Search results for "Membrane proce"
showing 10 items of 27 documents
Modelling and cost analysis of hybrid systems for seawater desalination: Electromembrane pre-treatments for Reverse Osmosis
2019
Abstract The need to reduce energy consumption in seawater Reverse Osmosis (RO) process has pushed research towards the development of new hybrid systems in which, for example, other membrane processes can be used to pre-treat seawater. Electrodialysis (ED) and Reverse Electrodialysis (RED) can act as a pre-desalting step before seawater enters the RO unit, thus leading to an important energy saving in RO. In this work, two coupled models are proposed for the RED-RO and ED-RO systems. Each process model was validated. Then a sensitivity analysis was performed to assess the effect of the integration on the overall process cost saving. The analysis was performed by changing ED or RED voltage …
A multi-scale tool for simulating electrodialysis with bipolar membranes systems
2022
In recent years, the global capacity of the desalination industry has increased to address freshwater scarcity, with reverse osmosis established as the leading technology. Brine disposal is a major issue due to the environmental impacts. However, novel brine management methods are oriented by (near) Zero Liquid Discharge strategies towards waste disposal minimization and resource recovery. In this context, ElectroDialysis with Bipolar Membranes (EDBM) can be utilised to valorise and, thus, repurpose the waste brine, thereby producing valuable chemicals, such as acid and base solutions, and recovering desalted water. However, the EDBM system must be carefully designed to meet the process req…
A comprehensive multi-scale model for bipolar membrane electrodialysis (BMED)
2022
Bipolar membrane electrodialysis (BMED) is a technology combining solute and solvent dissociation to produce chemicals. In the recent decades, it has been typically studied for the production of valuable acid and base solutions from salt streams. Although many works have been devoted to the experimental investigation of BMED, only a few efforts have focused on its mathematical modelling. In the present work, a comprehensive process model based on a multi-scale approach with distributed parameters is presented for the first time. Five models related to four different dimensional scales were fully integrated to form a comprehensive tool. The integrated model was developed by using the process…
A novel 2D model for the assessment of deformation-induced flow redistribution phenomena in electrodialysis units
2022
Valorization of surface-water RO brines via Assisted-Reverse Electrodialysis for minerals recovery: Performance analysis and scale-up perspectives
2022
Reverse osmosis (RO) processes have been recently identified as mostly capable of quantitative removal of salts and contaminants from saline and surface waters, though posing the problem of a concentrated brine to be disposed of and a produced permeate too low in minerals, thus requiring a sometimes expensive remineralization step. In the present paper, Assisted-Reverse Electrodialysis (A-RED) has been proposed for the remineralization of surface-water RO permeate by recovering minerals from its brine. A purposely developed and validated model has been adopted to carry out a parametric analysis for design and optimization of an industrial-scale plant. The techno-economic analysis underlined…
Mass transfer in channels in the presence of wall transpiration
Mass transfer to or from transpiring walls is studied. Examples from different fields of engineering, notably involving membrane processes, are illustrated, and analogies or differences with respect to heat transfer problems are discussed. With special reference to plane channel flow, suitable dimensionless parameters are introduced, and the dependence of the Sherwood number upon these parameters is computed by a number of approaches of different complexity, from two-dimensional CFD to simple algebraic correlations.
Ionic shortcut currents via manifolds in reverse electrodialysis stacks
2020
Abstract Reverse electrodialysis (RED) is a blue energy technology for clean and sustainable electricity harvesting from the mixing entropy of salinity gradients. Recently, many efforts have been devoted to improving the performance of RED units by developing new ion-exchange membranes and by reducing the detrimental phenomena affecting the process. Among these sources of “irreversibility”, the shortcut currents (or parasitic currents) flowing through alternative pathways may affect the process efficiency. Although such phenomena occur in several electrochemical processes (e.g. fuel cells, bipolar plate cells and vanadium redox flow batteries), they have received a poor attention in RED uni…
Pressure drop at low reynolds numbers in woven-spacer-filled channels for membrane processes: CFD prediction and experimental validation
2017
The energy consumption due to pumping power is a crucial issue in membrane processes. Spacers provide mechanical stability and promote mixing, yet increasing pressure drop. Woven spacers and their behaviour at low Reynolds numbers are less studied in the literature. Nevertheless, they are typical of some membrane technologies, as reverse electrodialysis (RED). RED is a promising technology for electric power generation by the chemical potential difference of two salt solutions within a stack equipped by selective ion-exchange membranes. The mechanical energy required for pumping the feed solutions, can dramatically reduce the net power output. In this work computational fluid dynamics (CFD)…
Numerical simulations supporting process models of chemical engineering: applications for membrane systems
2019
This work presents computational fluid dynamics simulations aimed at characterizing flow and mass/heat transport mechanisms in spacer-filled channels for membrane processes, with particular reference to (reverse) electrodyalisis and membrane distillation.
Modelling hybrid systems for seawater desalination: electromembrane processes (RED, ARED and ED) coupled with RO
2018
The need to reduce energy consumption in seawater reverse osmosis processes has pushed research towards the development of new hybrid systems in which, for example, other membrane processes can be used to pre-treat seawater. Electrodialysis and reverse electrodialysis can act as a dilution step before seawater enters the RO unit, thus leading to an important energy saving in RO. In this work, two coupled models are proposed for the RED-RO and ED-RO system. Each process model was validated before being used for a sensitivity analysis in which the effect of the integration on the cost saving in the overall process was assessed. The analysis was performed by changing (R)ED voltage and RO press…