Development of chiller-attached apparatus for accurate initial ground temperature measurement: Insights from global sensitivity analysis of thermal response tests
Development of chiller-attached apparatus for accurate initial ground temperature measurement: Insights from global sensitivity analysis of thermal response tests
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DOI：
10.1016/j.enbuild.2021.110841
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发表时间：
2021-02
影响因子：
6.7
通讯作者：
W. Choi;R. Choudhary;R. Ooka
中科院分区：
文献类型：
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作者：
W. Choi;R. Choudhary;R. Ooka
局部灵敏度分析（LSA）被广泛用于评估模型输出或估计参数的不确定性。然而，它没有考虑改变参数空间中的参数值和参数集的同时改变的影响。全局敏感性分析（GSA）通过充分表示模型使用或参数估计中传播的不确定性来克服LSA的这些限制。在这项研究中，通过使用Sobol的方法，GSA进行分析的时间不确定性转换的模型输入所需的热性能估计通过地面热响应测试（TRT）。所获得的结果提供了重要的见解，具体而言，在各种输入参数中，初始地温和地下体积热容分别占井阻力估计的总不确定性的~27%和~20%以上。此外，由于钻孔直径的不确定性，估计的钻孔热阻大于预期热阻，这在施工过程中可能会增加。因此，通过固定钻孔直径的确定性估计导致比实际电阻更低的估计。然后，所获得的见解被用来开发一个冷却器连接TRT设备，以克服传统的设备，不能准确地测量初始地面温度的限制。通过使用所开发的能够精确控制流体温度的装置，可以在0.1 °C的不确定度范围内渐近地找到循环流体和周围土壤处于热平衡时的温度。与传统做法相比，这种初始地温精度的提高导致钻孔热阻的估计不确定性降低了24%。
Local sensitivity analysis (LSA) is widely used for evaluating the uncertainty in a model output or estimated parameters. However, it does not consider the effect of changing parameter values in the parameter space and the simultaneous change of the parameter set. Global sensitivity analysis (GSA) overcomes these limitations of LSA by adequately representing the propagated uncertainty in model usage or parameter estimation. In this study, by using Sobol’s method, GSA was conducted to analyze the temporal uncertainty transition of model inputs required in the thermal property estimation via a ground thermal response test (TRT). The obtained results provide important insights; specifically, among the various input parameters, the initial ground temperature and ground volumetric heat capacity account for more than ~27% and ~20% of the total uncertainty in borehole resistance estimation, respectively. Further, the estimated borehole thermal resistance is larger than intended owing to the uncertainty in the borehole diameter, which is likely to increase during the construction process. Thus, a deterministic estimation by fixing the borehole diameter leads to a lower estimate than the actual resistance. Then, the insights obtained are used to develop a chiller-attached TRT apparatus to overcome the limitations of conventional apparatuses that cannot measure the initial ground temperature accurately. By using the developed apparatus that can accurately control the fluid temperature, the temperature at which the circulating fluid and surrounding soil are in thermal equilibrium can be asymptotically found with an uncertainty range of 0.1 °C. This improvement in the initial ground temperature accuracy results in a 24% reduction in the estimation uncertainty of the borehole thermal resistance compared to conventional practice.