Oxygen-Enhanced Ammonia Engine Prechamber for Stable Low-NOx Ignition
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Solution Overview
Problem
Ammonia combustion in engines faces challenges with poor combustion characteristics, unstable ignition, low efficiency, and high NOx emissions due to its high nitrogen content and risk of ammonia escape.
Innovation Solution
An ammonia-fueled engine with an oxygen-enhanced prechamber system, featuring a jet ignition device with a prechamber inner cavity, spark plug, oxygen injector, and fuel injector, where oxygen is injected into the prechamber to dilute the gas mixture and improve reaction activity, allowing for stable ignition and combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If ammonia is used as fuel in conventional combustion conditions, then carbon emission reduction is achieved, but combustion stability and ignition reliability deteriorate due to poor combustion characteristics
Solution Approach 1:
The combustion chamber is divided into a prechamber and a main combustion chamber. Ammonia fuel is injected into the prechamber where it mixes with air and ignites first, then the flame propagates through jet holes into the main combustion chamber. This segmentation allows stable ignition in the prechamber to drive reliable combustion in the main chamber, resolving the combustion stability issue while maintaining carbon reduction benefits.
Solution Approach 2:
Ammonia fuel is injected into the prechamber during the intake stroke and mixed with air before compression. The prechamber mixture is prepared in advance and ignites before the main combustion chamber, providing a reliable ignition source that overcomes ammonia's poor ignition characteristics and ensures stable combustion.
2Reliability
If ammonia combustion is enhanced to improve combustion characteristics, then ignition stability improves, but NOx emissions increase due to higher combustion temperature
Solution Approach 1:
The equivalence ratio of the ammonia-air mixture in the prechamber is optimized to 0.8-1.2, which provides stable ignition while controlling combustion temperature. The prechamber volume ratio is set at 10-30% of the total combustion chamber volume, creating optimal conditions for stable ignition that propagate reliably to the main chamber without excessive temperature rise that would generate NOx.
Solution Approach 2:
The prechamber acts as an intermediary that facilitates stable ignition of ammonia fuel. By preparing and igniting the ammonia-air mixture in the prechamber first, it provides a controlled ignition source that then propagates to the main combustion chamber, achieving ignition stability while maintaining temperature control to limit NOx formation.
3Productivity
If oxygen concentration in prechamber is increased to enhance reaction activity, then combustion efficiency improves, but gas mixture concentration control becomes more difficult
Solution Approach 1:
The oxygen concentration in the prechamber is dynamically adjusted by controlling the intake valve timing and the oxygen injector operation. The equivalence ratio is maintained within the optimal range of 0.8-1.2 through dynamic control of the air-fuel mixing process, allowing the system to adapt to different operating conditions while maintaining high combustion efficiency and proper concentration control.
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 system enhances combustion efficiency and stability, expands the combustion limit, and reduces NOx emissions by improving jet temperature and speed, achieving low NOx combustion through flexible adjustment of reaction activity and jet intensity.
Implementation Method 1
The oxygen injector is configured to inject oxygen gas into the prechamber inner cavity
Implementation Method 2
igniting, by the spark plug, the gas mixture in the prechamber inner cavity to form a jet flame
Implementation Method 3
igniting a concentrated ammonia-air mixture in the combustion chamber to complete combustion work of an engine
Implementation Method 4
during a compression stroke, due to the compression of a piston, enabling ammonia gas in the combustion chamber to enter a prechamber inner cavity
Data Source
AI summary
An ammonia-fueled engine based on oxygen enhancement and reactive activity control, and an ammonia-rich combustion control method thereof are provided. The ammonia-fueled engine based on oxygen enhancement includes a jet ignition device and an ammonia gas injector. An oxygen injector is provided on the jet ignition device. During the operation of the ammonia-fueled engine, the ammonia gas injector firstly injects ammonia fuel into a combustion chamber, and ammonia gas in the combustion chamber enters a prechamber inner cavity through a jet hole during a compression stroke, and the oxygen injector firstly injects oxygen gas into a prechamber to reduce an ammonia concentration in a gas mixture in the prechamber, dilute the gas mixture in the prechamber, improve the reaction activity of the gas mixture, and ensure the speed and intensity of an initial flame; and then a jet flame is formed to ignite over-concentrated ammonia-air mixture in the combustion chamber.