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    The effect of ethane on the performance of commercial polyphenylene oxide and cardo-type polyimide hollow fiber membranes in CO 2/CH 4 separation applications

    , Article Korean Journal of Chemical Engineering ; Volume 27, Issue 6 , 2010 , Pages 1876-1881 ; 02561115 (ISSN) Chenar, M. P ; Savoji, H ; Soltanieh, M ; Matsuura, T ; Tabe, S ; Sharif University of Technology
    2010
    Abstract
    Impurities such as hydrogen sulfide, water vapor and heavy hydrocarbons in natural gas have considerable effects on the membrane performance. Small amounts of condensable and polymer soluble components in the feed gas cause swelling or plasticization of glassy membranes, leading to a reduction in membrane selectivity. In the present research the influence of ethane was investigated on the permeance and selectivity of two commercially available hollow fiber membranes, namely Cardo-type polyimide and PPO hollow fibers for CO 2/CH 4 separations. It was concluded that the gas mixture permeation rate was increased in the presence of C 2H 6. However, the CO 2/CH 4 separation factors remained... 

    A gas cartel in the global market? Hype or reality

    , Article International Journal of Energy Economics and Policy ; Volume 9, Issue 6 , 2019 , Pages 296-304 ; 21464553 (ISSN) Farimani, F. M ; Mirnezami, S. R ; Maleki, A ; Sharif University of Technology
    Econjournals  2019
    Abstract
    In late 2018, Qatar -as a key player in the global gas market-announced that it has decided to quit the Organisation of the Petroleum Exporting Countries (OPEC) and rather will be focussing on its gas industry. Such a decision, drew the attentions once again and after a decade to the issue of gas cartel formation. The basic question of this paper is under which conditions gas cartel formation is feasible in presence of an oil cartel. Using a game theory framework the paper models the interaction of countries that export both gas and oil and are member of OPEC with those that export only gas or oil. Results indicate that gas cartel formation is feasible but under very vulnerable conditions.... 

    A gas cartel in the global market? Hype or reality

    , Article International Journal of Energy Economics and Policy ; Volume 9, Issue 6 , 2019 , Pages 296-304 ; 21464553 (ISSN) Farimani, F. M ; Mirnezami, S. R ; Maleki, A ; Sharif University of Technology
    Econjournals  2019
    Abstract
    In late 2018, Qatar -as a key player in the global gas market-announced that it has decided to quit the Organisation of the Petroleum Exporting Countries (OPEC) and rather will be focussing on its gas industry. Such a decision, drew the attentions once again and after a decade to the issue of gas cartel formation. The basic question of this paper is under which conditions gas cartel formation is feasible in presence of an oil cartel. Using a game theory framework the paper models the interaction of countries that export both gas and oil and are member of OPEC with those that export only gas or oil. Results indicate that gas cartel formation is feasible but under very vulnerable conditions.... 

    A simple correlation to estimate natural gas viscosity

    , Article Journal of Natural Gas Science and Engineering ; Volume 20 , September 2014 , Pages 50–57 Jarrahian, A ; Heidaryan, E ; Sharif University of Technology
    Abstract
    A general investigation of the viscosity of natural gas as a function of temperature, pressure and composition was carried out to develop a generalized correlation. The model obtained was based on 3231 data points of 29 multicomponent mixtures in wide ranges of pressures (0.1-137.8MPa), temperatures (241-473K) and specific gravities (0.573-1.337). Correction terms for non-hydrocarbons of hydrogen sulfide, carbon dioxide and nitrogen were up to 70, 54.4 and 15.8 of mole percent, respectively. The arithmetic average of the model's absolute error was found to be 5.05%, which is acceptable in engineering calculations and has superiority over other methods in its class  

    Nuclear magnetic resonance -based metabolomics analysis of patients exposed to sulfur mustard in different stages using random forest method

    , Article Koomesh ; Volume 17, Issue 3 , 2016 , Pages 701-706 ; 16087046 (ISSN) Nobakht M. Gh., B. F ; Aliannejad, R ; Oskouie, A. A ; Fathi, F ; Sahakhah, H. A ; Rezaei Tavirani, M ; Sharif University of Technology
    Semnan University of Medical Sciences 
    Abstract
    Metabolomics is a powerful technique for determination of biomarkers. Here, we aimed to determine discriminatory metabolomic profiles in different stages of sulfur mustard-exposed patients (SMEPs). Materials and methods: Nuclear magnetic resonance spectroscopy was used to analyze serum samples from 17 SMEPs (normal group patients) and 17 SMEPs (severe group patients). Multivariate statistical analysis using random forest (RF) was performed on a ‘training set’ (70% of the total sample) in order to produce a discriminatory model classifying two groups of patients, and the model tested in the remaining subjects. Results: A classification model was derived using data from the training set with... 

