Experimental study on the effect of light source arrangements on the disinfection performance of upper-room 222 nm Far-UVC

• Published in: Journal of hazardous materials Vol. 479; p. 135571
• Main Authors: Wang, M.H., Wu, X.M., Lai, A.C.K.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 05.11.2024
• Subjects: Air Microbiology; Disinfection - methods; Escherichia coli - drug effects; Escherichia coli - radiation effects; Far-UVC irradiation; Indoor air quality; Spatial irradiance prediction; Staphylococcus epidermidis - drug effects; Staphylococcus epidermidis - radiation effects; Ultraviolet Rays; Upper-room germicidal irradiation; Upper-room germicidal irradiation; Far-UVC irradiation; Spatial irradiance prediction; Indoor air quality
• ISSN: 0304-3894; 1873-3336; 1873-3336
• DOI: 10.1016/j.jhazmat.2024.135571

The air disinfection efficacy of upper-room 222 nm Far-UVC was experimentally investigated in a real-size chamber under well-mixed air conditions. Two bacteria (Escherichia coli, Staphylococcus epidermidis) and two bacteriophages (MS2, and P22) were selected for the test. The study considered different lamp source arrangements, including single and double sources, stationary and rotating operating modes, and an overlapping mode with a 45° irradiation angle. A numerical view-factor model was developed to analyze the irradiance distributions. Four irradiation angles, 30°, 45°, 60°, and 90°, were chosen. The results show that the lamps operating with an irradiation angle of 45° provide the highest chamber-averaged irradiance. This suggests an optimal irradiance level for a given room dimension, as inferred from the view factor model. Experimental results indicated that the overlapping mode with a 45° irradiation angle consistently outperformed both the stationary mode and rotating mode in disinfection. This can be attributed to the higher chamber-averaged irradiance, which is also supported by the numerical model predictions. The increment ratios ranged from 14.9 % to 42.9 % compared to the stationary mode. The susceptibility constants of Escherichia coli, Staphylococcus epidermidis, MS2, and P22 were measured as 0.572 m2/J, 0.099 m2/J, 0.060 m2/J, and 0.081 m2/J respectively. [Display omitted] •Upper-room far-UVC irradiation effectively inactivates a wide range of microbial species.•A model based on radiative view factor reliably predicts the distribution of UV irradiance.•The chamber-averaged irradiation delivered by a UV lamp is influenced by its irradiation angle.•Fixed lamps inclined at 45° gives the highest disinfection efficacy.