The Use of Finite Element Modeling in Thermal Packaging Design
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The document discusses using finite element modeling in thermal packaging design. It describes the advantages of including thermal modeling in the design process, such as not needing prototypes and being able to test multiple variations. The presentation introduces finite element analysis and heat transfer concepts. It also provides examples of simulating standard designs and using simulation as part of the development process through case studies.
The Use of Finite Element Modeling in Thermal Packaging Design
- 1. The Use of Finite Element Modeling in Thermal Packaging Design Presented By: Landon Halloran Finite Element Analysis Engineer lhalloran@cryopak.com October 2011 www.cryopak.com www.tcpreliablegroup.com
- 2. Overview • Advantages of Thermal Modeling in the Design Process • Introduction to Finite Element Analysis • Heat Transfer • Thermal Simulation • Simulation of Standard Designs • Simulation as Part of the Development Process: Case Studies L. Halloran 12/Oct/2011 www.cryopak.com 2 www.tcpreliablegroup.com
- 3. Advantages of Including Thermal Modeling in the Design Process L. Halloran 12/Oct/2011 www.cryopak.com 3 www.tcpreliablegroup.com
- 4. Why Simulate? • No prototyping required • No inventory required • Saves on chamber time • Limitless number of temperature probes • Can identify susceptible locations in the pack-out • Accelerates the design process • Multiple variations can be tested and compared • Graphic rendering for customers L. Halloran 12/Oct/2011 www.cryopak.com 4 www.tcpreliablegroup.com
- 5. Introduction to Finite Element Analysis L. Halloran 12/Oct/2011 www.cryopak.com 5 www.tcpreliablegroup.com
- 6. A Wide Variety of Applications L. Halloran 12/Oct/2011 www.cryopak.com 6 www.tcpreliablegroup.com
- 7. What is “Finite Element Analysis”? • A computational method for performing analysis of a physical system. • A tool for simulation of the mechanical, thermal, rheological, electronic or other response of a system. • Involves the division of a body into smaller domains or “elements”. • The applicable equations describing the physics of the system can then be evaluated for each of the elements. L. Halloran 12/Oct/2011 www.cryopak.com 7 www.tcpreliablegroup.com
- 8. A Simple Example in 2-D: I -10 W/m2 40 C 10 C 10 W/m2 An odd-shaped sheet of HDPE is A CAD model of the sheet is divided into subjected to a heat input and output, as smaller components by meshing. well as constant temperatures at two places. L. Halloran 12/Oct/2011 www.cryopak.com 8 www.tcpreliablegroup.com
- 9. A Simple Example in 2-D: II -10 W/m2 40 C 10 C 10 W/m2 Constraints such as fixed temperatures The simulation algorithm runs with are defined in the simulation set-up. multiple iterations and calculates the resulting temperature throughout the object. L. Halloran 12/Oct/2011 www.cryopak.com 9 www.tcpreliablegroup.com
- 10. Heat Transfer L. Halloran 12/Oct/2011 www.cryopak.com 10 www.tcpreliablegroup.com
- 11. Heat Transfer: I • There are three methods of heat transfer between two objects: – Conduction • Transfer of thermal energy through direct contact • Fourier’s Law: q = kAΔT/Δx – Convection • Transfer of thermal energy through a fluid • Can be free or forced • q = hcAΔT – Radiation • Transfer of energy through electromagnetic radiation emitted by all objects with temperature > 0 K (-273 C) • Hotter objects emit more power: P = σT4 L. Halloran 12/Oct/2011 www.cryopak.com 11 www.tcpreliablegroup.com
- 12. Heat Transfer: II • In thermal packaging, the primary method of heat transfer is conduction • Free convection by air cells in a packaging configuration also have a significant effect • To properly treat both mechanisms of heat transfer, a hybrid thermal-fluid solver is required L. Halloran 12/Oct/2011 www.cryopak.com 12 www.tcpreliablegroup.com
- 13. Thermal Simulation L. Halloran 12/Oct/2011 www.cryopak.com 13 www.tcpreliablegroup.com
- 14. Thermal Simulation: I • In order for thermal simulation to be an integral part of the design process, simulation results must be validated. • In thermal/flow simulation, there are multiple user parameters and options that govern the thermodynamics of the modelled system. • Many of these can be measured directly, however many must be determined through simulated experiment L. Halloran 12/Oct/2011 www.cryopak.com 14 www.tcpreliablegroup.com
