Search results for " Electrodialysis"
showing 10 items of 114 documents
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…
The acid–base flow battery : Sustainable energy storage via reversible water dissociation with bipolar membranes
2020
The increasing share of renewables in electric grids nowadays causes a growing daily and seasonal mismatch between electricity generation and demand. In this regard, novel energy storage systems need to be developed, to allow large-scale storage of the excess electricity during low-demand time, and its distribution during peak demand time. Acid–base flow battery (ABFB) is a novel and environmentally friendly technology based on the reversible water dissociation by bipolar membranes, and it stores electricity in the form of chemical energy in acid and base solutions. The technology has already been demonstrated at the laboratory scale, and the experimental testing of the first 1 kW pilot pla…
Performance of the first reverse electrodialysis pilot plant for power production from saline waters and concentrated brines
2016
Abstract This work reports experimental data collected for the first time on a full-scale RED pilot plant operated with natural streams in a real environment. The plant – located in the South of Italy – represents the final accomplishment of the REAPower project ( www.reapower.eu ). A RED unit equipped with almost 50 m2 of IEMs (125 cell pairs, 44x44 cm2) was tested, using both artificial and natural feed solutions, these latter corresponding to brackish water (≈0.03 M NaClequivalent) and saturated brine (4–5 M NaClequivalent). A power output up to around 40 W (i.e. 1.6 W/m2 of cell pair) was reached using natural solutions, while an increase of 60% was observed when testing the system with…
Towards 1 kW power production in a reverse electrodialysis pilot plant with saline waters and concentrated brines
2017
Abstract Reverse electrodialysis (RED) is a promising technology to extract energy from salinity gradients, especially in the areas where concentrated brine and saline waters are available as feed streams. A first pilot-scale plant was recently built in Trapani (Italy), and tested with real brackish water and brine from saltworks. The present work focuses on the scale-up of the pilot plant, reaching more than 400 m 2 of total membrane area installed and representing the largest operating RED plant so far reported in the literature. With a nominal power capacity of 1 kW, the pilot plant reached almost 700 W of power capacity using artificial brine and brackish water, while a 50% decrease in …
Effect of membrane profiles on the limiting current density in electrodialysis
2019
In the present work, we experimenrtally investigated the effect of different membrane profiles on the LCD, testing also different operating conditions.
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)…
Potential applications of Salinity Gradient Power-Heat Engines for recovering low-temperature waste heat in cogeneration plants
2021
Abstract Salinity Gradient Power-Heat Engine is an innovative technology able to convert very low-temperature heat into electricity. Energy and economic benefits could be achieved by integrating this technology into cogeneration plants, where the exploitation of waste heat available during the operation could increase the revenues arising from “High-Efficiency” labels. For the first time, this paper proposes two potential applications in this field, and three illustrative case studies are purposely investigated. In the first case study, a salinity gradient-heat engine converts the waste heat available from a cogeneration plant serving an industrial process. In the second case study, a salin…
CFD modelling of profiled-membrane channels for reverse electrodialysis
2014
Abstract: Reverse electrodialysis (RE) is a promising technology for electric power generation from controlled mixing of two differently concentrated salt solutions, where ion-exchange membranes are adopted for the generation of ionic currents within the system. Channel geometry strongly influences fluid flow and thus crucial phenomena such as pressure drop and concentration polarization. Profiled membranes are an alternative to the more commonly adopted net spacers and offer a number of advantages: avoiding the use of non-conductive and relatively expensive materials, reducing hydraulic losses and increasing the active membrane area. In this work, Computational Fluid Dynamic simulations we…