The Study On Heat Transfer And Anti-Fouling Of Evaporator With Surface Treatment

The fouling easily is formed on the heat transfer surface in the boiling process. The efficiency of heat transfer will fall down while the consumption of energy and material will increase for the existence of fouling.Research shows that the formation of fouling is related with the adhesion between fouling and heat transfer surface .While the adhesion is related with the surface energy, the bigger the surface energy, the bigger the adhesion. So if reduce the surface energy, it will reduce the formation of the fouling on the heat transfer surface. Treating the heat transfer surface with surface treatment technology can reduce the surface energy. In this paper, the mechanics of fouling formation are summarized; The heating surface is treated by using liquid deposition. That is used to the research of anti-fouling. The surface energy, contact angle of the treated surface and thin film thickness are measured and attributed to get the relationship between the thin film thickness and the surface energy. The results show that as the heating surfaces are treated properly so to reduce the surface energy.The thinner the layer, the lower the surface energy. The research on heat transfer and fouling are made by flow boiling device, the process of heat transfer and fouling formation on the different heating surface are studied by automatic data acquisition system. The experiment results show that when the thin film thickness is 1587nm, as compared with the untreated heating surface its heat transfer coefficient is 6%-14% bigger than the untreated surface, when the thin film thickness is 141nm, as compared with the untreated surface its heat transfer coefficient is 10%~44% bigger than the untreated surface. In the fouling experiment, when the thin film thickness is 141nm, its heat transfer coefficient almost dose not change within a certain time.When the thin film thickness is 1587nm, its heat transfer coefficient drops a little within a certain time, while the heat transfer coefficient of the untreated heating surface drops quickly within the operating time. Heating surface is treated by liquid deposition, its effect of heat transfer enhancement and anti-fouling is good. The experiment results also show that the thinner the layer, the better the effect. The surface energy is reduced so to reduce the wetting effect of heating surface, where upon the fouling can not easily is formed on the surface.