Abstract: In this paper, a multi-scale model combining the local transmembrane osmosis model and the mass transfer in flow channels in a full-scale pressure retarded osmosis(PRO) membrane module was set up to determine the performance of PRO in a full-scale operation(i.e., power density and specific energy) by calculating the parameter distributions along feed and draw channels. This work focused on the effects of porosities, heights and numbers of layer of both feed and draw spacers on the performance of PRO. According to the numerical simulations, higher porosities of feed and draw spacer can achieve higher power densities but lower specific energy. Smaller height of feed spacer and larger height of draw spacer result in higher power densities while the specific energy increases as the heights of feed spacer and draw spacer decrease. Multilayer spacers were found to have adverse effects on the performance. Our findings give insight into designing membrane modules. Feed spacers should have relatively small porosity and small height while draw spacers can have relatively larger porosity and large height, and for both feed and draw spacers, monolayer spacers are recommended.

Key words: spacer, pressure retarded osmosis, multi-scale model, numerical simulation, optimization

摘要： 建立了一个将局部跨膜渗透过程和全尺寸通道内流动过程相结合的多尺度理论模型，通过计算各物理参数沿膜组件的分布来确定全尺寸应用下压力延迟渗透过程的工作性能。通过数值计算，重点研究了隔网的孔隙率、厚度以及层数对全尺寸应用下压力延迟渗透过程性能的影响，发现提高原料液和提取液隔网的孔隙率可以提高压力延迟渗透过程的功率密度，但是同时会降低该过程的比能。降低原料液隔网的厚度和提高提取液隔网的厚度可以提高该过程的功率密度，而原料液和提取液隔网厚度的降低均可以提高该过程的比能。多层隔网会对压力延迟渗透过程的能量密度和比能均产生负面影响。本文研究结果可以为膜组件的设计提供参考：原料液隔网应当具有相对较小的孔隙率和厚度，而提取液隔网应当具有相对较大的孔隙率和厚度，尽量不要使用多层隔网。

关键词: 隔网, 压力延迟渗透过程, 多尺度模型, 数值模拟, 优化