Applied Thermal Engineering ( IF 6.4 ) Pub Date : 2020-11-25 , DOI: 10.1016/j.applthermaleng.2020.116370 Antonio Cazorla-Marín , Carla Montagud-Montalvá , José Miguel Corberán , Álvaro Montero , Teresa Magraner
The determination of ground thermal properties is essential to design competitive commercial ground source heat pump systems. A thermal response test (TRT) carried out on site allows the determination of both the conductivity of the ground and the borehole thermal resistance by means of analytical approaches, which require several simplifying assumptions as well as TRT durations of at least fifty hours and constant heat injection. In this context, a detailed dynamic numerical model of the borehole can help reducing both the uncertainties, associated with these simplifying assumptions, and the required test duration. This paper presents a TRNSYS tool to obtain the grout and ground thermal properties by means of a parameter estimation technique in conjunction with a two-dimensional dynamic numerical model, the B2G model, which is able to provide accurate results with a much shorter testing time and without the necessity of a constant heat injection.
The methodology to estimate the borehole and ground characteristics has been validated thanks to the analysis of a set of experimental TRTs for U-pipe vertical boreholes carried out in different type of soils and borehole geometries. Results show that, for the analysed tests, it is possible to obtain an accurate and fast estimation of the ground thermal conductivity with reductions of the necessary TRT duration of up to a 70%, with a total uncertainty between ±10% and ±18%, considering not only the uncertainty introduced by the reduction of the test duration, but also the main sources of uncertainty.
中文翻译:
TRNSYS辅助工具,用于估算应用于TRT(热响应测试)数据的地热特性:B2G模型
地热性能的确定对于设计具有竞争力的商业地源热泵系统至关重要。现场进行的热响应测试(TRT)可以通过分析方法来确定地面的电导率和井眼的热阻,这需要一些简化的假设以及至少50小时的TRT持续时间和恒定热量注射。在这种情况下,详细的钻孔动态数值模型可以帮助减少与这些简化假设相关的不确定性以及所需的测试持续时间。本文介绍了一种TRNSYS工具,该工具可通过参数估算技术结合二维动态数值模型B2G模型来获得水泥浆和地面的热特性,
得益于对在不同类型的土壤和几何结构中进行的U形垂直井孔实验TRT的分析,验证了估算井孔和地面特征的方法已得到验证。结果表明,对于所分析的测试,可以通过将所需的TRT持续时间减少多达70%来获得准确而快速的地面导热系数估算,总不确定度在±10%到±18%之间,不仅要考虑减少测试时间所带来的不确定性,还要考虑不确定性的主要来源。