HCCI Engine Fuel Injection for NOx Reduction
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Solution Overview
Problem
HCCI engines face challenges in controlling emissions, particularly NOx production due to high combustion temperatures, and variability in expansion timing leading to roughness and pre-detonation, while conventional engines struggle with incomplete combustion and high NOx formation.
Innovation Solution
The implementation of a pilot quantity of fuel that will not support auto-ignition, dispersed within the combustion chamber, combined with a working fluid, allowing for controlled cool flame combustion and reduced peak temperatures, along with precise timing of auto-ignition to minimize NOx formation and pre-detonation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If compression ignition engines run with excess air to ensure adequate oxygen supply for complete combustion, then unburned hydrocarbons and carbon monoxide are reduced, but nitrogen reactivity increases at high temperatures forming oxides of nitrogen
Solution Approach 1:
The patent changes the temperature parameter by injecting fuel during the intake stroke rather than at combustion, allowing the combustion process to occur at lower peak temperatures. This reduces nitrogen reactivity while maintaining adequate oxygen supply through excess air, thereby reducing oxides of nitrogen formation
Solution Approach 2:
The patent performs preliminary fuel injection during the intake stroke, allowing fuel to be distributed throughout the combustion chamber before combustion occurs. This preliminary distribution enables complete combustion with excess air at lower temperatures, reducing both incomplete combustion products and nitrogen oxides
2Power
If fuel is injected into the center of the combustion chamber in conventional compression-ignition engines, then combustion is supported by concentrated fuel, but combustion proceeds for a long period with high temperatures developing
Solution Approach 1:
The patent performs preliminary fuel injection during the intake stroke, distributing fuel throughout the combustion chamber before combustion. This creates a more uniform fuel distribution that allows combustion to proceed more quickly and completely at lower temperatures, reducing the duration and peak temperature of combustion
Solution Approach 2:
The patent changes the spatial distribution of fuel from concentrated at the center to distributed throughout the combustion chamber. This local distribution quality enables multiple combustion zones to burn simultaneously at lower temperatures, reducing peak combustion temperature and duration
3Quantity of substance
If HCCI engines allow fuel to propagate throughout the combustion chamber volume before ignition, then combustion may occur simultaneously throughout the volume, but expansion timing becomes difficult to control causing roughness and pre-detonation
Solution Approach 1:
The patent performs preliminary fuel injection during the intake stroke, distributing fuel before compression and combustion. This preliminary distribution enables controlled auto-ignition timing while maintaining uniform fuel distribution throughout the combustion chamber, reducing pre-detonation and improving expansion timing control
Solution Approach 2:
The patent employs feedback control by monitoring combustion characteristics and adjusting fuel injection timing and quantity accordingly. This feedback mechanism enables precise control of expansion timing while maintaining the benefits of distributed fuel combustion, reducing roughness and pre-detonation
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 NOx emissions by maintaining lower flame temperatures, optimizing fuel distribution for complete combustion, and controlling auto-ignition timing, thereby improving combustion efficiency and reducing engine roughness.
Implementation Method 1
a piston disposed slidably within the cylinder, the piston having a bottom dead center position distal from the combustion chamber and a top dead center position proximate to the combustion chamber, a pilot quantity of fuel disposed substantially dispersably within the cylinder, a working fluid disposed compressably within the cylinder, the piston compressing the working fluid and the pilot quantity of fuel as it slides from the bottom dead center position to the top dead center position
Implementation Method 2
the pilot quantity of fuel is substantially a maximum quantity that will not support auto-ignition when the working fluid and the pilot quantity of fuel have been compressed
Implementation Method 3
allowing for controlled cool flame combustion and reduced peak temperatures
Data Source
AI summary
An internal combustion cylinder assembly includes a cylinder having a cylinder head at an end thereof, a combustion chamber disposed in the cylinder head, a piston disposed slidably within the cylinder, the piston having a bottom dead center position distal from the combustion chamber and a top dead center position proximate to the combustion chamber, a pilot quantity of fuel disposed substantially dispersably within the cylinder, a working fluid disposed compressably within the cylinder, the piston compressing the working fluid and the pilot quantity of fuel as it slides from the bottom dead center position to the top dead center position, and wherein the pilot quantity of fuel is substantially a maximum quantity that will not support auto-ignition when the working fluid and the pilot quantity of fuel have been compressed.