Sharif Digital Repository

The usages of Autonomous Underwater Vehicles (AUV) are limited due to the lack of suitable portable energy sources. Researches show that chargeable batteries and fuel cells are the most appropriate energy source for AUVs in near future. The main purpose of thesis is the modeling and obtaining the governing equations for Aluminum/Air batteries containing seawater, the so-called semi fuel cell. The steady state governing equations include Navier-Stocks equations (Hydraulic-Boundary layer), chemical ionic species mass balance at boundary layer velocity field, electrochemical equations in the electrolyte and the electrode surface, equations of motion of the hydrogen bubbles and equations for the... 

In a polyvinyl alcohol (PVA) plant, equal moles of methyl acetate are produced as byproduct for every mole of PVA. Since there is a little demand for impure methyl acetate, it is converted to methanol and acetic acid as raw materials of PVA plant via hydrolysis reaction. Duo to the small equilibrium constant of hydrolysis reaction of methyl acetate, the conventional process (including reaction and separation sections) suffers some problems such as large recycle flow and high energy consumption. Therefore, reactive distillation is introduced as an alternative for these processes. Since the reactive distillation integrates both reaction and separation in a single vessel, it has more complex... 

There are many limitations to determine relationships within biological systems. Among the limitations of these systems, one can consider the lack of sufficient information about them, such as the complete knowledge of many networks, the lack of reaction information, the complexity of the analysis of these reactions, etc. One of the methods to analyze these systems is called flux balance analysis. This method consists of three parts: objective function, equal constraints and unequal constraints. Among the features available in this method, we can mention less need for experimental information and no need for high processing systems. In order to determine the objective functions in this... 

Oxidative coupling of methane (OCM) in a fixed bed tubular reactor over Mn-Na2WO4/SiO2 catalyst has been studied. Four kinetic models have been considered for OCM reactions. Based on an objective function and using genetic algorithm, kinetic parameters have been estimated. A reactor tube with 20 mm diameter and 400 mm length surrounded by molten salt for removing heat of reaction has been used for experimental study. Effects of different factors such as CH4/O2 ratio, nitrogen content in feed and contact time are investigated experimentally and by simulation. A good agreement has been observed between simulation and experimental data. Oxidative coupling of methane (OCM) in an industrial fixed... 

In this thesis we are about to simulate and control an MTBE production unit which use membrane instead of azeotropic distillation tower. At first an MTBE Production Unit with two distillation towers in separation part is simulated whit traditional method. One of these distillation towers is azeotropic. Then azeotropic distillation tower is replaced with membrane.After simulation the unit with best process indicators is selected. The goal is minimization of fixed and operating costs.In the next stage the best control loops in each unit is selected. The unit with best control indicators is determined. Control indicators are load rejection and set point tracking. All units have been simulated... 

Cell of fuel methanol can store fuel easily, because they can suitable for resources of energy with ambulant applications. As for with the extensive of electrical haul instruments, they attention to the use of fuel cell methanol. In this project a fuel cell methanol consist of different branches such as cathode, Anode, substrates of membrane and influx, has modeled with the form of flat three dimensional. This model consist of ambulant theorems, transfer of mass, chemistry theorems and reflexes of electro chemistry in spongy environment. As for with a little knowledge that is related to the oxidation of methanol, the first research is related to this reflex and the knowledge of mathematic... 

Many petroleum engineering operations, such as drilling, well completions, and workover, may cause an alteration in the properties of hydrocarbon-bearing formations, including porosity and permeability. Solid and fluid influx into the reservoir in an overbalanced pressure condition can cause permeability reduction from formation damage in the invaded zone. While the solid invasion is limited to a few inches away from the wellbore, the fluids will invade significantly deeper into the formation. Therefore, the invasion of fluids may be considered as the primary mechanism that causes the near-wellbore damage. Correct quantification of the damage is an important component for predicting well... 

Layer melt crystallization is one of the most attractive and productive separation methods in the chemical industry. One of the most important coal tar components, which is present in concentration between 10 to 12% is naphthalene. One of the most commonly used techniques for producing naphthalene crystallization. In this thesis, the layer melt crystallization in a mixture of naphthalene and benzothiophene has been investigated using computational fluid dynamics. The simulation of crystallization was performed in Comsol Multiphisics version 5.6 and the thickness of the crystal layer was obtained according to the time. At first, simulation results were verified with the labroratory results of... 

Management decisions, enhanced oil recovery, and reservoir development plans in petroleum industries are based on predictions by reservoir simulation. Due to uncertainties in model parameters or engineering assumptions, the simulation results are not accurate, while they are correct. For more accurate estimation of unknown production quantities, it is required to characterize the unknown parameters and its uncertainty. By using static data alone the result of characterization is unreliable and unsure, therefore dynamic data use practically. In reservoir engineering literature, this is called “History Matching”.The ensemble Kalman filter is an optimal recursive data processing algorithm based... 

