Method and apparatus for evaporating a fluid

The inventive method for evaporating a predeterminable volume of a fluid comprising the steps of: a) successively adding at least one first and at least one different from the first partial volume of the second partial volume of the predeterminable volume in a feed line (3); b) so that a vapor film between the partial volume and a wall of the supply line (3) forms at least partially evaporating the partial volumes; c) guiding the partial volumes through the feed line (3) to an evaporator surface (5); and d) applying the partial volumes to a region of the evaporator surface (5), whose position is varied as a function of the mass of the corresponding partial volume. The inventive method and the inventive apparatus (1) allow in an advantageous manner as effective as possible the evaporation of a fluid, in particular of urea-water solution. that the largest possible portion of the evaporator surface (5) is used by the mass-dependent distribution of the impact on the evaporator surface (5) is achieved. For this purpose is operated advantageously in the range of the supply line (3) a heating strategy, which ensures that on addition of the individual partial volumes enters each of the Leidenfrost effect. Hereby may be achieved the most uniform possible distribution by a suitable design of the geometry of the evaporator channel (4).