Nuclear Heat Transport (NHT) MS Nuclear Engineering (3rd
Semester)
Nuclear Heat Transport (NHT)MS Nuclear Engineering (3rd
Semester)Dr. Kamran Rasheed QureshiBubble formation, growth and
detachment
Liquid agitation in boilingBubble growth and detachment from
cavity
Effect of heating surfacePool Boiling Curve
Regimes of pool boiling in water at atmospheric pressureNucleate
boiling regime
A lot of research has been conducted to establish a correlation
for heat flux and temperature difference.
One of the first and more widely used is Rosenhow
correlation
Where Csf = constant for a particular combination of liquid and
surface
Since appropriate value of Csf is often not known, more general
methods have been proposedPool boiling heat transfer regimesMost
useful among them are correlations of Stephan and Abdelsalam, and
Cooper. Stephan and Abdelsalam correlation
Valid for the range 10-4 p/pc 0.97, dd is the bubble diameter at
departure given by
Pool boiling heat transfer regimes (contd)
Cooper correlation
The Cooper correlation applies to flat plates and horizontal
cylinders for values of constant A equal to 55 and 95 respectively
and for the following conditions.
Water, refrigerants, and organic fluids0.001 pR 0.92 M 200 = 1
micron if the surface condition is not known.
Pool boiling heat transfer regimes (contd)
Film boiling regimeDifferent correlations are used for various
geometries such as horizontal flat plates, horizontal cylinders and
vertical plates. For horizontal flat plate
Where
For horizontal cylinder, Bromley gave the following
expressionPool boiling heat transfer regimes (contd)
Limiting conditions on the boiling curve
Example (Construction of pool boiling curve)
Draw the pool boiling curve for saturated water at 100 oC.
Assume that boiling occurs on a flat horizontal surface with a
conical cavity radius 5 microns and a surface roughness of 1
microns.
