Query: proton exchange membrane fuel cell stack assembly

title: An Analytical Model for Contact Pressure Prediction Considering Dimensional Error of Stamped Bipolar Plate and Gas Diffusion Layer in Proton Exchange Membrane Fuel Cell Stack Assembly

title: State of the Art and Development Trends of Assembly Technologies for Proton Exchange Membrane Fuel Cell Stack: A Review

title: A systematic review for structure optimization and clamping load design of large proton exchange membrane fuel cell stack
abstract: Great progress has been made on the research of proton exchange membrane fuel cell (PEMFC) in the past 20 years, especially in the key materials and components such as proton exchange membrane (PEM) catalytic layer (CL) gas diffusion layer (GDL) membrane electrode assembly (MEA) bipolar plate (BPP) endplate (EP) etc. There are a lot of studies on those materials and structures as well as several literature reviews on their chemical and physical properties. However, structure design of PEMFC stack is a key technology as it connects lab based study with large scale industrial applications. There is so far no systematic review on the structure design, manufacture, optimization, clamping theory and technology of large PEMFC stacks. In this article, a systematic review is presented for the progresses made in structure optimization and manufacturing technologies of EPs and BPPs, mechanical properties of structure materials, including PEM, GDL and MEA, optimization design of clamping load, anti vibration and reliability designs of large PEMFC stacks. Finally, discussions, challenges and prospects are made on the materials and structure designs of large PEMFC stacks. It is expected that this review can provide a systematic comprehension and direction for the structure optimization of high performance PEMFC stacks.

title: Performance degradation of 1 kW proton exchange membrane fuel cell stack using graphitized carbon supported Pt nanoparticle catalyst
abstract: Graphitic carbon supported Pt nanoparticles (Pt/GC) are used as high durability catalysts in 1 kW proton exchange membrane fuel cell (PEMFC) stack. Accelerated degradation tests (ADT) with different protocols at the half cell and single cell level show that Pt/GC catalysts exhibited better durability than commercial Pt/C. After 458 h of dynamic drive cycle durability testing, the PEMFC stack exhibits a voltage degradation rate at 1000 mA cm 2 of 5.3% and 85 mV/h. The results show that the majority of degradation was due to the contact angles of the hydrophilicity of the catalyst layer (CL) and the substrate layer (SL) is enhanced, which means the decrease in PEMFC stack durability also comes from the increase in mass transfer resistance and the reduction in the water management capacity of the cell. Partly, another reason is the collapse of the CL, which comes from the uneven assembly force and the structural change of CL. However, the structure and the size of the Pt/GC catalyst and electrochemically active surface area (ECSA) of CL is found hardly changed after 458 h, which indicates excellent stability of the catalyst and MEA under these practical conditions. Herein, this further supports that Pt/GC catalyst makes practical PEMFC applications possible.

title: Assembly design of proton exchange membrane fuel cell stack with stamped metallic bipolar plates
abstract: Fuel cell assembly plays a dominant role in performance and lifetime of proton exchange membrane (PEM) fuel cell. Most current methods for assembly design are based on experiment and finite element (FE) model, which need high cost and huge computation for the whole fuel cell. Unfortunately, there are only few theoretical methods which contribute to the whole stack assembly, especially those in 3D model. This study develops a comprehensive methodology to simulate the stack assembly and to design the clamping displacement/pressure. At first, contact pressure field on the GDL is predicted with the use of the continuous equivalent model. The total contact resistance and porosity of fuel cell are proposed as the evaluation indexes combined by the desirability of function method. Then, in order to validate the contact pressure prediction, experiments with dimensional error metallic bipolar plate are carried out and the numerical results show good agreements with experimental results. At last, clamping pressure of the endplate is calculated to optimize the assembly process. The methodology in this study is beneficial to the understanding of the internal contact behavior of the whole stack and helpful to guide the assembling of PEM fuel cell.

title: Investigation of the assembly for high power proton exchange membrane fuel cell stacks through an efficient equivalent model
abstract: A high power proton exchange membrane fuel cell (PEMFC) stack usually composes many cells, which induce high difficulty in evaluating its mechanical state of stack assembly. A methodology based on composite model and material property equivalent is developed to predict the mechanical state in PEMFC stack. In this methodology, the stack system is modeled based on a finite element model (FEM) in which bipolar plate (BPP) and membrane exchange assembly (MEA) are combined into a composite component. Experiments with stamped BPP are carried out to validate the FEM of the stack, and both the predicted clamping force and endplates deformation of FEM have a great agreement with the experimental results. Based on the methodology, it is found that more uniform pressure distribution can be generated when high stiffness endplates are applied and cell number of the stack increases. The cells approaching to mid stack have more uniform pressure. The pressure distribution of the stack is very sensitive to the compression ratio. High compression ratios leads to large endplate deformation, which increases the average pressure deviation between simulated value and design value, and also increases non uniformity of pressure distribution. This methodology offers the possibility of evaluating the mechanical state of high power fuel cell stack and greatly improves the computational efficiency.

