Numerical studies on underground thermal energy storages

Julian Schleicher, Islam Marzouk*, Matthias Rebhan, Franz Tschuchnigg

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference paperpeer-review

Abstract

The ever-increasing global energy consumption leads to a rise in demand for re-newable energy sources and storage solutions. Nevertheless, in several cases en-ergy is not sufficiently stored and dissipates unused (e.g., waste heat from air conditioning systems). This results in increasing the air temperature, especially in urban areas. Underground thermal energy storage (UTES) systems can be used to utilize underground soil to store unused energy for use when needed (e.g., dis-trict heating). The objective of this paper is to investigate the implementation of a UTES system in the 2D finite element software PLAXIS. Furthermore, the mod-elling approach used for thermally insulating the storage tank by using improved diaphragm walls was evaluated.
In case of a UTES system, it is necessary to model a heating phase in which the storage stores energy for later use. For this purpose, different modelling ap-proaches were investigated. Each analysis aimed to heat the storage reservoir to 90°C. Afterwards, the difference in temperature distribution in the soil was inves-tigated.
Moreover, the influence of the thermal properties of the diaphragm walls on the temperature distribution was reviewed. Concrete with a density of 2,400 kg/m³ was compared to a lightweight concrete developed at the Institute of Structural Concrete at Graz University of Technology. The thermal properties of the light-weight concrete were determined based on laboratory tests. The lightweight con-crete had a thermal conductivity of 1.026 W/mK, which led to a significant reduc-tion in heat losses from the storage.
Original languageEnglish
Title of host publicationRecent Research on Geotechnical Engineering, Remote Sensing, Geophysics and Earthquake Seismology
Subtitle of host publicationProceedings of the 2nd MedGU, Marrakesh 2022 (Volume 3)
PublisherSpringer
Pages83-86
Number of pages5
Publication statusPublished - 2024
EventMedGU-22 - Marrakech, Morocco, Hybrider Event, Morocco
Duration: 27 Nov 202230 Nov 2022
https://www.medgu.org/

Publication series

NameAdvances in Science, Technology & Innovation

Conference

ConferenceMedGU-22
Abbreviated titleMedGU-22
Country/TerritoryMorocco
CityHybrider Event
Period27/11/2230/11/22
Internet address

Keywords

  • numerical modelling
  • Underground Thermal Energy Storage System UTES
  • concrete thermal properties
  • temperature effects

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