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Numerical Study and Optimization of Effective Parameters in Freeze Desalination
, M.Sc. Thesis Sharif University of Technology ; Afshin, Hossein (Supervisor)
Abstract
Freeze desalination as a water refining method has attracted a lot of attention due to its potential in lowering process energy consumption compared to other methods. This method is based on the fact that the dissolved salt is drained from the saline water during its freezing. The current study conducts a parametric study on freezing saline water in a cylindrical container to investigate the impact of geometric and functional factors affecting the desalination quality. This has been done by examining the aforesaid factors in the form of dimensionless parameters such as thermal Grashof number, solutal Grashof number, and Jacob number. In addition, in order to improve the desalination, a novel...
Mechanistic Studies of Improved Oil Recovery under Forced Gravity Drainage GAGD Process
, Ph.D. Dissertation Sharif University of Technology ; Kharrat, Riyaz (Supervisor) ; Ghotbi, Cyrus (Supervisor) ; Pooladi Darvish, Mehran (Co-Advisor)
Abstract
Gas-oil displacement, when stabilized by gravity forces leads to high displacement efficiency, as manifested in high recovery factor associated with gas-cap drive and gravity drainage. The main objective of this research is improved understanding of drainage behavior and changes in flow properties when the importance of viscous, gravity and capillary forces varies. The influence of interplaying between controlling forces on relative permeabilities is also studied. Another objective of this work is to study effect of wettability on recovery under forced gravity drainage. To study drainage behavior under various dominant driving/resistive forces, a number of forced gravity drainage experiments...
Semi-Analytical Modeling And Simulation Of Heavy Oil Recovery Through VAPEX Process
, M.Sc. Thesis Sharif University of Technology ; Masihi, Mohsen (Supervisor) ; Kharrat, Riyaz (Supervisor)
Abstract
VAPEX is a relatively new EOR process for the recovery of heavy oil. In this process solvent is used to form a vapor chamber within a reservoir. Vapor dissolves in the oil and diluted oil drains by gravity to a horizontal production well. The essential features of this recovery mechanism have been discussed in this study. Furthermore, a semi-analytical and a simulation study of VAPEX process have been performed on a specified Iranian heavy oil reservoir (such as Kuh-e-Mond). The aim of this study is to investigate an exponential functionality (correlation) witch incorporates all physical parameters that affect the production rate of VAPEX process in dimensionless form. The adjustable...
Nonlinear analysis of chatter in turning process using dimensionless groups
, Article Journal of the Brazilian Society of Mechanical Sciences and Engineering ; Volume 37, Issue 4 , July , 2015 , Pages 1151-1162 ; 16785878 (ISSN) ; Jalili, M. M ; Movahhedy, M. R ; Sharif University of Technology
Springer Verlag
2015
Abstract
A new 3-D nonlinear model of chatter vibration in turning process is presented in this paper. The workpiece is modeled as a rotating clamped-free beam which is excited by cutting forces. π-Buckingham theory is used to extract dimensionless parameters for this problem. Using these parameters, non-dimensional equations of motion are developed. An approximate analytical solution of the nonlinear problem is obtained. A study of the influence of different parameters on the stability results is developed. Using these results, turning velocity intervals for stable and unstable cuts are determined
A newmodel for permeability reduction rate due to calciumsulfate precipitation in sandstone cores
, Article Journal of Porous Media ; Volume 13, Issue 10 , 2010 , Pages 911-922 ; 1091028X (ISSN) ; Soltanieh, M ; Kharrat, R ; Sharif University of Technology
2010
Abstract
In this work, a reliable dimensionless correlation is proposed for prediction of permeability reduction rate in porous media, which is verified by experimental data obtained in this work in glass bead and sand pack as well as the core data from the literature. Although this correlation is based on the data which were obtained in our work in glass bead and sand-packed media at low pressure, it shows considerable flexibility to match with the extracted data for sandstone cores at high pressure, various flow rates, different temperatures and concentrations of calcium, and sulfate ions in brine solutions. In addition, a novel relationship for predicting the rate of precipitation of CaSO4 in...