- 15. Thermal Simulation: II • Finding the correct simulation parameters and making the appropriate geometric approximations present the biggest challenges in obtaining simulation results that accurately replicate test results. • A standard set of processes, options and parameters has been developed leading to acceptable simulation results for existing and new thermal packaging designs. L. Halloran 12/Oct/2011 www.cryopak.com 15 www.tcpreliablegroup.com
- 16. Models of Individual Components • Database of part drawings • Can be used as components in assembly models and simulations. • Geometry is generally simplified for simulation www.cryopak.com 16 www.tcpreliablegroup.com
- 17. Simulation Parameters and Options • Density, specific heat capacity, and thermal conductivity • Convective heat transfer multiplier • Radiative and convective thermal coupling to ambient environment • Conductive contact between tangent faces • Solver parameters • Others L. Halloran 12/Oct/2011 www.cryopak.com 17 www.tcpreliablegroup.com
- 18. Parameterization Simulation Effect of Convective Heat Transfer Multiplier (TS-48 Large Canadian with ATP Summer 48H Profile) 12 11 10 9 Temperature (C) 8 Test - Probe 7 Test - Probe 10 7 Simulation - CHTM=1 6 Simulation - CHTM=0.5 5 Simulation - CHTM=0.25 4 Simulation - CHTM=0.125 3 2 0 12 24 36 48 Time (h) The extent to which the convective heat transfer multiplier affects results can be readily seen here. L. Halloran 12/Oct/2011 www.cryopak.com 18 www.tcpreliablegroup.com
- 19. Materials: I • For valid simulation results, accurate values of several physical properties of each material are required: – Density (ρ) – Specific heat capacity (cp) – Thermal conductivity (k) • For PCMs, values for these properties are required both above and below the phase-change temperature, as well as: – Latent heat capacity (L) – Phase change temperature (TPC) • Some of these material properties exhibit a significant variation over the temperature range of interest and must be programmed as temperature-dependent tables. L. Halloran 12/Oct/2011 www.cryopak.com 19 www.tcpreliablegroup.com
- 20. Materials: II • PCMs • Insulators – Water-based Cryogels – Expanded Polystyrene – Phase-5 (EPS) – Phase-22 – Low, medium and high density – Phase-27 – 20-Below Gel – Polyurethane (PUR) – Dry Ice – Polyisocyanurate (PIR) – Vacuum Insulated Panels • Containers – Corrugated Cardboard • Others – HDPE/LDPE L. Halloran 12/Oct/2011 www.cryopak.com 20 www.tcpreliablegroup.com
- 21. Simulation of Standard Designs L. Halloran 12/Oct/2011 www.cryopak.com 21 www.tcpreliablegroup.com
- 22. Simulations of Standard Designs • TimeSaver 24 Small (US) • TimeSaver 48 Premium Medium (US) • TimeSaver 48 Large (Canada) • TimeSaver 96 PUR Small (US) L. Halloran 12/Oct/2011 www.cryopak.com 22 www.tcpreliablegroup.com
- 23. TimeSaver-24 Small L. Halloran 12/Oct/2011 www.cryopak.com 23 www.tcpreliablegroup.com
- 24. Design Details • 12 CG1181 gel packs. • Was simulated both with and without a convective heat transfer coefficient multiplier to effectively model the configuration with and without bubble wrap. • Gel packs were modeled with a simplified geometry and with an averaged conductive heat transfer coefficient. L. Halloran 12/Oct/2011 www.cryopak.com 24 www.tcpreliablegroup.com
- 25. Summer Simulation Results 40 35 30 25 Temperature (°C) 20 15 10 5 0 0 6 12 18 24 Time (h) Test #1 Test #2 Test #3 Solution 1 SIM (with HTCM=1/8) Solution 3 SIM ISTA Summer 24H “w/ bubble-wrap” “w/o bubble-wrap” L. Halloran 12/Oct/2011 www.cryopak.com 25 www.tcpreliablegroup.com
- 26. Winter Simulation Results 20 15 10 Temperature (°C) 5 0 0 6 12 18 24 -5 -10 -15 Time (h) Test #1 Test #2 Test #3 Solution 2 SIM (with HTCM=1/8) Solution 4 SIM ISTA Winter 24H “w/ bubble-wrap” “w/o bubble-wrap” L. Halloran 12/Oct/2011 www.cryopak.com 26 www.tcpreliablegroup.com
- 27. TimeSaver-48 Medium Premium L. Halloran 12/Oct/2011 www.cryopak.com 27 www.tcpreliablegroup.com
