Characteristics Research Of CaCO₃ Crystallization Fouling On Obique Fin Tube

The performance of heat exchanger depends on its heat transfer coefficient. To enhance the heat transfer technology is to develop a variety of ways to improve the heat transfer coefficient. However, the fouling attached to the heat exchanger will decrease the capacity of heat transfer. Therefore, the design performance of heat exchanger will not be fulfilled. Fouling has influenced many areas. According to this, how to suppress and prevent fouling is significant.Two methods of experiments has been taken to investigate the crystallization of calcium carbonate fouling on straight and saw-tooth oblique fin tube and plain tube in this thesis. The influence of different flow rates, calcium concentration and geometric parameters of the tube to the crystallization of calcium carbonate fouling and to the fouling resistance has been considered. The first experiment method is to keep the concentration of calcium carbonate constant. And its results showed that with the increase of flow rate or the decrease of calcium carbonate concentration, the induction period of fouling became longer, and the fouling resistance became smaller. Under the same flow rate and the same calcium carbonate concentration, the fouling amount and the fouling resistance of the straight oblique fin tube and the saw-tooth oblique fin tube were higher than plain tube, but still, the overall heat transfer coefficient of the former two tubes were higher than the plain tube’s. So under the same condition, it’s better to use enhanced tubes to get the larger coefficient of heat transfer. The second experiment is to make the initial concentration of calcium carbonate constant. And its results showed that with the increase of flow rate, the fouling resistance became smaller. When concentration increases, the asymptotic fouling resistance is not always increasing. In the appropriate concentration, the asymptotic fouling thermal resistance is the largest.This research is support by the Shanghai Leading Academic Discipline Project(S30503) and the Innovation Fund Project For Graduate Student of Shanghai(JWCXSL1202).