What is departure from nucleate boiling?
What is departure from nucleate boiling?
The point at which the heat transfer from a fuel rod rapidly decreases due to the insulating effect of a steam blanket that forms on the rod surface when the temperature continues to increase.
What happens in the nucleate boiling?
Nucleate boiling A condition in which bubbles of steam nucleate at points on a metal surface and minute concentrations of solids develop at the interface of the bubbles and water. Oil-ash corrosion A liquid phase corrosion phenomenon where metal temperatures are in the range of 593–816°C.
What is meant by nucleate and film boiling?
Nucleate boiling is a type of boiling which occurs when the surface temperature is hotter than the saturated fluid temperature by a certain amount. In this type of boiling, the heat flux is below the critical heat flux.
What is the onset of nucleate boiling?
Onset of Nucleate Boiling (ONB) is defined as the first location on the heated surface where a bubble can exist. If the bubble detaches from the surface while the average bulk temperature remains below the saturation value, this phenomenon is called subcooled boiling.
What is meant by film boiling?
In film boiling, a continuous vapor film blankets the heater surface which prevents direct contact of liquid with the surface. Vapor is generated at the interface between the vapor film and the overlying liquid pool by conduction through the vapor film and thermal radiation across the vapor film from the hot surface.
Which of the following factors affect nucleate pool boiling?
It depends on pressure, material and liquid properties. It depends on pressure, material and liquid properties.
What happens in transition boiling?
Transition boiling is an intermediate, unstable form of boiling with elements of both types. The boiling point of water is 100 °C or 212 °F but is lower with the decreased atmospheric pressure found at higher altitudes.
What is a nucleate?
Definition of nucleate transitive verb. 1 : to form into a nucleus : cluster. 2 : to act as a nucleus for. 3 : to supply nuclei to.
How do you stop film boiling?
To prevent film boiling incipience, a microporous coating is applied over the smooth surface, which decreases incipient wall superheat and increases minimum heat flux.
What is the film boiling?
Film boiling occurs when the pressure of a system drops or the flow decreases. In this case, the bubbles cannot escape as quickly from the heat transfer surface. Likewise, if the temperature of the heat transfer surface is increased, more bubbles are created.