Hybrid dry coolers in cooling systems of high energy physics accelerators

Abstract

Wet water cooling towers in high energy physics facilities are state of the art. The advantages are robustness, effectiveness and cost-effectiveness. The return water temperature is lower than the air temperature due to cooling via evaporation. The disadvantages are the high water consumption, which becomes more costly in the future and the soiling of the heat exchangers. If the water source is taken from wells then the drawdown of the ground water level has to be taken into account.DESY intends to use hybrid dry coolers for the two future projects: the XFEL linac and the PETRA 3 synchrotron light source. A hybrid dry cooler is a combination of a dry air cooler during cold and moderate seasons and additional wet cooling during the hot summer season. The cooling surface is moistening by adding water to increase the cooling capability by a factor of 250%.By this the hybrid dry cooler saves a lot of water. The water consumption can be reduced by 80% compared to a wet cooling system. This contribution presents the consumption and the requirement of the make-up water and an estimate of the behaviour of the temperature control