过冷池沸腾落塔短时微重力实验研究

EXPERIMENTAL STUDY ON SUBCOOLED POOL BOILING IN MICROGRAVITY UTILIZING THE DROP TOWER BEIJING (NMLC)

本文研制了一套控温池沸腾实验设备,利用中国科学院国家微重力实验室落塔开展了短时微重力环境下的过冷池沸腾传热实验研究。加热元件为长30 mm、直径60μm的铂丝。实验工质为0．1 MPa压力下过冷度为24℃的R113。在地面常重力和落塔短时微重力实验中,观测到核态沸腾和双模态过渡沸腾现象。对核态沸腾,微重力传热效果稍有增强而汽泡形态却呈现出剧烈变化。对双模态过渡沸腾,微重力下膜态沸腾部分有明显收缩,但热流密度值仍比常重力时减小20％。

A temperature-controlled pool boiling device was developed to perform pool boiling heat transfer studies in microgravity utilizing the Drop Tower Beijing （NMLC）. A platinum wire of 60 μm in diameter and 30 mm in length was simultaneously used as heater and thermometer. The fluid was R113 at 0.1 MPa and subcooled by 24℃ nominally for all cases. Nucleate and two-mode transition boiling were observed during the experiments in both normal gravity and microgravity. For nucleate boiling, the heat transfer was slightly enhanced, while the bubble pattern is dramatically altered by the variation of the acceleration. For two-mode transition boiling, about 20% decrease of the heat flux was obtained, although the part of film boiling was receded in microgravity.