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Analysis of the Surfactant Effect on Detachment of a Droplet in Immiscible Fluid Phase
, M.Sc. Thesis Sharif University of Technology ; Roostaazad, Reza (Supervisor)
Abstract
The phenomenon of oil drop detachment from solid surface has great importance in many different industries, such as coating, print, membrane emulsification, detergency, and oil enhancement recovery. In our study, we tried to explore this phenomenon. Therefore, we attempted to employ Young equation as force balance for the discussed system which is comprised of n-Decane as oil droplet, aqueous solution (brine) with SDS (Sodium Dodecyl Sulfate), and glass. Also, in order to find governing factors regarding oil detachment process -such as interfacial tension, contact angle, and line friction coefficient- we used an advanced apparatus equipped with horizontal microscope and digital video camera....
Experimental Investigation of Mass Transfer by Droplet Using Image Processing
, M.Sc. Thesis Sharif University of Technology ; Firoozabadi, Bahar (Supervisor) ; Afshin, Hossein ($item.subfieldsMap.e)
Abstract
Wide and varied aspects of droplet motion due to its increasing application in various fields has attracted much attention. Analysis of mass transfer from the liquid drop into the other fluid, such as complex and intriguing problems in fluid mechanics, which is very important. Many experimental and numerical studies have been carried out in this case that the evelopment of laboratory equipment and software, are rapidly growing.
In this study, given the importance of this issue, experimental study on mass transfer in fluid systems solution droplet liquid - liquid extraction, have been considered. Different methods have been discussed to date. In the present study, using image processing...
In this study, given the importance of this issue, experimental study on mass transfer in fluid systems solution droplet liquid - liquid extraction, have been considered. Different methods have been discussed to date. In the present study, using image processing...
Modeling and Simulation of Two Phase Flow in Gas Condensate Wells
, M.Sc. Thesis Sharif University of Technology ; Taghikhani, Vahid (Supervisor) ; Ghazanfari, Mohammad Hossein (Supervisor)
Abstract
A numerical simulation of fluid flow in gas condensate wellbore, which annular flow is dominant, is performed. A three fluid model is used for annular two phase flow. The model is based on conservation equations of mass, momentum and energy for gas phase, dispersed phase (droplets) and the film. The friction between phases and with wellbore wall and also mass transfer between phases, which conservation equations rely on them, are considered. Computer programming of obtained system of equations is performed in Matlab. The Reimann method is used for solving our system of hyperbolic equations and simulation is performed for both steady and unsteady state. Transforming system of nonlinear...
Hydrodynamic Investigation of Large Drops and Their Breakage In Liquid Liquid Packed Beds
, M.Sc. Thesis Sharif University of Technology ; Safekordi, Ali Akbar (Supervisor)
Abstract
packed columns are important in liquid-liquid extraction processes. In most studies, at first, drops are broken to small drops as much as possible and then they contact with packings. But, because of different reasons drops during their moving up coalescence together. So far, there is not serious investigation about hydrodynamics of these large drops and their breakage in packed columns. Thus, breakage of two different sizes of drops while collision to 3 different height of 4 different type of packings with two volumetric flow rates and in 2 cases of straight collision of drops to bed and collision to support plate has been investigated. Then size distribution of produced drops throughout...
Investigation of Equilibrium and Kinetics of Uranium Solvent Extaction by Cyanex 301 Using a Single Drop Column
, M.Sc. Thesis Sharif University of Technology ; Samadfam, Mohammad (Supervisor) ; Torab-Mostaedi, Meisam (Supervisor)
Abstract
Uranium separation from other metals in ore and nuclear waste is one of the most important stagesin nuclear fuel cycling. Solvent extraction is the common method for uranium extraction that reagent plays important rule in this technique. In this investigation, uranium solvent extraction is carried out by Cyanex 301 as reagent from nitric acid. At beginning, equilibrium batch extraction was carried and the effect of parameters such as pH, reagent concentration, temperature, shaking time of two phases, volumetric ratio of two phases, diluent and nitric acid concentration on extraction was investigated and optimum value of parameters was calculated. Uranium concentration effect was also...
