Dimensional effect of graphite flow field channels of a direct methanol fuel cell under different operating conditions

Abstract

Direct methanol fuel cells are a potential candidate to replace traditional power sources for portable applications. The flow field design, manufacture, and optimization are of great significance to the cell performance. When the scale of flow channels decreases to the level of submillimeter‐scale, it is favourable to the reactant and product management. This paper focuses on the effectiveness of using a multi‐tooth planing technique to create submillimeter‐scale parallel channels in a graphite sheet. Besides the structural parameters of flow channels, a series of operating parameters are experimentally investigated, including methanol concentration, methanol feed rate, oxygen feed rate, cathode backpressure, and environmental temperature. Results indicate that the prepared channels promote a higher cell performance than the traditional design with a larger scale. It is beneficial to both the anode and cathode performances, but it has a more prominent effect at the anode. The methanol concentration of 4 mol/L yields the best performance. Using a relatively lower methanol feed rate below 0.5 mL/min has a more obvious effect on the fuel cell. The cell performance is insensitive to the change of cathode oxygen feed rate and backpressure especially when the oxygen can be sufficiently supplied. In this case we can use lower levels of oxygen feed rate and cathode backpressure. The cell temperatures and influence of environmental temperature are also discussed.

Local durability optimization of a large-scale direct methanol fuel cell: catalyst layer tuning for homogeneous operation and in-operando detection of localized hydrogen evolution

“…It is worth to mention that, particularly when dealing with samples upscale, the flow pattern of reactant distributors is of utter importance in determining local performance distribution; indeed, numerous works are present in the literature focusing on the identification of optimal distributor geometries [22][23][24][25][26][27][28]. In this work, instead, we intend to demonstrate that an alternative, or additional, approach can pursue local performance homogenization and stability improvement by optimizing local properties of the MEA given a specific a flow pattern for the distributors.…”

Performance enhancement of direct methanol fuel cell using multi‐zone narrow flow fields

“…They concluded that a metal mesh achieves a better performance at a low methanol concentration. Tan et al 26 studied the effects of the flow channel length on the performance of a DMFC, and concluded that using small channels of sub-millimeter dimensions is preferable, particularly at the anode side. They also found an increase in the parasitic pumping loads through the use of narrower channels.…”