Exhaust Gas Recirculation Cooler with Flow Blocking Plate
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Solution Overview
Problem
Heat exchangers used to cool exhaust gases face performance degradation due to fouling, which is exacerbated by increased surface area density designs that reduce the Reynolds number, leading to higher fouling factors and reduced efficiency.
Innovation Solution
The design incorporates an exhaust gas flow conduit with arcuately shaped narrow sides and a convoluted fin structure, featuring a flow blocking plate that inhibits gas flow through larger channels, directing it through smaller channels with a reduced hydraulic diameter, thereby reducing fouling susceptibility and maintaining thermal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If surface area density is increased to improve heat exchanger performance, then heat transfer capability is improved, but Reynolds number decreases leading to increased fouling factor
Solution Approach 1:
The patent applies different channel geometries in different locations within the heat exchanger. Specifically, it uses channels with arcuately shaped narrow sides in regions where high heat transfer is needed, while maintaining larger hydraulic diameters in other areas to preserve Reynolds number and reduce fouling. This local differentiation allows the system to optimize heat transfer capability in specific zones without sacrificing overall fouling resistance.
2Productivity
If channel hydraulic diameter is reduced to increase surface area density, then heat transfer efficiency is improved, but fouling factor increases due to lower Reynolds number
Solution Approach 1:
The patent employs asymmetric channel cross-sections with arcuately shaped narrow sides rather than conventional symmetric circular or rectangular channels. This asymmetric geometry provides enhanced heat transfer surface area while maintaining favorable flow characteristics. The curved narrow sides create optimized flow patterns that help sustain Reynolds number despite reduced hydraulic diameter, thereby improving heat transfer efficiency without proportionally increasing fouling factor.
3Volume of moving object
If flow area is decreased to increase surface area density, then heat exchanger compactness is improved, but pressure drop increases due to flow constriction
Solution Approach 1:
The patent utilizes channels with arcuately shaped narrow sides, employing curved geometries throughout the flow path. These curved channels reduce flow separation and turbulence compared to sharp-cornered rectangular channels, thereby minimizing pressure drop. The curvature allows for more efficient flow guidance through compact spaces, achieving high surface area density and compactness while maintaining lower pressure losses.
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 solution effectively maintains heat exchanger performance in fouled conditions by minimizing flow redirection to smaller channels, reducing pressure drop, and preventing performance degradation, as demonstrated by improved test results showing sustained thermal performance and pressure drop consistency.
Implementation Method 1
The accumulation of particulate on the surfaces adds an additional resistance to the transfer of heat energy from the exhaust gas to the cooling fluid of the heat exchanger
Implementation Method 2
A fluid flowing through the exhaust gas flow conduit is substantially blocked from accessing the first and second flow channels by a plate located at one of an inlet and an outlet of the exhaust gas flow conduit
Data Source
AI summary
An exhaust gas recirculation cooler includes an inlet configured to receive exhaust gas from an engine, an outlet configured to direct the exhaust gas back toward the engine, and an exhaust gas flow conduit. The flow conduit includes a first end adjacent the inlet, a second end adjacent the outlet, a first narrow side, a second narrow side, substantially flat broad sides extending between the narrow sides, a first channel adjacent the first narrow side and extending between the ends, a second channel adjacent the second narrow side and extending between the ends, and a plurality of third channels located between the first and second channels and extending between the ends. A plate is located at one end of the flow conduit to inhibit the exhaust gas from flowing through at least one of the first channel and the second channel while allowing exhaust gas flow through the third channels.