Electric Field Effect on the Rise of Single Bubbles during Boiling
An experimental study of saturated pool boiling on a single artificial nucleation site without and with the application of an electric field on the boiling surface has been conducted. N-pentane is boiling on a copper surface and is recorded with a high speed camera providing high quality pictures and movies. The accuracy of the visualization allowed establishing an experimental bubble growth law from a large number of experiments. This law shows that the evaporation rate is decreasing during the bubble growth, and underlines the importance of liquid motion induced by the preceding bubble. Bubble rise is therefore studied: once detached, bubbles accelerate vertically until reaching a maximum velocity in good agreement with a correlation from literature. The bubbles then turn to another direction. The effect of applying an electric field on the boiling surface in finally studied. In addition to changes of the bubble shape, changes are also shown in the liquid plume and the convective structures above the surface. Lower maximum rising velocities were measured in the presence of electric fields, especially with a negative polarity.
Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1339309Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 729
 S. Laohalertdecha, P. Naphon and S. Wongwises, A Review of Electrohydrodynamic Enhancement of Heat Transfer, Renew. Sustain. Energy Rev., vol. 11, Issue 5, pp. 858-876, 2007.
 W.L. Haberman and R.K. Morton, An Experimental Investigation of the Drag and Shape of Air Bubbles Rising in Various Liquids, Navy Department, The David W. Taylor Model Basin, Report 802, NS 715102, 1953.
 T.Z. Harmathy, Velocity of Large Drops and Bubbles in Media of Infinite or Restricted Extent, A.I.Ch.E. Journal, vol. 6, Issue 2, pp. 281-288, 1960.
 E.G. Keshock and R. Siegel, Forces Acting on Bubbles in Nucleate Boiling under Normal and Reduced Gravity Conditions, NASA, Technical Note D-2299, 1964.
 J.F. Harper, Bubbles Rising in Line: Why is the First Approximation so Bad, J. Fluid Mech., vol. 351, pp. 289-300, 1997.
 F.N. Peebles, H.J. Garber, Studies on the Motion of Gas Bubbles in Liquids, Chem. Eng. Progress, vol. 49, pp. 88-97, 1953.
 S. Siedel, S. Cioulachtjian and J. Bonjour, Experimental Analysis of Bubble Growth, Departure and Interactions during Pool Boiling on Artificial Nucleation Sites, Exp. Therm. Fluid Sci., vol. 32, Issue 8, pp. 1504-1511, 2008.
 M. Jenny, J. Dušek and G. Bouchet, Instabilities and Transition of a Sphere Falling or Ascending Freely in a Newtonian Fluid, J. Fluid Mech., vol. 508, pp. 201239, 2004.