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Comparison of Dynamic and Static Performances of a Quaternary Distillation Sequence
, Ph.D. Dissertation Sharif University of Technology ; Shahrokhi, Mohammad (Supervisor) ; Bozorgmehri, Ramin (Supervisor)
Abstract
In this work steady state and dynamic performances of quaternary distillation column sequences designed based on steady state and dynamic cost functions have been investigated. To quantify the dynamic performance, product loss due to disturbances has been considered in the objective function. In addition, variations of operating costs such as utilities have been considered in the objective function. To separate a quaternary mixture into four products, twenty two configurations have been used. It has been observed that the feed composition, disturbance frequency and magnitude affect the dynamic behavior strongly. To decrease the optimization computational load, a scheme that provides a...
Pore-scale Network Modeling of Gas-Liquid Membrane Contactors for CO2 and H2S Separation
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Abbas (Supervisor) ; Bozorgmehri, Ramin (Supervisor)
Abstract
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....
Simulation of Spontaneous Capilary Imbibition and Gravity Effects on Oil Recovery in Naturally Fractured Reservoirs
,
M.Sc. Thesis
Sharif University of Technology
;
Jamshidi, Saeed
(Supervisor)
;
Bozorgmehri, Ramin
(Supervisor)
Abstract
Oil reservoirs, have integrated identity; that is they consist of different parameters such as wettablity, initial water saturation, capillary and gravity forces, etc. which are related to each other and affect ultimate recovery simultaneously. In fractured reservoirs, other parameters such as fractures and complex geological structures are also considered among important parameters which affect ultimate recovery. Due to large amount of reserves, fractured reservoirs are subject to different studies and simulations. In this research, different parameters which affect ultimate recovery in fractured reservoirs, are studied and simulated. Different studies ...
Fault Detection in Plant Wide
,
Ph.D. Dissertation
Sharif University of Technology
;
Bozorgmehry, Ramin
(Supervisor)
;
Shahrokhi, Mohammad
(Supervisor)
Abstract
The accurate fault diagnosing system design helps the process safety and also helps increasing the products quality of the process. In this project, the fuzzy system and neural network have been used for fault detection and diagnosis of a yeast fermentation bioreactor. In one case, parameters of membership functions are selected in a conventional manner. In second case, the optimal values of these parameters have been obtained using the genetic algorithm. In another case, the neural network system is used for fault detection. These three cases are compared based on their performances in fault diagnosis of a yeast fermentation bioreactor for three different conditions. The results indicate...
Development of a Surrogate Simulator for Heterogeneous Reservoirs Using Trajectory Piecewise Linearization (TPWL) Method
, M.Sc. Thesis Sharif University of Technology ; Pishvaie, Mahmoud Reza (Supervisor) ; Bozorgmehri, Ramin (Supervisor)
Abstract
Reduced-order modeling (ROM) is a novel approach in all realms of computational science including reservoir simulation. Among various ROM methods, Trajectory Piecewise Linearization (TPWL) is on its evolution for reservoir applications. Previous investigations reflect promising future for incorporating TPWL into the next generations of enhanced reservoir simulators. In this work, we employ TPWL to investigate the claimed efficiency, robustness and accuracy of this method as a surrogate simulator for a developed reservoir simulator. The self construction of the used simulator gives us the opportunity to explore this method and to examine previous assertions on the subject. The efficiency of...
Assessment of the Motorized Wedge of the Compact Accelerator and Comparison with the Dosimetric Charactristics
, M.Sc. Thesis Sharif University of Technology ; Sohrabpour, Mostafa (Supervisor) ; Bozorgmehri, Ramin (Supervisor)
Abstract
Compact linear accelerator is equipped with a single fixed motorized wedge that produces different wedge angles by combining an open and a wedged field in the appropriate proportions.
