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Jeon, Yongseok,Jung, Jongho,Kim, Dongwoo,Kim, Sunjae,Kim, Yongchan Elsevier 2017 APPLIED ENERGY Vol.205 No.-
<P>The objective of this study was to investigate the effects of ejector geometries on the performance of an ejector expansion air conditioner (EEAC) considering the cooling seasonal performance factor (CSPF). The performance of the EEAC using R410A was measured and analyzed by varying the compressor speed, outdoor-bin temperature, operating pressures, nozzle-throat diameter, and mixing-section diameter. The EEAC in the medium capacity mode exhibited maximum coefficient of performance (COP) improvement, i.e., 7.5%, over the baseline (conventional) cycle. The optimum mixing-section diameter was determined to be 9 mm based on the CSPF. In addition, the optimum mixing-section diameter increased with an increase in the annual average outdoor temperature. The CSPF of the EEAC with the optimized mixing-section diameter improved in the range of 16.0-20.3% over the baseline cycle depending on the climatic conditions.</P>
Jeon, Yongseok,Lee, Sang Hun,Kim, Wonuk,Jung, Jongho,Kim, Yongchan Elsevier 2017 Applied thermal engineering Vol.113 No.-
<P><B>Abstract</B></P> <P>In a liquid injection heat pump, it is very essential to control the compressor discharge temperature without wet-compression problems at extreme outdoor conditions. The objective of this study was to optimize the injection-hole geometries of a liquid injection heat pump in order to prevent the risk of wet-compression while reducing compressor discharge temperature at overload cooling conditions. In this study, a simulation model for predicting the performance of a liquid injection heat pump was developed and validated. The optimum injection-hole geometries were determined to obtain the maximum multiplication ratio, which led to a lower instant injection mass flow rate in terms of R- and θ-directional positions. In addition, the injection-hole diameter was minimized to prevent wet-compression while obtaining the target injection mass flow rate. The discharge temperature of the optimized compressor was decreased by 9.2°C over the baseline compressor while maintaining the same risk for wet-compression at the overload cooling test condition.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A simulation model for a liquid injection heat pump is developed and validated. </LI> <LI> The effects of the injection-hole geometries on the system performance are analyzed. </LI> <LI> The injection-hole geometries are optimized to prevent wet-compression. </LI> <LI> Performance comparison between the optimized and baseline compressors is conducted. </LI> </UL> </P>
Jeon, Yongseok,Kim, Sunjae,Kim, Dongwoo,Chung, Hyun Joon,Kim, Yongchan Elsevier 2017 APPLIED ENERGY Vol.205 No.-
<P>Even though a condenser outlet split (COS) ejector cycle offers several advantages over a standard two-phase ejector cycle, few experimental investigations on the performance of the COS ejector cycle are available in the literature. The objective of this study is to investigate the effects of the various ejector geometries on the performance of a small-sized household refrigeration cycle by using the refrigerant R600a under various operating conditions. The performance of the COS ejector cycle was measured and analyzed by varying the compressor speed, entrainment ratio (ER), nozzle position, and mixing section diameter. The enhancement in COP of the COS ejector cycle over that of the baseline cycle increased with the decrease in ER and increase in compressor speed, owing to the reduction in expansion loss. At a compressor speed of 45 Hz and an ER of 0.3, the maximum COP improvement of the COS ejector cycle with the optimum mixing section diameter over that of the baseline cycle was 6.8%. In addition, the optimum mixing section diameter for a given ER and compressor speed was proposed.</P>
액인젝션을 적용한 열펌프의 운전변수에 따른 성능 특성에 관한 해석적 연구
전용석(Yongseok Jeon),이상헌(Sanghun Lee),강훈(Hoon Kang),김용찬(Yongchan Kim) 대한설비공학회 2013 대한설비공학회 학술발표대회논문집 Vol.2013 No.6
Air-source heat pump shows the performance degradation at severe ambient temperatures. Many researches on injection technique have been conducted in recent years. In this study, a simulation program for a heat pump cycle with liquid injection technique was developed. The simulation model was developed based on the mass and energy balances, and verified by the experiments at various operating conditions. This study discussed cycle performance characteristics with the operating parameters by the simulation program.
가정용 냉동사이클 성능향상을 위한 two-phase ejector의 최적 적용 방안 연구
전용석(Yongseok Jeon) 대한설비공학회 2019 대한설비공학회 학술발표대회논문집 Vol.2019 No.11
An ejector, which is a possible replacement for conventional expansion devices, such as capillary tubes, orifice and thermostatic expansion valves, has been proposed to save energy during the expansion process in the refrigeration cycle. Conventional ejectors were mainly studied high capacity or high operating pressure resulted in high expansion loss. However, ejectors can considerably decrease power consumption in households if they are applied to small capacity refrigeration cycles, such as refrigerators or residential air conditioners. The objective of this study is to investigate the performance characteristics of the ejector cycle, especially focusing on a household refrigeration cycle. To achieve the objective of this study, refrigerator-freezer (RF) test-bench, condenser outlet split (COS) ejector RF prototype, and ejector air-conditioning system were designed and tested with various operating and geometrical conditions.
응축기 출구 스플릿 이젝터 적용 R600a 가정용 냉장고에 관한 실험적 연구
전용석(Yongseok Jeon),김용찬(Yongchan Kim) 대한설비공학회 2019 대한설비공학회 학술발표대회논문집 Vol.2019 No.4
The objective of this study is to investigate the performance characteristics of an R600a domestic refrigerator-freezer adopting a condenser outlet split (COS) ejector cycle. Experiments are conducted to measure the performances of conventional and COS ejector-based domestic RFs using R600a. A test bench is used to analyze the pressure lifting effect, mass flow rate variation, and coefficient of performance (COP) improvement with respect to the entrainment ratio (ER). The COP improvement of the COS ejector cycle over that of the baseline cycle increased with the decrease in ER, owing to the reduction in expansion loss.