Abstract: The gravity heat pipe with small diameter in the startup process was investigated experimentally by analyzing the influences of heat input，inclination angle，cooling water flow rate on the startup properties.The tested gravity heat pipe was fabricated with copper tube and charged with distilled water.The heat pipe has the outer diameter of 8 mm with the thickness of 1mm，and total length of 1500 mm.The results show that with increasing heat inputs，the startup time decreases and the time to reach a steady effective thermal conductivity is shortened.The startup properties at inclination angle of 60° are superior to those at 30° and 90°.The startup temperature difference and startup time at 90° obtain the maximum values.When the cooling water flow rate is 10L·h^-1，the startup temperature difference and startup time both present the maximum value，and the effective thermal conductivity demonstrates the shortest time to reach the steady state.The relations of the startup temperature difference and startup time at other cooling water flow rates are all satisfied with the sequence of 10L·h-¹ ＞ 40L·h^-1＞ 20L·h^-1＞ 30L·h^-1.

Key words: gravity heat pipe, start up behavior, transmission characteristic, effective thermal conductivity

摘要： 实验研究了小管径重力热管启动过程特性，分析了加热功率、倾角、冷却水流量对热管启动特性的影响。实验用热管为铜水重力热管，外径8 mm，壁厚1 mm，总长1500 mm。结果表明，随加热功率增大，热管启动时间缩短，当量热导率到达稳定的时间缩短。在倾角为60°时热管启动特性要优于在30°和90°时的情况，90°时启动温差最大、启动时间最长。冷却水流量在10 L·h^-1时，热管启动温差最大，启动时间最长，当量热导率稳定得最慢，而在其他流量下时，热管的启动温差和启动时间大小关系均为10 L·h^-1＞40 L·h^-1＞20 L·^h-1＞30 L·h^-1。

关键词: 重力热管, 启动特性, 传输因素, 当量热导率