Optimization of induction charging of water droplets to develop an electrostatic spray scrubber intended for poultry particulate matter mitigation

Authors: KNIGHT, R - The Ohio State University; LI, X - The Ohio State University; HOCTER, J - The Ohio State University; ZHANG, B - The Ohio State University; ZHAO, L - The Ohio State University; Zhu, Heping

Submitted to: Journal of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2022
Publication Date: 8/30/2022
Citation: Knight, R.M., Li, X., Hocter, J.S., Zhang, B., Zhao, L., Zhu, H. 2022. Optimization of induction charging of water droplets to develop an electrostatic spray scrubber intended for poultry particulate matter mitigation. Journal of the ASABE. 65(4):815-824. https://doi.org/10.13031/ja.14913.
DOI: https://doi.org/10.13031/ja.14913

Interpretive Summary: Within poultry facilities, particulate matter (PM) is a major air pollutant. Exposure to poultry PM can lead to respiratory ailments among workers and increased bird mortality rates. In this research, an experimental electrostatic spray scrubber was developed. Three types of spray nozzles were tested with a range of applied voltages, mass flow rates, and water conductivities. Applied voltage was found to have a parabolic effect on mean charge-to-mass ratio using small spray nozzles. Once the applied voltage reached approximately negative 12 kV, the electric field strengthened to the point that droplet charging became most efficient. An optimal spray configuration was then determined to maximize the charge-to-mass ratio of the spray droplets for the electrostatic spray scrubber to collect airborne PM effectively in poultry facilities. The results of this study could be used to design, test, and optimize the electrostatic spray scrubber design for mitigation of poultry PM, as the spray droplet charging was found to be important but not the sole process governing collection of PM in poultry facilities.

Technical Abstract: Particulate matter (PM) is a prominent air pollutant in poultry facilities. One promising technology for PM mitigation in poultry facilities is the electrostatic spray scrubber (ESS). However, there is a significant lack of information on the charging characteristics of an ESS to promote efficient droplet charging and poultry PM collection. This study explored the effects of applied voltage, water mass flow rate, water conductivity, and spray pattern on the charge-to-mass ratio (CMR) of droplets charged by an ESS. Voltages from -5 to -14 kV were applied to a 100-mm diameter copper electrode ring to charge droplets sprayed from different nozzles using 80° hollow cone, 80° tapered edge flat, and 110° tapered edge flat spray patterns. It was found that CMRs increased with increasingly negative voltages up to a point, after which increasingly negative voltages would decrease the CMR. A similar trend was observed for the effects of water mass flow rate on CMR. Water conductivity showed inconsistent effects on CMR across spray patterns and was deemed a statistically significant but practically insignificant factor. The 80° tapered edge flat spray pattern was found to produce the greatest CMRs. A linear regression model (R2 = 0.865) was developed and optimized to find the ESS configuration resulting in the greatest droplet CMR. The optimal CMR was 0.578 mC kg-1, produced using an 80° tapered edge flat spray nozzle at a water mass flow rate of 0.397 kg min-1 and a conductivity of 0.05 S m-1 with an applied voltage of -11.6 kV.