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对土壤源热泵系统在制冷季中垂直U型地埋管的传热性能进行数值模拟,揭示U型管入口水温、入口流速和回填材料导热系数对地埋管传热性能的影响规律.计算结果表明:在30~60°C的入口温度范围内,当雷诺数从3 000提高到11 000时,会使地埋管热流量增大10~23W,但会导致流体进出口温差降低0.2~1.34°C,在工程应用中流体进口流速要控制在一定范围内.水的入口温度和雷诺数分别为45°C和7 000时,回填材料导热系数从0.5 W/m·K增大至2.5 W/m·K,U型地埋管的热流量增大了将近2倍,也就是说在工程应用中,如果在回填土中掺混一定比例的保水材料将会增强埋管换热,并防止埋管长期运行时由于土壤本身保水性差使得土壤板结从而导致埋管失效.模拟结果与实验数据进行对比吻合较好.
The heat transfer performance of vertical ground U-type ground source heat pump system during the cooling season was numerically simulated to reveal the effect of U-shaped pipe inlet water temperature, inlet velocity and backfill thermal conductivity on the heat transfer performance of buried pipe. The results show that when the Reynolds number is increased from 3000 to 11000 within the inlet temperature range of 30-60 ° C, the heat flux of the buried pipe will increase by 10 ~ 23W, but the temperature difference between the inlet and outlet of the fluid will decrease by 0.2-1.34 ° C, the fluid inlet flow rate should be controlled within a certain range in engineering applications.When the inlet temperature and Reynolds number of water are 45 ° C and 7 000, respectively, the thermal conductivity of backfill increases from 0.5 W / m · K to 2.5 W / m · K, U-type buried pipe heat flux increased nearly 2 times, which means that in engineering applications, if the backfill in a certain proportion of water-retaining material will enhance the heat transfer and prevent Under the long-term operation of buried pipe, soil subsidence resulted in failure of pipe due to the poor water holding capacity of soil itself.The simulation results are in good agreement with the experimental data.