    Hydrogen sensing properties of pure and Pd activated WO3 nanostructured films

    , Article Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry ; Volume 37, Issue 6 , 2007 , Pages 453-456 ; 15533174 (ISSN) Ghadiri, E ; Iraji zad, A ; Razi, F ; Sharif University of Technology
    2007
    Abstract
    Pure and Pd-doped WO3 Nanocrystalline tungsten oxide films on alumina substrates were prepared via sol-gel method from peroxopolytungstic acid. AFM, XRD, SEM, XPS methods were used to determine the surface morphology, grain size and layer composition. XRD analysis showed WO3 nanocrystalline particles in monoclinic phase and with average size of about 333nm, which was consistent with SEM analysis results. Sensing properties of samples toward H2 gas was studied. The sensitivity of WO3 nanocrystalline films was about 4 at 2300ppm (0.2%) H2 gas. Introducing Pd to the system led to an increase in the sensitivity about 2 orders of magnitude. The sensitivity of Pd: WO3 was about 400 at 2300ppmH2  

    Wettability alteration of reservoir rocks to gas wetting condition: a comparative study

    , Article Canadian Journal of Chemical Engineering ; Volume 96, Issue 4 , April , 2018 , Pages 997-1004 ; 00084034 (ISSN) Erfani Gahrooei, H. R ; Ghazanfari, M. H ; Karimi Malekabadi, F ; Sharif University of Technology
    Wiley-Liss Inc  2018
    Abstract
    Productivity of gas condensate reservoirs reduces significantly due to the near wellbore condensate/water blockage phenomenon. A novel, permanent solution to alleviate this problem is near wellbore wettability alteration of reservoir rocks to preferentially gas wetting conditions; industrial chemical materials are good candidates for this purpose, because of their eco-friendly characteristics, economical price, and mass production. In this paper, a comparative study is conducted on two industrial fluorinated chemicals, MariSeal 800 and SurfaPore M. Static and dynamic contact angle measurements, spontaneous imbibition, and core flooding tests were conducted to investigate the effect of... 

    Application of direct simulation Monte Carlo for development of micro gas sensor

    , Article Bulgarian Chemical Communications ; Volume 50, Issue 2 , 2018 , Pages 298-305 ; 08619808 (ISSN) Gerdroodbary, M. B ; Ganji, D. D ; Taeibi Rahni, M ; Vakilipour, Sh ; Moradi, R ; Sharif University of Technology
    Bulgarian Academy of Sciences  2018
    Abstract
    Development of a new micro gas sensor is essential for the analysis of the outcome of gas separation devices. In this paper, direct simulation Monte Carlo (DSMC) modeling of low-pressure gas sensor was performed to investigate the effect of physical parameters on the performance and main characteristics of this type of actuator in various operating conditions. Extensive parametric studies were done and the effect of ambient pressure, temperature and gap of arms were comprehensively investigated. Our findings showed that gap size significantly influences the flow features and force generation inside the sensor. © 2018 Bulgarian Academy of Sciences, Union of Chemists in Bulgaria  

    Structural and transport properties of polydimethylsiloxane based polyurethane/silica particles mixed matrix membranes for gas separation

    , Article Korean Journal of Chemical Engineering ; Volume 31, Issue 5 , 2014 , Pages 841-848 ; ISSN: 02561115 Semsarzadeh, M. A ; Ghalei, B ; Fardi, M ; Esmaeeli, M ; Vakili, E ; Sharif University of Technology
    Abstract
    Mixed matrix membranes of synthesized polyurethane (PU) based on toluene diisocyanate (TDI), polydimethylsiloxane (PDMS) and polytetramethylene glycol (PTMG) with polyvinyl alcohol based polar silica particles were prepared by solution casting technique. The homogeneity and thermal properties of the prepared PDMS-PU/silica membranes were characterized using scanning electron microscope (SEM), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The SEM micrographs confirmed the distribution of silica particles in the polymer matrix without agglomerations. Gas permeation properties of membranes with different silica contents were studied for pure CO2, CH4, O2, He... 

    Prediction of methane uptake on different adsorbents in adsorbed natural gas technology using a rigorous model

    , Article Energy and Fuels ; Vol. 28, issue. 10 , September , 2014 , p. 6299-6314 Soroush, E ; Mesbah, M ; Shokrollahi, A ; Bahadori, A ; Ghazanfari, M. H ; Sharif University of Technology
    Abstract
    One of the most promising methods for transporting natural gas and overcoming its low energy density is adsorbed natural gas (ANG) technology. ANG technology is highly dependent on the perfect conception of adsorption isotherms in different operational conditions and on different adsorbents. In this study, the utilization of a novel mathematical model of least squares support vector machine (LSSVM) for accurate prediction of adsorption isotherm has been examined. The considered variables were temperature, pressure and type of adsorbents. A data set containing 670 experimental data points of methane adsorption on 10 different adsorbents in a broad range of temperature and pressure were used... 

