The effects of temperature and humidity on the deposition of nebulized droplet in an idealized mouth-throat model

Abstract

Inhalation therapy is a practical approach to treat respiratory diseases. Vibrating mesh nebulizer (VMN), a device for inhalation therapy, is favored for its advantages, such as portability and noiselessness. The droplet deposition experiment using the VMN was carried out in an idealized mouth-throat (MT) model. This study used the 0.9% w/v concentration of nebulized sodium chloride (NaCl) droplet to measure the deposition fraction (DF). The inhalation flow rates were changed under two different temperature and humidity conditions, and the variation of droplet DFs as a function of inertial parameters was obtained under different inhalation flow rate conditions. The results show that the DF first decreases and then increases with the increasing inertial parameter, which is distinctly different from previous conclusions for dry powder or particle experiments and simulations. It indicates that the droplet evaporation substantially affects the transport and deposition. The results also show that increasing the mass fraction of water vapor in the air increases droplet DF in the airway.