深井地埋管换热器配置参数模拟计算研究

针对深井地埋管换热系统运行原理,根据地埋管换热器热阻-热容优化模型,建立深井地埋管井孔内、外非稳态柱坐标传热模型。基于环渤海湾盆地埋深1 000～2 000 m热储层水文地质条件,采用双连续介质空间耦合有限元数值计算方法,分析深井地埋管典型配置参数取值对于地埋管换热性能的影响程度。研究结果表明：深井地埋管换热性能随着系统运行时间的推移出现衰减趋势,至供暖季末期(120.0 d)深井地埋管换热量下降20%左右;当深井地埋管循环水量由10增大到60 m³/h时,深井地埋管平均换热量提高150.80 kW,同时循环水泵耗功率也相应提高26.00 kW;深井地埋管埋深由1 600提高到2 400 m时,平均换热量提高113%,耗功率提高50%;当进水套管直径由168提高到299 mm时,平均换热量提高10%,耗功率降低27%。

Numerical study on configuration parameters of the deep borehole heat exchanger

According to the operating principle of the deep borehole heat exchanger(DBHE)system,a unsteady state cylindrical coordinates heat transfer model coupled inside and outside of the borehole was established based upon the modified thermal resistance and capacity model of the buried pipe.Based on the hydrogeological conditions of the thermal reservoir at the depth of 1000-2000 m in the BoHai bay basin,the influence of the configuration parameters on the heat transfer characteristic of the DBHE was evaluated adopting the dual-continuum space coupling finite element method.The results show that the heat transfer characteristic of the DBHE reduced with the system operation time.At the end of the heating season(120.0 d),the heat transfer capacity is around 20%less than at the beginning of operation time(10.0 d).When the quantity of the circulating water is enhanced from 10 to 60 m³/h,the average heat transfer capacity of the DBHE is improved 150.80 kW meanwhile the pumping power is improved 26.00 kW.When the buried depth of the DBHE is enhanced from 1600 to 2400 m,the average heat transfer capacity and the pumping power of the DBHE are increased by 113%and 50%respectively.When the outer pipe diameter of the DBHE is enhanced from 168 to 299 mm,the average heat transfer capacity of the DBHE is increased by 10%,however the pumping power is decreased by 27%.