Dimensionless correlation for the prediction of permeability reduction rate due to calcium sulphate scale deposition in carbonate grain packed column
, Article Journal of the Taiwan Institute of Chemical Engineers ; Volume 41, Issue 3 , 2010 , Pages 268-278 ; 18761070 (ISSN) ; Kharrat, R ; Soltanieh, M ; Sharif University of Technology
Abstract
In this work, an experimental and theoretical study has been conducted to investigate the permeability reduction due to CaSO4 scale deposition in packed column porous media. Permeability reduction by calcium sulphate deposition follows a systematic trend considering various important parameters that are affected in this complex process. Hence, a novel dimensionless model has been proposed for the prediction of permeability reduction rate with high accuracy. The developed model is based on the data obtained from glass bead and carbonate grain packed column at low pressure. The proposed model was validated with Berea sandstone cores data at high pressure (100-20,678 kPa), various flow rates...
Axisymmetric problem of energetically consistent interacting annular and penny-shaped cracks in piezoelectric materials
, Article Journal of Applied Mechanics, Transactions ASME ; Volume 78, Issue 2 , 2011 ; 00218936 (ISSN) ; Moeini Ardakani, S. S ; Eskandari, M ; Sharif University of Technology
Abstract
The axisymmetric problem of a concentric set of energetically consistent annular and penny-shaped cracks in an infinite piezoelectric body subjected to uniform far-field electromechanical loading is addressed. With the aid of a robust innovated technique, the pertinent four-part mixed boundary value problem (MBVP) is reduced to a decoupled Fredholm integral equation of the second kind. The results of two limiting cases of a single penny-shaped crack and a single annular crack are recovered. The contour plots of dimensionless intensity factors (IFs) at each crack front provide the stress and electric displacement intensity factors (SIFs and EDIFs, respectively) for all combination of crack...
A Power-Law Relationship between Characteristics of Light Source and Quantum Yield in Photocatalytic Systems
, Article Journal of Physical Chemistry C ; Volume 119, Issue 39 , July , 2015 , Pages 22425-22431 ; 19327447 (ISSN) ; Sharif University of Technology
American Chemical Society
2015
Abstract
A new dimensionless parameter, Sh-factor, is introduced by using dimensional analysis and extending the quantum yield definition to show power-law relations among light intensity, light wavelength, distance from light source, concentrations of dye/pollutant and photocatalyst, time, and degradation percent. The Sh-factor has the same equation form for photoactivated remediation systems with particulate and thin-film photocatalysts, and it provides mathematical tools to predict degradation performance of a photocatalytic system. These power-law equations separate simply the operational parameters related to the lamp from semiconductor photocatalyst characteristics. The light scattering and...
Experimental investigation of two phase flow in horizontal wells: Flow regime assessment and pressure drop analysis
, Article Experimental Thermal and Fluid Science ; Volume 88 , 2017 , Pages 55-64 ; 08941777 (ISSN) ; Tavakoli, A ; Shad, S ; Sharif University of Technology
Elsevier Inc
2017
Abstract
Multiphase flow is fundamental to different fields of engineering and science including petroleum engineering. In oil and gas, flow of multiple phases inside wells is a common phenomenon. In such conditions, petroleum engineers deal with different design and operational difficulties due to complexities involved in flow of multiple phases inside a well. Unlike flow of gas and liquid inside a well, the liquid-liquid flow inside a horizontal well has received rather less attention. This study is aimed at experimentally investigating multiphase flow in a horizontal well by using a 12 m length and 30 mm diameter well made of Plexiglas. Despite the importance of defining pattern transition...
Mass transfer coefficients of extracting Mo (VI) and W (VI) in a stirred tank by solvent extraction using mixture of Cyanex272 and D2EHPA
, Article Separation Science and Technology (Philadelphia) ; 2019 ; 01496395 (ISSN) ; Torab Mostaedi, M ; Outokesh, M ; Asadollahzadeh, M ; Sharif University of Technology
Taylor and Francis Inc
2019
Abstract
In this study, the mass transfer evaluation of an agitated liquid-liquid system for the extraction of molybdenum and tungsten from aqueous sulfate solution was investigated. It was found from batch experiments for separation of molybdenum from tungsten that the initial aqueous pH, Cyanex272 and D2EHPA concentration, contact time, dispersed phase volume fraction and impeller speed were optimized at 1.3, 0.07 M, 0.29 M, 15 min, 0.09 and 280 rpm, respectively. The results indicate that a suitable composition for stripping is 1.5 M NH4OH and 0.6 M NH4F. Furthermore, a modified correlation based on dimensionless numbers was derived for the prediction of continuous phase mass transfer in the...
