Two parameters might affect the thermodynamic performance of reverse osmosis desalination plants, those are the recovery ratio and feed water salinity. Exergy analysis is performed to determine the effect of those parameters on the thermodynamic performance of a reverse osmosis desalination unit. Irreversibility, effectiveness and specific energy consumption are obtained at different recovery ratios and salinities.
The results of the developed thermodynamic model of the present work are validated against the obtained results from the literature, where the effectiveness and the contributions of the membrane, high-pressure valves, friction, and the other components to total irreversibility are compared.
The results show that the contribution of the high valve and membranes to total irreversibility depends strongly on the recovery ratio. The contribution of other components to total irreversibility is a minor one. The effect of source salinity on the percentage of the recovered exergy is not substantial, for instance, it is found that 7.96% and 6.88% of the destroyed exergy can be recovered, at salinities of 1000 ppm and 5000 ppm, repectively.
The analysis shows that using the Pelton wheel to recover part of the destroyed exergy is only reasonable at low and moderate recovery ratio. For instance, the input power decreases by 7% and 60% for recovery ratio of 0.9 and 0.1, respectively.