The conditions for boiling are that the temperature must reach the boiling point; it requires constant absorption of heat; and it is characterized by constant absorption of heat and constant temperature.

Explanation:

Boiling is the phenomenon of violent vaporization that occurs both inside and at the surface of a liquid when the liquid is heated above its saturation temperature. Different liquids have different boiling points. Even the same liquid, its boiling point should be changed with the change of the external atmospheric pressure. At the same time, the term has been derived to mean many different things, the most common being an expression of excitement and thrill in a crowd.

Physical explanation:

All kinds of liquids boil at a definite temperature called the boiling point. Different liquids have different boiling points. Even for the same liquid, its boiling point varies with the outside air pressure: the higher the atmospheric pressure, the higher the boiling point of the liquid, and vice versa.

A standard atmospheric pressure of water boiling point of 100 ℃, which is the most common. At a given external pressure, boiling can only take place at a specific temperature (boiling point) and under constant heat. When a liquid boils, the temperature remains constant and heat is still absorbed. The saturation vapor pressure is then equal to the external pressure P. When the external pressure on a liquid increases, its boiling point increases; the opposite is true.

Classification of boiling:

1. Nuclear

Boiling of water on a kitchen stove. Nuclear boiling is characterized by the growth of bubbles or air bubbles on a heated surface, which rise from a discrete point on the surface at a temperature only slightly above that of the liquid. Typically, the number of nucleation sites is increased by the increased surface temperature.

Irregular surfaces (i.e., increased surface roughness) or fluid additives (i.e., surfactants and/or nanoparticles) of the boiling vessel can produce additional nucleation sites, while particularly smooth surfaces, such as plastics, are suitable for superheating. Under these conditions, the heated fluid may show a delay in boiling, and the temperature may be slightly above the boiling point without boiling.

2. Critical heat flux

When a boiling surface is heated above a critical temperature, a film of vapor forms on the surface. Because this vapor film is able to carry heat away from the surface, the temperature rises very quickly above this point to the transition boiling state. The point at which this occurs depends on the properties of the boiling fluid and the heated surface being discussed.