Dual Fuel Engine Control Modulating Gas Flow
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Solution Overview
Problem
Dual fuel engines face difficulties in achieving high natural gas substitution rates for diesel fuel over a wide range of operating conditions due to variations in natural gas composition and site conditions, and existing control schemes struggle to accurately measure and predict air flow rates and fuel properties, leading to inefficiencies and reduced power density.
Innovation Solution
The system modulates the flow rate of the second fuel to maximize substitution rates by regulating the first fuel injection rate based on engine operating conditions, maintaining desired power output by adjusting the fuelling amount of the first fuel and modulating the second fuel flow, independent of varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pilot ignited gaseous fuel engines are used with intake air throttling to maintain air-to-fuel ratios, then high substitution rates of natural gas for diesel fuel can be achieved, but the overall engine efficiency is reduced and power density is limited
Solution Approach 1:
The patent extracts and eliminates the intake air throttling mechanism from the system. By removing this component and its associated control complexity, the engine achieves high natural gas substitution rates without the energy losses and efficiency penalties that throttle-based control schemes impose on the air-fuel mixture.
Solution Approach 2:
The dual fuel engine system performs self-regulation of the air-to-fuel ratio through its inherent combustion characteristics. The diesel fuel combustion automatically adjusts the mixing ratio to maintain optimal conditions, eliminating the need for external throttling control systems and their associated energy losses.
2Adaptability or versatility
If pilot ignited gaseous fuel engines use intake air throttling to maintain air-to-fuel ratios, then high substitution rates can be achieved, but the engine is limited to lower boost pressures, lower compression ratios, and lower power density
Solution Approach 1:
The patent removes the intake air throttling mechanism that constrains power density. By eliminating this limiting component, the engine can operate at higher boost pressures and compression ratios while maintaining high natural gas substitution rates, thereby increasing power density.
Solution Approach 2:
The patent changes the operating parameters by eliminating the throttle constraint. This allows the engine to operate at higher boost pressures, higher compression ratios, and higher power densities while maintaining the ability to substitute natural gas for diesel fuel at high rates.
3Reliability
If existing control schemes are used to compensate for natural gas quality variations, then desired air-to-fuel ratio can be maintained, but the control is limited by the ability to accurately measure and predict air flow rates and fuel properties
Solution Approach 1:
The engine system performs self-regulation of the air-to-fuel ratio through the inherent combustion characteristics of diesel fuel. This self-service approach eliminates the need for complex measurement and prediction systems, achieving reliable control without requiring precise measurement of air flow rates and fuel properties.
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 maximum substitution of natural gas for diesel fuel, improving engine efficiency and power output while maintaining desired speed and torque, without the need for intake air throttling, thus enhancing overall engine performance and reducing costs.
Implementation Method 1
The diesel fuel is ignited by energy compression heating of the charge
Implementation Method 2
the diffusion combustion of the diesel fuel creates turbulent regions of extremely high temperature within the cylinders that can drive oxidation reactions of the gaseous fuel
Implementation Method 3
drive oxidation reactions of the gaseous fuel
Data Source
AI summary
Systems and methods for controlling fuelling of dual fuel internal combustion engines are disclosed. The control techniques maximize the substitution rate of gaseous fuel for the liquid fuel by determining a target fuelling amount for the liquid fuel and then regulating an actual fuelling amount of the liquid fuel in response to engine speed and power variations and by modulating the flow rate of the gaseous fuel to the engine.