Thermal management system for an aircraft
A thermal management system for an aircraft includes a first gas turbine engine, one or more first electric machines rotatably coupled to the first gas turbine engine, a first thermal bus, and a first heat exchanger. Waste heat energy generated by at least one first gas turbine engine, and first electric machine, transfers to the first heat transfer fluid. The first heat exchanger directs a first proportion of the first heat transfer fluid through a first heat dissipation portion wherein a first proportion of the waste heat energy transfers to a first dissipation medium dependent on the first dissipation medium temperature and mass flow rate. The first heat exchanger directs a second proportion of the first heat transfer fluid through a second heat dissipation portion wherein the second proportion of waste heat energy transfers to a second dissipation medium dependent on the second dissipation medium temperature and mass flow rate.
1 . A thermal management system for an aircraft, the thermal management system comprising:
a first gas turbine engine;
one or more first electric machines rotatably coupled to the first gas turbine engine;
a first thermal bus;
a first heat exchanger; and
one or more ancillary systems, wherein
the first thermal bus comprises a first heat transfer fluid, the first heat transfer fluid being in fluid communication, in a closed loop flow, between the first gas turbine engine, each of the one or more first electric machines, and the first heat exchanger, such that waste heat energy generated by at least one of the first gas turbine engine, and each of the one or more first electric machines, is transferred to the first heat transfer fluid,
the first heat exchanger is configured to direct a first proportion of the flow of the first heat transfer fluid through a first heat dissipation portion in which a first proportion Q A of the waste heat energy from the first heat transfer fluid is transferred to a first dissipation medium being an air flow, and a second proportion of the flow of the first heat transfer fluid through a second heat dissipation portion in which a second proportion Q B of the waste heat energy from the first heat transfer fluid is transferred to a second dissipation medium being a fuel flow, and
the first heat exchanger selectively directs the first proportion through the first heat dissipation portion depending on a temperature of the first dissipation medium and a mass flow rate of the first dissipation medium, and/or directs the second proportion through the second heat dissipation portion depending on a temperature of the second dissipation medium and a mass flow rate of the second dissipation medium, and
in response to a temperature of the first heat transfer fluid leaving the first heat dissipation portion being less than the temperature of the first heat dissipation fluid, the first heat transfer fluid upstream of the first heat exchanger is controlled to pass through only the second heat dissipation portion; and in response to the temperature of the first heat transfer fluid leaving the first heat dissipation portion being greater than the temperature of the first heat dissipation fluid, the first heat transfer fluid upstream of the first heat exchanger is controlled to pass through the second heat dissipation portion and then through portion the first heat dissipation, via a cross-over path extending from an outlet of the second dissipation portion to an inlet of the first dissipation portion.
2 . The thermal management system as claimed in claim 1 , wherein the first thermal bus is arranged in a recirculatory ring configuration with the first heat transfer fluid passing through each of the first gas turbine engine, each of the one or more first electric machines, the first heat exchanger, and each of the one or more ancillary systems.
3 . The thermal management system as claimed in claim 1 , wherein the first heat exchanger is configured to direct the first proportion of the flow of the first heat transfer fluid through the first heat dissipation portion in which the first proportion Q A of the waste heat energy from the first heat transfer fluid is transferred to the first dissipation medium depending on a first temperature differential between the temperature of the first heat transfer fluid and the temperature of the first dissipation medium.
4 . The thermal management system as claimed in claim 1 , wherein the first heat exchanger comprises a bypass flow path, and wherein the first heat exchanger is configured to direct a third proportion of the flow of the first heat transfer fluid through the bypass flow path depending the temperature of the first dissipation medium and the mass flow rate of the first dissipation medium, and/or the temperature of the second dissipation medium and the mass flow rate of the second dissipation medium.
5 . The thermal management system as claimed in claim 1 , wherein the first gas turbine engine comprises, in axial flow sequence, the first heat exchanger, a compressor module, a combustor module, and a turbine module, and the first dissipation medium is the air flow passing through the first heat exchanger and entering the compressor module.
6 . The thermal management system as claimed in claim 1 , wherein the first gas turbine engine comprises, in axial flow sequence, a compressor module, a combustor module, and a turbine module, and the second dissipation medium is the fuel flow passing through the first heat exchanger and subsequently being directed to the combustor module.
7 . The thermal management system as claimed in claim 1 , wherein the first gas turbine engine is a first turbofan gas turbine engine, the turbofan gas turbine engine comprising, in axial flow sequential arrangement, a fan module, a compressor module, a combustor module, and a turbine module, the fan module comprising at least one fan stage having a plurality of fan blades extending radially from a hub, the plurality of fan blades defining a fan diameter (D FAN ), and wherein the fan diameter D FAN is within the range of 0.3 m to 2.0 m.
8 . The thermal management system as claimed in claim 7 , wherein the first turbofan gas turbine engine further comprises an outer casing, the outer casing enclosing the sequential arrangement of the fan assembly, the compressor module, the combustor module, and the turbine module, an annular bypass duct being defined between the outer casing and the sequential arrangement of the compressor module, the combustor module, and the turbine module, a bypass ratio being defined as a ratio of a mass air flow rate through the bypass duct to a mass air flow rate through the sequential arrangement of the compressor module, the combustor module, and the turbine module, and wherein the bypass ratio is less than 4.0.
9 . The thermal management system as claimed in claim 7 , wherein the at least one fan stage is two or more fan stages.
10 . A method of operating a thermal management system for an aircraft, the thermal management system comprising a first gas turbine engine, one or more first electric machines rotatably coupled to the first gas turbine engine, and a first heat exchanger,
the method comprising:
(i) providing a first thermal bus comprising a first heat transfer fluid with the first heat transfer fluid providing fluid communication, in a closed loop flow, between the first gas turbine engine, each of the one or more first electric machines and the first heat exchanger, such that waste heat energy generated by at least one of the first gas turbine engine, and each of the one or more first electric machines;
(ii) directing a first proportion of the flow of the first heat transfer fluid through a first heat dissipation portion in which a first proportion Q A of the waste heat energy from the first heat transfer fluid is transferred to a first dissipation medium being an air flow; and
(iii) directing a second proportion of the flow of the first heat transfer fluid through a second heat dissipation portion in which a second proportion Q B of the waste heat energy from the first heat transfer fluid is transferred to a second dissipation medium being a fuel flow, wherein
the first heat exchanger selectively directs the first proportion through the first heat dissipation portion depending on a temperature of the first dissipation medium and a mass flow rate of the first dissipation medium, and/or directs the second proportion through the second heat dissipation portion depending on a temperature of the second dissipation medium and a mass flow rate of the second dissipation medium, and
in response to a temperature of the first heat transfer fluid leaving the first heat dissipation portion being less than the temperature of the first heat dissipation fluid, the first heat transfer fluid upstream of the first heat exchanger is controlled to pass through only the second heat dissipation portion; and in response to the temperature of the first heat transfer fluid leaving the first heat dissipation portion being greater than the temperature of the first heat dissipation fluid, the first heat transfer fluid upstream of the first heat exchanger is controlled to pass through the second heat dissipation portion and then through portion the first heat dissipation, via a cross-over path extending from an outlet of the second dissipation portion to an inlet of the first dissipation portion.
11 . The method as claimed in claim 10 , further comprising:
(iv) directing a third proportion of the flow of the first heat transfer fluid through the bypass flow path depending the temperature of the first dissipation medium and the mass flow rate of the first dissipation medium, and/or the temperature of the second dissipation medium and the mass flow rate of the second dissipation medium.