• 설비공학논문집
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• 제3권4호
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• pp.286-296
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• 1991

The thermodynamic properties of R134a, the prospective R12 alternative, have been computerized using Martin-Hou equation of state and the coefficients given by Willson-Basu. Several experimental results in literatures for PVT data, saturated vapor pressure, saturated liquid density are compared with the calculated results to investigate the accuracy. The average deviation (max. deviation) is 0.13% (0.25%) for saturated liquid density, 0.25% (0.8%) for PVT data. Thermodynamic properties, enthalpy, entropy are compared with the NIST's. The maximum percent difference is 3% for saturated liquid enthalpy, 1.5% for saturated vapor enthalpy, 4% saturated liquid entropy, and 0.7% for saturated vapor entropy. Correction of W-B's coefficients and inclusion of the sixth term of M-H EOS for improvement of accuracy are recommended. R134a and R12 are compared with respect to refrigeration performance. COP's are different from each other within 3%. Refrigeration effect of R134a is superior to that of R12 but refrigeration capacity of R134a is inferior to that of R12 because the volumetric efficiency of the system using R134a is lower than that of the system using R12.

• 국방과기술
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• 6호통권244호
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• pp.84-91
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• 1999

우리의 후손들이 안심하고 살 수 있는 지구를 남겨줄 의무가 우리에게 있다는 것을 명심하여 친환경적인 제품의 개발에 관심을 가져야만 하며, 사용자들도 지구 환경 오염의 방지에 적극 나서야 할 때이다. 냉매를 보급하는데 있어서는 냉매 유출 유무를 충분히 점검하고 그 처치를 완전히 한 다음에 사용하여야 한다. 또한 냉매 사용량 삭감을 위해서는 과다한 충전이 되지 않도록 주의해야 한다. 불필요한 프레온의 사용을 삼가는 것은 지구 환경을 보호함과 동시에 불필요한 경비를 억제하므로 일거양득이 된다.

• 설비공학논문집
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• 제14권2호
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• pp.175-183
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• 2002

Flow Condensation heat transfer coefficients (HTCs) of Rl2, R22, R32, Rl23, Rl25, R134a, R142b were measured experimentally on a horizontal plain tube. The experi- mental apparatus was composed of three main parts; a refrigerant loop, a water loop and a water-glycol loop. The test section in a refrigerant loop was made of a copper tube of 8.8 mm inner diameter and 1000 mm length respectively. The refrigerant was cooled by passing cold water through an annulus surrounding the test section. All tests were performed at a filed refrigerant saturation temperature of 4$0^{\circ}C$ with mass fluxes of 100, 200, 300 kg/$m^2$s. The experimental result showed that flow condensation HTCs increase as the quality, mass flux, and latent heat of condensation increase. At the same mass flux, the HTCs of R32 and R142b were higher than those of R22 by 35~45% and 7~14% respectively while HTCs of R134a and Rl23 were similar to those of R22. On the other hand, HTCs of Rl25 and Rl2 were lower than those of R22 by 28 ~30% and 15 ~25% respectively Finally, a new correlation for flow condensation HTCs was developed by modifying Dobson and Chato's correlation with the latent heat of condensation considered. The correlaton showed an average deviation of 13.1% for all pure fluids data indicating an excellent agreement.

• 한국자동차공학회논문집
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• 제15권6호
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• pp.170-176
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• 2007

It is time to prepare the phaseout of R134a, the current refrigerant, in automotive air conditioning system because the EC deadline has been coming with new platform vehicles in 2011 and all vehicles by 2017. Until now a high-pressure carbon dioxide($CO_2$) system is the leading replacement of R134a in European auto-makers but there is no firm agreement in the world automotive market. Recently three new fluids have been announced as the possibilities from Honeywell, DuPont and INEOS Fluor. The new alternative refrigerant should meet the requirements like non flammable, non toxic, no ozone depletion effect and low GWP(under 150 to meet EC regulation). The objectives of this paper are to review the fluid H from Honeywell, the more possible alternative refrigerant in 3 new fluids, compare the properties of R134a & fluid H and see the possibility as a replacement of R134a. In this experimental paper we ran and reviewed the cooling performance data in the bench system, the vehicle and the field test. We found the possibility of fluid H system to meet the R134a system performance with some hardware modifications but agreed that it is still needed to study about the long term safety, environmental effects, material compatibilities and so on.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2004년도 동계학술대회 논문집
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• pp.121-121
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• 2004

