No 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.

This work presents an analytical and numerical methodology that allows determining stress distribution during the functioning of a screw conveyor utilized for conveying granular material. Different operating conditions were studied analytically and numerically. Initially, the reactions generated when the mechanism was fully braced with four supports along the longitudinal axis of the shaft were estimated. In addition, the system was analyzed with a typical fault in one of the central supports. The faults studied occur primarily due to the empirical modifications that companies make to these kinds of mechanisms and to the continuous operation of the conveyor system. Finally, a comparative analysis is presented between the analytical and the numerical results in order to validate the proposed methodology.