Exhaust emission prediction system and method

Abstract

An exhaust emission prediction system includes an engine configured to generate a flow of exhaust and a controller configured to determine a first estimation of an amount of an emissions constituent at a first location using an empirical model. The first location is downstream of the engine. The controller is also configured to determine a second estimation of the amount of the emissions constituent at the first location using a physics-based model and determine a third estimation of the amount of the emissions constituent at the first location based on at least one of the first estimation or the second estimation.

What is claimed is: 
     
         1 . An exhaust emission prediction system comprising:
 an engine configured to generate a flow of exhaust; and   a controller configured to:
 determine a first estimation of an amount of an emissions constituent at a first location using an empirical model, the first location being downstream of the engine; 
 determine a second estimation of the amount of the emissions constituent at the first location using a physics-based model; and 
 determine a third estimation of the amount of the emissions constituent at the first location based on at least one of the first estimation or the second estimation. 
   
     
     
         2 . The exhaust emission prediction system of  claim 1 , wherein:
 the empirical model is trained using at least one trained operating condition; and   the controller is further configured to determine an operating condition of the engine and determine the third estimation based on whether the at least one trained operating condition for the empirical model includes the operating condition of the engine.   
     
     
         3 . The exhaust emission prediction system of  claim 2 , wherein:
 when the at least one trained operating condition for the empirical model includes the operating condition of the engine, the controller is configured to determine the third estimation based at least in part on the first estimation; and   when the at least one trained operating condition for the empirical model does not include the operating condition of the engine, the controller is configured to determine the third estimation based at least in part on the second estimation.   
     
     
         4 . The exhaust emission prediction system of  claim 3 , wherein, when the at least one trained operating condition for the empirical model includes the operating condition of the engine, the controller is configured to determine that the third estimation is equal to the first estimation. 
     
     
         5 . The exhaust emission prediction system of  claim 3 , wherein, when the at least one trained operating condition for the empirical model does not include the operating condition of the engine, the controller is configured to determine that the third estimation is equal to the second estimation. 
     
     
         6 . The exhaust emission prediction system of  claim 3 , wherein, when the at least one trained operating condition for the empirical model does not include the operating condition of the engine, the controller is configured to determine the third estimation based on the first estimation and the second estimation. 
     
     
         7 . The exhaust emission prediction system of  claim 2 , wherein the operating condition includes at least one of an altitude, an ambient temperature, an engine speed, an ambient pressure, an application cycle, an engine configuration, or a fuel injection system calibration. 
     
     
         8 . The exhaust emission prediction system of  claim 1 , wherein the empirical model includes a neural network model or a curve fitting model. 
     
     
         9 . The exhaust emission prediction system of  claim 1 , wherein, to determine the first estimation, the controller is configured to input into the empirical model at least one of a speed of the engine, a fuel injection timing of the engine, an amount of fuel injected into the engine, a pressure of the fuel injected into the engine, a pressure in an intake manifold of the engine, a temperature in the intake manifold, or an amount of exhaust recirculated into the engine. 
     
     
         10 . The exhaust emission prediction system of  claim 1 , wherein the controller is further configured to determine at least one in-cylinder characteristic of at least one cylinder of the engine using the physics-based model and determine the second estimation using the at least one in-cylinder characteristic. 
     
     
         11 . The exhaust emission prediction system of  claim 10 , wherein the at least one in-cylinder characteristic includes at least one of a pressure, a bulk gas temperature, a bulk gas specific heat, a bulk gas density, a bulk gas mass, or a total heat transfer to the flow of exhaust. 
     
     
         12 . The exhaust emission prediction system of  claim 1 , wherein, to determine the second estimation, the controller is configured to input into the physics-based model at least one of a speed of the engine, a crank angle of the engine, an air flow rate into the engine, a fuel flow rate into the engine, a pressure in the engine, a temperature in the engine, or a volume percent of recirculated exhaust gas in the engine. 
     
     
         13 . The exhaust emission prediction system of  claim 1 , wherein the emissions constituent includes NOx. 
     
     
         14 . The exhaust emission prediction system of  claim 13 , further comprising:
 at least one NOx sensor disposed downstream of the engine and configured to output a measured amount of NOx;   wherein the controller is in communication with the at least one NOx sensor and further configured to adjust the third estimation based on the measured amount.   
     
     
         15 . A method of predicting an amount of NOx in a flow of exhaust from an engine using a controller, the method comprising:
 determining, using the controller, a first estimation of the amount of NOx at a first location using an empirical model, the first location being downstream of the engine;   determining, using the controller, a second estimation of the amount of NOx at the first location using a physics-based model; and   determining, using the controller, a third estimation of the amount of NOx at the first location based on at least one of the first estimation or the second estimation.   
     
     
         16 . The method of  claim 15 , further comprising:
 determining an ambient humidity;   wherein the first estimation is further determined, using the controller, based on the ambient humidity.   
     
     
         17 . The method of  claim 15 , further comprising:
 determining, using the controller, an operating condition of the engine;   wherein the empirical model is trained using at least one trained operating condition;   wherein the third estimation is further determined, using the controller, based at least in part on the first estimation when the at least one trained operating condition for the empirical model includes the operating condition of the engine; and   wherein the third estimation is further determined, using the controller, based at least in part on the second estimation when the at least one trained operating condition for the empirical model does not include the operating condition of the engine.   
     
     
         18 . An engine system comprising:
 an engine configured to generate a flow of exhaust;   an injector configured to inject a reductant into the flow of exhaust;   a catalytic device configured to receive the flow of exhaust after being injected with the reductant;   a processor;   a memory module configured to store instructions that, when executed, enable the processor to:
 determine a first estimation of an amount of NOx at a first location using an empirical model, the first location being downstream of the engine and upstream of the catalytic device; 
 determine a second estimation of the amount of NOx at the first location using a physics-based model; 
 determine a third estimation of the amount of NOx at the first location based on at least one of the first estimation or the second estimation; and 
 adjust an amount of the reductant injected by the injector based on the determined third estimation. 
   
     
     
         19 . The engine system of  claim 18 , further comprising a turbine upstream of the injector and configured to receive the flow of exhaust, wherein the first location is downstream of the turbine. 
     
     
         20 . The engine system of  claim 18 , wherein:
 the memory module is further configured to store instructions that, when executed, enable the processor to:   determine an operating condition of the engine;   determine the third estimation based at least in part on the first estimation when the at least one trained operating condition for the empirical model includes the operating condition of the engine; and   determine the third estimation based at least in part on the second estimation when the at least one trained operating condition for the empirical model does not include the operating condition of the engine.