enhancements of immersion cooling of high power chips with nucleate boiling of dielectric liquids

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1 Advancements in Thermal Management Conference, Denver, CO, 3-4 August 216 enhancements of immersion cooling of high power chips with nucleate boiling of dielectric liquids Mohamed S. El-Genk Regents Professor, Nuclear, Mechanical, and Chemical, Engineering, Director, Nuclear Power Studies University, Albuquerque, NM, USA Power Dissipation Figures Watts Watts 1

2 Mode of Heat Transfer Cooling Methods Spray Cooling Jet Impingement Plain Surfaces Flow Boiling Pool Boiling Enhanced/ Extended Surfaces Forced Convection, Dielectric Liquids Forced Convection, Air 1 3 atm Natural Convection, Dielectric Liquids Natural Convection, Air 1 3 atm Relative Heat Transfer Coefficients (W/m 2 K) Nucleate Boiling Immersion Cooling Dielectric Liquids Low boiling point (< 6 o C) & viscosity Excellent chemical compatibility High dielectric strength Chemical and thermal stability Environmentally friendly Non-toxic and nonflammable Highly wetting low surface tension Temperature excursion prior to boiling incipience For High Power Dissipation Increase bubble nucleation sites density Rough, dimpled, microstructured, porous surfaces Micro-porous coatings Nano-Dendrites & micro-porous surfaces Increase wetted surface area with liquid Macro- structures (Length scale >.5 mm) Micro-structures (Length Scale <.5 mm) Surface roughness (fraction - few microns) Subcooled liquid high junction Temp Search by image 2

3 Porous Graphite Power Lead Porous Graphite Thermocouple Leads Property Material Copper Porous Graphite Thermal conductivity (W/m 2 K) Density (kg/m 3 ) (in plane) (out of plane) ~ 375 ~ 8,95 ~ 7 ~245 9 Porosity (%) NA ~ 61 open pores (%) NA 95 Epoxy Filler Lexan Frame 36.4 mm Thermocouple Lead Teflon Block Lexan Frame Epoxy Filler 3 mm 3.2 mm Epoxy Filler Porous Graphite 1 mm Power Lead 3 mm Lexan Frame 1 mm 6 mm Parker and El-Genk, J. Thermophysics and Heat Transfer, 23(2), 29; El-Genk and Parker, J. ECM, 49(4), 28, Cu with Corner Pins 3 mm 4 mm Pinned Plane Copper Pinned Copper Epoxy Filler 1 mm Teflon Block Block Epoxy Filler 2 m m 5 m m Lexan Frame Cu surface roughness # 4 and 15 1 x 1 mm footprint: 2, 3, and 5 mm tall and 3x3 mm square corner pins; and uniformly heated surface Parker and El-Genk, J. Thermophysics and Heat Transfer, 23(2), 29; El-Genk and Parker, J. ECM, 49(4), 28,

4 Ra =.39 μm Ra =.21 μm -5 (a) G = 15, Ra = mm Ar (%) z (mm) Rough Cu Surfaces z (mm) 5 Ra =.58 μm Ra = 1.79 μm 8 (a) Ra =.39 mm Ar = (1-e (b) Ra =.58 mm z (mm) 5 Track 1 (c) Ra = 1.79 mm Track 2 Static CA ( ) (c) G = 28, Ra = mm 7 = 5.82 Ra % 5-1% -5 4 (e) G = 8, Ra = mm -1 ) H2O on Flat Cu Measurements at ~1 seconds *Ra Track Length (mm) Ra (mm) El-Genk and Suszko, J. Heat Transfer, 136, 214, ; Suszko and El-Genk, Int. J. Heat and Mass Transfer, 81, 215, ; El-Genk and Suszko, 214, Multiphase Science and Technology, 26(2), 214, Micro-Porous Copper (MPC) Surfaces 3 mm 3 mm (a) d = 8 mm (b) d = 171 mm (c) d = 197 mm El-Genk and Ali, J. Multiphase Flow, 36, 21, ; El-Genk and Ali, J. Heat Transfer, 132, 21, ; El-Genk, and Ali, J. Heat Transfer, 133, 211, 8153; El-Genk, J. Heat Transfer Engineering, 33(3), 212, ; Ali and El-Genk, Int. J. of Thermal Sciences, 53, 212,

5 Experimental Setup Microporous Copper Thermocouple Wires A Power Lead Epoxy Filler (a) Plane view Copper Substrate Copper Microporous Layer (5 ~ 25 mm ) 1.6mm Thick Thermocouple Heater Holes Teflon Block Lexan Frame (b) Sectional view 1. PC 2. Data Acquisition System 3. Power Supply 4. Variac for Voltage Control 5. Water Bath Temperature Monitor 6. Reflux Condensers Water Loop 7. Submerged Cooling Coils 8. Chiller with Temperature Control 9. Chilled Water Lines 1.. Mounted Test Section 11. Pool Temperature Thermocouples 12. Magnetic Stirrer Bar 13. Immersion Heater 14. Bath Temperature Thermocouple 15. Test Section Surface Temperature Thermocouple A. Computer Monitor B. Acrylic Water Bath Tank C. Test Vessel D. Tightly Sealed Cover of test Vessel E. Aluminum Support Block F. Dielectric Liquid Pool B F 12 E 7 D C 13 8 Experimental Setup: UNM-ISNPS Water Bath Tank Test Vessel DC Power Supply Chiller Variac Data Acquisition Unit PC 5

