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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

MICROSCOPIC MECHANISMS OF THE DISTURBANCE FREQUENCY EFFECT ON HEAT TRANSFER ENHANCEMENT IN WAVY CONDENSATE FILMS

Get access (open in a dialog) DOI: 10.1615/IHTC16.mpf.023219
pages 6289-6296

Resumo

It is of great significance to investigate the microscopic mechanism of heat transfer enhancement in wavy film as wavy condensation film is frequently encountered in various industrial fields because of its high energy efficiency. A numerical model, in which the wavy interface is tracked by a non-orthogonal coordinate transformation, is developed to study the effect of disturbance frequency on wave heat transfer enhancement along a vertical wall. A sinusoidal disturbance is introduced by a fictitious body force to sustain waves. A disturbance frequency of 16 Hz associated with the critical film Reynolds number is numerically determined by analyzing the generated neutral stability curve. Compared with other disturbance frequencies, the wave effect on heat transfer enhancement is the most significant at 16 Hz. The minimum time-averaged thickness and the maximum proportion of substrate film length in the wave length proves that the film thinning effect is dominated by the length of the film substrate rather than the substrate film thickness. The profile of the normal velocity close to the wall in solitary waves shows that the variation of the normal velocity from negative to positive in the normal direction at the wave front is more notable at 16 Hz. This change of the normal velocity accounts for the convection effect of heat transfer enhancement due to the fact that the positive normal velocity, which flows away from the wall, contributes to increasing the temperature gradient and heat transfer coefficient.