Fuel Cell Stack Operation with Low Cathode Stoichiometry with Cells or Sections Fed in Series

摘要

Reducing the air flow rate at the stack inlet could lower parasitic power and improve the system efficiency. However, this gain should not be offset by the loss of stack performance due to lower cathode stoichiometry. A configuration in which the sections of a stack are fed in series enabling operation at low stoichiometry while each section operates with significantly higher stoichiometry is analyzed. A drawback is that the second and each subsequent section would operate with reduced oxygen concentration at the inlet. The results of experimental and numerical analysis show that for the high pressure systems a stack with cathode sections fed with air in series could be considered as an alternative to the conventional parallel-fed stack design. However, this advantage diminishes for the systems with reduced parasitic losses such as the systems operating at lower pressures and the high pressure systems with an expander at the cathode exhaust.