Evaporative self-assembly of soft colloidal monolayers: The role of particle softness on microstructure

We investigate the sessile drop evaporation aided self-assembly of microgel particles by varying their softness. Evaporation of sessile drops containing amphiphilic microgel particles at suitable concentrations results in uniform monolayer...

Leidenfrost Phenomenon and its Impact on Sessile Drop Evaporation for Different Liquids and Surfaces

Recent study of the applications of the Leidenfrost effect has sparked renewed interest in this phenomenon. Due to Leidenfrost effect, a droplet can be levitated by its own vapor layer on a sufficiently heated surface. In this work an experimental investigation has been performed to determine the Leidenfrost point (LFP) of different liquids on different surfaces. Copper, aluminum and brass plates were used with water, methanol, and ethanol as different liquids to study the variation of LFP. The experiment was conducted with incident droplets of water, methanol, and ethanol on the three different metal blocks which were heated by cartridge heaters. The input powers in the heaters were varied by a voltage variac. At each temperature, droplet evaporation time was recorded where the highest evaporation time corresponded with the LFP. For the ranges of parameters considered in this study, the Leidenfrost temperature for water varied from 180°C to 200°C. For organic fluids like methanol it varied from 160°C to 200°C while for ethanol it varied from 160°C to 200°C. These findings are important because accurate modeling of Leidenfrost phenomenon is crucial for the design of many cooling devices. If a vapor layer is present between the liquid and the surface to be cooled, then the cooling becomes inefficient. This is especially important for the rapid cooling of overheated components in high power density systems, such as nuclear reactors and other devices.