Exhaust Gas Treatment Assembly Reactant Mixing
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Solution Overview
Problem
Existing exhaust gas treatment systems for internal combustion engines face challenges in achieving efficient and compact exhaust gas cleaning due to limitations in mixing and heat transfer, leading to suboptimal catalytic reactions and increased heat loss.
Innovation Solution
The exhaust gas treatment arrangement incorporates a housing design with a flow deflection mechanism that allows exhaust gas to flow around the exhaust pipe, enabling thermal interaction for reactant evaporation and mixing, with a reactant delivery system positioned to maximize the mixing path and utilize the exhaust pipe length effectively, and includes an SCR catalytic converter arrangement for efficient nitrogen oxide reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the exhaust gas treatment arrangement uses a conventional linear arrangement of treatment units, then the system is simple to design, but the system size becomes large and heat transfer efficiency decreases
Solution Approach 1:
The exhaust gas treatment arrangement employs a nested configuration where the exhaust pipe carrying reactant is positioned inside or adjacent to the SCR catalytic converter arrangement. The exhaust gas channel formed by the exhaust pipe utilizes the space within the SCR assembly, allowing the reactant to flow through a meandering path that maximizes contact with hot exhaust gases while occupying minimal overall volume. This nesting approach enables compact system design without sacrificing mixing efficiency.
Solution Approach 2:
The invention transforms the conventional linear one-dimensional arrangement of treatment units into a three-dimensional meandering flow path. The exhaust gas channel winds through multiple directions (first longitudinal area, second transverse area, third longitudinal area) within the confined space of the exhaust treatment housing, effectively utilizing spatial dimensions to extend the mixing path length while maintaining a compact external footprint.
2Duration of action of moving object
If the reactant is injected early in the flow path, then there is more time for mixing, but the reactant may condense in cooler regions before reaching the SCR catalyst
Solution Approach 1:
The reactant delivery assembly is positioned to inject reactant into the exhaust gas flow at an early stage (upstream of the SCR catalytic converter arrangement), but the meandering exhaust gas channel ensures that the reactant immediately enters a region surrounded by hot exhaust gases. This preliminary injection combined with immediate thermal exposure prevents condensation while allowing sufficient mixing time, as the reactant is continuously heated along the winding path before reaching the catalyst.
Solution Approach 2:
The hot exhaust gases act as an intermediary medium that transfers thermal energy to the reactant throughout the meandering flow path. As the reactant flows through the exhaust gas channel, the surrounding hot exhaust gases continuously heat the reactant, preventing condensation and ensuring reliable delivery to the SCR catalyst while providing extended mixing time.
3Volume of moving object
If the exhaust pipe is positioned centrally through the SCR arrangement, then space is efficiently utilized, but heat transfer to the reactant is reduced
Solution Approach 1:
The exhaust gas channel is designed with a meandering, curved path rather than a straight central position. The channel winds through longitudinal and transverse areas, creating extended surface area contact between the hot exhaust gases and the reactant-carrying exhaust pipe. This curved, multi-directional path maximizes heat transfer surface area while maintaining efficient use of the housing volume, preventing heat loss despite compact positioning.
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 enhances the mixing of exhaust gas and reactant, promotes reactant vaporization, and improves catalytic reactions with minimized heat loss, achieving efficient and uniform cleaning of exhaust gases within a compact system.
Implementation Method 1
the heat of the exhaust gas flow leaving the SCR catalytic converter arrangement is used in order to transfer heat to the exhaust gas line carrying the mixture of exhaust gas and reactant to the SCR catalytic converter arrangement and thus to the mixture flowing therein through thermal interaction of the same
Implementation Method 2
This supports the evaporation of the reactant entrained in the exhaust gas or impinging on the inner surface of the exhaust pipe
Data Source
Figure 1~2
AI summary
An exhaust gas treatment arrangement for an exhaust system of an internal combustion engine comprises: - an exhaust gas treatment housing (18) with a housing inlet (34) and a housing outlet (60), - an exhaust gas treatment unit (28) in the exhaust gas treatment housing (18) with an exhaust gas treatment unit inlet (32) and an exhaust gas treatment unit outlet (38) downstream of the housing inlet (34), - an SCR catalyst arrangement (30) in the exhaust gas treatment housing (18) with an SCR catalyst arrangement inlet (54) and an SCR catalyst arrangement outlet (56) downstream of the exhaust gas treatment unit outlet (38), - a reactant delivery arrangement (62) for delivering reactant upstream of the SCR catalyst arrangement inlet (54), wherein an exhaust gas channel (42) formed in an exhaust gas line (44) in the exhaust gas treatment housing (18) extends from the exhaust gas treatment unit outlet (38). leading to the SCR catalyst assembly inlet (54),that the exhaust gas leaving the SCR catalyst assembly (30) at the SCR catalyst assembly outlet (56) flows around the exhaust pipe (44) at least in certain areas.