Search results for "Reversed electrodialysis"
showing 10 items of 53 documents
Novel solutions for closed-loop Reverse Electrodialysis: thermodynamic characterisation and perspective analysis
2019
Abstract Closed-loop Reverse Electrodialysis is a novel technology to directly convert low-grade heat into electricity. It consists of a reverse electrodialysis (RED) unit where electricity is produced exploiting the salinity gradient between two salt-water solutions, coupled with a regeneration unit where waste-heat is used to treat the solutions exiting from the RED unit and restore their initial composition. One of the most important advantages of closed-loop systems compared to the open systems is the possibility to select ad-hoc salt solutions to achieve high efficiencies. Therefore, the properties of the salt solutions are essential to assess the performance of the energy generation a…
On the modelling of an Acid/Base Flow Battery: An innovative electrical energy storage device based on pH and salinity gradients
2020
Abstract Electrical energy storage can enhance the efficiency in the use of fluctuating renewable sources, e.g. solar and wind energy. The Acid/Base Flow Battery is an innovative and sustainable process to store electrical energy in the form of pH and salinity gradients via electrodialytic reversible techniques. Two electromembrane processes are involved: Bipolar Membrane Electrodialysis during the charge phase and its opposite, Bipolar Membrane Reverse Electrodialysis, during the discharge phase. For the first time, the present work aims at predicting the performance of this energy storage device via the development of a dynamic mathematical model based on a multi-scale approach with distr…
Modelling the Reverse ElectroDialysis process with seawater and concentrated brines
2012
Technologies for the exploitation of renewable energies have been dramatically increasing in number, complexity and type of source adopted. Among the others, the use of saline gradient power is one of the latest emerging possibilities, related to the use of the osmotic/chemical potential energy of concentrated saline solutions. Nowadays, the fate of this renewable energy source is intrinsically linked to the development of the pressure retarded osmosis and reverse electrodialysis technologies. In the latter, the different concentrations of two saline solutions is used as a driving force for the direct production of electricity within a stack very similar to the conventional electrodialysis …
Investigation of electrode material – Redox couple systems for reverse electrodialysis processes. Part I: Iron redox couples
2012
Abstract The performances of electrodialysis (ED) and reverse electrodialysis (RED) processes depend on several factors, including the nature of the electrode material and of the redox couple adopted to make possible the conversion between electric power and chemical potential. In this paper, the possible utilization of iron-based redox couples (FeCl3/FeCl2, hexacyanoferrate(III)/hexacyanoferrate(II) and Fe(III)-EDTA/Fe(II)-EDTA) on graphite and DSA electrodes for RED processes was studied by a detailed experimental investigation. The hexacyanoferrate(III)/hexacyanoferrate(II) system was stable for long time (more than 12 days) in the absence of light and oxygen at high redox couple concent…
Reverse electrodialysis heat engine for sustainable power production
2017
Abstract Reverse Electrodialysis Heat Engine (REDHE) is a promising technology to convert waste heat at temperatures lower than 100 °C into electric power. In the present work an overview of the possible regeneration methods is presented and the technological challenges for the development of the RED Heat Engine (REDHE) are identified. The potential of this power production cycle was investigated through a simplified mathematical model. In the first part of the work, several salts were singularly modelled as possible solutes in aqueous solutions feeding the RED unit and the corresponding optimal conditions were recognized via an optimization study. In the second part, three different RED He…
Cathodic reduction of hexavalent chromium coupled with electricity generation achieved by reverse-electrodialysis processes using salinity gradients
2014
Abstract A new approach for the simultaneous generation of electric energy and the treatment of waters contaminated by recalcitrant pollutants using salinity gradients was proposed. Reverse electrodialysis allows for the generation of electric energy from salinity gradients. Indeed, the utilization of different salt concentrations gives a potential difference between the electrodes which allows the generation of electric energy by using suitable electrolytes and an external circuit. The simultaneous generation of electric energy and the treatment of waters contaminated by Cr(VI) was successfully achieved for the first time by reverse electrodialysis processes using salinity gradients and pr…
Energy generation and abatement of Acid Orange 7 in reverse electrodialysis cells using salinity gradients
2015
Abstract The simultaneous generation of electric energy and the treatment of wastewaters contaminated by an organic pollutant resistant to conventional biological processes, Acid Orange 7 (AO7), was achieved for the first time using proper redox processes by reverse electrodialysis using salinity gradients. The stack was fed with two aqueous solutions with different concentrations of NaCl and a synthetic wastewater contaminated by AO7. Various electrochemical approaches including electro-Fenton, electrogeneration of active chlorine (IOAC) and coupled process were performed in a stack equipped with 40–60 cell pairs and studied by focused electrolyses. The effect of the number of cell pairs a…
Assisted reverse electrodialysis for CO2 electrochemical conversion and treatment of wastewater: A new approach towards more eco-friendly processes u…
2020
Abstract In this paper, the utilization of assisted reverse electrodialysis (A-RED), recently used for pre-desalination, is proposed as a general method to reduce the energy requirements of electrolysis processes and evaluated for two model processes: (i) the cathodic conversion of carbon dioxide to formic acid; (ii) the anodic treatment of water contaminated by organics. In A-RED, two solutions with different salt content and an external potential difference, applied in the direction of the natural salinity gradient, are both used to drive redox processes. It was shown, for the first time, that the cathodic conversion of CO2 to formic acid can be performed by both reverse electrodialysis (…
Evaluation of the Economic and Environmental Performance of Low-Temperature Heat to Power Conversion using a Reverse Electrodialysis – Multi-Effect D…
2019
In the examined heat engine, reverse electrodialysis (RED) is used to generate electricity from the salinity difference between two artificial solutions. The salinity gradient is restored through a multi-effect distillation system (MED) powered by low-temperature waste heat at 100 °C. The current work presents the first comprehensive economic and environmental analysis of this advanced concept, when varying the number of MED effects, the system sizing, the salt of the solutions, and other key parameters. The levelized cost of electricity (LCOE) has been calculated, showing that competitive solutions can be reached only when the system is at least medium to large scale. The lowest LCOE, at a…
CFD simulation of channels for direct and reverse electrodialysis
2012
Flows within very thin channels, typically filled with spacers, can be often encountered in many processes such as electrodialysis (ED) and reverse electrodialysis (RED). Although the ED and the RED processes have been studied for a long time, the optimization of the fluid dynamics within the channels is still an open problem. In the present work, realized within the EU-FP7 funded REAPower project, computational fluid dynamics simulations were carried out in order to predict the fluid flow field inside a single ED/RED channel. Some different configurations were tested which includes: an empty channel, a channel provided with a spacer, and a channel filled with a purposely manufactured fiber…