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 one aspect of this disclosure, there is provided a fuel system for a gas turbine engine of an aircraft, including a main inlet feed conduit fluidly connected to a primary manifold feed conduit and a secondary manifold feed conduit. A primary manifold fluidly connects the primary manifold feed conduit to a plurality of primary fuel injectors, and a secondary manifold fluidly connects the secondary manifold feed conduit to a plurality of secondary fuel injectors.

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.

Provided herein is a power generation system and method for transforming thermal energy, such as waste heat, into mechanical energy and/or electrical energy. The system employs features designed to accelerate start times, reduce size, lower cost, and be more environmentally friendly. Tire system may include multiple compressors on separate pinion shafts with multiple expanders, a temperature valve upstream of compressors with a mass management system downstream, an intercooler between compressors, and a cascade exchanger. In one embodiment, the system is configured to drive a synchronous generator, with the separate pinion shafts rotating at two separate, but constant, speeds.

Processes, systems, and apparatus are provided for producing a compressed process gas comprising light olefin such as ethylene. The process utilizes a pyrolysis reactor to produce the process gas. A power generator utilizes a turbine operated based on an Allam cycle to produce shaft power for operating one or more compressors involved in processing of the process gas while producing a reduced or minimized amount of CO.sub.2 that is released as a low-pressure gas phase product. Examples of using the shaft power for processing of the process gas can include compressing the process gas a process gas compressor powered by the produced shaft power and cooling the process gas using a refrigeration compressor powered by the produced shaft power.

Processes, systems, and apparatus are provided for producing a compressed process gas comprising light olefin such as ethylene. The process utilizes a pyrolysis reactor to produce the process gas. A power generator utilizes a turbine operated based on an Allam cycle to produce shaft power for operating one or more compressors involved in processing of the process gas while producing a reduced or minimized amount of CO.sub.2 that is released as a low-pressure gas phase product. Examples of using the shaft power for processing of the process gas can include compressing the process gas a process gas compressor powered by the produced shaft power and cooling the process gas using a refrigeration compressor powered by the produced shaft power.

A gas turbine engine includes a primary gas path having, in fluid series communication: a primary air inlet, a compressor fluidly connected to the primary air inlet, a combustor fluidly connected to an outlet of the compressor, and a turbine fluidly connected to an outlet of the combustor. The turbine is operatively connected to the compressor to drive the compressor. A turbine cooling air conduit extends from an air inlet of the turbine cooling air conduit to an air outlet of the turbine cooling air conduit.

A process for storing large amounts of energy underground in existing or artificial aquifers at very large scale using deep-water, high-pressure electrolysis. The process is intended for use as large scale storage for electrical power grids. When implemented at depths greater than roughly 500 m, it provides stored energy density equal to or greater than lead-acid batteries while requiring only a pressure vessel. If the geologic structure is appropriate, the vessel may already exist naturally.

Because this process does not require compression of the gas(es), when the gas(es) is expanded it become quite cold and therefore extracts heat from the atmosphere. When combined with a sustainable energy source such as wind, solar, ocean or other similar source—the entire process is endothermic. The cold gas(es) can also be used to precipitate CO.sub.2 and condense CH.sub.4 directly from the atmosphere. This means the combination of these processes removes heat and carbon from the environment at the same time they provide large scale, lower cost grid energy storage.