Understanding the Impact of Flow Fields on the Performance of Direct Methanol Fuel Cells: A Review on Design Trends.

Flow fields (FFs) play multifaceted roles in direct methanol fuel cells (DMFC) by facilitating the transport and distribution of species, removal of products, support to the membrane electrode assembly (MEA), electrical conductivity, water, and thermal management. Therefore, the performance of DMFC is directly related to the pattern and geometry of the FF. DMFCs can generate power density of up to ≈100-300 mW cm-2; however, their performance is impeded by cathode flooding, CO2 gas bubbles formation, and mass transfer limitations. These can be mitigated by employing appropriate FF designs with modifications in their geometrical parameters, such as rib area, channel width, and aspect ratio. This review underscores the importance of the five different FF patterns (parallel, serpentine, interdigitated, pin-type, and bioinspired) on the performance of the DMFC by highlighting the different experimental and computational investigations. How different FF patterns can aid in extenuating the limitations of DMFC and thereby boost their performance is discussed. Subsequently, the importance of employing computational fluid dynamics models to investigate the different FF patterns for developing efficient DMFC is also assessed. Finally, as a future prospect, how efficient FF designs can aid the development of μ-DMFC for portable applications is discussed.