article · Rutgers University Community Repository (Rutgers University) · 2026
Modeling and numerical simulation of the transport, distribution, and antimicrobial effectiveness of plasma-activated mist
Cited by 0Open access
Abstract
Non-thermal plasma (NTP) is an emerging technology that has the ability to treat foods to extend their shelf lives and reduce microbial loads. NTP generates reactive oxygen and nitrogen species (RONS), such as ozone, hydrogen peroxide, and peroxynitrite, which act as antimicrobial agents. Researchers are keen to leverage NTP in the food industry, as NTP treatments are seen as cleaner and non-residue-forming compared to conventional cleaning methods. Different variations of NTP are currently being investigated, including plasma-activated mist (PAM), which has been a topic of research over the past decade. In PAM, an aerosol of small water droplets, ranging in diameter from 2 µm to 20 µm, passes through a plasma discharge. The high surface to volume ratio of the droplets allows for effective mass transfer of the RONS into the liquid phase. As such, PAM has the potential to generate RONS in both the gaseous and liquid phases. There is a desire to understand more about PAM, particularly to evaluate if it can effectively treat surfaces with complex topologies, thereby increasing its commercial viability. However, not much is known about its transport or distribution in different treatment configurations yet. An area of interest is to understand how the design of a treatment chamber can potentially optimize or limit the antimicrobial effectiveness of PAM. Therefore, the objective of this research was to evaluate the transport phenomena of PAM droplets to see how the test conditions of a treatment chamber affected the efficacy of PAM as an antimicrobial agent for surface applications. In this work, PAM treatments were used to inactivate Klebsiella michiganensis B199A, a surrogate of pathogenic Salmonella spp. in cross-contamination studies, in a benchtop 33.5 L “small” chamber, a 100.5 L “long” chamber, and a 100.5 L “tall” chamber. Up to 4 log CFU/plate inactivation was achieved in the small chamber when treated for 20 min, whereas lower inactivation occurred in the tall and long chambers. A maximum of 1.6 CFU/plate and 0.6 CFU/plate inactivation was achieved in the tall and long chambers, respectively. These results indicated that it might not have been possible to further increase the size of the chamber without negatively affecting the microbial results. Therefore, it is likely that multiple plasma discharge devices would be needed to cover larger treatment areas than the ones used in this study. The findings in this work suggest that the PAM droplets contributed to a lesser degree to the overall microbial inactivation than the gas-plasma phase species. An additional set of tests were completed with the mist nebulizer removed from the systems. Results showed that equivalent inactivation was achieved in the small chamber whether mist was present or not, and less inactivation was seen in the tall and long chambers when the mist was present. However, the ozone concentration was significantly reduced, from 180 ppm when mist was absent to 24 ppm when mist was present. COMSOL Multiphysics® was used to numerically simulate three-dimensional PAM flow and flow from air-based DBD plasma with no mist within the chambers. Droplets were traced to evaluate transport non-uniformity, and the microbial inactivation of Klebsiella michiganensis B199A at various locations within the chamber was predicted based on the total RONS load delivered. Numerical simulation results demonstrated that PAM droplets did not evenly distribute within the treatment chambers. 20 µm droplets quickly fell out of air streamlines and did not progress significantly, whereas 2 µm droplets continued to recirculate through the plasma discharge and pick up additional RONS. Overall, there was an uneven distribution, with some petri dishes being significantly wetted less than others. As such, some petri dishes achieved near zero inactivation from the liquid species, particularly in the tall chamber, and the inactivation from the liquid RONS contributed less than 1 log CFU/plate consistently. The gas phase DBD plasma flow, however, quickly filled the chambers, resulting in more homogenous microbial inactivation across the chamber, achieving more than 1 log CFU/plate in all cases. These simulation results, combined with the physical microbial experiments, indicate that gaseous ozone could have been the primary species for inactivation. This further indicates that the introduction of mist served more to alter the plasma reaction mechanism rather than contribute to the antimicrobial effectiveness. This study showed that PAM treatments can be used to inactivate microorganisms as a mild treatment to reduce the presence of spoilage and pathogenic microorganisms and reduce the risk of cross contamination. It also showed that the addition of mist can help to reduce ozone concentrations closer to environmental, health, and safety limits. Going forward, it is recommended that research into PAM transport continues. Understanding the fundamental PAM transport models to simulate the microbial inactivation rates will further add to the current knowledge baseline of PAM treatments and potentially grant future researchers the ability to predict inactivation rates in other chamber configurations and applications.
Cite this paper
Lorenz, E. J. (2026). Modeling and numerical simulation of the transport, distribution, and antimicrobial effectiveness of plasma-activated mist. Rutgers University Community Repository (Rutgers University). https://doi.org/10.7282/t3-qdtp-7177
Lorenz, Eric Joseph. “Modeling and numerical simulation of the transport, distribution, and antimicrobial effectiveness of plasma-activated mist.” Rutgers University Community Repository (Rutgers University), 2026, https://doi.org/10.7282/t3-qdtp-7177.
Lorenz, Eric Joseph. 2026. “Modeling and numerical simulation of the transport, distribution, and antimicrobial effectiveness of plasma-activated mist.” Rutgers University Community Repository (Rutgers University). https://doi.org/10.7282/t3-qdtp-7177.
Lorenz, E.J. (2026) ‘Modeling and numerical simulation of the transport, distribution, and antimicrobial effectiveness of plasma-activated mist’, Rutgers University Community Repository (Rutgers University). Available at: https://doi.org/10.7282/t3-qdtp-7177.
@article{lorenz2026modeling,
title = {{Modeling and numerical simulation of the transport, distribution, and antimicrobial effectiveness of plasma-activated mist}},
author = {Lorenz, Eric Joseph},
journal = {Rutgers University Community Repository (Rutgers University)},
year = {2026},
doi = {10.7282/t3-qdtp-7177}
}Made from the index record. Check names, capitalisation and page numbers against the paper. Need another style? AI for Research has over 10,000.