Evaluation of electrostatic sprayers and foggers for the application of disinfectants in the era of SARS-CoV-2

Although research has shown that the COVID-19 disease is most likely caused by airborne transmission of the SARS-CoV-2 virus, disinfection of potentially contaminated surfaces is also recommended to limit the spread of the disease. Use of electrostatic sprayers (ESS) and foggers to rapidly apply disinfectants over large areas or to complex surfaces has emerged with the COVID-19 pandemic. ESSs are designed to impart an electrostatic charge to the spray droplets with the goal of increasing deposition of the droplets onto surfaces, thereby promoting more efficient use of the disinfectant. The purpose of this research was to evaluate several spray parameters for different types of sprayers and foggers, as they relate to the application of disinfectants. Some of the parameters evaluated included the spray droplet size distribution, the electrostatic charge, the ability of the spray to wrap around objects, and the loss of disinfectant chemical active ingredient due to the spray process. The results show that most of the devices evaluated for droplet size distribution had an average volume median diameter ≥ 40 microns, and that four out of the six ESS tested for charge/mass produced sprays of at least 0.1 mC/kg. A minimal wrap-around effect of the spray deposition onto a cylindrical object was observed. The loss of disinfectant active ingredient to the air due to spraying was minimal for the two disinfectants tested, and concurrently, the active ingredient concentrations of the liquid disinfectants sprayed and collected 3 feet (1 meter) away from the spray nozzle do not decrease.

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Investigation of Droplet Size Distribution for Vibrating Mesh Atomizer

10.21203/rs.3.rs-1108564/v1 ◽

2021 ◽

Author(s):

Pallavi Sharma ◽

Mohammed Quazi ◽

Irma Rocio Vazquez ◽

Nathan Jackson

Keyword(s):

Size Distribution ◽

Droplet Size ◽

Droplet Size Distribution ◽

Primary Objective ◽

Droplet Distribution ◽

High Uniformity ◽

Median Diameter ◽

Silicon Based ◽

And Control ◽

Uniform Droplet

Abstract Vibrating mesh atomizers (VMA) are increasing in demand for various aerosol applications due to their ability to generate uniformly sized droplets. Currently there are two types of VMA (commercial metallic membranes and silicon based). High Uniformity and control of small droplet size are the basic requirements for many aerosol applications, for which ultrasonic or VMA are employed. However, there is limited research on understanding the droplet size distribution of different types of atomizers. In this study three aerosol generators were investigated: Ultrasonic, metallic VMA, and MEMS-based silicon VMA. The primary objective was to compare these devices on droplet size distribution and mechanism of action. A systematic study to compare the performance of the two VMA was investigated based on droplet distribution, volumetric median diameter (VMD) using liquids with different physiochemical properties. Size distribution of the droplet produced by the metallic VMA was twice the span compared to silicon VMA for fluids with viscosity <2cP. The metallic VMA also resulted in an increase in VMD as the viscosity increased, whereas the Si VMA did not see a significant increase in VMD. The silicon-based VMA demonstrated a 4-15x increase in fine particle fraction control compared to metallic VMA. The results demonstrate that silicon based VMA has narrower droplet distribution with more uniform droplet size and lower span compared to metallic VMA.

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Characterization of Biological Pesticide Deliveries through Hydraulic Nozzles

Transactions of the ASABE ◽

10.13031/trans.12698 ◽

2018 ◽

Vol 61 (3) ◽

pp. 897-908

Author(s):

Liping Xiao ◽

Heping Zhu ◽

Matthew Wallhead ◽

Leona Horst ◽

Peter Ling ◽

...

Keyword(s):

Droplet Size ◽

Spray Deposition ◽

Crop Protection ◽

Droplet Size Distribution ◽

Spray Parameters ◽

Plant Leaves ◽

Spray Pattern ◽

Flow Capacity ◽

Nozzle Type ◽

Pattern Width

Abstract. Increased use of biopesticides has spurred demand for efficient and effective delivery systems. To this goal, laboratory tests were conducted to investigate six different classes of biopesticides discharged from five different types of flat-fan nozzles, each with three flow capacities. The biopesticide classes were horticultural oil insecticide (HOI), bacterial biofungicide (BBF), botanical extract bio-insecticide (BEBI), liquid fungal bio-insecticide (FBI-ES), wettable powder fungal bio-insecticide (FBI-WP), and mineral salt biofungicide (MSBF). Droplet size distribution, spray pattern width, spray deposition, and coverage on plant leaves and water-sensitive paper (WSP) were the spray parameters tested. These parameters varied greatly with biopesticide class, nozzle type, and nozzle flow capacity. The DV0.5 of the biopesticides ranged from 75 to 519 µm for 0.76 L min-1 nozzles, from 86 to 509 µm for 1.51 L min-1 nozzles, and from 99 to 622 µm for 2.25 L min-1 nozzles. The use of different biopesticides with the same nozzle significantly altered the spray pattern width. Compared to a water-only solution, the largest change of spray pattern width was 14.7% for the air-induction nozzle (AI11004) discharging FBI-ES. The amount of spray deposited on plant leaves for all tested biopesticides (except HOI) did not vary significantly with different nozzle types. However, the air-induction nozzles produced the most uneven spray deposition patterns. Therefore, to achieve optimal spray application efficiency and effectiveness for discharging specific classes of biopesticide, the choice of the proper nozzle type and flow capacity is critical. Keywords: Biopesticide, Crop protection, Deposition, Droplet size, Spray coverage.

