A monolithic heat exchanger body includes a plurality of heating walls and a plurality of combustion fins. The plurality of heating walls are configured and arranged in an array of spirals or spiral arcs relative to a longitudinal axis. Adjacent portions of the plurality of heating walls respectively define a corresponding plurality of heating fluid pathways therebetween. The plurality of combustion fins are circumferentially spaced about a perimeter of an inlet plenum. The inlet plenum includes or fluidly communicates with a combustion chamber. The plurality of heating fluid pathways fluidly communicate with the inlet plenum. The plurality of combustion fins occupy a radially or concentrically inward portion of the monolithic heat exchanger body. The plurality of heating fluid pathways have a heat transfer relationship with a heat sink disposed about a radially or concentrically outward portion of the monolithic heat exchanger body. A plurality of conduction breaks disposed radially or concentrically outward relative to the plurality of combustion fins at least partially inhibit heat conduction from the plurality of combustion fins to the plurality of heating walls.

An engine utilizing multiple closed loop heat exchangers. The engine makes use of a first exchanger dedicated to a given chamber of a piston assembly. This exchanger is configured to provide both heating and cooling to the chamber for changing the volume thereof in stroking the piston. The second exchanger is configured similarly to provide both heating and cooling to another chamber at the opposite side of the piston for correspondingly facilitating a change in its volume as the piston is stroked. This unique configuration allows for the working substance in the chambers, generally an operating CO.sub.2 fluid, to effectively remain in a supercritical state for the substantial duration of the thermal cycle.

A cooling device implementing a stirling-type thermodynamic cycle includes a compressor with a reciprocating piston driven by an electric motor rotating about an axis via a crankshaft. The electric motor comprises an internal stator and an external rotor and is connected to the crankshaft via a link with at least one degree of freedom in rotation about the axis of the electric motor.

A cooling device employing a thermodynamic cycle of the reverse stirling cycle type is provided. The device includes a compressor with a reciprocating piston driven by a rotary motor about an axis by means of a crankshaft. The device further comprises a monobloc support forming a cylinder in which the piston of the compressor moves. The crankshaft is supported by a single bearing. The bearing is positioned without an intermediate component in a housing of the monobloc support.

The price per performance advantages of double-acting Stirling engines have long been known, and recent experiments have demonstrated the performance and behavior advantages of Stirling engines which involve optimal parameters, such as an optimal phase angle between the pistons. Herein disclosed are new Stirling engine designs which permit both of these advantages to be achieved at once, as well as other benefits such as compactness, simplicity, reliability and lower cost.

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.

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.

A constant density heat exchanger and method of operating are 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 plate is positioned at the first end of the housing and rotatable about an axis of rotation such that the first plate selectively allows a working fluid to flow into the inlet of the chamber. A second plate is positioned at the second end of the housing and rotatable about the axis of rotation such that the second plate selectively allows the working fluid to flow out of the outlet of the chamber. The first plate and the second plate are rotatable about the axis of rotation so as to hold a volume of the working fluid at constant density as a heat source imparts thermal energy thereto.

A double acting, miller cycle, reciprocating piston with dual rotary displacer, stirling engine is provided. Configurable as a heat pump, a heat engine, or as a combination with one side driving the other, the engine is completely closed, sealed and pressurized with the piston ring as the only internal seal. A miller cycle is created by allowing transfer of the working fluid (typically hydrogen gas) past the piston to balance working fluid pressure only at the extremes of the piston stroke. Two coordinated rotating displacers service opposite sides of one piston. Each displacer manages heat flow, according it its length and shape, through one side of the length of its encasing tube into and out of the working fluid through the other side of the length of its encasing tube. The dead space between the piston and the displacer holds regenerator material.

free-piston engine power plant incorporating a first combustion cylinder having a first combustion piston, a fluid expander having an expansion cylinder with an expander piston therein, the expander piston reciprocating in unison with the first combustion piston, a bottoming cycle having a working fluid and a heat exchanger.