A Computational Framework for Design and Optimization of Dynamic Membrane Processes

动态膜过程设计和优化的计算框架

基本信息

批准号：
2140946
负责人：
Mingheng Li
金额：
$ 30万
依托单位：
Cal Poly Pomona Foundation, Inc.
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2022
资助国家：
美国
起止时间：
2022-06-01 至 2025-05-31
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2140946&HistoricalAwards=false
关键词：
Computational Framework Design Optimization Dynamic

项目摘要

It is estimated that over half of the world’s population is affected by fresh-water scarcity and that this figure will continue to rise because of the Earth’s changing climate, unbalanced socio-economic development, and continued population growth. The same can be said for the geographic imbalances of energy availability, which are driven by parallel factors. Desalination offers a viable solution to clean-water production from seawater and brackish groundwater. Among desalination techniques, reverse osmosis (RO) membrane separators are the most widely used due to their energy efficiency relative to those based on distillation. However, even advanced multistage RO processes suffer from inefficiencies and inherent operational challenges including membrane fouling and scaling, transient operation due to the need for periodic flushing of the membrane, the computational challenges posed in model-based optimization of RO networks, and the need for high water recovery levels in inland areas where costs are associated with disposal of brine waste. This research program will advance the fundamental understanding of dynamic (batch, semi-batch, and cyclic modes) membrane-based separation processes and will optimize their design and performance during dynamic operation. Specifically, this proposal aims to (i) investigate salt retention, fouling, scaling, and concentration polarization (a measure of solute concentration gradient at the membrane surface) under transient conditions and internal separator geometry design using computational fluid dynamics (CFD), (ii) explore system dynamics and apply optimal control theory to enhance system performance, (iii) develop novel networked process designs, and (iv) validate results using pilot-scale data from local water districts. These objectives will ultimately lead to transformative innovations in dynamic membrane processes to help address the pressing issues in water and energy availability. The project also will provide research opportunities to a diverse group of undergraduate and high school students. Educational modules on advanced RO system design and operation will be developed to benefit students, researchers, and industrial practitioners in the field.This proposal presents a vision for developing dynamic reverse osmosis (RO) processes to overcome the practical limitation of the infinite number of membrane stages and inter-stage booster pumps that would be required for (theoretically) optimal desalination system performance under steady operation, the current nominal mode of operation. The challenge to be addressed is the concurrent optimal design of the multistage networked membrane separator system together with determining the optimal time-periodic mode of operating the entire system. Dynamic 3-dimensional computational fluid dynamic (CFD) techniques are required for accurate RO module simulations – however, using these types of simulations in the task of RO network design and optimization is computationally intractable at this time. Therefore, a reduced-order 1-dimensional model with parameters fitted from the detailed CFD simulations and validated against actual desalination plant data will be developed. This reduced model can be efficiently discretized by orthogonal collocation and subsequently will be used to define a rigorous optimal control problem that seeks to minimize energy use and maximize clean water recovery. This research program will leverage current knowledge on the design of pressure-swing adsorption (PSA) processes, a mature industrial technology for gas separations, to guide initial designs for the networked RO desalination systems. Like the planned RO systems, PSA plants operate under transient conditions and feature spatial concentration gradients within the separation units. The dynamic modeling, optimization, and design tools for RO networks inspired by PSA systems will be extended to green power generation systems that effectively operate as RO in reverse: osmotic pressure generated by the permeation of water through a membrane to a saline solution increases the latter’s pressure and volumetric flowrate which is subsequently harvested for power. Overall, this research program will fundamentally advance the set of systems engineering tools available for producing reduced-order simulations from detailed, spatiotemporally distributed transport models needed for the model-based design and optimization of transient chemical processes outside of RO systems. Coupled with this research plan, a range of education and outreach plans focusing on undergraduate researcher support and a unique student exchange program with UCLA is planned.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

据估计，世界以上人口的一半以上受到淡水稀缺的影响，由于地球气候变化，社会经济发展不平衡以及持续的人口增长，这一数字将继续上升。对于能源可用性的地理不平衡，这是同样的，这是由平行因素驱动的。淡化提供了一种可行的解决方案，可从海水和咸水地下水中清洁水生产。在海水淡化技术中，反渗透（RO）膜分离器是最广泛使用的，因为它们的能效相对于基于蒸馏的能量效率。然而，即使是高级多阶段RO工艺，由于需要定期冲洗膜，在基于模型的RO网络优化以及对内陆地区的高水位恢复水平的需求中所带来的计算挑战所带来的计算挑战，即使需要定期冲洗膜，在内陆地区需要与膜相关的高度恢复水平，因此，由于需要定期冲洗膜而引起的瞬态操作，瞬时运行，即使是瞬时操作，即使是高级的多阶段RO工艺，也遭受了运营的操作挑战。该研究计划将提高对基于膜的分离过程的动态（批处理，半批量和环状模式）的基本理解，并将在动态操作过程中优化其设计和性能。 Specifically, this proposal aims to (i) investigate salt retention, fouling, scaling, and concentration polarization (a measure of solid concentration gradient at the membrane surface) under transient conditions and internal separator geometry design using computational fluid dynamics (CFD), (ii) explore system dynamics and apply optimal control theory to enhance system performance, (iii) develop novel networked process designs, and (iv) validate results using pilot-scale data from当地水区。这些目标最终将导致动态膜过程中的变革性创新，以帮助解决水和能源可用性的紧迫问题。该项目还将为科学家的本科生和高中生提供研究机会。将开发有关高级RO系统设计和操作的教育模块，以使该领域的学生，研究人员和工业实践者受益。该提案提出了开发动态反向渗透（RO）过程的愿景，以克服无限数量的膜阶段和阶段促进泵的实际限制，该阶段和阶段间助力泵（（theorical Inture）在（theoratient temental Inture）中的运作稳定运作中所需的运作稳定运作。要解决的挑战是多阶段网络膜分离器系统的同时最佳设计，以及确定操作整个系统的最佳时间周期模式。精确的RO模块模拟需要动态3维计算流体动力学（CFD）技术 - 但是，在RO网络设计和优化任务中使用这些类型的仿真在此时在计算上是可棘手的。因此，将开发出具有详细CFD模拟和针对实际目的地工厂数据验证的参数的缩小阶数1维模型。该简化的模型可以通过正交搭配有效地离散，随后将用于定义严格的最佳控制问题，该问题旨在最大程度地减少能源使用并最大程度地提高清洁水的回收率。该研究计划将利用当前有关压力式压力吸附设计（PSA）流程的知识，这是一种用于气体分离的成熟工业技术，用于指导网络RO脱盐系统的初始设计。像计划的RO系统一样，PSA植物在瞬态条件下运行，并具有分离单元内的空间浓度梯度。受PSA系统启发的RO网络的动态建模，优化和设计工具将扩展到有效地作为RO的绿色发电系统，这些系统有效地作为RO相反：通过膜通过膜渗透到盐水溶液中产生的渗透压会增加后来的压力和体积流量，并随后收获发电。总体而言，该研究计划将从根本上推进一组系统工程工具，可用于从RO系统以外的基于模型的设计和优化基于模型的设计和优化的详细的，空间分布的传输模型中产生减少订单模拟。加上该研究计划，一系列的教育和外展计划，专注于本科研究人员的支持以及与UCLA的独特学生交流计划。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子优点和更广泛的审查标准通过评估来评估的支持。