During the heat treatment of rolled sheet metal, it is often necessary to quench the material. Besides the conventional technologies such as oilbath- or metalbath-quenching, the eco-friendlier gasflow-quenching has become popular. The main advantages of this latter technology are the perfect surface qualities, the flexibility (especially in multi-product plants) and its eco-friendliness. Within this thesis, the behaviors of two special nozzle systems for gasjet-coolers were analyzed. One design was based on an array of round jet nozzles, the other one was a special development of a slot-nozzle array which should guarantee low pre-cooling while entering the jetcooler. Parameters such as the nozzle stripe distance, the nozzle exit velocity or the inert gas-mixture (Hydrogen / Nitrogen) influence on the cooling characteristics were studied on an industrial scale device. Besides these experimental studies, theoretical and computational tools including CFD-Analysis and similarity models were used and validated. A special goal of the CFD-Analysis was to become a better understanding of the cooling characteristics of the round-nozzle-array. A benchmark of the different arrays should assist design engineers while choosing nozzle geometries for special applications.