Impact of the feed concentration on the permeate flux of the solar vacuum membrane distillation equipped with helically coiled fibers

This paper presents the simulation of a solar membrane distillation equipped with helically coiled fibers. Due to this design of membrane distillation, a mutual dependence of the mass and heat transfer appears which complicates the solution of the system equations. After the establishment of these governing equations, a resolution was done with the finite element method. The results show that when feed salt concentration was varied between 10 to 300 g/1 a fall of the permeate flux of 12% was reported. This drop is du only to the reduction of the activity coefficient of 20% when the salt concentration increases from 10 to 300 g/1. This less drop of the permeate flux, for a high concentration of salt in feed solution, allows to use the membrane distillation process for water desalination instead of other distillation processes.