Heat transfer enhancement of a steam condensation by mixing ethanol vapor
The heat transfer enhancement of ethanol vapor mixing into steam were investigated. First, it was shown that the influence of the cooling intensity revealed themselves remarkably on the heat transfer rate and the modes of condensate varied with the change in cooling intensity. The effect could be shown as the condensation characteristic curve (Marangoni condensation curve) that exhibited the variation of the heat flux or the heat transfer coefficient against the surface subcooling. It was also confirmed that the enhancement effect of the heat transfer is considerable by using the mixing of small quantities of ethanol vapor into steam. Next, the effect of principal conditions such as the vapor concentration, the vapor velocity and the height of heat transfer surface on the condensation characteristic curves for the vapor mixture of water-ethanol were clarified. As a result, the maximum peak value of the heat transfer coefficient appeared at about ethanol vapor mass fraction of 0.05 due to the experiment of varying ethanol concentration. The condensation characteristic curve moved parallel to the axis of the heat transfer coefficient with increasing vapor velocity. The effect of vapor velocity acted as the reduction of the diffusion resistance in the vapor layer for relatively small surface subcooling region and the reduction of the condensate resistance in the region of the steep increase and transition regions. Although the peak value of the heat transfer coefficient decreased with increasing distance from the top of the condensing surface, the heat transfer coefficient was independent on the position of the surface in the steep increase region.
- Research Organization:
- Yokohama National Univ. (JP)
- OSTI ID:
- 20014108
- Resource Relation:
- Conference: 1999 International Joint Power Generation Conference, Burlingame, CA (US), 07/25/1999--07/28/1999; Other Information: PBD: 1999; Related Information: In: Proceedings of the 1999 international joint power generation conference (PWR-Vol. 34). Volume 2: Power, by Penfield, S.R. Jr.; Hayes, R.H.; McMullen, R. [ed.], 752 pages.
- Country of Publication:
- United States
- Language:
- English
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