Energy recovery system for a mobile machine

1. An energy recovery system for a mobile machine, comprising:

a tank configured to store a liquid fuel for combustion within a main engine located on the locomotive;

a fuel delivery circuit connecting the tank to the main engine;

an auxiliary engine;

a boil-off circuit connecting the tank to the auxiliary engine;

an accumulator fluidly connected to the boil-off circuit between the tank and the auxiliary engine and configured to store gaseous fuel formed in the tank; and

a carbon adsorbent disposed within the accumulator and configured to adsorb the gaseous fuel,

wherein the auxiliary engine is configured to selectively generate a suction force to withdraw gaseous fuel adsorbed onto the carbon adsorbent.

2. The energy recovery system of claim 1 , further including an inlet valve configured to selectively pass gaseous fuel from the tank to the accumulator when a pressure of the tank exceeds a tank pressure threshold.

3. The energy recovery system of claim 2 , further including an outlet valve configured to selectively pass gaseous fuel from the accumulator toward the auxiliary engine when an amount of gaseous fuel stored in the accumulator exceeds a high capacity threshold.

4. The energy recovery system of claim 3 , further including a controller configured to:

determine the amount of gaseous fuel stored in the accumulator based on a cumulative opening time of the inlet valve since a last opening event of the outlet valve; and

activate the outlet valve based on the determined amount.

5. The energy recovery system of claim 4 , further including a control valve selectively movable by the controller to direct fuel from the tank toward only the main engine, toward only the auxiliary engine, or toward both the main engine and the auxiliary engine.

6. The energy recovery system of claim 5 , wherein the controller is further configured to move the control valve to direct fuel from the tank toward the auxiliary engine when the amount of gaseous fuel stored in the accumulator is below a low capacity threshold.

7. The energy recovery system of claim 4 , wherein the outlet valve is movable by the controller to selectively pass gaseous fuel from the accumulator to the auxiliary engine when the amount of gaseous fuel stored in the accumulator exceeds a low capacity threshold.

8. The energy recovery system of claim 4 , wherein the controller is configured to operate the auxiliary engine in a power generating mode when the amount of gaseous fuel stored in the accumulator the exceeds a high capacity threshold and an external load connected to the auxiliary engine has an electrical demand.

9. The energy recovery system of claim 4 , wherein the controller is configured to operate the auxiliary engine in a burn-off mode when the amount of gaseous fuel stored in the accumulator exceeds the high capacity threshold and an external load connected to the auxiliary engine has an electrical demand of about zero.

10. The energy recovery system of claim 4 , wherein the controller is configured to operate the auxiliary engine in an idle state during the burn-off mode.

11. The energy recovery system of claim 4 , wherein the controller is further configured to move the outlet valve to a flow-blocking position when an amount of stored gaseous fuel in the accumulator is below a low delivery threshold.

12. The energy recovery system of claim 11 , wherein the controller is further configured to move the outlet valve to the flow-blocking position based on a cumulative opening time of the outlet valve.

13. The energy recovery system of claim 11 , further including a sensor located between the accumulator and the auxiliary engine and configured to measure a concentration of gaseous fuel exiting the accumulator, wherein the controller is configured to move the outlet valve to the flow-blocking position based on the measured concentration.

14. A method of operating a mobile machine, comprising:

directing liquid fuel from a tank toward a main engine;

directing gaseous fuel formed in the tank through an accumulator toward an auxiliary engine;

adsorbing gaseous fuel on a carbon adsorbent disposed in the accumulator; and

withdrawing gaseous fuel adsorbed on the carbon adsorbent with a suction force generated by the auxiliary engine.

15. The method of claim 14 , further including operating the auxiliary engine in a power generating mode when an amount of adsorbed gaseous fuel exceeds a high capacity threshold and an external load connected to the auxiliary engine has an electrical demand.

16. The method of claim 14 , further including operating the auxiliary engine in a burn-off mode when an amount of adsorbed gaseous fuel exceeds a high capacity threshold and an external load connected to the auxiliary engine has an electrical demand of about zero.

17. The method of claim 16 , further including operating the auxiliary engine in an idle state during the burn-off mode.

18. The method of claim 14 , further including directing liquid fuel from the tank toward the auxiliary engine when an amount of adsorbed gaseous fuel is below a low capacity threshold.

19. The method of claim 14 , further including directing adsorbed gaseous fuel toward the auxiliary engine only when an amount of adsorbed gaseous fuel exceeds a low capacity threshold.

20. A train consist, comprising:

a locomotive having:

a frame;

a main engine mounted to the frame;

a plurality of wheels configured to support the frame and driven by the main engine; and

an auxiliary engine mounted to the frame;

a tender car having a tank configured to store a liquid fuel;

a boil-off circuit connecting the tank to the auxiliary engine;

an accumulator fluidly connected to the boil-off circuit between the tank and the auxiliary engine and configured to store gaseous fuel formed in the tank; and

a carbon adsorbent disposed within the accumulator and configured to adsorb the gaseous fuel, wherein the auxiliary engine is configured to selectively generate a suction force to withdraw gaseous fuel adsorbed onto the carbon adsorbent;

an inlet valve configured to selectively pass gaseous fuel from the tank to the accumulator when a pressure of the tank exceeds a tank pressure threshold; and

an outlet valve configured to selectively pass gaseous fuel from the accumulator toward the auxiliary engine when an amount of gaseous fuel stored in the accumulator exceeds a high capacity threshold.