Emission control systems and methods

Abstract

Emission control systems, apparatus, and methods for engines. The emission control systems, apparatus, methods can mitigate the release of undesirable emission from a vehicle while optimizing fuel economy. The emission control system includes an upstream SCR and a downstream SCR. The methods disclosed herein include generating a performance model for the upstream SCR. The methods and systems disclosed herein include controlling sulfur regeneration based on the performance model for the upstream SCR. The methods and systems disclosed herein include determining a maximum DEF dosing quantity or rate at the downstream SCR and determining a DEF dosing quantity or rate at the upstream SCR based on the maximum DEF dosing quantity or rate at the downstream SCR. In some examples, the disclosed emission control systems, apparatus, and methods can have improved fuel efficiency relative to conventional emission control systems.

Description

EMISSION CONTROL SYSTEMS AND METHODSCROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to, and the benefit of, United States Provisional Application No. 63 / 772,184 filed on March 14, 2025 and entitled “EMISSION CONTROL SYSTEMS AND METHODS,” United States Provisional Application No. 63 / 772,193 filed on March 14, 2025 and entitled “EMISSION CONTROL SYSTEMS AND METHODS,” and United States Provisional Application No. 63 / 772,201 filed on March 14, 2025 and entitled “EMISSION CONTROL SYSTEMS AND METHODS,” the contents of which are hereby incorporated by reference in their entireties.FIELD

[0002] This disclosure generally relates to emission control systems, apparatus, and methods for engines, for example, diesel engine emission control systems, apparatus, methods for mitigating the release of undesirable emission and optimizing fuel economy.BACKGROUND

[0003] A vehicle typically includes an engine and an emission control system for controlling exhaust of undesirable emission from the engine. For example, a diesel engine emission control system can be designed to mitigate release of such undesirable emission generated during operation of the engine. An emission control system can include a diesel oxidation catalyst (DOC) for oxidizing carbon monoxide (CO), nitrogen monoxide (NO), and unburned hydrocarbons (HC) into carbon dioxide (CO2), nitrogen dioxide (NO2), and water (H2O). An emission control system can further include a diesel particulate filter (DPF) for trapping particulate matter or soot from the exhaust stream. The DPF can undergo periodic regeneration to burn off excess soot. During regeneration, the DPF is heated to a very high temperature, allowing the trapped soot to oxidize and turn into CO2 and / or ash, which can then be expelled from the filter. This process helps to restore the DPF’s capacity to trap more particulate matter, ensures the vehicle continues to meet emission standards, and maintains the overall health of the diesel engine.

[0004] The emission control system can further include a selective catalytic reduction (SCR) system, wherein a urea-based solution, commonly known as diesel exhaust fluid (DEF), is injected into the exhaust stream. The DEF undergoes thermal decomposition to produce- 1 - AFSDOCS:305402722.1ammonia (NH3), which then reacts with NOx in the presence of a catalyst to form nitrogen (N2) and water vapor (H2O).

[0005] Sulfur in diesel fuel can produce sulfur dioxide (SO2) and sulfate (SO4) particulate matter during combustion. Sulfur-containing deposits, such as ammonium sulfate (NH4HSO4) and ammonium bisulfate ((NH4)2SO4), can form on catalysts like X^Os-WOs / TiCE during SCR-DeNOx processes. These deposits can block the catalyst's surface and pores, reducing its efficiency in removing NOx from exhaust gases. The catalyst can undergo periodic regeneration to burn off excess sulfur-containing deposits. During regeneration, the SCR is heated to a high temperature, usually in a range of 500°C to 600°C, or a temperature greater than 600°C. The elevated temperature causes the sulfur compounds to decompose and be released from the SCR as sulfur dioxide (SO2). By regenerating the SCR, the catalysts in the SCR system can remain effective in reducing undesirable emission. In some examples, an emission control system can include a sulfur trap which can be utilized to capture sulfur compounds from the exhaust gases, thereby preventing the sulfur from reaching and deactivating the catalyst. When included, the sulfur trap can also undergo regeneration.SUMMARY

[0006] Described herein are emission control systems, apparatus, and methods for engines, such as, for example, emission control systems for vehicles with diesel engines. The disclosed emission control systems, apparatus, methods can mitigate the release of undesirable emission from the vehicle while optimizing fuel economy. In some examples, the emission control system includes an upstream SCR and a downstream SCR. In some examples, its position with the emission control system and / or its structure / chemistry of the upstream SCR can result in the upstream SCR having a greater exposure to sulfur oxides and / or a greater susceptibility to sulfur poisoning (i.e., excessive adsorption of sulfur-containing deposits that degrades the intended operation of the SCR) relative the downstream SCR. In some examples, methods disclosed herein can include generating a performance model for the upstream SCR. In some examples, methods disclosed herein can include controlling regeneration (e.g., sulfur regeneration) based on the performance model for the upstream SCR. In some examples, methods disclosed herein can include determining a maximum DEF dosing quantity or rate at the downstream SCR and determining a DEF dosing quantity or rate at the upstream SCR based on the maximum DEF dosing quantity or rate at the downstream SCR. In some examples, the disclosed emission - 2 - AFSDOCS:305402722.1control systems, apparatus, and methods can have improved fuel efficiency relative to conventional emission control systems.

[0007] In some examples, an emission control system for an engine includes an upstream SCR, a downstream SCR, and a computerized controller.

[0008] In some examples, a method of generating a performance model for an upstream SCR in an emission control system including the upstream SCR and a downstream SCR includes: generating first data modeling sulfur poisoning and recovery of the upstream SCR; generating second data modeling long-term sulfation effects on the upstream SCR; generating third data modeling DEF dosing effects on sulfation of the upstream SCR; and generating, based the first, second, and third data, one or more algorithms for the performance model of the upstream SCR.

[0009] In some examples, an emission control system includes an upstream SCR, a downstream SCR, and a computerized controller including a data communication interface, one or more processors, a memory having a plurality of computer-readable instructions stored thereon. In some examples, the plurality of computer-readable instructions configured to, when executed by the one or more processors, cause the system to: receive, from one or more sensors via the data communication interface, one or more operating parameters related to the upstream SCR; input the one or more operating parameters into an upstream SCR performance model; based on the input the one or more operating parameters into the upstream SCR performance model: determine whether an NOx conversion health sulfur regeneration criteria is met; determine whether an accumulated sulfur regeneration criteria is met; and determine whether a time-based sulfur regeneration criteria is met; and based at least on a determination that one or more of the NOx conversion health sulfur regeneration criteria, the accumulated sulfur regeneration criteria, or the time-based sulfur regeneration criteria are met, cause the emission control system to perform sulfur regeneration.

[0010] In some examples, an emission control system includes an upstream SCR, a downstream SCR, and a computerized controller including a data communication interface, one or more processors, a memory having a plurality of computer-readable instructions stored thereon. In some examples, the plurality of computer-readable instructions configured to, when executed by the one or more processors, cause the system to: receive, from one or more sensors via the data communication interface, one or more operating parameters related to the downstream SCR and one or more operating parameters related to the upstream SCR; based at least on the one or more - 3 - AFSDOCS:305402722.1operating parameters related to the downstream SCR, determine a maximum NOx conversion capability at the downstream SCR; based at least on the maximum NOx conversion capability at the downstream SCR, determine a percentage of NOx to be converted at the upstream SCR; based at least on the percentage of NOx to be converted at the upstream SCR, determine a first dosing control value for the upstream SCR and a second dosing control value for the downstream SCR; based at least on the first dosing control value for the upstream SCR, cause DEF dosing at a first amount at the upstream SCR; and based at least on the second dosing control value for the downstream SCR, cause DEF dosing at a second amount at the downstream SCR.

[0011] The foregoing and other objects, features, and advantages of the disclosed technology will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a block diagram of an exemplary emission control system including upstream and downstream selective catalytic converters (SCRs), according to the present disclosure.

[0013] FIG. 2A is a logical flow diagram of an exemplary high-level method of generating a performance model for an upstream SCR and operating an emission control system, such as the emission control system shown in FIG. 1 according to the present disclosure.

[0014] FIG. 2B is a functional diagram of an exemplary control modules that can be utilized with the method of FIG. 2A according to the present disclosure.

[0015] FIG. 3 is a logical flow diagram of an exemplary method for generating a performance model of an upstream SCR according to the present disclosure.

[0016] FIGS. 4-9 are exemplary graphical data illustrating modeling of sulfur poisoning and recovery of an upstream SCR according to the present disclosure.

[0017] FIGS. 10-13B are exemplary graphical data illustrating modeling of long-term sulfation effects on an upstream SCR according to the present disclosure.

[0018] FIG. 14A-15C are exemplary graphical data illustrating modeling of DEF dosing effects on sulfation of an upstream SCR according to the present disclosure.

[0019] FIG. 16 is a table illustrating exemplary factors related to SO2 deposition at an upstream SCR according to the present disclosure.

[0020] FIG. 17A is an exemplary algorithm for an upstream SCR sulfur storage model according to the present disclosure.- 4 - AFSDOCS:305402722.1

[0021] FIGS. 17B-17D are exemplary graphical data illustrating the upstream SCR sulfur storage model according to the present disclosure.

[0022] FIG. 18 is an exemplary algorithm for an upstream SCRNOx conversion health model according to the present disclosure.

[0023] FIGS. 19A-19D are exemplary graphical data illustrating model validation for soot regeneration according to the present disclosure.

[0024] FIGS. 20A-20D are exemplary graphical data illustrating model validation for sulfur according to the present disclosure.

[0025] FIGS. 21-24 are logical flow diagrams illustrating exemplary methods for utilizing an upstream SCR performance model to determine sulfur regeneration according to the present disclosure.

[0026] FIGS. 25-26 are logical flow diagrams illustration exemplary regeneration methods the emission control system of FIG. 1 according to the present disclosure.

[0027] FIG. 27 is an exemplary truth table for implementing soot and sulfur regeneration control strategies according to the present disclosure.

[0028] FIG. 28 is an exemplary control matrix for soot and sulfur zone classifications and associated user notifications according to the present disclosure.

[0029] FIGS. 29A-29B are illustrations of exemplary user notifications for soot and sulfur regeneration depending on soot and sulfur zone classifications according to the present disclosure.

[0030] FIG. 30 is a functional diagram of the control matrix of FIG. 28 and the upstream SCR performance model of FIG. 2B according to the present disclosure.

[0031] FIGS. 31-32 are logical flow diagrams of exemplary methods for controlling diesel exhaust fluid (DEF) dosing to upstream and downstream SCRs according to the present disclosure.

[0032] FIG. 33 is a schematic illustration of an exemplary computing system that can be utilized as the computerized controller of the emission control system of FIG. 1 according to the present disclosure.DETAILED DESCRIPTION

[0033] For purposes of this description, certain aspects, advantages, and novel features of the embodiments of this disclosure are described herein. The disclosed methods, apparatus, and - 5 - AFSDOCS:305402722.1systems should not be construed as being limiting in any way. Instead, the present disclosure is directed toward certain novel and nonobvious features and aspects of the various disclosed embodiments, alone and in various combinations and sub-combinations with one another. The methods, apparatus, and systems are not limited to any specific aspect or feature or combination thereof, nor do the disclosed embodiments require that any one or more specific advantages be present or problems be solved. The scope of this disclosure includes any features disclosed herein combined with any other features disclosed herein, unless physically impossible.

[0034] As introduced above, an emission control system can include a selective catalytic reduction (SCR) system, wherein a urea-based solution, commonly known as diesel exhaust fluid (DEF), is injected into the exhaust stream. The DEF undergoes thermal decomposition to produce ammonia (NEE), which then reacts with NOx in the presence of a catalyst to form nitrogen (N2) and water vapor (H2O). Sulfur in diesel fuel can produce sulfur dioxide (SO2) and sulfate (SO4) particulate matter during combustion. Sulfur-containing deposits, such as ammonium sulfate (NH4HSO4) and ammonium bisulfate ((NEL^SC ), can form on catalysts like X^Os-WCh / TiCh during SCR-DeNOx processes. These deposits can block the catalyst's surface and pores, reducing its efficiency in removing NOx from exhaust gases.

[0035] The catalyst can undergo periodic regeneration to burn off excess sulfur, sulfur compounds, and / or sulfur-containing deposits. During regeneration, the SCR is heated to a high temperature, such as a temperature in a range of 500°C to 600°C, or a temperature greater than 600°C. The elevated temperature causes the sulfur compounds to decompose and be released from the SCR as sulfur dioxide (SO2). By regenerating the SCR, the catalysts in the SCR system can remain effective in reducing undesirable emission. In some examples, an emission control system can include more than one SCR. For example, an emission control system can include an upstream SCR (closer to an engine outlet) and a downstream SCR (closer to an exhaust stream outlet and / or tail pipe). In some examples, the emission control system can include a diesel oxidation catalyst (DOC) and include a diesel particulate filter (DPF) disposed between the upstream and downstream SCRs.

[0036] In conventional emission control systems, regeneration of an SCR can be based solely on lapse of a specified period of time since a last regeneration cycle. For example, a timer can be set to zero when regeneration is performed, and a subsequent regeneration cycle can be initiated based on the timer reaching a threshold period of time (for example, 300 hours). In such- 6 - AFSDOCS:305402722.1conventional systems, regeneration is based on time without determining and / or estimating conditions and / or a status of the SCR (such as, for example, a sulfur load (e.g., amount of sulfur, sulfur compounds, and / or sulfur-containing deposits) and / or an NOx conversion rate at the SCR). Thus, in some examples, the time-based model can result in regeneration being carried out when the sulfur load at an SCR is low (e.g., lower than a threshold necessary to perform regeneration to avoid an unacceptable decrease in SCR efficiency) and / or when NOx conversion at an SCR is sufficient. As each regeneration cycle requires expenditure of fuel, the time-based model may therefore decrease fuel efficiency by performing regeneration when it is unnecessary. In other examples, the time-based model may be insufficient where an SCR has a high sulfur load (e.g., higher than the threshold necessary to perform regeneration to avoid an unacceptable decrease in SCR efficiency) and / or a low NOx conversion rate that occurs early within the regeneration period. Failure to initiate regeneration under such conditions can result in degradation of the catalyst(s) in the SCR. Therefore, such conventional systems can additionally or alternatively result in frequent servicing and / or replacement of an SCR.

[0037] In conventional emission control systems, at high engine-out NOx conditions, total NOx in the exhaust stream can be greater than the amount that can be converted in a single SCR (for example, greater than an amount that can be converted in an upstream SCR or a downstream SCR). In such conditions, DEF dosing can be split, for example, approximately equally, between upstream and downstream SCRs. However, as the DEF dosing rate increases, the sulfur deposit rate on the respective SCRs will increase. In some examples, increased sulfur deposit on the upstream SCR can require an increased frequency in regeneration cycles, thereby resulting in decreased fuel efficiency of the engine. In other examples, increased sulfur deposits on an upstream SCR can result in degradation of the catalyst(s) in the upstream SCR. Therefore, such conventional systems can additionally or alternatively result in frequent servicing and / or replacement of an upstream SCR.

[0038] The emission control systems and methods disclosed herein can address and / or overcome one or more of the foregoing issues with conventional emission control systems.

[0039] In some examples, the emission control systems and methods disclosed herein can include an SCR performance model that controls operations of the emission control system 100. In some examples, a method includes generating an SCR performance model. In some examples, the SCR performance model can include a sulfur adsorption / desorption model. In some- 7 - AFSDOCS:305402722.1examples, the SCR performance model can include an NOx conversion model. In some examples, the SCR performance model can include a sulfur adsorption / desorption model, an NOx conversion model, and a time-based model. In some examples, the SCR performance model can be generated based on data related to sulfur poisoning and recovery of an SCR, short-term and / or long-term effects on certification cycles of an SCR, and / or dosing effects on sulfation of an SCR. In some examples, one or more operating parameters and / or conditions are input into the SCR performance model to estimate a sulfur load and / or NOx conversion health at an SCR. In some examples, the emission control system includes an upstream SCR and a downstream SCR. In some examples, the upstream SCR is more susceptible to sulfur poisoning than the downstream SCR due to chemical and / or structural features of the emission control system, and the SCR performance model is an upstream SCR performance model. In some examples, the SCR performance model is configured to estimate a sulfur load at the upstream SCR.

[0040] In some examples, the emission control systems disclosed herein include systems and methods for controlling regeneration based on an SCR performance model, such as, for example, the SCR performance model discussed above. In some examples, the emission control systems disclosed herein include systems and methods for controlling exhaust gas flap (EGF) based on the SCR performance model. In some examples, the emission control systems disclosed herein include systems and methods for controlling a thermal control switch based on the SCR performance model. In some examples, the emission control systems disclosed herein include systems and methods for controlling a regeneration strategy for controlling over the road sulfur regeneration and / or idle sulfur regeneration based on the SCR performance model. In some examples, the emission control systems disclosed herein include systems and methods for generating user alerts based on the SCR performance model. In some examples, controlling regeneration based on the SCR performance model can limit frequency of regeneration cycles and / or increase fuel efficiency. In some examples, controlling regeneration based on the SCR performance model can improve long-term health of the SCR catalyst and / or limit the need for repair and / or replacement of the catalyst.

[0041] In some examples, the emission control systems disclosed herein include systems and methods for SCR trim control that can be utilized to control DEF dosing rates and / or a ratio of DEF dosing between upstream and downstream SCRs within an emission control system 100. In some examples, an SCR trim control strategy can be implemented in response to one or more - 8 - AFSDOCS:305402722.1operating conditions being met (for example, when one or more of the upstream and downstream SCRs is at a threshold temperature and / or is within a selected temperature range). In some examples, the SCR trim control strategy includes a look-up table for a maximum NOx conversion rate at an SCR based on one or more operating conditions. In some examples, the SCR look-up table includes a maximum NOx conversion at a downstream SCR based on one or more operating conditions. In some examples, the SCR trim control strategy includes controlling a dosing rate at each of an upstream SCR and a downstream SCR based on the maximum NOx conversion rate at the upstream SCR and / or downstream SCR. In some examples, the SCR trim control strategy includes controlling a DEF dosing ratio between an upstream SCR and a downstream SCR based on the maximum NOx conversion rate at the downstream SCR. In some examples, the dosing rate at the upstream SCR and / or the dosing ratio can be an operating parameter utilized by the SCR performance model for, e.g., controlling sulfur regeneration. In some examples, controlling dosing based on the SCR trim control method can enable maximum NOx conversion to occur at the main SCR (mSCR, which may be the downstream SCR or the upstream SCR), while minimizing NOx conversion at the closed coupled SCR (ccSCR, which may be the upstream SCR or the downstream SCR). In some examples, controlling dosing based on the SCR trim control method can limit frequency of regeneration cycles and / or increase fuel efficiency. In some examples, controlling dosing based on the SCR trim control method can improve long-term health of the upstream SCR catalyst and / or limit the need for repair and / or replacement of the catalyst.

[0042] FIG. 1 is a schematic illustration of an exemplary emission control system 100 according to various aspects of the present disclosure. As shown in FIG. 1, an exhaust flow pathway of the system 100 initiates at an engine outlet 102, where exhaust gases are expelled from a combustion engine. An exhaust gas flap (EGF) 104 can be coupled to and / or coupled downstream of the engine outlet 102 to regulate the flow of exhaust from the outlet 102. In some examples, the EGF 104 can be a valve (such as a butterfly valve, a gate valve, a diaphragm valve, a needle valve, a solenoid valve, or other types of valves) that is operable to control recirculation of exhaust gases back into the combustion chamber of the engine and / or flow of exhaust gases to downstream components in the emission control system 100. In some examples, the EGF valve can be configured to open and close exhaust gas channels to a selected degree to provide precise control over the direction and / or volume of exhaust gas flow. In some examples, the EGF valve (in its - 9 - AFSDOCS:305402722.1closed position) can be configured to create a back pressure in the exhaust stream and / or increase a temperature of the engine and the exhaust.

