Investigations On Heat Transfer And Anti-Fouling Of Nanometer Surface Treated By Magnetron Sputtering In Pool Boiling System

In this paper, the heat transfer surface was treated by using magnetron sputtering to investigate the anti-fouling characteristic based on the analysis of the mechanics of fouling formation. The surface energy, contact angle of the TiO2-sputtered surfaces and the thin film thickness were measured and characterized to find the relationship between the thin film thickness and the surface energy. It showed that surface free energy of the TiO2-coated copperplate obviously was lower than that of the untreated copperplate and the polished copperplate. It also showed surface free energy of the TiO2-coated copperplate slightly diminished as the thickness of the coatings reduced. The experimental researches on heat transfer and fouling were carried out by using the pool-boiling device. The process of heat transfer and fouling formation on the different heat surfaces were studied with the system of automatic data acquisition. In the distilled water experiment, it showed that heat transfer coefficient of the polished surface was higher than that of the untreated surface. The rule of heat transfer coefficient of the TiO2–sputtered surfaces was not assured while the thickness of the TiO2 coatings changed. In the fouling experiment, when TiO2 was sputtered on the polished surface, its heat transfer coefficient almost did not change with time. While the heat transfer coefficient of the untreated and polished surface dropped quickly with time. Under the same experimental conditions, the heat transfer coefficient of the MgF2-sputtered surface was higher than that of the untreated and polished surface. Compared with the polished surface, its heat transfer coefficient was higher than that of the polished surface. In the fouling experiment, it had anti–fouling characteristic when MgF2 was sputtered on the polished surface. The life of the TiO2-sputtered surface was longer than that of the MgF2-sputtered surface in the fouling experiment for a long time. The TiO2 -coatings of different thickness and the MgF2-coating were compared in a sputtering process and characterized with respect to their morphology, microstructure and chemical composition by scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively.