Dual Fuel Engine Cylinder Pressure Control
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Solution Overview
Problem
Dual fuel engines face challenges in achieving an optimal balance between diesel fuel energy and natural gas energy due to difficulties in accurately determining the flow rate and heating value of natural gas, leading to suboptimal fueling substitution rates.
Innovation Solution
The system controls dual fuel engine operation by determining cylinder pressure and adjusting the substitution rate of natural gas for diesel fuel based on pressure measurements, including indicated mean effective pressure (IMEP) and combustion parameters, to maintain target energy contributions and prevent over-pressurization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If natural gas flow rate and heating value are used to determine substitution rate, then fueling control is simplified, but measurement precision deteriorates due to difficulty in accurately determining natural gas flow rate and variable heating value
Solution Approach 1:
The patent introduces cylinder pressure as an intermediary measurement that indirectly reflects the combined energy contribution of both fuels. Instead of directly measuring difficult-to-obtain natural gas flow rate and heating value, the system measures cylinder pressure which is directly influenced by the total energy release from combustion, thereby resolving the measurement precision problem while maintaining operational simplicity
Solution Approach 2:
The system implements a feedback control mechanism where cylinder pressure measurements are continuously monitored and used to adjust the substitution rate of natural gas for diesel fuel. The controller compares actual pressure readings with target values and dynamically adjusts fueling rates to maintain optimal combustion, thereby achieving precise control without requiring direct measurement of natural gas flow rate and heating value
2Speed
If substitution rate is adjusted based on estimated natural gas parameters, then control responsiveness is improved, but manufacturing precision deteriorates due to suboptimal fueling balance
Solution Approach 1:
The system uses real-time cylinder pressure feedback to continuously adjust the substitution rate, ensuring both rapid responsiveness to changing operating conditions and high precision in achieving the target fueling balance. The closed-loop control mechanism allows the system to quickly respond to pressure deviations while maintaining accurate fueling proportions through iterative adjustments
3Measurement precision
If cylinder pressure is monitored and used for control adjustments, then energy balance precision is improved, but device complexity increases due to additional pressure determination requirements
Solution Approach 1:
The cylinder pressure measurement system serves multiple functions simultaneously: it determines total energy output, monitors combustion characteristics, detects knock conditions, and provides feedback for substitution rate control. By making the pressure sensor multi-functional, the system achieves high measurement precision for energy balance without proportionally increasing device complexity, as the same sensor infrastructure supports multiple control objectives
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 precise adjustment of fueling to achieve optimal energy balance and torque output, improving engine performance and reducing emissions by ensuring accurate energy contributions from both fuel sources.
Implementation Method 1
determining a pressure of at least one cylinder of the engine
Implementation Method 2
The diesel fuel ignites, and the diesel combustion causes the natural gas to burn
Data Source
AI summary
Systems and methods for controlling operation of dual fuel internal combustion engines in response to cylinder pressure based determinations are disclosed. The techniques control fueling contributions from a first fuel source and a second fuel source to achieve desired operational outcomes in response to the cylinder pressure based determinations.