Use of a temperature-measuring chain for the reconstruction of the vertical thermal disturbance induced by an open-loop groundwater heat pump system

Open-loop groundwater heat pumps (GWHP) currently represent one of the most energy-efficient and environmentally friendly air-conditioning systems for densely urbanised areas. Depending on the use mode, energy can be extracted or injected into a shallow aquifer. Among the technical aspects associated with GWHPs that need to be constantly controlled, there is the development of a thermally affected zone (TAZ) around injection points. The environmental impact extent is strongly influenced by the water flow rates and the re-injection modalities. The process of setting up an adequate monitoring system is fundamental for the proper reconstruction of TAZ propagation modes, during each plant-operating season. The work aims to analyse the potentialities of using a new sophisticated water temperature-measuring chain (type PT1004/ Pt) as a monitoring tool for the identification of the vertical stratigraphic intervals of the Turin shallow aquifer that are more affected by the thermal disturbances produced by the Politecnico di Torino’s open-loop GWHP system. The installation of such a monitoring instrument, together with the information deriving from the application of the data analysis proposed, can contribute the most in understanding the adequacy of the constructional characteristics of an open-loop system re-injection well to properly disperse vertical thermal perturbations.