Exhaust Gas Vortex Mixing for Reducing Agent Distribution
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Solution Overview
Problem
Existing exhaust systems face challenges in achieving uniform distribution and efficient evaporation of liquid reducing agents, such as mineral oil fuel and aqueous urea solutions, within internal combustion engine exhaust gas systems, particularly in ensuring effective ammonia release for nitrogen oxide reduction.
Innovation Solution
The system incorporates a first and second cylindrical exhaust pipe section with an injector unit for introducing reducing agents, where the exhaust gas flow is deflected by approximately 90 degrees upon connection, forming a stable rotating vortex in the second pipe section, allowing for efficient mixing and evaporation without the need for separate mixers, and utilizing evaporator plates to enhance evaporation through heat exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If liquid reducing agents are introduced into the exhaust gas, then the reducing agent can be supplied in a convenient form, but uniform distribution and evaporation become problematic
Solution Approach 1:
The patent changes the physical state parameter of the reducing agent from liquid to gaseous phase through evaporation on heated surfaces. The exhaust gas temperature serves as the heating parameter to evaporate the liquid reducing agent, transforming it into a fine spray that can be uniformly distributed in the exhaust stream.
Solution Approach 2:
The patent replaces mechanical mixing devices with a thermal-evaporation-based distribution system. Instead of using mixers or injectors that mechanically disperse the liquid, the system uses heated surfaces to evaporate the liquid reducing agent, allowing the exhaust gas flow itself to carry the vaporized agent uniformly downstream.
2Ease of operation
If liquid reducing agents are introduced into the exhaust gas, then the reducing agent can be supplied conveniently, but evaporation efficiency becomes problematic
Solution Approach 1:
The patent changes the thermal parameter by utilizing the existing exhaust gas temperature to provide the necessary heat for evaporation. The heated surfaces in the exhaust stream act as evaporation zones, transferring thermal energy from the hot exhaust gas to the liquid reducing agent, causing rapid phase change without requiring additional heating equipment.
Solution Approach 2:
The exhaust gas itself serves as the heating medium for evaporating the reducing agent. The thermal energy already present in the exhaust stream is utilized to complete the evaporation process, eliminating the need for separate heating systems or external energy sources.
3Quantity of substance
If aqueous urea solution is used as reducing agent, then ammonia can be released for nitrogen oxide reduction, but the hydrolysis and thermolysis processes are inefficient
Solution Approach 1:
The patent changes the thermal parameter by maintaining elevated exhaust gas temperatures throughout the reducing agent processing path. This thermal parameter control promotes efficient thermolysis of urea and subsequent hydrolysis reactions, ensuring complete decomposition into ammonia which then reacts with nitrogen oxides.
Solution Approach 2:
The patent ensures continuous processing of the reducing agent through the exhaust stream without interruptions or stagnant zones. The linear flow path from injection point through the heated section to the SCR catalyst maintains continuous evaporation, decomposition, and reaction processes, maximizing the productivity of ammonia generation and NOx reduction.
4Manufacturing precision
If separate mixers and evaporators are used to process reducing agent, then uniform distribution can be achieved, but device complexity increases
Solution Approach 1:
The patent merges the functions of injection, evaporation, mixing, and transport into a single integrated flow path. The reducing agent is injected directly into the exhaust stream where the hot gas simultaneously performs evaporation, mixing, and transport to the SCR catalyst, eliminating the need for separate mixer and evaporator components.
Solution Approach 2:
The exhaust gas flow serves multiple functions simultaneously: it acts as the heating medium for evaporation, the mixing medium for uniform distribution, and the transport medium for delivering the reducing agent to the SCR catalyst. This multi-functionality reduces the overall system complexity while maintaining effective reducing agent processing.
5Manufacturing precision
If separate mixers are used for distributing reducing agent, then uniform distribution can be achieved, but pressure loss increases
Solution Approach 1:
The patent replaces mechanical mixing systems with a thermal-evaporation-based distribution approach. The exhaust gas flow itself performs the mixing function through turbulent mixing and convection, eliminating the need for mechanical mixers that would create additional pressure drops. The system uses the existing flow energy to achieve uniform distribution without additional pressure loss.
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 configuration ensures effective and uniform distribution of reducing agents, improves evaporation rates, and enhances ammonia release, resulting in a compact and efficient exhaust system design with reduced pressure loss and flow resistance.
Implementation Method 1
The injector unit is preferably designed in such a way that it can inject or inject the reducing agent, which is preferably present in liquid form, into the exhaust gas in finely nebulized form
Implementation Method 2
immediately following the connection point of the first exhaust gas line pipe section with the second exhaust gas line pipe section, the main flow direction of the exhaust gas enriched with the reducing agent is deflected by at least approximately 90 degrees, as a result of which the exhaust gas is swirled and the reducing agent is mixed well in the exhaust gas
Implementation Method 3
As a result of this embodiment, it is possible to form a particularly stable rotating exhaust gas vortex in the second exhaust pipe section. This in turn enables a short design of the second exhaust pipe section or a short line length up to the subsequent exhaust gas cleaning unit
Implementation Method 4
utilizing evaporator plates to enhance evaporation through heat exchange
Implementation Method 5
utilizing evaporator plates to enhance evaporation through heat exchange
Implementation Method 6
releasing the ammonia required for the selective catalytic reduction of nitrogen oxides from the urea by hydrolysis and/or thermolysis
Implementation Method 7
releasing the ammonia required for the selective catalytic reduction of nitrogen oxides from the urea by hydrolysis and/or thermolysis
Implementation Method 8
releasing the ammonia required for the selective catalytic reduction of nitrogen oxides from the urea by hydrolysis and/or thermolysis
Data Source
AI summary
The invention relates to an exhaust gas system of an internal combustion engine and to a method for preparing a reducing agent which is introduced into the internal combustion engine exhaust gas. The exhaust gas system according to the invention has a reducing agent preparation section (1) with a first cylindrical exhaust gas line pipe portion (2) which opens approximately perpendicularly into a second exhaust gas line pipe portion (3) via an opening (8) in a cylinder lateral face of the second exhaust gas line pipe portion (3). An injector unit (4) for introducing the reducing agent into the exhaust gas is arranged on the first exhaust gas line pipe portion (2) upstream of the opening (8). According to the invention, the opening (8) in the cylinder lateral face of the second exhaust gas line pipe portion (3) has a greater extension in the direction of the length of the second exhaust gas line pipe portion (3) than transverse to said length. A rotating exhaust gas flow is formed within the second exhaust gas line pipe portion (3) for the method according to the invention.