Propulsion systems for aircraft include a fan and a low pressure turbine operably coupled to a first shaft, a low pressure compressor and an intermediate pressure turbine operably coupled to a second shaft, and a high pressure compressor and a high pressure turbine operably coupled to a third shaft. A burner is arranged between the high pressure compressor and the high pressure turbine, with a main flow path defined through the propulsion system. A hydrogen fuel system is configured to supply hydrogen fuel to the burner. A condenser is arranged along the main flow path and configured to extract water from exhaust from the burner. An evaporator is arranged along the main flow path and configured to receive a portion of the water to generate steam which is injected into the main flow path upstream from the evaporator.

A compressed air energy storage system may have an accumulator and a thermal storage subsystem having a cold storage chamber for containing a supply of granular heat transfer, a hot storage chamber and at least a first mixing chamber in the gas flow path and having an interior in which the compressed gas contacts the granular heat transfer particles at a mixing pressure that is greater than the cold storage pressure and the hot storage pressure and a conveying system operable to selectably move the granular heat transfer particles from the cold storage chamber, through the first mixing chamber and into the hot storage chamber, and vice versa.

An integrated hermetically sealed turboexpander-generator comprises a hermetically sealed casing arrangement, a turboexpander, a compressor and an electric generator, arranged in the hermetically sealed casing arrangement along a common shaft line, supported by active magnetic bearings. Also disclosed is a thermodynamic system using the integrated hermetically sealed turboexpander-generator to convert waste heat from a waste heat source into electric power. The electric generator is arranged at one end of the common shaft line.

A gas turbine engine includes a core engine that includes a core flow path that connects a compressor section, combustor section and a turbine section. The gas turbine engine further includes a bottoming cycle system that includes a supercritical CO2 (sCO2) working fluid flow. A first recuperator is disposed in the core flow path downstream of the turbine section, the first recuperator is configured to transfer thermal energy from a core flow aft of the turbine section to the sCO2 working fluid flow. A second recuperator is disposed in the compressor section, the second recuperator is configured to transfer thermal energy from the sCO2 working fluid flow to a location forward of the combustor section.

A gas turbine engine includes a core engine that includes a core flow path where air is compressed in a compressor section, communicated to a combustor section, mixed with an ammonia based fuel and ignited to generate a high energy combusted gas flow that is expanded through a turbine section. The turbine section is mechanically coupled to drive the compressor section. An ammonia flow path communicates an ammonia flow to the combustor section. A cracking device is disposed in the ammonia flow path. The cracking device is configured to decompose the ammonia flow into a fuel flow containing hydrogen (H2). At least one heat exchanger is upstream of the cracking device that provides thermal communication between the ammonia flow and a working fluid flow such that the ammonia fluid flow accepts thermal energy from the working fluid flow.

An aircraft power plant for a fuel cell including a turbo assembly, a compressor assembly, a turbo assembly, a compressor assembly controller, a first stage turbo assembly and compressor assembly operation configured to generate a first stage compressed fluid generated from ambient air and excess oxygen exhausted from a fuel cell of an aircraft power plant. A second stage turbo assembly and compressor assembly operation configured to receive the first stage compressed fluid, and a controller bleed valve coupled with the first stage turbo assembly and compressor assembly and the second stage turbo assembly and compressor assembly. An oxygen supply system, the oxygen supply system fluidically coupled with the first stage turbo assembly and compressor assembly wherein a first compressed oxygen is generated by the first stage turbo assembly is combined with a second compressed oxygen generated by the second stage turbo assembly to generate a combined oxygen controlled by the controller bleed valve. A third stage turbo assembly and compressor assembly operation configured to receive the combined oxygen, and a hydrogen supply system configured to provide hydrogen fluidically coupled with the third stage turbo assembly and compressor assembly.

A turbofan engine includes a fan, a core turbine engine having one or more turbines and an exhaust section, and a hydrogen-exhaust gas heat exchanger in flow communication with the exhaust section and hydrogen flowing along a hydrogen supply line. The hydrogen-exhaust gas heat exchanger defines a load capacity factor determined by raising a product to a one-quarter power, the product being determined by multiplying a heat transfer surface area density associated with the hydrogen-exhaust gas heat exchanger by a process conductance parameter that relates characteristics of hydrogen, ambient air, and exhaust gas at takeoff, as well as a fan diameter of the fan and a number of turbine stages of the turbofan engine. The load capacity factor is between 4.37 and 28.65 for the fan diameter being between 0.5 and 3.5 meters and the heat transfer surface area density being between 500 m.sup.2/m.sup.3 and 10,000 m.sup.2/m.sup.3.

In one aspect of the present disclosure, there is provided a gas turbine engine. The gas turbine engine includes a primary gas path having, in fluid series communication: an air inlet, a compressor fluidly connected to the air inlet, a combustor fluidly connected to an outlet of the compressor, and a turbine section fluidly connected to an outlet of the combustor section. In embodiments, a hydrogen expansion turbine is in fluid communication to receive hydrogen from the gaseous hydrogen outlet of the heat exchanger. In certain embodiments, the gas turbine engine includes a heat exchanger having a gas conduit fluidly connected to the primary gas path, and a fluid conduit in fluid isolation from the gas conduit and in thermal communication with the gas conduit.

Methods and apparatus to operate gas turbines with hydrogen as the combusting fuel are disclosed. An example gas turbine system includes an intercooler disposed between at a fan and at least a portion of a compressor, and at least one conduit to define a flow path to convey fluid, the flow path including a first portion and a second portion, the first portion of the flow path to carry the fluid to or through the intercooler, the second portion of the flow path to carry the fluid at least partially around at least one of a low-pressure turbine or an exhaust section downstream of a combustor.

A propulsion system for an aircraft includes a hydrogen fuel system supplying hydrogen fuel to the combustor through a fuel flow path. A condenser extracts water from an exhaust gas flow and includes a plurality of spiral passages disposed within a collector. The spiraling passages generate a transverse pressure gradient to direct water out of the exhaust gas flow toward the collector.