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采用含氟丙烯酸疏水树脂在套管换热器的水蒸气冷凝表面上构建疏水冷凝表面,研究冷热流体流量、换热器放置方式、涂膜厚度等对换热器传热系数的影响。研究表明,当其他条件不变,换热器水平放置时,热流体加热温度由125℃增加到175℃,传热系数由10409.9W·m-2·K-1增加到38353.2W·m-2·K-1;冷流体流量由5mL/s增加到35mL/s,传热系数由38000.2W·m-2·K-1增加到52195.9W·m-2·K-1。无论是垂直还是水平放置时,疏水涂膜的厚度对传热系数影响均不大。含氟丙烯酸疏水树脂能降低换热管壁的表面自由能,增大冷凝水的接触角使液滴更易滑落,水蒸汽冷凝由膜状冷凝转变为滴状冷凝,从而减小了液膜热阻,强化了传热过程,滴状冷凝维持时间超过1000h。
The hydrophobic condensation surface was constructed on the condensation surface of water vapor of the casing heat exchanger by using fluorine-containing acrylic hydrophobic resin. The influences of flow rate of hot and cold fluid, placement of heat exchanger and film thickness on the heat transfer coefficient of heat exchanger were studied. The results show that the heat transfer temperature increases from 125 ℃ to 175 ℃ and the heat transfer coefficient increases from 10409.9W · m-2 · K-1 to 38353.2W · m-2 · K-1. The flow rate of cold fluid increased from 5mL / s to 35mL / s and the heat transfer coefficient increased from 38000.2W · m-2 · K-1 to 52195.9W · m-2 · K-1. Whether it is vertical or horizontal, the thickness of the hydrophobic coating has little effect on the heat transfer coefficient. The fluorine-containing acrylic hydrophobic resin can reduce the surface free energy of the heat exchange tube wall, increase the contact angle of the condensed water to make the liquid drop more easily, and the condensation of the water vapor changes from film-like condensation to drop-like condensation, thereby reducing the thermal resistance of the liquid film , Strengthen the heat transfer process, drop-shaped condensate to maintain time more than 1000h.