Reverse air cycle machine (RACM) thermal management systems and methods

A method of cooling portions of an aircraft, the method comprising:

• mounting at least one reverse air cycle machine (RACM) on an engine of the aircraft;
• using a vapor cycle system (VCS) to circulate a refrigerant;
• coupling the at least one RACM to the VCS through a condenser;
• providing a first heat sink for the VCS through the coupling the at least one RACM to the VCS;
• receiving compressed bleed air from an engine compressor at the at least one RACM;
• cooling and expanding the compressed bleed air using the at least one RACM;
• directing the cooled and expanded bleed air to the condenser where the expanded bleed air absorbs heat energy from the fluid that circulates through the VCS.

An aircraft comprising:

• a fuselage defining an internal cabin;
• wings extending from the fuselage;
• an engine carried by the fuselage, wherein the engine comprises an engine case containing an engine fan, an engine core including an engine compressor, and a bypass heat exchanger within the engine case that is outside of the engine core, wherein the bypass heat exchanger is disposed within a bypass air stream outside of the engine core;
• and
• a thermal management system that is configured to cool portions of the aircraft, the thermal management system comprising:
• at least one reverse air cycle machine (RACM) mounted on the engine, wherein the at least one RACM is coupled to the engine compressor through the bypass heat exchanger, wherein the bypass heat exchanger cools compressed bleed air from the engine compressor before the compressed air is directed to the at least one RACM, wherein the at least one RACM comprises one or more turbines that are configured to expand and cool the compressed bleed air from the compressor, and one or more compressors that are configured to compress the bleed air;
• a vapor cycle system (VCS) that is configured to circulate a refrigerant;
• and
• a condenser that couples the at least one RACM to the VCS, wherein the at least one RACM coupled to the VCS through the condenser provides a first heat sink for the VCS,
• wherein the at least one RACM receives the compressed bleed air from the engine compressor and cools and expands the bleed air, and wherein the cooled and expanded bleed air is directed to the condenser where the expanded bleed air absorbs heat energy from the fluid that circulates through the VCS, and
• wherein the at least one RACM reintroduces the bleed air back into the engine after the bleed air passes through the at least one RACM to regain thrust.

A thermal management system that is configured to cool portions of an aircraft, the thermal management system comprising:

• at least one reverse air cycle machine (RACM) mounted on an engine of the aircraft, wherein the at least one RACM comprises a first turbine, a second turbine, a first compressor, and a second compressor, wherein the first turbine, the second turbine, the first compressor, and the second compressor are coupled to a common shaft;
• a vapor cycle system (VCS) that is configured to circulate a refrigerant;
• and
• a condenser that couples the at least one RACM to the VCS, wherein the at least one RACM coupled to the VCS through the condenser provides a first heat sink for the VCS.

A thermal management system that is configured to cool portions of an aircraft, the thermal management system comprising:

• at least one reverse air cycle machine (RACM) mounted on an engine of the aircraft;
• a vapor cycle system (VCS) that is configured to circulate a refrigerant;
• a first heat exchanger that couples the at least one RACM to the VCS, wherein the at least one RACM coupled to the VCS through the first heat exchanger provides a first heat sink for the VCS;
• a second heat exchanger coupled to a fuel line and the VCS, wherein the second heat exchanger coupled to the fuel line provides a second heat sink for the VCS;
• and
• a third heat exchanger coupled to a ram air bypass conduit and the VCS, wherein the third heat exchanger coupled to the ram air bypass conduit provides a third heat sink for the VCS.

A thermal management system that is configured to cool portions of an aircraft, the thermal management system comprising:

• a low pressure reverse air cycle machine (RACM) coupled to a high pressure RACM mounted on an engine of the aircraft;
• a vapor cycle system (VCS) that is configured to circulate a refrigerant;
• a condenser that couples the low pressure RACM and the high pressure RACM to the VCS, wherein the low pressure RACM and the high pressure RACM coupled to the VCS through the condenser provides a first heat sink for the VCS;
• and
• a control unit operatively coupled to the low pressure RACM and the high pressure RACM, wherein the control unit is configured to direct compressed bleed air from an engine compressor through only the low pressure RACM when an airspeed of the aircraft is subsonic, and wherein the control unit is configured to direct the compressed bleed air from the engine compressor through the high pressure RACM before the low pressure RACM when the airspeed of the aircraft is supersonic.

A method of cooling portions of an aircraft, the method comprising:

• mounting at least one reverse air cycle machine (RACM) on an engine of the aircraft;
• using a vapor cycle system (VCS) to circulate a refrigerant;
• coupling the at least one RACM to the VCS through a first heat exchanger to provide a first heat sink for the VCS;
• coupling a second heat exchanger to a fuel line and the VCS to provide a second heat sink for the VCS;
• and
• coupling a third heat exchanger coupled to a ram air bypass conduit and the VCS to provide a third heat sink for the VCS.

A method of cooling portions of an aircraft, the method comprising:

• mounting a low pressure RACM and a high pressure RACM on an engine of the aircraft;
• using a vapor cycle system (VCS) to circulate a refrigerant;
• coupling the a low pressure RACM and the high pressure RACM to the VCS through a condenser;
• providing a first heat sink for the VCS through the coupling the low pressure RACM and the high pressure RACM to the VCS;
• operatively coupling a control unit to the low pressure RACM and the high pressure RACM;
• using the control unit to direct the compressed bleed air from the engine compressor through only the low pressure RACM when an airspeed of the aircraft is subsonic;
• and
• using the control unit to direct the compressed bleed air from the engine compressor through the high pressure RACM before the low pressure RACM when the airspeed of the aircraft is supersonic.