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pem-fuel-cell
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High temperature proton exchange membrane fuel cells: Advantages and technical challenges
, Article 18th International Congress of Chemical and Process Engineering, CHISA 2008, Prague, 24 August 2008 through 28 August 2008 ; 2008 ; Rowshanzamir, S ; Eikani, M. H ; Sedghid, S ; Peighambardoust, S. J ; Sharif University of Technology
2008
Abstract
High temperature proton exchange membrane fuel cells (HT-PEMFC) are polymeric fuel cells that can operate at 120°-200°C). Preparation of new heat-resistant HT-PEMFC materials, e.g., membrane and electrodes, is the most challenging problem for these kinds of fuel cells. A discussion covers the benefits of HT-PEMFC; challenges in developing novel materials for membranes preparation; polymeric membranes of HT-PEMFC; improvement of high temperature membranes; high temperature membranes characteristics and types; and importance of electrodes porosity for HT-PEMFC. This is an abstract of a paper presented at the 18th International Congress of Chemical and Process Engineering (Prague, Czech...
Optimized cooling system for pem fuel cell stack based on entropy generation minimization
, Article Proceedings of the 7th Biennial Conference on Engineering Systems Design and Analysis - 2004, Manchester, 19 July 2004 through 22 July 2004 ; Volume 1 , 2004 , Pages 97-103 ; 0791841731 (ISBN); 9780791841730 (ISBN) ; Mozafari, A. A ; Sharifian, L ; Sharif University of Technology
American Society of Mechanical Engineers
2004
Abstract
Cell temperature in fuel cells is an important parameter which highly affects fuel cell stack efficiency. A suitable cooling system should satisfy an acceptable temperature range. In this research a relevant cooling system for a specified PEM fuel cell stack has been proposed complying with the criteria and cooling requirements of the fuel cell. The effect of various parameters on the entropy generation and temperature distribution in the cooling plates are surveyed. The number of cooling plates, the number of channels in each cooling plate and the channel width is determined. Two flow regimes namely laminar and turbulent flows of the cooling fluid in channels are analyzed and a design...
Optimization of the pem fuel cell cooling system by entropy generation minimization
, Article 3rd International Conference on Fuel Cell Science, Engineering, and Technology, 2005, Ypsilanti, MI, 23 May 2005 through 25 May 2005 ; 2005 , Pages 441-448 ; 0791837645 (ISBN); 9780791837641 (ISBN) ; Saidi, M. H ; Sharif University of Technology
American Society of Mechanical Engineers
2005
Abstract
Cooling system is essential for high power fuel cells to maintain cells temperature in an acceptable limit. In this paper a suitable cooling system for the PEM fuel cell has been designed and optimized. The design includes the number of the cooling plates, the proper circuit of the cooling channels in the plates, the channel dimensions, the flow rate of the cooling fluid and its temperature. The optimization technique is minimization of the entropy generation through the cooling plates. The design of the cooling channels and plates is such that the plate temperature doesn't exceed from a desired temperature and the temperature variation in the plate becomes minimized. In this design, the...
Construction of The Catalyst Layer of a PEM Fuel Cell Using Electrospray Method
, M.Sc. Thesis Sharif University of Technology ; Morad, Mohammad Reza (Supervisor)
Abstract
Due to Reduction of fossil fuels resources and the pollution caused by using them, it seems inevitable to shift to using reproducible energies. Among different resource of reproducible energy, fuel cell is one of suitable technologies for investigation and development. Fuel cell is an electrochemical system to convert chemical energy of fuel directly to electrical energy. Each fuel cell has seven part (two Bipolar Plate, two electrode, two catalyst layer and polymeric Membrane). Oxidation occur in anode of fuel cell and created electron enters external circuit and then riches the cathode. The positive ion created in the anode reaches the cathode through the membrane (electrolyte) and...
State Feedback Control Proton Exchange Membrane Fuel Cell (Pem) Stack
, M.Sc. Thesis Sharif University of Technology ; Pishvaie, Mahmoud Reza (Supervisor)
Abstract
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,...
