Numerical investigations of the tunnel environment effect on the performance of energy tunnels

摘要

Energy tunnels having lining equipped with heat exchangers as heat or sink resources have gained increasing popularity in recent decades to satisfy the energy demand. This study focuses on numerical simulations based on the continuous operation of thermally activated segmental linings. It aims to analyze the tunnel environment effect on the energy performance of a typical metro tunnel section and estimate the concrete lining role in the heat transfer. Two approaches are expressed to access the system energy efficiency and validated against existing literature data. The numerical results show the influence of the temperature difference between the tunnel air and the circulating fluid and the heat transfer coefficient on the system energy efficiency, which indicates that energy is mainly exchanged with the tunnel environment in winter, but in summer, the surrounding ground plays a major role for the studied case. When evaluating the geothermal potential of an energy tunnel, it is necessary to undertake an initial assessment not only on the ground conditions, but also on the tunnel environment and the concrete lining thermal properties.(c) 2021 Elsevier Ltd. All rights reserved.