수직원관 외부 유하액막 열전달에 주변 기체유동이 미치는 영향

The Effect of Surrounding Gas Flow on the Heat Transfer of the Falling Film Flowing Down the Outside of a Vertical Tube

  • 권경민 (서강대학교 기계공학과 대학원) ;
  • 정시영 (서강대학교 기계공학과) ;
  • 김병주 (홍익대학교 기계시스템디자인공학과)
  • 발행 : 2002.12.01

초록

Heat transfer characteristics were investigated for the falling film flowing down the outside of an electrically heated vertical tube. Water was used for the falling film, and its Reynolds number was varied in the range of 70~500. Because water is heated and evaporated as it flows down, both sensible and latent heat transfer should be considered. The effect of the surrounding air movement was investigated by changing the direction of the air injection; without air injection, parallel-flow, and counter-flow. For all cases, sensible teat transfer rate was almost linearly increased with the increasing film flow rate. It was found that the film heat transfer coefficient was hardly influenced by the parallel air flow. However, the counter-flow of air reduced the heat transfer coefficient, which might be caused by the uneven distribution or flooding of the film. At high heat flux, a sudden change of the film heat transfer coefficient was detected as the film flow rate reached the transition value. It is supposed that this phenomenon was caused by the change in the film flow pattern.

키워드

참고문헌

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