Nuclear Thermal Hydraulics Lab Univerisityof California, Berkeley

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					 Nuclear Thermal Hydraulics Lab
Univerisity of California, Berkeley




             IHX Thermal Modeling
Eugenio Urquiza Fernández « keno »
Nuclear Thermal Hydraulics Lab
Department of Mechanical Engineering
University of California, Berkeley
keno@me.berkeley.edu
                   Outline
AHTR, Intermediate Loop        5%
IHX Geometry                   35%
EPM Thermal Model              30%
CHEETAH Code                   10%
IHX Transient visualizations   20%




                                     2
                        Intermediate HT Loop
                           Sulfur Iodine Cycle




Image: Prof. Peterson - UC Berkeley
                                                 3
         Project Objective


To develop a global steady state and transient
model for the thermal & mechanical response of
a compact IHX




                                             4
UCB is studying metallic IHX designs
                                                Salt
                                           0.10 m
                                                       Helium
                                  Tube sheet
                                  Capillary tube
                                  bundle
                                  Insulation
                                  Helium
                                  vessel wall                   1.25 m




 Heatric is the baseline for      UCB is collaborating with UW to
    UCB IHX transient          develop a capillary tube and shell IHX
  thermal modeling effort       taking advantage of low LS pumping
                                        power requirements
                                                                         5
 Transient thermal response model for
    Heatric-type heat exchangers
Large temperature gradients can develop in compact heat
exchangers during flow transients (e.g. interruption of flow
of one fluid)
Normal modeling methods cannot model global HX thermal
response
Developed - Effective Porous Media (EPM) model based on
volume averaging of mass & energy conservation equations
The model has been implemented in the CHEETAH code;
example results are presented here
Global and local thermal stresses can then be calculated
using methods developed earlier by UCB
                                                               6
                          IHX Assembly
     liquid salt outlet            helium inlet



                                                      X
                    X                        X

                                                  Z
                                                          Y


Z                            Z

liquid salt inlet
liquid salt side plate        helium side plate

                    Image: David Huang
                                                      7
                          Unit Cell - Center
               l

          w                                                                   CVI/CVD
                                                                            carbon-coated
                                                               Milled or     MS surface
                               Py
                                                             die-embossed
                                                             flow channel
                          Px

                                    Radius at corner

              PLAN VIEW

                                    Milled or die embossed
   h                                 MS flow channel
dMS MS                                                                         Reaction-
                                    Low-permeability coating
                                    (optional)                                  bonded
dHe hHe                             Reaction-bonded joint                        joint
                                    Milled or die embossed
                                    He flow channel
              SIDE VIEW             Radius at corner

                                     Image: David Huang
                                                                                            8
   Unit Cell Lumped Thermal Model

Unit Cell in Offset Strip Fin Region


       z


                            x


                 y                                          x




                                       y
                                           3 Phases in
                                           this Unit Cell       9
Control Volumes – 3 Cell
         X




                           Z




                   Y




                               10
                           Effectiveness
      liquid salt outlet
    liquid salt outlet           helium inlet       Pressure Variation
                                                    Temp. dept. Properties
                                                    Manufacturing
                                                    Tolerances
                    X                           X   Corrosion
                                                    Creep ~ 7 MPa ∆P

                                                    All these effects can
                                                    contribute to flow
Z                           Z                       maldistribution and
liquid salt inlet                                   degradation of thermal
                                                    effectiveness ε
liquid salt side            helium side

                     Image: David Huang
                                                                        11
                    Fluid Mechanics
Eq. of Continuity        Darcy’s Transport Equation

                          x-dir               z-dir
∂u ∂w                             kx d Φ              kz d Φ
  +   =0                  u=−                  w=−
∂x ∂z                             µ dx                µ dz


Combining Eq. of Continuity with Darcy’s Transport Eq.
(Lam. Incomp. & Fully Dev. Flow)

  1 ∂k x ∂Φ k x ∂µ ∂Φ k x ∂ 2Φ 1 ∂k z ∂Φ k z ∂µ ∂Φ k z ∂ 2 Φ
−          + 2       −         −        + 2       −          =0
  µ ∂x ∂x µ ∂x ∂x µ ∂x       2
                                 µ ∂z ∂z µ ∂z ∂z µ ∂z      2




                                                                  12
               LS Plate Schematic

Z




    Inlet              Offset Strip   Outlet
    Manifold           Fin Section    Manifold
    Section                           Section




                   X




                                                 13
         Gas Plate Schematic


Z




    Inlet          Offset Strip   Outlet
    Manifold       Fin Section    Manifold
    Section                       Section




               X




                                             14
k x ∂ 2Φ k z ∂ 2Φ
        +         =0
µ ∂x 2 µ ∂z 2

                                   Fluid Mechanics
   But where can we find the effective permeabilities for such a complex geometry?
   > distinct 30 zones!

