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进行光管和平直斜翅管在不同碳酸钙浓度和流速下的动态结垢实验,得到碳酸钙浓度、流速和平直斜翅管对碳酸钙析晶污垢结垢过程的影响。结果表明:浓度增大使溶液中均相成核速率和所形成晶核的生长速率增大,使溶液换热表面界面的污垢晶粒浓度和成垢离子浓度均增大;前者使更多的污垢附着换热面,而后者使表面异相成核速率和生长速率增大。流速增大使光管表面形成的晶核、污垢晶体和污垢热阻均减少而诱导期延长;平直斜翅管初始成核增多,但诱导期延长、而结垢量和污垢热阻减小。平直斜翅管在清洁状态和结垢状态下均具有比光管更大的总换热系数、更小的污垢热阻,尽管结垢量略多。
The dynamic fouling experiments were carried out under different concentrations and velocities of calcium carbonate, and the effects of calcium carbonate concentration, flow rate, and straight beveled fin tube on the fouling process of calcium carbonate crystals were investigated. The results show that the increase of the concentration leads to the increase of the homogeneous nucleation rate and the growth rate of the formed nuclei in the solution, resulting in the increase of the concentration of the fouling grains and the fouling ions in the interface of the solution heat transfer surface. The former makes more fouling Attached to the heat transfer surface, while the latter increases the heterogeneous nucleation rate and growth rate of the surface. The increase of flow rate reduced the thermal resistance of crystal nucleus, fouling crystal and fouling formed on the surface of the light pipe and prolonged the induction period. The initial nucleation of straight beveled fin increased but the induction period prolonged while the fouling amount and fouling resistance decreased. Straight beveled finned tubes have a greater overall heat transfer coefficient and a lower resistance to fouling, both in the cleaned state and in the fouled state, although the amount of fouling is slightly greater.