Prechamber Spark Ignition Engine Dilution Limit Extension
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Solution Overview
Problem
Spark ignition engines face challenges with operation at low load and cold start, poor dilution tolerance with recycled inert exhaust gases, and high nitrogen oxide emissions when using turbulent jet ignition technology, particularly under lean conditions.
Innovation Solution
A system and method that generates hydrogen-rich gaseous reformate outside the engine cylinders using a catalyst-coated substrate, which is then used to fuel a prechamber with a spark plug, extending the dilution limit of combustion with cooled exhaust gas recirculation and reducing NOx emissions by igniting significantly diluted fuel-air mixtures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If turbulent jet ignition technology is used to improve combustion efficiency and reduce emissions, then combustion stability is improved, but dilution tolerance with recycled inert exhaust gases deteriorates
Solution Approach 1:
The combustion system is divided into two separate chambers: a prechamber for generating stable flame jets and a main combustion chamber for accommodating diluted fuel-air mixtures. This segmentation allows each chamber to be optimized independently - the prechamber maintains combustion stability while the main chamber handles high dilution levels
Solution Approach 2:
The prechamber acts as an intermediary device that generates high-energy flame jets to ignite the diluted mixture in the main combustion chamber. This intermediary mechanism enables the main chamber to operate with high dilution levels that would otherwise be impossible to ignite directly
2Object-generated harmful factors
If excess air is used to dilute the fuel-air mixture to reduce NOx emissions, then NOx emissions are reduced, but ignitability of the gases in the prechamber deteriorates
Solution Approach 1:
The system segments the fuel-air mixture preparation into two stages: a relatively undiluted mixture in the prechamber that ensures ignitability, and a highly diluted mixture in the main combustion chamber that reduces NOx emissions while remaining ignitable due to flame jet injection
Solution Approach 2:
The prechamber performs preliminary combustion of a small quantity of fuel to generate high-energy flame jets before the main combustion event. This preliminary action creates ignition sources that can reliably ignite the subsequently introduced diluted mixture in the main chamber
3Use of energy by moving object
If lean combustion is used to improve fuel efficiency, then fuel efficiency is improved, but nitrogen oxide emissions increase
Solution Approach 1:
The system changes the combustion parameters by using a two-stage combustion process with different equivalence ratios in each chamber. The prechamber operates with a richer mixture for stable flame generation, while the main chamber operates with a leaner, highly diluted mixture that reduces peak temperatures and consequently reduces NOx emissions while maintaining fuel efficiency
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
The hydrogen-rich gaseous reformate improves combustion stability and reduces NOx emissions, allowing for higher dilution levels without the need for expensive aftertreatment systems, enhancing engine efficiency and extending the operating limits of the engine.
Implementation Method 1
generates a gaseous reformate from a fuel... containing a catalyst-coated substrate
Implementation Method 2
prechamber containing a spark plug... spark igniting the first combustible mixture in the prechamber
Implementation Method 3
high energy flame jets are ejected from the prechamber into a main combustion chamber, where they ignite compressed fuel-air mixture
Implementation Method 4
exhaust gas recirculation (EGR) line in communication with the engine intake line and the engine exhaust line. The EGR line selectively transports a portion of the exhaust gases from the engine exhaust line to the engine intake line
Data Source
AI summary
A system includes an engine having a main combustion chamber and a prechamber containing a spark plug. The prechamber is in fluid communication with the main combustion chamber through at least one orifice. An engine intake line provides intake air to the engine. An engine exhaust line receives exhaust gases from the engine. An exhaust gas recirculation line transports a portion of the exhaust gases from the engine exhaust line to the engine intake line, forming an exhaust gas recirculation loop through the engine. The system includes a reformer having a reactor containing a catalyst-coated substrate. The reformer generates a gaseous reformate from a fuel. The system includes a prechamber feed line to transport a stream of the gaseous reformate from the reformer to the prechamber.