1. Principle : The air flows horizontally and the water falling downwards meets the air at different temperatures. Therefore the heat transfer is not always optimized.
Less cooling with more air
More cooling with less air
1. Principle Advantage : The air flows vertically upwards, counter current with the hot water falling downwards. The coolest water comes in contact with the coolest and most dry air, optimizing the heat transfer and obtaining the maximum performance.
2. Area : The area required is larger due to its constructional features like larger plenum chamber. Also the arrangement and material of the pack is different and requires a higher area.
More space required
20%–30% less space required
2. Area Advantage : The tower area required is comparatively much smaller. 30% more capacity tower can be installed. The air water contact is more due to the efficiency and arrangement of the fill pack. The plenum chamber area for hot air is smaller.
3. Structural Framework : In cross flow design, the base is lesser than the top dimension and the top is heavily loaded with water distribution arrangement and base frame for gear box & motor, which creates major instability of structural framework and results into collapsing of the whole Cooling Tower.
Unstable structure
Sturdy and stable structure
3. Structural Framework Advantage : In counter flow design, the complete structure is straight vertical and of the same size in the base and top, which gives very good structural stability. No chance of collapsing.
4. Air Flow : Since the air-water contact time is lesser, more air is required to effect heat transfer.
Lesser air-water contact time
More air-water contact time
4. Air Flow Advantage : Since the air-water contact time is higher, the quantity of air required is lesser.
5. Distribution System : The distribution is done through open trough systems on the fan deck, fitted with nozzles. Distribution may not be as uniform as the counter flow type and is easily attacked by algae and foreign particles causing problems like scaling and clogging of openings.
Not uniform & efficient distribution
Uniform & efficient distribution
5. Distribution System Advantage : The distribution is done through lateral pipes, fitted with the splash cum spray nozzles. Growth of algae is highly restricted as the lateral pipes are a closed unit and not located in direct sunlight.
6. Recirculation : Since the air intake area extends from the bottom to the deck level, the fume discharge is very close to the air intake area at the top. This creates the effect of recirculation wherein the discharged air re-enters the tower through the air intake at the top. This creates a significant reduction in performance.
Air recirculation is the problem
No chance of air recirculation
6. Recirculation Advantage : The problem of recirculation is completely eliminated as the air intake is at the bottom of the tower and the discharge is at much higher level. Further, the side walls of the tower are closed till the top of the air intake area.
7. Power Consumption and Pumping Head : The fan power consumption is higher as the air flow required is higher. The pumping head is also higher since the distribution is located at the fan deck level.
Higher power consumption
Lower power consumption
7. Power Consumption and Pumping Head Advantage : The fan power consumption is low as the required air quantity is comparatively lesser.
8. Maintenance : Maintenance for cross flow towers is time consuming and usually requires more skilled technicians on the job as the movement of material is more difficult.
Time consuming maintenance
Easy & quick maintenance
8. Maintenance Advantage : Maintenance for counter flow towers is much easier than cross flow towers. The simplicity of structure and comfortable sizing allow for quick and exhaustive maintenance.
