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two-phase
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Optimal ground state energy of two-phase conductors
, Article Electronic Journal of Differential Equations ; Vol. 2014 , 2014 ; ISSN: 10726691 ; Yousefnezhad, M ; Sharif University of Technology
Abstract
We consider the problem of distributing two conducting materials in a ball with xed proportion in order to minimize the rst eigenvalue of a Dirichlet operator. It was conjectured that the optimal distribution consists of putting the material with the highest conductivity in a ball around the center. In this paper, we show that the conjecture is false for all dimensions greater than or equal to two
Kinetic measurements for pseudomonas aeruginosa mr01 during biosurfactant production in two-phase system and developing a double-exponential model for viable cell profile
, Article World Applied Sciences Journal ; Volume 22, Issue 6 , 2013 , Pages 809-816 ; 18184952 (ISSN) ; Tayyebi, S ; Roostaazad, R ; Sharif University of Technology
2013
Abstract
Biosurfactants are microbial substances which influence interfacial tension. The kinetic study was carried out for Pseudomonas aeruginosa MR01 during biosurfactant production in a two-phase liquid-liquid batch fermentation system. The maximum rhamnolipid concentration (Pmax) and the yield of biosurfactant per 1 biomass (YP/X) in a 5-L bioreactor containing soybean oil medium were found to be approximately 20.9 g.L and 3.1 g.g-1, respectively. Previously reported kinetic models in aqueous systems, three-parameter Gompertz, 2 Luedeking-Piret and Mercier equations, demonstrated adequate goodness-of-fit (r >0.9) to kinetic data recorded for biomass growth, nitrate consumption and rhamnolipid...
Modeling process partitioning of biomolecules in polymer-polymer and polymer-salt aqueous two-phase systems (ATPS) using an extended excess gibbs energy model
, Article Zeitschrift fur Physikalische Chemie ; Volume 223, Issue 3 , 2009 , Pages 263-278 ; 09429352 (ISSN) ; Taghikhani, V ; Vossough, M ; Sharif University of Technology
2009
Abstract
A new local composition model was used to study the phase behavior of polymer-polymer and polymer-salt aqueous two-phase systems. The proposed model has three terms which account for the combinatorial, the long-range and the short-range effects in solution. The Flory-Huggins and the Debye-Hückel models were used for the combinatorial and long-range contributions. The interaction parameters of the model studied in this work can be regressed using a non-liner regression between the experimental data and those obtained from the proposed model. Also, this model was applied for modeling the partitioning of biomolecules in polymer-polymer and polymer-salt aqueous two-phase systems. The results...
Modeling and qualitative experiments on swirling bubbly flows: Single bubble with rossby number of order 1
, Article Journal of Fluids Engineering, Transactions of the ASME ; Volume 125, Issue 2 , 2003 , Pages 239-246 ; 00982202 (ISSN) ; Najafi, A. F ; Angilella, J. R ; Souhar, M ; Sharif University of Technology
2003
Abstract
The behavior of an isolated bubble in a single-phase swirling flow is investigated theoretically and experimentally. The Rossby number is such that the liquid flow can be approximated by a solid-body rotation superposed to a uniform axial velocity. The equations of the motion of the bubble are solved analytically and numerically, by assuming that the bubble is small and does not modify the water flow. Two kinds of bubbles have been considered: clean bubbles and bubbles with a contaminated interface. In the latter case the bubble is treated as a solid sphere. In both cases a critical angular velocity ωc for the rotating device is found. When ω<ωc the trajectory of the bubble is a conical...
Biodesulfurization of hydrocarbons and diesel fuels by Rhodococcus sp. strain P32C1
, Article Biochemical Engineering Journal ; Volume 8, Issue 2 , 2001 , Pages 151-156 ; 1369703X (ISSN) ; Vossoughi, M ; Kheirolomoom, A ; Tanaka, E ; Katoh, S ; Sharif University of Technology
2001
Abstract
The ability of Rhodococcus sp. P32C1 for desulfurization of n-hexadecane (n-C16) containing dibenzothiophene (DBT), and two different diesel oils is evaluated. Cells cultivated in the medium containing DBT of 0.1 mM showed higher desulfurization activity, and the effects of cell concentration on the desulfurization reaction were studied. Three hydrocarbon-aqueous phase ratios of 25, 50 and 75 vol.% were used for desulfurization of n-C16 containing 1 and 24mM of DBT as a sulfur source. The maximum specific production rate of 2-hydroxybiphenyl (2-HBP) in two-phase system was 43.5 mmol/(kg dry cell.h). Based on the optimum conditions determined for desulfurization of n-C16, diesel oils with...
