寒冷地区埋管式地源热泵系统热平衡分析

Analysis of soil heat balance of ground source heat pump system in cold region of China

以黄土高原寒冷地区埋管式地源热泵系统工程为平台，进行了为期两年的供热、恢复、供冷长期试验。在间歇制冷工况下，对换热井内岩土体的温度响应进行了研究。研究结果显示，开机30h后，岩土体温度趋于稳定，温度波动幅度为0．18-0．38℃；停机82h后，岩土体温度基本恢复稳定，温度下降范围仅为O．06～0．19℃。通过对工程岩土体热平衡分析发现，单纯地以全年累计冷热负荷的差异来判断岩土体的热平衡是值得商榷的。建议从全年累计冷热负荷平衡和岩土体的温度响应特性两个角度进行综合分析，进而确定埋管式地源热泵的适用性，以保证埋管式地源热泵系统长期稳定可靠地运行。试验结果可为黄土高原寒冷地区埋管式地源热泵系统的推广应用提供参考。

Relying on a demonstration project of vertical U-tube heat exchanger ground source heat pump in cold region of Loess Plateau,a long-term experiment in heating, recovering, and cooling of 2 years is carried out. A study on soil temperature response in intermittent cooling operation shows that the soil temperature increases a little after the unit runs for 30 hours and the fluctuation range of soil temperature is 0.18-0.38 ℃; the soil temperature drops close to its original temperature after the unit stops for 82 hours and the falling range of soil temperature is 0.06-0.19℃ . Analyses of the project ground heat balance show that it is worth discussing to judge soil heat balance by the difference of annual accumulative cold and heat load. The system analysis should therefore be implemented from the viewpoint of both annual accumulative energy equilibrium and soil temperature response in order to determine the suitability of ground source heat pump and ensure the whole stability and reliability for long-term operation. Moreover, it provides a reference to popularization and application of ground source heat pump in cold region of Loess Plateau.