Abstract: Some factors were summarized systematically according to the research in China and abroad in recent years, including convection flow state, phasetransformation, geometric factors, fluid pulse, fluid physical properties and viscosities. At the same time, some methods of enhancing heat transfer in tubes were also summarized, such as additives, electrohydrodynamical, metal foam filled pipes etc. Finally, the characteristics and the method of heat transfer enhancement were analyzed in highmedium temperature solar power systems.

Key words: tube; convection; heat transfer; heat transfer enhancing