High-pressure and high-temperature closed geothermal exchanger for a magmatic or metamorphic formation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing closed geothermal exchangers are ill-suited for operating temperatures above 100° C due to thermal coupling limitations with the rocky massif, restricting the heat-transfer fluid temperature to typically 50° C to 70° C, whereas applications require temperatures up to 240° C.
Innovation Solution
A closed geothermal exchanger with a flexible silicone elastomer shell that directly contacts the magmatic or metamorphic formation, allowing for enhanced thermal coupling without additional coupling materials, capable of operating at temperatures up to 250° C and pressures up to 150 bar, using a containment device to manage internal pressure and maintain contact with the rocky massif.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If hydrated cement is used for thermal coupling between the exchanger and the rocky massif, then thermal coupling is provided, but the geomechanical properties are impeded at temperatures above 100° C
Solution Approach 1:
The invention removes the hydrated cement coupling material from the system entirely. The flexible shell exchanger comes into direct contact with the rocky massif wall without any intermediate thermal coupling material, thereby eliminating the temperature limitation imposed by cement's geomechanical property degradation above 100° C.
Solution Approach 2:
The exchanger employs a flexible shell that can deform and conform to the borehole wall, maintaining direct contact and thermal coupling with the rocky massif. This flexible structure replaces the rigid cement coupling, enabling operation at temperatures above 100° C while maintaining reliable thermal contact.
2Device complexity
If a flexible shell is used to enable direct contact with the rocky massif, then thermal coupling is enhanced and system complexity is reduced, but the shell must withstand high internal pressures up to 150 bar
Solution Approach 1:
The invention specifies that the flexible shell be made from silicone elastomer with particular mechanical properties (Shore A hardness between 60 and 90) that enable it to withstand the high internal pressures of up to 150 bar while maintaining flexibility for direct contact with the rocky massif.
3Temperature
If the heat-transfer fluid operates at temperatures above 100° C, then higher temperature applications are enabled, but existing exchanger designs with rigid tubes and cement coupling become unsuitable
Solution Approach 1:
The invention replaces the conventional rigid tube design with a flexible shell that can directly contact the rocky massif. This flexible structure is specifically adapted for high-temperature operation above 100° C, enabling the exchanger to function in magmatic or metamorphic formations where existing rigid tube designs with cement coupling would fail.
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
Enables efficient thermal coupling at higher temperatures and pressures, simplifying the system and allowing for the use of superheated steam or CO2 in a supercritical state, thereby supporting diffusive geostorage of heat at temperatures higher than 100° C.
Implementation Method 1
the wall of the shell, or bladder, is pressed firmly into contact with the rocky massif, thus providing thermal coupling between the exchanger and the encasing rocky massif
Implementation Method 2
a heat-transfer fluid that exchanges its heat with the sub-soil encasing the exchanger
Data Source
AI summary
The invention relates to a geothermal exchanger comprising a casing containing a heat-transfer fluid with which it is in direct contact. The casing is flexible such as to be in direct contact with a wall of the borehole containing the exchanger under the effect of the pressure of the heat-transfer fluid.