Dual-Fuel Engine Combustion Mode Transition Control
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Solution Overview
Problem
Existing control methods for dual-fuel engines fail to effectively manage transitions between fuel modes due to variations in fuel composition, energy content, and environmental factors, leading to power surges, droops, and inadequate emission mitigation.
Innovation Solution
A method using a combustion index value to control dual-fuel engine operations by interpolating between engine operating maps for different fuel ratios, accounting for various engine parameters to achieve desired performance and emission criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If total fuel energy content is maintained constant during fuel mode transition, then fuel energy stability is improved, but engine power stability deteriorates due to airflow control devices unable to adjust rapidly enough
Solution Approach 1:
The invention changes the control parameter from total fuel energy content to combustion index, which directly correlates with engine power output. By monitoring and controlling the combustion index derived from exhaust gas analysis, the system can rapidly adjust fuel injection rates to maintain power stability during transitions, bypassing the limitation of slow airflow control devices.
2Use of energy by moving object
If lambda control is used to manage air-fuel ratio, then combustion efficiency is improved, but measurement accuracy deteriorates due to variations in fuel composition and environmental factors
Solution Approach 1:
The invention introduces an intermediary parameter - the combustion index - which is derived from exhaust gas composition analysis rather than direct lambda calculation. This intermediary measurement is less sensitive to fuel composition variations and environmental factors because it measures the actual combustion products rather than inferring air-fuel ratio from multiple variable inputs.
3Device complexity
If existing control methods are used to manage fuel transitions, then system complexity is reduced, but emission control effectiveness deteriorates due to inadequate mitigation of post-cylinder emissions
Solution Approach 1:
The invention implements a feedback control mechanism where exhaust gas composition is continuously analyzed and used to adjust fuel injection strategies in real-time. This feedback loop enables effective control of post-cylinder emissions including hydrocarbon slip and NOx by dynamically modifying combustion parameters based on actual emission-forming conditions, achieving better emission control without significantly increasing system complexity.
Data Source
AI summary
Apparatuses, methods and systems for controlling operation of dual fuel engines are disclosed. One embodiment is a method for controlling operation of a dual fuel engine based upon a combustion index value. The combustion index may be empirically determined to provide desired engine operation at a plurality of ratios of gaseous fuel and liquid fuel. The desired engine operation may include a number of criteria including, for examiner an engine knock criterion and/or an exhaust emissions criterion. The combustion index value may be determined during operation of the engine based upon measured, estimated or predicted engine operating parameters. The combustion index value may be utilized to interpolate between a first engine operating map for a first ratio of gaseous fuel and liquid fuel and a second engine operating map for a second ratio of gaseous fuel and liquid fuel.