Remote Chamber Ignition System for Low Reactivity Fuels
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Solution Overview
Problem
Existing ignition systems for engines, particularly those using low carbon or zero carbon renewable fuels like natural gas and ammonia, struggle with achieving complete combustion due to the low chemical reactivity of these fuels, requiring an ignition source that can supply sufficient energy for fast and reliable combustion.
Innovation Solution
A remote chamber ignition system is developed, featuring a remote ignition chamber with an ignition source, a tubing assembly with high-voltage electrodes and sparkplugs, and an electronic controller for pretreating the combustible charge gas and controlling the spark timing to stimulate deflagration-to-detonation transition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If passive pre-chamber ignition system is used to generate local turbulence, then combustion duration is shortened and engine efficiency is improved, but ignition energy is insufficient for low reactivity fuels like natural gas and ammonia
Solution Approach 1:
The ignition system is divided into multiple functional zones: a pre-chamber for turbulence generation and a main combustion chamber for energy release. The tube structure segments the flame propagation path, allowing different regions to perform specialized functions - the pre-chamber creates turbulence while the main chamber receives and utilizes the high-energy ignition from the spark plug.
Solution Approach 2:
The system performs preliminary turbulence generation in the pre-chamber before the main combustion event. By creating local turbulence ahead of time, the system prepares the air-fuel mixture for faster and more complete combustion, thereby reducing overall combustion duration and improving efficiency without requiring excessive ignition energy.
2Productivity
If active pre-chamber ignition system is used to adjust air/fuel ratio, then combustion efficiency is improved for lean and EGR diluted combustion, but the limited pre-chamber volume restricts further improvement
Solution Approach 1:
The system extends the combustion process into the spatial dimension of the tube, allowing the flame to propagate through a controlled path from the pre-chamber to the main combustion chamber. This dimensional extension enables the limited pre-chamber volume to have a greater impact on overall combustion efficiency by creating a directed flame propagation path that utilizes the full length of the tube.
3Use of energy by moving object
If diesel-natural gas dual fuel engines use autoignition of pilot injection diesel, then ignition energy is increased to 30-200 J, but soot emission increases due to direct-injected diesel fuel
Solution Approach 1:
The system extracts and eliminates the diesel fuel component from the ignition process. Instead of using diesel for autoignition, the invention employs a spark plug-based ignition system that ignites the natural gas-air mixture directly without requiring diesel injection, thereby achieving high ignition energy while avoiding the soot emission problem associated with diesel combustion.
Solution Approach 2:
The system replaces the chemical autoignition mechanism of diesel with an electrical spark ignition system. The spark plug provides a controlled electrical discharge that ignites the natural gas-air mixture, substituting the mechanical/diesel-based ignition process with an electrical one that avoids soot generation while providing sufficient ignition energy for low reactivity fuels.
4Speed
If high-voltage electrodes are used for pretreating charge gas, then flame speed is enhanced and combustion is accelerated, but device complexity increases
Solution Approach 1:
The system merges the high-voltage electrode pretreatment function with the existing spark plug assembly. The electrodes are integrated into the tube structure and work in conjunction with the spark plug, combining multiple functions (pretreatment, ignition, and flame propagation control) into a unified assembly that enhances flame speed without proportionally increasing 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
The system effectively enhances flame speed and temperature, achieving complete or near-complete combustion of low reactivity fuels like natural gas and ammonia, while reducing pollutant emissions and improving combustion efficiency.
Implementation Method 1
using a plurality of high-voltage electrodes arranged along a length of the tube, pretreating the first combustible charge gas to generate radicals therein
Implementation Method 2
using the ignition source, igniting the pretreated first combustible gas to produce a deflagration flame
Implementation Method 3
providing a transient high energy spark to the deflagration flame using at least one of the high-energy discharge sparkplugs for stimulating deflagration-to-detonation transition
Implementation Method 4
a tube disposed between the remote ignition chamber and a main combustion chamber defined within the engine cylinder, the tube having a central passageway bounded by a wall and defining a flame propagation pathway
Data Source
AI summary
An ignition method is provided for an internal combustion engine having an engine cylinder and a remote ignition chamber in fluid communication with the main combustion chamber via a tubing assembly. The remote ignition chamber and tube are charged with a first combustible charge gas. The main combustion chamber is charged with a second combustible charge gas. A plurality of high-voltage electrodes arranged along the tube are used to pretreat the first combustible charge gas to generate radicals therein. The pretreated first combustible charge gas is ignited to produce a deflagration flame. A plurality of high-energy discharge sparkplugs arranged along the tube are used to sense a property of the deflagration flame. When the sensed property of the deflagration flame is within predetermined threshold limits, at least one of the high-energy discharge sparkplugs is used to provide a transient high energy spark to the deflagration flame to stimulate deflagration-to-detonation transition.