• Title/Summary/Keyword: Pure Refrigerant

Search Result 78, Processing Time 0.017 seconds

Forced convective boiling heat transfer for a ternary refrigerant mixture inside a horizontal tube (수평관내 3성분 혼합냉매의 강제대류비등 열전달)

  • 오종택
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.11 no.6
    • /
    • pp.912-920
    • /
    • 1999
  • The forced convective boiling heat transfer coefficients of R-407C were measured inside a horizontal tube 6.0mm I.D. and 4.0m long. The heat transfer coefficients increased according to an increase in heat flux at constant mass flux. Because nucleation was completely suppressed in the two-phase flow region with high quality, heat transfer coefficients in forced convective evaporation were higher than those in nucleate boiling region. Average heat transfer coefficients of R-407C were about 30 percent lower than the pure refrigerant correlation, due to mass transfer resistance at the gas-liquid interface. However, the total experimental data shows an agreement with the predicted data for ternary refrigerant mixtures with a mean deviation of 30%.

  • PDF

Condensing Heat Transfer Characteristics on a Heat Pump System Using Non-Azeotropic Refrigerant Mixtures (비공비혼합냉매를 사용하는 열펌프의 응축열전달 특성)

  • 박기원;오후규;김욱중
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.19 no.4
    • /
    • pp.1125-1133
    • /
    • 1995
  • Experiments were performed to investigate the condensing heat transfer characteristics of non-azeotropic mixtures of R-22 and R-114 in a heat pump system with a horizontal smooth tube as a condenser. The ranges of parameters, such as heating capacity, mass flow rate of refrigerant and quality were 780-3,480W, 24-71kg/h, and 0-1, respectively. The overall compositions of R-22 in a R-22/114 mixture were 25, 50, 75 and 100 per cent by wight. The results show that the overall condensing heat transfer coefficients for the mixtures were lower than the pure R-22 values. Local heat transfer coefficient of the pure R-22 was hghest at the top of the test tube. The local heat transfer coefficient of R-22/114 (50/50 wt%) at side and bottom of the test tube was higher than that at the top. From the obtained data, a prediction for the condensing heat transfer coefficients of the mixture was done based on the method of Fujii.

Performance and Heat Transfer Characteristics of Heat Pump System Using Refrigerant Mixtures (혼합냉매를 사용한 열펌프 시스템의 성능과 열전달 특성)

  • Kim, T.S.;Shin, J.Y.;Ro, S.T.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.4 no.4
    • /
    • pp.360-369
    • /
    • 1992
  • A heat pump system is constructed to evaluate its performance and heat transfer characteristics with mixtures of R22/R142b as working fluids. The heat transfer in the evaporator and the overall performance are measured and analyzed in terms of the compositions and relevant variables. Possibility of capacity modulation by changing composition is observed without degradation of heat transfer coefficients and coefficient of performance. The cooling capacity is varied continuously within 200 percent based on minimum capacity at constant compressor speed. For similar cooling capacity, COP is improved by mixing two refrigerants and shows maximum value at 60% mass fraction of R22. Average heat transfer coefficients of mixtures decrease in comparison with pure refrigerants at similar cooling capacity and mass flow rate. However, the overall heat transfer coefficients decrease moderately. A cycle simulation is performed in order to manifest the advantages of using refrigerant mixtures, considering experimentally observed heat transfer characteristics.

  • PDF

External Condensation Heat Transfer Coefficients of Refrigerant Mixtures on a Smooth Tube

  • An, Kwang-Yong;Cho, Young-Mok;Seo, Kang-Tae;Jung, Dong-Soo
    • International Journal of Air-Conditioning and Refrigeration
    • /
    • v.9 no.3
    • /
    • pp.1-9
    • /
    • 2001
  • In this study, condensation heat transfer coefficients (HTCs) of nonazeotropic refrigerant mixtures of HFC32/HFC 134a and HCFC123 at various compositions were measured on a horizontal smooth tube. All data were taken at the vapor temperature of 39$^{\circ}C$ with a wall subcooling of 3~8K. Test results showed that HTCs of tested mixtures were 11.0~85.0% lowed than the ideal values calculated by the mass fraction weighting of the HTCs of the pure components. Thermal resistance due to the diffusion vapor film was partly responsible for the significant reduction of HTCs with these nonazeotropic mixtures. The measured data were compared against thc predicted ones by Colburn and Drew's film model and a good agreement was observed within a deviation of 15%.

  • PDF

Comparative Study on the Performance of Correlations of the Enthalpy of Vaporization for Pure Substance Refrigerants

  • Park Kyoung Kuhn
    • International Journal of Air-Conditioning and Refrigeration
    • /
    • v.12 no.4
    • /
    • pp.214-219
    • /
    • 2004
  • A few commonly used correlation equations of the enthalpy of vaporization are reviewed and a new three-parameter correlation equation is proposed. Performance of the pro­posed equation is examined using the data listed in the ASHRAE table for 22 pure substance refrigerants. The new equation yields an average absolute deviation of $0.14\%$ for 22 refrig­erants, which is better than those of other equations, such as Xiang $(0.18\%),$ Majer-Svoboda­Pick $(0.18\%),$ and Somayajulu equation $(0.23\%)$.

