Seawater desalination using Dewvaporation technique: theoretical development and design evolution

Dewvaporation is a relatively new technique for seawater desalination. This technique uses air as a carrier gas to evaporate liquid from a saline solution, using cross flow configuration, at atmospheric pressure. A mathematical model was developed which related the production density (kg/h.m2) to the energy reuse factor. However, an approximate solution was established that could be used instead of the rigorous model to predict the energy reuse factor at a given production density. The cross flow was also modeled to evaluate the effect of such flow on the energy reuse factor. It was concluded that with passes greater than 15, the cross flow effect was negligible. Mylar, polypropylene, and twin wall plastic materials were used in studying the Dewvaporation technique. Different designs were constructed and tested which varied from counter flow to cross flow with spacers and without spacers on the evaporation and/or dewformation sides. Different attempts were made to maintain air streams balanced on either side of the heat transfer wall to obtain the maximum heat transfer area. The final design included cross flow with twin wall polypropylene plastics and spacers on the evaporation side only.