Flow Field Plate Research Articles

Development of flow field plates based on asymmetric leaf structure for PEM fuel cells

Bipolar plates are the key parts of a polymer electrolyte membrane (PEM) fuel cell, which allow the reaction gas to be more evenly distributed over the electrode surface, so that the fuel cell can achieve the best performance. In this paper, a novel asymmetric flow channel is used to design the bipolar plate of PEM fuel cells. It is demonstrated by numerical simulation that the structure of the asymmetrical bionic flow field plate, shows pressure loss from the inlet to outlet less than the pressure loss of the conventional flow field. In the design of asymmetrical bionic flow channel structure, it can scatter gas into each bifurcation channel uniformly, improving the efficiency of gas reaction and pushing the water generated during the reaction from each branch to the outlet, which may be conducive to prevent water flooding of the fuel cell.

Development of flow field plates based on asymmetric leaf structure for PEM fuel cells

Development of flow field plates based on asymmetric leaf structure for PEM fuel cells

Flow field bipolar plates in a proton exchange membrane fuel cell: Analysis & modeling

This study investigates flow fields and flow field plates (bipolar plates) in proton exchange membrane fuel cells. In this regard, the main design considerations and limitations for a flow field network have been examined, along with a comprehensive review of currently available flow field channel configurations. Also, the common materials and material properties used for flow field plates have been explored. Furthermore, a case study of step-by-step modeling for an optimum flow field design has been presented in-details. Finally, a parametric study has been conducted with respect to many design and performance parameters in a flow field plate.

Micro direct methanol fuel cell: functional components, supplies management, packaging technology and application

This review reports the progress on the recent development of micro direct methanol fuel cell. Various functional components including micro flow field plate, membrane electrode assembly, proton exchange membrane, catalytic layer, diffusion layer, and collector are narrated and discussed. The supplies management and packaging technology are also illustrated and discussed. A variety of portable devices whose power is supplied by micro direct methanol fuel cell are analyzed and discussed. This paper will provide an expedient and valuable reference to those who intend to research micro direct methanol fuel cell. Copyright © 2016 John Wiley & Sons, Ltd.

Influence of Binder Porosity on Gdl Gas Phase Transport

In polymer electrolyte fuels (PEFC) carbon fiber based gas diffusion layers (GDL) are used for fine distribution of reactant gases from the flow field channels to the catalyst layer (CL). It is a key component for PEFC as it serves also for water removal from the CL as well as heat and electricity transport between CL and the flow field plates. GDL materials can be classified as woven, felts, papers, where the later type requires a binder to mechanically stabilize the fiber arrangement. While most GDL binders are solid, the binder of SGL GDLs appears porous and it’s influence on gas phase transport is unclear [1]. In SEM surface images of SGL, GDL binder domains of appear as flake like fine-structure with particles of about 100 to 300 nm (see Fig. 1a). Here, we apply multi-dimensional X-ray imaging techniques and multi-scale numerical simulations to clarify possible contributions of the binder porosity to overall GDL gas transport. Absorption contrast X-ray tomographic microscopy measurements at the TOMCAT beamline of the Swiss Light Source (SLS) with voxel sizes of minimum 0.16 µm revealed a high porosity (59 %) of SGL 24 BA binder domains of (Fig. 1b). Computational transport simulations on the segmented binder structures showed, that the binder domains provide isotropic effective diffusivity of 0.30. In order to quantify the contribution of the porous binder to the overall fluid transport in the GDL, the obtained binder diffusivity values were used in multi-scale transport simulations of ternary segmented XTM data of representative GDL samples with 2.2 µm voxel size. If the binder was treated as solid, through-plane effective diffusivity of the GDL of 0.1 was obtained. If we applied a multi-scale simulation approach, that treats the binder domain as porous and uses the transport parameters of the binder domain as input values for the coarse scale simulations of the whole GDL domain, the through-plane effective diffusivity increased to 0.4 (+300 %). These numbers will be verified by X-ray ptychograptic computed tomography measurements of the binder fine structure at the cSAXS beamline of the SLS that proved resolutions of up to 16 nm [2].