title: Proton Exchange Membrane Fuel Cell Stack Design Optimization Using an Improved Jaya Algorithm
abstract: Fuel cell stack configuration optimization is known to be a problem that, in addition to presenting engineering challenges, is computationally hard. This paper presents an improved computational heuristic for solving the problem. The problem addressed in this paper is one of constrained optimization, where the goal is to seek optimal (or near optimal) values of (i) the number of proton exchange membrane fuel cells (PEMFCs) to be connected in series to form a group, (ii) the number of such groups to be connected in parallel, and (iii) the cell area, such that the PEMFC assembly delivers the rated voltage at the rated power while the cost of building the assembly is as low as possible. Simulation results show that the proposed method outperforms four of the best known methods in the literature. The improvement in performance afforded by the proposed algorithm is validated with statistical tests of significance.

title: Finite Element Analysis for Stress Distribution in a Proton Exchange Membrane Fuel Cell Stack
abstract: The component design of a proton exchange membrane fuel cell (PEMFC) considerably affects pressure distribution in the PEMFC stack by creating uniform and effective pressure distribution. Assembly and component designs are essential in the PEMFC system to achieve optimal performance and durability of the PEMFC stack. Inadequate pressure in the stacking process can damage the cells and cause leakage and contact resistance. Moreover, an uneven distribution of pressure produces hot spots that can damage the system. Achieving the optimal design with reduced production cost requires pressure distribution simulation during the assembly. Finite element analysis (FEA) was used to analyze system behavior with pressure variation during assembly by using Autodesk Inventory software. This study discussed the geometric modeling and FEA of the tensile distribution of the PEMFC stack. The detailed components reported on the geometry, dimensions, and mechanical properties of PEMFC components, such as membranes, gas diffusion layers, end plates, and bipolar plates. Results from the simulations showed no significant difference in the deformation of cells in the PEMFC stack, with changes in tensile distribution.

title: Impact of dummy load shut down strategy on performance and durability of proton exchange membrane fuel cell stack
abstract: In this paper, the performance and durability of a self designed proton exchange membrane fuel cell (PEMFC) stack with 5 single cells are investigated with in situ segmented cell technology. Effect of dummy load application during shut down process on performance degradation is analyzed through measuring polarization curves and electrochemical impedance spectroscopy (EIS) after different start up and shut down (SU/SD) cycles. Scanning electron microscope (SEM) images of membrane electrode assembly (MEA) are taken after the SU/SD cycles. According to the analysis results, it is confirmed that dummy load can take benefit to the durability of PEMFC during the SU/SD process and also the uniformity of current density in different regions for each single cell. However, dummy load may not affect the uniformity of single cells for the stack. This paper contributes to the strategies for promoting performance and durability of PEMFC stack.

title: Do not forget the electrochemical characteristics of the membrane electrode assembly when designing a Proton Exchange Membrane Fuel Cell stack
abstract: The membrane electrode assembly (MEA) is the key component of a PEMFC stack. Conventional MEAs are composed of catalyzed electrodes loaded with 0.1 0.4 mg Pt cm 2 pressed against a Nafion (r) membrane, leading to cell performance close to 0.8 W cm 2 at 0.6 V. Due to their limited stability at high temperatures, the cost of platinum catalysts and that of proton exchange membranes, the recycling problems and material availability, the MEA components do not match the requirements for large scale development of PEMCFs at a low cost, particularly for automotive applications. Novel approaches to medium and high temperature membranes are described in this work, and a composite polybenzimidazole poly(vinylphosphonic) acid membrane, stable up to 190 deg C, led to a power density of 0.5 W cm 2 at 160 degC under 3 bar abs with hydrogen and air. Concerning the preparation of efficient electrocatalysts supported on a Vulcan XC72 carbon powder, the Bonnemann colloidal method and above all plasma sputtering allowed preparing bimetallic platinum based electrocatalysts with a low Pt loading. In the case of plasma deposition of Pt nanoclusters, Pt loadings as low as 10 mg cm 2 were achieved, leading to a very high mass power density of ca. 20 kW g 1 Pt Finally characterization of the MEA electrical properties by Electrochemical Impedance Spectroscopy (EIS) based on a theoretical model of mass and charge transport inside the active and gas diffusion layers, together with the optimization of the operating parameters (cell temperature, humidity, flow rate and pressure) allowed obtaining electrical performance greater than 1.2 W cm 2 using an homemade MEA with a rather low Pt loading.