1,721,025 research outputs found
Thermo-physical properties of grouting mixtures and 3D simulations in vertical closed loop geothermal systems
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Comparative methods to determine thermal conductivity of grouting mixtures and 3D simulations in vertical closed-loop system
Full text linkThermo-physical properties of groundwater in sedimentary deposits of Umbria-Marche Succession and their role in low enthalpy geothermal studies
No full textHow a sensitive analysis on the coupling geology and borehole heat exchanger characteristics can improve the efficiency and production of shallow geothermal plants
Full text linkKnowledge of the thermal behaviour around and throughout borehole heat exchangers (BHEs) is essential for designing a low enthalpy geothermal plant. In particular, the type of grout used in sealing the space between BHE walls and the pipes is fundamental for optimizing the heat transfer and minimizing the thermal resistance, thereby promoting the reduction of total drilling lengths and installation costs. A comparison between grouts with different thermal conductivities coupled with common hydrogeological contexts, was modelled for a typical one-year heating for continental climates. These data have been used for a sensitivity analysis taking into account different flow rates through pipes. The results highlight that in groundwater transient conditions, porous lithologies allow for greater heat power extractions to be obtained with an increasing grout thermal conductivity than limestone or clayey silt deposits do. Moreover, increasing the inlet flow rates through the pipe greatly improves the final heat power extraction. As a result, when the underground allows for high extraction rates, the use of high performing grouts is warmly suggested ensuring greater productions
Thermo-physical and geo-mechanical characterization of faulted carbonate rock masses (Valdieri, Italy)
Full text linkWater in rock masses is a key factor in geo-mechanics, hydrogeology, mining, geo-thermics, and more. It is relevant in interpreting rock mass behavior (e.g., water-rock interaction or slope stability), as well as in defining heat transfer mechanisms. Pointing out the contribution of secondary porosity in increasing advective heat transfer instead of the conduction phenomenon, this study aims to highlight a different thermal response of sound rocks and faulted zones. Moreover, it provides some methodological suggestions to minimize environment disturbance in data collection and a robust interpretation of the results. An interesting outcrop was identified in a carbonate quarry near Valdieri (north-west Italian Alps): it was studied coupling a geo-mechanical and a thermo-physical approach. In particular, geo-mechanical and photogrammetric surveys, InfraRed Thermography (IRT), and Thermal Conductivity (TC) measurements were conducted. The rationale of the research is based on the fact that, when a substantial temperature difference between flowing groundwater and rocks was detected, IRT can reveal information about geo-mechanical and hydrogeological properties of the rock masses such as a degree of fracturing and joint interconnection. A comparative field and laboratory analysis using different devices enabled a more detailed insight providing values in both dry and wet conditions. A different thermal response was highlighted for the cataclastic zone as well. IRT results showed an evident inverse relationship among the number of joints per meter and the detected surface temperature. This is probably caused by the higher water flow within the cataclastic fault zone. Moreover, low fractured portions of the rock mass presented higher cooling rates and conducted heat far more than those with poor geo-mechanical characteristics (difference up to 40%). A negligible ratio between wet and dried thermal conductivity (about 1%) was also detected in lab measurements, which confirmed that primary porosity is not usually relevant in influencing thermal properties of the sound rock
The use of open-source electronic platforms to monitor the efficiency of Borehole Thermal Energy Storage Systems (BTES) in porous materials by means of lab scale modeling
No full textIn the framework of heating and cooling of buildings, the underground can be used as thermal energy storage to smooth the difference between production and demand. The heat transfer performances vary significantly depending on the type of soil where the plant is set up, but also with the water content and the presence of groundwater flow. A lab scale modelling aimed at the simulation of thermal energy storage behaviour in porous materials was begun by Giordano et al. (2013) in order to better design the field scale living lab set up in Torino (Giordano et al., 2016). In this work, an implementation of the laboratory device is proposed with a monitoring system made of a low-cost open-source electronic platform based on Arduino®. With respect to the previous version, the heat sources have been replaced with small scale borehole heat exchangers fed by a heating bath circulator equipped with in/out temperature sensors and flow rate control. Temperature and moisture monitoring within the medium has been improved with new and more accurate sensors. In addition, load sensors have been set up below the box to monitor the moisture migration induced during the heat injection. All the sensors are read by Arduino® boards and shields thanks to on purpose scripts and the data are monitored by a lab PC
Innovative applications of geothermal energy for direct uses: A pilot study case in Marche region (Italy)
No full textA detailed investigation aimed to optimize the knowledge about the realization of low enthalpy geothermal plants, answering to the energy related challenges proposed by Horizon 2020 and trying to move toward a better integration between research and industry, is currently in progress in the Marche Region (Central Italy). The main goals of this project are: i) to improve the present-day knowledge about the heat transfer coming from two geothermal boreholes 100 m in depth and with a distance of 9 m from each other, in order to better understand the behaviour of a geothermal probes in a particular geological, hydrogeological and structural context; ii) to control the behaviour of two commercial grouts and to study the thermo-physical and mineralogical properties of new grouts performing laboratory tests and monitoring; iii) to test a new hybrid geothermal/micro-cogeneration system for the heating of the buildings. As part of the project, an experimental plant is in progress at the University of Camerino (Geology Division). An interdisciplinary research team as well as private companies and University spin off, are engaged for the project development
Multidisciplinary study of the “salinelle" of paternò mud volcanoes: Characteristics of the fluids and possible correlations with the activity of mt. etna
Full text linkMonitoring of hydrothermal fluid emissions can provide detailed information about convective upwelling of geothermal fluids and their geochemical characteristics, as a function of tectonic stress or deeper gas input. In particular, at the Salinelle of Mt. Etna Geosite (Paterno' and Belpasso, Eastern Sicily) natural emissions mainly consist of a fluid phase made of salty water, mud, gas and liquid hydrocarbons from an admixture of magmatic and hydrothermal gases. In this framework, our study mainly focused on the thermal and geochemical monitoring of hydrothermal fluids of the most active site, Salinelle dei Cappuccini. N earby hydrothermal vents (Salinelle del Fiume; Salinelle di San Biagio), were also investigated. Analysis of the magnitude and frequency of seismic events all around Mt. Etna were conducted as well. Analysis of daily temperatures showed a constant trend: higher values (> 35 °C) within the first monitoring period, followed by a strong decrease (down to 9 °C), and a new gradual increase over the following months. This trend seems to be linked to magmatic processes occurring at depth below Mt. Etna, and could lead to a modification of the geochemical and thermal characteristics of the fluids issuing at the mud-pools and gas vents of Salinelle. The higher the frequency of seismic events corresponding to higher daily energy released, the higher fluid temperatures observed. Understanding how these fluids blend and what is their relationship with Mt. Etna volcanism can be of great importance in forecasting new eruptive cycles in the case they precede changes in volcanic activity
Geological, hydrogeological and thermal characterization of deep subsoil (Marche Region, Italy) linked to use of low enthalpy geothermal heat pumps
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