On the Enhancement of the Critical Heat Flux in Water-Based Nanofluids for Applications in Nuclear S...
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On the Enhancement of the Critical Heat Flux in Water-Based Nanofluids for Applications in Nuclear Systems

Presented by Prof. Jacopo Buongiorno

Co-authors: Sung Joong Kim, In Cheol Bang, Lin-wen Hu

Nuclear Science and Engineering Department

Massachusetts Institute of Technology

Workshop on Modeling and Measurements of Two-Phase Flows and Heat Transfer in Nuclear Fuel Assemblies

KTH, Stockholm, October 10-11, 2006


Outline l.jpg
Outline Nanofluids for Applications in Nuclear Systems

  • Intro to nanofluids

  • MIT program research highlights

    • single-phase heat transfer

    • boiling heat transfer

  • Promising nuclear applications

  • Conclusions


Nanofluids l.jpg

Aluminum Oxide Particles in Water Nanofluids for Applications in Nuclear Systems

Nanofluids

  • Nanofluids are engineered colloids = base fluid (water, organic liquid) + nanoparticles

  • Nanoparticle size: 1-100 nm

  • Nanoparticle materials: Al2O3, ZrO2, SiO2, CuO, Fe3O4, Au, Cu, C (diamond, PyC, fullerene) etc.

  • Previous studies suggest significant enhancement of:

    • Thermal conductivity (+40%)

    • Single-phase convective

      heat transfer (+40%)

    • Critical Heat Flux (+100%)


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Nanofluid Research Program at MIT Nanofluids for Applications in Nuclear Systems

Objectives

  • Measure and understand key transport phenomena in nanofluids

  • Evaluate nanofluids applicability to nuclear systems

    Other applications include processor cooling, air conditioning, automotive cooling…

  • Faculty (2), staff (3), students (8), post-doc (1) involved

  • Sponsors include INL, AREVA, NRC and NRL

  • Collaborations with MIT MechE, MIT ChemE, UFL, U-Leeds, POLIMI, Olin College, RPI


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    Research Highlights Nanofluids for Applications in Nuclear Systems


    Nanofluid thermal conductivity l.jpg
    Nanofluid Thermal Conductivity Nanofluids for Applications in Nuclear Systems

    Measured thermal conductivity of >20 nanofluids with transient hot wire technique

    No abnormal thermal conductivity enhancement observed


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    Nanofluid Convective Heat Transfer Nanofluids for Applications in Nuclear Systems

    Measured heat transfer coefficient and pressure drop in flow loop

    • Nanofluids seem to follow traditional heat transfer behavior

    • No heat transfer enhancement detected so far


    Nanofluid critical heat flux l.jpg

    Water-based nanofluid with ZrO Nanofluids for Applications in Nuclear Systems2 particles

    DI water (1 MW/m2)

    DI water (0.5 MW/m

    )

    2

    Nanofluid (1 MW/m

    )

    2

    Nanofluid (0.5 MW/m2)

    Very significant CHF enhancement observed at low nanoparticle concentrations

    Nanofluid Critical Heat Flux


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    Why Does CHF Increase? Nanofluids for Applications in Nuclear Systems

    • Thermophysical properties do not change significantly at low nanoparticle concentration


    Why does chf increase 2 l.jpg

    Al Nanofluids for Applications in Nuclear Systems

    EDS: 0.01v% Al2O3

    SEM Picture of SS316 Wire

    After Boiling of 0.01v% Al2O3 Nanofluid

    SEM Picture of SS316 Wire

    After Boiling of DI Water

    Why Does CHF Increase? (2)

    • Heater surface does change upon nanofluid boiling!!


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    Why Does CHF Increase? (3) Nanofluids for Applications in Nuclear Systems

    Measurements of nanoparticle deposition on heated surface during boiling

    Plate Type Heater – SS316

    SEM: Clean SS316 Surface

    EDS: Clean SS316 Surface


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    SEM: 0.01v% Al Nanofluids for Applications in Nuclear Systems2O3

    Al

    SEM: 0.01v% SiO2

    100 m

    EDS: 0.01v% Al2O3

    Si

    Zr

    SEM: 0.01v% ZrO2

    100 m

    EDS: 0.01v% SiO2

    EDS: 0.01v% ZrO2

    100 m

    Why Does CHF Increase? (4)


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    Pure water on clean surface Nanofluids for Applications in Nuclear Systems

    Nanofluid on clean surface

    Pure water on nanoparticle fouled surface

    Nanofluid on nanoparticle fouled surface

    Why Does CHF Increase? (5)

    Surface wettability increases dramatically


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    Why Does CHF Increase? (6) Nanofluids for Applications in Nuclear Systems

    CHF theories:

    • Hydrodynamic Theory

    • Macrolayer Dryout Theory

    • Hot/Dry Spot Theory

    • Bubble Interaction Theory

      - 1 predicts no effect of wettability on CHF

      - 2, 3 and 4 predict CHF enhancement if wettability increases


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    Why Does CHF Increase? (7) Nanofluids for Applications in Nuclear Systems

    Observed CHF enhancement magnitude is consistent with theory prediction


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    Nuclear Applications of Nanofluids Nanofluids for Applications in Nuclear Systems

    • PWR main coolant. Coolant chemistry and particle deposition are big concerns

    • Safety systems. Requires also post-CHF enhancement (not proven yet)

    • In-vessel retention for high-power density reactors. Very promising


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    In-Vessel Retention Nanofluids for Applications in Nuclear Systems

    Use of a nanofluid results in a stable +40% heat removal enhancement with the same margin to DNB


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    In-Vessel Retention (2) Nanofluids for Applications in Nuclear Systems

    Concentrated nanofluid is injected in already flooded reactor cavity, thus creating a dilute nanofluid


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    In-Vessel Retention (3) Nanofluids for Applications in Nuclear Systems

    Mean particle diameter in alumina nanofluid, as measured with DLS

    Little agglomeration occurs after dilution

    Nanofluid stays stable for at least 24 hours after dilution


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    Conclusions Nanofluids for Applications in Nuclear Systems

    • Nanofluids offer potential for significant enhancement of the boiling critical heat flux

    • Nuclear applications include PWR primary coolant, safety systems, in-vessel retention

    • MIT is conducting a multi-disciplinary research program to investigate heat transfer enhancement in nanofluids


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    Future Work Nanofluids for Applications in Nuclear Systems

    Flow boiling


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