中图分类号：TK513.5 文献标志码：A

Simulation study on heat storage characteristics of molten salt by moving baffle

AO Xuelian， ZHU Zhiwei， ZHOU Ruirui （SchoolofEnergyandPower Engineering， UniversityofShanghai forScienceandTechnology，Shanghai 2Oo093，China）

Abstract： In order to optimize the heat storage performance of the single-tank molten salt heat storage system， the influence law of setting moving baffles in the storage tank on the heat storage process was discussed. The influence of the moving bafle on the heat transfer of molten salt flow in the tank was studied by numerical simulation method. The dynamic movement of the bafle was simulated based on the dynamic grid and grid adaptive technology. The heat storage processes before and after the settig of the baffle were compared， and the influence of the moving baffle on the heat transfer of the heat storage fluid flow was analyzed. On this basis， the influence of the moving speed and size of the moving baffle on the heat storage performance of the system was further discussed. The results show that the moving baffle can promote the flow heat transfer of molten salt and enhance the heat storage capacity of the tank compared with the case without baffle. The size of the baffle has a litle effect on the heat storage process， while the moving speed of the baffle has a significant effect on it. Within the range of parameters studied， the thermal storage time of the system can be reduced by up to 17.65% with the addition of the baffle， and the thermal storage efficiency can be increased by up to 11.65% . Further results found that the heat transfer of molten salt can be promoted when the moving bafle is always above the thermocline， while it is weakened when it is below the thermocline. Therefore， setting up moving bales in the storage tank is an effective way to improve the performance ofthe molten salt heat storage system. The speed of the baffles and their positional relationship with the thermocline are the key factors affecting the heat storage efficiency.

Keywords： heat storage of molten salt; dynamic grid; moving baffles; thermal performance

储能技术是解决可再生能源间歇性和不稳定性问题的关键技术之一，有助于实现能源供需平衡，提高能源利用效率[1-5]。单罐熔盐蓄热系统是一种以熔盐作为蓄热工质，将高温和低温熔盐共同储存在一个罐体中的蓄热系统。由于工作温度范围广、占地面积小、成本低等优点，在电力调峰、余热回收、太阳能热利用等领域已有广泛的应用[6-10]。在单罐蓄热系统中，冷热流体依靠密度差和重力形成了稳定的冷热流体分层，其中高温流体到低温流体的温度跃变区域称为斜温层。斜温层的稳定性会影响系统的有效蓄热量，从而影响系统的蓄热性能[1-14]。因此，如何改善单罐蓄热系统的蓄热性能是研究的焦点。

蓄热罐蓄热性能的提高多数通过改善蓄热罐结构来调整内部流体的流动行为，从而得到理想的热分层和斜温层厚度，最终实现蓄热效率的提升。Ievers等[15]通过数值分析方法研究了蓄热罐形状和运行条件对蓄热效果的影响，结果表明，增加罐体的纵横比并降低进出口流量能够减小斜温层厚度，提高蓄热罐的热分层水平和蓄热效率。为探究在罐内添加挡板对蓄热罐蓄热性能的影响，Erdemir等[1通过实验和数值分析方法，研究了蓄热罐内4种不同类型挡板的位置对蓄热性能的影响，经计算分析得到罐内有挡板且将挡板放置在距离罐底 200～300mm 的位置能够取得最好的热分层效果，提高蓄热量，从而提升蓄热性能。Paing等[17]模拟研究了竖直挡板的长度和位置对蓄热罐内对流换热的影响。……