Multi-Fuel Compression Ignition Engine CNG Diesel Operation
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Solution Overview
Problem
Compression ignition engines using compressed natural gas (CNG) face limitations due to CNG's low volumetric energy content, which restricts vehicle range and does not fully utilize the low cost of CNG, especially at low power or idle conditions.
Innovation Solution
Development of multi-fuel compression ignition engines that can operate on both liquid fuels like diesel and gaseous fuels such as CNG, utilizing electronically controlled hydraulic valve actuation and fuel injection systems to optimize combustion cycles, allowing for flexible fuel use and increased compression ratios, enabling efficient operation on CNG while supplementing with diesel fuel for higher power outputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If CNG is used in compression ignition engines, then fuel cost is reduced, but vehicle range is limited due to low volumetric energy content
Solution Approach 1:
The engine is designed to operate with multiple fuel types (CNG, diesel, or dual-fuel combinations) by incorporating both a CNG injection system and a diesel injection system. The electronic control system selectively activates the appropriate fuel delivery system based on operating conditions, allowing the engine to leverage the low cost of CNG while maintaining the high energy density of diesel for extended range requirements.
2Use of energy by moving object
If CNG is used at low power or idle, then fuel cost is reduced, but full advantage of low cost CNG is not taken
Solution Approach 1:
The engine employs dynamic fuel selection capability where the electronic control system continuously monitors operating conditions (load, speed, temperature) and dynamically switches between CNG-only mode, diesel-only mode, and dual-fuel mode. At low power or idle conditions, the system optimizes for CNG usage to maximize fuel cost savings, while at higher power demands, it transitions to diesel or dual-fuel operation to maintain operational efficiency and take full advantage of the low cost of CNG when appropriate.
3Power
If diesel fuel is used for higher power outputs, then power is improved, but fuel cost increases
Solution Approach 1:
The engine utilizes parameter changes in fuel composition and injection timing based on power demand. At low to medium power levels, the system operates on CNG with adjusted compression ratios and injection timing to optimize fuel cost savings. When high power output is required, the system transitions to diesel fuel or dual-fuel operation, changing the fuel parameters (energy density, combustion characteristics) to deliver the necessary power while minimizing fuel cost impact through optimized blend ratios and injection strategies.
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 solution enables extended vehicle range by utilizing CNG efficiently at low loads and switching to diesel for higher power, maintaining efficient combustion and reducing NOX generation, while ensuring reliable ignition and optimal energy conversion.
Implementation Method 1
fuel (diesel or biodiesel) is injected into the combustion chamber after the heat of compression exceeds the self ignition temperature of the fuel
Implementation Method 2
electronically controlled hydraulic valve actuation and fuel injection systems
Implementation Method 3
fuel (diesel or biodiesel) is injected into the combustion chamber
Data Source
AI summary
Methods of operation of liquid and gaseous multi-fuel compression ignition engines that may be operated on a gaseous fuel or a liquid fuel, or a combination of both a gaseous fuel and a liquid fuel at the same time and in some embodiments, in the same combustion event. Various embodiments are disclosed.