Oscillating DPF Regeneration for Fuel and Thermal Management
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Solution Overview
Problem
Conventional active regeneration methods for diesel particulate filters in exhaust systems require high temperatures, leading to increased fuel consumption, thermal aging of catalysts, and higher insulation needs, which are costly and inefficient.
Innovation Solution
An exhaust gas treatment system that oscillates between two target temperatures (between 300°C and 600°C) using a diesel oxidation catalyst to exothermically react hydrocarbons, promoting both passive and active regeneration, while minimizing the thermal impact on downstream components through an oscillating regeneration sequence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high temperature active regeneration is used to oxidize soot on the DPF, then soot removal effectiveness is improved, but fuel consumption increases and thermal aging of downstream catalysts accelerates
Solution Approach 1:
The system alternates between active regeneration mode (high temperature, 600-650°C) and passive regeneration mode (lower temperature, 300-450°C) in periodic cycles. The control unit monitors soot load and exhaust conditions to switch between modes, using active regeneration only when necessary to oxidize accumulated soot, thereby reducing overall fuel consumption compared to continuous high-temperature operation.
Solution Approach 2:
The system dynamically changes the temperature parameter of exhaust gas by controlling the dosing rate of hydrocarbons to the DOC. During active regeneration, higher hydrocarbon dosing raises temperature to 600-650°C for efficient soot oxidation. During passive regeneration, lower dosing maintains temperature at 300-450°C, reducing fuel consumption while still achieving soot removal through NO2-assisted oxidation.
2Productivity
If high temperature active regeneration is used to oxidize soot on the DPF, then soot removal effectiveness is improved, but thermal aging of downstream SCR catalyst accelerates
Solution Approach 1:
The system uses periodic alternation between active and passive regeneration modes to limit the duration and frequency of high-temperature exposure to downstream catalysts. By switching to passive regeneration at lower temperatures (300-450°C) during normal operation, the SCR catalyst experiences reduced thermal stress and aging, extending its service life while maintaining soot removal effectiveness through periodic active regeneration cycles.
Solution Approach 2:
The system converts the potentially harmful high-temperature condition into a beneficial controlled process by using it only when necessary (active regeneration mode) and limiting its duration. The majority of the time, the system operates in passive regeneration mode at lower temperatures that are gentle on catalysts but still effective for soot oxidation through NO2, thereby turning the thermal stress challenge into an opportunity for catalyst protection.
3Productivity
If high temperature active regeneration is used to oxidize soot on the DPF, then soot removal effectiveness is improved, but insulation requirements and system cost increase
Solution Approach 1:
The system alternates between active regeneration mode requiring high temperature (600-650°C) and passive regeneration mode operating at lower temperature (300-450°C). By spending most operational time in the lower-temperature passive mode, the average thermal load on the exhaust system is reduced, allowing for lighter insulation materials and reduced thermal protection requirements while maintaining effective soot removal through periodic active regeneration.
Solution Approach 2:
The system changes the operating temperature parameter dynamically between two distinct ranges: 600-650°C during active regeneration for maximum soot oxidation rate, and 300-450°C during passive regeneration for reduced thermal requirements. This parameter switching allows the exhaust system to be designed for the lower average temperature, reducing insulation mass and system cost while achieving the same cumulative soot removal performance.
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 reduces fuel consumption, minimizes thermal aging of catalysts, and decreases insulation requirements by maintaining an average temperature between the two target temperatures, thereby improving the efficiency and longevity of the exhaust treatment system.
Implementation Method 1
The DOC includes one or more precious group metals (e.g., platinum, palladium, etc.) that act as a catalyst to reduce emission of carbon monoxide, hydrocarbons, and volatile organic compounds. The DOC also oxidizes NO to NO 2 , which promotes faster SCR reactions and enhances passive regeneration.
Implementation Method 2
The DOC includes one or more precious group metals (e.g., platinum, palladium, etc.) that act as a catalyst to reduce emission of carbon monoxide, hydrocarbons, and volatile organic compounds.
Implementation Method 3
During passive regeneration, the carbon-based soot reacts with NO 2 in accordance with Equation (2) and Equation (3): C + 2NO 2 → CO 2 + 2NO (2) C + NO 2 → CO + NO (3)
Implementation Method 4
a selective catalytic reduction (SCR) element can be used to convert the NO x present in exhaust gas into other compounds, such as nitrogen, water, and carbon dioxide
Implementation Method 5
The DOC also oxidizes NO to NO 2 , which promotes faster SCR reactions and enhances passive regeneration.
Data Source
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AI summary
An exhaust gas treatment system for an internal combustion engine includes an exhaust gas pathway configured to receive exhaust from the engine, a diesel particulate filter (DPF) element positioned in the exhaust gas pathway to capture particulate matter from the exhaust, and a regenerator operable to increase a temperature of the exhaust that passes through the DPF element. The system also includes a controller configured to selectively operate the exhaust gas treatment system in a first mode in which the regenerator is inactive such that a temperature of the exhaust is within a first range, a second mode in which the regenerator is activated to increase the temperature of the exhaust to a first target temperature beyond the first range, and a third mode in which the regenerator is activated to increase the temperature of the exhaust to a second target temperature greater than the first temperature.