文献类型：期刊文献

英文题名：Short-time performance of composite-medium line-source model for predicting responses of ground heat exchangers with single U-shaped tube

作者：Yang, Yi[1];Li, Min[2]

机构：[1]Guangdong Ocean Univ, Engn Coll, Zhanjiang 524088, Peoples R China;[2]Cent South Univ, Sch Energy Sci & Engn, Changsha 410083, Hunan, Peoples R China

年份：2014

卷号：82

期号：1

起止页码：130

外文期刊名：INTERNATIONAL JOURNAL OF THERMAL SCIENCES

收录：SCI-EXPANDED(收录号：WOS:000337653800012)、、EI(收录号：20142017714194)、Scopus(收录号：2-s2.0-84899861174)、WOS

语种：英文

外文关键词：Composite-medium line-source model; Borehole ground heat exchanger; Ground-coupled heat pump; Finite volume model; Short-time response

外文摘要：A composite-medium line-source model has been recently developed for modeling short-time thermal processes of borehole ground heat exchangers. The composite-medium line-source model is attractive for applications where the short-term or high-frequency responses of borehole ground heat exchangers are important. In this paper, the short-time performance of this analytical model is examined in depth by comparing it with a two-dimensional finite volume model. The numerical model can address the heat capacity of circulating water by using a novel time-varying boundary condition on the inner walls of the U-shaped tube, in addition to the heat capacities of U-shaped tube and grouting material. Both the numerical and the analytical composite-medium models are validated using an independent sandbox experiment. Comparisons between the two models are also made for different parameters, including heating rate, the spacing of the U-tube legs, thermal properties, and borehole radius. Overall, the composite-medium line-source model gives the virtually same results as the numerical model except for the first several minutes: the analytical solution overestimates temperature responses during the first 3 min, which is caused by the line-source assumption ignoring the heat capacities of the fluid and the U-shaped pipe. (C) 2014 Elsevier Masson SAS. All rights reserved.