소수성 구리 표면에서의 액적 응축에 관한 액적 성장및 열전달 특성 연구Investigation of Droplet Growth and Heat Transfer Characteristics during Dropwise Condensation on Hydrophobic Copper Surface
- Authors
- 이형주; 정찬호; 김대윤; 문주현; 이재빈; 이성혁
- Issue Date
- 2018
- Publisher
- 한국액체미립화학회
- Keywords
- Dropwise condensation; Droplet growth behavior; Hydrophobic surface; Condensation heat transfer; 액적 응축; 액적 성장 거동; 소수성 표면; 응축 열전달
- Citation
- 한국액체미립화 학회지, v.23, no.3, pp 149 - 153
- Pages
- 5
- Journal Title
- 한국액체미립화 학회지
- Volume
- 23
- Number
- 3
- Start Page
- 149
- End Page
- 153
- URI
- https://scholarworks.bwise.kr/cau/handle/2019.sw.cau/2533
- DOI
- 10.15435/JILASSKR.2018.23.3.149
- ISSN
- 1226-2277
- Abstract
- The present study investigates the heat transfer characteristics of droplet growth during dropwise condensation on the hydrophobic copper surface. We use the copper specimen coated by the self-assembled layer and conduct the real-time measurement of droplet size and spatial distribution of condensates during condensation with the use of the K2 lens (long distance microscope lens) and CMOS camera. The temperatures are measured by three RTDs (resistance temperature detectors) that are located through the holes made in the specimen. The surface temperature is estimated by the measured temperatures with the use of the one-dimensional conduction equation. It is observed that the droplets on the surface are growing up and merging, causing larger droplets. The experimental results show that there are three distinct regimes; in the first regime, individual small droplets are created on the surface in the early stage of condensation, and they are getting larger owing to direct condensation and coalescence with other droplets. In the second and third regimes, the coalescence occurs mainly, and the droplets are detached from the surface. Also, the fall-off time becomes faster as the surface wettability decreases. In particular, the heat transfer coefficient increases substantially with the decrease in wettability because of faster removal of droplets on the surfaces for lower wettability.
The present study investigates the heat transfer characteristics of droplet growth during dropwise condensation on the hydrophobic copper surface. We use the copper specimen coated by the self-assembled layer and conduct the real-time measurement of droplet size and spatial distribution of condensates during condensation with the use of the K2 lens (long distance microscope lens) and CMOS camera. The temperatures are measured by three RTDs (resistance temperature detectors) that are located through the holes made in the specimen. The surface temperature is estimated by the measured temperatures with the use of the one-dimensional conduction equation. It is observed that the droplets on the surface are growing up and merging, causing larger droplets. The experimental results show that there are three distinct regimes; in the first regime, individual small droplets are created on the surface in the early stage of condensation, and they are getting larger owing to direct condensation and coalescence with other droplets. In the second and third regimes, the coalescence occurs mainly, and the droplets are detached from the surface. Also, the fall-off time becomes faster as the surface wettability decreases. In particular, the heat transfer coefficient increases substantially with the decrease in wettability because of faster removal of droplets on the surfaces for lower wettability.
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