Three-dimensional Fuel Cell Model Research Articles

Study on anode single-phase flow pressure drop law of proton exchange membrane fuel cell

This article briefly describes the research status of water flooding and pressure drop (PD) of the fuel cell. Then, a mathematical model of the single-phase flow PD of the fuel cell anode is established using hydrodynamics theory and referring to existing research. Then, the three-dimensional fuel cell model is established with Gambit software, and the grid is divided. Then, the numerical simulation of the single-phase flow of the fuel cell is carried out with Fluent software. Through the analysis of the simulation data, the relationship between the fuel cell anode pressure drops and some main influencing factors under steady-state conditions is explored, and the fuel cell anode’s single-phase flow pressure drop model is preliminarily verified. Anodes are highly sensitive to water flooding. The study of the single-phase flow PD law has a good contrast effect on the abnormal pressure drop during water flooding of fuel cells, which can be used to diagnose water flooding.

EFFECT OF NON-UNIFORMLY DISTRIBUTED POROSITY OF GAS DIFFUSION LAYERS ON MASS TRANSFER IN PROTON EXCHANGE MEMBRANE FUEL CELLS

Gas diffusion layer porosity can affect mass and charge transfer inside proton exchange membrane fuel cells and influence cell performance. Moreover, the electrochemical reaction rate distribution in various regions inside the cell is not uniform. Proper porosity distribution is very important to improve cell performance. In this paper, a three-dimensional fuel cell model with three steps porosity along the gas flow direction is established. Four cases of non-uniformly distributed porosity, both in anode and cathode gas diffusion layers are simulated, which are compared with uniform porosity distribution to study the effect of these structures on mass transfer inside the cell. Then, an optimization calculation is carried out to obtain the optimal porosity distribution along gas flow direction at 0.2 V and 0.6 V. The numerical results indicate that non-uniformly distributed porosity can change cell performance, and porosity increasing along the gas flow direction makes cell performance be better. Porosity increasing along the gas flow direction can improve the uniformity of current density distribution at low voltage. Diffusive mass flux plays a dominant role in reactant mass transfer. Higher porosity near the outlet region increases total mass flux at the interface, and the proportion of diffusion mass flux in total mass flux also increases.

Numerical analysis of the influence of flow direction on heat distribution performance of a PEM fuel cell with serpentine flow field deign

The distribution of reactive species in the proton exchange membrane fuel cell (PEMFC) influences the overall performance of the fuel cell in terms of current density, temperature, and water distribution. The flow field configuration and flow direction of the reacting gas influence’s the distribution and reaction rates of the fuel and oxidant. In this work, the serpentine flow field is numerically investigated to determine the influence of the flow direction of reactant gas on the distribution of reactant gas and heat transfer within the fuel cell. The three-dimensional fuel cell model is used to analyze the effect of the flow direction on the fuel cell performance. The temperature distribution is improved for the counter flow. The current density is increased for the counter flow compared to the co-flow. The current density is increased at the lower values of the terminal voltage which could be due to the oxygen molar concentration at the cathode end.

Prediction of Deformation and Hygro-Thermal Stresses Distribution in Ambient Air-Breathing PEM Fuel Cells using Three-Dimensional CFD Model

The need for improved lifetime of air-breathing proton exchange membrane (PEM) fuel cells for portable applications necessitates that the failure mechanisms be clearly understood and life prediction models be developed, so that new designs can be introduced to improve long-term performance. A three-dimensional, multi-phase, non-isothermal computational fluid dynamics (CFD) model of an ambient air-breathing proton exchange membrane fuel cell has been developed and used to investigate the displacement, deformation, and stresses inside the whole cell, which developed during the cell operation due to the changes of temperature and relative humidity. The behaviour of the fuel cell during operation has been studied and investigated under real cell operating conditions. A unique feature of the present model is to incorporate the effect of mechanical, hygro and thermal stresses into actual three-dimensional fuel cell model. The results show that the non-uniform distribution of stresses, caused by the temperature gradient in the cell, induces localized bending stresses, which can contribute to delaminating between the membrane and the gas diffusion layers. The nonuniform distribution of stresses can also contribute to delaminating between the gas diffusion layers and the current collectors, especially in the cathode side. These stresses may explain the occurrence of cracks and pinholes in the fuel cells components under steady-state loading during regular cell operation, especially in the high loading conditions. The paper ends with some recent patents and developments in the field.

