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Phillip Servio - One of the best experts on this subject based on the ideXlab platform.
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bulk liquid and gas Mole Fraction measurements during hydrate growth for the ch4 co2 h2o system
The Journal of Chemical Thermodynamics, 2018Co-Authors: Francis Lang, Phillip ServioAbstract:Abstract Gas and liquid Mole Fraction were experimentally obtained for the CH 4 + CO 2 + H 2 O system at four different time intervals during hydrate growth. In order to validate the procedure, equilibrium Mole Fractions were also obtained and satisfactorily compared to literature values. Using a 70.0% CH 4 – 30.0% CO 2 loading composition in combination with a 1.6 MPa driving force at 274 K, results showed that both the liquid and gas Mole Fraction of methane and carbon dioxide were independent of time during the early stages of growth. For comparison purposes, samples were also obtained during the induction period. After the nucleation event, methane liquid Mole Fractions dropped below induction values while no change was observed for carbon dioxide. It is therefore postulated that methane consumption is favored during the early stages of growth. The rates of crystal growth were acquired and in parallel with all other parameters obtained experimentally, were proven critical to understand multicomponent gas hydrate kinetics.
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Bulk liquid and gas Mole Fraction measurements during hydrate growth for the CH4 + CO2 + H2O system
The Journal of Chemical Thermodynamics, 2018Co-Authors: Francis Lang, Phillip ServioAbstract:Abstract Gas and liquid Mole Fraction were experimentally obtained for the CH 4 + CO 2 + H 2 O system at four different time intervals during hydrate growth. In order to validate the procedure, equilibrium Mole Fractions were also obtained and satisfactorily compared to literature values. Using a 70.0% CH 4 – 30.0% CO 2 loading composition in combination with a 1.6 MPa driving force at 274 K, results showed that both the liquid and gas Mole Fraction of methane and carbon dioxide were independent of time during the early stages of growth. For comparison purposes, samples were also obtained during the induction period. After the nucleation event, methane liquid Mole Fractions dropped below induction values while no change was observed for carbon dioxide. It is therefore postulated that methane consumption is favored during the early stages of growth. The rates of crystal growth were acquired and in parallel with all other parameters obtained experimentally, were proven critical to understand multicomponent gas hydrate kinetics.
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new insights into the effect of polyvinylpyrrolidone pvp concentration on methane hydrate growth 2 liquid phase methane Mole Fraction
Chemical Engineering Science, 2015Co-Authors: Dany Posteraro, Jason Ivall, Milan Maric, Phillip ServioAbstract:Abstract Kinetic hydrate inhibition studies generally characterize the effect of inhibitors on the crystal phase during formation and growth conditions. However, little work has been conducted to investigate the influence of the inhibitors on the gas hydrate former in kinetically inhibited systems. The current study examines the effect of polyvinylpyrrolidone (PVP) on methane Mole Fraction in the bulk liquid phase during growth. Hydrates were formed in an isothermal/isobaric semi-batch stirred crystallizer maintained at 275.1 K and 5645 kPa that contained aqueous solutions of 0–0.07 wt% PVP. Mole Fraction measurements were taken from liquid samples extracted at 450 s and 900 s after the start of hydrate growth. Results indicated that while PVP had a negligible effect on methane solubility, the degree of supersaturation was significantly enhanced with inhibitor loading. The increase in supersaturation was attributed predominantly to a reduced surface area available for enclathration of methane into the hydrate lattice due to PVP binding. Correlation of Mole Fraction results to growth rate data through a kinetic model further pointed to a significant decrease in the total surface area available for reaction as a function of inhibitor loading.
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surfactant effects on methane solubility and Mole Fraction during hydrate growth
Chemical Engineering Science, 2012Co-Authors: Jonathan Verrett, Dany Posteraro, Phillip ServioAbstract:Investigations are still ongoing to discover the mechanism by which surfactants promote hydrate growth. This paper investigates the effects of sodium dodecyl sulfate (SDS), a common surfactant for promoting hydrate growth, on methane solubility and Mole Fraction in the bulk liquid phase. Hydrates were formed in a stirred 600 cm3 isobaric/isothermal reactor containing 343 cm3 of liquid. Bulk solubility experiments under hydrate–liquid, liquid–gas, and hydrate–liquid–gas equilibria were performed at temperatures ranging from 275.1 K to 283.3 K and pressures ranging from 3049 kPa to 6500 kPa with pure water as well as SDS solutions. Kinetic experiments were also performed with water and 360-ppm solutions of SDS at temperatures of 275.1 K, 277.1 K and 279.1 K and pressures of 4545 kPa, 5180 kPa and 6080 kPa respectively. Measurements of the Mole Fraction of methane in the bulk liquid were taken at 0 s, 225 s and 450 s after hydrate nucleation. Experiments showed that SDS has no effect on bulk methane solubility at concentrations that significantly promote hydrate growth. SDS was found to increase methane Mole Fraction in the bulk liquid during hydrate growth following nucleation. Results were analyzed using the solubility model previously developed by Bergeron and Servio. The increase in methane Mole Fraction was found to be the major contributor to the increase in hydrate growth rate. It is estimated that other factors, such as changes in hydrate particle surface area, may also affect the growth rate and should be investigated further.
