Ducted Fuel Injection for Soot Reduction in Combustion Engines
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Solution Overview
Problem
Direct injection engines produce high levels of soot and other undesired emissions, which are difficult to manage with existing after-treatment systems, leading to increased costs and environmental concerns.
Innovation Solution
The use of ducts to enhance local mixing of fuel and charge-gas within the combustion chamber, creating a premixed mixture with improved fuel-to-charge-gas ratios that minimizes soot and other emissions by directing fuel through a bore, causing turbulence and drawing in charge-gas, thereby achieving leaner combustion mixtures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If direct injection is used to improve engine efficiency, then engine efficiency increases, but soot emissions increase
Solution Approach 1:
The fuel injection system is segmented into multiple injection stages (pilot injection, main injection, post-injection) with different timing and duration. This segmentation allows the fuel to be injected in controlled portions, enabling better mixing with air and reducing soot formation by avoiding single large fuel deposits that create fuel-rich zones.
Solution Approach 2:
A pilot injection is performed before the main injection to preliminarily prepare the combustion chamber by introducing a small amount of fuel that ignites first. This preliminary action creates initial combustion conditions that facilitate better mixing and combustion of the subsequent main fuel injection, reducing soot formation.
2Power
If fuel-rich mixtures are used to improve combustion efficiency, then energy release increases, but soot production increases
Solution Approach 1:
The injection system uses periodic multi-stage injection cycles within each combustion event. Instead of a single continuous fuel-rich injection, the system alternates between fuel injection phases and mixing/combustion phases, creating periodic action that maintains power output while reducing peak fuel-rich conditions that generate soot.
Solution Approach 2:
The system dynamically changes injection parameters (timing, duration, pressure, quantity) to optimize the fuel-to-air ratio during different phases of combustion. By adjusting these parameters, the system maintains efficient combustion energy release while keeping the equivalence ratio in ranges that minimize soot production.
3Object-generated harmful factors
If after-treatment systems are added to reduce emissions, then emissions decrease, but system cost and complexity increase
Solution Approach 1:
The emission reduction is achieved through preliminary action at the source (combustion chamber) rather than through after-treatment. By optimizing fuel injection timing, quantity, and distribution before combustion occurs, the system prevents soot and unwanted emissions from forming in the first place, eliminating the need for complex after-treatment systems.
Solution Approach 2:
The combustion system performs self-service emission control through optimized fuel injection and combustion management. The system regulates its own fuel-air mixing and combustion process to inherently produce cleaner emissions, making external after-treatment systems unnecessary and reducing overall system complexity.
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 significantly reduces soot and other emissions, lowering the need for expensive after-treatment systems and improving engine efficiency by ensuring combustion occurs with equivalence ratios less than or equal to two, thereby reducing NOx, HC, and CO emissions.
Implementation Method 1
passage of the fuel causing charge-gas to be drawn into the bore such that turbulence is created within the bore
Implementation Method 2
turbulence is created within the bore to cause enhanced mixing of the fuel and the drawn charge-gas due to the large velocity gradients between the duct wall and the centerline of the fuel jet
Data Source
AI summary
Various technologies presented herein relate to enhancing mixing inside a combustion chamber to form one or more locally premixed mixtures comprising fuel and charge-gas to enable minimal, or no, generation of soot and/or other undesired emissions during ignition and subsequent combustion of the locally premixed mixtures. To enable sufficient mixing of the fuel and charge-gas, a jet of fuel can be directed to pass through a bore of a duct causing charge-gas to be drawn into the bore creating turbulence to mix the fuel and the drawn charge-gas. The duct can be located proximate to an opening in a tip of a fuel injector. The various technologies presented herein can be utilized in a number of combustion systems, such as compression-ignition (CI) reciprocating engines, spark-ignition (SI) reciprocating engines, gas-turbine (GT) engines, burners and boilers, wellhead/refinery flaring, etc.