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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Experimental Study of Transport Phenomena at the Onset of Nucleate Boiling Using a Boilingmeter

Get access (open in a dialog) DOI: 10.1615/IHTC15.pbl.009404
pages 6189-6203

Sinopsis

The purpose of this study is a contribution to a better understanding of transport phenomena in the region of the onset of nucleate boiling. The aim is to characterize the transport phenomena with controlled operating conditions (thermodynamics of the fluid, incondensable, etc.) as well as the surface state. Experimental investigations were carried out in natural convection and nucleate boiling regimes. An experimental device was realized to perform boiling experiments with FC72 on flat heating wall in different operating conditions. In this work, we studied the effect of the saturation pressure of the fluid as well as the inclination angle of the heated surface on the transport phenomena and wall superheat at the ONB. With regard to the effect of the saturation pressure, investigated in the range 0.2 to 1 bar, the superheat at the ONB decreases as a function of the saturation pressure. The interpretation of this result has been conducted considering both the influence of the saturation pressure on the natural convection and the nucleation.. A criterion based on a competition between natural convection and boiling has been proposed. Concerning the inclination angle, a lower value of the wall superheat at the ONB was measured in case of a downward heat flux compared to an upward heat flux. As the surface state was the same for all the experiments, again the natural convection is the main phenomenon influencing the ONB and by the way the transport phenomena. These investigations indicate a strong effect of natural convection on the superheat at the ONB.