The study of spray evaporation and deposition in the respiratory airway is crucial for understanding the efficacy of inhaled medications. While numerous factors influence these processes, the effect of applied mass remains an underexplored variable. This paper investigated the relationship between the applied mass of a spray and its evaporation and deposition within the respiratory airway. Experimentally determined spray parameters were implemented as the boundary/initial conditions in an integrated MDI-airway model. Large-eddy simulations (LES) and the chemical species model were implemented to simulate airflow and water vapor transport. The discrete-phase Lagrangian approach and a multicomponent evaporation–condensation model were utilized to track the trajectories and deposition of evaporating droplets. The results showed significant thermohumidity differences in the mouth among the four applied masses considered. Droplets evaporated most quickly upon administration; however, it took 0.9 s for 17 mg sprays to reach their equilibrium and 0.4 s for 0.017 mg sprays, indicating a prevailing influence of droplet evaporation throughout the respiratory tract. Smaller droplets evaporated faster than larger droplets and were more affected by the local thermohumidity and applied mass. The most notable dosimetry differences among different applied masses were observed in the mouth and pulmonary region. The regional DF exhibited a positive relationship with applied mass in the mouth but a negative relationship in the larynx and downstream airways. For all applied masses considered, the count-based dosimetry method overestimated the drug-based DF in the pulmonary region by a factor of 2.70%±0.65%, while the mass-based dosimetry underestimated it by a factor of 0.26%±0.08%.

As a means of harvesting solar energy for water treatment, solar-driven vapor generation is becoming more appealing. Due to their entangled fibrous networks and high surface area, fibers can be used as building blocks to generate water vapor. In this paper, using a two-dimensional fiber bundle model, we studied the generation of solar vapor based on the fiber height, distance between fibers, and input sun radiation. The performance of solar absorption system was also evaluated by evaluating thermal and water management. Results showed a constant increase in solar vapor generation with an increasing fiber height and decreasing inter-fiber distance. However, the gain rate of using taller and more densely packed fiber bundles dwindled quickly. On the other hand, a shorter fiber had a higher evaporation rate per fiber height. The distance between fibers had a nonlinear effect on the fiber bundle evaporation rate. A new fiber bundle design was recommended with a fiber height of 15–20 mm and an inter-fiber distance of 1.5 mm. The results of this study can provide guidelines for future fiber bundle designs with increased efficiency, reduced cost, and versatile applications (i.e., desalination, water purification, and power generation).

Accurate modeling and simulation of metered-dose inhaler (MDI) drug delivery require detailed information about the spray aerosols and carrier airflows, which are sensitive to the geometry and formulation of the inhaler. This study aimed to systemically examine the effects of the MDI canister–holder guiding vanes and the orifice airflow on inhalation dosimetry. An MDI model was reconstructed from an actual inhaler that included a 0.5-mm-diameter orifice and six vertical guiding vanes on the inner wall of the canister–holder. Large-eddy simulation was used to capture the transient concurrent inspiratory and orifice airflows, and spray aerosols were tracked using the Lagrangian method. Measured aerosol size distribution and velocity were used to develop the computational model. Results show that MDI spray plume transport and deposition are sensitive to the instantaneous flow structures. Excluding the guiding vanes increased the mouth deposition by 8% (from 60% to 68%), while excluding the orifice jet flow decreased the mouth deposition by 5.5% (from 60% to 54.5%) compared to the control case. The impact of these two geometrical and flow details could persist in the small airways. The penetration rate to the left-lower lobe beyond the nineth generation (G9) increased by 67% when neglecting guiding vanes and increased by 50% when neglecting orifice flow.