Abstract: An air cooled condenser is provided which improves the heat transfer in the dephlegmator pipes and reduces the risk of condensate back-up. A condensate outlet extending from the bottom end to the top is arranged in selected dephlegmator pipes. The cross section and the geometry of the condensate outlet is configured in accordance with the respective cross section geometry and the dimensions of the dephlegmator pipe. The length of the condensate outlet is preferably between 100 mm and 500 mm. By separating the steam phase and the condensate phase at the entrance to the dephlegmator pipes, a mutual disadvantageous influence of the two phases on each other is prevented. In particular, the frictional forces between the steam and condensate can be appreciably reduced. As a result, the back-up velocity, that is, the steam inlet velocity at which the condensate starts to back up, is appreciably reduced. Depending on the length of the condensate outlets, a condensate back-up or swallowing can be prevented entirely.