板式单环路脉动热管的流动和传热特性

以制冷剂R245fa为工质对常规以及带连通通道的板式单环路脉动热管流动特性进行了可视化研究,并对传热性能进行了测试,考察了充液率和加热功率的影响规律。结果表明:对于常规环路,充液率一定时,随加热功率增加,工作方式依次经历振荡流、有方向改变的循环流、定向循环流,且充液率越高,出现定向循环的加热功率越低;连通通道提供了流动的额外通路,工作方式更具振荡特性,定向循环在高充液率、高功率下才能出现。在合适的充液率下,连通通道不但能降低热阻,而且能提高传热极限。

Experimental investigation of flow visualization and thermal performance of flat-plate single-loop pulsating heat pipes

The experimental study was conducted to visualize the two-phase flow and test the thermal performance of a single-loop flat plate pulsating heat pipe using R245fa as working fluid.The comparison was made between normal loop and an improved loop with interconnecting channel (IC) between the two vertical parallel channels.It was found that for the normal loop,for a fixed filling ratio,with the increasing of heating power,the two-phase flow experiences oscillation,circulation with alternative change of direction,and circulation with fixed direction.The incorporation of IC provides an additional short-cut for fluid flow and prolongs the oscillation regime,with the fixed direction circulation only occurring at high filling ratio and high working load.With an appropriate filling ratio,IC not only can decrease thermal resistance but also can delay the deterioration of heat transfer.