Abstract: The invention relates to a process and device for cooling and cleaning surface elements of a plate heat exchanger to recover heat from outgoing air by spraying water into a stream of outgoing air. Wetting nozzles are used to spray a fine stream of processed water into the outgoing airflow channels of the plate heat exchanger at equal time intervals. This entails no trickling off of sprayed water and the surface elements swept by outgoing air remain moist until the next spraying. Scouring nozzles are used at the end of a daily cooling period to spray a stream of tap water into the outgoing airflow channels. The wetting device comprises a back-and-forth nozzle rail with wetting and scouring nozzles, the axes of which are preferably located in one plane.