Swirl Generating Plate for SCR Urea Decomposition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional selective catalytic reduction (SCR) systems for diesel engines face issues with incomplete urea decomposition due to short residence times, low exhaust gas temperatures, and urea impingement on surfaces, leading to solid deposits that increase engine backpressure and degrade system performance.
Innovation Solution
The implementation of a swirl generating plate in the SCR system, which divides the intake flow into opposing swirls to enhance mixing and residence time, reducing urea deposits by increasing shear force and temperature, and directing fluid towards a merging point for improved decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional SCR systems use short residence times due to space constraints, then system compactness is improved, but urea decomposition completeness deteriorates leading to deposits
Solution Approach 1:
The decomposition chamber is divided into multiple zones: an intake chamber for receiving exhaust gas, an intermediate chamber for mixing, and a reaction chamber for decomposition. This segmentation allows each zone to perform its specific function efficiently, ensuring complete urea decomposition within a compact overall volume by optimizing the flow path and residence time in each segment.
2Use of energy by moving object
If exhaust gas temperature is low, then energy consumption is reduced, but urea decomposition efficiency deteriorates causing deposits on surfaces
Solution Approach 1:
A swirl generating plate is introduced as an intermediary device in the intake chamber to create rotational flow patterns. This mediator enhances the mixing between exhaust gas and urea solution without requiring additional energy input, thereby improving decomposition efficiency while maintaining low energy consumption and preventing surface deposits.
3Productivity
If urea is injected into the system, then NOx reduction capability is improved, but urea impingement on surfaces increases causing deposits and backpressure
Solution Approach 1:
The swirl generating plate utilizes curved surfaces to create rotational flow patterns that guide the injected urea solution through the exhaust gas stream. The curved geometry promotes uniform distribution and prevents direct impingement on chamber surfaces, thereby maintaining high NOx reduction capability while minimizing deposit formation and backpressure issues.
4Reliability
If mixing efficiency is increased through swirl generation, then decomposition completeness is improved, but device complexity increases
Solution Approach 1:
The swirl generating plate serves multiple functions simultaneously: it generates rotational flow for enhanced mixing, guides the exhaust gas flow through the decomposition chamber, and prevents direct impingement of urea on surfaces. This multi-functionality achieves complete decomposition without significantly increasing device complexity, as a single component accomplishes what would otherwise require multiple separate devices.
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 design significantly reduces urea deposits to near zero levels, minimizes recirculation, increases sidewall temperature, and enhances mixing efficiency, thereby reducing tailpipe NH3 slip and preventing adverse effects on fuel economy while maintaining desired flow characteristics.
Implementation Method 1
The swirl generating plate is configured to divide the intake flow into a first flow portion, a second flow portion, and a third flow portion... create opposing swirls in the internal volume
Implementation Method 2
reducing urea deposits by increasing shear force and temperature
Implementation Method 3
a selective catalytic reduction (SCR) system to convert NOx (NO and NO2 in some fraction) into harmless nitrogen gas (N2) and water vapor (H2O) in the presence of ammonia (NH3) and a reducing catalyst
Implementation Method 4
incomplete thermolysis of urea include short residence times... The urea or any other source of ammonia communicated into conventional aftertreatment systems
Data Source
AI summary
A selective catalytic reduction including a decomposition section including an intake chamber, with a swirl generating plate disposed in an internal volume of the intake chamber. The swirl generating plate includes a curved sidewall, a first end defining an opening, and a second end. The curved sidewall is oriented substantially normal to the direction of an intake flow of exhaust gas and a convex surface of the curved sidewall is oriented to face the direction of the intake flow. The swirl generating plate is configured to divide the intake flow into a first flow portion flowing through the opening, a second and a third flow portion which are directed substantially normal to the direction of intake flow and the flow direction of the first flow portion, and in opposite directions to each other towards a backwall of the intake chamber so as to create opposing swirls.