重力热管壁温与传热特性的实验分析

使用FC-72、乙醇和水作为工质,根据热管各部分的温度变化,研究重力热管的启动、壁温波动和传热性能,分析工质对重力热管壁温和传热特性的综合影响.实验结果表明:重力热管在启动和运行过程中的壁温波动与内部工质和加热功率等因素相关,使用FC-72作为工质时,重力热管可在加热功率Q=10 W时平稳启动,以乙醇为工质时虽在启动中有温度波动但当加热功率升高时波动消失,而充有水的重力热管在小功率启动时温度波动较大,且存在温度波动的功率范围较广.所以FC-72或乙醇为工质时热管壁温稳定性较好;而以水作为工质时热管整体传热性能较好,冷凝热阻较小.同时蒸发段的轴向温度均匀性受工质类型和加热功率影响,在加热功率较小时,以FC-72为工质的热管蒸发段轴向均温性较差.

Experimental analysis of wall temperature and heat transfer characteristics of gravity heat pipe

In the experiment, FC-72, ethanol and water were used as working fluid. According to the temperature change of the heat pipe, the startup, wall temperature fluctuation and heat transfer performance of the gravity heat pipe were studied, the effect of the working fluid to the wall temperature and heat transfer characteristics of the gravity heat pipe were analyzed. The experimental results show that the wall temperature fluctuations of the gravity heat pipe during startup and operation are related to factors such as working fluid and heating power. When FC-72 is used as the working fluid, the gravity heat pipe can start smoothly at Q=10 W. Although there are temperature fluctuations during startup when ethanol is used as the working fluid, the fluctuation disappears when the heating power increased. However the gravity heat pipe has a large temperature fluctuation when filled with water at low heating power, and the power range is wider which exists the temperature fluctuations. Therefore, the gravity heat pipe wall temperature is stability when FC-72 and ethanol are used as working fluids. When water is used as the working fluid, the overall heat transfer performance of the heat pipe is better. and the condensation heat resistance is lower, the temperature difference of the evaporator and the condenser is small. At the same time, the axial temperature uniformity of the evaporation section is affected by the working fluid and heating power. The axial temperature is not uniform of the heat pipe evaporation section when use FC-72 as the working fluid at small heating power.