Abstract: Aircraft comprises a heater system, a conduit system thermally connected to fuel cell stacks, a pump system, and a controller. The heater system is configured to heat a coolant. The coolant flows through the conduit system. The pump system is configured to circulate the coolant through the conduit system to the fuel cell stacks. The controller is configured to control the heater system to heat the coolant to form a heated coolant. The controller is configured to control the pump system to circulate the heated coolant through the conduit system. The controller is configured to control the conduit system to circulate the heated coolant to a subset of the fuel cell stacks, wherein the heated coolant causes the subset of the fuel cell stacks to reach an operating temperature.

Abstract: An aircraft comprises a fuselage, wings connected to the fuselage, engines connected to the wings, and liquid hydrogen tanks. Each engine in the engines comprises a nacelle, an electric motor within the nacelle, a fuel cell stack within the nacelle, and a nacelle heat exchanger within the nacelle that receives air flowing through an inlet in the nacelle. The liquid hydrogen tanks are configured to store liquid hydrogen, wherein the liquid hydrogen tanks extend along an outside of the fuselage and above the wings and below windows in the fuselage.

Abstract: An aircraft air management system comprises an air heat exchanger; an intercooler; and a conduit system connected to the air heat exchanger, the intercooler, and a fuel cell stack. Heated air flows through the conduit system to the air heat exchanger. The air heat exchanger is configured to cool the heated air to form cooler air, wherein the cooler air flows from the air heat exchanger through the conduit system to the intercooler; and the intercooler is configured to cool the cooler air to form cooled air, wherein the cooled air flows from the intercooler through the conduit system to the fuel cell stack.

Abstract: An aircraft thermal management system comprising a high temperature loop and a low temperature loop. The high temperature loop is configured to manage a temperature of a fuel cell stack in a nacelle using a nacelle heat exchanger. The low temperature loop is configured to cool a number of heat loads in a nacelle using a heat capacity of liquid hydrogen.

Abstract: A heat exchanger system for an aircraft comprises nacelle having an inlet and an outlet, a nacelle heat exchanger within the nacelle, and a fan system within the nacelle. Air flows into the nacelle through the inlet and out of the nacelle through the outlet. The nacelle heat exchanger is configured to transfer heat away from a coolant using the air in an airflow to the nacelle heat exchanger. The fan system is configured to increase the airflow to the nacelle heat exchanger.

Abstract: A fuel cell stack is described. The fuel cell stack comprises an interconnect assembly comprising a cathode-side interface coupled to an interconnect via a first joint, and an anode-side interface coupled to the interconnect via a second joint, the interconnect assembly having a first coefficient of thermal expansion (CTE) at an interface side of the interconnect assembly. The fuel cell stack further comprises a fuel cell element coupled to the interconnect assembly at the interface side via a hermetic seal, the fuel cell element having a second CTE at the interface side, the first CTE and the second CTE satisfying a predetermined CTE matching condition.

Abstract: A fuel cell stack is described. The fuel cell stack comprises an interconnect assembly comprising a cathode-side interface coupled to an interconnect via a first joint, and an anode-side interface coupled to the interconnect via a second joint, the interconnect assembly having a first coefficient of thermal expansion (CTE) at an interface side of the interconnect assembly. The fuel cell stack further comprises a fuel cell element coupled to the interconnect assembly at the interface side via a hermetic seal, the fuel cell element having a second CTE at the interface side, the first CTE and the second CTE satisfying a predetermined CTE matching condition.

Abstract: In an example, a system for increasing solid oxide fuel cell (SOFC) efficiency is described. The system comprises a series of SOFC stacks, a fuel flow path through the series, and an air flow path through the series. In the fuel flow path between two sequential SOFC stacks in the series, fuel exhaust from a first SOFC stack of the two sequential SOFC stacks is input into a second SOFC stack of the two sequential SOFC stacks. In the air flow path between the two sequential SOFC stacks, air exhaust from the first SOFC stack is input into the second SOFC stack. Further, between the two sequential SOFC stacks, (i) the fuel flow path comprises a fuel inlet positioned for injecting fuel into the fuel flow path and/or (ii) the air flow path comprises an air inlet positioned for injecting air into the air flow path.

Abstract: A rapid start power unit and a method of operating a rapid start power unit are disclosed. A fuel cell converts combustible fuel into electrical power during a normal operational period after an initial start-up period when little to no electrical energy is produced. One combustion chamber receives unspent fuel emitted by the fuel cell and combusts the unspent fuel to generate a first heated gas stream. Another combustion chamber receives combustible fuel and burns the combustible fuel to generate a second heated gas stream during the initial start-up period. A turbine receives and is driven by the first and second heated gas streams to drive a drive shaft. A generator coupled to the drive shaft generates electrical power during the initial start-up period and supplemental power during the normal operational period. In an alternative embodiment, a two-stage combustion chamber is used instead of two serially-arranged separate combustion chambers.

Abstract: Systems and methods provide for the thermal management of a high temperature fuel cell. According to embodiments described herein, a non-reactant coolant is routed into a fuel cell from a compressor or a ram air source. The non-reactant coolant absorbs waste heat from the electrochemical reaction within the fuel cell. The heated coolant is discharged from the fuel cell and is vented to the surrounding environment or directed through a turbine. The energy recouped from the heated coolant by the turbine may be used to drive the compressor or a generator to create additional electricity and increase the efficiency of the fuel cell system. A portion of the heated coolant may be recycled into the non-reactant coolant entering the fuel cell to prevent thermal shock of the fuel cell.

