Sharif Digital Repository

Optimization always has been a major industrial field of study. Optimization is the process of finding the best result based on some events. In design, construction and maintenance of any kind of engineering system ,engineers must take a lot of decisions in the case of management or engineering at different levels in order to minimize the attempts to reach the optimum conditions and obtain the maximum profit on the other side. high speed of processing and litle time for calculations by using computers is very common nowadays which is caused in many improvements in optimization approaches. In this thesis some different classical optimization methods have been applied on Williams-Otto reactor... 

In industries there are many nonlinear processes which cannot be easily controlled with classical methods. Model predictive control is a useful method for nonlinear processes which not only has high efficiency, but also extension of this control to interferential multi variable case, with constraint on the controlled and manipulated variables and other problematic dynamic specifications such as slow dynamics and inverse response is very simple. Industrial polymerization processes are regarded as significant nonlinear processes. Optimization and control of polymerization reactors have considerable importance in process applicability and in economics. The molecular structure of polymer such as... 

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... 

Ever-increasing energy consumption and consequent extensive greenhouse gas (GHG) emissions have become two major global challenges for all human beings in the 21st century. If this trend of increasing energy consumption continues, our primary energy reserves willbe exhausted very soon.One solution is, shift of primary energy resources from fossil fuels to renewable energy could greatly reduce the current heavy dependence upon fossil fuels. Renewable energies have small share in the global energy market, therefore couldn't be a main method in the mid-term. Because of the low efficiency and consequent extensive GHG emissions of the conventional power generation that producing major amount of... 

In the industry, there are nonlinear processes that can not be controlled with classical methods. Also, there are many processes that are more than one controlled variable that with classical methods, the design of a multiple input - multiple output controler is very difficult for them as well as the constraints on the inputs and outputs of the process exist, using classical controllers will be far more difficult. A model-based predictive control method for controlling nonlinear processes is useful in addition to having very high efficiency, extended to multi-mode interference together with constraints on the control variables and other controlled Problem with dynamic properties such as... 

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... 

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... 

Molten carbonate fuel cell (MCFC) is a kind of high operating temperature fuel cells (600-800℃), tupically used for stationary power plant. These fuel cells have high efficiency (about 50%), but expensive to produce electricity. Hence, fuel cells are integrated into gas turbine cycle to decrease cost and increase efficiency of system. In this work, an integrated pressurized molten carbonate fuel cell is selected. Then, structure of selected process is changed and two new systems have proposed. Then, steady-state and dynamic behaviors of three systems were simulated separately, and their performances were compared. Efficiency increased about 5% in two new structures. Total power of system,... 

Integrated SOFC plants, because of the high efficiency and optimum energy consumption, are important processes that have many applications. According to the importance of these plants, their optimum operability and favorable operations are also very important. One of the ways to optimize the process performance is the suitable selection of the control structures. The objective of this project is to analyze the operability or inherent controllability of integrated SOFC plants in the absence of any controller. In this work, the controllability of the process have been investigated with using the output controllability index and the other indexes such as relative gain array, singular value and... 

The purpose of this project is to study the interactions between process design and process control in a gas transmission pipeline. A part of gas pipeline in two conditions is considered, 1: The gas pipeline that has nominal structure and 2: the one with optimal structure by using an economic objective function that considers the capital and operation cost. To aim this object, by creation of an interface to communicate decision variables between MATLA (as an optimizer and controller engine) and Aspen HYSYS (as a pipeline simulator) is attempted to design and then control the pipeline with to control algorithms PI and MPC. Finally the interaction between process design and process is... 

The application of fuel cell systems as sources of clean energy production is common. Control, performance optimization, design, manufacturing and the operation management are considered as significant research interest of the fuel cell in academic circles. A major problem, at least in the advanced model-based control, is the slowness of solving the nonlinear multi-scale model (time). One option would be using the black-box neuro-fuzzy models. Then if the predictive controller is used for this distributed system, calling the output of neuro-fuzzy model allocated a negligibility proportion in time of calculations during the optimization. In this project, the data generated by a dynamic... 

Fuel cells are considered as one of the most promising for production of efficient and low-polluting electrical power. Hence, they can be a suitable alternative for fossil fuel sources. The solid oxide fuel cell (SOFC) is a direct conversion process, which works at high operating temperature (about 1000 °C). This high operating temperature makes them suitable for combining with gas turbines to achieve high overall fuel and power efficiency. A hybrid comportment consisting of an SOFC and a turbine (GT) is a multivariable nonlinear and strongly coupled system. On the other hand, total power generation in these systems which is a principal parameter should not be so sensitive to operating... 

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... 

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 this thesis, a model of electrochemical treatment of tumor is simulated by numerical method. The orthogonal collocation method is used for numerical solution. The model is solved in two situations, one in the absence of chemical reaction (water hydrolysis) and the other when chemical reaction is occurring in the electrolyte. In transient mode, it is possible to solve the model in low level currents (about 20 A/m2) by few number of collocation points (about 15 points) and only in a single domain. However, by increasing current, it is necessary to use more points in domain especially in the first 10% of the domain (very close to the electrode) where the maximum rate of diffusion/migration... 

The purpose of this study is the implementation of multi-model predictive control (MMPC) approach for the co-polymerization system of methyl methacrylate - vinyl acetate. Simpler development of local models and controllers and also convenience of understanding the model and controller structure are the main reasons for using this approach. In the first step, RGA analysis has been used for pairing input and output variables. Then the performance of PI controller on the system has been investigated. For designing model predictive controller (MPC) the nonlinear model has been linearized at operational point and the controller has been designed in MPC toolbox of MATLAB software R2013a. In the... 

In thisstudy, a three-dimensional modelbased onpartial differential equations (PDEs) was used foraplanarsolid oxidefuel cellunit. These PDEs were evaluatedregardingthe equations ofconservation involvingelectric, ionic charge, mass,energy andmomentum equilibriums.To investigate the behavior and strength of the presented model, thestatic and dynamic analyses were considered. The trend of the system against thechanges incurrent density, flow rateand fuelflow ratewere investigated.The PDE of the real model evaluated using the finite element method inCOMSOLsoftware and The PDE of the EstimatorisimplementedinMATLABenvironment by orthogonalcollocation method.Kalman Nonlinearobserverto estimate... 

Today, considering the global demand for reducing greenhouse gas emissions, rechargeable batteries are considered as a source of energy in electric vehicles, hybrid electric vehicles and smart grids. In all these applications for secondary batteries, the battery management system requires an accurate estimate state of charge of each cell. However, this estimate is difficult particularly for battery aging. In this study, a lithium-ion battery is modeled by using multidimensional multiphysics modeling and simulated in a comsol. In this simulation, the effect of the thermal conductivity coefficient on the battery temperature, initial salt concentration in electrolyte and the rate of discharge... 

In this project, a viscous instability phenomenon in CO2 injection process has been investigated. The viscosity of CO2 is much less than the reservoir fluid and the resultant mobility ratio results in the instability of sweeping front. The instability may occur in a typical permeable thief zone. This is due to severe change in gas saturation and/or relative permeability of the gas, hence reducing the sweeping efficiency. This process severely affects areal recovery and results in the inefficacy or failure of gas injection process. Here we tried to simulate the phenomena by higher order finite element methods and the results are in agreement with the geometry of thief zone. Indeed, lower...