Experiment for Drop-wise Condensation Heat Transfer by Infrared Thermal Imager
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摘要: 通过非接触式测温装置红外热像仪，观测冷凝液滴的形成、生长以及液滴之间汇聚、滚落过程.实验发现在珠状冷凝过程中，其表面温度变化显著.随着冷凝过程的进行，小液滴逐渐汇聚成大液滴，其液滴单位面积换热量明显下降，液滴表面温度逐渐降低.微纳米级小液滴在珠状冷凝换热中具有至关重要的作用.液滴在洁净表面上的珠状凝结和液滴在汇合后自清理表面上的珠状凝结表现出不同的温度分布，即珠状凝结汇聚后的自清理表面一直被前驱膜所覆盖.Abstract: T-type thermocouples and an IR (Infrared) thermal imager are used to observe the generation, growth, coalescence and roll off from the cooling surface of the droplets. Results have been found that the surface temperature varies sharply during the drop-wise condensation, which is not the same to the literature assumption of keeping constant at saturate temperature. The temperature of droplets surface increases sharply and decreases gradually during condensation, though the condensation surface keeps at constant temperature. Through analysis, studies have been presented that the small diameter droplets are critical to the whole condensation heat transfer. The diameter of the droplet has been obtained during drop-wise condensation. The surface temperature after the droplets coalescence is different from that at the beginning without condensation and it is found that the surface is covered by precursor film after coalescence.
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