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A Statistical Model for the Joint Distribution of Droplet Size and Charge Density in an Electrostatic Spray

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.97-101.1438 ◽

2010 ◽

Vol 97-101 ◽

pp. 1438-1444

Author(s):

Jun Zhang ◽

Michael W. Reeks

Keyword(s):

Charge Density ◽

Size Distribution ◽

Droplet Size ◽

Joint Distribution ◽

Droplet Size Distribution ◽

Peak Position ◽

Entropy Method ◽

Spray Parameters ◽

The Right ◽

Electrostatic Spray

A theoretical model to predict the joint distribution of droplet size and charge density for an electrostatic spray is described based on the maximum entropy method. From known values of the electrostatic spray parameters, the model is used to evaluate the joint distribution of droplet size and charge density for a cone-jet mode electrostatic spray. The predicted results of present model show that it has generally a relatively narrow distribution for both droplet and charge density in a cone-jet mode. Comparatively, the droplet size distribution is narrower than that of the charge density. In addition the two distributions are significantly different in shape. The droplet size distribution is nearly symmetric about its peak position, whilst the left side of the charge density distribution curve is noticeably steeper than the right side. The results are also compared with existing experimental data with agreement considering the uncertainties in the data.

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Quantitative Analysis of Droplet Size Distribution in Plant Protection Spray Based on Machine Learning Method

Water ◽

10.3390/w14020175 ◽

2022 ◽

Vol 14 (2) ◽

pp. 175

Author(s):

Yong He ◽

Jianjian Wu ◽

Haoluan Fu ◽

Zeyu Sun ◽

Hui Fang ◽

...

Keyword(s):

Machine Learning ◽

Size Distribution ◽

Droplet Size ◽

Evaluation Method ◽

Plant Protection ◽

Droplet Size Distribution ◽

Support Vector ◽

Median Diameter ◽

Deposition Uniformity ◽

Main Factor

Spray droplet size is the main factor affecting the deposition uniformity on a target crop. Studying the influence of multiple factors on the droplet size distribution as well as the evaluation method is of great significance for improving the utilization of pesticides. In this paper, volume median diameter (VMD) and relative span (RS) were selected to evaluate the droplet size distribution under different hollow cone nozzles, flow rates and spatial positions, and the quantitative models of VMD and RS were established based on machine learning methods. The results showed that support vector regression (SVR) had excellent results for VMD (Rc = 0.9974, Rp = 0.9929), while multi-layer perceptron (MLP) had the best effect for RS (Rc = 0.9504, Rp = 0.9537). The correlation coefficient of the prediction set is higher than 0.95, showing the excellent ability of machine learning on predicting the droplet size distribution. In addition, the visualization images of the droplet size distribution were obtained based on the optimal models, which provided intuitive guidance for realizing the uniform distribution of pesticide deposition. In conclusion, this study provides a novel and feasible method for quantitative evaluation of droplet size distribution and offers a theoretical basis for further determining appropriate operation parameters according to the optimal droplet size.

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Fog Classification by Their Droplet Size Distributions: Application to the Characterization of Cerema’s Platform

Atmosphere ◽

10.3390/atmos11060596 ◽

2020 ◽

Vol 11 (6) ◽

pp. 596 ◽

Cited By ~ 1

Author(s):

Pierre Duthon ◽

Michèle Colomb ◽

Frédéric Bernardin

Keyword(s):

Size Distribution ◽

Droplet Size ◽

Droplet Size Distribution ◽

Transportation Systems ◽

Distribution Range ◽

Size Distributions ◽

Atmospheric Conditions ◽

Different Types ◽

Radiation Fogs ◽

Droplet Size Distributions

Fog is one of major challenges for transportation systems. The automation of the latter is based on perception sensors that can be disrupted by atmospheric conditions. As fog conditions are random and non-reproducible in nature, Cerema has designed a platform to generate fog and rain on demand. Two types of artificial fog with different droplet size distributions are generated: they correspond to radiation fogs with small and medium droplets. This study presents an original method for classifying these different types of fog in a descriptive and quantitative way. It uses a new fog classification coefficient based on a principal component analysis, which measures the ability of a pair of droplet size distribution descriptors to differentiate between the two different types of fog. This method is applied to a database containing more than 12,000 droplet size distributions collected within the platform. It makes it possible to show: (1) that the two types of fog proposed by Cerema have significantly different droplet size distributions, for meteorological visibility values from 10 m to 1000 m; (2) that the proposed droplet size distribution range is included in the natural droplet size distribution range; (3) that the proposed droplet size distribution range should be extended in particular with larger droplets. Finally, the proposed method makes it possible to compare the different fog droplet size distribution descriptors proposed in the literature.

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Review of electrospray observations and theory

JOURNAL OF ENGINEERING & PROCESSING MANAGEMENT ◽

10.7251/jepm181002041b ◽

2019 ◽

Vol 10 (2) ◽

Author(s):

Stefan Bošković ◽

Branko Bugarski

Keyword(s):

Electric Field ◽

Size Distribution ◽

Droplet Size ◽

Capillary Tube ◽

Droplet Diameter ◽

Droplet Size Distribution ◽

New Classification ◽

Different Types

While a liquid is dripping out of a capillary tube, there is a possibility to affect the characteristics of the exiting flow in certain ways. One of the ways already used is by introducing an electric field that can be used to change the average droplet diameter and the droplet size distribution. This process is called electrospraying, while the theory behind it is sometimes called electrohydrodynamics (EHD). This phenomenon has been investigated for more than a hundred years both empirically and theoretically. In this paper, a review of the available literature and the empirical and theoretical findings is presented. A new classification of the electrospray modes had to be given to include all the different modes mentioned by different authors. The necessary pieces of the equipment and their different types are also given.

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