[0043] In some examples, the EGF 104 includes a proportional-integral-derivative (PID) controller for controlling a position of the EGF valve. The PID controller includes three components: proportional, integral, and derivative. The proportional component can adjust the flap position based on the current error (e.g., the difference between the desired and actual positions). The integral component can address accumulated errors over time by integrating the error into collected error data and making any necessary adjustments. The derivative component can predict future errors based on the rate of change of the current error. The PID controller can continuously monitor exhaust gas temperature and adjust the flap position in real-time using sensor signals and / or other engine operation parameters and / or data (for example, parameters, data, and / or instructions received from a computerized controller, such as the computerized controller 101 discussed below). Other types of controllers known to one skilled in the art may also be utilized according to aspects of the present disclosure.

[0044] An upstream selective catalytic reduction (SCR) unit 106 (which can also be referred to as “an upstream SCR,” “a closely coupled SCR (ccSCR),” or “a pre-SCR (pSCR)”) is located close and / or proximate to the engine outlet 102. In one aspect, the SCR unit 106 may be located at an end of the exhaust flow pathway that is associated with the engine outlet 102. In some examples, the ccSCR 106 includes a substrate core, which can be made from ceramic materials (e g., cordierite) and / or metallic materials (e.g., stainless steel). Other materials may also be used. In some examples, the substrate can provide a surface area which can be coated with a catalyst. In some examples, a catalyst can be in the form a “brick” which can be a small, removable catalyst block installed in one or more layers of the ccSCR unit 106. In some examples, the ccSCR catalyst is a plate-type catalyst. In some examples, the ccSCR catalyst is a honeycomb-type catalyst. The catalyst can include one or more metals, such as, for example, copper, iron, vanadium, tungsten, titanium, and / or other metals or combinations thereof, which facilitates conversion of NOx (NO and NO2) into nitrogen (N2) and water (H2O). In some examples, the ccSCR 106 includes a copper (Cu) catalyst. In some examples, the ccSCR 106 includes a zeolite wash coat on the substrate, which can increase the surface area available for catalytic reactions, enhancing the efficiency of the catalyst. In some examples, the ccSCR 106 includes a Pt / Pd zone which can be a specified area within the ccSCR 106 where platinum (Pt)- 10 - AFSDOCS:305402722.1and palladium (Pd) are used as catalysts, which can be included to oxidize excess NH3 and enhance overall efficiency.

[0045] In some examples, a sulfur trap can be excluded from the ccSCR 106. For example, in some examples, spatial constraints and / or a location of the ccSCR 106 within the emission control system 100 and / or a body of vehicle can limit a size of the ccSCR 106. In other examples, the ccSCR 106 includes a sulfur trap such as, for example, alkaline scrubbers, to capture sulfur oxides before they reach the catalyst. Other types of sulfur trap implementations may also be used according to aspects of the present disclosure.

[0046] A diesel exhaust fluid (DEF) injection system 108 can be configured to inject a reductant, for example, a urea solution (e.g., 32.5% urea (CH4N2O) and 67.5% de-ionized water (H2O)) into the exhaust stream upstream of the ccSCR 106. Upon injection, the urea solution mixes with the exhaust gases in a mixing chamber where the urea decomposes into ammonia (NH3). The ammonia then reacts with the NOx in the presence of the catalyst (e.g., copper), converting the NOx into nitrogen and water to reduce NOx in the exhaust stream.

[0047] One or more sensors, such as sensors 110, 112 can be integrated into the inlet of the ccSCR 106 and / or can be coupled upstream of the ccSCR inlet between the urea injection system 108 and inlet of the ccSCR 106. In some examples, the sensors 110, 112 can be configured for monitoring operating parameters upstream of the ccSCR 106 and / or at the ccSCR inlet, including parameters such as, for example, NOx levels, temperature, and / or urea concentration. In some examples, sensor 110 is an NOx sensor, and sensor 112 is a temperature sensor. In other examples, the sensors 110, 112 may be other types of sensors for monitoring the contents of the exhaust gas.

[0048] The ccSCR catalyst can be designed to operate efficiently with low levels of sulfur. High levels of sulfur content in the fuel can lead to the formation of sulfur oxides (SO2 and SO3), which can poison the catalyst and / or reduce its efficiency. In some example, one or more characteristics of the selected substrate and catalyst coating combination can render the ccSCR catalyst susceptible to reactions with sulfur compounds present in the exhaust gas, thereby physically coating and chemically reducing the available catalytic material which in turn deactivates the capability of the ccSCR catalyst to convert NOx into nitrogen and water. As discussed further below, the ccSCR catalyst can undergo periodic regeneration to burn off excess sulfur and return the ccSCR catalyst to an active and / or functional state. Here, the ccSCR- 11 - AFSDOCS:305402722.1catalyst may operate at an active and / or functional state if it is able to convert the expected amount of NOx into nitrogen and water. The expected amount of NOx may depend on the catalyst temperature and / or other factors. The ccSCR may be considered “poisoned” (reduction in NOx conversion efficiency) if it is unable to convert the expected amount of NOx into nitrogen and water. In one example, to operate at an active and / or function state, the ccSCR catalyst may be able to convert up to 99%, 95%, 90%, 85%, 80%, 70%, 60% or other percentages of expected NOx conversion capability into nitrogen and water. The ccSCR may be considered “poisoned” (reduction in NOx conversion efficiency) if the ccSCR catalyst is able to convert less than 50%, 40%, 30%, 20%, 10% or other percentages of expected NOx conversion capability into nitrogen and water. Other percentages and methods of quantifying ccSCR catalyst capability may also be used.

[0049] Operation of the engine over time can result in the ccSCR catalyst becoming saturated with sulfur deposits (such as sulfur and / or sulfur compounds). To mitigate sulfur poisoning, ccSCR catalyst can undergo one or more regeneration processes that include heating the ccSCR catalyst to high temperatures to remove sulfur compounds and restore catalytic activity.Regeneration can be utilized to restore functionality of the ccSCR 106 and prevent or limit degradation of the catalyst. In some examples, during a regeneration cycle, the ccSCR 106 can be heated to a selected and / or a threshold temperature (for example, a temperature within a range of 500 °C to 600 °C) to release the adsorbed sulfur compounds from the ccSCR catalyst. Other temperature and / or temperature ranges may also be used to desorb the sulfur deposits from the ccSCR catalyst. As discussed further below, one or more components of the emission control system 100 can be controlled by the computerized controller 101 to cause heating of the ccSCR 106 to a selected temperature for sulfur regeneration.

[0050] Returning to FIG. 1, downstream of the ccSCR 106, the system 100 can, in some examples, include a diesel oxidation catalyst (DOC) 114 for oxidizing carbon monoxide (CO) and hydrocarbons (HC) into carbon dioxide (CO2) and water. In some examples, the system 100 can additionally include a diesel particulate filter (DPF) 116 for capturing and storing particulate matter (e.g., soot) from the exhaust gases downstream of the DOC 114. One or more sensors, such as sensors 118, 120 can be disposed at the outlet of the ccSCR 106 and / or can be coupled downstream of the ccSCR 106 (i.e., between the ccSCR 106 and the DOC 114). In some examples, the sensors 118, 120 can be configured for monitoring operating parameters at the - 12 - AFSDOCS:305402722.1ccSCR outlet, such as, for example, NOx levels, temperature, and / or urea concentration. In some examples, sensor 118 is an NOx sensor. In some examples, sensor 120 is a temperature sensor. In some examples, one or more sensors can be located downstream of the DPF 116. For example, the system 100 can include a temperature sensor 122 downstream of the DPF 116. Other sensors may also be disposed along the exhaust flow path according to an aspect of the present disclosure.

[0051] Operation of the engine over time can result in the DPF 116 becoming saturated and / or clogged with soot, which can result in reduced engine performance and / or higher fuel consumption. The DPF 116 can undergo regeneration to bum off the accumulated soot and / or particulate matter for maintaining efficiency (i.e., ability to effectively remove particulate from the exhaust flow path) of the DPF. In some examples, during a regeneration cycle, the DPF 116 can be heated to a selected and / or a threshold temperature (for example, a temperature within a range of 500 °C to 600 °C) to release and / or burn off the accumulated soot. Other temperatures or temperature ranges for the regeneration cycle may also be used. As discussed further below, one or more components of the emission control system 100 can be controlled by the computerized controller 101 to cause heating of the DPF 116 to a selected temperature for soot regeneration.

[0052] In the example of FIG. 1, the emission control system 100 further includes a downstream SCR unit 124 (which can also be referred to as a “main SCR (mSCR)”) having catalysts configured to reduce NOx from the exhaust fume flowing through the mSCR 124. and the emission control system 100 includes a DEF injection system 126 that is configured to inject a reductant solution into the exhaust stream upstream of the mSCR 124. The system 100 can also include one or more sensors 128, 130 integrated into an outlet of the mSCR 124 and / or downstream of an outlet of mSCR 124. In some examples, the sensor 128 is a temperature sensor. In some examples, the sensor 130 is an NOx sensor. In some examples, the mSCR 124 and / or the DEF injection system 126 can have one or more features of the ccSCR 106 and the DEF injection system 108, discussed above. In some examples, the mSCR 124 and / or the DEF injection system 126 can have one or more features that differ from the ccSCR 106 and the DEF injection system 108. For example, in some examples, the mSCR 124 includes a different catalyst from the ccSCR 106, such as, for example, iron (Fe) catalysts or iron and copper catalysts. Other variations of the mSCR 124 and / or the DEF injection system 126 may also be possible according to certain aspects of the present disclosure.- 13 - AFSDOCS:305402722.1

[0053] In some examples, the ccSCR 106 (disposed upstream of the mSCR 124) can be configured to reduce a portion of NOx from the exhaust gases, which are then passed through the DOC 114 and the DPF 116. In some examples, the mSCR 124 (disposed downstream of the ccSCR 106) is configured to further reduce at least some of the remaining NOx, improving reduction efficiency of the system 100. The treated exhaust gases can then be directed through a tail pipe 132, where they are expelled into the atmosphere.

[0054] To manage the temperature of the exhaust gases, the system 100 can include a thermal management system 134. In some examples, the thermal management system includes one or more actuators and / or switches upstream of the engine outlet 102 and the EGF 104 for controlling a thermal mode of the engine. The thermal management system 134 can be designed to regulate the temperature of various components in the system. In some examples, the thermal management system 134 can enable rapid heating of one or more components of the system 100 during cold starts and regeneration cycles, ensuring that the emission control components operate at optimal temperatures. The thermal management system 134 can also help dissipate excess heat generated during combustion, preventing overheating and potential damage to the emission control components. In some examples, the thermal management system 134 forms a thermal management switch control. Here, the thermal management switch control is a scheme for the thermal management system 134 to control the exhaust temperature (downstream from engine) via one or more actuators (e.g., flaps, valves, etc.), switches, and / or other mechanical devices. Specifically, the thermal management system 134 may close, open, and / or adjust the actuators, switches, and / or other mechanical devices relating to the engine to raise (or lower) the exhaust temperature to a certain threshold associated with the configurations of the actuators, flaps, and / or mechanical devices. In some example, the thermal management switch control can cause operation of the engine in various thermal management modes.

[0055] In some examples, the thermal management system 134 includes one or more thermistors (e g., temperature-sensitive resistors that changes its resistance with temperature). For example, a thermistor can be a negative temperature coefficient (NTC) thermistor, where resistance decreases as temperature increases, a positive temperature coefficient (PTC) thermistor, where resistance increases with rising temperature, or other types of thermistors. A control circuit can process signals from the thermistor(s) and activate cooling or heating mechanisms as depending on operating conditions of the engine.- 14 - AFSDOCS:305402722.1

[0056] In some examples, the thermal management system 134 ensures that the ccSCR 106 and / or the mSCR 124 reaches its respective light-off temperature quickly and maintains it for effective NOx conversion and emission reduction. In some examples, the DOC 114 can require high temperatures (e.g., 250 °C to 300 °C) to convert carbon monoxide (CO) and hydrocarbons (HC) and the thermal control switch can maintain these temperatures by activating heating elements or adjusting the flow of exhaust gases. In some examples, the thermal management system 134 can be utilized to ensure that the DPF 116 reaches and maintains the necessary temperature (e.g., 580 °C) for its regeneration.

[0057] In some examples, the emission control system 100 can further include a hydrocarbon dosing system 136, which can include dosing fuel line in communication with the engine fuel supply and an injector. Hydrocarbon dosing can facilitate regeneration of the DPF 116 by injecting a small amount of fuel into the exhaust stream upstream of the DOC 114 and / or directly into the DPF 116. The fuel can vaporize and react with the exhaust gases to generate heat that helps burn off the soot accumulated in the DPF 116. The dosing (e.g., timing and amount of fuel to be injected) can be based on one or more operating parameters, such as e.g., exhaust temperature and / or engine load as described below.

[0058] The emission control system 100 includes a computerized controller 101 in communication with various components and sensors within the system for managing and / or controlling its operation. In some examples, the computerized controller 101 includes one or more processors 105 in communication with a memory 103 and a data communication interface 107. In some examples, the computerized controller 101 is a motor control module (MCM) and / or a motor control unit (MCU). In some examples, the computerized controller 101, the one or more processors 105, the memory 103, and / or the data communication interface 107 include one or more features of the computing system 800, the one or more processing units 810, 815, the memory 820, 825, and / or the communication connections 870 shown in FIG. 33 and discussed below.

[0059] In some examples, the computerized controller 101 can be configured to receive signals from one or more of the temperature sensors 110, 118, 130, the NOx sensors 112, 120, 122, 128, and / or other sensors (e.g., one or more sensors of the thermal management switch 134, one or more sensors of the EGF 104, and / or one or more sensors within the engine). In some examples, the computerized controller 101 can be configured for data communication with EGF 104, the - 15 - AFSDOCS:305402722.1DEF injection systems 106, 126, the thermal control switch 134, and / or the hydrocarbon dosing system 136. In some examples, the computerized controller 101 can be configured to control the EGF control loop. For example, the computerized controller 101 can be configured to control a position of the EGF 104 and / or determining a target exhaust temperature for regulating a position of the EGF 104. In some examples, the computerized controller 101 can be configured to control the thermal management switch control. For example, the computerized controller 101 operations of and / or actuation of one or more actuators of the thermal management switch 134 and / or determining a target exhaust temperature for regulating actuators of the thermal management switch 134. In some examples, the computerized controller 101 can be configured to control a timing, an amount of DEF dosing, and / or an injection rate for each of the DEF injection systems 106, 126. In some examples, the computerized controller 101 can be configured to control a timing, an amount of fuel dosing, and / or an injection rate for hydrocarbon dosing system 136.

[0060] In some examples, due to its proximity to the engine, the ccSCR 106 can be smaller than the mSCR 124. In some examples, the ccSCR 106 can have a smaller volume than the mSCR 124. In some examples, the ccSCR 106 can have a greater surface area to volume ratio than the mSCR 124. In some examples, the ccSCR 106 can have a lower maximum NOx conversion capacity than the mSCR 124. In some examples, the mSCR 124 includes a sulfur trap and the ccSCR 106 can exclude a sulfur trap. In some examples, a catalyst and / or substrate of the ccSCR 106 can be more susceptible to sulfur poisoning than a catalyst and / or substrate of the mSCR 124. In some examples, a proximity of the upstream ccSCR 106 to the engine outlet and / or its position upstream of the DOC 114 and the DPF 116 can render the ccSCR 106 more susceptible to sulfur poisoning than the downstream mSCR 124 due to greater exposure to sulfur compounds. In some examples, formation of sulfur deposits can be temperature dependent. Thus, in some examples, because of its position downstream of the DOC 114, mSCR 124 can be regularly exposed to higher temperatures than the ccSCR 106, while the ccSCR 106 experiences lower operating temperatures, which result in increased sulfur deposition and susceptibility to sulfur poisoning. In such examples, the ccSCR 106 may require more frequent regeneration than the mSCR 124.

[0061] As discussed above, in some examples, the emission control system 100 includes systems and methods of operation that can limit frequency of regeneration cycles at the ccSCR 106, and - 16 - AFSDOCS:305402722.1thereby increase fuel efficiency of the system. In some examples, the emission control system 100 includes systems and methods of operation that can improve health of the ccSCR 106 catalyst and / or limit the need for repair and / or replacement of the catalyst of the ccSCR 106.

[0062] For example, FIG. 2A shows an example of a method 200 for generating one or more operational models and controlling operation of an emission control system, such as the emission control system 100 (FIG. 1) discussed above. As can be seen therein at step 202, the method 200 includes generating a performance model for an upstream SCR, such as the ccSCR 106. As discussed further below with reference to FIGS. 3-20H, modeling performance of the ccSCR 106 can include modeling sulfur adsorption and / or desorption at the ccSCR, modeling long-term sulfation effects on ccSCR 106, and / or modeling DEF dosing effects on sulfation of the ccSCR 106.

[0063] In some examples, at step 204, the method 200 includes generating a look-up table for maximum NOx conversion at a downstream SCR, such as the mSCR 124. In some examples, the look-up table can include a plurality of values for one or more operating parameters correlated with maximum NOx conversion and / or maximum DEF dosing rates at the mSCR 124 under the specified operational conditions. For example, the look-up table can cross-reference mSCR catalyst temperature and exhaust mass flow to maximum NOx conversion capability at the mSCR 124.

[0064] The ccSCR performance model and / or the maximum NOx conversion mSCR look-up table can be stored, for example, in a memory of a computerized controller for the vehicle or the emission control system, such as in the memory 103 of the computerized controller 101. In some examples, the ccSCR performance model and / or the maximum NOx conversion mSCR look-up table can be stored in a network storage location in data communication with a computerized controller for the vehicle and / or the emission control system 100. Other mechanisms, such as using one or more equations and / or algorithms, may also be used to derive one or more of the maximum NOx conversion rates under specific conditions, the maximum DEF dosing rates under specific conditions, and / or other values associated with the ccSCR performance model.

[0065] Per step 206, the method 200 includes operating an engine (for example, operating an automotive engine) including the emission control system 100, which can include operating the engine during a single continuous period of operation and / or operating the engine over multiple periods of operation.- 17 - AFSDOCS:305402722.1

[0066] Per step 208, the method 200 includes measuring and / or detecting one or more operating parameters during the operation and / or over the repeated periods of operation of the engine. In some examples, the one or more operating parameters can include a fuel mass (e.g., an amount of fuel used or available in the system measured in kg / s, Ib / s, or other suitable units) and / or an exhaust mass flow rate (e.g., an exhaust flow rate measured in kg / h, Ib / hr, or other suitable units). In some examples, the one or more operating parameters can one or more ccSCR temperature values (e.g., a temperature at the ccSCR inlet, a temperature at the ccSCR outlet, and / or a temperature of the ccSCR catalyst), an amount and / or concentration of NOx at the ccSCR inlet, an amount and / or concentration of NOx at the ccSCR outlet, an operational state of the engine (e.g., an off state or an on state), a quantity of urea dosed at the ccSCR 106, and / or a time elapsed since a last regeneration cycle has occurred. In some examples, the one or more operating parameters can include one or more mSCR temperature values (e.g., a temperature at the mSCR inlet, a temperature at the mSCR outlet, and / or a temperature of the mSCR catalyst), an amount and / or concentration of NOx at the mSCR inlet, an amount and / or concentration of NOx at the mSCR outlet, and / or a quantity of urea dosed at the mSCR. Other types and / or combinations of operating parameters may also be used according to various aspects of the present disclosure.

