NO2 Emission Control via Hydrocarbon Competition in Exhaust Catalysts
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Solution Overview
Problem
Internal combustion engines with catalysts for NO2 oxidation face a challenge in reducing NO2 emissions, as high NO2 concentrations at low temperatures are necessary for effective exhaust aftertreatment but lead to excessive NO2 generation at higher temperatures, causing environmental issues and conflicting with the need for long catalyst lifespan and efficient performance.
Innovation Solution
A method that adjusts the proportion of substances competing with NO oxidation in the exhaust gas, using platinum or platinum oxide catalysts, to ensure only the required NO2 fraction is present downstream of the catalytic converter, achieved by varying hydrocarbon concentrations through engine parameters and electronic control units, ensuring optimal NO2 levels for aftertreatment without increasing emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the catalyst is designed to produce high NO2 proportions at low temperatures for effective exhaust aftertreatment, then the aftertreatment system performance is improved, but excessive NO2 is generated at higher temperatures leading to unwanted emissions
Solution Approach 1:
The patent introduces a dynamic control system that adjusts the air-to-fuel ratio in real-time based on engine operating conditions and catalyst state. The electronic control unit modifies engine parameters such as injection timing, EGR rate, and throttle position to dynamically control NO2 generation, allowing the system to adapt between different temperature regimes and catalyst aging states
Solution Approach 2:
The invention changes the operating parameters of the engine-exhaust system by adjusting the air-to-fuel ratio and other combustion parameters to control the amount of NO2 generated. By varying these parameters based on temperature and catalyst state, the system optimizes NO2 production for aftertreatment while preventing excessive emissions
2Reliability
If the catalytic converter is designed to be large to maintain effectiveness after service life expiration, then long-term reliability is improved, but significantly more NO2 is generated than necessary when the catalyst is fresh
Solution Approach 1:
The patent implements a feedback control system using NO2 sensors to monitor exhaust gas composition and provide real-time information to the electronic control unit. This feedback loop allows the system to adjust engine parameters dynamically, compensating for catalyst aging and ensuring optimal NO2 generation levels throughout the catalyst's service life
Solution Approach 2:
The system transitions from a static catalyst design to a dynamic control approach where engine parameters are continuously adjusted based on catalyst state and operating conditions, allowing the same catalyst size to perform optimally throughout its entire service life
3Object-generated harmful factors
If the engine operates with hydrocarbons to compete with NO oxidation and reduce NO2 generation, then NO2 emissions are reduced, but the combustion efficiency may be affected
Solution Approach 1:
The invention makes precise adjustments to combustion parameters including injection timing, injection pressure, EGR rate, and throttle position to control hydrocarbon release. These parameter changes are optimized to provide just enough hydrocarbons to compete with NO oxidation without significantly impacting combustion efficiency or creating other emissions problems
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 effectively minimizes unwanted NO2 emissions across varying engine operating conditions and catalyst states, maintaining exhaust gas aftertreatment efficiency while reducing toxic NO2 output, particularly at higher temperatures, and extending catalyst lifespan.
Implementation Method 1
catalysts with NO oxidation activity, the catalyst with NO oxidation activity serving to reduce the proportion of NO2 in the exhaust gas
Implementation Method 2
2 NO + O2 ↔ 2NO2 Equation 1
Implementation Method 3
The proportion of substances that compete with the NO oxidation is varied... hydrocarbons, in particular the fuel used to operate the internal combustion engine
Data Source
Figure 1
AI summary
The invention relates to a method for reducing undesirable NO2 emissions from internal combustion engines operating with excess air and equipped in their exhaust system with at least one catalyst with NO oxidation activity, wherein the catalyst with NO oxidation activity serves to increase the proportion of NO2 in the exhaust gas of the internal combustion engine for downstream exhaust aftertreatment processes. The reduction of NO2 emissions is achieved by varying the proportion of substances that compete with NO oxidation during the operation of the internal combustion engine, adapted to the respective operating point of the internal combustion engine and the state of the catalyst with NO oxidation activity, such that downstream of the catalyst with NO oxidation activity only the target NO2 proportion required for the subsequent exhaust aftertreatment is present in the exhaust gas.