Soil thermal properties are important parameters to design the coaxial ground heat exchanger (GHE). This paper adopts an accurate semi-analytical model to analyse the sensitivities of soil thermal properties on the performance and parameter estimation of coaxial GHE, and then proposes a two-step parameter estimation method by using early-time thermal response test (TRT) data to estimate the soil volumetric heat capacity and using long-time TRT data to estimate the soil thermal conductivity, and finally verifies the proposed method by comparison with another parameter estimation method and experimental data. The main findings are as follows: there is strong correlation between soil thermal conductivity and coaxial GHE performance, and the correlation between soil volumetric heat capacity and coaxial GHE performance for the early 10 hours is stronger than that after 10 hours; long-time TRT data can lead to more accurate estimation of soil thermal conductivity than early-time TRT data, and early-time TRT data can lead to more accurate estimation of soil volumetric heat capacity than long-time TRT data; the soil thermal properties (especially volumetric heat capacity) estimated by the proposed method have higher precision than those by another method, which uses long-time TRT data to estimate the soil thermal properties.

土壤热特性是设计同轴地下换热器 (GHE) 的重要参数。本文采用精确的半解析模型分析了土壤热特性对同轴 GHE 性能和参数估计的敏感性，然后提出了一种利用早期热响应试验 (TRT) 数据的两步参数估计方法。估计土壤体积热容量，并利用长时间TRT数据估计土壤热导率，最后通过与另一种参数估计方法和实验数据的对比验证了所提出的方法。主要发现如下：土壤热导率与同轴 GHE 性能之间存在很强的相关性，土壤体积热容与同轴 GHE 性能在前 10 小时的相关性强于 10 小时后；长期TRT数据比早期TRT数据可以更准确地估计土壤热导率，早期TRT数据可以比长期TRT数据更准确地估计土壤体积热容量；该方法估计的土壤热特性（尤其是体积热容）比另一种使用长时间TRT数据估计土壤热特性的方法具有更高的精度。