摘要
通过建立的垂直U形地埋管三维非稳态模型,在5种不同导热系数回填材料U形地埋管连续运行条件下,对U形管的水温进行了逐时监测。比较不同填料条件下钻孔的传热情况,分析了对支管间热短路的影响,结果表明,当填料的导热系数小于临界值时,提高导热系数有利于降低出水温度,取得较好的传热效果;当导热系数继续增加时,强化传热的能力逐渐降低。单纯提高填料的导热系数强化传热会带来热短路问题,填料的导热系数越大,热短路现象越明显,换热的不利影响也就越严重。建议应根据地质条件选择回填材料,使其导热系数略大于地下土壤的。采用支管间架设弹簧的措施有利于缓解地埋管道的热短路现象,因为弹簧可以防止随着时间的推移,支管间间隙变小。
In this study,A three-dimensional unsteady state model for vertical U-tube is developed and the water temperature of U-tube is monitored hourly through continuous operation of U-tube in conditions of 5 kinds of backfill thermal conductivity.Comparing the heat transfer in boreholes with different backfill and analyzing the influence of thermal short-circuit between branches,the results show that increasing the thermal conductivity of backfill material is beneficial to reduce the outlet water temperature and results in better heat transfer effect,and the capability of strengthening heat transfer decreases gradually if continuing to increase the thermal conductivity of backfill material beyond the critical valve;increasing the thermal conductivity of fillers purely for the enhancement of heat transfer will bring the thermal short-circuit problem;the greater the thermal conductivity is,the more obvious the thermal short-circuiting phenomenon and the more serious the adverse effects of heat exchange will be.It is suggested that the thermal conductivity of backfill material is slightly larger than that of ground soil,and should be chosen according to geological conditions.The measure of adopting springs is beneficial to reduce thermal short-circuiting phenomenon of buried pipes since springs prevent the gap from getting smaller as time goes on.
作者
廖露
LIAO Lu(Unit 68068 PLA,Wuwei 733000,China)
出处
《防护工程》
2018年第3期16-21,共6页
Protective Engineering
关键词
地埋管换热器
回填材料
导热系数
换热量
ground heat exchanger
backfill material
thermal conductivity
heat exchange capacity