[0067] In some examples, the method 200 includes controlling sulfur regeneration based on the ccSCR performance model (steps 210-216). For example, at step 210, one or more of the operating parameters can be input into the ccSCR performance model. An estimate of accumulated sulfur and / or an estimate of NOx conversion health at the ccSCR 106 can be determined (step 214), which can be utilized to control regeneration via, for example, control of an exhaust gas flap control loop and / or thermal management switch control. For example, in a “driving” operational state of the engine, regeneration can be carried out utilizing the thermal management switch control. In an “idle” operational state of the engine, regeneration can be carried out utilizing the exhaust gas flap control loop. Exemplary detailed methods for controlling sulfur regeneration based on the ccSCR performance model are discussed further below with respect to FIGS. 21-30.

[0068] In some examples, the method 200 includes controlling DEF dosing to each of the downstream and upstream SCRs (steps 218-224). For example, at step 218, it can be determined that one or more operating parameters are met (e.g., that the ccSCR temperature within a- 18 - AFSDOCS:305402722.1specified range, that the mSCR temperature is within a specified range, etc.). Next, at step 220, a dosing rate for the mSCR can be determined. In some examples, the dosing rate of the mSCR 124 can be determined based on the lookup table for maximum NOx conversion at the mSCR 124. In some examples, the dosing rate for the mSCR 124 can be determined based on other criteria (for example, temperatures of one or more of the mSCR 124 and the ccSCR 106 and / or an operational state of the engine). The method 200 can further include determining a dosing rate for the ccSCR 106 (step 222). In some examples, the dosing rate of the ccSCR 106 can be determined based on dosing rate for the mSCR 124. In some examples, the dosing rate for the ccSCR 106 can be determined based on other criteria (for example, temperatures of one or more of the mSCR 124 and the ccSCR 106 and / or an operational state of the engine). As discussed above, in some examples, the dosing rate for the ccSCR 106 is input into the ccSCR performance model at step 210. The determined dosing rates for the ccSCR 106 and the mSCR 124 can be utilized to control DEF dosing thereto (step 224). In some examples, the dosing rates can be characterized as a dosing ratio between the ccSCR 106 and the mSCR 124. An exemplary detailed method for controlling DEF dosing is discussed further below with respect to FIGS. 31-32.

[0069] FIG. 2B shows a functional diagram of an example of a control module 230 for carrying out the method 200. The control module 230 may be implemented by one or more of computerized controller 101, the computing system 800, and / or one or more subcomponents of the computerized controller 101 or the computing system 800. Referring to FIGs. 1 and 2B, in one aspect of the present disclosure, FIG. 2B shows a ccSCR performance model module 232. The ccSCR performance model module 232 can receive a plurality of operating parameters 234 that can be utilized for controlling sulfur regeneration via a regeneration control module 236. A DEF dosing trim control module 238 can receive a plurality of operating parameters 240 that can be utilized for controlling DEF dosing to the mSCR 124 and the ccSCR 106. At least one of the operating parameters input into the ccSCR performance module (e.g., ccSCR Urea Dosing Quantity) can be received from the DEF dosing trim control module 238.

[0070] Turning to FIG. 3, an exemplary method 300 for generating a ccSCR performance model is shown and described. The method 300 can include one or more features or steps of the step 202 of the method 200 discussed above. In some examples, the method 300 includes generating a first set of data modeling sulfur adsorption and / or desorption at the ccSCR 106 (e.g., utilizing a - 19 - AFSDOCS:305402722.1core sample of the ccSCR 106 and various controlled dosing rates of SO2) (step 302), generating a second set of data modeling long-term sulfation effects on the ccSCR 106 (e.g., by running various low temperature duty cycles repeatedly on an engine / after treatment system (ATS) combination and observing the effects on sulfation) (step 304), and / or generating a third set of data modeling DEF dosing effects on sulfation of the ccSCR 106 (e.g., utilizing various controlled urea dosing rates or quantities) (step 306). Here, the ATS may include one or more components shown in FIG. 1 of the current disclosure. In some examples, modeling sulfur adsorption and / or desorption at the ccSCR 106 at step 302 includes modeling the physics and / or chemistry of the ccSCR 106 in isolation (e.g., in isolation from the engine and one or more other components of the emission control system). In some examples, modeling long-term sulfation effects on the ccSCR 106 at step 304 includes modeling the ccSCR 106 in combination with the engine and emission control system to simulate over-the-road conditions of a vehicle including the engine and emission control system 100. In some examples, modeling DEF dosing effects on sulfation of the ccSCR at step 306 includes modeling the ccSCR modeling the ccSCR 106 in combination with the engine and emission control system over various duty cycles.

[0071] In some examples, modeling sulfur adsorption and / or desorption at the ccSCR 106 at step 302 includes modeling NOx conversion at the ccSCR 106 relative to a temperature of the ccSCR inlet over selected periods of time. For example, FIG. 4 illustrates exemplary data showing NOx conversion at the ccSCR 106 for a period of pre-regeneration (e.g., 100-hour period preregeneration), NOx conversion at the ccSCR 106 for various periods of time periods of postregeneration. For example, the post-regeneration periods may be x, 2x, and 3x, where x is a certain number of hours. From this data, a relationship between a temperature of the ccSCR inlet and NOx conversion and / or a relationship between NOx conversion at the ccSCR 106 and time (e.g., time post-sulfur regeneration) can be determined.

[0072] In some examples, modeling sulfur adsorption and desorption at the ccSCR 106 at step 302 includes modeling NO conversion during sulfur adsorption at the ccSCR 106. For example, FIGS. 5 and 6 illustrate exemplary data showing percentage (%) of NO conversion at the ccSCR 106 during sulfur adsorption relative to temperature overtime. In some examples, each dose (e.g., Doses 1-3 shown in FIGS. 5 and 6) can refer to a dose of 2.5 ppm SO2 for 20000 seconds, followed by a 550 °C regeneration cycle. Other doses (varying parts per million and / or durations) may also be possible. Doses 1-3 can be consecutive. For example, Dose 1 be administered first,- 20 - AFSDOCS:305402722.1then Dose 2, and then Dose 3. From this data, differences between this “tightly bound” sulfur deposits (that is, sulfur deposits that cannot be removed by regeneration) and “loosely bound” sulfur deposits (that is, sulfur deposits that can be removed by regeneration) over multiple temperatures (e.g., 200 °C and 350 °C, as shown in FIGS. 5 and 6, and / or other temperatures) at the ccSCR 106 can be determined. The exemplary data shown in FIGS. 5 and 6 illustrate that at colder temperatures the ccSCR 106 will sulfate more, while at hotter temperatures, the ccSCR 106 will sulfate less.

[0073] In some examples, modeling sulfur adsorption and desorption at the ccSCR 106 at step 302 includes modeling desulfation of the ccSCR 106 at various temperatures. For example, FIGS. 7 and 8 illustrate exemplary data showing SO2 concentration at the ccSCR relative to temperature. In some examples, DeSOx 1-4 can refer to the deSOx regeneration completed after each dose (e.g., a dose of 2.5 ppm SO2 for 20000 seconds, followed by a 550 °C regeneration cycle at Doses 1-3 discussed above) and finally a high temperature regeneration (e.g., 1000 °C regeneration). The data illustrate that the first regeneration (DeSOx 1) shows less sulfur being removed between a certain temperature range (e.g., 400 °C and 500 °C) because the first dose can result in deposition of a greater amount of “tightly bound” sulfur and a smaller amount of “loosely bound” sulfur. The next two regeneration cycles (DeSOx 2-3) illustrate “loosely bound” sulfur that can be consistently removed at regeneration cycles performed at the same temperature range (e.g., 400 °C - 550 °C). The last regeneration (DeSOx 4 at, e.g., 1000 °C) damages (potentially irreversibly damages) the ccSCR sample but illustrates the presence of the remaining “tightly bound” sulfur. In some examples, the data shown in FIGS. 7 and 8 illustrate that a lower adsorption temperature may result in increased sulfur storage at the ccSCR catalyst. The dosing parameters and / or conditions described above are for illustrative purposes and other parameters and / or conditions may also be used for constructing the models and / or methods implemented in the present disclosure.

[0074] FIG. 9 illustrates exemplary data showing SO2 concentration at the ccSCR 106 relative to temperature after regeneration at 1000 °C. DeSOx T1-T5 show concentrations of SO2 at the ccSCR outlet at a 1000 °C regeneration, carried out after three cycles of regeneration at the indicated temperatures Tl, T2, T3, T4, and T5. The temperatures for T1 to T5 may vary. In one example, Tl, T2, T3, T4, and T5 correspond to 550 °C, 525 °C, 500 °C, 450 °C, and 375 °C. Other temperatures may also be used. From this data, it can be determined, at a specified level of - 21 - AFSDOCS:305402722.1sulfur adsorption, if the recurring deSOx regenerations are at a lower temperature, the “loosely bound” sulfur may remain deposited on the ccSCR catalyst. In some examples, the data in FIG. 9 can be utilized to determine at which temperature a cyclic regeneration policy will be successful. In some examples, the data in FIG. 9 illustrate that sulfur adsorption at the ccSCR 106 can occur during steady-state adsorption with controlled SO2 ppm inputs.

[0075] In some examples, the exemplary data of FIGS. 4-9 show that permanent (“tightly bound”) sulfur deposits may accumulate in the ccSCR catalyst (which can be removeable at regeneration temperatures above 600 °C). In some examples, the exemplary data of FIGS. 4-9 show that sulfur adsorption and desorption trends are correlated to temperature. In some examples, the exemplary data of FIGS. 4-9 show an effective regeneration temperature (e.g., 550 °C) and / or an effective regeneration temperature range (e.g., 450 °C to 600 °C) for the ccSCR 106. Other temperatures and / or temperature ranges may also be implemented depending on operating conditions, catalyst materials, catalyst designs, fuel consumption strategy, or other parameters.

[0076] In some examples, modeling long-term sulfation effects on the ccSCR 106 at step 304 includes modeling ccSCR NOx conversion over time and / or over a series of certification cycles. In some examples, a certification cycle can correspond to a period during in which an emission certification remains valid in an engine and aftertreatment system. FIG. 10 illustrates exemplary data showing ccSCR NOx conversion over time. In some examples, the data in FIG. 10 can be utilized to model the ccSCR 106 under low load cycle (LLC) and / or low load torque conditions. The trend line illustrated in dark dots data points shows the degradation of a “fresh” ccSCR catalyst. The trend line illustrated in light dots data points shows degradation of a ccSCR catalyst under sulfur poisoning conditions (for example, where “tightly bound” sulfur is deposited on the catalyst). From this data, it can be determined that degradation of the ccSCR catalyst can occur over repeated transient cycles.

[0077] In some examples, modeling long-term sulfation effects on the ccSCR 106 at step 304 includes modeling ccSCR NOx conversion relative to an internal temperature of the ccSCR 106 (which can be measured at, for example, the ccSCR input and / or the ccSCR output). In some examples, signals from a selected one or more of the inlet or outlet sensors or signals from both the inlet and outlet sensors can be utilized (for example, depending on which yields more accurate results relative to the others, or using an average of both measurements). For example,- 22 - AFSDOCS:305402722.1FIGS. 11 and 12 illustrate exemplary data showing NOx conversion by the ccSCR 106 relative to a temperature of the ccSCR 106, including at a baseline condition (which can be, for example, a condition where an SCR system, such as the ccSCR 106 or the mSCR 124 has been regenerated at a certain temperature for a certain duration, such as 500 °C for one hour) and at one or more sulfur adsorption conditions (e.g., 430 hours adsorption, 500 hours adsorption). In FIGS. 11 and 12, x and y represent positive integers measured in hours.

[0078] In some examples, modeling long-term sulfation effects on the ccSCR 106 at step 304 includes modeling sulfur loading at the ccSCR 106. For example, FIG. 13A illustrates exemplary data characterizing sulfation at the ccSCR 106 (i.e., sulfur loading and / or sulfur sticking to the ccSCR catalyst) at a baseline condition (which can be, for example, a condition where a ccSCR system has been regenerated at 500 °C for one hour) and a sulfur adsorption condition (e.g., 500 hours adsorption). In some examples, FTP refers to a certification cycle. In some examples, an hFTP refers to a ‘hot’ FTP and a eFTP refers to a ‘cold’ FTP. A eFTP can occur after the ccSCR system is returned to a standard temperature and pressure, while an hFTP occurs while the ccSCR system is operating at temperatures greater than 100 °C to 200 °C. A wFTP can refer to a calculated weighted FTP emissions result (for example, 1 / 7 eFTP + 6 / 7 hFTP). In some examples, the baseline condition refers to a ccSCR system that has just been regenerated. In some examples, “500 hr adsorption” refers to the ccSCR system after a steady state 500-hour adsorption. From the data shown in FIGS. 11-13A temperature-specific degradation before and after adsorption at a specified certification cycle and how sulfur deposition can affect certification can be determined.

[0079] In some examples, modeling long-term sulfation effects on the ccSCR 106 at step 304 includes modeling sulfur unloading at the ccSCR 106. For example, FIG. 13B illustrates exemplary data characterizing desulfation of the ccSCR 106 (e.g., sulfur loading and / or sulfur removed from the ccSCR catalyst) at a baseline condition and various FTP conditions. As discussed above, FTP can refer to a certification cycle. In some examples, an hFTP refers to a ‘hot’ FTP and a eFTP refers to a ‘cold’ FTP. A eFTP can occur after the ccSCR system is returned to a standard temperature and pressure, while an hFTP occurs while the ccSCR system is operating at temperatures greater than 100 °C to 200 °C. A wFTP can refer to a calculated weighted FTP emissions result (for example, 1 / 7 eFTP + 6 / 7 hFTP). In some examples, the baseline condition refers to a ccSCR system that has just been regenerated. In some examples,- 23 - AFSDOCS:305402722.1“500 hr adsorption” refers to the ccSCR system after a steady state 500-hour adsorption. In some examples, “Post xl FTP in Regen Mode” refers to the ccSCR system after an FTP run in an engine hot mode and shows the reduction in emissions occurring thereafter. In some examples, “Post x3 FTP in Regen Mode” refers to the ccSCR system after three repeated FTPs in an engine hot mode. In some examples, “Post xl Idle Sulfur Regen” is a stationary idle regeneration. From this data, it can be determined that over the road regenerations and idle regenerations for sulfur are feasible. For example, 500 hours at worst case sulfur adsorption can reach an acceptable limit, and after additional (e.g., several) regenerations the ccSCR 106 can return to baseline.

[0080] In some examples, the exemplary data shown in FIGS. 10-13B illustrate NOx conversion profiles at the ccSCR 106 after sulfur adsorption and desorption (after regeneration) of the ccSCR catalyst. In some examples, modeling of long-term sulfation effects on the ccSCR 106 at step 304 includes correlating the sulfation effects data to the data produced during modeling sulfur adsorption and desorption at the ccSCR 106 at step 302.

[0081] In some examples, modeling DEF dosing effects on sulfation of the ccSCR 106 at step 306 includes modeling SO2 adsorption at the ccSCR catalyst over time at various dosing rates. For example, FIGS. 14A and 14B respectively illustrate exemplary data showing SO2 adsorption at ccSCR catalyst over time relative to temperature at the ccSCR inlet and SO2 adsorption at ccSCR catalyst over time relative to incoming an amount of NH3 delivered to the ccSCR. From this data, a relationship between NH3 dosing and SO2 adsorption can be determined. For example, the exemplary data illustrate that increased amounts of NH3 result in higher SO2 adsorption at the ccSCR catalyst.

[0082] In another examples, FIGS. 15A-15C illustrate exemplary data showing SO2 concentration in the exhaust stream at various DEF dosing conditions for the ccSCR 106. For example, FIG. 15A illustrates exemplary data showing SO2 in the exhaust stream at an outlet of the ccSCR 106 at various DEF dosing conditions (such as at various Ammonia-to-NOx Ratios (ANRs), e.g., 1, 0.5, 0). FIG. 15B illustrates exemplary data showing adsorption of SO2 at the ccSCR 106 at various DEF dosing conditions (such as at various Ammonia-to-NOx Ratios (ANRs), e.g., 1, 0.5, 0). FIG. 15C illustrates exemplary data showing a ratio of SO2 in the exhaust stream at an inlet of the ccSCR SO2 relative to SO2 in the exhaust stream at an outlet of the ccSCR at various DEF dosing conditions (such as at various Ammonia-to-NOx Ratios (ANRs), e.g., 1, 0.5, 0). From this data, it can be determined that DEF dosing has an effect on the - 24 - AFSDOCS:305402722.1amount of SO2 that is adsorbed onto the ccSCR 106. For example, FIG. 15B shows that as the ANR increases, the amount of SO2 adsorbed increases, thereby characterizing the relationship between DEF dosing and SO2 adsorption.

[0083] The exemplary data in FIG. 15A illustrate that SO2 in the exhaust stream at an outlet of the ccSCR 106 decreases as DEF dosing increases, indicating that sulfur is accumulating at the ccSCR catalyst. The exemplary data in FIGS. 15A-15C illustrate that SO2 deposition at the ccSCR 106 can be a function of incoming SO2 and / or pressure, ccSCR temperature (e.g., a catalyst temperature, a substrate temperature, etc.), and / or NH3 present in the exhaust flow at the inlet of the ccSCR 106 and / or injected at onto the ccSCR 106.

[0084] Returning to FIG. 3, as discussed above, the model data can be utilized to generate the ccSCR performance model (step 308). In some examples, the model data can be utilized to identify operating parameters that can be correlated to NOx conversion and / or sulfur load at the ccSCR. For example, FIG. 16 shows a table of operating parameters and their relationship (illustrated in arrows indicating an upward increase or a downward decrease) to sulfur deposition at the ccSCR catalyst. As can be seen therein, sulfur deposition at the ccSCR catalyst can be a function of DEF dosing, fuel mass burned, catalyst temperature, and a time / duration at a given temperature. In some examples, as incoming SO2 increases, SO2 adsorption increases. In some examples, as temperature increases, SO2 adsorption decreases. In some examples, as DEF dosing increase, SO2 adsorption increases.

[0085] In some examples, the model data can be utilized to generate one or more algorithms of the ccSCR performance model. FIG. 17A shows an exemplary algorithm for a sulfur storage model for the ccSCR. FIGS. 17B-17D include exemplary graphical data illustrating modeled adsorption (FIG. 17B), desorption (FIG. 17C), and sulfur storage (FIG. 17D). FIG. 18 shows an exemplary algorithm for an NOx conversion health model for the ccSCR 106 and a representative calibration map for the NOx conversion health model.

[0086] As shown in FIG. 17A, the exemplary algorithm for the sulfur storage model for the ccSCR includes: / >. r ABM!^ads kadsorption\TpSCRJ ' ^sulfur * tsr 0 <- TpSCR< 375°CASd<,s(i) = (S(tes{;}_5<jes{i_1) r^cs>375„c- 25 - AFSDOCS:305402722.1^desorption (TpSCR)'[ti~tn]$deseSnet{t} J [A^adsO} + AS^es{i}] dts+ SR2Pwhereini: current iterationn: iteration on rising edge ofTpSCR> 375°C

[0087] FIG. 17B illustrates modeled sulfur adsorption, which is a linear function of fuel mass injected (kg / s) and a shows a variable rate of adsorption, kadsorption-. as a function of temperature. FIG. 17C illustrated modeled sulfur desorption, which triggers when the ccSCR temperature is greater than or equal to 375 °C, is a negative exponential function of time since trigger, and shows a variable rate of desorption, kdesorption, as a function of temperature. FIG.17D illustrates that stored sulfur is an E2P value, which is updated by a net change in sulfur per tsand resets to a minimum value every regeneration completion.

