Heat Exchanger Collar Design for Thermal Stress Reduction
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Solution Overview
Problem
Heat exchangers in mobile applications face durability issues due to stochastic pressure and temperature changes, leading to mechanical stress and thermal cycling, which causes inhomogeneous temperature distribution and distortion, particularly at the tube sheet connections, resulting in reduced service life and challenges in automated production.
Innovation Solution
The design incorporates a collar with sections on all sides, featuring a transverse shoulder contour that creates a predominant wall cross-section difference between the section near the ground and the end section, allowing for a sufficient contact surface and increased strength while enabling easy bending, thus resolving the conflict between insertion bevel size and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the collar is made thinner to improve thermal shock resistance, then thermal cycling durability is improved, but the contact surface between tube and base is reduced leading to loss of strength
Solution Approach 1:
The collar is segmented into two distinct sections: a first section with greater wall thickness for strength and a second section with smaller wall thickness for thermal shock resistance. This segmentation allows each section to fulfill its specific functional requirement independently.
Solution Approach 2:
Different wall thicknesses are applied to different sections of the collar based on local requirements. The first section near the base has greater thickness for structural strength and contact surface, while the second section at the end has smaller thickness for thermal cycling durability.
2Ease of manufacture
If a larger insertion bevel is provided to improve process reliability for automated production, then manufacturing reliability is improved, but the collar material thickness must be increased which reduces thermal shock resistance
Solution Approach 1:
The collar structure is divided into sections with different wall thicknesses, allowing the first section to provide sufficient material for a large insertion bevel (improving manufacturing reliability) while the second section maintains thin walls for thermal shock resistance.
Solution Approach 2:
The collar has non-uniform wall thickness distributed locally: thicker at the base section to accommodate large insertion bevels for reliable automated tube insertion, and thinner at the end section to maintain thermal shock resistance.
3Ease of manufacture
If the collar is bent outward to provide insertion bevel, then manufacturing ease is improved, but the contact surface between tube and base is strongly reduced leading to strength loss
Solution Approach 1:
The collar is segmented into a first section that maintains sufficient wall thickness for contact surface and a second section that is bent to form the insertion bevel, preventing strength loss while enabling easy manufacture.
Solution Approach 2:
The bending to form insertion bevel is localized to the second section of the collar, while the first section near the base maintains its original geometry and sufficient wall thickness to preserve contact surface area and strength.
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 design enhances the durability and manufacturing reliability of heat exchangers by providing a stronger tube-plate connection with a larger insertion bevel, reducing stress concentrations and improving process reliability, while maintaining flexibility for thermal cycling.
Implementation Method 1
a heat exchanger is exposed to a particularly high stochastic pressure and temperature change stress... inhomogeneous temperature distribution within the block with a directly associated, inhomogeneous distribution of thermal expansion
Implementation Method 2
a so-called cooling network consisting of an alternating arrangement of tubes and heat-transferring corrugated fins
Implementation Method 3
Heat exchanger for exchanging heat between a first fluid, in particular a charge air or an exhaust gas, and a second fluid, in particular a coolant
Data Source
Figure 1A~1B
Figure 2
Figure 3A~4B
AI summary
A heat exchanger (10) for heat exchange between a first fluid, in particular charge air or exhaust gas, and a second fluid, in particular a coolant, is described, comprising: a block for the separate and heat-exchanging guidance of the first and second fluids, the block having a number of flow channels through which the first fluid can flow; at least one box (3) associated with the block, which is flow-connected to the flow channels; and at least one base (1) which is provided with one or more through-openings for the passage of the flow channels between the block and the box (3); wherein at least one through-opening is formed as a passage (17) with a collar (7).The invention provides that the collar (7) has a lower section (23) and an end section (25), wherein a wall cross-section (d) of the end section (25) is smaller than a wall cross-section (D) of the lower section (23), and at least one step (27, 28) is arranged between the lower and the end section (23, 25), the step having a step contour (29) extending transversely to the contour (33, 35) of the lower section (23) and/or the end section (25), and wherein the end section (25) is inclined away from a through axis (37). A use and a manufacturing method are also described.