Patent ID: 8790840

Claim:
A method of operating a fuel cell system that is configured to supply an electrical output to an energy consuming device and which comprises a fuel cell stack configured to produce the electrical output, an energy delivery system configured to supply the electrical output to the energy consuming device, a thermal management system configured to regulate the temperature of the fuel cell stack, a fuel supply system configured to supply fuel to the fuel cell stack, an oxidant supply system configured to supply oxidant to the fuel cell stack, a sensor system configured to detect a status of the fuel cell system, and a control system configured to control operation of the fuel cell system, the method comprising: supplying a feedstock stream to a fuel processing assembly of the fuel supply system; generating a mixed gas stream, which includes hydrogen gas and other gasses, from the feedstock stream within the fuel processing assembly; purifying the mixed gas stream within a separation region of the fuel supply system to generate a byproduct stream, which includes a greater concentration of the other gasses than the mixed gas stream, and a fuel stream, which includes a greater concentration of hydrogen gas than the mixed gas stream; supplying the fuel stream from the fuel supply system to the fuel cell stack; supplying an oxidant stream from the oxidant supply system to the fuel cell stack; producing the electrical output from the fuel cell stack; supplying a thermal management fluid from the thermal management system and from a fuel cell stack fluid outlet to a fuel cell stack fluid inlet in a thermal management fluid recirculation loop, wherein the thermal management fluid recirculation loop includes a thermal management fluid conditioning assembly; detecting a variable associated with the oxidant stream, wherein the variable associated with the oxidant stream is an oxidant inlet temperature associated with the oxidant stream at a fuel cell stack oxidant inlet; detecting a temperature associated with the thermal management fluid; and controlling the temperature associated with the thermal management fluid based at least in part on the variable associated with the oxidant stream by controlling a heat transfer from the thermal management fluid by the thermal management fluid conditioning assembly.