相变回填材料配比对地埋管换热器蓄能传热特性影响研究

Effect of the Mixture Ratio of the Phase Change Backfilled Material on the Energy Storage and Heat Transfer Characteristics of Ground Heat Exchanger

在所搭建的相变蓄能型地埋管换热器的数值模型和仿真模型实验台的基础上,考虑扬州地区地下土壤温度条件与相变材料经济性,夏季工况选用混合酸,冬季工况选用油酸。这两种相变材料分别以2∶8、4∶6、6∶4和8∶2的配比作为回填材料共同回填至钻孔内时,对比探究了相变回填材料配比在夏季和冬季工况下一天内运行10h以及夜间停机恢复14h对地埋管换热器蓄能传热特性影响。研究结果表明:混合酸和油酸两种相变材料的物性参数不同,当两者共同回填至钻孔内时,回填材料的综合热物性会发生变化;随着当季起作用的相变回填材料配比含量的增加,能够显著提升钻孔换热量,提升蓄热能力,缓解钻孔外土壤温度的冷热堆积问题,减小热影响范围;选择适合实际工程的配比需要参考实际建筑冷热负荷进行计算。

Based on the numerical model and simulation model test bench of the ground heat exchanger with phase change backfilled material built in this paper,considering the underground soil temperature conditions and economics of phase change materials in Yangzhou area,the mixed acids are used in summer conditions,the oleic acid is used in winter conditions.These two phase change materials were compared and explored in summer and winter conditions for 10 hours of operation and 14 hours of recovery after shutdown.The ratios of 2∶8,4∶6,6∶4,and 8∶2 were used as backfilled materials into the borehole to study the effect on the energy storage and heat transfer characteristics of the ground heat exchanger.The research results show that the physical properties of two phase change materials of mixed acid and oleic acid are different,when these two are backfilled into the borehole,the comprehensive thermophysical properties of the backfilled material will change.Increasing the content of the material ratio can significantly increase the heat exchange capacity of the borehole,increase the heat storage capacity,alleviate the cold and hot accumulation of the soil temperature outside the borehole,and reduce the thermal impact.Choosing a suitable ratio for the actual project requires reference to the actual building cooling and heating loads.