| The photochemical reactions have been widely applied in chemical industries such as material preparation,organic synthesis,and pollution treatment due to the advantages such as mild reaction conditions,controllable selectivity.The incident light intensity decreases rapidly with increasing penetration distance in photochemical reactions.The spinning disk reactor（SDR）produces a thin liquid film thickness by centrifugal force,which creates shorter light penetration distance in photochemical reactions.Therefore,the SDR has potential advantages and broad application prospects in photo-induced reaction processes.Conventional SDR still exists the phenomenon of inhomogeneous distribution of photochemical reaction rate in liquid film.The liquid near the disk surface receives lower incident light energy,resulting in a slower reaction rate.The liquid near the surface of liquid film receives higher incident light energy and has a faster reaction rate.In this thesis,the disk structure of the SDR is designed to enhance the disturbance level of liquid at different radial positions of the disk by arranging spoilers,and promote the exchange and renewal of the reactant with different light penetration distances to achieve the process intensification of the photochemical reactions.This thesis mainly focused on the flow behavior and photochemical application performance on the SDR with spoilers.The main results of the thesis are listed as follows:1.The liquid film flow behavior on the disk of the spinning disk reactor was evaluated by the three-dimensional volume of fluid（VOF）computational fluid dynamic simulations.The effect of spoiler structure,rotational speed,liquid flow rate and viscosity on the hydrodynamic characteristics of the SDR with spoilers was systematically investigated.The simulation results indicated that the existence of spoilers on the disk surface increased the turbulent kinetic energy and the liquid renewal in the vertical liquid film radial flow direction.The liquid film thickness increased with the presence of the spoilers at the same time.The spinning disk reactor with elliptic-cylindrical（ES）spoilers has greater liquid film disturbance than the spinning disk reactor with cylindrical spoilers（CS）.Compared with the SDR with smooth disk,the SDR has the superior average turbulent kinetic,which was increased from 2.1×10-4m2/s2 to 3.8×10-3m2/s2.2.A comparative study of the residence time distribution characteristics of the SDRs with different disk configuration was carried out.The simulation results showed that the presence of spoilers on the disk led to an increase in mean residence time and variance.The mean residence time and dimensionless variance of the SDRs were in ranges of 0.29-1.43 s and 0.02-0.15,respectively.The non-ideal flow behavior of the spinning disk reactor was evaluated by the tanks-in-series model and axial dispersion model.The spinning disk reactor revealed a deviation trend from the ideal plug flow,which strengthened the macromixing performance of the SDR.According to the dimensionless analysis,the empirical correlation of the parameters in the non-ideal flow model was established.3.The photon absorption rate was experimentally measured by the potassium ferrioxalate chemical actinometry method.The relative magnitude of photon absorption rate is consistent with the average turbulent kinetic energy in fluid flow simulation and the liquid renewal in vertical liquid film radial flow direction.Under the same operating conditions,the photon absorption rate of the SDR with ES-0°was 20.49%higher than that of the SDR with smooth disk,and the maximum photon absorption rate can reach 2.73×10-4 molar photons per minute.Compared with other types of photochemical reactors in the literature,the photon absorption rate of the SDR with ES-0°was increased by69.33%.Based on the research results of liquid film flow in the SDR with spoilers,a SDR model for photochemical reactions was established.For different disk structures and operating conditions,the error between the predicted and experimental values of the photoreaction conversion of the model compounds was within±20%,indicating the reliability of the established reactor model.4.Photocatalytic degradation of methylene blue and Rhodamine B composite wastewater was used as a working system to investigate the photochemical application of the SDR with spoilers.The apparent photochemical reaction rate constant and the overall removal rate of dyeing wastewater increased with the increase of rotational speed,liquid flow rate and incident light intensity and the decrease of dye concentration.The comparative study shows that the apparent rate constant and total removal rate of the SDR with ES-0°were higher,and the incident light energy consumed per unit volume of wastewater is lower.Compared with photochemical reactors reported in the literature,the apparent reaction rate constants of methylene blue and Rhodamine B in the SDR with ES-0°were increased by 1.34 times and 2.77times,respectively.The incident light energy consumed per unit volume of dye wastewater for SDR with ES-0°was reduced by 81.33%compared with other photochemical reactors.The reactor model is used to predict the total removal rate of composite wastewater.The error of overall removal efficiency of dyes between the model prediction and the experimental measurement is within±20%,which further indicates that the photochemical reactor model is reliable. |
