Sequential Hydrogen Diesel Combustion for Power Density
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Solution Overview
Problem
Hydrogen's high ignition quality and knocking tendency pose challenges for internal combustion engines, leading to low power density and increased costs due to the need for low compression and excess air, which negatively impacts turbocharging and engine performance.
Innovation Solution
A method where diesel is used as the second fuel, injected into the combustion chamber after at least 80% of the first fuel (hydrogen) has burned, allowing for sequential combustion in two stages, optimizing fuel usage and combining properties to enhance efficiency and power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If hydrogen is used as fuel in internal combustion engines, then environmental friendliness and ease of production are improved, but power density and combustion efficiency deteriorate due to high knocking tendency requiring low compression ratios
Solution Approach 1:
The combustion process is divided into two distinct stages: first hydrogen combustion, then diesel combustion. This segmentation allows each fuel to be optimized for its specific combustion characteristics, with hydrogen providing clean burning and diesel providing high energy density and knock resistance
Solution Approach 2:
The patent combines hydrogen and diesel fuels in a single engine cycle, merging the advantages of both fuels: hydrogen's environmental benefits with diesel's high power density and combustion efficiency
2Reliability
If excess air is used during hydrogen combustion, then knocking tendency is reduced, but exhaust gas temperature decreases negatively impacting turbocharging
Solution Approach 1:
Hydrogen is burned first to pre-heat the combustion chamber and generate high-temperature exhaust gases before diesel injection, ensuring sufficient thermal energy for turbocharging while maintaining knock resistance through controlled excess air during the hydrogen phase
3Ease of operation
If diesel is used as ignition source in dual-fuel engines, then hydrogen combustion is enabled, but pure hydrogen operation becomes impossible and power is reduced due to limited diesel quantity
Solution Approach 1:
The engine operates in periodic cycles where hydrogen combustion occurs first, followed by diesel injection and combustion. This periodic sequence allows the system to leverage hydrogen's ease of combustion while periodically supplementing with diesel to maintain power levels
4Reliability
If low compression ratio is used for hydrogen, then knocking is prevented, but energy conversion efficiency decreases
Solution Approach 1:
The patent changes the combustion parameters by introducing a two-stage process: first stage uses hydrogen with low compression ratio to prevent knocking, second stage uses diesel with higher effective compression to improve energy conversion efficiency
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 enables higher power density and efficient energy conversion, similar to diesel engines, while reducing knocking tendencies and increasing thermal energy for turbocharging, thus overcoming the limitations of hydrogen operation.
Implementation Method 1
an air-fuel mixture is burned in a combustion stroke, wherein different fuels are burned sequentially in the combustion stroke
Implementation Method 2
liquid diesel fuel is injected into the cylinder, which is already almost completely burnt out. Due to the already high temperatures, this fuel ignites with very little ignition delay
Data Source
Figure 1~2
Figure 3
AI summary
In an internal combustion engine and a method for operating an internal combustion engine in which an air-fuel mixture and an exhaust-air mixture are sequentially burned in a working stroke, different fuels are burned sequentially in the combustion stroke.