of martian magma ocean and its inverse correlation with depth along the mantle liquidus could have triggered a sulfur pump where the post-core-formation magma ocean of Mars would gain sulfur through interaction with SO2/H2S rich nascent atmosphere.

Ding, Shuo; Dasgupta, Rajdeep; Tsuno, Kyusei

2014-04-01

379

High-pressure vapor-liquid equilibria of the binary mixtures nitrogen + n-butane and argon + n-butane  

Microsoft Academic Search

High-pressure vapor-liquid equilibrium composition and density data of the binary systems nitrogen + n-butane (at 339.4 and 380.2 K) and argon + n-butane (at 340.0 and 380.1 K) are reported. The data sets sere fit with the Peng-Robinson equation of state using both generalized and fluid-specific temperature-dependent parameters. The binary interaction parameters so obtained are reported.

Martin K. F. Malewski; Stanley I. Sandler

1989-01-01

380

Ex situ ellipsometry characterization of excimer laser annealed amorphous silicon thin films grown by low pressure chemical vapor deposition  

Microsoft Academic Search

Spectroscopic ellipsometry was used to monitor excimer laser annealed thin (?100 nm) amorphous silicon (a-Si) films grown on quartz substrates by low pressure chemical vapor deposition (LPCVD). The peak position of the imaginary part of the complex dielectric function &egr;2 was used to determine the degree of crystallization of the a-Si. The amplitude of &egr;2 at the Si E1 transition

Chau-Hong Kuo; In-Cha Hsieh; Dieter K. Schroder; George N. Maracas; Sheau Chen; Thomas W. Sigmon

1997-01-01

381

Mechanism of a remarkable enhancement in the light emission from nanocrystalline porous silicon annealed in high-pressure water vapor  

Microsoft Academic Search

To clarify the effect of surface passivation on the optical properties of nanocrystalline porous silicon (PS), the photoluminescence (PL) characteristics of PS have been investigated by employing a high-pressure water vapor annealing (HWA). PS samples with various porosities were prepared on (100)-oriented p-type (4 Omega cm) single-crystalline silicon wafers by electrochemical anodization. Some samples were then electrochemically oxidized. The HWA

Bernard Gelloz; Nobuyoshi Koshida

2005-01-01

382

Polarization memory of blue and red luminescence from nanocrystalline porous silicon treated by high-pressure water vapor annealing  

Microsoft Academic Search

The polarization memory (PM) effect in the blue and red photoluminescence (PL) of p-type porous Si (PS) treated by high-pressure water vapor annealing (HWA) has been investigated. HWA induces a significant blue PL emission at about 450nm, together with a drastic enhancement of the red PL intensity. The polarization memory of the red emission band is anisotropic and is in

B. Gelloz; H. Koyama; N. Koshida

2008-01-01

383

Electrical properties of low pressure chemical vapor deposited silicon nitride thin films for temperatures up to 650 C  

Microsoft Academic Search

The results of a study on electrical conduction in low pressure chemical vapor deposited silicon nitride thin films for temperatures up to 650 C are described. Current density versus electrical field characteristics are measured as a function of temperature for 100 and 200 nm thick stoichiometric (Si3N4) and low stress silicon-rich (SiRN) films. For high E-fields and temperatures up to

R. M. Tiggelaar; R. G. P. Sanders; J. G. E. Gardeniers

2009-01-01

384

Vapor pressures of phenethyl alcohol and phenethyl acetate in aqueous solutions of sodium xylene sulfonate and polyvinylpyrrolidone  

Microsoft Academic Search

Vapor pressures of two fragrance materials in aqueous solutions of polyvinylpyrrolidone and sodium xylenesulfonate were determined\\u000a using gas chromatography of head space samples. The association between polymer and hydrotrope was evaluated from the values\\u000a of surface tension and electrical conductance. The result showed an association of the hydrotrope and the polymer leading\\u000a to enhanced surface tension after addition of polymer

S. Friberg; L. Fei

385

Vaporliquid equilibria at elevated pressures of binary mixtures of carbon dioxide with methyl salicylate, eugenol, and diethyl phthalate  

Microsoft Academic Search

A semi-flow type apparatus was used to measure the vaporliquid equilibria (VLE) of CO2 with methyl salicylate, eugenol, and diethyl phthalate binary mixtures at 308.15, 318.15, and 328.15 K over the pressure range from 1.4 to 13 MPa. New VLE data for these binary mixtures are presented and the Henry's constants were determined from these results. The SoaveRedlichKwong and the

Kong-Wei Cheng; Shin-Jien Kuo; Muoi Tang; Yan-Ping Chen

2000-01-01

386

Excess internal pressure, excess energy of vaporization and excess pseudo-Gruneisen parameter of binary, ternary and quaternary liquid mixtures  

