Optimum design of flow field geometry in polymer fuel cell using genetic algorithm

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  • Summary of Optimum design of flow field geometry in polymer fuel cell using genetic algorithm

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    Abstract

    Fuel cells are electrochemical devices that are used to directly convert fuel into electrical energy. One of the most important types of fuel cells is the polymer fuel cell, which is widely used. In general, two types of optimization can be done in a polymer fuel cell: optimization in design and construction

    optimization of process parameters

    The first category refers to optimization in construction, to things such as the type of flow channel, channel geometry, material of the components of the cell, as well as a suitable configuration. returns Although these parameters are very important and effective parameters, they cannot be changed in any way during the process and are fixed throughout the process. The second category, which is related to functional parameters or process parameters, includes parameters such as anode side pressure, cathode side pressure, operating temperature of the fuel cell, input flow rate on the anode and cathode side, etc. are flexible and can change during the process. Due to the problems in the optimization of geometrical parameters, the current research has focused on the optimization of three parameters: anode side pressure, cathode side pressure and operating temperature of a fuel cell, which is of great importance among the process parameters. Power is used. The maximum value of the power curve of the optimality of the parameters (fitness function) is considered.

    In genetic algorithms, the base two coding method is usually used for the parameter values, but for the ease of work and to create more speed, real number coding method has been used in the algorithm used. Also, in order not to lose the fit solutions in the middle generations, the elitist algorithm has been used. The table below shows the values ??obtained for the above three parameters as well as the optimal values ??reported from the article by Suleiman and his colleagues [1]. 

    In this research, the maximum power graphs in terms of partial pressures of the anode and cathode showed that the changes in the pressure on the anode side are much more effective in the output efficiency than the similar change in the pressure on the cathode side, and the sensitivity of the anode pressure is much higher than the cathode pressure, which is the reason for the importance of reactions and fuel consumption on the anode side.

    The value obtained for the operating temperature of the battery shows that the temperature increases up A limit has a positive effect on the efficiency of the battery, but if the temperature exceeds a certain value, the efficiency of the battery will decrease significantly, which can be justified due to excessive drying of the membrane.

    (Tables are available in the main file)

    Foreword

    There are two basic problems in using fossil fuels that make up more than 80% of the consumed energy demand. has The first problem is their limitation, so that these fuels will run out in the near future. According to the estimate provided by the oil companies, between 2015 and 2030, the consumption of crude oil, natural gas and fossil fuels will reach their maximum, and after that fossil resources will face a significant decrease. The ice on the planet, the creation of acid rains, the depletion of the ozone layer, the destruction of agricultural areas and forests due to the excessive extraction of coal from mines, and most importantly the problem of pollution and environmental pollution that will disrupt living conditions.Before 1970, hydrogen energy systems were proposed to solve these two basic problems, and since those years, many scientists have tried to use these systems and develop them.

    Hydrogen is a portable energy with unique characteristics. It is a clean fuel with high output efficiency, light and available. One of its special features is its use in electrochemical processes, which can produce electrical energy when used in fuel cells, which has much higher efficiency and special advantages compared to fossil fuel energy. In the last 20 years, the development and application of these systems has gained a lot of strength.

    1-2 What is a fuel cell?

    A fuel cell is an electrochemical energy converter that converts chemical energy into electrical energy

    (direct current of electricity) does In general, a process of generating electricity from fuel includes several energy conversion steps, which include: (1) burning the desired fuel and turning it into heat (2) creating boiling water and water vapor from the heat (3) using the generated water vapor in the turbine to convert thermal energy into energy Mechanical

    (4) Using mechanical energy in the generator and producing electricity

    A fuel cell summarizes all the above steps in order to produce electricity in one step, in addition to not needing any moving parts. (Figure 1-1) shows how a fuel cell generates electricity in one step.

    Figure (1-1) Direct electricity generation from a fuel cell in one step [2]

    A fuel cell is similar to a battery in some aspects because it contains electrolyte and positive poles. and it is negative and generates DC electricity from electrochemical reactions, but unlike a battery, it requires continuous fuel and oxygen, and unlike a battery, fuel cell electrodes do not undergo chemical changes. It needs to be recharged, of course, provided that it has the ability to recharge, but a fuel cell cannot be discharged as long as oxygen and fuel are injected into it, and it can work for a long time. Oxygen and hydrogen, which are the materials required for fuel cells, are abundantly available and can be found both individually and in combination, for example, hydrogen may be combined with gases such as, Co, and is available or in hydrocarbons such as natural gas or even liquid hydrocarbons such as methanol, also the ambient air contains enough oxygen needed by the fuel cell. On the other hand, the battery has advantages over the fuel cell, which can be mentioned as follows:

    - No heat and water loss by the battery [the heat generated in the battery is much less than the fuel cell]

    - No need to manage the system in the battery

    - No need for a lot of equipment and heavy side costs

    1-3 optimization of polymer fuel cell parameters

    In general, two types of optimization can be done in polymer fuel cell :

    Optimization of process parameters or performance parameters

    Optimization in design and construction of the battery

    1-3-1 Optimization of process parameters

    Optimization in variable parameters including parameters such as temperature, working pressure, ratio of fuel consumption in cathode to anode, humidity temperature, concentration or molarity of fuel, reaction kinetics and so on.

