Abstract To further improve the flat-type loop heat pipe (LHP) performance, this study evaluates the practical potential of use of highly enhanced boiling structures. It is found that in our proposed new heat pipe (NHP) system, the working fluid from the evaporator outlet to the condenser inlet is in a liquid–vapor two phase flow, which is different from the classical LHP theory. A new P-T diagram is developed to better understand the thermal and hydraulic process during the NHP steady operation. In this study, by using the laser ablation technique two different types of micro- and nanoscale hybrid structures are synthesized on the boiling pool substrate. It is indicated that the formed valleys with a larger opening width play an important role in more effectively improving the bubble nucleation and bubble growth at the micrometer sites, which can subsequently lead to an increased number of active nucleation sites. The best loop performance is obtained with the micro-cone structured substrate at a heat load of 140 W, at which the maximum boiling pool heat transfer coefficient of 42.17 kW/m2·K is achieved. Compared with the polishing Cu substrate, it is enhanced by 110%. When maintaining the boiling pool temperature lower than 85 °C, the proposed new heat pipe system can tolerate a maximum heat flux of 35.12 W/cm2, which is larger than that of the most conventional LHPs with methanol as the working fluid.

中文翻译：

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应用微/纳米混合结构增强回路热管性能

摘要 为了进一步提高扁平型回路热管（LHP）的性能，本研究评估了使用高度增强沸腾结构的实际潜力。发现在我们提出的新型热管（NHP）系统中，从蒸发器出口到冷凝器入口的工作流体处于液-气两相流，这与经典的 LHP 理论不同。开发了新的 PT 图以更好地了解 NHP 稳定运行期间的热力和水力过程。在这项研究中，通过使用激光烧蚀技术，在沸腾池基底上合成了两种不同类型的微米级和纳米级混合结构。表明形成的具有较大开口宽度的谷对更有效地改善微米位点气泡的成核和气泡的生长起着重要的作用，这随后会导致活性成核位点的数量增加。微锥结构基板在140 W热负荷下获得最佳循环性能，最大沸腾池传热系数达到42.17 kW/m2·K。与抛光Cu基板相比，提高了110%。当沸腾池温度保持在 85°C 以下时，所提出的新型热管系统可承受的最大热通量为 35.12 W/cm2，这比以甲醇为工作流体的最传统 LHP 的热通量大。与抛光Cu基板相比，提高了110%。当沸腾池温度保持在 85°C 以下时，所提出的新型热管系统可承受的最大热通量为 35.12 W/cm2，这比以甲醇为工作流体的最传统 LHP 的热通量大。与抛光Cu基板相比，提高了110%。当沸腾池温度保持在 85°C 以下时，所提出的新型热管系统可承受的最大热通量为 35.12 W/cm2，这比以甲醇为工作流体的最传统 LHP 的热通量大。