- 28. Model Details • Presence of two different PCMs, Phase-5 and water-based gels, presents additional challenges in obtaining accurate simulation results. • To account for attenuated convective heat transfer due to blockage from bubble-wrap , a convective heat transfer coefficient multiplier was used. • Conduction assumed perfect between EPS layers Cut-away view of 48H Winter Simulation • Effective conductive transfer coefficient used for other surface-to-surface contact L. Halloran 12/Oct/2011 www.cryopak.com 28 www.tcpreliablegroup.com
- 29. Simulation Results - Winter TimeSaver 48 Medium Premium - Winter Minimum Load 20 15 10 Temperature (C) 5 0.61 C 0 0 12 24 36 48 -5 -10 -15 Time (h) Qualification Test #1 Qualification Test #2 Qualification Test #3 Simulation Payload T ISTA Winter 48H L. Halloran 12/Oct/2011 www.cryopak.com 29 www.tcpreliablegroup.com
- 30. TimeSaver-48 Large Canadian L. Halloran 12/Oct/2011 www.cryopak.com 30 www.tcpreliablegroup.com
- 31. Model Details • Customer expressed interest in using the design but as concerned about the performance against their own temperature profile. Final Temperature - Winter • In order to facilitate the conversation the shipper was modeled and tested against the profile in question. • Gel packs are the sole PCMs. Modeled geometry was idealized. • Effective conductive heat transfer coefficient used • Effect of convective heat transfer multiplier was extensively investigated Final Temperature - Summer with this model. L. Halloran 12/Oct/2011 www.cryopak.com 31 www.tcpreliablegroup.com
- 32. Simulation Results - Summer Timesaver-48 Large Canadian Assembly 001 – Summer – SIM 001: Solution 10 - ATP Canadian Summer 48H 40 35 30 25 Temperature (C) 20 Payload Test Temperature Payload Simulation Temperature 15 Temperature Profile 10 5 0 0 12 24 36 48 Time (h) L. Halloran 12/Oct/2011 www.cryopak.com 32 www.tcpreliablegroup.com
- 33. Simulation Results - Winter Timesaver-48 Large Canadian Assembly 001 - SIM 001: Solution 2 - ATP Canadian Winter 48H 25 20 15 10 Temperature (C) 5 0 0 6 12 18 24 30 36 42 48 -5 -10 -15 -20 -25 Time (h) Temp Probe 1 (C) Temp Probe 2 (C) Payload Simulation (C) External Profile Temperature L. Halloran 12/Oct/2011 www.cryopak.com 33 www.tcpreliablegroup.com
- 34. Simulation Results – Winter (Customer-supplied profile) Timesaver-48 Large Canadian Assembly 001 - SIM 001: Solution 3 - Lynden Winter 51H 25 20 15 10 5 Temperature (C) 0 0 12 24 36 48 -5 -10 -15 -20 -25 -30 Time (h) External Temperature Profile Payload Center Temperature L. Halloran 12/Oct/2011 www.cryopak.com 34 www.tcpreliablegroup.com
- 35. TimeSaver-96 Small PUR L. Halloran 12/Oct/2011 www.cryopak.com 35 www.tcpreliablegroup.com
- 36. Model Details • PCMs are Phase-5 bottles and gel bottles. • Again, effective conductive heat transfer coefficient used to model imperfect conduction between surfaces L. Halloran 12/Oct/2011 www.cryopak.com 36 www.tcpreliablegroup.com
- 37. Simulation Results TimeSaver-96 Small PUR - Winter 20 15 10 Temperature (C) 5 0 0 12 24 36 48 60 72 84 96 -5 -10 -15 Time (h) Qualification Test #1 Qualification Test #2 Qualification Test #3 Payload (Sol'n 1) Payload (Sol'n 3) ISTA Winter 96H Convection Heat Transfer Multiplier : 1/8 (sol’n 1) & 1/16 (sol’n 3) L. Halloran 12/Oct/2011 www.cryopak.com 37 www.tcpreliablegroup.com
- 38. Simulation as Part of the Development Process: Case Studies L. Halloran 12/Oct/2011 www.cryopak.com 38 www.tcpreliablegroup.com
- 39. Modifications to Existing Pallet Shipper Design L. Halloran 12/Oct/2011 www.cryopak.com 39 www.tcpreliablegroup.com
- 40. Model Details • In order make the REPAK 120 design more robust, the performance of new bottle configurations was examined. • We wanted to examine the effect of adding an extra bottle to each sleeve. • By simulating this new configuration, significant prototyping labour and chamber time were avoided. • Other options may be further explored by modifying the model. L. Halloran 12/Oct/2011 www.cryopak.com 40 www.tcpreliablegroup.com
- 41. New Panels 3-Bottle Panel 4-Bottle Panel L. Halloran 12/Oct/2011 www.cryopak.com 41 www.tcpreliablegroup.com
