Patent ID: 7393602

Claim:
A method for determining when to start a coolant pump in a fuel cell system at system start-up, said fuel cell system including a fuel cell stack, said fuel cell stack including a stack of fuel cells, said method comprising: determining a start temperature of the fuel cell stack; calculating a theoretical voltage of the fuel cell stack; calculating an average cell voltage for the fuel cells in the fuel cell stack; calculating an average current density of the fuel cells in the fuel cell stack; scaling the calculated current density to account for localized non-uniformities in the fuel cells; calculating an original heat rate of the fuel cell stack over a predetermined time interval; scaling the original heat rate based on the start temperature to provide a corrected heat rate to include heat losses from a control volume element; determining whether to use the corrected heat rate or the original heat rate based on the current density for a temperature calculation; calculating an energy in the control element based on the determined heat rate over the time interval; calculating a temperature increase of the control element based on the energy in the control element; calculating a new temperature of the control element based on the temperature increase of the control element; starting the coolant pump if the new temperature is above a predetermined temperature; and using the new temperature as the start temperature to repeat the process of calculating the new temperature if the new temperature is less than the predetermined temperature.