Exhaust system having multiple dosers

1. An exhaust system, comprising:

a diffuser configured to receive exhaust from an engine;

a plurality of dosers associated with the diffuser and configured to inject fuel into the diffuser;

a plenum fluidly connected downstream of the diffuser;

a controller configured to determine a temperature of exhaust in the plenum and selectively control an amount of fuel injected by each of the plurality of dosers based on the determined temperature and a velocity of the exhaust adjacent to each doser; and

an aftertreatment component fluidly connected downstream of the plenum and configured to heat the exhaust by oxidizing the injected fuel.

2. The exhaust system of claim 1 , wherein a number of the plurality of dosers is 8 and wherein the dosers are disposed equidistant from each other across a width of the diffuser.

3. The exhaust system of claim 1 , wherein the plurality of dosers are distributed across a width of the diffuser.

4. The exhaust system of claim 3 , wherein the plurality of dosers are distributed across a portion of the width of the diffuser, the portion being smaller than the width of the diffuser.

5. The exhaust system of claim 3 , wherein one of the plurality of dosers is disposed on a side wall of the diffuser and the remaining dosers are distributed across the width of the diffuser.

6. The exhaust system of claim 5 , wherein the controller is configured to activate the plurality of dosers when a temperature of exhaust in the after-treatment component is below a regeneration temperature.

7. The exhaust system of claim 6 , wherein the controller is configured to determine a total amount of fuel required to raise the temperature of exhaust in the after-treatment component above the regeneration temperature based on a flow rate of exhaust in the diffuser.

8. The exhaust system of claim 7 , wherein the controller is configured to determine an amount of fuel to be injected by each doser based on the relative velocities of the exhaust adjacent to each of the plurality of dosers.

9. The exhaust system of claim 8 , wherein the controller is configured to direct a first doser selected from among the plurality of dosers to inject a different amount of fuel than a second doser selected from among the remaining plurality of dosers when a velocity of exhaust adjacent to the first doser is different from a velocity of exhaust adjacent to the second doser.

10. The exhaust system of claim 9 , wherein the after-treatment component includes:

a diesel oxidation catalyst configured to oxidize the injected fuel; and

a diesel particulate filter located downstream of the diesel oxidation catalyst.

11. A method of heating exhaust, the method comprising:

directing exhaust from an engine into a diffuser;

injecting fuel into the diffuser using a plurality of dosers;

directing the exhaust from the diffuser into a plenum;

determining a temperature of exhaust in the plenum;

selectively controlling, via a controller, an amount of fuel injected by each of the plurality of dosers based on the determined temperature and a velocity of the exhausted adjacent to each doser; and

heating the exhaust by oxidizing the injected fuel in an after-treatment component connected downstream of the plenum.

12. The method of claim 11 , further comprising:

determining a flow rate of exhaust in the diffuser;

determining a temperature of exhaust in the after-treatment component;

determining a total amount of fuel required to raise the temperature of exhaust above a regeneration temperature based on the determined flow rate and the determined temperature; and

injecting the determined total amount of fuel.

13. The method of claim 12 , further comprising:

determining relative amounts of fuel to be injected using each doser based on the determined velocity and the total amount of fuel required.

14. The method of claim 13 , wherein injecting includes injecting more fuel using a first doser at a first location than using a second doser at a second location.

15. The method of claim 14 , wherein heating includes:

oxidizing the injected fuel in the presence of a diesel oxidation catalyst; and

heating the exhaust using heat generated during oxidation of the injected fuel.

16. The method of claim 15 , further including:

determining a temperature of exhaust in the after-treatment component after injecting fuel into the diffuser; and

halting fuel injection when the temperature of exhaust in the after-treatment component is above the regeneration temperature.

17. A machine, comprising:

an engine having a plurality of cylinders;

a diffuser configured to receive exhaust from the plurality of cylinders;

a plurality of dosers configured to inject fuel into the diffuser;

a plenum fluidly connected downstream of the diffuser;

a temperature sensor configured to determine a temperature of exhaust in the plenum;

a controller configured to selectively control an amount of fuel injected by each of the plurality of dosers based on the determined temperature and a velocity of exhaust adjacent to each closer; and

an after-treatment component fluidly connected downstream of the diffuser and configured to heat the exhaust by oxidizing the injected fuel.

18. The machine of claim 17 , wherein the plurality of dosers are disposed across a width of the diffuser.

19. The machine of claim 18 , wherein the controller is configured to determine a total amount of fuel required to raise the temperature of exhaust in the after-treatment component above the regeneration temperature based on a flow rate of exhaust in the diffuser.

20. The machine of claim 19 , wherein the controller is configured to determine an amount of fuel to be injected by each doser based on the relative velocities of exhaust adjacent to each of the plurality of dosers.