Microsoft Academic Search

Densities, viscosities and ultrasonic velocities were measured for four binary, one ternary and one quaternary liquid systems at 298.15K to obtain values of excess internal pressure and excess energy of vaporization. Values of pseudo-Gruneisen parameter and excess pseudo-Gruneisen parameter have been evaluated theoretically for two quaternary liquid systems. A quantitative relationship has been established among these thermodynamic properties with the

R. K. Shukla; S. K. Shukla; V. K. Pandey; Piyush Awasthi

2008-01-01

387

Defect Properties of CuInS2 Single Crystals Grown by Horizontal Bridgman Method with Controlling S Vapor Pressure  

Microsoft Academic Search

We have analyzed the lattice defects of CuInS2 bulk single crystals prepared by the horizontal Bridgman method with controlling S vapor pressure. The grown crystals have p-type conduction and electrical resistivities of more than 103 Omega{\\\\cdot}cm at room temperature. From measurements of the Hall effect, photoluminescence, optical absorption and photoconductivity, the activation energies of acceptors in CuInS2 crystals are shown

Hiroaki Matsushita; Tomohiro Mihira; Takeo Takizawa

2001-01-01

388

Alkali-metal-vapor removal from pressurized fluidized-bed-combustor flue gas. Annual report, October 1981September 1982  

Microsoft Academic Search

This work supports the program to develop sorbents for the cleanup of gases from pressurized fluidized-bed coal combustion (PFBC) so that the cleaned hot gases can be used to power downstream gas turbines without causing corrosion. A simulated PFBC flue gas containing NaCl vapor was used to characterize activated bauxite and diatomaceous earth at a bed temperature of 905°C and

S. H. D. Lee; K. M. Myles; A. A. Jonke

1983-01-01

389

Se vapor pressure dependence of the phase diagram of the CuGa 1- xIn xSe 2 system  

NASA Astrophysics Data System (ADS)

Phase transition points of the CuGa 1- xIn xSe 2 system are investigated by the differential thermal analysis with varying Se vapor pressure up to 760 Torr. The phase diagrams constructed under controlled Se vapor pressure show that the solidus and liquidus points decrease more than 100C with increasing Se vapor pressure, and that the temperature zone of the (sphalerite+liquid) phase narrows in the region of same pressure. From the analysis of chemical reactions of CuGa 1- xIn x+2Se mixtures, it is shown that In-rich CuGa 1- xIn xSe 2 bulk crystals can be grown using the selenization horizontal Bridgman method. In this case, it is necessary to optimize the temperature width of the temperature gradient zones in the furnace so as to cover the solidus points at the respective Se vapor pressures.

Matsushita, Hiroaki; Takizawa, Takeo

1998-07-01

390

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

Code of Federal Regulations, 2010 CFR

...subpart. (b)(1) After each pressure release, the pressure relief device...than 5 calendar days after each pressure release, except as provided in § 63...than 5 calendar days after the pressure release and being returned to...

2009-07-01

391

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

Code of Federal Regulations, 2010 CFR

...requirements. (1) After each pressure release, the pressure relief device...than 5 calendar days after each pressure release, except as provided in § 63...of this section following a pressure release including the background...

2009-07-01

392

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

Code of Federal Regulations, 2010 CFR

...requirements. (1) After each pressure release, the pressure relief device...than 5 calendar days after each pressure release except as provided in § 65...than 5 calendar days after the pressure release and being returned to...

2009-07-01

393

Low temperature atmospheric pressure chemical vapor deposition of group 14 oxide films  

SciTech Connect

Depositions of high quality SiO{sub 2} and SnO{sub 2} films from the reaction of homoleptic amido precursors M(NMe{sub 2})4 (M = Si,Sn) and oxygen were carried out in an atmospheric pressure chemical vapor deposition r. The films were deposited on silicon, glass and quartz substrates at temperatures of 250 to 450C. The silicon dioxide films are stoichiometric (O/Si = 2.0) with less than 0.2 atom % C and 0.3 atom % N and have hydrogen contents of 9 {plus_minus} 5 atom %. They are deposited with growth rates from 380 to 900 {angstrom}/min. The refractive indexes of the SiO{sub 2} films are 1.46, and infrared spectra show a possible Si-OH peak at 950 cm{sup {minus}1}. X-Ray diffraction studies reveal that the SiO{sub 2} film deposited at 350C is amorphous. The tin oxide films are stoichiometric (O/Sn = 2.0) and contain less than 0.8 atom % carbon, and 0.3 atom % N. No hydrogen was detected by elastic recoil spectroscopy. The band gap for the SnO{sub 2} films, as estimated from transmission spectra, is 3.9 eV. The resistivities of the tin oxide films are in the range 10{sup {minus}2} to 10{sup {minus}3} {Omega}cm and do not vary significantly with deposition temperature. The tin oxide film deposited at 350C is cassitterite with some (101) orientation.

