Heat transfer and bubble formation in pool boiling: Effect of basic surface modifications for heat transfer enhancement

The present project within the joint research program on fundamentals of boiling heat transfer aims at better understanding of the basic processes which produce heat transfer enhancement in nucleate pool boiling. In the experiments, heater surfaces with two kinds of modifications for enhancement in the form of macro cavities with comparatively simple shapes are used in order to link experimental results of bubble formation and heat transfer to the geometric features of the cavities without additional assumptions, and particularly to resolve their overall effect on heat transfer into local convective or evaporative contributions without introducing severe simplifications. The very accurate results on local heat transfer obtained so far around the circumference of the horizontal test tube with and without macro cavities for enhancement, and their combination with the local events connected to growing, departing and sliding bubbles are suitable to interpret the basic convective and evaporative processes which produce heat transfer enhancement in nucleate pool boiling. (c) 2005 Elsevier SAS. All rights reserved.