A process for reducing pressure of a vapor stream used for reducing a temperature or pressure in a reactor. A pressure of a vapor stream is reduced with a turbine to provide a lower pressure vapor stream. The vapor stream rotates a turbine wheel within the turbine. The turbine wheel is configured to transmit rotational movement to an electrical generator. Thus, electricity is generated with the turbine. The lower pressure vapor stream is injected into a reactor and reduces a temperature in the reactor or reduces a partial pressure of a hydrocarbon vapor in the reactor.

A process for reducing pressure of a vapor stream used for reducing a temperature or pressure in a reactor. A pressure of a vapor stream is reduced with a turbine to provide a lower pressure vapor stream. The vapor stream rotates a turbine wheel within the turbine. The turbine wheel is configured to transmit rotational movement to an electrical generator. Thus, electricity is generated with the turbine. The lower pressure vapor stream is injected into a reactor and reduces a temperature in the reactor or reduces a partial pressure of a hydrocarbon vapor in the reactor.

A power generation system for a nuclear reactor includes an externally-heated turbine engine, a reactor heat exchanger, and a heat recuperating system. The externally-heated turbine engine produces compressed air that is heated by the reactor heat exchanger. The heat recuperating system includes a heat exchanger thermally connected to the externally-heated turbine engine to transfer heat to the compressed air to supplement the reactor heat exchanger.

A power generation system for a nuclear reactor includes an externally-heated turbine engine, a reactor heat exchanger, and a heat recuperating system. The externally-heated turbine engine produces compressed air that is heated by the reactor heat exchanger. The heat recuperating system includes a heat exchanger thermally connected to the externally-heated turbine engine to transfer heat to the compressed air to supplement the reactor heat exchanger.

Systems and methods for variable pressure inventory control of a closed thermodynamic cycle power generation system or energy storage system, such as a reversible Brayton cycle system, with at least a high pressure tank and an intermediate pressure tank are disclosed. Operational parameters of the system such as working fluid pressure, turbine torque, turbine RPM, generator torque, generator RPM, and current, voltage, phase, frequency, and/or quantity of electrical power generated and/or distributed by the generator may be the basis for controlling a quantity of working fluid that circulates through a closed cycle fluid path of the system.

Systems and methods for variable pressure inventory control of a closed thermodynamic cycle power generation system or energy storage system, such as a reversible Brayton cycle system, with at least a high pressure tank and an intermediate pressure tank are disclosed. Operational parameters of the system such as working fluid pressure, turbine torque, turbine RPM, generator torque, generator RPM, and current, voltage, phase, frequency, and/or quantity of electrical power generated and/or distributed by the generator may be the basis for controlling a quantity of working fluid that circulates through a closed cycle fluid path of the system.

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.

The present disclosure relates to systems and methods wherein a dilute hydrocarbon stream can be oxidized to impart added energy to a power production system. The oxidation can be carried out without substantial combustion of the hydrocarbons. In this manner, dilute hydrocarbon streams that would otherwise be required to undergo costly separation processes can be efficiently utilized for improving the power production system and method. Such systems and methods particularly can utilize dilute hydrocarbon stream including a significant amount of carbon dioxide, such as may be produced in hydrocarbon recovery process, such as enhanced oil recovery or conventional hydrocarbon recovery processes.

This invention presents a method for conversion of heat to electrical power through absorption of heat from any types of fluids with temperatures both higher and lower than 0° C. Heat can be absorbed from fossil or renewable energy resources. The mechanism in this invention uses fluid internal energy and enthalpy difference to generate power, where a reciprocating piston-cylinder system provides the required force to rotate a turbine for power generation.

Inventive concentrated solar power systems using solar receivers, and related devices and methods, are generally described. Low pressure solar receivers are provided that function to convert solar radiation energy to thermal energy of a working fluid, e.g., a working fluid of a power generation or thermal storage system. In some embodiments, low pressure solar receivers are provided herein that are useful in conjunction with gas turbine based power generation systems.