3D Simulation of Water Desalination via Fibrous Distillation Membranes
Abstract
Direct contact membrane distillation (DCMD) is a promising desalination technique that can operate by using low-grade energy sources. In this study, we present a novel numerical framework in which a realistic model of the membrane's microstructure is generated and used to simulate the DCMD process. Virtual membranes resembling electrospun structures were generated by using the discrete element method (DEM). An in-house pore morphology method (PMM) code was employed to predict the shape and location of the air-water interface (AWI) on the cold and hot sides of the membrane and to evaluate its liquid entry pressure (LEP). The Navier-Stokes and species equations were then solved to predict the rate of vapor transport between these AWIs. Using such realistic geometries in the simulations allowed us to examine the counteracting impacts of membrane thickness and porosity on the LEP, air dissolution, and vapor transport. Our simulations also quantified the negative impact of temperature polarization on the freshwater production rate. The computational framework developed in this work enables the design and optimization of fibrous DCMD membranes for the highest transmembrane vapor flux while preventing membrane flooding.