Page 227 - Thermal Hydraulics Aspects of Liquid Metal Cooled Nuclear Reactors

198 Thermal Hydraulics Aspects of Liquid Metal Cooled Nuclear Reactors

25
20
Nusselt number (–) 15

10
5

Kirillov
Ibragimov
0 Skupinski Sleicher
Cheng
–5
0 1000 2000 3000 4000
Peclet number (–)
Fig. 5.8 Comparison of different HT correlations.

with

4:5 Pe 1000
8
>
<
4
A ¼ 5:4 9 10 Pe 1000 Pe 2000 (5.29)
>
:
3:6 Pe 2000
for liquid-metal flow in tubes and equations
Nu ¼ a + b Pe 0:86 (5.30)

with

2
P P
a ¼ 6:66 + 3:126 +1:184 (5.31)
D D
8
0:0109, Pe 2000
>
<
0:86
b ¼ 0:0155= 2:5 0:0005 PeÞ ,2000 Pe 3000 (5.32)
ð
>
:
0:0155, Pe 3000
for liquid-metal flow in rod bundles.
5.2.2.3 Transversal exchange
For the transversal exchange in fuel assemblies with liquid-metal flow, five different
mechanisms are identified, three in the group “undirected flow fluctuation” and two in
the group “directed cross flow,” as summarized in Table 5.2.