Verdampfungsabscheidung

Verdampfungsabkühlung, commonly referred to as evaporative cooling, describes processes in which liquid water absorbs heat as it changes to vapor, thereby reducing the temperature of the surrounding air or a connected fluid. There are two main variants: direct evaporative cooling, where water evaporates into the air stream and the air is cooled and humidified; and indirect evaporative cooling, where a separate air loop is cooled by vaporization in a parallel process, allowing cooling without adding moisture to the cooled fluid.

The underlying principle is the latent heat of vaporization. The cooling effect equals the mass flow rate of evaporated water multiplied by the latent heat of vaporization. In practical terms, the maximum achievable temperature drop is linked to the difference between ambient dry-bulb temperature and ambient wet-bulb temperature; the drier the climate and the higher the airflow, the greater the potential cooling.

Applications span industrial process cooling, air-conditioning in hot climates, data centers, beverage and food processing, and power generation. Evaporative cooling is valued for relatively low energy consumption compared with mechanical refrigeration, though it consumes water and depends on climate and air quality.

Key factors influencing performance include humidity, airflow rate, and water quality. Potential limitations comprise increased ambient humidity (in direct systems), water usage, mineral scaling, and microbial growth. System design must balance cooling requirements with environmental and economic considerations, selecting direct or indirect approaches based on the acceptable level of humidity and the desired cooling power. See also evaporation, latent heat, and cooling towers.