Abstract The energy world is changing rapidly pushed also by the need for new green energy sources to reduce greenhouse gas emissions. The fast development of renewable energies has created many problems associated with grid management and stability, which could be solved with storage systems. The hydrogen economy could be an answer to the need of storage systems and clean fuel for transportation. The Electrochemical Hydrogen Compressor (EHC) is an electrochemical device, which could find a place in this scenario giving a solution for the hydrogen purification and compression for storage. This work analyzes, through experimental and modeling studies, the performance of the EHC in terms of polarization curve, Hydrogen Recovery Factor (HRF) and outlet hydrogen purity. The influence of many input parameters, such as the total inlet flow rate, the hydrogen inlet concentration, the contaminant in the feed, and the cathode pressure have been investigated. Furthermore, the EHC performance have been modelled in a 1D + 1D model implemented in Matlab® solving the Butler-Volmer system of equations numerically. The experimental campaign has shown that high purities can be obtained for the hydrogen separation from N2 and CH4 and purities over 98% feeding He. An increase in the cathode pressure has shown a slight improvement in the obtained purity. A comparison between PSA unit and EHC for a mixture 75% H2 – 25% CH4 at different outlet hydrogen pressure and purity was performed to analyze the energy consumption required. Results show PSA unit is convenient at large scale and high H2 concentration, while for low concentration is extremely energy intense. The EHC proved to be worthwhile at small scale and higher outlet hydrogen pressure.

Experimental and modeling study of an electrochemical hydrogen compressor

In this study, the poisoning effects of cerium oxide (CeO2) as the contaminant on the performance of proton exchange membrane fuel cells (PEMFCs) are evaluated. An experimental setup was developed to analyze the performance characteristic (I-V) curves in contaminated and non-contaminated conditions. Focused ion-beam scanning electron microscopy (FIB-SEM) cross-section images were obtained as an input for the energy dispersive X-ray (EDX) analysis. The results of the EDX analysis verified the presence of CeO2 in the contaminated membrane electrode assembly (MEA), in addition to fluorine and sulfur. EDX analysis also revealed that as a result of CeO2 contamination, sulfur and fluorine would be distributed all around the MEA, instead of being only in the membrane. The results illustrate that hydrofluoric acid (HF), sulfuric acid (H2SO4), and fluorinated polymer fragments are released, which enhance the crossover of the reactant gases through the membrane, hence reducing the cell’s performance. The I-V characteristic curves proved that the non-contaminated PEMFC setup had double the performance of the contaminated PEMFC.

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Poisoning Effects of Cerium Oxide (CeO2) on the Performance of Proton Exchange Membrane Fuel Cells (PEMFCs)

Fuel cells, designed for mobile applications, should feature compact and low-weight designs. This study describes a design process that fulfills the specific needs of target applications and the production process. The key challenge for this type of metallic bipolar plate is that the combination of two plates creates three flow fields, namely an anode side, a cathode side, and a coolant. This illustrates the fact that each cell constitutes an electrochemical converter with an integrated heat exchanger. The final arrangement is comprised of plates with parallel and separate serpentine channel configurations. The anode and cathode sides are optimized for operation under dry conditions. The final plate offers an almost perfect distribution of coolant flow over the active area. The high quality of this distribution is almost independent of the coolant mass flow, even if one of the six inlet channels is blocked. The software employed (OpenFOAM and SALOME) is freely available and can be used with templates.

Design and Modeling of Metallic Bipolar Plates for a Fuel Cell Range Extender

A Simple Electrochemical Cell Model

Low-Temperature Polymer Electrolyte Fuel Cells

Metallic flow field plates, also called bipolar plates, are an important component of fuel cell stacks, electrolyzers, hydrogen purification and compression stacks. The manufacturing of these plates by means of stamping or hydroforming is highly suitable for mass production. In this work, a toolbox is created that is suitable for a screening process of different flow field design variants. For this purpose, the geometry and computational mesh are generated in an automated manner. Basic building blocks are combined using the open source software SALOME, and these allow for the construction of a large variant of serpentine-like flow field structures. These geometric variants are evaluated through computational fluid dynamics (CFD) simulations with the open source software OpenFOAM. The overall procedure allows for the screening of more than 100 variants within one week using a standard desktop computer. The performance of the flow fields is evaluated on the basis of two parameters: the overall pressure difference across the plate and the relative difference of the hydrogen concentration at the outlet of the channels. The results of such a screening first provide information about optimum channel geometry and the best choice of the general flow field layout. Such results are important at the beginning of the design process, as the channel geometry has an influence on the selection of the metal for deep drawing or hydroforming processes.

https://www.mdpi.com/2305-7084/3/4/85/pdf

Leonard F. J. M. Raymakers

Papers

An Engineering Toolbox for the Evaluation of Metallic Flow Field Plates