In this thesis, a reduced model of a distributed one-dimensional Solid Oxide Fuel Cell (SOFC) system is presented. Consequently the reduced model is used to estimate the states of the exact model. The reduced model is derived using the exact solution of the distributed model and implementing the Karhunen-Loève-Galerkin procedure. To achieve an exact solution of the distributed model, method of lines is used. In the method of lines, accuracy of the solution depends on the number of grid points. To increase the accuracy, the number of grid points should be increased which will lead to a high order dynamic model. Such a model is not suitable for state estimation, optimization or control... 

this is one of the most widely used is the weighted residual method. The advantages of this method is likely to reach an appropriate solution is (in this project collocation method for solving systems of differential equations is used). After solving steady-state model with the lowest number of variables come to turn the control measures, including non-linear design of a Kalman Filter incentives that could be the orthogonal modulation system (which requires less computational time and good accuracy) as a representative of the system in the state estimation, optimization and control system used. In the end, offering a range of control methods such as multivariate linear and nonlinear... 

Selecting an appropriate control structure is an important subject in the design of control systems. Distillation column is one of the most popular and widely used unit operations in industry which complete understanding of its operability and controllability is one of the most important issues in the process control engineering. The present work studies the method of Output Controllability Index for nonlinear systems and compares it with Relative Gain Array and Condition Number. By using this index, the extent of intrinsic controllability of a process can be identified quantitatively in the absence of any controller. Also, the controllability of the process can be stated numerically or... 

Recently experiences in chemical processes approved that periodic operation for some of the processes (e.g. ion exchangers, activated sludge tanks, etc) were being successful. The performance and/or effectiveness of process due to periodic changes in the systems input, such as concentration, feed or coolant temperature and other possibilities, typically express whether in term of yield or selectivity improvement. Though, prominent issue in this type of dynamical control problem is optimal frequency and amplitude in the cycle. Supporting mathematics, include two main approaches: (1) the Hamilton-Jacobi approach based on the maximum principle and (2) a frequency domain approach using second... 

In this work, a model was presented for an MCFC fuel cell with internal reforming and combustion chamber. The model consists of mass and heat transfer equations beside the chemical and electrochemical reaction rate equations. Velocity distribution due to reactions and temperature distribution along the cell is considered. The model has been simulated in steady state form using finite difference method in MATLAB package environment accompanied by the analysis of the dynamic behavior of cell using method of lines in Simulink environment. Simulation results have been validated with experimental data extracted from literature. The last part of the work concerns with sensitivity analysis of some... 

There is many Nonlinear process in industry which are not control able with classic control methods. Model predictive control is a very useful method of control for nonlinear processes.
The nonlinearity of polymerization reactors are considerable in modeling, simulation, dynamic study and control .Design of free radical polymerization in continues reactors are very populated in industries.in this thesis modeling of free radical polymerization for polyvinyl acetate in industrial scale is studied for dynamic behavior studies of CSTR and design of Model predictive control system for the CSTR.
One of the important challenges in control system for this reactor is the existence of delay... 

High efficiency and low-emission fuel cells have the capacity to replace fossil fuels for energy supply concerns. Solid oxide fuel cells operate in relatively high temperature and have power plant applications. Hence, they are acquainted to be coupled with cycle gas turbine to reduce the cost and increase the overall system efficiency. The control of these hybrid systems is so important. Due to the system nonlinearity and having more than one controlled variable, its control with classic methods would be difficult. The model based predictive control is used as an alternative to mitigate these difficulties. In addition to their high performance, their extension to the multivariate case would... 

High efficiency and low-emission fuel cells have the capacity to replace fossil fuels for energy supply concerns. Solid oxide fuel cells operate in relatively high temperature and have power plant applications. Hence, they are acquainted to be coupled with cycle gas turbine to reduce the cost and increase the overall system efficiency. The control of these hybrid systems is so important. Due to the system nonlinearity and having more than one controlled variable, its control with classic methods would be difficult. The model based predictive control is used as an alternative to mitigate these difficulties. In addition to their high performance, their extension to the multivariate case would... 

In recent years, due to the development of smart wells, optimization of waterflooding by injection/production rate control has receivedsome interests. We can postpone breakthrough time and increase the sweep efficiency by using inflow control valves (ICV). Due to complexity of reservoirs, existence of constraints and numerous influencing parameters, we need a robust and suitable optimization approach to overcome such problems. In this thesis, model predictive control (MPC) is chosen to be our optimization approach. MPC is suitable for constrained multi variable functions. Genetic algorithm is was chosenas optimizer. Eclipse reservoir simulator was used for reservoir simulation. Eclipse input... 

Continuous synthesis of different kinds of industrial copolymers plays an important role in economics of the polymer industry. But copolymerization reactions are complex and with a high degree of nonlinearity so the control problem in this case needs a detailed study on system dynamic behavior. One of the solutions is using a optimal control method in the shape of predictive controllers. The main goal in this thesis is to design a generalized multi-varriable predictive controller for a solution copolymerization of methyl methacrylate and vinyl acetate in a continuous stirred tank reactor with separator and recycle stream. In this study, after simulating the nonlinear model of the process... 

In recent years, fuel cells have been proposed as an alternative option to conventional energy conversion systems. Fuel cell is an electrochemical system that can convert chemical energy to electrical energy without combustion. High efficiency, low temperature performance, poor pollution, good reliability, flexibility in the production potential, low start-up time and high life expectancy are the major advantages of this system. The most important barriers to the use of fuel cells are high cost polymer membrane and using expensive platinum catalysts. Modeling of fuel cells in general will meet two objectives. The first, due to the complexity of the processes taking place within the cell,...