Investigation of the Mixing Rate and Channel Volume Efficiency of a Self-Driven Rotary Energy Recovery Device in the Reverse Osmosis System

The mixing problem of the rotary energy recovery device (RERD) adversely affects the reverse osmosis desalination process. The influence of working conditions on the inflow length and mixing rate in a self-driven hydraulic RERD was studied by analyzing the mass transfer mechanism in the rotor channels via computational fluid dynamics (CFD) simulation. The feasibility and reliability of the simulation were experimentally verified. Channel volume efficiency was defined to analyze the inflow status of channels and the mixing behavior. The simulation data exhibited a linear relationship between the inflow length and the ratio of the flow rate and rotary speed, and the mixing rate represented the quadratic function of the channel volume efficiency. The results indicated that the proposed mathematical model of the inflow length and mixing rate is valid. This model in conjunction with the variation relationship between the rotary speed and the flow rate of the self-driven RERD can help considerably improve the mixing problem of the RERD in the design stage, thus reducing the testing cost.