Study On Hydrodynamic Characteristics Of Tubular Membrane

The tubular membrane has the advantages of wide flow channel, no easy to pollution, easy cleaning, low cost and low accuracy of the feed liquid.in recent years has been widely used in the field of liquid separation. Seeking to reduce and eliminate concentration polarization and membrane fouling in membrane filtration process, the method of strengthening membrane filtration process, has always been a hotspot in research of membrane. So the fluid dynamics research of membrane filtration process is very important. This article through experiment,CFD and basic theory formula three methods to study the fluid mechanics of tubular membrane filtration process.First of all, made tubular membrane module, and set up the test bed. Set up the mathematic calculation model of Pure water during the process of tubular membrane filtration.Marching on membrane component 80 kpa constant pressure, seven different flow and 10001/H constant flow, five different pressure filtration process has carried on the calculation and analysis, reveals the internal flow characteristics, Verified by the experiment, simulation results are in good agreement with the experimental value. Analysis results show that the flow to the membrane on the surface of the lining erosion ability stronger, the greater the disturbance is more intense, penetrating flow vortex bigger, transmembrane pressure difference is bigger. Membrane tube with the increase of axial distance linear pressure decreases, the pressure value of the slope of the linear decrease k as flow decreases with the increase of Q (L/H), the relationship basic accord with k=-0.0125 Q.The radial velocity and the seepage water volume increased obviously with the increase of outlet pressure, pressure increases more than flow increase can increase the filtered water.Second, calculation and analysis with the contrast velocity to 8 mm and 12.8 mm of two different membrane tube diameter of membrane module, the results show that the smaller the diameter of turbulent the kinetic energy and the pressure become greater, under the condition of the same filtration water, consume less energy. The smaller of the diameter, the axial velocity in the center of the near wall area and membrane tube area difference is smaller, the greater the pressure value of the slope of the linear decrease.Third, through the experiment, the pipe flow equation of basic theory, using porous media model CFD simulation research and no penetrate wall model CFD simulation research, four methods to the analysis of the characteristics of the tubular membrane module in pressure. The results show that the theoretical formula calculation is close to the no seepage wall CFD analysis. Porous wall CFD analysis is close to the experimental values. So the theory model built by this article is more suitable for the filtration process of tubular membrane module, The research method of no penetrate wall has a bigger error.Finally, Under the same inlet velocity and outlet pressure, five different penetration resistance coefficient was calculated, the results show that the smaller the permeability coefficient of resistance is, the filtration water volume is greater, the axial velocity, turbulent kinetic energy, and the pressure value is smaller. With the increase of axial distance, the difference of axial velocity, turbulent kinetic energy and the pressure value under different penetration resistance coefficient is becoming bigger. Because of the filtration water increases, the radial velocity increases with the decrease of the penetration resistance coefficient obviously. Under different penetration resistance coefficient, the pressure value curve are linearly decreasing trend, and the bigger permeability resistance coefficient has a bigger slope. Different penetration resistance coefficient of membrane module in L=460 mm pressure values are equal, the curve converges.