热源井填砾抽灌同井流/热贯通及温度锋面运移数值模拟  

Numerical simulation on flow/thermal transfixion and temperature front migration of thermal well of pumping & recharging well filled with gravel

作　　者：宋伟 刘远周 郑湍峰 刘晓秀 Song Wei;Liu Yuanzhou;Zheng Tuanfeng;Liu Xiaoxiu(School of Civil Engineering, North China University of Technology, Beijing 100144, China)

机构地区：[1]北方工业大学土木工程学院,北京100144

出　　处：《农业工程学报》2018年第24期210-216,共7页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金资助项目(41602278);中国博士后科学基金资助项目(2016M601129);供热供燃气通风及空调工程北京市重点实验室研究基金资助课题(NR2016K03);北方工业大学青年拔尖人才培育计划资助项目(XN018032);北方工业大学青年毓杰人才计划资助项目(18XN154-006)

摘　　要：针对填砾抽灌同井流贯通、热贯通及温度锋面运移研究的不足,该文在已验证的数值模型中建立监测点、线、面和体对以上问题进行量化分析,并将热源井回水经过回填砾石直接流入抽水管的流量占总回水流量的百分比定义为流贯通强度。研究结果表明,填砾抽灌同井回水进入含水层后的流速可以用某一方向的分速度代替;该模型中的流贯通强度为1.2%,热贯通发生与完全形成的时间分别为模型运行2.5和12 min,抽水温度变化较剧烈的时刻与热贯通形成发展的时刻基本一致。在地下水渗流速度大于1×10^(-3)m/s的区域,速度锋面运移较温度锋面运移快;反之,温度锋面运移快于速度锋面运移。通过对填砾抽灌同井流贯通、热贯通及温度锋面运移的量化分析,为进一步探索填砾抽灌同井最优运行策略和更高换热效率提供了理论基础。The system of pumping & recharging well filled with gravel (PRWFG) is a specific type of the single thermal well used as ground heat exchanger. The heat efficiency of PRWFG is higher than that of the standing column well (SCW) or the traditional pumping & recharging well (PRW). The inlet water of the PRWFG converges and seeps toward the thermal well both horizontally and longitudinally as combined impacts of the positive recharging pressure, the negative pumping pressure and the gravity. During the procedure of seepage, the heat transfers between the inlet water and the water/solids in the aquifer via conduction, convection and thermal dispersion. The amount of heat transferred directly affects the efficiency and the capacity of the thermal well. Due to the low velocity of underground water, heat conduction occurs between the fluid and the solids, as well as between the solids. The heat transfer coefficient is relatively stable if there are certain hydrogeological conditions. Heat convection and thermal dispersion occur in the pores among the solids and the heat transfer coefficients depend on the flow rate of groundwater. A small amount of inlet water enters the outlet water pipe after heat exchanged with the gravel zone and the wall of the thermal well. Considering the facts that normally the porosity of the gravel zone is larger than that of the aquifer, the pressure difference between inlet and outlet water pipes is high and the distance between them is short, flow transfixion is more commonly happened in the thermal well than in the aquifer. Flow transfixion is a process that the inlet water in the thermal well enters the outlet water pipe through the gravel zone and the zone near the wellbore. The flow transfixion leads to a thermal transfixion by mixing water at different temperatures and mixed flow moves to the outlet water pipe. The formation of flow/thermal transfixion reduces the heat transfer efficiency and load-carrying capacity of thermal well. Currently, the bleeding strategy is usually used for de

关 键 词：井 温度 速度 填砾抽灌同井 流贯通强度 热贯通 温度锋面 数值模拟 

分 类 号：TK529[动力工程及工程热物理—热能工程]