Modification of hydraulic turbocharger's rotor for maintaining constant water production and energy recovery rate in reverse osmosis systems

One of the challenges in seawater desalination using reverse osmosis is the fluctuation in water production due to changes in process conditions. In this study, to address this issue, the rotor of a hydraulic turbocharger, employed as an energy recovery device in desalination plants, was redesigned. First, the flow field within an operational turbocharger was analyzed and validated using computational fluid dynamics (CFD) simulations and experimental data. Subsequently, considering two scenarios of process variation, two new rotors were designed, manufactured, and tested for the existing turbocharger based on similarity laws in turbomachinery and flow field simulations. The results indicate that, despite variations in membrane inlet pressure, the turbocharger equipped with the new rotors not only maintained a constant water production rate but also ensured a stable energy recovery rate. Moreover, under high-pressure conditions, the overall efficiency improved by more than 4%, and the energy recovery rate increased by approximately 2% compared to the original turbocharger. These findings demonstrate that this method can be effectively utilized in situations where membrane pressures deviate significantly from the initial design pressure.