Types of Cooling Circuit
Cooling towers can be classified based on different aspects:
- Material used
- Water flow or capacity
- Quality of the water to cool down
The basic cooling tower classification tends to be based on the following criteria:
- Natural or mechanical draft
- Induced or forced draft
- Open, closed or hybrid cooling circuit
The cooling circuit type determines the exact heat exchange process.
Natural or mechanical draft
Natural draft cooling towers make use of the chimney operation of the cooling tower. The air flow is caused by the temperature difference between the air inside and outside the cooling tower.
The fans used in mechanical draft cooling towers cause the air flow. All cooling towers distributed by Almeco have mechanical draft. For natural draft cooling towers Almeco only carries out the maintenance. We also supply spare parts for this cooling tower type.
Induced or forced draft
Induced draft implies an inlet fan placed on top of the cooling tower and the creation of low pressure. Axial fans are always used for this type of draft.
Forced draft means an exhaust fan placed at the base of the cooling tower which then causes overpressure. Both axial and centrifugal fans can be used.
Almeco’s cooling tower range contains all different types.
Induced draft - Axial fan | |
Advantages | Disadvantages |
Low absorbed capacity | Higher noise level |
Small foot print (requiring little space) | A more difficult maintenance |
Humid air stream drive | |
Forced draft - Axial fan | |
Advantages | Disadvantages |
Low absorbed capacity | Higher noise level |
Easy maintenance | |
Dry air stream drive | |
Forced draft - Centrifugal fan | |
Advantages | Disadvantages |
Low noise level | Higher absorbed capacity |
Easy maintenance | |
Dry air stream drive | |
Open, closed or hybrid cooling circuit
Almeco’s cooling tower range includes open, closed and hybrid circuit cooling towers.
Open
In open circuit cooling towers, there is a direct contact between the water to cool down and the air.
More about the open circuit cooling tower operation.
Closed
There is no direct contact between the water to cool down and the air inside closed circuit cooling towers, but an additional heat exchanger is however used. Cooling towers with piping and plate heat exchanger also exist.
More about the closed circuit cooling tower operation with plate heat exchanger.
Hybrid
For hybrid cooling towers (both open and closed cooling circuits) an additional cooling battery is installed in the outgoing air stream. This will allow a water saving operation due to partial or entire dry cooling.
More about the hybrid circuit cooling tower operation.