Influence of silicon carbide incorporation on the macroscale and microscale heat transfer characteristics of energy piles

This paper explores the impact of silicon carbide (SiC) incorporation on the heat transfer capabilities of energy piles by deploying a suite of methodologies that includes standard specimen tests, scanning electron microscopy (SEM) analysis, and indoor modeling tests. The findings indicate that SiC doping enhances the thermal conductivity, compressive strength, and flexural strength of the pile material at the macroscopic level. Whereas, the doping of SiC forms a new cluster structure in the concrete compared to that without SiC at the microscopic scale. In contrast to conventional energy piles, the SiC-enhanced energy piles exhibit superior heat transfer efficiency and accelerated temperature growth rates. In addition, SiC helps to mitigate the heat accumulation around the heat exchange tube. The temperature-induced upward displacements at the top of the SiC-enhanced energy pile increase at elevated temperatures, while the additional displacement reduces when the pile top is loaded. On the contrary, the temperature induces downward displacements as well as the top decreases during the cooling process, with heavier loads resulting in large settlements. Finally, this research assists in establishing an experimental foundation for the design and implementation of SiC-enhanced energy piles.