• 에너지공학
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• 제9권3호
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• pp.192-201
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• 2000

증발기와 응축기로 폐회로 냉동 시스템을 구성하여 기존 사용 냉매인 R22와 대체냉매로써 부각되고 있는 R407C, R410A를 사용하여 여러 가지 관 직경과 휜 형상을 가지는 열교환기에 대한 열전달량, 질량유량, 열교환기를 지나가는 냉매의 온도분포 그리고 공기측 압력강하를 측정하였다. 모든 열교환기에서 냉매의 질량유량이 증가함에 따라 열전달량은 증가하였다. R22와 R407C의 경우에 증발기측에서는 거의 같은 열전달량을 나타냈고 응축기측에서는 R407C가 전체적으로 열전달량이 높게 나타났다. 그리고 열교환기의 전달량은 유로의 형상보다는 냉매의 질량유량과 전열면적에 더 많은 영향을 받는다. 공기측 압력 강하는 열수가 많은 열교환기의 경우가 작게 나타났으며 슬릿휜을 가지는 열교환기의 압력강하가 가장 크고 웨이비휜을 가지는 열교환기가 가장 작게 나타났다.

• 설비공학논문집
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• 제10권1호
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• pp.56-65
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• 1998

In this paper, experimental investigation of capillary tube performance for R-407C is performed. The experimental setup is made of real vapor-compression refrigerating system. In this study, mass flow rate is measured for capillary tubes of various diameter and length as inlet pressure and degree of subcooling are changed. These data are compared with the results of a numerical model. The mass flow rates of the numerical model are less than by 14% compared with the measured mass flow rates. It is found that mass flow rate and length for R-407c are less than those of R-22 under the same condition. Also based on this experimental study and the numerical model, a set of capillary tube selection charts for R-407C is constructed.

• 설비공학논문집
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• 제9권3호
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• pp.276-283
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• 1997

The nucleate boiling heat transfer experiments are performed using a ternary refrigerant R407C which is a candidate of alternatives of HCFC 22. The boiling phenomena for R-32, R-125, and R-134a which are the constituent refrigerants of R407C are also investigated to give the foundation of theoretical research for the mixture component boiling. The nucleate boiling heat transfer coefficients of R407C is less than those of HCFC 22 which has the similar physical and transport properties. Since the experimental results show the deterioration of boiling heat transfer coefficients of ternary mixture refrigerants R407C, the boiling heat transfer coefficients of R407C cannot be obtained by the linear combination of boiling heat transfer coefficients from its constituent components R-32, R125, and R134a.

• Journal of Advanced Marine Engineering and Technology
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• 제32권4호
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• pp.542-549
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• 2008

The evaporation heat transfer coefficient and pressure drop of R-22 and R-407C in a horizontal copper tube were investigated experimentally. The main components of the refrigerant loop are a receiver, a compressor, a mass flow meter, a condenser and a double pipe type evaporator (test section). The test section consists of a smooth copper tube of 6.4 mm inner diameter. The refrigerant mass fluxes were varied from 100 to $300\;kg/m^2s$ and the saturation temperature of evaporator were $5^{\circ}C$. The evaporation heat transfer coefficients of R-22 and R-407C increase with the increase of mass flux and vapor quality. The evaporation heat transfer coefficients of R-22 is about $5.68{\times}46.6%$ higher than that of R-407C. The evaporation pressure drop of R-22 and R-407C increase with the increase of mass flux. The pressure drop of R-22 is similar to that of R-407C. In comparison with test results and existing correlations, correlations failed to predict the evaporation heat transfer coefficient of R-22 and R-407C. therefore, it is necessary to develope reliable and accurate predictions determining the evaporation heat transfer coefficient of R-22 and R-407C in a horizontal tube.

• 한국가스학회지
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• 제12권3호
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• pp.43-49
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• 2008

본 연구에서는 내경 4.3 mm와 6.4 mm의 수평동관내 R-22와 R-407C의 증발 열전달과 압력강하를 실험적으로 조사하였다. 냉매 순환루프의 주요구성품은 수액기, 압축기, 질량유량계, 응축기, 이중관식 증발기 (시험부)로 구성된다. 시험부는 내경 4.3 mm와 6.4mm의 평활 동관으로 이루어져 있다. 냉매질량유속은 $100\;kg/m^2s$에서 $300\;kg/m^2s$까지 변화시켰고, 증발기 냉매포화온도는 $5^{\circ}C$이다. R-22와 R-407C의 증발 열전달계수는 질량유속과 증기건도의 증가와 함께 따라 상승한다. 내경 4.3 mm와 6.4mm관내 R-22의 증발 열전달계수가 R-407C에 비해 각각 $7.3{\sim}47.1%$와 $5.68{\sim}46.6%$ 정도 높다.

