Numerical investigation of the backfilling material thermal conductivity impact on the heat transfer performance of the buried pipe heat exchanger

2019 3rd International Workshop on Renewable Energy and Development

能源学;生态环境科学

Song, Xiao-Qing^1^2 ; Jiang, Ming^1^2 ; Qin, Peng^1^2

Geo-engineering Investigation Institute of Guizhou Province, Guiyang

550008, China^1

111 Geological Party, Guizhou Bureau of Geology and Mineral Exploration and Development, Guiyang

550008, China^2

关键词: Backfill material;    Heat exchange capacities;    Heat exchange efficiency;    Heat transfer efficiency;    Heat transfer process;    Numerical investigations;    Outlet-water temperatures;    Shallow geothermal energies;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/267/4/042010/pdf
DOI  :  10.1088/1755-1315/267/4/042010

学科分类：环境科学（综合）

来源: IOP

【 摘 要 】

Based on the in-site thermal response experiment of a shallow geothermal energy plant in Guiyang, a model characterizing the heat transfer process between well-backfill material-ground material of a buried double vertical U-tube underground heat transfer system is established. Moreover, the influence of the thermal conductivity of the backfill material on the heat exchange efficiency for the summer condition is investigated. Results show that the maximum error between the outlet water temperatures calculated from model and obtained from field testing is less than 1.7%, which verifies the correctness of the model. When the thermal conductivity of the backfill is low, the heat in the buried heat exchanger is basically limited in the domain of the borehole. Furthermore, it is observed that the heat transfer efficiency increases, as the thermal conductivity increases. When the thermal conductivity of the backfill is close to that of the surrounding rock, the heat transfer efficiency increases in a faster rate. However, when the thermal conductivity of the backfill further increases, the heat transfer efficiency insignificantly increases. It is found that higher thermal conductivity of the backfill material has limited improvement on the heat exchange capacity of the buried pipe.