1,709 research outputs found
Optimisation of geothermal resources in urban areas
No full textL'abstract è presente nell'allegato / the abstract is in the attachmen
Testing of a Novel Energy Wall System in Torino
No full textThe need of renewable energy sources is increasingly pushing the design of new and renovated buildings as a result of compelling regulation in the construction sector. On the one hand shallow geothermal energy is suitable as a sustainable and distributed energy source. On the other hand, significant installation cost related to drilling of traditional installations represent a ham- pering factor. Energy geostructures as piles, diaphragm wall, tunnels and anchors include these costs in the construction of primary or secondary struc- tural elements. Major part of building heritage in urban areas present under- ground levels that can be equipped with heat exchangers.
This paper introduces the concept of a modular very shallow geothermal exchanger as part of a Heating, Ventilation and Air Conditioning (HVAC) system. The system is conceived to externally equip with heat exchangers the earth-contact area of underground walls that are generally widely available in residential and commercial buildings. An experimental site consisting of three modules of the above mentioned technology was designed by the authors and installed in an office building in Torino (Italy). Pipes were placed externally to the basement wall in two different arrangements. A large number of sensors were placed to monitor the additional stresses and strains on the wall and the thermal regime of the partly saturated ground volume involved in heat exchange. A comprehensive view of the main components of the prototype and the related monitoring system are given together with preliminary thermal performance results
Sistema energetico contro terra e metodo per scambiare calore tramite tale sistema (Geothermskin)
No full textOttimizzazione nell'uso della risorsa geotermica superficiale nei centri urbani
No full textLa crescente domanda di energia rinnovabile nel campo del riscaldamento e raffrescamento degli edifici ha sostenuto un incremento della presenza di impianti geotermici a bassa entalpia. Nei grandi centri urbani italiani ed europei si concretizza dunque il rischio di interferenze tra installazioni che mettono a rischio l’investimento della loro realizzazione.
Nella nota, a partire dalle evidenze del caso studio della Città di Torino, sono discusse e analizzate le prospettive e i metodi per gestire queste problematiche nell’ottica di una pianificazione equa e razionale nell’uso della risorsa geotermica. L’integrazione tra i metodi analitici di valutazione del potenziale e la modellazione numerica termo-idraulica (T-H) delle effettive condizioni termiche del sottosuolo viene individuata come approccio privilegiato per l’ottimizzazione nell’utilizzo della geotermia superficiale alla scala urbana
rOGER: A method for determining the geothermal potential in urban areas
No full textShallow geothermal energy is increasingly adopted for heating and cooling purposes because of the short payback time of initial installation investments. As a result, a relevant concentration of Ground Heat Exchangers is being experienced in urban areas. Planning issues thus arise to manage interferences and optimize the use of underground heat resources without depletion, harm to the environment nor efficiency losses on heat pumps or plant oversizing. This study provides a rational approach to optimise geothermal resources based on the use of Geographic Information Systems and transient 3D Thermo-Hydro numerical models. An optimised semianalytical formula for the assessment of Borehole Heat Exchangers geothermal potential in hydrodynamic conditions is developed through a parametric numerical study. The long-term performances of BHE subjected to groundwater velocity in the range of 0 to 1 m/day were analysed with multiple aquifer thermal parameters. This analytical expression allows a fast and accurate assessment of the potential even in large areas without leading to excessively conservative evaluations. This may serve designers in the preliminary sizing of installations and city planners in the development of appropriate policies for the promotion and management of shallow geothermal resources. An example of the application to the central district of the city of Turin (Italy) is also shown
Evaluating borehole heat exchanger long term potential including the influence of advection and dispersion
No full textShallow geothermal energy (SGE) applications are gaining growing attention in the renewable energy sector because of high efficiency, worldwide availability and low environmental impact. Significant increase in the number of installations is envisaged as a result of energy policies and European Directives. Thus, the reliable evaluation of the available exchangeable energy, namely the geothermal potential, is of primary importance to support energy planning policies.
A variety of factors influences the geothermal potential of a specific area, including ground properties, installation features, the presence of groundwater flows and the site temperature. Different approaches to assess the geothermal potential have been proposed, both with reference to the regional scale and to the city or district scale [1]. These are based either on numerical simulations or on analytical closed form solutions. The latter are particularly suitable to be adopted in Geographical Information Systems (GIS) for geothermal potential mapping purposes and are being used in practice. Most available methods consider heat conduction only. This may lead to a conservative evaluation of the potential and to a non-optimised installation planning. This is particularly true in urban areas, where space scarcity is a key factor. Furthermore, these areas may present high density of geothermal installations [2], leading to overexploitation or conflicting use of the resource. Assessment of the geothermal potential at the natural state [3] in these cases is of limited use and can lead to wrong estimation of the actual working load of a new installation.
