Analysis of geological parameters for optimization of geothermal probes applied to heat pumps: individuation of a technical and procedural iter

摘要

The geothermal heat pump systems have been developed in Italy only during the last few years and today only some regions are investing in this field. In particular, the Tuscany Region and the Autonomus Bolzano Province have promoted the study of these systems with the objective of being able to promote and to disclose in the time this technology. A fundamental aspect for a oculata planning and a greater knowledge of the real predisposition of the territory to the installation is sure the acquaintance of the specification of the geological, geophysical, geotechnical and hidrogeological systems and the parameters that enter at stake. The fundamental parameter in a position to discriminating from a point of view not only economic but also of real thermal yield is the thermal conductivity that the determinated site is able to offer.udThis research examines the essential elements that they characterize a system of geothermal heat pump system. It has been to such respect important to study at first the various type of systems from a technical-engineering point of view that of principle operation. In a second phase, the parameters were characterized to consider in phase of thermal characterization, therefore the study of the heat conductivity, the transmission of heat between probe and land, the thermal stability and the thermal behavior of the ground. In particular, regarding the study of the heat conductivity, in the Capitol 3 are given the tools used for the acquisition of such parameter through investigations in the laboratory and in situ.udSuccessively the normatives elements that regulate the phases of authorization were characterized and analyzed, afterwards planning and installation of the heat pumps systems in the various international and national contexts were considered. A panoramic pre-emptive of the normative picture of the Nations and Regions was drawn to the vanguard in the field of geothermal energy to low and the lowest entalpy. This was dictated by the requirement to define the problematic ones met from the agencies that have legislated in matter and to put of in evidence virtues and criticality. The checks carried out both in terms of legal and procedural provided anudinspiration for the creation of authorization processes and procedures for the installation of various types of geothermal heat pump systems in various geological contexts, in order to assess the possible impacts that these systems can cause on the environmental matrices. Central part of the research project is the study of the heat conductivity, parameter key for the development of a useful cartography in this field. It was decided to perform a literature search of that parameter, in order to process and then compare the data of thermal conductivity obtained from detailed investigation carried out in a pilot site and found through the stratigraphy. In fact, nowadays the available data measured on lithologies of the Italian territory are few and hard to find. The literature research has allowed later to thermally classify the lithostratigraphic units of the geological legend of Sardinia Region, in scale 1:10000, one of the few regions to boast of an updated geological territorial Continuum. The performed research is based on the possibility of drawing up maps of the thermal conductivity from the investigation and trying different methods, ultimately, to compare the two approaches. The first method concerned a detailed investigation of the pilot site located in proximity of Lago Baratz (Municipality of Sassari) through a geological and hidrogeological framework, a pedologic survey and at last, investigations of geoelectrical type. The detailed study has afforded to frame the site potentially interesting to the installation of a system being afforded to characterize from a thermal point of view the area. Therefore, it has been possible to calculate the value of thermal yield for 1800 – 2400 hours of operation of the system in modality cooling and heating.udBy means of the second method of calculation, it was considered appropriate to disclose a test personally conducted in the territory of the Arezzo Province. Thus, it is reported below an example of processing of the data of thermal conductivity from the stratigraphic information. Giving the high number of information (about 12566 stratigraphic data points), it was decided to perform a first test in order to verify and consolidate the processing procedure.udIn the Chapter 7 all the passages executed for the elaboration of the thermal conductivity data from the stratigraphic information for the provincial territory are illustrated. Three maps for the depths of interest of 30, 60 and 100 meters Were elaborated. Successively the respective papers of the errors were calculated, allowing to divide the province territory in areas for which it can be identified different planes of address to be followed in the process of thermal characterization. The last chapter contains a possible synthesis of a procedural iter initially for defining the parts that enter as stake in phase of realization of a system. They will follow some detailed lists reported to the criteria to follow, in sensitive areas, for the study and the control from a thermal point of view, of a potentially apt site to the installation of a system The entire research aims to set an example as well as the application of geological information at a scale of detail, the stratigraphic information and spread knowledge of the parameters involved can be combined to create thematic maps useful for public authorities and citizens.