Study on Improvement of Effective Volume Ratio in Multi-Connected Thermal Storage Tank

设计高有效容积比的多连通水蓄冷箱具有重要意义。本课题通过实验和数值模拟的方法，研究了连接口的大小、位置以及连接口内的流速分布对储罐混合性能的影响。通过三种不同连接孔大小和位置的试验，研究了连接孔大小和位置对混凝土强度的影响。研究发现，在储存温差较大或水流量较小的情况下，由于浮力分流的存在，连接口的位置对罐内混合性能影响较大.连接开口中的速度分布用从伯努利方程导出的模型计算。由两侧水箱的流量和水密度得到开口两侧的静水压力差。计算得到的速度剖面与实验结果吻合较好。在罐底高温输入条件下，研究了两种模型作为罐内混合模型。一种是流量从孔口到水面呈线性分布的模型。另一种是从开口向上形成浮力羽流的模型。结果表明，烟羽模型具有上级物理性能，计算得到的罐内温度分布与实验结果基本吻合。

It is important to design multi-connected water thermal storage tanks with high effective volume ratio. In this project, effect of the connecting opening size and position and the velocity profile in the connecting opening on mixing property of the storage tank were studied by means of experiments and simulations as follows :1. Effect of the connecting opening size and position were studied by three type experiments which had the connecting opening of different size and position. In case of large storage temperature difference or little water flow rate, it was found that the position of the connecting opening has great effect on the mixing property in the tank because of buoyant bypass flow.2. The velocity profile in the connecting opening was calculated with a model derived from the Bernoulli's equation. The static water pressure difference between both side of the opening was obtained from flow rate and water density of both side tanks. The calculated velocity profile agreed well with experiment results. Two models were studied as mixing model in the tank under high temperature input from bottom opening. The one is a model in which flow rate is distributed from the opening to water surface linearly. The other is a model in which a buoyant plume is formed upward from the opening. The plume model was proven to be superior physically and calculated temperature profiles in the tank agreed roughly with the experiment results.