Search results for "Electrodialysi"

Modelling of Electrodialysis units by a multi-scale process simulator

Drinking water production by desalination is an interesting alternative to face water scarcity issues. Electrodialysis (ED) is an electro-membrane process that is actually gaining attention as a competitive alternative for seawater and brackish water desalination due to recent developments in manufacturing of high performance ion exchange membranes (IEMs). In this context, a suitable process simulator can be a very effective tool in order to drive the design of optimized ED systems. In this work a novel mathematical model of ED units was developed by a hierarchical simulation strategy of separation of scales, in order to address the full simulation problem. The model was implemented in PSE …

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…

A 2-D model of electrodialysis stacks including the effects of membrane deformation

2021

Abstract Membrane-based processes have gained a relevant role in many engineering applications. Much effort has been devoted to thoroughly understand the fundamental phenomena behind them. However, membrane deformation has been taken into consideration only recently, although much evidence has shown its impacts in many applications. This work presents a novel 2-D, multi-scale, semi-empirical process model able to predict the behavior and the performance of Electrodialysis (ED) systems in cross-flow configurations in the presence and absence of local membrane deformations. The model exploits the results and the simulation approaches of previous fluid-structure investigations performed by the…

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)…

Two-dimensional model of cross-flow electrodialysis units for the assessment of membrane deformation effects on the process performance

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…