    Simulation & process optimization of an ethane recovery plant

    , Article 18th International Congress of Chemical and Process Engineering, CHISA 2008, Prague, 24 August 2008 through 28 August 2008 ; 2008 Ghassemian, S ; Farhadi, F ; DEZA; CEPRO; BorsodChem MCHZ, s.r.o.; Zentiva; Ceska rafinerska ; Sharif University of Technology
    2008
    Abstract
    Optimization of ethane recovery in Phases 4 and 5 of Assalouyeh was studied. The influence of some parameters on the ethane recovery and the sensitivity analysis were determined. The effect of the parameter variation on the neighboring unit showed that a significant energy saving for compressor power consumption could be achieved. Some of the operating conditions of this unit were modified, including columns pressure, split fraction, minimum approach temperature, and expander power. This led to a 6% increase in ethane yield. This is an abstract of a paper presented at the 18th International Congress of Chemical and Process Engineering (Prague, Czech Republic 8/24-28/2008)  

    Optimal gas distribution network using minimum spanning tree

    , Article Proceedings - 2010 IEEE 17th International Conference on Industrial Engineering and Engineering Management, IE and EM2010, 29 October 2010 through 31 October 2010 ; October , 2010 , Pages 1374-1377 ; 9781424464814 (ISBN) Mahdavi, I ; Mahdavi Amiri, N ; Makui, A ; Mohajeri, A ; Tafazzoli, R ; Sharif University of Technology
    2010
    Abstract
    Here, a case study of natural gas network is conducted. We design an optimal distribution network of natural gas. Our proposed network is composed of stations reducing gas pressure to desirable pressure using consumer's viewpoint. By using minimum spanning tree (MST) technique, an optimal distribution network among stations and consumers is constructed. Our aim is to determine both locations and types of stations minimizing location-allocation costs in the network. A case study in Mazandaran Gas Company in Iran is made to assess the validity and effectiveness of the proposed model  

    Near wellbore thermal effects in a tight gas reservoir: Impact of different reservoir and fluid parameters

    , Article Journal of Unconventional Oil and Gas Resources ; Volume 16 , 2016 , Pages 1-13 ; 22133976 (ISSN) Shad, S ; Holmgrün, C ; Calogirou, A ; Sharif University of Technology
    Elsevier Ltd  2016
    Abstract
    Temperature changes in and around the wellbore could lead to significant well performance and flow assurance issues. Despite its importance, near wellbore temperature change due to gas production and its importance on well performance is not well understood. Reduction of temperature in the near well bore section, could potentially lead to hydrate formation and as a result reduction of well performance. This work is aimed at evaluating the thermal behaviour in the near wellbore region of a low to tight permeability gas reservoir (ranging between 0.02 and 10 mD) during its natural depletion. The study is conducted by using a thermal-compositional simulator. The process required to simulate... 

    Thermodynamic analysis of a hybrid gas turbine/thermoacoustic heat pump/refrigeration engine

    , Article International Journal of Exergy ; Volume 15, Issue 2 , 1 November , 2014 , Pages 152-170 ; ISSN: 17428297 Ghorbanian, K ; Karimi, M ; Sharif University of Technology
    Abstract
    Possible performance enhancement of small gas turbine power plants through the application of thermoacoustic systems is examined. The thermoacoustic subsystem is powered only by the waste heat of the gas turbine. Two different gas turbine configurations are considered: a Thermoacoustic refrigerator assisted gas turbine (TRG) and a Combined thermoacoustic heat pump and refrigeration assisted gas turbine (CTHRG). Exergy, rational efficiency and relative power gain (RPG) of these configurations are compared with those from the recuperated gas turbine engine. The results indicate that the integration of thermoacoustic system to a simple gas turbine cycle will not only enhance the energy/exergy... 

    Fabrication of gas ionization sensor based on titanium oxide nanotube arrays

    , Article Applied Physics A ; Volume 115, Issue 4 , June , 2014 , pp 1387-1393 ; 1432-0630 Nikfarjam, A. (Alireza) ; Mohammadpour, R. (Raheleh) ; Iraji Zad, A. (Azam) ; Sharif University of Technology
    Abstract
    Gas sensors have been fabricated based on field ionization from titanium oxide nanotubes grown on titanium foil. Ordered nanaotube arrays of titanium oxides were grown by the anodization method. We measured breakdown voltages and discharge currents of the device for various gases. Our gas ionization sensors (GIS) presented good sensitivity, selectivity, and short response time. The GISs based on TiO2 nanotube arrays showed lower breakdown voltage, higher discharge current, and good selectivity. An excellent response observed for Ar compared to other gases. Besides, by introducing 2 % CO and 4 % H2 to N2 flow gas, the amount of breakdown voltage shifts about 20 and 70 volts to the lower... 