In this work, the required data for the Treatment Planning System, TPS were generated for utilizing Compact motorized wedge, MW and was verified by dosimetry. To verify MW, the accumulated wedge profiles at a depth of 10 cm for different wedge angles were measured using 2-D Profiler and were calculated the wedge angles using an analytical formula. The validity of effective wedge angles 2-D Profiler has been done by determining the wedge angles in accordance with ICRU-24 for compact MW and Telecobalt...
In this work, the required data for the Treatment Planning System, TPS were generated for utilizing Compact motorized wedge, MW and was verified by dosimetry. To verify MW, the accumulated wedge profiles at a depth of 10 cm for different wedge angles were measured using 2-D Profiler and were calculated the wedge angles using an analytical formula. The validity of effective wedge angles 2-D Profiler has been done by determining the wedge angles in accordance with ICRU-24 for compact MW and Telecobalt...
An Ontological Study on Enterprise-wide Optimization of Supply Chain Problems
, M.Sc. Thesis Sharif University of Technology ; Farhadi, Fatollah (Supervisor) ; Bozorgmehri, Ramin (Supervisor)
Abstract
Supply Chain is a complex system and its modeling generally results in complicated mathematical problems. Solving these problems, one should make assumptions that make solutions impractical. Knowledge-based frameworks such as ontology has been proposed for tackling this issue. In this thesis, with relying on a seven step ontology developing method, UML as development language and Rational Rose as development software environment, an application ontology for supply chain and its problems has been developed. Furthermore, with use of a Benzene, Toluene and Xylene supply chain as an instance, it has been shown qualitatively how to use the ontology in various supply chain problems. It is...
Rigorous Synthesis of Optimal Heat Integrated Complex Column Sequences Using Genetic Algorithm
, M.Sc. Thesis Sharif University of Technology ; Bozorgmehri, Ramin (Supervisor) ; Farhadi, Fathollah (Supervisor)
Abstract
Finding the optimal heat integrated distillation column sequence is an utmost important optimization problem in process engineering. The frequently used approach in this area is to obtain a suitable sequencing candidate and then accomplish the heat integration based on the application of Pinch technology to finalize the design. This approach reduces the problem complexity at the expense of not necessarily reaching the best possible result. This work follows a genetic super structure approach to systematic and rigorous synthesis of optimal multi-component distillation sequences (including simple and thermally coupled complex columns) and simultaneously heat exchanger networks by using a...
Pore Network Model of Two Phase Flow in low permeable carbonate Rock
, Ph.D. Dissertation Sharif University of Technology ; Bozorgmehry, Ramin (Supervisor) ; Pishvaie, Mahmoud Reza (Supervisor)
Abstract
Development of pore network models for real porous media requires a detailed understanding of physical processes occurring on the microscopic scale and a complete description of porous media morphology. In this study, the microstructure of porous media has been represented by three dimensional networks of interconnected pores and throats which are designed by an object oriented approach. Afterwards, the connectivity of the system has been optimized by an optimization algorithm. To validate the methodology, a network of a carbonate sample is constructed. In this model, the geometrical characteristics of the pores and throats, such as their shapes, effective radii and lengths, are selected...
Optimization of Refinery Crude Distillation unit Production
, M.Sc. Thesis Sharif University of Technology ; Farhadi, Fatola (Supervisor) ; Bozorgmehry, Ramin (Supervisor)
Abstract
The design and optimization of processes was focused in the past on economic issues such as profitability and return on investment, and less attention has been paid to environmental issues. In recent years, by introducing environmental criterion as pillars of sustainable development, environmental optimization of processes has becoming an inseparable element of the process engineering. Therefore, it is necessary to examine the compatibility of environmental indicators with economic objective. The purpose of this study is to investigate environmental indicators and economic objective function in optimizing the Crude Distillation Unit (CDU) of an oil refinery. The CDU is one of the most...
