日光温室地中热水管加温对土壤温度的影响

Soil Temperature in Solar Greenhouse with Buried Hot Water Pipes

为了明确日光温室地中埋热水管对土壤加温效果的影响,利用Ansys有限元分析方法,对日光温室内地埋热水管在不同进回水平均温度(30,40,50℃)、水流速度(0.05,0.10,0.25,0.50m·s-1)、管道埋深(30,40,50,80cm)、埋管间距(20,40,50,60,80,100cm)和管道直径(25,32,40,50,63mm)下的土壤温度分布进行研究。结果表明:水温对地表温度影响显著,管道内水流速≥0.10m·s-1时地表温度变化不大,在长期平稳条件下,埋管深度、管径对地表温度影响不大,而管间距对土壤温度分布影响显著。选择适宜条件:进回水温度40℃,水流流速0.10m·s-1,管道埋深40cm,管间距20cm,管径25mm进行试验,与相应条件下的模拟结果对比,实测值与模拟值相关程度较高,可为地埋管道加温方式的布设和运行提供理论参考。

The aim of this study was to analyze the influence of hot-water pipe buried on soil temperature in the solar greenhouse, with Finite element analysis method-ANS^S. The distribution of soil temperature parameters were discovered. These parameters included the supply and return water temperature in buried pipe at 30, 40 or 50℃, and water velocity at 0.05, 0.10, 0.25 or 0.50 m·s^-1, and pipeline depth at 30, 40, 50 or 80cm, and pipe spacing at 20, 40, 50, 60, 80 or 100cm, and pipe diameter at 25, 32, 40, 50 or 63ram. The results showed that the supply and return water temperature in buried pipe had affected significantly. Pipe water flow rate affected greatly on surface soil temperature. When pipe water flow rate was greater than 0.10 m·s^-1, in the long-term stable conditions, buried depth and pipe diameter had little effect on the surface soil temperature, while the tube spacing had a significant effect. Optimization design thermal parameters： supply and returned water temperature in buried pipe is 40~C, flow velocity is 0.10m·s^-1, pipeline depth 40cm, tube spacing 20cm, diameter is 25mm. Experiments under the above conditions got highly correlationship of the measured and simulated values. The simulation results provide a theoretical basis for optimization design and operation buried hot water pipes system in the solar greenhouse.