Heat Exchanger Tube Group Stacking for Weight and Pressure Loss
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Solution Overview
Problem
Conventional heat exchangers face challenges in optimizing the number of tube groups to achieve maximum heat exchange performance within limited dimensions, leading to issues with weight, pressure resistance, and heat exchange efficiency, especially when using carbon dioxide as a refrigerant.
Innovation Solution
A heat exchanger design with three cylindrical headers and three tube groups arranged in the air flow direction, where the width dimension of the tubes and flow channel cross-sectional area are optimized to ensure an optimal number of arrays, improving endothermic capacity and reducing weight while securing sufficient refrigerant flow rate and pressure resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of tube groups is increased to increase heat exchange area, then the heat exchange amount increases, but the width dimension of each tube becomes small, the flow channel cross-sectional area per tube is reduced, and the pressure loss becomes large
Solution Approach 1:
The patent transitions from a two-dimensional arrangement (increasing tube groups in plan view) to a three-dimensional arrangement by stacking tube groups vertically between upper and lower headers. This vertical stacking allows multiple tube groups to be arranged in the height direction, increasing heat exchange area without reducing tube dimensions or increasing pressure loss in the horizontal plane.
Solution Approach 2:
The heat exchanger is divided into multiple tube groups that are stacked vertically, with each tube group having its own headers. This segmentation allows the system to achieve large total heat exchange area while maintaining adequate tube dimensions in each group, as the vertical arrangement distributes the tube groups across different height levels rather than compressing them horizontally.
2Productivity
If the number of tube groups is increased to increase heat exchange area, then the heat exchange amount increases, but the outer diameter of the headers increases, reducing the length of each tube and the flow area of external air
Solution Approach 1:
Instead of expanding headers horizontally to accommodate more tube groups, the patent stacks tube groups vertically between upper and lower headers. This vertical arrangement allows multiple tube groups to be connected to the same pair of headers without increasing header outer diameter, thereby maintaining adequate tube length and external air flow area.
3Strength
If the wall thickness of headers is increased to obtain pressure resistance for carbon dioxide refrigerant, then the pressure resistance increases, but the weight increases and workability reduces
Solution Approach 1:
The patent optimizes the wall thickness parameter of headers to achieve the minimum required pressure resistance for carbon dioxide refrigerant without excessive thickness. By carefully selecting and controlling the wall thickness parameter, the design achieves adequate strength while minimizing weight and maintaining workability.
4Device complexity
If all tubes of multiple tube groups are connected in single headers, then the structure is simplified, but the width in the front and back direction becomes large, causing condensed water accumulation and freezing
Solution Approach 1:
The patent arranges tube groups vertically between upper and lower headers, which distributes the structure in the height direction rather than expanding it in the front-back direction. This vertical stacking prevents condensed water from accumulating on a large horizontal surface area, reducing the risk of freezing, while still connecting all tubes through the header system.
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 allows for a lightweight, high-performance heat exchanger that maintains optimal performance even under size restrictions, particularly beneficial for vehicle air conditioning applications.
Implementation Method 1
a heat exchanger exchanging heat of air flowing through a core section formed by the tube groups and heat of a heating medium flowing through a plurality of heating medium flow holes forming flow channels in each of the tubes
Data Source
AI summary
Problem to be SolvedTo provide a heat exchanger that can increase the performance by setting an optimal number of tube groups in a configuration where each of the tube groups is provided with headers.SolutionThe number of arrays of tube groups of a core section 2 is set to three rows. The number N of heating medium flow holes 21 per tube is set for each width dimension Tw of tubes 20, and the tubes 20 are formed such that the width dimension Tw of the tubes and a flow channel cross-sectional area S satisfy a relationship of S1≤S≤S2. Therefore, the number of arrays of the tube groups in the core section 2 can be set to an optimal number of arrays for improving the endothermic capacity and reducing the weight, and sufficient refrigerant flow rate and pressure resistance can be secured. As a result, even when there is a restriction on the size of the entire heat exchanger, a light high-performance heat exchanger can be configured. This is significantly advantageous when the heat exchanger is used as an evaporator of a vehicle air conditioning apparatus for which a reduction in the weight of the components and an increase in the performance are demanded.