Ammonia SCR Control Model for Lean Engine NOx Reduction
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Solution Overview
Problem
Existing exhaust aftertreatment systems for internal combustion engines operating at lean air/fuel ratios face challenges in effectively managing NOx emissions, as they can lead to increased NOx emissions due to higher local combustion temperatures, and current urea injection control systems may not accurately adjust ammonia consumption in ammonia-selective catalytic reduction devices, resulting in inefficiencies.
Innovation Solution
A method for monitoring and adjusting ammonia consumption in ammonia-selective catalytic reduction devices by tracking adsorbed, desorbed, oxidized, and consumed ammonia, using a virtual sensor to determine ammonia storage concentration and adjust consumption based on real-time data, ensuring optimal NOx reduction without excess urea usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If urea injection control systems dispense urea at a rate corresponding to engine-out NOx emissions concentrations, then NOx reduction is achieved without excess urea usage, but inaccurate ammonia storage concentration estimates can result in inefficient NOx reduction or excess ammonia slip
Solution Approach 1:
The system continuously monitors actual ammonia storage concentration using sensors and feeds this information back to the control module. The control module then adjusts urea injection rates based on this feedback, creating a closed-loop control system that maintains accurate ammonia storage concentration estimates and optimizes NOx reduction efficiency while preventing excess ammonia slip.
Solution Approach 2:
The patent replaces traditional open-loop mechanical control of urea injection with an electronic control system that uses sensor data and computational algorithms to dynamically adjust injection rates. This substitution of mechanical control with electronic feedback-based control significantly improves measurement precision of ammonia storage concentration and enables more reliable NOx reduction.
2Use of energy by moving object
If engines operate at lean air/fuel ratios to improve fuel economy, then fuel consumption is reduced, but local combustion temperatures increase leading to increased NOx emissions
Solution Approach 1:
The system converts the harmful effect of high combustion temperatures (which produce NOx) into a beneficial outcome by using the ammonia-selective catalytic reduction device to transform excess ammonia into nitrogen and water vapor. The high temperatures that would normally create harmful NOx instead facilitate the SCR reactions that reduce NOx, turning the thermal condition into a benefit for emissions control.
Solution Approach 2:
The ammonia-selective catalytic reduction device acts as an intermediary between the engine exhaust and the atmosphere. It introduces ammonia as a intermediate substance that reacts with NOx to produce harmless nitrogen and water vapor, thereby mediating the harmful interaction between lean-burn combustion and NOx emissions.
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 allows for precise control of ammonia consumption, improving NOx reduction efficiency and reducing the risk of inaccurate ammonia storage concentration estimates, thereby enhancing the overall performance of the exhaust aftertreatment system.
Implementation Method 1
monitoring an amount of ammonia that is adsorbed, an amount of ammonia that is desorbed, an amount of ammonia that is oxidized and an amount of ammonia that is consumed in reducing NOx
Implementation Method 2
monitoring an amount of ammonia that is adsorbed, an amount of ammonia that is desorbed, an amount of ammonia that is oxidized and an amount of ammonia that is consumed in reducing NOx
Implementation Method 3
monitoring an amount of ammonia that is adsorbed, an amount of ammonia that is desorbed, an amount of ammonia that is oxidized and an amount of ammonia that is consumed in reducing NOx
Implementation Method 4
ammonia-selective catalytic reduction device configured to treat an exhaust gas feedstream
Implementation Method 5
ammonia that is consumed in reducing NOx in the exhaust gas feedstream
Data Source
AI summary
A method for monitoring a discrete substrate element from an ammonia-selective catalyst reduction device configured to treat an exhaust gas feedstream of an internal combustion engine includes monitoring amounts of ammonia that are adsorbed, desorbed, and oxidized and an amount of ammonia that is consumed in reducing NOx in the exhaust gas feedstream from the discrete substrate element. An amount of ammonia consumption for the discrete substrate element is determined based on the amount of ammonia that is oxidized and the amount of ammonia that is consumed in reducing NOx in the exhaust gas feedstream. The amount of ammonia that is adsorbed and the amount of ammonia that is desorbed for the discrete substrate element are compared and the amount of ammonia consumption for the discrete substrate element is adjusted when the amount of ammonia that is adsorbed is less than the amount of ammonia that is desorbed.