Update: HEMJ Experiments in the GT Helium Loop
description
Transcript of Update: HEMJ Experiments in the GT Helium Loop
![Page 1: Update: HEMJ Experiments in the GT Helium Loop](https://reader035.fdocuments.us/reader035/viewer/2022062323/5681555d550346895dc3260e/html5/thumbnails/1.jpg)
Update: HEMJ Experiments in the
GT Helium Loop
M. Yoda, S. I. Abdel-Khalik, D. L. Sadowski, B. H. MillsSeptember 18, 2013
![Page 2: Update: HEMJ Experiments in the GT Helium Loop](https://reader035.fdocuments.us/reader035/viewer/2022062323/5681555d550346895dc3260e/html5/thumbnails/2.jpg)
Objectives •Evaluate thermal performance of leading helium-cooled divertor designs at prototypical conditions •Determine design correlations from experimental data at near-prototypical conditions and numerical simulations•Use correlations to estimate how changes in operating conditions affect divertor thermal performanceCurrent Approach•Test a single helium-cooled divertor with multi-jet cooling (HEMJ) module in helium loop at prototypical pressures, near-prototypical temperatures •Estimate maximum heat flux and He pumping power requirements from cooled surface temperature and pressure drop data
Gas-Cooled Divertors
ARIES Mtg. (9/13) 2
![Page 3: Update: HEMJ Experiments in the GT Helium Loop](https://reader035.fdocuments.us/reader035/viewer/2022062323/5681555d550346895dc3260e/html5/thumbnails/3.jpg)
HEMJ Design
ARIES Mtg. (9/13) 3
W-alloy
18 mmW Tile
Steel
15 mm
18 mm
• Divertor design proposed for DEMO– Jet impingement cooling: He at 600 °C
(increased to 650-700 °C), 10 MPa exits from 25 (24 each 0.6 mm dia. + one 1.0 mm dia.) holes
– He mass flow rate 6.8 g/s
– KIT/Efremov experiments of 9-module unit at prototypical conditions show HEMJ can accommodate heat fluxes q > 10 MW/m2
– Cools very small area: need ~5105 modules to cool O(100 m2) divertor
m
![Page 4: Update: HEMJ Experiments in the GT Helium Loop](https://reader035.fdocuments.us/reader035/viewer/2022062323/5681555d550346895dc3260e/html5/thumbnails/4.jpg)
ARIES Mtg. (9/13) 4
Background• Previous work: Dynamically similar studies of various divertor
designs extrapolated to prototypical conditions– Study HEMJ, finger-type divertor with single impinging jet, He-cooled
flat-plate (HCFP) and T-tube divertors– Cool with air, He and Ar at near-ambient temperatures– Match coolant mass flow rate (Re) and fraction of heat removed by
convection, vs. conduction (Biot number Bi Nu / , where thermal
conductivity ratio ks / k)
– Determine correlations for Nusselt number Nu = f (Re, ) [neglecting
Prandtl number effects] and loss coefficient KL = g (Re)
• Test at near-prototypical conditions in helium test loop– 10 g/s, inlet temperature Ti 400 °C, inlet pressure pi 10 MPa
– Can accommodate test sections with pressure drops 0.7 MPam
![Page 5: Update: HEMJ Experiments in the GT Helium Loop](https://reader035.fdocuments.us/reader035/viewer/2022062323/5681555d550346895dc3260e/html5/thumbnails/5.jpg)
Average Nu and KL
• Reynolds number from mass flow rate– Dj = 1 mm
• Calculate average heat transfer coefficient – Heat flux from energy balance for He (Te exit
temperature)– Avg. cooled surface temperature extrapolated from embedded TCs– Ac = 131.5 mm2 = area of cooled surface
• Average Nusselt number from– coolant thermal conductivity
• Loss coefficient from pressure drop p– average speed
j
4mRe
D
p e in
c in c
( )
( )
mc T Th
T T A
cT
jhDNu
kh
m
k
L 2ρ 2
pK
V
V
ARIES Mtg. (9/13) 5
![Page 6: Update: HEMJ Experiments in the GT Helium Loop](https://reader035.fdocuments.us/reader035/viewer/2022062323/5681555d550346895dc3260e/html5/thumbnails/6.jpg)
