Effect of rotor area covered by end cover on flow characteristics and performance of seawater desalination energy recovery device

The multi-phase flow mixing numerical model was used to simulate the influence of the end cover on the rotor area on the flow characteristics and performance of the seawater desalination energy recovery device under three structural designs. The pressure energy recovery efficiency, flow field pressure distribution, and NaCl concentration distribution, high pressure inlet, and outlet differential pressure characteristics, and pressure pulsation characteristics of seawater desalination energy recovery device were numerically simulated under different end caps covering rotor area and speed. The results show that the area covered by the end face of the rotor plays an important role in the recovery efficiency of the pressure energy. The effect of rotational speed on the recovery efficiency of the pressure energy is not uniquely determined, but there is a rotational speed in which the rotor speed is not suitable for the energy recovery efficiency. The higher the pressure difference between the high pressure inlet and outlet of the energy recovery device, the lower the pressure energy recovery efficiency. Considering the fluid-forming hydrostatic mechanical seal and system stability, the design method of the structure a (single layer, area = 3,534.29 mm2) end cover covering the rotor area is the optimal design among the three structures.