Thermodynamic Study of Operation Properties Effect on Polymer Electrolyte Membrane Fuel Cells (PEM) (original) (raw)
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Detailed thermodynamic analysis of polymer electrolyte membrane fuel cell efficiency
International Journal of Hydrogen Energy, 2013
It is common knowledge that efficiency of fuel cells is highest when no electric current is produced while when the fuel cell is really working, the efficiency is reduced by dissipation. In this paper the relation between efficiency and dissipation inside the fuel cell is formulated within the framework of classical irreversible thermodynamics of mixtures. It is shown that not only dissipation influences the efficiency but that there are also some other terms which become important if there are steep temperature gradients inside the fuel cell. Indeed, we show that the new terms are negligible in polymer-electrolyte membrane fuel cells while they become important in solid oxide fuel cells. In summary, this paper presents a formulation of non-equilibrium thermodynamics of fuel cells and provides analysis of efficiency in terms of processes inside the fuel cells, revealing some new terms affecting the efficiency.
Renewable and Sustainable Energy Reviews, 2019
Polymeric Electrolyte Membrane Fuel Cell (PEMFC) modeling considering thermal and electrical behavior in a coupled manner is a key aspect when evaluating new designs, materials, physical phenomena or control strategies. Depending on the behavior to be emulated, it is important to choose the modeling technique that best suits the needs required. In this sense, this paper describes the most commonly used PEMFC modeling techniques in the context of analytical-mechanistic approach, semi-empirical approach based on theoretical formulation and empirical correlations, as well as empirical approach based on experimentation with a real system. In addition, an in-depth analysis of PEMFC models at the cell and stack level that emulate the thermal and electrical behavior of these systems in a coupled manner is carried out. A chronological classification of the most relevant models has been made based on the modeling technique used, purpose of the model, state and dimension of the model, and the real system, other developed models or experimental results that have been used to validate the proposed new model. Additionally, guidelines to improve the energy efficiency of PEMFC systems through the development of new models are given.
The main objective of this work is to give information on the behavior of three small PEMFC (Polymer Electrolyte Membrane Fuel Cell/Proton Exchange Membrane Fuel Cell) prototypes under static and dynamic load conditions. This is a fuel cell that holds promise in the use for energy in automotive and household applications. A computational model was developed to simulate the static and dynamic performance of this particular type of fuel cell. This model is based on electrochemical equations and takes into consideration the advantages and disadvantages of the device in order to generate power. The model takes into consideration the operating and design parameters of the materials, with the results being compared with practical experiments. This research gives the possibility to infer, from steady state and dynamic studies, on the design of PEMFC's of different sizes and also to develop a further research on the need for control such as of hydrogen and oxygen pressure and flow. The study of sizing of the fuel cell is also an invaluable asset due to the low cost of the simulation.
The Characteristic Thickness of Polymer Electrolyte Membrane and the Efficiency of Fuel Cell
Heat Transfer Engineering, 2009
We propose a simple diffusion model of a PEM fuel cell and perform its thermodynamic analysis. Our description is based on a set of two mass balance equations involving water and proton transport through the membrane coupled with two reaction equations describing the electrochemical reactions at the electrodes. Equations for the water and proton flux densities are constructed in a linearized form suitable for the analysis from the point of view of irreversible thermodynamics. In terms of our simplified model, relations for the characteristic thickness of a PEM membrane is derived, and the maximum efficiency of a fuel cell is evaluated, both as functions of the transport properties of the PEM material.
Asia-Pacific Journal of Chemical Engineering, 2009
Abstract The aim of this paper is to present a simple 3D computational model of a polymer electrolyte membrane fuel cell (PEMFC) that simulates over time the heat distribution, energy, and mass balance of the reactant gas flows in the fuel cell including pressure drop, humidity, and liquid water. Although this theoretical model can be adapted to any type of PEMFC, for verification of the model and to present different analysis it has been adapted to a single cell test fixture. The model parameters were adjusted through a series of ...
Advances in Polymer Technology
Fuel cells are energy conversion devices that directly convert chemical energy of fuels such as hydrogen to useful work with negligible environmental impact and high efficiency. This study deals with thermodynamic analysis and modeling of polymer electrolyte membrane fuel cell (PEMFC) power systems for portable applications. In this regard, a case study of powering a computer with a PEMFC is presented. Also, an inclusive evaluation of various parameters such as voltage polarization, overall system efficiency, power output, and heat generation is reported. In addition, a parametric study is conducted to study the effect of many design and operation parameters on the overall efficiency. Results show the direct influence of current density and temperature values on optimization of the design parameters in PEMFCs.
The dynamic and steady state behavior of a PEM fuel cell as an electric energy source
Journal of Power Sources, 2006
The main objective of this work is to extract information on the internal behavior of three small polymer electrolyte membrane fuel cells under static and dynamic load conditions. A computational model was developed using Scilab [SCILAB 4, Scilab-a free scientific software package, http://www.scilab.org/, INRIA, France, December, 2005] to simulate the static and dynamic performance [J.M. Correa, A.F. Farret, L.N. Canha, An analysis of the dynamic performance of proton exchange membrane fuel cells using an electrochemical model, in: 27th Annual Conference of IEEE Industrial Electronics Society, 2001, pp. 141-146] of this particular type of fuel cell. This dynamic model is based on electrochemical equations and takes into consideration most of the chemical and physical characteristics of the device in order to generate electric power. The model takes into consideration the operating, design parameters and physical material properties. The results show the internal losses and concentration effects behavior, which are of interest for power engineers and researchers.
2006
A thorough analysis of a polymer electrolyte membrane (PEM) fuel cell system is presented. A generalized performance model of a single PEM fuel cell is developed and applied in a semi-empirical form for a Ballard Mark V 35-cell, 5 kW PEM fuel cell. A thermodynamic and economic analysis of the components and of the whole system is performed. The purpose of this study is to explore the intrinsic relations among various fuel cell system performance and cost indicators in order to provide insights for new cost effective and high performance designs. Optimization techniques have been applied in order to determine the optimal design and operation mode of the system. An application of the system onboard merchant ships has been considered as an example.
Design and optimization of polymer electrolyte membrane (PEM) fuel cells
The performance of polymer electrolyte membrane (PEM) fuel cells is studied using a single-phase two-dimensional electrochemical model. The model is coupled with a nonlinear constrained optimization algorithm to determine an optimum design of the fuel cell with respect to the operation and the geometrical parameters of cathode such as the air inlet pressure, the cathode thickness and length and the width of shoulders in the interdigitated air distributor. In addition, the robustness of the optimum design of the fuel cell with respect to uncertainties in several electrochemical reaction and species transport parameters (e.g., gas diffusivity, agglomerate particle size, etc.) is tested using a statistical sensitivity analysis. The results of the optimization analysis show that higher current densities at a constant cell voltage are obtained as the inlet air pressure and the fraction of the cathode length associated with a shoulder of the interdigitated air distributor are increased, and as the cathode thickness and the length of the cathode per one interdigitated gas distributor shoulder are decreased. The statistical sensitivity analysis results, on the other hand, show that the equilibrium cathode/membrane potential difference has the largest effect on the predicted polarization curve of the fuel cell. However, the optimal design of the cathode side of the fuel cell is found not to be affected by the uncertainties in the model parameters such as the equilibrium cathode/membrane potential difference. The results obtained are rationalized in terms of the effect of the fuel-cell design on the air flow fields and the competition between the rates of species transport to and from the cathode active layer and the kinetics of the oxygen reduction half-reaction. #