Exhaust Mixer Chamber Layout for Urea Decomposition
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Solution Overview
Problem
Existing exhaust treatment systems face inefficiencies in promoting the evaporative decomposition of reducing agents, such as urea solutions, which are crucial for effectively reducing nitrogen oxides in exhaust gases from internal combustion engines.
Innovation Solution
An exhaust treatment apparatus with a chamber and pipe configuration that includes a cylindrical wall, a pipe with a circumferential space, an injector, and a guide plate to enhance the contact area and heat transfer of the reducing agent, promoting efficient decomposition into ammonia.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the reducing agent is injected into the exhaust passage and heated by exhaust gas flow, then evaporative decomposition is promoted, but the decomposition efficiency is insufficient
Solution Approach 1:
The exhaust passage is divided into multiple segments: a heating section where the reducing agent is initially heated by exhaust gas, and a decomposition section where further decomposition occurs. This segmentation allows different decomposition stages to occur in optimized zones, improving overall decomposition efficiency and completeness.
Solution Approach 2:
A heating element or thermal mediator is introduced into the system to enhance heat transfer to the reducing agent. This intermediary component facilitates more efficient energy transfer from the exhaust gas to the reducing agent, promoting complete evaporative decomposition without requiring excessive residence time.
2Device complexity
If the reducing agent injection system is simplified, then device complexity is reduced, but decomposition efficiency decreases
Solution Approach 1:
The injection system combines multiple functions into integrated components. The injection nozzle is designed to simultaneously perform atomization, heating, and initial decomposition functions. The heating section and decomposition section are merged into a continuous flow path, reducing the number of separate components while maintaining high decomposition efficiency.
Solution Approach 2:
The exhaust passage structure serves multiple purposes: it acts as both the flow channel for exhaust gas and the heating/decomposition chamber for the reducing agent. The cylindrical partition wall simultaneously provides structural support, flow separation, and heat transfer surface, reducing the need for additional dedicated components.
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
The apparatus efficiently promotes the evaporative decomposition of reducing agents, enhancing the conversion of nitrogen oxides to nitrogen and water, thereby improving the overall efficiency of the exhaust treatment process.
Implementation Method 1
the exhaust gas flowing along the outer circumference direction of the pipe heats the entire pipe peripheral wall, thereby efficiently promoting evaporative decomposition of the reducing agent passing through the pipe
Implementation Method 2
efficiently promoting the evaporative decomposition of the reducing agent
Data Source
AI summary
An exhaust treatment apparatus for reducing nitrogen oxides contained in exhaust gas discharged from an internal combustion engine, the exhaust treatment apparatus including: a chamber that includes a cylindrical wall and includes one-side end and another-side end in a cylinder-axis direction, the one-side end including an inlet port for introducing the exhaust gas, the another-side end being closed; a pipe that includes: a pipe peripheral wall; an inlet provided in one-side portion of a pipe axis; and an outlet provided in another-side portion of the pipe axis and positioned outside the chamber, the pipe being disposed so that a circumferential space is formed between the cylindrical wall and the pipe peripheral wall; an injector that injects a reducing agent toward the circumferential space; and a guide plate that guides the exhaust gas and the injected reducing agent from a side of the circumferential space toward the inlet.