Numerical Simulation of Laminar Film Condensation in a Horizontal Minitube with and Without Non-Condensable Gas by the VOF Method

Summary, in English

Based on the volume of fluid (VOF) method, a steady three-dimensional numerical simulation of laminar film condensation of water vapor in a horizontal minitube, with and without non-condensable gas, has been conducted. A user-defined function defining the phase change is interpreted and the interface temperature is correspondingly assumed to be the saturation temperature. An annular flow pattern is to be expected according to a generally accepted flow regime map. The heat-transfer coefficient increases with higher saturation temperature and a smaller temperature difference between the saturation and wall temperatures, but varies little with different mass flux and degree of superheat. The existence of a non-condensable gas will lead to the generation of a gas layer between vapor and liquid, resulting in a lower mass-transfer rate near the interface and higher vapor quality at the outlet. In consequence, the heat-transfer coefficient of condensation with a non-condensable gas drops sharply compared with that of pure vapor condensation. Meanwhile, the non-condensable gas with a smaller thermal conductivity would cause a stronger negative effect on heat flux as a result of a higher thermal resistance of heat conduction in the non-condensable gas layer.

• Författare: Zhan Yin; Yanling Guo; Bengt Sundén; Qiuwang Wang; Min Zeng
• Avdelning/ar: Värmeöverföring
• Publiceringsår: 2015
• Språk: Engelska
• Sidor: 958-977
• Publikation/Tidskrift/Serie: Numerical Heat Transfer Part A: Applications
• Volym: 68
• Issue: 9
• Länkar: http://dx.doi.org/10.1080/10407782.2015.1023143
• Dokumenttyp: Artikel i tidskrift
• Förlag: Taylor & Francis
• Ämne: Energy Engineering
• Status: Published
• ISBN/ISSN/Övrigt: ISSN: 1040-7782