Experimental investigation on the performance of series control multi-stage reverse electrodialysis

Abstract Compared with the single-stage reverse electrodialysis, multi-stage reverse electrodialysis (MSRED) is superior for reverse electrodialysis heat engine (REDHE) because it can harvest more salinity gradient energy (SGE). Generally, there are two kinds of MSRED systems, i.e., individual control MSRED system and serial control MSRED system. And the series system is more practical compared with the other one. In this paper, influences of relevant parameters on the performance of the series system were investigated experimentally. The results demonstrated that on the premise of assuring efficiency of the MSRED harvesting SGE, to increase current density might have a negative impact on the performance of the MSRED due to the phenomenon of electrodialysis. Moreover, low feed solution velocity was more suitable for REDHE since less RED stacks were employed to reduce capital input and higher efficiencies of the MSRED and even the REDHE could be reached. Besides, to increase the initial molarity of high concentration feed solution was able to improve the performance of the MSRED except for its energy efficiency which decreased. Finally, to decrease the initial molarity of low concentration feed solution could improve all performance indicators of the MSRED.