A cryogenic loop heat pipe (CLHP) is an effective means of temperature control at low temperatures, but the physical properties of cryogenic working fluids are quite different from those of room-temperature working fluids, and their phase change and heat transfer characteristics need to be further studied. In this paper, a test system for evaluating the loop heat pipe (LHP) heat transfer performance and visualizing the condensation phenomenon in the condenser was fabricated. The performance of a propylene LHP with 20 W of heat exchange was tested as the condenser temperature was varied from 283 to 153 K, and the flow patterns and heat transfer characteristics during condensation were obtained. With the decreasing condenser temperature, slug flow disappeared, and pseudo-slug flow occurred and transitioned into wavy-annular flow, which was mainly caused by the increase of density ratio and viscosity ratio of the liquid to vapor. These change of flow pattern further affected the two-phase heat transfer and the performance of the CLHP. Pseudo-slug flow was observed at a condenser temperature of 273 to 203 K and it had a notable influence on the condensation pressure drop. The heat transfer coefficient of the two-phase region ranged from 2500 to 5500 W/m²K. When the condenser temperature ranged from 203 to 173 K, the transition of flow pattern and the fluctuation in the system caused a large deviation between the obtained and predicted heat transfer coefficients, and at other condenser temperatures, the obtained values were consistent with the predicted values for the corresponding flow patterns.

低温回路热管（CLHP）是在低温下进行温度控制的有效手段，但是低温工作流体的物理特性与室温工作流体的物理特性完全不同，因此它们的相变和传热特性需要保持一致。进一步研究。在本文中，制造了一个用于评估回路热管（LHP）传热性能并可视化冷凝器中冷凝现象的测试系统。当冷凝器温度从283 K改变到153 K时，测试了具有20 W热交换的丙烯LHP的性能，并获得了冷凝过程中的流动模式和传热特性。随着冷凝器温度的降低，团状流消失，出现了假团状流，并转变为波状环状流；这主要是由于液体与蒸气的密度比和粘度比增加所致。流动模式的这些变化进一步影响了两相传热和CLHP的性能。在冷凝器温度为273至203 K时观察到伪团流，它对冷凝压降有显着影响。两相区域的传热系数为2500至5500 W / m² K.当冷凝器温度范围为203至173 K，流动模式和过渡在系统中的波动引起所得的和预测的热传递系数之间的大的偏差，并且在其它的冷凝器温度，所获得的值分别具有一致的相应流型的预测值。