Dual EGR Cooler System Thermal Gradient Management
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Solution Overview
Problem
Internal combustion engines face challenges in managing the thermal gradient across EGR coolers, leading to performance issues and degradation due to high exhaust gas temperatures and lower coolant temperatures, which existing configurations struggle to effectively mitigate.
Innovation Solution
The implementation of a dual EGR cooler system where the first cooler pre-cools the EGR using a higher temperature fluid, such as exhaust gas from downstream of a turbine, and the second cooler uses a lower temperature fluid, like liquid coolant, to split the temperature reduction and reduce the thermal gradient on each cooler.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single EGR cooler is used with high-temperature exhaust gas and low-temperature coolant, then the EGR can be cooled effectively, but the thermal gradient across the cooler becomes large leading to performance degradation
Solution Approach 1:
The EGR cooling process is divided into two separate stages using two distinct coolers. The first EGR cooler performs initial cooling of the high-temperature exhaust gas, while the second EGR cooler performs final cooling before the EGR enters the intake manifold. This segmentation reduces the thermal gradient across each individual cooler, preventing performance degradation and extending component lifespan.
Solution Approach 2:
The first EGR cooler acts as an intermediary component between the high-temperature exhaust gas source and the second EGR cooler. It pre-cools the exhaust gas using a first coolant, creating a temperature buffer that reduces the thermal shock and gradient experienced by the second cooler, thereby protecting both components from excessive thermal stress.
2Device complexity
If a single EGR cooler is used, then the system structure is simple, but the thermal load on the cooler is high causing stress and degradation
Solution Approach 1:
The EGR cooling function is segmented into two separate cooling stages with two distinct coolers. Each cooler handles a portion of the total temperature reduction, distributing the thermal load and mechanical stress across two components rather than concentrating it all in one cooler, thereby improving overall system durability.
Solution Approach 2:
The first EGR cooler provides beforehand cushioning by pre-cooling the exhaust gas before it reaches the second cooler. This reduces the thermal shock and peak thermal loads that the second cooler would otherwise experience, protecting both coolers from excessive stress and extending their operational life.
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 approach reduces the thermal load on EGR coolers, prolonging their lifespan and maintaining engine efficiency by lowering the temperature of the EGR before it enters the second cooler, thereby minimizing stress and degradation.
Implementation Method 1
The first EGR cooler is configured to cool EGR with a first fluid
Implementation Method 2
the second EGR cooler is configured to cool EGR with a second fluid
Data Source
AI summary
Various systems and methods are provided for exhaust gas recirculation, including an exhaust gas recirculation (EGR) system includes an EGR passage coupling an engine exhaust system to an engine intake system, a first EGR cooler positioned in the EGR passage, the first EGR cooler configured to cool EGR with a first fluid, and a second EGR cooler positioned in the EGR passage downstream of the first EGR cooler, the second EGR cooler configured to cool EGR with a second fluid.