• 설비공학논문집
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• 제11권4호
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• pp.492-498
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• 1999

Mass flow rates of R407C and R290 through capillary tubes were measured with various capillary tube geometries and flow conditions. For all refrigerants tested in the present study, mass flow rate through the capillary tube was strongly dependent on the condensing pressure, subcooling and capillary length and diameter. The flow rate of R407C was 5~10［%］ higher than that of R22 at the same condensing temperature and degree of subcooling, while flow rate for R290 was 40［%］ lower than that for R22. Based on experimental results, an empirical correlation was developed using Pi theorem to predict the mass flow rate through capillary tubes. The predicted flow rates using the model were consistent with the experimental data within ${\pm}$10[%］.

• Journal of Advanced Marine Engineering and Technology
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• 제22권2호
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• pp.210-218
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• 1998

Experimental results for forced convection condensationof Refrigerant-22 and ternary Refrigerant-407c(HFC-32/125/134a 23/25/52 wt%) considered as a substitute R-22 inside horizontal micor-fin tubes are presented. The test section was horizontal double-tubed counterflow condenser with a length 4000 mm micro-fin tube having 9.53 mm OD., 0.2 mm fin height and 60 fins. The refrigerants R-22 and R-407c were cooled by a coolant circulated in a surrounding annulus. The range of parameters of mass velocity was varied from 102.1 to 301.0kg/($\textrm{m}^{2}.s$) with inlet quality 1.0. Both refrigerant R-22 and its alternative refrigerant R-407c were tested within the same range of parameters. At the given experimental conditions for R-22 and R-407c the pressure drops for R-407c were considerably higher than those for R-22 at micro-fin tubes. Over the mass velocity range tested the PF(penalty factor)was lower than the increasing ratio of heat transfer area by fins. Based on the data correlation was proposed for predicting the frictional pressure drops for R-22 and R-407c for a duration of condensation inside a horizontal micro-fin tube.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2003년도 유체기계 연구개발 발표회 논문집
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• pp.607-612
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• 2003

• Journal of Advanced Marine Engineering and Technology
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• 제20권4호
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• pp.70-80
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• 1996

Experimental results for forced convection condensation of R-22 and R-407C inside 7.5mm ID and 4000mm length of horizontal tubes are presented. The experimental data covered total flow rate from 114.3 to 267.1kg/($m^2$.s) and quality from 0 to 1. The vapor temperature and pressure drop along the tube were measured. The pressure drop for R-407C increased with flow rate similar to that of R-22. The experimental data compared with the available perdictions for pressure drop. Based on the data a prediction method was presented for the calculation of pressure drop of R-22 alternative refrigerants.

• Journal of Advanced Marine Engineering and Technology
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• 제21권2호
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• pp.144-156
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• 1997

Experimental results for forced convection heat transfer of pure refrigerant and nonrefrigerant mixtures during condensing inside horizontal smooth tubes, double pipe heat exchanger of 7.5 mm ID and 4 000 mm long inside tube, are presented. Pure refrigerant R - 22 and R - 407 c, the mixture of R - 32 + R - 125 + R - 134a (23/25/52, wt %) are used as the test fluids. The ranges of parameters are $114.3{\sim}267.1 kg/(m^2 {\cdot} s)$ of mass velocity, <0$\sim$1.0 of quality. The vapor pressure, vapor temperature and tube wall temperature were measured. Using these data, the local and average heat transfer coefficients for the condensation are obtained. At the same given experimental conditions, the condensation heat transfer coefficients for NARMs R - 407c were lower than those for the pure refrigerant of R - 22. Local heat transfer characteristics for R - 407c were different from pure refrigerant R - 22. The condensaheat transfer coefficients for R - 407c and R - 22 increased with mass velocity. Based on the data a prediction method was presented for the calculation of dimensionless average heat transfer coefficient.