A monolithic heater body may include a combustor body, a hot-side heat exchanger body, and an eductor body. The combustor body may define a combustion chamber and a conditioning conduit circumferentially surrounding the combustion chamber. The conditioning conduit may fluidly communicate with the combustion chamber at a distal portion of the combustion chamber. The hot-side heat exchanger body may define a hot-side heat exchanger that includes a heating fluid pathway fluidly communicating with a proximal portion of the combustion chamber. The eductor body may define an eduction pathway fluidly communicating with a downstream portion of the heating fluid pathway and a proximal portion of the conditioning conduit.

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.

A system including a closed cycle engine having a piston body defining a hot side and a cold side and having a piston assembly movable within the piston body. An electric machine is operatively coupled with the piston assembly. A control system includes one or more sensors operable to detect a piston movement characteristic of the piston assembly movable within the piston body. A controller is communicatively coupled with the one or more sensors and a controllable device. The controller is configured to determine a control command based at least in part on data received from the one or more sensors. The control command is selected based at least in part to cause the electric machine operatively coupled with the piston assembly to generate a preselected electrical power output. The controller provides the determined control command to the controllable device. The controllable device is operable to control an input to an engine working fluid disposed within the piston body.

A system including a closed cycle engine having a piston body defining a hot side and a cold side and having a piston assembly movable within the piston body. An electric machine is operatively coupled with the piston assembly. A control system includes one or more sensors operable to detect a piston movement characteristic of the piston assembly movable within the piston body. A controller is communicatively coupled with the one or more sensors and a controllable device. The controller is configured to determine a control command based at least in part on data received from the one or more sensors. The control command is selected based at least in part to cause the electric machine operatively coupled with the piston assembly to generate a preselected electrical power output. The controller provides the determined control command to the controllable device. The controllable device is operable to control an input to an engine working fluid disposed within the piston body.

A split Stirling cryogenic refrigerator device may include a resonant pneumatic expander comprising a resonant displacer assembly supported by a spring and configured to slide back and forth along a longitudinal axis within a housing of the resonant pneumatic expander, the resonant displacer assembly comprising a tubular displacer containing a regenerator and coupled to a sealing piston, and a driving piston coupled to the sealing piston by an elongated radially compliant and axially rigid connecting member.

A split Stirling cryogenic refrigerator device may include a resonant pneumatic expander comprising a resonant displacer assembly supported by a spring and configured to slide back and forth along a longitudinal axis within a housing of the resonant pneumatic expander, the resonant displacer assembly comprising a tubular displacer containing a regenerator and coupled to a sealing piston, and a driving piston coupled to the sealing piston by an elongated radially compliant and axially rigid connecting member.

An exhaust gas heat recovery system for an internal combustion engine has a pump for conveying an operating fluid, an evaporator for converting the operating fluid from the liquid state to the gaseous state, and a condenser for liquefaction of the operating fluid, and having an expansion engine through which the gaseous operating fluid can flow. A sensor is arranged on the expansion engine with which a function of the expansion engine can be monitored. An exhaust system may have such an exhaust gas heat recovery system, and a method for the diagnosis of such an exhaust heat recovery system.

An exhaust gas heat recovery system for an internal combustion engine has a pump for conveying an operating fluid, an evaporator for converting the operating fluid from the liquid state to the gaseous state, and a condenser for liquefaction of the operating fluid, and having an expansion engine through which the gaseous operating fluid can flow. A sensor is arranged on the expansion engine with which a function of the expansion engine can be monitored. An exhaust system may have such an exhaust gas heat recovery system, and a method for the diagnosis of such an exhaust heat recovery system.

An internal combustion engine having at least one combustion chamber, the internal combustion engine being connected via the exhaust thereof with an exhaust system. Disposed in the exhaust system is a heat exchanger of an exhaust heat recovery system, which can be used to transfer the waste heat of the exhaust gas to an operating fluid of the exhaust heat recovery system. Furthermore, the internal combustion engine is couplable to an air-conditioning compressor of an air-conditioning circuit. The exhaust heat recovery system has a further heat exchanger, in which the waste heat of a compressed refrigerant of the air-conditioning circuit is transferred to the operating fluid of the exhaust heat recovery system. A method for recovering the exhaust heat from such an internal combustion engine, an operating fluid of the exhaust heat recovery system being heated in a first method step by the waste heat of a compressed refrigerant of the air-conditioning circuit and, in a second method step, by the waste heat of the exhaust gas from the internal combustion engine.

An internal combustion engine having at least one combustion chamber, the internal combustion engine being connected via the exhaust thereof with an exhaust system. Disposed in the exhaust system is a heat exchanger of an exhaust heat recovery system, which can be used to transfer the waste heat of the exhaust gas to an operating fluid of the exhaust heat recovery system. Furthermore, the internal combustion engine is couplable to an air-conditioning compressor of an air-conditioning circuit. The exhaust heat recovery system has a further heat exchanger, in which the waste heat of a compressed refrigerant of the air-conditioning circuit is transferred to the operating fluid of the exhaust heat recovery system. A method for recovering the exhaust heat from such an internal combustion engine, an operating fluid of the exhaust heat recovery system being heated in a first method step by the waste heat of a compressed refrigerant of the air-conditioning circuit and, in a second method step, by the waste heat of the exhaust gas from the internal combustion engine.