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  • Micro- & Nano-Technologies Enabling More Compact, Lightweight Thermoelectric Power Generation & Cooling Systems

    2011 Thermoelectrics Applications Workshop San Diego, CA 5 January 2011

    Terry J. Hendricks, Shankar Krishnan, Steven Leith

    Pacific Northwest National Laboratory Energy & Efficiency Division

    MicroProducts Breakthrough Institute Corvallis, OR

    We Sincerely Thank Our Sponsor: John Fairbanks, Gurpreet Singh U.S. Department of Energy

    EERE - Office of Vehicle Technologies

  • Advanced Thermoelectric System Design Single & Segmented Material TE Legs

    2

    Qh,out

    Qc,in

    Power InPower In

    Th

    N

    Tc

    Compartment Cooling Flow

    Hot-Side Rejection Flow

    Tcol d

    Cold Side Heat Exchanger

    Hot Side Heat Exchanger

    Tamb , mh Ambient

    Tcabin , mc •

    P

    I

    Power InPower In

    Th

    N

    Tc

    Compartment Cooling Flow

    Hot-Side Rejection Flow

    Tcol d

    Cold Side Heat Exchanger

    Hot Side Heat Exchanger

    Tamb , mh Ambient

    •Tamb , mh Ambient

    Tcabin , mc •Tcabin , mc •

    P

    I

    Thermoelectric Heating/Cooling Low-Temperature Systems

    Qh,in

    Power Out

    Tcold

    N1

    Thot

    Industrial & Vehicle Exhaust Flow

    Environment Ambient Flow

    Tcold

    Qc,out

    External Load, Ro

    Hot Side Heat Exchanger

    Cold Side Heat Exchanger

    Tamb , mc Ambient

    Tex , mh Exhaust

    P2

    Thermoelectric Power Generation High-Temperature Systems

    P1

    N2

    Generally Do Cascading Rather Than Segmenting to Achieve Large ∆T

    Advantages of Segmenting Depends on Available ∆T

  • 0 200 400 600 800 1000 1200 0

    0.02

    0.04

    0.06

    0.08

    0.1

    0.12

    Power [W]

    M ax

    im um

    E ffi

    ci en

    cy

    0.237(W/cm2) →

    0.403(W/cm2) →

    0.589(W/cm2) →

    0.808(W/cm2) →

    1.06(W/cm2) →

    1.34(W/cm2) →

    1.66(W/cm2) →

    2.02(W/cm2) →

    2.41(W/cm2) →

    2.83(W/cm2) →

    3.28(W/cm2) →

    3.77(W/cm2) →

    ← T h

    =4 90

    (K )

    ← T h

    =5 15

    (K )

    ← T h

    =5 40

    (K )

    ← T h

    =5 65

    (K )

    ← T h

    =5 90

    (K )

    ← T h

    =6 15

    (K )

    ← T h

    =6 40

    (K )

    ← T h

    =6 65

    (K )

    ← T h

    =6 90

    (K )

    ← T h

    =7 15

    (K )

    ← T h

    =7 40

    (K )

    ← T h

    =7 65

    (K )

    ← T h

    =7 90

    (K )

    ← T h

    =8 15

    (K )

    ← T h

    =8 40

    (K )

    ← T h

    =8 65

    (K ) Tcold=380 (K)

    Tcold=415 (K) Tcold=450 (K) Constant Thot

    0 200 400 600 800 1000 1200 0

    0.02

    0.04

    0.06

    0.08

    0.1

    0.12

    Power [W]

    M ax

    im um

    E ffi

    ci en

    cy

    98(W/kg) →

    165(W/kg) →

    243(W/kg) →

    335(W/kg) →

    441(W/kg) →

    561(W/kg) →

    696(W/kg) →

    846(W/kg) →

    1012(W/kg) →

    1194(W/kg) →

    1392(W/kg) →

    1608(W/kg) →

    1841(W/kg) →

    ← T h

    =4 90

    (K )

    ← T h

    =5 15

    (K )

    ← T h

    =5 40

    (K )

    ← T h

    =5 65

    (K )

    ← T h

    =5 90

    (K )

    ← T h

    =6 15

    (K )

    ← T h

    =6 40

    (K )

    ← T h

    =6 65

    (K )

    ← T h

    =6 90

    (K )

    ← T h

    =7 15

    (K )

    ← T h

    =7 40

    (K )

    ← T h

    =7 65

    (K )

    ← T h

    =7 90

    (K )

    ← T h

    =8 15

    (K )

    ← T h

    =8 40

    (K )

    ← T h

    =8 65

    (K ) Tcold=380 (K)

    Tcold=415 (K) Tcold=450 (K) Constant Thot

    TE Power Generation Heat Exchanger / TE Device Integration Requirements

     Regions of Higher Specific Power Also Associated with Higher Heat Flux Regions

     Hot Side Heat Exchanger Dictates:  TE Specific Power  TE Power Flux  TE Volumetric Specific

    Power

     Heat Fluxes > 15 W/cm2 in Preferred Design Regimes  Hot-side  Cold-side

    Segmented Skutterudite /Bi2Te3 Materials

    hm

    Preferred TE Design Regime

    Texh= 873 K Tamb = 300 K

    = 0.1 kg/s UAh = 377 W/K

  • TE Cooling Heat Exchanger / TE Device Integration Requirements

    250 300 350 400 450 500 550 600 0

    0.1

    0.2

    0.3

    0.4

    0.5

    0.6

    0.7

    0.8

    Cooling Capacity [W]

