Systems and methods relating to use of external air for inventory control of a closed thermodynamic cycle system or energy storage system, such as a reversible Brayton cycle system, are disclosed. A method may involve, in a closed cycle system operating in a power generation mode, circulating a working fluid may through a closed cycle fluid path. The closed cycle fluid path may include a high pressure leg and a low pressure leg. The method may further involve in response to a demand for increased power generation, compressing and dehumidifying environmental air. And the method may involve injecting the compressed and dehumidified environmental air into the low pressure leg.

The present invention provides a composition, such as a refrigerant composition comprising 1, 1-difluoroethene (vinylidene fluoride, R-1132a); trifluoromethane (R-23); and one or more compound selected from hexafluoroethane (R-116), ethane (R-170) and carbon dioxide (R-744, CO.sub.2).

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.

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 invention provides a composition, such as a refrigerant composition comprising 1,1-difluoroethene (vinylidene fluoride, R-1132a); trifluoromethane (R-23); and one or more compound selected from hexafluoroethane (R-116), ethane (R-170) and carbon dioxide (R-744, CO.sub.2).

The present disclosure relates to systems and methods for power production utilizing a recirculating working fluid. In particular, a portion of the recirculating working fluid can be separated from the main stream of recirculating working fluid as a bypass stream that can be compressed for adding heat to the system.

Systems, apparatuses, and methods relating to heat transfer devices having nested layers of helical fluid channels. In some examples, a device for transferring heat includes a set of nested tubular walls and a plurality of helical walls intersecting each of the nested tubular walls to form one or more first channel layers nested with one or more second channel layers. Each of the first and second channel layers includes a plurality of helical fluid channels. A first intake and a first outtake are in fluid communication with one another via the plurality of helical fluid channels of each first channel layer, for flow of a first fluid through the device. A second intake and a second outtake are in fluid communication with one another via the plurality of helical fluid channels of each second channel layer, for flow of a second fluid through the device.

The present invention relates to systems and methods for controlling a power production plant and optionally providing a one or more product streams for an end use thereof. Control of a power production plant specifically can include executing one or more functions effective for adjusting a heat profile of a heat exchange unit (HEU) operating with a plurality of streams passing therethrough. This can include implementing a control function that alters a flow of one or more of the plurality of streams by adding flow to or withdrawing flow one or more of the plurality of streams at an intermediate temperature range within the HEU at a point that is positioned between a first end and a second end of the HEU.

In some embodiments the disclosure is directed to a closed-loop piston engine system using a recirculating carbon dioxide (CO.sub.2) system with supercritical carbon dioxide (scCO.sub.2) as a working fluid. The closed-loop piston engine system may include a scCO.sub.2 injector; a superheating nozzle region; a first valve; a second valve; a piston moving in the cylinder and coupled with a crankshaft, the piston being driven toward a centerline of the crankshaft during a power stroke using a connecting rod and causing the crankshaft to rotate thereby causing one power stroke per piston per crankshaft rotation and thereby producing two power strokes for every single power stroke that a similar engine would produce if run as a hydrocarbon fuel powered internal combustion engine. The recirculating CO.sub.2 system recirculates the used carbon dioxide and there are no carbon dioxide emissions from the system.

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.