NCSX VACUUM VESSEL HEATING/COOLING

PL Goranson

Preliminary Results February 17, 2006

MDL Testing of Coolant Tracing

NCSX

NCSXTalk Overview

P. Goranson• GOALS• TEST SUMMARIES• TEST RESULTS

K. Freudenberg• ANALYSES • ANALYSES/TEST COMPARISONS

P. Goranson• CONCLUSIONS/RECOMMENDATIONS/STATUS

NCSXGOALS

• Compare thermal performance of smooth tube vs. braided corrugated hose.

• Benchmark ANSYS analyses.• Project the test results across to VV cooling performance.• Determine baseline design for VV heating/cooling tracing

configuration.• Evaluate alternative conductive materials (thermal caulk).• Measure pressure drop in braided hose.• Test effectiveness of Copper ground strap (doily)

NCSXMDL TEST SETUP

NCSXTEST ASSY

• Utilized existing MDL resources– Oven– Thermocouple controllers– Braided hose– Building compressed air for cooling

• Setup geometry was not meant to be completely duplicate VV system. A helium source was not available nor was very high pressure air.

- Curved SS plate represented VVNSTX center stack mockup with studs

- Cu saddles were fabricated to correct geometry- Hose was prototypic

• Smooth tubing test used Cu tube with SS insert to represent tube wall

- permitted using same saddles and at same time duplicating hose flow parameters (h, v)- large SS tube overloaded building capacity

Test Assembly With Braided Hosess

Tube Assy

Saddle

Tube

Gasket

NCSXAIR FLOW/PRESSURE/TEMP MONITORING

NCSXTEST COMPONENTS

• Saddles– Cu precision fit to hose & tubing insert

• Saddle Gaskets– 1/16” Grafoil– 0.005” Cu shim

• Tube and Hose gaskets– 0.005” Cu shim– 0.01” Grafoil

• Clamps1/8” x 1” steel to permit large clamping force

NCSXTEST PROCEDURE

• Test assembly was covered in insulation and heated to test temperature by the oven.

• When assy temperature equilibrated, oven was turned off; door remained closed.

• Temperature of thermocouple at varying positions around saddles were recorded in 2 minute intervals, for 30 minutes total.

• Air flow (scfm), temperature, inlet pressure, and outlet pressure across test section were monitored.

• Tests were performed using different combinations of gasket materials under the saddles and under the tubing inserts.

Straight tube Approximation TC LocationsNCSX

NCSXTEST RESULTS

TC1 Cooling Time as function of Hose Configuration

60

70

80

90

100

110

120

130

140

150

0 5 10 15 20 25 30 35

Time (min)

Tem

per

atu

re (

F)

braided with bothGrafoil

smooth, Grafoil gasket

braided, Cu gasket

smooth withboth Grafoil

braided, Grafoil gasketsmooth, Cu gasket

Braided hose does cool.

NCSXGround Strap (doily)

Results of the test were disappointing.

• Test performed with 0.04” x 1” x 6” Cu strap wrapped and clamped to hose with Grafoil.

• Other end bolted down by stud, washer, and Grafoil gasket.

• Results- temperature drop after 15 minutes – 6.5 C- temperature drop after 30 minutes – 13 C

NCSXFACS

• Un-cooled plate temperature fell less than 2 degrees C in 30 minutes, none in 15 minutes. Cooled plate dropped by as much as 24 C in 15 minutes.

• Cu foil under the braided hose decreased performance.

• Grafoil under the braided hose increased performance.

• Grafoil under the smooth tube improved performance.

• Grafoil under the saddle improved braided both hose and smooth tube performance.

• Grafoil was required under both the saddle and the tube insert to attain the theoretical cool down time of the smooth tube.

• Pressure drop in braided hose is ~6 times the equivalent smooth tube with same I.D.,At these flow regimes, twice the manufacturer’s estimate.

NCSXCONCLUSIONS

Where we are headed:• Braided hose does not perform as well as smooth tube but is good enough.

We propose to go with it.• Neither tubing nor hose is proving to be as effective as previously predicted.

Braided hose is:more cost effective (more studs cost a lot less than segmented hose)easier to installquicker procurement timemore suppliersprobably more reliable

• The VV will require twice the number of studs and saddles, and a redistribution of some of the tracing, regardless of whether or not the tracing is tubesor hose.

• Presently, the only alternative to hose is segmented hose made up of short braided sections intervened with shot straight tube sections, essentially a lot of braided hoses with end fittings welded together.

• None of the thermal caulks tested has proven to be advantageous.Only one, Pyro-Putty 950, adhered and exhibited structural integrity through bakeout; unfortunately its conductivity was 7.4 time worse than saddles.

NCSXDesign Changes

• Simplified saddle assySaddle is two pieces rather than oneReduces machiningAssures good alignment and clamping

• Two clamps rather than onePermits spacing tubes further apart in some locationsOne saddle cools almost as well as two so wider spacing can be more effective

WAS NOW

0.47 DIA1/16

5/16 STUD.062

Gasket omitted for clarity

1.25

Ø.375

2.75

STUD LOCATION INDICATED WITH 1INCH RADIUS BALLS

STUD LOCATION

THE RIGHT HAND SIDE REPRESENTS A 5 INCH SPACING BETWEEN STUD LOCATIONS

THE LEFT HAND SIDE IS THE ORIGINAL SPACING . THE SPACING VARIES FROM A NOMINAL OF 8 INCHES +/- 2 INCHES.

THE TOTAL NO. OF STUD LOCATIONS ON THE RIGHT HAND SIDE IS ~ 356 FOR A HALF PERIOD

THE TOTAL NO. OF STUD LOCATIONS ON THE LEFT HAND SIDE IS ~ 226 FOR A HALF PERIOD

THE STUD LOCATIONS HAVE NOT BEEN OPTIMIZED RELATIVE TO THE MAGNETIC LOOPS.

TOP VIEW

STUD LOCATIONS ON THE FRONT AND BACK SIDE

5 INCH SPACING BETWEEN STUDS

NOMINAL 8 INCH SPACING +/- 2

INCHES5 INCH SPACING BETWEEN STUDS

Outboard viewInboard view

STUD LOCATIONS ON THE FRONT AND BACK SIDE

NOMINAL 8 INCH SPACING +/- 2

INCHES

5 INCH SPACING BETWEEN STUDS

Inboard view

HEATING/COOLING CLAMP ASSY

GRAFFOIL

2.5X1.25X.06

COPPER

1.0X1.25X.333

GRAFFOIL

.01 THICK

STUD

5/16ODX3/4LG

WASHER

NUT

HEATING/COOLING TUBE

.48OD

CLAMP