Hoffman, D.M. [Houston Univ., TX (United States); Atagi, L.M. [Houston Univ., TX (United States)]|[Los Alamos National Lab., NM (United States); Chu, Wei-Kan; Liu, Jia-Rui; Zheng, Zongshuang [Houston Univ., TX (United States); Rubiano, R.R. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Springer, R.W.; Smith, D.C. [Los Alamos National Lab., NM (United States)

1994-06-01

394

Evaluation of Vapor Pressure and Ultra-High Vacuum Tribological Properties of Ionic Liquids (2) Mixtures and Additives  

NASA Technical Reports Server (NTRS)

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.

Morales, Wilfredo; Koch, Victor R.; Street, Kenneth W., Jr.; Richard, Ryan M.

2008-01-01

395

Prediction of spatially distributed regional-scale fields of air temperature and vapor pressure over mountain glaciers  

NASA Astrophysics Data System (ADS)

Physically based models of glacier melt require fields of near-surface air temperature (Tg) and vapor pressure (eg) for estimating turbulent heat exchanges. However, katabatic boundary layer (KBL) processes limit the effectiveness of standard interpolation or extrapolation routines for estimating Tg and eg from regional weather station networks. Climate data collected from nine automatic weather stations operated over three ablation seasons at three glaciers in the southern Coast Mountains of British Columbia are analyzed in this study. On-glacier observations were compared to ambient values (Ta and ea) estimated from a regional network of off-glacier weather stations. Piecewise regressions of Tg versus Ta at each AWS site reveal (1) a critical threshold temperature (T*) that denotes the onset of katabatic boundary layer (KBL) development and (2) a temperature damping that is consistent at each site, but variable between sites. Variations in near-surface vapor pressure are related to processes of condensation or evaporation/sublimation at the glacier surface, which are controlled by the vapor pressure gradient between the surface and the ambient air. Statistical relations with flow path lengths calculated from glacier digital elevation models are used to predict the strength of KBL effects on Tg and eg, and examples of the approach for generating distributed fields of Tg and eg are given.

Shea, J. M.; Moore, R. D.

2010-12-01

396

The vapor pressure of 1,1,1,2-tetrafluoroethane (R134a) and chlorodifluoromethane (R22)  

Microsoft Academic Search

We measured the vapor pressure of chlorodifluoromethane (commonly known as R22) at temperatures between 217.1 and 248.5 K and of 1,1,1,2-tetrafluoroethane (commonly known as R134a) in the temperature range 214.4 to 264.7 K using a comparative ebulliometer. For 1,1,1,2-tetrafluoroethane at pressures between 220.8 and 1017.7kPa (corresponding to temperatures in the range 265.6 to 313.2K), additional measurements were made with a

A. R. H. Goodwin; D. R. Defibaugh; L. A. Weber

1992-01-01

397

Measurements of seismic attenuation and transient fluid pressure in partially saturated Berea sandstone: evidence of fluid flow on the mesoscopic scale  

NASA Astrophysics Data System (ADS)

A novel laboratory technique is proposed to investigate wave-induced fluid flow on the mesoscopic scale as a mechanism for seismic attenuation in partially saturated rocks. This technique combines measurements of seismic attenuation in the frequency range from 1 to 100 Hz with measurements of transient fluid pressure as a response of a step stress applied on top of the sample. We used a Berea sandstone sample partially saturated with water. The laboratory results suggest that wave-induced fluid flow on the mesoscopic scale is dominant in partially saturated samples. A 3-D numerical model representing the sample was used to verify the experimental results. Biot's equations of consolidation were solved with the finite-element method. Wave-induced fluid flow on the mesoscopic scale was the only attenuation mechanism accounted for in the numerical solution. The numerically calculated transient fluid pressure reproduced the laboratory data. Moreover, the numerically calculated attenuation, superposed to the frequency-independent matrix anelasticity, reproduced the attenuation measured in the laboratory in the partially saturated sample. This experimental-numerical fit demonstrates that wave-induced fluid flow on the mesoscopic scale and matrix anelasticity are the dominant mechanisms for seismic attenuation in partially saturated Berea sandstone.

Tisato, Nicola; Quintal, Beatriz

2013-10-01

398

Relationship of Wvtr to Water Vapor Pressure as a Determinant in Predicting Package Life.  

National Technical Information Service (NTIS)

A series of water vapor transmission rates were determined for a number of flexible barriers over a range of temperatures and humidities. The results obtained were used to provide a basis for establishing an empirical formula permitting the extrapolation ...

