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0．727／1．032mm）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45kW·每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 article the effects of vapor the condensation heat transfer characteristics concentration, vapor pressure and vapor velocity on of ethanol-water mixture vapor on external wall of vertical micro tube（inner and outer diameter were 0.727/1.032 ram） were investigated experimentally. Visual results showed that condensation modes changed with the vapor-to-surface temperature difference. When the vapor-to-surface temperature difference was larger, the condensation modes were typical dropwise condensation. The condensation modes changed to filmwise with decreasing the vapor-to-surface temperature difference. The experimental results indicated that the condensation heat transfer coefficients revealed nonlinear characteristics. The condensation heat transfer coefficient of the ethanol-water mixture was found to have a maximum value of 45 kW·m^-2·K^-1. The heat transfer coefficients increased significantly when the vapor mixture concentrations were lower, and the heat transfer coefficients increased slowly when the vapor mixture concentrations was higher. The condensation heat transfer coefficient increased with the increase of vapor pressure and vapor velocity.
参考文献
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