关键词: 地埋管管群, 动态负荷 , 土壤温度场, 传热, 模型

Abstract: The comparison of the infinite line source model, finite line source model (FLS) and moving finite line source model (MFLS) of borehole heat exchangers (BHEs) shows that the axial effects and groundwater flow have some effects on BHEs. Based on the temperature superposition principle and dynamic loads, the heat transfer models for multi-boreholes are established, combined with typical annual dynamic load model, the long-term multi-borehole heat transfer is analyzed with FLS and MFLS. The results show that the center temperature of BHEs fields calculated with FLS increases fast and heat exchanger capacity attenuation should be taken into account for a long-term running. With MFLS, reasonable optimization strategy should be used to avoid fast increase of downstream soil temperature, and stable heat transfer ability should be adopted for design to prevent inadequate capacity of late runtime. The temperature rise at typical points in BHEs filed with three-day dynamic loads shows that the operation adjustment could significantly alleviate soil temperature rise and especially reduce the heat accumulation in downstream tubes, which is very good for recovery of soil heat exchanger capacity.

Key words: multi-boreholes, dynamic load, soil temperature field, heat transfer, model