Structural analysis and modeling of the commercial high performance composite flat sheet membranes for membrane distillation application

• Performances of commercial PTFE membranes were tested in DCMD configuration.
• Structural analysis and modeling of composite flat sheet membranes were conducted.
• Pore size, membrane thickness, and support layer structure could result in high flux.
• Temperature profiles across the tested membranes were computed by numerical analysis.
• Heat and mass transfer models were applied to know hydrodynamic conditions in module.

Direct contact membrane distillation (DCMD) module was operated with three flat sheet commercial membranes (PTFE/PP 1.0, PTFE/PP 0.45, and PTFE/PE 0.45) under various operating conditions. High flux was observed when the PTFE/PP 1.0 membrane was used and there was no membrane wetting when the feed concentration was up to 3.0 M as NaCl. In order to understand the relationship between membrane characteristics and operating conditions, the heat and mass transfer models were employed. Instrumental analyses (SEM, porosimetry and contact angle analysis) were carried out for the membrane characteristics and thermo-hydrodynamic parameters were calculated under given experimental conditions. High flux of PTFE/PP 1.0 membrane was thermodynamically possible because the flow in the feed side was not fully developed in the water channel of the module. The membrane characteristics, such as pore-size of active layer and porosity and thickness of support layer were also attributed to a high flux of PTFE/PP 1.0 membrane.