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Öğe Comparative assessment and optimization of fuel cells(Pergamon-Elsevier Science Ltd, 2015) Mert, Suha Orcun; Ozcelik, Zehra; Dincer, IbrahimIn this study, a comprehensive exergoeconomic analysis and a multi-objective optimization study are performed for four different types of fuel cell systems, in order to determine their maximum power production capacities, exergy efficiencies, and minimum production costs, by use of a genetic algorithm method. The investigated fuel cell types are Polymer Electrolyte Membrane (PEMFC) and Direct Methanol (DMFC) for low temperature fuel cells, and Solid Oxide (SOFC) and Molten Carbonate (MCFC) for high temperature fuel cells. The selected fuel cell systems are modeled exergetically and exergoeconomically. After modeling, the cases are studied parametrically with various available operating conditions, such as temperature, pressure, surrounding temperature and pressure, current density, and relative humidity, using the developed computer program MULOP (Multi-Objective Optimizer). For the low temperature fuel cells it is observed that the efficiencies are in the range of 10-30% and the costs are around $3-4/kW. On the other hand, for the high temperature fuel cell systems, efficiencies are in the range of 15-45% and the costs seems to be $0.003-0.01/kW. The results show that high temperature fuel cells operate more effectively for large scale applications. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Öğe Comparative assessment and optimization of fuel cells(Pergamon-Elsevier Science Ltd, 2015) Mert, Suha Orcun; Ozcelik, Zehra; Dincer, IbrahimIn this study, a comprehensive exergoeconomic analysis and a multi-objective optimization study are performed for four different types of fuel cell systems, in order to determine their maximum power production capacities, exergy efficiencies, and minimum production costs, by use of a genetic algorithm method. The investigated fuel cell types are Polymer Electrolyte Membrane (PEMFC) and Direct Methanol (DMFC) for low temperature fuel cells, and Solid Oxide (SOFC) and Molten Carbonate (MCFC) for high temperature fuel cells. The selected fuel cell systems are modeled exergetically and exergoeconomically. After modeling, the cases are studied parametrically with various available operating conditions, such as temperature, pressure, surrounding temperature and pressure, current density, and relative humidity, using the developed computer program MULOP (Multi-Objective Optimizer). For the low temperature fuel cells it is observed that the efficiencies are in the range of 10-30% and the costs are around $3-4/kW. On the other hand, for the high temperature fuel cell systems, efficiencies are in the range of 15-45% and the costs seems to be $0.003-0.01/kW. The results show that high temperature fuel cells operate more effectively for large scale applications. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Öğe Comparative assessment and optimization of fuel cells(Pergamon-Elsevier Science Ltd, 2015) Mert, Suha Orcun; Ozcelik, Zehra; Dincer, IbrahimIn this study, a comprehensive exergoeconomic analysis and a multi-objective optimization study are performed for four different types of fuel cell systems, in order to determine their maximum power production capacities, exergy efficiencies, and minimum production costs, by use of a genetic algorithm method. The investigated fuel cell types are Polymer Electrolyte Membrane (PEMFC) and Direct Methanol (DMFC) for low temperature fuel cells, and Solid Oxide (SOFC) and Molten Carbonate (MCFC) for high temperature fuel cells. The selected fuel cell systems are modeled exergetically and exergoeconomically. After modeling, the cases are studied parametrically with various available operating conditions, such as temperature, pressure, surrounding temperature and pressure, current density, and relative humidity, using the developed computer program MULOP (Multi-Objective Optimizer). For the low temperature fuel cells it is observed that the efficiencies are in the range of 10-30% and the costs are around $3-4/kW. On the other hand, for the high temperature fuel cell systems, efficiencies are in the range of 15-45% and the costs seems to be $0.003-0.01/kW. The results show that high temperature fuel cells operate more effectively for large scale applications. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Öğe Exergoeconomic based multi-objective optimisation of a solid oxide fuel cell system(Inderscience Enterprises Ltd, 2014) Mert, Suha Orcun; Ozcelik, Zehra; Dincer, IbrahimIn this study, the multi-objective optimisation of a solid oxide fuel cell (SOFC) system by defining the objective functions to maximise the power output, energy efficiency and exergy efficiency, and minimise the cost under various constraints is conducted. In this regard, energy, exergy and exergoeconomic analyses are performed. Some specific cases are considered and studied parametrically by varying practical operating conditions, namely temperature, pressure, current density and stack assembly thickness. An exergoeconomic model is developed for the system and incorporated into the developed computer program MULOP (multi-objective optimiser) which is based on a genetic algorithm to investigate the system parametrically, depending on the multi-objective optimisation of the objective function ratios. The best result obtained for each objective function is 1.65 W for the power produced, 0.242 and 0.269 for both exergy and energy efficiencies, respectively, and 0.0017 $/W for the cost generated.Öğe Multi-objective optimization of a direct methanol fuel cell system using a genetic-based algorithm(Wiley-Blackwell, 2013) Mert, Suha Orcun; Ozcelik, ZehraThe multi-objective optimization of a direct methanol fuel cell system was conducted with the objective functions of maximizing both the power output and energy and exergy efficiencies depending on the comprehensive exergy analysis of this study. This advanced model is mounted into the developed computer program multi-objective optimizer which is based on an improved genetic algorithm. The problem is solved parametrically depending on the on the multi-objective optimization objective function ratios which allows a chance to investigate the trade-offs and the importance of the objectives. The investigated parameters are the varying available operating conditions, such as temperature, concentration, and current density. The best results found for each objective were 9.72W for the power produced and 10.732 and 10.467 energy and exergy efficiency, respectively. However, the best optimum for the overall investigation, taking the fitness function into consideration, was 9.59W for the power and 10.248 and 9.995 energy and exergy efficiencies. Copyright (c) 2012 John Wiley & Sons, Ltd.Öğe Multi-objective optimization of a vehicular PEM fuel cell system(Pergamon-Elsevier Science Ltd, 2011) Mert, Suha Orcun; Ozcelik, Zehra; Ozcelik, Yavuz; Dincer, IbrahimThe multi-objective optimization of a vehicular fuel cell system was conducted in this study with the objective functions for maximizing the power output, both energy and exergy efficiencies, and minimizing cost generation (through exergoeconomics). The cases were investigated parametrically using varying operating conditions, such as temperature, pressure, surrounding temperature and pressure, current density, humidity and membrane thickness. A computer program was developed (MULOP-The Multi-Objective Optimizer) and a genetic algorithm based solver was applied to the program for dealing with the multi-objective problems. It was seen that the variation of the cost and work values at the same work, energy, and exergy fractions are in opposite directions. This study not only calculates the minimum result of cost and maximum results of work, energy and exergy efficiencies, but also improves the computer program for solving general multi-objective optimization problems. The selection of the optimum value depends on the requirements of the system that will be used The Pareto solution values of the multi-objective problem are 3.31 $/GW, 118 kW, 0.49 and 0.55 from the cost, work, energy efficiency and exergy efficiency points of views respectively. (C) 2011 Elsevier Ltd. All rights reserved.Öğe SINGLE OBJECTIVE SUPPLY CHAIN NETWORK OPTIMIZATION AROUND ACRYLONITRILE PLANT(Int Journal Contemporary Economics & Administrative Sciences, 2019) Armay, Sinem; Ozcelik, Zehra; Ozcelik, YavuzIn this study, a profit oriented supply chain network optimization is performed on an acrylonitrile plant. the network consists of three suppliers which provide two necessary raw materials (propylene and ammonia) for the production of acrylonitrile, one production plant and four customers. in the transportation of the raw materials and product, either highway transportation or sea transportation can be preferred with respect to constraints to achieve maximum profit. To investigate the effects of constraints for raw materials purchased from suppliers, product sold to customers, production capacity of the plant and amount of raw materials & product transported by alternative transportation modes on profit maximization, four cases are performed within the framework of this study. in the solution of this single objective optimization problem GAMS, MATLAB and Solver Tool of Excel are used. in MATLAB, "fmincon" solver; in GAMS program "Cplex", "LindoGlobal" and "Baron" solvers are preferred whereas "Simplex" is used in Excel. According to the results obtained in each program, it is seen that maximum achievable profit changes from 3,869,389 to 4,664,841 $/year and amount of acrylonitrile produced is 79,040 tonnes/year (in the first two cases) and 90,000 tonnes/year (in the consecutive two cases).