Selective Cylinder EGR Layout for Hydrogen Combustion Engines
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing internal combustion engines face challenges in managing high exhaust gas recirculation rates, particularly when using carbon-neutral fuels like hydrogen, leading to the need for larger and more complex EGR systems, which consume resources and increase assembly space.
Innovation Solution
An internal combustion engine design where exhaust gas recirculation is implemented only for a part of the piston-cylinder units, with exhaust ports of at least two units directly connected to the intake system, allowing exhaust gases to be pumped back efficiently, reducing the size of the exhaust and intake systems, and potentially incorporating a fuel injector to enrich the recirculated exhaust gas with hydrogen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If exhaust gas recirculation is implemented for all piston-cylinder units to reduce nitrogen oxide emissions, then emission reduction effectiveness is improved, but system size and complexity increase
Solution Approach 1:
The engine's piston-cylinder units are divided into two groups: a first number of units (e.g., 2 out of 3 or 4) have their exhaust ports connected to the intake system for EGR, while the remaining units discharge exhaust separately. This segmentation allows partial EGR implementation, reducing system complexity while maintaining emission reduction benefits through selective exhaust recirculation to control combustion peak temperatures.
2Object-affected harmful factors
If high exhaust gas recirculation rates are used with hydrogen combustion, then emission reduction is improved, but system size increases
Solution Approach 1:
By segmenting the exhaust system to handle only a portion of total exhaust flow for recirculation (from the first number of piston-cylinder units), the required EGR component sizes are reduced compared to systems that recirculate all exhaust. This allows high EGR rates for hydrogen combustion without proportionally increasing overall system volume.
Solution Approach 2:
Different parts of the exhaust system serve different functions: the EGR line handles recirculated exhaust from selected cylinders, while separate exhaust lines handle discharge from remaining cylinders. This local differentiation optimizes component sizing for their specific flow requirements rather than designing for maximum flow throughout the entire system.
3Productivity
If exhaust ports of multiple piston-cylinder units are connected to intake system for EGR, then EGR efficiency is improved, but intake system complexity increases
Solution Approach 1:
The exhaust ports from the first number of piston-cylinder units are merged into a common exhaust line that connects to the intake system, rather than requiring separate connections for each cylinder. This merging approach improves EGR efficiency by consolidating exhaust flow paths while reducing intake system complexity compared to individual cylinder connections.
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 design achieves a smaller footprint and more efficient exhaust gas recirculation, reducing the need for separate components and enabling stable combustion by enriching the intake mixture with hydrogen, thus maintaining delivery to piston-cylinder units while minimizing assembly space and complexity.
Implementation Method 1
supply exhaust gases to the air or air-fuel-mixture provided for combustion, wherein the recirculated exhaust gas amount increases specific heat capacity of the mixture in the combustion chamber, which lowers the combustion peak temperature
Implementation Method 2
potentially incorporating a fuel injector to enrich the recirculated exhaust gas with hydrogen
Implementation Method 3
at least three piston-cylinder-units for combusting an air-fuel mixture
Data Source
AI summary
An internal combustion engine includes at least three piston-cylinder-units for combusting an air-fuel mixture, wherein each piston-cylinder-unit comprises an intake port and an exhaust port. The engine further includes an intake system fluidically connected to each intake port of the at least three piston-cylinder-units for providing air or air-fuel mixture. The engine further includes an exhaust system for discharging exhaust gases of the combustion. The exhaust ports of at least two piston-cylinder-units are fluidically connected to the intake system to recirculate an exhaust gas into the combustion of the at least three piston-cylinder-units and the exhaust system is configured to entirely discharge exhaust gas from one or more remaining piston cylinder-units of the at least three piston-cylinder-units.