Mohamad Kanaan, N. Ghaddar and K. Ghali
Posters: J Appl Mech Eng
The aim of this work is to check the performance of an upper room ultraviolet germicidal irradiation ( UVGI ) system operated with a localized ceiling-mounted air-conditioning system. Renewed interest emerged in upper-room UVGI due to ability to kill microorganisms while reducing the energy consumption associated with ventilation. The conditioned space is modeled using detailed computational fluid dynamics ( CFD ) software while incorporating UV intensity distribution to predict the UV dose and bacteria concentration in the supply and return stream. The CFD simulation of the space calculates the concentration distribution of the microorganism and incorporates their inactivation in presence of an ultraviolet ( UV ) field. The UV field is calculated using a published predictive model and compared to measurements performed using actinometry. The effectiveness of the UVGI system is then studied for two microorganisms: Bacillus subtilis and Escherichia coli and evaluated by the decrease, due to the UV field, in the microorganism concentration of the room return air. Moreover, CFD simulations are performed to determine an equivalent ventilation rate of the used air distribution system that will produce the same air quality in the room without use of UVGI. It was found that the killing rates of up to 71 % for B. subtilis and up to 92 % for E. coli were achieved with the use of the UVGI.
Mohamad Kanaan is a Ph.D. student at the American University of Beirut at the Department of Mechanical Engineering.