Reducing Agent Line Insert for SCR Backsuction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing SCR systems face challenges in completely sucking back reducing agents like aqueous urea solutions due to air bubble formation and line diameter limitations, which can lead to incomplete drainage and potential freezing issues at low temperatures.
Innovation Solution
An insert with a cylindrical bore and chamfered portion is integrated into the reducing agent line, reducing the cross-section to a smaller diameter, allowing effective bubble trapping and phase boundary conversion to a larger diameter, enabling almost complete drainage even with larger line diameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the line diameter is increased to improve reducing agent flow capacity, then the system performance is improved, but the ability to completely drain the line through backsuction deteriorates due to air bubble formation
Solution Approach 1:
The insert acts as an intermediary element within the reducing agent line, providing a restricted flow path through its cylindrical bore. This intermediary structure forces the reducing agent to flow through a smaller cross-section, preventing air bubble entrapment while maintaining the ability to use larger external line diameters for improved flow capacity
Solution Approach 2:
The insert segments the reducing agent line into different flow zones - a restricted zone through the cylindrical bore and a larger zone in the chamfered area. This segmentation allows the system to benefit from both small and large cross-sectional areas at different locations, resolving the contradiction between flow capacity and drainage completeness
2Reliability
If the line diameter is reduced to improve backsuctionability, then the drainage completeness is improved, but the system performance and flow capacity are limited
Solution Approach 1:
The insert with the smaller cylindrical bore is nested within the larger reducing agent line. This nesting arrangement allows the system to have a large external diameter for flow capacity while containing a smaller internal flow path for complete backsuctionability, effectively combining both requirements
3Device complexity
If residual reducing agent remains in the line after engine shutdown, then the system is simpler, but freezing occurs at low temperatures causing ice pressure in valves and lines
Solution Approach 1:
The insert serves as a mediator that enables complete draining of the reducing agent line by providing a restricted flow path that prevents air bubble formation. This allows the system to maintain simplicity without residual agent while avoiding the complexity of additional heating or drainage systems, and prevents freezing damage
Data Source
Figure 1
Figure 2a~2b
Figure 2c
AI summary
In order to prevent the formation of bubbles in a reductant line (2) of an exhaust gas reduction system, when reduction agent is extracted from the reductant line (2), an insert piece (4) is arranged in the reductant line (2) having a first cross-section. The insert piece (4) is designed in such a manner that it reduces the cross-section of the reductant line (2) to a second cross-section which is smaller than the first cross-section.