Fast dynamic interfacial tension measurements and dilational rheology of interfacial layers by using the capillary pressure technique
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 407 , August , 2012 , Pages 159-168 ; 09277757 (ISSN) ; Krägel, J ; Makievski, A. V ; Kovalchuk, V. I ; Kovalchuk, N. M ; Mucic, N ; Loglio, G ; Pandolfini, P ; Karbaschi, M ; Miller, R ; Sharif University of Technology
Elsevier
2012
Abstract
The oscillating drop and bubble analyzer (ODBA) is an experimental set-up based on the measurement of capillary pressure under static and dynamic conditions. It allows studies of slow and fast dynamic surface and interfacial tensions, following different growing and oscillating drop or bubble protocols, as well as determination of the dilational interfacial visco-elasticity of liquid interfacial layers. For the visco-elasticity studies, drops or bubbles are subjected to harmonic oscillations of area or volume in a broad frequency range, and the resulting harmonic capillary pressure response is analyzed by Fourier analysis. Also, transient relaxations can be easily performed, which are of...
Novel boundary condition implementation to model electroosmotic phenomenon in microchannels
, Article Proceedings of the 7th International Conference on Nanochannels, Microchannels, and Minichannels 2009, ICNMM2009, 22 June 2009 through 24 June 2009, Pohang ; Issue PART A , 2009 , Pages 243-251 ; 9780791843499 (ISBN) ; Farzinpour, P ; Sharif University of Technology
Abstract
This Paper presents simulation of Electroosmotic phenomenon in a capillary using an extended hybrid finite-volume-element method. Most of the last electroosmotic phenomenon studies in microchannels do not take into consideration the effect of reservoirs and pressure drops occurred at the inlet and outlet of the microchannel. This neglect may lead to a few drawbacks. For example, the incorrect pressure drops can significantly alter the flow patterns and mass flow rates in microchannels. As a remedy the use of reservoirs at the two ends of a microchannel has been recently practiced as a novel strategy to overcome this drawback. However, this remedy needs careful attention because the resulting...
The role of reactants and droplet interfaces on nucleation and growth of ZnO nanorods synthesized by vapor-liquid-solid (VLS) mechanism
, Article Journal of Alloys and Compounds ; Volume 455, Issue 1-2 , 2008 , Pages 353-357 ; 09258388 (ISSN) ; Madaah Hossein, H. R ; Ghamsari, M. S ; Sharif University of Technology
2008
Abstract
Short ZnO nanorods and long ZnO nanowires have been produced on SiO2 and Si substrates by VLS and VS mechanisms via a double tube chemical vapor transport and condensation (CVTC) process. The role of reactants and droplet interfaces on the nucleation and growth of ZnO nanorods have been investigated. A conceptual model for nucleation of ZnO nanorods has been proposed by describing the half-oxidation and reduction reactions at the growth front. The importance of Zn vapor in the nucleation phenomena has been studied by changing starting materials. Atomic force microscopy (AFM), scanning electron microscopy (SEM), and EDX analysis have been used to characterize ZnO nanorods and investigate the...
Physical and hydraulic properties of a new spring packing
, Article CHISA 2006 - 17th International Congress of Chemical and Process Engineering, Prague, 27 August 2006 through 31 August 2006 ; 2006 ; 8086059456 (ISBN); 9788086059457 (ISBN) ; Yazdani, F ; Farhadi, F ; Deldari, H ; Sharif University of Technology
2006
Abstract
Physical and hydraulic properties of new stainless steel spring packing are introduced. The measured hydraulic properties are: dry and wetted packed bed pressure drop, loading and flooding points and the liquid holdups. The appropriate coefficients for predicting the mentioned hydraulic properties from different correlations are also reported. Hydraulic properties for this packing are compared with available packings. In spite of small size, the dry and wetted packed bed pressure drops of spring packing are less than similar Raschig and Protruded rings. The total liquid holdup of this packing is greater than other commercial packings. The big total liquid holdup and physical surface area are...
Simulation and exergy-method analysis of an industrial refrigeration cycle used in NGL recovery units
, Article International Journal of Energy Research ; Volume 30, Issue 15 , 2006 , Pages 1336-1351 ; 0363907X (ISSN) ; Jarrahian, A ; Pishvaie, M. R ; Sharif University of Technology
2006
Abstract
The behaviour of an industrial refrigeration cycle with refrigerant propane has been investigated by the exergy method. An natural gas liquid recovery unit with its refrigeration cycle has been simulated to prepare the exergy analysis. Using a typical actual work input value; the exergetic efficiency of the refrigeration cycle is determined to be 26.51 % indicating a great potential for improvements. The obtained simulation results reveal that the exergetic efficiencies of the air cooler(s) and chilling sections get the lowest rank among the other compartments of refrigeration cycle. Refrigeration calculations have been carried out through the analysis of T-S and P-H diagrams where...
