화학공학소재연구정보센터
홈 로그인 로그아웃 연락처 사이트맵
Journal of the Korean Industrial and Engineering Chemistry, Vol.12, No.5, 554-559, August, 2001
Export Citation
Electric Field를 이용한 전열관 내 증발열전달 특성
Evaporating Heat Transfer Characteristics of a Smooth Tube Using an Electric Field
이윤수, 이상재, 강희정, 권영철†, 권정태1
  • 선문대학교 기계공학과, 충남 336-840
  • 1남부대학교 자동차기계공학부, 광주 506-302
Yun Su Lee, Sang Jae Lee, Hee Jeong Kang, Young Chel Kweon†, and Jeong Tae Kwon1
  • Division of Mechanical Engineering, Sunmoon University, Chungnam 336-840, Korea
  • 1School of Automotive and Mechnical Engineering, Nambu University, Kwangju 506-302, Korea
E-mail:
초록
본 연구는 전기장에 의한 수평관 내 유동비등 열전달 현상을 이해하기 위해 수행되었으며, 이를 위해 전기장이 인가되지 않았을 때와 전기장이 인가되었을 때의 R-22를 작동유체로 하는 수평 평활관의 증발 열전달계수 및 압력강하를 조사하였다. 실험변수들로 시험부 입구건도, 질량유속, 열유속, DC 고전압을 선정하였고, 시험부내 증발온도는 21℃로 고정시키고 실험을 수행하였다. 냉매의 질량유량은 7.5 kg/h, 8.9 kg/h, 10.5 kg/h, 11.5 kg/h, 열유속은 3 kW/m(2), 5 kW/m(2), 그리고 건도 0에서 0.4까지의 영역에서 DC 고전압(6 kV)을 인가하였다. 본 실험의 결과, EHD 효과에 의해 평활관 내 기포들의 동적 거동이 활발해지며, 또한 관 내부표면에서의 기포들의 이탈이 크게 촉진되어 평활관 내 증발 열전달계수는 전기장이 인가되지 않은 경우에 비해 뚜렷이 증가함을 알 수 있었다. 그리고 질량유량 및 건도가 증가할수록 증발 열전달계수는 증가하며, 이 효과는 전기장 하에서 더욱 뚜렷이 관찰되었다. 또한 질량유량과 건도가 증가함에 따라 관내의 압력강하는 거의 선형적으로 증가하였다.
An experimental study on evaporative heat transfer characteristics in a tube has been performed. The smooth tube with outer diameter of 12.8 mm was used as the heat section, and it was heated by applying hot liquid to the test tube. The working fluid was R-22, and the tube-circular electrode system was used. The DC voltage was applied to the circular electrode, while the tube was grounded. Experiments were conducted at mass flow rates of 7.5 kg/h, 8.9 kg/h, 10.5 kg/h, 11.5 kg/h and heat fluxes of 2 kW/m(2), 5kW/m(2). For each mass flow rate condition, the evaporation temperature was set at 21 ℃. The inlet quality was changed from 0 to 0.4. The results show that the imcrease in the evaporative heat transfer in enhanced largely under the high voltage, compared with that of the normal condition(0 kV). With increasing the mass flow rate and the quality, the evporytive heat transfer conefficients increase and the pressure drop in the tube increases linearly. This effect is remarkable considering it is under the electric field. It is also found that at a low inlet quality the mechanisms of EHD in-tube boiling are closely connected with dynamic behavior of bubbles.
Keywords:electric field;heat transfer enhancement;in-tube flow boiling;evaporation
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