The air flow simulation is performed with KULI. KULI is a software package for one-dimensional analysis and simulation of air flow and heat transfer. It offers the option of comparing different concepts with each other in a short period of time. In this case, it is possible to compare different fan arrangements, cooler variants or combination options. For certain sections, such as in the area of the frames of heat exchangers, the accuracy concerning flow distribution and local heat transfer can be improved even further by modeling with CFD section by section and transferring the speed distribution into the 1D model.