Compact SCR Doser Radial Flow Mixing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current SCR systems for reducing NOx emissions in diesel engines are costly and require significant space due to the need for extensive mixing of diesel emission fluid (DEF) with exhaust gases before entering the catalytic reactor.
Innovation Solution
A reduction agent doser with a tubular housing featuring a target plate, baffle, and diffuser plate configuration that directs exhaust gas flow in a serpentine path, ensuring adequate mixing of DEF with exhaust gases before entering the catalytic reactor, thereby reducing the system's spatial requirements while maintaining effective mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a conventional SCR system uses a long exhaust pipe (0.5m to 1.0m) for mixing DEF with exhaust gases, then adequate mixing is achieved, but the system requires considerable space and adds cost
Solution Approach 1:
The patent transforms the mixing process from a linear axial flow in a long pipe to a radial flow pattern using a target plate. The exhaust gas is directed radially outward against the target plate and then radially inward through the catalyst housing, creating a serpentine path that achieves adequate mixing within a compact cylindrical space, eliminating the need for a long exhaust pipe
Solution Approach 2:
The mixing process is divided into distinct zones: a first zone where exhaust gas flows radially outward against the target plate, and a second zone where gas flows radially inward through the catalyst housing. This segmentation allows each zone to perform a specific mixing function, achieving overall mixing effectiveness in a compact configuration
2Length of stationary object
If the SCR system is compacted to reduce space, then spatial requirements are reduced, but mixing effectiveness may be compromised
Solution Approach 1:
By introducing radial flow components through the target plate arrangement, the system creates a three-dimensional serpentine flow path within the cylindrical housing. This multi-dimensional flow pattern increases the effective mixing path length without increasing the overall system length, maintaining mixing effectiveness in a compact form
Solution Approach 2:
The system creates dynamic flow patterns where exhaust gas alternates between radially outward and radially inward motion. This dynamic serpentine flow ensures continuous mixing action throughout the catalyst housing, achieving adequate mixing in a compact space without requiring static long pipes
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 configuration allows for efficient mixing of DEF with exhaust gases within a reduced spatial footprint, enhancing the effectiveness of NOx reduction while minimizing costs by optimizing the flow path and latency period for the catalytic reaction.
Implementation Method 1
a target plate positioned crosswise in the housing and terminating at a distance from the inside diameter of the housing, the target plate directing a flow of exhaust gas in a radially outward direction
Implementation Method 2
a baffle positioned crosswise in the housing downstream from the target plate, the baffle terminating at the inside diameter of the housing and including a center opening for directing a flow of exhaust gas in a radially inward direction
Implementation Method 3
a diffuser plate located downstream from the baffle, the diffuser plate terminating at the inside diameter of the housing
Implementation Method 4
As the exhaust gas stream is passed through the SCR catalyst, the gaseous ammonia reacts with the NOx to reduce the NOx to molecular nitrogen
Implementation Method 5
When the temperature of the exhaust gas stream is above a reaction temperature, for example a temperature above 160°C for aqueous urea, the reduction agent undergoes a hydrolysis process and is decomposed into ammonia and CO2
Data Source
Figure 1
Figure 2
AI summary
An SCR system (12) for use with an IC engine (10) includes a reduction agent doser (24) and a catalytic reactor (26). The reduction agent doser (24) includes a tubular housing (28) with an inside diameter. A target plate (32) is positioned crosswise in the housing (28) and terminates at a distance from the inside diameter of the housing (28). The target plate (32) directs a flow of exhaust gas in a radially outward direction. A baffle (34) is positioned crosswise in the housing (28) downstream from the target plate (32). The baffle (34) terminates at the inside diameter of the housing (28) and includes a center opening (40) for directing a flow of exhaust gas in a radially inward direction. A diffuser plate (36) is located downstream from the baffle (34). The diffuser plate (36) terminates at the inside diameter of the housing (28). A catalytic reactor (26) is directly coupled with a downstream side of the reduction agent doser (24).