Investigations on the energy conversion and dissipation in hydraulic-driven rotary energy recovery device from a designer's perspective: Simulation and validation

Hydraulic-driven rotary energy recovery device (HD-RERD) has attracted considerable attention in membrane desalination for energy conservation. Plentiful studies have typically aimed at the operating performance in specific working conditions which fail to evaluate the energy flows holistically. This paper focuses on the revelation of energy conversion and dissipation in HD-RERD by exploring the operating performances under multiple conditions, which pays close attention to the hydraulic driven, internal leakage, salinity mixing and energy efficiency. The results indicate that the rotor speed follows the cubic function and varies from 0 rpm to 742 rpm within the flowrate range of 70 m3/h. A linear function appears in internal leakage within the pressure scope of 7.00 MPa. The salinity mixing leads to the extra energy consumption in HD-RERD which is about 10.71 kJ/(m3/h) at the flowrate of 70 m3/h. In addition, the ratios of dissipation energy to total energy conversion are about 0.46 % 1.53 % and 1.46 % for hydraulic driven, internal leakage and pressure losses respectively at the pressure and flowrate of 7.00 MPa and 70 m3/h. This study provides an in-depth understanding of the energy conversion in HD-RERD for researchers and engineers.