Exhaust Gas Mixer Guide for Reactant Accrual
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Solution Overview
Problem
Existing exhaust gas aftertreatment systems face challenges in efficiently mixing reactants like urea without using compressed air, leading to reactant accrual on surfaces and reduced mixing efficiency due to turbulence.
Innovation Solution
A method and mixer design that utilizes a rotating flow of exhaust gas, an air-free doser, and a guide with a central opening to create a pressure difference, inhibiting turbulence and forming a laminar carrier flow around the doser to prevent reactant accrual.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If air-free dosing of reactant is used, then energy consumption is reduced and compressor is avoided, but reactant accrual occurs on doser tip and body
Solution Approach 1:
A guide structure with a central opening is introduced as an intermediary element between the doser and the exhaust gas flow. The guide defines a carrier flow that wraps around the doser, preventing reactant accrual without requiring compressed air. This mediator structure enables air-free dosing while eliminating the harmful accrual effect.
Solution Approach 2:
The invention uses the exhaust gas itself as a fluid carrier to create a protective flow around the doser. By utilizing the kinetic energy and pressure of the existing exhaust gas stream, a carrier flow is generated that prevents reactant accumulation on the doser surfaces, maintaining air-free dosing benefits while solving the accrual problem.
2Device complexity
If reactant is sprayed without gas phase carrier, then compressor and air supply system are eliminated, but mixing efficiency deteriorates due to turbulence
Solution Approach 1:
The guide structure acts as an intermediary that organizes the exhaust gas flow into a controlled carrier flow pattern. This carrier flow wraps around the doser in a laminar manner, providing a structured environment for reactant injection and mixing, thereby maintaining mixing efficiency without requiring external gas compression systems.
Solution Approach 2:
The guide structure modifies the flow parameters of the exhaust gas, transforming it into a controlled carrier flow with specific velocity and pressure characteristics. By changing the flow regime from turbulent to laminar in the region around the doser, the mixing efficiency is maintained while eliminating the need for complex compression systems.
3Ease of operation
If compressed air is used to disperse reactant, then mixing is easier and more efficient, but energy consumption increases and compressor is required
Solution Approach 1:
The exhaust gas flow serves itself as the dispersing medium for the reactant. The guide structure enables the exhaust gas to automatically form a carrier flow that disperses the reactant effectively, eliminating the need for external compressed air systems while maintaining easy and efficient mixing operation.
Solution Approach 2:
The invention utilizes the pneumatic properties of the exhaust gas flow to achieve reactant dispersion. By harnessing the pressure and velocity of the exhaust stream, the system creates an effective dispersing flow without requiring additional energy input from compressors, thereby maintaining ease of operation while reducing energy consumption.
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
Enhances reactant dispersion by reducing turbulence, preventing accrual on surfaces, and maintaining efficient mixing without compressed air, thus improving energy efficiency and mixing quality.
Implementation Method 1
forming a pressure difference between a periphery of the guide and the mixing chamber around the guide. The side flow may be guided out of the rotating flow using the pressure difference to the carrier flow around the doser via the central opening.
Implementation Method 2
inhibiting by the guide turbulence from being transferred from the side flow to the carrier flow. The inhibiting of turbulence may make the carrier flow laminar around the doser.
Implementation Method 3
feeding a rotating flow of exhaust gas in a mixing pipe towards a turning end of a mixing chamber
Data Source
Figure 1
Figure 2~3b
Figure 4a~5
AI summary
A mixer and a method therein, including feeding a rotating flow (150) of exhaust gas in a mixing pipe (120) towards a turning end (112) of a mixing chamber (110); dosing reactant by a doser (170) against the rotating flow around a centreline (122) of the mixing pipe; maintaining a guide (180) around the doser such that a front face of the guide faces the rotating flow, and the guide defines a central opening (182) surrounding the doser; guiding a side flow (1b) out of the rotating flow to a carrier flow around the doser via the central opening; and inhibiting by the guide turbulence from being transferred from the side flow to the carrier flow.