ORNL-2106 - the Molten Salt Energy Technologies Web Site

4.1. HEAT TRANSFER AND PHYSICAL PROPERTIES
ART FUEL-TO-NoK HEAT EXCHANGER
S. 1. Cohen J. L. Wantland
The ART fuel-to-NaK heat exchanger test system1
was modified for further studies of heat transfer
and friction characteristics. Six 60-deg staggered
spacers and six &de9 inclined spacers were
placed alternately on the tube bundle, and trans-
verse pressure taps were installed across one
spacer of each type. The average transverse
pressure drop across each instrumented spacer
was plotted in terms of the ratio of the transverse
pressure drop to the velocity head times the fluid
density over the Reynolds modulus range of 3000
to 8000. For the inclined spacer this term varied
from 1.4 to 1.1, and for the staggered spacer the
data fell randomly between 0.01 and 0.03, with no
definite trend established. The analytical investi-
gation, referred to previously,2 on a method of
correlating fluid-friction data for flow parallel
to a square array of cylindrical tubes in rectangular
cross-section flow channels was ~ompleted.~
An experimental study is being made of the
fuel-side fluid-friction characteristics 6f a mockup
of the present design of the ART fuel-to-NaK
heat exchanger. The dimensions of this apparatus
and the spacer configuratibn will simulate the
ART heat exchanger as nearly as possible, except
that there will be no headers and the tube bundle
will not have the curvature specified for the
ART; that is, the friction characteristics for a
straight length of tube bundle will be determined.
An experimental heat exchanger has been de-
signed and is now being fabricated that will be
similar to the one on which tests were conducted
previously,' with the exception that the tubes will
be spaced on a triangular array rather than a
Friction Data /or Tube Bundles of
and Tube Bundle to Shell Wall Spacing,
ORNL CF-M-4-162 (April 5, 1956).
'J. L. Wantland, Thennnl Cbnracieristics of the ART
Fuel-to-NaK Heat Exchanger, ORNL CF-55-12-120
(Dec. 22, 1955).
H. F. Poppendiek
data for direct comparison of the heat-transfer
and fluid-friction characteristics of the two differ-
ent configurations in the transitional Reynolds
modulus range.
ART HYDRODYNAMICS
C. M. Copenhover F. E. Lynch
G. L. MullerS
Sodium Flow in Reflector Cooling Sysfem
A 5/22-scale model of the reflector-core shell
cooling annulus and inlet system was designed and
fabricated (Fig. 4.1.1) in order to determine quanti-
tatively the flow distribution in the annulus and
the various pressure drops in the sodium system.
The fluid used in the model was water at temper-
atures between 20 and SOOC. Although the model
does not incorporate the reflector cooling holes,
12 nozzles were spaced radially around the inlet
header to take off fluid at various sectors of the
inlet header to mock up flow through the cooling
holes.
The flow distribution was studied by three
methods: (1) the static pressure measured axially
across the annulus in conjunction with the total
annulus flow rate measured by a rotameter gave
the average velocities through the annulus for the
two positions nearest the inlets and the two
positions farthest away, (2) Pitot-static combi-
nation measurements were obtained at positions
1-3 and 3-3 (Fig. 4.1.1), and (3) high-speed motion
pictures were made of periodic ink injections.
A quantitative measurement of the flow distri-
bution was defined as
on v1 + v3
where
Qj = volumetric flow rate in annulus farthest
from inlet,
Qn = volumetric flow rate in annulus nearest to
inlet,
. V = average linear velocity at station indicated
by subscript number.
'On assignment from Pratt 8 Whitney Aircraft.
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