팽창기 및 2단압축을 적용한 고효율 이산화탄소 사이클의 성능특성에 대한 해석적 연구 = Simulation Study on the Transcritical CO2 Cycle with an Expander and Two-stage Compression

다국어 초록 (Multilingual Abstract)

A transcritical CO2 cycle using 2-stage and expander was simulated to predict the performance characteristics. The cycle simulation was conducted as a function of design parameters and operating conditions. The simulation results of the 2-stage cycle showed similar tendency with the measured system pressure, compressor work, evaporator capacity and COP. The performance of the expander cycle was compared with that of the basic CO2 cycle. System characteristics were analyzed with variations of compressor frequency, outdoor temperature and EEV opening. In the 2-stage cycle simulation, the highest COP was 2.7 at 30-30 Hz. The COP decreased as the compressor frequency increased. Besides, the COP can be increased by optimizing EEV opening. The COP of the 2-stage cycle was approximately 23% higher than that of the basic cycle. The expander as an expansion device can help to enhance the COP of the system.

목차 (Table of Contents)

• 목 차
• Abstract.
• Contents.
• ListofFigures.
• ListofTables.
• Nomenclature.
• 제 1장 서 론.
• 1.1연구 배경.
• 1.2연구 동향.
• 1.3연구 목적 및 내용.
• 제 2장 고효율 CO2사이클 모델링.
• 2.1CO2사이클 모델링.
• 2.2압축기 모델링.
• 2.3열교환기 모델링.
• 2.4플래시 탱크 및 믹서 탱크 모델링.
• 2.5팽창기 모델링.
• 2.6시스템 시뮬레이션 매칭 방법 및 검증.
• 2.6.12단압축 사이클 모델의 검증.
• 2.6.2팽창기 사이클 모델의 검증.
• 제 3장 결과 및 고찰.
• 3.12단압축 사이클 시뮬레이션 결과 및 고찰.
• 3.1.1기본 CO2사이클과의 성능 비교.
• 3.1.2압축기 주파수 변화에 따른 고찰.
• 3.1.3외기온도 변화에 따른 고찰.
• 3.2팽창기 사이클 시뮬레이션 결과 및 고찰.
• 3.2.1기본 CO2사이클과의 성능 비교.
• 3.2.2외기온도 변화에 따른 고찰.
• 3.2.3팽창기 효율 변화에 따른 고찰.
• 3.3팽창기를 적용한 2단압축 사이클에 대한 고찰.
• 3.4개선된 사이클에 대한 성능향상 비교.
• 제 4장 결 론.
• 4.12단압축을 적용한 CO2사이클.
• 4.2팽창기를 적용한 CO2사이클.
• 4.3팽창기를 적용한 2단압축 CO2사이클.
• 참고문헌.
• 감사의 글.
• ListofFigures
• Fig.1.1 ConceptofaCO2cyclewithexpander.
• Fig.2.1 SchematicofabasicCO2cycle.
• Fig.2.2 P-hdiagram ofbasicCO2cycle.
• Fig.2.3 Schematicofa2-stagecompressioncycle.
• Fig.2.4 P-hdiagram of2-stageCO2cycle.
• Fig.2.5 Flow chartfora2-stagecompressioncyclemodel.
• Fig.2.6 SchematicofaCO2cyclewithexpander.
• Fig.2.7 P-hdiagram ofCO2cyclewithexpander.
• Fig.2.8 Schematicdiagram ofthecompressor.
• Fig.2.9 Heatandmassflow diagram ofthethermodynamicmodel.
• Fig.2.10Flow chartofthecompressormodel.
• Fig.2.11Finandtubetypeheatexchanger.
• Fig.2.12Offsetstripfin.
• Fig.2.13Comparisonoftheheattransfercoefficients.
• Fig.2.14SegmentofanoutdoorHXforthemodel.
• Fig.2.15Flow chartoftheoutdoorHXmodel.
• Fig.2.16IsentropicefficiencyofaCO2cyclewithexpander.
• Fig.2.17Comparisonofcompressorwork,evaporatorcapacityandCOPbetweenexperimentalandsimulationresults.
• Fig.2.18Comparisonofmeasuredmassflow ratewithpredictedvalues.
• Fig.2.19Comparisonofmeasuredpressureswithpredictedvalues.
