渗流条件下地埋管换热器热短路现象的数值研究

Numerical Study on the Thermal Short Circuit Phenomenon of Buried Pipe Heat Exchanger under Seepage Condition

针对渗流条件下地埋管换热器受到热短路影响,导致夏季埋管出口水温上升以及换热量减少的现象,采取在进出水支管间加装隔热板的措施进行优化。通过对单U型地埋管换热性能的数值模拟,对比分析了加装隔热板前后的传热过程,并深入研究了隔热板的几何尺寸和安装位置对换热量的影响。结果表明:加装隔热板可有效抑制地埋管换热器的热短路现象,提高换热能力;隔热板宽度为120 mm时,U型地埋管换热器换热性能最优;隔热板高度取50 m时,换热器单位井深换热量最大,达到44.703 W/m;将隔热板安装在两支管中心向出水管侧偏移2 mm处,换热效果最佳。

In view of the phenomenon that the heat exchanger of the buried pipeis affected by thermal short circuit under the seepage condition,which leads to the rise of water temperature at the outlet of the buried pipe and the decrease of heat flux in summer,the heat insulation board is installed between the branch pipes of the inlet and outlet water for optimization.By the numerical simulation of the heat transfer performance of single U-shaped buried pipe,the heat transfer characteristics with or without heat shield is compared and analyzed,and the influence of the geometric size and installation position of heat insulation board on the heat flux is studied in depth.The results show that the installation of heat shields effectively suppresses the thermal short-circuit of the buried pipe heat exchanger and improves the heat exchange capacity.When the width of the heat insulation board is 120 mm,the U-shaped buried pipe heat exchanger has the best heat exchange performance.When the height of the heat insulation board is 50 m,the heat transfer per unit well depth of the heat flux is the largest and can reach 44.703 W/m.The heat transfer effect is the best if the heat insulation board is installed at a position that moves 2 mm to the side of the outlet pipe relative to the center of the two branchpipes.