   Illustrative Example:
   1D FD Laminar Incompressible Flow –
   Navier Stokes reduce to:

       −D2 d Φ                   − D2 d Φ         D dΦ
    u=                     u =u*
                               2
                                          = − Re
       32µ dx                    32µ dx          32ρ dx
                                                              Derivation of Darcy’s
    Fanning Friction Factor                                   transport equation for IHX
                                              16              gives:
    for Lam. flow in Pipe
                                       ff =
                                              Re
                                                                                  Dh µφ 2 1 d Φ
                                                                          uD = −
                                                                                 2 f f ρ uD µ dx
     Average, Interstitial & Darcy
     Velocities defined as:                        Finally:
                                                                                      ƒ from Kays
                                                                      Dh µφ  2
                                                                                      & London or
                          uD                                  kx =
             u = uint =                                              2 f f ρ uD       other exp. or
                          φ                                                           interpolation
                                                                                               15
k x ∂ 2Φ k z ∂ 2Φ
        +         =0
µ ∂x 2 µ ∂z 2


                          Fluid Mechanics
     Combining Eq. of Continuity with Darcy’s Transport Eq.
     (Lam. Incomp. & Fully Dev. Flow)

      1 ∂k x ∂Φ k x ∂µ ∂Φ k x ∂ 2Φ 1 ∂k z ∂Φ k z ∂µ ∂Φ k z ∂ 2 Φ
    −          + 2       −         −        + 2       −          =0
      µ ∂x ∂x µ ∂x ∂x µ ∂x       2
                                     µ ∂z ∂z µ ∂z ∂z µ ∂z      2




      If treated with constant
      Viscosity and Permeability



      k x ∂ 2Φ k z ∂ 2Φ
               +        =0
      µ ∂x   2
                 µ ∂z 2



                                                                      16
Unit Cell Lumped Thermal Model
                      Unit Cell in Offset Strip Fin Region


     Fluid phase #1



   Solid phase


  Fluid phase #2



                      Separate energy equations can be
                           written for each phase            17
        Unit Cell Lumped Thermal Model
 Conservation of Energy Eq. for each phase

Hot Fluid                                                         High Peclet Number

                   ∂T fh                       dT fh                  ∂ 2T fh                   ∂ 2T fh                                                  ∂T fh
−u fh ρ fh c pfh           − w fh ρ fh c pfh           + k fh a′fhx             + k fh a′fhz              − h fhs a′fhs (T fh − Ts ) = φ fh ρ fh c pfh
                    ∂x                          dz                     ∂x 2                      ∂z 2                                                     ∂t


Solid
                                                             ∂ 2Ts          ∂ 2Ts               ∂T
                                   ′                       ′
h fhs a ′fhs (T fh − Ts ) − hsfc a sfc (Ts − T fc ) + k s ak              ′
                                                                   + k s ak       = φ s ρ s c ps s
                                                             ∂x 2           ∂z 2                 ∂t
                                                                                                                                     z
                                                                                                                                                   x
Cold Fluid                                                            High Peclet Number                                                   y

                   ∂T fc                       ∂T fc                  ∂ 2T fc                    ∂ 2T fc                                                  ∂T fc
−u fc ρ fc c pfc           − w fc ρ fc c pfc           + k fc a′fcx              + k fc a′fcz                      ′
                                                                                                           + hsfc asfc (Ts − T fc ) = φ fc ρ fc c pfc
                    ∂x                          ∂z                      ∂x 2                      ∂z 2                                                     ∂t


                                                                                                                                                                  18
The Cheetah Code




     Compact
     Heat
     Exchanger
     Explicit
     Thermal
     And
     Hydraulics
Steady State LS Pressure IHX




                               20
Steady State LS Fluid Speed IHX




                              21
Steady State Gas Pressure IHX




                                22
          Transient Response from Steady State

                      0s           0s




                      20s          20s


LS Pump                                      Gas Pump
Trip                                         Trip
                      40s          40s




