Factors Influencing the Thermal Efficiency of Horizontal Ground Heat Exchangers

Eloisa Di Sipio and David Bertermann
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Eloisa Di Sipio: Department of Geology, GeoZentrum Nordbayern, Friedrich-Alexander University Erlangen-Nuremberg, 91054 Erlangen, Germany
David Bertermann: Department of Geology, GeoZentrum Nordbayern, Friedrich-Alexander University Erlangen-Nuremberg, 91054 Erlangen, Germany

Energies, 2017, vol. 10, issue 11, 1-21

Abstract: The performance of very shallow geothermal systems (VSGs), interesting the first 2 m of depth from ground level, is strongly correlated to the kind of sediment locally available. These systems are attractive due to their low installation costs, less legal constraints, easy maintenance and possibility for technical improvements. The Improving Thermal Efficiency of horizontal ground heat exchangers Project (ITER) aims to understand how to enhance the heat transfer of the sediments surrounding the pipes and to depict the VSGs behavior in extreme thermal situations. In this regard, five helices were installed horizontally surrounded by five different backfilling materials under the same climatic conditions and tested under different operation modes. The field test monitoring concerned: (a) monthly measurement of thermal conductivity and moisture content on surface; (b) continuous recording of air and ground temperature (inside and outside each helix); (c) continuous climatological and ground volumetric water content (VWC) data acquisition. The interactions between soils, VSGs, environment and climate are presented here, focusing on the differences and similarities between the behavior of the helix and surrounding material, especially when the heat pump is running in heating mode for a very long time, forcing the ground temperature to drop below 0 °C.

Keywords: very shallow geothermal energy; horizontal collectors; thermal conductivity; volumetric water content; soil (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2017
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (11)

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