Flat-Tube Heat Exchanger Fin Structure for Pressure Resistance

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Solution Overview

Problem

In heat-exchangers, the configuration of bonding two plates together to form tubular body parts results in increased weight due to thicker fins for pressure resistance and brazing filler metal penetrating into refrigerant passages, compromising performance and manufacturing ease.

Innovation Solution

A heat-exchanger design featuring plural flat-tube groups connected by a fin, where the fin is formed by bending a single plate-like part to fit around each flat tube, reducing fin thickness and weight while maintaining pressure resistance and improving heat-exchange performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If two plates are bonded together to form tubular body parts, then the structure provides pressure resistance, but the fin thickness must be increased leading to increased weight

Engineering Contradiction:
Improvepressure resistanceVSAvoidfin weight
Core Design Contradiction:
StrengthVSWeight of stationary object

Solution Approach 1:

The invention divides the heat exchanger into multiple tubular bodies arranged in parallel, each with its own fin structure. This segmentation allows each fin to be optimized independently for minimal thickness while maintaining pressure resistance through the tubular body design with inwardly directed flanges.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention transitions from a plate-bonded construction to a three-dimensional tubular structure with flanges that extend inward. This dimensional change allows the fin to be thinner while the tubular body provides the necessary pressure containment through its geometric form and flange reinforcement.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Strength

If two plates are bonded together using brazing filler metal, then the joints are strong, but the filler metal penetrates into the refrigerant passage

Engineering Contradiction:
Improvejoint strengthVSAvoidbrazing filler metal penetration
Core Design Contradiction:
StrengthVSObject-generated harmful factors

Solution Approach 1:

The invention eliminates the brazing process entirely by using mechanical interlocking through flanges that extend inward into the tubular body. This extraction of the harmful brazing step prevents filler metal penetration while maintaining joint strength through the mechanical flange structure.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the thermal-bonding mechanism of brazing with a mechanical interlocking system using flanges. This substitution eliminates the need for filler metal while providing equivalent or superior joint strength through precise mechanical engagement.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Strength

If tubular body parts are formed by bonding plates, then the structure is robust, but manufacturing complexity increases

Engineering Contradiction:
Improvestructural robustnessVSAvoidmanufacturing simplicity
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The flanges are formed as integral parts of the tubular bodies during the extrusion or forming process, before assembly. This preliminary action eliminates the need for separate bonding operations, reducing manufacturing complexity while maintaining structural robustness through the pre-formed interlocking geometry.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention merges the tubular body and fin into an integrated assembly where the flange is an inherent feature of the tubular body itself. This merging eliminates separate bonding steps and simplifies manufacturing by reducing the number of components and assembly operations required.

Inventive Principle:
Principle #5Merging (Combining)

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 pressure resistance, reduces fin weight, and simplifies manufacturing while maintaining high heat-exchange performance, making it suitable for refrigeration-cycle applications.

Implementation Method 1

heat transfer fins

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

heat-exchange performance

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 3

pressure resistance of the tubes through which refrigerant is passed

Methodology Applied
Scientific EffectPressure resistance: Pressure Increase

Data Source

PatentEP3845851B1Heat exchanger, heat exchanger unit, and refrigeration cycle device
Publication Date: 2023.03.01 MITSUBISHI ELECTRIC CORP
  • EP3845851B1 patent drawingFigure 1
  • EP3845851B1 patent drawingFigure 2
  • EP3845851B1 patent drawingFigure 3~4

AI summary

A heat-exchanger, a heat-exchanger unit, and a refrigeration-cycle apparatus are provided that allow for improved pressure resistance of tubes through which refrigerant passes, reduced weight of heat transfer fins, and easy manufacture. The heat-exchanger includes a first flat-tube group, a second flat-tube group, and a fin. The first flat-tube group includes plural flat tubes each having a pipe axis, and the flat tubes included in the first flat-tube group are arranged in such a manner that the pipe axes of the flat tubes included in the first flat-tube group are arranged in parallel to each other. One of the flat tubes included in the first flat-tube group is a first flat tube. The second flat-tube group is provided adjacent to the first flat-tube group, the second flat-tube group includes plural flat tubes each having a pipe axis, and the flat tubes included in the second flat-tube group are arranged in such a manner that the pipe axes of the flat tubes included in the second flat-tube group are arranged in parallel to each other. One of the flat tubes included in the second flat-tube group is a second flat tube. The fin is provided to the first flat-tube group and the second flat-tube group. The fin includes a first portion connecting an end of a longitudinal axis of the first flat tube in a section perpendicular to the pipe axis of the first flat tube and an end of a longitudinal axis of the second flat tube in a section perpendicular to the pipe axis of the second flat tube.