超疏水表面黏附性对冷凝传热的影响

Effect of super-hydrophobic surface adhesion on condensation heat transfer

表面黏附性对冷凝液滴的成核、生长和脱离过程有重要影响。为进一步提高表面的冷凝传热系数,制备亲水、超疏水高黏附和超疏水低黏附3类表面,在不同蒸汽压力及风冷条件下,研究表面黏附性、压力、加热功率和冷却功率等因素对冷凝传热的影响。研究结果表明:由于超疏水高黏附表面的液滴易成核但不易脱离,而超疏水低黏附表面的液滴极易脱离,因此,在相同压力和过冷度下,超疏水低黏附表面的换热系数远大于超疏水高黏附表面的换热系数;在过冷度为4.0 K的常压条件下,超疏水低黏附和高黏附表面换热系数分别是亲水表面换热系数的4.99倍和1.77倍;在同一风冷功率和加热功率下,超疏水低黏附表面的过冷度明显小于超疏水高黏附表面的过冷度。

The adhesion of surface has an important influence on the nucleation,growth and detachment of condensed droplets.To further enhance the condensation heat transfer coefficient of surface,three types of surface,i.e.,hydrophilic surface,super-hydrophobic surface with high adhesion and super-hydrophobic surface with low adhesion,were prepared.The effects of surface adhesion,pressure,heating power and cooling power on condensation heat transfer were investigated under different steam pressures and air-cooling conditions.The results show that droplets are easy to nucleate but not easy to detach on super-hydrophobic surface with high adhesion,and are easy to detach on super-hydrophobic surface with low adhesion.Therefore,the heat transfer coefficient of super-hydrophobic surface with low adhesion is greater than that of high adhesion surface at the same pressure and sub-cooling.When sub-cooling temperature is 4.0 K at atmospheric pressure,the heat transfer coefficient of super-hydrophobic surface with low adhesion and super-hydrophobic surface with high adhesion are 4.99 times and 1.77 times that of hydrophilic surface,respectively.The sub-cooling of super-hydrophobic surface with low adhesion is significantly less than that of super-hydrophobic surface with high adhesion at the same aircooling power and heating power.