A constant density heat exchanger and system for energy conversion is provided. The constant density heat exchanger includes a housing extending between a first end and a second end and defining a chamber having an inlet and an outlet. A first flow control device is positioned at the inlet of the chamber and movable between an open position in which a working fluid is permitted into the chamber and a closed position in which the working fluid is prevented from entering the chamber. A second flow control device is positioned at the outlet of the chamber and movable between an open position in which the working fluid is permitted to exit the chamber and a closed position in which the working fluid is prevented from exiting the chamber. A heat exchange fluid imparts thermal energy to the volume of working fluid as the first flow control device and the second flow control device hold the volume of working fluid at constant density within the chamber.

The invention relates to a liquid air energy storage system. The storage system includes a cryocooler, a dewar, and a Sterling engine. The cryocooler cools a tip of a cold head to cryogenic temperatures, the cryocooler further includes a heat sink to reject heat from the cryocooler and a cold head that protrudes into a dewar through a cryocooler cavity, the cold head to condense ambient air to create liquified air in the dewar. The dewar holds the liquified air at low temperatures, the dewar having the cryocooler cavity and a Stirling cavity. The Stirling engine drives an electric generator, the Stirling engine further including a cold finger protruding into the dewar through the Stirling cavity, the cold finger to move the liquified air from the dewar to a Stirling heat sink; the Stirling heat sink to expand the liquified air; and the electric generator to generate output electricity.

A constant density heat exchanger is provided. The constant density heat exchanger includes a housing extending between a first end and a second end and defining a chamber having an inlet and an outlet. A first flow control device is positioned at the inlet of the chamber and movable between an open position in which a working fluid is permitted into the chamber and a closed position in which the working fluid is prevented from entering the chamber. A second flow control device is positioned at the outlet of the chamber and movable between an open position in which the working fluid is permitted to exit the chamber and a closed position in which the working fluid is prevented from exiting the chamber. A heat exchange fluid imparts thermal energy to the volume of working fluid held at constant density within the chamber by the first and second control devices.

An energy conversion apparatus may include an engine assembly, such as a monolithic engine assembly. The engine assembly may include a first monolithic body segment and a plurality of second monolithic body segments directly coupled or directly couplable to the first monolithic body segment. The first monolithic body segment may define a combustion chamber and a recirculation pathway in fluid communication with the combustion chamber. The recirculation pathway may be configured to recirculate combustion gas through the combustion chamber. The plurality of second monolithic body segments may respectively define at least a portion of a piston chamber and a plurality of working-fluid pathways fluidly communicating with the piston chamber.

A Stirling engine can take advantage of adiabatic compression (which heats working gas leaving the cold cylinder) and adiabatic expansion (which cools working gas leaving the hot cylinder) to increase efficiency. In some implementations, partially-heated gas leaving the cold cylinder and partially-cooled gas leaving the hot cylinder can be routed directly to a regenerator using bypass paths that are opened using one-way valves. The resultant relatively reduced temperature difference across the regenerator, e.g., as compared to a typical Stirling engine, can reduce thermal loss and improve efficiency. In some implementations, the compression ratios of the Stirling engine can be adjusted such that the temperature of the adiabatic heated gas is the same or higher than the temperature of the adiabatic cooled temperatures, thus eliminating the need for a regenerator.

The invention relates to a liquid air energy storage system. The storage system includes a cryocooler, a dewar, and a Sterling engine. The cryocooler cools a tip of a cold head to cryogenic temperatures, the cryocooler further includes a heat sink to reject heat from the cryocooler and a cold head that protrudes into a dewar through a cryocooler cavity, the cold head to condense ambient air to create liquified air in the dewar. The dewar holds the liquified air at low temperatures, the dewar having the cryocooler cavity and a Stirling cavity. The Stirling engine drives an electric generator, the Stirling engine further including a cold finger protruding into the dewar through the Stirling cavity, the cold finger to move the liquified air from the dewar to a Stirling heat sink; the Stirling heat sink to expand the liquified air; and the electric generator to generate output electricity.

An engine body may include a piston body comprising a piston chamber and a regenerator body comprising a regenerator conduit. An engine body may include a working-fluid heat exchanger body comprising a plurality of working-fluid pathways fluidly communicating between the piston chamber and the regenerator conduit. Additionally, or alternatively, an engine body may include a heater body comprising a plurality of heating fluid pathways and the plurality of working-fluid pathways. The heating fluid pathways may have a heat transfer relationship with the working fluid pathways. The working-fluid pathways may fluidly communicate between the piston chamber and the regenerator conduit. The engine body may include a monolithic body defined at least in part by the piston body, the regenerator body, and the working-fluid heat exchanger body, and/or defined at least in part by the piston body, the regenerator body, and the heater body.

A constant density heat exchanger and system for energy conversion is provided. The constant density heat exchanger includes a housing extending between a first end and a second end and defining a chamber having an inlet and an outlet. A first flow control device is positioned at the inlet of the chamber and movable between an open position in which a working fluid is permitted into the chamber and a closed position in which the working fluid is prevented from entering the chamber. A second flow control device is positioned at the outlet of the chamber and movable between an open position in which the working fluid is permitted to exit the chamber and a closed position in which the working fluid is prevented from exiting the chamber. A heat exchange fluid imparts thermal energy to the volume of working fluid as the first flow control device and the second flow control device hold the volume of working fluid at constant density within the chamber.

A monolithic heat exchanger body for inputting heat to a closed-cycle engine may include a plurality of heating walls and heat sink, such as a plurality of heat transfer regions. The plurality of heating walls may be configured and arranged in an array of spirals or spiral arcs relative to a longitudinal axis of an inlet plenum. Adjacent portions of the plurality of heating walls may respectively define a corresponding plurality of heating fluid pathways therebetween, for example, fluidly communicating with the inlet plenum. At least a portion of the heat sink may be disposed about at least a portion of the monolithic heat exchanger body. The heat sink may include a plurality of working-fluid bodies, for example, including a plurality of working-fluid pathways that have a heat transfer relationship with the plurality of heating fluid pathways. Respective ones of the plurality of heat transfer regions may have a heat transfer relationship with a corresponding semiannular portion of the plurality of heating fluid pathways. Respective ones of the plurality of heat transfer regions may include a plurality of working-fluid pathways fluidly communicating between a heat input region and a heat extraction region.

An engine body may include a piston body comprising a piston chamber and a regenerator body comprising a regenerator conduit. An engine body may include a working-fluid heat exchanger body comprising a plurality of working-fluid pathways fluidly communicating between the piston chamber and the regenerator conduit. Additionally, or alternatively, an engine body may include a heater body comprising a plurality of heating fluid pathways and the plurality of working-fluid pathways. The heating fluid pathways may have a heat transfer relationship with the working fluid pathways. The working-fluid pathways may fluidly communicate between the piston chamber and the regenerator conduit. The engine body may include a monolithic body defined at least in part by the piston body, the regenerator body, and the working-fluid heat exchanger body, and/or defined at least in part by the piston body, the regenerator body, and the heater body.