Modeling of the passive evaporative cooling in a wet inclined tube truncated at both ends

This study investigates the passive evaporative cooling process in a wet, inclined, and circular-section tube truncated at both ends. An analytical model, developed using one-dimensional energy and species balances under buoyancy-driven airflow, is validated against experimental data from a previously published study. A parametric analysis is conducted by varying tube length (28.3–56.6 mm), inclination angle (15°–75°), and diameter (5–15 mm). The results indicate that increasing tube length reduces air temperature at the tube exit and increases relative humidity by expanding the wetted surface area and increasing air residence time. Conversely, increasing the inclination angle or tube inner diameter enhances the mass flow rate through stronger buoyancy forces and larger cross-sectional areas. Although these factors reduce residence time, leading to higher air temperature and lower relative humidity at the tube exit, the significant rise in volumetric airflow effectively compensates for this, ultimately increasing evaporation rate and cooling capacity. The proposed model provides mechanistic insight and a predictive framework for optimizing passive evaporative cooling media for applications in building cooling and postharvest preservation of fresh fruits and vegetables.