[0088] In some examples, the algorithm for the sulfur storage model is a piece-wise linear / exponential algorithm with variable coefficients. In some examples, the inputs to the model can include fuel mass flow rate, SCR temperature, and the current sulfur storage value outputted from the model. In some examples, the output of the model is an estimated sulfur stored in the ccSCR 106. In some examples, the variable coefficients to the model are based on SCR temperatures and DEF dosing and are calibrated with respect to the data collected above.

[0089] As shown in FIG. 18, the exemplary algorithm for an NOx conversion health model for the ccSCR 106 includes:N OxoutNOXinNOXxi.nconvNOxin <- NOXxi.nwherein the resulting NOx conversion value is passed through a filter, which includes:y(ri) = a • x(n) + (1 — a) • y(n — 1))- 26 - AFSDOCS:305402722.1LPF: tz = -T

[0090] In some examples, the NOx conversion health model is designed for generating a filtered NOx conversion calculation, which can be utilized with an ammonia NOx ratio (ANR) / temperature calibration map, which maps optimal NOx conversion, and can be used for calibrating the optimal NOx map. In some examples, the NOx conversion health model and the calibration map can be utilized to generate an NOx conversion health metric for the ccSCR 106.

[0091] In some examples, the NOx conversion health model is configured to ensure that the regeneration policy is robust. In some examples, the NOx conversion health model is a performance-based method for safeguarding the system. In some examples, the NOx conversion health model waits until the system is operating at a desired condition (certain speed, temperature, etc.), and measures the NOx conversion across the ccSCR 106. In some examples, the NOx conversion health model then compares the measured conversion to a “healthy” calibrated NOx conversion table or map. In some examples, a ratio between the “real” and “healthy” values is utilized to calculate the sulfur storage value. In some examples, the system can periodically check the emission control system and regenerate the emission control system or reset the model to ensure robustness.

[0092] In some examples, the method 300 can optionally include performing one or more validation analyses to determine accuracy of the ccSCR performance model. For example, FIGS.19A-19H illustrate exemplary model validation data showing utilization of the EGF temperature control loop (which can also be referred to as “EGF closed loop PID control targeting”) during idle conditions for soot regeneration at the DPF (FIGS. 19A-19D) and sulfur regeneration at the ccSCR (FIGS. 19E-19H). In another examples, FIGS. 20A-20H illustrate exemplary model validation data showing thermal management switch temperature control during over the road driving conditions for soot regeneration at the DPF (FIGS. 20A-20D) and sulfur regeneration at the ccSCR (FIGS. 20E-20H). In some examples, the data of FIGS. 20A-H show the over the road (OTR) regenerations illustrating that hot mode operation / keep warm mode operation switch is capable of achieving the correct temperature for soot regeneration, and hot mode operation is capable of achieving the correct temperature for sulfur regeneration. In some examples, the validation data illustrates that the EGF PID control is effective for soot or sulfur regeneration.- 27 - AFSDOCS:305402722.1For example, FIG. 19D shows the Soot Regeneration temperature trace controlling to a desired temp. FIG. 19H shows the sulfur regeneration temperature trace controlled to a desired temp.

[0093] Turning to FIGS. 21-28, exemplary methods for controlling sulfur regeneration based on a ccSCR performance model are shown and described. In some examples, the methods shown in FIGS. 21-28 can include one or more of the features and / or steps of steps 210-216 of the method 200 discussed above (FIG. 2A). In some examples, the ccSCR performance model can be generated via the method 300 discussed above (FIG. 3). In some examples, the methods shown in FIGS. 21-28 may be implemented as computer-readable instructions and / or one or more programs, which can be stored in memory and executed by one or more processors of a computerized controller (such as, e.g., the computerized controller 101 shown in FIG. 1 and / or the computing system 800 shown in FIG. 33).

[0094] The ccSCR performance model can be correlated with one or more thermal management control strategies and / or one or more vehicle components that effect thermal management. In some examples, characterization of temperature drops between the end of engine exhaust to the inlet to aftertreatment systems can be used to determine heat loss as a function of different pipe lengths and ambient conditions for various chassis installation configurations. In some examples, measurement of engine exhaust temperature as a function of EGF position can be used to estimate correlation between exhaust temperatures, EGF position, and exhaust mass flow parameters. In some examples, measurement of the influence of EGF positional sensitivity (e.g., commanded vs. actual, drifted EGF valve) can be characterized as it relates to engine emissions and internal hardware limits. In some examples, minimum and maximum EGF positions (end limits of permissible EGF positions) can be determined or identified with respect to maintaining acceptable engine emission limits and maintaining internal hardware limits. In some examples, EGF gradient limitations (e.g., how fast or slow the actuator is permitted to open and close) can be characterized for sustaining optimal performance with respect to actuator durability.

[0095] FIG. 21 shows a logical flow diagram for an exemplary method 400 which can be utilized for controlling sulfur regeneration based on a ccSCR performance model. The method 400 shows a scheme for delaying time-based regeneration. Specifically, the scheme tracks NOx conversion and / or sulfur accumulation during operation of the vehicle under various conditions. As the vehicle operates, the emission control system 100 may perform “passive” regeneration of the- 28 - AFSDOCS:305402722.1catalysts. As such, the scheme associated with the method 400 may delay time-based regeneration, thus conserving fuel.

[0096] At step 402, the computerized controller 101 can receive operating parameters from one or more sensors in the emission control system 100. For example, while the engine is operative, one or more operating parameters can be received at the computerized controller 101 and input into to the ccSCR performance model. Outputs of the ccSCR performance model can be utilized to determine whether one or more criteria are met for ccSCR regeneration based on NOx conversion health are met (step 404), whether one or more criteria are met for ccSCR regeneration based on estimated accumulated sulfur are met (step 406), and / or whether one or more time-based criteria for ccSCR regeneration are met (step 408).

[0097] In one aspect of the present disclosure, determining whether a criterion for regeneration is met may include comparing one or more of the operating parameters with one or more respective threshold values. If the criterion is met (e.g., a parameter meets, exceeds, and / or falls below a predetermined threshold), the method 400 may advance to 410 to request regeneration. In some aspects, the NOx conversion health criteria may be met (step 404) if the NO conversion percentage (as measured by one or more sensors) reaches or falls below a predetermined NO conversion threshold percentage.

[0098] In another aspect, the ccSCR regeneration criteria based on estimated accumulated sulfur criteria may be met (step 406) if the estimated sulfur deposits (e.g., sulfur, sulfur compounds, and / or sulfur-containing deposits) on one or more of the ccSCR catalysts in the ccSCR 106 meets or exceeds a predetermined concentration. In other aspects, the ccSCR regeneration based on estimated accumulated sulfur criteria may be met (step 406) based on the estimated amount of sulfur deposits (or concentration of sulfur deposits) removed from the ccSCR catalyst.

[0099] In yet another aspect, the time-based criteria for ccSCR regeneration criteria may be met if a threshold amount of time has been met or exceeded since the last regeneration during a particular operation scheme of the vehicle. Other determination for whether the criteria have been met may also be implemented according to various aspects of the present disclosure.

[0100] As discussed above, in some examples, the one or more operating parameters can include but are not limited to a fuel mass (e.g., an amount of fuel used or available in the system measured in kg / s or Ib / s), one or more ccSCR temperature values (e.g., a temperature at the ccSCR inlet, a temperature at the ccSCR outlet, a temperature of the ccSCR catalyst, and / or a - 29 - AFSDOCS:305402722.1combination thereof), an amount and / or concentration of NOx at the ccSCR inlet, an amount and / or concentration of NOx at the ccSCR outlet, an operational state of the engine (e.g., an off state or an on state), and / or a time elapsed since a last regeneration cycle has occurred.

[0101] If none of the criteria are met, the one or more parameters can continue to be monitored and provided to the ccSCR performance model while the engine is operative. If one or more of the criteria are met at steps 404-408, a request and / or command for ccSCR regeneration can be generated (step 410). Per step 412, it can be determined whether the engine is a idle operational state (e.g., a vehicle is parked with the engine running) or is in an over the road operational state (e g., the engine is driving movement of the vehicle). If the engine is in a idle operational state, regeneration of the ccSCR 106 can be carried out via control of the EGF control loop (step 414) via, for example, controlling the EGF 104 to achieve a target regeneration temperature (e.g., 500 °C) at the inlet of the ccSCR 106. If the engine is in an over the road operational state (i.e., not in a idle operational state), regeneration of the ccSCR 106 can be carried out via control of the thermal management switch (step 416). Optionally, it can be determined whether the estimated sulfur is greater than one or more thresholds (step 418). Based on meeting a specified threshold, a user notification can be generated (step 420). For example, one or more of the user notifications shown in FIGS. 28-29B and discussed further can be generated based on a determined sulfur zone.

[0102] FIG. 22 shows a logical flow diagram of an exemplary method 404' for determining whether one or more criteria are met for ccSCR regeneration based on NOx conversion health which can be utilized to carry out step 404 of the method 400 illustrated in FIG. 21. It will be appreciated that in some examples, the step 404 can be carried out by a method including additional, fewer, or different steps than those included in FIG. 22.

[0103] As shown in FIG. 22, at step 422 the method 404' includes determining whether the ccSCR 106 is operating at a conversion condition, which can include one or more operating parameters of the engine and / or the ccSCR 106. For example, it can be determined whether the engine is operated at or above a threshold speed (e.g., RPM) and / or within a specified range, whether the ccSCR catalyst is at a threshold temperature and / or within a specified temperature range, and / or whether NOx detected at the inlet and / or the outlet of the ccSCR is at a threshold level and / or within a specified range. In some examples, exemplary ranges for the parameters include the vehicle speed in a range of 45 mph to 80 mph and / or the corresponding engine speed - 30 - AFSDOCS:305402722.1in RPM, ccSCR temperatures in a range of 200 °C to 400 °C, a thermal management mode set an efficiency mode, and / or that NOx is sensed. In some examples, threshold parameters and / or ranges can represent general highway driving conditions experience by the engine during normal operation. If the conversion condition is not met, the operating parameters can continue to be monitored. When the conversion condition is met, an amount of NOx conversion at the ccSCR 106 can be estimated based on the ccSCR temperature and DEF dosing quantity (step 424).

[0104] Per step 426, a normalized difference value between the estimated (modeled) NOx conversion and an NOx conversion based on output from the NOx sensor (e.g., NOx sensors at the inlet and outlet of the ccSCR) can be calculated (e g., as a percentage of NOx converted based on the inlet NOx and / or the outlet NOx), for example, via the NOx conversion health model algorithm discussion above and shown in FIG. 18. It can then be determined whether the normalized difference value is less than a pre-determined threshold (step 428). If the normalized difference value is less than or equal to the threshold, the operating parameters of the engine and the ccSCR 106 can continue to be monitored. If the normalized difference value is greater than the threshold, a request or command regeneration of the ccSCR can be generated. For example, a request or command regeneration of the ccSCR can be generated by and / or transmitted to a controller (e.g., the computerized controller 101) (step 410').

[0105] FIG. 23 shows a logical flow diagram of an exemplary method 406' for determining whether one or more criteria are met for ccSCR regeneration based on estimated sulfur accumulation which can be utilized to carry out step 406 of the method 400 illustrated in FIG.21. It will be appreciated that in some examples, the step 406 can be carried out by a method including additional, fewer, or different steps than those included in FIG. 23.

[0106] As shown in FIG. 23, at step 430 the method 406' includes obtaining a stored cumulative sulfur value from a memory (e.g., a read-only memory (ROM) of the computerized controller 101 (FIG. 1) and / or the computing system 800 (FIG. 8)). In some examples, the obtained stored cumulative sulfur value can be referred to as an electrically erasable programmable read-only memory (EEPROM) cumulative sulfur value that is stored in non-volatile memory and is generated by a running sulfur storage algorithm (which can be, for example, the sulfur storage model algorithm discussed above and shown in FIG. 17). Per step 432, it can be determined whether the ccSCR inlet temperature is less than a threshold. For example, it can be determined whether the ccSCR temperature is less than 375 °C. If the ccSCR temperature is greater than or - 31 - AFSDOCS:305402722.1equal to the threshold temperature, the obtained cumulative sulfur value (the EEPROM cumulative sulfur value from step 430) can be utilized (step 434). An estimate of fast exponential desorption of sulfur deposits can be determined based on the obtained cumulative sulfur value, time elapsed since a last (previous) ccSCR generation, and the ccSCR temperature (step 436). If the ccSCR temperature is below the threshold, an estimate of slow linear adsorption of sulfur deposits can be determined based on an amount of fuel burned and the ccSCR temperature (step 438). Either of the estimate of fast exponential desorption of sulfur deposits or the estimate of slow linear adsorption of sulfur deposits (along with the obtained stored cumulative sulfur value) can be utilized to accumulate a sulfur value (step 440), which can be referred to as a volatile memory cumulative sulfur value. Per step 442, the current EEPROM cumulative sulfur value can then be stored to a memory (e.g., the read-only memory (ROM) discussed above with reference to step 430).

[0107] At step 444, it can be determined whether the current volatile memory cumulative sulfur value is less than a success threshold. In some examples, the success threshold can be a minimum value, such as, for example, a minimum threshold in a range of 0.1 to 0.2 grams of sulfur. If the volatile memory cumulative sulfur value is less than the success threshold, the stored cumulative sulfur value is reset to a calibrated value (step 446). For example, the calibrated sulfur value can be a value slightly greater than the success threshold. In some examples, the calibrated value is in a range of 0.15 to 0.25 grams of sulfur. Additionally, a stopwatch (e.g., stopwatch #1 discussed further below with reference to FIG. 24) can be reset to zero (step 446). If the volatile memory cumulative sulfur value is greater than or equal to the success threshold, it can then be determined whether the volatile memory cumulative sulfur value is greater than a regeneration threshold (step 448). For example, the regeneration threshold can be in a range of 15 to 20 grams of sulfur. If the volatile memory cumulative sulfur value is less than or equal to the regeneration threshold, then the computerized controller can continue to monitor accumulated sulfur. If the volatile memory cumulative sulfur value is greater than the regeneration threshold, a request or command regeneration of the ccSCR 106 can be generated. For example, a request or command regeneration of the ccSCR 106 can be generated by and / or transmitted to a controller (e.g., the computerized controller 101 (FIG. 1)) (step 410").

[0108] FIG. 24 shows a logical flow diagram of an exemplary method 408' for determining whether one or more criteria are met for ccSCR regeneration based on time which can be utilized - 32 - AFSDOCS:305402722.1to carry out step 408 of the method 400 illustrated in FIG. 21. It will be appreciated that in some examples, the step 408 can be carried out by a method including additional, fewer, or different steps than those included in FIG. 24.

[0109] As shown in FIG. 24, at step 450 the method 408' includes determining and / or identifying whether the engine is an operative state (i.e., determining whether the engine is running). If the engine is identified as inoperative, first stopwatch or timer (which can also be referred to herein as “stopwatch #1”) can be paused. If the engine is identified as operative, stopwatch #1 can be run (i.e., time can be accumulated at stopwatch #1) (step 454). Per step 462, it can be determined whether stopwatch #1 is greater than a threshold time for initiating regeneration. In some examples, the threshold time for initiating regeneration can be in a range of 50 to 200 hours, such as e.g., 100 hours. If it is determined that time accumulated at stopwatch #1 is less than or equal to the threshold time for initiating regeneration, stopwatch #1 can continue to accumulate time while the engine is operative. If it is determined that time accumulated at stopwatch #1 is greater than the threshold time for initiating regeneration, a request or command regeneration of the ccSCR can be generated. For example, a request or command regeneration of the ccSCR can be generated by and / or transmitted to a controller (e.g., the computerized controller 101 (FIG. 1)) (step 410'"). Stopwatch #1 can be set to zero after or during regeneration.

[0110] Optionally, time can also be accumulated at a second stopwatch or timer (which can also be referred to herein as “stopwatch #2”) dependent on the ccSCR temperature (step 458). For example, time may be accumulated at stopwatch #2 for an amount of time at a current temperature of the ccSCR 106 (i.e., an amount of time at the current temperature). Per step 460, it can be determined if stopwatch #2 is greater than a success threshold. In some examples, the success threshold can be a threshold temperature for the ccSCR 106 for a threshold amount of time. If the reading from stopwatch #2 is less than or equal to the success threshold, time can continue to accumulate at stopwatch #2. If the reading from stopwatch #2 is greater than the success threshold, a stored estimated sulfur value can be reset to a calibrated value (which can be utilized in the method 406') and both stopwatch #1 and stopwatch #2 can be reset to zero (step 462).

[0111] FIGS. 25 and 26 illustrate logical flow diagrams for exemplary methods for regeneration. As discussed above with respect to the method 400 of FIG. 21, after a sulfur regeneration- 33 - AFSDOCS:305402722.1request / command is generated (step 410) it can be determined whether the engine is in idle (step 412). If the engine is in idle, regeneration can be carried out via the EGF control loop (step 414), whereas if the engine is not in idle, regeneration can be carried out via the thermal management switch control (step 416). FIG. 25 illustrates an exemplary method 500 for regeneration during idle (e.g., such as at step 414 of the method 200). FIG. 26 illustrates an exemplary method 600 for regeneration during over the road driving (e.g., such as at step 416 of the method 400).

[0112] As can be seen in FIG. 25, the method 500 includes determining whether the DOC inlet is at a threshold temperature for a threshold amount of time (step 502). For example, the threshold temperature can be in a range of 270 °C to 320 °C and the threshold time can be in range of 12 minutes to 20 minutes. Other temperatures, temperature ranges, threshold time, and / or threshold time ranges may also be used. If not, the EGF 104 can be controlled to achieve the target temperature for the threshold amount of time (step 504) as discussed above. Once the DOC inlet is at the threshold temperature for the threshold amount of time, an appropriate regeneration strategy can be selected and / or determined based on generation and / or receipt of one or more regeneration requests (step 506). For example, the computerized controller 101 may determine whether regeneration requests have been generated for sulfur regeneration, soot regeneration, and / or hydrocarbon (HC) dosing. Depending on which regeneration requests are received, the method 500 includes selecting one of the of the regeneration control strategies 508a-508g.Depending on which one of the regeneration strategies 508a-508g is selected, a corresponding one of the sets of control commands 510a-510g can be implemented according to various aspects of the present disclosure. In FIG. 25, the values in the set of control commands 510a-510g are shown as examples and other temperatures and / or temperature ranges may also be implemented.

[0113] The control commands 510a-510g include instructions for controlling the EGF control loop and / or other components of the emission control system 100 to achieve one or more regeneration conditions, which can include, for example, operation in a hot thermal management regeneration mode (“hot mode”), EGF control to achieve a target sulfur regeneration temperature (e.g., 500 °C) at the ccSCR inlet (EGF target 500 C @ pSCR In), hydrocarbon dosing to achieve a target HC regeneration temperature (e.g., 580 °C or 535 °C) at the DPF outlet (HC Dosing targets 580 °C @ DPF Out and HC Dosing targets 535 °C @ DPF Out), and / or EGF control to achieve a target soot regeneration temperature (e.g., 280 °C) at the DOC inlet (EGF targets 280 °C @ DOC In)- 34 - AFSDOCS:305402722.1

[0114] In some examples, the “keep warm” mode maintains the mSCR 124 between 200 °C to 250 °C. The keep warm mode can ensure that the mSCR 124 experiences a sustained exhaust temperature of between 200 °C to 240 °C, and can utilize a combination of the EGF 104, EGR (exhaust gas recirculation) and half engine combustion to achieve the targeted exhaust temperatures. Here, the EGR relates to the flow rate of the exhaust system that may be controlled by a valve and / or other actuators. Modulating the actuator position changes how much exhaust gas is recirculated and there by the engine exhaust temperatures. In some examples, the hot mode is an operational mode that is hotter than a “keep warm” mode. In some examples, the hot mode can ensure that the ccSCR 106 experiences a sustained exhaust temperature of > 400 °C and utilizes a combination of the EGF 104 and very late post injection (which is non-torque contributing) to achieve very high exhaust temperature (e.g., greater than 350 °C, 400 °C, 450 °C, 500 °C, etc.). In some examples, the engine be operated in an efficiency mode (that is, a mode that is efficient with regard to fuel economy and / or emissions) that consumes less fuel and at a lower exhaust temperature than the hot mode.

