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Flow field and electrolyte potential in a PEMFC.
The Fuel Cell & Electrolyzer Module is designed for gaining a deeper understanding of fuel cell and electrolyzer systems, which is useful for designing and optimizing the electrochemical cells. The types of systems that may be studied include proton exchange membrane fuel cells (PEMFCs), hydroxide exchange (alkaline) fuel cells (AFCs), and solid oxide fuel cells (SOFCs), as well as the corresponding water electrolyzer systems. These simulations can involve the transport of charged and neutral species, current conduction, fluid flow, heat transfer, and electrochemical reactions in porous electrodes.
Alkaline water electrolysis is a well-established industrial process for producing hydrogen gas. In the cell, hydrogen gas is formed at the cathode whereas oxygen gas is formed at the anode. The electrolyte is an aqueous liquid, and when the evolved gases form bubbles, the effective ionic conductivity is lowered. The generated gases may have a detrimental effect on cell performance also due to a lowered accessible surface area for the electrode reactions. This example investigates the impact of the gas formation on the performance of an alkaline electrolysis cell.
In a polymer electrolyte membrane electrolyzer cell (PEMEC), the two electrode compartments are separated by a polymer membrane. Liquid water is fed to the anode side, forming oxygen gas on the anode, and hydrogen gas on the cathode side, respectively. The respective designs of the flow field patterns are important in order to obtain a uniform distribution of flow, in combination with low pressure drops, during operation. In this example, the mixture model is used to model the two-phase fluid dynamics on the anode side of a PEMEC.
This tutorial explores the current distribution in a low-temperature PEMFC when using serpentine-based flow field patterns. The cell is operated in counter-flow mode so that the oxygen and hydrogen inlet flow streams are located at opposite sides. Relatively dry inlet gas compositions are used so that the cell relies on self-humidification for achieving good performance.
This example models a solid oxide electrolyzer cell wherein water vapor is reduced to form hydrogen gas on the cathode, and oxygen gas is evolved on the anode. The current distribution in the cell is coupled to the cathode mass transfer of hydrogen and water and momentum transport.
This model defines a zero-gap alkaline water electrolyzer, where oxygen and hydrogen gas are evolved in porous gas diffusion nickel felt electrodes, placed adjacent to a porous separator (diaphragm). The geometry defines a unit cell of an electrolyzer stack, in turn comprising two full electrolyzer cells, extending 10 cm along the channel direction. The two electrolyzer cells are separated by a corrugated bipolar steel plate.
This tutorial models the intercoupled electrochemical reactions, charge and species transport as well as heat transfer in a polymer electrolyte membrane (PEM) fuel cell. For the gas flow fields, straight channels are used on the hydrogen anode side, whereas a mesh structure is used on the air cathode side. The cell is cooled by a cooling fluid, flowing in a separate channel.
In an alkaline electrolyzer stack, all cells share the same electrolyte. As a result of all cells being in ionic contact, parasitic shunt currents flow between the cells through the manifolds and the electrolyte channels, on both the inlet and outlet side. This example models a secondary current distribution in a stack comprising 20 cells. The electricity-to-hydrogen coulombic and energy efficiencies for the stack are computed, as well as the individual shunt currents entering or exiting each cell.
