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Methane Conversion to Higher and Valuable Hydrocarbons by Non-thermal Plasma
, M.Sc. Thesis Sharif University of Technology ; Saddighi Bonabi, Rasoul (Supervisor)
Abstract
Methane conversion into higher hydrocarbons has been investigated by non-thermal plasma. The most important advantages of utilizing this type of plasma are atmospheric pressure and ambient temperature of the operating system. Without any catalysts and with pure methane used as the feed gas, a stable 20 kilohertz spark discharge leads to an acetylene selectivity of 90.4 % with 54.5 % of methane conversion at a methane fow rate of 33 ml/min and a specific input energy of 54 kJ/L. Other components such as hydrogen, ethylene and ethane are also formed in the process as by-products. These remarkable results expose superiority of spark plasma in comparison with other types of non-thermal...
Kinetic Study of Heterogeneous and Homogeneous Catalytic Reactions in Molecular and Ionic Solvents and Their Mixtures
, Ph.D. Dissertation Sharif University of Technology ; Gholami, Mohammad Reza (Supervisor) ; Habibi Yangjeh, Aziz (Supervisor)
Abstract
Solvatochromic parameters (ETN: normalized polarity parameter, π*: dipolarity/polarizability, β: hydrogen-bond acceptor basicity, α: hydrogen-bond donor acidity) have been determined for binary mixtures of propan-2-ol, propan-1-ol, ethanol, methanol and water with recently synthesized ionic liquid (2-hydroxyethylammonium formate) at 25 ◦C. The applicability of nearly ideal combined binary solvent/Redlich-Kister equation was proved for the correlation of various solvatochromic parameters with solvent composition. Solute-solvent and solvent-solvent interactions were applied to interpret the results. Heterogeneous catalytic hydrogenation of cyclohexene, catalyzed by Pt/Al2O3, was carried out in...
A new cubic equation of state for sweet and sour natural gases even when composition is unknown
, Article Fuel ; Vol. 134, issue , 2014 , pp. 333-342 ; ISSN: 00162361 ; Heidaryan, E ; Sharif University of Technology
Abstract
In this paper, the Heidaryan and Jarrahian equation of state (Heidaryan and Jarrahian, 2013) has been adapted as a first worldwide cubic EOS to calculate the density of dry natural gases, wet natural gases, and single-phase gas condensates "sweet and sour mixtures" (up to 73.85, 97.63 and 38.37 mol percent of H2S, CO2, and N2 respectively) even when the gas composition is unknown, through new gas specific gravity correlation equations. Correction terms of water content as high as 10 mol percent of H2O and hythane (natural gas + hydrogen) as high as 74.9 mol percent of H2 were obtained. The equation of state was validated with 8985 experimental compressibility factor data points from 308...
Process optimization for mineral carbonation in aqueous phase
, Article International Journal of Mineral Processing ; Vol. 130 , July , 2014 , pp. 20-27 ; ISSN: 03017516 ; Shayegan, J ; Bu, J ; Yeo, T. Y ; Sharratt, P ; Sharif University of Technology
Abstract
Carbon dioxide sequestration by a pH-swing carbonation process was considered in this work. A multi-step aqueous process is described for the fractional precipitation of magnesium carbonate and other minerals in an aqueous system at room temperature and atmospheric pressure. With the aim to achieve higher purity and deliver more valuable mineral products, the process was split into four steps. The first step consists of Mg leaching from the magnesium silicate in a stirred vessel using 1 M HCl at 80 °C, followed by a three step precipitation in reactors in sequence to remove Fe(OH)3, then Fe(OH)2 and other divalent ions, and finally MgCO3 nucleation and growth. Hydrated magnesium carbonate...
The modeling of kinetics and catalyst deactivation in propane dehydrogenation over Pt-Sn/γ-Al2O3 in presence of water as an oxygenated additive
, Article Petroleum Science and Technology ; Vol. 32, issue. 10 , Mar , 2014 , pp. 1139-1149 ; ISSN: 10916466 ; Fattahi, M ; Khorasheh, F ; Sharif University of Technology
Abstract
A reduction in catalyst's activity with time-on-stream and the formation of side products are two of the problems associated with catalytic propane dehydrogenation (PDH). Previous studies have indicated that the presence of small amounts of oxygenated additives such as water can reduce coke formation and enhance catalyst activity. The aim of the present work was to develop an appropriate kinetic model for PDH over a commercial Pt-Sn/γ-Al 2O3 catalyst in the presence of small amounts of water. Experimental data were obtained from a previous study where catalytic PDH was carried out in a bench scale reactor system at atmospheric pressure in the temperature range of 575-620°C in the presence of...
