A Study on the Evaluation of Flow Distribution Evenness in Parallel-Arrayed Type Low Pressure Membrane Module Piping

Abstract

Objectives : In this study, the degree of uniformity of the flow rate flowing into each module is measured for the external pressure typed low-pressure membrane (microfiltration) filtration process that has been actually applied to water treatment, and computational fluid dynamics (CFD) technique is used to clarify the cause and effect.Methods : Mobile ultrasonic flow meter was used to measure the flow rate flowing from the membrane module pipe to each module, and the CFD technique was used to verify this.Results and Discussion : From the results of the actual measurement using ultrasonic flowmeter and CFD simulation, it was confirmed that the outflow flow rate from the branch pipe located at the end of the header pipe was three times higher than that of the branch pipe near the inlet. The reason was that the differential pressure generated between each membrane module was higher toward the end of the header pipe.Conclusions : When the ratio of the sum of the cross-sectional area of the branch pipe and the cross-sectional area of the header pipe was reduced by about 30 times, it was confirmed that the flow rate flowing from each branch pipe to the membrane module was almost equal. Also, If the flow in the header pipe is transitional or laminar (Reynolds No. is approximately 4,000 or less), the flowrate flowing from each branch pipe to the membrane module can be more even.