Heat Transport Characteristics and Operating Limit Expansion of Oscillating Heat Pipe

对于在空间环境中使用振荡热管（OHP），除了高性能之外，它们在宽范围的条件、温度和热输入下工作是非常重要的。在本研究中，将芯插入OHP（I.D.=φ 1.5mm），以扩大这一范围的条件。邪恶的OHP工作在一个较高的输入功率范围内，没有灯芯的OHP不工作。但在中等温度范围内，邪恶的OHP的有效导热系数变得低于正常的OHP。如果芯以对称的配置插入，则不会发生循环流动，并且OHP不能很好地工作。虽然正常的OHP为2mm I.D.结果表明，在垂直加热工况下，无芯OHP的性能较好;在水平加热工况下，以乙醇为工质，在整个OHP长度的一半处有芯OHP的性能较好。通过将绝热段长度从270 mm延长到1000 mm来研究有无毛细作用的OHP性能。在水平操作中，毛细作用的OHP工作良好，并且在绝热段长度为270 mm或500 mm时表现出良好的性能。此外，为了满足空间应用的需要，还对低温区氨工质的OHP进行了研究。在垂直操作中，无芯的氨OHP显示出比乙醇OHP更高的性能。在水平操作中，毛细氨OHP工作良好，但在较高的热输入功率的情况下不稳定。

For use of oscillating heat pipes (OHPs) in a space environment, in addition to a high performance, it is very important that they work in a wide range of conditions, temperature and heat input. In this research, wick was inserted to the OHP (I.D.=φ1.5mm) to expand this range of conditions. The wicked OHP worked well at a range of higher input power, where a OHP without wick didn't work. But at a middle range, the wicked OHP's effective thermal conductivity became lower than that of the normal OHP. If wicks were inserted in a symmetrical configuration, circulating flow didn't occur and OHP didn't worked well. Although a normal OHP of 2mm I.D. didn't work, the wicked OHP worked well and showed a good performance.The OHP showed a better performance both without a wick in a vertical-bottom-heating operation, and with a wick at half-length of overall OHP in a horizontal operation using ethanol as the working fluid. The OHP performance with or without wick was investigated by extending the adiabatic section length from 270 to 1000 mm. In a horizontal operation, the wicked OHP worked well and showed a good performance with the adiabatic section 270 or 500 mm in length. Furthermore, for practical space use, the OHP using ammonia as the working fluid was investigated in the lower temperature region. The ammonia OHP without a wick showed higher performance than the ethanol OHP in a vertical operation. In a horizontal operation, the wicked ammonia OHP worked well, but unstably in the case of higher thermal input power.