Two-Stroke Hydrogen Engine EGR Layout for Lower NOx
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Solution Overview
Problem
Existing internal combustion engines, particularly those designed for heavy-duty vehicles, face challenges in efficiently utilizing hydrogen fuel due to inadequate handling of exhaust gases, leading to gas exchange losses, high combustion temperatures, and increased emissions of NOx, which are not effectively addressed by conventional engine architectures.
Innovation Solution
A two-stroke ICE system integrated with an exhaust gas recirculation (EGR) system, featuring a dedicated EGR inlet control valve and positive displacement device, separates intake and exhaust ports, and includes an EGR cooler to manage exhaust gas recirculation, controlling combustion temperature and emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional internal combustion engines are adapted to use hydrogen fuel, then fossil fuel consumption is reduced, but gas exchange losses increase and combustion efficiency deteriorates
Solution Approach 1:
The patent divides the engine system into separate intake and exhaust pathways with dedicated control mechanisms. The intake system is segmented into fresh air intake and EGR gas intake through separate manifolds, allowing independent optimization of each flow path for hydrogen combustion efficiency.
Solution Approach 2:
The patent implements preliminary cooling of exhaust gases through an EGR cooler before recirculation, and pre-mixing of EGR gases with fresh air in the intake manifold. This preliminary preparation optimizes the combustion characteristics when hydrogen is introduced, improving combustion efficiency while maintaining reduced emissions.
2Object-generated harmful factors
If exhaust gas recirculation is implemented in two-stroke engines, then NOx emissions are reduced, but gas exchange losses increase
Solution Approach 1:
The patent introduces a positive displacement device as an intermediary component between the exhaust system and intake manifold. This device actively meters and controls EGR gas flow, ensuring optimal recirculation rates that reduce NOx emissions while minimizing energy losses through precise flow management rather than passive recirculation.
Solution Approach 2:
The patent dynamically adjusts EGR gas recirculation parameters including flow rate, temperature (through cooling), and timing using the positive displacement device and EGR control valve. By optimizing these parameters, the system achieves NOx reduction while minimizing the impact on gas exchange efficiency and overall engine performance.
3Measurement precision
If separate intake manifolds for fresh air and EGR gas are implemented, then combustion control is improved, but device complexity increases
Solution Approach 1:
The patent designs the separate intake manifolds to serve multiple functions: the fresh air manifold handles air intake and mixing, while the EGR manifold handles exhaust gas recirculation and mixing. Both manifolds work together in a unified system that maintains relatively simple overall architecture while achieving precise combustion control through their coordinated, multi-functional operation.
4Measurement precision
If positive displacement device is used for EGR gas metering, then EGR flow control precision is improved, but device complexity increases
Solution Approach 1:
The positive displacement device is designed to automatically meter EGR gas flow based on engine operating conditions without requiring complex external control systems. The device inherently provides precise flow control through its mechanical design, reducing the need for additional sensors, actuators, and control electronics, thereby achieving precise EGR control with minimal added complexity.
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 system reduces gas exchange losses, enhances combustion efficiency, and lowers emissions by precisely metering exhaust gases, reducing peak combustion temperatures, and improving thermal efficiency, thereby increasing engine performance and durability.
Implementation Method 1
an EGR cooler for regulating the temperature of the EGR gas
Implementation Method 2
a positive displacement device configured to direct EGR gas to the second intake manifold
Implementation Method 3
a reciprocating piston moveable in an axial direction within the cylinder between a bottom dead center BDC and a top dead center TDC
Implementation Method 4
a two-stroke ICE operable on a fuel... the at least one cylinder at least partly defining a combustion chamber
Data Source
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AI summary
The present disclosure relates to an internal combustion engine (ICE) system (10) for a vehicle (1), the ICE system comprising: a two-stroke ICE (20) operable on a fuel (50), the ICE having at least one cylinder (30) with a cylinder wall (30a) and further a reciprocating piston (31) moveable in an axial direction (A) within the cylinder between a bottom dead center (BDC) and a top dead center (TDC), the at least one cylinder at least partly defining a combustion chamber with a top end (33) of the piston; a first intake manifold (22) for receiving fresh air, the first intake manifold configured to be in fluid communication with a first intake port (35) arranged at a top end (36) of the at least one cylinder; an exhaust port (38) arranged axially distal from the top end of the at least one cylinder; a second intake manifold (86) configured to be in fluid connection with an exhaust gas recirculation (EGR) system (80), the second intake manifold further being configured to be in fluid communication with a second intake port (87) arranged at the top end of the at least one cylinder, the second intake port being configured to be in fluid communication with the combustion chamber, wherein the flow of gas through the second intake port is controllable by a controllable EGR control valve (88); the EGR system further having an EGR conduit (81) arranged to connect an exhaust duct (61) of the ICE system to the second intake manifold, wherein the EGR system further comprises a positive displacement device (82) configured to direct EGR gas to the second intake manifold, and an EGR cooler (89) for regulating the temperature of the EGR gas.