Channel geometry optimization using a 2D fuel cell model and its verification for a polymer electrolyte membrane fuel cell

This paper studies the optimization method of channel geometries for a proton exchange membrane fuel cell (PEMFC) using a genetic algorithm (GA). The channel and rib widths and channel height are selected as geometry variables. The fuel cell output power is chosen as the cost function for the optimization. In this paper, an in-house genetic algorithm is constructed, and the fuel cell output power is obtained using an interfacing program connected to a commercial computational fluid dynamics (CFD) tool, COMSOL, in a Matlab environment. The 2D PEMFC is used to calculate the performance cost function for computational time and cost. The calculated output power of the PEMFC is delivered to the in-house GA program to check for optimality. After the optimality is checked, the new geometry data is fed back to the COMSOL to calculate the PEMFC output power until the optimization process is finished. Experiments are conducted to support the optimized results using three different channel geometries: channel-to-rib width ratios of 0.5:1, 1:1, and 2:1. A full 3D PEMFC CFD model is constructed using COMSOL to support the 2D CFD optimization results. This paper shows the possibility of applying the geometry optimization process to sophisticated electrochemical reaction systems, such as a PEMFC, using a GA and a commercial CFD tool on the Matlab platform. The geometries and materials can be optimized using this approach to obtain the most efficient performance of an electrochemical system.     

Design for geometric parameters of PEM fuel cell by integrating computational fluid dynamics code with optimization method

The present study is aimed at optimization of the geometric parameters of the proton exchange membrane (PEM) fuel cells through numerical simulation. The approach is developed by integrating a direct problem solver with an optimizer. A commercial computational fluid dynamics code is used as the direct problem solver, which is used to simulate the three-dimensional mass, momentum and species transport phenomena as well as the electron- and proton-transfer process taking place in a PEMFC. On the other hand, the simplified conjugate-gradient method (SCGM) is employed to build the optimizer, which is combined with the direct problem solver in order to seek the optimal geometric parameters, including, for example, the gas channel width fraction, the gas channel height and the thickness of the gas diffusion layer. It is found that the present approach can be applied to determine the optimal set of geometric parameters, and the search process is robust and always leads to a unique final solution regardless of the initial guess.     

A novel surrogate model for channel geometry optimization of PEM fuel cell based on Bagging-SVM Ensemble Regression

Channel structure plays an important role on the performance of proton exchange membrane fuel cell (PEMFC). In this study, the channel geometry of a PEMFC is optimized through genetic algorithm to obtain better performance. For the first time, a machine learning method called Bagging Ensemble Regression is employed as the surrogate model to calculate the fitness value of the algorithm, which accelerates the optimization process. First, a three-dimensional PEMFC simulation model is developed as the optimization prototype through CFD technology. Second, the Bagging ensemble model is trained through training data obtained from the CFD model. Then the Bagging ensemble model is integrated into the genetic algorithm to conduct the optimization process. Finally, the optimal model obtained is compared with the optimization prototype in terms of polarization curves, pressure drop, and reactant distribution, and the advantages of using Bagging ensemble model are discussed. Results show that the optimal model has a smaller pressure drop and a more uniform reactant distribution than the basic model at the expense of just a little power density. The presented surrogate model shows high prediction accuracy with only a small amount of training data, which is superior to the commonly used surrogate models.     

Optimal parameter identification for the proton exchange membrane fuel cell using Satin Bowerbird optimizer

This study proposes precise modeling for the proton exchange membrane fuel cells which present desirable advantages compared with other energy management systems. The presented model can be applied for the simulation of the actual behavior of the proton exchange membrane fuel cells such as the electrical, electrochemical, and mechanical. In the present literature, a newly presented optimizer namely Satin Bowerbird is implemented for the evaluation of the proton exchange membrane fuel cell performance criteria. The Satin Bowerbird optimizer is an evolutionary algorithm that imitates the mating process of the Bowerbirds in the mating season. The Satin Bowerbird optimizer is applied to the different commercial benchmark of proton exchange membrane fuel cell stack to assess the performance of the proposed algorithm. The statistical study is also carried out to show the superiority of the proposed method compared with other schemes. The standard deviation for the Satin Bowerbird optimizer is obtained 0.0941 which is the lowest value amongst the other well‐known approaches. Also, the lowest sum of squared error is calculated for the proposed algorithm. Moreover, the validation of the presented method is done with the experimental data which shows good agreement between the experimental and modeling data.     

A general model of proton exchange membrane fuel cell

In this study, a general model of proton exchange membrane fuel cell (PEMFC) was constructed, implemented and employed to simulate the fluid flow, heat transfer, species transport, electrochemical reaction, and current density distribution, especially focusing on liquid water effects on PEMFC performance. The model is a three-dimensional and unsteady one with detailed thermo-electrochemistry, multi-species, and two-phase interaction with explicit gas–liquid interface tracking by using the volume-of-fluid (VOF) method. The general model was implemented into the commercial computational fluid dynamics (CFD) software package FLUENT^® v6.2, with its user-defined functions (UDFs). A complete PEMFC was considered, including membrane, gas diffusion layers (GDLs), catalyst layers, gas flow channels, and current collectors. The effects of liquid water on PEMFC with serpentine channels were investigated. The results showed that this general model of PEMFC can be a very useful tool for the optimization of practical engineering designs of PEMFC.     

