Disposable Percussion Mole for Geothermal Ground-Loop Installation
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Solution Overview
Problem
Current methods for installing underground pipework for geothermal heat-pump systems are costly and cumbersome, especially in confined locations, requiring expensive drilling equipment and risking hole collapse, which complicates the insertion of thermally conductive pipes and necessitates costly caulking to maintain efficiency.
Innovation Solution
A disposable percussion mole is used to concurrently create a blind-ended passage and insert a closed loop of pipework, eliminating the need for expensive drilling equipment and caulking, with a valve assembly allowing for efficient fluid flow and switching configurations to facilitate heat exchange, and using recycled glass granules to reduce friction during insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional drilling and boring machines are used to create holes for pipework installation, then the holes can be created with access control, but the equipment is expensive and cumbersome requiring significant access space
Solution Approach 1:
The patent employs a disposable percussion mole that is discarded after single use, eliminating the need for expensive, complex drilling equipment. The mole creates the hole and is then abandoned in place, with pipework inserted through it, solving the access and equipment complexity problem for confined locations.
Solution Approach 2:
The invention extracts the mole creation function from the expensive drilling equipment and implements it through a simple, disposable percussion mole that can be manually or mechanically operated with minimal space requirements.
2Ease of operation
If drilling techniques are used to create deep holes, then access to the distant end is possible, but the equipment is expensive and must be located at ground-level entry point
Solution Approach 1:
The disposable percussion mole eliminates the need for expensive drilling machinery located at ground level. The mole is inserted through the pipework and discarded after use, creating the hole from within the building rather than requiring ground-level equipment access.
Solution Approach 2:
Instead of creating holes from ground level downward with expensive drilling equipment, the invention inverts the approach by inserting the mole through the pipework from the building interior, allowing hole creation without external equipment access.
3Device complexity
If drilled holes are used without sleeves, then installation is simpler, but the holes may collapse after drilling equipment removal
Solution Approach 1:
The pipework is inserted into the hole before the mole is discarded, ensuring the hole is stabilized by the presence of the pipework throughout the mole's operational life. This preliminary insertion prevents hole collapse that would occur if equipment were removed before pipe installation.
Solution Approach 2:
The disposable mole serves as a temporary support structure during installation, then is discarded after the pipework is in place and the hole is sealed with grout, eliminating the need for permanent sleeves while ensuring hole stability during the critical installation phase.
4Reliability
If conventional drilling with sleeves is used, then hole collapse is prevented, but thermally conductive caulking is required to maintain system efficiency
Solution Approach 1:
The disposable mole is discarded and the hole is sealed with grout instead of using expensive sleeves requiring thermal caulking. The grout provides both structural support and thermal conductivity, eliminating the need for additional caulking materials and processes.
Solution Approach 2:
The invention changes the sealing material from thermally conductive caulking (required with sleeves) to grout that provides both structural support and thermal conductivity, simplifying the installation process while maintaining system efficiency.
5Device complexity
If percussion mole is used to create passages, then expensive drilling equipment is eliminated, but the mole must be recovered after use which adds complexity
Solution Approach 1:
The percussion mole is designed as a disposable component that is discarded after single use. This eliminates the need for expensive equipment recovery operations while maintaining the cost-effectiveness advantage of using a simple mole instead of complex drilling machinery.
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 approach reduces installation costs, simplifies the process, and enhances thermal conductivity by eliminating the need for traditional excavation methods and caulking, while ensuring efficient heat transfer and minimizing environmental impact.
Implementation Method 1
The mole is driven by compressed air, provided along a rear-mounted compressed air hose. An internal piston having significant mass is caused to travel rapidly forwards within the tubular casing of the mole, where it strikes the forward end of the casing, driving the casing forwards
Implementation Method 2
An internal piston having significant mass is caused to travel rapidly forwards within the tubular casing of the mole, where it strikes the forward end of the casing, driving the casing forwards, displacing the ground around the casing in the process
Implementation Method 3
The first fluid pipe is used for delivery of driving fluid during insertion
Implementation Method 4
The second pipe is used as an exhaust for the spent compressed air expelled from the mole
Data Source
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AI summary
An apparatus for inserting a ground-loop for a geothermal heat-pump system comprises: a percussion mole (4);a first fluid pipe (5), connected to the mole (4), for conveying a heat-exchange fluid from the heat- pump system into the ground; and a second fluid pipe (6), connected to the mole (4), for returning the heat-exchange fluid to the heat-pump system. One of the first and second fluid pipes (5, 6) comprises an intake pipe for delivering a driving fluid to the mole (4) during insertion of the ground-loop and the other fluid pipe comprises an exhaust pipe for the driving fluid.