影响换热面结垢诱导期的表面特性研究

Influence of Heat Transfer Surface Characteristics on Fouling Induction Period

换热面结垢是一个普遍存在的问题,而结垢诱导期的长短对污垢形成过程具有重要的影响,即使在相同实验条件下,不同材料换热面的结垢诱导期仍相差较大。因此本文通过对附着在换热面上的半球形污垢晶核进行受力分析,发现污垢晶核与换热面之间的附着力对其结垢诱导期长短起决定性作用,然后根据颗粒与平板间附着力模型,计算了污垢晶核与具有不同表面能的换热面间附着力,并与相应的结垢诱导期进行对比。结果表明:结垢诱导期的长短与换热面的表面能、污垢晶核与换热面间的附着力及表面粗糙度尺度有关。

Fouling on heat transfer surfaces has been recognized as a widespread problem in heat exchangers and the length of fouling induction period has important effect on all fouling process. Even if in the same experimental condition, the different surfaces present the different fouling induction period. In this paper, the force balance analysis, which is derived for a hemispherical fouling particle on heat transfer surface, reveals that the adhesion forces of both particle and surfaces have significant influence on the fouling induction period. The effects of surface free energy on adhesion forces of particle - surfaces have been investigated according to the mode of particle - surface interaction. The adhesion forces of both particle and surfaces are calculated, and compared with their fouling induction period. Results show that the surface free energy, adhesion force and the roughness scale effect on the fouling induction period.