Sopporting information for "Breaking the saturated vapor layer by a thin porous membrane"

The main idea of membrane distillation is to use a porous hydrophobic membrane as a barrier that isolates vapor from aqueous solutions. It is similar to the evaporation process from a free water surface but introduces solid-liquid interfaces and solid-vapor interfaces to the liquid-vapor interface. The transmembrane mass flux of a membrane distillation process is affected by the membrane intrinsic properties and temperature gradient across the membrane. It is interesting and important to know whether the evaporation process of membrane distillation is faster or slower than that of a free surface evaporation under the same conditions, and the capacity of the transmembrane mass flux of a membrane distillation process. In this work, a set of proof-of-principle experiments with various water surface/membrane interfacial conditions are performed. The effect and mechanism of membrane-induced evaporation are investigated. Moreover, a practical engineering model is proposed based on mathematical fitting and audacious simplification, which reflects the capacity of transmembrane flux.

Index for this document:

1. Evaporation test system and the core module

2. Theoretical estimation of mass transfer flux for free surface evaporation

3. Mass transfer behavior across porous membrane

4. Theoretical estimation of water surface coverage by fibers

5. Fitting equations for transmembrane flux capacity of MD

6. Reference collection