Moving Mesh-based Dynamic Numerical Simulation For The Process Of Retaining Pollution On Ultrafiltration Membrane

During operation of the membrane, the membrane pollution has been one of the major problems constraining the development and application of membrane technology. An effective solution to the problem of membrane fouling is the key to optimize the operating conditions of the membrane module and extend the period of operation.Studying the mechanism of contamination and understanding adequately the process of membrane fouling is the core of the problem. Because many factors affect membrane fouling process, experimental and theoretical studies are indispensable research tools. Due to cost constraint and measuring instruments, experiment measures usually can not research on membrane pollution accurately and extensively, which requires a combination of powerful mathematical model to obtain in-depth and comprehensive understanding on this issue. In recent years, there have been a lot of membrane filtration process simulation and optimization work based on computational fluid dynamics(CFD). This method not only can visually obtain various flow parameters within the membrane by numerical simulation, but also optimize membrane filtration characteristics and operating conditions, and even can also get the valuable information in some cases that is unable to carry out experimental studies.The current research of numerical simulation on membrane fouling focused on flow field and concentration distribution, as well as trapping pollutants and eluting in situation of steady state or quasi-steady state. However, because membrane fouling process is dynamic process of complex multi-physics interaction. Different from the existing analytical solutions and the static numerical simulation, this paper aims at the problem of ultrafiltration membrane fouling. We established the CFD–based research means with moving mesh skill. Membrane is considered as a porous medium.The physical model coupled free flow, porous media flow and diluted species transport process. Grid velocity at the pollutant interface was decided by the summing of normal accumulation of pollutants and the tangential shear elution. The dynamic simulation process about retaining pollutants on the membrane surface was realized. This paper obtains the flow field and concentration distribution of the internal pressure hollow fiber ultrafiltration membrane component, and concentration polarization phenomenon on membrane surface by numerical simulation. Then the matching parameters in this expression were determined by a hollow fiber membrane module experiments. When the pollutants interception matching parameters 1 is 2003/mol and shear matching parameters 2 is 5 × 10-15 m, the numerical simulation result is consistent with two groups experimental data. We can carry out the same type study of pollutants interception after determining those parameters.On the basis of the established dynamic model, we studied the filtration performance with the different membrane surface pattern(flat membrane and sinusoidal patterned membrane). The study showed that the distribution of shear stress on flat membrane was more uniform and the flux decreased significantly. However, after a period of time, the special shape sinusoidal patterned membrane generated an uneven distribution of shear stress on the peaks and valleys region, by which the better anti-pollution performance was obtained and the membrane can maintain a certain degree of filtration flux for a long time. In summary, the established model provides an effective means for the in-depth study of pollutants interception process and optimizing design of the membrane module.