Optimization of the pem fuel cell cooling system by entropy generation minimization
, Article 3rd International Conference on Fuel Cell Science, Engineering, and Technology, 2005, Ypsilanti, MI, 23 May 2005 through 25 May 2005 ; 2005 , Pages 441-448 ; 0791837645 (ISBN); 9780791837641 (ISBN) ; Saidi, M. H ; Sharif University of Technology
American Society of Mechanical Engineers
2005
Abstract
Cooling system is essential for high power fuel cells to maintain cells temperature in an acceptable limit. In this paper a suitable cooling system for the PEM fuel cell has been designed and optimized. The design includes the number of the cooling plates, the proper circuit of the cooling channels in the plates, the channel dimensions, the flow rate of the cooling fluid and its temperature. The optimization technique is minimization of the entropy generation through the cooling plates. The design of the cooling channels and plates is such that the plate temperature doesn't exceed from a desired temperature and the temperature variation in the plate becomes minimized. In this design, the...
A novel inference algorithm for active Learning method
, Article 1st Iranian Conference on Pattern Recognition and Image Analysis ; 2013 ; 9781467362047 (ISBN) ; Shouraki, S. B ; Ghaffari, A ; Sharif University of Technology
2013
Abstract
This paper presents a new inference algorithm for Active Learning Method (ALM). ALM is a pattern-based algorithm for soft computing which uses the Ink Drop Spread (IDS) algorithm as its main engine for feature extraction. In this paper a fuzzy number is extracted from each IDS plane rather than the narrow path and spread as in previous approaches. In order to compare performance of the proposed algorithm with the original one, two functions which are widely used in literature are modeled as the benchmark. Simulation results show that the proposed algorithm is as effective as previous one in the modeling task
Mixed protein-surfactant adsorption layers formed in a sequential and simultaneous way at water-air and water-oil interfaces
, Article Soft Matter ; Volume 8, Issue 22 , 2012 , Pages 6057-6065 ; 1744683X (ISSN) ; Kotsmar, C ; Ferri, J. K ; Javadi, A ; Karbaschi, M ; Krägel, J ; Wüstneck, R ; Miller, R ; Sharif University of Technology
2012
Abstract
Mixed protein-surfactant adsorption layers can be built up in two different ways. The classical way is when all components adsorb simultaneously from a mixed solution. Alternatively, the components adsorb one after another, i.e. in a sequential way. In the present work, the formation of such surface layers has been studied with the random coil protein β-casein in the presence of added anionic surfactant SDS and compared for two different interfaces: the water-air (W-A) and water-hexane (W-H) interfaces. The used experimental technique is a drop profile analysis tensiometer PAT-1 specially equipped with a coaxial double capillary for drop volume exchange during the experiments. The results...
Memristor crossbar-based hardware implementation of the IDS method
, Article IEEE Transactions on Fuzzy Systems ; Volume 19, Issue 6 , Dec , 2011 , Pages 1083-1096 ; 10636706 (ISSN) ; Shouraki, S. B ; Rohani, A ; Sharif University of Technology
2011
Abstract
Ink drop spread (IDS) is the engine of an active learning method, which is the methodology of soft computing. IDS, as a pattern-based processing unit, extracts useful information from a system that is subjected to modeling. In spite of its excellent potential to solve problems such as classification and modeling compared with other soft-computing tools, finding its simple and fast hardware implementation is still a challenge. This paper describes a new hardware implementation of the IDS method that is based on the memristor crossbar structure. In addition to simplicity, being completely real time, having low latency, and the ability to continue working properly after the occurrence of power...
Heat transfer and pressure drop characteristics of nanofluid in unsteady squeezing flow between rotating porous disks considering the effects of thermophoresis and Brownian motion
, Article Advanced Powder Technology ; Volume 27, Issue 2 , March , 2016 , Pages 564–574 ; 09218831 (ISSN) ; Tamim, H ; Sharif University of Technology
Elsevier
2016
Abstract
In this study, the unsteady three dimensional nanofluid flow, heat and mass transfer in a rotating system in the presence of an externally applied uniform vertical magnetic field is investigated. This study has different applications in rotating magneto-hydrodynamic (MHD) energy generators for new space systems and also thermal conversion mechanisms for nuclear propulsion space vehicles. The important effects of Brownian motion and thermophoresis have been included in the model of nanofluid. The governing equations are non-dimensionalized using geometrical and physical flow field-dependent parameters. The velocity profiles in radial, tangential and axial directions, pressure gradient,...
