ORNL-1771 - Oak Ridge National Laboratory

ANP QUARTERLY PROGRESS REPORT
Burner
TABLE 3.2. EXPLORATORY TESTS OF GAS BURNERS
ORNL 2.1 (max) 170
Furnace
Gas Rate Rate of Heat Temperature*
(cfm) Release* (Btu/sec.ft 1
(OF)
Fisher, laboratory type 3.5 160
Remarks
2000 Flame did not fill
combustion space on
which rate was based
Rate based on esti-
mated flame dimensions
National N-4 1.2 20 Maximum attainable
Two-in. pipe with let 1.3 20 2900
*These values are the highest that were attained in the test but do not necessarily represent the maximum volues
attainable, except where indicated.
on the cavitation phenomenon in forced-circulation
high-temperature sodium systems, a preliminary
study was initiated,
Tests were run on the ARE hot pump test facility
in which pressures at the venturi throat could be
varied by varying the pressure of the blanketing
gas. Thus it was possible to vary the pressures
without changing the pump speed, the throttle
valve setting, or the temperature. Data were taken
during eight runs at temperatures in the range
1200 to 1500’F. Measurements were made of pump
discharge pressure, venturi throat pressure, and
pump suction pressure as the pump suction pres-
sure was varied. Cavitation was found to begin
when the venturi throat pressure ceased to decrease
uniformly with decreasing pump suction pressure.
Also, as cavitation began, the loop pressure drop
increased and the flow rate decreased. Observation
of fluid flow noise revealed a correlation of noise
intensity with pressure data.
The pressure at which cavitation occurred cannot
be exactly ascertained, since the pressure at the
middle of the throat of the venturi is obviously
not the lowest pressure in the venturi. In water
cavitation, bubbles form at the start of the flow
expansion, and, in the particular venturi used, the
rather sharp radius at the transition from the throat
to the diffusion cone probably caused flow sepa-
ration. The minimum pressures observed at the
throat were within 1 psi of the vapor pressure of
sodium.
42
Instrumentation for measurement of subatmos-
pheric pressures was required for these high-
temperature (up to 1500°F) sodium-cavitation
studies. A Moore nul I-balance bel lows-type pres-
sure transmitter and a Moore Model 60-N “nullmaticf’
pilot valve modified to vent the pilot volve to a
vacuum source proved to be satisfactory for this
application. When the venting atmosphere or sink
pressure is reduced, the unit is capable of meas-
uring correspondingly lower process pressures.
Pressure measurements were made over the range
of 20 to 1.6 psia, with the sodium-filled transmitter
maintained at about 65OOF. The zero shift of the
pressure transmitter ranged from 4.3 to -0.2 in.
tig over the range.
A second check of the zero shift was made as
the transmitter temperature was varied from 800 to
470’F with a constant system pressure of approxi-
mately 16.2 psiu. The zero shift then observed was
+0.1 to -0.2 in. tig. In general, the performance
of this pressure-measuring device was quite sotis-
factory; a more highly refined application of this
device might lead PO even smaller zero shift. A
report covering this modification is being prepared.
EXPANSION AND IMPROVEMENT Of THERMAL-
CONVECTION LOOP TESTING FAClLlTlES
E. M. Lees
Aircraft Reactor Engineering Division
The number of power panels installed for sup-
plying thermal-convection loops has been expanded