Development of an ejector-based device to mitigate paint particle dispersion during airless spraying

Abstract

In airless spray painting, a considerable quantity of paint mist is generated and dispersed into the atmosphere, adversely affecting both workers’ health and the surrounding environment. In this study, a paint particle dispersion reduction device (PPDRD) was developed to be mounted on an airless spray gun, applying the ejector principle. The ejector consisted of convergent, throttle, and diffuser sections. As high-speed paint mist was ejected from the spray gun, the surrounding air was accelerated and passed through the throttle section, creating a low-pressure zone that induced air intake from the convergent section. This mechanism allowed surrounding air to be drawn in and aerosol particles to be captured without the need for an external pump. The behavior of dispersed paint particles was predicted using CFD simulations, and the ejector section of the PPDRD was optimized using Box–Behnken Design and Response Surface Methodology. The optimized geometry was fabricated via 3D printing, and pilot-scale experiments were conducted in a chamber. The number concentration of dispersed paint particles was measured and compared with and without the PPDRD. As a result, an average reduction efficiency of 41.7 % was achieved in the chamber, with a particularly pronounced decrease in number concentration observed for particles of respirable sizes. Later, a field test was performed during exterior painting work on an apartment building, where a reduction efficiency of 42.7 % was measured. The ejector-based PPDRD developed in this study is expected to reduce airborne paint particles without external power, helping mitigate air pollution and lower human exposure.