Numerical investigation on a quaternary-driven rotary energy recovery device for desalination system: Performance evaluation and theoretical validation

Abstract

The rotary energy recovery device (RERD) is widely considered to be one of the most promising energy-saving equipment in seawater desalination system. The commonly used binary-driven pattern employs the direct driving mode of the working fluids which is hard to maintain the symmetrical and stable driving states in RERD. This paper proposes a quaternary-driven rotary energy recovery device (QD-RERD) and investigates the new quaternary distribution driven pattern in stabilizing the pressure exchanging and boosting the energy efficiency through the numerical and theoretical methods. The results indicate that the working fluids are deflected and accelerated in the quaternary-driven flow channels which achieves the maximum impacting velocity and driving moment of 12.38 m/s and 1.20 Nm at the flowrate of 30 m³/h. Both the pressure characteristics and fluid flowrate illustrate the symmetrical and quaternary distribution in the QD-RERD and the internal leakage can be controlled within 0.35 m³/h at 6.00 MPa. Furthermore, QD-RERD demonstrates the robust energy recovery efficiency which remains above 96 % in the wide flowrate range between 10 m³/h and 50 m³/h and the peak efficiency arrives at 98.10 %. This research represents further step towards developing stable and efficient RERD for membrane desalination.