School of Civil Engineering,North China Institute of Science and Technology
Department of Mechanical Engineering,University of Malaya
Faculty of Urban Construction,Beijing University of Technology
Beijing Key Laboratory of Green Building Environment and Energy Efficient Technology,Beijing University of Technology

为了研究黄土高原地区土壤分层与未分层地埋管埋深的最优值。本文使用Fluent仿真软件建立单U型地埋管三维模型,分析土壤分层与未分层两种情况下,埋深分别为60m、70m、80m、90m、100m地埋管出口温度和换热量的变化规律,从而确定地埋管的最优埋深。结果表明:地埋管的埋深对于整个系统的出口温度和换热量影响显著,埋深越深地埋管的换热性能越好,但随着地埋管埋深的增加,两者增长幅度逐渐降低;土壤分层情况下的地埋管进出口温差和单位井深换热量大于土壤未分层情况下的进出口温差和单位井深换热量,且差距明显;在土壤分层情况下,埋深从60m到70m时,进出口温差最大为0.17℃,换热量变化率为0.12;在土壤未分层情况下,埋深从70m增加到80m时,进出口温差最大为0.15℃,换热量变化率为0.13。综合考虑地埋管的出口温差和总热量变化率,单U26管,土壤分层地埋管最优埋深为60~70m,土壤未分层地埋管最优埋深为70~80m。该研究结论可为黄土高原地区或同类地貌下地源热泵单U形地埋管埋深提供数据支撑和理论参考。

In order to study the optimal buried depth of layered and non-layered soil ground heat exchanger inthe Loess Plateau.In this paper,a three-dimensional model of a single U-shaped gronnd heat exchanger is established by Fluent simulation software,and the variation laws of outlet temperature and heat exchange of theburied pipe with depth of 60m,70m,80m,90m and 100m are analyzed under the conditions of layered soil and non-layered soil,respectively,so as to determine the optimal buried depth of the ground heat exchanger.Theresults show that the buried depth of the ground heat exchanger has a significant influence on the outlet temperature and heat exchange capacity of the whole system.The deeper the buried pipe is,the better the heat exchange performance is,but with the increase of the buried depth of the ground heat exchanger,the growth rateof the two gradually decreases.The temperature difference between the inlet and outlet of the ground heat exchanger and the heat exchange capacity per well depth in the case of layered soil are larger than those in thecase of non-layered soil,and the difference is obvious.In the case of soil stratification,when the burial depthranges from 60 m to 70 m,the maxium temperature difference between the inlet and outlet is 0.17℃ and heattransfer rate is 0.12,respectively;When the burial depth increases from 70m to 80m without soil stratification,the maximum temperature difference between the inlet and outlet is 0.15℃,and the heat transfer rate is 0.13.Taking into account the outlet temperature difference and total heat change rate of the buried pipe,the optimalburial depth for a single U26 pipe and a soil layered buried pipe is 60 ~70 m,while the optimal burial depthfor an ungraded soil buried pipe is 70~80 m.The research conclusion can provide data support and theoreticalreference for the burial depth of single U-shaped buried pipes in ground source heat pumps in the Loess Plateau region or similar landforms.