Helium Loop Schematic
• Evacuate loop, then charge to 10 MPa with He from 41.3 MPa source tanks
• Two buffer tanks increase He inventory and reduce flow pulsation
• Mass flow rate adjusted using bypass • He supplied to test module is heated
with recuperator and electric heater• Inline filters remove particulates
larger than 7 μm
ARIES Mtg. (9/13) 6
He source tanks
Reciprocating compressor
Vacuum pump
Recuperator
CoolerTest section
Electric heaterBuffer tanks
Bypass
![Page 7: Update: HEMJ Experiments in the GT Helium Loop](https://reader035.fdocuments.us/reader035/viewer/2022062323/5681555d550346895dc3260e/html5/thumbnails/7.jpg)
Reciprocating Compressor
Reciprocating Compressor
Test Section (in fume
hood)
Test Section (in fume
hood)
Buffer TanksBuffer Tanks
Recuperator/Preheater
Recuperator/Preheater
GT Helium Loop
ARIES Mtg. (9/13) 7
![Page 8: Update: HEMJ Experiments in the GT Helium Loop](https://reader035.fdocuments.us/reader035/viewer/2022062323/5681555d550346895dc3260e/html5/thumbnails/8.jpg)
ARIES Mtg. (9/13) 8
HEMJ Experiments• HEMJ test section: J-1c design– D185 W-alloy (97% W + 2.1% Ni
+ 0.9% Fe) outer shell + brass C360 inner jets cartridge
– Heat with oxy-acetylene torch: incident heat fluxes q 2.7 MW/m2
– Flow argon over flame impingement location to minimize oxidation (D185 “oxidation-resistant” up to 600 °C): maximum measured temperatures ~950 °C
![Page 9: Update: HEMJ Experiments in the GT Helium Loop](https://reader035.fdocuments.us/reader035/viewer/2022062323/5681555d550346895dc3260e/html5/thumbnails/9.jpg)
ARIES Mtg. (9/13) 9
Current Status• HEMJ experiments in GT helium loop– Inlet temperatures Ti = 43 – 295 °C (pi = 10 MPa)
– Mass flow rates = 2.9 – 6.9 g/s (fluctuations <3%): Re 1.4104 4.1104 (vs. 2.14104 at prototypical conditions)
– Incident heat fluxes q = 0.7 2.7 MW/m2
– Minor oxidation + stress-induced fracture (at TC port 0.25 mm from heated surface) observed on outer shell
– Based on pressure drop data loss coefficients KL = 2.4 – 2.5 over all
measurements– Inconsistent results for Nu due to variations in gap between inner
cartridge, outer shell (0.9 mm): machining tolerance (0.1 mm) + seating of cartridge inside shell
m
![Page 10: Update: HEMJ Experiments in the GT Helium Loop](https://reader035.fdocuments.us/reader035/viewer/2022062323/5681555d550346895dc3260e/html5/thumbnails/10.jpg)
Relaminarization• Focus of US-Japan collaboration
PHENIX (Kyoto U., TUS)– Relaminarization/“Deteriorated turbulent heat
transfer” reduction in Nu due to variations in coolant properties
– Based on available data (in simpler geometries), only occurs at low Re: potential issue for off-normal events
– Use He loop to see if anomalous heat transfer behavior observed at low Re ( 0.6 g/s with 6% fluctuation), smaller gaps
– Hosting visitors in Aug., Sept.
ARIES Mtg. (9/13) 10
Reynolds number
mMcEligot & Jackson 2004
Flow regime map: Square ducts
![Page 11: Update: HEMJ Experiments in the GT Helium Loop](https://reader035.fdocuments.us/reader035/viewer/2022062323/5681555d550346895dc3260e/html5/thumbnails/11.jpg)
Next Steps• HEMJ experiments– New test section: WL10 outer cartridge + stainless steel inner jets cartridge with
adjustable gap– Measurements by ORNL ks (T) for D185, brass
– Increase Ti to ~400 °C and q above 5 MW/m2 using 10 kW RF induction heater
(loan from INL): avoid oxidation• Relaminarization experiments– Continue experiments at low mass flow rates– Vary gap width
ARIES Mtg. (9/13) 11