Deng Baoqing, Jiang Yuanzhen, Gao Lin, Zhao Bensheng
Department of Environmental Science and Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, People's Republic of China.
Environ Sci Pollut Res Int. 2023 Feb;30(9):24132-24142. doi: 10.1007/s11356-022-23737-8. Epub 2022 Nov 5.
Photocatalytic oxidation is a promising technology to degrade volatile organic compounds. The performance of photocatalytic reactors is affected by the hydrodynamics, radiation transfer, mass transfer and reaction kinetics. Baffles may improve the hydrodynamics. The effect of baffles on heterogeneous photocatalytic oxidation of gas-phase ethylene in three annular reactors is simulated using computational fluid dynamics. ANSYS Fluent is used to solve all governing equations. Baffles can improve the uniformity of flow and prolong the residence time. The residence time of the C-type reactor and B-type reactor is 0.5% greater than the unbaffled reactor. Baffles have little effect on the radiation distribution. The concentric arrangement of lamp and the reactor leads to a radial dominance of radiation. The effect of baffles on the diffusion of ethylene is complex. The effective diffusion coefficient at the catalyst surface in the C-type reactor decreases 9.5% and that in the B-type reactor increases 3% with respect to the unbaffled reactor. The outlet ethylene concentration is 4.19 ppmv for the U-type reactor, 3.93 ppmv for the C-type reactor and 3.62 ppmv for the B-type reactor. The optimal performance in the B-type reactor is due to the large diffusion coefficient of ethylene. The arrangement of baffles should enlarge the effective diffusion coefficient at the catalyst surface as far as possible.
光催化氧化是一种降解挥发性有机化合物的很有前景的技术。光催化反应器的性能受流体动力学、辐射传递、传质和反应动力学的影响。挡板可以改善流体动力学。使用计算流体动力学模拟了挡板对三个环形反应器中气相乙烯非均相光催化氧化的影响。使用ANSYS Fluent求解所有控制方程。挡板可以提高流动均匀性并延长停留时间。C型反应器和B型反应器的停留时间比无挡板反应器长0.5%。挡板对辐射分布影响很小。灯与反应器的同心布置导致辐射呈径向主导。挡板对乙烯扩散的影响很复杂。相对于无挡板反应器，C型反应器中催化剂表面的有效扩散系数降低了9.5%，B型反应器中则增加了3%。U型反应器的出口乙烯浓度为4.19 ppmv，C型反应器为3.93 ppmv，B型反应器为3.62 ppmv。B型反应器的最佳性能归因于乙烯的大扩散系数。挡板的布置应尽可能扩大催化剂表面的有效扩散系数。
