On-board Ammonia Decomposition for Cold-start Emission Control
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Solution Overview
Problem
Current emission control systems for internal combustion engines face challenges in delivering ammonia as a reductant for SCR catalysts, especially at low temperatures, due to the complexity and inefficiency of urea-based diesel exhaust fluid systems, which require high temperatures for decomposition and can lead to deposition issues.
Innovation Solution
An on-board vehicle system that generates hydrogen through the catalytic decomposition of ammonia from an ammonia/organic solvent solution, allowing for direct injection into the exhaust gas stream as a reductant, improving low-temperature performance and reducing system complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If urea-based diesel exhaust fluid systems are used to provide ammonia for SCR catalysts, then ammonia supply is achieved, but system complexity increases and low-temperature performance deteriorates due to requiring high temperatures for decomposition
Solution Approach 1:
The patent extracts the essential function (ammonia supply) from the complex urea decomposition system and replaces it with a direct ammonia storage system. The ammonia storage container directly stores and supplies ammonia without requiring thermal decomposition, eliminating the need for complex heating and decomposition control systems while maintaining reliable ammonia supply for SCR catalysts
Solution Approach 2:
The patent introduces an ammonia storage container as an intermediary component that directly holds and supplies ammonia to the SCR catalyst. This intermediary eliminates the need for urea as a precursor and the associated decomposition processes, simplifying the system architecture while ensuring consistent ammonia delivery across various operating temperatures
2Reliability
If urea-based diesel exhaust fluid systems are used, then ammonia can be generated, but deposition issues occur and low-temperature performance is poor
Solution Approach 1:
The patent removes urea from the system entirely and uses pure ammonia stored in an ammonia storage container. This extraction of the problematic urea component eliminates the deposition issues that arise from urea decomposition byproducts while maintaining the essential ammonia generation capability needed for SCR catalyst operation
Solution Approach 2:
The patent employs a simple ammonia storage container that directly supplies ammonia without complex decomposition mechanisms. This approach uses a straightforward, maintenance-free storage system that avoids the deposition problems associated with urea-based systems, effectively replacing a complex long-lived system with a simpler alternative that eliminates harmful deposition
3Quantity of substance
If high temperatures are used for urea decomposition, then ammonia can be produced, but system complexity increases
Solution Approach 1:
The patent extracts the ammonia production function from the thermal decomposition process and implements it through direct storage and supply from an ammonia storage container. This eliminates the need for high-temperature thermal management systems, heat exchangers, and decomposition control mechanisms while ensuring sufficient ammonia production for SCR catalysts
Solution Approach 2:
The ammonia storage container serves itself by directly storing and supplying ammonia without requiring external thermal energy input or decomposition processes. This self-service approach eliminates the need for complex thermal management systems while maintaining adequate ammonia supply for emission control
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
The system effectively provides hydrogen as a reductant for SCR catalysts, enhancing NOx conversion and reducing emissions at low temperatures, while simplifying the system and eliminating deposition issues associated with urea-based systems.
Implementation Method 1
a catalytic reactor in fluid communication with the ammonia source and configured to decompose ammonia from the ammonia source to generate hydrogen
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
An on-board vehicle reservoir containing an ammonia/organic solvent solution may be associated with a phase separator configured to isolate ammonia from the solution. The ammonia may be introduced into an exhaust gas stream of an internal combustion engine to function as a catalytic reductant. Ammonia may be employed to generate hydrogen via catalytic decomposition of ammonia, and the hydrogen may be introduced into an exhaust gas stream to aid catalytic reactions such as catalytic oxidation of carbon monoxide (CO) and/or hydrocarbons (HC) and/or reduction of nitrogen oxides (NO); for instance during a cold-start period.