Cooling system

The cooling unit (1) has several box-type coolers (2-5) containing radial ventilators having impellers, where the ventilators are supported in the center of a rear wall of the cooling unit. The impellers have blower blades, a cover disc and a rear wall and suck fresh air in through a nozzle in a front wall and blow out cool air. The center line of the impeller's blower blades is spaced in front of the center line of the cooling unit. The ratio of the distance from the nozzle inlet to the middle of the impeller's blower blades, along the rotation axis, to the diameter of the impeller is between 0.2 and 0.36.