D. Minuti

1967-01-01

399

Temperature and Water Vapor Pressure Effects on the Friction Coefficient of Hydrogenated Diamondlike Carbon Films.  

National Technical Information Service (NTIS)

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 th...

A. Erdemir N. Argibay O. L. Eryilmaz P. L. Dickrell W. G. Sawyer

2009-01-01

400

Pressure and power generation during explosive vaporization on a thin-film microheater  

Microsoft Academic Search

When a liquid is superheated above its boiling point to temperatures near or at the homogeneous nucleation limit, the energy released could create a so-called explosive vaporization, if a significant fraction of this energy is manifested in the form of vapor expansion. In this study, a thin-film microheater (100?m110?m) was placed on the underside of a water layer. The surface

Z. Zhao; S. Glod; D. Poulikakos

2000-01-01

401

Vapor-liquid equilibrium in low pressure water+congener mixtures  

Microsoft Academic Search

Vapor-liquid equilibrium in binary water+congeners mixtures found in alcoholic distillation has been analyzed using the Peng-Robinson\\u000a equation of state and one of the most popular modern mixing rules, the Wong-Sandler model. Accurate modeling of the concentration\\u000a of congeners (substances different from ethanol and water) in the vapor phase is of special importance because these substances\\u000a give some special characteristics of

Claudio Alonso Fandez; Felipe Andrs Urbina; Jos Omar Valderrama

2009-01-01

402

Isobaric low pressure vaporliquid equilibrium data for the binary system monochloroacetic acid + dichloroacetic acid  

Microsoft Academic Search

Isobaric vaporliquid equilibrium (VLE) data for the binary system monochloroacetic acid+dichloroacetic acid have been measured at 5, 7.5, and 10kPa. The VLE data measured in this work is thermodynamically consistent according to the Herington area method. The non-ideal behavior in the vapor phase was correlated using the HaydenOConnell model. Wilson, NRTL, and UNIQUAC were used to account for the liquid

Alex Londoo; Mark T. G. Jongmans; Boelo Schuur; Andr B. de Haan

403

A combined droplet train and ambient pressure photoemission spectrometer for the investigation of liquid/vapor interfaces.  

PubMed

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 mum 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. PMID:18688373

Starr, David E; Wong, Ed K; Worsnop, Douglas R; Wilson, Kevin R; Bluhm, Hendrik

2008-06-01

404

The effect of halogen hetero-atoms on the vapor pressures and thermodynamics of polycyclic aromatic compounds measured via the Knudsen effusion technique  

Microsoft Academic Search

Knowledge of vapor pressures of high molar mass organics is essential to predicting their behavior in combustion systems as well as their fate and transport within the environment. This study involved polycyclic aromatic compounds (PACs) containing halogen hetero-atoms, including bromine and chlorine. The vapor pressures of eight PACs, ranging in molar mass from (212 to 336)gmol?1, were measured using the

Jillian L. Goldfarb; Eric M. Suuberg

2008-01-01

405

Does Spatial Variation in Soil Characteristics Affect Tree Transpiration Responses to Vapor Pressure Deficit?  

NASA Astrophysics Data System (ADS)

Forest canopy transpiration (Ec) both depends on and influences the local and regional atmospheric conditions. Because soil is the source of water for Ec, the soil's chemical and physical properties are also likely to be drivers of transpiration. The objective of this study is to spatially quantify the relationship between the soil's chemical and physical characteristics and Ec across environmental gradients. The two study sites are in northern Wisconsin, in mixed hardwood forest. In one site, the environmental gradient runs from a dry upland dominated by aspen (Populus tremuloides) to a wetland dominated by alders (Alnus rugosa). The second site has little elevational variation, is well-drained, and is dominated by sugar maple (Acer saccharum) bisected by a swath of red pine (Pinus resinosa). Ec data have been collected over three summers on the same set of trees using Granier sensors, while the soil samples were collected in 2006 from the same plots as the measured trees. Both of the approximately 120 m x 120 m plots have been sampled in 10 m x 10 m subplots based on a 3/7 cyclic sampling scheme to maximize spatially explicit information with a minimum number of sampled points. Roughly 150 trees were measured in each plot. We have previously shown an inverse relationship between the spatial autocorrelation of Ec and vapor pressure deficit (D). We thus hypothesize that a significant amount of this relationship can be explained by soil properties. Preliminary analysis of soil data from a representative transect in the aspen site show that soil texture, carbon (C) content, and nitrogen (N) content change along the gradient. From the upland through the wetland, Ec declined significantly, and, while all the soils were a sandy loam, the sand content showed a decreasing trend, while the silt content increased nearly two-fold. Across the same (upland to wetland) gradient, the C:N ratio showed a slightly increasing trend, but the total percentage values of the two elements increased nearly 25 fold: from C of 0.884 and N of 0.060 to C of 22.34 and N of 1.283. We hypothesize that the maple site will show less variability in Ec because of its more uniform soil characteristics. Ongoing work of soil moisture release curves, bulk density, and root biomass will provide additional explanations of the spatial relationships between Ec and D. Our analytical approach, then, provides a first step in explaining the processes behind spatial patterns in transpiration.

