Cooling system and method for a dual-powered railroad vehicle

1. A dual-powered railroad vehicle, comprising:

a combustion engine having a first cooling circuit;

a traction transformer operatively coupled to an electric grid to provide power to the dual-powered railroad vehicle during pure electric operation of the dual-powered railroad vehicle, the traction transformer having a second cooling circuit;

at least one radiator for dissipating thermal energy to surrounding air,

wherein the first cooling circuit and the second cooling circuit are configured to dissipate thermal energy via the at least one radiator.

2. The railroad vehicle of claim 1 , wherein the second cooling circuit is thermally coupled to the first cooling circuit outside from the at least one radiator, and wherein preferably, only coolant from the first cooling circuit flows through the at least one radiator.

3. The railroad vehicle of claim 1 , wherein the second cooling circuit is thermally coupled to the first cooling circuit via a heat exchanger.

4. The railroad vehicle of claim 1 , wherein the first cooling circuit- and the second cooling circuit are liquid-based.

5. The railroad vehicle of claim 1 , wherein the first cooling circuit comprises water or oil, and wherein the second cooling circuit comprises an insulating fluid.

6. The railroad vehicle of claim 5 , wherein the insulating fluid comprises a natural oil and/or a synthetic oil and/or an ester oil and/or Silicon oil.

7. The railroad vehicle of claim 1 , further comprising a reactor and/or a power electronic traction converter, being in thermal connection to the second cooling circuit or to third cooling circuit, which is configured to dissipate thermal energy via the at least one radiator.

8. The railroad vehicle of claim 1 , wherein a part of the first cooling circuit, to which the second cooling circuit is thermally coupled, is fluidly disconnected from the combustion engine during pure electric operation of the railroad vehicle.

9. The railroad vehicle of claim 1 , further comprising at least one fan, which is electrically or hydrostatically driven, to circulate air through the at least one radiator.

10. The railroad vehicle of claim 1 , wherein at least one fan, employed during operation of the combustion engine for dissipating heat from the first cooling circuit, is electrically driven.

11. The railroad vehicle of claim 1 , wherein at least one fan, employed during operation of the combustion engine for dissipating heat from the first cooling circuit, is hydrostatically driven.

12. The railroad vehicle of claim 11 , wherein the at least one fan is driven by an electrical oil pump.

13. The railroad vehicle of claim 1 , further comprising an auxiliary coolant pump, which is preferably an electrical coolant pump, for pumping a coolant in at least a part of the first cooling circuit.

14. The railroad vehicle of claim 13 , wherein the auxiliary coolant pump is an electrical coolant pump.

15. The railroad vehicle of claim 14 , further comprising a bypassing mechanism to bypass a mechanically driven coolant pump of the combustion engine during pure electric operation of the railroad vehicle.

16. The railroad vehicle of claim 1 , wherein during pure electric operation of the railroad vehicle, either:

the coolant in the first cooling circuit circulates through the first cooling circuit via the same coolant flow path as during operation of the combustion engine, or

the coolant in the first cooling circuit circulates only through part of the first cooling circuit, compared to the coolant flow path during operation of the combustion engine.

17. The railroad vehicle of claim 1 , wherein during pure electric operation of the railroad vehicle, an engine block of the combustion engine is used as a heat sink for thermal energy from the traction transformer, wherein optionally coolant flow through the at least one radiator is partially, or preferably fully, blocked.

18. The railroad vehicle of claim 17 , wherein during pure electric operation of the railroad vehicle, a coolant flow through the at least one radiator is at least partially blocked.

19. The railroad vehicle of claim 1 , further comprising a controllably movable cover or hatch, wherein during pure electric operation of the railroad vehicle, at least a part of the at least one radiator is covered by the cover or hatch in a manner to reduce an aerodynamic resistance of the railroad vehicle.

20. A method for operating a dual-powered railroad vehicle, comprising:

dissipating heat from a combustion engine with a first cooling circuit; and/or

dissipating heat from a traction transformer with a second cooling circuit, the traction transformer operatively coupled to an electric grid to provide power to the dual-powered railroad vehicle during pure electric operation of the dual-powered railroad vehicle,

wherein heat from the combustion engine and heat from the traction transformer is dissipated via at least one radiator, and wherein the first cooling circuit is thermally coupled to the second cooling circuit via a heat exchanger situated outside of the at least one radiator and wherein only coolant of the first cooling circuit flows through the at least one radiator.