Integrated heat management for hybrid propulsion

1. A power plant for a hybrid electric aircraft, the power plant comprising:

at least one electric propulsor having a nacelle housing a fan for generating thrust for the aircraft, wherein the nacelle defines an air passage for ducting a stream of air drawn by the fan;

a generator for supplying power to the at least one electric propulsor;

at least one combustion engine operatively connected to the generator; and

a heat exchanger connected in heat exchange relationship with both the generator and the at least one combustion engine, the heat exchanger being provided at an outer duct wall of the nacelle of the at least one electric propulsor to dissipate combined heat from the generator and the at least one combustion engine into the stream of air drawn into the air passage by the fan;

wherein the at least one combustion engine has an exhaust gas section in flow communication with the air passage of the nacelle to discharge exhaust gases into the air passage downstream of the heat exchanger such as to further energize the air discharged from the at least one electric propulsor.

2. The power plant defined in claim 1 , wherein the at least one combustion engine comprises an internal combustion engine (ICE) having a variable volume combustion chamber, the ICE being liquid cooled, and wherein the heat exchanger is a liquid-air heat exchanger.

3. The power plant defined in claim 1 , further comprising a battery pack for supplying power to the at least one electric propulsor, the heat exchanger being also connected in heat exchange relationship with the battery pack to dissipate combined heat from the battery pack, the at least one combustion engine and the generator.

4. The power plant defined in claim 3 , wherein the at least one combustion engine comprises a gas turbine engine and an internal combustions engine (ICE), and wherein the heat exchanger is exposed to ambient air and is in heat exchange relationship with the generator, the battery pack and the ICE to dissipate combined heat therefrom into the ambient air.

5. The power plant defined in claim 1 , wherein heat dissipated by the heat exchanger is routed to an inlet lip of the nacelle of the at least one electric propulsor to perform a de-icing function.

6. The power plant defined in claim 1 , wherein the heat exchanger is disposed at an outer flow boundary of the air passage.

7. The power plant defined in claim 6 , wherein the at least one combustion engine comprises a gas turbine engine and an internal combustions engine (ICE).

8. An aircraft comprising:

an electric propulsor having a nacelle housing a fan driven by an electric motor, the nacelle circumscribing an air passage for directing a stream of air drawn by the fan;

a source of power for supplying power to the electric propulsor, the source of power including a battery pack and a generator;

a combustion engine operatively connected to the generator; and

a common cooling system for the battery pack, the generator and the combustion engine, the common cooling system comprising a heat exchanger integrated to the nacelle of the electric propulsor downstream of the fan, the heat exchanger disposed to discharge heat into the stream of air flowing through the air passage; wherein the combustion engine has an exhaust section fluidly connected to the air passage and configured to discharge combustion gases into the air passage downstream of the heat exchanger.

9. The aircraft defined in claim 8 , wherein the combustion engine comprises an internal combustion engine (ICE) having a variable volume combustion chamber, and wherein the common cooling system comprises a coolant circuit through which a coolant is circulated to pick up heat from the battery pack, the generator and the ICE, the coolant circuit extending through the heat exchanger for dissipating heat carried by the coolant into ambient air.

10. The aircraft defined in claim 8 , wherein the nacelle has an inlet lip, and wherein the cooling system further comprises an additional heat exchanger integrated to the inlet lip, the additional heat exchanger being connected in heat exchange relationship with the battery pack, the generator and the combustion engine.

11. A method of managing heat generated by a power plant of an aircraft having electric propulsors powered at least in part by a battery pack and a generator, the generator operatively connected to a combustion engine, the method comprising: withdrawing heat from the battery pack, the generator and the combustion engine and dissipating the heat in ambient air outside the aircraft via a heat exchanger operatively connected to the battery pack, the generator and the combustion engine.

12. The method of claim 11 , wherein withdrawing heat comprises circulating a coolant in heat exchange relationship with the battery pack, the combustion engine and the generator, and wherein dissipating heat comprises circulating the coolant through the heat exchanger.

13. The method of claim 12 , comprising transferring heat from the coolant to a flow of air propelled by the electric propulsors to generate thrust for the aircraft.

14. The method of claim 12 , comprising using the heat carried by the liquid coolant to de-ice an inlet lip of the nacelle of the electric propulsors.

15. The method of claim 13 , wherein each of the electric propulsors has a nacelle circumscribing an air passage, and wherein the method further comprises directing exhaust gases from the combustion engine into the air passage to further energize the flow of air downstream of the heat exchanger.

16. The method of claim 12 , wherein withdrawing heat comprises using the same coolant for removing heat from the battery pack, the generator and the combustions engine.

17. The method of claim 16 , wherein the heat exchanger is mounted to an outer duct wall of a nacelle of the electric propulsor, and wherein the combustion engine a liquid cooled internal combustion engine (ICE).