Multi-Fuel Engine Combustion Control via Pilot Injection
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Solution Overview
Problem
Internal combustion engines face challenges in achieving efficient combustion of fuels with high heat of vaporization and low flame speed, leading to poor combustion conditions, particularly when using energy-dense fuels that are prone to poor mixing and low ignitibility.
Innovation Solution
A multi-fuel engine system that adjusts the substitution ratio of carbon-containing fuels with carbon-free fuels like hydrogen and ammonia, along with adjustments in injection timings and exhaust gas recirculation, to enhance combustion efficiency and reduce carbon emissions across various engine operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If energy-dense fuels with high heat of vaporization are used, then fuel energy density is improved, but combustion efficiency deteriorates due to poor mixing and low flame speed
Solution Approach 1:
A pilot fuel injector introduces a small amount of pilot fuel (different from the main energy-dense fuel) into the combustion chamber before the main fuel injection. This pilot fuel acts as an intermediary that ignites first, creating ignition sources that then ignite the main energy-dense fuel, thereby solving the low flame speed and poor combustion efficiency problems while maintaining high energy density
Solution Approach 2:
The system changes the chemical composition parameter of the fuel mixture by combining pilot fuel with main fuel. This parameter change enables the fuel mixture to have both high energy density (from main fuel) and good combustion characteristics (from pilot fuel), resolving the contradiction between energy density and combustion efficiency
2Power
If carbon-containing fuels are used to maintain power output, then engine power is improved, but carbon emissions increase
Solution Approach 1:
The system changes the carbon content parameter of the fuel mixture by combining carbon-containing pilot fuel with carbon-free main fuel (hydrogen or ammonia). This parameter change allows the engine to maintain power output while significantly reducing carbon emissions, as the carbon-free main fuel provides the bulk of the energy without producing carbon dioxide
Solution Approach 2:
The fuel system uses a composite fuel approach, combining carbon-containing pilot fuel with carbon-free main fuel in a dual-fuel system. This composite fuel strategy enables the engine to achieve both power output requirements and emission reduction goals simultaneously
3Object-generated harmful factors
If substitution ratio of carbon-free fuel is increased to reduce emissions, then carbon emissions are reduced, but combustion stability deteriorates due to low flame speed
Solution Approach 1:
The pilot fuel acts as an intermediary that provides stable ignition sources for the carbon-free main fuel. This intermediary role ensures combustion stability even when the substitution ratio of carbon-free fuel is high, because the pilot fuel reliably initiates combustion in each cycle, preventing misfires and unstable combustion
Solution Approach 2:
The system optimizes the substitution ratio parameter by maintaining a small proportion of carbon-containing pilot fuel (typically 5-20% of total fuel energy) combined with carbon-free main fuel. This parameter optimization achieves both emission reduction and combustion stability simultaneously
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 system improves combustion efficiency, reduces carbon emissions, and mitigates issues like knock and pre-combustion by optimizing the ratio of fuels and adjusting ignition timing based on engine conditions, thereby enhancing overall engine performance.
Implementation Method 1
a multi-fuel engine configured to combust a first fuel and a second fuel
Implementation Method 2
adjustments in injection timings and exhaust gas recirculation
Data Source
AI summary
Methods and systems are provided for adjusting a substitution ratio based on water in a combustion mixture of a multi-fuel engine. In one example, a method includes adjusting a substitution ratio in response to an amount of water provided to a multi-fuel engine configured to combust a first fuel and a second fuel, the second fuel different than the first fuel.