Comparision of Effective Thermal Conductivity Values in Borehole Heat Exchangers from Thermal Response Tests with Theoretical Rock Conductivity Values

The article presents an analysis of the thermal conductivity coefficient determined using three methods. One is based on data taken from the literature, while the other is based on the results obtained from field thermal response tests. Third one is something between this two. The analysis covers the results obtained for five different boreholes of varying depths, in which seals with increased conductivity and different trade names were used. In one location, gravel with a grain size of 8 mm to 16 mm was used as a seal. Each of the boreholes has a different location, which is also related to different geological structures.