Mass-transfer enhancement in single drop extraction in the presence of magnetic nanoparticles and magnetic field
, Article AIChE Journal ; Volume 62, Issue 12 , 2016 , Pages 4466-4479 ; 00011541 (ISSN) ; Molaei Dehkordi, A ; Fadaei, F ; Sharif University of Technology
John Wiley and Sons Inc
2016
Abstract
Magnetite nanoparticles with an average particle size of 28.8 nm were synthesized, coated with oleic acid, and characterized using various techniques such as DLS, FT-IR, SEM, XRD, VSM, and UV-Vis analysis. A nanofluid consisting of synthesized nanoparticles and 5 wt % acetic acid in toluene as the dispersed phase was prepared and used in the chemical test system, Toluene-Acetic Acid-Water, for the single drop extraction in the presence and absence of an external oscillating magnetic field. Influences of various operating and design parameters such as nanoparticle concentration, drop diameter, and the applied current and frequency on the overall mass-transfer coefficients for the...
Numerical simulation of collision between two droplets in the T-shaped microchannel with lattice Boltzmann method
, Article AIP Advances ; Volume 6, Issue 11 , 2016 ; 21583226 (ISSN) ; Ebrahimi, S ; Moosavi, A ; Shafii, M. B ; Kowsary, F ; Sharif University of Technology
American Institute of Physics Inc
Abstract
In this study, the Lattice Boltzmann Method (LBM) is used to investigate the deformation of two droplets within microfluidic T-junctions (MFTD). In order to increase the accuracy the two immiscible fluids are modeled using the He-Chen-Zhang model. First, this model is applied to ensure that the surface tension effect existing between the droplets and the continuous fluid is properly implemented in the model. Then the collision and merging of the two droplets within the intersection of a T-shaped microchannel is investigated. For generating droplet formation the effects of relevant dimensionless parameters such as the Reynolds, the Weber numbers as well as a collision parameter affecting the...
Droplet dynamics in rotating flows
, Article Advances in Colloid and Interface Science ; Volume 236 , 2016 , Pages 63-82 ; 00018686 (ISSN) ; Javadi, K ; Taeibi Rahni, M ; Miller, R ; Sharif University of Technology
Elsevier B.V
2016
Abstract
This paper deals with investigations of droplet dynamics in rotating flows. In many previous studies droplet dynamics was analyzed in simple unidirectional flows. To fill this gap, the focus of this study is an overview on investigations of droplet dynamics in a complex rotating flow. A Lattice Boltzmann Method with high potential in simulation of two-phase unsteady flows is applied to simulate the physics of the problem in a lid-driven cavity. In spite of its simple geometry, there is a complex rotating flow field containing different vortices and shear regions. The Reynolds number based on the cavity length scale and the upper wall velocity, ReL, is considered to be 1000. We discuss here...
Modeling of Non-Darcy flow through anisotropic porous media: Role of pore space profiles
, Article Chemical Engineering Science ; Volume 151 , 2016 , Pages 93-104 ; 00092509 (ISSN) ; Hassani, A. H ; Ghazanfari, M. H ; Sharif University of Technology
Elsevier Ltd
Abstract
Excess pressure drop induced by inertial effects limits the applicability of Darcy's law for modeling of fluid flow through porous media at high velocities. It is expected such additional pressure drop is influenced by pore/morphology of porous media. This work concerns with fundamental understanding of how throat curvature affects intrinsic properties of porous media at non-Darcy flow conditions using network modeling. Conical, parabolic, hyperbolic, and sinusoidal capillary ducts with three types of imposed anisotropy are used to construct the network in a more realistic manner. Solutions of one dimensional Navier-Stokes equation for incompressible fluid flow through converging/diverging...
Effects of initial static bed height on fractional conversion and bed pressure drop in tapered-in and tapered-out fluidized bed reactors
, Article International Journal of Multiphase Flow ; Volume 79 , 2016 , Pages 50-61 ; 03019322 (ISSN) ; Molaei Dehkordi, A ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
In this article, a standard 2D Two-Fluid Model (TFM) closed by the kinetic theory of granular flow (KTGF) has been applied to simulate the behavior of tapered-in and tapered-out fluidized bed reactors. In this regard, two types of chemical reactions with gas volume reduction and increase were considered to investigate the effects of initial static bed height on the fractional conversion and bed pressure drop. To validate the CFD model predictions, the results of hydrodynamic simulations concerning bed pressure drop and bed expansion ratio were compared against experimental data reported in the literature and excellent agreement was observed. The obtained simulation results clearly indicate...