Examples for Pressure Drop Calculations in Parallel Flow Helium Cooling Page: 3
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or a friction loos of 0.27% of the host transported. To this cause bo added
& for each exit cf ti e hot c«- Honor, if wo have two pli<s in series, we
lose u.5 r 0.27 ■ 0.77% in the plug. To thia add the friction Ices in tho
duct and at the hot exit frees tho duct. If the duct is twice the critical**
Is, the -ctal friction loss for the duet and exit la 0.78%, giving about
grand total, or, for 3QC.OOO kw, a loss of 4,600 kw. By reducing the
velocity in the duct and at the duct exit by a factor cf /T we reduce the
duct fraction loss to U.7S/3 a 0.25, giving a total loco of about 1%, or for
a SOu.OQC kw machine, a loss of 3,000 kw.
1.1
-I.
tower Output.
Wo will now calculate tho heat transfer. using heliiso at It stsnos. hares
pressure with a velocity Oc.ua 1 to 1/2 tho critical velocity or 8.86 x IQ3 ee^oec.
1). The Uranium lisa, «• plug oonslste of U.6 am al an etar cylindrical
sticks, 4.5 cm long, pxclcad so as to have 3p 4 of tho cross section saotal and
i empty space, he cool two sweh plugs ir. series (at tho center cl the pile) la
order to get a twnpcra.uro rise ot 5UOC la the gas. This corresponds to a
heat production of 210 calories per double stiokj and, sinoo * t*wky weigh
60.® g, to a production of 17.3 watts/g at tho center oT the pile, or 4.32
aatts/g average. For 40 tons of natal this gives a total production of
173,OOC kw.
Z). We cooreaso tho uianeter of the sticks to 0.3 os, hydraulic radius
0.06 or. This glees h * 4.73 x IO"** »/~—2/or—--------------. —
cool single plugs of length 4 oat at the center of th* pile.
o«lcrlM/<a»Z/t’C/**«. end requires us to
_ j Fear tJi i • t, • ■ ... ® of*
plug we twee, at the cont er or the pile a production of 39 wutts/g, or for 40
tons, a total production of 390.OOC kw. The friction lore in this case .s
1.28% of t he host transf wt.
tons, a total production of 390,COC Jew. ‘uw crew
0-26 *0.27 s Q.52% per plug plus 0.78% per duct •
Thia gives the frictional work equal to 4870 kw.
3£_*T_r^yC* y*® SOO.OOO kw (by reducing the velocity
■< ■—i,.1 —- . However,
If we increase the pencil length in the
3). 7‘ ‘ _ _____2w____________________
cf the c**>. -*• friction loss drops by the square of the velocity,
the heat transfer dro^s nor# slowly. . ___ #_______
plug slightly, so that ZiT rennins 3O0°C. tber., for a 300*000 kw smMm the
<870*1.6®, or 2880 kw. For 1/2 tho critical velocity.
*; area. The friction loss in tho
aroe to go up to about 12 percent.
* > - 6.8. * IO3 cc/soo.
friction rork equals 4870*1.6®, or 2880 kw- J
300.OOC kw output requires about 9 percent duet
ducts can be node smiler if we allow tho duct <
correspooclag to tho new velocity of 8.86 x 10s
6.8. * IO3 asS—a.
111. Effect of reducing pressure.
If the auota are unchanged and wo keep the assoc exit velocity
cropping ths pressure », l-v-st aS ^.a .
fee -C; of 1
rv
’ JI
• ■ ’ ’ ’ ________________________________________________________________
is squat to Ute Kinetic energy ci tho gd*-
***Tha hydraulic radius is a Measure of tho effective radius of tho empty epece
for beat transfer snu pressure loss. — - - —
tho space through which tho gas flows.
1 :^th Is wblah t’.e frictlunsl loss In Ou. -ubo
tho gua -
It Is defined a* 2
x area/periphory of
3 0 ~----— 9 twHort p
i
i
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F: F C i M S i F
• • #•• ••• o o ee •• e e
... "7" ~?
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Feld, Bernard T. (Bernard Taub), 1919-1993 & Szilard, Leo. Examples for Pressure Drop Calculations in Parallel Flow Helium Cooling, report, June 18, 1942; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc1256455/m1/3/: accessed July 16, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.