Reformed Fuel Composition Control for Lean Combustion Engines
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Solution Overview
Problem
Existing internal combustion engines face challenges in achieving normal combustion of lean air-fuel mixtures across a wide operating range, particularly at low and high loads, leading to issues such as poor flame propagation, increased unburnt hydrocarbons, environmental impact from methane, and insufficient power output due to the composition of reformed fuels.
Innovation Solution
An internal combustion engine equipped with an operating state detection unit, fuel reforming unit, and a control device that adjusts the composition of reformed fuel based on engine load, optimizing the proportions of hydrogen, carbon monoxide, and methane to ensure efficient combustion across varying loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a lean air-fuel mixture is supplied to the output cylinder for uniform lean combustion, then NOx emission and soot are reduced, but flame propagation becomes poor and accidental fire occurs at low load
Solution Approach 1:
The invention adjusts the equivalence ratio of the air-fuel mixture based on operating conditions. At low load, a richer mixture (higher equivalence ratio) is supplied to ensure stable flame propagation, while at high load, a leaner mixture (lower equivalence ratio) is supplied to reduce NOx and soot emissions. This dynamic parameter adjustment resolves the contradiction between emission reduction and combustion stability.
Solution Approach 2:
The invention implements dynamic control of the fuel injection timing and amount to adapt the air-fuel mixture composition to varying engine loads. The control unit modifies the equivalence ratio in real-time, transitioning from a richer mixture at low load to a leaner mixture at high load, thereby maintaining both combustion reliability and emission performance across different operating conditions.
2Object-generated harmful factors
If the equivalence ratio is set low for lean combustion, then emissions are reduced, but the air-fuel mixture is excessively lean causing poor flame propagation and increased unburnt hydrocarbons
Solution Approach 1:
The invention dynamically adjusts the equivalence ratio parameter based on engine load detection. At low load conditions, a higher equivalence ratio (richer mixture) is used to ensure complete combustion and prevent unburnt hydrocarbons, while at high load conditions, a lower equivalence ratio (leaner mixture) is used to reduce emissions. This parameter optimization resolves the contradiction between emission reduction and combustion efficiency.
3Object-generated harmful factors
If a reformed fuel with high anti-knock property (high octane number) is used, then knocking is suppressed, but power output is insufficient at high load due to lower calorific value per mole
Solution Approach 1:
The invention uses a composite fuel system combining reformed fuel (high octane number components like hydrogen, carbon monoxide, and methane) with a pilot fuel (diesel or gasoline). The reformed fuel suppresses knocking due to its high anti-knock property, while the pilot fuel provides the necessary calorific value for adequate power output at high load. This composite approach resolves the contradiction between knocking suppression and power output.
Solution Approach 2:
The pilot fuel acts as an intermediary that initiates combustion in the reformed fuel mixture. The pilot fuel is injected at a specific timing to create localized high-temperature zones that ignite the reformed fuel, thereby ensuring complete combustion and adequate power output while maintaining the knocking suppression benefits of the reformed fuel.
4Object-generated harmful factors
If a reformed fuel with high hydrogen content is used for high anti-knock property, then knocking is suppressed, but preignition or knocking occurs at high load due to low flash point of hydrogen
Solution Approach 1:
The invention performs preliminary combustion using pilot fuel injection before the main reformed fuel combustion. The pilot fuel is injected and combusted first to create controlled high-temperature zones, which then ignite the reformed fuel at the desired timing. This preliminary action prevents preignition of the hydrogen-rich reformed fuel while maintaining its knocking suppression benefits.
Solution Approach 2:
The pilot fuel serves as an intermediary that controls the ignition timing of the hydrogen-rich reformed fuel. By injecting the pilot fuel at a precisely controlled timing, the invention ensures that the reformed fuel ignites only after the pilot fuel has created the necessary conditions, thereby preventing preignition while maintaining knocking suppression.
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
Enables uniform lean combustion and reduced emissions, enhancing thermal efficiency and power output while reducing emissions and reducing emissions, and improving combustion efficiency by optimizing the composition of reformed fuel mixtures for the fuel reforming unit.
Implementation Method 1
an air-fuel mixture having a high equivalence ratio is adiabatically compressed in the fuel reformation cylinder. Accordingly, the liquid fuel is reformed under a high-temperature and high-pressure environment
Implementation Method 2
the liquid fuel is reformed under a high-temperature and high-pressure environment, thereby generating a reformed fuel having a high anti-knock property, such as hydrogen (H2), carbon monoxide (CO), and methane (CH4)
Implementation Method 3
a fuel (e.g., light oil) having a higher ignitability than a reformed fuel is injected as a pilot fuel reformed fuel at an ignition timing near a compression top dead point. Accordingly, excellent ignition of a lean air-fuel premixture with a reformed fuel having a low ignitability can be obtained
Data Source
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AI summary
An internal combustion engine enabling normal combustion of a lean air-fuel mixture generated from a reformed fuel to be performed in a wide operating range is provided. An internal combustion engine (1) includes: an operating state detection unit (101-108) that detects an operating state of the internal combustion engine (1); a fuel reforming unit (2) configured to be supplied with a liquid fuel including hydrocarbon and generate a reformed fuel having an octane number larger than that of the supplied liquid fuel; a reformed fuel composition adjusting unit (28, 73, 75) that adjusts a composition of the reformed fuel generated by the fuel reforming unit (2); and a control device (100) that controls a composition of the reformed fuel by controlling the reformed fuel composition adjusting unit (28, 73, 75) in accordance with the operating state detected by the operating state detection unit (101-108).