Numerical Simulation Research On Energy Recovery Process Of Rotary Pressure Exchanger

Rotary Pressure Exchanger (RPE) is a typical technique which withdraws pressure energy through direct contact between high and low pressure fluids. Due to its simple design, lower maintenance fees, stability and high recovery efficiency, RPE has been widely used for energy recovery in process industries such as Seawater Reverse Osmosis (SWRO).As RPE devices use direct contact of fluids to realize pressure energy recovery, this brings about two of its core problems-effective control of fluid mixing in order to guarantee the purity of the pressurized fluid as well as achieve face seal so that the efficiency of energy transportation can be ensured. Based on those two points, this report will use numerical simulation to research and analyze fluid mixing inside of rotor duct and face seal between rotor and stator.The main achievements of this study are1)3D model is set up in order to simulate the mixing process in RPE’s duct. This model successfully describes the fluid mass transportation at transient contact inside the duct. During the above process, a stable plume piston is formed. The fluid piston does reciprocating motion inside the duct, which assures effective control of mixing rate because the piston has the adaptive ability for flow fluctuation.2) Increasing rotor diameter is the main method to meet single RPE handling capacity requirement. This paper explores the impact of radial mixing in the large-diameter ducts on the whole mass transportation and the reasons behind it. Additionally, research of large-diameter rotor design theory is carried out aiming to control radical mixing which proposes an optimum design method of rotors with larger single handling capacity.3) To solve the face seal problem, this report first analyzes the specialty of such structure in RPE, then a corresponding3D model is set up. The model is proven to be rational and valid, comparing the experiment results with theoretical analysis. Studies indicate that change of clearance is vital for sealing performance of pure flat.4) In order to disengage from dependence on Ultra-precision Machining, this paper suggests reconstructing face seal, so that the opening force caused by hydrodynamic effect can be used to produce micron thickness of liquid film. Common groove model is set up in the paper.