• Title/Summary/Keyword: Inner grooved tube

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Effects of Fin Configuration on the Evaporator Performance (휜 형상에 따른 증발기의 전열 성능)

  • Lee, Jin Ho;Kwon, O Kap
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.2 no.1
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    • pp.27-36
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    • 1990
  • An experimental investigation was made to study the performance characteristics of evaporator having different fin configurations and tube inner grooves. Three different types of fin such as super slitted fin, slitted fin, plain fin, and two types of tube such as inner grooved tube, and bare tube, are tested varying the air velocity, evaporation temperature and superheat of refrigerant. Results show that in the range of air side Reynolds number $3{\times}10^3\;-\;1.5{\times}10^4$ evaporator with super slitted fin and inner grooved tube shows best performance. It is 80% higher in overall heat transfer coefficient and 2.6 times higher in pressure loss compared to that with plain fin inner grooved tube. Friction factor is found to be almost independent of evaporating temperature and degree of superheat, while Colburn j factor varies with evaporating temperature.

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A study about shape processing for the bend of the Copper-Tube that use Hair Pin Bending Machine (Hair Pin Bending Machine을 이용한 동 튜브 굽힘 성형가공에 관한 연구)

  • Kang, Heung-Sik;Kim, Dong-Sung;Heo, Sin;Hong, Sung-In
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1705-1708
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    • 2003
  • The purpose of this study is to investigate the manufacturing technique on the U type Draw-Bending of inner grooved tube. This bending process make the U shape tube by Hair Pin Bending machine. The U type tube requires the quality of product that satisfy sufficient conditions for a heat exchanger. The mandrel components act the important roles that prevent wrinkles and keep the shape of cross section of bended tube at bending process. We performed the FEM simulation using LS-DYNA software and the bending test of inner groove tube and then, compared bending simulation with bending test results about mandrel ball diameter, mandrel position and optimal clearance between mandrel and tube.

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Condensation heat transfer characteristics of hydrocarbon refrigerants R-290 and R-600a inside horizontal tubes (탄화수소계 냉매 R-290, R-600a의 수평관내 응축 열전달 특성에 관한 연구)

  • 박승준;박기원;노건상;정재천;오후규
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.12 no.1
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    • pp.20-25
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    • 2000
  • An experimental study on the condensation heat transfer coefficients of R-22, R-290 and R-600a inside horizontal tube was performed. Heat transfer measurements were performed for smooth tube with inside diameter of 10.07 mm and outside diameter of 12.07 mm and inner grooved tube having 75 fins whose height is 0.25 mm. This study was performed for condensation temperatures were from 308 K to 323 K, and mass velocity of $51 kg/m^2s - 250kg/m^2s$. The test results showed that the local condensation heat transfer coefficients increased as the mass flux increased, and also the effect of mass flow rate on heat transfer coefficients of R-290 was less than R-22. In addition, heat transfer coefficient of R-22 increased to a larger extent than R-290 and R-600a as the mass flow rate increased. Average condensation heat transfer coefficients of natural refrigerants were superior to that of R-22. The present results had a good agreement with Cavallini-Zecchin's correlation for smooth and inner grooved tubes.

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Evaporating heat transfer characteristics of R-22 alternative hydrocarbon refrigerants at heat exchanger using grooved inner tube (내면 핀관을 사용하는 열교환기에서 R-22 대체 탄화수소계 냉매의 증발 열전달 특성)

  • 홍진우;박승준;노건상;구학근;오후규
    • Journal of Advanced Marine Engineering and Technology
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    • v.24 no.4
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    • pp.414-420
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    • 2000
  • In this paper, evaporation heat transfer characteristics at a inner grooved tube were studied using a new natural refrigerants R-290, R-600a and HCFC refrigerant R-22. Experiments were performed in the inner tube with outside diameter of 12.70mm, having 75 fins with a fin height of 0.25mm. The following results were obtained from this research. On the evaporating heat transfer characteristics, the maximum increment of heat transfer coefficient was found in R-290. Average heat transfer coefficient was obtained the maximum value in R-290 and the minimum value in R-22. It reveals that the natural refrigerant can be used as a substitute for R-22. In the grooved inner tube, 70% of the increment of the heat transfer coefficient was obtained compared to the smooth tube. Comparing the heat transfer coefficient between experimental results and simulation data of other's, the Kandlikar's correlated equation was closely approximated to the author's experimental results in the smooth tube or grooved inner one.

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Study on Condensation Heat Transfer Characteristics of Hydrocarbons Natural Refrigerants

  • Oh, Hoo-Kyu;Park, Seung-Jun;Park, Ki-Won;Roh, Geon-Sang;Jeong, Jae-Cheon
    • International Journal of Air-Conditioning and Refrigeration
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    • v.9 no.3
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    • pp.10-17
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    • 2001
  • This study investigated the condensation heat transfer coefficients of R-22, R-290 and R-600a inside horizontal tube. Heat transfer measurements were performed for smooth tube with inside diameter of 10.07 mm and outside diameter of 12.07 mm and inner grooved tube having 75 fins whose height is 0.25 mm. Condensation temperatures and mass velocity were ranged from 308K to 323 K and $51kg/m^2s$ to $250kg/m^2s$, respectively. The test results showed that the local condensation heat transfer coefficients increased as the mass flux increased, and also the effects of mass velocity on heat transfer coefficients of R-290 and R-600a were less than those of R-22. Average condensation heat transfer coefficients of natural refrigerants were superior to that of R-22. The present results had a good agreement with Cavallini-Zecchin's correlation for smooth and inner grooved tubes.

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