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냉장고용 증발기의 핀 형상 변화에 따른 착상 열전달 성능특성
이무연(Mooyeon Lee),이상헌(Sangheon Lee),정해원(Haewon Jung),김용찬(Yongchan Kim),박재정(Jaejung Park) 대한기계학회 2010 大韓機械學會論文集B Vol.34 No.12
본 논문은 냉장고용 증발기의 핀 형상을 변화시켜가면서 열전달 성능을 실험적으로 규명하는 것을 목적으로 하고 있다. 냉장고용 핀-튜브 증발기에 나선형 원형핀, 개별 평판핀 및 연속 평판핀을 적용하여 무착상 및 착상 열전달 성능과 제상성능을 측정하고 특성변화를 고찰하였다. 무착상조건에서 나선형 원형핀 증발기의 총괄열전달계수가 개별 평판핀 증발기에 비하여 22.3% 우수하고, 연속 평판핀 증발기에 비하여 40.2% 우수함을 알 수 있었다. 착상조건에서 나선형 원형핀 증발기의 총괄열전달계수가 개별 평판핀 증발기에 비하여 27.0% 우수하고, 연속 평판핀 증발기에 비하여 46.3% 우수함을 알 수 있었다. 또한, 나선형 원형핀 증발기의 제상량은 개별 평판핀 증발기에 비하여 3.2% 적고, 연속 평판핀 증발기에 비하여 9.4% 적었다. The objective of this study is to investigate the heat transfer characteristics of evaporators that have various fin configurations and are used in household refrigerators. The frosting and defrosting characteristics of a spirally coiled circular fin-tube evaporator, a discrete-plate fin-tube evaporator, and a continuous-plate fin-tube evaporator were measured and compared. Under non-frosting conditions, the heat transfer coefficient of the spirally coiled circular fin-tube evaporator was 22.3% and 40.2% higher than the coefficients of the discrete- and continuous-plate fin-tube evaporators, respectively. Under frosting conditions, the heat transfer coefficient of the spirally coiled circular fin-tube evaporator was 27.0% and 46.3% higher than the coefficients of the discrete- and continuous-plate fin-tube evaporators, respectively. In addition, the defrosting water amount of the spirally coiled circular fin-tube evaporator was 3.2% and 9.4% lower than the amounts in the case of the discrete- and continuous-plate fin-tube evaporators, respectively.
이무연(Mooyeon Lee),이호성(Hosung Lee),장용희(Yonghee Jang),김용찬(Yongchan Kim) 대한기계학회 2008 大韓機械學會論文集B Vol.32 No.4
The objective of this study is to provide numerical and experimental data that can be used to investigate the performance characteristics of a flat plate fin-tube evaporator in household and commercial refrigerators under frosting conditions. Computer simulations with variations of operating conditions such as air inlet temperature, relative humidity, and geometries were performed to find out optimal design parameters of a fintube evaporator for household and commercial refrigerators. The tube-by-tube method was used in the simulation and the frost growth model was considered under frosting conditions. The developed analytical model predicted the decreasing rates of heat transfer capacity and air flow rate ratio within ± 10% compared to the experimental results for a refrigerator under real operating conditions. As a result, the frost thickness at 3 ℃ & 80% is increased 40% than that of -3 ℃ & 80%, and the frost thickness at 3 ℃ & 90% is increased 30% than that of 3 ℃ & 60%. Accordingly, the operating time of the evaporator in the refrigerator was reduced with the increase of the decreasing rate of air flow rate ratio at each condition.
