• Boiling occurs at the solid-liquid interface when the liquid is brought into contact with a surface at \(T_w\), above the saturation temperature of the liquid \(T_{\text{sat}}\). Boiling heat flux (\(q\)) is given by \[q = h(T_{w}-T_{\text{sat}}) = h\Delta T_{\text{excess}}\]

  • Boiling is the transition from liquid to vapor via formation (or nucleation) of bubbles. It typically requires heat addition. The heat required to vaporize a unit mass of liquid is latent heat of vaporization.

  • Conventionally, based on the relative bulk motion of the body of a liquid to the heating surface, the boiling is divided into two categories:

    • pool boiling, and

    • convective or flow boiling

  • In addition to the regular variables of importance, surface tension (\(\sigma\)) of liquid with its vapor also play an important role in boiling.