Estimation of thermal properties of soil and backfilling material from thermal response tests (TRTs) for exploiting shallow geothermal energy: Sensitivity, identifiability, and uncertainty
Estimation of thermal properties of soil and backfilling material from thermal response tests (TRTs) for exploiting shallow geothermal energy: Sensitivity, identifiability, and uncertainty
复制标题
通过热响应测试 (TRT) 估算土壤和回填材料的热特性，以开发浅层地热能：敏感性、可识别性和不确定性
DOI：
10.1016/j.renene.2018.09.022
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发表时间：
2019-03-01
期刊：
影响因子：
8.7
通讯作者：
Liu, Gang
中科院分区：
文献类型：
--
作者：
Li, Min;Zhang, Liwen;Liu, Gang
准确地估算土壤和地下介质的热物性是浅层地热系统设计的关键。本文提出了一种同时估算土壤和土壤材料导热系数和扩散系数的新算法。该算法采用二维复合介质线源求解埋管换热器，使得早期（< 10 h）的热响应试验数据可用于参数估计。最后通过一个参考沙箱实验数据对新算法进行了验证。探讨了参数估计的几个理论问题，包括灵敏度、可辨识性和不确定性。本研究的主要发现是：（1）TRT的早期数据可以大大降低估计参数的线性相关性，从而提高参数估计的可辨识性。(2)按降序排列的估计准确度如下：土壤热导率k（s）（+/- 2%）、水泥浆热扩散率a（B）和电导率k（B）（+/- 15%）、土壤热扩散率a（s）（+/- 60%）。(3)井眼半径、加热速率和U形管腿的半间距的+/- 10%的不确定性导致ks、a（s）、k（B）或a（B）的原始估计值的总偏差分别等于8.4%、87.5%、12.8%和15.5%。(C)2018爱思唯尔有限公司版权所有
It is critical for designing shallow geothermal systems to accurately estimate thermal properties of soil and backfilling material. This paper reports on a new algorithm for simultaneously estimating thermal conductivities and diffusivities of soil and backfilling material. The algorithm uses a 2D composite medium line-source solution for borehole ground heat exchangers, enabling early-time (< 10 hr) data of thermal response tests (TRTs) to be used in the parameter estimation. The new algorithm is validated by a reference sandbox experimental data. Several theoretical issues of parameter estimation were explored, including sensitivity, identifiability, and uncertainty. The key findings of this study are: (1) the early-time data of TRTs can greatly reduce the linear dependence of the estimated parameters and thus improve the identifiability of the parameter estimation. (2) The accuracy of the estimates, ranked in descending order are as follows: soil thermal conductivity k(s) (+/- 2%), grout thermal diffusivity a(b) and conductivity k(b) (+/- 15%), soil thermal diffusivity a(s) (+/- 60%). (3) +/- 10% uncertainties in borehole radius, heating rate, and half-spacing of U-tube legs lead to the total deviations from the original estimates of ks, a(s), k(b), or a(b) equal to 8.4%, 87.5%, 12.8%, and 15.5%, respectively. (C) 2018 Elsevier Ltd. All rights reserved.