Transactions of the Korean Society of Mechanical Engineers B (대한기계학회논문집B)

The Korean Society of Mechanical Engineers (대한기계학회)
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An Experimental Study on Evaporative Heat Transfer Characteristics in a Small Diameter Tube

미소직경관 내 증발열전달 특성에 관한 실험적 연구

  • Hwang, Yun-Uk (Dept.of Mechanical Aerospace Engineering, Graduate School of Seoul National University) ;
  • Kim, Min-Su (Dept.of Mechanical Aerospace Engineering, Seoul National University)
  • 황윤욱 (서울대학교 대학원 기계항공공학부) ;
  • 김민수 (서울대학교 기계항공공학부)
  • Published : 2001.02.01
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Abstract

Experiments have been performed to investigate evaporative heat transfer characteristics of R-134a flowing in a small diameter tube. Test section was made of stainless steel tube with an inner diameter of 2.2mm and was uniformly heated by electric current which was applied to the tube wall. The local saturation temperature of refrigerant flowing in a tube is calculated from the measured local saturation pressure by using an equation of state. Inner wall temperature was calculated from measured outer wall temperature, accounting for heat generation in the tube and one dimensional heat conduction through the tube wall. Mass quality of refrigerant flowing in a tube was calculated by considering energy balance in the pre-heater and the test section. Heat flux was varied from 19 to 64kW/$m^2$, and mass flux was chanted from 380 to 570kg/$m^2$s for each heat flux condition. From this study, heat transfer in a small diameter tube is affected by heat flux as well as mass flux for a wide range of mass quality. Heat transfer coefficient in a small diameter tube is much greater than that in medium sized tubes. Test results in this study are compared with Gungor and Winterton correlation, which gives an absolute average deviation of 27%.

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References

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