• 설비공학논문집
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• 제6권1호
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• pp.39-46
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• 1994

Experiments on the performance of refrigeration system using alternatives to R12 are carried out. The condenser and the evaporator are concentric-tube heat exchangers of counter-flow type and the compressor is driven by a variable speed motor. In this study, R134a, R152a, R22/142b(50 : 50 by mass) are adopted as alternatives to R12. Tests are performed by varying the inlet and outlet temperatures of secondary fluids of evaporator and condenser under the condition of constant compressor speed, degree of superheating and degree of subcooling. Results show that R134a has refrigeration capacity close to that of R12 and requires the greatest compressor power compared with that of others. And the system using R152a shows the best performance from the viewpoint of refrigeration capacity, compressor power and coefficient of performance. R22/142b is superior to R12 in the above points.

• 에너지공학
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• 제15권3호
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• pp.166-173
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• 2006

본 연구에서는 상용 냉동 공조기기에서 사용하고 있는 휜-관 열교환기에서 R22와 이의 대체냉매로 채용하고 있는 R134a 압력강하와 열전달 특성에 대해 실험적으로 연구하였다. 실험은 입구온도 $60^{\circ}C$, 질량유량 $150,\;200,\;250\;kg/m^{2}s$의 범위에 대해 수행하였다. 이때 공기의 유입조건은 전구온도 $35^{\circ}C$, 상대습도 40%, 공기유속은 $0.68{\sim}1.6m/s$이다. 실험 결과 응축기 출구의 과냉도를 $5^{\circ}C$로 유지한 경우 Rl34a의 필요공기유속은 R22보다 5.9%작게 나타났으며, R134a의 압력강하는 R22보다 $18.1{\sim}20.4%$의 범위 내에서 크게 나타났다.

• 한국산학기술학회논문지
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• 제14권1호
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• pp.69-73
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• 2013

내부열교환기를 이용한 에어컨 시스템은 작동유체인 R134a의 고압측 액상냉매와 저압측 기상냉매의 상호 열교환을 통해 시스템의 응축 효율을 증가시켜 에너지 효율을 개선시킨다. 이는 에어컨 시스템의 성능 향상 및 경량화를 가능하게 하여 차량 연비 향상과 냉매 누출을 최소화할 수 있으며, 또한 현 R134a 대비 대체냉매 (R1234yf 등)의 동등 냉방성능 확보를 가능하게 하는 기술이다. 본 연구에서는 내측 압출 파이프 및 외측 사이 고효율 냉각 휜 (fin)이 삽입된 이중관 형태의 내부열교환기 상세 설계를 위해, 냉각 휜의 높이 및 내측 압출 파이프 내부형상 등의 다양한 형상 설계인자 변경에 따른 열전달 성능 및 압력강하 특성을 살펴보았다. 가장 우수한 내부열교환기 성능은 난류형성을 위한 내측관 형상이 라이너 및 세레이션 겸용 타입이었으며, 이는 내부열교환기가 장착되지 않은 경우보다 냉방시스템 성능이 약 6.4%, 시스템 COP는 약 9.2% 향상된 결과를 나타내었다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.250-257
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• 2002

A centrifugal compressor for HFC-l34a has been newly designed and developed. Flow analysis using commertial programs was used to evaluate performance and internal flow of the impeller, inlet guide vane and diffuser etc. and design software was developed. The compressor for HFC-l34a was also investigated experimentally to check compression performance. The calculated data coincide the test results of compressor. The data obtained in the present study are useful for design of HFC-l34a centrifugal compressors.

• Journal of Advanced Marine Engineering and Technology
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• 제24권2호
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• pp.24-30
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• 2000

The high-pressure natural refrigerant $CO_2$ is now being evaluated for use in the motor vehicle air-conditioning systems and for several types of unitary equipment. In this study thermodynamic properties of $CO_2$ is compared to those of R-22 and R-134a and the performance characteristics of $CO_2$ refrigeration cycle is analyzed. The results show that the optimum discharge pressure for the cycle performance exists. New design concept for the $CO_2$ refrigeration system should be developed due to the high-operating pressure of itself.