Documents disponibles écrits par cet auteur

Effect of thermodynamic restriction on energy cost optimization of RO membrane water desalination / Aihua Zhu in Industrial & engineering chemistry research, Vol. 48 N° 13 (Juillet 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 13 (Juillet 2009) . - pp. 6010–6021 Titre : Effect of thermodynamic restriction on energy cost optimization of RO membrane water desalination Type de document : texte imprimé Auteurs : Aihua Zhu, Auteur ; Panagiotis D. Christofides, Auteur ; Yoram Cohen, Auteur Année de publication : 2009 Article en page(s) : pp. 6010–6021 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Reverse  osmosis  membranes  Water  production Résumé : Advances in highly permeable reverse osmosis (RO) membranes have enabled desalting operations, in which it is practically feasible for the applied pressure to approach the osmotic pressure of the exit brine stream. However, energy cost remains a major contributor to the total cost of water produced by RO membrane desalination. Reduction of the overall cost of water production represents a major challenge and, in the present work, various elements of water production cost are evaluated from the viewpoint of optimization, with respect to various costs (energy, membrane area and permeability, brine management, and pressure drop), as well as the important thermodynamic cross-flow constraint, utilization of energy recovery devices, and operational feed and permeate flow rate constraints. More specifically, in the present study, an approach to the optimization of product water recovery at pressures that approach the osmotic pressure of the exit brine stream is presented via several simple RO process models that utilize highly permeable membranes. The results suggest that it is indeed feasible to refine RO processes to target for operation under the condition of minimum energy consumption, while considering the constraint imposed by the osmotic pressure, as specified by the thermodynamic cross-flow restriction. Although it is shown that multistage RO provides energy savings, this is at the expense of greater membrane area cost. Overall, as process costs above energy costs are added, the operational point for achieving minimum water production cost shifts to higher recoveries. Although the newer generation of RO membranes can allow high recovery operations at lower pressures, limitations due to mineral scaling and fouling impose additional constraints. The incorporation of these phenomena in the optimization approach is the subject of ongoing research. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800735q [article] Effect of thermodynamic restriction on energy cost optimization of RO membrane water desalination [texte imprimé] / Aihua Zhu, Auteur ; Panagiotis D. Christofides, Auteur ; Yoram Cohen, Auteur . - 2009 . - pp. 6010–6021. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 13 (Juillet 2009) . - pp. 6010–6021 Mots-clés : Reverse  osmosis  membranes  Water  production Résumé : Advances in highly permeable reverse osmosis (RO) membranes have enabled desalting operations, in which it is practically feasible for the applied pressure to approach the osmotic pressure of the exit brine stream. However, energy cost remains a major contributor to the total cost of water produced by RO membrane desalination. Reduction of the overall cost of water production represents a major challenge and, in the present work, various elements of water production cost are evaluated from the viewpoint of optimization, with respect to various costs (energy, membrane area and permeability, brine management, and pressure drop), as well as the important thermodynamic cross-flow constraint, utilization of energy recovery devices, and operational feed and permeate flow rate constraints. More specifically, in the present study, an approach to the optimization of product water recovery at pressures that approach the osmotic pressure of the exit brine stream is presented via several simple RO process models that utilize highly permeable membranes. The results suggest that it is indeed feasible to refine RO processes to target for operation under the condition of minimum energy consumption, while considering the constraint imposed by the osmotic pressure, as specified by the thermodynamic cross-flow restriction. Although it is shown that multistage RO provides energy savings, this is at the expense of greater membrane area cost. Overall, as process costs above energy costs are added, the operational point for achieving minimum water production cost shifts to higher recoveries. Although the newer generation of RO membranes can allow high recovery operations at lower pressures, limitations due to mineral scaling and fouling impose additional constraints. The incorporation of these phenomena in the optimization approach is the subject of ongoing research. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800735q

