Innovative Helicoidal Ground Source Heat Exchanger Coupled with a New Timesaving Installation Technique

Abstract

To increase the awareness on sustainable shallow geo-energy solutions the European commission funded the H2020 project „Cheap-GSHPs“. The focus of the project are new developments on all components (accessibility of the heat source, ground source heat exchanger, heat pump, software application) of shallow geothermal applications in terms of innovation but also in terms of saving costs. On several real demonstration sites, the new techniques were tested, monitored and evaluated. Under the umbrella of this project, one purpose was the development of vertical helicoidal ground source heat exchangers to fit in boreholes with a diameter of 350 mm. Therefore the design of the spiral collector HELIX© (REHAU AG & Co. KG) was changed in its dimension and in its base material. The new prototype was mounted at selected demonstration sites of the project. In Erlangen, Germany four prototypes were installed down to a depth of 8 m. The boreholes were drilled using the new engineered “enlarged easy-drill technique” which combines hollow auger drilling with a supporting casing in order to strongly reduce the installation time of the ground source heat exchanger and the consecutive grouting process. This paper should evaluate the advantages and barriers of this novel combination of helicoidal ground source heat exchanger and drilling technique. CHEAP-GSHPs project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 657982.