Computational Fluid Dynamics Simulation of Brine–Seawater Mixing in a Rotary Energy Recovery Device

Abstract

The effects of operational conditions on the mixing behavior of a rotary energy recovery device have been systematically investigated through the combined methods of computational fluid dynamics and validating experiments in this paper. The sliding mesh technique and species transport equations were applied in the simulation process. An innovative parameter of inflow length was defined to express the moving distance of a mixing section in rotor ducts. A theoretical formula between the inflow length and operational conditions was first established on the basis of the mass balance and computational fluid dynamics analysis. Simulation results revealed that the mixing has a polynomial relation with dimensionless inflow length, which was in good agreement with the experimental results. The obtained formulas between mixing and dimensionless flow length provide a simple way to calculate and predict the mixing behavior of the device, which will be beneficial to design and operate the rotary energy recovery device in a lower mixing level.

Reverse osmosis (RO) membrane desalination driven by wind and solar photovoltaic (PV) energy: State of the art and challenges for large-scale implementation

“…This is especially true for the pressure exchanger (PX®), as there is no physical barrier between the brine and feed streams. A study was performed by Xu et al [126] to analyse the effect of rotor speed, brine and feed flow velocities on the mixing rate for a rotary pressure exchanger. The analysis was performed using a computational fluid dynamics simulation, presented in Fig.…”

“…16. Two-dimensional salinity contour of the central cylindrical surface of the ERD (reproduced with permission from [126]).…”

Integration of CFD and RTD analysis in flow pattern and mixing behavior of rotary pressure exchanger with extended angle

“…Comparison between the numerical results and experimental data in Ref. [11]. obvious at about 0.6 s. Thereafter, the overall V m of ±30˚case appears to remain at the lowest level, whereas the 0˚case seems to keep a highest V m .…”

“…A numerical validation has been made using a 4-port RPE with 0 extended angles presented in the literature [11]. As the parameters are not all provided, the model parameter settings follow approximately the experimental conditions.…”

“…Also, the mixing intensified with an increase in flow rate and a decrease in rotation speed. Xu et al [11] also carried out a simulation of mixing in RPE with the turbulence model. A second-order polynomial relationship between the mixing rate and the dimensionless inflow length was obtained, and was validated by an experiment.…”