U型垂直埋管非稳态换热的数值模拟与研究

Numerical simulation of unsteady heat transfer of U-tube ground heat exchanger

采用有限容积法,使用计算流体力学软件对有效换热长度为120m的单U型地埋管进行三维建模和非稳态数值模拟。在考虑U型地埋管管壁热阻的情况下,分析了单U型地埋管不同土壤初始温度及不同进口流速对地埋管持续运行及间歇运行三个月的换热性能和热响应的影响。模拟分析结果表明:相同的土壤初始温度下,随着流速增大单位井深换热量和出口温度均增大;流速对出口温度的影响比土壤初始温度对出口温度的影响大;间歇运行期间平均单位井深换热量比连续运行大0.7W/m。

Based on finite volume method,computational fluid dynamics software is used to simulate the single U-tube ground heat exchanger with effective heat exchange length of 120m,and three dimensional numerical model of coupled heat transfer between U-tube ground heat exchangers and soil is established.Considering U-tube wall thermal insulation,the thermal response and heat exchanger property is analyzed,based on different soil initial temperature,inlet water velocity and continuous operation or intermittent operation of running three months.The simulation results show： at the same soil temperature,with the increase of initial velocity,the unit heat transfer capacity and outlet water temperature increase;the velocity has more influence on outlet water temperature than the soil initial temperature;the average specific heat transfer capacity during intermittent operation is 0.7W/m larger than that during continuous operation.