Chicco J.

Mandrone G.

English

PORTO@iris (Publications Open Repository TOrino - Politecnico di Torino)

29 November 2022POLITECNICO DI TORINORepository ISTITUZIONALEThermo-physical properties of grouting mixtures and 3D simulations in vertical closed loop geothermal systems / Chicco,J.; Mandrone, G.. - In: GEOPHYSICAL RESEARCH ABSTRACTS. - ISSN 1607-7962. - (2018). ((Intervento presentatoal convegno European Geosciences Union (EGU), General Assembly 2018 tenutosi a Vienna, Austria nel Aprile 2018.OriginalThermo-physical properties of grouting mixtures and 3D simulations in vertical closed loop geothermalsystemsPublisher:PublishedDOI:Terms of use:openAccessPublisher copyright(Article begins on next page)This article is made available under terms and conditions as specified in the  corresponding bibliographic description inthe repositoryAvailability:This version is available at: 11583/2915354 since: 2021-07-27T14:22:32ZCopernicusGeophysical Research AbstractsVol. 20, EGU2018-10757, 2018EGU General Assembly 2018© Author(s) 2018. CC Attribution 4.0 license.Thermo-physical properties of grouting mixtures and 3D simulations invertical closed-loop geothermal system.Jessica Chicco and Giuseppe MandroneUniversity of Torino, Department of Earth Sciences, Torino, Italy (jessica.chicco@unito.it)Knowledge of thermophysical properties of grouting materials is one of the important factors to improve the heatexchange between pipes and the ground in vertical closed-loop geothermal systems. The use of a proper grout isin fact essential in order to guarantee an effective heat transfer between the ground and the heat carrier fluid inthe pipe. Generally, the commercial demand is of a workable and cheaper geothermal grout, not always payingattention to the thermal and mechanical characteristics. In particular, since thermal conductivity is a fundamentalproperty to be considered, the main objective of this paper is to study the physical properties of suitable materialto be used as geothermal grout. To this regard, different mixtures were investigated and thermal, mechanical, andmineralogical properties were tested after twenty-eight days of hardening. We tested two commercial geothermalgrouts adding different quantities of water, and two composed of Portland cement and quartz sand in differentpercentages. In order to obtain reliable results, thermal properties were evaluated through the use of three devicesworking on different principles both in steady state and in transient conditions. Moreover, with the aim ofcharacterizing the four mixtures, strength and homogeneity of the analysed materials through ultrasonic pulsevelocity (UPV), together with mineralogical determinations through X-ray diffraction (XRD) were determined.The results reveal that commercial geothermal grouts present lower values of thermal conductivity (0.9-1.2 Wm-1K-1) compared to that claimed (2.0-2.5 W m-1K-1), and approach those measured on the cement and sandmixtures (0.5-0. 7 W m-1K-1). The slightly differences between the two group of mixtures, are probably relatedto the different mineralogical composition and to the distinct mechanical characteristics. Moreover, since aluminais an highly conductivity element, two further mixtures consisting on Portland cement, quartz sand and aluminashavings in various proportions were tested, leading to an improvement of both thermal and mechanical properties.Three-dimensional thermal simulations of BHE filled with the different grout mixtures and located in differentgeological and hydrogeological conditions, were also realized by means of a numerical approach. First resultsconfirm the importance of the thermal properties of grout as well as those of the underground in increasing theefficiency of closed-loop geothermal systems.

Thermo-physical properties of grouting mixtures and 3D simulations in vertical closed loop geothermal systems

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Thermo-physical properties of grouting mixtures and 3D simulations in vertical closed loop geothermal systems

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