Modelling the performance of upper room ultraviolet germicidal Irradiation devices in ventilated rooms: comparison of analytical and CFD methods

Models to evaluate upper room ultraviolet germicidal irradiation (UVGI) devices can be used to improve the understanding of the behaviour of UV devices in ventilated rooms and so enable more confident predictions to be made of their performance. This paper presents two- and three-zone mixing models for investigating the effect of upper room UVGI devices in a typical ventilated room. The results from these analytical models are compared to a CFD simulation of the same room that incorporates the biological inactivation of microorganisms in the presence of an ultraviolet field. The study demonstrates that analytical mixing models give reasonably good average zone concentrations and are therefore useful in estimating overall performance. However, the CFD simulations are necessary to fully examine the interaction of the room airflow with the inactivation of micro-organisms due to the UV field.