关中地区U型地热井水平井段高效换热规律数值模拟

Numerical simulation of high efficiency heat transfer rule in horizontal section of U-shaped geothermal well in Guanzhong area

为研究U型地热井水平井段在采暖期间换热能力随注水流量的变化规律,并在非采暖期间不同流速且地层恢复至初始温度的前提下确定最优流速及最大取热量,以西安市深度为2050 m的垂直埋深U型地热井水平井段取暖系统为研究对象,利用ANSYS FLUENT软件进行数值计算。根据恒定入口水温和流速的现场实际情况,建立了数值模拟的物理模型和数学模型,设置合理的边界条件,得到了U型地热井水平井段换热能力随流速的变化规律。研究表明在同一采暖期间,注水流量越大,出口水温越低,取热量越大。在流速为0.3 m/s即流量为33.85 t/h时地层在非取暖期间可以恢复至初始温度且水平井段最大取热量为1.81×1013 J.

The purpose of this paper is to study the change rule of the heat transfer capacity of horizontal well section of u-shaped geothermal well with water injection flow during heating period and determine the optimal flow rate and maximum heat withdrawal under the premise of different flow rates during non-heating period and the formation recovery to the initial temperature.The u-shaped geothermal well heating system with a vertical buried depth of 2050 m in Xi’an was taken as the research object,and the software ANSYS FLUENT was used for numerical calculation.According to the actual situation of constant inlet water temperature and flow velocity,the physical and mathematical models of numerical simulation were established,and reasonable boundary conditions were set up.The results show that during the same heating period,the greater the water injection flow is,the lower the outlet water temperature is,and the greater the heat extraction is.When the flow rate is 0.3 m/s,that is,the flow rate is 33.85 t/h,the formation can recover to the initial temperature during the non-heating period,and the maximum heat recovery of the horizontal well section is 1.81×1013 J.