To deliver an airflow through a heat exchanger, a sufficient pressure differential is needed to overcome the flow resistance of the exchanger. Normally, the delivered air flows at high speed from the exit side of the fan and is dissipated into the environment. Dissipation means that the kinetic energy of the flow is converted into heat that is no longer technically utilised. The AxiTop diffuser is designed to decelerate the flow, allowing a large proportion of the dynamic kinetic energy to be converted into static pressure. This reverse-conversion boosts the pressure increase of the impeller. If all components are aerodynamically optimised, this allows efficiency to be significantly enhanced, making it possible to reduce the fan speed and thus noise emissions.