Which region is the second region of the pool boiling curve?

Which region is the second region of the pool boiling curve?

• A. Natural Convection
• B. Nucleate Boiling
• C. Transition Boiling
• D. Film Boiling

Answer: (B)

In pool boiling, the heat-transfer regime advances as the surface temperature rises above the liquid’s saturation temperature. The second region is nucleate boiling, where numerous vapor bubbles form at active nucleation sites on the heated surface and detach into the liquid. This bubbling dramatically increases heat transfer because each bubble carries away latent heat and the surrounding liquid is replenished, keeping the surface close to the saturation temperature while cooling it efficiently. As heating continues, bubbles become less stable and dry patches can form, leading into transition boiling, and at still higher superheats a continuous vapor film forms for film boiling.

In pool boiling, the heat-transfer regime advances as the surface temperature rises above the liquid’s saturation temperature. The second region is nucleate boiling, where numerous vapor bubbles form at active nucleation sites on the heated surface and detach into the liquid. This bubbling dramatically increases heat transfer because each bubble carries away latent heat and the surrounding liquid is replenished, keeping the surface close to the saturation temperature while cooling it efficiently. As heating continues, bubbles become less stable and dry patches can form, leading into transition boiling, and at still higher superheats a continuous vapor film forms for film boiling.