Abstract: An optical detection system for detecting undesirable constituents in a fuel cell system includes a sensing material configured to change color in the presence of the undesirable constituents and at least one sensor configured to register the change in color of the sensing material. The sensor is coupled to a corresponding light source. The sensing material, the sensor and the light source are enclosed in a housing.

Abstract: An optical detection system for detecting undesirable constituents in a fuel cell system includes a sensing material configured to change color in the presence of the undesirable constituents and at least one sensor configured to register the change in color of the sensing material. The sensor is coupled to a corresponding light source. The sensing material, the sensor and the light source are enclosed in a housing.

Abstract: A technique includes operating a converter to convert a first voltage produced by an electrochemical cell stack in a power producing mode into a second voltage. The technique includes operating the converter to convert a third voltage into a fourth voltage to drive the electrochemical cell stack in a pumping mode.

Abstract: A system and technique for purging condensate from an electrochemical cell stack prior to operating the stack in one of a power producing mode of operation and an electrochemical pumping mode of operation is provided. The system and technique include storing hydrogen in the anode and cathode chambers of the stack to place the stack in a shutdown state, purging the anode and cathode chambers of condensate prior to starting operation of the stack, and preventing a fuel starvation condition in the stack while purging by sequencing communication of a fuel flow and an oxidant flow to the anode chamber with an oxidant flow to the cathode chamber while purging the condensate.

Abstract: A technique includes operating an electrochemical cell as a pump, including providing a current to the cell and providing a fuel flow to an anode chamber of the cell. The technique includes communicating an anode exhaust flow from the anode chamber to an oxidizer and controlling the current to regulate a temperature of the oxidizer.

Abstract: A system and technique for switching the polarity of an electrochemical cell stack to switch operation of the stack between a power producing mode of operation and an electrochemical pumping mode of operation is provided. The system and technique include a plurality of polarity switches that are switched between configurations in response to a mode select signal.

Abstract: A technique includes operating an electrochemical cell stack in a power producing mode, including communicating a fuel flow in an anode chamber of the stack and communicating an oxidant flow in a cathode chamber of the stack. The technique includes halting the oxidant flow and monitoring a voltage of the stack while the oxidant flow is halted, and in response to the voltage decreasing below a predefined threshold, transitioning the stack into an electrochemical cell pumping mode.

Abstract: A technique includes operating an electrochemical cell as a pump, including providing a current to the cell and providing a fuel flow to an anode chamber of the cell. The technique includes communicating an anode exhaust flow from the anode chamber to an oxidizer and controlling the current to regulate a temperature of the oxidizer.

Abstract: A system and technique for purging condensate from an electrochemical cell stack prior to operating the stack in one of a power producing mode of operation and an electrochemical pumping mode of operation is provided. The system and technique include storing hydrogen in the anode and cathode chambers of the stack to place the stack in a shutdown state, purging the anode and cathode chambers of condensate prior to starting operation of the stack, and preventing a fuel starvation condition in the stack while purging by sequencing communication of a fuel flow and an oxidant flow to the anode chamber with an oxidant flow to the cathode chamber while purging the condensate.

Abstract: A technique includes operating a converter to convert a first voltage produced by an electrochemical cell stack in a power producing mode into a second voltage. The technique includes operating the converter to convert a third voltage into a fourth voltage to drive the electrochemical cell stack in a pumping mode.

Abstract: A system and technique for switching the polarity of an electrochemical cell stack to switch operation of the stack between a power producing mode of operation and an electrochemical pumping mode of operation is provided. The system and technique include a plurality of polarity switches that are switched between configurations in response to a mode select signal.