etc.) is full of micro‐cavities, naturally present due to roughness, corrosion, etc. Therefore, air or vapor
trapped in those cavities serve as nucleation sites for the bubbles and ensure initiation of the boiling
process. The bottom line is that one needs to raise the temperature of the surface a little bit above
Tsat if boiling is to be initiated and sustained. For a rigorous derivation of Eq. 6 and more details about
bubble nucleation, refer to any boiling heat transfer textbook (e.g. Boiling, Condensation and Gas‐Liquid
Flow by P. B. Whalley, Oxford Science Publications, 1987).