回填空气间隙对地埋管岩土温度恢复性能影响.docVIP

回填空气间隙对地埋管岩土温度恢复性能影响摘 要：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。 关键词：土壤源热泵；空气间隙；温度恢复；岩土平均过余温度 中图分类号：TU831 文献标志码：A 文章编号：1674-4764（2012）04-0142-07 Influence of Backfill Air Gap on Soil Temperature Recovery in Ground-coupled Heat Pumps WANG Yong, JIN Yitao （Key Laboratory of the Three Gorges Reservoir Regions Eco-Environment, Ministry of Education, Chongqing University, 400045, P. R. China） Abstract: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. Key words:ground-coupled heat pumps; air gap; temperature recovery; soil average excess temperature  地源热泵是随全球能源环境问题的可持续发展而兴起的一种节能环保的地热利用技术［1］。在地源热泵工程中，地埋换热器周围岩土温度的恢复一直是研究、设计人员非常关心的问题，相关学者对此进行了大量的研究［2］。刘俊等［3］提出地温的恢复特性主要取决于岩土热物性、管群布置、系统启停比、冷热负荷强度和冷热负荷不平衡率等因素。Shang等［4］研究了间歇运行情况下，影响地温恢复的因素：岩土及回填材料的热物性、多孔性对岩土温度的恢复有较大影响，当多孔性指数下降时，岩土温度恢复所需的时间减少。赵利君等［5］通过对间歇运行岩土温度在不同深度及半径下的恢复率的研究，发现由于岩土对传热的衰减作用，离孔壁距离越远，温度受到间歇运行工况的影响就越小；岩土恢复能力随着运行周期的增加而不断降低。高源等［6］的实验结果表明，同一埋管深度处，机组的运行时间越长，岩土短期内可恢复的可用稳定温度越高，且需要的稳定恢复时间也越长。陈颖