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本文搭建了竖直微细管外凝结传热实验台,以酒精水混合蒸气为工质,对不同酒精浓度、不同蒸气流速以及不同蒸气压力下的竖直微细管外(内外径为0 727/1.032 mm)Marangoni凝结传热特性进行了研究。可视化结果表明,凝结形态随过冷度的变化有显著变化。在大过冷度时,凝结形态为典型的珠状,随着过冷度逐渐减小,凝结形态由珠状凝结逐渐过渡到膜状凝结。实验结果显示,凝结传热曲线呈现为有峰值的非线性曲线。凝结传热系数最大值为45 kW·m~(-2)·K~(-1),约为纯水3～4倍。凝结传热系数随着过冷度的增加在蒸气浓度低时增加较快,在高浓度时,增加速率较慢。凝结传热系数随蒸气压力或蒸气流速的增加而增加。
In this paper, a vertical micro-tube external condensation heat transfer experiment bench was set up. Using alcohol-water mixed steam as working fluid, the vertical microtubules with different alcohol concentrations, different vapor velocities and different vapor pressures (inner diameter and outer diameter were 0 727 / 1.032 mm) Marangoni condensation heat transfer characteristics were studied. Visualization results show that the condensation morphology changes significantly with the variation of undercooling. When the degree of supercooling is too high, the coagulation morphology is a typical bead. As the supercooling degree gradually decreases, the coagulation morphology gradually changes from bead to film. Experimental results show that the condensation heat transfer curve presents a non-linear curve with a peak. The maximum value of condensation heat transfer coefficient is 45 kW · m ~ (-2) · K ~ (-1), about 3 ~ 4 times of pure water. Condensation heat transfer coefficient increases rapidly with low supercritical temperature and low supercritical water with low supercritical fluid. Condensation heat transfer coefficient increases with vapor pressure or vapor flow rate.