Effect of design and operating parameters on power generation in reverse electrodialysis (RED): experimental analysis and modeling

This paper investigated the effect of key parameters such as the number of cell pairs, flow rate, temperature, and salt concentration on the power output characteristics of a reverse electrodialysis (RED) system. Experiments were carried out to measure the open-circuit voltage (OCV) and maximum power (P-max) in a bench-scale RED system. The Nernst-Plank flux equations, together with the Donnan equilibrium relations and the electrical neutrality condition, were used to interpret experiments values. Results showed that the OCV and P-max increased with an increase in the number of cell pairs and temperature. Using 20 cell pairs, the OCV and P-max were 2.75 V and 1.4 W/m(2), respectively. The flow rate affected the OCV and P-max but also led to an increase in the pressure drop in the RED stack. Thus, the flow rate was suggested to be 60 mL/min with the use of 20 cell pairs in our system. The OCV and P-max were higher at a higher salinity difference between the high salinity and low salinity solutions. Nevertheless, the OCV and P-max were smaller at a higher salt concentration even if the salinity gradient between the high and low salinity solutions were the same.