Ultraviolet irradiance measurement and modeling for evaluating the effectiveness of in-duct ultraviolet germicidal irradiation devices

Josephine Lau, William Bahnfleth, Richard Mistrick, Diana Kompare

Research output: Contribution to journalArticle

8 Scopus citations


This study uses ray-tracing software to calculate the fluence distribution in ultraviolet germicidal irradiation devices with different surface reflectivities and lamp configurations. Of five validation cases considered, one incorporating anisotropic duct surface reflectivity and wind-chill correction of lamp output gave the best agreement with planar irradiance measurements (mean error -3%, standard deviation 9%). The ray-tracing software was used as a validated design tool to evaluate two typical in-duct ultraviolet germicidal irradiation devices (Cases 6 and 7). Four identical UVC lamps were modeled inside a rectangular duct. The lamps were either arranged in parallel or cross flow, and spherical irradiance values along the flow path were compared. Without accounting for the thermal effect on lamp output, an ultraviolet germicidal irradiation device placed in a cross flow would give a higher average UV irradiance. This benefit would be practical when a sufficient straight run is provided in a ventilation system. However, a lamp in parallel flow would produce a more uniform UV irradiance field near the center of the device. Changing the thermal conditions would have significant impact on lamp outputs. Arranging lamps in a parallel flow would provide a higher total irradiance at low temperature and high flow conditions, especially for lamps with outputs lower than the simulated lamps and lamps without sleeves.

Original languageEnglish (US)
Pages (from-to)626-642
Number of pages17
JournalHVAC and R Research
Issue number4
Publication statusPublished - Aug 1 2012


All Science Journal Classification (ASJC) codes

  • Building and Construction

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