Comparative Study on the Performance of Correlations of the Enthalpy of Vaporization for Pure Substance Refrigerants (순수물질 냉매에 대한 증발 엔탈피 상관식의 성능비교 연구)

  • 박경근
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.15 no.8
    • /
    • pp.704-709
    • /
    • 2003
  • A few commonly used correlation equations of the enthalpy of vaporization are reviewed and a new three-parameter correlation equation is proposed. Performance of the proposed equation is examined using the data listed in the ASHRAE table for 22 pure substance refrigerants. The new equation yields an average absolute deviation of 0.14% for 22 refrigerants, which is better than those of other equations, such as Xiang (0.18%), Major-Svoboda-Pick (0.18%), and Somayajulu equation (0.23%).

Pool boiling heat transfer coefficients of alternative refrigerants on low fin tubes (낮은 핀관에서 대체냉매의 풀비등 열전달계수)

  • 송길홍;이준강;정동수;김종보
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.10 no.4
    • /
    • pp.411-422
    • /
    • 1998
  • In this study, experiments were carried out to provide nucleate pool boiling heat transfer data for a plain tube and 4 different low fin tubes employing 2 refrigerant mixtures of R410A, R407C, and 12 pure fluids. Low fin tubes were machined on a 19.05mm nominal outside diameter copper block according to the manufacturer's low fin tube specifications. Cartridge heaters were used to generate uniform heat flux on the tubes. For all refrigerants, heat flux varied from 10㎾/$\m^2$ to 80㎾/$\m^2$. It is found that heat transfer coefficients(HTCs) of high vapor pressure refrigerants are usually higher than those of low pressure fluids. On the other hand, the fin effect was more prominent with low pressure refrigerants than with high pressure ones. Optimum fin density as well as the increase in heat transfer coefficient with the increase in fin density were found to be strongly fluid dependent. HTCs of Rl23, a low pressure alternative refrigerant, were similar to those of Rll while HTCs of R134a, an intermediate pressure alternative refrigerant, were roughly 20% higher than those of Rl2. Finally, HTCs of R32, R125, R143a, and R410A were all higher than those of R22 by 30~50%.

  • PDF

Flow Characteristics of Refrigerant Mixtures with R32 in a Capillary Tube (R32를 포함한 R22 대체 혼합냉매의 모세관 유동 특성)

  • Chang, S.D.;Ro, S.T.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.8 no.2
    • /
    • pp.177-186
    • /
    • 1996
  • The characteristics of the flow of pure HFC refrigerants(R32, R125, and R134a) and their mixtures through capillary tubes were investigated experimentally. Two capillary tubes with 1.2mm and 1.6mm inner diameter and 1.5m length were adopted as test sections. Mass flow rates and temperatures and pressures were measured for several condensing temperatures and degrees of subcooling at capillary tube inlet. The effects of the condensing temperature, inner diameter of capillary tube, and subcooling on the mass flow rate of refrigerants were discussed, and the mass flow rates of HFC refrigerants were compared with that of R22. The pressure and temperature distributions along the capillary tube compared with that of R22. The pressure and temperature distributions along the capillary tube show that there is a metastable equilibrium state in the flow through the tube. Underpressure for vaporization increases as refrigerant mass flux increases and inlet subcooling decreases. Empirical correlation was suggested to predict underpressure for vaporization of the HFC refrigerants.

  • PDF

Performance analysis of 20 kW OTEC power cycle using various working fluids (다양한 작동유체를 이용한 20 kW급 해양온도차 발전 사이클 성능 분석)

  • Yoon, Jung In;Ye, Byung Hyo;Heo, Jung Ho;Kim, Hyun Ju;Lee, Ho Saeng;Son, Chang Hyo
    • Journal of Advanced Marine Engineering and Technology
    • /
    • v.37 no.8
    • /
    • pp.836-842
    • /
    • 2013
  • In this paper, the 20 kW Ocean Thermal Energy Conversion(OTEC) is newly proposed in order to select the refrigerant that makes the cycle performance be optimized and the performance of 20 kW OTEC applying 15 pure refrigerants and 16 mixed refrigerants is analyzed. The efficiency of system, the mass flow of working fluids and TPP, which is new concepts, are analyzed. In view of cycle efficiency, R32/R152a (87:13) is the highest efficiency among the refrigerants. At the mass flow of working fluid to make the 20 kW electricity, R717 is shown as the lowest value. And in view of TPP in this study, R32/R134a 70:30 is the most optimized refrigerant. The analysis can confirm that the refrigerant is different along with the part of the system, so it is necessary to select the optimized refrigerant for 20 kW OTEC.

A Computer Simulation Study on the Separation Process for Electronic Grade, Highly Pure Carbon Dioxide through a Cryogenic Distillation (심냉 증류를 통한 전자급 고순도 이산화탄소의 분리 공정에 대한 전산 모사 연구)

  • ILSU PARK;HUNGMAN MOON;JUNGHO CHO
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.34 no.1
    • /
    • pp.83-89
    • /
    • 2023
  • In this study, a computer simulation work has been performed for the separation of electronic grade highly pure carbon dioxide more than 7 N purity through a cryogenic distillation process. For the cold utility as a cooling medium for a condenser of the cryogenic distillation column, propylene was utilized as a refrigerant in the vapor-recompression refrigeration cycle. Through this work, it was concluded that the cryogenic distillation column with two stage compression and refrigeration cycle were essential to obtain a highly-pure liquefied CO2.