Heat Exchange Plate Ridge Layout for Thermal Stress Control

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Solution Overview

Problem

Existing heat exchange arrangements in gas-fired hot water heaters and burners face thermal stress, leakage, and efficiency issues due to high temperature variations and scaling, which prior art has not adequately addressed.

Innovation Solution

A heat exchange plate design with a protrusion forming a ridge that divides the heat transfer surface into two regions, allowing for efficient internal flow of the first medium through a transfer channel, optimizing cooling of the second medium and heating of the first medium without external channels, thereby managing thermal stresses and improving compactness and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If high temperature gas is used for heating, then heating efficiency is improved, but thermal stress and leakage risk increase

Engineering Contradiction:
Improveheating efficiencyVSAvoidthermal stress and leakage risk
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The plate is divided into different temperature zones with varying thickness. The first region near the gas inlet has greater thickness to withstand high thermal stress, while the second region has reduced thickness for compactness. This local variation in geometric properties allows the plate to handle high temperature gas efficiently while maintaining reliability through stress distribution.

Inventive Principle:
Principle #3Local quality

2Reliability

If metal surface temperature is reduced to prevent boiling, then safety is improved, but heat exchange efficiency decreases

Engineering Contradiction:
Improveboiling prevention safetyVSAvoidheat exchange efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The heat transfer surface is segmented into multiple regions with different functions. The first region handles high-temperature gas cooling with thicker plate structure, while the second region optimizes for efficient heat transfer to water with reduced thickness. This segmentation allows different parts of the plate to operate at optimal temperatures for their specific functions, preventing boiling while maintaining overall heat exchange efficiency.

Inventive Principle:
Principle #1Segmentation

3Volume of moving object

If plate thickness is reduced for compactness, then device size is improved, but thermal stress resistance decreases

Engineering Contradiction:
Improvedevice compactnessVSAvoidthermal stress resistance
Core Design Contradiction:
Volume of moving objectVSStrength

Solution Approach 1:

The plate implements local quality variation through region-specific thickness optimization. The first region near the high-temperature gas inlet maintains greater thickness to provide sufficient thermal stress resistance, while the second region has reduced thickness to achieve device compactness. This localized geometric optimization allows the plate to be both compact and strong where needed.

Inventive Principle:
Principle #3Local quality

4Productivity

If water flow path is extended for efficient heating, then heat exchange efficiency is improved, but device complexity increases

Engineering Contradiction:
Improveheat exchange efficiencyVSAvoidflow channel structure
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The plate merges multiple functions into a single integrated structure. The protrusion serving as a flow separator also creates the ridge structure that defines flow paths and provides structural support. The first and second regions are integrated into one continuous plate with varying thickness, eliminating the need for separate components. This merging achieves efficient heat exchange through extended water flow paths while keeping the device structure simple and compact.

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

The solution effectively maintains metal surface temperatures within safe limits, reducing thermal fatigue and leakage risks while achieving efficient heat exchange and extensive condensation, resulting in a cost-effective and compact heat exchange arrangement for gas-fired systems.

Implementation Method 1

The plate for a heat exchange arrangement for the exchange of heat between a first and a second medium

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

The gas is at the same time cooled by the tap water, i.e. the tap water is heated by the gas

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

Condensation provides additional thermal energy from the fuel due to the release of latent heat. Water vapour from the combustion gases condenses when in contact with low temperature metal surfaces of the heat exchange arrangement

Methodology Applied
Scientific EffectCondensation: Condensation

Data Source

PatentEP3622237B1Plate for heat exchange arrangement and heat exchange arrangement
Publication Date: 2023.07.12 ALFA LAVAL CORP AB
  • EP3622237B1 patent drawingFigure 1~2
  • EP3622237B1 patent drawingFigure 3~4
  • EP3622237B1 patent drawingFigure 5~6

AI summary

A plate (1,1A) for a heat exchange arrangement for the exchange of heat between a first and a second medium. The plate has a first heat transferring surface (A) in contact with the first medium and a second heat transferring surface (B) in contactwith the second medium. The plate comprises an inlet porthole (2) for the first medium; an inlet porthole (4) for the second medium, and an outlet porthole (6,6',6'') for the first medium. The first heat transferring surface comprises a protrusion forming at least one ridge which is arranged to divide said heat transfer surface into at least a first region, which is in direct thermal contact with the said inlet porthole for the second medium, and a second region, which is not in direct thermal contact with the inlet porthole for the second medium. The second region substantially surrounds the first region. The inlet porthole for the first medium is arranged in said first region, whilethe outlet porthole for the first medium is arranged in the second region. Moreover, the said at least one ridge forms at least one elongated transfer channel arranged to convey the said first medium from the first region to the second region.