An Analytical Study of The Pem Fuel Cell
, M.Sc. Thesis Sharif University of Technology ; Nouri Borujerdi, Ali (Supervisor)
Abstract
In this thesis, the quasi-two-dimensional modeling of polymer electrolyte membrane fuel cell cathode side is presented as a single phase. Polymer membrane fuel cell modeling equations are solved in the equations of continuity, momentum, and chemical species are potential equation. In this report, for modeling the electrochemical reaction in the catalyst layer of the relationship Baltr-Vollmer is used. The present analytical solution based on two fixed pressure gradient and the velocity dependent pressure gradient is developed. Momentum and continuity equations in the model with separation, velocity and pressure field is achieved. By comparing the results of the modeling analysis with...
Effects of Nano Metallic Catalysts on The Life-Time and Efficiency of Proton Exchange Membrane Fuel Cells
, M.Sc. Thesis Sharif University of Technology ; Vesaghi, Mohammad Ali (Supervisor)
Abstract
The Fuel cell is an energy converter which converts the chemical energy of a chemical reaction to electricity and heat directly and without any pollution. One of the most important types of fuel cells is the proton exchange membrane (PEM) fuel cell. The importance of PEM fuel cells is a result of their high energy density, quick start up ability, lower operating temperature, high efficiency and low or zero emissions. Catalysts play an important role in both costs and durability of PEM fuel cells. Alloying the Pt with other metals can increase the activity of the catalysts of the fuel cells and also reduces the amount of costly Pt. In this study, the nanoparticles of Ni were added to the...
The effect of variable catalyst loading in electrodes on PEM fuel cell performance
, Article 3rd International Conference on Fuel Cell Science, Engineering, and Technology, 2005, Ypsilanti, MI, 23 May 2005 through 25 May 2005 ; 2005 , Pages 145-152 ; 0791837645 (ISBN); 9780791837641 (ISBN) ; Farhanieh, B ; Sharif University of Technology
American Society of Mechanical Engineers
2005
Abstract
Catalyst layers are one the important parts of the PEM fuel cells as they are the main place for electrochemical reaction taking place in anode and cathode of the cells. The amount of catalyst loading of this layer has a large effect on PEM fuel cell performance. Non-uniformity of reactant concentration could lead to a variation of current density in anode and cathode catalyst layer. The main reason for this phenomenon is porosity variation due to two effects: 1. compression of electrode on the solid landing area and 2. Water produced at the cathode side of diffusion layer. In this study the effect of variable current density in anode and cathode electrode on cell performance is...
Modeling Reaction and Distribution of Water in Nanopores of the Cathode Catalyst Layer of PEM Fuel Cell
, M.Sc. Thesis Sharif University of Technology ; baghalha, morteza (Supervisor)
Abstract
In the proton exchange membrane fuel cells (PEM, the produced water would be divided into two phases of vapor and liquid. distribution of both liquid and vapor phases in different cell layers affects the performance, the efficiency and the life of a fuel cell significantly. Moreover, Nano pores of the cathode catalyst layer are involved with some phenomena such as electrochemical reaction kinetics, heat and mass transfer and interface phase change. One of the most important problems in the performance of fuel cells is distribution of liquid water in the porous areas. Water flooding in fuel cells causes to delay in oxygen transport to active sites in the catalyst layer because the pores of...
Exergy, economic, and environmental analysis of a PEM fuel cell power system to meet electrical and thermal energy needs of residential buildings
, Article Journal of Fuel Cell Science and Technology ; Volume 9, Issue 5 , 2012 ; 1550624X (ISSN) ; Ehyaei, M. A ; Mozafari, A ; Atabi, F ; Hajidavalloo, E ; Shalbaf, S ; Sharif University of Technology
ASME
2012
Abstract
In this paper, a Polymer Electrolyte Membrane (PEM) fuel cell power system including burner, steam reformer, heat exchanger, and water heater has been considered. A PEM fuel cell system is designed to meet the electrical, domestic hot water, heating, and cooling loads of a residential building located in Tehran. Operating conditions of the system with consideration of the electricity cost has been studied. The cost includes social cost of the environmental pollutants (e.g. CO 2, CO and NO). The results show that the maximum energy needs of the building can be met by 12 fuel cell stacks with nominal capacity of 8.5 kW. Annual average electricity cost of thissystem is equal to 0.39 US$/kWh and...