6 h NB (W/m 2 K) q (W/cm 2 ) q NC (W/cm 2 ) Natural Convection Results 4 3 FC-72 Smooth Cu (UNM-ISNPS) FC-72 PG & MS Surfaces (UNM-ISNPS) PF-56 Unoxidized Rough Cu (UNM-ISNPS) PF-56 Oxidized Rough Cu (UNM-ISNPS PF-56 MPC (UNM-ISNPS) HFE-71 Cu Corner Pins (UNM-ISNPS) C NC =.526 (67.5%) 2 C NC =.44 (4.1%) C NC =.38 (21%) 1 C NC =.4 (27.4%) C NC =.353 (12.4%) C NC =.314 (-) q NC = C NC T b T b Nucleate Boiling on Plane Cu Saturation boiling of FC-72 Liquid on plane Cu, = (upward-facing) T SUB =. K (sat) T SUB = 1. K T SUB = 2. K T SUB = 3. K h MNB (I) (I) (I) (I) (I) (I) (I) (I) T b T p 6

7 q (W/m 2 ) h NB (W/m 2.K) h NB (W/cm 2 ) h NB (W/cm 2 ) Saturation Boiling on Cu with Corner Pins 2. (a) Plane Copper (b) Cu with 2 mm pins (c) Cu with 3 mm pins Saturation Boiling of HFE T sat (d) Cu with 5 mm pins = T sat 3x1 5 Saturation Boiling PF-56 Boiling on MPC Surfaces 1.4x x1 5 Saturation Boiling PF-56 2x1 5 1.x1 5.8x1 5 1x mm mm mm mm 46.3 mm 33.1 mm T Sat.6x1 5.4x1 5.2x T Sat 7

8 h NB (W/cm 2 K) Saturation Boiling on Rough Cu Surfaces Nucleate boiling and heat transfer coefficient curves for the upward facing Cu surfaces with Ra = µm. critical heat flux (CHF) maximum nucleate boiling heat transfer coefficient, h MNB Saturation Boiling on Rough Cu Surfaces Ra =.39 mm.134 PF-56 Saturation Boiling Rough Cu Surfaces q (W/cm 2 ) El-Genk and A. Suszko, J. Heat Transfer, 136, 214, ; El-Genk and Suszko, J. Multiphase Science and Technology, 26(2), 214, ; El-Genk, Suszko and Ali, Proc. IMECE213), paper No , November, San Diego, CA,

9 h NB (W/cm 2 K) q (W/cm 2 ) h NB (W/cm 2 K) Comparison NB on MPC & other Surfaces 8 6 Cu oxide Nano struture, PF 56 (Im et al., 212) Sintered Cu, HFE-73 (McHale, 211) d PG, FC-72 (El-Genk and Parker, 25) MPC = 171 mm MPC, FC-72(J. H. Kim, 26) Cu with nano wires, PF-56 (Im et al., 21) 197 mm Microporous Coating, PF-56 (Kim and Han, 28) MPC Surfaces 23 mm 115 mm 4 8 mm 2 Saturation Boiling, = o q (W/cm 2 ) Rough Cu: Effect of Liquid Subcooling (a) Ra = 1.79 mm (a) (b) (c) (d) CHF q ~3 W/cm 2 (a) ΔT sub = K (b) ΔT sub = 1 K (b) Subcooled Boiling, PF-56 (c) ΔT sub = 2 K (d) ΔT sub = 3 K MNB T b PF-56, o Inclination 9

