Investigation of Downward Facing CHF with Water-Based
Nanofluids for IVR
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Citation
DeWitt, G., R. J. Park, J. Buongiorno, T. McKrell, L. W. Hu.
"Investigation of Downward Facing CHF with Water-Based
Nanofluids for IVR." American Nuclear Society 2011 Annual
Meeting, June 26-30, 2011, Hollywood, Florida.
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American Nuclear Society
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Wed May 25 19:07:28 EDT 2016
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http://hdl.handle.net/1721.1/87109
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Investigation of Downward Facing CHF with Water-based Nanofluids for IVR
G. DeWitt*, R.J. Park**, J. Buongiorno*, T. McKrell*, L.W. Hu*
* Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, gdewitt@mit.edu
** Thermal Hydraulics Safety Research Division, KAERI, 1045 Daedeok-daero, Yuseong-gu, Daejeon, 305-353 Korea
INTRODUCTION
RESULTS
In-Vessel Retention (IVR) through External Reactor
Vessel Cooling is a severe accident management measure
that is power limiting to the Westinghouse AP1000 due to
critical heat flux (CHF) at the outer surface of the vessel.
Increasing CHF by altering the coolant would increase
safety margin at current design power or allow for higher
power. Modification to current design would not require
significant changes to the containment and systems [1].
Research at MIT has demonstrated that CHF of water
on a heated metal surface can be increased from 30% to
100% with the introduction of nanoparticles at low
concentrations. Research has measured enhanced CHF in
both pool [2,3] and force convective [4,5] boiling.
Alumina and water nanofluid has shown the best
enhancement and long-term stability in solution.
Conceptual implementation could involve storage
tanks of high concentration nanofluids installed in
containment (Fig. 1). Once IVR strategy has been
initiated with flooding of the vessel support cavity with
water from the In-Vessel Refueling Water Storage Tank,
nanofluids would be released to mix as the natural
circulation sets up along the gap between the vessel and
the insulation on the vessel cavity.
Results indicate 35% to 116% enhancement in CHF
for conditions expected for IVR (Fig. 3). The CHF
enhancement is higher, as a percent, in low flow
conditions and in downward facing geometry with
inclination angle of less than 60o. As expected, for a
given fluid, CHF increases for increasing mass flux and
pressure. Angular dependence of CHF is inversely
proportional to mass flux and nearly disappears at a mass
flux of 1500 kg/m2-s. At a given mass flux, CHF is
nearly linear with angle increasing smoothly from
downward horizontal position to maximum at vertical.
Water only cases were compared to studies done at
the Sultan facility in France [6] and UCSB [7] and show
similar trends and levels.
Results support utilizing alumina based nanofluid
during IVR to improve margin to CHF for the AP1000.
DESCRIPTION OF THE ACTUAL WORK
To measure CHF for the conditions relevant to IVR
in the AP1000, a two-phase flow loop has been built (Fig.
2). The test section has hydrodynamic similarity to the
AP1000 insulation/vessel gap and allows for all angles
that represent the bottom surface of the reactor vessel.
Research competed herein has measured CHF for varied
conditions of angle, pressure, mass flux, fluid type and
surface material.
Downward inclination angles are from 0o (horizontal)
to 90o (vertical). Pressure range is 1 to 5 atmospheres
absolute and bounds the AP1000 containment design
limit. Mass fluxes in the test section range from 500 to
1500 kg/m2-s. Working fluids studied are de-ionized
water and alumina nanofluids (<0.01% volume). Surface
materials are stainless steel 316L and SA508, which is the
vessel material.
REFERENCES
1. J. Buongiorno, L. W. Hu, G. Apostolaks, R. Hannink,
T. Lucas, A. Chupin, “A Feasibility Assessment of the
Use of Nanofluids to Enhance the In-Vessel Retention
Capability
in
Light-Water
Reactors”,
Nuclear
Engineering and Design, 239, 941, (2009).
2. H. Kim, G. DeWitt, T. McKrell, J. Buongiorno, L-w.
Hu, “On the Quenching of Steel and Zircaloy Spheres in
Water-Based Nanofluids with Alumina, Silica and
Diamond Nanoparticles”, International Journal of
Multiphase Flow, 35, 427, ( 2009).
3. C. Gerardi, “Investigation of the Pool Boiling Heat
Transfer Enhancement of Nano-Engineered Fluids by
means of High-Speed Infrared Thermography”, PhD
Thesis, Nuclear Science and Engineering Department,
MIT, (2009).
4. S. J. Kim, T. Mckrell, J. Buongiorno, L.W. Hu,
“Subcooled Flow Boiling Heat Transfer of Dilute
Alumina, Zinc Oxide, and Diamond Nanofluids at
Atmospheric Pressure”, Nuclear Engineering and Design,
240, 1186, (2010).
5. B. Truong, L. W. Hu, J. Buongiorno, T. McKrell,
“Subcooled Flow Boiling Critical Heat Flux Enhancement
of
Alumina
Nanoparticle
Pre-coated
Tubing”,
Proceedings of ECI International Conference on Boiling
Heat Transfer, Florianópolis, Brazil, May 3-7 2009,
(2009).
6. S. Rouge, “SULTAN Test Facility for Large-Scale
Vessel Coolability in Natural Convection at Low
Pressure”, Nuclear Engineering and Design, ISSN 00295493, 169, 185, (1997).
7. T. Dinh, J. Tu, T. Salmassi, T. Theofanous, “Limits of
Coolability in the AP1000-Related ULPU-2400
Configuration V Facility”, Proceedings of NURETH-10,
Seoul, Korea, October 5-9, 2003, Paper Number G00407,
(2003).
Fig. 1 – Conceptual application of nanofluid to AP1000 IVR
Downward Facing CHF Experiment with Nanofluids
Needle Valve
Accumulator
Pressure
Nitrogen Gas Bottle
Chilled Water
Ball Valve
Three way valve (de-gasing)
Ball Valve
Heat Exchanger
Ball Valve
Ball Valve
Thermocouple
Ball Valve
Test Section
Pressure
Thermocouple
Thermocouple
Pressure
Ball Valve
Flow Meter
Ball Valve
Thermocouple
Covered Filling &
DischargeTank
Pump
Fig. 2 – Schematic of flow boiling loop (left) and photo of variable inclination test section (right)
CHF versus Mass Flux at Atmospheric Pressures
3.50
3.00
CHF [MW/m^2]
2.50
2.00
1.50
1.00
0.50
0.00
0
500
1,000
1,500
2,000
Mass Flux [kg/m^2-s]
Water - 0
Water - 45
Water - 90
Alumina 0.001% - 0
Alumina 0.001% - 45
Alumina 0.001% - 90
Fig. 3 – CHF data versus mass flux and inclination angle for water and alumina nanofluids at atmospheric pressures.