Experimental investigation on two-phase flow in a unitized regenerative fuel cell during mode switching from water electrolyzer to fuel cell

Summary Electrochemical water splitting is one of the practical systems for green hydrogen production. This hydrogen processing is sustainable by the use of a water electrolysis cell known as an electrolyzer. In recent decades, the alkaline electrolyzer and the proton exchange membrane electrolyzer have entered the advanced commercial level for the hydrogen processing industry. Unfortunately, both techniques have many crucial issues, such as the handling of hydrogen, large structure, and expensive materials needed during the construction of the cell. Anion exchange membrane (AEM) electrolyzers have been recommended to address the worst of previous electrolyzer types due to the ability to use non‐platinum and non‐Nafion membrane materials, high hydrogen storage density, and the ability to build compact micro‐cells on a large cell scale. A solid polymer alkaline membrane is a key component that influences the efficiency of the AEM electrolyzer, which reacts as an anion exchange membrane (AEM membrane). AEM membrane serves as an anode and cathode separator, ion transfer pathway, and electron flow barriers. This review paper explores polymeric materials and the characterization of an alkaline solid polymeric membrane used in an AEM electrolyzer. Several polymeric membranes that have been investigated by researchers for this application have been discussed. Critical characterizations such as ion exchange capability, ionic conductivity, chemical and mechanical stability, and cell performance durability are comprehensively addressed to guide future research and development in an alkaline solid polymeric membrane for application in an AEM electrolyzer. Highlights An overview of materials and characterization assessment of alkaline solid polymeric membrane in AEM electrolyzer is discussed. The progress of polymeric materials for alkaline solid polymeric membrane modification in the AEM electrolyzer is presented. Critical characterization of the alkaline solid polymeric membrane is described, including the ion exchange capacity, ionic conductivity, chemical and mechanical stability, and durability of cell performance.

Section: Introductionmentioning

confidence: 99%

A review of alkaline solid polymer membrane in the application of AEM electrolyzer: Materials and characterization

Zakaria

Kamarudin

2021

“…On the aspect of experimental research, optical visualization, X‐ray radiography, MRI (magnetic resonance imaging), and neutron imaging are widely used methods 9 . Guo et al 10 utilized optical visualization to investigate the two‐phase flow in a unitized regenerative fuel cell. Dunbar and Masel 11 measured the water distribution in the flow field using MRI and found that the flow pattern in the flow field seems to be wavy‐stratified flow.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of water dynamics in a novel wettability gradient anode flow channel for proton exchange membrane fuel cells

Zhang

Yang

et al. 2020

The effective removal and transport of water in flow channels play an important role in the water management of proton exchange membrane fuel cells (PEMFCs). In this paper, a novel design of anode serpentine flow channel with the wettability gradient wall is discussed and numerically investigated by utilizing the volume-of-fluid (VOF) method. The effects of the contact angle and the wettability gradient of channel walls, as well as hydrogen flow velocity and water droplet size, on the droplet dynamic behavior are studied. The results indicate that compared with the conventional flow channel, the water droplet can be more effectively removed from the turning part in the wettability gradient flow channel. And the water removal ability in the turning part is improved with the increase of the wettability gradient. Moreover, the wettability gradient flow channel can also improve the water removal performance for the cases with different hydrogen flow velocities and water droplet sizes. This study provides ideas for guiding the design of flow channel to effectively enhance anode water management.

“…The distribution of gas-liquid two-phase flow in URFC is important in cell performance. Excessive liquid water easily causes water flooding and seriously hinders the normal operation of URFC due to the existence of gas and liquid in the cell during the actual operation [18][19][20][21][22][23] . Therefore, studying two-phase flow in simulation and reducing flooding phenomenon is important.…”

Section: Introductionmentioning

confidence: 99%

Mass transfer and cell performance of a unitized regenerative fuel cell with nonuniform depth channel in oxygen‐side flow field

Jia

Guo

et al. 2019

Self Cite

Summary In this study, the cell performance of nonuniform depth and conventional straight channel in a unitized regenerative fuel cell (URFC) is compared. Various shapes of oxygen‐side channel cases are also proposed. Several parameters, such as the distribution of reactants and products and current density and powers in fuel cell (FC) and electrolytic cell (EC) modes, are investigated. A steady‐state model of two‐dimensional, two‐phase, nonisothermal, and coupled electrochemical reaction is developed. Five oxygen‐side channel shapes are also designed, in which the depth along the flow direction is narrowed. Result shows that narrowing the average channel depth can promote and guide the reactant transfer to the catalyst layer and avoid the blocking of the production. Thus, in comparison with the conventional channel, the cell performances of nonuniform depth and shallow straight channel cases are improved in both modes. In addition, with the decrease of average channel depth, the temperature uniformity gets better, which is also conductive to the improvement of cell performance. Furthermore, in FC mode at low voltage and EC mode, the cell net power basically increases with the decrease of the average channel depth ratio. And when the average channel depth is the same, the net power of straight channel is always lower than nonuniform depth case. This study introduces the round‐trip energy efficiency as an evaluation indicator of URFC. This efficiency can be increased by improving the cell performance of both modes, especially at high current density.