Prechamber Water Injection for Combustion Engine NOx Reduction
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Solution Overview
Problem
High nitrogen oxide emissions and thermal loading in large combustion engines due to lean fuel-air mixtures are challenging to manage, especially with prechambers used as ignition intensifiers, where water injection to reduce NOx emissions compromises engine performance.
Innovation Solution
Introducing a two-phase medium, preferably water, into the prechamber after the first transfer phase to cool the burnt gases and reduce NOx formation without impairing the prechamber's ignition performance, by injecting it during the second transfer phase when backflowing gas forces it into the prechamber, utilizing high injection pressures to overcome cylinder pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If water is injected into the prechamber before or during ignition to reduce nitrogen oxide emissions, then NOx emissions are reduced, but the prechamber's ignition performance is compromised
Solution Approach 1:
Water is injected into the prechamber during the second transfer phase (after ignition has occurred) rather than before ignition. This preliminary timing ensures that the prechamber maintains optimal temperature and mixture conditions for ignition, while the water subsequently evaporates to cool the combustion gases and reduce NOx emissions during the expansion phase.
Solution Approach 2:
The water injection is performed periodically during specific phases of the combustion cycle (second transfer phase), rather than continuously or before ignition. This periodic injection at the optimal moment allows the system to alternate between maintaining ignition performance and reducing emissions, with the water being introduced only after the ignition process has been initiated.
2Use of energy by moving object
If a lean fuel-air mixture is used to improve efficiency and reduce thermal loading, then fuel efficiency improves, but ignition and combustion become more difficult
Solution Approach 1:
The prechamber is used to create a localized region with different mixture properties than the main combustion chamber. The prechamber receives a richer mixture or additional fuel gas to facilitate reliable ignition, while the main combustion chamber maintains the lean mixture for high efficiency. This local differentiation allows each zone to have optimal properties for its specific function.
Solution Approach 2:
The prechamber acts as an intermediary between the fuel supply system and the main combustion chamber. It receives fuel gas from the supply line, mixes it with air to create an ignitable mixture, and then transfers this prepared mixture to the main combustion chamber. This intermediary role allows the system to maintain lean operation in the main chamber while ensuring reliable ignition through the prechamber's enriched mixture.
3Reliability
If the prechamber is flushed with fuel gas to enrich the mixture and improve ignition, then ignition properties improve, but thermal loading of prechamber components increases
Solution Approach 1:
The invention changes the timing parameter of water injection to occur during the second transfer phase rather than before ignition. This parameter change allows the prechamber to maintain higher temperatures during ignition for improved reliability, while the subsequently injected water provides cooling during the expansion phase to reduce thermal loading on prechamber components and NOx emissions.
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
Effectively reduces nitrogen oxide emissions while maintaining conventional ignition temperatures and energy levels in the prechamber and main combustion chamber, requiring only small amounts of the cooling medium to achieve significant emission reduction.
Implementation Method 1
Through the evaporation of the medium or of the water in the prechamber, the contents of the prechamber are cooled
Implementation Method 2
after the ignition in the prechamber and optionally even before the ignition in the main combustion chamber in the same combustion cycle, an at least two-phase medium, preferably in its liquid state, is introduced into the prechamber. Through the evaporation of the medium or of the water in the prechamber, the contents of the prechamber are cooled
Data Source
AI summary
A method of operating a combustion engine provided with at least one flushed prechamber, and the at least one prechamber is connected to a main combustion chamber of the combustion engine. During a compression phase immediately preceding the ignition in the main combustion chamber—after ignition has taken place in the prechamber, in a first transfer phase, gas transfers from the prechamber into the main combustion chamber. After the first transfer phase, an at least two-phase, incompressible medium—preferably water—is introduced into the prechamber.