무착상 조건에서 나선형 원형핀-튜브 증발기의 열전달 성능에 관한 해석적 연구
이무연(Mooyeon Lee),강태형(Taehyung Kang),김용찬(Yongchan Kim),박재정(Jaejung Park) 대한기계학회 2011 大韓機械學會論文集B Vol.35 No.2
본 연구의 목적은 나선형 원형핀-튜브 증발기의 열전달 성능에 관하여 해석적으로 연구하는 것이다. 이를 위하여 두 가지 냉매인 R134a 와 R600a 에 대하여 냉매의 질량유량, 공기온도, 공기풍량 및 튜브직경 변화에 대하여 나선형 원형핀-튜브 증발기의 열전달 성능변화를 고찰하였다. 본 연구에서 개발된 증발기 성능해석 프로그램은 실험결과와 평균 8.3% 오차 범위 안에서 잘 예측되었다. 결과적으로, 동일한 냉매유량 범위에서 R600a 를 사용하는 경우가 R134a 를 사용하는 경우보다 더 우수한 열전달율을 나타내었다. 열전달량은 풍량 및 공기온도가 증가할수록 증가하였으나 열전달량은 튜브두께가 증가할수록 감소하였다. The objective of this study is to predict the heat-transfer performance of a spirally coiled circular fin-tube evaporator in which either R134a or R600a was used; this heat-transfer performance was predicted by varying the mass flow rate, inlet air temperature, air flow rate, and tube thickness. Mean deviation for the analytical model from the measured data was ±8.3%. Simulation results revealed that at a given mass flow rate, the heat-transfer rate of the evaporator using R600a was higher than that usingR134a because the enthalpy of the former is higher than that of the latter at the given conditions. The heat-transfer rate of both refrigerants increased with an increase in the air flow rate and inlet air temperature but decreased with an increase in the tube thickness.
모세관 내경 축소에 따른 소형멀티 냉동시스템의 성능특성변화
이무연(MooYeon Lee),최석재(Seokjae Choi),김상욱(Sangok Kim) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
This paper is an experimental study on the performance characteristic with a variation of capillary diameter and length. The performance characteristic of a refrigeration system is predicted that it is occurring changes of flow pattern and pressure drop in a capillary tube because of reduction of capillary diameter 0.74 to 0.6 mm. The difference between experimental results and analytical results is mainly caused by values of friction factor for using to calculate pressure drop through a small diameter capillary tube under 0.74mm. The experimental equation is derived from capillary tube test data using curve fitting method.
김치냉장고를 중심으로한 소형 멀티 냉동시스템의 성능특성 변화에 관한 연구
이무연(Mooyeon Lee),최석재(Seokjae Choi),김상욱(Sangok Kim),이원근(Wonkeum Lee) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
In this paper, the performance of a domestic Kim-Chi refrigerator is predicted by using a calculation<br/> model & experiment. The objectives of this study are to find out the best design points of a refrigeration<br/> system and calculate an adiabatic characteristic to change outdoor temperature. The best design points such as<br/> refrigerant charge and capillary length were experimentally investigated. And the calculation model is<br/> conducted as a function of calculation parameters and outdoor temperature. According to this study results,<br/> the best design points of a refrigeration system are each 95g of a refrigerant charge and 3500/3500mm of<br/> capillary lengths. And the power consumption is 13.578 Kwh/month. And a part of the worst heat loss is a<br/> front side of a domestic Kim-Chi refrigerator body.
프로판/이소부탄 혼합냉매를 적용한 가정용 소형 멀티 냉동시스템의 성능특성에 관한 연구
이무연(MooYeon Lee),최석재(Seokjae Choi),김상욱(Sangok Kim) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
In this paper, The performance of Kim-Chi refrigerator with three evaporator and one compressor was investigated in employing 55% propane and 45% isobutane (R290/R600a) refrigerant mixture as an alternative refrigerant of R134a. The drop in test was performed by varying both refrigerant charge amount and capillary tube length in order to find both the performance and reliability of a small multi-refrigeration system. As a result, Both the power consumption and COP is increased by about 15% and 10%, respectively as compared to the baseline R134a system. In addition, the propane/isobutene refrigerant mixture system took advantage of the minimization of modification and redesigning of system components because of similar thermodynamic properties with R134a such as saturation pressure, temperature, normal boiling point(NBP) characteristics.
이성희(Sunghee Lee),김무연(Mooyeon Kim) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
In the present study, the effects of orthogonal ribs on post-warpage through injection molding process were investigated. Injection molding experiments with three kinds of injection molds were performed for orthogonal stiffened plastic plate. The warpage of each injection molded specimen was measured using 3D CMM. And plastic injection molding analysis with commercial code was performed for the presented model. Results of injection molding CAE analysis were compared with those of experiments. It was shown that orthogonal ribs have significant effect on the warpage of the structure in both cases of experiment and CAE analysis after injection molding.