Adaptive SCR Reducing Agent Supply for Temperature-Dependent Storage
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Solution Overview
Problem
Existing methods for reducing nitrogen oxide levels in internal combustion engine exhaust gases, such as selective catalytic reduction (SCR), often result in the unintended discharge of reducing agents like ammonia into the atmosphere due to unaccounted storage capacity and temperature fluctuations in catalytic converters.
Innovation Solution
A method and device that adaptively supply reducing agents based on the temperature-dependent storage capacity of the catalytic converter, calculating future temperature profiles and adjusting the quantity of reducing agent to prevent desorption and ensure complete nitrogen oxide conversion, potentially using an oxidation catalytic converter downstream to handle temperature jumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the storage capacity of the reduction catalytic converter is not taken into consideration in the regulation of reducing agent supply, then the system operation is simple, but non-converted nitrogen oxides or reducing agent are discharged to the atmosphere
Solution Approach 1:
The patent implements feedback control by continuously monitoring the storage capacity state of the reduction catalytic converter and adjusting the reducing agent supply rate accordingly. The control device receives information about the current storage capacity and modifies the reducing agent injection to prevent both overfilling and discharge, creating a closed-loop control system that resolves the contradiction between operational simplicity and emission prevention.
Solution Approach 2:
The reduction catalytic converter effectively monitors its own storage capacity state and provides this information to the control device, enabling the system to self-regulate the reducing agent supply without complex external monitoring. The converter's inherent properties (temperature, storage capacity) are used to automatically adjust the reducing agent injection rate, allowing the system to prevent reducing agent discharge while maintaining simple operation.
2Object-generated harmful factors
If the storage capacity of the reduction catalytic converter is taken into consideration in the regulation of reducing agent supply, then the discharge of reducing agent is prevented, but the device complexity increases
Solution Approach 1:
The control device performs multiple functions: it monitors storage capacity, calculates appropriate reducing agent supply rates, and adjusts injection accordingly. By making the control device multi-functional rather than adding separate dedicated components for each function, the patent prevents reducing agent discharge while minimizing the increase in overall device complexity. The existing control infrastructure is leveraged to handle storage capacity regulation.
Solution Approach 2:
The patent introduces an intermediary control device that mediates between the reducing agent supply system and the reduction catalytic converter. This intermediary processes storage capacity information and translates it into appropriate reducing agent injection rates, preventing direct complex interactions between the supply system and converter while achieving precise control to prevent reducing agent discharge.
3Ease of operation
If a fixed quantity of reducing agent is supplied continuously, then the supply regulation is simple, but non-converted reducing agent is discharged during temperature increases
Solution Approach 1:
The patent transitions from static fixed-quantity reducing agent supply to dynamic supply regulation that adapts to changing operating conditions, particularly temperature variations. The reducing agent supply rate is continuously adjusted based on real-time storage capacity measurements and temperature data, allowing the system to prevent reducing agent discharge during temperature increases while maintaining simple operational concepts through automated control.
Solution Approach 2:
The patent changes the key parameter of reducing agent supply rate from a fixed value to a variable that responds to storage capacity and temperature conditions. By making the supply rate a dynamic parameter rather than a constant, the system can adapt to temperature increases and prevent reducing agent discharge while maintaining the simplicity of automated control based on measured parameters.
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 reduces nitrogen oxide emissions by optimizing reducing agent supply, minimizing atmospheric discharge, and maintaining efficient conversion of nitrogen oxides across varying engine conditions.
Implementation Method 1
The storage capacity is to be understood to mean the quantity of reducing agent which can be stored in the coating and/or in the honeycomb body and, in particular, adsorbed, preferably physisorbed and/or chemisorbed, therein or thereon
Implementation Method 2
with increasing temperature of the reduction catalytic converter and without the method according to the invention, desorption of reducing agent out of the reduction catalytic converter can occur
Implementation Method 3
A reduction of the nitrogen oxides to form molecular nitrogen takes place with simultaneous consumption of the reducing agent. The selective catalytic reduction conventionally takes place in the exhaust gas as it flows through a correspondingly constructed catalyst carrier body
Data Source
AI summary
A method and device for reducing the nitrogen oxide proportion in exhaust gas of an internal combustion engine, carry out selective catalytic reduction on a reduction catalytic converter, at least discontinuously supplied with reducing agent. A reduction catalytic converter storage capacity for reducing agent and dependence of the storage capacity on temperature of the catalytic converter are considered when determining the reducing agent amount to be supplied. The reducing agent amount to be supplied can be adjusted to future temperature of the reduction catalytic converter and storage capacity at that temperature, for example preventing the reducing agent from desorbing from the catalytic converter when the temperature of the catalytic converter increases, e.g. by regenerating a particle filter. A reduced reducing agent amount is therefore supplied prior to regeneration of the particle filter instead of an amount required for stoichiometrically reacting nitrogen oxides in the exhaust gas without considering storage capacity.