真空膜蒸馏NaCl水溶液脱盐过程模拟研究

在尘气模型的基础上建立了真空膜蒸馏NaCl水溶液过程的传质传热机理模型,并用膜孔径分布函数代替膜平均孔径值,首次实现了孔径分布与膜蒸馏机理模型的有效结合.与平均孔径模型相比,随温度变化的通量模拟结果与实验数据吻合良好,证明了所建模型的实用性.在此基础上,探讨了操作条件和孔径分布函数的主要参数对蒸馏过程的影响.模拟结果表明,通量随进料温度和流量的增加而增大,随料液中NaCl浓度的增大而减小;膜的平均孔径越大,通量越大;在平均孔径相同的情况下,膜孔分布越密集,通量越小.

Research on simulation of desalination of NaCl aqueous solution by vacuum membrane distillation

A heat and mass transfer model for vacuum membrane distillation of NaCl aqueous solution was established based on the dusty gas model. The average membrane pore size in the model was replaced by an experimentally fitted relationship of pore size distribution, and an effective combination of a consecutive pore size distribution with the membrane distillation model was achieved for the first time. Comparison of flux variation with temperature between experimental data and simulative results shows that prediction of the established model has a better agreement than that of the average pore size model. The effects of operating conditions and distribution function parameters on the distillation are discussed. Results show that the flux increases respectively with the increase in feed temperature and flowrate, and decreases with the increase in NaCl concentration. Under the operating conditions tested, the bigger the average pore size is, the bigger the flux is. While for the same average pore size, the narrower the pore size distribution is, the smaller the flux is.