By subjecting a volume or a bulk of a working material to a body force per unit mass, such as gravity, inertial forces, electric forces, or magnetic forces, the perceived specific heat capacity of the volume of the working material can be increased or decreased as desired. The artificial modification of the perceived specific heat capacity of a material can be employed in a thermodynamic cycle to convert thermal energy directly into useful mechanical work, and vice versa.

A method for power generation via a liquid-gas phase transition. The method includes receiving atmospheric air as input to create an enthalpy difference gradient. A regenerative piston engine received atmospheric air. The regenerative piston engine collects heat generated from the enthalpy difference gradient. The regenerative piston engine converts the collected heat to a mechanical form of energy at the regenerative piston engine.

A method for power generation via a liquid-gas phase transition. The method includes receiving atmospheric air as input to create an enthalpy difference gradient. A regenerative piston engine received atmospheric air. The regenerative piston engine collects heat generated from the enthalpy difference gradient. The regenerative piston engine converts the collected heat to a mechanical form of energy at the regenerative piston engine.

The present invention concerns an external heat source engine comprising: at least one cylinder (2), a piston (3) that is movable back and forth in the cylinder, a cylinder head (4) defining a working chamber (5) with the piston and the cylinder, a heat exchanger (6) for exchanging heat between a working gas and a heat-transfer fluid, a distribution comprising two rotary slide valves (20, 30) mounted so as to be able to rotate in the cylinder head and bringing the working chamber selectively into communication with the following resources: a working gas inlet (A), a cold end (B) of the exchanger, a hot end (C) of the exchanger, an exhaust (D). The slide valves (20, 30) comprise internal passages that open through the side wall of same through at least one opening that communicates selectively with the working chamber (5) via at least one opening formed in the cylinder head (4).

The present invention concerns an external heat source engine comprising: at least one cylinder (2), a piston (3) that is movable back and forth in the cylinder, a cylinder head (4) defining a working chamber (5) with the piston and the cylinder, a heat exchanger (6) for exchanging heat between a working gas and a heat-transfer fluid, a distribution comprising two rotary slide valves (20, 30) mounted so as to be able to rotate in the cylinder head and bringing the working chamber selectively into communication with the following resources: a working gas inlet (A), a cold end (B) of the exchanger, a hot end (C) of the exchanger, an exhaust (D). The slide valves (20, 30) comprise internal passages that open through the side wall of same through at least one opening that communicates selectively with the working chamber (5) via at least one opening formed in the cylinder head (4).

A method for controlling an internal combustion engine system, the engine system including a combustor arranged to receive air and fuel, and combust the received air and fuel, an expander arranged to expand exhaust gases from the combustion in the combustor and to extract energy from the expanded exhaust gases, and a communication valve arranged to control a communication between the combustor and the expander, including determining during operation of the engine system whether there is a pressure difference across said communication valve.

An internal combustion engine system includes at least one combustor, a compressor arranged to compress air, an air guide arranged to guide compressed air from the compressor to at least one of the at least one combustor, an expander arranged to expand exhaust gases from at least one of the at least one combustor and to extract energy from the expanded exhaust gases, and an exhaust guide arranged to guide exhaust gases from at least one of the at least one combustor to the expander, wherein the exhaust guide is at least partly integrated with the air guide.

An internal combustion engine system includes at least one combustor, a compressor arranged to compress air, an air guide arranged to guide compressed air from the compressor to at least one of the at least one combustor, an expander arranged to expand exhaust gases from at least one of the at least one combustor and to extract energy from the expanded exhaust gases, and an exhaust guide arranged to guide exhaust gases from at least one of the at least one combustor to the expander, wherein the exhaust guide is at least partly integrated with the air guide.

To provide refrigeration below 200 K, a Brayton cycle engine contains a light reciprocating piston. The refrigerator includes a compressor, a gas-balanced reciprocating engine having a cold rotary valve, a counterflow heat exchanger, a gas storage volume with valves that can adjust system pressures, a variable speed engine and a control system that controls gas pressure, engine speed, and the speed of the piston. The engine is connected to a load such as a cryopanel, for pumping water vapor, through insulated transfer lines.

To provide refrigeration below 200 K, a Brayton cycle engine contains a light reciprocating piston. The refrigerator includes a compressor, a gas-balanced reciprocating engine having a cold rotary valve, a counterflow heat exchanger, a gas storage volume with valves that can adjust system pressures, a variable speed engine and a control system that controls gas pressure, engine speed, and the speed of the piston. The engine is connected to a load such as a cryopanel, for pumping water vapor, through insulated transfer lines.