    Natural gas hydrate promotion capabilities of toluene sulfonic acid isomers

    , Article Polish Journal of Chemical Technology ; Vol. 16, Issue. 1 , 2014 , pp. 97-102 ; ISSN: 1899-4741 Jarrahian, A ; Heidaryan, E ; Sharif University of Technology
    Abstract
    The purpose of this study was to investigate the natural gas hydrate promotion capabilities of the hydrotrope Toluene Sulfonic Acid (TSA) isomers as an additive. The capabilities of TSA isomers were measured with different concentrations. The optimum additive concentration for hydrate formation was determined for the given pressure, temperature, mixing condition, and cooling time. The natural gas hydrate promotability of para-TSA was found to be 20% and 35% more than meta-TSA and ortho-TSA respectively at the optimum concentration. Beyond the optimum TSA concentration, the hydrate formation declined as the ice formation reduced the overall gas-to-water volume ratio in the hydrates  

    Estimation of demand function for natural gas in Iran: Evidences based on smooth transition regression models

    , Article Economic Modelling ; Vol. 36, issue , 2014 , pp. 341-347 Kani, A. H ; Abbasspour, M ; Abedi, Z ; Sharif University of Technology
    Abstract
    This paper attempts to study the demand function of natural gas in Iran using smooth transition regression model (STR). To this end, gross domestic productions (GDP), real price of natural gas and temperature have been employed as variables explaining the natural gas demand from 1971 to 2009. The results indicate that natural gas demand follows an LSTR1 nonlinear two-regime model if the real price of natural gas is considered as the transition variable. Estimation results also indicate that the slope parameter approximately equals the high value of 10 and the threshold value is 31.82. Rials. 111 USD=24,700 Rials (IRR) at April 2013. per one cubic meter consumption of natural gas. The results... 

    Experimental investigation and modeling of asphaltene precipitation due to Gas Injection

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 31, Issue 1 , 2012 , Pages 89-98 ; 10219986 (ISSN) Moradi, S ; Rashtchian, D ; Ganjeh Ghazvini, M ; Emadi, M. A ; Dabir, B ; Sharif University of Technology
    2012
    Abstract
    Asphaltene instability is one of the major problems in gas injection projects throughout the world. Numerous models have been developed to predict asphaltene precipitation; The scaling equation is an attractive tool because of its simplicity and not involving complex properties of asphaltene. In this work, a new scaling model is presented to account for asphaltene precipitation due to gas injection at reservoir conditions. Extensive published data from literature have been used in model preparation. To check predictive capability of the equation, miscible gas injection experiments are conducted for a southwest Iranian oil reservoir. Experimental results show that methane injection has... 

    Computational modeling of intraocular gas dynamics

    , Article Physical Biology ; Volume 12, Issue 6 , 2015 ; 14783967 (ISSN) Noohi, P ; Abdekhodaie, M. J ; Cheng, Y. L ; Sharif University of Technology
    Institute of Physics Publishing  2015
    Abstract
    The purpose of this study was to develop a computational model to simulate the dynamics of intraocular gas behavior in pneumatic retinopexy (PR) procedure. The presented model predicted intraocular gas volume at any time and determined the tolerance angle within which a patient can maneuver and still gas completely covers the tear(s). Computational fluid dynamics calculations were conducted to describe PR procedure. The geometrical model was constructed based on the rabbit and human eye dimensions. SF6 in the form of pure and diluted with air was considered as the injected gas. The presented results indicated that the composition of the injected gas affected the gas absorption rate and gas... 

    Condensate blockage study in gas condensate reservoir

    , Article Journal of Natural Gas Science and Engineering ; Volume 33 , 2016 , Pages 634-643 ; 18755100 (ISSN) Rahimzadeh, A ; Bazargan, M ; Darvishi, R ; Mohammadi, A. H ; Sharif University of Technology
    Elsevier  2016
    Abstract
    The effect of condensate blockage on the pressure drop near the well bore has been studied. Two types of single well simulations have been conducted and pressure drop due to condensate blockage has been quantified based on variation of gas relative permeabilities in near well bore area. The relationship of condensate banking pressure drop, gas rate and reservoir quality has been presented. It is shown that for a poor reservoir quality, condensate blockage can increase the pressure drop up to 200% of the pressure drop in the tubing