Heat Exchanger Headers with Segmented Flow Paths
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Solution Overview
Problem
Conventional heat exchangers face challenges in improving pressure-resistant strength while minimizing refrigerant pressure loss, particularly when high-pressure refrigerants like CO2 are used, as reducing header diameter affects heat exchanger performance and increasing it compromises pressure-resistant strength.
Innovation Solution
The heat exchanger design features headers extending in an up-and-down direction with flat tubes connected at different heights, utilizing a separate flat tube holding member and intermediate flow paths to circulate refrigerant without inserting tubes into the main flow path, allowing for reduced main flow path diameter and enhanced pressure-resistant strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the diameter of the headers is reduced to improve pressure-resistant strength, then the pressure-resistant strength is improved, but the width of the flat tubes is reduced which impacts heat exchanger performance
Solution Approach 1:
The header is divided into two functional parts: a main flow path portion with reduced diameter for high pressure resistance, and connection portions with larger diameter that accommodate the flat tubes. This segmentation allows each part to be optimized for its specific function without compromising the other.
Solution Approach 2:
The connection function for flat tubes is extracted from the main flow path. Instead of the main flow path serving both as high-pressure conduit and tube accommodation, a separate connection portion is provided that extends from the main flow path to the flat tube insertion positions, allowing the main flow path diameter to be minimized for pressure resistance.
2Productivity
If the diameter of the headers is increased to maintain flat tube width, then heat exchanger performance is maintained, but the pressure-resistant strength cannot be improved
Solution Approach 1:
The header structure is segmented into a narrow main flow path for pressure resistance and wider connection portions for tube accommodation, eliminating the need to increase the entire header diameter.
Solution Approach 2:
Different parts of the header have different diameters optimized for their local functions: the main flow path has small diameter for pressure resistance, while the connection portions have larger diameter to match flat tube widths for optimal heat exchange performance.
3Ease of manufacture
If flat tubes are inserted into the inside space of the headers through which refrigerant mainly travels, then connection is achieved, but pressure loss of the refrigerant occurs inside the headers
Solution Approach 1:
The refrigerant flow path is extracted and separated from the tube insertion space. The main flow path provides a clear, obstruction-free route for refrigerant, while connection portions provide separate access points to flat tubes without interfering with the main flow.
Solution Approach 2:
Connection portions act as intermediaries between the main flow path and flat tubes. Refrigerant flows through the main flow path without obstruction, then transitions through connection portions to reach flat tubes, minimizing pressure loss while achieving proper connection.
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 effectively suppresses refrigerant pressure loss and improves pressure-resistant strength by allowing the main flow path diameter to be smaller than the flat tubes, facilitating easier tube positioning and securing, while maintaining high flow dividing ability.
Implementation Method 1
heat exchange between refrigerant flowing through plural holes formed in the flat tubes and air flowing outside the flat tubes
Implementation Method 2
air flowing outside the flat tubes in a width direction (transverse direction) of the flat tubes
Implementation Method 3
refrigerant flows through it
Data Source
Figure 1
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Figure 3
AI summary
The provision of a heat exchanger that can achieve both improving the pressure-resistant strength of headers and suppressing pressure loss of refrigerant. A heat exchanger is equipped with a pair of headers and plural flat tubes (11a to 11f). Each of the headers has a first member (131) and a flat tube holding member (132) to which end portions of the flat tubes (11a to 11f) are adhered and which holds the flat tubes (11a to 11f). The first member (131) has formed therein a refrigerant main flow path (131a), which extends in an up-and-down direction and through which refrigerant flows, and refrigerant connection flow paths (231 a to 231f), which extend from the refrigerant main flow path (131a) to an end surface in the direction in which the flat tubes (11a to 11f) are positioned in order to circulate the refrigerant between the refrigerant main flow path (131a) and plural refrigerant flow paths formed in the flat tubes (11a to 11f). Intermediate flow paths (133a to 133f) that interconnect the refrigerant connection flow paths (231a to 231f) and the plural refrigerant flow paths in the flat tubes (11a to 11f) are formed in the headers and/or the flat tubes (11a to 11f).