分离式热管蒸发段传热特性试验研究

Heat Transfer Characteristics of Evaporator Section for Separate-Type Heat Pipe

通过对分离式热管水平及小倾角 ( 0°～ 5°)蒸发段传热特性的大比例尺模型的试验研究 ,获得了其壁温特性及换热规律 ,探讨了热流密度、工作温度、倾角及充液率等因素对传热特性的影响 .结果表明 ,与蒸发段垂直布置的分离式热管相比 ,水平及小倾角热管的换热系数较小 .特别是当热流密度大于 2 0kW /m2 时 ,蒸发管上下管壁温差增大 ,沿管长方向上管壁温度的波动较大 ,使上壁的换热系数降低 ,局部烧干热负荷过早出现 ,使热管的工作范围减小 .此外 ,还得出了水平蒸发管平均换热系数的无量纲准则关系式 .

Using a large scale model, an experiment is conducted to obtain the heat transfer characteristics of the horizontal evaporator section. The same is carried out for evaporator section with small inclination angles of a separate type heat pipe. The wall temperature distribution and heat transfer characteristics are obtained. Studied are the effects of heat flux, working temperature, inclination angle, and quantity of actuating medium on heat transfer. The worse heat transfer is obtained in comparison with the vertical evaporator where the top and bottom wall temperature difference increased when the value of heat flux exceeds 20 kilowatts per square meter. The top wall temperature has a large fluctuation along the axes of the evaporator tubes, resulting in a reduction of heat transfer coefficient at the top wall and making the dry out heat flux occur earlier, such that the work area of heat pipe is limited. In addition, an empirical dimentionless correlation is developed for the heat transfer coefficient of horizontal evaporator section.