Kupfernagel, Jan-Henrik ; Hesse, Jan Christopher ; Schedel, Markus ; Welsch, Bastian ; Anbergen, Hauke ; Müller, Lutz ; Sass, Ingo (2024)
Impact of operational temperature changes and freeze–thaw cycles on the hydraulic conductivity of borehole heat exchangers.
In: Geothermal Energy : Science – Society – Technology, 2021, 9 (1)
doi: 10.26083/tuprints-00023617
Artikel, Zweitveröffentlichung, Verlagsversion
 | Es ist eine neuere Version dieses Eintrags verfügbar. |
Kurzbeschreibung (Abstract)
A large share of the primary energy is consumed to provide space heating. Geothermal energy offers a regenerative alternative. For reasons of efficiency and environmental protection, it is important to ensure the system integrity of a borehole heat exchanger (BHE). Previous investigations have focused on the individual components of the BHE or on the grout and pipe systems’ integrity. This study focused on the analysis of the hydraulic system integrity of the complete subsoil–grout–pipe system as well as possible thermally induced changes. For this purpose, a pilot-scale experiment was built to test a 1-m section of a typical BHE under in situ pressure, hydraulic and temperature conditions. During the tests the hydraulic system permeability of the soil and the BHE was measured continuously and separately from each other. In addition, the temperature monitoring array was installed in a 50-cm cross-sectional area. Significant temperature-related fluctuations in the sealing performance could be observed. Hydraulic conductivity limits required by VDI 4640-2 (Thermal use of the underground—ground source heat pump systems, 2019) were exceeded without frost action. The succeeding application of freeze–thaw cycles further enhances the system permeability. The study shows that the thermally induced effects on the system integrity of the BHE are larger and more significant than the subsequent frost-induced effects. The hydrophobic character of the high-density polyethylene (PE-HD) pipes as well as its high coefficient of thermal expansion seem to be the main points of weakness in the system. Optimization research should focus on the interface connection between grout and pipe, whereby hydrophilic pipe materials such as stainless steel or aluminum should also be considered as well as manipulation of the pipe surface properties of PE-HD.
| Typ des Eintrags: | Artikel |
|---|---|
| Erschienen: | 2024 |
| Autor(en): | Kupfernagel, Jan-Henrik ; Hesse, Jan Christopher ; Schedel, Markus ; Welsch, Bastian ; Anbergen, Hauke ; Müller, Lutz ; Sass, Ingo |
| Art des Eintrags: | Zweitveröffentlichung |
| Titel: | Impact of operational temperature changes and freeze–thaw cycles on the hydraulic conductivity of borehole heat exchangers |
| Sprache: | Englisch |
| Publikationsjahr: | 8 April 2024 |
| Ort: | Darmstadt |
| Publikationsdatum der Erstveröffentlichung: | 28 Oktober 2021 |
| Ort der Erstveröffentlichung: | Berlin ; Heidelberg |
| Verlag: | SpringerOpen |
| Titel der Zeitschrift, Zeitung oder Schriftenreihe: | Geothermal Energy : Science – Society – Technology |
| Jahrgang/Volume einer Zeitschrift: | 9 |
| (Heft-)Nummer: | 1 |
| Kollation: | 25 Seiten |
| DOI: | 10.26083/tuprints-00023617 |
| URL / URN: | https://tuprints.ulb.tu-darmstadt.de/23617 |
| Zugehörige Links: | |
| Herkunft: | Zweitveröffentlichung DeepGreen |
| Kurzbeschreibung (Abstract): | A large share of the primary energy is consumed to provide space heating. Geothermal energy offers a regenerative alternative. For reasons of efficiency and environmental protection, it is important to ensure the system integrity of a borehole heat exchanger (BHE). Previous investigations have focused on the individual components of the BHE or on the grout and pipe systems’ integrity. This study focused on the analysis of the hydraulic system integrity of the complete subsoil–grout–pipe system as well as possible thermally induced changes. For this purpose, a pilot-scale experiment was built to test a 1-m section of a typical BHE under in situ pressure, hydraulic and temperature conditions. During the tests the hydraulic system permeability of the soil and the BHE was measured continuously and separately from each other. In addition, the temperature monitoring array was installed in a 50-cm cross-sectional area. Significant temperature-related fluctuations in the sealing performance could be observed. Hydraulic conductivity limits required by VDI 4640-2 (Thermal use of the underground—ground source heat pump systems, 2019) were exceeded without frost action. The succeeding application of freeze–thaw cycles further enhances the system permeability. The study shows that the thermally induced effects on the system integrity of the BHE are larger and more significant than the subsequent frost-induced effects. The hydrophobic character of the high-density polyethylene (PE-HD) pipes as well as its high coefficient of thermal expansion seem to be the main points of weakness in the system. Optimization research should focus on the interface connection between grout and pipe, whereby hydrophilic pipe materials such as stainless steel or aluminum should also be considered as well as manipulation of the pipe surface properties of PE-HD. |
| Freie Schlagworte: | Borehole heat exchanger, Freeze–thaw cycles, Grouting material, Pilot-scale experiment, Hydraulic system conductivity, System integrity |
| ID-Nummer: | Artikel-ID: 24 |
| Status: | Verlagsversion |
| URN: | urn:nbn:de:tuda-tuprints-236178 |
| Sachgruppe der Dewey Dezimalklassifikatin (DDC): | 300 Sozialwissenschaften > 333.7 Natürliche Ressourcen, Energie und Umwelt 500 Naturwissenschaften und Mathematik > 550 Geowissenschaften |
| Fachbereich(e)/-gebiet(e): | 11 Fachbereich Material- und Geowissenschaften 11 Fachbereich Material- und Geowissenschaften > Geowissenschaften 11 Fachbereich Material- und Geowissenschaften > Geowissenschaften > Fachgebiet Angewandte Geothermie Exzellenzinitiative Exzellenzinitiative > Graduiertenschulen Exzellenzinitiative > Graduiertenschulen > Graduate School of Energy Science and Engineering (ESE) |
| Hinterlegungsdatum: | 08 Apr 2024 12:26 |
| Letzte Änderung: | 09 Apr 2024 06:22 |
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| Suche nach Titel in: | TUfind oder in Google |
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- Impact of operational temperature changes and freeze–thaw cycles on the hydraulic conductivity of borehole heat exchangers. (deposited 08 Apr 2024 12:26) [Gegenwärtig angezeigt]
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