波纹内翅片管外水的冻结特性实验研究

Experimental study on characteristics of water icing outside tube with wave-like internal fins

通过测量管内低温气体、管壁温度分布及冰层图相,分析了波纹内翅片管管内传热热阻、管壁温度和冰层增长的变化特性。结果表明:内翅片管管内传热阻仅为光管的6.65%,由管壁至管内低温气体的热流量大大增加,因此,管外冰层增长速度在距入口250 mm和500 mm处分别约为光管的4.2倍和1.7倍。冰层热阻占整个耦合传热总热阻的比例更大,以至于管外冰层热阻的增加引起管壁和管内气体温度的降低。由于内翅片管管内低温气体沿轴向温升更大,使其冰层厚度沿轴向斜率远大于光管。

Time-wise variation of thermal resistance, wall temperature and ice-layer increasing of wave-like internal finned tube were analyzed through measuring internal cryogenic gas temperature, tube wall temperature, and ice profiles outside tube. The comparison with smooth tube shows that the internal convective thermal resistance of finned tube is only 6.65 % of that of smooth tube and the heat transfer flux from tube wall to internal cryogenic gas is augmented greatly due to heat transfer enhancement by internal fins. Thus, ice layer outside tube grows about 4.2 and 1.7 times as much as outside smooth tube at axial position of 250 mm and 500 mm. The corresponding icelayer thermal resistance accounts for such a high proportion in that of overall conjugate heat transfer that the temperature of tube wall and internal cryogenic gas decreases due to the increase of ice layer. The axial rise of internal cryogenic gas temperature is enormous for internally finned tube so the slope of ice thickness in the axial direction is much higher than that of smooth tube.