Study of cyclic operation of RO desalination process

The performance of a tubular reverse osmosis (RO) process for water desalination was investigated when the unit was periodically forced. The study was performed using a dynamic model that was developed and validated in a previous work of the authors [Al-haj Ali et al., Desalination; 245, 194–204 (2009)]. The forcing was carried out through feed pressure using both symmetric and asymmetric rectangular pulses. For a symmetric pulse, it was found that the permeate flow rate increased monotonically with the forcing amplitude. The improvement in the permeate flow rate was limited by the constraints on the operating pressure. For an asymmetric pressure pulse, the permeate flow rate reached a clear maximum for some values of ratio of pulse width to the period. For both pulses, the model predicted that the enhancement in the permeate flow rate was attributed to the reduction in the effect of concentration polarisation. Moreover, the trends obtained with both symmetric and asymmetric shapes were consistent with the experimental results reported in the literature. On a analyse le rendement d'une osmose inverse (OI) tubulaire pour le dessalement de l'eau lorsque l'unite etait forcee de facon periodique. L'etude a ete realisee en utilisant un modele dynamique cree et valide dans un travail anterieur des auteurs [Al-haj Ali et al., Desalination 245, 194–204 (2009)]. Le forcage a ete realise par une pression d'alimentation en utilisant a la fois des impulsions rectangulaires symetriques et asymetriques. Pour une impulsion symetrique, on a trouve que le debit de permeation augmentait monotonement avec l'amplitude de forcage. L'amelioration du debit de permeation etait limitee par les contraintes de la pression de fonctionnement. Pour une impulsion de pression asymetrique, le debit de permeation a atteint un maximum clair pour certaines valeurs de ratio de largeur d'impulsion pour la periode. Pour les deux impulsions, le modele a predit que l'accroissement du debit de permeation etait attribue a la reduction de l'effet de la polarisation de concentration. De plus, les tendances obtenues a la fois pour les formes symetriques et asymetriques correspondaient aux resultats experimentaux de la litterature.