Design and field tests of a new membrane distillation desalination process

Abstract Membrane distillation is a process in which, for example water in a heated salt solution, evaporates through a porous membrane. The vapor condenses on a coolant surface at the other side of the membrane. The two liquid streams, the salt solution and the condensate, are separated by a nonwettable (hydrofobic), highly porous membrane. Surface tension forces withhold liquids from the pores and prevent contact of the two liquids. Theoretical research and verifying laboratory tests have resulted in a desalination module design. Trial production by injection-moulding technique has been performed. Produced modules have been subject to field tests. In this paper construction principles are shown and related to the theoretical and practical research. Test arrangements and conditions are described. Concluding features are presented. Performance data will be given as separate appendices.