Energy consumption optimization of reverse osmosis membrane water desalination subject to feed salinity fluctuation / Aihua Zhu in Industrial & engineering chemistry research, Vol. 48 N° 21 (Novembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 21 (Novembre 2009) . - pp. 9581–9589 Titre : Energy consumption optimization of reverse osmosis membrane water desalination subject to feed salinity fluctuation Type de document : texte imprimé Auteurs : Aihua Zhu, Auteur ; Panagiotis D. Christofides, Auteur ; Yoram Cohen, Auteur Année de publication : 2010 Article en page(s) : pp. 9581–9589 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Reverse  osmosis  water  desalination  Feed  concentration  fluctuation  Time-varying  optimal  operation  strategy Résumé : We study the energy consumption optimization of a reverse osmosis water desalination process producing a constant permeate flow in the presence of feed concentration fluctuation. We propose a time-varying optimal operation strategy that can significantly reduce the specific energy consumption compared to time-invariant process operation. We present both computational and experimental results that demonstrate the effectiveness of the proposed optimal operation policy. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900729x [article] Energy consumption optimization of reverse osmosis membrane water desalination subject to feed salinity fluctuation [texte imprimé] / Aihua Zhu, Auteur ; Panagiotis D. Christofides, Auteur ; Yoram Cohen, Auteur . - 2010 . - pp. 9581–9589. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 21 (Novembre 2009) . - pp. 9581–9589 Mots-clés : Reverse  osmosis  water  desalination  Feed  concentration  fluctuation  Time-varying  optimal  operation  strategy Résumé : We study the energy consumption optimization of a reverse osmosis water desalination process producing a constant permeate flow in the presence of feed concentration fluctuation. We propose a time-varying optimal operation strategy that can significantly reduce the specific energy consumption compared to time-invariant process operation. We present both computational and experimental results that demonstrate the effectiveness of the proposed optimal operation policy. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900729x

Nonlinear model-based control of an experimental reverse-osmosis water desalination system / Alex R. Bartman in Industrial & engineering chemistry research, Vol. 48 N° 13 (Juillet 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 13 (Juillet 2009) . - pp. 6126–6136 Titre : Nonlinear model-based control of an experimental reverse-osmosis water desalination system Type de document : texte imprimé Auteurs : Alex R. Bartman, Auteur ; Panagiotis D. Christofides, Auteur ; Yoram Cohen, Auteur Année de publication : 2009 Article en page(s) : pp. 6126–6136 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Reverse-osmosis  membrane  water  desalination  system  Nonlinear  model-based  control  system Résumé : This work focuses on the design and implementation of a nonlinear model-based control system on an experimental reverse-osmosis (RO) membrane water desalination system to address large set-point changes and variations in feedwater salinity. A dynamic nonlinear lumped-parameter model is derived using first-principles, and its parameters are computed from experimental data to minimize the error between model predictions and experimental RO system response. This model then is used as the basis for the design of a nonlinear control system, using geometric control techniques. The nonlinear control system is implemented on the experimental RO system, and its set-point tracking and disturbance rejection capabilities are successfully evaluated. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900322x [article] Nonlinear model-based control of an experimental reverse-osmosis water desalination system [texte imprimé] / Alex R. Bartman, Auteur ; Panagiotis D. Christofides, Auteur ; Yoram Cohen, Auteur . - 2009 . - pp. 6126–6136. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 13 (Juillet 2009) . - pp. 6126–6136 Mots-clés : Reverse-osmosis  membrane  water  desalination  system  Nonlinear  model-based  control  system Résumé : This work focuses on the design and implementation of a nonlinear model-based control system on an experimental reverse-osmosis (RO) membrane water desalination system to address large set-point changes and variations in feedwater salinity. A dynamic nonlinear lumped-parameter model is derived using first-principles, and its parameters are computed from experimental data to minimize the error between model predictions and experimental RO system response. This model then is used as the basis for the design of a nonlinear control system, using geometric control techniques. The nonlinear control system is implemented on the experimental RO system, and its set-point tracking and disturbance rejection capabilities are successfully evaluated. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900322x