Adam BELA, Laszlo TOTH

Heat technical masuring of ground for vertical borehole heat exchangers installations

Nowadays in Hungary the utilization of vertical borehole heat exchanger systems is increasingly used to buildings heating and cooling by ground-source heat pumps. The eighth largest ground-source heat pump system of Europe has been established by the TELENOR office building in 2007, with 18,000 m BHE. A trial drilling was carried out during the start of the construction on the area. This provided data to scale the system, in this the borehole geophysical measurements and the Thermal Response Test (TRT) were executed. The studies began with a survey of undisturbed ground condition, but since then the ground temperature is recorded, i.e. the system impact on the geological environment. It be ascertained that the BHE field caused 5-6°C temperature change by the 100 m deep BHEs in long-term heating and cooling periods (directly next to the pipe) in comparison with the undisturbed ground temperature. The heating results in 5,74°C temperature decrease close to the active BHE, and 4,30°C temperature increase caused by cooling. 3,5 m away the active BHE the heating causes 0,28°C temperature decrease, and the ground is warmed by 0,08 ° C because of the cooling influence. Temperature change is not measurable 6.6 m away the boreholes. 7 m grid is recommended to the layout of the BHEs.

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