A ray-tracing-based method for ultraviolet fluence rate field simulation and disinfection prediction in occluded...

In recent years, ultraviolet (UV) germicidal irradiation (UVGI) has garnered increasing interest for use in public settings owing to its effectiveness and economic viability. In particular, the ultraviolet C (UVC) band exhibits strong microbicidal effects. Accurate modelling of UV fluence rate fields is essential for evaluating the disinfection performance of UVGI systems in complex indoor environments. In this study, we developed a ray-tracing-based simulation method capable of resolving fluence rate distributions under complex geometries and multiple occlusion conditions. The simulated fluence rate field was coupled with a computational fluid dynamics model to construct a predictive framework for airborne bioaerosol transport and ultraviolet disinfection. The model was validated through field measurements within a biosafety laboratory characterized by complex geometries, then used to assess the disinfection efficacy of three 0.34 W, 222 nm far-UVC lamps under 30 air changes per hour ventilation. Results indicated that far-UVC irradiation reduced bioaerosol concentrations by 18.6 % in the near-field breathing zone and by 60.0 % in the far-field zone, with a 31.0 % concentration reduction across the occupied zone. The disinfection performance was found to be influenced by pathogen-specific characteristics, source-side design parameters and environmental conditions. This method provides a robust tool for evaluating far-UVC disinfection systems in realistic indoor environments.