Micro-scale engines, components, and methods for generating power

A heat engine, comprising:

• a combustor comprising a fuel inlet, an air inlet and an exhaust outlet;
• a turbocharger rotatable about a spool and communicating with the air inlet wherein the turbocharger feeds air to the combustor;
• a compressor rotatable about the spool wherein the compressor is driven to rotate by the turbocharger, the compressor comprising a compressor inlet for aspirating ambient air;
• a power turbine communicating with the compressor wherein the power turbine is driven to rotate by compressed air from the compressor;
• a recuperator comprising a high-temperature recuperator circuit in thermal contact with a low-temperature recuperator circuit for transferring heat thereto, the high-temperature recuperator circuit communicating with the exhaust outlet, and the low-temperature recuperator circuit interposed between the power turbine and the turbocharger, wherein the turbocharger is driven to rotate by heated air from the recuperator;
• a boiler comprising a high-temperature boiler circuit in thermal contact with a low-temperature boiler circuit for transferring heat thereto, the high-temperature boiler circuit communicating with the high-temperature recuperator circuit for receiving exhaust gas therefrom;
• an ejector comprising a first ejector inlet communicating with the low-temperature boiler circuit for receiving a flow of vaporized working fluid therefrom, a second ejector inlet communicating with the high-temperature boiler circuit for receiving exhaust gas therefrom, and an ejector outlet, wherein the ejector is configured for entraining the exhaust gas from the second ejector inlet in the flow of vaporized working fluid from the first ejector inlet and increasing a pressure drop across the power turbine;
• a condenser comprising a high-temperature condenser circuit in thermal contact with a low-temperature condenser circuit for transferring heat thereto, the high-temperature condenser circuit communicating with the ejector outlet, wherein the low-temperature condenser circuit is configured for flowing a cold fluid through the condenser;
• and
• an injector comprising an injector liquid inlet communicating with the high-temperature condenser circuit for receiving condensed working fluid therefrom, and an injector outlet communicating with the low-temperature boiler circuit, wherein the injector is configured for flowing liquid-phase working fluid to the boiler.

A method for generating power, the method comprising:

• flowing an exhaust gas comprising combustion products from a power turbine to a boiler;
• vaporizing a working fluid by flowing the working fluid through the boiler while flowing the exhaust gas through the boiler, wherein heat is transferred from the exhaust gas to the working fluid;
• flowing the vaporized working fluid through an ejector;
• entraining the exhaust gas in the vaporized working fluid as the vaporized working fluid flows through the ejector by flowing the exhaust gas from the boiler into the ejector, wherein entrainment of the exhaust gas creates suction downstream of the power turbine;
• condensing the working fluid discharged from the ejector and returning the condensed working fluid to the boiler for vaporization by the exhaust gas flowing through the boiler;
• and
• driving the power turbine to rotate by flowing the exhaust gas to the turbine from a combustor disposed upstream of the power turbine, and by creating the suction in the exhaust gas downstream of the power turbine.

A method for generating power, comprising:

• flowing an exhaust gas comprising combustion products from a combustor to a recuperator;
• while flowing the exhaust gas through the recuperator, flowing air discharged from a power turbine through the recuperator wherein heat is transferred from the exhaust gas to the air;
• flowing the exhaust gas from the recuperator to a boiler;
• vaporizing a working fluid by flowing the working fluid through the boiler while flowing the exhaust gas through the boiler, wherein heat is transferred from the exhaust gas to the working fluid;
• flowing the vaporized working fluid through an ejector;
• entraining the exhaust gas in the vaporized working fluid as the vaporized working fluid flows through the ejector by flowing the exhaust gas from the boiler into the ejector, wherein entrainment of the exhaust gas creates suction downstream of the power turbine;
• condensing the working fluid discharged from the ejector and returning the condensed working fluid to the boiler for vaporization by the exhaust gas flowing through the boiler;
• and
• driving a turbocharger and a compressor to rotate by flowing the heated air from the recuperator to the turbocharger, wherein the compressor rotates on a common spool with the turbocharger;
• driving the power turbine to rotate by flowing compressed air from the compressor to the power turbine.

A heat exchanger, comprising:

• a plurality of hot fluid plates stacked in series along a longitudinal direction, each hot fluid plate having a thickness in the longitudinal direction and a planar area in a transverse plane orthogonal to the longitudinal direction, and each hot fluid plate comprising a central hole, a hot fluid inlet hole and a hot fluid outlet hole formed through the thickness, the hot fluid inlet hole and the hot fluid outlet hole located at respective radial distances from the central hole, and each hot fluid plate further comprising a transverse channel running in the transverse plane from the hot fluid inlet hole, around the central hole and to the hot fluid outlet hole;
• and
• a cold fluid circuit running from a cold fluid inlet to a cold fluid outlet in thermal contact with the transverse channels, wherein:
• the central holes are aligned with each other along the longitudinal direction;
• the hot fluid inlet holes are aligned with each other along the longitudinal direction, forming a hot fluid inlet plenum;
• the hot fluid outlet holes are aligned with each other along the longitudinal direction, forming a hot fluid outlet plenum;
• and
• the transverse channels establish a plurality of transverse flow paths from the hot fluid inlet plenum to the hot fluid outlet plenum.

A heat exchanger, comprising:

• a plurality of hot fluid plates each having a thickness in a longitudinal direction and a planar area in a transverse plane orthogonal to the longitudinal direction, each hot fluid plate comprising a central hole, a hot fluid outlet hole, a cold fluid inlet hole and a cold fluid outlet hole formed through the thickness, the hot fluid outlet hole, the cold fluid inlet hole and the cold fluid outlet hole located at respective radial distances from the central hole, and each hot fluid plate further comprising a hot fluid transverse channel running in the transverse plane from the central hole and radially outward therefrom, around the central hole and to the hot fluid outlet hole;
• and
• a plurality of cold fluid plates each having a thickness in the longitudinal direction and a planar area in the transverse plane, each cold fluid plate comprising a central hole, a hot fluid outlet hole, a cold fluid inlet hole and a cold fluid outlet hole formed through the thickness, and each cold fluid plate further comprising a cold fluid transverse channel running in the transverse plane from the cold fluid inlet hole, around the central hole and to the cold fluid outlet hole, wherein:
• the hot fluid plates and the cold fluid plates are stacked along the longitudinal direction in alternating series with each other such that each hot fluid plate is adjacent to at least one of the cold fluid plates and each hot fluid transverse channel is in thermal contact with at least one of the cold fluid transverse channels;
• the central holes of the hot fluid plates and the cold fluid plates are aligned with each other along the longitudinal direction, forming a hot fluid inlet plenum;
• the hot fluid outlet holes of the hot fluid plates and the cold fluid plates are aligned with each other along the longitudinal direction, forming a hot fluid outlet plenum;
• the cold fluid inlet holes of the hot fluid plates and the cold fluid plates are aligned with each other along the longitudinal direction, forming a cold fluid inlet plenum;
• the cold fluid outlet holes of the hot fluid plates and the cold fluid plates are aligned with each other along the longitudinal direction, forming a cold fluid outlet plenum;
• the hot fluid transverse channels establish a plurality of transverse flow paths from the hot fluid inlet plenum to the hot fluid outlet plenum;
• and
• the cold fluid transverse channels establish a plurality of transverse flow paths from the cold fluid inlet plenum to the cold fluid outlet plenum.