Traver, E.; Ewers, B. E.; Loranty, M.; Mackay, D. S.

2006-12-01

406

A new approach to determine vapor pressures of compounds in multicomponent systems by comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry.  

PubMed

A method is described to determine vapor pressures of compounds in multicomponent systems simultaneously. The method is based on temperature-gradient analysis by comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GCxGC-TOFMS). Vapor pressures are determined with the aid of known vapor pressure values of reference compounds eluting before and after the analytes. Reference compounds with the same functionalities as the analytes are preferred, but when these are not available, the alkane series can be utilized. The number of compounds whose vapor pressures can be determined is limited only by the peak capacity of the chromatographic system. Although the lowest subcooled vapor pressure determined was 0.006Pa, for tetrahydroaraucarolone in an atmospheric aerosol sample, vapor pressures as low as 10(-6)Pa can be measured with the described set-up. Even lower values can be measured with higher GC temperatures and longer analysis times. Since only a few picograms of compound is required, in a mixture of any complexity, the GCxGC-TOFMS method offers unique sensitivity, rapidity, and comprehensiveness. PMID:24767441

Parshintsev, Jevgeni; Lai, Ching Kwan; Hartonen, Kari; Kulmala, Markku; Riekkola, Marja-Liisa

2014-06-15

407

Positive Charge Increase in Plasma Deposited Oxides Induced by Low Pressure Chemical Vapor Deposition of Silicon Nitride  

NASA Astrophysics Data System (ADS)

The origin of the positive charge observed in an interlayer dielectrics made of a silicon-oxide layer deposited by plasma enhanced chemical vapor deposition (PECVD) from an O2/tetraethoxysilane (TEOS) mixture covered by a silicon-nitride layer obtained by low pressure chemical vapor deposition (LPCVD) is studied. Charge creation during silicon-nitride deposition is evidenced. Even though NH3 thermal decomposition is one of the main parameters of both hydrogen incorporation and the charge creation in the oxide layer, the increase in hydrogen content and charge trapping after nitride deposition is not only due to the diffusion of hydrogen originating from ammonia fragmentation. The results show that the charge decrease observed when increasing the O2/TEOS ratio and boron doping is partly related to the decrease of the carbon content in the oxide.

Fay, Jean Luc; Beluch, Jean; Despax, Bernard; Sarrabayrouse, Grard

2001-01-01

408

A Convenient, Inexpensive, and Environmentally Friendly Method of Measuring the Vapor Pressure of a Liquid as a Function of Temperature  

NASA Astrophysics Data System (ADS)

The popular experiment in which students measure the vapor pressure of a liquid as a function of temperature has been modified by introducing the use of a hand-held vacuum pump. This inexpensive modification not only eliminates the need to use mercury manometers and water aspirators, but it also makes the experimental apparatus much simpler and allows more data points to be collected during the three-hour lab period. Enthapies of vaporization and normal boiling points for the unknown samples, determined from the data by use of the Clausius-Clapeyron equation, are usually within approximately 5% of the actual values. This paper describes the experimental procedure and setup needed for the revised experiment and compares the accuracy and precision of the data collected by both the original and the modified procedures.

Burness, James H.

1996-10-01

409

Alkali metal vapor removal from pressurized fluidized-bed combustor flue gas. Quarterly report, January-March 1980  

SciTech Connect

In the application of pressurized fluidized-bed combustion (PFBC) to the generation of electricity, hot corrosion of the gas turbine (downstream from the combustor) by alkali metal compounds is a possible problem. The objective of this investigation is to develop a method for the removal of the gaseous alkali metal compounds from the high-pressure high-temperature gas from a PFBC before the gas enters the gas turbine. The use of a granular bed filter, with either diatomaceous earth or activated bauxite as the bed material, is under study. A sectioned-bed technique is under development for the measurement of vapor breakthrough. The magnitude of the pressure drop across the bed is under investigation.

Johnson, I.; Swift, W.M.; Lee, S.H.D.