                      67s          67s




                     150s          150s
                                                  23
          Future Work

Qualifying Exams – Dec. 7th, 2007
Thermal Model
  Incorporate Temp. dept. Properties
  Implicit Scheme esp. for FD
  Fortran increase CHEETAH’s speed
  Benchmark w/ experimental data GT-MHR
Mechanical Model
  CAD IHX & Preliminary Stress Analysis
  Incorporate most recent results into AIChE
  Presentation


                                               24
UCB is studying metallic IHX designs
                                                Salt
                                           0.10 m
                                                       Helium
                                  Tube sheet
                                  Capillary tube
                                  bundle
                                  Insulation
                                  Helium
                                  vessel wall                   1.25 m




 Heatric is the baseline for      UCB is collaborating with UW to
    UCB IHX transient          develop a capillary tube and shell IHX
  thermal modeling effort       taking advantage of low LS pumping
                                        power requirements
                                                                         25
            Transient Response
             from Steady State




Eugenio Urquiza Fernández « keno »
PhD Candidate
Nuclear Thermal Hydraulics Lab – NE Dept.
Department of Mechanical Engineering
University of California, Berkeley
keno@me.berkeley.edu
                                            26
Nuclear Thermal Hydraulics Lab
 Research Directed by Prof. Peterson
 Department of Nuclear Engineering
 4118 Etcheverry Hall
 Reactor & Power Plant Design
   Thermal Hydraulics
 PB-AHTR



                                       27
            The Challenges
Construction Costs
  Utilities must prove that they can build new nuclear
  power plants: On Time & On Budget
Construction & Budget
  Building the plants is complicated
  CAD & Modular construction techniques
  AREVA – EPR in Finland
Waste Politics

                                                         28
Hoffert et al. – Nature 1998

                    N



                    GDP/N



                    E/GDP
                    Conservation & Efficiency



                    C/E
                    Non-Fossil Energy Sources
                                          29
US Department of Energy
                          30
US Electricity by Source




                           31
               Nuclear has very low
            life-cycle CO2 emissions




If we assume that nuclear electricity is used for uranium enrichment,
rather than coal electricity, nuclear life-cycle emissions drop further
                                                                          32
                     Slide: Prof. Peterson - UC Berkeley
                 Energy from Nuclear FissionFISSION PRODUCT
                                                                                                 ACTIVATION
                                                        neutron                     activation    PRODUCT

                                       fission
                                                        neutron                                    CHAIN
                                                                                     fission      REACTION
                                       200 MeV
                             235
                 neutron           U        FISSION PRODUCT         235    239
                                                                          U,     Pu, etc.


• Fission Fuel Energy Density: 8.2 x 1013 J/kg
• Fuel Consumed by 1000-MWe Plant: 3.2 kg/day
   Waste:
• Fission Prod. (3.2 kg/day) Activation Products                                                       Mining
                 90Sr,   30 yr; 137Cs, 30 yr;    Fuel        Transuranics, longer                       Radon
                      99Tc, 2x105 yr; etc.                   half lives (239Pu, 24,000 yr;            from mill
                 10                                           237Np, 2x106 yr; etc.)                    tails if
 Percent Yield




                                                  Structures    Moderate half lives, low-            not capped
                 10-1                                           level waste (60Co, 5 yr)
                                                  Coolants      Low (water) to moderate Construction
                 10-3                                           (metals) half lives        materials
                    60       100    140     180 Transmutation         Convert from long
                             Mass Number                              to short half life             33
                                           Slide: Prof. Peterson - UC Berkeley
Image: Steven Koonin - BP
                            34
      Resource inputs will affect future capital
             costs and competition
     •   Nuclear: 1970’s vintage PWR, 90% capacity factor, 60 year life [1]
          – 40 MT steel / MW(average)
          – 190 m3 concrete / MW(average)
     •   Wind: 1990’s vintage, 6.4 m/s average wind speed, 25% capacity
         factor, 15 year life [2]
          – 460 MT steel / MW (average)
          – 870 m3 concrete / MW(average)
     •   Coal: 78% capacity factor, 30 year life [2]
          – 98 MT steel / MW(average)
          – 160 m3 concrete / MW(average)
     •   Natural Gas Combined Cycle: 75% capacity factor, 30 year life [3]
          – 3.3 MT steel / MW(average)
          – 27 m3 concrete / MW(average)

Concrete + steel are >95% of construction   1. R.H. Bryan and I.T. Dudley, “Estimated Quantities of Materials Contained in a 1000-MW(e)
                                                  PWR Power Plant,” Oak Ridge National Laboratory, TM-4515, June (1974)
inputs, and become more expensive in a      2. S. Pacca and A. Horvath, Environ. Sci. Technol., 36, 3194-3200 (2002).
                                            3. P.J. Meier, “Life-Cycle Assessment of Electricity Generation Systems and Applications for
carbon-constrained economy                        Climate Change Policy Analysis,” U. WisconsinReport UWFDM-1181, August, 2002.

