Double-Wall Heat-Exchanger Tube With Pure Iron Interphase Bonding
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Solution Overview
Problem
Existing methods for manufacturing double-wall heat-exchanger tubes are expensive and complicated, and they do not effectively address the issues of thermal conductivity, fluid tightness, and resistance to pressure, particularly in applications involving reactive fluids.
Innovation Solution
A method involving the use of a pure iron interphase between the external and internal tubes, formed through brazing, co-deformation, and hot isostatic pressing, to create a dense metallic junction without mechanical clearance, enhancing thermal conductivity and resistance to fatigue cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical clearance or gap is left between the internal and external tubes, then it is possible to detect the presence of fluid from tube piercing, but the thermal conductivity properties of the double-wall heat-exchange tube are deteriorated
Solution Approach 1:
The patent changes the physical state of the gap-filling material from loose powder to a densified compacted form. By applying compaction pressure to the metal powder or granulated material filling the gap, the density increases and voids are eliminated, thereby restoring and improving thermal conductivity while maintaining the fluid detection capability through the retained gap structure.
2Temperature
If the gap between the two tubes is filled with metal powder to improve thermal conductivity, then thermal conductivity properties are improved, but the manufacturing process becomes more complicated and expensive
Solution Approach 1:
The patent employs inexpensive metal powder or granulated material that can be easily introduced into the gap and then compacted. This disposable-like approach uses simple, cheap filling material rather than complex deposition layers or precision-fit components, achieving good thermal conductivity through compaction without requiring sophisticated manufacturing equipment or processes.
3Temperature
If chemical or electrolytic deposition is used to create an intermediate layer, then thermal conductivity is improved, but the manufacturing cost and process complexity increase
Solution Approach 1:
The patent replaces complex chemical or electrolytic deposition processes with a purely mechanical compaction process. Instead of using chemical reactions or electrical currents to deposit material layers, the invention simply packs and compacts metal powder or granulated material into the gap using mechanical pressure, thereby achieving similar thermal conductivity improvement with much simpler and more economical manufacturing.
4Temperature
If a dense metallic interphase is formed without mechanical clearance, then thermal conductivity and resistance to pressure are improved, but the ability to detect tube piercing is reduced
Solution Approach 1:
The patent applies local quality by creating different characteristics in different regions: the gap is filled and compacted locally at specific sections where thermal conductivity needs improvement, while leaving other portions of the gap structure intact or with different compaction levels. This allows simultaneous optimization of thermal conductivity in critical areas while maintaining fluid detection capability in other areas.
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 method results in a double-wall heat-exchanger tube with improved thermal conductivity, fluid tightness, and resistance to pressure, offering a 30% longer service life and reduced industrial implementation costs.
Implementation Method 1
The method results in a double-wall heat-exchanger tube with improved thermal conductivity
Implementation Method 2
hot isostatic pressing
Data Source
AI summary
A method for manufacturing a double-wall heat-exchanger tube including an external tube and an internal tube, these tubes being metallic, cylindrical and coaxial. This method includes providing a first tube having an inside diameter d1int and an outside diameter d1ext, this first tube being intended to form the external tube, a second tube having an inside diameter d2int and an outside diameter d2ext, this second tube being intended to form the internal tube, and a cylindrical coaxial tubular leaf made from Fe0 having an inside diameter dint and an outside diameter dext, such that 0.15 mm≤(d1int−dext)≤0.25 mm, 0.15 mm≤(dint−d2ext)≤0.25 mm, and 10 μm≤(dext−dint)≤200 μm.