Motor Vehicle Heat Exchanger Header Tank Thermal Shock Mitigation
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Solution Overview
Problem
Heat exchangers with a bundle of tubes between two header boxes face issues with thermal shock due to temperature differences, leading to stress and potential leaks or rupture at the interface zone between the two passes, with existing solutions either complicating manufacturing or reducing thermal performance.
Innovation Solution
A heat exchanger design where the header box is divided into compartments by a transverse partition with a seal that partially closes at least one tube near the partition, reducing fluid flow and temperature difference, and using ribs to apply pressure on the seal, thereby reducing thermal shock and maintaining heat exchange efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the header box is divided into two compartments by a transverse partition, then thermal shock between the two parts of the bundle is reduced, but the device complexity increases due to additional elements required for reinforcement
Solution Approach 1:
A thermal barrier element is introduced as an intermediary between the hot and cold parts of the tube bundle. This element acts as a mediator that reduces thermal shock at the interface zone without requiring complex reinforcement structures. The thermal barrier absorbs and redistributes thermal energy, protecting the tubes in the interface zone from extreme temperature variations.
Solution Approach 2:
The transverse partition is designed with non-uniform properties - it provides full thermal separation in regions where tubes are present, while allowing thermal communication in regions without tubes. This local differentiation of thermal properties reduces thermal shock where needed without unnecessarily complicating the overall structure.
2Reliability
If an inactive tube forming a thermal barrier is used to separate the two parts, then thermal shock is reduced, but the thermal performance is significantly penalized
Solution Approach 1:
The thermal barrier is implemented locally only in the interface zone where thermal shock occurs, rather than throughout the entire header box. This localized approach protects vulnerable tubes from thermal shock while maintaining efficient heat exchange in the majority of the tube bundle where thermal barrier would not be needed.
Solution Approach 2:
Instead of using a complete inactive tube that would fully block thermal flow, a partial thermal barrier is implemented that provides sufficient protection against thermal shock while allowing adequate thermal communication to maintain overall heat exchange performance.
3Reliability
If reinforcement elements are inserted inside the tubes, then thermal shock resistance is improved, but the manufacturing complexity increases
Solution Approach 1:
The thermal barrier serves as an intermediary structure that protects tubes from thermal shock without requiring internal reinforcement elements. This external protection approach simplifies manufacturing compared to inserting complex internal reinforcement structures into each tube.
Solution Approach 2:
The thermal barrier function is merged with the transverse partition structure, combining two functions (thermal separation and structural support) into a single integrated component. This reduces the total number of parts and simplifies manufacturing compared to separate reinforcement elements for each tube.
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 reduces the risk of leaks and rupture while maintaining thermal performance by partially blocking tubes near the partition, minimizing thermal shock and ensuring effective heat exchange.
Implementation Method 1
the tubes of the first pass and the tubes of the second pass undergo a different expansion generating stresses at the level of the tubes, in particular of their openings at the level of contact with the collector plate. These constraints are all the greater with regard to the tubes located in the interface zone between the two passes. These undergo a greater thermal shock
Implementation Method 2
the tubes of the first pass and the tubes of the second pass undergo a different expansion generating stresses at the level of the tubes
Data Source
Figure 1~2c
Figure 3a~3b
Figure 4a~4c
AI summary
The invention relates to a heat exchanger (1), notably for a motor vehicle, comprising a header tank (9a) and a bundle of tubes, the said header tank (9a) comprising a collector plate (21), a cover (23) and a seal located between the collector plate (21) and the cover (23), the said header tank (9a) being divided into two compartments (15a and 15b) by a transverse partition (17), the said compartments (15a and 15b) being configured to communicate respectively with two parts of the bundle, the said seal isolating the said compartments (15a and 15b) from one another and partially closing off the opening of at least one tube, referred to as the partially-closed tube (51), opening into the said header tank (9a) near the said transverse partition (17).