Abstract
The process of water droplet interaction with hot surface can result in droplet shooting off the surface. When the water is contaminated with bacteria the interaction causes substantial ambient air contamination due to aerosolization of live or injured microorganisms. This study investigates the behaviour of water droplets interacting with heated surfaces in the film boiling regime. A suggested mathematical model considers droplet shooting off conditions and following airborne droplet evolution due to cooling. The critical size of the droplet capable of taking off was modelled as a function of the wall temperature and droplet size. Following the departure from the hot surface, droplet cooling time mainly depends on the initial droplet radius while the influence of the ambient temperature is marginal. The experimental part of the study was focused on (1) investigation of the size of droplets capable of departing from the hot surface, and (2) evaluation of the influence of cooling time on the survivability of two common environmental bacterial species, Gram-negative Escherichia coli and Gram-positive Bacillus subtilis. Droplets with the sizes of up to one millimetre shooting off the hot surfaces were detected, which correlates with the theoretical results. It was found that, under realistic physical conditions, the process of liquid interaction with hot surface does not ensure an efficient microbial inactivation. It was also shown that the shortest cooling time was associated with higher survival rates of both bacterial strains used in this study. However, even for the longest cooling time of 15 seconds the amount of live bacteria in the aerosolized droplet carrier can be substantially high with recovery rates of approximately 50% for B. subtilis.
Highlights
The process of interaction between a water droplet and hot surfaces has been widely investigated
In our previous investigation we experimentally demonstrated that the water-surface interaction may be associated with generation of viable bacterial aerosols when the water is contaminated with bacteria[11]
Aerosolization of live microorganisms in liquid carriers resulting from interaction of microbial suspension with hot surfaces can potentially cause substantial contamination of ambient air in industrial and residential environments
Summary
Ekaterina Mirskaya[1], Vladimir Maksimenko[2], Valery Zagaynov2 & Igor Agranovski 1 ✉. This study investigates the behaviour of water droplets interacting with heated surfaces in the film boiling regime. The experimental part of the study was focused on (1) investigation of the size of droplets capable of departing from the hot surface, and (2) evaluation of the influence of cooling time on the survivability of two common environmental bacterial species, Gram-negative Escherichia coli and Gram-positive Bacillus subtilis. Aerosolization of live microorganisms in liquid carriers resulting from interaction of microbial suspension with hot surfaces can potentially cause substantial contamination of ambient air in industrial (cooling of hot equipment, using of metal-working fluids in machining operations, etc) and residential (using of potentially microbially contaminated liquids to pour onto rocks in saunas, extinguishing BBQ equipment, etc.) environments Considering that such process can potentially result in aerosolization of pathogenic bacteria, the mechanism requires special attention. The results were analysed taking into account the additional 100 ml of water mixed with the bacterial suspension
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