[0115] The target temperature discussed above can depend on the torque / speed, but generally hot mode operation aims for a temperature of 500 °C for one or more components in the emission control system 100, keep warm mode operation aims for a slower warm up, and efficiency mode operation aims to control emissions. In some examples, the foregoing modes can be implemented via calibration of multiple actuators associated with the emission control system 100. As discussed above, the hot mode can maintain the ccSCR 106 at about 500 °C (e.g., + / - 10 °C), and the keep warm mode can maintain the mSCR 124 at a temperature that is in a range of 200 °C to 250 °C.

[0116] In one aspect of the present disclosure, the following scheme may be utilized for sulfur and soot regeneration (510b). In some examples, operation in a hot mode can be enabled after enablement criteria (such as, e.g., after a period of time of engine operation) are met (Engine hot mode). In some examples, the scheme for controlling the EGF 104 to achieve a target sulfur regeneration temperature includes first targeting a temperature that is equal to the current ccSCR temperature plus an additional amount and then dividing by two (e.g., (current temp + 500) / 2) and then targeting the sulfur regeneration temperature (EGF target 500 C @ pSCR In). In some examples, hydrocarbon dosing can be initiated after the DOC inlet reaches a light-off- 35 - AFSDOCS:305402722.1temperature and / or one or more other criteria (such as e.g., a specified exhaust gas mass flow rate restriction (> 200 g / hr)) are met (HC Dosing targets 580 C @ DPF Out).

[0117] In another aspect, soot only regeneration (510e) may be performed as follows). In some examples, the scheme for controlling the EGF 104 to achieve a target soot regeneration temperature at the DOC inlet can be an approximate temperature target and the precise target can be determined from a model of DOC light-off temperatures (EGF targets 280 C @ DOC In).

[0118] As can be seen in FIG. 26, the method 600 includes selecting and / or determining an appropriate regeneration strategy based on generation and / or receipt of one or more regeneration requests (step 602). For example, the computerized controller 101 may determine whether regeneration requests have been generated for sulfur regeneration, soot regeneration, and / or hydrocarbon dosing. Depending on which regeneration requests are received, the method 600 includes selecting one of the of the regeneration control strategies 604a-604g. Depending on which one of the regeneration strategies 604a-604g is selected, a corresponding one of the sets of control commands 606a-606g can be implemented according to various aspects of the present disclosure. In FIG. 26, the values in the set of control commands 606a-606g are shown as examples and other temperatures and / or temperature ranges may also be implemented.

[0119] The control commands 606a-606g can include instructions for controlling the thermal management switch control and / or other components of the emission control system 101 to achieve one or more regeneration conditions, which can include, for example, operation in the hot mode, operation in engine mode switch control between a warm mode and a hot regeneration mode to achieve a target temperature (e.g., 300 °C) at the DOC inlet (Targeting 300 C @ DOC In), and / or hydrocarbon dosing to achieve a target HC regeneration temperature (e.g., a temperature in a range of 535 °C to 580 °C) at the DPF outlet (HC Dosing targets 580 C @ DPF Out and HC Dosing targets 535 C @ DPF Out).

[0120] In some examples, selecting one of the regeneration control strategies and implementing a corresponding one of the sets of control commands in the methods 500 and 600 can include utilizing a truth table or matrix, such as, for example, the truth table shown in FIG. 27.

[0121] In some examples, a control strategy for soot and sulfur regeneration can be represented in a control matrix, for example, the matrix shown in FIG. 28. The control matrix can include cross-reference of estimated sulfur within a specified range (zone) and estimated soot within a specified range (zone). In some examples, sulfur zone 1 can be in a range of 1g to 5 g of sulfur,- 36 - AFSDOCS:305402722.1sulfur zone 2 can be in a range of 3 g to 7 g of sulfur, sulfur zone 3 can be in a range of 8 g to 12 g of sulfur, sulfur zone 4 can be in a range of 13 g to 17 g of sulfur, and sulfur zone 5 can be in a range of 18 g to 22 g of sulfur. Other ranges of sulfur may also be utilized for the control matrix.

[0122] In some examples, soot zone 1 can be in a range of 100 g to 118 g of soot, soot zone 2 can be in a rage of 138 g to 148 g of soot, soot zone 3 can be in a range of 138 g to 148 g of soot, soot zone 4 can be in a range of 148 g to 158 g of soot, soot zone 5 can be above 158 g. Other ranges of soot may also be utilized for the control matrix.

[0123] Depending on the sulfur and soot zones, over-the-road soot regeneration (OTR), high-idle soot regeneration (HIR), over-the-road sulfur regeneration (sOTR), high-idle sulfur regeneration (sHIR) can be carried out via one or more of the methods and / or control strategies / commands discussed above. Alternatively or additionally, one or more user warnings and / or signals can be generated based on the current sulfur and / or soot zones, such as those illustrated in FIGS. 28-29B. These warnings and / or signals are examples and more, less, and / or different warnings and / or signals may be utilized according to various aspects of the present disclosure.

[0124] The user warnings can be indicative escalating conditions of the emission control system 100. For example, a zone 2 signal (e.g., a solid emission symbol indicator) can indicate that an over-the-road regeneration is being performed but no user intervention is required. A zone 5 signal (e.g., flashing emission symbol, check engine, and stop engine indicators) can indicate that the engine should be stopped and user intervention is required. FIG. 30 functional diagram of the soot and sulfur control matrix of FIG. 28 in combination with the ccSCR performance model discussed above with reference to FIGS 2A-20H.

[0125] In some examples, depending on the kind of regeneration requested, the emission control system 100 can select between engine modes to sustain the required exhaust temperature in order to complete the regeneration process. In some examples, sulfur regeneration can include an over-the-road request or a parked regeneration request depending on the operational state of the vehicle. In some examples, for the over-the-road sulfur regeneration request, the engine control system can implement the hot mode exclusively if sulfur regeneration is required during over the road operation. In some examples, for the parked sulfur regeneration request, the emission control system 100 can implement the hot mode with PID control on the EGF 104 to target a specific temperature (e.g., ccSCR of 500 °C) required to complete the process, and a sub-- 37 - AFSDOCS:305402722.1controller can open or close the EGF 104 as required to achieve the target temperature regardless of external boundary conditions.

[0126] In some examples, soot regeneration includes an over-the-road request or a parked regeneration request depending on the operational state of the vehicle. In some examples, for the over-the-road soot regeneration request, the emission control system 100 can choose a combination of the keep warm mode and the hot mode. Because the requirement for soot regeneration is to provide exhaust temperatures of 300 °C to the inlet of diesel oxidation catalyst, the hot mode in certain drive cycles may be too hot. In order to limit waste of exhaust enthalpy, the emission control system 100 can switch to the keep warm mode to maintain the exhaust temperature within the target temperature range for soot regeneration. In some examples, for the parked regeneration request, the emission control system 100 can implement the hot mode with PID control on the EGF to target a specific temperature (e.g., DOC inlet of 350 °C) required to complete the process, and a sub-controller can open or close EGF as and when required to achieve the target temperature regardless of external boundary conditions.

[0127] As discussed above, in some examples, controlling regeneration based on an SCR performance model via the method 400 can limit frequency of regeneration cycles and / or increase fuel efficiency. In some examples, controlling regeneration based on an SCR performance model via the method 400 can improve long-term health of the SCR catalyst and / or limit the need for repair and / or replacement of the catalyst.

[0128] Turning to FIGS. 31-32 exemplary methods for controlling DEF dosing to each of the mSCR 124 and / or the ccSCR 106 are shown and described. In some examples, the methods of FIGS. 31-32 include one or more of the features and / or steps of steps 218-224 of the method 200 (FIG. 2A) discussed above. In some examples, the methods shown in FIGS. 31-32 are a plurality of computer-readable instructions and / or one or more programs, which can be stored in memory and executed by one or more processors of a computerized controller (such as, e.g., the computerized controller 101 shown in FIG. 1 and / or the computing system 800 shown in FIG.33).

[0129] FIG. 31 shows an exemplary detailed method 700 for controlling DEF dosing to each of the mSCR 124 and / or the ccSCR 106. At step 702, the method 700 includes determining whether a temperature at the ccSCR 106 meets one or more temperature criteria. In some examples, it can be determined whether a temperature of the ccSCR 106 is in a specified range (such as, e.g., - 38 - AFSDOCS:305402722.1within a range of 200 °C to 500 °C). In some examples, it can be determined whether a temperature of the ccSCR 106 is at least a minimum temperature (such as e.g., 200 °C). If the temperature of the ccSCR 106 does not meet the temperature criteria, dosing at the ccSCR can be inhibited (step 704). In some examples, DEF dosing may occur at the mSCR 124 for NOx conversion while no DEF dosing occurs at the ccSCR 106. If the ccSCR temperature criteria are met, it can be determined whether a temperature at the mSCR 124 meets one or more temperature criteria (step 706). In some examples, it can be determined whether a temperature of the mSCR 124 is in a specified range (such as, e.g., within a range of 200 °C to 270 °C). In some examples, it can be determined whether a temperature of the mSCR 124 is less than a maximum temperature (such as e.g., 270 °C). If the temperature criteria for the mSCR 124 are not met, DEF dosing to the ccSCR 106 and the mSCR 124 can be controlled based on a ccSCR storage controller (step 708). In some examples, the SCR storage control method models the instantaneous NH3 stored in the catalyst and targets a certain value in the SCR 106.

[0130] If the temperature criteria for the ccSCR 106 and the mSCR 124 are met, the method 700 can implement DEF dosing trim control via steps 710-718. Per step 710, an mSCR NOx conversion capability (e.g., a maximum mSCR NOx conversion capability) can be estimated based on the mSCR catalyst temperature and exhaust mass flow. In some examples, estimating mSCR NOx conversion capability includes accessing a look-up table cross-referencing mSCR catalyst temperature and exhaust mass flow to maximum NOx conversion capability at the mSCR.

[0131] Next, a percentage of NOx to be converted the ccSCR 106 can be determined from the estimated NOx conversion capability at the mSCR 124 and / or NOx sensor value at the ccSCR inlet (step 712). An untrimmed stoichiometric ratio of NFb / NOx conversion (which can also be referred to as an “ammonia-to-NOx ratio (ANR)” can be determined from the ccSCR catalyst temperature and exhaust mass flow (step 714). The untrimmed ratio can be multiplied by the percentage of NOx to be converted at the ccSCR 106 to generate a trimmed stoichiometric ratio of NHs / NOx conversion (step 716). The DEF injection system for each of the ccSCR 106 and / or the mSCR 124 (i.e., DEF dosing to each of the ccSCR and the mSCR) can be controlled based on the trimmed stoichiometric ratio of NFh / NOx conversion (step 718).

[0132] As discussed above, in some examples, the method 700 can enable maximum NOx conversion to occur at the mSCR 124, while minimizing NOx conversion at the ccSCR 106. In - 39 - AFSDOCS:305402722.1some examples, controlling dosing based on the SCR trim control method 700 can limit frequency of regeneration cycles and / or increase fuel efficiency. In some examples, controlling dosing based on the SCR trim control method 700 can improve long-term health of the upstream SCR catalyst and / or limit the need for repair and / or replacement of the catalyst.

[0133] FIG. 32 shows an exemplary high-level method 720 for controlling DEF dosing to each of the mSCR 124 and the ccSCR 106. At step 722, the method 720 includes receiving operating parameters from one or more the sensors in the emission control system 100 (such as, e.g., temperature readings from one or more of the temperature sensors at the ccSCR 106 and / or the mSCR 124). At step 724, it can be determined whether one or more criteria are met for operating the emission control system 100 under DEF trim control based on one or more of the operating parameters. For example, it can be determined whether a temperature of the ccSCR 106 and / or the mSCR 124 each meet a minimum temperature and / or are within a specified temperature range for performing DEF trim control. If the one or more trim control criteria are not met, an alternative strategy can be utilized for controlling DEF dosing (such as, e.g., those discussed below with respect to the method 700 shown in FIG. 32) and the operating parameters can continue to be monitored. If the criteria for one or more trim control are met, the computerized controller can implement steps 728-736.

[0134] At step 728, based at least on one or more operating parameters related to the mSCR 124 (e.g., a temperature of the mSCR 124) and / or other or more other operating parameters (e.g., exhaust mass flow), an estimated maximum NOx conversion capability at the mSCR 124 can be determined. For example, the computerized controller 101 can reference a lookup table correlating the selected operating parameters to NOx conversion capability at the mSCR 124. Alternatively or additionally, the computerized controller 101 may use one or more algorithms to determine the NOx conversion capability of the mSCR 124. Other methods may also be used according to certain aspects of the present disclosure.

[0135] Based at least on the maximum NOx conversion capability at the mSCR 124, a percentage of NOx to be converted at the ccSCR 106 is determined (step 730). In some examples, a minimum NOx required conversion at the ccSCR 106 is determined based on the maximum NOx conversion capability at the mSCR 124. A first dosing control value or parameter (e.g., a dosing rate, a dosing timing, and / or a dosing quantity) for controlling dosing at an upstream DEF injection system (e.g., the DEF injection system 108) can be determined based - 40 - AFSDOCS:305402722.1on the percentage of NOx to be converted at the ccSCR 106 (step 732). A second dosing control value or parameter (e.g., a dosing rate, a dosing timing, and / or a dosing quantity) for controlling dosing at a downstream DEF injection system (e.g., the DEF injection system 126) can be determined based on the percentage of NOx to be converted at the ccSCR 106 and / or the maximum NOx conversion capability at the mSCR 124 (step 734). Per step 736, the computerized controller can cause operation of each of the DEF injection systems 108, 126 based on their respective first and second dosing control values or parameters.

[0136] FIG. 33 depicts a generalized example of a suitable computing system 800 in which the described methods may be implemented. The computing system 800 is not intended to suggest any limitation as to scope of use or functionality, as the innovations may be implemented in diverse general-purpose or special -purpose computing systems. For example, the computing system 800 can be used to implement hardware and software.

[0137] With reference to FIG. 33, the computing system 800 includes one or more processing units 810, 815, non-volatile memory 820, and memory 825. In FIG. 33, this basic configuration 830 is included within a dashed line. The processing units 810, 815 execute computer-executable instructions, including instructions for generating shape models, locating fiducials in images, and / or aligning an output device with an article as disclosed herein. A processing unit can be a general-purpose central processing unit (“CPU”), processor in an application-specific integrated circuit (“ASIC”), or any other type of processor. In a multi-processing system, multiple processing units execute computer-executable instructions to increase processing power. For example, FIG. 33 shows a central processing unit 810 as well as a graphics processing unit (“GPU”) or co-processing unit 815. The tangible memory 825 may be volatile memory (e.g., registers, cache, RAM), non-volatile memory (e.g., ROM, EEPROM, flash memory, etc.), or some combination of the two, accessible by the processing unit(s). The memory 825 stores software 880 implementing one or more innovations described herein, in the form of computerexecutable instructions suitable for execution by the processing unit(s).

[0138] A computing system may have additional features. For example, the computing system 800 includes storage 840, one or more input devices 850, one or more output devices 860, and one or more communication connections 870. An interconnection mechanism (not shown) such as a bus, controller, or network interconnects the components of the computing system 800. Typically, operating system software (not shown) provides an operating environment for other - 41 - AFSDOCS:305402722.1software executing in the computing system 800, and coordinates activities of the components of the computing system 800.

[0139] The tangible storage 840 may be removable or non-removable, and includes magnetic disks, magnetic tapes or cassettes, CD-ROMs, DVDs, or any other medium which can be used to store information and which can be accessed within the computing system 800. The storage 840 stores instructions for the software 880 implementing one or more innovations described herein.

[0140] The input device(s) 850 may be a touch input device such as a keyboard, mouse, pen, or trackball, a voice input device, a scanning device, microphone, button, pedal, or another device that provides input to the computing system 800. For video encoding, the input device(s) 850 may be a camera with an image sensor, video card, TV tuner card, or similar device that accepts video input in analog or digital form, or a CD-ROM, CD-RW, DVD, or Blu-Ray that reads video samples into the computing system 800. The output device(s) 860 may be a display, printer, speaker, CD-writer, or another device that provides output from the computing system 800.

[0141] The communication connection(s) 870 enable communication over a communication medium (e.g., a connecting network) to another computing entity. The communication medium conveys information such as computer-executable instructions, compressed graphics information, video, or other data in a modulated data signal. The communication connect! on(s) 1170 are not limited to wired connections (e.g., megabit or gigabit Ethernet, Infiniband, Fibre Channel over electrical or fiber optic connections) but also include wireless technologies (e.g., RF connections via Bluetooth, WiFi (IEEE 802.1 la / b / n), WiMax, cellular, satellite, laser, infrared) and other suitable communication connections for providing a network connection for the disclosed agents, bridges, and agent data consumers. In a virtual host environment, the communication(s) connections can be a virtualized network connection provided by the virtual host.

[0142] Some embodiments of the disclosed methods can be performed using computerexecutable instructions implementing all or a portion of the disclosed technology in a computing cloud 890. For example, disclosed computer-readable instructions can be executed by processors located in the computing environment 830, or the disclosed computer-readable instructions can be executed on servers located in the computing cloud 890.

[0143] Computer-readable media are any available media that can be accessed within a computing system 800. By way of example, and not limitation, with the computing system 800,- 42 - AFSDOCS:305402722.1computer-readable media include memory 820 and / or storage 840. As should be readily understood, the term computer-readable storage media includes the media for data storage such as memory 820 and storage 840 but does not include transmission media such as modulated data signals or other transitory signals.

[0144] The innovations can be described in the general context of computer-executable instructions, such as those included in program modules, being executed in a computing system on a target real or virtual processor. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Computer-executable instructions for program modules may be executed within a local or distributed computing system.

[0145] In some examples, the computerized controller 101 shown in FIG. 1 can be configured with one or more of the components and / or one or more of the functionalities of computing system 800.

[0146] Aspects of the present disclosure include a method of generating a performance model for an upstream SCR in an emission control system including the upstream SCR and a downstream SCR, the method comprising generating first data modeling sulfur poisoning and recovery of the upstream SCR, generating second data modeling long-term sulfation effects on the upstream SCR, generating third data modeling DEF dosing effects on sulfation of the upstream SCR, and generating, based the first, second, and third data, one or more algorithms for the performance model of the upstream SCR.

[0147] Aspects of the present disclosure include the method above, wherein the one or more algorithms comprise an NOx conversion health algorithm for the upstream SCR and a sulfur storage model for the upstream SCR.

[0148] Aspects of the present disclosure include any of the methods above, wherein the generating the first data comprises modeling NOx conversion at the upstream SCR relative to a temperature of an inlet of the upstream SCR over one or more selected periods of time.

[0149] Aspects of the present disclosure include any of the methods above, wherein the generating the first data comprises modeling percentage of NO conversion at the upstream SCR during sulfur poisoning relative to temperature over time.- 43 - AFSDOCS:305402722.1

[0150] Aspects of the present disclosure include any of the methods above, wherein the generating the first data comprises modeling SO2 concentration at the upstream SCR relative to temperature.

