Modeling and use of virtual temperature sensor at fuel cell stack active area outlet with stack coolant bypass

A fuel cell temperature-measuring system comprising:

• a coolant source that provides liquid coolant at a total coolant flow rate and an initial coolant temperature;
• a flow field plate defining coolant flow channels through which the liquid coolant flows, the coolant flow channels including peripheral flow channels and active area flow channels, the peripheral flow channels and the active area flow channels diverging from a common input and converging to a common output, the flow field plate adapted to be positioned in a fuel cell stack between individual fuel cells wherein an input liquid coolant with a total coolant flow rate provided to the common input divides into a bypass flow that flows through the peripheral flow channels with a bypass coolant flow rate and a bypass coolant temperature and an active area flow that flows through the active area flow channels with an active area flow rate and an active area temperature, the bypass flow combining with the active area flow to emerge from the common output as an output liquid coolant with an output coolant temperature;
• a temperature sensor that measures the output coolant temperature from the common output;
• and
• a temperature estimator that estimates an active area coolant temperature from the output coolant temperature.