Effective UVGI system design through improved modeling

• Published in: ASHRAE transactions Vol. 106; pp. 721 - 730
• Main Authors: Kowalski, W J, Bahnfleth, William P
• Format: Journal Article
• Language: English
• Published: Atlanta American Society of Heating, Refrigeration and Air Conditioning Engineers, Inc 01.01.2000
• Subjects: Disease control; Disinfection; Mathematical models; Microorganisms; Ultraviolet radiation
• ISSN: 0001-2505

This paper summarizes an improved methodology for predicting the rate of airstream disinfection for UVGI systems that will enable effective designs and lower energy costs. This approach uses radiative view factors to define the three-dimensional intensity field for lamps and reflective surfaces inside enclosures. Lamp photosensor data for a variety of lamps are shown to agree more closely with the view factor model than with models using the Inverse Square Law. The intensity field due to reflectivity from internal surfaces is determined by assuming diffuse reflectivity. An analytical method is used to determine the inter-reflection component of intensity due to multiple internal reflections. The superposition of these components yields a three-dimensional intensity field matrix that can be used to calculate disinfection rates for any given microbial rate constant. Results from laboratory bioassays using S. marcescens in various duct configurations have corroborated model predictions within plus or minus 15% in most cases.