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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

VISUALIZED EXPERIMENT OF BUBBLE BEHAVIORS IN A NARROW RECTANGULAR CHANNEL UNDER NATURAL CIRCULATION CONDITION

Get access (open in a dialog) DOI: 10.1615/IHTC16.nee.024262
pages 7533-7540

Аннотация

For flow boiling in vertical narrow rectangular channels, the bubbles generated by heating surface affect the distribution of heat flux, the bubble growth, detachment and slide have an impact on the distribution of heat, thus it is of great importance to analyze bubble behaviors and characteristics. Especially in regard to the related issues in vertical narrow rectangular channel under natural circulation, due to the limitation of wall conditions, the bubble behavior is different from the conventional channel. A visualized one-side heating narrow rectangular channel has been used for the analysis of the bubble behaviors and characteristics. A series of digital image processing algorithms has been adopted to deal with the initial pictures shot by the high-speed camera. From the pictures it can be obtained that the bubbles generated are divided into two categories according to the length of movement distances and diameter changes rates. Within the scope of this experiment, the share of second type bubble decreases obviously as the inlet subcooling and heat flux increases. The bubble growth diameters in various experimental conditions were obtained by analyzing the recorded pictures, a power law model was adopted to predict the bubble growth diameters.