Exhaust Mixing Device Impingement for Solute Deposit Prevention
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Solution Overview
Problem
Conventional exhaust gas purification systems face issues with solute deposits on mixing devices and exhaust passages due to uneven distribution of liquid reducing agents, leading to increased exhaust gas flow resistance and reduced fuel efficiency.
Innovation Solution
The exhaust gas purification apparatus positions the mixing device to ensure the liquid reducing agent or its precursor impinges on its entire surface, preventing droplet adherence and solute deposition, while optimizing the positional relationship between the injection nozzle and mixing device to promote uniform mixing and reduce solvent evaporation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the liquid reducing agent is injection-supplied to the exhaust passage, then NOx purification is achieved, but solute deposits on the mixing device and exhaust passage causing increased flow resistance
Solution Approach 1:
The mixing device is designed with a specific geometric shape and positioned at a predetermined location to create localized high-velocity flow regions. This ensures that the liquid reducing agent is dispersed uniformly across the exhaust passage cross-section, preventing localized droplet accumulation and subsequent solute deposits on the mixing device and exhaust passage surfaces.
2Productivity
If the liquid reducing agent spreads widely and impinges on the exhaust passage, then mixing is promoted, but solute deposits on the exhaust passage increasing flow resistance
Solution Approach 1:
The patent converts the potentially harmful effect of liquid reducing agent impingement on exhaust passage surfaces into a beneficial outcome by designing the mixing device to control the impingement pattern. The geometric shape and positioning create a flow distribution that promotes widespread mixing while minimizing droplet adherence, thus converting what could be a deposit-forming scenario into an effective mixing mechanism without causing solute deposits and associated energy losses.
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 prevents solute deposits, enhances mixing efficiency, and maintains exhaust gas purification performance by ensuring uniform impingement and distribution of the reducing agent, thereby improving fuel efficiency and reducing flow resistance.
Implementation Method 1
the liquid reducing agent or the precursor thereof adheres to the mixing device in a droplet state, raising a possibility that only a solvent evaporates from the liquid reducing agent or the precursor thereof adhering to the mixing device to deposit a solute
Implementation Method 2
an SCR catalyst for selectively reducing and purifying NOx in exhaust gas using a reducing agent
Data Source
AI summary
An engine exhaust gas purification apparatus for engine includes a mixing device for promoting mixing of a liquid reducing agent or a precursor thereof and exhaust gas is disposed at a position at which, when an engine is operating in a predetermined operating state, the liquid reducing agent or the precursor thereof injection-supplied from an injection nozzle impinges on substantially an entire surface of the mixing device. The predetermined operating state may be, for example, an operating state in which a solute tends to deposit from the liquid reducing agent or the precursor thereof. Thus, the liquid reducing agent or the precursor thereof adhering to the mixing device or an exhaust passage is reduced in absolute amount, thereby preventing that only a solvent evaporates from the liquid reducing agent or the precursor thereof adhering to the mixing device or the exhaust passage to deposit the solute.