  • Contents & References of Optimum design of flow field geometry in polymer fuel cell using genetic algorithm

    List:

    Chapter 1: 1

    1-1 Preface 2

    1-2 What is a fuel cell? 2

    1-3 optimization of polymer fuel cell parameters 4

    1-3-1 optimization of process parameters 4

    1-3-2 optimization in cell design and manufacturing 5

    1-4 researches conducted on optimization of process parameters of polymer fuel cell 6

    1-5 optimization of process parameters of polymer fuel cell 8

    Chapter two: 11

    2-1 Brief history of fuel cells 12

    2-2 Types of fuel cells: 15

    2-2-1 Alkaline fuel cells 16

    2-2-2 Polymer fuel cells 16

    2-2-3 Phosphoric acid fuel cells 16

    2-2-4 Molten Carbonate Fuel Cells 17

    2-2-5 Solid Oxide Fuel Cells 17

    2-3 How Polymer Fuel Cells Work 17

    2-4 The Importance of Needing Fuel Cells 20

    2-4-1 High Efficiency 20

    2-4-2 adjusting the system according to the need 20

    2-4-3 compatibility with environmental laws 20

    2-4-4 flexibility towards fuel 21

    2-4-5 increasing production and reducing distribution 21

    2-4-6 no need for repair 21

    2-4-7 no emission or minimal dispersion of energy 21

    2-4-8 Simplicity of structure 22

    2-4-9 Small size and dimensions 22

    2-5 Fuel cell applications 22

    2-5-1 Power systems 23

    2-5-2 Transportation systems 24

    2-5-3 Portable systems 24

    2-5-4 Audio and video devices 24

    2-5-5 Military systems 24

    Chapter three: 25

    3-1 Introduction 26

    3-2 Genesis of genetic algorithm 27

    3-3 Genetic algorithm 28

    3-3-1 main operators GA 29

    3-3-1-1 Coding methods 29

    3-3-1-2 Initial population 31

    3-3-1-3 Fitness function 32

    3-3-1-4 Selection 32

    3-3-1-4-1 Selection of rotary wheel (RWS) 33

    3-3-1-4-2 Competitive selection 34

    3-3-1-5 Integration 35

    3-3-1-6 Mutation 37

    3-3-1-6-1 Mutation probability) 38

    3-3-1-7 Other genetic operators 38

    3-3-2 Genetic algorithm with elite Simple bureaucracy 38 3-3-3 replacement methods 39 3-3-4 convergence criteria 40 3-3-5 performance criteria 3-3-6 GA differences with conventional optimization methods [21] 41 3-3-7 GA strengths 42 3-3-8 GA weaknesses 42

    3-3-9 When GA is used 43

    3-3-10 Applications of GA 43

    3-4 Optimization of fuel cell process parameters using genetic algorithm 44

    3-4-1 Use of analytical solution in the current genetic algorithm 44

    3-4-1-1 Use of practical tests 45

    3-4-1-2 using CFD solution 46

    3-4-1-3 using analytical solution 46

    3-4-2 defining the fitness function 47

    3-4-3 programming in Manuscript File environment of MATLAB software 48

    3-4-4 using elitist genetic algorithm 48

    3-4-4-1 Coding of parameter values ??48

    3-4-4-2 Selecting the number of initial population and number of generations 49

    3-4-4-3 Applying the link and mutation operator in the current genetic algorithm 50

    3-4-5 Using Lookup Table in the MATLAB Simulink environment 50

    3-4-6 The reason for choosing the current 3 parameters for optimization 52

    Chapter four: 53

    4-1 Polymer fuel cell modeling using analytical solution 54

    4-1-1 Channel modeling 54

    4-1-2 MEA modeling 55

    4-1-3 Equation solving methodology 57

    4-2 Validation of modeling with practical tests 57

    4-3 constant modeling parameters 61

    Chapter five: 62

    5-1 values ??of fitness obtained from analytical solution 63

    5-2 Implementation of genetic algorithm linked with MATLAB Simulink 63

    5-3 Effect of temperature on fuel cell performance 65

    5-4 Effect of pressure on fuel cell performance 66

    5-5 importance of anode pressure compared to cathode pressure 67

    6-5 three-dimensional temperature-pressure diagrams 70

    Sixth chapter: 72

    6-1 conclusion 73

    6-2 suggestions 74

    List of references 75

    Appendix A 78

    MATLAB program linked with MATLAB Simulink 78  84

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Optimum design of flow field geometry in polymer fuel cell using genetic algorithm