An Experimental and Theoretical £ Investigation of Annular Steam ...

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through a heat exchanger, where a subcooling takes place.
The secondary cooling fl.w through the heat exchanger is
measured by one of two flowmeters. The primary flow, the total
suction rate, is measured by one of three flowmeters (venturi
or orifice) and one of -hree dp-cells. The measuring range is
from 10 g/s to 350 g/s with an accuracy of • 1.5%.
After the total suction rate is measured, the primary flow
is returned to the regenerator, where it is reheated. Finally,
it is returned to the main system through the ejector pump at
VI on fig. 3.1.
From the measured flow rates and temperatures T 2 to T,_,
the film flow rate can be determined as described in sect.
3.2.2.
When the film flow rates on the rod and tube wall in the
annular test section are determined, two heat balance units are
used. However, the measurements were not carried out simultaneously
because the opposite film might be disturbed.
3.1.3. Test Sections
The following test sections were used during the experimental
periods (cf. table 3.2):
where
Period 1: Annular test section 17/26S
dj = 0.017 m, d 2 = 0.026 m, 1 = 3.5 m
Periods 2-4: Tubular test .section 10
d_ = 0.010 m, 1 = 9.0 m
Period 5: Annular test section 17/26L
d. = 0.017 m, d_ = 0.026 m, 1 = 8.0 m
Period 6: Tubular test section 20
d_ = 0.020 m, 1 = 9.0 m
d, (m) is the outer diameter of the rod
d- (ni) is the inner diameter of the tube
1 (in) is the length of the test section
In the adiabatic experiments (periods 2, 5 and 6) the experimental
set-up consisted in addition to the test section, of a
steam generator placed between the flowmeter and the inlet
flange at the test section.
The steam generator is electrically heated as a resistance
element. It consists of nine tubes (d 2 = 0.0063 m, 1 = 4.0 m)