Evaluating the performance of artificial neural network model in downscaling daily temperature, precipitation and wind speed parameters
, Article International Journal of Environmental Research ; Vol. 8, issue. 4 , 2014 , p. 1223-1230 ; Abbaspour, M ; Soltaniyeh, M ; Hosseinzadeh, F ; Abedi, Z ; Sharif University of Technology
Abstract
Numerous studies yet have been carried out on downscaling of the large-scale climate data using both dynamical and statistical methods to investigate the hydrological and meteorological impacts of climate change on different parts of the world. This study was also conducted to investigate the capability of feedforward neural network with error back-propagation algorithm to downscale the provincial segmentation of Iran (30 provinces) on a daily scale. This model was proposed for the downscaling daily temperature, precipitation and wind speed data, and it was calibrated and verified by using the daily outputs derived from the National Center for Environmental Prediction (NCEP) database...
Modeling of coke formation and catalyst deactivation in propane dehydrogenation over a commercial Pt-Sn/γ-Al2O3 catalyst
, Article Petroleum Science and Technology ; Volume 31, Issue 23 , 2013 , Pages 2451-2462 ; 10916466 (ISSN) ; Soltani, M ; Farjoo, A ; Khorasheh, F ; Sharif University of Technology
2013
Abstract
Propane dehydrogenation was carried over a commercial Pt-Sn/γ-Al 2O3 catalyst at atmospheric pressure and reaction temperatures of 580, 600, and 620°C and WHSV of 11 h-1 in an experimental tubular quartz reactor. Propane conversions were measured for catalyst time on stream of up to nine days. The amounts of coke deposited on the catalyst were measured after one, three, six, and nine days on stream using a thermogravimetric differential thermal analyzer (TG-DTA) for each reaction temperature. The coke formation kinetics was successfully described by a coke formation model based on a monolayer-multilayer mechanism. In addition, catalyst deactivation was presented by a time-dependant...
Dynamic pull-in instability and vibration analysis of a nonlinear microcantilever gyroscope under step voltage considering squeeze film damping
, Article International Journal of Applied Mechanics ; Volume 5, Issue 3 , September , 2013 ; 17588251 (ISSN) ; Ahmadian, M. T ; Firoozbakhsh, K ; Sharif University of Technology
2013
Abstract
In this paper, a nonlinear model is used to analyze the dynamic pull-in instability and vibrational behavior of a microcantilever gyroscope. The gyroscope has a proof mass at its end and is subjected to nonlinear squeeze film damping, step DC voltages as well as base rotation excitation. The electrostatically actuated and detected microgyroscopes are subjected to coupled flexural-flexural vibrations that are related by base rotation. In order to detune the stiffness and natural frequencies of the system, DC voltages are applied to the proof mass electrodes in drive and sense directions. Nonlinear integro differential equations of the system are derived using extended Hamilton principle...
Integration of CFD and Nelder-Mead algorithm for optimization of MOCVD process in an atmospheric pressure vertical rotating disk reactor
, Article International Communications in Heat and Mass Transfer ; Volume 43 , April , 2013 , Pages 138-145 ; 07351933 (ISSN) ; Farhadi, F ; Boozarjomehry, R. B ; Sharif University of Technology
2013
Abstract
In this work, optimization of metalorganic chemical vapor deposition process for uniform layer thickness with especial attention to reactor geometric parameters as decision variables is presented. A numerical solution to a steady thermal flow associated with multi-species and chemical reactions in atmospheric pressure axisymmetrical rotating disk reactor by the CFD technique is obtained. Such a simulation is conducted on the assumption that the low Mach number flow is laminar. Then the validation of the numerical results with the benchmark solutions is conducted. Finally, integrating the CFD simulator with an optimization program, based on the Nelder-Mead algorithm, as a new approach is...
CVD-grown TiO2 particles as light scattering structures in dye-sensitized solar cells
, Article RSC Advances ; Volume 2, Issue 32 , 2012 , Pages 12278-12285 ; 20462069 (ISSN) ; Taghavinia, N ; Abdi, Y ; Tajabadi, F ; Boschloo, G ; Hagfeldt, A ; Sharif University of Technology
2012
Abstract
Chemical vapour deposition (CVD) at atmospheric pressure, using TiCl 4 as a precursor, was used to grow nanostructured TiO2 films on glass substrates. At relatively low temperatures (∼245 °C) and using relatively high reactant concentrations, different nano-morphologies of TiO2 were formed simultaneously, such as spheres, nanowires and mesoporous structures. The TiO2 spheres were successfully applied as light-scattering particles in dye-sensitized solar cells, either by direct deposition onto electrodes in the reactor, or by preparation of a printing paste from the deposited particles. For dye-sensitized solar cells using the organic dye D35 as sensitizer and a cobalt-complex based redox...
