Multi-Fuel Engine Startup Using Dynamic Hydrogen-Diesel Ratio
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Solution Overview
Problem
Multi-fuel engine systems, particularly those using hydrogen and diesel, face challenges during startup due to low engine temperatures, leading to inefficient combustion, delayed ignition, and increased emissions of unburned diesel and undesirable combustion by-products like carbon monoxide, soot, NOx, and particulate matter.
Innovation Solution
A method is implemented where a higher proportion of hydrogen to diesel is injected during engine startup to expedite warming and reduce emissions, with the hydrogen-to-diesel ratio adjusted as the engine reaches idling speed to minimize unburned diesel release and mitigate engine knock, allowing for efficient startup and operation with lower compression ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a higher proportion of hydrogen to diesel is injected during engine startup, then combustion efficiency and engine warming are improved, but engine knock and unburned diesel release increase
Solution Approach 1:
The fuel mixture ratio is dynamically adjusted based on engine operating conditions. During startup, a higher hydrogen proportion is used to improve combustion efficiency and warming rate. As the engine warms up and reaches stable operating conditions, the ratio is adjusted to reduce hydrogen proportion and increase diesel proportion, thereby reducing engine knock and unburned diesel release while maintaining efficient operation.
Solution Approach 2:
The hydrogen-to-diesel fuel ratio parameter is changed based on engine temperature and operating state. At cold startup, a higher hydrogen proportion is injected to improve combustion efficiency and accelerate engine warming. As engine temperature increases and stable operation is achieved, the parameter is adjusted to optimize the mix for reduced emissions and minimized engine knock, balancing combustion efficiency with harmful factor reduction.
2Ease of manufacture
If the engine operates at lower compression ratios to accommodate hydrogen combustion, then ease of manufacture is improved, but combustion stability deteriorates
Solution Approach 1:
The compression ratio parameter is optimized for hydrogen combustion characteristics. Hydrogen requires lower compression ratios compared to diesel for stable combustion. The engine is designed with a compression ratio that accommodates hydrogen combustion stability, and the fuel injection system dynamically adjusts the hydrogen-to-diesel ratio to maintain stable combustion across different operating conditions, thereby achieving both ease of manufacture and combustion stability.
Solution Approach 2:
The fuel injection control system acts as an intermediary between the combustion chamber and the fuel sources. It dynamically mixes and controls the hydrogen and diesel fuels, adjusting their proportion based on operating conditions. This intermediary control allows the engine to operate stably at lower compression ratios by compensating for the reduced compression effect through optimized fuel mixture management, thus achieving both manufacturing simplicity and combustion stability.
3Reliability
If additional heating devices such as heaters and glow plugs are used during startup, then ignition reliability is improved, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the need for additional heating devices like heaters and glow plugs by using a chemical approach. Instead of relying on thermal assistance devices to aid ignition during cold startup, the system uses a chemically optimized hydrogen-diesel fuel mixture that facilitates self-ignition through controlled combustion chemistry, thereby improving ignition reliability while reducing device complexity.
Solution Approach 2:
The patent replaces the mechanical/thermal heating system (heaters and glow plugs) with a chemical combustion approach. By optimizing the fuel mixture composition and utilizing the combustion characteristics of hydrogen and diesel, the system achieves reliable ignition and combustion without requiring additional thermal assistance devices, thus reducing overall system complexity while maintaining or improving ignition reliability.
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 enables faster and more efficient engine startup with reduced emissions, as hydrogen's higher ignition temperature range and faster heat release properties enhance combustion efficiency, while decreasing the likelihood of engine knock and unburned diesel release.
Implementation Method 1
combustion of more than one type of fuel at an engine... Combustion parameters may vary according to a ratio of hydrogen to diesel injected at the engine... faster combustion and lower volumetric density of hydrogen relative to diesel may be leveraged to increase combustion efficiency
Data Source
AI summary
Various methods and systems are provided for engine startup. In one example, a method for an engine includes injecting a fuel mixture with a proportion of a first fuel to a second fuel to decrease carbon emissions, in response to detection of or request for the engine to start. The proportion of the first fuel to the second fuel in the injected fuel mixture is decreased in response to engine speed reaching an idling speed. The first fuel may be a non-hydrocarbon-based fuel and the second fuel may be a hydrocarbon-based fuel.