A CFD study of hygro–thermal stresses distribution in PEM fuel cell during regular cell operation

A three-dimensional, multi-phase, non-isothermal computational fluid dynamics model of a proton exchange membrane fuel cell has been developed and used to investigate the displacement, deformation, and stresses inside the whole cell, which developed during the cell operation due to the changes of temperature and relative humidity. The behaviour of the fuel cell during operation has been studied and investigated under real cell operating conditions. A unique feature of the present model is to incorporate the effect of hygro and thermal stresses into actual three-dimensional fuel cell model for a complete cell with both the membrane-electrode-assembly and the gas distribution flow channels. The results show that the non-uniform distribution of stresses, caused by the temperature gradient in the cell, induces localized bending stresses, which can contribute to delaminating between the membrane and the gas diffusion layers. The non-uniform distribution of stresses can also contribute to delaminating between the gas diffusion layers and the channels, especially in the cathode side. These stresses may explain the occurrence of cracks and pinholes in the fuel cells components under steady-state loading during regular cell operation, especially in the high loading conditions.

Effects of the electrical resistances of the GDL in a PEM fuel cell

In most PEM fuel cell models, the electrical resistance of the gas diffusion layers (GDL) is neglected under the assumptions that the GDL electrical conductivity is orders of magnitude higher than the ionic conductivity of the membrane. Recently some modeling efforts have taken the effects of electrical resistance of the GDL into consideration [H. Meng, C.Y. Wang, Electron transport in PEFCs, J. Electrochem. Soc. 151 (2004) A358–A367; B.R. Sivertsen, N. Djilali, CFD-based modeling of proton exchange membrane fuel cells, J. Power Sources 141 (2005) 65–78] and some of the results showed that under certain conditions, this effect was significant enough to alter the characteristics of current density distributions under the gas channels and the land areas. If these results are applicable to real-life fuel cells, the present design criteria and optimization procedures must be significantly changed to incorporate the effect of GDL electrical resistance. To examine this issue closely, a three-dimensional fuel cell model incorporating electron transport in the GDL is developed and employed to investigate the effect of electrical resistance through the GDL. In this model, the anisotropic nature of the GDL is taken into consideration by using different electrical conductivities in the through-plane and in-plane directions. The modeling results show that when realistic electrical conductivities for the GDL are used, the effect of the electrical resistance of GDL is slight and can be neglected for all industrial applications. It is believed that the over-estimations of the GDL resistance were mainly caused by neglecting the anisotropic nature of the GDL and/or lumping the contact resistance indiscriminately into the GDL, thus overestimating the electrical resistance of the GDL in the in-plane direction. Besides taking into consideration of the electrical resistance of GDL, the present model also take into consideration of the electron transport in the catalyst layers. When realistic values of electrical conductivities are used for both the GDL and catalyst layers, there is no significant change in the characteristics of current density distribution across the land and channel.

Numerical investigation of transport component design effect on a proton exchange membrane fuel cell

A numerical investigation of the transport phenomena and performance of a proton exchange membrane fuel cell (PEMFC) with various design parameters of the transport component is presented. A three-dimensional fuel cell model, incorporating conservations of species, momentum, as well as current transport, is used. The Bulter–Volmer equation that describes the electrochemical reaction in the catalyst layer is introduced; the activation overpotential connects the solid phase potential field to that of the electrolyte phase. Through cell performance simulation with various channel aspect ratios and gas diffusion layer (GDL) thicknesses, a slender channel is found suitable for cells operating at moderate reaction rate, and a flat channel produces more current at low cell voltage. Plots of transverse oxygen concentration and phase potential variation indicate that these oppositely affect the local current density pattern. The relative strengths of these two factors depend on the transport component position and geometry, as well as on the cell operating conditions. Consequently, the curves of cell output current density demonstrate that the optimal GDL thickness increases as the cell voltage decreases. However, at the lowest considered cell voltage of 0.14 V, optimal thickness decreases as that of a thick GDL. The oxygen deficiency caused by long traveling length and clogging effect of liquid water reverses this relationship.

A parametric study of PEM fuel cell performances

The effects of different operating parameters on the performance of proton exchange membrane (PEM) fuel cell have been studied experimentally using pure hydrogen on the anode side and air on the cathode side. Experiments with different fuel cell operating temperatures, different cathode and anode humidification temperatures, different operating pressures, and various combinations of these parameters have been carried out. The experimental results are presented in the form of polarization curves, which show the effects of the various operating parameters on the performance of the PEM fuel cell. The possible mechanisms of the parameter effects and their interrelationships are discussed. In addition, a comprehensive three-dimensional fuel cell model is briefly presented and the modeling results are compared with our experimental data. The comparison shows good agreements between the modeling results and the experimental data.