Reservoir flow simulation using combined vorticity-based gridding and multi-scale upscaling
, Article Society of Petroleum Engineers - SPE Asia Pacific Oil and Gas Conference and Exhibition 2007 ""Resources, Professionalism, Technology: Time to Deliver"", Jakarta, 30 October 2007 through 1 November 2007 ; Volume 2 , 2007 , Pages 927-946 ; 9781604238594 (ISBN) ; Ashjari, M. A ; Firoozabadi, B ; Sharif University of Technology
Society of Petroleum Engineers (SPE)
2007
Abstract
A novel technique for upscaling of detailed geological reservoir descriptions is presented. The technique aims at reducing both numerical dispersion and homogenization error, generated due to incorporating a coarse computational grid and assigning effective permeability to coarse grid blocks respectively. In particular we consider implicit-pressure explicit-saturation (IMPES) scheme where homogenization error impacts the accuracy of the coarse grid solution of the pressure equation. To reduce the homogenization error, we employ the new vorticity-based gridding that generates a non-uniform coarse grid with high resolution at high vorticity zones. In addition, to control numerical dispersion,...
High performance dual mesh method to simulated two-phase gravity dominated flows in porous media
, Article 11th European Conference on the Mathematics of Oil Recovery, ECMOR 2008, Bergen, 8 September 2008 through 11 September 2008 ; 2008 ; Firoozabadi, B ; Sharif University of Technology
European Association of Geoscientists and Engineers, EAGE
2008
Abstract
This paper presents a new combined method for accurate upscaling of two-phase displacements in highly heterogeneous reservoirs. The method has the capability to retain its high performance for various flow regimes, from viscous to gravity dominant displacements, without the need for further modifications and computational steps. Two different grids are incorporated for simulation. The grid on fine scale is used to recognize the complicated physics of flow which depends on dominated driving forces and their interaction with heterogeneity. However, to achieve a fast simulation, the global flow calculation is performed on the coarse scale grid using upscaled equivalent properties. The...
Lipoxygenase-1 mass-transfer coefficient in aqueous two-phase system using spray extraction column
, Article Industrial and Engineering Chemistry Research ; Volume 44, Issue 19 , 2005 , Pages 7469-7473 ; 08885885 (ISSN) ; Rostami, K ; Kheirolomoom, A ; Sharif University of Technology
2005
Abstract
Extraction of lipoxygenase-1 was investigated by using the aqueous two-phase system formed by sodium sulfate-poly(ethylene glycol)-buffer. The extraction was performed in a 47-mm inner diameter spray column, operating in a semibatch manner. The effects of dispersed-phase flow rate and phase compositions on fractional dispersed-phase hold up (εD) and volumetric masstransfer coefficient (KDa) were respectively studied. It was found that the hold-up and volumetric mass-transfer coefficient increased with an increase in dispersed-phase velocity and decreased with increasing phase composition. Correlations have been developed by nonlinear regression for estimation of fractional dispersed-phase...
Numerical Investigation of Two-Phase Flow Contains Water and Oil in Hydrocyclones
, M.Sc. Thesis Sharif University of Technology ; Farhanieh, Bijan (Supervisor)
Abstract
Having an efficient and reliable system for oil-water separation is of crucial importance in oil and gas industry. Hydrocyclones have been used for more than a century to separate oil from water as well as sand from liquid or gas. The main objectives of this research are as follows: Determination the hydrocyclone principle of operation, based on computational fluid dynamic simulations. Hydrocyclones, in a spite of simple structure, are widely used in industry such as Petrochemical, Mining, Chemical Industries, Pharmacy, Food and Pulp Industries. The CALC BFC is one phase flow numerical code based on finite volume method and SIMPLEC algorithm. It was extended for simulating the two phase flow...
