A heat recovery engine (5) including a compressor (15) to increase pressure, density and temperature of a gas stream flowing in a closed loop within the engine, with the gas stream at base system pressure (10) at a compressor inlet; an expander (30) to reduce the pressure of said gas stream when compressed to just above said base system pressure, at the same time receiving power from the gas stream; a recuperator (20) to transfer thermal energy from downstream gas stream of said expander (30) to downstream gas stream of said compressor (15), thereby increasing the temperature of said downstream gas stream of said compressor (15) at approximately constant pressure; a heater (25) to provide further heat energy to said gas stream at approximately constant pressure after exit from said recuperator (20); a heat source (40) and a means (45) for transferring heat energy from said heat source (40) to said heater (25); a cooler (35) to cool said gas stream prior to compression in said compressor; a heat energy transfer device to transfer heat from aid cooler (35) to the environment; an operability device to ensure the operation of said compressor and said expander, and to take off surplus power either mechanically or electrically; a plurality of insulated ducts to transfer said gas stream between said compressor (15), recuperator (20), heater (25), expander (30) and cooler (35).

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 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.

The regenerative cooling system (100) is provided for a regenerative heat engine (1) and comprises a cooling chamber (79) which surrounds a gas expander (78), leaving open a gas circulation space (80) between said chamber (79) and said expander (78), a working gas (81) expelled from the gas expander (78) circulating in said space (80) before returning to a regenerative heat exchanger (5) where it is cooled, a large portion of the heat of said gas (81) being reintroduced into the thermodynamic cycle of the regenerative heat engine (1).

The regenerative cooling system (100) is provided for a regenerative heat engine (1) and comprises a cooling chamber (79) which surrounds a gas expander (78), leaving open a gas circulation space (80) between said chamber (79) and said expander (78), a working gas (81) expelled from the gas expander (78) circulating in said space (80) before returning to a regenerative heat exchanger (5) where it is cooled, a large portion of the heat of said gas (81) being reintroduced into the thermodynamic cycle of the regenerative heat engine (1).

An alpha type Stirling engine (1) comprises an expansion cylinder (2) and a compression cylinder (3). The Stirling engine further comprises a regenerator (4), a cooler (5), a heater (6), and a gas channel (7) which provides the expansion cylinder (2) in fluid communication with the compression cylinder (3). At least one of the expansion cylinder (2) and the compression cylinder (3) has a twin cylinder (2, 3) which functions as an additional expansion cylinder (2) or an additional compression cylinder (3), respectively, wherein the one of the expansion cylinder (2) and the compression cylinder (3) that has a twin cylinder (2, 3), is together with said twin cylinder (2 3) connected to a first portion (7a) of the gas channel (7), from which first portion (7a) the gas channel (7) extends via the regenerator (4) to a second portion (7b) to which the other one of the expansion cylinder (2) and the compression cylinder (3) is connected.

An alpha type Stirling engine (1) comprises an expansion cylinder (2) and a compression cylinder (3). The Stirling engine further comprises a regenerator (4), a cooler (5), a heater (6), and a gas channel (7) which provides the expansion cylinder (2) in fluid communication with the compression cylinder (3). At least one of the expansion cylinder (2) and the compression cylinder (3) has a twin cylinder (2, 3) which functions as an additional expansion cylinder (2) or an additional compression cylinder (3), respectively, wherein the one of the expansion cylinder (2) and the compression cylinder (3) that has a twin cylinder (2, 3), is together with said twin cylinder (2 3) connected to a first portion (7a) of the gas channel (7), from which first portion (7a) the gas channel (7) extends via the regenerator (4) to a second portion (7b) to which the other one of the expansion cylinder (2) and the compression cylinder (3) is connected.

A Stirling engine comprising: a crank case (1) with a crank shaft (2) arranged therein, a displacer cylinder (3) with a reciprocatingly arranged displacer piston (4) therein, said displacer piston (4) being connected to said crank shaft (2) via a connecting rod (5) extending through a first end of said displacer cylinder (3), and wherein the displacer cylinder (3) defines a hot chamber (6) and a cool chamber (7) separated by the displacer piston (4), a working cylinder (8) defining a working cylinder chamber (11) with a reciprocatingly arranged working piston (9) therein, said working piston (9) being connected to said crank shaft (2) via a connecting rod (10) extending through a first end of the working cylinder (8), a heater device (14), arranged at a second end of said displacer cylinder (3) opposite to said first end and configured to heat a working gas which is present in the hot chamber (6) of the displacer cylinder (3) and in fluid communication with the working cylinder chamber (11) through a working gas channel which comprises a first heat exchanger (16) extending from a head (19) of the displacer cylinder (3) into the heater device (14), and a second heat exchanger (17) formed by a regenerator arranged outside the heater device (14). The regenerator (17) comprises a regenerator element (17) formed by metal foam that has an open porosity.

A Stirling engine comprising: a crank case (1) with a crank shaft (2) arranged therein, a displacer cylinder (3) with a reciprocatingly arranged displacer piston (4) therein, said displacer piston (4) being connected to said crank shaft (2) via a connecting rod (5) extending through a first end of said displacer cylinder (3), and wherein the displacer cylinder (3) defines a hot chamber (6) and a cool chamber (7) separated by the displacer piston (4), a working cylinder (8) defining a working cylinder chamber (11) with a reciprocatingly arranged working piston (9) therein, said working piston (9) being connected to said crank shaft (2) via a connecting rod (10) extending through a first end of the working cylinder (8), a heater device (14), arranged at a second end of said displacer cylinder (3) opposite to said first end and configured to heat a working gas which is present in the hot chamber (6) of the displacer cylinder (3) and in fluid communication with the working cylinder chamber (11) through a working gas channel which comprises a first heat exchanger (16) extending from a head (19) of the displacer cylinder (3) into the heater device (14), and a second heat exchanger (17) formed by a regenerator arranged outside the heater device (14). The regenerator (17) comprises a regenerator element (17) formed by metal foam that has an open porosity.

A Stirling engine comprising: a crank case (1) with a crank shaft (2) arranged therein, a displacer cylinder (3) with a reciprocatingly arranged displacer piston (4) therein, said displacer piston (4) being connected to said crank shaft (2) via a connecting rod (5) extending through a first end of said displacer cylinder (3), and wherein the displacer cylinder (3) defines a hot chamber (6) and a cool chamber (7) separated by the displacer piston (4), a working cylinder (8) defining a working cylinder chamber (11) with a reciprocatingly arranged working piston (9) therein, said working piston (9) being connected to said crank shaft (2) via a connecting rod (10) extending through a first end of the working cylinder (8), a heater device (14), arranged at a second end of said displacer cylinder opposite to said first end and configured to heat a working gas which is present in the hot chamber (6) of the displacer cylinder (3) and in fluid communication with the working cylinder chamber (11) through a working gas channel which comprises a first heat exchanger (16) extending from a head (19) of the displacer cylinder (3) into the heater device (14), a second heat exchanger (17) formed by a regenerator arranged outside the heater device (14), and a third heat exchanger (20) formed by a cooler arranged between the regenerator (17) and the working cylinder chamber (11). At any point along the working gas channel, as seen cross wise to an assumed working gas flow direction through the working gas channel, the cross section area of the working gas channel defined by the first, second and third heat exchangers is within the range of the medium cross section area of the working gas channel +/10%.