Development of a Response Surface Model of an Electrostatic Spray System and its Contributing Parameters

Electrostatic forces have been applied during the spraying of a target to enhance energy efficiency, reduce resource input and environmental pollutant output, and improve overall product quality and economic competitiveness. This study was therefore undertaken to develop a prediction response surface methodology (RSM) model of an electrostatic spray system to maximize solution attachment on the target. A ball with a surface area of 77.3 cm2 was used as a model to simulate a spherical food sample. Results indicated that the cross-products of height decrement and distance from the target to the sprayer nozzle were the most significant contributing factors for solution attachment to the front and back sides of the target, respectively. Multiple regression yielded models to predict solution attachment as functions of the contributing factors studied (air pressure from 138 to 276 kPa, distance from 80 to 120 cm, and height decrement from 10 to 20 cm) with coefficients of determination (R2) of 0.69 and 0.75 for the front and back sides of the target, respectively. Within the range of parameters tested, the response predictive model suggested that 7 s of electrostatic spraying with parameter values of 276 kPa air pressure, 100 cm distance, and 10 cm height decrement using a 1.50 mm disk orifice would achieve the most efficient solution attachment to the target. Verification studies on tomatoes and apples supported the findings that electrostatic charge enhanced spray efficiency and uniformity. This study may hence provide guidelines for the development of effective spray applications, such as sanitizing or watering target food materials.