Nanofluidic reverse electrodialysis with strengthened electric double layer using industrial low-grade waste heat

Abstract Nanofluidic reverse electrodialysis is an effective technique to harvest clean salinity-gradient energy. However, the osmotic power density of nanofluidic reverse electrodialysis is still limited. This work designs an industrial low-grade waste heat–enhanced nanofluidic reverse electrodialysis using theoretical and experimental analyses. The osmotic output power and energy conversion efficiency of nanofluidic reverse electrodialysis are theoretically observed to be enhanced with the pH value and the temperature of ionic aqueous solution. When the industrial low-grade waste heat at a temperature of 50 °C is utilized to increase the ionic aqueous solution temperature in nanofluidic reverse electrodialysis, its experimental osmotic power density is increased from 3.651 W m −2 to 7.130 W m −2 by 95.29%. In addition, when the pH value of the ionic aqueous solution is transferred from acidic condition at 3 to alkaline condition at 11, the experimental osmotic power density of nanofluidic reverse electrodialysis is enhanced from 6.431 W m −2 to 7.666 W m −2 by 19.20%. In addition, a trend-based parametric analysis of nanofluidic reverse electrodialysis is constructed, and its derivative of the experimental relative osmotic power density with respect to the pH value and salinity-gradient ratio of the ionic aqueous solution can be increased via the utilization of industrial low-grade waste heat, further demonstrating the effectiveness of thermally ameliorating the performance of nanofluidic reverse electrodialysis.