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Work package 3 Thermal management

Work package 3 Thermal management. 17. November 2005. Patrik Müller Andres Bolleter. Content. - Resume thermal concept - Theoretical thermal resistance - Thermal measurement - Redesign vacuum insulation - Status WP3 - Next steps - Miscellaneous to other WP. ~ 2 cm.

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Work package 3 Thermal management

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  1. Work package 3 Thermal management 17. November 2005 Patrik Müller Andres Bolleter Patrik Müller, Andres Bolleter, Aziz Ibzazene OneBat Discovery - Work Package 3: Thermal Management- Page 1

  2. Content • - Resume thermal concept - Theoretical thermal resistance - Thermal measurement - Redesign vacuum insulation - Status WP3 • - Next steps • - Miscellaneous to other WP Patrik Müller, Andres Bolleter, Aziz Ibzazene OneBat Discovery - Work Package 3: Thermal Management- Page 2

  3. ~2 cm < 1 cm ~2 cm Resume thermalconcept Vacuum insulation / insulation Air Insulation Exhaust Stack Air Vacuum insulation / insulation Fuel Exhaust Separation of in- and outlet (heat exchanger) Shape cylindrical or cubical Patrik Müller, Andres Bolleter, Aziz Ibzazene OneBat Discovery - Work Package 3: Thermal Management- Page 3

  4. Vacuum chamber Vacuum insulation Air / Gas ~ 40°C ~7e4 W/(m2) ~3e3 W/(m2) Exhaust 600 °C Stack Separation of Gases Insulation material Resume thermal concept Three insulation-possibilities • Vacuum chamber • Vacuum chamber filled with porous insulation (WDS) • Insulation material (WDS, Aerogel) Patrik Müller, Andres Bolleter, Aziz Ibzazene OneBat Discovery - Work Package 3: Thermal Management- Page 4

  5. Steel foil Vacuum-Insulation Outer Vacuum-Housing Inner Vacuum-Housing Air / Gas Exhaust Stack Patrik Müller, Andres Bolleter, Aziz Ibzazene OneBat Discovery - Work Package 3: Thermal Management- Page 5

  6. Thermally self-sustained SOFC • Comments on the paper “A thermally self-sustained micro solid oxide fuel-cell stack with high power density” * • Idea is to use the exothermic oxidation reaction to locally sustain the 500-600°C which is needed for the electrochemical reaction • Fuel utilization of experiments at ~ 1% • Therefore 99% is released as heat • OneBat-project efficiency 40% • Insulation needed * Z. Shao, S. M. Haile, J. Ahn, P. D. Ronney, Z. Zhan, S. A. Barnett, “A thermally self-sustained micro solid-oxide fuel-cell stack with high power density”, 2005, Nature Publishing Group Patrik Müller, Andres Bolleter, Aziz Ibzazene OneBat Discovery - Work Package 3: Thermal Management- Page 6

  7. Theoretical thermal resistance Simulation Measurements T2 Insulation “Stack” T1 Patrik Müller, Andres Bolleter, Aziz Ibzazene OneBat Discovery - Work Package 3: Thermal Management- Page 7

  8. Thermal measurement Aim: determination of thermal resistant Microtherm Super G Thermal conductivity 0.028 W/m*K @ 400°C Dummy stack Pmax ~ 12 W Ø 8 x 4 mm Patrik Müller, Andres Bolleter, Aziz Ibzazene OneBat Discovery - Work Package 3: Thermal Management- Page 8

  9. Measurements Silica Aerogel t2 t3 t1 t4 t1: 500°C t2: 48°C t3: 147°C t4: 23°C Dimensions: 14 x 30 x 45 mm ( : 8 °C) Patrik Müller, Andres Bolleter, Aziz Ibzazene OneBat Discovery - Work Package 3: Thermal Management- Page 9

  10. Measurements vacuum insulation t2 t3 t1 t4 t1: 500°C t2: 148°C t3: 102°C t4: 23°C Pressure: 2*10-3 mbar Dimensions: Ø 22 x 2 mm ( : 8 °C) Patrik Müller, Andres Bolleter, Aziz Ibzazene OneBat Discovery - Work Package 3: Thermal Management- Page 10

  11. Measurements vacuum insulation t2 t4 t1 t3  Ptotal: 1.6 W to keep the stack temperature Patrik Müller, Andres Bolleter, Aziz Ibzazene OneBat Discovery - Work Package 3: Thermal Management- Page 11

