Method of prediction of NOx mass flow in exhaust

• US 7,155,331 B1
• Filed: 12/14/2004
• Issued: 12/26/2006
• Est. Priority Date: 12/15/2003
• Status: Expired due to Fees

• Current Assignee: Donaldson Company Incorporated
• Original Assignee: Donaldson Company Incorporated
• Inventors: Zhang, Wenzhong, Angelo, Theodore G.
• Primary Examiner(s): Vo, Hieu T.
• Application Number:
  US11/012,075
• Time in Patent Office: 742 Days
• Field of Search: 701/108, 701/109, 701/114, 602/74, 602/85, 602/86, 602/99, 603/01
• US Class Current: 701/108
• CPC Class Codes: F01N 3/0821 combined with particulate filters catalysed diesel particulate filters F01N3/035
• CPC Class Codes: F01N 3/206 Adding periodically or continuously substances to exhaust gases for promoting purification, e.g. catalytic material in liquid form, NOx reducing agents F01N3/2066 takes precedence
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

Methods for estimating the mass flow rate of NOx in an exhaust stream by correlating the level of NOx to an engine parameter. The level of NOx can be estimated as a function of engine power, of intake pressure, of exhaust temperature, as a function of the percentage of O₂ in the exhaust stream, or as a combination of any of these. Once the level of NOx is approximately known, the exhaust system of the engine system can be modified to improve the removal efficiency of NOx and exhaust particulate matter from the exhaust stream. These methods for estimating the NOx mass flow rate can be used for an exhaust configuration that includes a lean NOx catalyst (LNC), a selective catalytic reduction (SCR) catalyst, or a lean NOx trap (LNT). A particulate filter can be present in the exhaust configuration.

Claims

1. A method for estimation of a NOx mass flow rate in a diesel engine exhaust stream, the method comprising:

(a) using a mathematical function to estimate the NOx mass flow rate, the mathematical function being one of;

(i) Y=K₁X₁+K₂, where Y is the estimated NOx mass flow level in mmol/second, X₁ is the engine output in horsepower, K₁ is a first constant, and K₂ is a second constant;

(ii) Y=K₃X₂+K₄, where Y is the estimated NOx mass flow level in mmol/second, X₂ is the engine intake pressure in PSI, K₃ is a third constant, and K₄ is a fourth constant;

(iii) Y=K₅e^K6X3, where Y is the estimated NOx mass flow level in mmol/second, X₃ is the engine'"'"'s turbo-outlet temperature in degrees Celsius, K₅ is a fifth constant, and K₆ is a sixth constant; and

(iv) Y=K₇e^K8X4, where Y is the estimated NOx mass flow level in mmol/second, X₄ is the percentage of oxygen in the engine'"'"'s outlet exhaust stream, K₇ is a seventh constant, and K₈ is an eighth constant.

2. A method according to claim 1, wherein K₁ is about 0.020 to 0.040, and K₂ is about 0.50 to 2.0.

3. A method according to claim 2, wherein K₁ is about 0.025 to 0.035, and K₂ is about 0.50 to 1.10.

4. A method according to claim 1, wherein K₃ is about 0.030 to 0.050, and K₄ is about 0.30 to 0.90.

5. A method according to claim 4, wherein K₃ is about 0.035 to 0.045, and K₄ is about 0.40 to 0.80.

6. A method according to claim 1, wherein K₅ is about 0.010 to 0.20, and K₆ is about 0.0090 to 0.020.

7. A method according to claim 6, wherein K₅ is about 0.015 to 0.10, and K₆ is about 0.0090 to 0.012.

8. A method according to claim 1, wherein K₇ is about 30 to 100, and K₈ is about −

0.18 to −

0.40.

9. A method according to claim 8, wherein K₇ is about 38 to 95, and K₈ is about −

0.20 to −

0.33.

10. A method according to claim 1, further comprising using the estimated NOx mass flow rate as a parameter in controlling an exhaust treatment operation.

11. A method according to claim 10, wherein the exhaust treatment operation includes injection of reductants into the exhaust stream.

12. A method according to claim 10, wherein the exhaust treatment operation includes injection of hydrocarbons into the exhaust stream.

13. A method according to claim 10, wherein the exhaust treatment operation includes regeneration of an exhaust component.

14. A method of retrofitting an emission reduction system to an in-use, existing engine, the method comprising:

(a) providing a sensor to measure a selected engine parameter of the in-use, existing engine and using a mathematical function of the selected engine parameter to estimate a NOx mass flow rate, the mathematical function being one of;

(i) Y=K₁X₁+K₂, where Y is the estimated NOx mass flow level in mmol/second, X₁ is the engine output in horsepower, K₁ is a first constant, and K₂ is a second constant;

(ii) Y=K₃X₂+K₄, where Y is the estimated NOx mass flow level in mmol/second, X₂ is the engine intake pressure in PSI, K₃ is a third constant, and K₄ is a fourth constant;

(iii) Y=K₅e^K6X3, where Y is the estimated NOx mass flow level in mmol/second, X₃ is the engine'"'"'s turbo-outlet temperature in degrees Celsius, K₅ is a fifth constant, and K₆ is a sixth constant; and

(iv) Y=K₇e^K8X4, where Y is the estimated NOx mass flow level in mmol/second, X₄ is the percentage of oxygen in the engine'"'"'s outlet exhaust stream, K₇ is a seventh constant, and K₈ is an eighth constant; and

(b) using the estimated NOx mass flow rate as a parameter in controlling an exhaust treatment operation.

15. A method according to claim 14, wherein the exhaust treatment operation includes injection of reductants into the exhaust stream.

16. A method according to claim 14, wherein the exhaust treatment operation includes injection of hydrocarbons into the exhaust stream.

17. A method according to claim 14, wherein the exhaust treatment operation includes regeneration of an exhaust component.