1980-07-01

410

Alkali metal vapor removal from pressurized fluidized-bed combustor flue gas. Quarterly report, April-June 1980  

SciTech Connect

In the application of pressurized fluidized-bed combustors (PFBC) to the generation of electricity, hot corrosion of gas turbine components by alkali metal compounds is a potential problem. The objective of this investigation is to develop a method for removing these gaseous alkali metal compounds from the high-pressure high-temperature gas from a PFBC before the gas enters the gas turbine. A granular-bed filter, using either diatomaceous earth or activated bauxite as the bed material, is the concept currently being studied. Results are presented for the testing of diatomaceous earth for alkali vapor sorption at 800/sup 0/C and 9-atm pressure, using a simulated flue gas. Activated bauxite sorbent can be regenerated by leaching with water, and the kinetics of the leaching is under study.

Johnson, I.; Swift, W.M.; Lee, S.H.D.; Boyd, W.A.

1980-07-01

411

1 V saturated Pb(Zr,Ti)O3 films with (111) orientation using lattice-matched (111)SrRuO3\\/(111)Pt bottom electrode prepared by pulsed metal organic chemical vapor deposition  

Microsoft Academic Search

Pb(Zr0.35Ti0.65)O3 films measuring 33 nm thick, were prepared on (111)SrRuO3\\/(111)Pt\\/TiO2\\/SiO2\\/(100)Si substrates at 540 C using pulsed metal organic chemical vapor deposition. (111)-oriented films consisting of columnar grains possessed local epitaxial relationships with the underling (111)-oriented SrRuO3 layer. Their polarization (electric field characteristics), which had better symmetry than those on (111)Ir\\/\\/TiO2\\/SiO2\\/(100)Si substrates, were saturated below 1 V with a large remanent

Hiroki Kuwabara; Nicolas Menou; Hiroshi Funakubo

2008-01-01

412

Realization of the 3He Vapor-Pressure Temperature Scale and Development of a Liquid-He-Free Calibration Apparatus  

NASA Astrophysics Data System (ADS)

The 3He vapor-pressure temperature scale was realized using an apparatus based on a continuously operating 3He cryostat at the National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST). The cryostat has two operational modes: a 3He circulation mode and a 1 K pot mode. The 3He circulation mode can be used for 3He vapor-pressure measurements below 1.6 K, and the 1 K pot mode can be used for measurements above 1.3 K. Either mode can be selected for measurements from 1.3 K to 1.6 K. The realization of the 3He vapor-pressure temperature scale in this study fully covers its defined temperature range from 0.65 K to 3.2 K in the International Temperature Scale of 1990. The latest realization results are presented in this article. In addition, a liquid-He-free calibration apparatus was developed. It does not require liquid helium as a cryogen, which usually entails cumbersome handling and periodic refilling. The apparatus was designed for the calibration of capsule-type resistance thermometers from 0.65 K to 24.5561 K (the triple point of neon). The cooling system of the apparatus consists of a commercially available pulse-tube refrigerator and a 3He Joule-Thomson (JT) cooling circuit developed at NMIJ/AIST. The pulse-tube refrigerator is used in a pre-cooling stage and cools the apparatus to approximately 5 K. The 3He JT cooling circuit is used to cool the apparatus from 5 K to below 0.65 K. Since the 3He JT cooling circuit is a closed circuit, the apparatus can run continuously with only simple maintenance required. The basic characteristics of the apparatus are described.

Shimazaki, T.; Toyoda, K.; Tamura, O.

2011-12-01

413

Effects Of Water-Saturation On Strength And Ductility Of Three Igneous Rocks At Effective Pressures To 50 Mpa And Temperatures To Partial Melting  

Microsoft Academic Search

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 10⁻⁴s⁻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

S. J. Bauer; M. Friedman; J. Handin

1981-01-01

414

Strength and ductility of room-dry and water-saturated igneous rocks at low pressures and temperatures to partial melting. Final report  

Microsoft Academic Search

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° to 1050°C and a strain rate of 10⁻⁴s⁻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

M. Friedman; J. Handin; N. G. Higgs; J. R. Lantz; S. J. Bauer

1980-01-01

415

Small scale experiments on boiling liquid expanding vapor explosions: Vessel over-pressure  

Microsoft Academic Search

The boiling liquid expanding vapor explosion (BLEVE) is a type of physical explosion that has caused massive damage in the petrochemical industry. In this paper, a study has been made of the conditions that could lead to a BLEVE. A device was built to simulate the occurrence of suddenly initiated release through a top orifice. As there is some danger

Si-Ning Chen; Jin-Hua Sun; Guan-Quan Chu

2007-01-01

416

Grid orientation and capillary pressure effects in the simulation of water injection into depleted vapor zones  

Microsoft Academic Search

The spatial orientation of finite difference computational grids can strongly influence numerical simulations of water injection into vapor zones. Robust numerical behavior is seen in two-dimensional areal models, while extreme sensitivity to grid orientation is found in vertical sections. Mathematical analysis of finite difference approximations provides insight into the nature and strength of grid effects and leads to the concept

K PRUESS

1991-01-01

417

Separation and Characterization of a Hydrogen Getter Product Mixture: Part 2, Measurement of Product Vapor Pressures.  

