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CFD Analysis of Hydroxyl Technology to Reduce Risk of Indoor Pathogen Transmission

ASHRAE Journal, Vol. 66, no. 3, March 2024


Kishor Khankari, Connie Araps, and David Crosley


The evaluated hydroxyl technology generates reactive organic oxidant air cleaning agents (ROO radicals) that can inactivate indoor infectious aerosols and complement traditional dilution ventilation to reduce the risk of pathogen transmission. When the organic oxidants are introduced, the indoor airflow patterns play a crucial role in their distribution. Additionally, the life of the radicals and their respective kill rate are the most important parameters that determine the efficacy of this reactive air cleaning technology.

This study, with the help of CFD simulations, systematically evaluated the impact of the ROO organic oxidant radicals on the probability of infection at a breathing zone level and the spread of infection probability in a typical office space with two cubicles. The analysis predicts that introduction of hydroxyl-generated OH and ROO and radicals into the supply airstream can reduce the average probability of infection at the breathing zone of occupants by about 38% and the zone of the probability of infection (Spread Index) by 73% with an equivalent ach of 6.

The analysis further predicts that the addition of hydroxyl-generated organic oxidants can reduce the required dilution ach by 33%. The efficacy of this hydroxyl technology primarily depends on the concentration and lifespan of the circulating reactive agents and their effective kill rates. Once these parameters are determined with controlled experiments, CFD can help not only in determining the efficacy of the air cleaning technology but also in optimizing HVAC layout and strategic locations for introduction of such reactants to maximize the reduced probability of infection in indoor spaces.

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    About the author

    Dr. Kishor Khankari

    ASHRAE Fellow, ASHRAE Distinguished Lecturer

    Dr Kishor Khankari is the founder of AnSight LLC. As a specialist in Computational Fluid Dynamics (CFD), his passion for solving engineering problems and providing sound scientific solutions has led to innovations and optimized designs in the industry.

    A noted expert in his field, he has a Ph.D. from the University of Minnesota and has published in several technical journals and trade magazines. As a well sought-after speaker Dr. Khankari makes regular presentations in various technical conferences and professional meetings worldwide.

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