Hydrogen Four-Stroke Engine With Timed Water Injection for NOx Control
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Solution Overview
Problem
Substituting hydrocarbon fuels with hydrogen in four-stroke internal combustion engines is challenging due to hydrogen's unique properties, including high mass to energy ratio, high combustion velocity, wide flammability limits, low ignition energy, high auto-ignition temperature, and embrittling effect on metals, leading to increased NOx production and mechanical issues.
Innovation Solution
A four-stroke internal combustion engine design that injects hydrogen and water into the combustion chamber at specific timings during the compression stroke, using a spark or glow plug for ignition, to control combustion temperature and reduce NOx production, with an engine control unit managing the injection of hydrogen and water quantities and timings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If hydrogen is used as fuel to avoid carbon emissions, then environmental cleanliness is improved, but NOx production increases due to high combustion temperature
Solution Approach 1:
Water is introduced as an intermediary substance into the combustion chamber to mediate the combustion process. The water absorbs excess heat during combustion, acting as a thermal buffer that reduces peak combustion temperatures and thereby suppresses NOx formation, while allowing hydrogen combustion to proceed
Solution Approach 2:
The invention changes the thermal parameters of the combustion process by introducing water that absorbs heat and reduces combustion temperature. This parameter change (temperature reduction) directly addresses the NOx formation issue while maintaining the benefits of hydrogen combustion
2Object-generated harmful factors
If water is injected early during compression stroke to control temperature, then NOx production is reduced, but lubricant film integrity is compromised
Solution Approach 1:
Water is injected preliminarily during the compression stroke before combustion occurs. This preliminary action allows the water to be distributed and partially evaporated before the combustion event, preparing the combustion environment to control temperature while minimizing direct contact with lubricant during the critical combustion phase
Solution Approach 2:
The water injection is applied locally to specific regions of the combustion chamber where it can most effectively control combustion temperature without excessively impacting the lubricant film areas. The injection timing and positioning create local thermal management zones
3Ease of operation
If hydrogen is injected at multiple timings to control combustion, then combustion control is improved, but device complexity increases
Solution Approach 1:
The hydrogen injection process is segmented into multiple distinct phases: a first quantity injected at a first timing, a second quantity (water) injected at a second timing, and a third quantity of hydrogen injected at a third timing. This segmentation allows precise control of different aspects of combustion (ignition, temperature control, completeness) through separate injection events
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 engine operates efficiently with reduced NOx emissions and higher torque, allowing operation at lower lambda values and higher efficiencies without the need for complex exhaust gas recirculation systems, and maintains lubricant integrity by utilizing hydrogen's diffusivity to disperse water effectively.
Implementation Method 1
hydrogen's diffusivity to disperse water effectively
Implementation Method 2
injects a second quantity of (liquid or gaseous) water into the combustion chamber at a second timing from 110° to 90° before TDC during compression stroke
Implementation Method 3
a sparked reciprocating four-stroke internal combustion hydrogen-fueled engine
Implementation Method 4
The fuel-air mixture combustion produces a pressure on the piston head and pushes the piston downward
Data Source
AI summary
A sparked reciprocating four-stroke internal combustion hydrogen-fueled engine having a casing, a rotatable crankshaft, a cylinder inside the casing, a piston inside the cylinder to movably reciprocate along an axis between top and bottom dead center positions (TDC, BDC) and operatively connected to the crankshaft such that the piston imparts a rotational movement to the crankshaft, a combustion chamber within the cylinder between the engine casing and piston head opposite the crankshaft, intake and exhaust valves, hydrogen and water injectors; a spark or glow plug, and an engine control unit to control timing and quantity of hydrogen and water injections by injecting into the combustion chamber first, second, and third quantities of hydrogen at first, second, and third timings, respectively, from 20° before TDC during compression stroke to 20° after TDC, from 110° to 90° before TDC during compression stroke and from 180° to 100° before TDC during compression stroke.