Abstract: A technique that is usable with a fuel cell includes generating a humidified reactant flow. The technique includes measuring a rate of condensate production from the reactant flow and controlling the generation of the humidified reactant flow in response to the measured rate of condensate production.

Abstract: A technique includes providing a fluid to a heat exchanger to produce a gas. The technique includes humidifying a flow of a fuel cell system with the gas and regulating a level of the fluid in the heat exchanger based on a temperature of the gas.

Abstract: A technique that is usable with a fuel cell includes generating a humidified reactant flow. The technique includes measuring a rate of condensate production from the reactant flow and controlling the generation of the humidified reactant flow in response to the measured rate of condensate production.

Abstract: The invention relates to systems and associated methods of operating fuel cell systems where the rotational speed of a reactant humidification enthalpy wheel is dynamically controlled according to various process variables. In one embodiment, a method is provided for operating a fuel cell system, including the following steps: (1) rotating a porous desiccant material about a rotational axis; (2) flowing air through the desiccant material in a direction parallel to the rotational axis to a cathode inlet of a fuel cell; (3) flowing cathode exhaust from the fuel cell through the desiccant material; (4) monitoring a process performance variable; (5) detecting a change in a value of the process performance variable; and (6) varying a rotational speed of the desiccant material in response to the detected change in the value of the process performance variable.

Abstract: A technique that is usable with a fuel cell system includes using a stored energy source to supply power to a load, placing a fuel cell stack in an inactive state during the using, returning the fuel cell stack to an active state to recharge the stored energy source and returning the fuel cell stack to the inactive state in response to the completion of the charging. Another technique may include determining a system power demand in the fuel cell system and may include determining whether a fuel cell stack is exhibiting unstable behavior during an interval of low power demand from the fuel cell stack. In response to these determinations, the fuel cell stack is isolated from the fuel cell system. Another technique includes pulsing a fuel processor of the fuel cell system with an input reactant flow to minimize at least one of a power loss and a startup time of the fuel processor.

Abstract: The invention relates to systems and associated methods of operating fuel cell systems where the rotational speed of a reactant humidification enthalpy wheel is dynamically controlled according to various process variables. In one embodiment, a method is provided for operating a fuel cell system, including the following steps: (1) rotating a porous desiccant material about a rotational axis; (2) flowing air through the desiccant material in a direction parallel to the rotational axis to a cathode inlet of a fuel cell; (3) flowing cathode exhaust from the fuel cell through the desiccant material; (4) monitoring a process performance variable; (5) detecting a change in a value of the process performance variable; and (6) varying a rotational speed of the desiccant material in response to the detected change in the value of the process performance variable.