Modeling of platinum extraction from used reforming catalyst in iodine solutions
, Article ECS Transactions ; Volume 41, Issue 17 , 2012 , Pages 45-51 ; 19385862 (ISSN) ; 9781607683070 (ISBN) ; Baghallha, M ; Sharif University of Technology
Abstract
Platinum extraction from spent reforming catalysts in iodine solutions under atmospheric pressure and at temperatures up to 95°C was previously investigated in our group. In this system, platinum is oxidized from the spent catalyst with tri-iodide. In some of the experiments, it was observed that platinum extraction peaked and then decreased. This indicates that a precipitation reaction slowly occurs that removes the dissolved Pt ions from the solution. Power-law rate equation for the Pt extraction to PtI6 2- and the precipitation of the dissolved platinum to PtI 4(s) was implemented to model the experimental Pt extraction data. The activation energies for the platinum dissolution reaction...
Simulation approach to investigate the effect of the jet structure and air pressure on the performance of siro-jet spinning
, Article Fibres and Textiles in Eastern Europe ; Volume 92, Issue 3 , 2012 , Pages 46-50 ; 12303666 (ISSN) ; Hasani, M ; Sharif University of Technology
2012
Abstract
In this paper, the effects of different parameters on the hairiness of siro-jet spun yarns, such as the nozzle pressure, the distance between the front roller nip and inlet of the nozzle, and jet structure were investigated. Using the Taguchi method, it was concluded that the factor air pressure has the strongest effect and the factor distance between the front roller nip and inlet of the nozzle does not have a significant effect on the performance of the siro-jet spinning system in reducing yarn hairiness. A computational fluid dynamics model was developed to simulate the airflow pattern inside the jets. The effect of air pressure and the jet structure was simulated using Fluent 6.3...
Liquid-liquid equilibrium (LLE) data for ternary mixtures of {aliphatic+p-xylene+[EMpy][ESO 4]} at T=313.15K
, Article Fluid Phase Equilibria ; Volume 332 , 2012 , Pages 48-54 ; 03783812 (ISSN) ; Vossoughi, M ; Shamloo, A ; Mirkhani, S. A ; Akbari, J ; Sharif University of Technology
Elsevier
2012
Abstract
Liquid-liquid equilibrium (LLE) data for the ternary systems (heptane. +. p-xylene. +. 1-ethyl-3-methylpyridinium ethylsulfate) and (n-octane. +. p-xylene. +. 1-ethyl-3-methylpyridinium ethylsulfate) were measured at . T=. 313.15. K and atmospheric pressure. The selectivity and aromatic distribution coefficients, calculated from the equilibrium data, were used to determine if this ionic liquid can be used as a potential extracting solvent for the separation of p-xylene from heptane and n-octane. The consistency of tie-line data was ascertained by applying the Othmer-Tobias and Hand equations
Kinetic modeling of propane dehydrogenation over an industrial catalyst in the presence of oxygenated compounds
, Article Reaction Kinetics, Mechanisms and Catalysis ; Volume 107, Issue 1 , 2012 , Pages 141-155 ; 18785190 (ISSN) ; Fattahi, M ; Khorasheh, F ; Sharif University of Technology
Springer
2012
Abstract
The aim of this study was to develop an appropriate kinetic model for propane dehydrogenation (PDH) over an industrial Pt-Sn/γ-Al 2O 3 catalyst in the presence of small amounts of oxygenated compounds. Experimental data were obtained from a previous study where catalytic PDH was carried out in a laboratory scale reactor at atmospheric pressure in the temperature range of 575-620 °C in the presence of small amounts of water or methanol. The kinetics of the main dehydrogenation reaction was described and the effects of water and methanol on coke deposition and catalyst sintering were considered in a catalyst deactivation model to explain the observed optimum level in the amount of added...
Densities, viscosities, and surface tensions of aqueous mixtures of sulfolane + triethanolamine and sulfolane + diisopropanolamine
, Article Journal of Chemical and Engineering Data ; Volume 56, Issue 12 , 2011 , Pages 4317-4324 ; 00219568 (ISSN) ; Jalili, A. H ; Ghotbi, C ; Hosseini Jenab, M ; Taghikhani, V ; Sharif University of Technology
Abstract
Densities and viscosities of aqueous solutions containing sulfolane and ternary aqueous solutions of sulfolane and triethanolamine and ternary aqueous solutions containing sulfolane and disopropanolamine and also equilibrium surface tensions of the above ternary aqueous solutions were measured at temperatures ranging from (303.15 to 343.15) K and atmospheric pressure. The overall concentration of sulfolane, triethanolamine, and diisopropanolamine in solutions varied in the range of 0 to 16.5, 0 to 43, and 0 to 40 mass percent, respectively. Using the density, viscosity, and surface tension of pure water as the solvent, the corresponding experimental values obtained for the investigated...