[0151] Aspects of the present disclosure include any of the methods above, wherein the generating the second data comprises modeling NOx conversion at the upstream SCR over a series of certification cycles.

[0152] Aspects of the present disclosure include any of the methods above, wherein the generating the second data comprises modeling NOx conversion at the upstream SCR relative to an internal temperature of the upstream SCR.

[0153] Aspects of the present disclosure include any of the methods above, wherein the generating the second data comprises modeling sulfur unloading at the upstream SCR at each of a baseline condition after regeneration and at a sulfur-poisoning condition.

[0154] Aspects of the present disclosure include any of the methods above, wherein the generating the third data comprises modeling SO2 adsorption at the upstream SCR over time at one or more NH3 dosing rates.

[0155] Aspects of the present disclosure include any of the methods above, wherein the one or more algorithms comprise an algorithm modeling performance of the upstream SCR.

[0156] Aspects of the present disclosure include any of the methods above, wherein the one or more algorithms comprise an algorithm modeling sulfur storage of the upstream SCR.

[0157] Aspects of the present disclosure include an emission control system for an engine, the emission control system including an upstream SCR, a downstream SCR, and a computerized controller, the computerized controller comprising a data communication interface, one or more processors, a memory having a plurality of computer-readable instructions stored thereon, the plurality of computer-readable instructions configured to, when executed by the one or more processors, cause the system to receive, from one or more sensors via the data communication interface, one or more operating parameters related to the upstream SCR, input the one or more operating parameters into an upstream SCR performance model, based at least on the input of the one or more operating parameters into the upstream SCR performance model determine whether an NOx conversion health sulfur regeneration criteria is met, determine whether an accumulated sulfur regeneration criteria is met, and determine whether a time-based sulfur regeneration criteria is met, and based at least on a determination that one or more of the NOx conversion - 44 - AFSDOCS:305402722.1health sulfur regeneration criteria, the accumulated sulfur regeneration criteria, or the time-based sulfur regeneration criteria are met, cause the emission control system to perform sulfur regeneration.

[0158] Aspects of the present disclosure include the emission control system above, further comprising an exhaust gas flap (EGF) control loop and athermal management control system, wherein the plurality of computer-readable instructions configured to, when executed by the one or more processors, cause the system to: determine whether the engine is in a idle operational state; based at least on a determination that the engine is in the idle operational state, cause the performance of sulfur regeneration via the EGF control loop; and based at least on a determination that the engine in not in the idle operational state, cause the performance of sulfur regeneration via the thermal management control system.

[0159] Aspects of the present disclosure include any of the emission control systems above, wherein for the determination of whether the NOx conversion health sulfur regeneration criteria is met, the plurality of computer-readable instructions configured to, when executed by the one or more processors, cause the system to determine that one or more engine operating parameters indicative of operating at a conversion condition are met, estimate an amount of NOx conversion at the upstream SCR based on a current temperature of the upstream SCR and a DEF dosing quantity at the upstream SCR, determine a normalized NOx conversion difference value based at least on the estimated amount of NOx conversion and an NOx conversion health model for the upstream SCR, determine whether the normalized NOx conversion difference value is less than an NOx regeneration threshold, based at least on the normalized NOx conversion difference value being less than the NOx regeneration threshold, determine that the NOx conversion health sulfur regeneration criteria is met, and based at least on the normalized NOx conversion difference value being greater than or equal to the NOx regeneration threshold, determine that the NOx conversion health sulfur regeneration criteria is not met.

[0160] Aspects of the present disclosure include any of the emission control systems above, wherein the one or more engine operating parameters indicative of operating at the conversion condition comprise one or more of an engine speed being within a specified range, a temperature of the upstream SCR being within a specified range, or an NOx detected at one or more of an inlet or an outlet of the upstream SCR is within a specified range.- 45 - AFSDOCS:305402722.1

[0161] Aspects of the present disclosure include any of the emission control systems above, wherein for the determination of whether the accumulated sulfur regeneration criteria is met, the plurality of computer-readable instructions configured to, when executed by the one or more processors, cause the system to obtain a stored EEPROM cumulative sulfur value from memory, determine whether a temperature of the upstream SCR is below a threshold temperature, based at least on a determination that the temperature of the upstream SCR is below the threshold temperature, determine an estimated slow linear adsorption of sulfur deposits at the upstream SCR from an amount of fuel burned and the temperature of the upstream SCR, and based at least on a determination that the temperature of the upstream SCR is greater than or equal to the threshold temperature, determine an estimated fast exponential desorption of sulfur deposits at the upstream SCR from the obtained EEPROM cumulative sulfur value, a time elapsed since a last regeneration, and the temperature of the upstream SCR.

[0162] Aspects of the present disclosure include any of the emission control systems above, wherein for the determination of whether the accumulated sulfur regeneration criteria is met, the plurality of computer-readable instructions are further configured to, when executed by the one or more processors, cause the system to accumulate a volatile memory sulfur value from one of the estimated slow linear adsorption of sulfur deposits at the upstream SCR or the estimated fast exponential desorption of sulfur deposits at the upstream SCR, determine whether the cumulative volatile memory sulfur value is greater than a sulfur regeneration threshold, based at least on the cumulative volatile memory sulfur value being less than the sulfur regeneration threshold, determine that the NOx conversion health sulfur regeneration criteria is met, and based at least on the cumulative volatile memory sulfur value being greater than or equal to the sulfur regeneration threshold, determine that the NOx conversion health sulfur regeneration criteria is not met.

[0163] Aspects of the present disclosure include any of the emission control systems above, wherein for the determination of whether the accumulated sulfur regeneration criteria is met, the plurality of computer-readable instructions are further configured to, when executed by the one or more processors, cause the system to store the EEPROM cumulative sulfur value to the memory, determine whether the cumulative volatile memory sulfur value is less than a success threshold, wherein the success threshold is a minimum amount of sulfur, and based at least on a determination that the cumulative volatile memory sulfur value is less than the success threshold,- 46 - AFSDOCS:305402722.1reset the cumulative volatile memory sulfur value to a calibrated value and reset a first stopwatch to zero.

[0164] Aspects of the present disclosure include any of the emission control systems above, wherein for the determination of whether the time-based sulfur regeneration criteria is met, the plurality of computer-readable instructions configured to, when executed by the one or more processors, cause the system to determine that the engine is operative, based on the determination that the engine is operative, run the first stopwatch, determine whether a current time at the first stopwatch is greater than a time-based regeneration threshold, and based at least on the current time at the first stopwatch being less than the time-based regeneration threshold, determine that the time-based regeneration criteria is met, and based at least on the current time at the first stopwatch being greater than or equal to the time-based regeneration threshold, determine that the time-based regeneration criteria is not met.

[0165] Aspects of the present disclosure include any of the emission control systems above, wherein for the determination of whether the time-based sulfur regeneration criteria is met, the plurality of computer-readable instructions are further configured to, when executed by the one or more processors, cause the system to determine a current temperature of the upstream SCR, run a second stopwatch to track an amount of time at the current temperature, determine whether the time at the second stopwatch is greater than a success threshold, wherein the success threshold is a threshold temperature for a threshold amount of time, and based on the time at the second stopwatch being greater than the success threshold, reset each of the first stopwatch and the second stopwatch to zero.

[0166] Aspects of the present disclosure include an emission control system for an engine, the emission control system including an upstream SCR, a downstream SCR, and a computerized controller, the computerized controller comprising: a data communication interface; one or more processors; a memory having a plurality of computer-readable instructions stored thereon, the plurality of computer-readable instructions configured to, when executed by the one or more processors, cause the system to receive, from one or more sensors via the data communication interface, one or more operating parameters related to the downstream SCR and one or more operating parameters related to the upstream SCR, based at least on the one or more operating parameters related to the downstream SCR, determine a maximum NOx conversion capability at the downstream SCR, based at least on the maximum NOx conversion capability at the- 47 - AFSDOCS:305402722.1downstream SCR, determine a percentage of NOx to be converted at the upstream SCR, based at least on the percentage of NOx to be converted at the upstream SCR, determine a first dosing control value for the upstream SCR and a second dosing control value for the downstream SCR, based at least on the first dosing control value for the upstream SCR, cause DEF dosing at a first amount at the upstream SCR, and based at least on the second dosing control value for the downstream SCR, cause DEF dosing at a second amount at the downstream SCR.

[0167] Aspects of the present disclosure include any of the emission control systems above, wherein the one or more operating parameters related to the downstream SCR comprise a temperature of a catalyst of the downstream SCR and an exhaust mass flow.

[0168] Aspects of the present disclosure include any of the emission control systems above, wherein the determination of the percentage of NOx to be converted at the upstream SCR is further based on an NOx sensor value at an inlet of the upstream SCR.

[0169] Aspects of the present disclosure include any of the emission control systems above, wherein the determination of the first dosing control value and the second dosing control value comprises determination of an untrimmed stoichiometric ratio of NH3 / N0x conversion for the upstream SCR based at least a temperature of a catalyst of the upstream SCR and an exhaust mass flow, determination of a trimmed stoichiometric ratio of NH3 / N0x conversion by multiplying the untrimmed stoichiometric ratio of NH3 / N0x conversion by the percentage of NOx to be converted at the upstream SCR, and determination of the first dosing control value and the second dosing control value based on the trimmed stoichiometric ratio of NH3 / N0x conversion.

[0170] Aspects of the present disclosure include a method of reducing undesirable emission pollutant from a vehicle, including receiving a plurality of parameters associated with one or more of first sulfur deposits on a first catalyst of a first selective catalytic reduction (SCR) system, second sulfur deposits on a second catalyst of a second SCR system, or soot deposits on a diesel particulate filter, wherein the first SCR system is disposed at a first position in an exhaust stream of the vehicle and the second SCR system is located at a second position in the exhaust stream that is downstream of the first position, determining, based on the plurality of parameters, to remove a selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits, and removing the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits by performing one or more of changing- 48 - AFSDOCS:305402722.1temperatures of the first catalyst, the second catalyst, or the diesel particulate filter, or injecting diesel exhaust fluid (DEF) into the first SCR system or the second SCR system.

[0171] Aspects of the present disclosure include any of the methods above, wherein receiving the plurality of parameters includes receiving a first set of parameters associated with the first SCR system including a first nitrogen oxides (NOx) conversion percentage, a first urea dosing quantity, a first temperature, a second set of parameters associated with the second SCR system including a second NOx conversion percentage, a second urea dosing quantity, and a second temperature, and a third set of parameters including a fuel amount, a time since last regeneration, and an engine operation duration.

[0172] Aspects of the present disclosure include any of the methods above, wherein determining to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits includes determining to remove the first sulfur deposits or the second sulfur deposits by obtaining a NOx conversion health model, obtaining a sulfur storage model, inputting the first set of parameters, the second set of parameters, and at least a portion of the third set of parameters into the NOx conversion health model and the sulfur storage model.

[0173] Aspects of the present disclosure include any of the methods above, wherein determining to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits includes determining to remove the first sulfur deposits or the second sulfur deposits by comparing the time since last regeneration with a threshold time.

[0174] Aspects of the present disclosure include any of the methods above, wherein determining to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits includes determining to remove the first sulfur deposits or the second sulfur deposits based on one or more of a first output of the NOx conversion health model, a second output of the sulfur storage model, or the time since last regeneration being longer than the threshold time.

[0175] Aspects of the present disclosure include any of the methods above, further including, in response to determining to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits, generating a request for regeneration.

[0176] Aspects of the present disclosure include any of the methods above, further including performing the regeneration via an exhaust gas flap scheme or a thermal management control scheme.- 49 - AFSDOCS:305402722.1

[0177] Aspects of the present disclosure include an exhaust control system, including one or more memories storing instructions, and one or more processors configured to execute the instructions to receive a plurality of parameters associated with one or more of first sulfur deposits on a first catalyst of a first selective catalytic reduction (SCR) system, second sulfur deposits on a second catalyst of the second SCR system, or soot deposits on a diesel particulate filter, wherein the first SCR system is disposed at a first position in an exhaust stream of the vehicle and the second SCR system is disposed at a second position in the exhaust stream that is downstream of the first position, determine, based on the plurality of parameters, to remove a selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits, and remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits by performing one or more of changing temperatures of the first catalyst, the second catalyst, or the diesel particulate filter, or injecting diesel exhaust fluid (DEF) into the first SCR system or the second SCR system.

[0178] Aspects of the present disclosure include the exhaustion control system above, wherein the plurality of parameters comprise a first set of parameters associated with the first SCR system including a first nitrogen oxides (NOx) conversion percentage, a first urea dosing quantity, a first temperature, a second set of parameters associated with the second SCR system including a second NOx conversion percentage, a second urea dosing quantity, and a second temperature, and a third set of parameters including a fuel amount, a time since last regeneration, and an engine operation duration.

[0179] Aspects of the present disclosure include any of the exhaustion control systems above, wherein the one or more processors are further configured to determine to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits by obtaining a NOx conversion health model, obtaining a sulfur storage model, inputting the first set of parameters, the second set of parameters, and at least a portion of the third set of parameters into the NOx conversion health model and the sulfur storage model.

[0180] Aspects of the present disclosure include any of the exhaustion control systems above, wherein the one or more processors are further configured to determine to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits by comparing the time since last regeneration with a threshold time.- 50 - AFSDOCS:305402722.1

[0181] Aspects of the present disclosure include any of the exhaustion control systems above, wherein the one or more processors are further configured to determine to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits based on one or more of a first output of the NOx conversion health model, a second output of the sulfur storage model, or the time since last regeneration being longer than the threshold time.

[0182] Aspects of the present disclosure include any of the exhaustion control systems above, wherein the one or more processors are further configured to generate a request for regeneration in response to determining to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits.

[0183] Aspects of the present disclosure include any of the exhaustion control systems above, wherein the one or more processors are further configured to perform the regeneration via an exhaust gas flap scheme or a thermal management control scheme.

[0184] Aspects of the present disclosure include a vehicle having an exhaust control system, including a first selective catalytic reduction (SCR) system at a first position in an exhaust stream of the vehicle, a second SCR system at a second position in the exhaust stream, the second position being downstream of the first position, one or more memories storing instructions, and one or more processors configured to execute the instructions to receive a plurality of parameters associated with one or more of first sulfur deposits on the first SCR system, second sulfur deposits on a second catalyst of the second SCR system, or soot deposits on a diesel particulate filter, determine, based on the plurality of parameters, to remove a selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits, and remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits by performing one or more of changing temperatures of the first catalyst, the second catalyst, or the diesel particulate filter, or injecting diesel exhaust fluid (DEF) into the first SCR system or the second SCR system.

[0185] Aspects of the present disclosure include the vehicle above, wherein the plurality of parameters includes a first set of parameters associated with the first SCR system including a first nitrogen oxides (NOx) conversion percentage, a first urea dosing quantity, a first temperature, a second set of parameters associated with the second SCR system including a second NOx conversion percentage, a second urea dosing quantity, and a second temperature,- 51 - AFSDOCS:305402722.1and a third set of parameters including a fuel amount, a time since last regeneration, and an engine operation duration.

[0186] Aspects of the present disclosure include any of the vehicles above, wherein the one or more processors are further configured to determine to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits by obtaining a NOx conversion health model, obtaining a sulfur storage model, inputting the first set of parameters, the second set of parameters, and at least a portion of the third set of parameters into the NOx conversion health model and the sulfur storage model.

[0187] Aspects of the present disclosure include any of the vehicles above, wherein the one or more processors are further configured to determine to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits by comparing the time since last regeneration with a threshold time.

[0188] Aspects of the present disclosure include any of the vehicles above, wherein the one or more processors are further configured to determine to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits based on one or more of a first output of the NOx conversion health model, a second output of the sulfur storage model, or the time since last regeneration being longer than the threshold time.

[0189] Aspects of the present disclosure include any of the vehicles above, wherein the one or more processors are further configured to generate a request for regeneration in response to determining to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits, and perform the regeneration via an exhaust gas flap scheme or a thermal management control scheme.

[0190] Aspects of the present disclosure include a method of diesel exhaust fluid (DEF) dosing in a vehicle, including receiving a plurality of parameters associated with a first selective catalytic reduction (SCR) system or a second SCR system, wherein the first SCR system is disposed at a first position in an exhaust stream of the vehicle and the second SCR system is located at a second position in the exhaust stream that is downstream of the first position, determining, based on the plurality of parameters, whether to dose the first SCR system and the second SCR system, determining, in response to determining to dose the first SCR system and the second SCR system, a first nitrous nitrogen oxides (NOx) conversion capability of the first SCR system and a second NOx conversion capability of the second SCR system, determining,- 52 - AFSDOCS:305402722.1based on the first NOx conversion capability and the second NOx conversion capability, a first DEF dose for the first SCR system and a second DEF dose for the second SCR system, and injecting the first DEF dose of DEF into the first SCR system and the second DEF dose of DEF into the second SCR system.

[0191] Aspects of the present disclosure include the method above, wherein the plurality of parameters include a first temperature associated with the first SCR system, a second temperature associated with the second SCR system, and an exhaust flow rate of the exhaust stream.

[0192] Aspects of the present disclosure include any of the methods above, wherein determining whether to dose the first SCR system and the second SCR system includes determining to dose the first SCR system in response to the first temperature being above a first threshold temperature, and determining to dose the second SCR system in response to the second temperature being above a second threshold temperature.

[0193] Aspects of the present disclosure include any of the methods above, wherein determining the second nitrous oxide (N0x)N0x conversion capability of the second SCR system and the first NOx conversion capability of the first SCR system further includes determining the second NOx conversion capability by using a lookup table to identify the second NOx conversion capability based on one or more of the second temperature or the exhaust flow rate.

[0194] Aspects of the present disclosure include any of the methods above, wherein determining whether to dose the first SCR system and the second SCR system includes determining the first temperature being below a first threshold temperature or the second temperature being below a second threshold temperature, and suspending dosing the first SCR system and the second SCR system in response to the first temperature being below the first threshold temperature or the second temperature being below the second threshold temperature.

[0195] Aspects of the present disclosure include any of the methods above, further including, after suspending the dosing the first SCR system and the second SCR system, determining to dose the first SCR system and the second SCR system based on determining that the first temperature exceeds the first threshold temperature and the second temperature exceeds the second threshold temperature.

[0196] Aspects of the present disclosure include any of the methods above, further including estimating an untrimmed stoichiometric ratio of ammonia and NOx reaction based on the first - 53 - AFSDOCS:305402722.1temperature and the exhaust flow rate, and multiplying the untrimmed stoichiometric ratio by a percentage of NOx to be converted at the first SCR system to obtain a trimmed stoichiometric ratio, wherein determining the first DEF dose and the second DEF dose includes determining the first DEF dose and the second DEF dose based on the trimmed stoichiometric ratio.

[0197] Aspects of the present disclosure include an exhaust control system of a vehicle, including one or more memories storing instructions, and one or more processors configured to execute the instructions to receive a plurality of parameters associated with a first selective catalytic reduction (SCR) system or a second SCR system, wherein the first SCR system is disposed at a first position in an exhaust stream of the vehicle and the second SCR system is located at a second position in the exhaust stream that is downstream of the first position, determine, based on the plurality of parameters, whether to dose the first SCR system and the second SCR system, determine, in response to determining to dose the first SCR system and the second SCR system, a first nitrogen nitrous oxide (NOx) conversion capability of the first SCR system and a second NOx conversion capability of the second SCR system, determine, based on the first NOx conversion capability and the second NOx conversion capability, a first diesel exhaust fluid (DEF) dose for the first SCR system and a second DEF dose for the second SCR system, and cause an injection system to inject the first DEF dose of DEF into the first SCR system and the second DEF dose of DEF into the second SCR system.

