Thermal energy storage systems based on phase change materials (PCM) are used to shift the peak load in buildings. An effective method to improve the performance of such system is to bury it in the soil to take advantage of soil’s high thermal inertia. In this study, the model of underground buried water tank integrated with PCM panels as thermal accumulators is firstly proposed for a heat pump system. The study is conducted using an experimentally validated numerical model based on a heat balance approach using the effective heat capacity method. The performances of the buried water-PCM tank and an insulated water-PCM tank were compared to determine the improvement in the system efficiency as the results of soil’s thermal inertia. A parametric study was also conducted to determine the optimal configuration and operating strategy of the buried water-PCM tank to satisfy the requirement of heat pump systems for load shifting. The outlet temperature, effective discharge duration (EDD), and total released heat were used as the indicators. The cooling capacity of the buried water-PCM tank is 24.96% higher than that of the insulated tank. The parametric study indicates that the parameters influencing the tank performance are the thermal conductivity of the PCM, length and width of the PCM panels, and heat transfer fluid velocity in the gaps between the panels. The study results are expected to serve as reference for the application of the newly proposed buried water-PCM tank in the underground engineering for load shifting.

基于相变材料（PCM）的热能存储系统用于转移建筑物的峰值负荷。改善这种系统性能的有效方法是将其埋在土壤中，以利用土壤的高热惯性。在这项研究中，首先提出了一种将热电偶系统与PCM面板集成为蓄热器的地下储水罐模型。这项研究是使用实验验证的数值模型进行的，该模型基于使用有效热容量方法的热平衡方法。比较了埋入式水-PCM储罐和保温水-PCM储罐的性能，以确定土壤热惯性导致系统效率的提高。还进行了参数研究，以确定埋水式PCM储罐的最佳配置和运行策略，以满足热泵系统进行负荷转移的要求。出口温度，有效放电持续时间（EDD）和总释放热量用作指标。埋入式PCM水箱的冷却能力比保温水箱高24.96％。参数研究表明，影响储罐性能的参数是PCM的热导率，PCM面板的长度和宽度以及面板之间间隙中的传热流体速度。研究结果有望为新近提出的埋藏式PCM水箱在地下工程中用于负荷转移的应用提供参考。