Sharif Digital Repository

There are many different opinions about the mass transfer contribution during jet formation in liquid - liquid extraction columns, and this could impact on their design. In this work, using experimental data obtained in two RDC columns and unpublished data of the jet mass transfer coefficients, mass transfer can be predicted during jet formation. The jet length and diameter were anticipated by using existing relations, and then the jet mass transfer coefficient was predicted, jet mass transfer rate and total column mass transfer rate were calculated and finally the contribution of mass transfer during jet formation in the column was predicted. Mass transfer contribution in the jet in various... 

Extraction and separetion of molybdenum is important because of its application in different industries. Since molybdenum resources are finite and low-grade, hydrometallurgical methods can be used to extract molybdenum. Solvent extraction of rare metals one of the important processes of hydrometallurgy.In the first of research, molybdenum solvent extraction from sulfate msoloution was investigated in batch and semi-industrial scale. In the laboratory scale, molybdenum solvent extraction from aqueous solution was investigated by using of D2EHPA, Cyanex272 and TBP. The effects of various parameters such as extractrant concentration, synergistic enhancement factor for mixture of extractants,... 

In present study, it is tried to investigate the effect of physical properties on hydrodynamic and overall mass transfer coefficient of single drops using different experiments and then simulation of drop motion with OpenFOAM software version 1.7.1. the systems were choosen are toluene/acetone/water and n-butanol/succinic acid/water which their interfacial tensions are 36 and 1.6 mN/m respectively. Various type of nozzles have been used for produce of 1.5, 2, 3 and 4 millimeter drops. The results show that in absence of solute component, the rising velocity of toluene drops in each size is higher than rising velocity of butanol drops inside the water between 25 to 75 percent. But with... 

In this work, a pore-scale analysis of nonaqueous phase liquid (NAPL) flow, transport, dissolution, and mobilization in heterogeneous and homogeneous porous media was presented. First, dissolution processes and distribution of NAPL phase were investigated using micromodel experiments. The tests were conducted at different injection rates in NAPL-saturated porous media using distilled water, surfactant, and nanoparticles-assisted surfactant. Changes in residual NAPL volume and interfacial area were measured using image analysis method to calculate the mass transfer coefficient, k, and the lumped mass transfer rate coefficient, K. Based on the experimental results, empirical Sherwood... 

Gas injection is one of the common methods for enhance oil recovery from oil reservoirs. At miscible injection condition, the efficiency of the process is majorly affected by the molecular diffusion coefficient of the gas in the oil. Therefore, the accurate value of this coefficient is an essential for applying in reservoir simulator. However, determination of this coefficient only is possible through experimental methods. In this study, pressure decay method was applied to determine the diffusion coefficient of nitrogen, methane and carbon dioxide gases in crude oil. The reasons for choosing this method are : accuracy in designing the experiment, covering a wide range of pressure... 

In this study, a tree-dimensional random pore-scale network model is used to simulate the membrane contactor porous medium. Drainage and imbibition phenomena is simulated to have a better knowledge of liquid and/gas intrusion trough the membrane porous structure. A genetic algorithm is used as an optimization tool. Several variables such as the number, radius and location of pores, the coordination number, as well as the radius and length of the throats are used herein as the optimization parameters. The difference between the binary SEM images and virtual sections on the generated network in conjunction with the permeability and mean pore size data were selected as the objective function.... 

In this work, flow transport, distribution, and dissolution of non-aqueous phase liquids (NAPLs) in heterogeneous porous media were modeled by focusing on the dissolution process in pore-level and field scale. First, by adopting advection-diffusion and mass transfer equations, dissolution process and NAPL distribution were investigated in a heterogeneous porous media using pore network modeling. The 2-D developed model was based on observations of micromodel tests. The pore scale simulator which adopted by this work was improved in some aspects in comparison to previous models in the literatures. First, in the phase displacement, by considering more realistic geometries for pore structure... 

In this thesis, hemodynamic parameters of flow and deposition of low density lipoproteins (LDL) on wall of coronary arteries with taking into account their curvature on the heart are studied. At first, numerical solution of the blood flow by assumption of blood as incompressible and Newtonian fluid for steady and pulsatile inlet is done. Then by assuming LDL particles as dilute solute in the blood, LDL transport from artery lumen into arterial wall is studied. LDL accumulation and penetration into the vessel wall cause thickening of the walls and eventually eclipse it and its known as the first stage of atherosclerosis disease. The results show that low shear region occurs on inner wall... 

Liquid-liquid extraction is one of the most important processes of chemical industries. So determination of operatiol condition in extraction columns is important. In this study, in various regimes of jet flow mass transfer coefficient during jet formation was measured and predicted experimentally. Results shown turbulent flow regime has higher mass transfer coefficient and axisymmetric jetting flow has lower mass transfer coefficient. Whereas studies related to mass transfer in liquid-liquid system are afew, numericall study was performed in this project. In this study system was simulated in unsteady state.Front-tracking method was used for simulating two phase flow and finite-volume... 

Mass transfer of a drop moving in a bulk fluid is an interesting subject which has attracted a lot of attention. Understanding effective parameters in this process would be helpful in order to increase the efficiency of the industrial processes related to mass transfer. In this research, the deformation and mas transfer of a moving drop was studied numerically. Navier-Stokes equations and concentration equation were solved separately with a VOF method in an axisymmetric domain using Fluent software. Comparision between numerical results and former experimental results proves the accuracy of the modelling in both fields of deformation and mass transfer. Moreover, effects of the physical... 

