Bitumen-Filled Wire Tube Heat Exchanger for Stable Thermal Contact

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Solution Overview

Problem

Existing wire tube heat exchangers in refrigeration appliances face inefficiencies due to thermal ballast issues from pliable energy storage bags, which can leak or collapse, affecting heat exchange efficiency regardless of installation position and are difficult to manufacture.

Innovation Solution

A wire tube heat exchanger with two layers of wires and a refrigerant tube, where bitumen is used to ensure close thermal contact and is heated to adhere to the wires and tube, providing a solid and effective energy storage medium that maintains contact without leakage risks, with protruding ribs for enhanced heat exchange and a flexible cushion for pressing bitumen through gaps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If pliable bags are used to accommodate the energy storage medium, then close thermal contact between the wires/refrigerant line and the energy storage medium can be ensured, but there is a high risk of the bags leaking if improperly handled

Engineering Contradiction:
Improvethermal contact reliabilityVSAvoidleakage risk
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the physical state of the energy storage medium from liquid (in bags) to solid (bitumen). This parameter change eliminates the leakage risk inherent in liquid-filled bags while maintaining thermal contact through the molding process that forms bitumen around the wires and refrigerant line.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the reusable but fragile plastic bags with a solid bitumen material that is molded directly into the heat exchanger structure. This eliminates the need for separate containment bags and their associated leakage risks.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Ease of operation

If pliable bags are used for energy storage, then they are well suited for horizontal installation, but in vertical installation position the bags collapse and limit their effectiveness

Engineering Contradiction:
Improveinstallation adaptabilityVSAvoidheat exchange effectiveness
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent changes the energy storage medium from liquid-filled bags to solid bitumen. This parameter change provides structural support that prevents collapse under gravity in vertical installations while maintaining thermal contact through the molding process.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite structure where bitumen is molded around the wires and refrigerant line, forming an integrated heat exchanger assembly. This composite construction provides both structural integrity for vertical installation and optimal thermal contact.

Inventive Principle:
Principle #40Composite materials

3Reliability

If bitumen is used to fill the intermediate space, then close thermal contact is guaranteed and leakage risk is eliminated, but the bitumen layer is vulnerable to damage

Engineering Contradiction:
Improvethermal contact stabilityVSAvoidbitumen layer protection
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent merges the bitumen layer with the wire structure by molding the bitumen directly around the wires and refrigerant line. This integration creates a unified structure where the wires provide structural support to the bitumen layer, protecting it from damage while maintaining thermal contact.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent nests the bitumen within the structure formed by the two layers of wires and refrigerant line. This nesting arrangement provides mechanical protection to the bitumen layer while allowing it to maintain close thermal contact with all heat exchange surfaces.

Inventive Principle:
Principle #7Nested doll (Nesting)

4Reliability

If the bitumen is pressed through the gaps between wires to ensure thermal contact, then intensive heat exchange is achieved, but the manufacturing process becomes more complex

Engineering Contradiction:
Improvethermal contact intensityVSAvoidmanufacturing process simplicity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent performs the bitumen pressing action during the initial molding process, before final assembly. The bitumen is heated and pressed through the wire gaps as part of the formation process, creating permanent thermal contact channels that eliminate the need for separate pressing operations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses temperature as a parameter to facilitate the pressing process. By heating the bitumen to a plastic state, it becomes flowable and can be pressed through the wire gaps more easily, reducing the required pressing force and simplifying manufacturing.

Inventive Principle:
Principle #35Parameter changes

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 solution ensures efficient heat exchange regardless of installation position, reduces the risk of damage, and enhances energy storage capacity while maintaining operational efficiency by extending compressor operating phases without increasing total operating time.

Implementation Method 1

Bitumen can be easily made plastic by heating, so that it can cling to any contour of the wires or the refrigerant tube

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 2

an intensive heat exchange between the wires or the refrigerant pipe on the one hand and the bitumen on the other hand is possible

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP2556319B1Wire tube heat exchanger, method for producing same, and refrigeration device using same
Publication Date: 2014.03.05 BSH HAUSGERATE GMBH
  • EP2556319B1 patent drawingFigure 1~2
  • EP2556319B1 patent drawingFigure 3~5
  • EP2556319B1 patent drawingFigure 6

AI summary

The invention relates to a wire tube heat exchanger, in particular for a household refrigerator, comprising two layers (2; 3) of wires (2a, 2b, ...; 3a, 3b, ...) and a coolant tube (5) extending in an intermediate space (4) between the layers (2; 3). The intermediate space (4) is at least partially filled with bitumen (6). The bitumen (6) is heated and pressed through the gaps between the wires (2a, 2b, ...) into the intermediate space (4).