Lens Evaporation on Immiscible Liquid Surface with an Interfacial Cooling Effect

Area of Science:

• Heat and Mass Transfer
• Fluid Dynamics
• Surface Science

Background:

• Evaporation of liquid lenses on immiscible substrates is crucial in various industrial applications.
• Previous models often simplified heat and mass transfer dynamics, limiting predictive accuracy.
• Understanding the interplay of thermal and concentration gradients is key to controlling evaporation rates.

Purpose of the Study:

• To develop a theoretical heat and mass transfer model for volatile liquid lens evaporation on immiscible liquid substrates.
• To derive the first analytical solutions for the temperature and vapor concentration fields.
• To investigate the influence of various parameters on the evaporation process.

Main Methods:

• Establishment of a theoretical model in toroidal coordinates.
• Incorporation of coupled boundary conditions for heat and mass transfer.
• Derivation of analytical solutions for temperature and vapor concentration fields.
• Comparison of model predictions with experimental data.

Main Results:

• The model accurately predicts changes in contact radius, especially at higher substrate temperatures.
• Non-uniform temperature distribution within the liquid lens was observed, similar to sessile droplet evaporation.
• Excess temperature, heat flux, and evaporation flux increase from the lens center to the contact line.
• Lens mass evaporation rate decreases with increasing density ratio and evaporative cooling number (E0).

Conclusions:

• The developed theoretical model provides accurate predictions for liquid lens evaporation on immiscible substrates.
• Interfacial cooling effects and non-uniform temperature distributions significantly influence evaporation dynamics.
• Density ratio and evaporative cooling number are critical parameters for controlling evaporation rates.