海水淡化露点蒸发传热柱中不凝气分率的变化及其对传热过程的影响

蒸汽冷凝传热中，高分率不凝气，对露点蒸发（增湿／去湿）、多效和多级闪蒸等淡化装置，以及某些工业装置的传热过程，具有很大的不良影响。本文建立了含高分率不凝气的冷凝传热实验系统（有效传热高度分别为2．5、2．0、1．6、1,3、1.0m），着重考察了在不同高度条件下，不凝气的分率变化情况及其对传热效率的影响。研究了改善含高分率不凝气传热过程的合理措施。实验表明冷凝柱高度对其传热系数有重要影响，随着柱高的增加，气侧不凝气分率提高，传热系数不断下降；较低的柱高有利于保持较高的传热系数，但需通过优化处理决定有关过程和设备参数。在实验基础上对该传热过程进行了数据模拟，模拟结果很好的证实了实验结果，也进一步深化了实验结果。

EFFECT OF COLUMN HEIGHT ON CONDENSATION WITH HIGH FRACTION NONCONDENSABLE GAS IN THE DEWVAPORATION DESALINATION PROCESS

Noncondensable gas,especially high fraction noncondensable gas,has great effect on desalination equipment in dewvaporation desalination(including humidification-dehumidification),multi-effect desalination(MED),multi-stage flash(MSF),and heat transfer process of some industrial equipment.Condensing heat transfer experimental system with high fraction noncondensable gas is set up in this work.And it is focused on the height effect investigated with various column heights of 2.5,2.0,1.6,1.3 and 1.0 m.The reasonable measure is investigated to improve the heat transfer process with high fraction noncondensable gas.The experimental result showed that the fraction of noncondensable gas increased and the heat transfer coefficient decreased with the column height increasing.The lower column height was beneficial to keep the higher heat transfer coefficient.So the parameters of process and equipment are determined through optimization treatment.The simulation results based on heat and mass balances as well as heat transfer velocity equation could verify the experimental results well.