A solar-collecting system for tunnel thermal storage

Despite being resilient geostructures, a non-negligible amount of tunnels worldwide are approaching the end of their service life. This is mainly evident in Italy due to the agedness of most of the underground built environment. To address this issue, a plan to renovate existing motorway tunnels is underway to extend their serviceability. In this framework, a novel energy tunnel based anti-icing solar-collecting system is being implemented on a full scale in a motorway tunnel undergoing renovation. This envisages a geothermal serpentine embedded in the rehabilitated lining connected to other heat exchanger piping placed within the motorway pavement. Working in free-cooling mode, the system can take advantage of the thermal inertia of the ground behind the lining to store the solar heat collected through the motorway pavement, acting as a solar collector. The aim is to use this heat for anti-icing operations during the harshest periods of winter seasons. This paper will illustrate the laboratory testing and numerical modelling needed to preliminarily assess the functionality of the energy tunnel based anti-icing solar-collecting system.