Märkäjäähdytys

Märkäjäähdytys, also known as wet cooling, is a heat transfer method widely used in industrial refrigeration, air conditioning, and power generation to remove heat from systems by evaporating water. The process involves a coolant—typically water—cooled via evaporative heat exchange, which lowers the temperature of the fluid passing through the heat exchanger. The cooled fluid is then circulated through the system that requires temperature control, while the evaporated water is either vented to the atmosphere or condensed for reuse.

In a wet cooling tower, incoming warm water is distributed across a packed bed or spray system. Air drawn or forced across the tower passes through the water, promoting evaporation. The partial evaporation removes latent heat, resulting in cooler return water. The cooled water is returned to the plant or served as chilled water in HVAC applications. Because the heat is removed via evaporation, wet cooling towers can achieve lower outlet temperatures than dry coolers of the same size.

Advantages of märkäjäähdytys include higher cooling efficiency, lower operating temperatures, and the ability to use lower-grade water inputs. The primary disadvantages are higher water consumption, potential for scaling and corrosion, and the need for maintenance to control biological growth. In climates with high relative humidity, the evaporative efficiency decreases, making dry cooling or hybrid solutions preferable.

Historically, wet cooling has been employed since the early twentieth century in air conditioning and gas cooling. Contemporary designs incorporate water‑recycling systems and advanced materials to minimize water losses and extend tower life. The choice between wet and dry cooling depends on environmental conditions, energy costs, and regulatory requirements.