Ring Catalyst Exhaust System for Rapid Urea Evaporation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing exhaust aftertreatment systems face delays in activating nitrogen oxide reduction due to suboptimal evaporation and mixing sections, especially at low exhaust gas temperatures, leading to inefficient urea solution metering and emission conversion.
Innovation Solution
An exhaust system with a ring catalyst featuring a tubular first flow path and annular second flow path, where a tube is guided through the second flow section to enhance heating and evaporation of the aqueous urea solution, allowing early metering and efficient mixing with exhaust gas for rapid conversion of nitrogen oxides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional catalyst design is used, then the installation space is larger, but the heating speed and activation time are slower
Solution Approach 1:
The catalyst is designed as a ring structure with segmented flow paths (first flow path and second flow path) that allow exhaust gas to flow through different sections sequentially. This segmentation increases the heating surface area and improves heat distribution, enabling faster heating speed while maintaining a compact installation space.
2Loss of time
If the aqueous urea solution is injected at low exhaust gas temperatures, then the metering can start earlier, but the evaporation is insufficient and the urea solution is carried away in liquid form
Solution Approach 1:
The ring catalyst is designed to heat the aqueous urea solution before injection into the main exhaust flow. The first flow path and second flow path are configured to pre-heat the urea solution using exhaust gas heat, ensuring that by the time the urea solution is injected, it has already been heated to a temperature that enables efficient evaporation, thus eliminating activation delay while maintaining evaporation reliability.
3Productivity
If the flow path is shortened, then the system response is faster, but the mixing time between urea solution and exhaust gas is insufficient
Solution Approach 1:
The ring catalyst design extends the flow path in the radial direction with concentric first and second flow paths, effectively increasing the mixing length without extending the axial dimension. This allows sufficient mixing time between the urea solution and exhaust gas while maintaining a compact overall system size and fast response speed.
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 design enables rapid heating and early metering of the urea solution, facilitating quicker evaporation and conversion of nitrogen oxides, thereby reducing emissions effectively, especially during cold starts.
Implementation Method 1
the tube opens into the ring catalyst and the tube has a radial extension at least into the inner first flow path... enables rapid heating and thus allows particularly early metering
Implementation Method 2
the solution must be evaporated. This requires a sufficiently high system temperature... enables particularly rapid heating and thus allows particularly early metering, making it possible to meter the aqueous urea solution shortly after the start of the upstream combustion engine
Implementation Method 3
The thermolysis and hydrolysis of the aqueous urea solution produce ammonia, which reacts with the nitrogen oxides in the exhaust gas, converting them into nitrogen and water vapor
Implementation Method 4
the ring catalyst has a tubular first flow path and an annular second flow path, which are aligned concentrically to each other and through which exhaust gas flows successively
Data Source
Figure 1
Figure 2
AI summary
The invention relates to an exhaust gas system for the post-treatment of exhaust gases from an internal combustion engine, said system comprising an annular catalytic converter (1) through which exhaust gas can flow, wherein the annular catalytic converter (1) has an inflow point (3) and an outflow point (11) and the annular catalytic converter (1) has a tubular first flow path (2) and an annular second flow path (7) which are oriented concentrically to one another and which can be passed sequentially, the first flow path (2) is radially outwardly surrounded by the second flow path (7), a tube (12) runs in the radial direction from outside through the second flow path (7), the tube (12) leads into the annular catalytic converter (1), and the tube (12) extends radially at least into the inner first flow path (2).