Abstract
The dynamics of liquid water in the gas channels with rectangular sections (REC), trapezoidal sections with open angles of 60 degrees (T60), and trapezoidal sections with open angles of 72 degrees (T72) are numerically investigated via the volume of fluid method. The effects of the contact angle of the top and side walls (CATS), the water inlet configuration, and the air inlet velocity are studied based on the temporal evolution of gas-liquid interface, the water volume fraction (WVF), the water coverage ratio of the gas diffusion layer (GDL) surface (GWCR), and the pressure drop between the air inlet and the outlet. For the hydrophobic GDL surface and the hydrophilic top and side walls, the T72 provides the lowest WVF and GWCR of around 7 percent due to periodic pressure spikes. The REC and T60 show a higher WVF and a lower GWCR as most of liquid water moves along the channel while attached to the top wall. As the CATS increases from 60 to 120 degrees, the behaviors of liquid water become similar for the three cross-sectional shapes. The T72 shows especially similar results irrespective of the CATS. When the liquid water emergence is concentrated along the side wall, the T72 shows the best water removal characteristics. For all the three channel cross-sectional shapes, water slugs move faster and have smaller sizes as the air inlet velocity increases.
Highlights
To address the problems of environmental pollution, energy depletion, and climate change due to the excessive usage of fossil fuels, polymer electrolyte membrane (PEM) fuel cell has been one of the promising candidates among various alternative energy technologies [1,2,3,4]
A water slug attached to the water inlet behaves like a variable sized valve in the gas channel (GC) cross section and the spike in the pressure difference is observed in Figure 2f for the T72 configuration
The GWCR of the T72 configuration shows higher values than the other two because some portion of liquid water travels along the GC attached to the side and gas diffusion layer (GDL) surfaces
Summary
The PEM fuel cell has many advantages which include high power density, zero emissions, a low operating temperature range, and a wide range of applications. One major technological issue of the PEM fuel cell is proper water management to avoid membrane dehydration and the so-called water flooding phenomena [5,6,7,8]. A properly hydrated membrane produces the best performance and the cathode gas diffusion layer (GDL) surface should be free of liquid water to provide sufficient amounts of oxygen. Water removal in the gas channel (GC) is especially important in automotive applications of PEM fuel cells due to the frequent demand for high current density. To visualize and quantify the gas-liquid two-phase flow phenomena in the GC and the GDL, many experimental and numerical modeling techniques have been applied [5,6].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
