Concept, design and testing of an innovative geothermal heat exchanger installed at the Brenner Base Tunnel

The article presents the design, installation and testing of an innovative geoexchanger, tailored for tunnels excavated by TBM. The prototype was developed through the joint efforts of BBT-SE, involved in the construction of the Brenner Base Tunnel connecting Italy and Austria, and the University of Bologna. It consists in a modular horizontal closed-loop system located in the lining invert space dedicated to the drainage water flow in the exploratory tunnel. Due to the manner in which it functions, based on the heat exchange process with the drainage water, and to its compact design and straightforward installation procedure, the prototype was called "Smart Flowing". Modules were built outside and aflerwards assembled in the tunnel system, concurrently to the advancement of the TBM. Specific tests were performed, simulating a heat pump conditioning system's operation in both heating and cooling modes, to prove the prototype's reliability and efficiency. Finally, a preliminary economic and environmental potential assessment was carried out.