Downstream Reactant Injection for Exhaust Purification
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Solution Overview
Problem
Existing exhaust gas purification systems for internal combustion engines face challenges in achieving uniform distribution and efficient evaporation of reactants, such as ammonia or hydrocarbons, within the exhaust gas stream due to turbulence and non-uniform flow patterns.
Innovation Solution
An arrangement and method where a reactant is added downstream of an exhaust gas purification element, positioned within the laminar flow region at most 30 mm from the element's second end face, ensuring at least 90% of the reactant hits the element, utilizing a specially designed addition unit with a nozzle that adapts to flow conditions to achieve uniform distribution and evaporation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the reactant is added upstream of the exhaust gas purification element, then the reactant can be evaporated by the hot exhaust gas, but the distribution of the reactant becomes non-uniform due to turbulence
Solution Approach 1:
The patent inverts the conventional approach by adding the reactant downstream of the exhaust gas purification element instead of upstream. This reversal places the injection point in the laminar flow region where the exhaust gas flows uniformly over the element surface, ensuring even distribution of the reactant while still allowing evaporation to occur.
Solution Approach 2:
The exhaust gas purification element is used preliminarily to create a laminar flow condition before the reactant is injected. By positioning the element upstream of the injection point, the system prepares the flow environment in advance to ensure uniform reactant distribution when injected.
2Manufacturing precision
If the reactant is added downstream of the exhaust gas purification element, then the distribution of the reactant becomes uniform, but the evaporation efficiency decreases
Solution Approach 1:
The exhaust gas purification element acts as an intermediary surface that facilitates both uniform reactant distribution and evaporation. The element's surface provides a structured interface where the reactant can be evenly distributed and simultaneously exposed to hot exhaust gas for evaporation, resolving the contradiction between uniformity and evaporation efficiency.
3Duration of action of moving object
If the injection device is positioned far from the exhaust gas purification element, then the reactant has time to evaporate, but the distribution becomes non-uniform
Solution Approach 1:
The patent changes the flow regime parameter from turbulent to laminar by positioning the injection point downstream of the purification element. This parameter change allows for shorter injection-to-evaporation distances while maintaining uniform distribution, as the laminar flow conditions preserve spray pattern integrity even over shorter distances.
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 approach ensures a reproducible and uniform distribution of the reactant across the element's surface, enhancing the evaporation and conversion efficiency of the reactant in the exhaust gas stream, thereby improving the overall cleaning process.
Implementation Method 1
the impacting drops of the reactant are additionally atomized or can evaporate from the surfaces of the element directly into the exhaust gas stream
Implementation Method 2
at least partial evaporation of the reactant flow through the heat of the exhaust gas
Implementation Method 3
evaporate the reactant improve
Data Source
Figure 1
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AI summary
The invention relates to an arrangement (1) for cleaning an exhaust gas flow (2) of an internal combustion engine (3), comprising at least one exhaust gas line (4) in which an element (5) for exhaust gas cleaning is disposed having a first face (6) and a second face (7), wherein the exhaust gas flow (2) flows through the element (5) from the first face (6) to the second face (7), and an adding device (8) is provided downstream of the element (5) for adding a reaction agent (9) to the exhaust gas flow (2). The adding device (8) is positioned at a distance (10) of no more than 30 mm from the second face of the element such that at least part of the fed reaction agent strikes the second face of the element.