Folded Outer Pipe for Coaxial Geothermal Collector Installation
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Solution Overview
Problem
The installation of coaxial geothermal collectors into deep heat wells is challenging due to the close dimensioning of the outer pipe, which can damage the pipe during installation and is exacerbated by increasing well depths, especially when the outer pipe is rubbed against the borehole wall.
Innovation Solution
The outer pipe is designed with a crystallized plastic material and a folded installation shape with a non-circular cross section, featuring inwards folded sections and varying thicknesses to facilitate insertion, and can be opened to a circular cross section for use, with optional recesses or protuberances for enhanced wear resistance and rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the outer pipe is dimensioned to fill as large portion of the borehole as possible, then thermal contact with bedrock is improved, but installation difficulty increases and pipe damage risk increases
Solution Approach 1:
The outer pipe transitions from a static circular cross-section to a dynamic folded cross-section during installation, then returns to circular shape after installation. This dynamic shape change allows the pipe to adapt to different operational phases: folded for easy insertion, circular for optimal thermal contact.
Solution Approach 2:
The pipe's geometric parameters (cross-sectional shape, diameter) are changed temporarily during installation. The pipe is deformed to a folded shape with reduced maximum diameter for insertion, then restored to its original circular shape with full diameter for optimal thermal contact with the borehole wall.
2Reliability
If the outer pipe is dimensioned to fill as large portion of the borehole as possible, then thermal contact with bedrock is improved, but pipe damage during installation increases
Solution Approach 1:
The pipe dynamically changes its shape from folded during installation to circular during operation, allowing it to avoid damage during insertion while maintaining structural integrity and optimal thermal contact during use.
Solution Approach 2:
The pipe is pre-formed with a folded configuration specifically for the installation phase, reducing the risk of damage during insertion. After installation, it transitions to its operational circular shape where it can properly contact the borehole wall for thermal exchange.
3Ease of operation
If the outer pipe is folded into a non-circular cross section for installation, then ease of installation is improved, but pipe wall thickness must be reduced which worsens wear resistance
Solution Approach 1:
The pipe wall thickness is optimized locally: thinner in the folded section to enable deformation and insertion, and thicker in the non-folded sections to maintain wear resistance. This local differentiation allows the pipe to achieve both installability and durability.
Solution Approach 2:
The pipe wall is segmented into different thickness zones: the folded section has reduced thickness for easy deformation, while other sections maintain full thickness for wear resistance. This segmentation allows each part to serve its specific function optimally.
4Ease of operation
If the shortest distance between folded pipe wall sections is reduced to facilitate insertion, then ease of installation is improved, but structural rigidity may be compromised
Solution Approach 1:
The pipe structure has local quality variations: the folded section with reduced distance between walls is designed to be flexible for insertion, while other sections maintain full structural rigidity. The localized thinning is confined only to where needed for deformation.
Solution Approach 2:
The pipe is segmented into flexible folded sections and rigid non-folded sections. The folded sections are designed with reduced wall separation to enable bending, while other segments maintain full thickness and rigidity for structural support and wear resistance.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
An outer pipe (100) for a coaxial geothermal collector (10) is configured to be inserted into a heat well bored in the bedrock while being folded into a folded installation shape Si with a substantially non-circular cross section, and to be opened in the heat well into an open use shape Suse with a substantially circular cross section. The pipe wall (101) has, in the folded installation shape, a maximum diameter Dmax which is smaller than the circle diameter DC, and comprises an inwards folded pipe wall section (103). The inwards folded pipe wall section (103) has a first pipe wall thickness T1 and the pipe wall has, outside the inwards folded pipe wall section, a second pipe wall thickness T2 which is higher than the first pipe wall thickness for improving the wear resistance of the outer pipe.