Plate-Type Heat Exchanger Solid-Phase Diffusion Bonding
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Solution Overview
Problem
The existing methods for layering and joining corrugated plate-like components in plate-type heat exchangers, such as brazing, often result in joining defects like erosion, cracks, decreased corrosion resistance, and buried flow paths, and are costly, while solid phase diffusion bonding is affected by pressure and temperature conditions and additive elements in stainless steel sheets.
Innovation Solution
A plate-type heat exchanger design that uses solid phase diffusion bonding for joining side-edge surfaces and flow paths, with specific angles and surface preparations, and optional braze bonding for desired strength, utilizing stainless steel sheets with controlled additive elements and surface roughness, to achieve robust air-tightness and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If brazing is used to join plate-like components, then pressure resistance is improved, but joining defects occur such as erosion, cracks, decreased corrosion resistance, and buried flow paths
Solution Approach 1:
The patent removes the braze material from the joining process entirely, extracting the harmful element that causes erosion, cracks, and corrosion resistance degradation. Instead of using brazing, the invention employs solid-phase diffusion bonding to join the plate-like components directly without any filler material, thereby eliminating the associated defects while maintaining pressure resistance.
Solution Approach 2:
The patent replaces the thermal-metallurgical joining system (brazing) with a solid-phase diffusion bonding system. This substitution changes the fundamental mechanism from melting and filling with braze material to direct atomic diffusion between clean metal surfaces under controlled temperature and pressure, eliminating the harmful effects of braze material while achieving reliable joints.
2Reliability
If solid phase diffusion bonding is used to join plate-like components, then corrosion resistance is improved, but joining quality is affected by additive elements in stainless steel sheets
Solution Approach 1:
The patent applies local quality control by specifically managing the composition of stainless steel sheets at the joining interfaces. It controls the content of easily oxidizable elements (Al, Ti, Si) to 0.05% or less in the regions that will undergo diffusion bonding, ensuring that these local areas have the appropriate chemical composition for high-quality joining while allowing other regions of the material to maintain their overall properties.
Solution Approach 2:
The patent changes the chemical composition parameters of the stainless steel material by strictly limiting the content of easily oxidizable elements (Al, Ti, Si) to 0.05% or less. This parameter change ensures that the material is suitable for solid-phase diffusion bonding by preventing excessive oxide formation that would interfere with the bonding process, thereby achieving both corrosion resistance and high joining quality.
3Manufacturing precision
If stainless steel sheets with controlled additive elements are used, then diffusion bonding quality is improved, but material selection becomes more restricted
Solution Approach 1:
The patent establishes specific parameter ranges for stainless steel composition (Al, Ti, Si ≤ 0.05%) that optimize diffusion bonding quality. By defining these precise compositional parameters, the invention ensures high bonding quality while providing clear material selection criteria that balance performance requirements with manufacturing feasibility.
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 method allows for the cost-effective manufacturing of a robustly air-tightened plate-type heat exchanger with improved durability, avoiding the limitations of brazing and ensuring sufficient joining quality across the plate-like components.
Implementation Method 1
the contact region between overlapping portions of the standing wall sections of adjacent box-like plates are joined to one another by brazing
Implementation Method 2
heat exchange is effected mutually by virtue of the temperature difference between the media flowing through these paths of the high- and low-temperature media
Data Source
Figure 1~2B
Figure 3A~4
Figure 5A~6
AI summary
This plate-type heat exchanger which ensures air-tightness can be easily produced by performing solid-phase diffusion bonding without using a brazing material in at least part of the joining of lateral-end surfaces of plate-type components constituting a plate-type heat exchanger, and the joining of a channel for upper and lower plate-type components. The present invention involves: a rectangular plate-type component constituting the heat exchanger case being a box-type component provided with a vertical wall section along the peripheral edge thereof; box-type components (1, 2) which have the same shape being configured in a manner such that the orientation of the horizontal surface of one of the box-type components is reversed; layering the box-type components (1, 2) in order; engaging the upper section of the vertical wall section of the lower-layer component with the lower section of the vertical wall section of the upper-layer component; setting the angle (θ) of the vertical wall section to θ≤30°; and performing solid-phase diffusion bonding in at least part of the contact site between the vertical wall section of the upper-layer component and the vertical wall section of the lower-layer component.