Research perspective of membrane distillation: multi-scale and multi-physics phenomena

Abstract

This paper introduces an overview of the principles and discusses current stages and future directions of theoretical and simulation research on membrane distillation (MD). MD as an absolutely two-interface phenomenon consists of microscopic molecular motion, mesoscopic transport, and macroscopic fluid flow. Momentum, heat, and/or mass transfer are dominant in feed, membrane, and distillate regions. We discuss critical issues of MD in various aspects, as follows. Fundamental flaws of using one interface (theoretically induced) are discussed in depth. A general theoretical approach is proposed in terms of a general flux equation developed from statistical physics, and distillate flux is mathematically redefined for hollow fiber MD. Simulation tricks to compare the performances of various membranes and operating conditions are proposed using open source package of OpenFOAM. Big data analysis using a self-organizing map provides specific information regarding key operational parameters for efficient, optimal control of MD plants.