Question

The temperature of the liquid is below the saturation temperature and boiling takes place only in vicinity of the heated surface. This type of boiling is known as:

• A. Subcooled
• B. Forces
• C. Saturated
• D. Pool

Hint:

When boiling occurs even though the bulk liquid is below saturation temperature, and is confined to the heated surface region, it is known as subcooled boiling.

Answer 1

The Correct Option is A

Boiling can be classified into different types based on the temperature of the liquid and where the phase change occurs.
In this case, the key detail is that the temperature of the liquid is below the saturation temperature, yet boiling occurs in the vicinity of the heated surface.
This phenomenon is characteristic of subcooled boiling, also known as local boiling.
Here's how it works:
- In subcooled boiling, the bulk of the liquid remains at a temperature below saturation.
- However, the temperature near the heated surface can be high enough to cause localized vapor bubble formation.
- These bubbles often collapse quickly as they move into the cooler bulk fluid.
- Subcooled boiling is typically observed in high-heat flux systems where the surface gets significantly hotter than the fluid.
Incorrect options analysis:
- Forces: Not a recognized classification of boiling.
- Saturated boiling: Occurs when the entire liquid is at saturation temperature — not applicable here.
- Pool boiling: Refers to boiling in a stagnant liquid — but doesn't specify the temperature condition relevant here.
Therefore, the correct answer is clearly: Subcooled.