Development of a Simulator to Simulate Multi-phase Flow with Asphaltene Precipitation in the Wellbore
, M.Sc. Thesis Sharif University of Technology ; Taghikhani, Vahid (Supervisor) ; Bozorgmehri, Ramin (Supervisor)
Abstract
Asphaltene, the heaviest and most polarizable fraction of crude oil, has a potential to precipitate, deposit and plug pipelines, causing considerable production costs. The main objective of this study is to contribute to the thermodynamic and transport modeling of asphaltene in order to predict its precipitation, segregation and deposition. Potential calculation of some thermophysical properties of asphaltene is also explored. Predicting the flow assurance issues caused by asphaltene requires the ability to model the phase behavior of asphaltene as a function of pressure, temperature and composition. It has been previously demonstrated that the Perturbed Chain form of Statistical Association...
, M.Sc. Thesis Sharif University of Technology ; Farhadi, Fathollah (Supervisor) ; Bozorgmehri, Ramin (Supervisor)
Abstract
In the present work, a comprehensive economic, environmental and exergy analysis and multi-objective optimization for world’s largest aromatic plant are provided and the interaction between decision variables in these criterions is discussed. In the first part, potentials of seven environmental features of the operational plant are quantified and normalized using life cycle assessment (LCA) for both process waste and utility environmental impacts. Exergy analysis (EA) is also used to determine the lowest eco-efficiency equipment. By choosing proper decision variables based on sensitivity analysis, LCA and EA results, optimization is performed to determine the best design variables based on...
Simulation of GAGD Process to Study the Impact of Effective Parameters on Operability Range and Recovery Factor
,
M.Sc. Thesis
Sharif University of Technology
;
Pishvaie, Mahmoud Reza
(Supervisor)
;
Bozorgmehry, Ramin
(Supervisor)
Abstract
Gravity drainage is the self-propulsion of oil downward in the reservoir rock. Under favorable natural and operational conditions, it has been found to effect recoveries comparable to water displacement. With modern technical knowledge, the operator can often make a choice between dissolved gas drive, water drive and gravity drainage as the principal recovery agent in a reservoir. So far, gravity drainage has received less consideration than the other two. Gravity drainage is one of the most important processes taking place in fractured reservoirs and it plays a major role in oil recovery from low permeability matrix blocks during gas injection process. Gravity drainage is responsible for...
Modeling and Numerical Simulation of Inertial Two-Phase Flow in Heterogeneous Porous Media
, M.Sc. Thesis Sharif University of Technology ; Ghazanfari, Mohammad Hossein (Supervisor) ; Bozorgmehri, Ramin (Supervisor)
Abstract
In this study, single-phase and two-phase, incompressible flow in a non-deformable porous media was modeled and also simulated. The Reynolds numbers have been considered high enough to justify the use of the model including inertial terms. Afterwards, the mass conservative equations were discretized. Then, the numerical model has been developed for heterogeneous porous media. The heterogeneous porous media was comprised by several specified homogeneous regions, each having isotropic transport properties or permeability distribution with applying stochastic methods. The developed numerical model was used for predicting of saturation profile in water flooding process in one, two and...
Using Intelligent Local Thermodynamic Models in Simulation of Thermal EOR Processes
, M.Sc. Thesis Sharif University of Technology ; Bozorgmehri, Ramin (Supervisor) ; Pishvaie, Mahmoud Reza (Supervisor)
Abstract
Fluid property calculation is one of the most time consuming parts of compositional reservoir simulation. Also in thermal reservoir simulations, more iterations and smaller time steps increase number of fluid properties calculations required. Fluid property calculations require multiphase equilibrium calculations which could be very time consuming depending on the level of sophistication of the fluid model used. In this work a simulator with capability to use EoS for fluid property calculations is developed. The simulator uses full implicit finite difference solution scheme. EoS is used as fluid model to increase the accuracy and applicability of simulator for different fluid properties and...
