Department of Mechanical Engineering, Hanyang University, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan, Gyeonggi-do 15588, Republic of Korea.
Department of Mechanical Design Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea.
Water Res. 2018 Apr 1;132:23-33. doi: 10.1016/j.watres.2017.12.066. Epub 2017 Dec 27.
In this study, a detailed rigorous theoretical model was developed to predict the transmembrane flux of a shell-and-tube type vacuum membrane distillation (VMD) module for seawater desalination. Two modes of operation are used for performing the VMD, namely lumen-side feed (in-out) configuration and shell-side feed (out-in) configuration. In this study, detailed mathematical formulations are derived for an out-in configuration that is commonly used in seawater desalination applications. Experimental results and model predictions for mean permeate flux are compared and shown to be in good agreement. The results indicate that although the simple VMD model that maintains a constant permeate pressure is easy to use, it is likely to significantly overestimate the mean permeate flux when compared to the detailed model that considers the pressure build-up in the fiber lumen. The pressure build-up of water vapor in the fiber lumen is identified as the crucial factor that significantly affects the VMD performance because it directly reduces the driving force for vapor permeation through the membrane pores. Additionally, its effect is more pronounced at longer fiber lengths and higher permeate fluxes, and this is achieved at higher feed temperatures and velocities and at lower feed salinities. In conclusion, the results of the study are extremely important in module design for the practical applications of VMD processes.
在这项研究中，开发了一个详细而严格的理论模型，用于预测用于海水淡化的壳管式真空膜蒸馏（VMD）模块的跨膜通量。VMD 采用两种操作模式，即内腔进料（进出）配置和外壳侧进料（出进）配置。在这项研究中，针对常用于海水淡化应用的出进配置推导出了详细的数学公式。比较了平均渗透通量的实验结果和模型预测，结果表明，尽管保持恒定渗透压力的简单 VMD 模型易于使用，但与考虑纤维内腔中压力升高的详细模型相比，它可能会显著高估平均渗透通量。纤维内腔中水蒸气的压力升高被确定为显着影响 VMD 性能的关键因素，因为它直接降低了通过膜孔的蒸汽渗透的驱动力。此外，在较长的纤维长度和较高的渗透通量下，其效果更为明显，这是在较高的进料温度和速度以及较低的进料盐度下实现的。总之，研究结果对于 VMD 过程的实际应用中的模块设计极为重要。
