新型内嵌式热管流型演化与传热特性实验研究

Investigation on the Flow Pattern Evolution and Heat Transfer Characteristics of an Embedded Heat Pipe

本文面向电蓄热采暖应用设计了一种新型内嵌式热管,通过可视化和传热实验研究了充液率在5%至70%之间变化时热管内部的流型演化规律和传热特性。根据流型演化过程可以将充液率分为小、中、大三个类别。小充液率时,热管内部出现间歇剧烈沸腾过程;中等充液率时,热管内部出现持续沸腾现象,冷凝段受到搅混流的周期性冲刷;大充液率时,气液混合工质在绝热段往复振荡,冷凝段始终存在液态工质。对于充液高度小于加热段高度和充液高度大于加热段高度两种情况,随着充液率的增大,热阻均先降低后升高,但充液高度大于加热段高度时的热阻普遍大于充液高度小于加热段高度时的热阻。10%充液率时热阻最小,80 W加热功率时约为0.017℃/W,此时蒸发段为持续薄液膜蒸发传热,冷凝段为周期性扰动冷凝和强制对流耦合传热。

A novel embedded heat pipe is designed for the application of electric heat storage and heating. The evolution law of flow pattern and heat transfer characteristic when the liquid filling ratio(FR) changes from 5% to 70% are investigated through experiments. It is found that the FR can be divided into three categories: small, medium and large. When the FR is small, the intermittent violent boiling process occurs. At medium FR, continuous boiling occurs, and the condensation section is periodically scoured by the stirred flow. When the FR is high, the gas-liquid mixed fluid oscillates back and forth in the adiabatic section, and there is always liquid in the condensation section. When the filling height is less than the heating height and the filling height is larger than the heating height, the thermal resistance both decreases first and then increases with the increase of FR, but the thermal resistance when the filling height is greater than the heating height is generally larger than that when the filling height is less than the heating height. The minimum thermal resistance about 0.017℃/W occurs at 10% FR and 80 W. In this case, continuous thin liquid film evaporation occurs at the evaporation section, while the periodic disturbance condensation and forced convection coupled heat transfer occurs at the condensation section.