Evaporation Behaviour of a Pair of Sessile Droplets on a Heated Substrate

The evaporation of water droplets is important for a wide range of industrial applications, including inkjet printing and DNA mapping; Here, we present an experimental investigation which addresses the evaporation characteristics of a pair of sessile droplets on a heated aluminum substrate.

Experiments were conducted to monitor the changes in contact angle and surface temperature of pairs of droplets during evaporation for different substrate temperatures. The temperature distributions over the droplet surfaces were visualized using an infrared camera. Also, it aims to study the effect of the high vapour concentration wedge area, formulated between the droplets when they come close to each other, on evaporation behaviour.

The results demonstrated a relationship between the droplet separation distance and the uniformity of temperature distribution of their surfaces. We further determined a critical separation distance beyond which the temperature distributions were relatively uniform. This threshold separating distance proves that the effect of the wedge area formulated between the droplets is less, and the droplets behave as if they are isolated single ones. In addition, the substrate's temperature significantly affects the initial contact angle of the droplets, in which increasing the substrate temperature decreases the contact angle of the droplet. The evaporation process can be optimized with the help of this knowledge, leading to higher control and consistency in industrial applications.

These findings positively enhance numerous industrial applications, resulting in improved performance in fields where evaporation is crucial.