Numerical study of soil heat and moisture migration in seasonal ground heat storage

Heat and moisture transfer is an important factor leading to soil drying shrinkage and heat transfer attenuation in the process of seasonal soil heat storage with high temperature. The purpose of this study is to establish a numerical model to explore the characteristic of heat and moisture migration in heat storage soil. The numerical model is verified by the experimental data. In this study, two months heat storage with high-temperature (80℃) and five months heat extraction with low-temperature (20℃) seasonal operation period was simulated, and the changes in the temperature and moisture content of the heat storage soil were analyzed. After a seasonal period, the mean temperature in the backfill and the original soil would increase. The moisture content in original soil would increase, while the moisture content in the backfill would decrease. For the typical backfill with 0.4 m diameter, the obvious heat and moisture migration phenomenon only occurs in the backfill and the part of the original soil close to the backfill.