Abstract
Designing a filtration medium requires balancing high filtration efficiency and low energy requirement (i.e., low pressure drop). Unlike fibrous and random porous membranes, the pore architecture of isoporous membranes is deterministic, can be precisely controlled as per design, and is characterized by a periodic array of parallel pores with narrow pore size distribution. Although isoporous membrane allows for a deterministic approach towards targeted design and optimization of multiscale pore architecture, it is challenging to obtaining free-standing and residual-layer-free isoporous membrane with submicron pores. As such, there exist an under-explored design space of multiscale pore architecture for the concurrent optimization of pressure drop and filtration efficiency. Thus, the goal of this thesis is to develop physics-based computational design models, validated with experiments, to aid in the deterministic approach of designing and optimizing the pore architecture of single and multilayer isoporous membrane to obtain low pressure drop and high filtration efficiency. Generally, artificial neural networks (ANNs) were trained with experimentally validated physics-based simulations where the incompressible, isothermal, laminar flow was solved. In this work, both single layer and multilayer systems were investigated. This work has enabled the accelerated exploration of the design space of isoporous membrane through a concurrent optimization of low pressure drop and high filtration efficiency. Major contributions of this thesis include 1) the incorporation of fabrication variabilities in the computation models assisted by artificial neural networks; in contrast to conventional simulation efforts in which a single pressure drop value is obtained, here predictive pressure drop range was obtained for a given set of pore geometries. Furthermore, through sensitivity analysis, pressure drop across single layer membrane was found to have the highest degree of dependency on pore channel length. The results of this study are important for application-specific tailor-design of isoporous membrane and can significantly reduce prototyping costs associated with the fabrication processes. 2) The quantification of pressure drop reduction and the visualization of the more gradual change in airflow direction due to the introduction of the microscale spacers between two membranes. Due to a more gradual change in airflow direction, there is a reduction in kinetic energy loss and hence, reduction in the pressure drop which was observed experimentally and in the simulations. In contrast to a bilayer system where the top and bottom membranes are directly stacked on each other, the system with the microscale spacers maintains the same filtration efficiency while enabling pressure drop reduction. Hence, this result is important for the co-optimization of pressure drop and filtration efficiency of multilayer isoporous membranes. 3) The co-optimization of pressure drop and filtration efficiency for a single layer isoporous membrane resulted in a set of optimal designs with maximized filtration efficiency at varying pressure drop. Depending on the pressure drop or filtration efficiency requirement, an optimal design can be selected and hence, time required for obtaining an optimal membrane design is reduced.