USING COMPUTATIONAL FLUID DYNAMICS (CFD) TO STUDY UPPER-ROOM UVGI LAMP DISINFECTION EFFECTIVENESS IN THE PATIENTS’ ROOMS

Open Access
Author:
Heidarinejad, Mohammad
Graduate Program:
Architectural Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
July 30, 2010
Committee Members:
  • Dr Jelena Srebric, Thesis Advisor
  • Jelena Srebric, Thesis Advisor
Keywords:
  • UR-UVGI lamp
  • Patient room
  • CFD
Abstract:
During the recent decades, there has been a renewed interest in dispersion of airborne microorganisms and disinfection of hospital patient rooms. This interest was particularly invigorated after results of microorganism dispersion from Computational Fluid Dynamics (CFD) obtained the same results as the physical phenomena are. The growing interest in dispersion of airborne microorganisms revealed a need to disinfect indoor environment of buildings. This disinfection process of building indoor environments increases the occupants’ health and decreases the overexposure risk of occupants to contaminants. A practical way to disinfect rooms with known presence of microorganisms, such as patient rooms or microbiology laboratories, uses upper-room ultraviolet germicidal irradiation (UR-UVGI) lamps. However, performance of UR-UVGI lamps in the patient rooms depends on a transport phenomenon that is not completely understood. For instance, it is important to notice that the wavelength of UV-C emitted from the UR-UVGI lamps can be useful to inactivate DNA of microorganisms, but the same wavelength can be harmful to occupants’ health. The intention of the present master thesis is namely to study the UR-UVGI effectiveness in patient rooms by using CFD. To assess a realistic performance of UR-UVGI lamps in patient rooms, this thesis performed a sensitivity analysis on global results, such as the fraction of remaining microorganisms, by applying various simplifications on the boundary conditions. Then, this research study used two well-known particle dispersion and spatial distribution of microorganism concentration methods: (1) The Eulerian method, and (2) The Lagrangian method. This research study used two commercial CFD software, including the PHOENICS and the Fluent, to implement the Eulerian and the Lagrangian method. To expedite simulation computational time, the present research study utilized High Performance Computers (HP) at Pennsylvania State University. This research study assessed the quality of simulations with these two methods by comparing the results with the existing experimental studies in the literature. This validation provided confidence in the simulated results as well as an insight into efficient simulations for future research studies. To the best of our knowledge, there is no single study that used various kinds of simplifications on the boundary conditions and used two microorganisms modeling approaches together. Additional research studies are needed to further validation of local microorganism concentration and improvement of simplifications. Finally, the CFD modeling methods and simplification applied in UR-UVGI CFD studies should be developed to improve accuracy of simulated results.