Startup and Shutdown Strategies

Durability is most challenging in the development of all kinds of fuel cells. For commercialization fuel cells have to have lifetimes comparable to those 

and IV parts. These four parts form an internal circuit as indicated by the arrows for the flows of electrons and protons in the figure. The half reaction at Part I is the common hydrogen oxidation reaction with an electrode/ PEM interfacial potential around 0 V the half reaction at Parts II and III is the 

Typical OCV and the anode/PEM and the cathode/PEM interfacial potentials during shutdown time period. 

Voltage situation when an O2/H2 boundary forms at anode. 

Similar process and damage can occur after a fuel cell is shut down if air from the environment diffuses info fhe anode chamber. 

---

Startup and Shutdown Strategies. In addition to safe operation, the usual goal of a reactor startup is to minimize production of off-specification material. This can sometimes be accomplished perfectly. 

Because ice formation is the main reason for structural and performance degradation during exposure to subzero temperatures, proposed mitigation strategies include gas purging and solution purging to remove residual water during fuel cell startup and shutdown. Delamination between the CLs and the baer membrane can result in the development of flooded areas, increased resistance in the MEA, the development of pinhole areas, loss of apparent catalytic activity, and the development of areas susceptible to erosion. 

Repeat steps 2-4 for each control strategy. Compare ease of startup and shutdown, disturbance rejection, what would happen if there were a change in the rate of production, complexity, and interaction between the controllers [14]. 

The AP-X process was new and required new startup, operating and shutdown procedmes. A new control strategy was also needed, and it was developed and tested using simulation. For the nitrogen loop, dynamic simulation was used to prove that it was possible for the process to successfully respond to the sudden loss of one... 

---