The present paper describes a study on the evaporation in a horizontal tube spray film evaporator. Single tubes

either electrically heated or steam heated

are used for the study. Two types of tube surface properties are considered

namely an electro-chemically etched porous tube surface and a smooth tube surface. The latter also serves as a reference De-ionized water is used as working fluid. Liquid feed rate

changes in the rate of heat flux

annealing treatment of the porous tubes and steam velocity in the tube are explored as operational variables. Compared with smooth tubes and pool boiling

porous tubes proved to give much better performance as such tubes tended to promote nucleate boiling of the film.