HEAT TRANSFER ENHANCEMENT IN BOILING OVER MODIFIED SURFACES: A CRITICAL REVIEW

Boiling enhancement has been strongly linked to surface modification techniques for many decades. However, improvements in this field are always emerging, making it necessary to catch up with recently applied methods of increasing the critical heat flux and heat transfer coefficient. This review outlines the basic ideas of four surface modification techniques (roughness, artificial cavities, pin-fins, and wettability) and their effect on heat transfer performance. For each of the aforementioned surface modification techniques, cited works are classified and evaluated according to the type of boiling (flow or pool), the kind of working fluid used (water or other refrigerant), and the magnitude of heat exchanged (high or low heat flux). A respective enhancement factor, defined as the percentage of the performance of the corresponding plain surface, is calculated for each experimental work in order to compare them on a common ground. Comprehensive plots and tables are constructed herein using data from the cited works to allow direct comparison of the results. In addition, an effort is made through the cited works to identify the role of surface topography on heat transfer mechanisms and bubble dynamics. Finally, recommendations for future research are presented.