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Jun Xu and Richard Wirtz Mechanical Engineering Department University of Nevada, Reno

IN-PLANE EFFECTIVE THERMAL CONDUCTIVITY OF PLAIN WEAVE SCREEN LAMINATES WITH ARBITRARY WEAVE PARAMETERS TED-AJ03-417. Jun Xu and Richard Wirtz Mechanical Engineering Department University of Nevada, Reno March 19, 2003

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Jun Xu and Richard Wirtz Mechanical Engineering Department University of Nevada, Reno

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  1. IN-PLANE EFFECTIVE THERMAL CONDUCTIVITY OF PLAIN WEAVE SCREEN LAMINATES WITH ARBITRARY WEAVE PARAMETERSTED-AJ03-417 Jun Xu and Richard Wirtz Mechanical Engineering Department University of Nevada, Reno March 19, 2003 Research sponsored by the Missile Defense Agency through the Air Force Office of Scientific Research, contract F49620-99-1-0286 AJTEC 2003

  2. Motivation Anisotropic Organized Reticulated Structures (AORS) are effective Heat Exchange Matrices • Wide range of porosity, surface area to volume ratio, effective thermal conductivity • Easy control of ,  and ke through mesh parameters • Anisotropy: Large ke in a particular direction AJTEC 2003

  3. Heat Exchanger Implementation[Park, Ruch and Wirtz, 2002] AJTEC 2003

  4. Heat Exchanger ImplementationTwo Approaches 3-D AORS • Dense structures, High key, , heat transfer and pressure drop. • Example: 3-D Weaves [Wirtz et al, Itherm, 2002] • Suited to liquid coolant applications Screen Laminates • Wide ranging  and , high key • Relatively low pressure drop suited for air cooling applications • Example: Screen-fin heat sink, [Li and Wirtz, SemiTherm, 2003] AJTEC 2003

  5. Screen-Fin Heat Sink[Li and Wirtz, 2003] 3” x 2.5” and 1.5” tall orthogonal-weave screen–fins Rba = 0.23 C/watt @ P = 0.25” H2O 8 liter per sec (17 cfm) coolant (air) AJTEC 2003

  6. Non-orthogonal weaves(diamond weaves)have the potential forhigher valuesofkey 50% increase in key: Li/Wirtz S-F HS Rba 0.18C/W AJTEC 2003

  7. Non-Orthogonal Plain Weave M: Mesh # d: filament dia cf: comp factor AJTEC 2003

  8. Symmetric Diamond Weave d=d1=d2 M=M1=M2 d(effective) = 0.48mm, M = 6.3cm-1  = 0.724. AJTEC 2003

  9. Symmetric Diamond Weave Porosity Orthogonal Xu & Wirtz, 2003 Diamond weave  higher metal fraction AJTEC 2003

  10. orthogonal Sym. Diamond Weave Specific Surface Area Diamond weave  higher  AJTEC 2003

  11. Sym. Diamond Weave Effective Thermal Cond Define ke: AJTEC 2003

  12. Sym Diamond Weave Effective Therm Cond Diamond weave  higher key AJTEC 2003

  13. Effective Thermal Conductivity Example cf key(diamond weave)  0.78ks AJTEC 2003

  14. Model Verification Transient thermal diffusivity measurements [Xu and Wirtz, 2003] The present model is within 8% of all of the measurements. AJTEC 2003

  15. ImplicationsWirtz/Li Screen-Fin Heat Sink Diamond weave with Md=0.529 0.484 2= 90   63.8 Gives same  and  with key = 72 W/mK 108 W/mK And Rba = 0.23 C/W 0.19 C/W (?) AJTEC 2003

  16. Conclusions Diamond vs Orthogonal Weaves • Higher metal fraction (lower ) • Higher Sp. Surface Area,  • Higher effective thermal conductivity, ke • Ke  0.78 • It is possible to configure diamond weaves having same  (same P?) &  with enhanced ke(enhanced U) AJTEC 2003

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