[0198] Aspects of the present disclosure include the exhaust control system above, wherein the plurality of parameters include a first temperature associated with the first SCR system, a second temperature associated with the second SCR system, and an exhaust flow rate of the exhaust stream.

[0199] Aspects of the present disclosure include any of the exhaust control systems above, wherein, to determine whether to dose the first SCR system and the second SCR system, the one or more processors are further configured to determine to dose the first SCR system in response to the first temperature being above a first threshold temperature, and determine to dose the second SCR system in response to the second temperature being above a second threshold temperature.

[0200] Aspects of the present disclosure include any of the exhaust control systems above, wherein, to determine the second nitrous oxide (NOx) conversion capability of the second SCR system and the first NOx conversion capability of the first SCR system, the one or more - 54 - AFSDOCS:305402722.1processors are further configured to determine the second NOx conversion capability using a lookup table to identify the second NOx conversion capability based on one or more of the second temperature or the exhaust flow rate.

[0201] Aspects of the present disclosure include any of the exhaust control systems above, wherein, to determine whether to dose the first SCR system and the second SCR system, the one or more processors are further configured to determine the first temperature being below a first threshold temperature or the second temperature being below a second threshold temperature, and suspend dosing the first SCR system and the second SCR system in response to the first temperature being below the first threshold temperature or the second temperature being below the second threshold temperature.

[0202] Aspects of the present disclosure include any of the exhaust control systems above, wherein, after suspending the dosing the first SCR system and the second SCR system, the one or more processors are further configured to determine to dose the first SCR system and the second SCR system based on a determination that the first temperature exceeds the first threshold temperature and the second temperature exceeds the second threshold temperature.

[0203] Aspects of the present disclosure include any of the exhaust control systems above, wherein the one or more processors are further configured to estimate an untrimmed stoichiometric ratio of ammonia and NOx reaction based on the first temperature and the exhaust flow rate, and multiply the untrimmed stoichiometric ratio by a percentage of NOx to be converted at the first SCR system to obtain a trimmed stoichiometric ratio, wherein the one or more processors are further configured to determine the first DEF dose and the second DEF dose by determining the first DEF dose and the second DEF dose based on the trimmed stoichiometric ratio.

[0204] Aspects of the present disclosure include a vehicle having an exhaust control system, including a first selective catalytic reduction (SCR) system at a first position in an exhaust stream of the vehicle, a second SCR system at a second position in the exhaust stream, the second position being downstream of the first position, one or more memories storing instructions, one or more processors configured to execute the instructions to receive a plurality of parameters associated with the first SCR system or the second SCR system, determine, based on the plurality of parameters, whether to dose the first SCR system and the second SCR system, determine, in response to determining to dose the first SCR system and the second SCR system,- 55 - AFSDOCS:305402722.1a first nitrogen nitrous oxides (NOx) conversion capability of the first SCR system and a second NOx conversion capability of the second SCR system, and determine, based on the first NOx conversion capability and the second NOx conversion capability, a first diesel exhaust fluid (DEF) dose for the first SCR system and a second DEF dose for the second SCR system, and an injection system configured to inject the first DEF dose of DEF into the first SCR system and the second DEF dose of DEF into the second SCR system.

[0205] Aspects of the present disclosure include the vehicle above, wherein the plurality of parameters include a first temperature associated with the first SCR system, a second temperature associated with the second SCR system, and an exhaust flow rate of the exhaust stream.

[0206] Aspects of the present disclosure include any of the vehicles above, wherein, to determine whether to dose the first SCR system and the second SCR system, the one or more processors are further configured to determine to dose the first SCR system in response to the first temperature being above a first threshold temperature, and determine to dose the second SCR system in response to the second temperature being above a second threshold temperature.

[0207] Aspects of the present disclosure include any of the vehicles above, wherein, to determine the second nitrous oxide (NOx) conversion capability of the second SCR system and the first NOx conversion capability of the first SCR system, the one or more processors are further configured to determine the second NOx conversion capability using a lookup table to identify the second NOx conversion capability based on one or more of the second temperature or the exhaust flow rate.

[0208] Aspects of the present disclosure include any of the vehicles above, wherein, to determine whether to dose the first SCR system and the second SCR system, the one or more processors are further configured to determine the first temperature being below a first threshold temperature or the second temperature being below a second threshold temperature, and suspend dosing the first SCR system and the second SCR system in response to the first temperature being below the first threshold temperature or the second temperature being below the second threshold temperature.

[0209] Aspects of the present disclosure include any of the vehicles above, wherein the one or more processors are further configured to estimate an untrimmed stoichiometric ratio of ammonia and NOx reaction based on the first temperature and the exhaust flow rate, and - 56 - AFSDOCS:305402722.1multiply the untrimmed stoichiometric ratio by a percentage of NOx to be converted at the first SCR system to obtain a trimmed stoichiometric ratio, wherein the one or more processors are further configured to determine the first DEF dose and the second DEF dose by determining the first DEF dose and the second DEF dose based on the trimmed stoichiometric ratio.

[0210] Aspects of the present disclosure include a method of controlling emission of a vehicle, including receiving a plurality of parameters associated with a first selective catalytic reduction (SCR) system, wherein the first SCR system is disposed at a position in an exhaust stream of the vehicle that is upstream relative to a second SCR system, determining, based on the plurality of parameters, whether one or more of a nitrogen nitrous oxide (NOx) conversion condition, an estimated sulfur regeneration condition, or a time-based regeneration condition is met, and regenerating, in response to the one or more of the conditions being met, the first SCR system.

[0211] Aspects of the present disclosure include the method above, wherein the plurality of parameters includes one or more of an engine speed of the vehicle, a temperature of the first SCR system, an amount of NOx associated with the first SCR system, a diesel exhaust fluid (DEF) dose associated with the first SCR system, or a time period since a last regeneration.

[0212] Aspects of the present disclosure include any of the methods above, wherein determining whether the one or more of the NOx conversion condition, the estimated sulfur regeneration condition, or the time-based regeneration condition is met includes determining whether the NOx conversion condition is met by determining existence of at least one of the engine speed is above a threshold speed or within a threshold speed range, the temperature is above a threshold temperature or within a threshold temperature range, or the amount of NOx is above a threshold amount or within a threshold range, estimating an estimated NOx conversion amount based on the temperature and the DEF dose, calculating a normalized difference between the estimated NOx conversion amount and the amount of NOx, and determining the NOx conversion condition is met in response to the normalized difference being less than or equal to a threshold difference.

[0213] Aspects of the present disclosure include any of the methods above, wherein determining whether the one or more of the NOx conversion condition, the estimated sulfur regeneration condition, or the time-based regeneration condition is met includes determining whether the estimated sulfur regeneration condition is met by obtaining an accumulated sulfur value, determining whether the accumulated sulfur value is greater than or equal to a regeneration- 57 - AFSDOCS:305402722.1threshold, and determining that the estimated sulfur regeneration condition is met in response to the accumulated sulfur value being greater than or equal to the regeneration threshold.

[0214] Aspects of the present disclosure include any of the methods above, wherein determining whether the one or more of the NOx conversion condition, the estimated sulfur regeneration condition, or the time-based regeneration condition is met includes determining whether the time-based regeneration condition by determining whether the time period since the last regeneration is greater than or equal to a regeneration trigger threshold, and determining that the time-based regeneration condition is met in response to the time period since the last regeneration being greater than or equal to the regeneration trigger threshold.

[0215] Aspects of the present disclosure include any of the methods above, wherein regenerating the first SCR system includes determining whether an engine of the vehicle is in an idle state above an idle state threshold, and controlling an exhaust gas inlet flap to the first SCR system to achieve a target regeneration temperature in response to the idle state being above the idle state threshold, or controlling a thermal management control in response to the idle state not being above the idle state threshold.

[0216] Aspects of the present disclosure include any of the methods above, wherein receiving the plurality of parameters associated with the first SCR system is a first set of the plurality of parameters from a first time, and further including receiving a second set of the plurality of parameters from a second time subsequent to the first time associated with the first SCR system to continue monitoring the emission of the vehicle.

[0217] Aspects of the present disclosure include an exhaust control system of a vehicle, including one or more memories storing instructions, and one or more processors configured to execute the instructions to receive a plurality of parameters associated with a first selective catalytic reduction (SCR) system, wherein the first SCR system is disposed at a position in an exhaust stream of the vehicle that is upstream relative to a second SCR system, determine, based on the plurality of parameters, whether one or more of a nitrogen nitrous oxides (NOx) conversion condition, an estimated sulfur regeneration condition, or a time-based regeneration condition is met, and cause a regeneration system to regenerate, in response to the one or more of the conditions being met, the first SCR system.

[0218] Aspects of the present disclosure include the exhaust control system above, wherein the plurality of parameters includes one or more of an engine speed of the vehicle, a temperature of - 58 - AFSDOCS:305402722.1the first SCR system, an amount of NOx associated with the first SCR system, a diesel exhaust fluid (DEF) dose associated with the first SCR system, or a time period since a last regeneration.

[0219] Aspects of the present disclosure include any of the exhaust control systems above, wherein to determine whether the one or more of the NOx conversion condition, the estimated sulfur regeneration condition, or the time-based regeneration condition is met, the one or more processors are further configured to determine existence of at least one of the engine speed is above a threshold speed or within a threshold speed range, the temperature is above a threshold temperature or within a threshold temperature range, or the amount of NOx is above a threshold amount or within a threshold range, estimate an estimated NOx conversion amount based on the temperature and the DEF dose, calculate a normalized difference between the estimated NOx conversion amount and the amount of NOx, and determine the NOx conversion condition is met in response to the normalized difference being less than or equal to a threshold difference.

[0220] Aspects of the present disclosure include any of the exhaust control systems above, wherein to determine whether the one or more of the NOx conversion condition, the estimated sulfur regeneration condition, or the time-based regeneration condition is met, the one or more processors are further configured to obtain an accumulated sulfur value, determine whether the accumulated sulfur value is greater than or equal to a regeneration threshold, and determine that the estimated sulfur regeneration condition is met in response to the accumulated sulfur value being greater than or equal to the regeneration threshold.

[0221] Aspects of the present disclosure include any of the exhaust control systems above, wherein to determine whether the one or more of the NOx conversion condition, the estimated sulfur regeneration condition, or the time-based regeneration condition is met, the one or more processors are further configured to determine whether the time period since the last regeneration is greater than or equal to a regeneration trigger threshold, and determine that the time-based regeneration condition is met in response to the time period since the last regeneration being greater than or equal to the regeneration trigger threshold.

[0222] Aspects of the present disclosure include any of the exhaust control systems above, wherein to cause the regeneration system to regenerate the first SCR system, the one or more processors are further configured to determine whether an engine of the vehicle is in an idle state above an idle state threshold, and control an exhaust gas inlet flap to the first SCR system to achieve a target regeneration temperature in response to the idle state being above the idle state - 59 - AFSDOCS:305402722.1threshold, or control a thermal management control in response to the idle state not being above the idle state threshold.

[0223] Aspects of the present disclosure include any of the exhaust control systems above, wherein the plurality of parameters associated with the first SCR system is a first set of the plurality of parameters received at a first time, and the one or more processors are further configured to receive a second set of the plurality of parameters from a second time subsequent to the first time associated with the first SCR system to continue monitoring the emission of the vehicle.

[0224] Aspects of the present disclosure include a vehicle having an exhaust control system, including a first selective catalytic reduction (SCR) system that is disposed at a position in an exhaust stream of the vehicle that is upstream relative to a second SCR system, one or more memories storing instructions, one or more processors configured to execute the instructions to receive a plurality of parameters associated with the first SCR system, and determine, based on the plurality of parameters, whether one or more of a nitrogen nitrous oxide (NOx) conversion condition, an estimated sulfur regeneration condition, or a time-based regeneration condition is met, and a regeneration system configured to regenerate, in response to the one or more of the conditions being met, the first SCR system.

[0225] Aspects of the present disclosure include the vehicle above, wherein the plurality of parameters includes one or more of an engine speed of the vehicle, a temperature of the first SCR system, an amount of NOx associated with the first SCR system, a diesel exhaust fluid (DEF) dose associated with the first SCR system, or a time period since a last regeneration.

[0226] Aspects of the present disclosure include any of the vehicles above, wherein to determine whether the one or more of the NOx conversion condition, the estimated sulfur regeneration condition, or the time-based regeneration condition is met, the one or more processors are further configured to determine existence of at least one of the engine speed is above a threshold speed or within a threshold speed range, the temperature is above a threshold temperature or within a threshold temperature range, or the amount of NOx is above a threshold amount or within a threshold range, estimate an estimated NOx conversion amount based on the temperature and the DEF dose, calculate a normalized difference between the estimated NOx conversion amount and the amount of NOx, and determine the NOx conversion condition is met in response to the normalized difference being less than or equal to a threshold difference.- 60 - AFSDOCS:305402722.1

[0227] Aspects of the present disclosure include any of the vehicles above, wherein to determine whether the one or more of the NOx conversion condition, the estimated sulfur regeneration condition, or the time-based regeneration condition is met, the one or more processors are further configured to obtain an accumulated sulfur value, determine whether the accumulated sulfur value is greater than or equal to a regeneration threshold, and determine that the estimated sulfur regeneration condition is met in response to the accumulated sulfur value being greater than or equal to the regeneration threshold.

[0228] Aspects of the present disclosure include any of the vehicles above, wherein to determine whether the one or more of the NOx conversion condition, the estimated sulfur regeneration condition, or the time-based regeneration condition is met, the one or more processors are further configured to determine whether the time period since the last regeneration is greater than or equal to a regeneration trigger threshold, and determine that the time-based regeneration condition is met in response to the time period since the last regeneration being greater than or equal to the regeneration trigger threshold.

[0229] Aspects of the present disclosure include any of the vehicles above, wherein to cause the regeneration system to regenerate the first SCR system, the one or more processors are further configured to determine whether an engine of the vehicle is in an idle state above an idle state threshold, and control an exhaust gas inlet flap to the first SCR system to achieve a target regeneration temperature in response to the idle state being above the idle state threshold, or control a thermal management control in response to the idle state not being above the idle state threshold.

[0230] Although the operations of some of the disclosed aspects have been described in a particular, sequential order for convenient presentation, it should be understood that this manner of description encompasses rearrangement. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Moreover, for the sake of simplicity, the attached figures may not show the various ways in which the disclosed methods can be used in conjunction with other methods.

[0231] As used in this disclosure and in the claims, the singular forms “a,” “an,” and “the” include the plural forms unless the context clearly dictates otherwise. Additionally, the term “includes” means “comprises.” Further, the terms “coupled” and “associated” generally mean electrically, electromagnetically, and / or physically (e.g., mechanically or chemically) coupled or - 61 - AFSDOCS:305402722.1linked and does not exclude the presence of intermediate elements between the coupled or associated items absent specific contrary language.

[0232] Further, certain terms such as “forward,” “front,” “rear,” “back,” “up,” “down,” “upper,” “lower,” “horizontal,” “vertical,” “left,” “right,” “longitudinal,” “lateral,” and the like are used, where applicable, to provide some clarity of description when dealing with relative relationships. However, these terms are not intended to imply absolute relationships, positions, and / or orientations. For example, with respect to an object, an “upper” surface can become a “lower” surface by turning the object over. Nevertheless, it is still the same object.

[0233] Similar components in different implementations may be described herein and illustrated in the figures with similar reference numbers for improved understanding and readability. It should be understood that this numbering convention is merely for convenience, however, and is not intended to limit and / or exclude any claim scope.

[0234] Although there are alternatives for various components, parameters, operating conditions, etc., set forth herein, that does not mean that those alternatives are necessarily equivalent and / or perform equally well. Nor does it mean that the alternatives are listed in a preferred order unless stated otherwise.

[0235] In view of the many possible ways in which the principles of the disclosure may be applied, it should be recognized that the illustrated configurations depict examples of the disclosed technology and should not be taken as limiting the scope of the disclosure nor the claims. Rather, the scope of the claimed subject matter is defined by the following claims and their equivalents.- 62 - AFSDOCS:305402722.1

Claims

We claim:

1. A method of reducing undesirable emission from a vehicle, comprising: receiving a plurality of parameters associated with one or more of first sulfur deposits on a first catalyst of a first selective catalytic reduction (SCR) system, second sulfur deposits on a second catalyst of a second SCR system, or soot deposits on a diesel particulate filter, wherein the first SCR system is disposed at a first position in an exhaust stream of the vehicle and the second SCR system is located at a second position in the exhaust stream that is downstream of the first position;determining, based on the plurality of parameters, to remove a selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits; andremoving the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits by performing one or more of:changing temperatures of the first catalyst, the second catalyst, or the diesel particulate filter, orinjecting diesel exhaust fluid (DEF) into the first SCR system or the second SCR system.

2. The method of claim 1, wherein receiving the plurality of parameters comprises receiving:a first set of parameters associated with the first SCR system including a first nitrogen oxides (NOx) conversion percentage, a first urea dosing quantity, a first temperature;a second set of parameters associated with the second SCR system including a second NOx conversion percentage, a second urea dosing quantity, and a second temperature; and a third set of parameters including a fuel amount, a time since last regeneration, and an engine operation duration.

3. The method of claim 2, wherein determining to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits comprises determining to remove the first sulfur deposits or the second sulfur deposits by:obtaining a NOx conversion health model;- 63 - AFSDOCS:305402722.1obtaining a sulfur storage model;inputting the first set of parameters, the second set of parameters, and at least a portion of the third set of parameters into the NOx conversion health model and the sulfur storage model.

4. The method of claim 3, wherein determining to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits comprises determining to remove the first sulfur deposits or the second sulfur deposits by comparing the time since last regeneration with a threshold time.

5. The method of claim 4, wherein determining to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits comprises determining to remove the first sulfur deposits or the second sulfur deposits based on one or more of a first output of the NOx conversion health model, a second output of the sulfur storage model, or the time since last regeneration being longer than the threshold time.

6. The method of claim 1, further comprising, in response to determining to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits, generating a request for regeneration.

7. The method of claim 6, further comprising performing the regeneration via an exhaust gas flap scheme or a thermal management control scheme.

8. An exhaust control system of a vehicle, comprising:one or more memories storing instructions; andone or more processors configured to execute the instructions to:receive a plurality of parameters associated with one or more of first sulfur deposits on a first catalyst of a first selective catalytic reduction (SCR) system, second sulfur deposits on a second catalyst of the second SCR system, or soot deposits on a diesel particulate filter, wherein the first SCR system is disposed at a first position in an exhaust stream of the vehicle and the second SCR system is disposed at a second position in the exhaust stream that is downstream of the first position;- 64 - AFSDOCS:305402722.1determine, based on the plurality of parameters, to remove a selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits; and remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits by performing one or more of:changing temperatures of the first catalyst, the second catalyst, or the diesel particulate filter, orinjecting diesel exhaust fluid (DEF) into the first SCR system or the second SCR system.

9. The exhaust control system of claim 8, wherein the plurality of parameters comprise:a first set of parameters associated with the first SCR system including a first nitrogen oxides (NOx) conversion percentage, a first urea dosing quantity, a first temperature;a second set of parameters associated with the second SCR system including a second NOx conversion percentage, a second urea dosing quantity, and a second temperature; and a third set of parameters including a fuel amount, a time since last regeneration, and an engine operation duration.

10. The exhaust control system of claim 9, wherein the one or more processors are further configured to determine to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits by:obtaining a NOx conversion health model;obtaining a sulfur storage model;inputting the first set of parameters, the second set of parameters, and at least a portion of the third set of parameters into the NOx conversion health model and the sulfur storage model.

