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Thermal Efficiency Comparison of Borehole Heat Exchangers with Different Drillhole Diameters

Please always quote using this URN: urn:nbn:de:bvb:29-opus-49236
  • Thermal efficiency of borehole heat exchangers (BHE) is of crucial importance for the design and optimization of ground source heat pump (GSHP) system. This paper investigates thermal efficiency of a BHE with three drillhole diameters: 121 mm, 165 mm and 180 mm. The BHE was installed in a GSHP system of an office building located in Nuremberg, Germany. Thermal properties and hydraulic properties of the ground where the BHE was installed have been measured by thermal response tests as well as pumping tests. Furthermore, the evaluation of thermal performance is made possible by monitoring operation of the GSHP system. Using the recorded data, thermal exchange rates have been calculated andThermal efficiency of borehole heat exchangers (BHE) is of crucial importance for the design and optimization of ground source heat pump (GSHP) system. This paper investigates thermal efficiency of a BHE with three drillhole diameters: 121 mm, 165 mm and 180 mm. The BHE was installed in a GSHP system of an office building located in Nuremberg, Germany. Thermal properties and hydraulic properties of the ground where the BHE was installed have been measured by thermal response tests as well as pumping tests. Furthermore, the evaluation of thermal performance is made possible by monitoring operation of the GSHP system. Using the recorded data, thermal exchange rates have been calculated and compared in a daily period as well as a seasonal period. The daily statistics indicate that the thermal exchange rate of the BHE increases with larger drillhole diameter. For the seasonal cooling performance, the amount of thermal exchange of BHE with 165 mm and 180 mm diameters was found to be 3.2% and 7.1% larger than that of the BHE with 121 mm diameter, respectively. These findings provide helpful suggestions for the design of future GSHP systems to achieve higher energy-efficiency.show moreshow less

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Metadaten
Author:Jin Luo, Joachim Rohn, Manfred Bayer, Anna Priess
URN:urn:nbn:de:bvb:29-opus-49236
Document Type:Article
Language:English
Year of Completion:2013
Publishing Institution:Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)
Release Date:2013/08/28
Tag:borehole heat exchanger; drillhole diameter; ground source heat pump system; thermal efficiency
SWD-Keyword:-
Original publication:Energies 6.8 (2013): S. 4187-4206. 26.08.2013 <http://www.mdpi.com/1996-1073/6/8/4187>
Institutes:Naturwissenschaftliche Fakultät / Naturwissenschaftliche Fakultät -ohne weitere Spezifikation-
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 55 Geowissenschaften, Geologie / 550 Geowissenschaften
open_access (DINI-Set):open_access
Collections:Universität Erlangen-Nürnberg / Von der FAU geförderte Open Access Artikel / Von der FAU geförderte Open Access Artikel 2013