An innovative Borehole Heat Exchanger configuration with improved heat transfer

•A protection system for vertical probes in closed loop geothermal systems is proposed.•In the annulus between probes and protection system there is a liquid.•This system leads to an increase in the heat transfer rate.•TRCM scheme, with addiction of protection system, is proposed for single U tube borehole.

This paper presents an innovative Borehole Heat Exchanger (BHE) configuration in which the vertical probes are immersed in an artificial fluid, contained in a case separated from the ground by the usual filling material. This system leads to an increased heat transfer within the borehole due to the onset of induced natural convection in the annulus between the protection system and the vertical probes. The related TRCM schemes are presented for grouting filled conditions.