Thermal management system for an aircraft
A thermal management system for an aircraft includes a thermal bus including one or more first heat sources; a heat sink; a vapour compression system including a compressor, a condenser, a receiver, a first side of a recuperator, an expansion valve, an evaporator, a second side of the recuperator, and the compressor; and one or more second heat sources. A heat transfer fluid transfers waste heat energy generated by the first heat sources to the heat sink. A second flow of waste heat energy from the second heat source(s) is transferred to a refrigerant. A third flow of heat energy in the refrigerant is transferred to the heat transfer fluid. The compressor includes a supplementary refrigerant reservoir, and the volume of refrigerant in the vapour compression system is increased during operation when a temperature of the heat transfer fluid is at or below a temperature of the second heat source(s).
1. A thermal management system for an aircraft, the thermal management system comprising a first thermal bus, the first thermal bus comprising, in a closed loop flow sequence, one or more first heat sources, a heat sink, a vapour compression system, and one or more second heat sources, and
wherein the vapour compression system comprises, in closed loop flow sequence, a compressor, a condenser, a receiver, a first side of a recuperator, an expansion valve, an evaporator, a second side of the recuperator, and the compressor, each of the compressor and the expansion valve being controlled by a controller,
wherein the first thermal bus comprises a first heat transfer fluid, a first heat flow (Q 1 ) of waste heat energy generated by the first heat sources is transferred via the first heat transfer fluid to the heat sink, and
wherein the vapour compression system comprises a refrigerant fluid, a second heat flow (Q 2 ) of waste heat energy generated by the or each second heat source is transferred via the evaporator to the refrigerant, and a third heat flow (Q 3 ) of heat energy in the refrigerant is transferred via the condenser to the first heat transfer fluid, and the compressor is provided with a supplementary reservoir of refrigerant fluid, the supplementary reservoir being configured to increase the volume of the refrigerant fluid in the vapour compression system during operation when a temperature of the first heat transfer fluid is equal to or less than a temperature of the or each second heat source.
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 a first gas turbine engine, a first electric machine, a first heat exchanger, and a first ancillary system.
3. The thermal management system as claimed in claim 2 , wherein the first gas turbine engine is a first turbofan gas turbine engine, the turbofan gas turbine engine comprising, in axial flow sequence, 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, preferably within the range 0.4 m to 1.5 m, and more preferably in the range of 0.7 m to 1.0 m.
4. The thermal management system as claimed in claim 3 , wherein the first turbofan gas turbine engine further comprises an outer casing, the outer casing enclosing the sequential arrangement of fan assembly, compressor module, combustor module, and turbine module, an annular bypass duct being defined between the outer casing and the sequential arrangement of compressor module, combustor module, and 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 compressor module, combustor module, and turbine module, and wherein the bypass ratio is less than 4.0.
5. The thermal management system as claimed in claim 3 , wherein the fan assembly has two or more fan stages, at least one of the fan stages comprising a plurality of fan blades defining the fan diameter D FAN .
6. A method of operating a thermal management system for an aircraft, the thermal management system comprising a first thermal bus, the first thermal bus comprising, in a closed loop flow sequence, one or more first heat sources, a heat sink, a vapour compression system, and one or more second heat sources,
the method comprising the steps of:
providing a vapour compression system comprising, in closed loop flow sequence, a compressor, a condenser, a receiver, a first side of a recuperator, an expansion valve, an evaporator, a second side of the recuperator, and the compressor;
providing the vapour compression system with a refrigerant fluid;
providing a controller configured to control each of the compressor and the expansion valve;
operating the expansion valve to a fully open condition;
increasing a volume of refrigerant in the vapour compression system closed loop when a temperature of a first heat transfer fluid is equal to or less than a temperature of the or each second heat source;
transferring a first heat flow (Q 1 ) of waste heat energy generated by at least one of the first heat sources, to the first heat transfer fluid;
transferring a second heat flow (Q 2 ) of waste heat energy generated by the or each second heat source is transferred via the evaporator to the refrigerant
transferring a third heat flow (Q 3 ) of heat energy in the refrigerant generated by the or each second heat source is transferred via the condenser to the first heat transfer fluid; and
transferring the waste heat energy from the first heat transfer fluid to a dissipation medium.