Dual-Fuel Engine Combustion Homogeneity Control
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Solution Overview
Problem
Current engine systems using both natural gas and diesel fuels face inefficiencies and high emissions due to limitations in controlling combustion processes, particularly in achieving homogeneous fuel mixtures and precise ignition timing.
Innovation Solution
A method involving the introduction of a non-compression-combustible fuel and a compression-combustible fuel into an engine cylinder, with a focus on mixing them to achieve a homogeneity factor of at least 0.5 before compression combustion, and delaying the start of combustion to optimize the combustion event, allowing for simultaneous ignition and propagation of flame fronts throughout the cylinder volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If diesel fuel is injected into natural gas/air mixture at end of compression stroke, then combustion is achieved, but fuel efficiency is reduced and emissions increase due to non-homogeneous mixture and delayed ignition control
Solution Approach 1:
The patent applies preliminary action by injecting diesel fuel early in the compression stroke (at a predetermined angle before top dead center) rather than at the end, allowing the fuel to mix with the natural gas/air mixture before compression combustion occurs. This preliminary injection and mixing action enables better homogeneity and controlled combustion timing, improving fuel efficiency and reducing emissions.
Solution Approach 2:
The patent changes the timing parameter of diesel injection from end-of-compression to early-compression stage, and adjusts the homogeneity factor of the fuel mixture. By controlling the injection timing and achieving a homogeneity factor of at least 0.5, the combustion process is optimized to reduce energy loss and harmful emissions.
2Measurement precision
If diesel injection timing is precisely controlled, then ignition timing is improved, but device complexity increases due to additional control mechanisms
Solution Approach 1:
The patent applies self-service by utilizing the natural compression heating process of the engine to achieve auto-ignition of the diesel fuel, eliminating the need for separate ignition systems or complex electronic control mechanisms. The predetermined injection timing before top dead center leverages the existing compression stroke to provide precise ignition control through the natural thermodynamic process.
3Manufacturing precision
If mixing time of fuels is increased to achieve homogeneity, then combustion quality improves, but productivity decreases due to extended preparation time
Solution Approach 1:
The patent performs the fuel mixing action preliminarily during the compression stroke by injecting diesel early and allowing it to mix with the natural gas/air mixture before compression reaches top dead center. This preliminary mixing during the existing compression phase achieves the required homogeneity factor without extending the overall engine cycle time, maintaining productivity while improving combustion quality.
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 enhances fuel efficiency, reduces emissions, and provides better control over the ignition event, resulting in lower NOx and particulate emissions, flex fuel capability, and cost-effective operation.
Implementation Method 1
compressing a piston in the cylinder volume, thereby compression combusting the second fuel
Implementation Method 2
compression combusting the second fuel
Implementation Method 3
mixing the first mixture and the second fuel in the cylinder volume, such that the first mixture and the second fuel have a factor of homogeneity of at least about 0.5 in the cylinder volume
Implementation Method 4
mixing the first mixture and the second fuel in the cylinder volume
Implementation Method 5
compression combusting the second fuel
Data Source
AI summary
A method of operating an engine comprises introducing into a cylinder volume a non-compression-combustible fuel, such as natural gas, a compression-combustible fuel, such as diesel, and an oxidant and mixing the components for greater than about 275 microseconds, prior to compression combusting the compression-combustible fuel. The mixing may be done such that the two fuels are at least partially homogenized in the cylinder volume. By mixing, or premixing, the two fuels prior to combustion, the compression-combustible fuel is then simultaneously combusted via compression at multiple ignition points in the volume. The second, non-compression-combustible fuel is ignited in response to the combustion of the first fuel. An engine that enables the various methods is also disclosed.