SCR Catalyst NO and NO2 Measurement for Adaptive Reductant Dosing
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Solution Overview
Problem
Existing exhaust aftertreatment systems struggle to accurately distinguish between nitric oxide (NO) and nitrogen dioxide (NO2) concentrations in exhaust gas, leading to inefficient management of reductant dosing, which can result in either increased NOx emissions or unreacted reductant slip.
Innovation Solution
A system and method for determining NO and NO2 concentrations using a dynamic model of the SCR catalyst, combined with sensor data, to precisely control reductant dosing through an exhaust analysis circuit and reductant delivery circuit, optimizing reductant injection based on actual NO and NO2 levels and stored reductant amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If reductant dosing is increased to ensure complete NOx conversion, then NOx emissions are reduced, but unreacted reductant slip increases
Solution Approach 1:
The system implements feedback control by continuously monitoring outlet NOx concentration and using it to adjust reductant dosing rates. The controller dynamically modifies dosing based on measured NOx levels, ensuring optimal reductant utilization while preventing both excessive emissions and reductant slip.
Solution Approach 2:
The system changes the dosing parameter (reductant injection rate) based on operating conditions and measured NOx concentrations. By dynamically adjusting this parameter rather than using fixed dosing rates, the system optimizes the balance between NOx conversion efficiency and reductant slip prevention.
2Loss of energy
If reductant dosing is decreased to reduce reductant slip, then reductant utilization efficiency improves, but NOx conversion completeness deteriorates
Solution Approach 1:
The feedback control system monitors outlet NOx concentrations and adjusts reductant dosing accordingly. When NOx levels indicate incomplete conversion, the system increases dosing to maintain conversion efficiency while minimizing excess reductant injection, thereby optimizing reductant utilization.
Solution Approach 2:
The system transitions from static fixed dosing rates to dynamic dosing adjustment based on real-time measurements and operating conditions. This dynamic approach allows the system to adapt reductant injection rates to actual conversion needs, improving utilization efficiency while maintaining emission compliance.
3Device complexity
If fixed reductant dosing rates are used to simplify control, then system complexity is reduced, but emission compliance and reductant efficiency deteriorate
Solution Approach 1:
The system employs feedback control where outlet NOx measurements are continuously fed back to the controller, which automatically adjusts dosing rates. This feedback mechanism enables compliant emission control without requiring complex manual intervention or overly sophisticated control algorithms.
Solution Approach 2:
The control system performs self-adjustment based on measured NOx levels and stored catalyst state information. The controller autonomously determines optimal dosing rates without external intervention, simplifying operation while maintaining emission compliance through continuous adaptive control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances the efficiency of reductant utilization, reducing NOx emissions and minimizing reductant slip by ensuring accurate dosing based on individual NO and NO2 concentrations, thereby complying with stringent emission standards.
Implementation Method 1
Exhaust aftertreatment systems treat engine exhaust gas with catalysts and reductant to convert NOx in the exhaust gas into less harmful compounds
Implementation Method 2
selective catalytic reduction (SCR) catalyst in exhaust gas-receiving communication with an engine and at least one reductant dosing system structured to provide reductant to the exhaust gas
Data Source
AI summary
A system includes a controller for an exhaust aftertreatment system including a catalyst. The controller is structured to: receive information indicative of a first characteristic of the exhaust gas at a first time; receive information indicative of a second characteristic of the exhaust gas at a second time after the first time; determine one or more of a concentration of one or more of nitric oxide (NO), nitrogen dioxide (NO2), or a ratio of NO to NO2 at or proximate an inlet of the catalyst; and command at least one reductant dosing system to increase, decrease, or maintain an amount of reductant provided to the exhaust gas based on each of the first characteristic, the second characteristic, and the determination.