圆管内CaCO_3污垢生长引起负热阻机理的数值分析  

The Numerical Investigation of the Mechanism of the Negative Thermal Resistence Appered in CaCO_3 Fouling Process on the Inner Tube Wall

作　　者：崔涛[1,2] 王良成[3] 常立民[1,2] 王良璧[1,2] 李素芳[3] 

机构地区：[1]兰州交通大学机电工程学院,甘肃兰州730070 [2]兰州交通大学铁道车辆热工教育部重点实验室,甘肃兰州730070 [3]兰州交通大学化学工程学院,甘肃兰州730070

出　　处：《甘肃科学学报》2016年第4期87-94,共8页Journal of Gansu Sciences

基　　金：国家自然科学基金(51166007);甘肃省财政厅基金(620013)

摘　　要：以实验研究结果为基础,采用数值模拟方法研究了圆管内CaCO_3结晶污垢生长不同时期,污垢对流场和温度场以及壁面传热特性的影响,得到了不同时期Nu/Nu_0随晶体大小的变化关系以及晶体生长过程中Nu/Nu_0随时间的变化关系。研究结果表明,圆管内CaCO_3污垢生长过程中存在负热阻阶段和正热阻阶段,负热阻阶段污垢对传热的阻碍作用小于因污垢存在而引起的扰流对传热的增强效果,即Nu/Nu_0>1,表现为负热阻;而正热阻阶段污垢对传热的阻碍作用大于因污垢存在而引起的扰流对传热的增强效果,即Nu/Nu_0<1,表现为正热阻。Based on experimental results,the fluid flow and heat transfer characteristics enforced by the growth of CaCO_3 crystallization fouling on the inner tube were studied by numerical simulation.Through the analyzing,get the relationship between Nu/Nu_0 and the crystal size in the different period,also get the result of Nu/Nu_0 changes with time in a process of crystal growth.The effects of CaCO_3 crystallization fouling on the flow field,temperature field and the heat transfer coefficient were investigated systematically in different periods of fouling growth.The results showed that there was an induction period,in this period the thermal resistance decreases,and Nu/Nu_01.This means that in this stage the effect of the fouling on heat transfer was less than that of the additional disturbances caused by the fouling.As growing of the fouling,the effect of the fouling on heat transfer is larger than that of the additional disturbances caused by the fouling,Nu/Nu_01,the thermal resistance increases.

关 键 词：圆管 CACO3污垢 负热阻 数值分析 

分 类 号：TB611[一般工业技术—制冷工程]