平板过冷却器内结冰行为的实验研究

Experimental Study on Freezing Behavior in Flat-plate Supercooler

本文设计并搭建了一套过冷水动态制冰系统,开发了一种可视化平板过冷却器,通过实验研究流动和换热对过冷却器内结冰行为的影响,并基于经典成核理论与边界层理论对其作用机理进行解释。实验结果表明:平板过冷却器内存在两种典型结冰行为,结冰行为一表现为过冷却器内不结冰,系统可连续制取冰浆;结冰行为二表现为过冷却器内发生结冰,系统不能制取冰浆。载冷剂进口温度过低、制冰溶液流量过大或过小均会促进结冰行为二的出现,不利于系统制冰稳定性。发生结冰行为二时,相对距离d为0.15的壁面优先发生结冰,且该处壁面的温度总低于其余区域,因此优先发生结冰的局部条件是具有更低的壁面温度。

In this study,a dynamic ice-making system with supercooling water was designed and built,and a visual flat-plate supercooler was developed.The influence of flow and heat transfer on the freezing behavior in the flat-plate supercooler was studied by a large number of experiments,and the mechanism was explained by the classical nucleation theory and boundary layer theory.The results shows that there were two types of freezing behavior in the flat-plate supercooler:freezing behavior 1 shows that no freezing occurs in the supercooler and the system can continuously produce ice slurry,and freezing behavior 2 shows that freezing occurs in the supercooler and the system cannot produce ice slurry.The low inlet temperature of the secondary refrigerant and too large or too small flow of ice-making solutions were largely responsible for promoting the occurrence of freezing behavior 2,which was not conducive to the ice-making stability of the system.When freezing behavior 2 occurs,freezing occurs first on the wall with a relative distance d=0.15,where the temperature is always lower than that of the wall with a relative distance d=0.25,0.35,0.45,so the local condition for freezing to occur first is a lower wall temperature.