Study of Electrical Properties of Two Phase Liquids using Capacitance Sensor
, M.Sc. Thesis Sharif University of Technology ; Golnabi, Hossein (Supervisor) ; Gobal, Fereydoon (Co-Advisor)
Abstract
Estimation of physical parameters for solutions and mixed liqids are used widely in industrial applications. However, we can do these measurements with conventional laboratory analysis, but we always want to find an easy and quick method that use on-line measurements. In this study electrical properties of different water liquids and mixture samples in frequency stepwise range of 100-100000 Hz are measured by using a short cylindrical capacitive sensor and a measuring module (LCR-703).Operation of the capacitance measurement module for such probes is based on the auto-balancing bridge method.The effects of frequency and volume fraction on the electrical parameters and permittivity of mixed...
Theoretical and Experimental Study of the Partitioning of Cephalexin in Aqueous Two Phase System of Polymer-Salt
, M.Sc. Thesis Sharif University of Technology ; Teghikhani, Vahid (Supervisor) ; Ghotbi, Cirouc (Supervisor) ; vossoughi, Manouchehr (Supervisor)
Abstract
The aqueous two phase systems provide a suitable environment for separation and purification of biological compounds. Because both phases are water rich and biomolecule remain active in them. In this work, the partition coefficients of Cephalexin in polymer-salt aqueous two-phase systems have been measured. The experimental results were obtained at three various temperatures (37.2, 34.2 and 28.2) C and in each temperature, two salt (K2HPO4, Na3Cit) and two polymer with different molecular weight (4000, 10000) are investigated. According to the two phase analysis, the effect of different factors on tie line of systems is studied. It is observed that with increasing the PEG molecular weight,...
Numerical Simulation of Near-well Flow for Gas-condensate Reservoirs and Investigation of the Effect of Various Flow Parameters
, M.Sc. Thesis Sharif University of Technology ; Taghizade Manzari, Mehrdad (Supervisor)
Abstract
This thesis studies a gas condensate reservoir and considers the effect of different parameters. In this group of gas reservoirs, if the pressure drops below the dew point pressure, liquid phase appears. Appearing and disappearing of phases creates four regions in the reservoir. In the region far from the production well, pressure is still above the dew point pressure and vapor phase is present. By approaching production well, pressure drops below the dew point pressure and liquid phase starts to form but it is immobile. In closer regions to the well the liquid phase saturation grows and this phase becomes mobile. As a result, relative permeability of the vapor phase decreases sharply. In...
Experimental Study on Two-Phase Flow Characteristics in Micro-Channels
, M.Sc. Thesis Sharif University of Technology ; Nouri, Ali (Supervisor)
Abstract
The present study provids an experimental investigation on two-pase flow characteristics in microchannels. Experiment were conducted with a mixture of air and water in horizontal circular pyrex channel with 400µm inner diameter. The pressure drop and flow rates of the liquid and gas were measured using new method and images of the flow patterns recorded by high shutter speed camera. The gas and liquid superficial velocity ranges were 0.025-12.5m/s and 0.016-3.6m/s, respectively. The flow pattern map is developed from the observed flow patterns based on phases superficial velocity as wel as We numbers of liquid and gas phases. The flow pattern map is compared with those of larger channels....
Intelligent image-based gas-liquid two-phase flow regime recognition
, Article Journal of Fluids Engineering, Transactions of the ASME ; Volume 134, Issue 6 , 2012 ; 00982202 (ISSN) ; Hanafizadeh, P ; Hassan Saidi, M ; Sharif University of Technology
2012
Abstract
Identification of different flow regimes in industrial systems operating under two-phase flow conditions is necessary in order to safely design and optimize their performance. In the present work, experiments on two-phase flow have been performed in a large scale test facility with the length of 6 m and diameter of 5 cm. Four main flow regimes have been observed in vertical air-water two-phase flow at moderate superficial velocities of gas and water namely: Bubbly, Slug, Churn, and Annular. An image processing technique was used to extract information from each picture. This information includes the number of bubbles or objects, area, perimeter, as well as the height and width of objects...
Experimental study and calculation of CO 2-oil relative permeability
, Article Petroleum and Coal ; Volume 53, Issue 2 , 2011 , Pages 123-131 ; 13377027 (ISSN) ; Bolouri, S. H ; Sharif University of Technology
2011
Abstract
Carbon dioxide-oil relative permeability is measured under reservoir condition using core flood apparatus. Then the results are compared with Nitrogen-oil relative permeability. The results show that oil permeability is higher in Carbon dioxide injection compared to nitrogen injection. The comparison of gas permeabilities shows that at the start of injection, nitrogen and carbon dioxide relative permeability are equal, but as the gas saturation increased, Nitrogen relative permeability becomes higher. Finally, a method is proposed to calculate carbon dioxide-oil relative permeability from nitrogen-oil relative permeability. This method can be generalized to calculate relative permeability...
