Abstract:

The evaporator is one of the common heat exchangers, which is widely used in chemical industry and food industry etc. The traditional evaporator with metal tubes is extremely limited in utilization for some reasons that the metal tubes are apt to be corroded by acid or alkali and the serious surface scaling. These problems could be well settled by using excellent performance polymer hollow fibers and good application foreground could be in foresight. In this study, the self-made polymer hollow fibers were used to manipulate the non-metal evaporator and the related evaporation experiments were carried out. The results showed that the performance of the hollow fiber evaporator relied on the thermal conditions of the feed solution. The heat transfer coefficient, the water production and the heat efficiency were better when feed with boiling solution than with low temperature solutions. The heat transfer resistances of fiber walls and the shell side were the main heat transfer resistance. The percentage of the heat transfer resistance with fiber walls can be more than 66% when feed with boiling solution. However, the percentage of heat transfer resistance in the lumen side was as low as 15.3%, and can be lower than 5% when the solution velocity increased. The heat transfer coefficient, the heat efficiency and the water production decreased dramatically when the feed temperature became lower. The results in this study can serve data support for the design and operating parameters optimization of the polymer hollow fiber evaporators, and can promote the further researches and applications of polymer hollow fiber evaporators.

Key words: hollow fiber evaporator, heat transfer, heat conduction, heat efficiency, evaporation

摘要：

蒸发器广泛应用于化工、食品等行业，传统的金属管蒸发器由于其耐酸碱腐蚀性差、表面易结垢等弱点，一定程度上限制了其应用范围，而具有优良性能的高分子中空纤维管可有效解决这些问题，具有很好的应用前景。采用自制的高分子改性中空纤维管，制备出非金属换热器，并进行了蒸发传热实验。结果表明，高分子中空纤维蒸发器的性能与料液温度有密切关系，沸腾进料时蒸发器的传热系数、产水量和热量利用率均高于低温进料；传热热阻主要集中在管外蒸汽加热侧和管壁的导热性能，当沸腾进料时管壁热阻占总传热热阻的66%以上，而管内蒸发侧传热热阻所占比重较低，均低于15.3%，且随着料液流速的增大而降低到5%以下；随着料液温度的降低，蒸发过程的传热系数、能量利用效率以及产水量均显著下降。

关键词: 中空纤维蒸发器, 传热, 热传导, 能量利用率, 蒸发