This paper focuses on using computational fluid dynamics (CFD) modelling methods to study the effectiveness of upper–room ultraviolet germicidal irradiation (UR–UVGI) lamps in healthcare facilities. This work develops and uses simplifications for boundary conditions in CFD, while details of UR–UVGI lamps and microorganism characteristics were obtained from existing experimental studies. Three approximation methods were developed to implement the effects of UR–UVGI lamps on microorganism dispersion patterns represented with the Eulerian and the Lagrangian methods in CFD simulations. Then, a non–dimensional parameter, the UR–UVGI effectiveness, was introduced to study the effectiveness of UR–UVGI lamp(s) disinfection process with respect to the combined effect of UR–UVGI lamp(s) and ventilation systems. Although comparisons of results obtained from CFD simulations and experimental data show that local microorganism numbers/concentrations depend on boundary condition modelling methods, global variables such as the fraction of remaining microorganisms remain relatively unchanged and in a good agreement with the measured data.
Keywords: ultraviolet germicidal irradiation, UVGI, UR–UVGI lamps, lamp effectiveness, computational fluid dynamics, CFD, airborne microorganisms, healthcare facilities, boundary condition modelling, disinfection, dispersion patterns, UV radiation, simulation, ventilation systems