Numerical modeling of two-phase fluid flow in deformable fractured porous media using the extended finite element method and an equivalent continuum model
, Article Advances in Water Resources ; Volume 94 , August , 2016 , Pages 510–528 ; 03091708 (ISSN) ; Hosseini, N ; Mohammadnejad, T ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
In the present paper, a numerical model is developed based on a combination of the extended finite element method and an equivalent continuum model to simulate the two-phase fluid flow through fractured porous media containing fractures with multiple length scales. The governing equations involve the linear momentum balance equation and the flow continuity equation for each fluid phase. The extended finite element method allows for an explicit and accurate representation of cracks by enriching the standard finite element approximation of the field variables with appropriate enrichment functions, and captures the mass transfer between the fracture and the matrix. Due to the high computational...
Numerical simulation of two-phase flow in airlift pumps using the Physical Influence Scheme
, Article Progress in Computational Fluid Dynamics ; Volume 10, Issue 3 , 2010 , Pages 186-194 ; 14684349 (ISSN) ; Saidi, M. H ; Darbandi, M ; Kebriaee, A ; Sharif University of Technology
2010
Abstract
A new approach has been presented to solve gas-liquid flow numerically in vertical pipes of air-lift pumps. To improve modelling, a new strategy has been employed with the capability of coupling the continuity and momentum equations and enforcing the role of pressure directly in the continuity equation. This is achieved via applying a novel scheme called the Physical Influence Scheme (PIS). The current finite volume solution is compared with other available numerical solutions. Indeed, they are in fair agreement. However, the present predictions are far superior to those obtained from an existing simple method, which is widely used in airlift pump modelling
Polyethylene quality control in an industrial scale fluidized bed reactor
, Article Indian Journal of Chemical Technology ; Volume 25, Issue 1 , January , 2018 , Pages 21-30 ; 0971457X (ISSN) ; Shahrokhi, M ; Sharif University of Technology
National Institute of Science Communication and Information Resources (NISCAIR)
2018
Abstract
Polymer quality control in an industrial scale polyethylene fluidized bed reactor has been addressed. Since online measurements of polymer properties (melt index and density) are not available, they must be controlled indirectly via other available measurements. In the present paper, two algebraic equations correlating polyethylene melt index and density with the measureable concentrations of chemical components are obtained. Having the desired polyethylene properties and using these correlations, desired concentrations of chemical components are calculated and used via corresponding control loops. By using the infrequently available polyethylene property measurements, the correlation...
Experimental and numerical approach to enlargement of performance of primary settling tanks
, Article Journal of Applied Fluid Mechanics ; Volume 2, Issue 1 , 2009 , Pages 1-12 ; 17353572 (ISSN) ; Firoozabadi, B ; Ahmadi, G ; Sharif University of Technology
2009
Abstract
Circulation regions always exist in settling tanks. These regions would result in short-circuiting enlargement of the dead zone and high flow mixing problems and avoid optimal particle sedimentation. Therefore, the main objective of the tank design process is to avoid formation of the circulation zone, which is known as dead zone. Experiments show that the tank performance can be improved by altering the geometry of the tank which leads to a different velocity distributions and flow patterns. In this paper, the presence of a baffle and its effect on the hydrodynamics of the flow field has been investigated in a primary settling tank. Hydrodynamics of the flow field in these basins is...
Pore-scale investigation of selective plugging mechanism in immiscible two-phase flow using phase-field method
, Article Oil and Gas Science and Technology ; Volume 74 , 2019 ; 12944475 (ISSN) ; Rokhforouz, M. R ; Ayatollahi, S ; Sharif University of Technology
Editions Technip
2019
Abstract
The selective plugging effect of hydrophobic bacteria cell on secondary oil recovery performance was investigated. Water and aqua solution of purified Acinetobacter strain RAG-1 were injected into an oil-saturated heterogeneous micromodel porous media. Pure water injection expelled oil by 41%, while bacterial solution injection resulted in higher oil recovery efficiency (59%). In the simulation section, a smaller part of the heterogeneous geometry was applied as a computational domain. A numerical model was developed using coupled Cahn-Hilliard phase-field method and Navier-Stokes equations, solved by a finite element solver. In the non-plugging model, approximately 50% of the matrix oil was...