• Title/Summary/Keyword: 냉매 134a

Search Result 202, Processing Time 0.037 seconds

Numerical Study on Tip Clearance Effect on Performance Characteristics of a Centrifugal Compressor for a R134a Turbo-Chiller (R134a 터보냉동기용 원심압축기의 익단간극이 성능특성에 미치는 영향에 관한 수치해석적 연구)

  • Lee, Kyoung-Yong;Choi, Young-Seok;Park, Woon-Jean
    • 유체기계공업학회:학술대회논문집
    • /
    • 2003.12a
    • /
    • pp.451-456
    • /
    • 2003
  • In this study, the overall performance and the effect of the tip leakage flow of the centrifugal compressor with the refrigerant HFC-l34a were numerically studied using CFX-TASCflow. To study the effect of a tip leakage flow, the numerical study of the overall performance of HFC-l34a centrifugal compressor with a cascade diffuser was preceded and compared with experimental result. Six different tip clearances were used to consider the influence of a tip clearance on performance. The tip leakage flow was illustrated for qualitative discussion. The results obtained in this study can be applied to the determination of the cold clearance.

  • PDF

The Design and Performance Test of a Centrifugal Compressor for HFC-134a Refrigerant (HFC-134a용 원심압축기의 성능시험 및 설계방안)

  • Sin, Jung-Kwan;Kim, Kyung-Hoon;Kang, Shin-Hyoung
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.22 no.3
    • /
    • pp.139-148
    • /
    • 2010
  • A centrifugal compressor for HFC-134a has been newly designed and developed. Flow analysis using commercial programs was used to evaluate performance and internal flow of the impeller, inlet guide vane and diffuser etc. The purpose of this study is to establish the design theory necessary to the development of HFC-134a centrifugal compressors and to supply basic data related to design by reviewing design values and experimental values through the performance test. The compressor for HFC-134a 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-134a centrifugal compressors.

Calculation of the Thermodynamic Properties of R-134a and A Preliminary Study of the Refrigeration Performance (R-134a의 열역학적 물성치 계산과 냉동 성능에 관한 연구)

  • Park, Y.M.;Lee, H.W.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.3 no.4
    • /
    • pp.286-296
    • /
    • 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.

  • PDF

Numerical Study on the Performance Characteristics of a Centrifugal Compressor for a R134a Turbo-Chiller (R134a 터보냉동기용 원심압축기의 성능특성에 관한 수치해석적 연구)

  • Lee, Kyoung-Yong;Choi, Young-Seok;Park, Woon-Jean
    • The KSFM Journal of Fluid Machinery
    • /
    • v.7 no.2 s.23
    • /
    • pp.14-20
    • /
    • 2004
  • In this study, the overall performance and the local flow field of the centrifugal compressor with the refrigerant HFC-l34a were numerically studied using CFX-TASCflow. The thermodynamic and transport properties of the refrigerant gas were modeled by REFPROP which is NIST refrigerant properties database. The impacts of a grid qualify, discretization scheme, turbulent model and interaction between a impeller and a cascade diffuser were analyzed comparatively. The results were compared with experimental data and 1-D design results using COMPAL and agreed well with others. The numerical method and data obtained in this study can be applied to the design and modification of centrifugal compressors with real gases

Numerical Study on Tip Clearance Effect on Performance Characteristics of a Centrifugal Compressor for a R134a Turbo-Chiller (R134a 터보냉동기용 원심압축기의 익단간극이 성능특성에 미치는 영향에 관한 수치해석적 연구)

  • Lee, Kyoung-Yong;Choi, Young-Seok;Park, Woon-Jean
    • The KSFM Journal of Fluid Machinery
    • /
    • v.7 no.6 s.27
    • /
    • pp.38-44
    • /
    • 2004
  • In this study, the overall performance and the effect of the tip leakage flow of the centrifugal compressor with a refrigerant HFC-l34a were numerically studied using CFX-TASCflow. To study the effect of the tip leakage flow, the numerical study of the overall performance of HFC-l34a centrifugal compressor with a cascade diffuser was preceded and compared with the experimental result. Six different tip clearances were used to consider the influence of the tip clearance on the performance. The tip leakage flow was illustrated for qualitative discussion. The results obtained in this study can be applied to the determination of the cold clearance.