Liquid-liquid extraction is one of most important processes in chemical industries. So determination of operating condition effects is very critical. In this thesis we modeled concentration profile in the jet via mathematical equations and compare with experimental data. The major problem in concentration profile and solving equations is lack of knowledge in velocity profile within the jet was formed. Therefore, different flow models such as piston flow model, parabolic flow model, vortex flow model and a cone flow model was used and terminal concentrations inside the jet compared with laboratory values. Results shows the most accurate model to predict the flow concentration along the... 

In this study, the numerical simulation of cavitating flows for cryogens fluids is performed. The algorithm employs the homogenous, multiphase Euler/Navier-Stokes equations with the interface capturing method. The thermodynamic and thermal effects substantially impact the cavitation dynamics of cryogenic fluids and therefore these effects should be considered by solving the energy equation in conjunction with the mass and momentum conservation, and updating the fluid physical properties. Here, two cavitation modeling strategies, namely, the barotropic cavitation model and the transport equation-based model are used. Both laminar and turbulent cavitating flows are studied in this work. For... 

In this research, surface reaction phenomenon in porous media has been numerically simulated in pore scale. The main interesting part in this kind of physics is surface reaction exposed to a flow field. In this regard, an in-house code, based on LBM was developed. To speed-up our simulation, parallel computing was used on a GPU platform leading to a significant speed-up. Also, to model a real complex geometry, X-CT and MRI medical imaging technique were used to accurately model several complex 3D geometries. While, image processing technique was used to model our 2D geometries. The basic equilibrium equation of isopropanol dehydrogenation was considered to simulate and to analize chemical... 

In this dissertation, mass transport in cardiovascular system has been simulated using one-dimensional approach. As one-dimensional simulation has computation cost less than that of the three-dimensional simulations, and as it is more precise than lumped models, they are extensively used in the study of the phenomena in cardiovascular system. In addition, such an approach is more useful in the extraction of medical indices. In this study, a one-dimensional geometry of the systemic arteries has been used to solve momentum and continuity equations using characteristics method.
At first, the physiological data of the systemic arteries have been used to simulate a one-dimensional geometry... 

By studying change of ion concentrations in animal cells, researchers have reach to important information about cell cycles such as cell growth, muscle cell contraction and cell migration. Manner and amount of passage of ions through cell membrane are basic information that for studying the cell cycle is required. In this thesis, by using two methods, Forward-Reverse constant velocity Steered Molecular Dynamics (FR-cv-SMD) and classical Equilibrium Molecular Dynamics (EMD), diffusion coefficient and Potential of Mean Force (PMF) of sodium and potassium permeation through their protein channels are obtained. For verification the molecular dynamics (MD) methods, diffusion coefficient of K+... 

Tissue engineering aims to produce artificial tissues and organs to treat the damaged part, by implant in body of patients, is an important issue in research and development. In cases that tissue damage is sever or due to genetic defects or congenital disease, tissue in the body are not fully formed, tissue engineering can be used to regenerate, repair or replace organs or tissues. Cell culture on the scaffold and put it in the bioreactor is a critical step in the formation of tissues or organs. Among various bioreactors, perfusion bioreactor due to increase of convection in the structure of cell-scaffold is widely used. Enhancement of convection increases shear stress on the cells that is... 

During the Acidizing process in oil and gas reservoirs, the injected acid reacts with the rock grains, changes the rock pore structure and affects the flow conditions. Due to the presence of a large concentration gradient at the vicinity of the rock grains and the continuous changes in rock-fluid interfaces of the porous medium, the continuum assumption has been remained debatable for the effective local mass transport and effective molecular diffusion coefficients and the porosity-permeability relation in the continuum scale modeling of this process. Therefore, the need for pore scale modelling is evident. The novelty of this study relies in adapting the grid refinement method on the... 

The effects of gravity and inertia dominate our experiences of the physical world. But as systems are reduced in size, phenomena such as diffusion, surface tension and viscosity become ever more important; at the microscale they can dominate and result in a world that operates very differently from the macroscopic world. Kidney is one of the vital organs in which fluid and mass transfer occur between blood flow in microvessels and urine in microchannels called nephron. The present work is aimed at applying microchannel theory to study renal system. First, a n efficient numerical orthogonal collocation method has been employed to solve the steady-state formulation of electrolyte transport in... 

In this study the effect of nanoparticles on the mass transfer of dispersed phase in the liquid-liquid extraction systems, containing toluene with acetic acid as dispersed phase and saturated water of toluene as continues phase was investigated. For the ease of dispersion of nanoparticles in nonpolar organic dispersed phase, with the use of a novel method, hydrophobic tiania nanoparticles were synthesized and during producing with the sole-gel method were modified by adding Tetraethyl Ortho titanate as modifying agent, also the smallest hydrophobic nanoparticles of magnetite were synthesized by co-precipitating method and then, under optimum thermal condition were coated by adding Oleic... 

Transport phenomena i.e. momentum, heat and mass transfer are occurring inside the eye constantly. Any disturbance in each of these could lead to diseases or ocular problems. Konwledge of transport phenomena can help surgeons and specialists to identify problems more easily and cure the problems effectively. Further more, these phenomena have a great impact on drug delivery inside the eye. Therefore deep understanding of them makes investigation of different therapies easy and convenient. Consequently this understanding could lead to choose the best method and route of administration available. A precise model which is in consistence with the real human eye has been developed and the ocular...