Recent data on the direct transfer of hut acxns a liquid-liquid interface during vaporization and condensation ha= made it possible IO estimate the cost of producing potabic Hater by direct contact vapor recompression er7apomtion of sea water. The ad\antageJ of direct contact heat exhange are: (a) cIiminates cost& heat Zransfiz surfam. (b) prevents scale formation, (c) prewnts corrosion, (d) altows a bigb rate of hczst tmnsfer. (et) aftows close temperature approach. and (f) simpfifitts the evaprator design. These a&mtages show up as both capita1 and operating cost reductions compared to the costs of tbc standard sapor recompression process. As with the standard process added advantages could be obtained by combining the dim contact process with mutti-cffcct ctaporation or nuclear power production_ Tbc proportional savings should be about the SUIIC as xc now proposed for the standard procar When this process was first described at the First International Symposium on Desalination, (I) no cost figures were given because insufficient process data were available. Several rcn-nt publications, plus further work iti our laboratories at the University of British Columbia, Vancouver, Canada, have now made it possible to estimate the cost of desalination. by this technique. Reference wilI be made to these publications when each item of equipment is discussed. PROC?SS DESCRIPl-iON Referring to Fig. I, the process as it is now envisa&, will be described in broad terms. The details will be filled in when the cost estimate is considered. Sea water is preheated in a shell and tube heat exchanger to its boiling temperature. The main heat source for the preheater is the exhaust steam from the steam turbine which drives the compressor. The preheated sea water is sheared into fine droplets by hot immiscible heat exchange liquid in the throat of a venturi. As the water evaporates the heat exchange medium cools, and the fraction of the water evaporated is determined by the inlet temperature of the beat transfer medium-Tbe steam-liquid mixture enters the evaporator tangenti,ally and the steam disengages from the liquid. Sieve l Paper presented at the Second European Symposium on Fresh Water from the Sea, May 9-12, 1967, Athcas, Grm. European Federation of Cbanical Engineering.