• 대한기계학회논문집B
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• 제38권3호
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• pp.255-262
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• 2014

판형열교환기의 증발과정에서 오일에 위한 영향을 알아보기 위해 마이크로 기어 펌프를 이용한 냉매-R134a 순환 성능실험 장치를 구성하여, 증발열전달 실험을 수행하였다. POE 오일을 펌프를 이용하여 냉매 질량 유량에 비례하도록 0~5%를 첨가하여, 오일순환량에 따른 열전달계수 변화를 측정하였다. 오일순환율이 증가할수록 R134a 증발 열전달계수는 감소하며, 압력손실은 증가한다. 질량유량 80 g/s, 증발 온도 $30^{\circ}C$ 일 때, 오일 순환율 2%조건에서 무오일 대비 약 10%의 열전달계수가 감소하였고, 압력손실은 약 10% 증가하였다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 하계학술발표대회 논문집
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• pp.10-10
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• 2007

• 설비공학논문집
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• 제20권6호
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• pp.388-393
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• 2008

This study has been conducted to select the suitable refrigeration oil for a $CO_2$ refrigeration system. Non-hygroscopic property of refrigeration oils is one of the most important properties for refrigeration oils. PAG and POE oils are considered as test oils in this study. Transient variation of water content of PAG and POE oils was measured for 3 different vessels in the environmental conditions, such as in the range of temperature $25^{\circ}C$ to $40^{\circ}C$ and relative humidity 40% to 85%. The results obtained that water content of both POE and PAG is increased with an increase in the contact area with ambient for 3 different vessels. It is also found that water content of both POE and PAG is increased as the ambient temperature and relative humidity is increased. Non-hygroscopic property of POE oil is found to be much superior than that of PAG oil.

• 설비공학논문집
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• 제11권3호
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• pp.384-390
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• 1999

A vibrating U-Tube decimeter has been evaluated as a sensor for measuring the concentration of oil in the liquid line of a refrigeration system. Calibration and performance tests were conducted under simulated liquid-line conditions for R-407C/POE oil and R-410A/POE oil mixtures in oil concentration from 0 to 15 weight percent. Test temperatures ranged from 20 to 5$0^{\circ}C$. As a result of test, oil concentration correlations are presented in terms of specific gravity at each constant temperature. These equations enable to predict the oil concentration without any extraction of the mixture, and can be applied for R-407C/POE oil and R-410A/POE oil mixtures.

• 에너지공학
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• 제18권3호
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• pp.203-211
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• 2009

기존의 CFC 계열 및 HCFC 계열 냉매들이 오존층 붕괴와 지구온난화의 원인들 중의 한가지로 밝혀지면서 이것을 대체할 수 있는 냉매의 개발은 주요한 연구과제였다. 이제 몇 가지 대체 냉매들이 개발되면서 이것들 이 냉동시스템에 사용될 때 발생하는 상용성 (Compatibility)이 연구될 필요가 있다. 본 연구에서는 대체냉매의 상용성 연구의 일환으로 1,1,1,2-Tetrafluoroethane(HFC-134a) +1,1,1-Trifluoroetane(HFC-143a) + Pentafluoroethane (HFC-125)의 혼합대체냉매 HFC-404a 와 냉매 윤활유의 하나인 POE 오일 혼합물의 증기압을 측정하였다. 측정온도범위는 냉매 시스템의 운전온도를 고려하여, 263.15K 에서 323.15 K로 하였으며 오일농도범위는 0 mass% 에서 90 mass% 까지로 하였다. 측정결과 273.15K 이하의 온도에서 오일 농도 30 mass%까지 증기압에 대한 오일의 영향은 미미하였으며 50 mass% 이상에서는 증기압이 급격히 떨어지는 것이 밝혀졌다. 측정자료를 이용하여 HFC-404a와 POE 오일 혼합물의 증기압을 예측할 수 있는 모형을 개발 하기 위하여 Rault 모델과 Flory-Huggins 모델을 사용하여 측정치와 비교하였다. 그리고 보다 정확하고 실용적으로 증기압을 예측할 수 있는 경험식을 도출하였다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.646-651
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• 2007

