A facility for generating mechanical energy by means of a combined power cycle is disclosed herein, which includes at least means for carrying out a closed or semi-closed, constituent regenerative Brayton cycle, which uses water as a heat-transfer fluid, means for carrying out at least one Rankine cycle, a constituent fundamental Rankine cycle, interconnected with the regenerative Brayton cycle, and a heat pump (UAX) including a closed circuit that regenerates the constituent regenerative Brayton cycle, as well as to the method for generating energy using the facility.

Several innovative technologies, including pressure-drop minimization, advanced refractory high entropy alloys, and advanced manufacturing can provide a compact heat exchanger that extends the state-of-the-art heat-exchanger operating range. The compact heat exchanger can reduce pressure drop losses by 100 to 500%, while retaining most of the heat transfer. The compact heat exchanger can be fabricated from refractory high entropy alloys that have favorable corrosion, thermal fatigue, and creep properties at high temperatures and pressures. Therefore, the compact heat exchanger using high entropy alloys can operate at >800° C. and 80 bars.

A heat exchanger has: a first manifold assembly having a stack of plates; a second manifold assembly having a stack of plates; and a plurality of tubes extending from the first manifold assembly to the second manifold assembly. The plurality of tubes is a plurality groups of tubes. For each of the groups of the tubes: the tubes of the group have first ends mounted between plates of the first manifold assembly; and the tubes of the group have second ends mounted between plates of the second manifold assembly.

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 heat exchanger includes a shell housing a plurality of tubes and defining an exhaust fluid flow path within a first volume enclosed by the shell. The outer surfaces of the plurality of tubes are in fluid communication with the exhaust fluid flow path. The heat exchanger includes a cap attached to a first end of the shell and defining a second volume. A header is configured to separate the first volume from the second volume, flex with thermal expansion, and define tube inlet and outlet positions. The tube inlets and outlets are in fluid communication with a source fluid flow path, and each tube is substantially U-shaped and defines a flow path of the source fluid within the exhaust fluid flow path. The heat exchanger includes at least one longitudinal flow baffle within the shell configured to reduce an amount of exhaust fluid that may bypass the tubes.

Electrical/mechanical power is derived from oxycombustion of hydrocarbons, preferably LNG, in a first of two nested cycles each operating on a Brayton cycle to provide a source of power, without mixing of working fluids between the two cycles. Each cycle employs CO.sub.2 as a working fluid, the first cycle operating under low pressure conditions in which CO.sub.2 is sub-critical, and the other cycle operating under higher pressure conditions in which CO.sub.2 is supercritical. The first cycle serves as a source of heat for the second cycle by gas/gas heat exchange which cools the products of combustion and circulating working fluid in the first cycle and heats working fluid in the second cycle.

The present disclosure provides a method for generating higher hydrocarbon(s) from a stream comprising compounds with two or more carbon atoms (C.sub.2+), comprising introducing methane and an oxidant (e.g., O.sub.2) into an oxidative coupling of methane (OCM) reactor that has been retrofitted into a system comprising an ethylene-to-liquids (ETL) reactor. The OCM reactor reacts the methane with the oxidant to generate a first product stream comprising the C.sub.2+ compounds. The first product stream can then be directed to a pressure swing adsorption (PSA) unit that recovers at least a portion of the C.sub.2+ compounds from the first product stream to yield a second product stream comprising the at least the portion of the C.sub.2+ compounds. The second product stream can then be directed to the ETL reactor. The higher hydrocarbon(s) can then be generated from the at least the portion of the C.sub.2+ compounds in the ETL reactor.

A system includes a power cycle and a cooling cycle. The power cycle includes a first compressor, a recuperative heat exchanger, a waste-heat heat exchanger, and a turbine. The turbine includes a drive shaft coupled to the first compressor. The working fluid from the waste-heat heat exchanger drives the turbine, the drive shaft, and the first compressor. The recuperative heat exchanger cools the working fluid from the turbine, and at least one ram-air heat exchanger further cools the working fluid from the recuperative heat exchanger. The first compressor is configured to pressurize the working fluid from the at least one ram-air heat exchanger. The cooling cycle includes a pump, an isenthalpic valve, an ambient air heat exchanger, and a second compressor. The cooling cycle cools the working fluid and ambient air and is connected to the power cycle in the at least one ram-air heat exchanger.

A waste heat recovery system, based on a Brayton cycle, comprises a heater configured to circulate carbon dioxide vapor in heat exchange relationship with a hot fluid to heat the carbon dioxide vapor. An expander is coupled to the heater and configured to expand the carbon dioxide vapor. A compressor is configured to compress the carbon dioxide vapor fed through a cooler and a heat exchanger is adapted to circulate the carbon dioxide vapor from the expander to the cooler in heat exchange relationship with the carbon dioxide vapor from the compressor to the heater, wherein the expander and the compressor are mechanically coupled volumetric machines.

The invention relates to a method for operating a power plant (1) for generating electrical energy for delivery to at least one consumer (16) by combustion of a carbonaceous combustible, wherein carbon dioxide (19) is separated from the flue gas (7) of the power plant (1), the separated carbon dioxide (19) is converted at least in part into a fuel (20), characterized in that the fuel (20) is combusted at least temporarily in at least one heat engine (4) so as to form a waste gas (8), and electrical energy is generated by the heat engine (4) and is delivered to at least one consumer (16), at least some of the thermal energy of the waste gas (8) being used in at least one of the following processes: a) for heating combustion air (10) of a power plant (1); b) for heating a process medium (14) of the power plant (1); c) in a drying of the combustible of the power plant (1); and d) in carbon dioxide separation.