National Technical Information Service (NTIS)

HCPB is the acronym of an organic hydrogen getter compound used in weapon systems. When this material scavenges hydrogen by reacting with it, a number of compounds are formed, each of which is more volatile than HCPB. It is desirable to know the vapor pre...

D. W. Fircish T. R. Shell

1987-01-01

418

Extension of Pitzer corresponding states correlations using new vapor pressure measurements of the n-alkanes C sub 10 to C sub 28  

SciTech Connect

Direct vapor pressure measurements of zone-refined n-alkane samples in the carbon number range from C{sub 10} to C{sub 28} (decane, dodecane, tetradecane, hexadecane, octadecane, nonadecane, eicosane, docosane, tetracosane, and octacosane) have been obtained. The overall range of the new measurements are from 0.1 to 1400 kPa and from 323 to 588{degree}K with expected accuracies given by (0.00015P + 0.0048)kPa and 0.03{degree}K. The vapor pressure data have been regressed to Wagner-type equations using critical parameters developed. To extend the range of the Wagner equations toward low reduced temperatures, an alternative set of conformal'' equations were constructed using two real-fluid corresponding states principle (CSP) methods. Using n-alkane vapor pressure data in the range from C{sub 1} to C{sub 36}, the acentric factor ranges of Pitzer-type CSP correlations for vapor pressures and heats of vaporization were extended. In a first approach dubbed PERT2'', a set of conformal'' Wagner equations was generalized by including a second order perturbation term in Pitzer's acentric factor expansion for In(P{sub r}). In a second approach, input parameters (P{sub c},{omega}) were determined from vapor pressure data for accurate pairs of vapor pressure and heat of vaporization reference equations based on methane and octane (C{sub 1}/C{sub 8}). Input parameters (T{sub c},P{sub c},{omega}) for n-alkanes have been correlated and tabulated out to C{sub 36} for both of these approaches. Ratios of the parameters for the two methods can be interpreted in terms of shape factor'' effects. 83 refs., 23 figs., 25 tabs.

Morgan, D.L.; Kobayashi, R.

1989-12-31

419

Very long single- and few-walled boron nitride nanotubes via the pressurized vapor/condenser method  

NASA Astrophysics Data System (ADS)

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.

Smith, Michael W.; Jordan, Kevin C.; Park, Cheol; Kim, Jae-Woo; Lillehei, Peter T.; Crooks, Roy; Harrison, Joycelyn S.

2009-12-01

420

High-pressure vapor-liquid equilibria for ethylene + 4-methyl-1-pentane and 1-butene + 1-hexene  

SciTech Connect

Isothermal vapor-liquid equilibria (VLE) for the ethylene + 4-methyl-1-pentene and 1-butene + 1-hexene binary systems were measured by the static method at several temperatures for pressures in the range (0.3 to 8.5) MPa. Representations of VLE data by the Soave and Peng-Robinson cubic equations of state are compared in both modes: predictive and binary parameter adjustment. As the two binary systems behave almost ideally, there is no significant difference between their representation qualities through both equations of state.

Laugier, S. [Ecole Nationale Superieure de Chimie et Physique de Bordeaux, Talence (France)] [Ecole Nationale Superieure de Chimie et Physique de Bordeaux, Talence (France); Richon, D. [Ecole Nationale Superieure des Mines de Paris, Fontainebleau (France)] [Ecole Nationale Superieure des Mines de Paris, Fontainebleau (France)

1996-03-01

421

Transformation of Bromine Species During Decomposition of Bromate under UV Light from Low Pressure Mercury Vapor Lamps  

Microsoft Academic Search

Bromate decomposition with low pressure mercury vapor lamps (LPMVL) was studied in buffer-free and buffered Milli-Q water by following the fate of bromine species BrO3 , Br, and free bromine. BrO3 was converted over time to Br with total free bromine (TFBr) as secondary reaction product. BrO3 decay followed pseudo-first-order kinetics and was independent of [BrO3 ]o (0.060.6 mM), pHo

Neal H. Phillip; Erdal Grten; Vasil Diyamando?lu

2006-01-01

422

Very long single- and few-walled boron nitride nanotubes via the pressurized vapor/condenser method  

SciTech Connect

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.

Michael W. Smith, Kevin Jordan, Cheol Park, Jae-Woo Kim, Peter Lillehei, Roy Crooks, Joycelyn Harrison

2009-11-01

423

Very Long Single and Few-Walled Boron Nitride Nanotubes via the Pressurized Vapor/Condenser Method  

NASA Technical Reports Server (NTRS)

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.

