Pilot Fuel Low-Temperature Reaction Controls Constant-Volume Combustion
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Solution Overview
Problem
Internal combustion engines face challenges in achieving high efficiency due to instability in combustion processes, particularly in naturally aspirated engines, where constant volume combustion is difficult to control, leading to inefficiencies and knocking issues.
Innovation Solution
A method for operating a reciprocating piston engine that introduces a fuel-air mixture and a pilot fuel, where the pilot fuel's low-temperature reaction controls the timing and heat release to achieve rapid and simultaneous combustion under constant-volume conditions, minimizing nitrogen oxide production and stabilizing the combustion process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If constant-volume combustion is increased to achieve higher efficiency, then effective efficiency increases, but combustion stability deteriorates due to parallel constant-pressure and constant-volume processes causing severe knocking
Solution Approach 1:
The patent applies preliminary action by introducing a pilot fuel that undergoes low-temperature reaction before the main fuel combustion. This preliminary low-temperature reaction prepares the combustion chamber conditions (temperature, pressure, radical concentration) to enable controlled subsequent high-temperature combustion, preventing the instability and knocking that occur when constant-pressure and constant-volume processes proceed in parallel.
Solution Approach 2:
The combustion process is segmented into distinct stages: first the low-temperature reaction of the pilot fuel, then the high-temperature reaction of the main fuel-air mixture. This segmentation allows the combustion chamber to transition smoothly from constant-pressure to constant-volume conditions, maintaining combustion stability while achieving high efficiency.
2Productivity
If homogeneous fuel-air mixture is ignited simultaneously throughout the entire combustion chamber to achieve constant-volume combustion, then effective efficiency increases, but control difficulty increases due to the rapid energy conversion
Solution Approach 1:
The pilot fuel acts as an intermediary substance that facilitates controlled ignition of the main fuel-air mixture. The low-temperature reaction of the pilot fuel creates controlled heat release and radical generation, which then triggers the high-temperature reaction of the main fuel in a controlled manner, making the rapid energy conversion process controllable and measurable.
Solution Approach 2:
The patent utilizes parameter changes by controlling the timing and amount of pilot fuel injection to adjust the temperature and pressure evolution during combustion. By varying these parameters, the combustion process can be controlled to achieve simultaneous ignition throughout the combustion chamber while maintaining manageability and predictability.
3Ease of operation
If pilot fuel is introduced to control constant-volume combustion timing and heat release, then combustion control improves, but device complexity increases
Solution Approach 1:
The pilot fuel system serves multiple functions: it controls combustion timing, regulates heat release rate, prevents knocking, and enables constant-volume combustion. By consolidating these control functions into a single pilot fuel injection mechanism, the patent avoids the need for multiple separate control systems, thereby limiting the increase in device 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
This approach allows for improved control of constant volume combustion, increasing efficiency and reducing knocking, with the pilot fuel's low-temperature reaction initiating the fuel-air mixture's combustion, resulting in higher efficiency and lower nitrogen oxide production.
Implementation Method 1
the combustion of which has a low-temperature reaction and a subsequent high-temperature reaction
Implementation Method 2
controlled by the timing of the heat release resulting from the low-temperature reaction of the pilot fuel
Implementation Method 3
the combustion of which has a low-temperature reaction and a subsequent high-temperature reaction
Implementation Method 4
The energy conversion is so rapid that combustion takes place at a constant volume
Implementation Method 5
a fuel-air mixture is introduced into a combustion chamber of the reciprocating engine and compressed by the piston
Implementation Method 6
A stable constant-volume process exists when the effective efficiency reaches over 42% for naturally aspirated engines and over 52% for turbocharged combustion engines at full load
Data Source
Figure 1
AI summary
Method for operating a reciprocating engine (1) comprising a crankshaft (3) and at least one cylinder (4), wherein a fuel-air mixture (10) is introduced into a combustion chamber (8) of the reciprocating engine (1) and compressed by a piston (5) until the fuel-air mixture (10) ignites and burns under constant volume conditions in the combustion chamber (8), into which a pilot fuel (11) is introduced and burned, the combustion of which has a low-temperature reaction and a subsequent high-temperature reaction, wherein the combustion of the fuel-air mixture (10) under constant volume conditions is controlled by the time of the heat release resulting from the low-temperature reaction of the pilot fuel (11) and/or by the amount of heat released by the low-temperature reaction of the pilot fuel (11).