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NEEP 411: HW#7
Single Phase Heat Transfer; Heat Transfer with Change in Phase
Due:
Friday, November 11
th
, 2011
1.
In our expression for natural circulation through a PWR, we had a frictional loss term
in the denominator of our dimensionless flow/power expression:
The term in [] is a frictional loss term, which we took as 10
×
the cold leg frictional
loss.
The purpose of this first problem is to evaluate that term a bit more rigorously.
Suppose we consider the frictional loss around the loop as having these components:
(a) The frictional loss in the cold leg as calculated in class
(b) The frictional loss in the hot leg (same pipe diameter and length as the cold leg)
(c) The frictional loss in the annular gap of the downcomer.
Take the flow area based
on a 20 cm thick annulus with inner radius 1.85 m and outer radius 2.05 m.
Take
the height of the downcomer as 4 m.
Note that all 18,000 kg/s passes through the
downcomer.
(d) The frictional loss in the assembly region. Take the average assembly geometry

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