Economically Optimal and Inherently Safe Design and Operation of Microreactor for Hydrogen Production in Portable Power Generation Devices Such as PEM Fuel Cell
, M.Sc. Thesis Sharif University of Technology ; Rashtchian, Davood (Supervisor) ; Sharifzadeh, Mehdi (Supervisor)
Abstract
Due to high efficiency and modular production ability of fuel cells, they have been used extensively in the power plants, especially in portable devices such as fuel cell vehicles. The commercialization of the equipment is dependent on ensuring the safety of their operations. Many of these platforms employ steam reforming reactions at very high temperature in order to produce the hydrogen, which is implemented as the fuel in the PEM fuel cell. The technique of miniaturization is a promising approach to design a chemical process in which the rate of transport phenomena such as the mass and heat transfer are intensified by reducing the size of the reactor and allowing the process to be run...
Praparation of Nanometric Platinum Coatings on Carbon Substrate (Pt/C) for Catalytic Plates of Fuel Cells
, M.Sc. Thesis Sharif University of Technology ; Ghorbani , Mohammad (Supervisor) ; Afshar, Abdollah (Supervisor)
Abstract
With increasing pollution and decrease in global reservoirs of fossil fuels, a lot of interest has been attracted to fuel cells as efficient and clean energy sources. Polymeric (membrane) fuel cells are special type of fuel cells, which can be built in small dimensions and power. These cells use hydrogen (and oxygen or air) and produce water. In these cells, platinum is used as electrode (and electrocatalyst) both in anode and cathode, due to its low overvoltage for both hydrogen and oxygen. To increase the efficiency of these coatings, it is best to produce platinum particles with maximum area and it automatically leads to nanometric particles. In this thesis, platinum particles are...
Preparation of Proton Exchange Membrane for Microbial Fuel Cell Application
, M.Sc. Thesis Sharif University of Technology ; Mousavi, Abbas (Supervisor) ; Mohammad jafar Abdekhodayi (Co-Advisor)
Abstract
Synthesis and characterization of Nafion/TiO2 membranes whit different solvent (DMF, DMAc, NMP) for proton exchange membrane fuel cell (PEMFC) were investigated in this study. Nafion/ TiO2 nanocomposite membranes have been prepared by solution casting Method. The structures of membranes were investigated by Scanning Electron Microscopy (SEM). Also water uptake, proton conductivity and ion exchange capacity (IEC) of membranes were measured and compared whit Nafion 112 in microbial fuel cell. The membrane was prepared whit DMF solvent has maximum proton conductivity and best morphology and maximum cell voltage
Modeling of Humidity Variation Along Cathode air Channel of PEM Fuel Cell
, M.Sc. Thesis Sharif University of Technology ; Rashtchian, Davood (Supervisor) ; Baghalha, Morteza (Co-Advisor)
Abstract
Fuel cells provide a clean mechanism of energy conversion and they have been given due consideration in recent years. Polymer membrane fuel cells have particularly been considered because of a wide range of their application and their portability. The industrial application of this type of fuel cells is spreading rapidly in recent years. Therefore, optimal design of such technologies of fuel cells may accelerate their industrial application. Bipolar/ end plates are detrimental to high efficiency and power density in fuel cells. Appropriate design of bipolar plates with suitable distribution of gas and the least pressure drop could provide the best possible outlet of reaction...
Modeling and Heat Management in Polymer Electrolyte Membrane Fuel Cell Using Heat pipes for CHP Applications
, M.Sc. Thesis Sharif University of Technology ; Roshandel, Ramin (Supervisor) ; Shafii, Mohammad Behshad (Co-Advisor)
Abstract
Fuel cell-based CHP systems for distributed residential power generation represent an interesting alternative to traditional thermoelectric plants. This is mainly due to the high efficiency obtainable in the production of electricity and heat in a decentralized, quiet and environmental friendly way. The current thesis focuses on the development, in Matlab_Simulink environment, of a complete dynamic model of a residential cogenerative (CHP) energy system consisting of the Proton Exchange Membrane fuel cell (PEMFC), in two scenarios. The first scenario emphasizes on use of fan and usual Heat Exchanger for cooling of Proton membrane fuel cell and conveying generated heat in PEM fuel cell to...
