Effect of different aqueous solutions of pure salts and salt mixtures in reverse electrodialysis systems for closed-loop applications

Abstract

Reverse Electrodialysis in a closed-loop arrangement is a viable way to convert lowgrade heat into electric power. For the first time, the present work experimentally investigates the use of pure saltwater and equimolar two salts-water as feed solutions in a lab-scale RED unit in terms of OCV, stack resistance and corrected power density. The pure salts and the mixture salts to be employed were chosen via a computational analysis. Effect of feed solution velocity and concentration was also investigated. Results concerning the pure saltwater experiments suggest the use of NH4Cl in the concentration range investigated, while higher power density values are expected with the use of LiCl at larger concentrations. As regards the salt binary mixtures, in some cases the measured stack electrical resistance was found lower than both the two values measured for the corresponding pure salts, thus resulting into higher power density values for the mixtures. This surprising experimental evidence suggests that it is possible to increase the power produced by a conventional RED unit by adding an equivalent molar quantity of another suitable salt. Finally, among the mixtures tested, the NH4Cl-LiCl mixture appears as the most promising, thanks to the combination of the favorable properties of these two salts.

Exergy analysis of reverse electrodialysis

“…The mono-dimensional RED model was validated by comparison with experimental results reported in the literature [57].…”

Thermolytic reverse electrodialysis heat engine: model development, integration and performance analysis

“…Similarly, Giacalone et al [15] performed a theoretical analysis concerning the influence of different salt-water solutions, namely NaCl, LiCl, potassium chloride (KCl), potassium acetate (KCH3CO2), caesium acetate (CsCH3CO2) and sodium acetate (NaCH3CO2) water solutions, on the performance of SGP HEs consisting of single and multi-stage regeneration units. Micari et al [16] experimentally investigated the performance of a RED unit fed by aqueous solutions of binary salt mixtures.…”

Optimum Recovery of Saline Gradient Power Using Reversal Electrodialysis: Influence of the Stack Components

“…Two different multivalent commercial types of cationic (FKS-50 and FKS-30) and anionic (FAS-50 and FA-30) exchange membranes have been used and supplied by Fumasep® (Germany). The membrane A solution composed of 0.05 M K 3 Fe(CN) 6 , 0.05 M K 4 Fe(CN) 6, and 0.25 M NaCl in deionized water was employed as electrolyte [48]. Eq.…”