Folded Double-Wall Heat Exchanger Tube for Refrigerant Containment

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Solution Overview

Problem

Conventional heat exchanger tubes in water heaters are prone to refrigerant leakage, which is undesirable and poses a technical challenge in maintaining efficient and reliable heating systems.

Innovation Solution

The development of a double-walled heat exchanger tube with an inner and outer wall formed by folding a single sheet of material, featuring a plurality of ridges at opposite ends that form flow channels to prevent refrigerant leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional single-walled heat exchanger tubes are used, then the device complexity is low, but refrigerant leakage occurs reducing reliability

Engineering Contradiction:

Improverefrigerant leakage preventionVSAvoidtube structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The heat exchanger tube is segmented into an inner wall and an outer wall, creating a double-walled structure. This segmentation allows the refrigerant to be contained within the inner wall while the outer wall provides an additional containment barrier, preventing refrigerant leakage into the water tank even if one wall is compromised.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The inner wall is nested within the outer wall, forming a concentric double-walled structure. The refrigerant flows through the inner wall while the annular space between the inner and outer walls provides a secondary containment zone, ensuring that refrigerant cannot leak into the water tank.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If a double-walled structure is implemented, then refrigerant leakage is prevented improving reliability, but the manufacturing process becomes more complex

Engineering Contradiction:

Improverefrigerant containmentVSAvoidmanufacturing process simplicity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The manufacturing process merges the formation of the inner wall and outer wall into a single integrated process. The tube is formed by simultaneously creating both walls and the flow channels between them, eliminating the need for separate manufacturing and assembly steps for the inner and outer walls.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single tube structure serves multiple functions: it provides refrigerant flow paths through the inner wall, contains refrigerant pressure, prevents refrigerant leakage into the water tank, and requires no additional sealing components or assembly steps between separate walls.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If conventional tubes are used, then the manufacturing process is simple, but heat exchange efficiency is reduced due to leakage

Engineering Contradiction:

Improveheating efficiencyVSAvoidrefrigerant loss

Core Design Contradiction:

ProductivityVSLoss of substance

Solution Approach 1:

The design accepts that the tube structure may be simpler and more economical to manufacture, even though it uses a double-walled configuration, because it eliminates the need for expensive refrigerant replacement and system repairs that would result from leakage in conventional single-walled tubes.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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

The double-walled design effectively prevents refrigerant leakage into the water tank, enhancing the reliability and efficiency of the water heating system while allowing for flexibility in material selection for the tube walls.

Implementation Method 1

The inner wall and the outer wall may be formed by folding a single sheet of material onto itself

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Implementation Method 2

the heat exchanger may be disposed inside the water tank and may be configured to transfer heat from the refrigerant to the water inside the water tank

Methodology Applied

Scientific EffectHeat transfer: Heat Exchanger

Data Source

PatentUS20250075981A1Folded Double Wall Heat Exchanger Tubes and Methods of Manufacture

Publication Date: 2025.03.06 RHEEM MFG CO

AI summary

A method of manufacturing a heat exchanger tube is disclosed. The method may include folding a single sheet of material onto itself to form a folded sheet of material and forming first and second pluralities of ridges on a first portion of the folded sheet and a second portion of the folded sheet. The method may further include folding the first portion about a first portion distal end to overlay on a third portion of the folded sheet, and the second portion about a second portion proximal end to overlay on a fourth portion of the folded sheet. Furthermore, the method may include folding the third inner portion about a third portion distal end to overlay on a fifth portion of the folded sheet and folding the fourth portion about a fourth portion proximal end to overlay on the fifth portion to form the heat exchanger tube.