• Fig.2.20Comparisonofmeasuredwithpredictedresultsfor2-stageCO2cycle.
• Fig.2.21Comparisonofthemeasuredwiththepredictedcycle.
• Fig.2.22Comparisonofcompressorwork,evaporatorcapacityandCOPbetweenexperimentalandsimulationresults.
• Fig.2.23ComparisonofmeasuredwithpredictedresultsofbasicCO
• cycle.
• Fig.3.1 Comparisonofcompressorworkandevaporatorcapacitybetweenbasicand2-stagecycle.
• Fig.3.2 ComparisonofCOPbetweenbasicand2-stagecycle.
• Fig.3.3 Variationofpressureswithoutdoortemperatureof2-stageCO2cycle.
• Fig.3.4 Variationofevaporatorenthalpydifferencewithoutdoortemperatureof2-stageCO2cycle.
• Fig.3.5 Variationofevaporatorinletqualitywithoutdoortemperatureof2-stageCO2cycle.
• Fig.3.6 Variationofmassflow ratewithoutdoortemperatureof
• 2-stageCO2cycle.
• Fig.3.7 Variationofcompressorworkwithoutdoortemperatureof
• 2-stageCO2cycle.
• Fig.3.8 Variationofcompressorwork,evaporatorcapacityandCOPwithoutdoortemperatureof2-stageCO2cycle.
• Fig.3.9 QualitywithEEVopeningvariationsof2-stageCO
• cycle.
• Fig.3.10COPwithEEVopeningvariationsof2-stageCO
• cycle.
• Fig.3.11Variationsofcompressorandexpanderworkoftheexpandercycleaccordingtocompressorfrequency.
• Fig.3.12Variationsofgascoolerpressureaccordingtocompressorfrequency.
• Fig.3.13Variationsofcoolingcapacityaccordingtocompressorfrequency.
• Fig.3.14Variationsofenthalpydifferenceintheevaporatoraccording
• tocompressorfrequency.
• Fig.3.15Variationsofmassflow rateaccordingtocompressorfrequency.
• Fig.3.16Variationsofqualityaccordingtocompressorfrequency.
• Fig.3.17VariationsofcoolingCOPaccordingtocompressorfrequency.
• Fig.3.18Variationofgascoolingpressureaccordingtooutdoortemperature.
• Fig.3.19Variationofevaporatingpressureaccordingtooutdoortemperature.
• Fig.3.20Variationofpressuredifferenceaccordingtooutdoortemperature.
• Fig.3.21Variationofmassflow rateaccordingtooutdoortemperature.
• Fig.3.22Variationsofcompressorandexpanderworkaccordingtooutdoortemperature.
• Fig.3.23Variationofenthalpydifferenceinthecompressoraccordingtooutdoortemperature.
• Fig.3.24Variationofcoolingcapacityaccordingtooutdoortemperature.
• Fig.3.25VariationofcoolingCOPaccordingtooutdoortemperature.
• Fig.3.26Variationofqualityaccordingtoexpanderefficiency.
• Fig.3.27Variationofcoolingcapacityaccordingtoexpanderefficiency.
• Fig.3.28Variationsofcompressorandexpanderworkaccordingtoexpanderefficiency.
• Fig.3.29VariationofcoolingCOPaccordingtoexpanderefficiency.
• Fig.3.30Schematicofa2-stagecompressioncyclewithexapnder.
• Fig.3.31P-hdiagram ofa2-stagecompressioncyclewithexapnder.
• Fig.3.32Compressorworkof2-stageCO2cyclewithorwithoutexpander.
• Fig.3.33COPof2-stageCO2cyclewithorwithoutexpander.
• ListofTables
• Table1.1Thermophysicalpropertiesofseveralrefrigerants.
• Table2.1Variationsofcompressormodel.
• Table2.2EEVopeningratioforeachcompressorratio.
• Table3.1ComparisonofvariousCO2cycle.