• Title/Summary/Keyword: Inner grooved tube

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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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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-290, R-600a Inside Horizontal Double Pipe Heat Exchangers (R-290, R-600a의 수평 이중관형 열교환기내 증발 특성)

  • 홍진우;노건상;권옥배;박기원;오후규
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.12 no.3
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    • pp.309-314
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    • 2000
  • Experimental results for heat transfer characteristics of natural refrigerants R-290, R-600a and HCFC refrigerant R-22 during evaporating inside horizontal double pipe heat exchangers are presented. The experimental apparatus is basically a vapour heat pump system, composed of a compressor, a condenser, expansion devices, a evaporator, and some other peripheral devices. The test sections were horizontal double pipe heat exchangers, which were a pair of smoothed tube, having 10.07 mm ID, 12.07 mm OD, and grooved inner fin tube, having 12.70 mm OD, 0.25 mm fin height, and 75 fins. The local evaporating heat transfer coefficients of natural refrigerants were not much affected with the mass velocity than R-22 and it could be interpreted that the local evaporating heat transfer coefficients of R-22 were increased more than those of R-290, R-600a according to the increment of mass velocity. Moreover, the maximum increment of the heat transfer coefficient was found in R-290. The 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 fin tube, 70% of the increment of the heat transfer coefficient was obtained compared to the smoothed tube.

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Heat Transfer Characteristics of Fin-Tube Heat Exchanger using Two-Port Tube of Small Inner Diameter by Mechanical Expansion (연결세경관을 이용한 휜관형 열교환기의 기계확관에 의한 전열특성)

  • Lee, Sangmu;Park, Byung-Duck
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.28 no.11
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    • pp.428-433
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    • 2016
  • The fin and tube heat exchanger using a two-port tube has in air-conditioner heat exchanger because heat transfer performance. This study investigates the feasibility of a fin and tube heat exchanger using two-port copper tube by mechanical expansion. The optimum size of the tube-expanding bullet for the heat exchanger using two-port tube was through numerical calculation. The heat exchanger using a two-port tube was fabricated by mechanical expansion, and the heat exchanger performance was evaluated condensation and evaporation experiments. Compared to the heat exchanger of a conventional circular tube, the pressure drop per unit length of the heat exchanger with a two-port tube decreased. Compared to the heat exchanger using a conventional circular tube, the overall heat transfer coefficient of heat exchanger with a two-port tube increased up to 13% in the case of condensation, and up to 25% in the case of evaporation. The two-port tube heat exchanger outperforms conventional heat exchanger for air conditioner with a inner grooved circular tube.

Enhancement of Heat and Mass Transfer for a Vertical Type Absorber (수직흡수기의 열 및 물질전달 촉진)

  • 권오경
    • Journal of Advanced Marine Engineering and Technology
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    • v.22 no.3
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    • pp.362-370
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    • 1998
  • Absorption systems require a heat source for working but they have a great merit in that relatively low-temperature and low-quality types of thermal energy such as solar heat and exhaust heat can be effectively utilized as heat source. However details research related to absorbers which have a great effect on performances has been rarely done and thus there has been a strong hope for positive developments to improve their efficiencies. This paper describes absorption experiments made with different inside tube diameters and shapes. The purpose of this study is to acquire basic knowledge about heat and mass transfer in a falling film type absorber with vertical inner tubes. Heat and mass transfer were measured for water vapor absorption into a water/LiBr solution flowing down an absorber of vertical inner tubes. As a result absorption acceleration tube compares bare tube and heat transfer improved by order of insert spring tube corrugated tube grooved tube. And the acceleration that is good provided in inserting spring tube for both sides of heat and mass transfer.

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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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Cycle performance of refrigeration and air-conditioning system using the hydrocarbon refrigerant R-290 (탄화수소계 냉매 R-290을 사용하는 냉동.공조 장치의 사이클 특성에 관한 연구)

  • 박기원
    • Journal of Advanced Marine Engineering and Technology
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    • v.23 no.4
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    • pp.447-452
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    • 1999
  • This paper describes the cycle performance of heat-pump system using R-22 and R-290. Experiments were performed in the smooth tube with inside diameter of 10.07mm and outside diameter of 12.07 mm and grooved inner tube having 75 fins with a height of 0.25mm Condensing temperatures were held constantly between 318K and 328 K while evaporating temperatures were varied from 257 K to 288 K mass velocities from 51 to $280 kg/m^2s$. From the experiments it was known that the evaporating temperature and condensing temperature had more affected by the compressor shaft power than the tube geometries. Cooling capacity of the R-22 and R-290 had similar values in the smooth and grooved inner tubes. The coefficient of performance(COP) was calculated using the compressor shaft power volumetric refrigeration capacity compression ratio and cooling capacity. The COP of the R-290 had slightly higher values than that of R-22 The major parameters affecting the heat pump cycle performance wee the refrigerant proper-ties and operating conditions rather than the geometric shapes of the heat exchanger

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Effects of the Groove Type Tubes on Friction Factors in the Annuli (이중관에서 홈형튜브가 압력강하에 미치는 효과)

  • 안수환;손강필;신승화
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2001.05a
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    • pp.100-105
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    • 2001
  • The present paper is to present the results of studied of pressure drop in annuli with corrugated and spirally fluted inner tubes for the turbulent flow regime. To understand the underlying physical phenomena responsible for heat transfer enhancement, flow mechanism documented elsewhere are combined with pressure drop measurements to confirm the friction factors obtained from the annuli with the grooved inner tubes for the Reynolds number of 1000 to 8000. Friction factors were found to be functions of trough depth, pitch and angle, and the annulus radius ratio. friction factor increases in the spirally fluted tubes were larger than those in the corrugated tubes.

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