10 N o r m a l l i z e d C H F Effect of Inclination on CHF Sat N o r m a l i z e d C H F P r i a r o n e, 3 m m d i a ( 25 ) P r i a r o n e, 3 m m d i a ( 25 ) H F E - 71 P r e s e n t W o r k, 1 x 1 m m E l - G e n k a n d B o s t a n c i, 1 x 1 m m ( 23 ) H F E - 71 R e e d, x ( 1996 ) H o w a r d a n d M u d a w a r, x m m ( 1999 ) H o w a r d, 3. 2 x 35. m m ( 1999 ) R e e d a n d M u d a w a r, x ( 1997 ) M u d a w a r, H o w a r d a n d G e r s e y, x m m ( 1997 ) C h a n g a n d Y o u, 1 x 1 m m ( 1996 ) R a i n i e y a n d Y o u, 2 x 2 m m ( 2 1 ) R a i n e y a n d Y o u, 5 x 5 m m ( 2 1 ) ( a ) P l a n e C o p p e r F C a n d H F E P l a n e P o r o u s G r a p h i t e P a r k e r a n d E l - G e n k, 1 x 1 m m, F C - 72 ( 26 ) P a r k e r a n d E l - G e n k, 1 x 1 m m, H F E - 71 ( 26 ) M i c r o p o r o u s C o a t i n g s C h a n g a n d Y o u, 1 x 1 m m ( 1996 ) R a i n e y a n d Y o u, 2 x 2 m m ( 21 ) R a i n e y a n d Y o u, 5 x 5 m m ( 21 ) ( b ) P l a n e P G a n d M i c r o p o r o u s C o a t i n g s F C a n d H F E m m P i n s, A R = m m P i n s, A R = m m P i n s, A R = P l a n e C u, A R = 1 ( c ) P l a n e C u a n d C u w i t h C o r n e r P i n s H F E (d) Cu Nano-Dendrites ( d ) M i c r o p o r o u s C o p p e r FC-72 F C I n c l i n a t i o n, ( º ) I n c l i n a t i o n, ( º ) MPC Spreader Performance 91.1 W W 9.3 W W T sat = 51.4 o C T sat = 51.4 o C T sat = 51.4 o C T sat = 51.4 o C Q Boil (3.6) Q Boil (3.51) Q Boil (3.61) Q Boil (2.59) Q MPC (.4) Q MPC (.35) Q MPC (.4) Q MPC (.34) Q SP (18) Q ToT (38.76 o C) Q SP (25) Q ToT (45.24 o C Q SP (16.5) Q ToT (21.98 o C) Q SP (2.27) Q ToT (24.62 o C Q TIM (17.12) Q TIM (16.69) Q TIM (1.81) Q TIM (1.73) 1 mm 2 CHS t Cu = 3.2 mm T chip. Max (9.16 o C) 4 mm 2 CHS t Cu = 3.2 mm T chip. Max (96.6 o C) (a) TI TIM =.19 o C-cm 2 /W, HFR = 6 1 mm 2 CHS t Cu = 3.2 mm T chip. Max (73.4 o C) 4 mm 2 CHS t Cu = 3.2 mm T chip. Max (76.1 o C) (b) TI TIM =.21 o C-cm 2 /W, HFR = 6 El-Genk and Ali, J. Frontiers in Heat and Mass Transfer (FHMT), 3, 431,

11 Rough Cu / HOPG Spreader Surface Rough Cu (1.79 μm) Spreader Width (mm) 2 7 δ (mm),.25,.5,.75, 1. Layer k x [1 7] (W/mK) 325, 5, 1, 18, 2 Layer k [1 7] z (W/mK) 5, 8, 1, 2 Bulk PF-56 Dielectric Liquid z Rough Cu, Ra = 1.79 µm Top Cu Lament t SP Thermally Anisotropic Layer (HOPG) δ Thermal Interface Material Bottom Cu Lament o Microprocessor y Adiabatic Boundary Suszko and El-Genk, Proc. Int. Tech. Conf., Paper# InterPACKICNMM , San Francisco, CA, USA, 6-9 July, 215. Suszko and El-Genk, Int. J. Thermal Sciences, 1, , 215. x Rough Cu Spreader with HOPG 227 W 132 W 163 W 88 W T sat (51.4 o C) R boil.38 o C/W o C R sp T s.95 o C/W R TOT.163 o C/W 6.3 o C o C o C 81.7 o C 76.4 o C 9.1 o C 63.9 o C R TIM.3 o C/W o C 8.4 o C 95.4 o C 66.5 o C 227 W (a) Rough Cu/HOPG Spreader (k x = 2 W/mK k z = 2 W/mK, k x / k z = 2, δ = 1. mm) 132 W (b) Rough Cu/HOPG Spreader (k x = 1 W/mK k z = 1 W/mK, k x / k z = 1, δ =.5 mm) 163 W (c) Rough Cu/HOPG Spreader (k x = 5 W/mK k z = 1 W/mK, k x / k z = 5, δ = 1. mm) 88 W (d) Plane Cu Spreader (k x = 4 W/mK k z = 4 W/mK, k x / k z = 1, δ = ) Suszko and El-Genk, Proc. Int. Tech. Conf., Paper# InterPACKICNMM , San Francisco, CA, USA, 6-9 July, 215. Suszko and El-Genk, Int. J. Thermal Sciences, 1, ,

12 Acknowledgements Financial support provided by University of New Mexico s Nuclear Power Studies (UNM-ISNPS) Contributing Researchers at UNM-ISNPS o Jack L. Parker, Ph.D., Chemical & Nuclear Engineering Department, University, August 28 o Amir F. Ali, Ph.D., Mechanical Engineering Department, University, August 213 o Arthur Suszko, Ph.D., Mechanical Engineering Department, University, August 215 Thank You for Listening Happy to Answer Questions! New Nuclear Power Mexico, Studies El-Genk- Advancements USA, in Immersion Cooling-Thermal-Management-216, the land of Denver, enchantment 24 CO 12