Flow Characteristics And Mass Transfer Properties In A Plug Flow Electrochemical Reactor With Mesh Plate Electrode

The plug flow electrochemical reactor(PFER) is a novel electrochemical treatment technology which can improve the current efficiency and reduce the processing costs. The plug flow electrochemical reactor with mesh plate electrode(MPE-PFER) solved the weakness of traditional plug flow electrochemical reactor and improved the mass transport of pollutant, such as uneven current density distribution, disunion fluid velocity distribution and non-uniform turbulence intensity, due to the same electrodes size and the fluid flows through the electrode surface perpendicularly. Computational Fluid Dynamics(CFD) can effectively simulate the flow field inside the reactor, Particle Image Velocimetry(PIV) can directly show the flow field in a reactor, the combination of these two techniques can provide a reliable basis for the optimization of reactor performance and structure.In this paper, the combination of Computational Fluid Dynamics(CFD) and Particle Image Velocimetry(PIV) were used to simulate and test the flow field and pressure drop with different inlet(axial, radial and tangent). The results show that the simulation results and test results are basically the same. As a transitional area of fluid flow, the inlet region impact by inlet way greatly. Compared to the other ways of inlet, for tangential inlet, velocity distribution is uniform, no large velocity gradients, no reflux dead zone, the flow rate of the electrode surface is also more suitable, and the pressure drop is least.Secondly, by DPM model, the effects of different bubble diameter and mass flow rate to flow field inside the reactor were analyzed. The simulation results show that the impact of bubbles on the continuous phase flow field increases as the bubble diameter increases. When the bubble diameter is small, it can enhance the turbulence and uniform the flow field distribution, the diameter is larger, the turbulence intensity distribution of reactor upper and lower part is uneven, the upper part turbulent intensively, while the lower part appear the low turbulent region. When the bubble mass flow rate is less, the flow of continuous phase plays a dominant role, the impact of bubbles on the turbulent intensity is not obvious, with the increase of the bubble, bubble effect more obvious, the flow field distribution becomes more uniform.Finally, the flow field distribution and mass transfer performance of both MPE-PFER and PFER were comparative analysed. From the view of flow field, the effect by inlet region of MPE-PFER flow field is small, the flow field can be stabilized earlier, velocity distribution in the radial direction and velocity peaks were obtained to the electrode holds, the flow field distribution between the electrodes in PFER was parabolic, the flow field influenced by the inlet area is small. By analyzing the mass transfer semi-empirical formula for both reactors, we found that the mass transfer performance of MPE-PFER is higher than PFER significantly due to the presence of mesh plate electrode, the mass transfer correlation of MPE-PFER is 23.061.4 ?u times as much as PFER, under the same flow change, the increased mass transfer coefficient of MPE-PFER is twice as large as PFER.