Pressure Coupled Control for Natural Gas Engine Combustion
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Solution Overview
Problem
Natural gas engines using premixed combustion technology face issues such as poor responsiveness, high thermal load, and knocking, which limit the improvement of engine compression ratio and thermal efficiency, and the diffusion combustion method often results in insufficient matching of natural gas and diesel fuel pressures, reducing the effectiveness of igniting natural gas.
Innovation Solution
A pressure coupled control method and system that calculates and adjusts the target pressure values for diesel fuel and natural gas based on real-time operating conditions, ensuring they are injected into the engine as high-pressure fuels, allowing for precise matching and full combustion, thereby improving diffusion combustion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diffusion combustion method is used to improve compression ratio and thermal efficiency, then knocking problem is solved and compression ratio is improved, but natural gas pressure and diesel fuel pressure are insufficiently matched, reducing the effectiveness of igniting natural gas
Solution Approach 1:
The system implements feedback control by detecting actual diesel fuel pressure through a pressure sensor and using this information to adjust natural gas pressure. The electronic control unit continuously monitors the diesel fuel pressure and regulates natural gas pressure accordingly, ensuring precise pressure matching between the two fuels during diffusion combustion, thereby maintaining effective ignition while solving knocking problems
Solution Approach 2:
The system dynamically adjusts the pressure parameters of both diesel fuel and natural gas based on operating conditions. By changing the pressure parameters of natural gas in response to detected diesel fuel pressure, the system achieves optimal pressure matching for diffusion combustion, resolving the contradiction between reliability improvement and precision maintenance
2Ease of operation
If premixed combustion technology is used, then natural gas is mixed with air in intake pipe and ignited by spark plug, but responsiveness is poor, thermal load is high and knocking is prone to occur
Solution Approach 1:
The system inverts the conventional premixed combustion approach by using diffusion combustion where diesel fuel ignites natural gas directly in the cylinder rather than using a spark plug to ignite a pre-mixed charge. This inversion of the ignition method eliminates the need for precise intake mixing and spark timing, improving responsiveness while reducing thermal load and knocking tendencies
Solution Approach 2:
The system introduces diesel fuel as an intermediary substance to ignite natural gas. Instead of directly igniting the natural gas-air mixture with a spark plug, diesel fuel serves as a mediator that provides the necessary ignition source for natural gas diffusion combustion, thereby improving combustion control and reducing harmful effects
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 pressure coupled control method enhances the combustion efficiency of natural gas engines by ensuring full combustion of diesel fuel and natural gas, reducing knocking and burst pressure, and improving compression ratio and thermal efficiency.
Implementation Method 1
a high-pressure fuel pump, configured to increase pressure of the diesel fuel to the target pressure value, and deliver the diesel fuel to the fuel injection nozzle
Implementation Method 2
a high-pressure natural gas pump, configured to increase pressure of the natural gas to the target pressure value, and deliver the natural gas to the gas injection nozzle
Implementation Method 3
the fuel injection nozzle is used to inject the high-pressure diesel fuel into the cylinder, and the gas injection nozzle is used to inject the high-pressure natural gas into the cylinder
Implementation Method 4
diffusion combustion method of injecting the natural gas directly into the cylinder and igniting the natural gas with a small amount of diesel fuel
Data Source
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AI summary
The present invention relates to a pressure coupled control method and system for diffusion combustion of a natural gas engine, the method comprising: S11: detecting an operating condition of a natural gas engine; S12: an electronic control unit calculating a target diesel fuel pressure value flowing into a fuel rail of the natural gas engine according to the operating condition, and detecting an actual diesel fuel pressure value flowing into the fuel rail by means of a diesel pressure sensor in the fuel rail; S13: the electronic control unit calculating a target natural gas pressure value flowing into a gas rail of the natural gas engine according to the actual diesel fuel pressure value, and regulating a natural gas flowing into the gas rail by means of a signal of a gas rail pressure sensor in the gas rail; S14: after the target diesel fuel pressure value and the target natural gas pressure value are established, successively injecting high pressure diesel fuel and a high pressure natural gas into a gas cylinder; S15: detecting in real time a real-time operating condition of the natural gas engine, and promptly regulating the target diesel fuel pressure value and the target natural gas pressure value according to the real-time operating condition. The present invention improves diffusion combustion efficiency by means of the pressure coupled control of diesel fuel and natural gas.