The condensation patterns of R1234ze(E) inside horizontal mini/macro-channels were numerically investigated under normal-gravity and zero-gravity conditions. The gravity effects on condensation heat transfer coefficients, liquid film thickness, film distribution, cross-sectional stream-traces, and liquid-phase velocity were analyzed detailedly. The influence of surface tension on condensation flow was also discussed. The gravity effect on condensation heat transfer coefficients was negligible in mini-channels with D = 1 mm, while was important for D = 2 mm and D = 4.57 mm. The gravity effect can either enhance or weaken the condensation heat transfer coefficient, which was dependent on the tube diameter and vapor quality. The enhancement on heat transfer caused by the gravity was more pronounced at lower vapor quality and mass fluxes with a larger diameter tube. The gravity affected the condensation heat performance through changing the vapor–liquid distribution, rather than the film thickness. The gravity has a great influence on the condensation flow field in both circumferential and axial direction. The surface tension played an important role in heat transfer under zero-gravity condition.

It is important to understand the patterns of two-phase flow in human nasal cavity in exploring the nasal pathology knowledge. In this paper, a realistic human nasal cavity geometry obtained from CT scans was applied to investigate the unsteady particle deposition during inhalation. The transient airflow pattern in the nasal cavity was investigated through imposing two sine wave curves at inlet with the tidal volume of 159 and 318 mL. The time-varying particle deposition pattern in the nasal cavity and a comparison of deposition characteristic between steady and unsteady inhalation were studied using the Lagrangian approach. By releasing particles continuously during inhalation, it was found that the highest transient deposition appeared about 1.4 s and the particle deposition at different time intervals was strongly depended on the instantaneous inlet flow rate. The total deposition of micro particles ranging from 1 to 20 μm under unsteady inhalation was almost the same as that at steady state when the volume of inhaled airflow was equivalent. The deposition in the anterior region of the nasal cavity was overestimated at steady state for ignoring the gravity effects at the beginning and ending of unsteady inhalation. The results of this paper can be used for both toxicological and therapeutic applications.