PEM Fuel Cell (pem + fuel_cell)

Distribution by Scientific Domains


Selected Abstracts


Electrodes for PEM Fuel Cells

FUEL CELLS, Issue 2 2010
M. L. Di Vona
No abstract is available for this article. [source]


Visualising Liquid Water in PEM Fuel Cells Using Neutron Imaging,

FUEL CELLS, Issue 5 2009
R. Mukundan
Abstract In this article, we review the neutron imaging techniques that have been used to visualise liquid water in PEM fuel cells. A list of the various facilities engaged in this research is provided and the published literature in this field reviewed. Neutron imaging has been successfully used to visualise water dynamics in the flow channels of operating fuel cells. This technique has also been used to understand water removal mechanisms and the importance of membrane hydration and GDL flooding to optimal fuel cell performance. More recently this technique has been applied to imaging the water in fuel cell cross-sections in order to quantify the water contents in the different components of an operating fuel cell. Finally, this technique has also been utilised to examine ice formation during sub-zero operation of single fuel cells. With ongoing improvements in spatial and temporal resolution, neutron imaging can be expected to play a greater role in any fuel cell development related to water transport. [source]


Review: Durability and Degradation Issues of PEM Fuel Cell Components

FUEL CELLS, Issue 1 2008
F. A. de Bruijn
Abstract Besides cost reduction, durability is the most important issue to be solved before commercialisation of PEM Fuel Cells can be successful. For a fuel cell operating under constant load conditions, at a relative humidity close to 100% and at a temperature of maximum 75,°C, using optimal stack and flow design, the voltage degradation can be as low as 1,2,,V·h. However, the degradation rates can increase by orders of magnitude when conditions include some of the following, i.e. load cycling, start,stop cycles, low humidification or humidification cycling, temperatures of 90,°C or higher and fuel starvation. This review paper aims at assessing the degradation mechanisms of membranes, electrodes, bipolar plates and seals. By collecting long-term experiments as well, the relative importance of these degradation mechanisms and the operating conditions become apparent. [source]


Start Up and Freezing Processes in PEM Fuel Cells

FUEL CELLS, Issue 2 2007
M. Oszcipok
No abstract is available for this article. [source]


Transport mechanisms and performance simulation of a PEM fuel cell

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 6 2008
Geng-Po Ren
Abstract A three-dimensional, gas,liquid two-phase flow and transport model has been developed and utilized to simulate the multi-dimensional, multi-phase flow and transport phenomena in both the anode and cathode sides in a proton exchange membrane (PEM) fuel cell and the cell performance with different influencing operational and geometric parameters. The simulations are presented with an emphasis on the physical insight and fundamental understanding afforded by the detailed distributions of velocity vector, oxygen concentration, water vapor concentration, liquid water concentration, water content in the PEM, net water flux per proton flux, local current density, and overpotential. Cell performances with different influencing factors are also presented and discussed. The comparison of the model prediction and experimental data shows a good agreement. Copyright © 2007 John Wiley & Sons, Ltd. [source]


Exergetic performance analysis of a PEM fuel cell

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2006
M. Ay
Abstract In this paper we investigate the effects of thermodynamic irreversibilities on the exergetic performance of proton exchange membrane (PEM) fuel cells as a function of cell operating temperature, pressures of anode and cathode, current density, and membrane thickness. The practical operating conditions are selected to be 3,5 atm for anode and cathode pressures, and 323,353 K for the cell temperatures, respectively. In addition, the membrane thicknesses are chosen as 0.016, 0.018 and 0.02 cm, respectively. Moreover, the current density range of the PEM fuel cell is selected to be 0.01,2.0 A cm,2. It is concluded that exergy efficiency of PEM fuel cell decreases with a rise in membrane thickness and current density, and increases with a rise of cell operating pressure and with a decrease of current density for the same membrane thickness. Thus, it can be said that, in order to increase the exergetic performance of PEM fuel cell, the lower membrane thickness, the lower current density and the higher cell operating pressure should be selected in case PEM fuel cell is operated at constant cell temperature. Copyright © 2005 John Wiley & Sons, Ltd. [source]


