Dry Cooling Towers with Adiabatic Cooling

Through the combination of “pre-cooling + dry cooling”, the adiabatic dry cooling tower breaks through the efficiency bottleneck of the traditional dry cooling tower in the high temperature environment, while retaining the advantages of dry cooling system of water saving and low pollution, is the ideal choice for cooling system in high temperature and water-scarce areas (e.g., the Northwest Industrial Base, Desert Power Station, and large-scale data centers).

Working Principle

The system usually consists of two parts: adiabatic pre-cooling section and dry-cooling section, and the flow is as follows:

Adiabatic pre-cooling section: After the air enters the tower, it first flows through the adiabatic section (usually the spray area or wet film area), absorbing heat through the evaporation of a small amount of water (latent heat exchange), which reduces the temperature of the air (it can be reduced by 5-15 ℃, depending on the humidity of the environment), and at the same time the humidity of the air rises a little bit (but it's much lower than the saturated state of the wet-cooled tower).

Dry cooling section: After pre-cooling, the low-temperature air enters the dry cooler (usually a finned tube bundle), exchanges sensible heat with the high-temperature work material in the bundle (e.g., turbine exhaust steam, process cooling water) (the air is warmed up and the work material cooled down), and finally the work material is cooled down to the target temperature, and the air is discharged out of the tower through the blower.

Note: The adiabatic section is only activated when it is necessary to improve the efficiency (e.g. high temperature in summer), and can be shut down in low temperature season, only operating in pure dry cooling mode.

Compared to traditional dry cooling towers (pure sensible heat exchange) and wet cooling towers (pure evaporative cooling), the advantage is centered on the balance between efficiency and water saving:

Significant efficiency improvement in high temperature working condition:

The cooling efficiency of traditional dry cooling tower is greatly affected by the ambient temperature (the higher the air temperature, the smaller the heat transfer temperature difference, the lower the efficiency). For example, in summer, under the environment of 35℃, the efficiency of traditional dry cooling tower may be reduced by 30%-40%; while adiabatic pre-cooling can reduce the temperature of the air entering the dry cooling section to 25-30℃, so as to increase the heat transfer temperature difference and improve the cooling efficiency by 20%-30%, which ensures that the equipment (e.g. turbine) can still operate at full capacity in high temperature seasons.

Substantial water saving:

Wet cooling tower is cooled by a large amount of water evaporation (evaporation loss accounts for 70%-80% of the total water consumption), while the adiabatic section of adiabatic dry cooling tower requires only a small amount of water (water consumption is 10%-20% of the wet cooling tower), which is mainly used for pre-cooling rather than direct cooling of the workpiece, especially suitable for water-scarce areas (e.g., arid and semi-arid areas).

Avoid the disadvantages of wet cooling tower:

No wet cooling tower common “white mist” (water vapor condensation), water scaling (evaporation of circulating water leads to salt concentration), fan corrosion (high humidity environment) and other issues, lower maintenance costs, and the impact on the surrounding environment is small (no salt spray pollution).

Flexible adaptation to climate fluctuations:

Low-temperature season (such as winter): shut down the adiabatic section, run in pure dry-cooling mode, with low energy consumption (requiring only fan power);

High-temperature season: start the adiabatic section, and enhance the efficiency through a small amount of water replenishment, taking into account energy saving and stable operation.