Numerical study of structure parameters on energy transfer and flow characteristics of integrated energy recovery and pressure boost device

Energy recovery device (ERD) is a critical power component in seawater reverse osmosis (SWRO) desalination system. In this study, the energy transfer and flow characteristics for an innovative integrated energy recovery and pressure boost device (IERPBD) are investigated. The IERPBD which consists of a rotary pressure exchanger (RPE) and an axial piston type booster pump (APBP) is introduced in Section 2. To optimize both the structure parameters and working conditions of IERPBD, a series of three-dimensional (3D) CFD simulations are carried out. The CFD simulations for the RPE with port plate silencing grooves are conducted with a set of operating conditions through orthogonal designed theory. It should be noted that the leakage through the lubricating gaps of valve-port plate, fluid compressibility effect and cavitation damage are considered in the simulation. And partial numerical results are validated by comparison with the results from other research groups. The mixing process, pressure distribution, components distribution, leakage flow characteristics and related characteristic parameters of RPE are presented in Section 3. And then the optimal parameters of RPE with a duct diameter of 10 mm, duct length of 70 mm, 12 ducts with fresh seawater flow of 10.8 L/min were used to design the IERPBD. The energy transfer and flow characteristics of IERPBD were also presented with different gap heights of the valve-port plate interface. The simulation results turned out that when the lubricating gap height of valve-port plate changes from 5 mu m to 20 mu m, the flow ripple rate of RPE could increase from 6.15% to 36.13%, whereas the energy recovery efficiency of RPE could decrease from 97.2% to 49.8%. Therefore, a well-designed lubricating gap of valve-port plate could improve both energy transfer and flow characteristics of IERPBD. This research will lay the foundation for the further development of high efficiency and low fluid noise IERPBD.