摘要 |
A method of operating a fuel cell system 1 comprising a fuel cell assembly 2 configured to generate electrical power from a fuel flow 4 and an oxidant flow 5, the method comprising a first phase and a subsequent second phase. The first phase comprises operating the fuel cell assembly 2 with a first stoichiometric ratio of oxidant flow 5 to fuel flow 4 to generate electrical power, and providing the generated electrical power to a heater element 12 for heating a coolant for supply to the fuel cell assembly. The second phase comprises delivering coolant heated in the first phase to the fuel cell assembly 2 , and operating the fuel cell assembly with a second stoichiometric ratio of oxidant flow 5 to fuel flow 4 to generate electrical power, the second stoichiometric ratio being lower than the first ratio. A second heater element 13 may also be provided if required. This method is particularly useful in the startup of fuel cells, especially in sub-zero conditions where the fuel cell needs to be pre-heated prior to full operation. A fuel cell system and computer program suitable for carrying out the method are also claimed. |