  12. Redesign vacuum insulation Reduced buckling • Matching thermal expansion • Pre-stressing Compact design • Dimension: adaptation on simulation results • Slimmer frame  Not tested yet: reliability Patrik Müller, Andres Bolleter, Aziz Ibzazene OneBat Discovery - Work Package 3: Thermal Management- Page 12

  13. Silica Aerogel reliability 1 hours @ 1100°C 1 hours @ 1000°C 1 hours @ 900°C 1 hours @ 800°C 1 hours @ 700°C 24 hours @ 600°C untreated SEM picture by magic Brandon, MNW ETHZ  By nowno information about long-term and insulation stability Patrik Müller, Andres Bolleter, Aziz Ibzazene OneBat Discovery - Work Package 3: Thermal Management- Page 13

  14. Status WP3 • WP 3.1: Thermal System Design • Milestones • Month 3: - thermal insulation concept (T inside = 550°C, T outside = 50°C) (ZHW) • Month 12: - system integration concept incl. thermal management concept heat exchanger design compatible with GPU designs and micro-fabrication (ZHW) • Deliverables • Month 3: - design from ZHW  NTB for fabrication ☺ ☺ • WP 3.2 Fabrication Concept of Thermal System • Milestones • Month 6: - test structures for validation of critical points of the concept (ΔT 500°C) (NTB) • Month 9: - test results of first designs • Month 12: - thermal system design demonstrator with simulated heat sources (dummy stack, reformer, post-combustor) (NTB) ☺ Patrik Müller, Andres Bolleter, Aziz Ibzazene OneBat Discovery - Work Package 3: Thermal Management- Page 14

  15. Next steps • Comparing first measurements with simulations • If discrepancies to large: why ? • Redesign of concept • Reliability vacuum insulation • Setup of second measurements: without gas-channels • Closer to concept • Comparing second measurements with simulations • Third set of measurements with simulations Patrik Müller, Andres Bolleter, Aziz Ibzazene OneBat Discovery - Work Package 3: Thermal Management- Page 15

  16. WP 1: structuring Pt-Electrode Process: combination of lift-off and shadow mask Parameter: • Development time • Resist thickness • Exposing dose • Adhesion Patrik Müller, Andres Bolleter, Aziz Ibzazene OneBat Discovery - Work Package 3: Thermal Management- Page 16

  17. WP 2: gas processing unit Test device: Foturan cannel 1 x 1 x 5 / 10 / 15 mm • Input needed for fabrication (month 6): • Final reformer design • 3 designs of post-combustor •  Drawings with all dimensions (CAD-File, dxf etc..) Patrik Müller, Andres Bolleter, Aziz Ibzazene OneBat Discovery - Work Package 3: Thermal Management- Page 17

  18. Thermo-mechanical simulations What could be gained out of simulation • Sensitivity of parameters can be evaluated • Source of stresses can be localized easier then by measurement • Design-criteria Patrik Müller, Andres Bolleter, Aziz Ibzazene OneBat Discovery - Work Package 3: Thermal Management- Page 18

  19. Thermo-mechanical simulations What inputs would these simulations require? • Geometry • Expansion coefficients • E-module, Poisson Ratio Where could thermo-mechanical simulations be used • As an additional tool for system design • To support cell-measurements, gaining insights Patrik Müller, Andres Bolleter, Aziz Ibzazene OneBat Discovery - Work Package 3: Thermal Management- Page 19

  20. Questions ? Patrik Müller, Andres Bolleter, Aziz Ibzazene OneBat Discovery - Work Package 3: Thermal Management- Page 20

  21. Thermo-mechanical simulations “ Resulting from elevated temperatures the major structural problem foreseen with planar SOFCs is their thermal stresses” * “ The stresses occurring in both cells are lying beyond the limit” * “ principal stress peak arises at the beginning of the process (startup process).” * “ Largest stress occurs in a ceramic cell fuelled with prereformed methane and it is located in the electrolyte layer at interface with the anode” * A. Selimovic, M. Kemm, T. Torisson, M. Assadi, “Steady state and transient thermal stress analysis in planar solid oxide fuel cells”, Journal of Power Sources, 2005 Patrik Müller, Andres Bolleter, Aziz Ibzazene OneBat Discovery - Work Package 3: Thermal Management- Page 21

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