Experimental studies of electrical and mass transfer processes in reverse electrodialysis

Abstract

OBJECT. Experimental studies on optimization of the output electrical and mass transfer characteristics of the reverse electrodialysis process.METHODS. System analysis techniques were used in this work and a mathematical model was developed to describe the movement of water streams and the concentrations of substances in them. The equipment involved, designed for experimental and industrial testing of the proposed technologies with technical characteristics of the developed apparatuses and installations, is described.RESULTS. RED (reverse electrodialysis) is a new membrane technology for renewable energy production using salinity gradients. The ultimate goal of RED is to achieve the highest possible value of power density, which depends on several parameters related to the intrinsic electrochemical characteristics of the membranes, stack configuration (number of cell pairs, channel length), hydrodynamics, nature of the working solutions (ionic composition, concentration), and others. The paper presents experimental studies on the influence and modeling of various parameters of the reverse electrodialysis operation on the output electrical characteristics of the system.CONCLUSIONS. It is shown that the system output power is significantly influenced by the composition of solutions in the near-electrode chambers, external load and internal resistance, concentrations of working solutions and time of the experiment. The maximum electrical efficiency was 56% (power density 0.34 W/m2) in semi-industrial electrodialysis reverse electrodialysis experiments using model NaCl solutions, K3Fe(CN)6/K4Fe(CN)6 and Chinese 0.6 mm thick IONSEP membranes.