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Air Cooling Design for Machine Components

Air Cooling Design for Machine Components . Presenter: Peter van Emmerik Faculty Advisor: Dr. LeRoy Alaways Department of Mechanical Engineering Villanova University. Air Cooling Design for Machine Components . Problem Statement.

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Air Cooling Design for Machine Components

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  1. Air Cooling Design for Machine Components

  2. Presenter: Peter van Emmerik Faculty Advisor: Dr. LeRoy Alaways Department of Mechanical Engineering Villanova University Air Cooling Design for Machine Components

  3. Problem Statement • Design a cooling system to reduce the steady state temperature of a given heated structure from 100 C to 50 C using compressed air • Accomplish goal using less than 18 normal liters per minute. • Create both finite element analysis (FEA) and computational fluid dynamics (CFD) simulation models validated by empirical results

  4. Background • As the demands on modern machinery used for high accuracy positioning systems grow, greater emphasis is placed on thermal control • Bearings systems can be sensitive to thermal gradations affecting life • Machine component C.T.E. differences coupled with uniform and non uniform thermal excursions may lead to accuracy issues

  5. Background • Heated Fixture Film Heater Stand-offs (SS) Thermocouple locations Heat Block (Al) Base (Al) Fixture representative of linear servo motor

  6. Methodology Advantages of using compressed air

  7. Methodology • Three delivery methods examined • Log Manifold • Pinched Tube • Air Knife • Two orientations to target surface • Cross Flow • Impinging Flow

  8. Methodology - Designs Log Manifold • Simple tube • Capped end • Cross drilled

  9. Methodology - Designs Pinched Tube • Simple tube • Pinched End • Shapes flow • Increases velocity

  10. Methodology - Designs Air Knife • Machined Manifold • Wide Slit Exit • Enhanced Air Entrainment Cover Spacer Manifold

  11. Apparatus • Test Equipment • Thermocouples k-type • Data Collection Box • Air Flow Meter • Heater Voltage Controller • Arrangements • Cross Flow • Impinging Flow

  12. Test Procedure • Apply power • Reach un-cooled steady state temperature • Turn on air delivery system • Reach cooled steady state temperature • Repeat for all designs and orientations

  13. Results Un-cooled baseline

  14. Results Cross Flow

  15. Results Steady State Temperature Comparison *Design Goal: 50 deg C Air Consumption: 17.2 nL/min for all tests

  16. Simulation • Simulation used empirical data to build accurate simulation model • Determine thermal conductance at interfaces • 2000W/m2-C • Heat loading from heater • 15.5 Watts • Convective heat transfer coefficient (h) • 6.5W/m2-C for natural convection

  17. Simulation – Un-cooled Correlation • Transient Un-cooled FEA vs Empirical

  18. Simulation – Un-cooled Good correlation between simulations and empirical results CFD Tmax = 108 C Empirical Tmax = 107 C FEA Tmax = 110 C

  19. Simulation – Heat Transfer Coefficient FEA predicted havg = 6.5 W/m2-C CFD predicts havg = 6.0 W/m2-C Natural Convection 0-20 W/m2-K Forced Convection 0-200 W/m2-K

  20. Simulation – Cooled (pinched tube) Velocity distribution through tube center plane Temperature distribution through tube center plane (top view)

  21. Simulation – Streamlines Streamlines colored by temperature Natural Convection Forced Convection

  22. Results- Simulation Average delta between CFD and empirical results is <5%

  23. Conclusion • Air knife and pinched tube met design goal temperature of 50 C or lower • Packaging and cost may dictate which design is most practical • FEA/CFD heat transfer simulation can be correlated to empirical results and then used as model for future designs. Approximate 5% difference between CFD and empirical results

  24. Future Work • Air exit geometry sensitivity study • Positional and orientational sensitivity study • Mesh density sensitivity study for FEA and CFD simulations

  25. Schedule

  26. Budget • All test apparatus provided courtesy of Kulicke & Soffa Industries. • All materials for fixture fabrication provided courtesy of Kulicke & Soffa Industries. • Film heater only purchased item: $39.99 • Total Expenditure: 39.99 • All materials reusable or recyclable for minimal environmental impact. • No exposure to hazardous conditions during testing

  27. Bibliography Fox, McDonald and Pritchard, 2004, Introduction to Fluid Mechanics, John Wiley and Sons Inc., Incropera, Dewitt, Bergman and Lavine, 2007, Fundamentals of Heat and Mass Transfer, John Wiley and Sons Inc., D.-Y. Lee, K. Vafai, 1998, “Comparative analysis of jet impingement and micro channel cooling for high heat flux applications”, International Journal of Heat and Mass Transfer, Material Web, materials data website, http://www.matweb.com/

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