Abstract: In order to study the influencing factors for the operation of the medium-deep geothermal buried pipe （MDGBP）, this work analyzed the long-term operation results of the heating system using the MDGBP in Xixian new area. A heat transfer model was established based on the geological data of Guanzhong Area and the depth was 2510 m. The simulation was used to study the influencing factors of operation condition, pipe structure and material of buried pipe. The results show that the average powers of No.1 and No.2 buried pipe in Xixian new area are both more than 310 kW, indicating that they have excellent heat supply capacity. The water temperature at pipe inlet changes obviously with the seasons, which can cause the fluctuation of the heat load and the water temperature of heat pump. In terms of structure, when inner diameter changes from 63 mm to 125 mm, the average water temperature at pipe outlet and heat transfer power decreases by 1.9% and 4.8%, respectively. However, it is not safe if the inner diameter is too small. Considering the safety and the influence of heat transfer, the optimal inner pipe should be ϕ110 × 10 mm; when the outer pipe diameter changes from 168.3 mm to 244.5 mm, the average water temperature at pipe outlet and heat transfer power increases by 3.5% and 9%, respectively. Considering the cost and the influence of heat transfer, the optimal outer pipe should be ϕ 177.8 × 19 mm. In terms of operation conditions, the water temperature at pipe outlet decreases with the increase of flow rate, and the heat transfer power had an opposite trend. With the increase of the inlet water temperature, the outlet water temperature increases and the heat exchange power decreased. In terms of material, the outlet water temperature and heat transfer power increases with the decrease of thermal conductivity of inner pipe and with the increase of the thermal conductivity of cementing material. Considering the change of heat transfer power and cost factors, the inner pipe is recommended in industry with thermal conductivity of 0.42 W/（m·K） and cementing material with thermal conductivity of 3 W/（m·K）.

Key words: geothermal energy, buried pipes, numerical simulation, heat transfer performance

摘要： 为研究中深层地热地埋管运行的影响因素,分析西咸新区中深层地热地埋管供暖系统的长期运行结果,并结合关中地区地质数据,建立深度为2510 m的中深层地埋管换热器全尺寸模型,采用数值模拟法研究实际岩层分布下地埋管的运行、结构和材料因素对其取热能力的影响。结果表明,西咸新区某项目1号地埋管和2号地埋管两个地埋管,其平均取热功率均在310 kW以上,具有优良的取热能力。地埋管进水温度随季节变化明显,并引起用户侧负荷及热泵回水温度的波动。在结构方面,随内管径由63 mm增至125 mm,平均出口水温和换热功率分别降低1.9%和4.8%,但内管径过小将影响内管运行的安全性,综合安全和换热两方面因素,最佳内管径应选取ϕ110 × 10mm规格;随外管径由168.3 mm增至244.5 mm,平均出口水温和换热功率分别增加3.5%和9%,综合成本和换热两方面因素,最佳外管径应选取ϕ 177.8 × 19 mm规格;在运行方面,地埋管出口水温随着流量的增加而减小,换热功率随着流量增加而增加;出口水温随着进水温度的升高而上升,换热功率也随之减小。在材料方面,减小内管导热系数和增加固井材料导热系数均能增加地埋管出口水温和换热功率,考虑换热功率变化和成本因素,在工程中导热系数为0.42 W/（m∙K）的内管和导热系数为3 W/（m∙K）左右的固井材料。

关键词: 地热能, 地埋管, 数值模拟, 取热性能