Mass transfer coefficients of extracting Mo (VI) and W (VI) in a stirred tank by solvent extraction using mixture of Cyanex272 and D2EHPA
, Article Separation Science and Technology (Philadelphia) ; Volume 55, Issue 17 , 2020 , Pages 3140-3150 ; Torab Mostaedi, M ; Outokesh, M ; Asadollahzadeh, M ; Sharif University of Technology
Bellwether Publishing, Ltd
2020
Abstract
In this study, the mass transfer evaluation of an agitated liquid-liquid system for the extraction of molybdenum and tungsten from aqueous sulfate solution was investigated. It was found from batch experiments for separation of molybdenum from tungsten that the initial aqueous pH, Cyanex272 and D2EHPA concentration, contact time, dispersed phase volume fraction and impeller speed were optimized at 1.3, 0.07 M, 0.29 M, 15 min, 0.09 and 280 rpm, respectively. The results indicate that a suitable composition for stripping is 1.5 M NH4OH and 0.6 M NH4F. Furthermore, a modified correlation based on dimensionless numbers was derived for the prediction of continuous phase mass transfer in the...
Mass transfer studies in RDC column by the coupling effects of perforated structure and reactive extraction of Mo(VI) and W(VI) from sulfate solution
, Article International Communications in Heat and Mass Transfer ; Volume 118 , 2020 ; Torkaman, R ; Torab Mostaedi, M ; Asadollahzadeh, M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Solvent extraction of molybdenum (VI) and tungsten (VI) by synergism of the mixture of D2EHPA and TBP were conducted in the RDC extractor with perforated structure. The initial aqueous pH, extractant concentration, ammonium hydroxide concentration as a stripping agent, and synergistic enhancement factor were optimized in the initial experiments before collecting column data. In the RDC column, the influence of agitation rate and inlet phase velocities were examined on the hydrodynamic velocities, mass transfer data, and distribution coefficients. The finding data indicated that the impact of agitation speed on the distribution coefficients of molybdenum and tungsten is considerable in...
Dynamic analysis of mud loss during overbalanced drilling operation: An experimental study
, Article Journal of Petroleum Science and Engineering ; Volume 196 , 2021 ; 09204105 (ISSN) ; Salmanpour, S ; Zamani, H ; Zivar, D ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Mud filtration happens during an overbalanced drilling operation that causes mud invasion into pores and fractures. The productivity of a formation is significantly affected by the invasion of the mud into the near-wellbore area during the mud loss process. A considerable number of studies have evaluated mud filtration statically; however, a few studies have considered the dynamic behavior of a mud loss process during overbalanced drilling, which results in the inadequate prediction of the mud loss volume and inflicted damage to the formation. In this study, a near-wellbore simulation system (NeWSS) was designed to evaluate the dynamic mud loss behavior using dimensionless parameters and...
Proposing a general formula to calculate the critical velocities in tunnels with different cross-sectional shapes
, Article Tunnelling and Underground Space Technology ; Volume 110 , 2021 ; 08867798 (ISSN) ; Farhanieh, B ; Afshin, H ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Among the parameters affecting the critical velocity in tunnel fires, the tunnel cross-sectional shape could significantly affect the tunnel fire characteristics, mainly due to the wall-bounded physics of the tunnel fire. Previously, the effects of the cross-sectional geometry of the tunnel were calculated using the non-dimensional analysis and hydraulic height of the tunnel. The dimensionless analysis using hydraulic height calculates only the effects of the tunnel sizes and does not capture the effects of the shape of the tunnel cross-section. Developing a 3D computational fluid dynamics tool using the body-fitted grids, the critical velocities are calculated for the 7 different...
Effects of corrugated roughness on gaseous slip flow forced convection in microtubes
, Article Journal of Thermophysics and Heat Transfer ; Volume 25, Issue 2 , 2011 , Pages 262-271 ; 08878722 (ISSN) ; Salarieh, H ; Saidi, M. H ; Mozafari, A. A ; Sharif University of Technology
Abstract
Because of technological restrictions, it is actually impossible to fabricate smooth microchannels. Therefore, exploring the roughness effects on the flow characteristics at microscale is of great importance for scientific communities. The present investigation deals with the effects of corrugated roughness on the fully developed slip flow forced convection in micropipes. The governing equations subject to first-order slip boundary conditions are solved by means of the straightforward perturbation method. Closed-form expressions are obtained for the dimensionless velocity and temperature distributions, for the friction coefficient and pressure drop, and finally for the Nusselt number. The...
