Authors: F. Giannino, G. Manacorda, A. Simi, M. Cecchetti, D. Vacce, IDS GeoRadar Srl
Abstract: The use of radars in Civil Engineering is well known and there are several applications where it is currently utilised; they include the location of buried objects with Ground Penetrating Radar (GPR) equipment and, more recently, the real-time monitoring of buildings and structures’ stability with Interferometric GroundBased SAR (GB-InSAR) measurements.
Scientific Paper published at Smart Structures and Systems, volume 30, issue 3 2022
Title: Experimental Characterization of a Smart Material via DIC
Language: English
Authors: S. Casciati (*1), D. Bortoluzzi (*1), L. Favarelli (*1), L. Rosadini (*2)
*1: SIART, SRL
*2: Formerly SIART, SRL
Abstract: When no extensometer is available in a generic tensile-compression test carried out by a universal testing machine (for instance the model BIONIX from Material Testing Systems (MTS), the test results only provide the relative displacement between the machine grips. The test does not provide any information on the local behaviour of the material. This contribution presents the potential of an application of Digital Image Correlation (DIC) toward the reconstruction of the behaviour along the specimen. In particular, the authors test a Ni-Ti shape memory alloys (SMA) specimen with emphasis on the coupling of the two measurement techniques. The activity reported in this work have been founded by European Union Horizon 2020 research and innovation program under grant agreement No 792210 (GEOFIT).
Raw data is available for download here.
Scientific Paper published at Smart Structures and Systems, volume 30, issue 3 2022
Title: On site monitoring during nearby drilling operations toward a geothermal power system installation
Language: English
Authors: D. Bortoluzzi (*1), S. Casciati (*1), Lucia Favarelli (*1), M. Francolini (*2)
*1: SIART, SRL
*2: Formerly SIART, SRL
Abstract: Among the approaches to the production of “green” energy, geothermal power systems are becoming quite popular in Europe. Their installation in existing buildings requires an extended, external pipes appendix whose laying operation needs a drilling activities nearby structural skeletons often designed to support static loads only, especially when ancient buildings are targeted {#7}. This contribution reports and discusses the experimental results achieved within a specific case study within the European project GEOFIT. In particular, standard accelerometric measurements in and nearby a single-story reinforced concrete building are collected and analysed in the absence of drilling (pre-drilling) and during drilling activities (drilling phase) to monitor the structure response to the external source of vibrations related to the excavations phase. The target is to outline automatic guidelines toward installations preventing from any sort of structural damage.
Raw data is available for download here.
Conference paper presented in EACS 2022 – The 7th European Conference on Structural Control held July 10th-13th 2022 in Warsaw, Poland.
Title: The problem of geothermal power installation on buildings: structural building monitoring and assessment during drilling activities
Language: English
Authors: D. Bortoluzzi (*1), S. Casciati (*1), M. Francolini (*2)
*1: SIART, SRL
*2: Formerly SIART, SRL
Abstract: The current European Union (EU) policy aims to increase the use of “green” energies, and within this strategy the exploitation of the geothermal energy is a well promising approach. The European Horizon2020 project GEOFIT (Deployment of novel GEOthermal systems, technologies and tools for energy efficient building retroFITting) aims among the others to deploy and to integrate advanced methods of worksite inspection, ground research, and building structural monitoring, drilling and worksite characterization into advanced geothermal based retrofitting methods.
When dealing with “plants of power production”, one needs to develop a Life Cycle Analysis and to apply a Life Cycle Assessment (LCA) for evaluating any environmental aspects and potential influences throughout the whole life cycle of a product or process or service. The paper first provides a preliminary discussion on this aspect. Then it focuses attention on a pilot site made available within the GEOFIT Consortium. The results from a structural monitoring campaign in this pilot site before and during the drilling operations associated to the implementation of the geothermal power system are presented discussed.
Raw data is available for download here.
