ISSN Online: 2377-424X
International Heat Transfer Conference 12
Curvature and contact angle measurements in an unstable evaporating extended meniscus
Résumé
A novel loop Constrained Vapor Bubble (CVB) heat exchanger system was used to study instabilities in an
evaporating extended meniscus of ethanol. To simultaneously measure the curvature and apparent contact angle
of the unstable liquid film, an image analyzing technique was used. The film's motion was first characterized by
a small amplitude and high oscillation frequency. During this period the contact angle was relatively constant
but curvature doubled. In the second phase, the film spread out to flood the surface and both the curvature and
contact angle decreased. Finally the spreading film receded, leaving the first two fringes on the flat surface ahead
of the main meniscus for thin film evaporation. We found that this kind of unstable film can increase heat
transport capacity.