• Journal of the Korean Professional Engineers Association
• /
• v.34 no.2
• /
• pp.23-27
• /
• 2001

Until 1996, CFC refrigerants haven't been used because it destroyed ozone that affecting In ecosystem. And HCFC will prohibit until 2020. In Europe, they attempt to move up its fulfillment. Until now the change have completed CFC into HFC134a and is considerated HCFC into HFC410A and HFC407C. But HFC41 OA has high condenser temperature and HFC407C is non-azeotropic refrigerant mixture and gliding temperature phenomenon. New refrigerant ell POE, PVE, PAG was also developed.

• Journal of the KSME
• /
• v.33 no.11
• /
• pp.979-984
• /
• 1993

압축기는 냉동 . 공조 사이클에서 냉매를 압축하여 순환시키는 기능을 한다. 냉동 . 공조 사이클 에서 압축기의 효율 COP는 압축기 모터 입력에 대한 증발기에서의 냉각 능력의 비로서 정의 된다. 따라서 압축기 자체의 특성도 중요하지만 냉매의 열역학적 물성도 중요한 역할을 한다. 압축기의 효율향상문제가 최근에 대두되게 된 것은 첫 째, 몬트리올 협정에 의해 CFC의 사용이 제한되면서 새로 검토하게 된 대체냉매들의 열물성이 CFC보다 불리한 점과 둘째, 에너지 소비를 줄이려는 인식이 환경 측면에서 확산되고 있기 때문이다. 이 글에서는 압축기 효율을 결정하는 주요요소에 대하여 알아보고 최근 국내외에서 이루어지고 있는 효율향상 성과에 대하여 소개하 기로 한다.

• 환경사랑
• /
• s.5
• /
• pp.5-5
• /
• 1996

• Bulletin of Korea Environmental Preservation Association
• /
• v.20 no.6
• /
• pp.4-9
• /
• 1998

• Science & Technology Policy
• /
• v.2 no.28 s.28
• /
• pp.20-25
• /
• 1992

• Bulletin of Korea Environmental Preservation Association
• /
• v.18 no.10
• /
• pp.60-65
• /
• 1996

• Journal of Korea Fishing Vessel Association
• /
• v.51
• /
• pp.28-36
• /
• 1992

• Analytical Science and Technology
• /
• v.14 no.4
• /
• pp.300-305
• /
• 2001

The impurities in isoprene were determined using GC/MS. There were good linearities (above $R^2=0.996$) in the range of the $1.0-50{\mu}g/mL$ and 0.5-5.0%, and the detection limits of the method were below $0.1{\mu}g/mL$ for each impurities. Reagent-grade isoprene contained isopropenyl acetylene and 2-butyne at $10-50{\mu}g/mL$ and the concentrations of cis-piperylene, trans-piperylene, cyclopentadiene and dicyclopentadiene were below $1{\mu}g/mL$. The analysis confirmed that the reagent grade isoprene could be obtained from the distillation of C5 fractions.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.41 no.1
• /
• pp.47-51
• /
• 2017

Recently international cooperations are formed to deal with the environmental pollution of the atmosphere generated by the vapor compression refrigeration system. A refrigeration technique, which can replace existing CFC refrigerants that are the main cause of environmental contamination, has received greater attention. Magnetic refrigeration is a refrigeration technique using the magnetocaloric effect of the magnetic material, and is an eco-friendly refrigeration technology using the solid refrigerant instead of CFC refrigerants. Also it is regarded as an efficient refrigeration system to generate temperature difference between high and low sides using the temperature change of magnetic refrigerants according to the change of magnetic field, instead of using power-consuming and noisy compressor. In this paper, we introduce the magnetic refrigeration apparatus using concentric Halbach cylinder permanent magnets and the experimental results using the apparatus.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.7 no.2
• /
• pp.234-248
• /
• 1995

A super-heat pump system composed of a suction line heat exchanger, low and high stage economizers, and a screw compressor is simulated to examine the energy performance and design options. CFC12, HCFC22, HFC134a, HCFC22/HCFC142b, HFC32/HFC134a, and HFC125/HFC134a are used as working fluids for comparison. The results indicate that the proposed system charged with appropriate mixtures is up to 33.4% more energy efficient than the normal system with CFC12. The performance of the super-heat pump system charged with mixtures was influenced by such factors as the temperature matching, heat source temperature difference, low stage economizer, and high stage economizer. The fluids with a larger liquid specific heat such as HFC134a would have more benefits when a suction line heat exchanger is installed. 40%HCFC22/60%HCFC142b mixture seems to be a good candidate to replace CFC12. On the other hand, 25%HFC32/75% HFC134a would be a good long term candidate to replace HCFC22.