Yu Jiaheng, Pawar Anisha, Plawsky Joel L, Chao David F
The Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA.
NASA Glenn Research Center, Cleveland, OH, 44135, USA.
NPJ Microgravity. 2022 Apr 28;8(1):12. doi: 10.1038/s41526-022-00197-5.
Bubble nucleation was investigated in a 20-mm-long, wickless heat pipe on the International Space Station. Over 20 h of running experiments using pentane as the working fluid, more than 100 nucleation events were observed. Bubble nucleation at the heater end temporarily boosted peak pressures and vapor temperatures in the device. At the moment of nucleation, the heater wall temperature significantly decreased due to increased evaporation and the original vapor bubble collapsed due to increased pressure. A thermal model was developed and using the measured temperatures and pressures, heat transfer coefficients near the heater end of the system were extracted. Peak heat transfer coefficients during the nucleation event were over a factor of three higher than at steady-state. The heat transfer coefficient data were all collapsed in the form of a single, linear correlation relating the Nusselt number to the Ohnesorge number.
在国际空间站上的一根20毫米长的无芯热管中对气泡成核进行了研究。使用戊烷作为工作流体进行了超过20小时的运行实验，观察到了100多次成核事件。加热器端的气泡成核暂时提高了装置中的峰值压力和蒸汽温度。在成核瞬间，由于蒸发增加，加热器壁温显著下降，并且由于压力增加，原始蒸汽泡坍塌。开发了一个热模型，并利用测量的温度和压力，提取了系统加热器端附近的传热系数。成核事件期间的峰值传热系数比稳态时高出三倍多。传热系数数据都以将努塞尔数与奥内佐格数相关联的单一线性相关性形式汇总在一起。
