Numerical Simulation of Heat Transfer in Saline Soil Energy Pile Groups

To reduce adverse environmental impacts and boost renewable energy utilization, energy pile technology bridges traditional energy systems and building structures, offering an innovative route for urban low-carbonization. Currently, research on energy piles is confined to conventional non-saline soil, with insufficient exploration of their heat transfer performance in saline soil. Thus, this paper studies the latter based on prior non-saline soil research. The heat transfer performance of pile groups is analyzed in COMSOL Multiphysics by varying the pile diameters, spacing, configurations, and numbers. The findings show that the central pile undergoes the most significant thermal interference, with its water temperature on the 30th day being 1.26 °C higher than that of a single pile. A pile spacing equal to four times the diameter greatly reduces thermal interference, and a spacing of six times the diameter renders the accumulated heat effect insignificant. Additionally, a plum-shaped pile arrangement reduces energy pile group interference effectively, with higher heat transfer capacity than the traditional square arrangement. Increasing pile diameter only benefits heat transfer greatly in the first 10 days, as thermal interference offsets the advantage of expanded heat transfer area from larger diameters.