Extending the Life-Time of Low Cost Fuel Cells

Extending the bipolar plate lifetime of low-cost fuel cell. Energy conversion sources that offer lower carbon emissions, increased efficiency and reduced environmental impact at a competitive cost are a key requirement for future low carbon transport and stationary power generation applications.Fuel cells are promising candidates but widespread uptake has so far been hindered by the high cost of materials and manufacturing in addition to limited durability under realistic operating conditions. There is a clear need for a lower cost approach but without sacrificing performance or durability. Bipolar plates are responsible for collecting current, supplying the fuel to the MEA as well as exhausting water produced at the cathode side1. Metallic bipolar plates must be resilient, non-porous, conductive with a low contact resistance and obviously cheap for mass market penetration2. The US Department of Energy (DoE) has introduced target cost plans for 2020 on different PEM fuel cell components, including bipolar plates3. The technical plan states that the corrosion rate must be below 1 µA.cm-2 and that an interfacial contact resistance must be below 10 mΩ.cm2 at a compaction pressure of 140 N.cm-2. These condition has to be attained with a cost below 3 $kW-1. Bipolar plates account for 45-60 % of the stack cost, 80 % of the weight, and almost all the volume of the PEM fuel cell stack. The flexiplanar approach uses a metallic substrate mounted on a printed circuit board (PCB) in order to produce a low cost cell. Copper is a strong candidate for this purpose: it is robust, has a high conductivity and a low contact resistance as well as a possibility of scalable hydroforming or stamping4, which is an important feature in order to produce a flow field plate. However, due to the harsh conditions within the fuel cell stack such as a high potential and temperature, the copper interface must be protected by a coating. Coatings applied on the flow field plate must have a good electrical conductivity, a low contact resistance and also have to be resilient to fuel cell operating conditions i.e. 120 °C and 1.2 V. In recent years, there has been an increasing amount of literature on carbon polymer blend used as metallic substrate protector19 , 20 , 21. Carbon-polymer mixtures are commercially available at reasonably affordable prices. Nevertheless, they are also likely to be corroded due to carbon micro-particles dispersed in the polymer. Hence further investigation needs to be done in this poorly understood area. 1 Polymer Fuel Cells - Cost reduction and market potential, C. Trust, 2012. 2 C. Spiegel, Designing and Building Fuel Cells, 2007. 3 T. Plan and F. Cells, 2015, 1–49. 4 ASM International, Copper and Copper Alloys, ASM International, 2001. 5 W. L. Wang, S. M. He and C. H. Lan, Electrochim. Acta, 2012, 62, 30–35. 6 Y. Show and K. Takahashi, J. Power Sources, 2009, 190, 322–325. 7 Y. B. Lee and D. S. Lim, Curr. Appl. Phys., 2010, 10, S18–S21.

Optimally catalyzed porous-silicon electrode of self-breathing micro fuel cells

Pt nanoparticles (Pt-NPs) are deposited on porous-silicon surface by electrochemical reduction to form self-breathing electrode of micro proton-exchange-membrane fuel cells (μPEMFCs). The Pt-NPs modified porous-silicon self-breathing windows are integrated in the cathode flow-field plate to replace traditional carbon paper for enhancement air diffusion. The test results show that the peak current increases with increasing the loaded Pt-NPs and the maximum peak current is obtained at the Pt-NPs loading of 0.38 mg/cm2. Attributed to the high surface-area of the porous-silicon electrode, the Pt electro-catalytic performance is significantly enhanced compared to that by using the conventional carbon paper electrode where Pt/C was brushed with the similar Pt loading of 0.4 mg/cm2. Therefore, the μPEMFCs with the porous-silicon electrode show higher electric energy generation. Moreover, experiments show that the peak power-density of the fuel cell with 350 nm pore-sized porous-silicon electrode is 30 % higher than that with 5 μm-sized porous silicon.

