The single working-medium vapor combined cycle and the vapor power device for combined cycle is provided in this invitation and belongs to the field of energy and power technology. The condenser connects the mixing evaporator by a condensate pipeline via the circulating pump and the preheater, the expander connects the mixing evaporator by a vapor channel via the middle-temperature evaporator, the mixing evaporator connects the compressor and the second expander by a vapor channel, the compressor connects the expander by a vapor channel via the high-temperature heat exchanger, the second expander connects the condenser by a vapor channel; the condenser connects the middle-temperature evaporator by a condensate pipeline via the second circulating pump and a second preheater, the middle-temperature evaporator connects the third expander and the condenser by a vapor channel; the high-temperature heat exchanger, the middle-temperature evaporator, the mixing evaporator, the preheater and the second preheater connects the external part by a working-medium channel of the heat source, the expander connects the compressor and transfers power, the expander, the second expander and the third expander connects the external part and output power, in summary, these above-mentioned equipment and pipelines build up the vapor power device for combined cycle.

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 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.

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 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.

Provided is an electric power generating system which exhibits favorable energy recovery efficiency compared to the prior art and, further, can generate not only cold heat but also warm heat. In an electric power generating system where working fluid is circulated in a system of a pressure resistant closed circuit while changing a state of the working fluid, power is generated by converting external heat energy given to the working fluid into kinetic energy, and electric power is generated by driving an electric power generator by the power, a pressure resistant closed circuit is formed of a main circuit and a sub circuit, the main circuit includes an evaporation chamber, an adiabatic expansion chamber, a power generating part, a warming-use heat exchange mechanism, and a liquefied working fluid return means, and the sub circuit includes a heating medium divided flow path, a liquefied auxiliary fluid supply path, a cooling equipment, a second-fluid-to-be-warmed supply path, a warming equipment, and a return flow compression means.

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 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.

The present disclosure provides pumped thermal energy storage systems that can be used to store and extract electrical energy. A pumped thermal energy storage system of the present disclosure can store energy by operating as a heat pump or refrigerator, whereby net work input can be used to transfer heat from the cold side to the hot side. A working fluid of the system is capable of efficient heat exchange with heat storage fluids on a hot side of the system and on a cold side of the system. The system can extract energy by operating as a heat engine transferring heat from the hot side to the cold side, which can result in net work output.

The present disclosure provides pumped thermal energy storage systems that can be used to store and extract electrical energy. A pumped thermal energy storage system of the present disclosure can store energy by operating as a heat pump or refrigerator, whereby net work input can be used to transfer heat from the cold side to the hot side. A working fluid of the system is capable of efficient heat exchange with heat storage fluids on a hot side of the system and on a cold side of the system. The system can extract energy by operating as a heat engine transferring heat from the hot side to the cold side, which can result in net work output.

Efficient energy storage is provided by using a working fluid flowing in a closed cycle including a ganged compressor and turbine, and capable of efficient heat exchange with heat storage fluids on a hot side of the system and on a cold side of the system. This system can operate as a heat engine by transferring heat from the hot side to the cold side to mechanically drive the turbine. The system can also operate as a refrigerator by mechanically driving the compressor to transfer heat from the cold side to the hot side. Heat exchange between the working fluid of the system and the heat storage fluids occurs in counter-flow heat exchangers. In a preferred approach, molten salt is the hot side heat storage fluid and water is the cold side heat storage fluid.

Provided is an electric power generating system which exhibits favorable energy recovery efficiency compared to the prior art and, further, can generate not only cold heat but also warm heat. In an electric power generating system where working fluid is circulated in a system of a pressure resistant closed circuit while changing a state of the working fluid, power is generated by converting external heat energy given to the working fluid into kinetic energy, and electric power is generated by driving an electric power generator by the power, a pressure resistant closed circuit is formed of a main circuit and a sub circuit, the main circuit includes an evaporation chamber, an adiabatic expansion chamber, a power generating part, a warming-use heat exchange mechanism, and a liquefied working fluid return means, and the sub circuit includes a heating medium divided flow path, a liquefied auxiliary fluid supply path, a cooling equipment, a second-fluid-to-be-warmed supply path, a warming equipment, and a return flow compression means.

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.