Modelling of a porous flowing electrolyte layer in a flowing electrolyte direct-methanol fuel cell

Duivesteyn, Eric, et al. “Modelling of a Porous Flowing Electrolyte Layer in a Flowing Electrolyte Direct-Methanol Fuel Cell.” International Journal of Hydrogen Energy, vol. 38, no. 30, 8 Oct. 2013, pp. 13434—13442. Web of Science, doi:10.1016/j.ijhydene.2013.08.017.

Presented by Juni Kim

Introduction (Direct Methanol Cell)

  1. Small Devices (e.g. golf carts, forklifts, electronic devices)
  2. Standard battery cell principles
  3. ABL $\rightarrow$ ACL (anode catalyst layer, oxidation occurs)
  4. Redox Reaction separated by PEM (polymer electrolyte membrane, protons pass through)

Introduction (Fluid Electrolyte-DMFC)

  1. Methanol Crossover- Methanol leaks through the PEM, reduces reaction efficiency
  2. Flowing Electrolyte Channel ($H_2SO_4$ sandwiched between PEM layers, washes away methanol)
  3. Porous Material as structural support + flow
  4. Ohmic losses b/c of the imperfect proton conductance of $H_2SO_4$

Introduction (Novelty)

  • Typically modeled with a parabolic velocity profile (non-porous)
  • Approach: include porous properties in modeling

Methods and Materials

  1. ANSYS CFX (Proprietary Computational Fluid Dynamics Software)

Assumptions

  • Constant Temperature, active area
  • Water-like properties
  • Laminar Flow
  • Used PET (Polyethylene) spacer properties (porousness)

Results

  • Thin and constant boundary layer despite velocity flux
  • Velocity Profile is relatively constant

Results (cont)

  • Permeability (ability of $H_2SO_4$ to pass) - significant effects on pressure drop
  • Porosity (amount of open space), relatively minimal effects

Conclusion

  • Novelty in fluid flow modeling of a fluid electrolyte
  • Maximize size of pores (permeability)
  • Minimize size of channel (ohmic losses)
  • Maximize Volume Flux (methanol crossover)
  • Perhaps in research interest?