Thermodynamic aspect of the shift of concave liquid–vapor interfacial phase equilibrium temperature and its effect on bubble formation

The thermodynamic analysis conducted here demonstrates that the capillary pressure discontinuity at the concave liquid–vapor interface could promote interfacial evaporation. The phase equilibrium temperature of the concave liquid interface decreases with increasing surface tension and/or decreasing radius of curvature of the concave liquid–vapor interface. The shift of phase equilibrium temperature and, hence, of latent heat implies that interfacial evaporation may even occur at a temperature lower than the nominated saturation temperature. According to these analytical results, bubbles can initiate from active cavities as long as the temperature of the liquid microlayer under the bubbles is higher than the phase equilibrium temperature, which may even be lower than the nominated saturation temperature. The conclusion is consistent with experimental observations about bubble formation.