In accordance with at least on aspect of this disclosure, there is provided a hydrogen fuel system for aircraft. The hydrogen fuel system includes a gas turbine engine and a fuel feed conduit. The fuel feed conduit is defined at least in part by, in fluid series, a liquid hydrogen tank fluidly connected to a combustor of the gas turbine engine, a liquid hydrogen pump to drive fuel to the combustor of the gas turbine engine, an evaporator, and an electric heat source in thermal communication with the evaporator to add heat into a flow of hydrogen passing through the evaporator. In embodiments, the electric energy source associated with the electric heat source to power the electric heat source.

In accordance with at least on aspect of this disclosure, there is provided a hydrogen fuel system for aircraft. The hydrogen fuel system includes a gas turbine engine and a fuel feed conduit. The fuel feed conduit is defined at least in part by, in fluid series, a liquid hydrogen tank fluidly connected to a combustor of the gas turbine engine, a liquid hydrogen pump to drive fuel to the combustor of the gas turbine engine, an evaporator, and an electric heat source in thermal communication with the evaporator to add heat into a flow of hydrogen passing through the evaporator. In embodiments, the electric energy source associated with the electric heat source to power the electric heat source.

A fuel oxygen conversion unit for a vehicle or an engine of the vehicle includes a contactor; a mechanically-driven, first fuel gas separator defining a liquid fuel outlet and a stripping gas outlet, the fuel oxygen conversion unit defining a liquid fuel outlet path in fluid communication with the liquid fuel outlet of the first fuel gas separator; and a second fuel gas separator positioned in fluid communication with the liquid fuel outlet path at a location downstream of the first fuel gas separator.

A heat exchanger including a sealed housing and a body positioned inside the housing, the body including a stack of least one first assembly of first and second plates pressed against each other, between which flows a first fluid, and at least one second assembly of third and fourth plates pressed against each other, between which flows a second fluid, the first and second assemblies being arranged so that they transfer heat between the first and second fluids. This configuration limits the risk of leaks and mixing of the two fluids.

An aircraft including a fuselage, a wing structure, at least one turbomachine running on hydrogen and generating thrust at a propulsion unit distant from the fuselage, at least one fuel tank positioned in the fuselage and configured to store hydrogen in the cryogenic state, at least one hydrogen supply device connecting the fuel tank and the turbomachine and including at least one pump positioned in the fuselage in the vicinity of the fuel tank, at least one hydrogen heating system positioned in the fuselage in the vicinity of the pump. This solution makes it possible to reduce a length of the complex double-walled pipes configured for carrying the hydrogen in the cryogenic state between the fuel tank and the hydrogen heating system.

An aircraft including a fuselage, a wing structure, at least one turbomachine running on hydrogen and generating thrust at a propulsion unit distant from the fuselage, at least one fuel tank positioned in the fuselage and configured to store hydrogen in the cryogenic state, at least one hydrogen supply device connecting the fuel tank and the turbomachine and including at least one pump positioned in the fuselage in the vicinity of the fuel tank, at least one hydrogen heating system positioned in the fuselage in the vicinity of the pump. This solution makes it possible to reduce a length of the complex double-walled pipes configured for carrying the hydrogen in the cryogenic state between the fuel tank and the hydrogen heating system.

In accordance with at least one aspect of this disclosure, there is provided a heat exchange system. The heat exchange system includes a first heat exchanger and a second heat exchanger. The first heat exchanger includes an engine fluid conduit fluidly connecting an engine fluid inlet to an engine fluid outlet. A first internal buffer fluid conduit fluidly connects a first buffer fluid inlet to a first buffer fluid outlet where the engine fluid conduit is in fluid isolation from the first internal buffer fluid conduit but is in thermal communication with the first internal buffer fluid conduit for heat exchange between the engine fluid and the buffer fluid.

In accordance with at least one aspect of this disclosure, there is provided a fuel control system for gaseous fuel in an aircraft. The system includes a control module operatively connected to a metering device in a fuel flow conduit, the control module operable to control the flow of fuel through the fuel flow conduit. The control module includes an input line operable to receive a command input indicative of a requested engine state. In embodiments, the control module includes a compressibility logic and machine readable instructions. The machine readable instruction can be configured to cause the control module to control the metering device to achieve the requested engine state based on a compressibility factor input from the compressibility logic.

A gas turbine engine is provided including a turbomachine having a compressor section, a combustion section, and a turbine section arranged in serial flow order; a rotor assembly driven by the turbomachine, the rotor assembly, the turbomachine, or both comprising a substantially annular duct relative to the centerline of the gas turbine engine, the annular duct defining a flowpath; a heat exchanger positioned within the annular duct and extending substantially continuously along the circumferential direction, the heat exchanger comprising a first material defining a heat exchange surface exposed to the flowpath, wherein the first material defines a heat exchange coefficient and wherein the heat exchange surface defines a surface area (A), and wherein the heat exchanger has an effective transmission loss (ETL) of between 5 decibels and 1 decibel for an operating condition.

A method of managing thermal energy in a propulsion system includes diverting a flow of bleed air from a compressor section of the propulsion system. An amount of the flow of bleed air diverted from the compressor section is at least 5% of an inlet flow at an inlet of a high pressure compressor of the compressor section. The flow of bleed air is provided to a thermal management system. The flow of bleed air is passed through an expansion turbine of the thermal management system. The flow of bleed air is provided to a thermal load.