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CFD Simulation of Multi-Dimensional Effects in Inertance Tube Pulse Tube Cryocoolers

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CFD Simulation of Multi-Dimensional Effects in Inertance Tube Pulse Tube Cryocoolers CFD Simulation of Multi-Dimensional Effects in Inertance Tube Pulse Tube Cryocoolers A Thesis Presented to The Academic Faculty By Jeesung (Jeff) Cha In Partial Fulfillment Of the Requirements for the Degree Master of Science in Mechanical Engineering Georgia Institute of Technology May, 2004 Copyright © Jeesung Cha and 2004 CFD Simulation of Multi-Dimensional Effects in Inertance Tube Pulse Tube Cryocoolers Approval S. Mostafa Ghiaasiaan, Chairman, Mechanical Engineering Prateen V. Desai, Mechanical Engineering Carl S. Kirkconnell, Raytheon Date Approved: 4/7/2004 ACKNOWLEDGEMENTS First, I would like to show my greatest gratitude to my advisors Dr. S. Mostafa Ghiaasiaan and Dr. Prateen V. Desai at Georgia Institute of Technology for their endless support and inputs which led to my successful graduate journey. I would also like to thank Dr. Carl S. Kirkconnell of Raytheon Systems for supporting me and exposing me to the research field of cryocoolers since the beginning of this project. Personally, I want to show my greatest thanks to my predecessor Dr. Jeremy P. Harvey for his unconditional support. With his inputs day and night, weekdays and weekends, in every occasion he has been there to share his knowledge with me and to motivate me to further excel in my research. I thank you again Jeremy. It has been a rollercoaster ride ever since the start of this research. During that time, my comfort came from friends here at Georgia Tech. They are Keunhan Park, Hyunjin Lee, Bongjae Lee, Dan Hays, J.R Aspinwall, Muhammad Khalid Akbar, and my best friend David Gutlay III. I thank you all for sharing my stressful and tough times with me. I also like to thank my former Purdue University buddies, HK Lee and Jongsoo Mok for their support. Lastly, my work towards the completion of the degree wouldn’t have been possible without my unsung supporters. They are the members of my family, my greatest asset of all. Without them and their support there is no way I would be standing here today. Thank you again, Dad (Jung E Cha), Mom (Myung H. Cha), Jessica and MJ, Jason and Mimi. You guys are the pure driving force of my life. ¡ TABLE OF CONTENTS ACKNOWLEDGEMENTS......................................................................................... III LIST OF TABLES ...................................................................................................VIII LIST OF FIGURES ...................................................................................................IX SUMMARY.......................................................................................................... XVIII INTRODUCTION AND BACKGROUND .................................................................... 1 1.1 INTRODUCTION................................................................................................... 1 1.2 BACKGROUND .................................................................................................... 7 1.2.1 History of Cryogenic Refrigerators.............................................................. 7 1.2.2 Pulse Tube Cryocoolers ............................................................................. 9 1.2.3 Application of PTCs.................................................................................. 10 1.3 REVIEW OF RECENT LITERATURE ...................................................................... 11 EXPERIMENTAL SETUP AND OPERATIONS ........................................................ 17 2.1 EXPERIMENTAL SETUP...................................................................................... 17 2.2 COMPONENT DESCRIPTIONS ............................................................................. 21 2.2.1 Compressor ............................................................................................. 21 2.2.2 Warm Heat Exchanger 1 (WHX1)............................................................. 21 ¡ 2.2.3 Regenerator ............................................................................................. 22 2.2.4 Cold Heat Exchanger (CHX) .................................................................... 23 2.2.5 Pulse Tube ............................................................................................... 23 2.2.6 Warm Heat Exchanger 2 (WHX2)............................................................. 23 2.2.7 Orifice Valve, Inertance Tube and Surge Volume...................................... 24 2.3 PULSE TUBE CRYOCOOLER OPERATION PRINCIPLES .......................................... 25 MODELING AND GOVERNING EQUATIONS......................................................... 32 3.1 COMPUTATIONAL FLUID DYNAMICS (CFD).......................................................... 