地下群井改变径流条件下的三维实验模拟研究
|
摘要
为研究改变地下径流条件时对U型地埋管换热器周围温度场恢复的影响,对北京某区实验基地U型地埋管进行夏季换热实验。通过抽水实验改变地下径流条件,取得了地源热泵系统的运行参数以及周边温度场变化趋势,通过COMSOL软件模拟三维U型地埋管在多场耦合作用下的换热过程,改变径流条件得到了换热孔周围0.5 m、1 m地温场恢复曲线,得到U形管口出口温度等。地下水径流能引起地埋管周围温度场的变形,地埋管周围温度场的迁移变化方向同地下径流速度场方向一致。对比实验值得出:运行稳定后地埋管的出口温度模拟值与实际值工况接近,地埋管在10 m、120 m处的温度模拟值与实验值吻合好,地埋管深5 m、48 m、89 m处周围0.5 m、1m的温度恢复比原始地温高1℃左右,与实际监测结果相同,证明了数值模拟的正确性。在此基础上预测了加大径流条件下的地温场恢复情况,并分析了原因。此三维模型可研究不同土壤分层构造、地下水不同流速、人为改变地下流场条等复杂三维多场耦合问题,可初步预测实际工程中,换热群井运行过程中地下温度场的变化。为进一步研究土壤分层和地下水分层流动下,地埋管群井周围温度场变化奠定了基础。
In order to study the temperature field of U-vertical buried pipes with underground runoff variation,the experiment on U-vertical buried pipes was carried out during summer in Beijing. Through the experiment,the operating parameters of the ground source heat pump system were recorded. Moreover, the temperature field surround the U-vertical buried pipes was acquired. By simulating the multi-field coupled heat transfer process between the U-vertical buried pipes and the soil surrounded, the temperature recovery curve around the buried pipes would be varied from 0.5 m to 1.0 m when the underground runoff condition changes was obtained, so was the outlet temperature of the U-vertical buried pipes. The simulation results show that the groundwater flow can cause the temperature field distortion around the buried pipes. Besides, the migration direction of the temperature field and the underground runoff velocity are the same. Comparing with the experimental value, the simulation result of the outlet temperature of U-vertical buried pipes was approximately the same, especially the temperature in the depth of 10 m and 120 m. In the depth of 5 m, 48 m and 89 m, it was about 1℃ higher than the original ground temperature around the buried pipes within 0.5 m and 1 m. The simulation results were consistent with the experimental values, which confirmed the validity of the numerical simulation in this study. Base on the simulation,the recovery of the geothermal field when increasing the underground runoff was predicted and analyzed. Using the three-dimensional model established in this study, the complex three-dimensional multi-field coupled problems for different soil layers with different groundwater velocities can be studied. Besides, the variation of underground temperature can be preliminarily predicted in actual geothermal engineering practice, which provides technical basis for the further research of the temperature field around the buried pipelines considering the stratification of soil and groundwater.
In order to study the temperature field of U-vertical buried pipes with underground runoff variation,the experiment on U-vertical buried pipes was carried out during summer in Beijing. Through the experiment,the operating parameters of the ground source heat pump system were recorded. Moreover, the temperature field surround the U-vertical buried pipes was acquired. By simulating the multi-field coupled heat transfer process between the U-vertical buried pipes and the soil surrounded, the temperature recovery curve around the buried pipes would be varied from 0.5 m to 1.0 m when the underground runoff condition changes was obtained, so was the outlet temperature of the U-vertical buried pipes. The simulation results show that the groundwater flow can cause the temperature field distortion around the buried pipes. Besides, the migration direction of the temperature field and the underground runoff velocity are the same. Comparing with the experimental value, the simulation result of the outlet temperature of U-vertical buried pipes was approximately the same, especially the temperature in the depth of 10 m and 120 m. In the depth of 5 m, 48 m and 89 m, it was about 1℃ higher than the original ground temperature around the buried pipes within 0.5 m and 1 m. The simulation results were consistent with the experimental values, which confirmed the validity of the numerical simulation in this study. Base on the simulation,the recovery of the geothermal field when increasing the underground runoff was predicted and analyzed. Using the three-dimensional model established in this study, the complex three-dimensional multi-field coupled problems for different soil layers with different groundwater velocities can be studied. Besides, the variation of underground temperature can be preliminarily predicted in actual geothermal engineering practice, which provides technical basis for the further research of the temperature field around the buried pipelines considering the stratification of soil and groundwater.
引文
Bandos T V,Montero A,femandez E,et al,2009.Finite linesource model for borehole heat exchangers effect of vertical temperature variations[J].Geothermics,(38):263-270.
Chiasson A D,1992.Advances in Modeling of Ground-sources Heat Pump Systems[C].Windsor:Applied Science University of Windsor.
Ingetsoll L R,Zoeble 0 J,Ingersoll A C.1954.Heat condition with engineering,Geological and other application[M].New York:Wisconsin:176-184.
Schmidt T,Mangold D,Muller-Steinhagen H,1997.Central Solar Heating Plants with Seasonal Storage in Germany[J].Public Utilities Science&Technology,76(1):165-174.
Witte H J L,Gelder A J V,Serrao M,2002.Comparison of Design and Operation of a Commercial UK Ground Source Heat Pump Project[A].lst International Conference on Sustainable Energy Technologies[C].Porto,Portugal paper,1-6.
程金明,刘阳,2017.地下水流动对垂直埋管换热器土壤温度场分布的影响[J].太阳能学报,38(10):2798-2802.
范蕊,马最良,姚杨,等,2007.地下水流动对地下埋管换热器影响的实验研究[J].太阳能学报,28(8):874-880.
龙会,余跃进,封周权,2007.埋地换热器在渗流中的三维温度场模拟[J].太阳能学报,32(6):862-867.
杨卫波,施明恒,2006.基于垂直U型埋管换热器的圆柱源理论及其应用研究[J].制冷学报,27(5):51-57.
Chiasson A D,1992.Advances in Modeling of Ground-sources Heat Pump Systems[C].Windsor:Applied Science University of Windsor.
Ingetsoll L R,Zoeble 0 J,Ingersoll A C.1954.Heat condition with engineering,Geological and other application[M].New York:Wisconsin:176-184.
Schmidt T,Mangold D,Muller-Steinhagen H,1997.Central Solar Heating Plants with Seasonal Storage in Germany[J].Public Utilities Science&Technology,76(1):165-174.
Witte H J L,Gelder A J V,Serrao M,2002.Comparison of Design and Operation of a Commercial UK Ground Source Heat Pump Project[A].lst International Conference on Sustainable Energy Technologies[C].Porto,Portugal paper,1-6.
程金明,刘阳,2017.地下水流动对垂直埋管换热器土壤温度场分布的影响[J].太阳能学报,38(10):2798-2802.
范蕊,马最良,姚杨,等,2007.地下水流动对地下埋管换热器影响的实验研究[J].太阳能学报,28(8):874-880.
龙会,余跃进,封周权,2007.埋地换热器在渗流中的三维温度场模拟[J].太阳能学报,32(6):862-867.
杨卫波,施明恒,2006.基于垂直U型埋管换热器的圆柱源理论及其应用研究[J].制冷学报,27(5):51-57.