In situ investigation of proton exchange membrane fuel cell performance with novel segmented cell design and a two-phase flow model

A novel segmented fuel cell device based on the multi-layered printed circuit board (PCB) flow field plates is designed to study the localized fuel cell performance with various operation conditions. With embedded sensors, distributions of current density, relative humidity (RH) and temperature for both anode and cathode are measured simultaneously along the direction of straight parallel flow channels. Meanwhile, a stationary two-phase flow fuel cell model is developed to study the internal reaction parameter distributions and the results are compared with the in situ experimental measurements. In the co-flow operation mode of hydrogen and air, current density and reactants' RH distributions are sensitive to the stoichiometry of air but the effect from hydrogen is minor. Water transfer behavior, local reactants' RH status, temperature gradients and their impacts on current distributions are analyzed based on the in situ measurements and the coupled model analysis. The segmented cell device discussed in this paper, as well as the experimental and modeling results can be employed to optimize stack design and operating parameters with “visible” internal distributions of water, RH and temperature inside membrane electrode assembly (MEA). Further investigation on fuel cell performance and lifetime with different reactant flow directions is also suggested.

Comparison of perforated and serpentine flow fields on the performance of proton exchange membrane fuel cell

Flow channel design is a significant criterion that affects the performance and water transport characteristics of Proton Exchange Membrane Fuel Cell (PEMFC). In this study, a perforated flow field is designed and fabricated to improve the performance of PEMFC in comparison with conventional serpentine flow field. This perforated flow field plate is designed in such a way that it consists of numerous holes of 2 mm diameter in a regular pattern on the entire active area of 25 cm2. The effect of perforated flow field on the cell performance at various relative pressures of reactants are evaluated and compared with the conventional single pass serpentine flow field. The experimental results show that perforated flow field delivered a peak power density of 242 mW/cm2 whereas with serpentine flow field a maximum power density of 230 mW/cm2 is achieved. On comparison with serpentine flow field, the perforated flow field showed an increase in power density of about 5.8%, 6.5% and 5.2% at relative pressures of 0, 0.5 and 1 bar respectively. Further, the cell impedance test reveals that the cell with perforated flow field plates shows least impedance. The conductance of the flow field plates have been calculated and found to be almost equal for both perforated and serpentine channel geometry.

Active multi-scale modeling and gas permeability study of porous metal fiber sintered felt for proton exchange membrane fuel cells

Porous metal fiber sintered felt (PMFSF) is a promising critical component in proton exchange membrane fuel cells, having the ability of simultaneously acting as the flow field plate, gas diffusion layers and also the catalyst layers support, and owing the property of multi-scale surface morphology. A simple multi-scale mathematical method was proposed to actively construct three dimensional models of PMFSF’s microstructure by synthesizing the implicit periodic surface (PS) model and the Weierstrass-Mandelbrot (W-M) fractal geometry. In this method, the PS model described the macro overall fiber shape, and the W-M fractal geometry modeled the micro fractal roughness topography attached. Based on the method, multi-scale fractal PMFSF models were reconstructed according to morphology parameters of physical PMFSFs, and were discretized in ANSYS/ICEM to generate refined mesh for computational fluid dynamics analysis. To verify the validity of the proposed modeling approach, PMFSFs with different porosity and fiber orientation are generated, and then the effects of the fractal surface topography and the fractal parameters such as fractal dimension and height scaling parameter on the gas permeability of PMFSF were investigated. The numeric simulation results show that the influence of the fractal topography on the in-plane and through-plane permeability of PMFSF cannot be ignored, and the permeability of fractal PMFSF models agrees with experimental measurements better. Especially, the results imply that the fractal morphology may have the potential to adjust the anisotropic properties of PMFSFs’ permeability. It is further found that the larger the fractal dimension is and the lower the height scaling parameter is, the better the permeability of PMFSF will be. The synthesis approach and numerical simulation method may facilitate the development of active functional design mode to predict and optimize key characteristics of PMFSF ahead of manufacture.

