Unsteady Measurement of Condensate Film Thickness for Solutal Marangoni Condensation by Using Leser Absorption Method : Measurement and Discussion

• Published in: Nihon Kikai Gakkai rombunshuu. B hen Vol. 68; no. 672; pp. 2292 - 2299
• Main Authors: UTAKA, Yoshio, NISHIKAWA, Tetsuji
• Format: Journal Article
• Language: English; Japanese
• Published: The Japan Society of Mechanical Engineers 2002
• Subjects: Laser Absorption Method
• ISSN: 0387-5016; 1884-8346
• DOI: 10.1299/kikaib.68.2292

The objective of the study is to investigate the condensate film thickness for water-ethanol solutal Marangoni dropwise condensation. The laser light absorption method for measuring the unsteady behaviors of the condensate thickness was adopted. The relation between the condensate behavior and the measuring position was specified by the observation using the high-speed digital camera. The variations of the film thickness were measured by changing the surface subcooling for various vapor concentrations. The unsteady variations of the thickness of condensate film, which was appeared after the sweeping of the heat transfer surface by the departing drop and existed among the various drops, and also the initial drop distances in Marangoni dropwise condensation cycle were measured. The dependencies of the minimum film thickness and non-dimensional condensate thickness among the drops on the initial drop distance were shown. It was clarified that the thinnest thickness of the condensate film was around 1 μm. The relation among the dominant factors determining the phenomena was discussed.