回填空气间隙对地埋管岩土温度恢复性能的影响

Influence of Backfill Air Gap on Soil Temperature Recovery in Ground-coupled Heat Pumps

地埋管地源热泵系统在换热孔回填过程中,由于施工不当易产生空气间隙。通过建立岩土耦合单U三维传热模型,按照实际工程中可能出现的3种不同空气层情况进行了计算分析,把不同空气层情况对传热造成显著影响的因素"地温恢复性能"作为研究对象,并根据理论计算结果与实际工程的运行数据进行了地埋管进、出水温度的对比验证。结果表明,在岩土温度恢复期内,空气间隙的存在提高了所在区域以内岩土的平均过余温度,降低了地埋管的换热性能。

Air gap may easily emerge in the progress of backfill in ground heat exchange due to field operation problems.The single U-tube three-dimensional numerical heat transfer model is set up and there are 3 kinds of backfill air gap assumptions for computational analysis,which are the most common situations in practical projects.Different air gap situations will have considerable effects on soil heat transfer,especially the factor of soil temperature recovery performance,which is investigated in this research,and there is practical project operating data for the comparison confirmation with the theoretical calculation results in inlet and outlet water temperatures.It can be concluded that the backfill air gap will increase the soil average excess temperature in the period of recovery inside the place where the air gap is,and degrade the heat transfer performance of the ground heat exchange.