Experimental Study of System Performance Improvements in Transcritical R744 Systems with Applications to Bottle Coolers

University of Illinois at Urbana-Champaign Air Conditioning and Refrigeration Center A National Science Foundation/University Cooperative Research Center Experimental Study of System Performance Improvements in Transcritical R744 Systems with Applications to Bottle Coolers J. M. DeAngelis and P. S. Hrnjak ACRC CR-57 March 2005 For additional information: Air Conditioning and Refrigeration Center University of Illinois Mechanical & Industrial Engineering Dept. 1206 West Green Street Urbana, IL 61801 (217) 333-3115 The Air Conditioning and Refrigeration Center was founded in 1988 with a grant from the estate of Richard W. Kritzer, the founder of Peerless of America Inc. A State of Illinois Technology Challenge Grant helped build the laboratory facilities. The ACRC receives continuing support from the Richard W. Kritzer Endowment and the National Science Foundation. The following organizations have also become sponsors of the Center. Arçelik A. S. Behr GmbH and Co. Carrier Corporation Cerro Flow Products, Inc. Copeland Corporation Daikin Industries, Ltd. Danfoss A/S Delphi Thermal and Interior Embraco S. A. Ford Motor Company Fujitsu General Limited General Motors Corporation Hill PHOENIX Hydro Aluminum Adrian, Inc. Ingersoll-Rand/Climate Control Lennox International, Inc. LG Electronics, Inc. Manitowoc Ice, Inc. Modine Manufacturing Co. Novelis Global Technology Centre Parker Hannifin Corporation Peerless of America, Inc. Samsung Electronics Co., Ltd. Sanden Corporation Sanyo Electric Co., Ltd. Tecumseh Products Company Trane Visteon Automotive Systems Wieland-Werke, AG Wolverine Tube, Inc. For additional information: Air Conditioning & Refrigeration Center Mechanical & Industrial Engineering Dept. University of Illinois 1206 West Green Street Urbana, IL 61801 217 333 3115 Table of Contents Page List of Figures ............................................................................................................... v List of Tables .............................................................................................................. viii Nomenclature ............................................................................................................... ix Chapter 1. Introduction................................................................................................. 1 Chapter 2. Characterization of a R134a Bottle Cooler ............................................... 2 2.1 Introduction..................................................................................................................................... 2 2.2 System Description ........................................................................................................................ 3 2.3 Experimental Results ..................................................................................................................... 5 2.3.1 Experimental Facility .............................................................................................................................5 2.3.2 Test Matrix .............................................................................................................................................9 2.3.3 Charge Determination ..........................................................................................................................10 2.3.4 System Performance.............................................................................................................................11 2.4 Conclusions .................................................................................................................................. 18 List of References .............................................................................................................................. 18 Chapter 3. Development of Transcritical R744 Systems for Small Commercial Applications................................................................................................................. 19 3.1 Introduction................................................................................................................................... 19 3.2 System Descriptions .................................................................................................................... 19 3.3 Experimental Results ................................................................................................................... 22 3.3.1 Experimental Facility ...........................................................................................................................22 3.3.2 Test Matrix ...........................................................................................................................................24 3.3.3 System Performance.............................................................................................................................26 3.3.4 Influence of the Size of the Outdoor Heat Exchangers on System Performance..................................28 3.3.5 Comparison of System Components ....................................................................................................31 3.4 Conclusion .................................................................................................................................... 36 List of References .............................................................................................................................. 37 Chapter 4. Effect of Oil on Small R744 System Performance.................................. 38 4.1 Introduction................................................................................................................................... 38 4.2 System Description ...................................................................................................................... 38 4.3 Experimental Results ................................................................................................................... 42 4.3.1 Experimental Facility ...........................................................................................................................42 4.3.2 Test Matrix ...........................................................................................................................................49 4.3.3 Correlation of Density Determined OCR to Measured Sample OCR ..................................................49 4.3.4 Improvements in System Performance Due to a Decrease in Viscosity and OCR...............................50 4.3.5 Effect on Heat Exchanger Performance ...............................................................................................55 4.3.6 Effect on Compressor Performance......................................................................................................65 4.3.7 Effect of Oil Charge on System and Compressor Performance ...........................................................69 4.4 Conclusions .................................................................................................................................. 73 iii List of References ....................................................................................................... 75 Appendices.................................................................................................................. 76 Appendix A. Component Descriptions...................................................................... 77 A.1 Air-to-Refrigerant Heat Exchangers........................................................................................... 77 A.2 Compressors................................................................................................................................ 78 A.3 Other Components ...................................................................................................................... 78 Appendix B. Instrumentation and Data Reduction................................................... 80 B.1 List of Instrumentation used to Calculate Energy Balances................................................... 80 B.2 Sample EES Data Reduction Files .............................................................................................81 Appendix C. Further Description of the Experimental Facilities............................. 95 Appendix D. Summary Tables of Experimental Test Data..................................... 100 iv List of Figures Page Figure 2-1: Empty R134a bottle cooler unit. .................................................................................................................2 Figure 2-2: Cassette style instrumented refrigeration unit that sits at the base of the bottle cooler...............................3 Figure 2-3: Schematic of R134a refrigeration system. ..................................................................................................4 Figure 2-4: Location of the cans containing thermocouples..........................................................................................6 Figure 2-5: Comparison of the energy balances for the evaporator...............................................................................8 Figure 2-6: Energy balance agreement for the condenser..............................................................................................8 Figure 2-7: Results of the charge determination test show an optimum charge of 325 g. ...........................................11 Figure 2-8: Maximum, average, and minimum can temperature for the high pull-down condition starting at 32.2 °C.................................................................................................................................................................12

Load more