Split-Flow Catalyst Valve Routing for Low-Temperature NOx Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current exhaust aftertreatment systems face inefficiencies at low temperatures due to reductant deposition and ammonia desorption issues, leading to suboptimal NOx reduction and potential emission regulation violations.
Innovation Solution
The aftertreatment system employs a dual-leg configuration with a selector valve to divert exhaust gas between two paths based on temperature, using a heater in the first path to maintain optimal conditions for the decomposition chamber and SCR system, and optimizing the SCR catalyst for low temperatures to enhance NOx reduction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If exhaust aftertreatment systems operate at low temperatures, then energy consumption is reduced, but reductant deposition occurs and ammonia desorption is insufficient leading to suboptimal NOx reduction
Solution Approach 1:
The system is divided into two separate exhaust gas paths: a first path with a heater for low temperature operation and a second path without heater for high temperature operation. The selector valve segments the exhaust flow to direct it through the appropriate path based on temperature conditions, resolving the contradiction between energy consumption and NOx reduction efficiency.
Solution Approach 2:
The system dynamically switches between two operational modes based on exhaust gas temperature. The selector valve adjusts in real-time to direct exhaust flow through the heated path when temperature is low (below threshold) and through the unheated path when temperature is high (above threshold), optimizing performance across varying operating conditions.
2Reliability
If a heater is added to the first exhaust gas path, then low temperature NOx reduction is improved, but device complexity increases
Solution Approach 1:
The heating function is segmented into a dedicated first exhaust gas path rather than being integrated into a single complex system. This modular approach allows the heater to be activated only when needed (low temperature conditions), reducing overall system complexity while maintaining improved low temperature performance.
3Quantity of substance
If reductant is injected into the decomposition chamber, then ammonia is produced for NOx reduction, but reductant deposits on chamber walls at low temperatures
Solution Approach 1:
The heater in the first exhaust gas path performs preliminary heating of the exhaust gas before it enters the decomposition chamber during low temperature operation. This preliminary thermal action prevents reductant deposition on chamber walls by maintaining the chamber temperature above the deposition threshold, while still enabling ammonia production through the decomposition chamber.
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 improves the efficiency of the aftertreatment system during low temperature conditions by reducing reductant deposition and maintaining ammonia storage, thereby achieving desired NOx reduction levels and compliance with emission regulations.
Implementation Method 1
The first exhaust gas path includes a heater configured to heat the exhaust gas received in the first exhaust gas path
Implementation Method 2
a selective catalytic reduction system that is formulated to reduce oxides of nitrogen in the exhaust gas in the presence of a catalyst
Implementation Method 3
a decomposition chamber configured to receive the reductant and decompose the reductant into a gaseous form
Data Source
AI summary
An aftertreatment system includes a first exhaust gas path, a second exhaust gas path, and a selector valve configured to divert exhaust gas between the first exhaust gas path and the second exhaust gas path based on a temperature of the exhaust gas. The aftertreatment system also includes a controller programmed to control the selector valve such that the selector valve diverts at least a portion of the exhaust gas to the first exhaust gas path when the temperature of the exhaust gas is equal to or less than a predetermined temperature threshold and the selector valve diverts the exhaust gas to the second exhaust gas path when the temperature of the exhaust gas is greater than the predetermined temperature threshold. The first exhaust gas path includes a heater configured to heat the exhaust gas received in the first exhaust gas path.