On the dual nature of nucleate boiling crisis on porous surfaces

Book · Tue Dec 31 04:00:00 EST 1996

OSTI ID:418147

Mosdorf, R ^[1]; Poniewski, M E ^[2]

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1. Technical Univ. of Bialystok (Poland)
2. Kielce Univ. of Tech. (Poland)

The model of nucleate boiling crisis on porous surfaces presented in the paper is based on an analysis of dynamic properties of the liquid flow in the porous layer. The motion of liquid is caused by the growth and departure of vapor bubbles from the porous surface. It was assumed that the liquid flow cyclically interacts with the vapor bubble in the porous layer. The nucleate boiling crisis begins when the liquid flow accompanying the growth of the vapor bubble becomes chaotic. The carried out analysis allows to conclude that the decrease of the porous layer resistance and the increasing frequency of the departure of vapor bubbles causes the critical heat flux to grow. The nucleate boiling crisis on porous surfaces may be thus dual in nature, depending on the thickness of the porous layer. Analysis results indicate that for thin layers the crisis should occur for almost the same {Delta}T{sub I,kr} as on smooth surfaces. This conclusion is confirmed by experimental results presented in Cieslinski (1995), where identical critical values of the heat flux were obtained for a porous layer with a thickness of 0.1 mm and for smooth surfaces. The paper suggests a correlation defining {Delta}T{sub I,kr} for thin porous layers. Calculations were carried out for water and freon 11.

• OSTI ID: 418147
• Report Number(s): CONF-960815--; ISBN 0-7918-1513-7
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
BUBBLE GROWTH
MATHEMATICAL MODELS
NUCLEATE BOILING
POROUS MATERIALS
THEORETICAL DATA