핵비등 영역의 가열면상 물 액적의 증발에 대한 연구

Abstract

본 연구는 동판, 탄소강판, 스테인레스강판의 가열면상 증류수 액적의 증발시간 및 표면의 온도변화에 대한 것으로 가열면의 초기온도는 핵비등이 존재하는 최저온도로부터 최고 온도 영역의 범위 내에서 논했다.

액적 밑면의 가열면 온도는, Rohsenow가 제시한 푸울 핵비등 열전달 관계식을 사용하여, 2차원 천이 열전도 해석으로부터 계산했으며, 가열면 재질 및 초기 액적크기 등에 따라 합리적인 변화 결과를 얻었다. 또한 본 연구에서 제시한 액적증발 모델은 액적과 가열면간의 접촉면적 변화를 계산하는데 사용되었다. 시간에 의존하는 접촉면 온도와 액적의 기하학적 형상 변화로부터, 특정 액체/고체조합에서 전 증발시간을, 초기 가열면 온도와 초기 액적 크기와 관련하여, 예측했다.

This paper discusses the evaporation time of a pure water droplet on smooth surface of copper, carbon steel and stainless steel. The initial surface temperature ranges from the lowest limit to the highest limit of the nucleate boiling region.

The surface temperature just below the droplet is calculated from the 2 dimensional transient conduction, using the transfer correlating equation of nucleate pool boiling proposed by Rohsenow. And the evaporation model proposed in this paper is used to calculate the changes of contact area between liquid droplet and heated surface. With these time dependent values of surface temperature and those of geometrical shape of droplet, the total evaporation time for a specific liquid-solid combination can be predicted as the initial surface temperature and the initial droplet size.

The predicted evaporation times are compared with the experimental data. Though the present model consists of some assumptions which include bubble waiting time, heat transfer coefficient and the shape of liquid droplet on surface, the predictions and measurements are in good agreement.

This paper discusses the evaporation time of a pure water droplet on smooth surface of copper, carbon steel and stainless steel. The initial surface temperature ranges from the lowest limit to the highest limit of the nucleate boiling region.

The surface temperature just below the droplet is calculated from the 2 dimensional transient conduction, using the transfer correlating equation of nucleate pool boiling proposed by Rohsenow. And the evaporation model proposed in this paper is used to calculate the changes of contact area between liquid droplet and heated surface. With these time dependent values of surface temperature and those of geometrical shape of droplet, the total evaporation time for a specific liquid-solid combination can be predicted as the initial surface temperature and the initial droplet size.

The predicted evaporation times are compared with the experimental data. Though the present model consists of some assumptions which include bubble waiting time, heat transfer coefficient and the shape of liquid droplet on surface, the predictions and measurements are in good agreement.