Thermodynamic performance assessment of a community-scale brackish water reverse osmosis plant using exergy analysis

Abstract

Abstract This study investigated the thermodynamic performance of a community-scale membrane-based brackish water reverse osmosis (BWRO) plant at various operating pressures from 13.79 to 27.58 bar and feed salinity levels from 2,000 to 20,000 mg/L. We aimed to identify the components responsible for the exergy losses and to suggest improvements. The results showed that the exergetic efficiency of some individual components had a significant impact on the performance of the desalination plant, where the high-pressure (HP) pump assembly and pressure control valve were identified as the major contributors to exergy losses (57.83–70.59 and 15.75–27.62%, respectively). The inefficiency of the feed pump assembly contributed to 11–12% of the total destruction of exergy under different operating conditions. The analysis further revealed that the exergetic efficiency of the plant was maximum (0.51%) at the feed salinity of 10,000 mg/L and operating pressure of 27.58 bar. It was minimum (0.01%) for the highest salinity (20,000 mg/L) and the lowest operating pressure (13.79 bar), due to the low requirement of work of separation and higher fixed losses. The exergetic efficiency was also correlated to the energetic performance of the BWRO plant at different operating conditions.