title: Impact of inner-wall reflection on UV reactor performance as evaluated by using computational fluid dynamics: The role of diffuse reflection.
abstract: Making use of the reflected ultraviolet (UV) radiation with a reflective inner wall is a promising way to improve UV reactor performance. In this study, the impact of inner-wall reflection on UV reactor performance was evaluated in annular single-lamp UV reactors by using computational fluid dynamics, with an emphasis on the role of diffuse reflection. The UV radiation inside the reactor chamber was simulated using a calibrated discrete ordinates radiation model, which has been proven to be a reliable tool for modeling fluence rate (FR) distributions in UV reactors with a reflective inner wall. The results show that UV reactors with a highly reflective inner wall (Reflectivity = 0.80) had obviously higher FRs and reduction equivalent fluences (REFs) than those with an ordinary inner wall (Reflectivity = 0.26). The inner-wall diffuse reflection further increased the reactor REF, as a result of the elevated volume-averaged FR. The FR distribution uniformity had conditioned contributions to UV reactor performance. Specifically, in UV reactors with a plug-like flow the FR distribution uniformity contributed to the REF to some extent, while in UV reactors with a mixed flow it had little influence on the REF. This study has evaluated, for the first time, the impact of inner-wall diffuse reflection on UV reactor performance and has renewed the understanding about the contribution of FR distribution uniformity to UV reactor performance.
authors.affiliation: Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing, 100085, China.
authors.forename: Wentao
authors.initials: W
authors.lastname: Li
authors.affiliation: Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing, 100085, China.
authors.forename: Mengkai
authors.initials: M
authors.lastname: Li
authors.affiliation: Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB T6G 2W2, Canada.
authors.forename: James R
authors.initials: JR
authors.lastname: Bolton
authors.affiliation: Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing, 100085, China.
authors.forename: Jiuhui
authors.initials: J
authors.lastname: Qu
authors.affiliation: Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing, 100085, China. Electronic address: qiangz@rcees.ac.cn.
authors.forename: Zhimin
authors.initials: Z
authors.lastname: Qiang
mesh_terms: D004203:Disinfection; D057446:Hydrodynamics; D008962:Models, Theoretical; D014466:Ultraviolet Rays
keywords: Diffuse reflection; Fluence rate distribution; Inner-wall reflection; Reduction equivalent fluence; UV reactor performance