Research on Rotational Driving Torque of Rotary Energy Recovery Device in Seawater Reverse Osmosis System

As one of the three key equipments in membrane desalination system, rotary energy recovery device can effectively reduce energy consumption during seawater desalination. As the only rotating part of the device, the rotor is driven by the operating flows and research of the rotational driving torque is always the most important hydrodynamic problem of the device. In this paper, the formation principle of driving torque was investigated and the driving torque was analyzed and calculated by both theoretical way and CFD way. Thus, a mathematical formula for calculating the driving torque was obtained. The simulative driving torque was in good agreement with the theoretical driving torque which indicates the formula and the simulation model were reasonable. The result showed that the driving torque decreases linearly with the increase of the rotor speed and increases with the square of the flow rate. This research provides a simple way to predict the driving torque of the device, which will be helpful to the design of new high-performance energy recovery devices and other similar devices.