Stagnation electrical MHD nanofluid mixed convection with slip boundary on a stretching sheet

In this study, the stagnation nano energy conversion problems have been completed for conjugate mixed convection heat and mass transfer with electrical magneto hydrodynamic (EMHD) and heat source/sink effects nanofluid flow field over a slip boundary stretching sheet surface. The physical phenomena varied which depended on different factors. All of the important nano energy conversion parameters S0, M, E, Gt, Gc, λ, Pr, Sc, Ncc, S and δ have represented the dominance of the magnetic energy effect, electric effect, mixed convection effect, heat generation/absorption energy effect, heat transfer effect, mass diffusion effect, heat conduction–convection effect and slip boundary effects, respectively. The similarity transformation and a modified Finite-Difference method are used to analyze the present nano energy conversion system's thermal energy conversion problem. The non-linear ordinary equations of the corresponding flow field momentum, temperature, concentration equations and plate sheet heat conduction equation are derived by employing the similarity transformation technology. The dimensionless non-linear ordinary equations are composed of momentum, temperature, concentration and plate sheet heat conduction equations which have been solved numerically by an improved finite difference technique.

Use of Computational Fluid Dynamic to Compare the Pressure Loss between a Parallel Flow Field Plate with a Parallel-baffle Flow Field Plate and a Fractal Parallel-baffle Flow Field Plate in a Proton Exchange Membrane Fuel Cell

This research provided CFD tests to verify and understand the reagents fluid dynamic behavior in the channels of the new parallel-baffle flow field plate during a direct ethanol proton exchange membrane fuel cell (DE-PEMFC) operation. The results showed that. The results showed that the fractal plate showed a similar behavior normal plate and a repetition through fractals, the fluid dynamic behavior.

Rapid prototyping of electrolyzer flow field plates

Electroplated 3D printed flow field plates are demonstrated for the electrolysis of water to hydrogen fuels.

Influence of porous carbon inserts on scaling up studies for performance enhancement on PEMFC

In order to reduce the effect of water flooding on larger active area of Proton Exchange Membrane Fuel cell (PEMFC), an enhanced flow distribution on the flow channel is mandatory. In this paper to mitigate the water flooding problem, experimental studies have been carried out on 25 cm2 and 70 cm2 active area of PEMFCs with various flow channel designs on the cathode flow plate namely serpentine, uniform and zigzag pin type; and flow channel with 2 mm cubical porous inserts on the uniform and zigzag pin types. The results show that the cathode flow field plate with zigzag positioned porous carbon inserts having 80–90% porosity has improved the current and power densities by 7% and 11.5% respectively, when compared to the conventional serpentine flow field plate for 25 cm2 PEMFC. The above procedure has been followed for scaling up studies from 25 cm2 to 70 cm2 PEMFCs for effective water management. It is concluded that the 70 cm2 PEMFC with zigzag positioned porous carbon inserts on the cathode flow field has increased the current and power densities by 8.7% and 20.6% respectively compared to the conventional serpentine flow field. The porous carbon inserts on the rib surface of the cathode flow field removes the accumulated liquid water from the rib surface through the capillarity of its porous structure, due to this the performance of PEMFC is enhanced in scaling-up studies with better water transport characteristics.

Research on the performance differences between a standard PEMFC single cell and transparent PEMFC single cells using optimized transparent flow field unit–Part II: Performance comparison and explanation

Three transparent single cells, i.e., a cathode transparent single cell, an anode transparent single cell and an overall transparent single cell are tested and compared with a standard single cell. Results show the standard single cell presents the best performance and the overall transparent single cell shows the worst performance. This is because a large contact resistance exists between the gas diffusion layer and the graphite pierced flow field plate of a transparent single cell due to the deformation of the transparent flow field unit, which is caused by the bolt preload. Based on the testing data, four deformation process models are proposed to reveal how the structure differences affect the performance differences between the standard single cell and the transparent single cells.

