Evolution of droplet size distribution in selected nebulizers

Abstract

Nebulizers are the class of atomizing devices used to disperse liquids to fine droplets. They found their application in selected technological (typically: small-scale) processes, but their most common use is related to the generation of medicinal aerosols for inhalation. In this work we present the experimental data on the evolution of the size distributions of water droplets generated by two nebulizers (pneumatic and vibrating-mesh) as a result of aerosol mixing with the ambient air. Such a process reflects the real situation, where aerosol emitted from a nebulizer is diluted by additional air sucked by a patient during inhalation. Droplet size distribution was determined by laser diffraction, and these results were further discussed including the data of the aerosol velocity measured by the Laser Doppler Anemometry (LDA). It was demonstrated-as expected-that dilution with the ambient air with moderate humidity results in the intense evaporation of the smallest droplets. However, larger droplet may be saved to a different degree depending on the velocity and geometry of the aerosol cloud emitted from the nebulizer, and on the volume of the diluting air. These parameters have an influence on the droplet coalescence which is another process shaping the droplet size distribution in the studied conditions. The results can deepen the understanding of the mist dynamics which can be applied in various fields of colloidal science and technology.

Optimizing Coaxial Sonic Spray Geometry for Generating Water Microdroplets

“…For a similar coaxial spray geometry, an increase in the gas velocity, which caused the shear effect of the gas on the droplet to increase, resulted in the decrease of the droplet diameters . In Figure B, the RSF values increase slightly at higher gas pressures, which indicates a slight decrease in spray quality. , …”

“…11 In Figure 4B, the RSF values increase slightly at higher gas pressures, which indicates a slight decrease in spray quality. 12,13 Effects of the Type of Water on Microdroplet Sizes. Different types of water were studied, from ultrapure water (ASTM) to tap water and water with added NaCl as listed in Table 1.…”

Influence of Physicochemical Properties of Budesonide Micro-Suspensions on Their Expected Lung Delivery Using a Vibrating Mesh Nebulizer

“…Another issue, although not discussed here, is the velocity of the aerosol emitted from the nebulizer, which also influences the amount of drug delivered to the lungs. The results obtained with the laser Doppler analysis (LDA) [ 54 ] allow to evaluate the role of droplet impaction on the elements attached to the nebulizer, such as the mouthpiece, mask, or the tubing of the nebulizer–ventilator circuit. Such losses of the drug have a fundamental role, e.g., in the effective treatment of patients under ventilatory support [ 55 , 56 ].…”

Liquid atomization process in medical applications

“…Both techniques require sophisticated equipment, so they are not often used for nebulizer characterization. In our laboratory, we have an opportunity to use 2D LDA system (Dantec, Denmark) for this purpose [1].…”