Presentation of GEOFIT at the European Shallow Geothermal Days 2022
Title: Introducing GEOFIT: Easy-to-install, economical and enhanced geothermal systems for energy efficient building retrofitting
Language: English
Author: Henk Witte (Groenholland)
Summary: GEOFIT is an EU-funded research project focussing on the use of shallow geothermal energy for heating and cooling of buildings. It specifically addresses retrofitting, therefore tackling the specific issues one has to face while designing, installing and operating a geothermal system in an existing building (Ground source Heat Exchanger – HEX, Heat Pump – HP, heating and cooling emission system).
GEOFIT aims to answer to the challenge by developing easy-to-install and efficient underground coupling systems, including historical buildings, to make geothermal energy a standard source of heat and cold in building renovation. Such systems consider the difficulties in drilling in built environments. The project also develops improved, more cost-efficient and less environmental-impacting heat pumps to optimize the use of the energy generated by geothermal systems. GEOFIT embraces the whole path of design-site survey-installation-operation. It particularly investigates coupling between GHEX and HP and between HP and heating/cooling emission systems, thus providing guidelines for planners to reduce errors and ensure high performance of the systems.
To aid the selection of different Ground Heat Exchanger technologies and support the design, an advanced integrated design toolkit is developed. This engineering toolkit allows the engineer to design and compare the different GHEX (vertical, horizontal, slinky and spiral/earth basket type) in an integrated model framework. The approach in the engineering toolkit is based on the well-known finite line source approach and implements G-functions to speed calculation. New finite line source models have been developed and validated for spiral type heat exchangers. Other advances include detailed (temperature dependent) fluid properties correlations and inclusion of seasonally varying temperature gradients. The finite line source model for spiral heat exchangers has been validated with sand-box experiments and CFD calculations.
Article published in Energies
Title: Performance Analysis of a Geothermal Radiant Cooling System Supported by Dehumidification
Datasets: “Building energy simulation data results” and “Acquired data from existing and/or new installed meters or from existing BEMS (pre intervention EcoSCADA monitoring data)” – Raw data is available upon request. Follow the link and fill the request form.
Language: English
Authors: Henrikki Pieskä (*1) , Adnan Ploskić (*1,2), Sture Holmberg (*1), Qian Wang (*1,3).
*1: Division of Sustainable Buildings, School of Architecture and the Built Environment, KTH Royal Institute of Technology, Brinellvägen 23, SE, 10044, Stockholm, Sweden
*2: Bravida Holding AB, Mikrofonvägen 28, SE, 12637, Hägersten, Sweden
*3: Uponor AB, Hackstavägen 1, SE, 72132, Västerås, Sweden
Abstract: Space cooling demand is increasing globally due to climate change. Cooling has also been linked to all 17 sustainable development goals of the United Nations. Adequate cooling improves productivity and thermal comfort and can also prevent health risks. Meanwhile, policy initiatives such as the European Union’s Green Deal require participants to cut greenhouse gas emissions and reduce energy use. Therefore, novel cooling systems that are capable of efficiently producing high levels of thermal comfort are needed. Radiant cooling systems provide a design capable of fulfilling these goals, but their application in hot and humid climates is limited due to the risk of condensation. In this study, we compare the performances of radiant cooling systems with and without dehumidification. The studied systems are supplied by geothermal energy. The study is conducted using building energy models of a small office building belonging to a three-building school complex located in Sant Cugat near Barcelona in Spain. The studied location has a Mediterranean climate. The simulations are conducted using IDA Indoor Climate and Energy 4.8 simulation software. The results show that the radiant cooling system with dehumidification (RCD) produces considerably improved thermal comfort conditions, with maximum predicted mean vote (PMV) reached during the cooling season being 0.4 (neutral) and the maximum PMV reached by the radiant cooling system without dehumidification (RC) being 1.2 (slightly warm). However, the improved thermal comfort comes at the cost of reduced energy and exergy efficiency. The RCD system uses 2.2 times as much energy and 5.3 times as much exergy as the RC system. A sensitivity analysis is also conducted to assess the influence of selected input parameters on the simulation output. The results suggest that maximising dehumidification temperature and minimising ventilation flow rate can improve the energy and exergy efficiency of the RCD system while having a minor effect on thermal comfort.
