Impact of Different Air Flow Rates on Disinfection Efficacy of Multi Lamp In-Duct UVC Air Disinfection System

Abstract

Highly consequential healthcare-associated infections stem from multidrug-resistant (MDR) pathogens, culminating in escalated morbidity and mortality rates. In combating airborne MDR pathogens, in-duct Ultraviolet-C technology emerges as a viable solution, necessitating systematic enhancement of its disinfection efficacy and performance. By employing computational fluid dynamics (CFD), we fortify the efficacy and performance of a 13-lamp configured in-duct air disinfection system. The Discrete Ordinates method (DO) and user-defined function (UDF) have been used for modeling lamp irradiation and finding the average Ultraviolet-C dose of the system. In this paper, the impact of different input air flow rates on the disinfection efficacy and type of airflow inside the in-duct Ultraviolet-C air disinfection system has been studied. It has been found from this study that particles having longest resident time are aligned among particles with the lowest Ultraviolet-C dose obtained. When air velocity is increased, Ultraviolet-C dose that every particle received changes in magnitude. At high velocity the particles experienced less Ultraviolet-C dose and vice versa. The Ultraviolet-C dose distribution, however, remains relatively consistent while rate of air flow changes. The derived performance efficiency rating (PER) of 0.94 gauges the system's efficacy; notably, this surpasses EPA test series ratings by more than 50%. Turbulence analysis demonstrates that airflow within the duct is not fully turbulent, indicating no direct turbulence-UV dose relationship. However, airflow patterns within the duct markedly impact system sterilization efficacy.