SCR Model Correction for Catalyst Aging
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Solution Overview
Problem
Existing nitrogen oxide reduction systems in vehicles face inefficiencies due to aging catalysts and errors in mathematical models for ammonia injection, leading to inconsistent emissions control.
Innovation Solution
A method for correcting the mathematical model used to determine the quantity of reducing agent for selective catalytic reduction, involving real-time gas analysis and adaptive correction factors based on engine operating conditions, to ensure optimal nitrogen oxide conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a mathematical model is used to determine the quantity of reducing agent to be injected, then the nitrogen oxide reduction system can operate automatically, but the model accuracy deteriorates over time due to catalyst aging
Solution Approach 1:
The patent implements a feedback mechanism where the nitrogen oxide sensor continuously monitors the actual reduction efficiency and compares it with the model's predicted values. When deviations are detected, the system automatically adjusts the reducing agent injection quantity to compensate for catalyst aging, thereby maintaining both automation and accuracy over time.
Solution Approach 2:
The system dynamically adjusts operating parameters (injection quantity, injection timing) based on detected deviations from expected performance. By changing these parameters in response to catalyst aging, the system maintains effective nitrogen oxide reduction without requiring manual recalibration of the mathematical model.
2Productivity
If the reducing agent injection quantity is increased to compensate for model errors, then nitrogen oxide conversion efficiency improves, but ammonia emissions increase
Solution Approach 1:
The nitrogen oxide sensor provides real-time feedback on reduction efficiency, allowing the system to make precise adjustments to the reducing agent injection quantity. This feedback control enables the system to achieve optimal conversion efficiency while avoiding excessive injection that would lead to ammonia slip, thus resolving the contradiction between productivity and harmful emissions.
Solution Approach 2:
Rather than consistently over-injecting to ensure adequate reduction, the system uses partial adjustments based on actual measured performance. The injection quantity is optimized to be just sufficient for effective reduction, avoiding the excessive action that would cause ammonia emissions while still achieving high conversion efficiency.
3Measurement precision
If nitrogen oxide sensors are added to monitor and correct injection accuracy, then emission control precision improves, but system complexity and cost increase
Solution Approach 1:
The system uses the existing nitrogen oxide sensor primarily for its intended purpose of monitoring emission levels, and leverages this same measurement to also detect model inaccuracies and trigger corrections. This self-service approach allows the system to achieve precise emission control without adding dedicated sensors solely for model verification, thereby improving precision without proportionally increasing complexity.
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
This method maintains efficient nitrogen oxide conversion while minimizing ammonia emissions and reducing the need for additional sensors, thereby optimizing SCR system performance and compliance with emission regulations.
Implementation Method 1
a selective catalytic reduction of the nitrogen oxides nitrogen using a reducing agent such as ammonia
Data Source
Figure 1a~2
Figure 3~4
AI summary
The invention relates to a method for correcting a model for determining the amount of reducing agent to inject for the selective catalytic reduction of nitrogen oxides contained in exhaust gases, which includes the following steps: determining an amount of reducing agent to inject based on the amount of nitrogen oxides emitted and an initial mathematical model; determining, by taking a measurement from the catalyst of the amount and/or nature of the gas, whether or not the reducing reaction is carried out under correct conditions; if an anomaly is detected, adjusting the amount of reducing agent to inject; and if the use of said method leads to a number of repeated adjustments of the same nature greater than a predetermined value N: the mathematical model is corrected, and the initial mathematical model is replaced by the corrected model.