Anti-fouling performance of chevron plate heat exchanger by the surface modification

摘要

In this study, we aimed to develop a method for modifying SUS304 with microanoscale holes using an electrical etching technique, and evaluated its impact on the anti-fouling performance of chevron plate heat exchangers. The modified SUS304 specimen exhibited hydrophobic wetting characteristics; however, water droplets stuck to the wall under inclined orientations at angles of 30 degrees and 60 degrees. We coated the modified SUS304 specimen with polymer (polymethyl methacrylate; PMMA) and hexagonal boron nitride (BN) particles to realize the hydrophobic and superhydrophobic wetting characteristics. To evaluate the anti-fouling performance of the heat exchanger, we carried out fouling acceleration experiments in a 2000 ppm CaCO3 solution for 2 h. The anti-fouling performance was determined by measuring the overall heat transfer coefficients during fouling acceleration experiments. As the operation time increased, the CaCO 3 particles were deposited on the surface of the heat exchanger, the overall heat transfer coefficient decreased, and the fouling factor ultimately increased. Out of bare, modified, PMMA- and BN-coated heat exchangers, the PMMA-coated heat exchanger exhibited the strongest anti-fouling performance, with the lowest increment in the fouling factor. Based on analysis of the contact angle hysteresis (CAH) in each case, we suggest that CaCO3 particles in solution would be deposited better in the case of the highest CAH. This is possible in cases without the triple contact line, and is caused by filling the polymer into microano holes on the modified surface. (C) 2019 Elsevier Ltd. All rights reserved.