IGCAR : Annual Report - Indira Gandhi Centre for Atomic Research

IGC
Annual Report 2007
Hot Pool Sodium Inlet
Intermediate Sodium
Inlet
Outlet
distributions of intermediate
sodium in the tubes and
primary sodium on the shell
side have been solved as a
conjugate problem, using the
CFD code STAR-CD.
Baffle
Hot Pool Sodium Outlet
Hot Pool
Fig.2 Computational model
Outlet
Inlet
inner rows of tubes from the the present study.
top, picks up heat from the
primary sodium and leaves
from the outer rows at the top.
Primary sodium in the hot pool
In the present investigations,
a 3-D 60° sector model of DHX
comprising of 15 tubes and hot
enters the DHX in radial pool has been considered (Fig.
direction through a perforated
outer shell, exchanges heat with
the intermediate sodium, gets
cooled and leaves back to the
2). The intermediate sodium
flow rate (32 kg/s) and its inlet
temperature (539 K) to DHX
have been estimated from a
pool through the bottom coupled 1-D model of the
window. To enable connectivity
between the 5 inner rows and 2
outer rows through U bends,
entire circuit. The resistances
offered by fine scale structures
viz. the porous shell, antivibration
the lengths of U-tubes are
plates etc. are
made unequal. Also, the tubes accounted by additional
see varying primary sodium sources added to the
temperature. Due to these momentum equations. High
reasons, there is a risk of flow Reynolds number k-∈
reversal in some tubes. The
flow reversal adversely affects
turbulence model has been
used for modeling turbulence.
the heat removal capacity of About 4 lakhs structured
the SGDHRS and hence, it is
essential to investigate the
possibility of flow reversal in the
hexahedral mesh have been
used for the computational
fluid dynamic (CFD) simulation.
tubes, which is the objective of The flow and temperature
The temperature of primary
and intermediate sodium in the
DHX at various elevations is
depicted in Fig. 3. The antivibration
plates cover the inner
leg of U-tubes and hence it
divert the primary sodium from
the inner leg to the outer leg,
thereby increasing the heat
transfer in the outer leg. The
intermediate sodium
temperature distribution along
the length of the tube centerline
for all the 15 tubes is shown in
the Fig. 4. The mean
temperature of the intermediate
sodium at the outlet is 723 K.
In the co-current direction (i.e.,
inner leg), the heat absorbed is
the least by the inner-most row
(i.e. Tube-1) and it increases as
one moves outwards. It is the
maximum in Row-5 (Tubes 11-
15). At the bottom end, the
maximum temperature
difference is 71 K. This large
difference in temperature is
compensated in the countercurrent
direction (outer leg),
leading to a marginal
temperature difference of 17 K
at intermediate sodium outlet.
This is due to the favorable
(larger) driving temperature
gradient between the
34 R&D FOR FBRs