The aim of the study is to investigate the influence of geometry on the thermal capacity and stratifications of a water pit heat storage for solar district heating. A TRNSYS component model for a truncated cone water pit was developed based on the coordinate transformation method and validated by experimental results from the water pit heat storage in Huangdicheng in 2018. The thermal performance of 26 water pits with different heights and side wall slopes was calculated for 10 consecutive years. It takes four to six years for the water pit to reach steady-state operation. The operation data from the tenth year was selected to evaluate the thermal performance of each configuration. The results show that because of the thermal insulation on top of the water pit, the height to diameter ratio of a water pit with minimum annual heat loss was always smaller than 1.0. The annual storage efficiency of a water pit increases with side wall slope due to the reduced side wall area. There is an almost linear increase in the thermal stratification number of a water pit with height. With an increase in the height, thermal stratification in water pits with a steeper slope increased more gradually than water pits with a lower slope. The findings in this paper are relevant for the design optimization of water pits as seasonal thermal energy storages.

该研究的目的是研究几何形状对太阳能集中供热水坑蓄热器的热容量和分层的影响。基于坐标变换法建立了截锥水坑TRNSYS组件模型，并通过2018年黄帝城水坑蓄热实验结果进行了验证。计算了26个不同高度和侧壁坡度的水坑的热性能。连续十年。水坑要达到稳态运行需要四到六年的时间。选择第十年的运行数据来评估每种配置的热性能。结果表明，由于水坑顶部的隔热，年热损失最小的水坑高度与直径之比始终小于1.0。由于侧壁面积的减小，水坑的年存储效率随着侧壁的倾斜而增加。水坑的热分层数几乎随高度线性增加。随着高度的增加，坡度较陡的水坑的热分层比坡度较小的水坑的热分层逐渐增加。本文的发现与季节性热能储水坑的设计优化有关。坡度较陡的水坑的热分层比坡度较小的水坑的热分层逐渐增加。本文的发现与季节性热能储水坑的设计优化有关。坡度较陡的水坑的热分层比坡度较小的水坑的热分层逐渐增加。本文的发现与季节性热能储水坑的设计优化有关。