Dimensional analysis of UVGI air disinfection systems

A dimensional analysis of an ultraviolet germicidal irradiation (UVGI) air disinfection system within a diffusely reflective enclosure is performed using the Buckingham pi theorem. The eight dimensionless parameters obtained include the duct aspect ratio, the lamp aspect ratio, the reflectivity, and terms that incorporate the UV dose, airflow, duct dimensions, and lamp location coordinates. Computer simulation of the dose absorbed by an airborne microbe is used to predict system performance for several thousand combinations of the dimensionless parameters. Statistical analysis of these results is performed to determine the significance of each of the dimensionless parameters and their interactions. Conclusions regarding performance are summarized. The most significant parameters that determine performance of diffusively reflective UVGI systems are shown to be the dose, the reflectivity, the duct geometry, the lamp aspect ratio, lamp location, and various combined functions of these parameters. Practical implications of this research may include the improvement or optimization of UVGI air disinfection systems for in-duct and recirculation unit applications, with a consequent improvement in energy efficiency.