Geothermal device and method
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Solution Overview
Problem
Existing geothermal probes and energy converters have limitations in thermal radiation and heat conduction, leading to inefficient energy generation and mechanical complexity, which reduces operational hours and adaptability.
Innovation Solution
A geothermal probe with a coaxial pipe string made of carbon fiber reinforced material, featuring a star-shaped cross-section and thermal insulation, combined with a fully electronic engine control system and a high-pressure expansion machine using carbon dioxide as a working medium, enhances thermal efficiency and adaptability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional circular pipe string is used, then manufacturing is simpler, but heat output is limited due to smaller outer surface area
Solution Approach 1:
The pipe string cross-section is changed from a conventional circular symmetric shape to an asymmetric star-shaped polygon with multiple points and depressions. This asymmetric geometry increases the outer surface area of the pipe string, thereby enhancing heat exchange with the surrounding geothermal environment while maintaining manufacturability through standardized forming processes.
2Strength
If conventional steel pipe string is used, then structural strength is sufficient, but weight is high requiring complex lowering mechanisms
Solution Approach 1:
The pipe string is constructed from carbon fiber reinforced plastic (CFRP) composite material, which combines the high strength characteristics of carbon fibers with the structural integrity of reinforced plastic. This composite material provides sufficient structural strength for deep borehole applications while reducing the overall weight compared to conventional steel pipe strings, thereby simplifying the lowering mechanism requirements.
3Power
If conventional materials with high thermal conductivity are used, then heat transfer is efficient, but heat loss in vertical section is excessive
Solution Approach 1:
The pipe string is divided into different sections with different thermal properties. The horizontal section uses material with high thermal conductivity to maximize heat absorption from the geothermal environment, while the vertical section uses material with low thermal conductivity (carbon fiber reinforced plastic) to minimize heat loss during fluid return. This local differentiation of thermal properties optimizes both heat transfer efficiency and energy conservation.
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 improves thermal insulation, reduces weight, increases heat output, and enhances operational efficiency and adaptability, allowing for continuous energy generation with reduced mechanical complexity.
Implementation Method 1
Carbon fibers also have a very low thermal conductivity of 17 W/mK. Therefore, heat loss can be advantageously reduced and insulation properties improved.
Implementation Method 2
Carbon fibers also have a very low thermal conductivity of 17 W/mK. Therefore, heat loss can be advantageously reduced and insulation properties improved.
Data Source
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AI summary
The invention relates to a device and a method for generating electrical energy or for obtaining heat from geothermal energy, comprising at least one geothermal probe and at least one energy converter, in particular wherein a working medium of the geothermal probe is also a working medium of the energy converter.