Reactor and Heat Exchanger Network Synthesis with Genetic Algorithm
, M.Sc. Thesis Sharif University of Technology ; Farhadi, Fathollah (Supervisor) ; Bozorgmehri, Ramin (Supervisor)
Abstract
In most chemical processes, at the first stage, the feed are being treated in physical steps such as preheating. Afterward it enters reaction system to undergo chemical treatment. In the final stage, product of reaction system is physically processed to prepare them to exit the boundary of the process. There are various ways to process materials chemically. This process can be continuous, batch and even semi-batch, via a single reactor or a network of the reactors. And also it can be performed under various range of operating condition. Moreover in some cases, intermediate cooling and heating is necessary. The question is that which configuration and operating condition is the best. The goal...
Simulation of Retrograde Behavior of Hydrocarbons around the Production Wells in Gas-Condensate Reservoirs
, M.Sc. Thesis Sharif University of Technology ; Pishvaie, Mahmmod Reza (Supervisor) ; Bozorgmehry, Ramin (Supervisor)
Abstract
The hydrocarbon reservoirs with temperature between critical temperature and cricondentherm are called gas condensate reservoirs. The hydrocarbon fluids of gas condensate reservoirs have retrograde behavior, i.e. when the pressure falls below the dewpoint, condensate liquid appears. This phenomenon usually occurs around the production wells, because pressure is typically the lowest in the near-well region.This so-called condensate blockage leads to reduced gas production because the condensate causes a decrease in gas relative permeability.
This phenomenon is difficult to capture in the standard compositional simulators, because well blocks are typically too large. The condensate...
This phenomenon is difficult to capture in the standard compositional simulators, because well blocks are typically too large. The condensate...
Optimization of MINLP Ethanol Biorefinery
, M.Sc. Thesis Sharif University of Technology ; Farhadi, Fateholla (Supervisor) ; Bozorgmehri, Ramin (Supervisor)
Abstract
Ethanol is one of the most important solvents in the industry with different applications in various fields, which can be used in disinfection solutions, perfumery, paints, fuels, etc. In this research, a predefined superstructure is examined to investigate the possibility of ethanol production by a process which has the lowest production cost per kilogram of ethanol.Various feeds can be used to produce ethanol, the most important of which are bagasse, wheat starch, sugar beet, sugar cane, corn and dextrose. In this study, the corn is selected as feed, while each of the above feed, and contains a different percentage of glucan, xylan and lignin. Conversion factor of components in...
Simulator Development for Thermal Operation (Pre-heating) of SAGD Techniques
, M.Sc. Thesis Sharif University of Technology ; Pishvaie, Mahmoud Reza (Supervisor) ; Bozorgmehri, Ramin (Supervisor)
Abstract
This work describes the use of a two-dimensional numerical simulator for Steam Assisted Gravity Drainage (SAGD) using the model proposed by Coats et al with some improvements. Despite the Coats model this developed model accounts for capillary and gravity effects in the energy equation with a variable thermal conductivity of the formation. First, a sensitivity analysis is performed for SAGD process. Then, the simulator is used to describe the pre-heating process preceding SAGD. We studied two methods of preheating process and found that there exists an optimum method of preheating for any reservoir. We concluded that longer preheating period does not necessarily yield a faster recovery
Mathematical Modeling of Diabetic Nephropathy
, M.Sc. Thesis Sharif University of Technology ; Abd Khodaei, Mohammad Jafar (Supervisor) ; Bozorgmehri, Ramin (Co-Advisor)
Abstract
Diabetes has become the most prevalent disease all among the world. One of the complications of this disease is diabetic nephropathy. Diabetic nephropathy occurs when the kidney cells encounter high glucose concentration for long periods. Kidney cells use glucose as their energy supply. However, the excess glucose in the diabetics triggers specific gene pathways, gradually leading to diabetic nephropathy. As a result, proteins’ levels and the activity of transcription factors change during the disease progression. Diabetic nephropathy is characterized by excessive deposition of the proteins comprising the extracellular matrix in the mesangium, basement membrane of the glomerulus, and in the...