中深层套管式地埋管换热器换热性能模拟研究

建立套管式地埋管换热器数值模型,采用FLUENT对制热工况下套管式地埋管换热器的换热性能进行模拟,研究运停比、岩土热导率、地温梯度等因素对单位钻孔深度换热量的影响.岩土热导率为2.5 W/(m·K),地温梯度为0.03℃/m条件下:不同运停比的单位钻孔深度换热量均随时间推移而下降.相同供暖期,单位钻孔深度换热量由大到小...

Simulation Research on Heat Transfer Performance of Middle-deep Double-pipe Buried Pipe Heat Exchanger

A numerical model of the double-pipe buried pipe heat exchanger is established, and FLUENT is used to simulate the heat transfer performance of the double-pipe buried pipe heat exchanger under heating conditions. The influence of the operation/shutdown ratio, geotechnical thermal conductivity, geothermal gradient and other factors on the heat transfer per unit borehole depth is studied. When the geotechnical thermal conductivity is 2.5 W/(m·K),and the geothermal gradient is 0.03 ℃/m, the heat transfer per unit borehole depth of different operation/shutdown ratios decreases with the passage of time. In the same heating period, the order of operation/shutdown ratio corresponding to the heat transfer per unit borehole depth from large to small is 8∶16,12∶12,16∶8 and 24∶0. When the geothermal gradient is 0.03 ℃/m, and the operation/shutdown ratio is 24:0,The heat transfer per unit borehole depth of different rock and soil thermal conductivities decreases with the passage of time. In the same heating period, the heat transfer per unit borehole depth increases with the increase of geotechnical thermal conductivity. When the geotechnical thermal conductivity is 2.5 W/(m·K),and the operation/shutdown ratio is 24∶0,the heat transfer per unit borehole depth of different geothermal gradients decreases with the passage of time. In the same heating period, the heat transfer per unit borehole depth increases with the increase of geothermal gradient. The intermittent operation can achieve effective heat recovery of rock and soil and increase the heat transfer capacity of the buried pipe heat exchanger.