CFD investigating the effects of different operating conditions on the performance and the characteristics of a high-temperature PEMFC

The effects of different operating conditions on the performance and the characteristics of a high-temperature proton exchange membrane fuel cell (PEMFC) are investigated using a three-dimensional (3-D) computational fluid dynamics (CFD) fuel-cell model. This model consists of the thermal-hydraulic equations and the electrochemical equations. Different operating conditions studied in this paper include the inlet gas temperature, system pressure, and inlet gas flow rate, respectively. Corresponding experiments are also carried out to assess the accuracy of this CFD model. Under the different operating conditions, the PEMFC performance curves predicted by the model correspond well with the experimentally measured ones. The performance of PEMFC is improved as the increase in the inlet temperature, system pressure or flow rate, which is precisely captured by the CFD fuel cell model. In addition, the concentration polarization caused by the insufficient supply of fuel gas can be also simulated as the high-temperature PEMFC is operated at the higher current density. Based on the calculation results, the localized thermal-hydraulic characteristics within a PEMFC can be reasonably captured. These characteristics include the fuel gas distribution, temperature variation, liquid water saturation distribution, and membrane conductivity, etc.     

Performance improvement of proton exchange membrane fuel cell by using annular shaped geometry

A complete three-dimensional and single phase CFD model for a different geometry of proton exchange membrane (PEM) fuel cell is used to investigate the effect of using different connections between bipolar plate and gas diffusion layer on the performances, current density and gas concentration. The proposed model is a full cell model, which includes all the parts of the PEM fuel cell, flow channels, gas diffusion electrodes, catalyst layers and the membrane. Coupled transport and electrochemical kinetics equations are solved in a single domain; therefore no interfacial boundary condition is required at the internal boundaries between cell components.This computational fluid dynamics code is used as the direct problem solver, which is used to simulate the three-dimensional mass, momentum and species transport phenomena as well as the electron- and proton-transfer process taking place in a PEMFC that cannot be investigated experimentally. The results show that the predicted polarization curves by using this model are in good agreement with the experimental results. Also the results show that by increasing the number of connection between GDL and bipolar plate the performance of the fuel cell enhances.     

Investigating the transport characteristics and cell performance for a micro PEMFC through the micro sensors and CFD simulations

The local transport characteristics and the global polarization curve for a self-made micro proton exchange membrane fuel cell (PEMFC) have been experimentally and numerically investigated in this paper. The micro-sensors are developed to measure the local fluid temperature, cell voltage, and current density and the fuel cell test system is used to measure the polarization curve. A three-dimensional (3-D) non-isothermal compressible computational fluid dynamics (CFD) full-cell model is also adopted to simulate the test micro PEMFC. This CFD model has been validated with these global and local data. The ionic conductivity is increased as the water content in the membrane increases, enhancing the cell performance. This positive effect of inlet fuel humidity on the cell performance is also captured by the CFD simulation model.     

Experimentally and numerically investigating cell performance and localized characteristics for a high-temperature proton exchange membrane fuel cell

This paper is to experimentally and numerically investigate the cell performance and the localized characteristics associated with a high-temperature proton exchange membrane fuel cell (PEMFC). Three experiments are carried out in order to study the performance of the PEMFC with different operating conditions and to validate the numerical simulation model. The model proposed herein is a three-dimensional (3-D) computational fluid dynamics (CFD) non-isothermal model that essentially consists of thermal–hydraulic equations and electrochemical model. The performance curves of the PEMFC predicted by the present model agree with the experimental measured data. In addition, both the experiments and the predictions precisely demonstrate the enhanced effects of inlet gas temperature and system pressure on the PEMFC performance. Based on the simulation results, the localized characteristics within a PEMFC can be reasonably captured. These parameters include the fuel gas distribution, liquid water saturation distribution, membrane conductivity distribution, temperature variation, and current density distribution etc. As the PEMFC is operated at the higher current density, the fuel gas would be insufficiently supplied to the catalyst layer, consequently causing the decline in the generation of power density. This phenomenon is so called mass transfer limitation, which can be precisely simulated by the present CFD model.     

Numerical investigation of the performance of symmetric flow distributors as flow channels for PEM fuel cells

This work reports on the performance of a single PEM fuel cell using symmetric flow patterns as gas delivery channels. Three flow patterns, two symmetric and one serpentine, are taken from the literature on cooling of electronics and they are implemented in a computational model as gas flow channels in the anode and cathode side of a PEMFC. A commercial CFD code was used to solve the physics involved in a fuel cell namely: the flow field, the mass conservation, the energy conservation, the species transport, and the electric/ionic fields under the assumptions of steady state and single phase. An important feature of the current modeling efforts is the analysis of the main irreversibilities at different current densities showing the main energy dissipation phenomena in each cell design. Also, the hydraulic performance of the flow patterns was studied by evaluating the pressure drop and pumping power. The first part of this work reveals the advantages of using a serpentine pattern over the base symmetric distributors. The second part is an optimization of the symmetric patterns using the entropy minimization criteria. Such an optimization led to the creation of a flow structure that promotes an improved performance from the point of view of power generation, uniformity of current density, and low pumping power.