Research On Hydrodynamic Characteristic Of Rotary Pressure Exchanger

At present,reverse osmosis desalination technology has become the mainstream in the seawater desalination field.Rotary energy recovery device is the key equipment in reverse osmosis desalination system.The performance of the rotary energy recovery device greatly determines the cost and running stability of the desalination system.Based on positive displacement principle,rotary energy recovery device make high-pressure salt water and low-pressure fresh water meet directly to exchange pressure energy in the rotor internal flow channel.In order to optimize the structure of the device to achieve large-scale engineering applications,this paper is based on three aspects,fluid theory,numerical simulation and on-site experimental study,research the hydrodynamic characteristics of rotary energy recovery device.Namely,the problem of energy loss.According to the cause of the energy loss during the operation of the rotary energy recovery device,the paper analyzes the influence factors on energy loss,including the rotation resistance torque,the pressure loss and the flow loss,and determines the influence of the three factors on the energy loss.Specific process includes the following two parts:1)In this paper,the rotation resistance moment of the rotary energy recovery device was studied in terms of theoretical analysis and simulation experiment.Firstly,the mathematic models of rotational resistance moment under laminar flow and turbulent flow were derived from Newtonian internal friction theory and boundary layer theory.Secondly,the influence of rotational speed,end clearance and annular clearance on the rotational resistance moment was calculated and analyzed by simulation experiment.Finally,the rotational resistance moments obtained by theoretical and simulation methods were compared under all kinds of working conditions,aiming at verifying the accuracy and applicable range of two mathematical models on rotational resistance moment in rotary energy recovery device.2)The pressure loss and leakage of the rotary energy recovery device were studied.Experiments were carried out by continuously adjusting the operating conditions of the device.Mathematical analysis was performed on the basis of the experimental data to obtain a predictable empirical model.Finally,the test data of field test operation proved the applicability of the prediction model,and the accuracy of the model was verified by the simulation experiment.