Swirler-Vane Mixing Conduit to Reduce Reductant Condensation
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Solution Overview
Problem
Conventional exhaust treatment systems in work vehicles face inefficiencies due to condensation of exhaust reductant on mixing conduit walls, leading to reduced reductant availability for mixing with exhaust gas, increased reductant consumption, and issues like caking and ammonia slip.
Innovation Solution
A mixing conduit with an inner and outer tube configuration and swirler vanes that promote heat transfer and mixing, reducing reductant condensation by maintaining a uniform temperature distribution and enhancing mixing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If liquid exhaust reductant is sprayed into the exhaust stream for mixing, then the reductant is introduced into the system, but condensation occurs on the mixing conduit walls reducing reductant availability
Solution Approach 1:
The mixing conduit is divided into an inner tube and an outer tube, creating separate flow paths. The inner tube carries the reductant-exhaust mixture while the outer tube carries hot exhaust gas, preventing direct contact between the cold mixture and the conduit walls that would cause condensation.
Solution Approach 2:
The outer tube acts as an intermediary heat transfer medium. Hot exhaust gas flows through the outer tube, transferring thermal energy through the tube wall to the inner tube, thereby heating the reductant mixture and preventing condensation without direct contact between the reductant and the heat source.
2Productivity
If the mixing conduit walls are cold relative to the exhaust mixture, then condensation is reduced, but mixing efficiency decreases due to liquid stream formation
Solution Approach 1:
By segmenting the flow paths into inner and outer tubes, the system prevents the formation of liquid streams along the wall. The reductant mixture remains confined to the inner tube where it mixes with exhaust gas, rather than flowing along the outer wall where condensation would occur.
Solution Approach 2:
The system changes the temperature parameter of the reductant mixture by transferring heat from the outer tube exhaust gas. This temperature increase prevents condensation and maintains the reductant in a vapor phase, improving mixing efficiency and preventing reductant loss.
3Reliability
If excessive reductant is consumed to meet emissions targets, then emissions standards are met, but system efficiency decreases
Solution Approach 1:
The system converts the potentially harmful cold conduit walls into a beneficial heat transfer surface. The outer tube exhaust gas, which would otherwise simply flow past, is utilized to heat the inner tube reductant mixture, preventing condensation and improving reductant utilization efficiency.
Solution Approach 2:
The hot exhaust gas flowing through the outer tube automatically serves to heat the reductant mixture in the inner tube through thermal conduction. The system uses its own exhaust gas as the heating medium, eliminating the need for external heating sources and improving overall efficiency.
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 solution increases the efficiency of the exhaust treatment system by ensuring more reductant is available for reaction, reduces caking, and minimizes ammonia slip, thereby meeting emission standards with optimal reductant usage.
Implementation Method 1
The engine exhaust flowing through the outer flowpath may heat the inner tube and reduce or prevent the reductant within the engine exhaust and reductant mixture from condensing on the inner tube
Implementation Method 2
The swirler vane(s) generally extends an effective length of the outer flowpath to promote heat transfer between the engine exhaust and the inner tube
Implementation Method 3
After a short distance, a portion of the liquid exhaust reductant typically condenses onto the walls of the mixing pipe due to the temperature differential
Data Source
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AI summary
A mixing conduit for use within an exhaust treatment system of a work vehicle. The mixing conduit is configured to receive engine exhaust and a mixture of engine exhaust and reductant. The mixing conduit includes an outer tube and an inner tube within the outer tube. Each tube extends lengthwise from upstream ends to downstream ends of the inner and outer tubes, respectively. The inner tube includes an exterior surface, and the outer tube includes an interior surface. The inner tube defines an inner flowpath within the inner tube. The outer tube and inner tube also define an outer flowpath radially between the exterior surface of the inner tube and the interior surface of the outer tube. The mixing conduit further includes one or more swirler vanes extending radially between the exterior surface of the inner tube and the interior surface of the outer tube and within the outer flowpath.