Abstract: Fuel cell systems and methods for controlling the operation of components of the fuel cell system, which may include a fuel source and a fuel cell stack. In some examples, a fuel source is adapted to provide supply fuel to a fuel cell stack at a supply pressure. The fuel cell stack produces electric current at a production amperage. In some examples, a control system is adapted to control operation of the fuel cell stack based on a pressure detected at the fuel cell stack. In some examples, a target production amperage is determined based on the detected pressure, such that when electric current is produced at the target production amperage for the detected pressure, the fuel cell stack consumes a predetermined proportion of the supply fuel.

Abstract: Fuel cell systems and methods for controlling the operation of fuel cell assemblies included therein. In some embodiments, the fuel cell assemblies include a fuel processor and a fuel cell stack, and the fuel cell system includes a control system that controls the operation thereof based upon at least one variable associated therewith. In some embodiments, the variable is associated with the hydrogen (or other product) stream from the fuel processor. In some embodiments, the variable is the pressure of this stream. In some embodiments, the control system controls the operation of the fuel cell system to maintain the pressure of the hydrogen stream within one or more threshold values. In some embodiments, the control system controls the operation of the fuel cell system to maintain the pressure of the hydrogen stream within selected threshold values and to maintain the fuel cell stack's output voltage above a selected threshold.

Abstract: Fuel cell systems and methods for controlling the operation of components of the fuel cell system, which may include a fuel source and a fuel cell stack. In some examples, a fuel source is adapted to provide supply fuel to a fuel cell stack at a supply pressure. The fuel cell stack produces electric current at a production amperage. In some examples, a control system is adapted to control operation of the fuel cell stack based on a pressure detected at the fuel cell stack. In some examples, a target production amperage is determined based on the detected pressure, such that when electric current is produced at the target production amperage for the detected pressure, the fuel cell stack consumes a predetermined proportion of the supply fuel.

Abstract: Feedstock delivery systems and hydrogen-producing fuel processing assemblies and fuel cell systems containing the same. The feedstock delivery systems include a liquid pump that draws at least one liquid feedstock from a supply and delivers at least one feed stream containing the feedstock(s) to a fuel processor, such as to the hydrogen-producing region thereof. The feedstock delivery system further includes a recycle conduit that establishes a fluid flow path for the liquid feedstock(s) from a location downstream of the pump back to a location upstream of the pump. In some embodiments, the feedstock delivery system further includes a flow restrictor associated with the recycle conduit and a pressure-actuated valve that selectively permits the recycled feedstock to bypass the flow restrictor. In some embodiments, the pump is configured to draw a greater flow rate of the feed stream from the supply than is delivered to the fuel processor.

Abstract: Fuel cell systems and methods for controlling the operation of components of the fuel cell system, which may include a fuel source and a fuel cell stack. In some examples, a fuel source is adapted to provide supply fuel to a fuel cell stack at a supply pressure. The fuel cell stack produces electric current at a production amperage. In some examples, a control system is adapted to control operation of the fuel cell stack based on a pressure detected at the fuel cell stack. In some examples, a target production amperage is determined based on the detected pressure, such that when electric current is produced at the target production amperage for the detected pressure, the fuel cell stack consumes a predetermined proportion of the supply fuel.

Abstract: Hydrogen-producing fuel processing assemblies, including steam reforming fuel processing assemblies, startup assemblies for use therein, and methods of operating the same. In some embodiments, the startup assemblies include a startup reforming region that is upstream from a primary, or second, hydrogen-producing reforming region. In some embodiments, the startup reforming region and primary reforming regions are both steam reforming regions. In some embodiments, the startup assembly further includes at least one of a vaporization region and a startup heating assembly. In some embodiments, the startup heating assembly is an electrically powered heating assembly, and the fuel processing assembly further includes a (primary) heating assembly that combusts a byproduct stream from the fuel processing assembly to produce a combustion exhaust stream.

Abstract: Fuel cell systems and methods for controlling the operation of components of the fuel cell system, such as which may include a fuel source and a fuel cell stack. In some examples, a fuel source is adapted to provide supply fuel to a fuel cell stack at a supply pressure. In some systems, fuel not used by the fuel cell stack is discharged through at least one exit orifice at an exit pressure. In some examples, a control system is adapted to control operation of one or both of the fuel source and the fuel cell stack based on the flow of unused fuel. In some examples, a target pressure is determined based on the level of electrical current produced by a fuel cell stack, such that when fuel is supplied at the target pressure, the fuel cell stack consumes a given proportion of the supply fuel.

