Dual-Fuel Combustion Phasing Control With Variable Pilot Shots
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Solution Overview
Problem
Dual fuel engines face challenges in balancing combustion efficiency and emissions due to variations in fuel quality and composition, particularly when using gaseous fuels, which can lead to undesired emissions and inefficiencies.
Innovation Solution
A dual fuel control system that adjusts the quantity of pilot fuel shots based on phasing error criteria, using in-cylinder pressure sensors to monitor heat release and adjust pilot fuel quantities in subsequent engine cycles to optimize combustion phasing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If tiny amounts of diesel fuel are used for ignition, then emissions are reduced, but combustion stability deteriorates due to fuel quality variations
Solution Approach 1:
The pilot fuel injection is divided into multiple shots (first shot, second shot, third shot) at different timing and quantities. This segmentation allows precise control of combustion phasing and stability while maintaining low overall diesel fuel consumption for emissions reduction.
Solution Approach 2:
The injection quantity of each pilot fuel shot is dynamically adjusted based on feedback from combustion phasing error detection. The system varies shot quantities in response to detected combustion variations to maintain stability despite fuel quality changes.
2Adaptability or versatility
If gaseous fuel composition varies, then fuel flexibility is improved, but combustion phasing control deteriorates
Solution Approach 1:
The system detects actual combustion phasing and compares it to desired phasing, then uses this feedback to adjust pilot fuel injection quantities in subsequent cycles. This closed-loop control compensates for variations in gaseous fuel composition and maintains precise combustion phasing control.
Solution Approach 2:
The system changes injection parameters (quantity, timing) of pilot fuel shots based on detected combustion characteristics. By adjusting these parameters in response to fuel composition variations, the system maintains optimal combustion control across different gaseous fuel blends.
3Reliability
If pilot fuel quantity is increased, then combustion stability is improved, but emissions increase due to higher diesel consumption
Solution Approach 1:
Instead of using a single large pilot fuel injection, the system segments the total pilot fuel quantity into multiple smaller shots. This achieves combustion stability through distributed ignition events while keeping the total diesel fuel quantity low for emissions reduction.
Solution Approach 2:
The system uses minimal pilot fuel quantities (partial action) distributed across multiple shots, which is sufficient to achieve stable combustion and ignite the gaseous fuel without the emissions penalty of larger single injections.
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 effectively compensates for fuel variations, improving combustion efficiency and reducing emissions by aligning combustion phasing with desired profiles, enhancing engine performance and stability.
Implementation Method 1
directly injecting an earlier shot and a later shot of a pilot fuel into a cylinder in an engine in a first engine cycle, and autoigniting the pilot fuel to ignite a primary fuel in the cylinder in the first engine cycle
Data Source
AI summary
An engine system operating and control strategy includes autoigniting a directly injected pilot fuel to ignite a primary fuel in a cylinder in a first engine cycle. The strategy further includes comparing data indicative of a heat release in a cylinder in the first engine cycle to phasing error criteria for an earlier pilot shot of the pilot fuel and a later shot of the pilot fuel. A quantity of one or more pilot shots in a subsequent engine cycle is varied, based on the comparison. Pilot shot quantity can be varied closed loop to obtain desired combustion phasing characteristics, such as when a characteristic of a primary fuel is changed during operation. Related apparatus and control logic is also disclosed.