Design, Simulation and Experimental Validation of a Minor Flow Channel Based Virtual Impactor to Generate Mono-Disperse Aerosols

Abstract

The controlled release of mono-disperse aerosols can lower pollution and improve the environment and public health in Bangladesh, a developing country in South Asia. Different aerosol generation systems, such as conventional and virtual impactors (VI) mostly jet impactor, rectangular jet virtual impactor, slot-in-line virtual impactor, dichotomous virtual impactor and cascade impactor have been identified so far for the aerosol research based on condensation, penetration, atomization, and diffusion. To ensure uniformity in the dispersed or suspended aerosols, both conventional and virtual impactors can be used. The virtual impactors substitute a fake area of the slowly drifting air for the impaction region. Mono-disperse aerosol can be produced using a variety of techniques and methods, however the virtualized mono-disperse aerosol generating system with impaction plate might be a viable choice with many application domains. In order to address issues like the re-suspension of impacted particles, a virtual impactor has been designed, and the flow of aerosol particles inside the impactor has been simulated. By dividing the flow streams, the impaction surface is in this instance substituted by a minor collecting flow, giving rise to the concept virtual. Particles that are too small to be collected in the minor flow are carried out of the side of the virtual impactor by the "major flow," which is the bigger proportion of the flow. In this study, a virtual impactor with a single air intake, a minor stream channel that is inclined at 450 degrees to the inlet aerosol flow path, and a particle generator are designed, numerically analyzed, and tested for performance. The intended impactor's distribution of velocity profile, distribution of pressure, tracking of particles, and erosion contour have all shown simulation results. Wall losses of the virtual impactor have also been analyzed. The liquid mixture of 80% ethanol and 20% olive oil is used to create the mono-disperse aerosol. The minimum GSD (Geometric Standard Deviation) for this aerosol has been found to be 1.22 at an air flow rate of 56.6 lpm to the virtual impactor, and the NMAD (Number Mean Aerodynamic Diameter) has been determined to be 0.475 μm. For a minor flow of 13.28%, the monodisperse aerosol has been produced. A comparative study has been done between different types of impactors of aerosol generation systems with the designed and simulated virtual impactor based on design, mono-disperse aerosol generation and performance.