INVESTIGATION OF AIR-COOLED CONDENSERS FOR WASTE HEAT DRIVEN ABSORPTION HEAT PUMPS A Dissertation Presented to The Academic Faculty by Subhrajit Chakraborty In Partial Fulfillment of the Requirements for the Degree Master of Science in Mechanical Engineering Georgia Institute of Technology May 2017 COPYRIGHT © 2017 BY SUBHRAJIT CHAKRABORTY INVESTIGATION OF AIR-COOLED CONDENSERS FOR WASTE HEAT DRIVEN ABSORPTION HEAT PUMPS Approved by: Dr. Srinivas Garimella, Advisor School of Mechanical Engineering Georgia Institute of Technology Dr. S. Mostafa Ghiaasiaan School of Mechanical Engineering Georgia Institute of Technology Dr. Sheldon M. Jeter School of Mechanical Engineering Georgia Institute of Technology Date Approved: April 25, 2017 To my mother iii ACKNOWLEDGEMENTS I would like to express my deepest gratitude to my advisor, Dr. Srinivas Garimella, for his continuous support and guidance. His direction was invaluable in research- and career-related junctures, and I look forward to applying those skills in future endeavors. I would like to thank past and present members of the Sustainable Thermal Systems Lab, particularly, Dr. Alex Rattner, Dr. Jared Delahanty, David Forinash, Dhruv Hoysall, Marcel Staedter, Dr. Darshan Pahinkar, Anurag Goyal, and Allison Mahvi for their technical guidance, willingness to review my work, and answer my questions. I would specifically like to acknowledge Victor Aiello’s help in fabrication of my components and test facility. In addition, I would like to thank Daniel Kromer, Jennifer Lin, Daniel Boman, Khoudor Keniar, Taylor Kunke, Bachir El Fil and Girish Kini for their scientific counsel and comradery. I am very thankful to my family and friends, without their help and support I would not have been able to complete this work. My parents and sister have bestowed me with immense love, teachings and unconditional support, which acted as the source of all my inspiration and determination. I do indeed feel blessed to have a company of friends, who have made me strive to be a better person by emulating their positive characteristics. I would like to thank my friends Arpan Kusari, Rohini Swaminathan, Cannon Cheng, Srinivas Hanasoge, and Kaivalya Bakshi for their advice and moral support. I must take this opportunity to thank Jayati Athavale and Girish Kini for assisting me during the later part of my work and keeping me motivated through stressful times. Finally, I would like to thank all the well-wishers, who hoped and prayed for my success. iv TABLE OF CONTENTS ACKNOWLEDGEMENTS .............................................................................................. IV LIST OF TABLES ............................................................................................................ IX LIST OF FIGURES ............................................................................................................ X LIST OF SYMBOLS AND ABBREVIATIONS ............................................................ XV SUMMARY ..................................................................................................................... XX CHAPTER 1: INTRODUCTION ....................................................................................... 1 1.1 Small Scale Absorption Heat Pump .................................................................... 4 1.2 Condenser in Compact Absorption Systems....................................................... 7 1.3 Scope of Present Study ....................................................................................... 9 1.4 Thesis Organization .......................................................................................... 14 CHAPTER 2: LITERATURE REVIEW .......................................................................... 16 2.1 Tube-Side Models ............................................................................................. 16 2.1.1 Two–phase flow regime ................................................................................ 17 2.1.2 Condensation................................................................................................. 20 2.1.3 Effect of zeotropic mixture ........................................................................... 25 2.1.4 Two-phase pressure drop .............................................................................. 29 2.2 Air-Side Models ................................................................................................ 31 2.2.1 Round-tube corrugated-fin condenser ........................................................... 32 2.2.2 Multi-pass tube-array condenser ................................................................... 34 v 2.3 Air-Coupled Heat Exchanger Studies ............................................................... 40 2.4 Summary ........................................................................................................... 41 CHAPTER 3: MODELING APPROACH ....................................................................... 43 3.1 General Modeling Architecture ........................................................................ 43 3.2 Round-Tube Corrugated-Fin Condenser........................................................... 57 3.2.1 Tube side modeling ....................................................................................... 60 3.2.1.1 Flow regime .......................................................................................... 60 3.2.1.2 Heat transfer .......................................................................................... 64 3.2.1.3 Pressure drop ......................................................................................... 75 3.2.2 Air-side modeling ......................................................................................... 79 3.2.2.1 Heat transfer .......................................................................................... 82 3.2.2.2 Pressure drop ......................................................................................... 83 3.2.3 Thermal resistance ........................................................................................ 86 3.3 Multi-Pass Tube-Array Condenser ................................................................... 88 3.3.1 Tube-side modeling ...................................................................................... 92 3.3.1.1 Flow regime .......................................................................................... 92 3.3.1.2 Heat transfer .......................................................................................... 94 3.3.1.3 Pressure drop ......................................................................................... 96 3.3.2 Air-side modeling ......................................................................................... 97 3.3.2.1 Heat transfer .......................................................................................... 99 3.3.2.2 Pressure drop ....................................................................................... 105 3.3.3 Thermal resistance ...................................................................................... 107 vi CHAPTER 4: EXPERIMENTAL APPROACH ............................................................ 110 4.1 Air-Coupled Condenser Fabrication ............................................................... 110 4.1.1 Round-tube corrugated-fin condenser ......................................................... 110 4.1.2 Multi-pass tube-array condensers ............................................................... 116 4.2 Air-Cooled Condenser Experimental Test Setup ............................................ 120 4.2.1 Ammonia-water test facility ....................................................................... 120 4.2.2 Air-handling unit ......................................................................................... 122 4.2.3 Equipment and instrumentation .................................................................. 124 4.3 Experimental Procedure .................................................................................. 129 4.3.1 Charging and discharging procedure .......................................................... 129 4.3.2 Startup and testing procedure...................................................................... 134 CHAPTER 5: RESULTS AND DISCUSSION.............................................................. 137 5.1 Round-Tube Corrugated-Fin Condenser......................................................... 140 5.1.1 Heat transfer ................................................................................................ 140 5.1.2 Pressure drop ............................................................................................... 145 5.2 Multi-Pass Tube-Array Condenser ................................................................. 151 5.2.1 Heat transfer ................................................................................................ 151 5.2.2 Pressure drop ............................................................................................... 164 CHAPTER 6: CONCLUSIONS AND RECOMMENDATIONS .................................. 169 6.1 Conclusions ..................................................................................................... 169 6.2 Recommendations ........................................................................................... 171 6.2.1 Experimental and analytical investigation .................................................. 171 vii 6.2.2