32 3.2 MODELING OF INERTANCE TUBE PULSE TUBE CRYOCOOLERS............................. 34 3.3 GOVERNING EQUATIONS................................................................................... 37 3.4 DIMENSIONS, BOUNDARY AND INITIAL CONDITIONS OF THE SIMULATED SYSTEMS . 49 RESULTS AND DISCUSSIONS .............................................................................. 54 4.1 CASE 1............................................................................................................ 54 4.2 CASE 2............................................................................................................ 59 4.3 CASE 3............................................................................................................ 61 4.4 CASES 4-6....................................................................................................... 66 4.5 CONVERGENCE ................................................................................................ 72 4.6 MULTI-DIMENSIONAL FLOW EFFECTS................................................................. 75 ¡¢ CONCLUSIONS AND RECOMMENDATIONS FOR FUTURE WORK..................... 83 5.1 CONCLUDING REMARKS.................................................................................... 83 5.2 RECOMMENDATIONS FOR FUTURE WORK........................................................... 84 APPENDICES ......................................................................................................... 86 A1. STIRLING CRYCOOLER ..................................................................................... 86 A2. FLUENT USER DEFINED FUNCTIONS.................................................................. 88 A2.1 UDF Compressor Code ............................................................................ 88 REFERENCES........................................................................................................ 89 ¡£ LIST OF TABLES Table 1: GIT OPTC Test Data .................................................................................. 20 Table 2: Component Radiuses................................................................................. 50 Table 3: Boundary Conditions and Initial Conditions for MOD1 and MOD2.............. 53 Table 4: Cycle Averaged Energy Balance Results ................................................... 74 ¡£ LIST OF FIGURES Figure 1 : Schematic Configuration of the Basic Pulse Tube Cryocoolers (BPTC) ..... 2 Figure 2 : Schematic Configuration of the Orifice Pulse Tube Cryocooler (OPTC)..... 4 Figure 3 : Schematic Configuration of the Inertance Tube Pulse Tube Cryocooler (ITP TC)...................................................................................................................... 5 Figure 4 : GIT OPTC Experimental Apparatus View 1.............................................. 18 Figure 5 : GIT OPTC Experimental Apparatus View 2.............................................. 18 Figure 6: GIT OPTC Experimental Apparatus View 3............................................... 19 Figure 7: Schematic of the Simple Vapor Compression Cycle ................................. 25 Figure 8 : Macroscopic Energy Balance .................................................................. 27 Figure 9 : Energy Balance of System Components.................................................. 28 Figure 10 : Gas Temperature and Mass Flow Rate Phase Shift Relationships......... 30 Figure 11 : 3-Dimensional View of the ITPTC (L/D=12)pt.......................................... 33 Figure 12 : 3-Dimensional View of the ITPTC (L/D=2)pt. .......................................... 33 Figure 13 : Meshed 2-D Axi- symmetric Large Diameter Model Generated by the Gambit Software .............. 35 Figure 14 : 2-Dimensional Axi-symmetric Mesh for MOD1....................................... 38 Figure 15 : 2-Dimensional Axi-symmetric Mesh for MOD2....................................... 39 ¤ Figure 16 : 2-Dimensional Axi-symmetric Coordinate System.................................. 44 Figure 17 : Dimensions of the PTC System MOD1. (All dimensions are in m.) ........ 50 Figure 18 : Dimensions of the PTC System MOD2. (All dimensions are in m.) ........ 51 Figure 19 : CHX Temperature for Case 1 (Adiabatic Wall B.C.) and Case 2 (1W cooli ng load)............................................................................................................. 55 Figure 20 : Cycle- average Temperature Distribution for Case 1 (Adiabatic B.C.) .... 56 Figure 21 : Snapshot of Density Distribution for Case 1 (Adiabatic Wall B.C.) ......... 57 Figure 22 : Temperature Contours for Case 1 (Adiabatic Wall B.C.) [K]. .................. 58 Figure 23 : Snapshot of Density Contours for Case 1 (Adiabatic Wall B.C.) [kg/m3].58 Figure 24 : Temperature Contour for Case 2 (1W Cooling Load) [K].......................
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