This work presents a systematic method for analysis and optimization of specific energy production (SEP) of pressure retarded osmosis (PRO) systems employing single-stage configuration as well as multistage design with interstage hydro-turbines. It is shown that the SEP normalized by the draw solution feed osmotic pressure increases with the number of stages as well as a dimensionless parameter . As compared to the single-stage PRO, the multistage arrangement not only increases flux and volume gain, but also allows a stage-dependent, progressively decreasing hydraulic pressure, both of which contribute to enhanced SEP and power density. At the thermodynamic limit where γ_tot goes to infinity, the theoretical maximum SEP by an N-stage PRO system is , where q_tot is the ratio of the draw solution flow rate at the outlet to the inlet on the system level. For single-stage PRO, it is no more than π₀. For infinite number of stages, the theoretical limit becomes . SEP under realistic conditions and practical constraints on multistage design are discussed. © 2017 American Institute of Chemical Engineers AIChE J, 2017

中文翻译：

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系统分析和优化压差渗透发电：多级设计的效果

这项工作提出了一种系统的方法，用于分析和优化采用单级配置以及带级间水轮机的多级设计的压力延迟渗透（PRO）系统的比能量产生（SEP）。结果表明，抽提溶液进料渗透压归一化的SEP随级数和无因次参数的增加而增加 。与单级PRO相比，多级装置不仅增加了通量和体积增益，而且还允许依赖于各个阶段的液压压力逐渐降低，这两者都有助于提高SEP和功率密度。在_γtot达到无穷大的热力学极限下，N级PRO系统的理论最大SEP为 ，其中q _tot是系统级别上出口处与入口处的汲取溶液流速之比。对于单级PRO，它不大于π ₀。对于无限多个阶段，理论极限变为 。讨论了在实际条件下和对多级设计的实际约束下的SEP。©2017美国化学工程师学会AIChE J，2017