Method to begin coolant circulation to prevent MEA overheating during cold start

A control system for determining when to start a coolant pump in a fuel cell system at fuel cell system start-up, said fuel cell system including a fuel cell stack, said fuel cell stack including a stack of fuel cells, said control system comprising:

• means for determining a start temperature of the fuel cell stack;
• means for calculating a theoretical voltage of the fuel cell stack;
• means for calculating an average cell voltage for the fuel cells in the fuel cell stack;
• means for calculating an average current density of the fuel cells in the fuel cell stack;
• means for scaling the calculated current density to account for localized non-uniformities in the fuel cells;
• means for calculating an original heat rate of the fuel cell stack over a predetermined time interval;
• means for 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;
• means for determining whether to use the corrected heat rate or the original heat rate based on the current density for a temperature calculation;
• means for calculating an energy in the control element based on the determined heat rate over the time interval;
• means for calculating a temperature increase of the control element based on the energy in the control element;
• means for calculating a new temperature of the control element based on the temperature increase of the control element;
• and
• means for starting the coolant pump if the new temperature is above a predetermined temperature, wherein the new temperature is used as the start temperature to repeat the process of calculating the new temperature if the new temperature is less than the predetermined temperature.

A fuel cell stack including a stack of fuel cells, said fuel cell stack comprising:

• a temperature sensor for sensing a start temperature of the fuel cell stack and providing a temperature signal;
• a voltage sensor for measuring the voltage of the stack and providing a stack voltage signal;
• a current sensor for measuring the current of the stack and providing a stack current signal;
• a pump for pumping a cooling fluid through the fuel cell stack;
• and
• an electronic control module for determining when to start the pump for pumping the cooling fluid through the fuel cell stack at a cold stack start-up, said electronic control module using the temperature signal, the voltage signal and the current signal to determine a temperature of a control volume element within the stack.