Journal Paper published in Journal of Building Engineering
Title: Thermodynamic and Thermal Comfort Performance Evaluation of Two Geothermal High-Temperature Cooling Systems in the Mediterranean Climate
Datasets: “Building energy simulation data results” and “Acquired data from existing and/or new installed meters or from existing BEMS (pre intervention EcoSCADA monitoring data)” – Raw data is available upon request. Follow the link and fill the request form.
Language: English
Authors: Henrikki Pieskä (*1) , Cong Wang (*1,2), Behrouz Nourozi (*1), Adnan Ploskic (*1,3), Qian Wang (*1,4).
*1 Division of Sustainable Buildings, School of Architecture and the Built Environment, KTH Royal Institute of Technology, Brinellv¨agen 23, SE-10044, Stockholm, Sweden
*2 College of Urban Construction and Safety Engineering, Shanghai Institute of Technology, 201418, Shanghai, China
*3 Bravida Holding AB, Mikrofonv¨agen 28, SE-12637, Hägersten, Sweden
*4 Uponor AB, Hackstavägen 1, SE-72132, Västerås, Sweden
Abstract: The European Commission aims to reduce the greenhouse gas emissions of the European Union’s building stock by 60% by 2030 compared with 1990. Meanwhile, the global demand for cooling is projected to grow 3% yearly between 2020 and 2050. High-temperature cooling systems provide cooling with lower exergy use than conventional cooling systems and enable the integration of renewable energy sources, and can play a crucial role in meeting the growing cooling demand with less energy use. The aim of this study is to analyse and critically evaluate two high-temperature cooling systems in terms of their energy and exergy use in a case study. We also consider thermal comfort performance, CO2 emissions, and sensitivity to changing operating conditions. The two systems considered are a mechanical ventilation system with heat recovery combined with geothermal cooling (GeoMVHR) and a radiant cooling system with ceiling panels connected to the same geothermal cooling (GeoRadiant) system. The study is conducted using building energy models of a typical office building belonging to a three-building school complex located in Sant Cugat near Barcelona, Spain. IDA ICE 4.8 simulation software was used for the simulations. The results show that the two different installations can produce near-identical thermal comfort conditions for the occupants. The GeoRadiant system achieves this result with 72% lower electricity use and 60% less exergy destruction than the GeoMVHR system. Due to the higher electricity use, the CO2 emissions caused by the GeoMVHR system are 3.5 times the emissions caused by the GeoRadiant system.
Towards Discrete Element Modelling of Rock Drilling
Author: Wessling, Albin
2021 (English)Licentiate thesis, comprehensive summary (Other academic)
The method of percussive rotary drilling is recognized as the most efficient method for hard rock drilling. Despite the clear advantages over conventional rotary meth-ods, there are still uncertainties associated with percussive rotary drilling. For geothermal applications, it is estimated that 50 % of the total cost per installed megawatt of energy is associated with drilling and well construction, with drill bit wear being a predominant cost factor. Numerical modelling and simulation of rock drilling, calibrated and validated towards rigorous experiments, can give insight into the rock drilling process. This thesis is focused on the prerequisites of numer-ical simulations of rock drilling, i.e. the development of a numerical model and experimental characterization of rock materials. A new approach for modelling brittle heterogeneous materials was developed in this work. The model is based on the Bonded Particle Method (BPM) for the Discrete Element Method (DEM), where heterogeneity is introduced in two ways. Firstly, the material grains are rep-resented by random, irregular ellipsoids that are distributed throughout the body. Secondly, these grains are constructed using the BPM-DEM approach with mi-cromechanical parameters governed by the Weibull distribution. The model was applied to the Brazilian Disc Test (BDT), where crack initiation, propagation, coalescence and branching could be investigated for different levels of heterogene-ity and intergranular cement strengths. The initiation and propagation of the cracks were found to be highly dependent on the level of heterogeneity and cement strengths. In the experimental study, the static and dynamic properties of two rock materials – Kuru grey granite and Kuru black diorite – were obtained from uniaxial compression and indirect tension tests. A Split-Hopkinson Pressure Bar was used to obtain the dynamic properties. Using high-speed photography with frame rate 663,000 fps, the crack initiation and propagation could be studied in de-tail, and the full-field exterior deformation fields of the samples were evaluated by using digital image correlation. From the high-speed images, the onset of unstable crack growth was detected. The crack-damage stresses, associated with unstable crack growth, was approx. 90 % of the peak strength in the dynamic compression tests, whereas the tensile crack-damage stress was approx 70 % of the tensile peak strength.
