Numerical Simulation Of The Flow Characteristics Of The Stencil Plug Flow Electrochemical Reactor

Electrochemical catalytic oxidation is a green technology with good application in wastewatertreatment. The plug flow (tubular) reactor can be effectively improve the current efficiency and reduce processing costs. Plug Flow Reactor with Porous Reticulated Electrode (PRE-PFER) was promoted in which meshed plate electrodes with same size were employed and the fluid flows through the electrode surface perpendicularly, so that the drawbacks caused by nonuniform distribution of velocity and current density were dealed. Computational Fluid Dynamics (CFD), which can effectively simulate the reactor flow, is an efficient technology for research of reactor performance and optimizing the structure.In this paper, CFD tools were employed to simulate the flow pattern in PRE-PFER with Fluent software. The hydrodynamics like, velocity distribution, turbulence density distribution and pressure drop was analyzed. First, in order to optimize the reactor within the electrode structure and arrangement, the single-plate and multi-plate model were designed. The effects of the electrode hole size, the angle between the plate and the plate spacing on the characteristics of the flow field were studied, considering the velocity, turbulent density distribution and pressure drop parameters, The results showed:Dead volume within the reactor was significantly increased with the increase in the size of the electrode hole; The flow field can be more evenly distributed and turbulent intensity increased at the presence of mesh electrodes; When angle is90degrees and spacing≥20mm, no obvious recirculation zone and dead volume could be observed at the cost of maximum pressure drop.Secondly, CFD simulations of four different inlet designs (central、 lateral, perpendicular and tangential) were performed, the results indicated: The velocity distribution is more uniform with radial inlets; According to the velocity vector display and pressure drop, for tangential inlet, the back-mixing area accounted for27%and the pressure drop is minimal. While the other three inlets except the tangential inlet would produce a large area of the vortex in the inlet area with the back-mixing area accounting for about50%.Furthermore, the velocity distribution, turbulent intensity distribution and pressure drop in PRE-PFER and PFER were compared by CFD simulation. The flow field in PRE-PFER was less affected by the inlet region and reached earlier stable. The velocity distribution in the radial direction in PRE-PFER is more uniform and velocity peaks were obtained oppsite to the electrode holes, while the velocity distribution between electrodes in PFER was parabolic. Not only the fluid disturbances and turbulence intensity were enhanced as well as the effective electrode area at the presence of meshed electrodes which were perpendicular to the fluid flow, but also the transport energy consumption and pressure loss increased.