How Does A Dry Cooler Work in Turbine Applications?
A dry cooler works as an air-cooled heat exchanger that removes heat from turbine auxiliary circuits-such as lube oil, hydraulic oil, cooling water, or generator cooling loops-by transferring heat to the surrounding air. It provides reliable cooling without the use of water.
1. Hot Fluid from the Turbine System Enters the Coils
The circuit (typically lube oil or closed-loop cooling water) absorbs heat from the turbine bearings, gearbox, generator, or control systems.
This hot fluid is pumped into the finned-tube coils of the dry cooler.
2. Finned Tubes Increase Heat Transfer Area
The coils are made of copper or stainless-steel tubes with aluminum fins.
The fins greatly increase the surface area, allowing heat to transfer quickly from the fluid to the airflow.
3. Fans Force Ambient Air Across the Coil Surface
Axial fans draw or push ambient air across the fins.
As the air contacts the heated finned surfaces, heat is transferred from the fluid to the air.
4. Heat Is Rejected Directly to the Atmosphere
The heated air is discharged upwards or sideways, depending on the cooler design.
Because no water is used, all heat is removed through dry (air-only) cooling.
5. The Cooled Fluid Returns to the Turbine System
After passing through the coils, the cooled oil or water returns to the turbine or auxiliary equipment, maintaining safe operating temperatures.
6. Temperature Control via Fan Speed or Staging
To match variable turbine loads and ambient temperatures, dry coolers often use:
VFD-controlled fans (variable speed)
Fan staging (on/off control)
Bypass valves for fluid-side control
This ensures consistent outlet temperature and energy-efficient operation.
7. Works in Both Hot and Cold Climates
In hot ambient conditions, fans run at higher speed to maintain cooling capacity.
In cold climates, fan speed reduces or fans stop to avoid overcooling.