A simulated auto-thermal membrane reformer process for a PEM fuel cell micro cogeneration unit

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2009
Dr. Atilla Ersöz
Abstract There are several methods of producing hydrogen-rich gas from fossil resources such as natural gas or naphtha, for example, steam reforming, partial oxidation and auto-thermal reforming. In this paper, an integrated ATR membrane reactor system was simulated. The effect of operating parameters on the product distribution, fuel cell hydrogen utilization and the net electric efficiency of the overall system were discussed. The overall system was integrated with a 1-kWe PEM fuel cell. The ASPEN-HYSIS 3.2 software has been utilized for the simulations and calculations of the fuel processing reactions. Natural gas fuel has been used as feedstock and applied to the simulated flow-sheet model. It was desired to produce hydrogen-rich gas with a low CO formation using an autothermal membrane reformer. A very low CO content with higher content of hydrogen was provided by the membrane reformer, eliminating the use of the conventional preferential oxidation (PrOx) reactor. Different combinations of TATR, S/C, O2/C ratios and UH2 have been parametrically studied. Fuel processing efficiency and net electrical efficiency of all selected operating conditions have been calculated as well. Results indicate that the system parameters are very critical for the appropriate operation of the residential cogeneration system with ATR membrane unit. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]


Membrane reformer PEM cogeneration systems for residential applications,Part A: full load and partial load simulation

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2009
Stefano Campanari
Abstract This two-part paper investigates the performances and economic potential benefits of a fuel cell cogeneration system based on a membrane reformer (MREF), using polymer electrolyte membrane (PEM) fuel cells, applied to residential cogeneration. Part A of this work focuses on the thermodynamic analysis and simulation of the system at full and partial load conditions, discussing its performance by means of a sensitivity analysis carried out under different operating conditions. Part B presents the technoeconomic analysis of the proposed system integrated into a real residential application, dealing with the energy savings and the economic balances, and proposes a preliminary design of the cogeneration unit. The system is based upon a PEM fuel cell, integrated with a membrane reformer (MREF) to form a small-scale, highly efficient cogeneration unit, potentially suitable for application to distributed generation in the residential field. The high purity hydrogen fuel required by the PEM fuel cell is produced in the membrane reformer through hydrogen selective membranes based on a Pd-Ag alloy. The analysis is carried out aiming to define the system energy balances in all the conditions occurring under real operation, including the influence of ambient temperature and of the expected fuel cell efficiency decay with time. The discussion reveals the relevant potential advantages of the MREF solution with respect to fuel cell units based on steam reforming (SR) or auto-thermal reforming (ATR): when compared to these solutions, MREF exhibits a 10% points higher electrical efficiency and requires a much simpler plant layout. These results are the basis for the detailed system technoeconomic analysis carried out in Part B of the work. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]


Visualising Liquid Water in PEM Fuel Cells Using Neutron Imaging,

FUEL CELLS, Issue 5 2009
R. Mukundan
Abstract In this article, we review the neutron imaging techniques that have been used to visualise liquid water in PEM fuel cells. A list of the various facilities engaged in this research is provided and the published literature in this field reviewed. Neutron imaging has been successfully used to visualise water dynamics in the flow channels of operating fuel cells. This technique has also been used to understand water removal mechanisms and the importance of membrane hydration and GDL flooding to optimal fuel cell performance. More recently this technique has been applied to imaging the water in fuel cell cross-sections in order to quantify the water contents in the different components of an operating fuel cell. Finally, this technique has also been utilised to examine ice formation during sub-zero operation of single fuel cells. With ongoing improvements in spatial and temporal resolution, neutron imaging can be expected to play a greater role in any fuel cell development related to water transport. [source]


