Reactivity Control via Injection Temperature in Compression Ignition Engines
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Compression ignition internal combustion engines face challenges in achieving high energy efficiency while avoiding detonation and excessive emissions, particularly due to limitations in fuel reactivity and the need for complex and costly dual fuel supply systems.
Innovation Solution
A method controlling combustion through temperature-adjusted fuel injection, where a majority of the fuel is injected during the intake stroke at a lower temperature and a smaller fraction is injected at the end of the compression stroke at a higher temperature, enhancing reactivity and reducing detonation risks without requiring separate fuel systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high compression ratio is used to improve energy efficiency, then energy efficiency increases, but detonation occurs causing engine damage
Solution Approach 1:
The fuel injection is divided into multiple fractions with different reactivities. A first fraction with lower reactivity (higher octane number) is injected during the intake stroke, followed by a second fraction with higher reactivity (higher cetane number) injected near top dead centre. This segmentation allows the engine to achieve high compression ratios for improved efficiency while the low-reactivity first fraction prevents premature detonation.
Solution Approach 2:
The reactivity parameter of the fuel is changed by selecting fractions with different cetane and octane numbers. The first fraction has lower reactivity (higher octane number) to prevent detonation during compression, while the second fraction has higher reactivity (higher cetane number) to ensure reliable ignition at high compression. This parameter change enables operation at high compression ratios without detonation damage.
2Ease of operation
If dual fuel supply system is used to control reactivity, then combustion control improves, but device complexity increases
Solution Approach 1:
A single fuel supply system is designed to perform multiple functions: it can inject both the low-reactivity first fraction during intake stroke and the high-reactivity second fraction near top dead centre. The system achieves dual-fuel-like combustion control capability while maintaining the simplicity of a single fuel supply infrastructure, avoiding the complexity of completely separate fuel systems.
Solution Approach 2:
The fuel supply system dynamically adjusts injection timing and fuel fraction selection based on operating conditions. The control unit determines the appropriate first and second fuel fractions to inject at different times within the same combustion cycle, enabling flexible combustion control without requiring physically separate static fuel systems for each fuel type.
3Productivity
If hot fuel injection is performed early to improve combustion, then combustion efficiency improves, but detonation risk increases
Solution Approach 1:
The reactivity parameter of the injected fuel is changed by selecting appropriate fractions. The first fraction has lower reactivity (higher octane number) when injected during intake stroke, preventing detonation even if heated. The second fraction has higher reactivity (higher cetane number) injected near top dead centre when combustion is needed, ensuring efficient combustion without premature detonation risk.
4Object-generated harmful factors
If high injection pressure is used to reduce particulate emissions, then particulate emissions decrease, but energy loss increases
Solution Approach 1:
The reactivity parameter of the fuel is changed by using a second fraction with higher cetane number injected near top dead centre. This higher reactivity allows combustion to proceed more completely at lower injection pressures, reducing particulate emissions without requiring the high injection pressures that would cause significant energy losses.
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 high compression ratios without detonation, improving energy efficiency above 45% and reducing emissions, including NOx and particulates, while simplifying the fuel system and reducing the need for high-pressure injection.
Implementation Method 1
a fraction F2 of the quantity Q of fuel to be injected is heated by an active heating device 12 to a predetermined injection temperature T, which is exceeding 100°C and preferably ranges from 100°C to 420°C
Implementation Method 2
the fraction F2 of the quantity Q of fuel to be injected is heated by an active heating device 12 to a predetermined injection temperature T... so as to increase the reactivity of the fraction F2 of the quantity Q of fuel to be injected
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Method to control the combustion of a compression ignition engine (1) with reactivity control through the injection temperature; the control method provides for the steps of: establishing a quantity (Q) of fuel to be injected into a cylinder (2); injecting a first fraction (F1) of the quantity (Q) of fuel fed by a first feed system without active heating devices, preferably equal to at least 70% of the quantity (Q) of fuel, at least partially during the intake and/or compression stroke; injecting a second fraction (F2) of the quantity (Q) of fuel fed by a second feed system provided with at least one active heating device (12; 13), and equal to the remaining fraction of the quantity (Q) of fuel, into the cylinder (2) at the end of the compression stroke and preferably at no more than 60° from the top dead centre (PMS); and heating the second fraction (F2) of the quantity (Q) of fuel to an injection temperature (T) of over 100°C, before injecting the second fraction (F2) of the quantity (Q) of fuel.