Abstract: Fuel cell systems and methods for controlling the operation of components of the fuel cell system, such as which may include a fuel source and a fuel cell stack. In some examples, a fuel source is adapted to provide supply fuel to a fuel cell stack at a supply pressure. In some systems, fuel not used by the fuel cell stack is discharged through at least one exit orifice at an exit pressure. In some examples, a control system is adapted to control operation of one or both of the fuel source and the fuel cell stack based on the flow of unused fuel. In some examples, a target pressure is determined based on the level of electrical current produced by a fuel cell stack, such that when fuel is supplied at the target pressure, the fuel cell stack consumes a given proportion of the supply fuel.

Abstract: Feedstock delivery systems and hydrogen-producing fuel processing assemblies and fuel cell systems containing the same. The feedstock delivery systems include a liquid pump that draws at least one liquid feedstock from a supply and delivers at least one feed stream containing the feedstock(s) to a fuel processor, such as to the hydrogen-producing region thereof. The feedstock delivery system further includes a recycle conduit that establishes a fluid flow path for the liquid feedstock(s) from a location downstream of the pump back to a location upstream of the pump. In some embodiments, the feedstock delivery system further includes a flow restrictor associated with the recycle conduit and a pressure-actuated valve that selectively permits the recycled feedstock to bypass the flow restrictor. In some embodiments, the pump is configured to draw a greater flow rate of the feed stream from the supply than is delivered to the fuel processor.

Abstract: Hydrogen-producing fuel processing assemblies, including steam reforming fuel processing assemblies, startup assemblies for use therein, and methods of operating the same. In some embodiments, the startup assemblies include a startup reforming region that is upstream from a primary, or second, hydrogen-producing reforming region. In some embodiments, the startup reforming region and primary reforming regions are both steam reforming regions. In some embodiments, the startup assembly further includes at least one of a vaporization region and a startup heating assembly. In some embodiments, the startup heating assembly is an electrically powered heating assembly, and the fuel processing assembly further includes a (primary) heating assembly that combusts a byproduct stream from the fuel processing assembly to produce a combustion exhaust stream.

Abstract: Systems and methods of purging liquid from an anode flow field of a fuel cell having an anode region and a cathode region. A fuel cell is electrically coupled to an energy consuming device that applies a load to the fuel cell. A fuel stream is delivered to the anode region, and an oxidant stream to the cathode region, thereby causing an anode purge stream to be emitted from the anode region, and causing the fuel cell to generate an electrical output that satisfies at least a portion of the electrical load. The fuel cell is then electrically isolated from the applied load for a temporary period of time without substantially altering the flow rate of the fuel stream delivered to the anode region. The period of time is sufficient to cause the flow rate of the purge stream emitted from the anode region to increase in magnitude to expel from the anode region a substantial portion of any liquid that has collected in the anode flow field.

Abstract: Fuel cell systems and methods for controlling the operation of fuel cell assemblies included therein. In some embodiments, the fuel cell assemblies include a fuel processor and a fuel cell stack, and the fuel cell system includes a control system that controls the operation thereof based upon at least one variable associated therewith. In some embodiments, the variable is associated with the hydrogen (or other product) stream from the fuel processor. In some embodiments, the variable is the pressure of this stream. In some embodiments, the control system controls the operation of the fuel cell system to maintain the pressure of the hydrogen stream within one or more threshold values. In some embodiments, the control system controls the operation of the fuel cell system to maintain the pressure of the hydrogen stream within selected threshold values and to maintain the fuel cell stack's output voltage above a selected threshold.

Abstract: Fuel cell systems and methods for controlling the operation of components of the fuel cell system, which may include a fuel source and a fuel cell stack. In some examples, a fuel source is adapted to provide supply fuel to a fuel cell stack at a supply pressure. The fuel cell stack produces electric current at a production amperage. In some examples, a control system is adapted to control operation of the fuel cell stack based on a pressure detected at the fuel cell stack. In some examples, a target production amperage is determined based on the detected pressure, such that when electric current is produced at the target production amperage for the detected pressure, the fuel cell stack consumes a predetermined proportion of the supply fuel.

Abstract: Fuel cell systems and methods for controlling the operation of components of the fuel cell system, such as which may include a fuel source and a fuel cell stack. In some examples, a fuel source is adapted to provide supply fuel to a fuel cell stack at a supply pressure. In some systems, fuel not used by the fuel cell stack is discharged through at least one exit orifice at an exit pressure. In some examples, a control system is adapted to control operation of one or both of the fuel source and the fuel cell stack based on the flow of unused fuel. In some examples, a target pressure is determined based on the level of electrical current produced by a fuel cell stack, such that when fuel is supplied at the target pressure, the fuel cell stack consumes a given proportion of the supply fuel.