Luleå: Luleå University of Technology, 2021.
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
Raw data is available for download here.
Article published in Computational Particle Mechanics, Springer, 2021.
Title: A statistical DEM approach for modelling heterogeneous brittle materials
Language: English
Authors: Albin Wessling (*1), Simon Larsson (*1), Pär Jonsén (*1), Jörgen Kajberg (*1)
*1: Division of Mechanics of Solid Materials, Luleå University of Technology, 97187 Luleå, Sweden
Abstract: By utilizing numerical models and simulation, insights about the fracture process of brittle heterogeneous materials can be gained without the need for expensive, difficult, or even impossible, experiments. Brittle and heterogeneous materials like rocks usually exhibit a large spread of experimental data and there is a need for a stochastic model that can mimic this behaviour. In this work, a new numerical approach, based on the Bonded Discrete Element Method, for modelling of heterogeneous brittle materials is proposed and evaluated. The material properties are introduced into the model via two main inputs. Firstly, the grains are constructed as ellipsoidal subsets of spherical discrete elements. The sizes and shapes of these ellipsoidal subsets are randomized, which introduces a grain shape heterogeneity Secondly, the micromechanical parameters of the constituent particles of the grains are given by the Weibull distribution. The model was applied to the Brazilian Disc Test, where the crack initiation, propagation, coalescence and branching could be investigated for different sets of grain cement strengths and sample heterogeneities. The crack initiation and propagation was found to be highly dependent on the level of heterogeneity and cement strength. Specifically, the amount of cracks initiating from the loading contact was found to be more prevalent for cases with higher cement strength and lower heterogeneity, while a more severe zigzag shaped crack pattern was found for the cases with lower cement strength and higher heterogeneity. Generally, the proposed model was found to be able to capture typical phenomena associated with brittle heterogeneous materials, e.g. the unpredictability of the strength in tension and crack properties.
Article pulished in Building and Environment (2020)
Title: Design Requirements for Condensation-Free Operation of High-Temperature Cooling Systems in Mediterranean Climate
Datasets: “Building energy simulation data results” and “Acquired data from existing and/or new installed meters or from existing BEMS (pre intervention EcoSCADA monitoring data)” – Raw data is available upon request. Follow the link and fill the request form.
Language: English
Authors: Henrikki Pieskä (*1) , Adnan Ploskić (*1,2), Qian Wang (*1,3).
*1: Division of Sustainable Buildings, School of Architecture and the Built Environment, KTH Royal Institute of Technology, Brinellvägen 23, SE, 10044, Stockholm, Sweden
*2: Bravida Holding AB, Mikrofonvägen 28, SE, 12637, Hägersten, Sweden
*3: Uponor AB, Hackstavägen 1, SE, 72132, Västerås, Sweden
Abstract: Radiant cooling systems are a subject of increasing scientific interest due to their efficiency and ability to use high-temperature cooling sources. In hot and humid conditions, they have generally been studied in combination with dehumidification systems. For retrofit projects, a control system that would eliminate the need for dehumidification would be beneficial. In the present study, a passive geothermal-based radiant high-temperature cooling system is studied in a Mediterranean climate. The system is operated with supply water temperature control using dew point temperature as a controlling variable. The system’s performance is compared with that of an all-air cooling system. The systems are evaluated using IDA-ICE building energy simulations, validated with on-site measurement data. The results show that the radiant cooling system produces the same level of thermal comfort with 40% lower energy use and 85% lower exergy consumption than the all-air system. The risk of condensation limits the cooling capacity of the radiant cooling system. Consequently, insufficient cooling capacity causes thermal discomfort for the occupants due to the operative temperature exceeding 26 ◦C.
This project has received funding from the European Union’s H2020 programme under Grant Agreement No. 792210.