Reciprocating Engine Combustion Control via Pilot Fuel Injection
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Solution Overview
Problem
Existing combustion methods for four-stroke reciprocating piston internal combustion engines face challenges in precisely controlling the ignition point, especially during dynamic operation with variable rotational speeds, leading to uncontrolled auto-ignition and increased NOx emissions.
Innovation Solution
A combustion method that introduces a fresh gas and primary fuel into the combustion chamber, forming intermediate products through a pilot fuel quantity, which are then compressed and ignited only when the mixture is fully formed, allowing for controlled ignition and delayed combustion, reducing NOx emissions by using fuels like formaldehyde and hydrogen peroxide, and optionally mixing with exhaust gas for further emission reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If homogeneous lean mixtures are used for compression ignition, then efficiency is improved and exhaust gas emissions are reduced, but uncontrolled auto-ignition occurs leading to steep pressure rise and increased NOx emissions
Solution Approach 1:
A pilot quantity of fuel is introduced before the main fuel quantity to initiate controlled combustion reactions. This preliminary action creates intermediate products that enable controlled ignition timing, preventing uncontrolled auto-ignition while maintaining efficient lean combustion operation
Solution Approach 2:
The combustion process is controlled by changing parameters including the timing and quantity of pilot fuel injection, the main fuel injection timing, and the compression ratio. These parameter changes enable precise control of ignition timing and combustion rate, reducing NOx emissions while maintaining efficiency
2Adaptability or versatility
If activation fuel is injected during compression to control ignition timing, then operating range is expanded, but precise control of ignition point becomes difficult during dynamic operation with variable rotational speeds
Solution Approach 1:
The combustion process incorporates feedback mechanisms where the pilot fuel quantity and timing are adjusted based on engine operating conditions including rotational speed. This feedback control enables precise ignition timing across the entire operating range, solving the problem of imprecise control during dynamic operation
Solution Approach 2:
The system dynamically adjusts the pilot fuel quantity and injection timing based on real-time operating conditions such as rotational speed and load. This dynamic adaptation maintains precise ignition control across varying operating conditions, expanding the usable operating range while preserving control precision
3Measurement precision
If complete ignition of the mixture is suppressed during compression phase, then combustion timing is delayed for control purposes, but additional intermediate products must be managed
Solution Approach 1:
Intermediate combustion products formed during the compression phase with pilot fuel act as mediators that facilitate controlled ignition of the main fuel mixture. These intermediate products enable precise timing control by creating a controlled reaction pathway that delays main ignition until the desired timing while managing the quantity of intermediate substances
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 method enables precise control over ignition, reduces NOx emissions, and achieves a lean combustion process with low combustion temperatures, compliant with emission regulations without increasing fuel consumption, and can be applied to various fuels.
Implementation Method 1
a pilot quantity of fuel is introduced before the primary quantity of fuel is introduced intermediate products of the pilot quantity of fuel are formed
Implementation Method 2
compresses the fresh gas and fuel in the compression phase
Implementation Method 3
igniting a mixture, which comprises fresh gas and fuel and is formed in the combustion chamber
Data Source
AI summary
A reciprocating engine includes a combustion chamber, and a gas exchange inlet valve and a gas exchange outlet valve for a charge cycle. The method introduces an inlet gas into the combustion chamber in an intake phase; introduces a primary quantity of fuel into the combustion chamber during the intake phase and/or a compression phase; compresses the inlet gas and the fuel in the compression phase; ignites a mixture of inlet gas and fuel formed in the combustion chamber; and expands and discharges an exhaust gas formed by the combustion in an expansion phase. A pilot quantity of fuel is introduced into the combustion chamber before the primary quantity of fuel is introduced. Intermediate products of the pilot quantity of fuel are formed and the primary quantity of fuel is introduced into the combustion chamber during the compression phase such that complete ignition of the mixture consisting of inlet gas and the intermediate products is suppressed and other intermediate products are formed until a controlled ignition of the mixture and other intermediate products occurs.