Wettability effects in gas gravity-Assisted flow as related to displacement instability
, Article Special Topics and Reviews in Porous Media ; Volume 1, Issue 1 , 2010 , Pages 39-47 ; 21514798 (ISSN) ; Kharrat, R ; Alipour Tabrizy, V ; Khosravi, M ; Ghotbi, C ; Sharif University of Technology
Abstract
The drainage of oil under gravity forces is an efficient method because it can farther reduce the remaining oil saturation to below that obtained after water flooding. This paper describes a series of visual experiments under forced gas invasion with special attention to the effects of wettability. From oil production history and image analysis, we examine a threshold criterion for displacement stability that is consistent with the results of gradient percolation theory. The effect of the destabilized front velocity on oil recovery and residual saturation is investigated for both wettability conditions. Different recovery rates occur with different fluid morphologies, which depend on the...
Identification of fluid dynamics in forced gravity drainage using dimensionless groups
, Article Transport in Porous Media ; Volume 83, Issue 3 , July , 2010 , Pages 725-740 ; 01693913 (ISSN) ; Kharrat, R ; Pooladi Darvish, M ; Ghotbi, C ; Sharif University of Technology
2010
Abstract
A number of forced gravity drainage experiments have been conducted using a wide range of the physical and operational parameters, wherein the type, length, and permeability of the porous medium as well as oil viscosity and injection rate were varied. Results indicate that an increase in the Bond number has a positive effect on oil recovery whereas the capillary number has an opposite effect. These trends were observed over a two-order of magnitude change in the value of the dimensionless groups. Furthermore, it was found that use of each number alone is insufficient to obtain a satisfactory correlation with recovery. A combined dimensionless group is proposed, which combines the effect of...
Gas-oil relative permeability and residual oil saturation as related to displacement instability and dimensionless numbers
, Article Oil and Gas Science and Technology ; Volume 65, Issue 2 , 2010 , Pages 299-313 ; 12944475 (ISSN) ; Kharrat, R ; Ghotbi, C ; Tabatabaie, S. H ; Sharif University of Technology
2010
Abstract
Displacement experiments of the gas-oil system are performed on long core scale models by varying the petrophysical properties and flowing conditions. Experiments are conducted in situations where capillary, gravity and viscous forces are comparable. From oil production history and picture analysis, the threshold for the stability is determined. The experimental findings are comparable to the results of a gradient percolation theory. The effect of destabilized front velocity on relative permeability and residual saturation is investigated. The relative permeabilities determined by using analytical and numerical approaches indicate that higher displacement velocity leads to a higher gas...
Relationship between wetting properties and macroscale hydrodynamics during forced gravity drainage and secondary waterflood
, Article Petroleum Science and Technology ; Volume 28, Issue 8 , 2010 , Pages 804-815 ; 10916466 (ISSN) ; Kharrat, R ; Ghotbi, C ; Alipour Tabrizy, V ; Sharif University of Technology
Abstract
In order to relate the wetting properties at the pore scale to the macroscale prevailing forces, a series of experiments was performed in vertical porous media under forced gas invasion at various wettability conditions with partially spreading oil. To describe the dynamics of oil recovery in a three-phase flow condition, the downward gas flood experiments were continued by water injection from the bottom. Experimental results obtained in situations where the magnitudes of viscous, capillary, and gravity forces are comparable. We study the transition from flow configurations where the interface is stable with respect to viscous instability to flow configurations where viscous fingering...
A new approach to characterize the performance of heavy oil recovery due to various gas injection
, Article International Journal of Multiphase Flow ; 2017 ; 03019322 (ISSN) ; Pourafshary, P ; Fathollahi, A ; Yassin, M. R ; Hassani, K ; Khosravi, M ; Mohammadifard, M ; Dangkooban, A ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
The performance of CO2 injection into a semi-heavy oil reservoir was investigated at reservoir conditions, using highly permeable sandstone in a complete series of PVT tests and coreflooding experiments. Analysis of involved parameters such as: injection rate, injectant type and reservoir pressure were also considered. Oil viscosity reduction and oil swelling are the most influential mechanisms of enhanced oil recovery in this process. The results demonstrated that CO2 injection would decrease the interfacial tension for the high permeable medium in the absence of capillarity, but this reduction may not improve the recovery drastically. One of the main important aspects of this work is the...