ISSN Online: 2377-424X
International Heat Transfer Conference 3
FUNDAMENTAL ASPECTS OF SUBCOOLED BOILING WlTH AND WITHOUT DISSOLVED GASSES
摘要
I - The effects of dissolved gas in
subcooled boiling (degassing and vaporization)
are experimentally studied in
different conditions : air saturated water
in free and forced convection with
visual observation of the heat exchange
mechanisms (photography and Schlieren
high speed cinematography), stagnant metaterphenyl
at 350°C, pressure less than
4kg/cm2, gas content between 0 and
26cm3/100g, terphenyl in forced convection
at 350-400°C, 5 to 9kg/cm2 pressure,
4 to 10 meters per second convection velocity,
and 10 to 70cm3/100 gas content.
Degassing improves the heat exchange without
increasing the pressure drop as
long as the wall temperature is lower
than the saturation one of the degassed
liquid.
II - In subcooled boiling of degassed water, histograms of bubble dimensions are obtained by a photographic method. They can be considered as the superposition of two distribution curves : the first one corresponds to isolated bubbles, the second one to agglomerated bubbles. Heat exchange mechanisms observed by Schlieren method are briefly recalled.
II - In subcooled boiling of degassed water, histograms of bubble dimensions are obtained by a photographic method. They can be considered as the superposition of two distribution curves : the first one corresponds to isolated bubbles, the second one to agglomerated bubbles. Heat exchange mechanisms observed by Schlieren method are briefly recalled.