    M ax

    im um

    C O

    P

    ←1421(W/kg)

    ←1294(W/kg)

    ←1173(W/kg)

    ←1057(W/kg)

    ← T h =340(K)

    ← T h =337(K)

    ← T h =334(K)

    ← T h =331(K)

    ← T h =328(K)

    ← T h =325(K)

    ← T h =322(K)

    ← T h =319(K)

    ← T h =316(K)

    Tcold=280 (K) Tcold=270 (K) Tcold=260 (K) Constant Thot

    Distributed Cooling Systems

     Typical COP – Cooling Capacity – Power / Mass Relationship Shown  Distributed TE Cooling Systems

     Create Lower Heat Flows per Unit

     Higher COP’s  Lower Power / Mass

     Generally Right Directions for Automotive Distributed Cooling

    p-type NPB BixSb2-xTe3 *

    n-type Bi2Te3 – Bi2Se3

    * Poudel, B., Hao, Q.H., Ma, Y., Lan, Y., Minnich, A. Yu, B., Yan, X., Wang, D., Muto, A., Vashaee, D., Chen, X., Liu, J., Dresselhaus, M.S., Chen, G., Ren, Z., 2008, “High- Thermoelectric Performance of Nanostructured Bismuth Antimony Telluride Bulk Alloys,” Sciencexpress, 10.1126, science.1156446.

    UAc = 40 W/K Tcabin = 298 K

  • 100 150 200 250 300 350 400 450 0

    0.1

    0.2

    0.3

    0.4

    0.5

    0.6

    0.7

    0.8

    Qc Per Mass[W/kg]

    M ax

    im um

    C O

    P

    ← T h

    =3 40

    (K )

    ← T h

    =3 37

    (K )

    ← T h

    =3 34

    (K )

    ← T h

    =3 31

    (K )

    ← T h

    =3 28

    (K )

    ← T h

    =3 25

    (K )

    ← T h

    =3 22

    (K )←

    T h =3

    19 (K

    )← T h

    =3 16

    (K )

    Tcold=280 (K) Tcold=270 (K) Tcold=260 (K) Constant Thot

    p-type NPB BixSb2-xTe3 n-type Bi2Te3 – Bi2Se3

    UAc = 40 W/K

    Tcabin = 298 K

    Preferred TE Design Regime

    TE Cooling Heat Exchanger / TE Device Integration Requirements

    0.4 0.5 0.6 0.7 0.8 0.9 1 0

    0.1

    0.2

    0.3

    0.4

    0.5

    0.6

    0.7

    0.8

    Qc Per Area [W/cm2]

    M ax

    im um

    C O

    P

    ← T h

    =3 40

    (K )

    ← T h

    =3 37

    (K )

    ← T h

    =3 34

    (K )

    ← T h

    =3 31

    (K )

    ← T h

    =3 28

    (K )

    ← T h

    =3 25

    (K )

    ← T h

    =3 22

    (K )

    ← T h

    =3 19

    (K )←

    T h =3

    16 (K

    )

    Tcold=280 (K) Tcold=270 (K) Tcold=260 (K) Constant Thot

    Preferred TE Design Regime

    p-type NPB BixSb2-xTe3 n-type Bi2Te3 – Bi2Se3 UAc = 40 W/K

    Tcabin = 298 K

     Distributed TE Cooling Systems Generally Move Into Regions of:  Higher COP’s  Higher Specific Cooling Capacity (Compact, Lightweight Systems)  Higher Heat Fluxes (Higher Heat Transfer Coefficients)

     Generally Higher Performance Heat Exchanger Systems Required

  • PNNL Developing High-Performance Microtechnology Heat Transfer Technologies

     TE Power Generation From TQG Exhaust Energy Recovery  Hot-Side Heat Exchanger Designs Being Developed & Refined  CFD Analyses & Experimental Testing Helping to Refine Designs  Design Performance Goals:

     High Thermal Transfer Flux (~10-12 W/cm2) in Hot-Side Heat Exchanger  Low Pressure Drop (< 1 psi)  Heat Flux vs. Pressure Drop Characteristics Quantified for Different Design Approaches

     Different Materials Can Be Used: Stainless Steel, Inconel, Haynes Materials, Ceramics

    COMSOL CFD Analysis

    Air Supply Heaters Water-Cooled Heat Sink

    Hydrodynamic Conditioning & Mixing

    Design Point

    60 kW TQG Design Conditions: 0.158 kg/sec, 780 K

    Rectangular Honeycomb Design

    Design Target

    Several Workable Design Points Identified

    ε = 0.93

  • 7

    Co-Functional Power / Cooling Systems  Co-Functional Integration of 3 Power & Cooling Technologies

     Organic Rankine Cycle Based Cooling  Thermoelectric Power Generation  Micro/Nano Heat Transfer Technologies (Microchannel Heat Exchangers)

     System Designed, Fabricated & Tested at PNNL MBI  TE Topping Cycle

     Step-Down (Lower) Input Temperatures to ORC

     Simultaneously Produce Useful Power

     E/C ORC to Provide Useful Cooling Capacity  Known & Demonstrated Components in this Phase  Reduce Cost

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