DESIGN AND MANUFACTURING OF A PULSATILE VALVE FOR GENERATING VARIABLE FLOWS IN REVERSE OSMOSIS DESALINATION MODULES

Abstract

It has been reported that pulsatile flow promotes greater permeate in reverse osmosis (RO) operations through the generation and shedding of vortices, increasing mass transfer and hindering the onset of fouling through the effect of higher shear rate. In this project, a valve has been manufactured that generates pressure variations in water flow as determined by simulation studies at pressures between 4826 and 6205 kPa, flow rates in the range of 0.6 to 1.2 L/min, and a range of frequencies from 10 to 45 Hz, in order to increase the permeate flow in RO desalination modules. In addition, its performance is experimentally tested. For its development, the engineering design method is employed using Newton´s second law, the conservation law -applying Bernoulli´s principles, as well as the angular momentum equation. The best result using RO membranes is under pulsatile flow induced in the feed flow at Q = 0.6 L/min, p = 6205 kPa and f = 40 Hz when the flow is not turbulent. The generated pulsatile flow increases the quantity of permeated water, reduces the formation of fouling layers on the membrane and consequently reduces the frequency of membrane replacement. The pulsatile valve has the necessary requirements in order to be part of any RO system.