Simulation of COVID-19 Ultraviolet Disinfection Using Coupled Ray Tracing and CFD

ABSTRACT

Ultraviolet Germicidal Irradiance (UVGI) is the effective technique of inactivating disease-causing bacteria, mould spores, fungi, and viruses using ultraviolet radiation. In this study, we seek to quantify the efficacy and COVID-19 infection risk reduction achieved by UVGI in the upper unoccupied zone of a room so that we may specify the type and placement of UVGI emitters optimally. We present a computational fluid dynamics (CFD) based approach to model disinfection of aerosolized pathogens in a non-uniform ultraviolet field with mixing driven by air exchange and temperature gradients. We validate our CFD against simple calculation methods for UVGI effectiveness in well mixed spaces, and we integrate it with the Wells-Riley model of airborne infection risk to assess the relative benefit of UVGI with and against other measures. We demonstrate an order of magnitude reduction in infection risk as a result of applying UVGI, as well as the ability to quantify infection risk in non-well-mixed settings where simplified calculations methods do not apply. © International Building Performance Simulation Association, 2022