Analysis and modeling of paired droplet evaporation on heated substrates considering vapor-shielding and natural convection effects

Document Type

Article

Publication Date

11-1-2025

Abstract

This study investigates the evaporation characteristics of paired droplets on heated substrates, focusing on the effects of droplet spacing and substrate temperature. Paired deionized (DI) water droplets are deposited on a copper substrate using a multi-syringe pump, and their evaporation dynamics are analyzed through shadowgraph imaging and OpenCV-based image processing. The results show that the contact line remains pinned for approximately 90 % of the total evaporation time before depinning occurs, regardless of droplet spacing and substrate temperature. It is also found that the vapor-shielding effect decreases with increasing droplet spacing and substrate temperature due to enhanced natural convection, causing the evaporation time of paired droplets to converge toward that of a single droplet. Moreover, the results indicate that droplet spacing significantly affects the evaporation time than substrate temperature. A Rayleigh number-based model is suggested to predict the evaporation rate by combining the diffusion and natural convection effects, showing good agreement with the experimental data with a maximum relative error of less than 5 %.

Publication Title

International Communications in Heat and Mass Transfer

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