Numerical analysis of anion-exchange membrane direct glycerol fuel cells under steady state and dynamic operations

• Developed new mathematical model of an AEM-based direct glycerol fuel cell.
• Numerically analyzed effects of design and reaction conditions on cell performance.
• Predicted dynamic cell behavior from transient mass transport and overpotentials.
• Verified model by comparison with steady state and dynamic experimental results.

This work develops a one-dimensional model of an alkaline anion-exchange membrane direct glycerol fuel cell (AEM-DGFC) for cogeneration of tartronate and electricity. The model is validated against steady state and dynamic experiments, and shows good agreement. Steady state modeling includes anode and cathode losses and predicts the single cell polarization and power density curves. Coupled mass transport, charge transport, and electrochemical kinetics predict the effects of varying reactant concentration and diffusion layer porosity on single cell performance. The results show that anode overpotential is the major source of loss at middle to high current density regions, due to limited glycerol diffusion at the catalyst layer. Furthermore, the dynamic response of AEM-DGFC to step changes in current density is simulated by considering time-dependent species transport and double-layer capacitance charging. Analysis of dynamic simulation reveals that the liquid-phase reactant diffusion is a key factor influencing the transient AEM-DGFC behavior and is very sensitive to diffusion layer design. This new numerical analysis of a glycerol-fed fuel cell demonstrates that a simple, single oxidation product model can successfully predict the steady state and dynamic losses.

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