How a sensitive analysis on the coupling geology and borehole heat exchanger characteristics can improve the efficiency and production of shallow geothermal plants

Knowledge 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

Dynamics and conceptual model of the Rossena castle landslide (Northern Apennines, Italy)

In the Northern Apennines there are many historical villages and castles, which are of great value and represent a cultural heritage of great importance. Their presence within a territory greatly affected by landslide hazards creates, in many circumstances, the need to solve problems of land management and to act for the preservation of historical monuments. </p><p style='line-height: 20px;'> This paper describe an interesting landslide, failed during the night of 28 February 2004, that involved the village of Rossena: the failure damaged the village (Fig.&nbsp;1), the road and the fields down to the stream but, fortunately, the castle just upslope the village was not involved at all. </p><p style='line-height: 20px;'> The 10th century massive castle of Rossena stands on the top of a cliff at about 500 m a.s.l., on the border between the provinces of Parma and Reggio Emilia, and it is surrounded by a small ancient village. The castle of Rossena is the best preserved stronghold of the Longobard times, enlarged and reinforced in the tenth century and partially rebuilt by Bonifacio, the father of Matilda of Canossa (the Vice-Queen of Italy and probably the most important woman in the Middle Ages) as a defensive structure guarding the Enza Valley. In addition, at Conossa, very close to Rossena, there was the meeting between Pope Gregory VII and the Emperor of Germany Henry IV, during the historical event known as 'fight for the investitures'. For these reasons, the area of Rossena is one of the most relevant from a historical point of view in the entire western part of the Emilia Romagna Region and it also has a high value as a geosite (Coratza et al., 2004). </p><p style='line-height: 20px;'>&nbsp;</p

Ultrasonic equipment aimed to detect grouting homogeneity in geothermal heat exchangers

The purpose of this study is to assess homogeneity and integrity of cementing grout in vertical borehole heat exchangers used for geothermal heat pumps using an ultrasonic non-destructive test. The used testing equipment, TUC (Ultrasonic Test to certificate grouting Continuity), is based on an ultrasonic system able to generate and record wave propagation from the inside of heat exchangers to the surrounding (cementation and soil, possibly). Differences in signal characteristics of the recorded waves along the pipe can indirectly provide useful information to evaluate the successful realization of the well cementation in terms of vertical homogeneity and continuity. Both laboratory and field tests have been evaluated and are hereafter presented to verify tests effectiveness and discuss eventual limitation of the proposed approach