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co2 and ch4 Mole Fraction measurements during hydrate growth in a semi batch stirred tank reactor and its significance to kinetic modeling
Fluid Phase Equilibria, 2009Co-Authors: Sebastien Bergeron, Phillip ServioAbstract:Abstract A new experimental technique has been developed to measure the Mole Fraction of the gas hydrate former in the bulk liquid phase, at the onset of hydrate growth and thereafter, in a semi-batch stirred tank reactor. The Mole Fraction of carbon dioxide and methane in the bulk liquid phase was obtained for the first 11 and 13 min of the growth stage, for the carbon dioxide–water and methane–water systems respectively. Experiments were conducted at temperatures ranging from 275.3 K to 281.4 K and at pressures ranging from 2017 kPa to 4000 kPa for the carbon dioxide–water system, while temperatures ranging from 275.1 K to 279.1 K and pressures ranging from 3858 kPa to 6992 kPa were investigated for the methane–water system. The Mole Fraction of carbon dioxide in the bulk liquid phase was found to be constant during the growth period, varying on average by 0.6% and 0.3% at 275.4 K and 279.5 K. Similarly, the Mole Fraction of methane in the bulk liquid phase was found to remain constant during the growth stage, varying on average by 2.0%, 0.8% and 0.2% at 275.1 K, 277.1 K and 279.1 K respectively. The Mole Fraction of the gas hydrate former in the bulk liquid phase was also found to increase with pressure and decrease with temperature, while remaining greater than its hydrate-liquid water equilibrium value. As a result, an alternate formulation of a hydrate growth model is proposed.
C W Chin - One of the best experts on this subject based on the ideXlab platform.
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effect of al Mole Fraction on structural and electrical properties of alxga1 xn gan heterostructures grown by plasma assisted Molecular beam epitaxy
Applied Surface Science, 2011Co-Authors: Sh A Hussein, Abu H. Hassan, Z Hassan, S M Thahab, S S Ng, C W ChinAbstract:Abstract The effect of Al Mole Fractions on the structural and electrical properties of Al x Ga 1− x N/GaN thin films grown by plasma-assisted Molecular beam epitaxy (PA-MBE) on Si (1 1 1) substrates has been investigated by X-ray difFraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and current–voltage ( I – V ) measurements. X-ray results revealed that the AlGaN/GaN/AlN was epitaxially grown on Si substrate. By applying Vegard's law, the Al Mole Fractions of Al x Ga 1− x N samples were found to be 0.11, 0.24, 0.30 and 0.43, respectively. The structural and morphology results indicated that there is a relatively larger tensile strain for the sample with the smallest Al Mole Fraction; while a smaller compressive strain and larger grain size appear with Al Mole Fraction equal to 0.30. The strain gets relaxed with the highest Al Mole Fraction sample. Finally, the linear relationship between the barrier height and Al Mole Fraction was obtained.
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Effect of Al Mole Fraction on structural and electrical properties of AlxGa1−xN/GaN heterostructures grown by plasma-assisted Molecular beam epitaxy
Applied Surface Science, 2011Co-Authors: A. Sh. Hussein, S. S. Ng, Z. Hassan, H. Abu Hassan, S M Thahab, C W ChinAbstract:Abstract The effect of Al Mole Fractions on the structural and electrical properties of Al x Ga 1− x N/GaN thin films grown by plasma-assisted Molecular beam epitaxy (PA-MBE) on Si (1 1 1) substrates has been investigated by X-ray difFraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and current–voltage ( I – V ) measurements. X-ray results revealed that the AlGaN/GaN/AlN was epitaxially grown on Si substrate. By applying Vegard's law, the Al Mole Fractions of Al x Ga 1− x N samples were found to be 0.11, 0.24, 0.30 and 0.43, respectively. The structural and morphology results indicated that there is a relatively larger tensile strain for the sample with the smallest Al Mole Fraction; while a smaller compressive strain and larger grain size appear with Al Mole Fraction equal to 0.30. The strain gets relaxed with the highest Al Mole Fraction sample. Finally, the linear relationship between the barrier height and Al Mole Fraction was obtained.
Mounir Laroussi - One of the best experts on this subject based on the ideXlab platform.