This study has been conducted to select the suitable refrigeration oil for a $CO_2$ refrigeration system. The oil return is one of the most important characteristics for refrigeration oils. PAG and POE oils are considered as a test fluids in this study. An evaporator model is employed to simulate the evaporator of a $CO_2$ refrigeration system. Oil return characteristics has been investigated for $CO_2$/PAG and $CO_2$/POE mixtures in the range of oil concentration 0 to 5 weight-percent and the mixture temperature range of $0^{\circ}C$ to $15^{\circ}C$. The results obtained indicate that oil return is decreased with an increase in the oil concentration and mixture temperature for both POE and PAG oils. It is also found that POE oil is seen to be superior than PAG oil in terms of oil return in an evaporator of a $CO_2$ refrigeration system.

• 대한설비공학회지:설비저널
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• 제38권12호
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• pp.61-65
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• 2009

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.386-391
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• 2005

An experimental study was conducted to analyze the thermal stability and to estimate the lifetime of refrigerating lubricants. PAG and POE oil are considered as a test fluids in this study. The viscosity of PAG and POE oil was measured by the vibration type viscometer while temperature is varied periodically in the range of $0^{\circ}C{\sim}100^{\circ}C$. The results indicate that the reduction rates of viscosity of PAG and POE oil were less than 5% after 510 cycles. In order to estimate lifetime of PAG and POE oil with temperature, the viscosity was measured while the temperature of oils was maintained at 180, 200 and $220^{\circ}C$. It is found that the lifetimes of PAG oil were shown to be 244, 177 and 89 hours at the temperature of 180, 200 and $220^{\circ}C$, respectively. Also the lifetimes of POE oil were estimated to be 1,744, 1,007 and 334 hours at the temperature of 180, 200 and $220^{\circ}C$, respectively. The lifetime correlations of PAG and POE oil are suggested in this paper.

• 설비공학논문집
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• 제12권6호
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• pp.589-598
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• 2000

The vapor-liquid equilibrium and miscibility measurement apparatus was developed and used to obtain data for refrigerant/oil mixture. The vapor-liquid equilibrium and miscibility data for R-410a/POE32 and R-410A/POE46 oil mixtures are obtained over the temperature range from -20 to $60^{\circ}C\;with\;10^{\circ}C$ intervals and the oil concentration range from 0 to 90 wt%. Using the experimental data, an empirical model is developed to predict the temperature-pressure-concentration relations for R-410A/POE oil mixtures at equilibrium. In the R-410A/POE32 oil mixture, the average root-mean-square deviation between measured data and calculated results from the empirical model is 2.00% and in the R-410a/POE46 oil mixture, that is 3.69%. Flory-Huggins theory is also used to predict refrigerant/oil mixture behavior. Miscibility for R-410A/POE32 oil mixture was observed all over the experimental conditions. Immiscibility for R-410A/POE46 oil mixture was observed at the low oil concentrations(10~30 wt%).

• 설비공학논문집
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• 제19권10호
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• pp.718-725
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• 2007

In the general vapor-compression refrigeration system, refrigeration lubricant circulates in refrigeration system with refrigerant. Knowledge of the amount of circulating lubricant is very important to exactly calculate capacity of the refrigeration system. An experimental study was conducted to estimate the oil concentration of a flowing $CO_2/Oil$ mixtures. POE and PAG oil are considered as test lubricants in this study. Performance tests were conducted under simulated liquid conditions for $CO_2/POE$ oil mixture in oil concentration of 0 to 10 weight-percent and $CO_2/PAG$ oil mixture in oil concentration of 0 to 6 weight-percent in the temperature ranges of $-5^{\circ}C\;to\;15^{\circ}C$. The results obtained indicate specific gravity of $CO_2/Oil$ mixture is increased as oil concentration is increased and as temperature of mixture is decreased. Oil concentration correlation of $CO_2/POE$ oil mixture and $CO_2/PAG$ oil mixture is suggested, based on the measurement of specific gravity and temperature. This correlation enable to predict the oil concentration without extraction of the mixture and can be applied for $CO_2/POE$ mixtures and $CO_2/PAG$ mixtures.