Controls giving −25° C. freeze start capability to a fuel cell system

摘要

A method for shutting down a fuel cell system including operating a fuel cell stack. the method includes providing an increased cathode air flow so as to dry fuel cell membranes in the stack until a first desired level of high frequency resistance is achieved, rehydrating the cell membranes of the stack until a second desired level of high frequency resistance is achieved, and operating the stack with a decreased cathode input relative humidity until a third desired level of high frequency resistance is achieved.

主权项

1. A method for shutting down a fuel cell system, said method comprising:
operating a fuel cell stack with an air flow so as to dry a plurality of fuel cell membranes in the stack to a predetermined average HFR within a predetermined window of time such that a first level of average high frequency resistance is achieved; rehydrating the cell membranes of the stack until a second level of average high frequency resistance is achieved; operating the stack with a predetermined cathode input relative humidity until a third level of average high frequency resistance is achieved; and shutting down the fuel cell system.