螺旋桨对冰浆存储冰晶动力学演化的影响研究

发布时间：2018-12-23 10:58

【摘要】：冰浆具有良好的流动性和热传输特性,是一种良好的载冷和蓄冷介质,在空调制冷、食品冷藏等行业中具有广泛的应用前景。蓄冰槽中螺旋桨的机械搅动直接影响冰浆存储特性,而冰浆存储特性对其流动性和热传输性有着重要影响。因此,本文将对蓄冰槽中冰浆存储过程进行模拟,研究螺旋桨对于冰浆存储期间冰晶动力学演化的影响。本文在国家自然科学基金(项目编号：51376198)的大力支持下展开了以下几方面的研究。首先,对冰浆存储过程中的冰浆特性进行分析,得出冰浆存储的数学模型是多相流模型和PBM模型,冰晶与载流溶液之间的相互作用力主要有重力、升力、拖拽力和Safinan力。其次,分析冰晶动力学事件核模型,冰晶的生长和成核已经有比较精确的核模型,而冰晶的破碎与聚集仍缺少合适的核模型。基于上述核模型对冰浆存储过程中冰晶粒径演化过程进行模拟,将平均粒径模拟值和实验值进行分析对比,对冰晶动力学事件核模型参数进行修正,修正后的核模型在模拟冰晶动力学演过过程更有效。最后,基于修正的冰晶动力学事件核模型对蓄冰槽内冰浆的存储过程进行模拟。结果表明：桨叶尺寸对冰晶流动、冰晶体积分数分布、冰晶粒径的数量密度、冰晶平均粒径都有影响；桨叶间距只对于冰晶体积分数分布有影响；双螺旋桨能够使蓄冰槽内冰晶分布更加均匀,更能抑制冰晶生长。
[Abstract]:Ice slurry has good fluidity and heat transfer characteristics and is a good carrier and cold storage medium. It has a wide application prospect in air conditioning refrigeration food refrigeration and other industries. The mechanical agitation of propeller in ice storage tank directly affects the storage characteristics of ice slurry, and the storage characteristics of ice slurry have an important influence on its fluidity and heat transfer. Therefore, in this paper, the ice slurry storage process in the ice storage tank will be simulated to study the effect of propeller on the ice crystal dynamics evolution during ice slurry storage. Supported by the National Natural Science Foundation of China (Project No. 51376198), this paper has carried out the following research. Firstly, the characteristics of ice slurry in ice slurry storage process are analyzed. The mathematical models of ice slurry storage are multiphase flow model and PBM model. The interaction forces between ice crystal and current carrying solution are mainly gravity, lift, towing force and Safinan force. Secondly, the kinetic event nucleation model of ice crystals is analyzed. The growth and nucleation of ice crystals have been more accurate, while the fragmentation and aggregation of ice crystals are still lack of suitable nuclear model. Based on the above kernel model, the evolution process of ice grain size in ice slurry storage process is simulated. The mean particle size simulation value is compared with the experimental value, and the parameters of the ice crystal kinetic event kernel model are modified. The modified nuclear model is more effective in simulating the ice crystal dynamics. Finally, based on the modified ice crystal dynamic event kernel model, the storage process of ice slurry in ice storage tank is simulated. The results show that the blade size has influence on ice crystal flow, ice crystal volume fraction distribution, the number density of ice crystal particle size and the average ice crystal particle size, and blade spacing has only effect on ice crystal volume fraction distribution. The double propeller can make the ice crystal distribution more uniform and restrain the ice crystal growth in the ice storage tank.
【学位授予单位】：中南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB611

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