Ceramic Supported Capillary Pd Membranes for Hydrogen Separation: Potential and Present Limitations

FUEL CELLS, Issue 6 2006
V. Gepert
Abstract Composite ceramic capillaries coated with thin palladium membranes are developed for the production of CO-free hydrogen for PEM fuel cells, via alcohol steam reforming. The composite membranes are tested for pure H2 and N2, as well as for synthetic reformate gas. The aim is to develop a heat-integrated compact membrane reformer for decentralized hydrogen production. In this context, a deep knowledge of the performance, behavior, and necessary treatment of the composite palladium membranes plays a decisive role in process design. The current contribution focuses on the main hurdles met while attempting to exploit the potential of ceramic supported capillary palladium membranes. [source]


A new parameter extraction method for accurate modeling of PEM fuel cells

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 11 2009
M. T. Outeiro
Abstract In this paper, a new parameter extraction method for accurate modeling of proton exchange membrane (PEM) fuel cell systems is presented. The main difficulty in obtaining an accurate PEM fuel cell dynamical model is the lack of manufacturer information about the exact values of the parameters needed for the model. In order to obtain a realistic dynamic model of the PEM system, the electrochemical considerations of the system are incorporated into the model. Although many models have been reported in the literature, the parameter extraction issue has been neglected. However, model parameters must be precisely identified in order to obtain accurate simulation results. The main contribution of the present work is the application of the simulated annealing (SA) optimization algorithm as a method for identification of PEM fuel cell model parameter identification. The major advantage of SA is its ability to avoid becoming trapped in local minimum, as well as its flexibility and robustness. The parameter extraction and performance validation are carried out by comparing experimental and simulated results. The good agreement observed confirms the usefulness of the proposed extraction approach together with adopted PEM fuel cell model as an efficient tool to help design of power fuel cell power systems. Copyright © 2009 John Wiley & Sons, Ltd. [source]


A parametric study of multi-phase and multi-species transport in the cathode of PEM fuel cells

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 8 2008
Nada Zamel
Abstract In this study, a mathematical model is developed for the cathode of PEM fuel cells, including multi-phase and multi-species transport and electrochemical reaction under the isothermal and steady-state conditions. The conservation equations for mass, momentum, species and charge are solved using the commercial software COMSOL Multiphysics. The catalyst layer is modeled as a finite domain and assumed to be composed of a uniform distribution of supported catalyst, liquid water, electrolyte and void space. The Stefan,Maxwell equation is used to model the multi-species diffusion in the gas diffusion and catalyst layers. Owing to the low relative species' velocity, Darcy's law is used to describe the transport of gas and liquid phases in the gas diffusion and catalyst layers. A serpentine flow field is considered to distribute the oxidant over the active cathode electrode surface, with pressure loss in the flow direction along the channel. The dependency of the capillary pressure on the saturation is modeled using the Leverette function and the Brooks and Corey relation. A parametric study is carried out to investigate the effects of pressure drop in the flow channel, permeability, inlet relative humidity and shoulder/channel width ratio on the performance of the cell and the transport of liquid water. An inlet relative humidity of 90 and 80% leads to the highest performance in the cathode. Owing to liquid water evaporation, the relative humidity in the catalyst layer reaches 100% with an inlet relative humidity of 90 and 80%, resulting in a high electrolyte conductivity. The electrolyte conductivity plays a significant role in determining the overall performance up to a point. Further, the catalyst layer is found to be important in controlling the water concentration in the cell. The cross-flow phenomenon is shown to enhance the removal of liquid water from the cell. Moreover, a shoulder/channel width ratio of 1:2 is found to be an optimal ratio. A decrease in the shoulder/channel ratio results in an increase in performance and an increase in cross flow. Finally, the Leverette function leads to lower liquid water saturations in the backing and catalyst layers than the Brooks and Corey relation. The overall trend, however, is similar for both functions. Copyright © 2007 John Wiley & Sons, Ltd. [source]