Smith, Michael W.; Jordan, Kevin C.; Park, Cheol; Kim, Jae-Woo; Lillehei, Peter T.; Crooks, Roy; Harrison, Joycelyn S.

2009-01-01

424

Development of tilted hexagonal platelet ZnO using atmospheric pressure chemical vapor deposition and investigation of its growth mechanism  

NASA Astrophysics Data System (ADS)

Large area ZnO films (25 25 cm2) grown via atmospheric pressure chemical vapor deposition (APCVD) showed unique surface morphologies of tilted hexagonal platelets. In response to the tilt angle change from 50 to 75, haze values increased from 7% to 25%, indicating that tilt angles directly affected the light-trapping capabilities of films. These unique surfaces were created when H2O oxidizers were used, while powder-like ZnO formed when O2 or O3 oxidizers were used. Based on experimental results, corresponding density function theory, and thermodynamic calculations, the initial growth and property of APCVD for ZnO on glass were elucidated.

Yoo, Y. Z.; Kim, S. H.; Yoon, G. S.; Choi, E. H.; Park, J.-W.; Park, J. H.; Kim, B.-G.; Jung, S. C.; Park, B. M.

2012-02-01

425

Beer Law Constants and Vapor Pressures of HgI2 over HgI2(s,l)  

NASA Technical Reports Server (NTRS)

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.

Su, Ching-Hua; Zhu, Shen; Ramachandran, N.; Burger, A.

2002-01-01

426

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)

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.

Keshav, Shantanu; Gudfinnsson, Gudmundur H.

2013-07-01

427

Strength and ductility of room-dry and water-saturated igneous rocks at low pressures and temperatures to partial melting. Final report  

SciTech Connect

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)

Friedman, M.; Handin, J.; Higgs, N.G.; Lantz, J.R.; Bauer, S.J.

1980-11-01

428

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

Microsoft Academic Search

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

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

1997-01-01

429

Comparing magnetotransport and surface magnetic properties of half-metallic CrO2 films grown by low pressure and atmospheric pressure chemical vapor deposition  

NASA Astrophysics Data System (ADS)

CrO2 films prepared by low pressure chemical vapor deposition (LPCVD) using Cr(CO)6 precursor have been investigated and compared with epitaxial half metallic CrO2 films prepared at atmospheric pressure (APCVD) using CrO3 precursor for their magnetotransport and surface magnetic properties. LPCVD films showed higher resistivity than APCVD epitaxial (100) CrO2 films prepared on (100) TiO2 substrates. Magnetoresistance of LPCVD films is comparable to that of APCVD films. X-ray magnetic circular dichroism suggests a reduced surface magnetic moment for LPCVD films. This reduced magnetic moment is attributed to antiferromagnetic alignment of the uncompensated Cr spins in the Cr2O3 surface layer.

Pathak, M.; Zhong, X.; Wang, J.; Zhang, X.; Klein, T. M.; Leclair, P.; Gupta, A.

2010-03-01

430

Enhanced growth of high quality single crystal diamond by microwave plasma assisted chemical vapor deposition at high gas pressures  

SciTech Connect

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 {mu}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.

Liang Qi; Chin Chengyi; Lai, Joseph; Yan Chihshiue; Meng Yufei; Mao Hokwang; Hemley, Russell J. [Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road NW, Washington, DC 20015 (United States)

2009-01-12

431

Spectral Radiance Between 0.42 mu and 1.1 mu of Rubidium and Cesium Vapor Arc Lamps as Function of Power Input and Pressure.  

PubMed

The spectral radiance between 0.42 mu. and 1.1 mu of rubidium and cesium vapor arc lamps was measured for various input powers and vapor pressures. A strong resonance broadening of the resonance lines was observed at high pressures. A strong continuum in the visible is tentatively attributed to Stark broadening of the overlapping lines of the higher order numbers of the 6p-nd and 5d-nf series and to the related series border continua. Data are given for total radiance (0.42-1.1 mu) as function of pressure, for the efficiency vs power input, and the lamp voltage and current. PMID:20076302

Fromm, D

1970-04-01

432

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

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.

Bauer, S.J.; Friedman, M.; Handin, J.

1981-01-01

433

Development of an aerosol shock tube for kinetic studies of low-vapor-pressure fuels  

Microsoft Academic Search

A new experimental flow facility, an aerosol shock tube, has been developed to enable studies of shock wave interactions with liquid aerosols, including droplet evaporation kinetics and subsequent chemical reaction of the vapor. This technique provides a uniform spatial distribution of aerosol in the shock tube, which ensures well-behaved shock-induced flows, and a narrow micrometer-sized aerosol size distribution that rapidly

D. F. Davidson; D. R. Haylett; R. K. Hanson