• Title/Summary/Keyword: 대체 CFC

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Condensation heat transfer coefficients of CFC-11 and its alternative refrigerants (CFC-11과 그 대체냉매의 응축 열전달 계수)

  • Joo, Jae-Kil;Cho, Seong-Joon;Jung, Dong-Soo;Kim, Chong-Bo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.21 no.6
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    • pp.830-840
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    • 1997

  • In this study, condensation heat transfer coefficients(HTCs) of CFC-11, HCFC-123 and HCFC-141b are measured, which are used/or considered as working fluids in centrifugal chillers. The main objectives of this study are to measure and compare the HTCs of various refrigerants on plain and low fin tubes and also to find out the optimum fin density of the low fin tubes. To accomplish these goals, HTCs of three refrigerants are measured for the plain tube as well as 4 types of low fin tubes. All measurements are carried out at the vapor temperature of 39.deg. C with the wall temperature difference of 3 .deg. C ~ 8.deg. C. For all the refrigerants tested, a low fin tube of 28 fins per inch yielded the best performance among all the tubes tested. For the plain tube, the HTCs of CFC-11 and HCFC-141b were very similar and those of HCFC-123 were 10% lower than those of CFC-11.Thus, it can be concluded that HCFC-123 and HCFC-141b are acceptable as alternative refrigerants for CFC-11 from the view point of condensation heat transfer.

  • https://doi.org/10.22634/KSME-B.1997.21.6.830 인용 PDF

Characteristics of Rigid Polyurethane Foams Blown by HFCs for LNG Storage Tank (HFC계 발포제를 사용한 LNG 저장탱크용 폴리우레탄 폼 단열재의 특성)

  • Lee Yeongbeom;Choi Sunghee;Choi Gunhyung
    • Journal of the Korean Institute of Gas
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    • v.9 no.1 s.26
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    • pp.16-20
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    • 2005

  • CFC-11 and HCFC-l4lb have been used as blowing agents for rigid polyurethane foam insulation of LNG storage tank. But CFC-11 and HCFC- l4lb deplete ozone layer in the stratosphere. So in leading countries, the use of CFC-11 has been prohibited since 1995 and the use of HCFC-l4lb will be prohibited from 2005. Much efforts and studies have been done about alternative blowing agents and insulations blown by alternative blowing agents. This paper deals with polyurethane foams (PUFs) blown by HFC-365mfc, shows their physical and mechanical characteristics and thermal performance. These data are compared with the results of PUFs blown by HCFC-l4lb. From these test results, PUFs blown by HFC-365mfc show good mechanical and thermal characteristics. It is possible to use PUFs blown by HFC-365mfc as main insulation of membrane type LNG storage tank.

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Performance Analysis of an Automotive Air Conditioning System Using HFC-134a as an Alternative Refrigerant (HFC-134a를 대체냉매로 사용한 자동차 냉방시스템의 성능해석)

  • Han, D.Y.;Cho, Y.D.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.7 no.3
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    • pp.406-420
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    • 1995

  • As concerns increase over the dangers of environmental destruction on a global scale, CFC regulations have finally been carried out and some CFC's are expected to be phased out by the end of 1995. The research for alternative refrigerants is very demanding. The major activities related to alternative refrigerants are focused on two different areas; one is the development of mixed refrigerants by using the existing refrigerants, and the other is the development of new HFC refrigerants. One of the most promising alternative refrigerant for CFC-12 is HFC-134a. HFC-134a has often been used as a replacement of CFC-12 for automotive air-conditioners. However, due to different thermodynamic properties of HFC-134a, performances of the replaced system are degraded compared with those of the CFC-12 system. Sometimes, the complete redesign of the system is required. In order to analyse and design the new system effectively, the developement of a system simulation program, in which HFC-134a can be selected as a refrigerant, is recommended. Therefore, the summary of this research is as follows : (1) The various thermodynamic properties of HFC-134a are ana lysed and programmed. (2) The model for serpentine heat exchanger is developed and programmed. (3) These subroutines are integrated to develop to develop an automotive air conditioning system simulation program which is verified by the test results. (4) The verified program is used to analyse the performance of a selected automotive air conditioning system.

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