Multi-Barrel EGR Mixer With Nested Nozzles for Low Pressure Drop
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Solution Overview
Problem
Existing exhaust gas recirculation (EGR) systems face challenges in maintaining efficient EGR performance across varying engine speeds, particularly at low speeds where additional EGR suction is needed, leading to increased pressure drop and efficiency penalties, and at high speeds where passive flow resistance occurs, causing retention of hot burned gases and knocking combustion.
Innovation Solution
The implementation of a multi-barrel exhaust gas recirculation mixer with nested multi-path nozzles and mixing passages that utilize concentric fluid paths to optimize EGR flow, incorporating a fuel nozzle for enhanced mixing, and controlled fluid ratios to manage EGR/AIR ratios and velocities, ensuring efficient operation across different engine speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reed valves and an EGR module are added to enhance EGR rate at low speeds, then EGR performance at low speeds is improved, but pressure drop across the EGR module increases during full power operation
Solution Approach 1:
The EGR system is segmented into multiple independent barrels (first barrel, second barrel, third barrel) with separate nozzles and flow paths. This allows each barrel to be optimized for different operating conditions, enabling low-speed EGR enhancement without excessive pressure drop at high power by selectively activating appropriate barrels.
Solution Approach 2:
The system employs variable geometry nozzles and controllable flow paths that can dynamically adjust their characteristics based on engine operating conditions. The nozzles are designed with adjustable opening areas that can respond to manifold pressure and flow requirements, optimizing EGR rate at low speeds while minimizing pressure drop at high power.
2Stress or pressure
If existing turbocharger area restriction creates pressure drop upstream of the turbine, then turbine inlet pressure is reduced at high engine speeds, but EGR flow can be driven by manifold absolute pressure
Solution Approach 1:
The multi-barrel mixer acts as an intermediary device that receives exhaust gas at high pressure from the turbocharger and conditions it through multiple nozzles and mixing passages before delivering it to the intake manifold. This intermediary structure allows the system to utilize the pressure differential created by the turbocharger's area restriction to drive EGR flow without requiring additional suction capability.
Solution Approach 2:
The system changes the pressure parameters of the exhaust gas stream through the multi-barrel mixer by utilizing the high pressure from the turbocharger outlet. The mixing passages and nozzles are designed to maintain adequate pressure differential to drive EGR flow even when manifold absolute pressure is insufficient, effectively using the turbocharger's pressure characteristics to overcome the area restriction limitation.
3Productivity
If EGR module provides passive flow resistance to drive EGR at peak torque at low engine speeds, then EGR flow is generated, but efficiency penalty occurs for engine performance
Solution Approach 1:
The multi-barrel mixer is designed to be self-regulating, utilizing the natural pressure differential between the exhaust manifold and intake manifold to drive EGR flow. The variable geometry nozzles and mixing passages automatically adjust to match engine operating conditions, eliminating the need for additional active flow resistance components that would cause efficiency penalties.
Solution Approach 2:
The system employs pneumatic principles by utilizing pressure differentials and flow dynamics to drive EGR flow. The multi-barrel mixer uses the pressure energy from the exhaust gas stream itself to create the necessary flow, rather than requiring additional mechanical or pneumatic resistance, thereby maintaining engine efficiency while achieving adequate EGR flow at peak torque.
4Productivity
If high AP across the engine prevents good breathing, then exhaust gas recirculation is reduced, but hot burned gas residuals are retained promoting knocking combustion
Solution Approach 1:
The EGR system is divided into multiple independent barrels that can operate simultaneously or individually. This segmentation allows the system to provide sufficient total EGR flow to prevent hot burned gas retention and knocking combustion while maintaining adequate breathing by distributing flow across multiple paths rather than relying on a single high-resistance path.
Solution Approach 2:
The system transitions from a single-dimensional EGR flow path to a multi-dimensional flow distribution system with multiple barrels and nozzles. This dimensional expansion allows the EGR flow to be distributed across multiple simultaneous paths, reducing the pressure drop in each individual path and improving overall breathing while maintaining sufficient recirculation to prevent knocking.
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 maintains optimal EGR performance by minimizing pressure drop, reducing pumping losses, and preventing hot-burned gas retention, thereby improving engine efficiency and reducing knocking combustion.
Implementation Method 1
Each multi-path nozzle generally includes an outer nozzle fluidically connected to the first fluid intake, and an inner nozzle fluidically connected to the second fluid intake. The inner nozzle is nested within the outer nozzle and projects into the throat of a corresponding and respective mixing passage.
Implementation Method 2
The exhaust gas recirculation mixer generally includes a plurality of mixing passages and a plurality of multi-path nozzles. Each mixing passage includes a corresponding and respective throat.
Implementation Method 3
incorporating a fuel nozzle for enhanced mixing
Data Source
AI summary
An exhaust gas recirculation mixer according to certain embodiments is operable to receive a first fluid via a first fluid intake and to receive a second fluid via a second fluid intake. One of the first fluid or the second fluid comprises air, and the other of the first fluid or the second fluid comprises exhaust gas. The exhaust gas recirculation mixer generally includes a plurality of mixing passages and a plurality of multi-path nozzles. Each mixing passage includes a corresponding and respective throat. Each multi-path nozzle generally includes an outer nozzle fluidically connected to the first fluid intake, and an inner nozzle fluidically connected to the second fluid intake. The inner nozzle is nested within the outer nozzle and projects into the throat of a corresponding and respective mixing passage.