The need arises to develop methods able to capture real and actual geothermal potential which result from the cumulative effect of both natural and anthropogenic boundary conditions. This study was accomplished to implement advective and dispersive contribution and heterogeneous temperature boundary conditions in the existing analytical approach developed by [4]. This latter is considered very suitable for mapping borehole heat exchanger (BHE) potential both at regional and city scale. To consider the presence of groundwater flow and its influence on the heat exchange, a numerical parametric study was carried out. Conditions explored include temperature vertical heterogeneities and various groundwater flow velocities. It was found that, assuming depth-averaged mean parameters and a thermal conductivity equal to the first invariant of the thermal conductivities tensor, a multiplication factor Cgw, function of the ratio between advective and conductive contributions, should be added to the analytical formula [4] in order to provide improved evaluation of the BHE potential
Development and testing of a novel geothermal wall system
No full textShallow geothermal energy systems have the potential to contribute to the decarbonization of heating and cooling demands
of buildings. These systems typically present drawbacks as high initial investments and occupancy of wide areas. In this
study, a novel energy wall system is proposed to overcome the limitations of conventional geothermal applications in urban
areas. The system is characterized by ease of installation, low initial costs and applicability to existing buildings undergoing
energy retrofitting. The paper illustrates the implementation of the prototype of such a system to an existing structure
in Torino (Italy). An overview of the components is given together with the interpretation of an illustrative test carried out
in heating mode. The data from both heating and cooling experimental campaigns allow us to highlight the potential of
the proposed technology. The results suggest that an average thermal power of about 17 W per unit area can be exchanged
with the ground in heating mode, while an average of 68 W per unit area is exchanged in cooling operations. The negligible
impact on the stress–strain state of the wall and the surrounding soil thermal and hygrometric regime is also testified by the
results collected. These aspects are associated with a reduced probability of interferences with other installations in highly
urbanized areas, easiness of installation and affordable cost
Development and testing of an innovative energy wall system in Torino (Italy)
No full textShallow geothermal energy (SGE) is increasingly being regarded as a valuable solution for space heating and conditioning because of high efficiency, diffuse availability and low environmental impact. Significant growth in the number of installations is envisaged as a result of energy policies and European Directives. Indeed, the obligations in the construction sector about the share of energy supply from renewable sources is increasingly pushing the design of new and renovated buildings. On the one hand shallow geothermal energy is suitable as a sustainable and distributed energy source. On the other hand, significant installation costs related to drilling of traditional installations represent an hampering factor. Thermally activating geostructures such as piles, diaphragm wall, tunnels and anchors can allow to include these costs in the construction of the structural elements. Moreover, a large availability of operational surface is represented by new and/or existing building heritage in urban areas as most of them have underground levels that can be equipped with heat exchangers.
This contribution introduces a novel modular very shallow geothermal exchanger as part of a Heating, Ventilation and Air Conditioning (HVAC) system. The system concept allows its application not only to new structures and buildings but also to existing ones. While the low depths interested may penalize the heat exchange rates, on the contrary, extremely low installation costs make the cost-benefit ratio of this new technology extremely interesting and promising.
A first prototype consisting of three modules was designed by the authors and installed in an office building in Torino (Italy). External deployment of pipes to the basement wall in two different arrangements was realized in order to test system efficiency. Due to the experimental nature of
the tests, a large number of sensors were placed to monitor the additional stresses and strains on the wall and the thermal regime of the partially saturated ground volume involved in heat exchange.
Preliminary thermal performance tests were performed together with numerical modelling reinterpretation. On the basis of the first tests and interpretation carried out, it was demonstrated that remarkable heat exchange rates of up to 20 and 27 W/m2 could be injected/extracted from the ground in summer and winter respectively. Furthermore, the monitoring records suggest that extremely low affection of ground thermal status is operated by the system with respect to analogous non thermo-active walls. This evidence is extremely promising in the perspective of wide and dense diffusion of this new shallow geothermal energy system in urban areas where thermal interferences should be limited or avoided
Energy Tunnels for Deicing of a Bridge Deck in Alpine Region
No full textRoads and paved surfaces in cold climate are exposed to the formation of ice and snow deposition. These phenomena are related to high risks for vehicles and road users due to reduced friction. Deicing techniques are up to now mainly based on chemicals, especially salt. These substances induce chemical decay of concrete infrastructure elements and environmental harm. In order to overcome these drawbacks, the use of embedded hydraulic pipes with a hot carrier fluid below the paved surfaces has been proposed in last decades. This circuit can be part of a Ground Source Heat Pump (GSHP) system. Despite a number of examples of this technology have been proposed, very few of them included the application of energy tunnels. This paper focuses on the thermal activation of a tunnel lining in relation to an application for bridge deck deicing. A theoretical case study along an Alpine road has been considered as representative of a common situation of alternated bridges and tunnels. The numerical results show that the thermal activation of the tunnel lining can provide enough heat to keep the paved surface unfrozen even in protracted periods of low external temperatures
TUTELA DEL LAVORO E LIBERTA' D'IMPRESA NEI PROCESSI DI ESTERNALIZZAZIONE
No full textL’elaborato analizza le conseguenze lavoristiche della successione fra imprenditori, muovendo da una ricognizione delle varie tipologie di esternalizzazione con le relative esigenze e principali criticità.
L’indagine si concentra in primo luogo sul trasferimento d’azienda, esaminando la normativa e la giurisprudenza europee per passare poi alla disciplina di diritto interno, alle procedure sindacali e a uno specifico focus sul trasferimento delle aziende in crisi.
Successivamente l’autore si sofferma sull’appalto, prendendone in particolare considerazione gli indici di genuinità, i criteri di distinzione dalla somministrazione illecita di manodopera e la tutela delle maestranze in caso di avvicendamento fra imprese.
Da ultimo, la ricerca approfondisce le c.d. “clausole sociali”, sia di prima che di seconda generazione, valutandone la compatibilità con il diritto eurounitario e con la costituzione nonché riflettendo sui possibili rimedi in caso di loro violazione.The author analyzes the labour consequences of the succession between entrepreneurs, starting from a recognition of the various types of outsourcing with the related needs and main critical issues.
The survey focuses primarily on the transfer of businesses, examining European legislation and case-law and then moving on to internal legislation, trade union procedures and a specific focus on the transfer of companies in crisis.
The author then dwells on the contract, taking into account in particular the indications of authenticity, the criteria of distinction from the illicit administration of labour and the protection of workers in the event of turnover between companies.
Finally, the research deepens the "social clauses", both first and second generation, assessing their compatibility with European law and with the constitution and reflecting on possible remedies in case of their violation
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