11. The exhaust control system of claim 10, wherein the one or more processors are further configured to determine to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits by comparing the time since last regeneration with a threshold time.- 65 - AFSDOCS:305402722.

112. The exhaust control system of claim 11, wherein the one or more processors are further configured to determine to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits based on one or more of a first output of the NOx conversion health model, a second output of the sulfur storage model, or the time since last regeneration being longer than the threshold time.

13. The exhaust control system of claim 8, wherein the one or more processors are further configured to generate a request for regeneration in response to determining to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits.

14. The exhaust control system of claim 13, wherein the one or more processors are further configured to perform the regeneration via an exhaust gas flap scheme or a thermal management control scheme.

15. A vehicle having an exhaust control system, comprising:a first selective catalytic reduction (SCR) system at a first position in an exhaust stream of the vehicle;a second SCR system at a second position in the exhaust stream, the second position being downstream of the first position;one or more memories storing instructions; andone or more processors configured to execute the instructions to:receive a plurality of parameters associated with one or more of first sulfur deposits on the first SCR system, second sulfur deposits on a second catalyst of the second SCR system, or soot deposits on a diesel particulate filter;determine, based on the plurality of parameters, to remove a selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits; and remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits by performing one or more of:changing temperatures of the first catalyst, the second catalyst, or the diesel particulate filter, or- 66 - AFSDOCS:305402722.1injecting diesel exhaust fluid (DEF) into the first SCR system or the second SCR system.

16. The vehicle of claim 15, wherein the plurality of parameters comprises:a first set of parameters associated with the first SCR system including a first nitrogen oxides (NOx) conversion percentage, a first urea dosing quantity, a first temperature;a second set of parameters associated with the second SCR system including a second NOx conversion percentage, a second urea dosing quantity, and a second temperature; and a third set of parameters including a fuel amount, a time since last regeneration, and an engine operation duration.

17. The vehicle of claim 16, wherein the one or more processors are further configured to determine to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits by:obtaining a NOx conversion health model;obtaining a sulfur storage model;inputting the first set of parameters, the second set of parameters, and at least a portion of the third set of parameters into the NOx conversion health model and the sulfur storage model.

18. The vehicle of claim 17, wherein the one or more processors are further configured to determine to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits by comparing the time since last regeneration with a threshold time.

19. The vehicle of claim 18, wherein the one or more processors are further configured to determine to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits based on one or more of a first output of the NOx conversion health model, a second output of the sulfur storage model, or the time since last regeneration being longer than the threshold time.- 67 - AFSDOCS:305402722.

120. The vehicle of claim 15, wherein the one or more processors are further configured to:generate a request for regeneration in response to determining to remove the selected one or more of the first sulfur deposits, the second sulfur deposits, or the soot deposits; and perform the regeneration via an exhaust gas flap scheme or a thermal management control scheme.

21. A method of diesel exhaust fluid (DEF) dosing in a vehicle, comprising: receiving a plurality of parameters associated with a first selective catalytic reduction (SCR) system or a second SCR system, wherein the first SCR system is disposed at a first position in an exhaust stream of the vehicle and the second SCR system is located at a second position in the exhaust stream that is downstream of the first position;determining, based on the plurality of parameters, whether to dose the first SCR system and the second SCR system;determining, in response to determining to dose the first SCR system and the second SCR system, a first nitrogen oxides (NOx) conversion capability of the first SCR system and a second NOx conversion capability of the second SCR system;determining, based on the first NOx conversion capability and the second NOx conversion capability, a first DEF dose for the first SCR system and a second DEF dose for the second SCR system; andinjecting the first DEF dose of DEF into the first SCR system and the second DEF dose of DEF into the second SCR system.

22. The method of claim 21, wherein the plurality of parameters include a first temperature associated with the first SCR system, a second temperature associated with the second SCR system, and an exhaust flow rate of the exhaust stream.

23. The method of claim 22, wherein determining whether to dose the first SCR system and the second SCR system comprises:determining to dose the first SCR system in response to the first temperature being above a first threshold temperature; and- 68 - AFSDOCS:305402722.1determining to dose the second SCR system in response to the second temperature being above a second threshold temperature.

24. The method of claim 22, wherein determining the second NOx conversion capability of the second SCR system and the first NOx conversion capability of the first SCR system further comprises determining the second NOx conversion capability by using a lookup table to identify the second NOx conversion capability based on one or more of the second temperature or the exhaust flow rate.

25. The method of claim 22, wherein determining whether to dose the first SCR system and the second SCR system comprises:determining the first temperature being below a first threshold temperature or the second temperature being below a second threshold temperature; andsuspending dosing the first SCR system and the second SCR system in response to the first temperature being below the first threshold temperature or the second temperature being below the second threshold temperature.

26. The method of claim 25, further comprising, after suspending the dosing the first SCR system and the second SCR system, determining to dose the first SCR system and the second SCR system based on determining that the first temperature exceeds the first threshold temperature and the second temperature exceeds the second threshold temperature.

27. The method of claim 22, further comprising:estimating an untrimmed stoichiometric ratio of ammonia and NOx reaction based on the first temperature and the exhaust flow rate; andmultiplying the untrimmed stoichiometric ratio by a percentage of NOx to be converted at the first SCR system to obtain a trimmed stoichiometric ratio;wherein determining the first DEF dose and the second DEF dose comprises determining the first DEF dose and the second DEF dose based on the trimmed stoichiometric ratio.

28. An exhaust control system of a vehicle, comprising:- 69 - AFSDOCS:305402722.1one or more memories storing instructions; andone or more processors configured to execute the instructions to:receive a plurality of parameters associated with a first selective catalytic reduction (SCR) system or a second SCR system, wherein the first SCR system is disposed at a first position in an exhaust stream of the vehicle and the second SCR system is located at a second position in the exhaust stream that is downstream of the first position;determine, based on the plurality of parameters, whether to dose the first SCR system and the second SCR system;determine, in response to determining to dose the first SCR system and the second SCR system, a first nitrogen oxide (NOx) conversion capability of the first SCR system and a second NOx conversion capability of the second SCR system;determine, based on the first NOx conversion capability and the second NOx conversion capability, a first diesel exhaust fluid (DEF) dose for the first SCR system and a second DEF dose for the second SCR system; andcause an injection system to inject the first DEF dose of DEF into the first SCR system and the second DEF dose of DEF into the second SCR system.

29. The exhaust control system of claim 28, wherein the plurality of parameters include a first temperature associated with the first SCR system, a second temperature associated with the second SCR system, and an exhaust flow rate of the exhaust stream.

30. The exhaust control system of claim 29, wherein, to determine whether to dose the first SCR system and the second SCR system, the one or more processors are further configured to:determine to dose the first SCR system in response to the first temperature being above a first threshold temperature; anddetermine to dose the second SCR system in response to the second temperature being above a second threshold temperature.- 70 - AFSDOCS:305402722.

131. The exhaust control system of claim 29, wherein, to determine the second NOx conversion capability of the second SCR system and the first NOx conversion capability of the first SCR system, the one or more processors are further configured to determine the second NOx conversion capability using a lookup table to identify the second NOx conversion capability based on one or more of the second temperature or the exhaust flow rate.

32. The exhaust control system of claim 29, wherein, to determine whether to dose the first SCR system and the second SCR system, the one or more processors are further configured to:determine the first temperature being below a first threshold temperature or the second temperature being below a second threshold temperature; andsuspend dosing the first SCR system and the second SCR system in response to the first temperature being below the first threshold temperature or the second temperature being below the second threshold temperature.

33. The exhaust control system of claim 32, wherein, after suspending the dosing the first SCR system and the second SCR system, the one or more processors are further configured to determine to dose the first SCR system and the second SCR system based on a determination that the first temperature exceeds the first threshold temperature and the second temperature exceeds the second threshold temperature.

34. The exhaust control system of claim 29, wherein the one or more processors are further configured to:estimate an untrimmed stoichiometric ratio of ammonia and NOx reaction based on the first temperature and the exhaust flow rate; andmultiply the untrimmed stoichiometric ratio by a percentage of NOx to be converted at the first SCR system to obtain a trimmed stoichiometric ratio;wherein the one or more processors are further configured to determine the first DEF dose and the second DEF dose by determining the first DEF dose and the second DEF dose based on the trimmed stoichiometric ratio.- 71 - AFSDOCS:305402722.

135. A vehicle having an exhaust control system, comprising:a first selective catalytic reduction (SCR) system at a first position in an exhaust stream of the vehicle;a second SCR system at a second position in the exhaust stream, the second position being downstream of the first position;one or more memories storing instructions;one or more processors configured to execute the instructions to:receive a plurality of parameters associated with the first SCR system or the second SCR system;determine, based on the plurality of parameters, whether to dose the first SCR system and the second SCR system;determine, in response to determining to dose the first SCR system and the second SCR system, a first nitrogen oxides (NOx) conversion capability of the first SCR system and a second NOx conversion capability of the second SCR system; anddetermine, based on the first NOx conversion capability and the second NOx conversion capability, a first diesel exhaust fluid (DEF) dose for the first SCR system and a second DEF dose for the second SCR system; andan injection system configured to inject the first DEF dose of DEF into the first SCR system and the second DEF dose of DEF into the second SCR system.

36. The vehicle of claim 35, wherein the plurality of parameters include a first temperature associated with the first SCR system, a second temperature associated with the second SCR system, and an exhaust flow rate of the exhaust stream.

37. The vehicle of claim 36, wherein, to determine whether to dose the first SCR system and the second SCR system, the one or more processors are further configured to:determine to dose the first SCR system in response to the first temperature being above a first threshold temperature; anddetermine to dose the second SCR system in response to the second temperature being above a second threshold temperature.- 72 - AFSDOCS:305402722.

138. The vehicle of claim 36, wherein, to determine the second NOx conversion capability of the second SCR system and the first NOx conversion capability of the first SCR system, the one or more processors are further configured to determine the second NOx conversion capability using a lookup table to identify the second NOx conversion capability based on one or more of the second temperature or the exhaust flow rate.

39. The vehicle of claim 36, wherein, to determine whether to dose the first SCR system and the second SCR system, the one or more processors are further configured to:determine the first temperature being below a first threshold temperature or the second temperature being below a second threshold temperature; andsuspend dosing the first SCR system and the second SCR system in response to the first temperature being below the first threshold temperature or the second temperature being below the second threshold temperature.

40. The vehicle of claim 36, wherein the one or more processors are further configured to:estimate an untrimmed stoichiometric ratio of ammonia and NOx reaction based on the first temperature and the exhaust flow rate; andmultiply the untrimmed stoichiometric ratio by a percentage of NOx to be converted at the first SCR system to obtain a trimmed stoichiometric ratio;wherein the one or more processors are further configured to determine the first DEF dose and the second DEF dose by determining the first DEF dose and the second DEF dose based on the trimmed stoichiometric ratio.

41. A method of controlling emission of a vehicle, comprising:receiving a plurality of parameters associated with a first selective catalytic reduction (SCR) system, wherein the first SCR system is disposed at a position in an exhaust stream of the vehicle that is upstream relative to a second SCR system;determining, based on the plurality of parameters, whether one or more of a nitrogen oxide (NOx) conversion condition, an estimated sulfur regeneration condition, or a time-based regeneration condition is met; and- 73 - AFSDOCS:305402722.1regenerating, in response to the one or more of the conditions being met, the first SCR system.

42. The method of claim 41, wherein the plurality of parameters includes one or more of an engine speed of the vehicle, a temperature of the first SCR system, an amount of NOx associated with the first SCR system, a diesel exhaust fluid (DEF) dose associated with the first SCR system, or a time period since a last regeneration.

43. The method of claim 42, wherein determining whether the one or more of the NOx conversion condition, the estimated sulfur regeneration condition, or the time-based regeneration condition is met comprises determining whether the NOx conversion condition is met by:determining existence of at least one of the engine speed is above a threshold speed or within a threshold speed range, the temperature is above a threshold temperature or within a threshold temperature range, or the amount of NOx is above a threshold amount or within a threshold range;estimating an estimated NOx conversion amount based on the temperature and the DEF dose;calculating a normalized difference between the estimated NOx conversion amount and the amount of NOx; anddetermining the NOx conversion condition is met in response to the normalized difference being less than or equal to a threshold difference.

44. The method of claim 42, wherein determining whether the one or more of the NOx conversion condition, the estimated sulfur regeneration condition, or the time-based regeneration condition is met comprises determining whether the estimated sulfur regeneration condition is met by:obtaining an accumulated sulfur value;determining whether the accumulated sulfur value is greater than or equal to a regeneration threshold; and- 74 - AFSDOCS:305402722.1determining that the estimated sulfur regeneration condition is met in response to the accumulated sulfur value being greater than or equal to the regeneration threshold.

45. The method of claim 42, wherein determining whether the one or more of the NOx conversion condition, the estimated sulfur regeneration condition, or the time-based regeneration condition is met comprises determining whether the time-based regeneration condition by:determining whether the time period since the last regeneration is greater than or equal to a regeneration trigger threshold; anddetermining that the time-based regeneration condition is met in response to the time period since the last regeneration being greater than or equal to the regeneration trigger threshold.

46. The method of claim 41, wherein regenerating the first SCR system comprises: determining whether an engine of the vehicle is in an idle state above an idle state threshold; andcontrolling an exhaust gas flap to the first SCR system to achieve a target regeneration temperature in response to the idle state being above the idle state threshold, orcontrolling a thermal management control in response to the idle state not being above the idle state threshold.

47. The method of claim 41, wherein receiving the plurality of parameters associated with the first SCR system is a first set of the plurality of parameters from a first time, and further comprising receiving a second set of the plurality of parameters from a second time subsequent to the first time associated with the first SCR system to continue monitoring the emission of the vehicle.

48. An exhaust control system of a vehicle, comprising:one or more memories storing instructions; andone or more processors configured to execute the instructions to:- 75 - AFSDOCS:305402722.1receive a plurality of parameters associated with a first selective catalytic reduction (SCR) system, wherein the first SCR system is disposed at a position in an exhaust stream of the vehicle that is upstream relative to a second SCR system;determine, based on the plurality of parameters, whether one or more of a nitrogen oxides (NOx) conversion condition, an estimated sulfur regeneration condition, or a time-based regeneration condition is met; andcause a regeneration system to regenerate, in response to the one or more of the conditions being met, the first SCR system.

49. The exhaust control system of claim 48, wherein the plurality of parameters includes one or more of an engine speed of the vehicle, a temperature of the first SCR system, an amount of NOx associated with the first SCR system, a diesel exhaust fluid (DEF) dose associated with the first SCR system, or a time period since a last regeneration.

50. The exhaust control system of claim 49, wherein to determine whether the one or more of the NOx conversion condition, the estimated sulfur regeneration condition, or the timebased regeneration condition is met, the one or more processors are further configured to:determine existence of at least one of the engine speed is above a threshold speed or within a threshold speed range, the temperature is above a threshold temperature or within a threshold temperature range, or the amount of NOx is above a threshold amount or within a threshold range;estimate an estimated NOx conversion amount based on the temperature and the DEF dose;calculate a normalized difference between the estimated NOx conversion amount and the amount of NOx; anddetermine the NOx conversion condition is met in response to the normalized difference being less than or equal to a threshold difference.

51. The exhaust control system of claim 49, wherein to determine whether the one or more of the NOx conversion condition, the estimated sulfur regeneration condition, or the timebased regeneration condition is met, the one or more processors are further configured to:- 76 - AFSDOCS:305402722.1obtain an accumulated sulfur value;determine whether the accumulated sulfur value is greater than or equal to a regeneration threshold; anddetermine that the estimated sulfur regeneration condition is met in response to the accumulated sulfur value being greater than or equal to the regeneration threshold.

52. The exhaust control system of claim 49, wherein to determine whether the one or more of the NOx conversion condition, the estimated sulfur regeneration condition, or the timebased regeneration condition is met, the one or more processors are further configured to:determine whether the time period since the last regeneration is greater than or equal to a regeneration trigger threshold; anddetermine that the time-based regeneration condition is met in response to the time period since the last regeneration being greater than or equal to the regeneration trigger threshold.

53. The exhaust control system of claim 48, wherein to cause the regeneration system to regenerate the first SCR system, the one or more processors are further configured to:determine whether an engine of the vehicle is in an idle state above an idle state threshold; andcontrol an exhaust gas flap to the first SCR system to achieve a target regeneration temperature in response to the idle state being above the idle state threshold, orcontrol a thermal management control in response to the idle state not being above the idle state threshold.

54. The exhaust control system of claim 48, wherein:the plurality of parameters associated with the first SCR system is a first set of the plurality of parameters received at a first time, andthe one or more processors are further configured to receive a second set of the plurality of parameters from a second time subsequent to the first time associated with the first SCR system to continue monitoring the emission of the vehicle.

55. A vehicle having an exhaust control system, comprising:- 77 - AFSDOCS:305402722.1a first selective catalytic reduction (SCR) system that is disposed at a position in an exhaust stream of the vehicle that is upstream relative to a second SCR system;one or more memories storing instructions;one or more processors configured to execute the instructions to:receive a plurality of parameters associated with the first SCR system; and determine, based on the plurality of parameters, whether one or more of a nitrogen oxide (NOx) conversion condition, an estimated sulfur regeneration condition, or a time-based regeneration condition is met; anda regeneration system configured to regenerate, in response to the one or more of the conditions being met, the first SCR system.

56. The vehicle of claim 55, wherein the plurality of parameters includes one or more of an engine speed of the vehicle, a temperature of the first SCR system, an amount of NOx associated with the first SCR system, a diesel exhaust fluid (DEF) dose associated with the first SCR system, or a time period since a last regeneration.

57. The vehicle of claim 56, wherein to determine whether the one or more of the NOx conversion condition, the estimated sulfur regeneration condition, or the time-based regeneration condition is met, the one or more processors are further configured to:determine existence of at least one of the engine speed is above a threshold speed or within a threshold speed range, the temperature is above a threshold temperature or within a threshold temperature range, or the amount of NOx is above a threshold amount or within a threshold range;estimate an estimated NOx conversion amount based on the temperature and the DEF dose;calculate a normalized difference between the estimated NOx conversion amount and the amount of NOx; anddetermine the NOx conversion condition is met in response to the normalized difference being less than or equal to a threshold difference.- 78 - AFSDOCS:305402722.

158. The vehicle of claim 56, wherein to determine whether the one or more of the NOx conversion condition, the estimated sulfur regeneration condition, or the time-based regeneration condition is met, the one or more processors are further configured to:obtain an accumulated sulfur value;determine whether the accumulated sulfur value is greater than or equal to a regeneration threshold; anddetermine that the estimated sulfur regeneration condition is met in response to the accumulated sulfur value being greater than or equal to the regeneration threshold.

59. The vehicle of claim 56, wherein to determine whether the one or more of the NOx conversion condition, the estimated sulfur regeneration condition, or the time-based regeneration condition is met, the one or more processors are further configured to:determine whether the time period since the last regeneration is greater than or equal to a regeneration trigger threshold; anddetermine that the time-based regeneration condition is met in response to the time period since the last regeneration being greater than or equal to the regeneration trigger threshold.

60. The vehicle of claim 55, wherein to cause the regeneration system to regenerate the first SCR system, the one or more processors are further configured to:determine whether an engine of the vehicle is in an idle state above an idle state threshold; andcontrol an exhaust gas flap to the first SCR system to achieve a target regeneration temperature in response to the idle state being above the idle state threshold, orcontrol a thermal management control in response to the idle state not being above the idle state threshold.- 79 - AFSDOCS:305402722.1

Images