Heat transfer analysis of boreholes in vertical ground heat exchangers
Heat transfer analysis of boreholes in vertical ground heat exchangers
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DOI：
10.1016/s0017-9310(03)00270-9
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发表时间：
2003-11
影响因子：
5.2
通讯作者：
H. Zeng;N. Diao;Z. Fang
中科院分区：
文献类型：
--
作者：
H. Zeng;N. Diao;Z. Fang
设计了一种地下热交换器，用于从地下提取热能或将热能注入地下。井筒热阻对GHEs性能有很大影响，井筒热阻由建筑材料的热物性和GHEs的流道布置决定。本文考虑了U型管柱间的流体轴向对流换热和热“短路”现象，建立了一种新的竖直埋管换热器的准三维模型，为更好地了解埋管换热器内的换热过程提供了理论依据。得到了沿井深方向流体温度分布的解析解。在此基础上，推导出了单U型和双U型两种不同井型的井筒阻力解析表达式。然后，对不同的井眼结构和流路布置的井筒阻力进行了评估。计算表明，双U型管的井眼阻力比单U型管的好，井筒阻力降低30~90%。双U形管并联比串联具有更好的性能。
A ground heat exchanger (GHE) is devised for extraction or injection of thermal energy from/into the ground. Bearing strong impact on GHE performance, the borehole thermal resistance is defined by the thermal properties of the construction materials and the arrangement of flow channels of the GHEs. Taking the fluid axial convective heat transfer and thermal “short-circuiting” among U-tube legs into account, a new quasi-three-dimensional model for vertical GHEs is established in this paper, which provides a better understanding of the heat transfer processes in the GHEs. Analytical solutions of the fluid temperature profiles along the borehole depth have been obtained. On this basis analytical expressions of the borehole resistance have been derived for different configurations of single and double U-tube boreholes. Then, different borehole configurations and flow circuit arrangements are assessed in regard to their borehole resistance. Calculations show that the double U-tubes boreholes are superior to those of the single U-tube with reduction in borehole resistance of 30–90%. And double U-tubes in parallel demonstrate better performance than those in series.