OPTICAL SENSING OF NOx AND AMMONIA IN AFTERTREATMENT SYSTEMS

Abstract

An aftertreatment system configured to reduce constituents of an exhaust gas produced by an engine comprises an aftertreatment component and an optical assembly. The optical assembly comprises an optical emitter configured to emit light onto a face of the aftertreatment component, and an optical detector configured to detect light reflected from the face of the aftertreatment component. A controller is configured to determine at least one of an amount of NOx gases or an amount of ammonia on the face of the aftertreatment component based on an optical parameter of the detected light that has reflected from the face of the aftertreatment component.

1 . An aftertreatment system configured to reduce constituents of an exhaust gas produced by an engine, comprising:
 an aftertreatment component;   an optical assembly comprising:
 an optical configured to emit light onto a face of the aftertreatment component, and 
 an optical detector configured to detect light reflected from the face of the aftertreatment component; and 
   a controller configured to determine at least one of an amount of NO x  gases or an amount of ammonia on the face of the aftertreatment component based on an optical parameter of the detected light that has reflected from the face of the aftertreatment component.   
     
     
         2 . The aftertreatment system of  claim 1 , wherein the controller is configured to determine the at least one of the amount of NO x  gases or the amount of ammonia on the face of the aftertreatment component based on a difference between a parameter of the light emitted from the optical emitter and a parameter of the detected light that has reflected from the face of the aftertreatment component. 
     
     
         3 . The aftertreatment system of  claim 1 , wherein the emitted light has a wavelength in the infrared (IR) range. 
     
     
         4 . The aftertreatment system of  claim 1 , wherein the emitted light has a wavelength in the ultraviolet-visible (UV-vis) range. 
     
     
         5 . The aftertreatment system of  claim 1 , wherein the face of the aftertreatment component is one of an inlet face structured to receive the exhaust gas, or an outlet face structured to expel exhaust gas. 
     
     
         6 . The aftertreatment system of  claim 5 , wherein the aftertreatment component comprises a selective catalytic reduction catalyst. 
     
     
         7 . The aftertreatment system of  claim 1 , further comprising:
 an upstream aftertreatment component disposed upstream of the aftertreatment component,   wherein the aftertreatment component comprises an ammonia oxidation catalyst and the upstream aftertreatment component comprises a selective catalytic reduction catalyst.   
     
     
         8 . The aftertreatment system of  claim 1 , wherein the optical emitter is disposed at a first location of the aftertreatment system, and the optical detector is disposed at a second location of the aftertreatment system that is opposite the first location. 
     
     
         9 . The aftertreatment system of  claim 1 , wherein the controller is further configured to determine an amount of NO x  gases and/or an amount of ammonia absorbed over an entire volume of the aftertreatment component based on the determined amount of NO x  gases and/or ammonia on the face of the aftertreatment component. 
     
     
         10 . The aftertreatment system of  claim 9 , further comprising:
 a reductant insertion assembly configured to insert a reductant into the exhaust gas flowing through the aftertreatment system,   wherein the aftertreatment component comprises a selective catalytic reduction system, and   wherein the controller is operatively coupled to the reductant insertion assembly, the controller further configured to, in response to determining that an amount of ammonia absorbed over the entire volume of the aftertreatment component is below an ammonia storage threshold, instruct the reductant insertion assembly to insert reductant into the exhaust gas.   
     
     
         11 . The aftertreatment system of  claim 10 , wherein the controller is further configured to, in response to determining that an amount of NO x  on the face of the aftertreatment component is above a NO x  threshold, instruct the reductant insertion assembly to insert reductant into the exhaust gas. 
     
     
         12 . The aftertreatment system of  claim 9 , further comprising:
 a reductant insertion assembly configured to insert a reductant into the exhaust gas flowing through the aftertreatment system,   wherein the aftertreatment component comprises an ammonia oxidation catalyst, and wherein the controller is operatively coupled to the reductant insertion assembly, the controller further configured to, in response to determining that an amount of ammonia absorbed over the entire volume of the aftertreatment component is above an ammonia threshold, instruct the reductant insertion assembly to stop inserting reductant into the exhaust gas.   
     
     
         13 . The aftertreatment system of  claim 1 , wherein the controller is further configured to calibrate an optical parameter value determined by the optical detector based on at least one of an exhaust gas temperature, an exhaust gas flow rate, an exhaust gas pressure, or an amount of water in the exhaust gas. 
     
     
         14 . An aftertreatment system configured to reduce constituents of an exhaust gas produced by an engine, comprising:
 a housing;   an aftertreatment component disposed in the housing;
 an optical assembly comprising: 
 an optical emitter configured to emit light through the exhaust gas, and an optical detector configured to detect light that has passed through the exhaust gas; and 
   a controller configured to determine an amount of ammonia in the exhaust gas based on an optical parameter of the detected light that has passed through the exhaust gas,   wherein the optical emitter and the optical detector are disposed at a first location of the housing, and wherein the optical assembly further comprises a first mirror disposed at a second location of the housing that is opposite the first location, the first mirror configured to reflect light received from the optical emitter towards the optical detector.   
     
     
         15 . The aftertreatment system of  claim 14 , wherein the controller is configured to determine the amount of ammonia in the exhaust gas based on a difference between a parameter of the light emitted from the optical emitter and a parameter of the detected light that has passed through the exhaust gas. 
     
     
         16 . The aftertreatment system of  claim 15 , wherein the emitted light has a wavelength in the infrared (IR) range. 
     
     
         17 . The aftertreatment system of  claim 15 , wherein the emitted light has a wavelength in the ultraviolet-visible (UV-vis) range. 
     
     
         18 . (canceled) 
     
     
         19 . The aftertreatment system of  claim 18 , wherein the optical assembly further comprises a second mirror disposed at the first location around the optical emitter and the optical detector, the second mirror configured to reflect at least a portion of the light received from the first mirror back towards the first mirror. 
     
     
         20 . The aftertreatment system of  claim 19 , further comprising a sampling tube extending from the first mirror to the second mirror, a plurality of holes defined through a wall of the sampling tube and configured to allow a portion of the exhaust gas to pass through the sampling tube.