Transport phenomena in membrane distillation

Abstract The characteristics of polytetrafluoroethylene membranes used in membrane distillation were measured. Flux was proportional to membrane porosity and inversely proportional to total diffusion length. Pore size became important when the surface tension of solutions was low. Both nonvolatile and volatile solutes were tested. For the latter case, a precise vapor-liquid equilibrium was necessary at low concentrations in order to assure correct behavior of the membrane. Transport equations were derived, and they coincided well with the experimental results. Also, a simple process design was performed using these equations. Some applications for the concentration of various feed solutions were examined.