振動平板流れ場におけるヒト赤血球の移動と変形挙動のモデリングに関する検討

振動平板流れ場におけるヒト赤血球の移動と変形挙動のモデリングに関する検討

Design and simulation of novel flow field plate geometry for proton exchange membrane fuel cells

Bipolar plate is one of the many important components of proton exchange membrane fuel cell (PEMFC) stacks as it supplies fuel and oxidant to the membrane-electrode assembly (MEA), removes water, collects produced current and provides mechanical support for the single cells in the stack. The flow field design of a bipolar plate greatly affects the performance of a PEMFC. It must uniformly distribute the reactant gases over the MEA and prevent product water flooding. This paper aims at improving the fuel cell performance by optimizing flow field designs and flow channel configurations. To achieve this, a novel biomimetic flow channel for flow field designs is proposed based on Murray’s Law. Computational fluid dynamics based simulations were performed to compare three different designs (parallel, serpentine and biomimetic channel, respectively) in terms of current density distribution, power density distribution, pressure distribution, temperature distribution, and hydrogen mass fraction distribution. It was found that flow field designs with biomimetic flow channel perform better than that with convectional flow channel under the same operating conditions.

In Situ Localized Current Distribution Measurements in All-Vanadium Redox Flow Batteries

A printed circuit board (PCB) was implemented for in-plane, two-dimensional distributed current measurements in an all-vanadium redox flow battery (VRFB). A PCB with built-in shunt resistors is a passive method of measuring localized currents in-situ, in real time. It is demonstrated that lateral current spread through non- or partially-segmented flow field plates will produce a distribution that does not properly reflect the distribution within the electrode; this issue is resolved in this work via fully-segmented flow plates. Large current gradients develop when a cell reaches a mass-transport limitation. Based upon the resultant distributions, it is shown that they reflect a combination of electrolyte velocity and local concentration within the electrode. The impact of flow rate and electrode material properties such as wettability, surface area, porosity, and thickness on current distribution are presented.

Effects of the Geometry of the Air Flowfield on the Performance of an Open-Cathode PEMFC – Transient Load Operation

The single-cell open-cathode PEMFC was fabricated with 100-cm2 activation area to study the influence of the geometry of the air flowfield on the performance. Six cathode flowfield plates with different channel configurations were tested and compared under limited amount of air supplied. The transient load is applied with sinusoidal variations representative of the automotive load profile. The results were compared in the form of the hysteresis loop on the polarization curve. The effect of mass transfer loss was found at the high current density region. The flowfield with high aspect ratio gave a better performance. On the other hand, the flow area played no significant effect on the performance.

Ultrasonic radiation to enable improvement of direct methanol fuel cell

To improve DMFC (direct methanol fuel cell) performance, a new method using ultrasonic radiation is proposed and a novel DMFC structure is designed and fabricated in the present paper. Three ultrasonic transducers (piezoelectric transducer, PZT) are integrated in the flow field plate to form the ultrasonic field in the liquid fuel. Ultrasonic frequency, acoustic power, and methanol concentration have been considered as variables in the experiments. With the help of ultrasonic radiation, the maximum output power and limiting current of cell can be independently increased by 30.73% and 40.54%, respectively. The best performance of DMFC is obtained at the condition of ultrasonic radiation (30kHz and 4W) fed with 2M methanol solution, because both its limiting current and output power reach their maximum value simultaneously (222mA and 33.6mW, respectively) under this condition. These results conclude that ultrasonic can be an alternative choice for improving the cell performance, and can facilitate a guideline for the optimization of DMFC.