Abstract: Pressure swing adsorption (PSA) assemblies with optimized startup times, as well as to hydrogen-generation assemblies and/or fuel cell systems containing the same, and methods of operating the same. Startup and shutdown methods for a PSA assembly, and optionally an associated fuel processing system, are disclosed to provide for shortened startup times. The PSA assemblies may be in fluid communication with a hydrogen source that may be used or otherwise configured or controlled to purge the PSA adsorbent columns of adsorbents during startup and/or shutdown procedures, the hydrogen source additionally or alternatively may be used or otherwise configured or controlled to charge the columns with hydrogen for idling in a pressurized state. The use of this hydrogen source, together with specific startup and shutdown methodologies, provides for reducing the startup time of the PSA assembly.

Abstract: Thermal and hydration management systems and methods for fuel cell systems, including control of electrolytic membrane hydration levels. In some embodiments, the thermal properties of the fuel cell are controlled based on a variable associated with the oxidant supply stream and/or a variable associated with the fuel cell energy output. In some embodiments, the temperature of the fuel cell is controlled based on the temperature of the oxidant supply stream. In some embodiments, the temperature range across the fuel cell stack is controlled based on the flow rate of the oxidant stream and the electrical output generated by the fuel cell stack. In some embodiments, the humidity within the fuel cell stack is controlled. In some embodiments, the liquid water content of the cathode exhaust stream is controlled.

Abstract: A system for optimizing the purge cycle of a fuel cell stack responsive to the performance of the fuel cell. The system includes a controller that measures a process parameter indicative of the rate at which water is being produced in the fuel cell. If the measured value exceeds a threshold value, then the purge assembly is automatically actuated.

Abstract: Systems and methods for producing hydrogen gas with a fuel processing system that includes a hydrogen-producing region that produces hydrogen gas from a feed stream and a heating assembly that consumes a fuel stream to produce a heated exhaust stream for heating the hydrogen-producing region. In some embodiments, the heating assembly heats the hydrogen-producing region to at least a minimum hydrogen-producing temperature. In some embodiments, the rate at which an air stream is delivered to the heating assembly is controlled to selectively increase or decrease the temperature of the heated exhaust stream. In some embodiments, the feed stream and the fuel stream both contain a carbon-containing feedstock and at least 25 wt % water. In some embodiments, the feed and fuel streams have the same composition.

Abstract: Thermally primed fuel processing assemblies and hydrogen-producing fuel cell systems that include the same. The thermally primed fuel processing assemblies include at least one hydrogen-producing region housed within an internal compartment of a heated containment structure. In some embodiments, the heated containment structure is an oven. In some embodiments, the compartment also contains a purification region and/or heating assembly. In some embodiments, the containment structure is adapted to heat and maintain the internal compartment at or above a threshold temperature, which may correspond to a suitable hydrogen-producing temperature. In some embodiments, the containment structure is adapted to maintain this temperature during periods in which the fuel cell system is not producing power and/or not producing power to satisfy an applied load to the system. In some embodiments, the fuel cell system is adapted to provide backup power to a power source, which may be adapted to power the containment structure.

Abstract: The present disclosure is directed to systems and methods for maintaining hydrogen-selective membranes during periods of inactivity. These systems and methods may include heating and maintaining at least the hydrogen-selective membrane of a hydrogen-producing fuel processing system in a thermally buffered state and/or controlling the chemical composition of the gas streams that may come into contact with the hydrogen-selective membrane. Controlling the chemical composition of the gas streams that may come into contact with the hydrogen-selective membrane may include maintaining a positive pressure of an inert, blanket, reducing, and/or non-oxidizing gas within the membrane separation assembly and/or periodically supplying a reducing gas stream to the membrane separation assembly.

Abstract: Hydrogen-producing fuel processing systems, hydrogen purification membranes, hydrogen purification devices, fuel processing and fuel cell systems that include hydrogen purification devices, and methods for operating the same. In some embodiments, operation of the fuel processing system is initiated by heating at least the reforming region of the fuel processing system to at least a selected hydrogen-producing operating temperature. In some embodiments, an electric heater is utilized to perform this initial heating. In some embodiments, use of the electric heater is discontinued after startup, and a burner or other combustion-based heating assembly combusts a fuel to heat at least the hydrogen producing region, such as due to the reforming region utilizing an endothermic catalytic reaction to produce hydrogen gas.

Abstract: The present disclosure is directed to systems and methods for independently controlling the operation of fuel cell stacks and to fuel cell systems incorporating the same. These systems and methods may include providing a fuel cell system including a plurality of fuel cell stacks and at least a first energy storage device and controlling the operation of the plurality of fuel cell stacks based at least in part on a variable associated with the fuel cell system and/or an energy consuming device. These systems and methods may further include beginning production of electrical output from the fuel cell system responsive to a start condition, initiating production of electrical output from the plurality of fuel cell stacks responsive to a plurality of stack start conditions, and ceasing the production of electrical output from the fuel cell stacks responsive to at least a first stack stop condition.

Abstract: Pressure swing adsorption (PSA) assemblies and hydrogen-producing fuel processing assemblies and/or fuel cell systems including the same. The PSA assemblies include, or are utilized with, combustion fuel stream supply systems that are adapted to regulate the flow of a byproduct stream from the PSA assembly for delivery to a heating assembly for use as a combustible fuel stream, such as to maintain at least a hydrogen-producing region of the fuel processing system at a hydrogen-producing temperature or range of temperatures. In some embodiments, the combustion fuel stream supply system is configured to ensure that the supply of combustible fuel from the PSA assembly to the heating assembly contains at least a sufficient fuel value, such as to maintain at least the hydrogen-producing region at or within a predetermined hydrogen-producing temperature or range of temperatures.

Abstract: Hydrogen-producing fuel processing assemblies and methods for delivering feedstock to a hydrogen-producing region of a hydrogen-producing fuel processing assembly. In some embodiments, the fuel processing assemblies include a feedstock delivery system that includes a pump assembly and a stall prevention mechanism that is adapted to reduce pressure in an outlet conduit during periods in which the pump assembly is not emitting a liquid outlet stream within or above a hydrogen-producing pressure range. In some embodiments, pressure in the outlet conduit is isolated from pressure in the hydrogen-producing region of the fuel processing assembly and is reduced during periods in which a liquid stream is not being pumped within or above a hydrogen-producing pressure range.