Ethylbenzene dehydrogenation to styrene over fresh and used commercial catalysts
, Article AIChE Annual Meeting, Conference Proceedings ; 2011 ; 9780816910670 (ISBN) ; Ebrahimpour, O ; Sharif University of Technology
2011
Abstract
Dehydrogenation of ethylbenzene (EB) to produce styrene (ST) monomer is commercially performed over potassium-promoted iron oxide catalysts. Catalyst deactivation due to coke deposition and loss of potassium is a major operation and economic drawback in this process. To better evaluate the performance change of these catalysts over their life-cycle, dehydrogenation of EB to ST over the fresh and used commercial catalysts was experimentally investigated at temperatures from 590 to 639°C under atmospheric pressure. The fresh and the used catalysts were obtained from a styrene plant. The used catalyst had been continuously operated for two years under severe plant conditions. The catalyst...
(Liquid + liquid) equilibrium for ternary mixtures of {heptane + aromatic compounds + [EMpy][ESO4]} at T = 298.15 K
, Article Journal of Chemical Thermodynamics ; Volume 43, Issue 10 , 2011 , Pages 1530-1534 ; 00219614 (ISSN) ; Vossoughi, M ; Pazuki, G. R ; Safekordi, A. A ; Heydari, A ; Akbari, J ; Yavari, M ; Sharif University of Technology
Abstract
(Liquid + liquid) equilibrium (LLE) data for the ternary systems (heptane + toluene + 1-ethyl-3-methylpyridinium ethylsulfate) and (heptane + benzene + 1-ethyl-3-methylpyridinium ethylsulfate) were measured at T = 298.15 K and atmospheric pressure. The selectivity and aromatic distribution coefficients, calculated from the equilibrium data, were used to determine if this ionic liquid can be used as a potential extracting solvent for the separation of aromatic compounds from heptane. The consistency of tie-line data was ascertained by applying the Othmer-Tobias and Hand equations
Surface chemistry of atmospheric plasma modified polycarbonate substrates
, Article Applied Surface Science ; Volume 257, Issue 23 , September , 2011 , Pages 9836-9839 ; 01694332 (ISSN) ; Taghavinia, N ; Sharif University of Technology
2011
Abstract
Surface of polycarbonate substrates were activated by atmospheric plasma torch using different gas pressure, distance from the substrates, velocity of the torch and number of treatments. The modifications were analyzed by contact angle measurements, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and UV-vis spectrophotometry. Plasma treatment caused the surface characteristics to become more hydrophilic as measured by the water contact angle, which decreased from 88° to 18°. The decrease in contact angle was mainly due to oxidation of the surface groups, leading to formation of polar groups with hydrophilic property. XPS results showed an increase in the intensity of...
Experimental study and modelling of saturation molality of NaCl in quaternary aqueous electrolyte solutions at various temperatures
, Article Desalination ; Volume 267, Issue 2-3 , February , 2011 , Pages 228-232 ; 00119164 (ISSN) ; Roayaei, E ; Taghikhani, V ; Safekordi, A ; Zahedzadeh, M ; Sharif University of Technology
2011
Abstract
Saturation molality of sodium chloride in mixed aqueous electrolyte solutions containing NaCl, CaSO4 and Na2SO4 was measured at atmospheric pressure over the wide range of temperatures using an equilibrium cell equipped with an accurate temperature control system. The measurements were carried out at different CaSO4 and Na2SO4 concentrations. In order to check the repeatability of the experimental data for the saturation molality of NaCl, the experiments were replicated three times and the values reported were the average of the replicas. To model the data generated in this work, the PDH+UNIFAC-Dortmund activity coefficient model was used. The model used to predict the mean ionic activity...
Air pressure dependence of natural-convection heat transfer
, Article World Congress on Engineering 2010, WCE 2010, London, 30 June 2010 through 2 July 2010 ; Volume 2 , 2010 , Pages 1444-1447 ; 9789881821072 (ISBN) ; Abardeh, R. H ; Sharif University of Technology
2010
Abstract
Heat transfer is one of the prevalent concepts with many usages in different fields of science, industry and so on. In different applications we need more or less to know about this phenomenon. Control of this phenomenon is too important in some cases and we should be aware how to control it. The importance of heat transfer rate and effect of various parameters on it, is a reason of performing this research. Because of changes of air pressure in different applications, we need to know how heat transfer affected by air pressure. In different places air pressure is higher or lower than atmospheric pressure and we can't use more of experimental equations (e.g. Morgan or Churchill-Chu for a...