                                                                                                                                   35
                            Slide: Prof. Peterson - UC Berkeley
        Energy from Fossil Fuels



•   Fossil Fuel (Coal) Energy Density: 2.9 x 107 J/kg
•   Fuel Consumed by 1000-MWe Plant: 7,300,000 kg/day
•   Waste:         Coal Combustion Products       Mining
             NOx     High temperature              Leachates/
                     combustion                    dust from
             SOx     Sulfur in coal (0.4% - 5%)     mining
             Ash     (5% - 25% of coal mass)      Construction
             CO2     Global warming                materials

                       2005 Global Coal Consumption: 5.4 billion tons
                                                                        36
                    Slide: Prof. Peterson - UC Berkeley
            Consistent comparison of levelized delivered
                         electricity costs
                                                     •Oconee 1

                                                     1973 - Construction initiated
                                                     5.7 years construction time
                                                     77.7% Capacity Factor
                                                     851 MW – Generating Capacity

                                                     •Arkansas 2

                                                     1980 - Construction initiated
                                                     7.2 years construction time
                                                     89.7% Capacity Factor
                                                     858 MW – Generating Capacity

                                                     •Byron 2

                                                     1987 - Construction initiated
                                                     11.6 years construction time
                                                     93.1% Capacity Factor
                                                     1120 MW – Generating Capacity

Hultman, Koomey, Kammen –
                                                                                     37
Environmental Science & Technology / APRIL 1, 2007
France closed its last coal mine in April, 2004




           Slide: Prof. Peterson - UC Berkeley
                                                  38
            Distribution of total levelized busbar costs for 99
           U.S. reactors, including capital and operating costs




Hultman, Koomey, Kammen – Environmental Science & Technology / APRIL 1, 2007   39
The Generations of Nuclear Energy




               Source: DOE Generation IV Project

                                                   40
Staggered Grid




                 41
Consistent comparison of levelized
    delivered electricity costs

Three of the least expensive U.S. reactors in our sample are compared with
estimates made in studies by the Massachusetts Insitute of Technology (MIT ;
9 ), the Generation-IV International Forum (11), and the University of Chicago
(UC; 10 ). Discount rate is 6% real. The least costly reactor in the sample is
Oconee 1; its busbar cost was 3.2 ¢/ kWh. Key data (date of operation start,
duration of construction, lifetime capacity factor [CF], size) for each plant are as
follows: Oconee 1 (1973, 5.7 years, 77.7%, 851 MW); Arkansas 2 (1980, 7.2
years, 89.7%, 858 MW); Byron 2 (1987, 11.6 years, 93.1%, 1120 MW). The MIT
construction duration is 5 years for the “no-policy” case and 4 years for the “all-
goeswell” case; lifetime CF is 85%, and size is 1000 MW. Capital cost estimates
for AP 1000 are taken from the U.S. Department of Energy road map for 2010.
Other costs and assumptions for AP 1000 are assumed to
be the same as for the MIT “all-goes-well” case. UC lifetime CF = 85%, size =
1000 MW, construction duration = 7 years.



                                                                                       42
                  Outline
Nuclear Power                      20%
Background IHX                     10%
CV’s & Grid Setup                  10%
Effective PM Model                 25%
Coupling of Regions in IHX Model   10%
IHX Transient visualizations       15%
Future Work                        10%



                                         43
               Heatric-type HX

Z




    Inlet             Off Set     Outlet
    Manifold          Strip Fin   Manifold
    Section           Section     Section




                  X




                                             44
Salt Side Permeability Zones




                               45
Helium Side Permeability Zones




                             46
Steady State Pressure in
    Inlet Manifold




                           47
Steady State Velocity Field
    in Inlet Manifold




                              48
Heatric-type HX




                  49

				
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