Heat Exchanger Support Tubes for Thermoelectric Temperature Homogenization
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Solution Overview
Problem
Existing heat exchangers for internal combustion engine exhaust systems face inefficiencies due to temperature gradients within heating and cooling tubes, which affect the performance of thermoelectric generators, and require support structures to prevent tube indentation under pressure loading.
Innovation Solution
Incorporating geometrically different support tubes within the heating and cooling tubes to achieve specific flow routing and temperature homogenization, with features such as varying lengths, cross sections, and positions, and elastic deformation to absorb pressure and thermal stresses, while allowing fluid flow and improved heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the stack is loaded with a force of pressure to improve heat transfer between thermoelectric generators and tubes, then heat transfer efficiency is improved, but the tubes may become indented in their cross sections
Solution Approach 1:
A support tube is nested inside the heating tube or cooling tube to provide internal structural reinforcement. The support tube is positioned within the main tube to prevent indentation while allowing the stack to be loaded with compressive force for improved heat transfer between the thermoelectric generators and the tubes.
2Device complexity
If a single uniform support tube is used in the heating and cooling tubes, then the structure is simple, but the temperature distribution within the tubes remains non-uniform due to temperature gradients
Solution Approach 1:
The support structure is segmented into multiple support tubes with different geometries rather than using a single uniform support tube. These segmented support tubes are arranged at different positions within the heating and cooling tubes to address local temperature gradients and achieve more uniform temperature distribution across the tube cross-sections.
Solution Approach 2:
Different support tubes are provided with different local qualities in terms of their geometries (diameters, lengths, positions) to address specific local temperature gradient issues. Each support tube is optimized for its particular location within the heating or cooling tube to homogenize the temperature distribution in that specific region.
3Loss of energy
If multiple geometrically different support tubes are arranged in the heating and cooling tubes to homogenize temperature distribution, then thermoelectric conversion efficiency is improved, but the device complexity increases
Solution Approach 1:
Multiple support tubes with different local qualities (varying diameters, lengths, and positions) are arranged within the heating and cooling tubes to address specific local temperature gradient issues. This localized optimization of support tube geometries homogenizes the temperature distribution across different regions, improving the thermoelectric conversion efficiency of the generators.
Solution Approach 2:
The support structure is divided into multiple segmented support tubes rather than using a single uniform structure. This segmentation allows each support tube to be optimized for its specific position and function, enabling better temperature homogenization while maintaining a manageable overall structure that can be integrated into the heat exchanger design.
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 configuration enhances the efficiency of thermoelectric conversion by homogenizing temperature distribution across the tubes, improving energy recovery and maintaining structural integrity under pressure and thermal changes.
Implementation Method 1
A thermoelectric generator can convert a heat flux into an electric current or a temperature difference into an electric voltage by utilizing the so-called Seebeck effect.
Implementation Method 2
the support tube to have a round tube cross section and be elastically deformed by the force of pressure. In other words, the support tubes used in this embodiment act as springs in order to push the wall sections located opposite each other in the stacking direction within the respective cooling or heating tube towards the outside in order to generate an opposing force to the force of pressure acting on the stack hereby.
Data Source
AI summary
A heat exchanger (7) for an exhaust system (5) of an internal combustion engine (1), includes a heating tube (16) for carrying hot exhaust gas and a cooling tube (17) for carrying a liquid cooling agent. A thermoelectric generator (13) generates an electric voltage from a temperature difference and is arranged with the adjacent tubes in a stacking direction (18) to form a stack (21). A support tube (28) is supported in the stacking direction on wall sections (29) of the respective tube (16, 17), which wall sections mutually face each other, and is arranged in the respective heating tube (16) and/or cooling tube (17). Increased energy efficiency is achieved if at least two support tubes (28), which differ from one another by tube length and/or tube end (30) and/or by tube cross sections, are arranged in the respective tube (16, 17) at right angles to a longitudinal direction (31).