Finned Coaxial Cooler for EGR Systems
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Solution Overview
Problem
Existing coaxial heat exchangers with corrugated designs suffer from low heat exchange efficiency per unit length, high gas pressure loss, and excessive coolant boiling, which can damage components and hinder engine performance in EGR systems.
Innovation Solution
A coaxial heat exchanger design featuring a heat exchange tube with internal fins that increase heat transfer without significantly raising gas pressure drop, using a combination of straight and bent sections with smooth and corrugated surfaces to optimize heat exchange and minimize boiling, and employing a fin structure that promotes efficient heat transfer while maintaining low pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If corrugated heat exchange tube is used, then heat exchange surface area is increased, but gas pressure loss increases due to turbulence
Solution Approach 1:
The patent applies local quality by using smooth sections of the heat exchange tube where gas flow is critical to minimize pressure loss, and corrugated sections where heat exchange is needed. The finned sections are strategically placed to enhance heat transfer without creating excessive turbulence in the gas flow path, thus locally optimizing both heat exchange efficiency and pressure drop characteristics.
2Area of stationary object
If corrugated heat exchange tube is used, then heat exchange surface area is increased, but heat exchange per unit length remains low
Solution Approach 1:
The patent employs fins extending radially from the heat exchange tube surface, adding a dimensional element that significantly increases the heat exchange surface area without extending the axial length of the heat exchanger. This allows more heat transfer surface to be packed into a compact unit length, directly addressing the low heat exchange per unit length problem.
3Length of moving object
If compact design is used to reduce length, then space is saved, but heat exchange efficiency per unit length decreases
Solution Approach 1:
By adding fins that extend in the radial dimension, the patent increases the heat exchange surface area without increasing the axial length of the cooler. This allows the heat exchanger to maintain a compact length while achieving high heat exchange efficiency per unit length through the enhanced surface area provided by the finned structure.
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 design enhances heat exchange efficiency per unit length while reducing gas pressure drop and coolant boiling, thereby improving the performance and reliability of EGR systems by effectively cooling hot gases without causing damage from excessive boiling.
Implementation Method 1
The fins may act to increase heat exchange between the gas and the liquid coolant by transferring heat from the centre of the gas flow to the inner walls of the heat exchange tube
Implementation Method 2
a heat exchange tube for exchanging heat between the gas and the liquid coolant; wherein the gas flows through a passage in the heat exchange tube and the liquid coolant flows between the heat exchange tube and the tubular outer body
Data Source
AI summary
A heat exchanger (100) for an exhaust gas recirculation system includes one or more rigid tubes (103), each having one or more internal cooling fins (111) that act as heat exchange surfaces to transfer heat from a gas to the walls of the rigid tubes. The rigid tubes are cooled by a liquid coolant contained within an outer jacket (113) surrounding the tubes. The rigid tubes may be straight and smooth, and may be alternated with one or more bellows sections (108, 104) which provide flexibility to the heat exchanger.