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A Numerical Approach for Multicomponent Vapor Solid Equilibrium Calculations in Gas Hydrate Formation

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Journal of Natural Gas Chemistry 2007年第1期16卷 16-21页

作者： Alireza bahadori Department of Petroleum Engineering National Iranian South Oil Co.AhwazP.O.Box 61735-1338Iran

A new numerical approach has been developed for vapor solid equilibrium calculations and for predicting vapor solid equilibrium constant and composition of vapor and solid phases in gas hydrate formation. Equation of state methods generally do a good job of determining vapor phase properties, but for solid phase it is much more difficult and inaccurate. This proposed new model calculates vapor solid equilibrium constant and vapor and solid phase composition as a function of temperature and partial pressure. The results of this proposed numerical approach, for vapor solid equilibrium, have a good agreement with the available reported data. This new numerical model also has an advantage to tune coefficients, to cover different sets of experimental data accurately.

关键词： numerical model vapor solid equilibrium hydrate multicomponent system

PREPARATION, CHARACTERIZATION AND ADHESIVE PROPERTIES OF DI-AND TRI-HYDROXY BENZOYL CHITOSAN NANOPARTICLES

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Chinese Journal of Polymer Science 2013年第4期31卷 649-659页

作者： Mohamad Taghi Taghizadeh Ali bahadori Department of Physical Chemistry Faculty of ChemistryUniversity of TabrizTabrizIran

Modified chitosans with 3,4-di-hydroxy benzoyl groups （CS-DHBA） and 3,4,5-tri-hydroxy benzoyl groups （CS- THBA） were synthesized and their nanoparticles were prepared via ionic crosslinking by tripolyphosphate （TPP）. The chemical structure and degree of substitution （DS） of di- and tri-hydroxy benzoyl chitosans are determined by FTIR and IH- NMR spectroscopy. The morphology of particles, size distribution and zeta potential of nanoparticles were studied using transmission electron microscopy （TEM） and dynamic light scattering （DLS）, respectively. The mean diameters of particles of CS-DHBA and CS-THBA nanoparticles were 144 nm and 112 nm, respectively. It was found that the particles size decreased slightly with decreasing the degree of substitution and increasing degree of deacetylation （DD）, due to increasing of ionic crosslinking of ammonium ions and polyanions of tripolyphosphate. The TEM photographs of CS-DHBA show that these particles are spherical in shape, but the particles of CS-THBA show some aggregation. In addition, the solubility and the mechanical properties of the prepared modified chitosans and their nanoparticles were evaluated for bio-adhesive and biomedical application. The results of solubility tests indicated that, the CS-DHBA and CS-THBA have higher solubility at pH 〉 7 comparing to CS. Also the CS-DHBA, CS-THBA and their nanoparticles showed a significant adhesive capacity and enhanced tensile strength and tensile modulus.

关键词： Nanoparticles Di- and tri-hydroxy benzoyl chitosans Ionic cross linking Solubility Adhesive properties.

Novel predictive tool for accurate estimation of packed column size

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Journal of Natural Gas Chemistry 2010年第2期19卷 146-150页

作者： Alireza bahadori Hari B.Vuthaluru Department of Chemical Engineering Curtin University of TechnologyGPO Box U1987PerthWA 6845Australia

Traditionally the majority of fractionation columns in natural gas processing plants were equipped with *** an option to trayed columns is to use *** columns offer a larger surface area per unit volume for mass transfer and the continuous gas to liquid contact throughout the column rather than at specific levels （such as in tray columns）.For process design purposes,it is essential to estimate the pressure drop for enabling the proper operation of packed *** this study,a simple generalized pressure drop correlation （GPDC） which is easier than existing approaches requiring more complicated and longer computations is developed for sizing randomly packed fractionation columns for pressure drops up to 150 mm water per meter of *** correlation can be used to estimate pressure drop for a given loading and column ***,for a given pressure drop the diameter can be *** predictions from the proposed correlation have been compared with reported data and found good agreement with average absolute deviation hovering around 4.9%.The proposed predictive tool is superior owing to its accuracy and clear numerical background,wherein the relevant coefficients can be retuned quickly if new and more accurate data are available in the *** proposed simple-to-use approach can be of immense practical value for the engineers and scientists to have a quick check on the pressure drop in packed columns for a given loading and column *** particular,gas engineers would find the proposed approach can be used very friendly involving no complex expressions with transparent and easy-to-handle calculation steps.

