Abstract: In order to study the heat transfer characteristics of the twophase thermosyphon,its internal flow was analysed theoretically, a criterion affecting its working limit was deduced. By studying the heat transfer characteristics through experiments, an experiential formula of the equivalent heat transfer coefficient was established including the influences of the inclination, the hole number, the hole diameter and the heat flux density. Contrast experiments showed that the equivalent heat transfer coefficient of the open thermosyphon is above 85% of that of the closed one, and its total heat transfer quantity is above 90% of that of the closed one under the same working condition, but its cost is only about 50% of that of the closed thermosyphon.

Key words: thermal engineering, open twophase thermosyphon, heat transfer characteristics, waste heat recovery