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

Abstract: 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.

Abstract: 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.

Abstract: A piston apparatus includes a plurality of piston assemblies respectively having a first piston body and a first piston disposed within a first volume defined by the first piston body, a second piston body and a second piston disposed within a second volume defined by the second piston body, and a connection member coupled to the first piston and the second piston. The first and second volume respectively include an expansion chamber and a compression chamber defined by opposite sides of the corresponding piston. The respective expansion chambers fluidly communicate with a corresponding compression chamber of another one of the piston assemblies. The first volume of a first piston assembly fluidly communicates with the first volume and the second volume of a second piston assembly, and the first volume of a third piston assembly fluidly communicate with the first volume and the second volume of the second piston assembly.

Abstract: 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.

Abstract: 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.

Abstract: A piston apparatus may include a plurality of piston assemblies respectively having a first piston body and a first piston disposed within a first volume defined by the first piston body, a second piston body and a second piston disposed within a second volume defined by the second piston body, and a connection member coupled to the first piston and the second piston. The first and second volume may respectively include an expansion chamber and a compression chamber defined by opposite sides of the corresponding piston. The respective expansion chambers may fluidly communicate with a corresponding compression chamber of another one of the piston assemblies. The first volume of a first piston assembly may fluidly communicate with the first volume and the second volume of a second piston assembly, and the first volume of a third piston assembly may fluidly communicate with the first volume and the second volume of the second piston assembly.

Abstract: 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.

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

Abstract: A system for energy conversion including a closed cycle engine containing a volume of working fluid is provided. The engine includes a double-ended piston assembly including a pair of pistons coupled to a connection member. An expansion chamber is separated from a compression chamber by the piston. The engine defines an outer end and an inner end relative to a lateral extension of the piston assembly. A heater body is positioned thermally proximal to the expansion chamber and thermally distal to the compression chamber, and the heater body is positioned at the outer end of the engine. A load device is operably coupled to the piston assembly at the inner end of the engine. The load device is positioned between the pair of pistons of the piston assembly.

Abstract: A system for energy conversion, the system including a closed cycle engine containing a volume of working fluid, the engine comprising a first chamber defining an expansion chamber and a second chamber defining a compression chamber each separated by a piston attached to a connection member of a piston assembly, and wherein the engine comprises a heater body in thermal communication with the first chamber, and further wherein the engine comprises a cold side heat exchanger in thermal communication with the second chamber, and wherein a third chamber is defined within the piston, wherein the third chamber is in selective flow communication with the first chamber, the second chamber, or both.

Abstract: 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.

Abstract: Systems and methods for converting energy are provided. In one aspect, the system includes a closed cycle engine having a piston body and a piston assembly movable within the piston body. An electric machine is operatively coupled with the piston assembly and operable to generate electrical power. An electrical device is in communication with the electric machine. The system includes a control system having sensors, a controllable device, and a controller. The controller is configured to determine whether a load change on the electric machine is anticipated based at least in part on received data indicative of a load state of the electrical device; in response to whether the load change is anticipated, determine a control command for adjusting an output of at least one of the engine and the electric machine; and cause the controllable device to adjust the output based at least in part on the control command.

Abstract: A piston apparatus may include a plurality of piston assemblies respectively having a first piston body and a first piston disposed within a first volume defined by the first piston body, a second piston body and a second piston disposed within a second volume defined by the second piston body, and a connection member coupled to the first piston and the second piston. The first and second volume may respectively include an expansion chamber and a compression chamber defined by opposite sides of the corresponding piston. The respective expansion chambers may fluidly communicate with a corresponding compression chamber of another one of the piston assemblies. The first volume of a first piston assembly may fluidly communicate with the first volume and the second volume of a second piston assembly, and the first volume of a third piston assembly may fluidly communicate with the first volume and the second volume of the second piston assembly.

Abstract: An energy conversion apparatus may include an engine assembly, such as a monolithic engine assembly, that includes a first heater body and a first engine body. The first heater body may define a first portion of a first monolithic body or at least a portion of a first monolithic body-segment. The first engine body may define a second portion of the first monolithic body or at least a portion of a second monolithic body-segment operably coupled or operably couplable to the first heater body. The engine assembly may include a second heater body and/or a second engine body. The second heater body may define a portion of a second monolithic body or a third monolithic body-segment. The second engine body may define a portion of the second monolithic body or a fourth monolithic body-segment operably coupled or operably couplable to the second heater body and/or the first engine body.

Abstract: Systems and methods for converting energy are provided. In one aspect, the system includes a closed cycle engine defining a cold side. The system also includes a bottoming-cycle loop. A pump is operable to move a working fluid along the bottoming-cycle loop. A cold side heat exchanger is positioned along the bottoming-cycle loop in a heat exchange relationship with the cold side of the closed cycle engine. A constant density heat exchanger is positioned along the bottoming-cycle loop downstream of the cold side heat exchanger and upstream of an expansion device. The constant density heat exchanger is operable to hold a volume of the working fluid flowing therethrough at constant density while increasing, via a heat source, the temperature and pressure of the working fluid. The expansion device receives the working fluid at elevated temperature and pressure and extracts thermal energy from the working fluid to produce work.

Abstract: 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.

Abstract: 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.

Abstract: An engine apparatus, in which each piston assembly includes a piston attached to a connection member at a first end and a second end. Each piston of the piston assembly defines a first chamber and a second chamber separated by the piston. The first chamber and the second chamber are each defined at the first end and at the second end. Each first chamber of one piston assembly is fluidly connected to the second chamber at a different piston assembly. At least one first chamber at the first end is fluidly connected to a respective second chamber at the second end. At least one first chamber at the second end is fluidly connected to a respective second chamber at the first end.

Abstract: A monolithic combustor body may provide multi-stage combustion. A combustor body may include a combustion chamber body and a plurality of heating walls that include a heat sink. The combustion chamber body may be disposed annularly about a longitudinal axis and defining a combustion chamber. The plurality of heating walls may include heat sink. The plurality of heating walls may occupy a radially or concentrically outward position relative to the combustion chamber and may define a corresponding plurality of combustion-gas pathways fluidly communicating with at least a proximal portion of the combustion chamber.