PERFORMANCE ANALYSIS FOR PRESSURE RETARDED OSMOSIS: EXPERIMENTATION WITH HIGH PRESSURE DIFFERENCE AND VARYING FLOW RATE, CONSIDERING EXPOSED MEMBRANE AREA

摘要

Pressure retarded osmosis (PRO) is a process for renewable energy conversion that makes use of a salinity gradient between two bodies of water. A semipermeable membrane separates two solutions: the draw solution, with higher salinity, and the feed solution, with lower salinity. In this study, three system design choices for bench-scale PRO systems were investigated: mesh spacer opening area, hydraulic pressure difference, and relative flow rates. Mesh spacers provide mechanical support to the membrane, but can reduce the water flux. Moreover, the water flux behavior at high hydraulic pressure difference is shown to be nonlinear, departing from the theoretically predicted water flux, which is based on a linear model. The ratio of feed solution flow rate to draw solution flow rate also determines PRO performance. Experimental data from a bench-scale system is used to present design-relevant information for optimizing PRO systems toward higher power densities.