Study On Microbiol Fouling Characteristics On Ni-P-PTFE Modified Surface

Microbial fouling is widely present on the surface and inside of various equipment in industrial circulating cooling water systems,drinking water systems and seawater systems.In the industrial circulating cooling water system,the formation of microbial fouling will reduce the heat exchange efficiency of the heat exchange equipment,resulting in great energy waste.The existence of temperature gradient makes the formation of microbial fouling on the heat exchange equipment more complicated,which makes the inhibition and removal of microorganisms on the heat exchange equipment more difficult,but the modified surface technology can effectively inhibit the formation of microorganisms.In this paper,Q235carbon steel with a thickness of 0.5 mm was used as the experimental substrate,and Q235carbon steel was cut into carbon steel sheets with a size of 30×30 mm~2.The Ni-P-PTFE modified surface was prepared by electroless plating process.The elemental surface was analyzed for elemental content and surface morphology.Subsequently,the stability of the Ni-P-PTFE modified surface combined with carbon steel was tested by a cleaning experiment.The results show that the Ni-P-PTFE modified surface is well bonded to the carbon steel substrate and can be applied in practice.The Ni-P-PTFE modified surface with different surface energy was prepared by changing the content of surfactant in the Ni-P-PTFE modified surface formulation.The results show that with the increase of surfactant content,the content of PTFE nanoparticles increases,and the surface energy of Ni-P-PTFE modified surface decreases.Using iron bacteria as a scale-causing strain,the anti-scaling and corrosion-resistance of Ni-P-PTFE modified surface and the surface energy of modified surface on the deposition of iron bacteria fouling were studied by microbial static experiment.The results show that the amount of fouling deposited on the surface of the test piece is first reduced and then increased.Compared with carbon steel,the Ni-P-PTFE modified surface with a surface energy of 32mJ/m~2has a 97.97%reduction in Ni-P-PTFE modified surface fouling and a 96.56%reduction in corrosion weight loss.Using distilled water as working fluid,the influence of Ni-P-PTFE modified surface on heat transfer coefficient was studied by flow heat exchange test bench.The results show that the reduced heat transfer coefficient after applying Ni-P-PTFE modified surface is about4.59%~9.24%of the total heat transfer coefficient.The anti-scaling and corrosion resistance of Ni-P-PTFE modified surface under flow heat transfer was studied.Ni-P-PTFE modified surface fouling thermal resistance asymptotic value is smaller than carbon steel surface,Ni-P-PTFE modified surface has good anti-scaling and corrosion resistance under flow heat transfer conditions.Finally,the influence of low temperature medium flow rate,temperature and concentration on the fouling of Ni-P-PTFE modified surface was studied.The results show that with the increase of flow rate,the shearing force of the low temperature medium on the heat transfer surface increases,the erosion rate increases and the deposition rate decreases.The fouling induction period of the Ni-P-PTFE modified surface increases,and the fouling thermal resistance asymptotic value reduce.When the concentration of iron bacteria increases,the attenuating value of the thermal resistance of the dirt increases,but the fouling induction period becomes shorter due to competition of the organism.In the appropriate temperature range,as the inlet temperature of the iron bacteria suspension increases,the asymptotic value of the thermal resistance of the dirt increases first and then increases.