关键词： packed columns packing pressure drop flooding design principles

Study of the O-mode in a relativistic degenerate electron plasma

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Plasma Science and Technology 2017年第3期19卷 34-41页

作者： Kalsoom azra Muddasir ALI Azhar HUSSAIN School of Natural Sciences (SNS) National University of Sciences and Technology (NUST) Islamabad 44000 Pakistan Department of Physics Quaid-i-Azam University Islamabad 44000 Pakistan

Using the linearized relativistic Vlasov-Maxwell equations,a generalized expression for the plasma conductivity tensor is *** dispersion relation for the O-mode in a relativistic degenerate electron plasma is investigated by employing the Fermi-Dirac distribution *** propagation characteristics of the O-mode（cut offs,resonances,propagation regimes,harmonic structure） are examined by using specific values of the density and the magnetic field that correspond to different relativistic dense ***,it is observed that due to the relativistic effects the cut off and the resonance points are shifted to low frequency values,as a result the propagation regime is *** dispersion relations for the non-relativistic and the ultra-relativistic limits are also presented.

关键词： O-mode degenerate plasma white dwarf

Analyzing solubility of acid gas and light alkanes in triethylene glycol

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Journal of Natural Gas Chemistry 2008年第1期17卷 51-58页

作者： Alireza bahadori Hari B.Vuthaluru Saeid Mokhatab Department of Chemical Engineering Curtin University of TechnologyGPO Box 1987PerthWA 6845Australia Process Technology Manager Tehran Raymand Consulting EngineersTehranIran

Physical solvents such as ethylene glycol （EG）, diethylene glycol （DEG）, and triethylene glycol （TEG） are commonly used in wet gas dehydration processes with TEG being the most popular due to ease of regeneration and low solvent losses. Unfortunately, TEG absorbs significantly more hydrocarbons and acid gases than EG or DEG. Quantifying this amount of absorption is therefore critical in order to minimize hydrocarbon losses or to optimize hydrocarbon recovery depending on the objective of the process. In this article, a new correlation that fully covers the operating ranges of TEG dehydration units is developed in order to determine the solubility of light alkanes and acid gases in TEG solvent. The influence of several parameters on hydrocarbon and acid gas solubility including temperature, pressure, and solvent content is also examined.

关键词： solubility triethylene glycol acid gas hydrocarbon gas dehydration

Regressive approach for predicting bearing capacity of bored piles from cone penetration test data

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Journal of Rock Mechanics and Geotechnical Engineering 2015年第5期7卷 584-592页

作者： Iyad S. Alkroosh Mohammad bahadori Hamid Nikraz Alireza bahadori Department of Civil Engineering College of Engineering Al-Qadissiya University School of Soil Science and Engineering University of Tehran Department of Civil Engineering Curtin University School of Environment Science and Engineering Southern Cross University

In this study, th e least sq u are su p p o rt v ecto r m achine （LSSVM） alg o rith m w as applied to predicting th ebearing capacity o f b ored piles e m b ed d ed in sand an d m ixed soils. Pile g eo m etry an d cone p e n e tra tio nte s t （CPT） resu lts w ere used as in p u t variables for pred ictio n o f pile bearin g capacity. The d ata u se d w erecollected from th e existing litera tu re an d consisted o f 50 case records. The application o f LSSVM w ascarried o u t by dividing th e d ata into th re e se ts： a train in g se t for learning th e pro b lem an d obtain in g arelationship b e tw e e n in p u t variables an d pile bearin g capacity, and testin g an d validation sets forevaluation o f th e predictive an d g en eralization ability o f th e o b tain ed relationship. The predictions o f pilebearing capacity by LSSVM w ere evaluated by com paring w ith ex p erim en tal d ata an d w ith th o se bytrad itio n al CPT-based m eth o d s and th e gene ex pression pro g ram m in g （GEP） m odel. It w as found th a t th eLSSVM perform s w ell w ith coefficient o f d eterm in atio n , m ean, an d sta n d ard dev iatio n equivalent to 0.99,1.03, an d 0.08, respectively, for th e testin g set, an d 1, 1.04, an d 0.11, respectively, for th e v alidation set. Thelow values o f th e calculated m ean squared e rro r an d m ean ab so lu te e rro r indicated th a t th e LSSVM w asaccurate in p redicting th e pile bearing capacity. The results o f com parison also show ed th a t th e p roposedalg o rith m p red icted th e pile bearin g capacity m ore accurately th a n th e trad itio n al m eth o d s including th eGEP m odel.

关键词： Bored piles Cone penetration test(CPT) Bearing capacity Least square support vector machine(LSSVM) Training Validation

Rapidly Estimating Natural Gas Compressibility Factor

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Journal of Natural Gas Chemistry 2007年第4期16卷 349-353页

作者： Alireza bahadori Saeid Mokhatab Brian F.Towler Department of Chemical Engineering Curtin University of Technology GPO Box 1987PerthWA 6845Australia Process Technology Department Tehran Raymand Consulting Engineers TehranIran Chemical and Petroleum Engineering Department University of Wyoming Laramie.WYUSA

Natural gases containing sour components exhibit different gas compressibility factor （Z） behavior than do sweet gases. Therefore, a new accurate method should be developed to account for these differences. Several methods are available today for calculating the Z-factor from an equation of state. However, these equations are more complex than the foregoing correlations, involving a large number of parameters, which require more complicated and longer computations. The aim of this study is to develop a simplified calculation method for a rapid estimating Z-factor for sour natural gases containing as much as 90% total acid gas. In this article, two new correlations are first presented for calculating the pseudo- critical pressure and temperature of the gas mixture as a function of the gas specific gravity. Then, a simple correlation on the basis of the standard gas compressibility factor chart is introduced for a quick estimation of sweet gases＇ compressibility factor as a function of reduced pressure and temperature. Finally, a new corrective term related to the mole fractions of carbon dioxide and hydrogen sulfide is developed.

关键词： natural gas compressibility factor sour gas critical pressure critical temperature

Visible light-driven photo remediation of hazardous cationic dye via Ce-doped WO_(3) nanostructures

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Journal of Rare Earths 2024年第5期42卷 869-878,I0003页

作者： azra Haroon Kaseed Anwar Arham S.Ahmed Department of Physics Aligarh Muslim University202002AligarhIndia Interdisciplinary Nanotechnology Centre Aligarh Muslim University202002AligarhIndia

Ce-doped WO_(3) nanoparticles were successfully synthesized by the sol-gel method and characterized through advanced characterization *** high resolution transmission electron microscopy(HRTEM)and scanning electron microscopy(SEM)results show a reduction in the agglomeration of nanoparticles upon *** energy dispersive X-ray(EDX)analysis validates the existence of the Ce element in all the doped samples.X-ray photoelectron spectroscopy(XPS)and Raman spectra justify the presence of structural defects(oxygen vacancies)and successful formation of the monoclinic WO_(3) phase,*** Kubelka-Munk function indicates a decrease in band gap with doping,while photoluminescence(PL)spectra show intense visible and UV emissions,Significantly,all doped samples exhibit higher photocatalytic performance than pure WO_(3) nanoparticles,with the 6 wt%Ce-doped sample displaying the highest degradation *** with Ce can help to increase the surface area of WO_(3),thereby improving its photoactivity,Moreover,a correlation between PL and photocatalysis is established in the light of oxygen vacancies suggesting a direct dependence of high photocatalytic activity on strong PL signals of WO_(3) *** experiments further reveal that the degradation process is primarily driven by active species,providing insight into a plausible photocatalytic mechanism.

关键词： WO_(3) Rare-earth element Environmental crisis Oxygen vacancies Luminescence Photocatalysis

A novel correlation for estimation of hydrate forming condition of natural gases

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Journal of Natural Gas Chemistry 2009年第4期18卷 453-457页

作者： Alireza bahadori Hari. B. Vuthaluru Department of Chemical Engineering Curtin University of Technology

An inherent problem with natural gas production or transmission is the formation of gas hydrates, which can lead to safety hazards to production/transportation systems and to substantial economic risks. Therefore, an understanding of conditions where hydrates form is necessary to overcome hydrate related issues. Over the years, several models requiring more complicated and longer computations have been proposed for the prediction of hydrate formation conditions of natural gases. For these reasons, it is essential to develop a reliable and simple-to-use method for oil and gas practitioners. The purpose of this study is to formulate a novel empirical correlation for rapid estimation of hydrate formation condition of sweet natural gases. The developed correlation holds for wide range of temperatures （265 - 298 K）, pressures （1200 to 40000 kPa） and molecular weights （16-29）. New proposed correlation shows consistently accurate results across proposed pressure, temperature and molecular weight ranges. This consistency could not be matched by any of the widely accepted existing correlations within the investigated range. For all conditions, new correlation showed average absolute deviation to be less than 0.2% and provided much better results than the widely accepted existing correlations.

关键词： gas hydrate correlation natural gas