NO2-Based Diesel Particulate Filter Regeneration Strategy
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Solution Overview
Problem
Oxygen-based aftertreatment regeneration of diesel particulate filters (DPFs) and selective catalytic reduction (SCR) systems in diesel exhaust systems operates at high temperatures, leading to premature aging and thermal degradation of components.
Innovation Solution
Implementing a control strategy that uses nitrogen dioxide (NO2) based regeneration for DPFs, with selective adjustments to exhaust gas recirculation (EGR), injection timing, and platinum catalysts to maintain target temperatures between 300°C and 500°C, and switching to oxygen-based regeneration or SCR desulfation when necessary to manage soot accumulation and sulfur oxide levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oxygen-based aftertreatment regeneration is used to remove soot from DPF, then soot removal efficiency is improved, but thermal degradation of DPF and SCR components occurs due to high operating temperatures
Solution Approach 1:
The patent changes the chemical parameter from oxygen-based oxidation to nitrogen dioxide-based oxidation for the regeneration process. This allows the regeneration to proceed at lower temperatures (avoiding thermal degradation) while maintaining effective soot removal through the alternative chemical mechanism of NO2 oxidation
Solution Approach 2:
The patent introduces nitrogen dioxide (NO2) as an intermediary substance to enable the regeneration process. By using NO2 as the oxidizing agent instead of direct oxygen combustion, the system achieves soot removal without requiring high temperatures that would cause thermal degradation of components
2Reliability
If nitrogen dioxide (NO2) based regeneration is used to reduce thermal degradation, then component lifespan is improved, but soot removal effectiveness decreases compared to oxygen-based regeneration
Solution Approach 1:
The patent modifies the chemical composition parameters of the exhaust gas by controlling NOx conversion to NO2 in the DOC, creating optimal conditions for NO2-based oxidation that maintains soot removal effectiveness while operating at lower temperatures
Solution Approach 2:
The patent implements a periodic control strategy where the system alternates between NO2-based regeneration (for low-temperature operation) and occasionally uses oxygen-based regeneration or SCR desulfation when needed, optimizing both soot removal effectiveness and component protection over time
3Quantity of substance
If DEF injector and SCR are deactivated to allow NO2 passage, then NO2 availability for regeneration is improved, but NOx emission control capability is reduced
Solution Approach 1:
The patent uses periodic control where the DEF injector and SCR are selectively deactivated only during the regeneration phase when NO2 availability is needed, while being active during normal operation for NOx control, thus balancing both requirements through time-based control
Solution Approach 2:
The patent implements dynamic control of the DEF injector and SCR system, adjusting their operation state based on real-time conditions (regeneration needs vs. NOx control needs), allowing the system to adapt between different functional priorities
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 approach minimizes thermal degradation of DPF and SCR components, effectively regenerating the DPF at lower temperatures and ensuring efficient soot removal while maintaining system integrity.
Implementation Method 1
converting, with the DOC, NO within the exhaust gas entering the DOC to NO2
Implementation Method 2
converting solid carbon-based particulate matter that has accumulated within the DPF to gaseous carbon dioxide (CO2) and NO by using NO2 as an oxidant
Data Source
AI summary
A method of aftertreatment regeneration includes routing exhaust gases from a diesel engine through an exhaust system and initiating a nitrogen dioxide based aftertreatment regeneration of a diesel particulate filter (DPF) by at least partially de-activating a first DEF injector and an upstream selective catalyst reducer (SCR), increasing levels of Nitric Oxide within exhaust gas from the engine, establishing and maintaining an target exhaust gas temperature at an inlet of the DPF by actively controlling combustion characteristics of the engine, converting, with a diesel oxidation catalyst, (DOC) NO within the exhaust gas entering the DOC to NO2, and converting solid carbon-based particulate matter that has accumulated within the DPF to gaseous carbon dioxide (CO2) and NO by using NO2 as an oxidant.