A gas turbine engine includes a primary flowpath fluidly connecting a compressor section, a combustor section, and a turbine section. A heat exchanger is disposed in the primary flowpath downstream of the turbine section. The heat exchanger includes a first inlet for receiving fluid from the primary flowpath and a first outlet for expelling fluid received at the first inlet. The heat exchanger further includes a second inlet fluidly connected to a supercharged CO2 (sCO2) bottoming cycle and a second outlet connected to the sCO2 bottoming cycle. The sCO2 bottoming cycle is an overexpanded, recuperated Brayton cycle.

Supercritical fluid systems and aircraft power systems are described. The systems include a compressor, a turbine operably coupled to the compressor, a generator operably coupled to the turbine and configured to generate power, a primary working fluid flow path having a primary working fluid configured to pass through the compressor, a separator, the turbine, and back to the compressor, and a secondary working fluid flow path passing through the generator, the compressor, the separator, and back to the generator. The primary working fluid is supercritical carbon dioxide (sCO.sub.2) and the secondary working fluid is a fluid having at least one of a density less than the primary working fluid and a molecular size smaller than the primary working fluid.

An emission-free power generation system includes a combustion chamber having a first inlet for receiving a fuel and a closed-loop fluidic circuit fluidly connected between a second inlet of the combustion chamber and an outlet of the combustion chamber. Combustion gases from the combustion chamber include only water and carbon dioxide, and the fuel includes performic acid or a combination of formic acid and hydrogen peroxide.

The present disclosure relates to systems and methods useful for power production. In particular, a power production cycle utilizing CO.sub.2 as a working fluid may be combined with a second cycle wherein a compressed CO.sub.2 stream from the power production cycle can be heated and expanded to produce additional power and to provide additional heating to the power production cycle.

A system includes a rotary liquid piston compressor configured to exchange pressure between a liquid and a supercritical fluid. The rotary liquid piston compressor includes a rotor configured to exchange pressure between the liquid and the supercritical fluid as the rotor rotates. The rotor defines channels that extend through the rotor. The rotary liquid piston compressor further includes barriers configured to block mixing between the liquid and the supercritical fluid. The barriers rest within the rotor. Each channel of the channels is configured to receive a barrier of the barriers.

A system method of geothermal energy recovery includes injecting carbon dioxide into a geothermal reservoir through an injection well, extracting a working fluid including previously injected carbon dioxide and hydrocarbons entrained in a flow of the carbon dioxide within the reservoir from an extraction well, separating components of the heated working fluid based on chemical composition, selectively mixing the separated components according to the current conditions of the extracted working fluid to produce an output modified working fluid that having a chemical composition that is optimized for energy recovery efficiency, and expanding the modified working fluid to generate mechanical or electrical energy.

Aircraft power plants including combustion engines, and associated methods for recuperating waste heat from such aircraft power plants are described. A method includes transferring the heat rejected by the internal combustion engine to supercritical CO.sub.2 (sCO.sub.2) used as a working fluid in a heat engine. The heat engine converts at least some the heat transferred to the sCO.sub.2 to mechanical energy to perform useful work onboard the aircraft.

A hybrid powerplant can include a fuel cell cycle system configured to generate a first power using a fuel and an oxidizer. The powerplant can also include a supercritical carbon dioxide (sCO.sub.2) cycle system operatively connected to the fuel cell cycle to receive heat from the fuel cell cycle to cause the sCO.sub.2 cycle system to generate a second power.

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.

Direct-fired supercritical carbon dioxide (CO.sub.2) power cycle that generates hydrogen. More specifically, the discharge of a direct fired supercritical CO.sub.2 power cycle is converted to carbon dioxide and hydrogen where the hydrogen and/or carbon dioxide can be separated and stored/utilized in another application.