System and method for reduced nitrous oxide emissions using predictive urea dosing control
AssigneeSouthwest Research Institute
InventorsVenkata R. Chundru, Sankar B. Rengarajan, Jayant V. Sarlashkar, Scott Hotz
Life of this patent
Estimating the term…
Abstract
In an approach to reduce nitrous oxide emissions using predictive urea dosing control, a route is determined. A set of target coverage fractions of ammonia is determined over a set of steps for the route, where the coverage fraction of ammonia is a ratio of stored ammonia to a maximum storage capacity of ammonia in a selective catalytic reduction (SCR) device. An actual coverage fraction of ammonia is determined for each step of the route. The actual coverage fraction of ammonia is compared to the target coverage fraction of ammonia for each step. The urea injection rate is adjusted based on a cost function.
Claims13
A system for reducing nitrous oxide (NOx) emissions in an aftertreatment system of a vehicle, the system comprising:
- one or more computer processors;
- one or more computer readable storage media;
- and
- program instructions stored on the one or more computer readable storage media for execution by at least one of the one or more computer processors, the stored program instructions including instructions to:
- determine a route for a trip for the vehicle;
- determine a predicted power demand for the vehicle, for each step of a set of steps for the route, based on the determined route, predicted traffic density and predicted vehicle speed;
- determine predicted vehicle dynamics that includes engine speed in revolutions per minute (RPM), torque and gear number for each step in the set of steps for the route based on the predicted power demand;
- determine predicted exhaust flow rate, temperature, and NOx concentration for each step in the set of steps for the route based on the predicted vehicle dynamics;
- determine, for each step in the set of steps for the route, predicted inlet conditions for a selective catalytic reduction (SCR) device associated with the aftertreatment system of the vehicle;
- the predicted inlet conditions includes a predicted NO2/NOx ratio, the predicted exhaust temperature, and the predicted exhaust flow rate;
- determine a target coverage fraction of ammonia in the SCR for each step of a set of steps for the route, based on a predicted NOx flux and exhaust temperature;
- wherein the target coverage fraction of ammonia is determined prior to a start of the trip;
- determine, during operation of the vehicle along the route, an actual coverage fraction of ammonia in the catalyst for each step of the set of steps for the route;
- compare the actual coverage fraction of ammonia to the target coverage fraction of ammonia for each step of the set of steps;
- determine a cost function based on maximizing an NOx conversion, reducing a consumption of urea, and maximizing a light-off SCR device for proper operation of a catalyzed particulate filter (CPF);
- wherein the cost function is determined according to:
- J
- =
- {
- ∑
- i
- =
- 1
- i
- =
- nu
-
- θ
- Target
- ,
- Final
- -
- θ
- 1
- ,
- k
- +
- i
-
- 2
- 2
- +
- λ
-
- ∑
- i
- =
- 0
- i
- =
- nu
- -
- 1
-
- Δ
-
- C
- NH
- 3
- ,
- k
- +
- i
-
- 2
- 2
- +
- λ
- 2
-
- ∑
- i
- =
- 0
- i
- =
- nu
- -
- 1
-
- Δ
-
- C
- NO
- x
- ,
- i
- ,
- SCR
-
- _
-
- in
- -
- Δ
-
- C
- NO
- x
- ,
- i
- ,
- SCR_out
-
- 2
- 2
- }
- wherein
- ∑
- i
- =
- 1
- i
- =
- nu
-
- θ
- Target
- ,
- Final
- -
- θ
- 1
- ,
- k
- +
- i
-
- 2
- 2
- is a control horizon cost,
- λ
-
- ∑
- i
- =
- 0
- i
- =
- nu
- -
- 1
-
- Δ
-
- C
- NH
- 3
- ,
- k
- +
- i
-
- 2
- 2
- is a urea injection rate cost, and
- +
- λ
- 2
-
- ∑
- i
- =
- 0
- i
- =
- nu
- -
- 1
-
- Δ
-
- C
- NO
- x
- ,
- i
- ,
- SCR
-
- _
-
- in
- -
- Δ
-
- C
- NO
- x
- ,
- i
- ,
- SCR_out
-
- 2
- 2
- is an NOx maximizing cost at the CPF inlet;
- and
- adjust a urea injection rate based on the determined cost function.
A tangible storage device that includes machine-readable instructions that, when executed by one or more processors, cause the one or more processors to perform operations for reducing nitrous oxide (NOx) emissions in an aftertreatment system, the operations comprising:
- determine a route for a trip for the vehicle;
- determine a predicted power demand for the vehicle, for each step of a set of steps for the route, based on the determined route, predicted traffic density and predicted vehicle speed;
- determine predicted vehicle dynamics that includes engine speed in revolutions per minute (RPM), torque and gear number for each step in the set of steps for the route based on, at least in part, the predicted power demand;
- determine predicted exhaust flow rate, temperature, and NOx concentration for each step in the set of steps for the route based on the predicted vehicle dynamics;
- determine, for each step in the set of steps for the route, predicted inlet conditions for a selective catalytic reduction (SCR) device associated with the aftertreatment system of the vehicle;
- the predicted inlet conditions includes a predicted NO2/NOx ratio, the predicted exhaust temperature, and the predicted exhaust flow rate;
- determine a target coverage fraction of ammonia in the SCR for each step of a set of steps for the route, based on a predicted NOx flux and exhaust temperature;
- wherein the target coverage fraction of ammonia is determined prior to a start of the trip;
- determine, during operation of the vehicle along the route, an actual coverage fraction of ammonia in the SCR for each step of the set of steps for the route;
- compare the actual coverage fraction of ammonia to the target coverage fraction of ammonia for each step of the set of steps;
- determine a cost function based on maximizing an NOx conversion, reducing a consumption of urea, and maximizing a light-off SCR device for proper operation of a catalyzed particulate filter (CPF);
- wherein the cost function is determined according to:
- J
- =
- {
- ∑
- i
- =
- 1
- i
- =
- nu
-
- θ
- Target
- ,
- Final
- -
- θ
- 1
- ,
- k
- +
- i
-
- 2
- 2
- +
- λ
-
- ∑
- i
- =
- 0
- i
- =
- nu
- -
- 1
-
- Δ
-
- C
- NH
- 3
- ,
- k
- +
- i
-
- 2
- 2
- +
- λ
- 2
-
- ∑
- i
- =
- 0
- i
- =
- nu
- -
- 1
-
- Δ
-
- C
- NO
- x
- ,
- i
- ,
- SCR
-
- _
-
- in
- -
- Δ
-
- C
- NO
- x
- ,
- i
- ,
- SCR_out
-
- 2
- 2
- }
- wherein
- ∑
- i
- =
- 1
- i
- =
- nu
-
- θ
- Target
- ,
- Final
- -
- θ
- 1
- ,
- k
- +
- i
-
- 2
- 2
- is a control horizon cost,
- λ
-
- ∑
- i
- =
- 0
- i
- =
- nu
- -
- 1
-
- Δ
-
- C
- NH
- 3
- ,
- k
- +
- i
-
- 2
- 2
- is a urea injection rate cost, and
- +
- λ
- 2
-
- ∑
- i
- =
- 0
- i
- =
- nu
- -
- 1
-
- Δ
-
- C
- NO
- x
- ,
- i
- ,
- SCR
-
- _
-
- in
- -
- Δ
-
- C
- NO
- x
- ,
- i
- ,
- SCR_out
-
- 2
- 2
- is an NOx maximizing cost at the CPF inlet;
- and
- adjust a urea injection rate based on the determined cost function.
Dependencies are inferred from the claim text.