- 42. Simulation Results - Summer 55 50 45 40 • Simulation results 35 from new designs Temperature (°C) 30 compared with test 25 results from old 20 design 15 10 5 0 REPAK 12- Bottom Corner REPAK 13-Bottom Center 0 24 48 Time (h) 72 96 120 REPAK 14-Top Corner 3-Bottle SIM - Payload Center REPAK 15-Top Center 4-Bottle SIM - Payload Center REPAK Summer 120H L. Halloran 12/Oct/2011 www.cryopak.com 42 www.tcpreliablegroup.com
- 43. Simulation Results - Winter 25 20 15 • Simulation 10 results from 5 new designs compared with Temperature (°C) 0 0 24 48 72 96 120 test results from -5 old design. -10 • Notably, the -15 initial payload -20 temperature in the test run was -25 less than 5 C. -30 Time (h) 3-Bottle SIM - Payload Center 4-Bottle SIM - Payload Center REPAK 8-Top Corner REPAK 6-Bottom Corner REPAK 7-Bottom Center REPAK 9-Top Center REPAK Winter 120H L. Halloran 12/Oct/2011 www.cryopak.com 43 www.tcpreliablegroup.com
- 44. Pallet Shipper Concept L. Halloran 12/Oct/2011 www.cryopak.com www.tcpreliablegroup.com 44
- 45. Overview of Project • A large distributor of medical products expressed interest in a custom pallet shipper capable of transporting a wide variety of temperature-sensitive products for at least 48 hours. • Customer was very concerned with volume optimization and reusability. • To help the customer make a more informed decision, the effect of varying PIR wall thickness was modelled. • Results were obtained within 2 weeks with no prototyping cost. • Prototype construction and testing would be very costly and take long to complete. Simulation allows us to rapidly evaluate the feasibility of various designs. The results can then be used to help us improve the ¼ view used to exploit symmetry and decrease calculation time design. L. Halloran 12/Oct/2011 www.cryopak.com 45 www.tcpreliablegroup.com
- 46. Simulation Parameters • Wall layers: • 1/4" HDPE • different thicknesses of PIR were tested (40, 60, and 80 mm) • 1/2" Phase-5 • 1/4" HDPE • Simulated payload: idealized non-fluid material with thermal properties of a bulk air/water blend. • Temperature profile is a constant 20 C (68 F) for 3 days • Worst-case (top corner) and best-case (center of XY face) points chosen from the payload surface for post-simulation analysis L. Halloran 12/Oct/2011 www.cryopak.com 46 www.tcpreliablegroup.com
- 47. Simulation Example 80mm PIR walls, Temperature after 72 hours L. Halloran 12/Oct/2011 www.cryopak.com 47 www.tcpreliablegroup.com
- 48. Temperature Response of Payload 12.00 in 20°C (68°F) Flat-line Simulation 11.00 10.00 Temperature (C) 9.00 8.00 7.00 6.00 5.00 0.00 8.00 16.00 24.00 32.00 40.00 48.00 56.00 64.00 72.00 Time (hour) 40mm Top Corner 40mm Middle of XZ Face 60mm Top Corner 60mm Middle of XZ Face 80mm Top Corner 80mm Middle of XZ Face L. Halloran 12/Oct/2011 www.cryopak.com 48 www.tcpreliablegroup.com
- 49. Effect of PIR Wall Thickness on Performance PIR Wall Payload Top Payload Center of Thickness Thickness x ID y ID z ID Volume Volume Corner Failure Face Failure Time (mm) (inches) (in) (in) (in) (in3) (L) time (h) (h) 40 2.57 35.85 43.85 72.85 114524 1876 30 47 60 3.36 34.28 42.28 71.28 103279 1692 34 55 80 4.15 32.70 40.70 69.70 92768 1520 62 72+ • Increased PIR thickness has the expected effect of prolonging the period that the payload can be transferred at its safe temperature range of 2 – 8 C. • The trade-off for longer effectiveness is a decreased payload volume. • By shipping products with lower initial temperatures, the period of effectiveness can be prolonged. • Many factors, especially the dimensions and the composition of the payload, can affect these times. L. Halloran 12/Oct/2011 www.cryopak.com 49 www.tcpreliablegroup.com
- 50. Conclusions • The results of finite element analysis have been demonstrated and verified with existing designs. • The use of finite element thermal analysis in the design process presents multiple advantages to our customers: – Comparison of multiple design variations – Rapid analysis of changes to designs – Identification of susceptible locations in the pack-out – Robust design and simulation of large or complex pack- outs that would entail large cost or time to prototype – Graphical output of models and results L. Halloran 12/Oct/2011 www.cryopak.com 50 www.tcpreliablegroup.com
- 51. Thank-you for your attention! Any questions? Landon Halloran lhalloran@cryopak.com L. Halloran 12/Oct/2011 www.cryopak.com 51 www.tcpreliablegroup.com