Abstract:

Ground thermal properties is an important design parameter of ground-coupled heat pump system (GCHPs), and it can be decided based on the data from in-situ thermal response test (TRT). Considering that constant heat input can seldom be ensured in TRT, this paper presents a novel method for determining parameters of rock-soil thermal properties by using simulated annealing algorithm (SAA). In the method, Green function used in cylinder source model (CSM) of borehole heat exchanger (BHE) accelerates calculation of inlet/outlet water temperatures based on the TRT system model, and RMSE distribution overcomes the ill-posed problem of parameter identification in inverse heat transfer analysis, which puts into effect of SAA. In a calculation sample based on TRT of variable heat input, annealing temperature decreases with identified parameters reaching agreement with true value individually, and the relative errors of ground thermal conductivity and volumetric heat capacity are respectively 4.1% and 1.3% by comparing with the value calculated based on national regulations on the same in-situ measuring location. At the same time, the effective heat resistance of BHE can be obtained in the process of ASS. In general, ASS used in the variable heat power TRT is proved to be successful, and the study is helpful for the design of BHE in GCHPs.

Key words: GCHPs, optimization, cylinder source, model, rock-soil thermal response test, simulated annealing algorithm, numerical simulation

摘要：

岩土的热物性是土壤源热泵系统设计的重要参数,需要在工程地点实施热响应试验才能确定。针对现场热响应试验中恒加热功率难以保证的实际情况提出了利用模拟退火算法确定变热流状况下热物性参数的新方法。该方法以竖直U形地埋管换热器的柱热源(CSM)模型为基础,引入格林函数加快了热响应试验系统模型确定换热器进出水温度的计算速度,利用RMSE分布图解决了传热反分析中参数识别的非适定问题,保障了模拟退火算法的有效实施。在结合具体算例实施热物性参数识别的过程中,变热流情况下模拟退火算法对应的退火温度降温速度快,确定的岩土热导率和容积比热容的相对误差分别为4.1%和1.3%,而且计算了地埋管换热器的有效热阻。研究结果可为确定岩土热物性参数和指导地埋管换热器系统设计提供参考。

关键词: 土壤源热泵系统, 优化, 柱热源, 模型, 岩土热物性试验, 模拟退火算法, 数值模拟