Integrated Diesel Engine and SCR Control for Emissions Optimization
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Solution Overview
Problem
Diesel engines face challenges in simultaneously reducing nitrogen oxides (NOx) and particulate matter (PM) emissions due to conflicting operational parameters that affect fuel efficiency and combustion temperatures, and existing after-treatment systems like urea-based SCR face issues with ammonia slip and infrastructure limitations.
Innovation Solution
An integrated system and method that optimizes engine and after-treatment device operations using engine controllers to dynamically adjust fuel and urea consumption based on cost inputs, employing transfer functions to balance fuel efficiency, urea usage, and emissions control, while ensuring compliance with emissions regulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If diesel engines operate with high compression ratios and lean air-fuel mixtures to improve fuel efficiency, then fuel economy and hydrocarbon emissions improve, but nitrogen oxides emissions increase
Solution Approach 1:
The patent segments the emissions control function into two distinct parts: the engine control system manages fuel injection timing and EGR to reduce NOx formation, while the after-treatment system (SCR catalyst) handles the conversion of remaining NOx to nitrogen and water. This segmentation allows each system to optimize its specific function without compromising the other.
Solution Approach 2:
The patent introduces an intermediary substance (urea solution) that decomposes to form ammonia, which then acts as a reducing agent in the SCR catalyst. This intermediary enables the conversion of harmful NOx into harmless nitrogen and water vapor, resolving the contradiction between maintaining efficient combustion and reducing NOx emissions.
2Object-generated harmful factors
If cooled exhaust gas recirculation is used to reduce nitrogen oxides emissions, then NOx emissions decrease, but fuel consumption increases
Solution Approach 1:
The patent applies partial EGR (typically 10-30% exhaust gas recirculation) rather than excessive recirculation, combining it with precise fuel injection timing control and after-treatment systems. This partial action approach achieves sufficient NOx reduction while minimizing the impact on fuel consumption and engine performance.
Solution Approach 2:
The patent dynamically adjusts EGR rates based on operating conditions, combining them with adjustments in fuel injection timing, pressure, and quantity. This parameter optimization ensures that EGR is applied at levels that reduce NOx emissions without excessively increasing fuel consumption or compromising engine performance.
3Use of energy by moving object
If fuel injection timing is advanced to improve fuel efficiency, then fuel economy improves, but nitrogen oxides emissions increase
Solution Approach 1:
The patent employs dynamic fuel injection timing control that adjusts the start of injection (SOI) timing based on real-time operating conditions such as engine load, speed, and temperature. This dynamic adjustment allows the system to optimize fuel economy while preventing excessive NOx formation under high-load conditions where advanced timing would otherwise increase emissions.
Solution Approach 2:
The patent incorporates feedback mechanisms where sensors monitor exhaust gas composition and engine operating parameters, and the control system adjusts fuel injection timing accordingly. This feedback loop ensures that fuel injection timing is optimized for fuel economy while maintaining NOx emissions within acceptable limits through real-time adjustments.
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
Achieves optimal fuel and urea consumption while meeting stringent NOx and PM emissions standards, minimizing ammonia slip, and addressing infrastructure challenges by dynamically adjusting engine and after-treatment device operations according to fuel and urea price fluctuations.
Implementation Method 1
A diesel engine can be integrated with a urea-based selective catalytic reduction (SCR) system to reduce overall system NOx emissions
Implementation Method 2
the air-fuel mixture in the combustion chamber is compressed to an extremely high pressure, causing the temperature to increase until the fuel's auto-ignition temperature is reached
Implementation Method 3
causing the temperature to increase until the fuel's auto-ignition temperature is reached
Implementation Method 4
a percentage of the exhaust gases are drawn or forced back into the intake and mixed with the fresh air and fuel that enters the combustion chamber. The air from the EGR lowers the peak flame temperatures inside the combustion chamber
Data Source
AI summary
Through the use transfer functions, or other modeling types, directed toward the individual operation of an engine and after-treatment subsystems, an optimizer determines the trade-offs between fuel consumption, urea consumption, and reduction of NOx and PM emissions for each component of the integrated system. Evaluation of these trade-offs permits the optimizer to dictate how each component should be controlled, or adjusted, to achieve optimal fuel (and urea) consumption while meeting the constraints bounding the solution. Response characteristics can be triggered by adjusting certain engine operating levers in order to achieve optimal performance of the integrated system.