The Effect Of Using Heat Pipes On Heat Management In Pem Fuel Cell- Metal Hydride System
, M.Sc. Thesis Sharif University of Technology ; Roshandel, Ramin (Supervisor) ; Shafii, Mohammad Behshad (Co-Advisor)
Abstract
On-board hydrogen storage systems (as a substitute for fossil fuels) employing high-pressure metal hydrides, promise advantages including high volumetric capacities and cold start capability. In this project, we discuss the development of a system simulation model in Matlab/Simulink platform. Transient equations for mass balance and energy balance are presented. During driving, the bed requires external heat source, which is planned to be supplied by rejected heat from proton-exchange membrane (PEM) fuel cell. Therefore, this study develops a system-level dynamic model of a PEM fuel cell that is capable of characterizing the mixed effects of temperature, gas flow and capacitance, with...
Modeling and Analysis of Optimal Control and Condition Monitoring of Fuel Cell System Based on Performance History
, M.Sc. Thesis Sharif University of Technology ; Roshandel, Ramin (Supervisor)
Abstract
The short life of Polymer Electrolyte Membrane (PEM) fuel cells is one of the critical criteria to their commercialization. A longer operation life time should be achieved to reach high reliability, low $/kWh cost and to use fuel cells as economical alternative energy systems.Therefore,diagnosing degradation mechanisms and the causes of power loss in fuel cell life time is of great importance. Operating conditions affect output power density and performance degradation. To achieve maximum power generation through fuel cell life time, a model is needed which is able to estimate power density and performance degradation simultaneously regarding to operating conditions. In present work, a...
Two Dimensional Computational Modeling of Multiphase Flow in Proton Exchange Membrane Fuel Cells
, M.Sc. Thesis Sharif University of Technology ; Roshandel, Ramin (Supervisor) ; Taghizadeh Manzari, Mehrdad (Supervisor)
Abstract
Performance of Polymer Electrolyte Membrane Fuel Cells (PEMFC) at high current densities is limited to transport of reactants and products. Also at high currents, large amounts of water are gener-ated due to electrochemical reactions. Due to low temperature of PEMFC, some of the steam condenses. The amount of water existing in a PEMFC influences its performance. Shortage of water adversely af-fects cell performance by drying out the membrane. On the other hand, an excessive amount of water blocks pores of porous medium and transport of fuel becomes difficult.
In order to predict flooding and its effects on the PEMFC performance, development of a two-phase flow model is necessary. In this...
In order to predict flooding and its effects on the PEMFC performance, development of a two-phase flow model is necessary. In this...
Modeling Solar Hydrogen Fuel Cell System for Residential Application
, M.Sc. Thesis Sharif University of Technology ; Roshandel, Ramin (Supervisor)
Abstract
The gradual exhaustion of oil and gas resources and the various problems involved in their pollution makes it necessary to promote a renewable energy system. One of the most interesting developments of standalone systems based on the utilization of hydrogen is solar hydrogen system. Central and southern Iran exhibit an excellent solar climate which makes them ideal places for solar hydrogen systems. The economy of Iran is based on oil and it has one of the largest reserves of oil and gas in the world but the reserves would not be enough to meet the domestic and export markets starting in three to four decades. Moreover, elimination of energy subsidies in Iran, will led to more tendencies to...
Experimental Modeling of a Transparent Fuel Cell with Aid of Deep Neural Network to Measure Water Coverage Ratio and Fuzzy Control
, M.Sc. Thesis Sharif University of Technology ; Alasty, Aria (Supervisor) ; Kermani, Mohammad Jafar (Supervisor) ; Boroushaki, Mehrdad (Co-Supervisor)
Abstract
Polymer membrane fuel cell is a rich source of renewable energy. Two problems of short life and low reliability in fuel cells are the main problems of this system. The difference in partial pressure of hydrogen and oxygen causes serious damage to the fuel cell and inefficiency of the electricity production capacity. On the other hand, the life and optimal performance of the fuel cell depends on the moisture content of the membrane because the membrane needs sufficient moisture to pass ions. Transparent fuel cells can be used to study the water in the fuel cell. With direct imaging of this type of fuel cells, the phenomenon of water creation in the fuel cell can be studied with the help of...