Abstract: A rapid start power unit and a method of operating a rapid start power unit are disclosed. A fuel cell converts combustible fuel into electrical power during a normal operational period after an initial start-up period when little to no electrical energy is produced. One combustion chamber receives unspent fuel emitted by the fuel cell and combusts the unspent fuel to generate a first heated gas stream. Another combustion chamber receives combustible fuel and burns the combustible fuel to generate a second heated gas stream during the initial start-up period. A turbine receives and is driven by the first and second heated gas streams to drive a drive shaft. A generator coupled to the drive shaft generates electrical power during the initial start-up period and supplemental power during the normal operational period. In an alternative embodiment, a two-stage combustion chamber is used instead of two serially-arranged separate combustion chambers.

Abstract: A fan assembly for an electrical device which comprises a number of heat generating electrical components mounted in an enclosure that includes a front wall, a rear wall and two generally parallel sidewalls. The fan assembly comprises a plurality of fans which are arranged in a row that extends generally perpendicularly between the sidewalls. Each fan comprises an axis of rotation which is oriented at an angle relative to the sidewalls, and the fan assembly further includes a plurality of inlet plenums which each communicate with an inlet end of a corresponding fan and a plurality of exhaust plenums which each communicate with an outlet end of a corresponding fan. In operation, the fans generate an airflow which is distributed through the enclosure by the inlet and exhaust plenums to thereby cool the electrical components.

Abstract: Systems and methods provide for the thermal management of a high temperature fuel cell. According to embodiments described herein, a non-reactant coolant is routed into a fuel cell from a compressor or a ram air source. The non-reactant coolant absorbs waste heat from the electrochemical reaction within the fuel cell. The heated coolant is discharged from the fuel cell and is vented to the surrounding environment or directed through a turbine. The energy recouped from the heated coolant by the turbine may be used to drive the compressor or a generator to create additional electricity and increase the efficiency of the fuel cell system. A portion of the heated coolant may be recycled into the non-reactant coolant entering the fuel cell to prevent thermal shock of the fuel cell.

Abstract: Systems and methods provide for the thermal management of a high temperature fuel cell. According to embodiments described herein, a non-reactant coolant is routed into a fuel cell from a compressor or a ram air source. The non-reactant coolant absorbs waste heat from the electrochemical reaction within the fuel cell. The heated coolant is discharged from the fuel cell and is vented to the surrounding environment or directed through a turbine. The energy recouped from the heated coolant by the turbine may be used to drive the compressor or a generator to create additional electricity and increase the efficiency of the fuel cell system. A portion of the heated coolant may be recycled into the non-reactant coolant entering the fuel cell to prevent thermal shock of the fuel cell.

Abstract: A fan comprises a fan housing which includes a fan inlet, a motor which is connected to the fan housing, and an impeller which is removably connected to the motor. The impeller includes an impeller hub, a number of impeller blades which extend radially outwardly from the impeller hub, an impeller leading edge, an impeller trailing edge and an impeller tip. The fan housing includes an inlet shroud which is positioned over the impeller. The inlet shroud comprises an upstream end portion within which the fan inlet is formed and a downstream end portion which is removably connected to a separate portion of the fan housing. The inlet shroud further includes a first section which extends axially from the upstream end portion to approximately the impeller leading edge, a second section which extends axially from the first section to approximately the impeller trailing edge, and a third section which extends axially from the second section to approximately the downstream end portion.

Abstract: A fan assembly for an electrical device which comprises a number of heat generating electrical components mounted in an enclosure that includes a front wall, a rear wall and two generally parallel sidewalls. The fan assembly comprises a plurality of fans which are arranged in a row that extends generally perpendicularly between the sidewalls. Each fan comprises an axis of rotation which is oriented at an angle relative to the sidewalls, and the fan assembly further includes a plurality of inlet plenums which each communicate with an inlet end of a corresponding fan and a plurality of exhaust plenums which each communicate with an outlet end of a corresponding fan. In operation, the fans generate an airflow which is distributed through the enclosure by the inlet and exhaust plenums to thereby cool the electrical components.

Abstract: A cooling fan includes an impeller which comprises a plurality of radially extending blades, each of which includes a blade hub, a blade tip and a blade midspan approximately midway between the hub and the tip. In addition, each blade includes a camber of between about 60° and 90° at the blade hub, between about 15° and 40° at the blade midspan and between about 15° and 40° at the blade tip.

Abstract: A cooling fan having a fan housing, a motor which is positioned within the fan housing and a plurality of electronics components which are associated with the motor includes at least one strut which extends radially between the motor and the fan housing and on which the electronics components are mounted.

Abstract: Apparatus, systems, and methods provide for the management of a high temperature electrolysis process. According to embodiments described herein, a fuel cell electrolyzer stack is utilized in an electrolysis process. One implementation includes the use of a solid oxide electrolyzer. Input voltage is cycled around a thermal neutral voltage such that the fuel cell electrolyzer stack cycles between operation in an exothermic mode and an endothermic mode. The waste heat generated by operation in the exothermic mode is used to support the endothermic operation. By cycling between operation modes, the temperature of the fuel cell electrolyzer stack may be controlled without the use of a cooling loop or recirculated reactant flow, and the efficiency of the electrolysis process is maximized.

Abstract: A cooling fan comprises an impeller which includes a plurality of radially extending blades, each of which includes a blade hub, a blade tip and a blade midspan approximately midway between the hub and the tip. In addition, each blade comprises a blade suction surface, and substantially the entire blade suction surface is visible from the forward looking aft direction.