Sub-ambient EGR System Using Segmented Cooling and Energy Extraction
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Solution Overview
Problem
Existing exhaust gas recirculation (EGR) systems face limitations in cooling, circulation efficiency, and temperature management, necessitating innovative approaches to enhance their performance.
Innovation Solution
A system that provides a mixture of charge air and exhaust to an internal combustion engine intake at a sub-ambient temperature by utilizing a combination of EGR coolers, turbines, and expanders to cool and recirculate exhaust gases, while also using bypass valves and various power sources to optimize energy extraction and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional EGR systems are used, then exhaust gas recirculation is achieved, but cooling efficiency is insufficient and temperature management is poor
Solution Approach 1:
The EGR system is divided into multiple independent cooling stages: a first cooler that performs initial cooling of exhaust gas, and a second cooler that performs final cooling of the mixed charge air and exhaust gas. This segmentation allows each cooler to be optimized for its specific temperature range and function, improving overall cooling efficiency and temperature management.
Solution Approach 2:
The first cooler performs preliminary cooling of the exhaust gas before it is mixed with charge air. By pre-cooling the exhaust gas, the thermal load on the second cooler is reduced, and the mixing process occurs with gases at more favorable temperatures, enhancing the overall cooling effectiveness and enabling sub-ambient temperature achievement.
2Productivity
If exhaust gas is recirculated without optimized cooling, then circulation is achieved, but energy efficiency is reduced
Solution Approach 1:
The system merges the cooling functions of two separate coolers and combines the flow paths of charge air and cooled exhaust gas. This integration allows heat exchange between the charge air and exhaust gas streams, recovering thermal energy that would otherwise be wasted, thereby improving circulation efficiency while reducing overall energy consumption.
Solution Approach 2:
The system changes the temperature parameter of the exhaust gas through staged cooling, transforming it from a high-temperature waste stream into a controlled, sub-ambient temperature recirculated charge. This parameter transformation improves the thermodynamic efficiency of the recirculation process and reduces the energy required for subsequent intake charging.
3Temperature
If simple cooling methods are used, then system complexity is low, but temperature control precision is insufficient
Solution Approach 1:
The cooling system is segmented into two distinct coolers with separate cooling circuits, allowing independent control and optimization of each cooling stage. This segmentation enables precise temperature control at different points in the process without requiring a single complex cooling system, as each cooler can be sized and controlled for its specific function.
Solution Approach 2:
The first cooler acts as an intermediary device that prepares the exhaust gas for mixing by achieving a target temperature before combination with charge air. This intermediary cooling stage simplifies the overall control system by creating a well-defined intermediate state, making the temperature control of the final mixture more predictable and easier to manage.
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 effectively cools the charge air and exhaust to sub-ambient temperatures, improving engine efficiency and emissions control by providing a more efficient mixture for intake, potentially reducing energy consumption and enhancing engine performance.
Implementation Method 1
utilizing a combination of EGR coolers, turbines, and expanders to cool and recirculate exhaust gases
Implementation Method 2
utilizing a combination of EGR coolers, turbines, and expanders to cool and recirculate exhaust gases
Data Source
AI summary
One embodiment is a unique system which is operable to provide a mixture of charge air and exhaust to an internal combustion intake at a sub-ambient temperature. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings.