Abstract: The heat pipe has important application value in industrial residualheat utilization and some other special industries. Thus, the research on heat transfer performance optimization and comprehensive design is of great significance. The three factors influencing on the heat transfer performance of gravity assisted heat pipe, which include the fin in pipe outside, the pipe shell diameter and the working fluid filling ratio, were analyzed. The relation between the fluid filling ration and the input heatflow density, which can cause the heat pipe to fail, was found by experiment. Based on the experimental data, the influences of the heatflow density on the vaporliquid distribution inside the heat pipes with different fluid filling ratio were analyzed emphatically.

Key words: gravity assisted heat pipe, heat transfer performance, fluid filling ratio, vapor-liquid distribution