A Study of Thermodynamic Cyclic Characteristics of HFC-134a Automotive Air-Conditioner System (HFC-134a 자동차용 공조시스템의 열역학적 사이클 특성에 관한 연구)

  • Lee, K.H.;Won, J.P.
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.2 no.1
    • /
    • pp.51-64
    • /
    • 1994
  • Analytical study on the thermodynamical cyclic behabiour and characteristics of HFC-l34a refrigerant for automotive air conditionser system for the replacement of existing CFC-12 has been carried out in this paper through development of system performance simulation program, expecially in the view point of system design considerations. The results indicate that HFC-l34a system will give a greater refrigerating capacity than CFC-12 if appropriate engineering measures such as proper codensers, flow controllers, etc., taken for certain operating conditions. The results, however, also show that the operating power for compression process increases over entire temperature range as a result of decreasing volumetric efficiency due to larger specific volume and increased discharging pressure. The present study results indicate that proper selection of condensing and evaporating temperature plus refrigerant control is very important performance factor to have better COP in the HFC-134a system design.

  • PDF

Flow Characteristics of Refrigerant-oil Mixtures in a Dehumidifying Cycle (제습 사이클에서의 냉매-오일 혼합물의 유동특성)

  • 박세민;하삼철;신종민;이장호
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.13 no.1
    • /
    • pp.1-8
    • /
    • 2001
  • This paper deals with refrigerant-oil mixtures in a dehumidifying cycle. Two different oils such as Alkylbenzene(AB) and Polyol-esters(POE) lubricants are used for R134a to investigate the effect of miscibility on oil returnability. It was found that R134a/AB mixture had more unstable interface between oil and refrigerant than R134a/POE mixture. However, overall flow patterns of both refrigerant-oil mixtures were almost same. The minimum height of oil measured in the compressor was as high as twice of the least permissible height of oil in the compressor required to insure its reliability. Thus, it is considered that immiscible oil, i. e., AB for R134a can be used without causing oil returnability problem.

  • PDF

External Condensation Heat Transfer Coefficients of R22 Alternative Refrigerants and R134a According to the Saturated Vapor Temperature Change on an Enhanced Tube (열전달 촉진관에서 R22 대체냉매 및 R134a의 포화증기 온도변화에 따른 외부 응축 열전달계수에 관한 연구)

  • Yoo Gil-Sang;Hwang Ji-Hwan;Park Ki-Jung;Jung Dongsoo
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.17 no.11
    • /
    • pp.981-989
    • /
    • 2005
  • In this study, external condensation heat transfer coefficients (HTCs) are measured on a low fin tube and Turbo-C tubes at the saturated vapor temperature of $30^{\circ}C$, $39^{\circ}C$, and $50^{\circ}C$ for R22, R410A, R407C and R134a with the wall subcooled at $3{\~}8^{\circ}C$. The HTCs of all refrigerants decreased as increasing the saturation temperature from $30^{\circ}C$ to $50^{\circ}C$. This trend is due to better thermodynamic properties of the liquid phase at low temperature Beatty and Katz's prediction yielded a $20.0\%$ deviation for the low fin tube data. The heat transfer enhancement factors for the 26 fpi low fin tube and Turbo-C tubes are 4.0${\~}$5.5 and 3.0${\~}$8.1 respectively for the refrigerants tested. Finally the performance of Turbo-C tube is better than that of the low fin tube.

Flow Boiling Heat Transfer Characteristics of R22 Alternative Refrigerants in a Horizontal Microfin Tube (R22 대체 냉매의 마이크로 핀관내 흐름 비등 열전달 특성)

  • 한재웅;김신종;정동수;김영일
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.13 no.8
    • /
    • pp.692-700
    • /
    • 2001
  • Flow boiling heat transfer coefficients(HTCs) of R22, R134a, R407C, and R410A were measured experimentally for a horizontal plain and a microfin tube. Experimental apparatus was composed of 3 main parts: a refrigerant loop, a water loop and a water-glycol loop. The test section in th refrigerant loop was made of a copper tube of 9.52 mm outer diameter and 1 m length for both tubes. The refrigerant was heated by passing hot water through an annulus surrounding the test section. Tests were performed at a fixed refrigerant saturation temperature of $5^{\circ}C$ with mass fluxes of 100~300 kg/$m^2$s. Test results showed that at similar mass flux the flow boiling HTCs of R134a were similar to those of R22 for both plain and microfin tube. HTCs of R407C were similar to those of R22 for a plain tube but lower than those of R2 by 25~48% for a microfin tube. And HTCs of R410A were higher than those of R2 by 20~63% for a plain tube and were similar to those of R22 for a microfin tube. In general, HTCs of a microfin tube were 1.8~5.7 times higher than those of a plain tube.

  • PDF

Flow Condensation Heat Transfer Coefficients of Pure Refrigerants (순수냉매의 흐름응축 열전달계수)

  • 김신종;송길홍;정동수
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.14 no.2
    • /
    • pp.175-183
    • /
    • 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.