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correlation between helium Mole Fraction and plasma bullet propagation in low temperature plasma jets
Journal of Physics D, 2010Co-Authors: Erdinc Karakas, Mehti Koklu, Mounir LaroussiAbstract:A helium flow dynamics simulation is performed along the propagation region of the plasma bullet to determine the minimum helium Mole Fraction value necessary to sustain its propagation. The plasma bullet launches from a plasma jet device called the 'plasma pencil' driven by unipolar square nanosecond high voltage pulses and propagates in the surrounding air. During its propagation, air Molecules diffuse into the path/helium channel of the plasma bullet. It is found that if the ratio of air Molecules to helium atoms exceeds a certain limit, the plasma bullet propagation is inhibited. In this study, the helium Mole Fraction limits are estimated for different operating conditions of the plasma pencil.
Christophe Leys - One of the best experts on this subject based on the ideXlab platform.
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influence of helium Mole Fraction distribution on the properties of cold atmospheric pressure helium plasma jets
Journal of Applied Physics, 2012Co-Authors: Ranhua Xiong, Qing Xiong, Anton Nikiforov, Patrick Vanraes, Christophe LeysAbstract:The influence of helium Mole Fraction distribution in air on the cold atmospheric plasma jets excited by 1.5 kHz rectangular high voltage pulse is studied in this work. Computational fluid dynamics (CFD) with incorporation of large eddy simulation (LES) model is used to simulate the helium Mole Fraction distribution in air under the helium flow from laminar to turbulent regime with increasing helium outlet velocity. Numerical simulation results are combined with experimental results in order to determine the influence of helium distribution on the cold plasma jets. It reveals that the structure of the helium distribution caused by diffusion or by turbulent mixing in turbulent regime determines the characteristics of the cold plasma jets. On the other hand, the curves of plasma jet length (L) versus helium outlet velocity (V) at different jet diameters (D) are unified in a map of jet Reynolds number (Re = ρHe·V·D/μHe, where μHe is the helium viscosity constant) versus dimensionless plasma jet length (l = L...
Abu H. Hassan - One of the best experts on this subject based on the ideXlab platform.
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effect of al Mole Fraction on structural and electrical properties of alxga1 xn gan heterostructures grown by plasma assisted Molecular beam epitaxy
Applied Surface Science, 2011Co-Authors: Sh A Hussein, Abu H. Hassan, Z Hassan, S M Thahab, S S Ng, C W ChinAbstract:Abstract The effect of Al Mole Fractions on the structural and electrical properties of Al x Ga 1− x N/GaN thin films grown by plasma-assisted Molecular beam epitaxy (PA-MBE) on Si (1 1 1) substrates has been investigated by X-ray difFraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and current–voltage ( I – V ) measurements. X-ray results revealed that the AlGaN/GaN/AlN was epitaxially grown on Si substrate. By applying Vegard's law, the Al Mole Fractions of Al x Ga 1− x N samples were found to be 0.11, 0.24, 0.30 and 0.43, respectively. The structural and morphology results indicated that there is a relatively larger tensile strain for the sample with the smallest Al Mole Fraction; while a smaller compressive strain and larger grain size appear with Al Mole Fraction equal to 0.30. The strain gets relaxed with the highest Al Mole Fraction sample. Finally, the linear relationship between the barrier height and Al Mole Fraction was obtained.
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The Energy Band Gap of AlxGa1-xN Thin Films as a Function of Al-Mole Fraction
2006 IEEE International Conference on Semiconductor Electronics, 2006Co-Authors: S. S. Ng, Z. Hassan, Abu H. HassanAbstract:In this work, the effects of Al Mole Fraction on energy band gap (Eg) of AlxGa1-xN epilayers grown on sapphire substrate are investigated. Attention is focused on the Ga-rich composition samples (0≤x≤0.10). The Al-Mole Fraction is determined by high-resolution X-ray difFraction (HR-XRD) spectroscopy. Ultraviolet-visible (UV-VIS) transmission and micro-photoluminescence (μ-PL) spectroscopy are employed to determine the energy band gap of the samples. The XRD results revealed that the Bragg angle of the rocking curve (RC) peak gradually increases as the Al-Mole Fraction increases, indicating the reductions in the lattice constant c of the alloys. By the application of Vegard's law, the Al-Mole Fractions of AlxGa1-xN samples have been calculated. Overall, the UV-VIS transmission and μ-PL results showed that as the Al-Mole Fraction increases, blue shifts of the absorption edge and band edge emission are observed in all samples. These indicate the strong dependence of the band gap energy of AlxGa1-xN on the Al-Mole Fraction. Finally, the band gap energy of the AlxGa1-xN as a function of Al-Mole Fraction have been plotted and the energy band gap bowing parameter of 14.62 eV is obtained from the best fit of the non-linear interpolation of the UV-VIS transmission and the PL data.
