Search results for "REVERSE ELECTRODIALYSIS"
showing 10 items of 77 documents
Performance of a RED system with ammonium hydrogen carbonate solutions
2016
The use of closed-loop salinity gradient power (SGP) technologies has been recently presented as a viable option to generate power using low-grade heat, by coupling a SGP unit with a thermally-driven regeneration process in a closed loop where artificial solutions can be adopted for the conversion of heat into power. Among these, the closed-loop reverse electrodialysis (RED) process presents a number of advantages such as the direct production of electricity, the extreme flexibility in operating conditions and the recently demonstrated large potentials for industrial scale-up. Ammonium hydrogen carbonate (NH4HCO3) is a salt suitable for such closed-loop RED process thanks to its particular …
REAPOWER – USE OF DESALINATION BRINE FOR POWER PRODUCTION THROUGH REVERSE ELECTRODIALYSIS
2015
Salinity gradient power (SGP) represents a viable renewable energy source associated with the mixing of two solutions of different salinities. Reverse electrodialysis (SGP-RE or RED) is a promising technology to exploit this energy source and directly generate electricity. However, although the principle of this technology is well known since several years, further R&D efforts are still necessary in order to explore the real potential of the SGP-RE process. With this regard, the aim of the REAPower project ( [GRAPHICS] ) is the development of an innovative system for power production by SGP-RE process, using sea (or brackish) water as a diluted solution and brine as a concentrate. The use o…
Investigation of Reverse ElectroDialysis Units by Multi-Physical Modelling
2016
Reverse electrodialysis (RED) is an electrochemical membrane process that converts the salinity gradient energy between two solutions into electric current, by using ion exchange membranes. A novel multi-physical approach for RED modelling is proposed. 2-D simulations of one cell pair with tertiary current distribution (Nernst–Plank equation and local electroneutrality) were performed. Moreover, the Donnan exclusion theory was implemented for simulating double layer phenomena. Transport phenomena and electrochemical behavior were well described. The influence of membrane/channel configuration, dilute concentration and feeds velocity on the process performance was assessed. For a dilute conc…
Flow and mass transfer in spacer-filled channels for reverse electrodialysis: a CFD parametrical study
2016
Abstract In reverse electrodialysis (RED) concentration polarization phenomena and pressure drop affect strongly the power output obtainable; therefore the channel geometry has a crucial impact on the system optimization. Both overlapped and woven spacers are commonly commercialised and adopted for RED experiments; the latter exhibit some potential advantages, such as better mixing and lower shadow effect, but they have been poorly investigated in the literature so far. In this work, computational fluid dynamics was used to predict fluid flow and mass transfer in spacer-filled channels for RED applications. A parametric analysis for different spacer geometries was carried out: woven (w) and…
Reverse electrodialysis with NH4HCO3-water systems for heat-to-power conversion
2017
Abstract A Reverse ElectroDialysis Heat Engine (REDHE) system operating with “thermolytic” ammonium hydrogen-carbonate (NH4HCO3) aqueous solutions as working fluids is studied. The engine is constituted by (i) a RED unit to produce electric power by mixing the solutions at different salinity and (ii) a thermally-driven regeneration unit including a stripping and an absorption column to restore the initial salinity gradient thus closing the cycle. In the present work only the RED unit and the stripping column are taken into account. In particular, a simplified integrated process model for the whole cycle was developed: it consists of (i) a lumped parameter model for the RED unit validated wi…
Bipolar membrane reverse electrodialysis for the sustainable recovery of energy from pH gradients of industrial wastewater: Performance prediction by…
2021
Abstract The theoretical energy density extractable from acidic and alkaline solutions is higher than 20 kWh m−3 of single solution when mixing 1 M concentrated streams. Therefore, acidic and alkaline industrial wastewater have a huge potential for the recovery of energy. To this purpose, bipolar membrane reverse electrodialysis (BMRED) is an interesting, yet poorly studied technology for the conversion of the mixing entropy of solutions at different pH into electricity. Although it shows promising performance, only few works have been presented in the literature so far, and no comprehensive models have been developed yet. This work presents a mathematical multi-scale model based on a semi-…
Pressure drop in woven-spacer-filled channels for reverse electrodialysis: CFD prediction and experimental validation
2015
Reverse electrodialysis (RED) is a promising technology for electric power generation by the chemical potential difference of two salt solutions within a stack equipped by selective ionexchange membranes (salinity gradient energy). Mechanical energy is required for pumping the feed solutions, which can reduce dramatically the net power output. In this work Computational Fluid Dynamics (CFD) simulations of spacer-filled channels for RED were carried out in parallel with an experimental campaign focused on the collection of data for model validation.
Reverse Electrodialysis: Applications to Different Case Studies
2018
Salinity gradient is a non-conventional renewable energy form which is widely available worldwide. Reverse Electrodialysis is a promising and innovative technology able to convert directly this chemical renewable energy into electricity. This paper presents a number of different scenarios where salinity gradients are naturally available or they result from industrial/urban activities. A sophisticated model accounting for all the main phenomena (including all the detrimental ones) occurring within a Reverse Electrodialysis unit has been purposely developed. The model is used to calculate how much electric energy can be harvested from the above-mentioned salinity gradients.
Experimental analysis of a continuously operated reverse electrodialysis unit fed with wastewaters
2017
Reverse Electrodialysis (RED) is one of the most promising technologies to convert salinity gradient chemical energy into electricity. RED units are traditionally operated with natural streams as river water and seawater thereby limiting the spread of the technology in sites far from coastal areas. Aim of the present work is that of exploring and expanding feed possibilities for RED systems by employing waste streams. Thus, an experimental study was performed by testing, for the first time, a Reverse Electrodialysis (RED) unit fed with a high salinity wastewater originated in a fish canning factory, and a low salinity wastewater from a sewage treatment plant. Uninterrupted, long duration ex…
Utilization of Reverse Electrodialysis Processes for the Abatement of Pollutants in Water
2014
The simultaneous generation of electric energy and th e treatment of waters contaminated by Cr(VI) was carried out by reverse electrodialysis processes using salinity gradients. The effect on the process of the nature of the cathode was investigated.